Joining method, device created thereby, surface activating device and joining device provided therewith

The present invention relates to a technique for laminating a plurality of objects to be joined, such as a wafer, by hydrophilization treatment with plasma.

Conventionally, Si and glass, SiO₂Or SiO₂In wafer bonding between wafers, a method is known in which the surface is hydrophilized using oxygen plasma, hydrogen-bonded, and bonded firmly by annealing. In the conventional method, the surface is cleaned by a wet treatment, so that the surface is carried in the atmosphere and hydrophilized by oxygen plasma in a vacuum chamber. It is also taken out into the atmosphere and hydrogen-bonded by laminating the wafers together, but the strength is as weak as 3 MPa as shown in FIG. Therefore, although it is heated, it only rises to about 5 MPa at about 400 ° C, and after all, diffusion bonding is performed at a high temperature of 1100 ° C to increase the strength. That is, the hydrogen bond by oxygen plasma is only a temporary bond.

Further, in the method shown in Patent Document 1, an example is shown in which metals are etched with an Ar ion beam and bonded at room temperature in a state where the surface is activated. However, in this method, organic substances and oxide films on the surface are removed to create an electrically activated surface of the metal, which is joined by atomic force. Therefore, Si, ceramics, which are semiconductors, and glass and SiO, which are oxides in particular, are used.₂Cannot be firmly joined.

Further, as shown in Patent Document 2, when the objects to be bonded are arranged facing each other and subjected to plasma treatment, either side of the objects to be bonded always becomes a plasma electrode, and the reaction gas ions are accelerated and collide with each other. Suitable for physical etching to remove, but too strong for chemical treatment such as OH groups.

In addition, a method using atmospheric pressure plasma can be considered, but since the atmosphere is in the atmosphere, the ions are not accelerated, so the ion collision force is weak and the surface can be activated by chemical treatment, but the organic layer in the initial stage. Since it is not possible to clean and remove such substances by physical etching, the bond contains an organic layer and its strength is weak.

<patcit num="1"><text>JP-A-54-124853</text></patcit><patcit num="2"><text>Japanese Unexamined Patent Publication No. 2003-318217</text></patcit>

<p> In the conventional method, no matter how much the object to be bonded is washed in advance, it is exposed to the atmosphere, so at least some organic substances and other deposits are reattached to the surface, and the hydrophilization treatment by oxygen plasma is only on the surface. OH groups are created by surface modification of organic substances, and hydrogen bonds are formed by the OH groups on both surfaces. In this case, the strength does not increase due to the presence of the organic substance layer at the low temperature annealing before diffusion. Therefore, it diffuses at a high temperature of 1100 ° C, and the organic layer is also mixed with the base material, and there is no choice but to increase the strength by incorporating it into the crystal.</p><p> Further, in the method shown in Patent Document 1, since organic substances and oxide films on the surface are removed to create an electrically activated surface of a metal or a semiconductor and bonded by an atomic force, Si semiconductors other than metals and particularly oxides are used. Glass and SiO₂Cannot be firmly joined.</p><p> Therefore, an object of the present invention is an ion collision after a physical treatment step of physically treating both objects to be bonded with an energy wave such as an atomic beam, an ion beam or plasma in a method of bonding the objects to be bonded with a solid layer at a low temperature. It is an object of the present invention to provide a method and an apparatus for joining both objects to be joined by performing a chemical treatment step of chemically treating with a weak plasma.</p><p> Further, in a method in which the surface of an object to be bonded is surface-activated by an OH group or the like to bring both bonding surfaces into close contact with each other, in the conventional method, the surface is hydrophilized with oxygen plasma and the wafers are bonded together in the atmosphere. As a result, hydrogen bonds are formed, but the plasma treatment is too strong by the usual method, and the OH groups cannot be neatly arranged on the bonding surface, resulting in hollowing out and chipping. In addition, the surface of the object to be joined is roughened, resulting in gaps that cannot be joined. Therefore, as shown in Fig. 9, the strength is as weak as 3 MPa. Even when heated, it only rises to about 4 MPa at about 100 ° C, and the strength is increased at high temperatures of 400 ° C or higher. In the conventional method, high-temperature heating is inevitably required for strong bonding, and there is a problem in bonding devices that cannot withstand the strain and high temperature due to the difference in thermal expansion between different materials. The tensile strength shown in FIG. 9 varies depending on the measurement method, but here, 9 MPa is assumed to be sufficient strength and 8 MPa is assumed to be a usable level.</p><p> In addition, in the method using atmospheric pressure plasma, since the atmosphere is in the atmosphere, the ions are not accelerated, so the ion collision force is weak and an adhesive layer can be attached, but the organic layer in the initial stage is washed and removed by etching. Since it cannot be formed, the bond contains an organic layer, and the strength is weakened.</p><p> Further, as shown in Patent Document 2, when the objects to be bonded are arranged facing each other and subjected to plasma treatment, either side of the objects to be bonded always becomes a plasma electrode, and the reaction gas ions are accelerated and collide with each other. Suitable for physical etching to remove, but too strong for surface activation by chemical treatment such as OH groups. As described above, there is no method that satisfies both cleaning and adsorption.</p>

<p> The surface activation treatment by an energy wave refers to a treatment in which the bonding interface is activated by an atomic beam, an ion beam, or plasma to facilitate bonding. The joining principle by surface activation can be thought of as follows. In a substance such as a metal, the organic matter on the surface and the deposits such as an oxide film are etched and removed to form a dangling bond of an active metal atom on the surface, whereby the other dangling bonds are bonded to each other. Also, Si or glass, SiO₂In the case of oxides containing ceramics, the bonding surface is activated by OH groups by hydrophilic treatment with oxygen or nitrogen plasma, and the other OH groups are bonded to each other. In the case of plasma, in addition to decompression plasma, there is also atmospheric pressure plasma that can be processed under atmospheric pressure, which can be easily handled.</p><p> According to these bonding principles, the present invention is to increase the bonding strength at a lower temperature by bonding after surface activation by an energy wave. The feature of the present invention is that in the surface activation step, the treatment is continuously switched between a treatment in which the physical treatment by ion collision is enhanced and a treatment in which the chemical treatment is promoted in a state where the ion collision force is weakened and the number of radicals is increased. The purpose is to efficiently promote the adhesion of OH radicals and perform a hydrophilization treatment.</p><p> The physical treatment refers to a phenomenon in which the surface layer is etched, a phenomenon in which ion molecules collide with the surface layer to replace the surface molecules, and a phenomenon in which the ion molecules adhere to the surface. For example, it is an act of Ar ions etching the adhesion layer by Ar plasma, and also indicates that oxygen ions replace or adhere to the surface layer in oxygen plasma. Chemical treatment refers to a phenomenon in which the surface layer is treated by a chemical reaction with active radicals or active ions with weakened ion collision force.</p><p> For example, if oxygen plasma treatment is performed after Ar plasma treatment, etching is performed by Ar having a large primitive weight, and OH groups are attached by a chemical reaction with active oxygen by oxygen plasma. Further, even when the same oxygen plasma is used, impurities are removed by etching in the initial treatment for increasing the ion collision force, and at the same time, oxygen is attached by replacing the surface layer by ion collision to create a source to which OH groups can be attached. The OH group is still attached to some extent as it is, but the ion collision force is too strong and it peels off at some point. Next, the adhesion of OH groups is efficiently promoted by weakening the ion collision force and performing chemical treatment with a large amount of active ions and radicals having a weak collision force.</p><p> Based on this principle, both the joining method and the surface activating device according to the present invention for solving the above problems will be collectively described below.</p><p> In order to solve the above problems, the bonding method according to the present invention is a bonding method in which the bonding surfaces of the objects to be bonded are hydrophilized with plasma and bonded in a solid layer within 500 ° C. After the physical treatment step of physically treating with an energy wave having a strong ion collision force such as an atomic beam, an ion beam or a plasma, a chemical treatment step of chemically treating with a plasma having a weak ion collision force is performed to join both objects to be joined. It comprises a joining method (claim 1).</p><p> Further, the surface activating device according to the present invention is an energy wave irradiating means and / or a plasma irradiating means in a device in which the bonding surfaces of objects to be bonded are hydrophilized with plasma and bonded in a solid layer within 500 ° C. After the physical treatment step of physically treating both objects to be joined by an energy wave having a strong ion collision force such as an atomic beam, an ion beam or a plasma, a chemical treatment step of chemically treating the two objects with a plasma having a weak ion collision force is performed. It comprises a surface activator (claim 20).</p><p> By etching the surface with an energy wave, removing deposits, and hydrophilizing the new surface of the base material with a reaction gas such as oxygen or nitrogen by chemical treatment with plasma, hydrophilicity without an organic layer is involved. Can be processed. Therefore, since there is no peeling from the organic layer, which has weak strength after bonding and weakness after annealing due to hydrogen bonding force, H after hydrogen bonding is not performed even if it is not diffused.₂Sufficient bonding strength can be obtained only by annealing at a low temperature to release 0.</p><p> The amount of etching by the energy wave is preferably 1 nm or more. Even after wet cleaning, the deposits existing on the surface of the object to be joined adhere to 1 nm or more in a few seconds when exposed to the atmosphere, so it is effective to etch at least 1 nm or more.</p><p> Further, the present invention comprises the joining method according to claim 1, wherein the energy irradiation means in the physical processing step is plasma (claim 2).</p><p> The present invention also comprises the surface activating device according to claim 20, wherein the energy irradiation means in the physical treatment step is plasma (claim 21).</p><p> If the energy wave irradiation means is plasma, it is a means that is easier and less costly than other energy waves, and since the same means as in the chemical treatment process can be used, it is simple and can be done in one chamber.</p><p> The present invention also comprises the joining method according to claim 1 or 2, wherein the reaction gas in the chemical treatment step is oxygen or nitrogen (claim 3).</p><p> The present invention also comprises the surface activating device according to Item 20 or 21, wherein the reaction gas in the chemical treatment step is oxygen or nitrogen (Claim 22).</p><p> As the plasma used in the chemical treatment step, it is preferable to use oxygen because OH groups are easily attached. Further, even if nitrogen is used, an OH group can be similarly attached.</p><p> The present invention also comprises the joining method according to any one of claims 1 to 3, wherein the chemical treatment step is performed after the physical treatment step and then the vacuum is drawn (claim 4).</p><p> The present invention also comprises the surface activating device according to any one of claims 20 to 22, wherein the chemical treatment step is performed after the physical treatment step and then evacuated (claim 23).</p><p> In the state of being etched by Ar plasma, Ar atoms may be attached to the surface or may be driven into the surface layer. Also, CF₄Even when etching with plasma, F (fluorine) may adhere to the surface layer. After etching, Ar and F (fluorine) are released by further evacuating from the plasma generation region, and can be removed by evacuating, which is more effective. Moreover, the effect is even higher if it is heated to about 100 ° C at the same time. After evacuating, the reaction gas may be filled and the degree of vacuum may be raised again to generate plasma.</p><p> Further, the present invention relates to H during or after chemical treatment.₂The joining method according to any one of claims 1 to 4 is used for joining after mixing a gas containing an O, H, or OH group (claim 5).</p><p> Further, the present invention comprises a water gas generating means, and H₂The surface activator according to any one of Items 20 to 23, which is joined after mixing a gas containing an O or H or OH group (claim 24).</p><p> H₂A gas containing O, H, or OH groups is also called water gas. Normally, it is treated with oxygen plasma, and when it is transported in the atmosphere, moisture is contained in the atmosphere, so OH groups are naturally formed, but it should be exposed to the atmosphere in a vacuum to avoid adhesion of impurities and organic substances. If the process proceeds to the bonding without any treatment, the water content may be insufficient and sufficient OH groups may not be formed. Therefore, during oxygen plasma treatment or before joining after treatment, H₂It is effective to supply a gas containing O, H, or OH groups. Although water gas can be supplied as it is, it is more effective because it is activated by mixing water gas with oxygen or by continuously plasma-treating water gas as a reaction gas after oxygen plasma treatment.</p><p> Further, in the present invention, the reaction gas in the physical treatment step is a gas different from that in the chemical treatment step, and Ar or CF₄The joining method according to any one of claims 1 to 5 is used (claim 6).</p><p> Further, in the present invention, the reaction gas in the physical treatment step is a gas different from that in the chemical treatment step, and Ar or CF₄25. The surface activating device according to any one of claims 20 to 24 (claim 25).</p><p> If Ar, which is inert as the plasma used in the physical treatment process, is used, it does not affect any material and has a large atomic weight, so that the ion collision force is high and suitable. In addition, if oxygen or nitrogen is used in the chemical treatment process, the primordial weight of Ar in the physical treatment process is larger, so the ion collision force becomes higher, and the ion collision force is weakened in the chemical treatment process to promote the chemical treatment. become. In addition, at least one of the objects to be joined is Si, SiO.₂, Glass, CF as plasma reaction gas in the case of ceramic₄Can be used to efficiently etch the material, making it suitable for physical processing processes.</p><p> The present invention also comprises the joining method according to any one of Items 1 to 6, wherein the physical treatment step and the chemical treatment step are carried out without being exposed to the atmosphere (claim 7).</p><p> The present invention also comprises the surface activating device according to any one of Items 20 to 25, wherein the physical treatment step and the chemical treatment step are performed without exposure to the atmosphere (claim 26).</p><p> By etching the surface with energy waves, removing deposits, and hydrophilizing treatment with plasma without exposing to the atmosphere with the new surface of the base material exposed, it does not come into contact with the atmosphere and reattach. Hydrophilization treatment without an organic layer can be performed.</p><p> As shown in FIG. 9, in the conventional method of bonding by oxygen plasma treatment after atmospheric transfer, the bonding strength at room temperature is 3 MPa, which is 5 MPa at 400 ° C and 10 MPa at 1100 ° C. This is because organic matter adheres during air transportation and includes a joint surface containing an organic matter layer, so the joint strength does not increase, and the strength increases only by diffusion. However, after plasma treatment by Ar etching in vacuum, the one that was continuously hydrophilized by oxygen plasma without being exposed to the atmosphere has a bonding strength of 6 MPa even at room temperature, 8 MPa at 200 ° C and 9 MPa at 400 ° C. It was possible to obtain sufficient bonding strength equivalent to that of diffusion bonding at 1100 ° C. Although 200 ° C is sufficient bonding strength, 400 ° C is more preferable. By the way, when the bonding strength in high vacuum after Ar ion beam treatment is measured, it can be seen that the bonding strength does not increase more than the conventional method even if it is heated at 5 MPa and 400 ° C at room temperature.</p><p> In addition, the energy wave is plasma, and both objects to be joined are placed facing each other in the same vacuum chamber, and after the physical treatment step by plasma, the chemical treatment step by plasma is continuously performed in the same chamber. It may be a device.</p><p> It is possible to separate and handle the chambers for dry cleaning with energy waves and oxygen plasma treatment, but after Ar plasma etching with Ar gas in the same chamber, it is replaced with oxygen gas and continuously hydrophilized. By doing so, the possibility of reattachment is eliminated, and since only one chamber is required, it leads to compactness and cost reduction. Further, if the energy wave is plasma, the same device as the hydrophilization treatment of oxygen plasma can be used as it is and is efficient. Moreover, it is not necessary to draw a high vacuum as compared with other energy waves.</p><p> Further, the plasma may be a joining method using an alternating power source and a surface activating device. By using an alternating power supply, positive ions and negative electrons alternately hit the surface of the object to be bonded, so that they are neutralized and there is less damage such as charge-up compared to other energy waves. Therefore, it is suitable for semiconductors and various devices.</p><p> The present invention also comprises the bonding method according to any one of claims 2 to 5, further comprising a plasma processing means for switching the ion collision force, weakening the ion collision force in the latter half of the plasma treatment, and promoting the chemical treatment (claim 8). ).</p><p> The present invention also comprises the surface activating device according to any one of claims 21 to 24, which comprises a plasma processing means for switching the ion collision force, weakens the ion collision force in the latter half of the plasma treatment, and promotes the chemical treatment (claim). Item 27).</p><p> In the process of hydrophilization by plasma treatment, the ion collision force is weakened in the latter half of the plasma treatment to perform plasma treatment. In normal plasma treatment, impurities are removed by physical treatment, and OH groups are attached to the surface by chemical treatment. Although they are lined up or replaced with nitrogen, etc., even if the surface is chemically treated, it is removed because the ion collision force is strong, and it is difficult to uniformly chemically treat the surface.</p><p> Therefore, in the latter half of the plasma treatment, since there are many ions and radicals that are not accelerated by the plasma treatment by weakening the ion collision force, the chemical reaction is promoted and the bonding surface is uniformly chemically treated to perform the surface activation treatment. Can be done. Therefore, the bonding strength can be increased at a low temperature. The low temperature is preferable because the conventional method requires 400 ° C or higher, and the bonding can be performed within 400 ° C, which is lower than that.</p><p> The joining method and the surface activating device may be used in which the joining temperature is 200 ° C. or lower. As shown in FIG. 9, joining at 200 ° C is possible, which is more preferable. Further, the latter half of the plasma treatment is not limited to half in time and has a meaning not related to time. Further, although the first half and the second half of the plasma treatment may be spaced apart, continuous plasma treatment is preferable in terms of chemical treatment. In particular, in claims 8 and 27 and earlier, the physical treatment is etching for removing impurities as a pretreatment for adhering OH groups, but in claims 8 and 27, in the step of adhering OH groups. By switching the ion collision force, oxygen is attached by physical treatment and OH group adhesion is promoted by chemical treatment, and the purpose is to efficiently attach OH groups.</p><p> Further, in the present invention, the plasma processing means for switching the ion collision force is decompression plasma, and the plasma electrodes are arranged so as to be switchable between the object holding electrode and the facing electrode, and the object holding electrode is formed. The joining method according to claim 8, wherein a power source is applied to the electrode side to perform plasma treatment, and then a power source is applied to the facing electrode side to weaken the ion collision force and perform plasma treatment to promote chemical treatment (the bonding method according to claim 8). Claim 9).</p><p> Further, in the present invention, the plasma processing means for switching the ion collision force is decompression plasma, and the plasma electrodes are arranged so as to be switchable between the object holding electrode and the facing electrode, and the object holding electrode is formed. Item 27. The surface activation device according to Item 27, wherein a power source is applied to the electrode side to perform plasma treatment, and then a power source is applied to the facing electrode side to weaken the ion collision force and perform plasma treatment to promote chemical treatment. (Claim 28).</p><p> On the plasma electrode side, ions are accelerated and collide because an electric field is created, so the ion collision force increases, and the ions do not accelerate and collide with the electrode, so the ion collision force is low, but there are many unaccelerated ions and radicals. Therefore, the chemical reaction is promoted. The plasma electrode is arranged so as to be switchable between the object holding electrode and the facing electrode, and a power source is applied to the object holding electrode side to perform plasma treatment, and then the power source is switched to the facing electrode side to ionize. By performing plasma treatment with weak collision force, impurities are removed, and since there are many ions and radicals that are not accelerated by weakening the ion collision force, the chemical reaction is promoted and the surface is uniformly activated on the bonded surface. be able to. Therefore, the bonding strength can be increased at a low temperature.</p><p> FIG. 14 shows the difference in temperature and bonding strength between the case where the plasma power supply is applied only to the conventional object holding electrode and the case where the object holding electrode and the facing electrode are switched. In the conventional method, 400 ° C was required to obtain sufficient strength, but in this method, sufficient bonding strength could be obtained within 200 ° C from room temperature, which is within 400 ° C. Further, the counter electrode may be arranged to face each other like a parallel plate type, but the same effect can be obtained by arranging the counter electrode around a circumference other than the electrode. Further, in order to avoid reattachment of the electrode material due to sputter etching, the side surface is preferable to the facing surface. The facing electrode in the text also includes arranging the electrodes in the surrounding parts.</p><p> Further, in the present invention, the plasma processing means for switching the ion collision force is decompression plasma, which comprises an RF plasma power source in which Vdc can be adjusted. In the latter half of the plasma processing, the Vdc value is changed to weaken the ion collision force, and chemistry. The joining method according to claim 8, wherein a plasma treatment for promoting the treatment is performed (claim 10).</p><p> Further, in the present invention, the plasma processing means for switching the ion collision force is decompression plasma, which comprises an RF plasma power source in which Vdc can be adjusted. In the latter half of the plasma processing, the Vdc value is changed to weaken the ion collision force, and chemicals are used. The surface activator according to claim 27, which performs plasma treatment to promote the treatment (claim 29).</p><p> An electric field is created on the plasma electrode side, but the speed at which ions collide changes depending on the Vdc value. As shown in Fig. 10, for example, + oxygen ions are accelerated as the Vdc value is-and the ion collision force increases, and as it approaches 0, the velocity slows down, the ion collision force decreases, and unaccelerated ions and radicals. Since there are many, the chemical reaction is promoted. By increasing the Vdc value to the-side and performing plasma treatment, and then moving the Vdc value closer to 0 and performing an adsorption step, impurities are removed by performing plasma treatment with weakened ion collision force in the latter half of the plasma treatment. Moreover, since there are many ions and radicals that are not accelerated by weakening the ion collision force, the chemical reaction is promoted and the surface can be uniformly activated on the bonded surface. Therefore, the bonding strength can be increased at a low temperature. As for the joining result, the same result as in FIG. 14 was obtained.</p><p> Further, in the present invention, the plasma processing means for switching the ion collision force is decompression plasma, which comprises a pulse wave plasma power source whose pulse width can be adjusted, and the pulse width is changed in the latter half of the plasma processing to weaken the ion collision force. The joining method according to claim 8, wherein the plasma treatment for promoting the chemical treatment is performed (claim 11).</p><p> Further, in the present invention, the plasma processing means for switching the ion collision force is decompression plasma, which comprises a pulse wave plasma power source whose pulse width can be adjusted, and the pulse width is changed in the latter half of the plasma processing to weaken the ion collision force. The surface activating device according to claim 27, which performs plasma treatment for promoting chemical treatment (claim 30).</p><p> An electric field is created on the plasma electrode side, but as shown in Fig. 11, by adjusting the pulse width, the interval between the time when the + ions collide-the time of the electric field and the time when the collision weakens-the time when the electric field is weak is adjusted. be able to. -Increasing the time of the electric field strengthens the collision of + ions, and decreasing the time of the-electric field weakens the collision of + ions.</p><p> For example, + oxygen ions-accelerate as the time of the electric field increases and the ion collision force increases, -the speed decreases as the time of the electric field decreases, the ion collision force decreases, and there are many unaccelerated ions and radicals. Its presence facilitates the chemical reaction. By adjusting the pulse width-increasing the time of the electric field to perform plasma treatment, and then-shortening the time of the electric field to perform plasma processing, the ion collision force is increased after decompression plasma treatment. Since there are many ions and radicals that are not accelerated by removing impurities and weakening the ion collision force by the weakened reduced pressure plasma treatment, the chemical reaction is promoted and the surface can be uniformly activated on the bonded surface. .. Therefore, the bonding strength can be increased at a low temperature. As for the joining result, the same result as in FIG. 14 was obtained.</p><p> In addition, a joining method and a surface activation device may be used in which a plurality of objects to be joined are brought into close contact with each other in the air after the treatment step. In this case, the chemical reaction is promoted by weakening the ion collision force in the latter half of the plasma treatment, and the surface activation treatment can be uniformly performed on the bonded surface. Since the bonding surface has already been chemically treated with OH groups and nitrogen substitution, it can be bonded even in the atmosphere.</p><p> Further, a joining method and a surface activation device may be used in which a plurality of objects to be joined are brought into close contact with each other under reduced pressure after the treatment step. Even if the pressure is returned to atmospheric pressure and the adsorption layer is attached, it is preferable to reduce the pressure in the vacuum chamber to bring the two objects to be joined in close contact with each other so that air can be joined by voidless without being involved in the joining interface. ..</p><p> Further, in the present invention, the plasma processing means for switching the ion collision force is a means for switching between two decompression plasma irradiation means, and the first plasma irradiation means for performing plasma processing by applying a power source to the object holding electrode side. In claim 8, the plasma generated in a separate chamber in the latter half of the plasma treatment is switched to a second plasma irradiation means that traps ions and irradiates radicals to weaken the ion collision force and promote the chemical treatment. It comprises the joining method described (claim 12).</p><p> Further, in the present invention, the plasma processing means for switching the ion collision force is a means for switching between two decompression plasma irradiation means, and the first plasma irradiation means for performing plasma processing by applying a power source to the object holding electrode side. In claim 27, the plasma generated in a separate chamber in the latter half of the plasma treatment is switched to a second plasma irradiation means that traps ions and irradiates radicals to weaken the ion collision force and promote the chemical treatment. The surface activator according to claim 31.</p><p> As shown in FIG. 12, in a state where the wafer to be the object to be bonded is held by the object holding electrode to be the plasma power source, first, an RF plasma power source is applied to physically process the object to be bonded by ion collision. Subsequently, the upper surface wave plasma irradiates the downflow with more radicals generated through the ion trap plate. Since the ions are trapped by the ion trap plate, more radicals can be irradiated and the chemical treatment is further promoted. As for the joining result, the same result as in FIG. 14 was obtained.</p><p> Further, in the present invention, the plasma processing means for switching the ion collision force is a means for switching between decompression plasma and atmospheric pressure plasma, and after treating the surface of the object to be joined with reduced ion collision force by increasing the ion collision force, the atmospheric pressure plasma The bonding method according to claim 8 is formed by performing plasma treatment that weakens the ion collision force and promotes chemical treatment at the above (claim 13).</p><p> Further, in the present invention, the plasma processing means for switching the ion collision force is a means for switching between the reduced pressure plasma and the atmospheric pressure plasma, and after treating the surface of the object to be joined with the reduced ion collision force by increasing the ion collision force, the atmospheric pressure plasma The surface activating device according to claim 27, which performs plasma treatment that weakens the ion collision force and promotes chemical treatment at the site (claim 32).</p><p> By dividing the plasma treatment into decompression plasma and atmospheric pressure plasma, in the decompression plasma treatment, impurities are removed by physical treatment, OH groups are attached to the surface by chemical treatment, and nitrogen is replaced. Since the chemically treated surface has a strong ion collision force, it is removed, and it is difficult to uniformly chemically treat the surface.</p><p> Therefore, by performing atmospheric pressure plasma treatment after decompression plasma treatment, in atmospheric pressure plasma, ions cannot be accelerated by an electric field as in vacuum, so the ion collision force is weak, and there are many ions and radicals that are not accelerated, so that a chemical reaction occurs. Can be promoted and the bonded surface can be uniformly chemically treated to perform a surface activation treatment. Therefore, the bonding strength can be increased at a low temperature. The low temperature is preferable because the conventional method requires 400 ° C or higher, and the bonding can be performed within 400 ° C, which is lower than that. The joining method and the surface activating device may be used in which the joining temperature is 200 ° C. or lower. As shown in FIG. 14, it is possible to join at 200 ° C or lower, which is more preferable. The joining method and joining device may be used in which the atmospheric pressure plasma treatment is performed, the vacuum is drawn again, and the joining is performed under reduced pressure. If the bonding is performed by vacuuming after plasma treatment under atmospheric pressure, the bonding environment is good and bonding can be performed without voids. Further, it may be a joining device provided with an atmospheric pressure plasma nozzle that irradiates in two directions between the objects to be held facing each other during the atmospheric pressure plasma treatment. Plasma processing can be performed efficiently by arranging them facing each other and processing with a two-way nozzle.</p><p> The present invention also comprises the joining method according to any one of claims 8 to 13, wherein the reaction gas is a mixed gas containing oxygen and nitrogen (claim 14).</p><p> The present invention also comprises the surface activator according to any one of Items 10 to 15, wherein the reaction gas is a mixed gas containing oxygen and nitrogen (claim 33).</p><p> By using a gas containing nitrogen, not only OH groups but also groups containing O and N are generated in the chemical treatment in which the ion collision force is weakened. As a result, compounds of Si, O, and N are generated at the interface at the time of bonding, and strong bonding is possible even at room temperature. FIG. 14 shows a comparison between the case of using only the oxygen reaction gas and the case of the reaction gas containing oxygen and nitrogen. In the case of oxygen alone, a strong bond cannot be obtained unless it is heated to about 200 ° C, but a mixture of oxygen and nitrogen enables a strong bond even at room temperature to 100 ° C.</p><p> The plasma reaction gas may be a joining method and a surface activating device using a different gas or a different compounding gas in the latter half of the plasma treatment. By using a different gas or a different compounding gas in the latter half of the plasma treatment, it is possible to use a gas superior to the chemical treatment, which is preferable. For example, by using Ar gas in the first half of the plasma treatment and oxygen gas in the second half, efficient plasma treatment becomes possible. Further, oxygen gas can be used in the first half and nitrogen gas can be used in the second half. Further, instead of simply using different gases, a mixed gas of Ar and oxygen may be used, and a large amount of Ar may be mixed in the first half and a large amount of oxygen may be mixed in the latter half. When a mixed gas of oxygen and nitrogen is used, a large amount of oxygen may be added in the first half and a large amount of nitrogen may be added in the latter half.</p><p> The joining method according to any one of claims 8 to 13, wherein the plasma reaction gas is switched to a reaction gas containing nitrogen at the time of plasma treatment in which the ion collision force is weakened by using the reaction gas containing oxygen. (Claim 15).</p><p> The surface according to any one of claims 26 to 32, wherein the plasma reaction gas is switched to a reaction gas containing nitrogen during plasma treatment in which the ion collision force is weakened by using the reaction gas containing oxygen. It comprises an activator (claim 34).</p><p> By using a gas containing nitrogen in a chemical treatment in which the ion collision force is weakened, not only OH groups but also groups containing O and N are generated. In addition, since some OH groups are attached even in the first half of the plasma treatment, the OH groups and N are replaced during the chemical treatment in which the ion collision force is weakened. Chemical treatment means treatment including substitution. As a result, compounds of Si, O, and N are generated at the interface at the time of bonding, and strong bonding is possible even at room temperature. In this method as well, the same good results as in FIG. 14 were obtained.</p><p> In addition, a joining method and a surface activation device for joining in a solid layer at a heating temperature of 100 ° C. or less at the time of joining may be used. Further, a joining method and a surface activating device may be used for joining in a solid layer at a heating temperature at room temperature.</p><p> If only OH groups are efficiently arranged excluding water molecules, bonding can be performed at 100 ° C or lower. Further, if a reaction gas containing nitrogen is chemically treated in the latter half of the plasma treatment, bonding can be performed even at room temperature, which is preferable. Further, the method and the joining apparatus according to the above are used for joining after the adsorption step of exposing to water molecules under atmospheric pressure or a gas containing hydrogen after the treatment step and before the joining step. After the treatment step, by exposing to water molecules or a gas containing hydrogen under atmospheric pressure, the bonding surface easily adsorbs water molecules and hydrogen compared to in vacuum plasma with less water molecules and hydrogen. Arrange OH groups to facilitate hydrogen bonding.</p><p> Further, the present invention is a method of plasma-treating and joining two objects to be joined in one vacuum chamber, in which a head for holding an upper object and a stage for holding a lower object are held in a vacuum chamber under reduced pressure. And, at least one of the stage or the head is provided with a pressurizing means for moving perpendicular to the joint surface, at least one of the stage or the head is provided with a means for moving laterally, and plasma processing means for each object to be joined. Both objects to be joined are placed facing each other in a state where they are moved to a lateral position where the joint surfaces do not overlap, and after plasma treatment is performed on both surfaces of the joints, they are slid to the joint position so that at least one of the objects to be joined is perpendicular to the joint surface. It may be a joining method and a surface activation device that are moved to and joined.</p><p> If both objects to be bonded are subjected to plasma treatment at a sliding position, a counter electrode can be provided on the facing surface of the electrode to be bonded. The plasma electrodes are arranged so as to be switchable between the object holding electrode and the facing electrode, and a power source is applied to the object holding electrode side to perform plasma treatment, and then a power source is applied to the facing electrode side. By weakening the ion collision force in the latter half of the plasma treatment, the chemical reaction is promoted and the surface activation treatment can be uniformly performed on the bonded surface. After that, if they are slid, both objects to be joined can be overlapped and brought into close contact with each other to be joined. In this method, two objects to be joined can be efficiently plasma-treated and joined in one chamber. Further, after the plasma treatment step, it can be easily bonded by exposing it to the atmosphere and adsorbing it. Further, in the apparatus configuration shown in FIG. 1, an alignment step for aligning and correcting the positions of both objects to be joined can be inserted before the joining step, and it is possible to perform positioning and joining with high accuracy.</p><p> Further, the present invention comprises the joining method according to any one of claims 1 to 15, wherein a voltage is applied between both objects to be joined at the time of joining and the bonding is performed in a solid layer under heating (claim 16).</p><p> The present invention also comprises the surface activating device according to any one of claims 20 to 34, wherein a voltage is applied between both objects to be joined at the time of joining and the solid layer is joined under heating (claim 35).</p><p> By applying a voltage of 500 to 1000V between both objects to be bonded, water molecules are efficiently discharged, and stronger bonding is possible even at low temperatures compared to the case of heating alone. Further, Si and SiO containing a material in which at least one of the objects to be bonded is decomposed into ions by a voltage.₂In the case of glass or ceramic, water molecules can be discharged more efficiently with the help of electrostatic force.</p><p> Further, in the present invention, at least one of the objects to be joined is Si, SiO.₂, Glass, ceramic, according to any one of Items 1 to 16 (Claim 17).</p><p> Further, in the present invention, at least one of the objects to be joined is Si, SiO.₂, Glass, ceramic, the surface activating apparatus according to any one of claims 20 to 35 (claim 36).</p><p> Si, SiO₂, Glass, ceramics, oxides, etc. can be easily arranged with OH groups attached to the bonding surface by using oxygen or nitrogen plasma to reduce the ion collision force in the latter half to promote the chemical reaction. If the OH group can be adsorbed, if both bonding surfaces are brought into close contact, they are bonded by hydrogen bonds. In addition, as explained as the conventional method, the surface activation method by Ar etching is the only method that can be bonded at low temperature, but the organic matter and oxide film on the surface are removed to create an electrically activated surface of the metal. Since it is bonded by interatomic force, it is not suitable for bonding semiconductors other than metals and especially oxides. Therefore, the present invention relates to semiconductors such as Si which are not metals, and SiO which contains oxides in particular.₂, The only effective low temperature bonding method for glass and ceramics. Also, when joining Si to each other, 10^-8A high vacuum state called Torr is required, but this method requires 10^-2It is preferable because it can be easily handled with a vacuum degree of about Torr.</p><p> The present invention also comprises the joining method according to any one of claims 1 to 17, wherein the object to be joined is a wafer or a chip cut out from the wafer (claim 18).</p><p> The present invention also comprises the surface activator according to any one of claims 20 to 36, wherein the object to be bonded is a wafer or a chip cut out from the wafer (claim 37).</p><p> SiO in semiconductors₂Is particularly suitable for this method because it is used as an internal insulator. In addition, glass and ceramics, which are insulators, are frequently used and effective in joining semiconductors and packages. As a form, it is most effective to handle and bond them on a wafer, which is a semiconductor manufacturing process, but it is also suitable in a chip state after dicing. It is a suitable method for heat-sensitive semiconductor devices because it enables bonding at low temperatures and releases ions when heated at high temperatures after ion implantation.</p><p> The present invention also comprises a device such as a semiconductor device or a MEMS device manufactured by the bonding method according to any one of claims 1 to 18 (claim 19).</p><p> It is a suitable method for heat-sensitive semiconductor devices because it enables bonding at low temperatures and releases ions when heated at high temperatures after ion implantation. In MEMS devices that superimpose dissimilar materials, distortion occurs due to high-temperature heating during conventional joining, and if one is an actuator, malfunction occurs. However, in this method, since bonding can be performed at a low temperature, strain due to heat is suppressed, which is suitable. Further, in pressure sensors and the like, since glass and Si are conventionally bonded, strain due to high temperature heating at the time of bonding affects the reliability of the device. In this method, since bonding can be performed at a low temperature, it is possible to produce a highly reliable MEMS device without distortion, which is suitable.</p><p> The present invention also includes the surface activating device according to any one of claims 20 to 37, and comprises a joining device that collectively performs the process from plasma hydrophilization treatment to bonding (claim 38).</p><p> In the bonding after hydrophilization treatment with plasma, it can be bonded in the atmosphere, but by performing it in the vacuum chamber, reattachment can be prevented without touching the atmosphere, and hydrogen bonding is possible in many pure OH groups. This is a more effective method next to it.</p>

<p> In the method of hydrophilizing the bonding surfaces of the objects to be bonded with plasma and bonding them in a solid layer within 500 ° C, the physics of physically processing both objects to be bonded with an energy wave such as an atomic beam, an ion beam or plasma. After the treatment step, a chemical treatment step of chemical treatment with plasma having a weak ion collision force is performed, and by joining both objects to be bonded, hydrophilic treatment without an organic material layer can be performed, and after hydrogen bonding without diffusion, it is possible to perform hydrophilic treatment. H₂Sufficient bonding strength can be obtained only by annealing at a low temperature to release O. Further, by processing both objects to be joined in the same vacuum chamber, all processing can be performed in one chamber.</p><p> Further, by weakening the ion collision force in the latter half of the plasma treatment, the chemical reaction is promoted and the surface activation treatment can be uniformly performed on the bonded surface. By doing so, a strong bond can be made at a low temperature.</p>

A preferred embodiment of the present invention will be described below with reference to the drawings.

(First Embodiment) FIG. 1 shows an apparatus for wafer surface activation and bonding according to the first embodiment of the present invention. In this embodiment, the physical treatment describes a method of etching for removing impurities as a pretreatment for adhering OH groups. In this embodiment, the chamber is closed while the wafers to be joined are held facing each other vertically, and after surface activation treatment with Ar plasma or oxygen plasma in a vacuum, the wafers are joined, and in some cases, the strength is increased by heating. It is a device to raise.

The apparatus configuration is divided into a head portion that holds the upper wafer 7 and performs elevating control and pressurization control by the Z axis 1, and a stage portion that holds the lower wafer 8 and aligns the wafers in some cases. A pressure detecting means is incorporated in the Z-axis 1, and the pressurizing control is performed by feeding back to the torque control of the Z-axis servomotor. The chamber wall 3 that can be raised and lowered by a separate actuator is lowered, and the chamber base 10 is evacuated while being grounded via the fixing packing 5, and the reaction gas is introduced to perform plasma processing. It is configured to join. Further, in some cases, the upper electrode 6 and the lower electrode 9 are also provided with a heating heater, and can be heated at the time of joining.

In FIG. 1, 2 is a piston type head, 4 is a sliding packing, 11 is a suction port, 12 is a discharge port, 13 is a suction valve, 14 is a discharge valve, 15 is a vacuum pump, 16 is a gas switching valve, and 17 Indicates gas A and 18 indicates gas B.

Explaining the processing procedure according to FIG. 2, first, the upper wafer 7 is held by the upper electrode 6 with the chamber wall 3 raised as shown in FIG. 2 (a). There is also a mechanical chucking method for holding, but the electrostatic chuck method is preferable.

Subsequently, the lower wafer 8 is held by the lower electrode 9. Then, as shown in FIG. 2B, the chamber wall 3 is lowered and grounded to the chamber base 10 via the fixing packing 5. Since the chamber wall 3 is shielded from the atmosphere by the sliding packing 4, it is possible to increase the degree of vacuum in the chamber by opening the discharge valve 14 with the suction valve 13 closed and evacuating with the vacuum pump 15. it can.

Next, as shown in FIG. 2 (c), the inside of the chamber is filled with the reaction gas. The vacuum pump 15 can be filled with the reaction gas while maintaining a constant degree of vacuum, which is to control the discharge amount of the discharge valve 14 and the gas suction amount of the suction valve 13 while operating the vacuum pump 15. As shown in Fig. (D) and (e), in this method, Ar gas is first filled, and then 10^-2Plasma is generated by applying an alternating power supply plasma voltage to the lower electrode 9 with a vacuum degree of about Torr, and the surface of the lower wafer 8 is cleaned by Ar etching. Subsequently, the upper wafer 7 is cleaned by Ar etching by applying a similar alternating power source to the upper electrode 6. Next, as shown in FIG. 6B, the inside of the chamber is further evacuated from the plasma generation region to discharge Ar. In some cases, by evacuating while heating both electrodes to about 100 ° C, Ar that adheres to the surface or is driven into the inside of the member is discharged. Further, the surface is subjected to oxygen plasma treatment by supplying oxygen gas instead of Ar in the procedures (c) to (e) of the same figure.

The method of switching between two gases, Ar and oxygen, in one chamber is to select and supply Ar and oxygen gas with the gas switching valve 16. First, after selecting and filling Ar, the suction valve 13 is closed, the inside of the chamber is evacuated and Ar is discharged, then the gas switching valve 16 switches to oxygen gas, the suction valve 13 is opened, and the inside of the chamber is oxygen gas. Fill with. Further, since the gas switching valve 16 can also inhale the atmosphere, it can be released to the atmosphere when the chamber is opened.

Next, in some cases, a gas containing water is supplied to hydrophilize the surface. Subsequently, as shown in FIG. 2 (f), the piston type head 2 is lowered by the Z axis 1 while the chamber wall 3 and the Z axis 1 are in contact with each other by the sliding packing 4 in a vacuum, and both wafers are placed in a vacuum. They are brought into contact with each other and joined by hydrogen bonding force. The inside of the chamber is shielded from the external atmosphere by the sliding packing 4 between the chamber wall 3 and the Z-axis 1, and the piston type head portion can be lowered while being held in a vacuum. In some cases, the heaters installed in both electrodes simultaneously heat the temperature from 200 ° C to 400 ° C to increase the strength.

After that, as shown in FIG. 2 (h), the atmosphere is supplied into the chamber, the pressure is returned to atmospheric pressure, the head portion is raised, and both the bonded wafers 7 and 8 are taken out. In some cases, when joining, the positions of both wafers may be aligned before joining.

Figure 3 shows a method of alignment before evacuation. The upper wafer 7 is provided with an alignment upper mark 23 at two locations, and the lower wafer 8 is provided with an alignment lower mark 24 at two similar positions. The two-field recognition means 25 is inserted between the two wafers, and the upper and lower mark positions are read by the recognition means. 2 The visual field recognition means 25 branches the upper and lower mark images by the prism 26, and separates and reads the upper mark recognition means 27 and the lower mark recognition means 28. The two-field recognition means 25 is moved by a table having an XY axis and, in some cases, a Z axis, and can read a mark at an arbitrary position. After that, the position of the lower wafer 8 is corrected and moved to the position of the upper wafer 7 by the alignment table 20. After moving, it is also possible to insert the two-field recognition means 25 again and repeat the correction to improve the accuracy.

Figure 4 shows a method that can be aligned even after vacuuming and before joining. The upper wafer 7 is provided with an alignment upper mark 23 at two locations, and the lower wafer 8 is provided with an alignment lower mark 24 at two locations. The upper and lower marks are shaped so that they can be recognized in the same field of view even if they overlap. Both wafers after plasma processing are brought close to each other, and the position is simultaneously recognized by the upper and lower alignment marks made of metal by passing through the lower wafer through the IR recognition means 22 through the mark reading transmission part 19 and the glass window 21. To read. If the depth of focus does not match, the IR recognition means 22 may be moved up and down to read. The IR recognition means 22 may be moved by a table having an XY axis and, in some cases, a Z axis so that the mark at an arbitrary position can be read. After that, the position of the lower wafer 8 is corrected and moved to the position of the upper wafer 7 by the alignment table 20. After the movement, the IR recognition means 22 can be used to make repeated corrections to improve the accuracy.

Next, SiO₂Fig. 5 shows the bonding principle of Si and Si by hydrophilization. As shown in Fig. 5 (a), OH groups are attached to the Si surface by hydrophilization treatment with oxygen plasma. Next, as shown in FIG. 6B, the two objects to be joined are brought into contact with each other and temporarily joined by hydrogen bonding. Subsequently, as shown in Fig. (C), H is heated by heating.₂O is released to obtain a strong bond of Si-O-Si.

However, as in the conventional case, when organic matter deposits are mixed on the surface, the organic matter is modified by oxygen plasma at that portion to form OH groups, as shown in FIG. 6 (a). Then, as shown in FIGS. (B) and (c), when this OH group and the other Si on the surface of the object to be bonded or the OH group on the organic substance are hydrogen-bonded, at least one of them is an organic substance, so water is released as it is. Even so, the bonding strength is low, and strong bonding cannot be achieved unless the organic layer is mixed and incorporated into the crystal by diffusing at a high temperature.

After oxygen plasma treatment, H₂As a method of joining after substituting with a gas containing O, H, or OH groups, a gas containing water is easy, but H₂O molecular beam, hydrogen gas, etc. can also be used.

Etching with Ar plasma is preferable for efficiency, but etching with other gases such as nitrogen and oxygen is also possible and is included in the present invention. In addition, at least one of the objects to be joined is Si, SiO.₂, Glass, CF as plasma reaction gas in the case of ceramic₄Is suitable because the material can be etched efficiently.

As a method of plasma treatment, it is preferable to clean the wafer on the alternating electrode surface in terms of efficiency, but in some cases, the electrodes are installed in a place other than the wafer to clean the wafer in order to reduce uniformity and damage.

In the configuration where the mark is read by the IR recognition means, the path of the IR light source in the mark reading transmission part 19, the glass window 21, the space between the alignment tables, etc. is not limited to the space and glass, but is made of a material that transmits IR light. It should be done. Further, not only the reflected light but also a transmitted light may be used by using a light source on the opposite side of the IR (infrared) recognition means.

Further, an elastic material is arranged on the surface of at least one of the objects to be bonded, and the parallelities are smoothed by pressing the two objects to be bonded through the elastic material at the time of the bonding, and even a thin object to be bonded can be used. For example, the flatness can be smoothed.

Further, the object holding means is held by a spherical bearing on the stage and / or the head, and the objects to be joined can be contact-pressurized at the time of joining or before joining to adjust the inclination of the other to at least one of the objects to be joined. If the structure is such that it can be joined, the parallelism can be made uniform.

In addition, at least one of the objects to be joined is Si, SiO.₂In the case of glass or ceramic, when treated with oxygen plasma, the bonding surface is hydrophilized, bonded by hydrogen bonds, and then heated at a low temperature of about 200 ° C for about 1 hour to release water molecules. It can be converted into a strong eutectic bond. Further, water molecules can be efficiently removed by applying a high voltage of about 500 V in a state where both objects to be joined are in contact with each other.

(Second Embodiment) Hereinafter, a desirable second embodiment of the present invention will be described with reference to the drawings. In the present embodiment, a method of attaching oxygen by physical treatment and promoting OH group adhesion by chemical treatment by switching the ion collision force in the step of adhering OH groups is described. To do.

FIG. 7 shows the configuration of the joining device by plasma processing in vacuum according to the present embodiment. In the present embodiment, an example is given as an apparatus for joining the upper wafer, which is the first object to be joined, and the lower wafer, which is the second object to be joined.

First, the device configuration will be described. As shown in FIG. 7, a head 207 for holding the upper wafer and a stage 208 for holding the lower wafer 209 are arranged in the vacuum chamber 211, and the head is a Z-axis elevating mechanism 202 to which a torque control type elevating drive motor 201 is connected. With the θ-axis rotation mechanism 203 that rotates the Z-axis elevating mechanism 202 and the XY alignment table 206 that aligns and moves the head portion in the XY horizontal direction, the alignment moving means in the X, Y, and θ directions and the elevating means in the Z direction Become. By feeding back the pressing force at the time of joining detected by the pressure detecting means 204 to the torque control type elevating drive motor 201, position control and pressure control can be switched. The pressure detecting means 204 can also be used to detect contact between objects to be joined. The XY alignment table 206 uses a means that can be used even in a vacuum, but since the Z and θ-axis mechanisms are installed outside the vacuum chamber, the head and the outside are movably cut off by the bellows 205.

The stage 208 can be slid and moved between the joining position and the standby position by the sliding moving means 229. The slide moving means is equipped with a highly accurate guide and a linear scale that recognizes the position, and the stop position between the joint position and the standby position can be maintained with high accuracy. Further, as the moving means, although it is incorporated inside the vacuum chamber, it is possible to arrange a cylinder, a linear servomotor, etc. outside by arranging the moving means outside and connecting them with a packing connecting rod. .. It can also be handled by arranging a ball screw in a vacuum and installing a servomotor outside. The means of transportation may be any means of transportation. As the means for holding the object to be joined of the head and the stage, a mechanical chucking method may be used, but it is preferable to provide an electrostatic chuck. In addition, it is equipped with a heater for heating and also serves as a plasma electrode, and has three functions of holding means, heating means, and plasma generating means.

As a depressurizing means, a vacuum pump 217 is connected to the exhaust pipe 215, and the exhaust valve 216 opens and closes and adjusts the flow rate, so that the degree of vacuum can be adjusted. On the suction side, the intake gas switching valve 20 is connected to the intake pipe 218, and the intake valve 219 opens and closes and adjusts the flow rate. Two types of plasma reaction gas can be connected as intake gas, for example, Ar221 and oxygen (O).₂) 222 can be connected. It is also possible to connect gases having different blends of mixed gases. The other is to connect nitrogen containing atmospheric or water molecules for atmospheric pressure release. The degree of vacuum including atmospheric pressure and the reaction gas concentration can be adjusted to the optimum values by adjusting the flow rate including opening and closing of the intake valve 219 and the exhaust valve 216. In addition, automatic feedback can be provided by installing a vacuum pressure sensor in the vacuum chamber.

Alignment mark recognition means consisting of an optical system for alignment is arranged outside the vacuum chamber above the stage standby position and below the head. The number of recognition means should be at least one on the stage and one on the head side, and if you want to recognize a small object such as a chip, the alignment mark has a shape that can read the θ direction component and two marks in one field of view. By arranging them, one recognition means can sufficiently read them, but as in the present embodiment, it is possible to read the wafers that are large in the radial direction with higher accuracy in the θ direction by arranging two at each end. It is preferable because it can be done.

Further, the recognition means may be provided with means that can move in the horizontal direction or the focal direction so that the alignment mark at an arbitrary position can be read. Further, the recognition means includes, for example, a camera with an optical lens composed of visible light or IR (infrared) light. A window made of a material that allows the optical system of the recognition means to pass through, for example, glass, is arranged in the vacuum chamber, and the alignment mark of the object to be joined in the vacuum chamber is recognized through the window. On the object to be joined, for example, alignment marks are provided on the opposing surfaces of the upper wafer and the lower wafer so that they can be recognized with high position accuracy. The alignment mark preferably has a specific shape, but a part of a circuit pattern or the like applied on the wafer may be diverted.

In addition, if there is no mark, an outer shape such as an orifra can be used. Both the alignment marks of the upper and lower wafers are read at the stage standby position, the stage is moved to the joining position, and the alignment is moved in the X, Y, and θ directions on the head side. In order to reflect the reading result of the standby position at the joint position, the relative movement distance vector between the standby position and the joint position of the stage must be accurate so that the same result is repeatedly obtained. Therefore, a guide having a high-precision repeatability is used, and a linear scale that reads the position recognition on both sides with high precision is arranged. A method to improve the stop position accuracy by feeding back the linear scale to the moving means, and if the moving means has a backlash such as a simple cylinder or a bolt / nut mechanism, the linear scale is placed in both stop positions. High accuracy can be easily achieved by reading with and correcting the excess or insufficient portion in consideration of when moving the head side alignment moving means.

For fine alignment at the nano level, after rough positioning, the head side recognition means can be used for both visible light and IR (infrared) with the upper and lower wafers close to each other by several μm. By using a recognition means and providing a transmission hole or a transparent material at the alignment mark position of the stage, the alignment mark on both wafers is simultaneously recognized through the stage from the bottom and aligned again in the X, Y, and θ directions. can do. When the recognition means has the moving means in the focal direction, the upper and lower sides can be recognized individually, but it is preferable to recognize them in close proximity to each other in terms of accuracy. In the case of fine alignment, it is possible to improve the accuracy by repeatedly aligning, and since the θ direction is affected by misalignment, after entering within a certain range, aligning only in the XY direction will improve the accuracy to the nano level. Can be improved. By using a sub-pixel algorithm as an image recognition means, it is possible to obtain recognition accuracy higher than the resolution of infrared rays. In addition, if the alignment is done in close proximity, the amount of Z movement required for joining will be within a minimum of several μm, so play and inclination with respect to Z movement can be minimized and high-precision nano-level joining accuracy is achieved. can do.

Next, the operation flow will be explained with reference to Fig. 8. First, as shown in FIG. 8A, the upper wafer and the lower wafer are held by the stage and the head with the front door of the vacuum chamber open. This may be done manually, but it may be automatically loaded from the cassette. Next, as shown in Fig. (B), the front door is closed and the pressure inside the vacuum chamber is reduced. 10 to remove impurities^-3It is preferable to reduce the pressure below Torr.

Subsequently, as shown in FIGS. 8 (c) and 8 (d), a plasma reaction gas such as oxygen gas is supplied, for example, 10^-2A plasma power supply is applied to the object holding electrode at a constant vacuum degree of about Torr to generate plasma. The generated plasma ions collide with the surface of the wafer held on the power supply side, and deposits such as an oxide film and an organic substance layer on the surface are etched. In addition, OH groups are attached to and arranged on the surface by replacing or adhering to the surface layer due to ion collision. However, since the ion collision force is strong, some OH groups are removed again and become uneven. It is difficult to uniformly chemically treat the surface of what has adhered to the surface because it has a strong ion collision force and is removed. Therefore, in the latter half of the plasma treatment, by switching the plasma power supply to the counter electrode, the ion collision force is weakened and there are many ions and radicals that are not accelerated by the plasma treatment, so the chemical reaction is promoted and the chemical treatment is uniformly applied to the bonded surface. This can be done to evenly align the OH radicals. It is also possible to process both wafers at the same time, but it is also possible to process them alternately by switching one matching box. Also, to remove reaction gas and etchings after or during treatment 10^-3It is preferable to reduce the pressure below Torr.

If the adsorption of OH groups is not sufficient by plasma treatment, as shown in Fig. 8 (e), water and hydrogen are easily adsorbed by exposing to gas or atmosphere containing water or hydrogen under atmospheric pressure. Can generate an OH group. After that, when joining in the atmosphere, the process proceeds to the step shown in the figure (g) while being exposed to the atmosphere, but when joining in a vacuum, the pressure is reduced again as shown in the figure (f). If this adsorption step is not required, proceed to the step shown in the figure (g) with reduced pressure.

Subsequently, as shown in FIG. 8 (g), the alignment marks on the upper and lower wafers are read in vacuum by the head side and stage side recognition means at the stage standby position to recognize the position. Then, as shown in FIG. 6H, the stage is slid to the joining position. At this time, the relative movement between the recognized standby position and the sliding joint position is performed with high accuracy using a linear scale.

If nano-level accuracy is required, the process shown in Fig. 8 (i) is added. After rough positioning, visible light and IR (infrared) combined recognition means are used for the head side recognition means with the upper wafer and lower wafer close to each other by about several μm, and they are transmitted to the alignment mark position of the stage. By providing holes and a transparent material, the alignment marks on both wafers can be simultaneously recognized by transmitting through the stage from the lower part and infrared-transmitted, and can be aligned again in the X, Y, and θ directions. In this case, it is possible to improve the accuracy by repeatedly aligning, and since the θ direction is affected by the misalignment, the accuracy can be improved to the nano level by aligning only in the XY direction after entering within a certain range. ..

Subsequently, as shown in FIG. 8 (j), the head is lowered, both wafers are brought into contact with each other, and the position control is switched to the pressure control to pressurize. With the contact detected by the pressure detecting means and the height position recognized, the value of the pressure detecting means is fed back to the torque control type elevating drive motor to control the pressure so as to reach the set pressure. Also, if necessary, it is heated at the time of joining. After contacting at room temperature, the temperature can be raised to keep the accuracy.

Further, as shown in FIG. 8 (k), the head-side holding means is released to raise the head. Subsequently, as shown in Fig. (L), the stage is returned to the standby position and the inside of the vacuum chamber is released to the atmosphere. Next, as shown in the figure (m), the front door is opened and the joined upper and lower wafers are taken out. It may be done manually, but it is preferable to automatically unload it into the cassette.

Further, an elastic material is arranged on the surface of at least one of the objects to be bonded, and the parallelities are smoothed by pressing the two objects to be bonded through the elastic material at the time of the bonding, and even a thin object to be bonded can be used. For example, the flatness can be smoothed.

Further, the object holding means is held by a spherical bearing on the stage and / or the head, and the objects to be joined can be contact-pressurized at the time of joining or before joining to adjust the inclination of the other to at least one of the objects to be joined. By making the structure so that it can be joined, the parallelism can be made uniform and joined.

In addition, in order to activate the surface by plasma treatment and join, as shown in Fig. 14, the heating temperature at the time of joining can be lowered from the conventional method of heating Si to 400 ° C or more to 200 ° C or less. It will be possible. In addition, solid layer bonding can be performed at 180 ° C or lower, which is the melting temperature of tin-lead solder of 183 ° C or lower. Further, it is possible and more preferable to use 100 ° C or less.

In addition, at least one of the objects to be joined is Si, SiO.₂In the case of glass or ceramic, when treated with oxygen plasma, the bonding surface is hydrophilized, bonded by hydrogen bonds, and then heated at a low temperature of about 200 ° C for about 1 hour to release water molecules. It can be converted into a strong eutectic bond. Further, as shown in FIG. 2 (g), water molecules can be efficiently removed by applying a high voltage of about 500 V in a state where both objects are in contact with each other.

Further, since it can be bonded at a low temperature by the above method, it is preferable for semiconductors that are sensitive to heat and MEMS devices that dislike thermal strain. Further, since bonding at a low temperature becomes possible and ions are released when the ions are implanted and then heated at a high temperature, this method is suitable for heat-sensitive semiconductor devices.

(Third Embodiment) As the plasma processing for switching the ion collision force, in the second embodiment, it was performed by switching the plasma electrode, but in the third embodiment, the decompression plasma is an RF plasma power supply whose Vdc can be adjusted. In preparation for this, the Vdc value is changed in the latter half of the plasma treatment to weaken the ion collision force and perform the plasma treatment. FIG. 10 is a waveform diagram of the RF plasma power supply.

An electric field is created on the plasma electrode side, but the speed at which ions collide changes depending on the Vdc value. For example, + oxygen ion is accelerated as the Vdc value is-and the ion collision force increases, and as it approaches 0, the velocity becomes slower, the ion collision force decreases, and there are many unaccelerated ions and radicals, so a chemical reaction. Is promoted. By increasing the Vdc value to the-side and performing plasma treatment, and then moving the Vdc value closer to 0 and performing an adsorption step, impurities are removed by performing plasma treatment with weakened ion collision force in the latter half of the plasma treatment. Moreover, since there are many ions and radicals that are not accelerated by weakening the ion collision force, the chemical reaction is promoted and the surface can be uniformly activated on the bonded surface. Therefore, the bonding strength can be increased at a low temperature. The joining results were similar to those in Fig. A.

(Fourth Embodiment) As the plasma processing for switching the ion collision force, in the fourth embodiment, the decompression plasma is provided with a pulse wave plasma power source whose pulse width can be adjusted, and the pulse width is changed in the latter half of the plasma treatment to generate ions. Plasma processing is performed by weakening the collision force. FIG. 11 is a waveform diagram of the pulse wave plasma power supply.

An electric field is created on the plasma electrode side, but by adjusting the pulse width, it is possible to adjust the feeling that + ions collide-the time of the electric field and the collision weaken-the time when the electric field is weak. -Increasing the time of the electric field strengthens the collision of + ions, and decreasing the time of the-electric field weakens the collision of + ions. For example, + oxygen ions-accelerate as the time of the electric field increases and the ion collision force increases, -the speed decreases as the time of the electric field decreases, the ion collision force decreases, and there are many unaccelerated ions and radicals. Therefore, the chemical reaction is promoted.

By adjusting the pulse width-increasing the time of the electric field to perform plasma treatment, and then-shortening the time of the electric field to perform plasma processing, the ion collision force is increased after decompression plasma treatment. Since there are many ions and radicals that are not accelerated by removing impurities and weakening the ion collision force by the weakened reduced pressure plasma treatment, the chemical reaction is promoted and the surface can be uniformly activated on the bonded surface. .. Therefore, the bonding strength can be increased at a low temperature. The joining results were similar to those in Fig. A.

(Fifth Embodiment) In the second embodiment, an example of bonding by hydrogen bonding by an OH group using oxygen plasma was given, but in the fifth embodiment, the reaction gas is composed of a mixed gas containing oxygen and nitrogen. A compound is produced and bonded.

By using a gas containing nitrogen in addition to oxygen, not only OH groups but also groups containing O and N are generated in the chemical treatment in which the ion collision force is weakened. In addition, since some OH groups are attached even in the first half of the plasma treatment, the OH groups and N are replaced during the chemical treatment in which the ion collision force is weakened. As a result, compounds of Si, O, and N are generated at the interface at the time of bonding, and strong bonding is possible even at 100 ° C or lower or at room temperature. Figure 9 shows a comparison between the case of using only the oxygen reaction gas and the case of the reaction gas containing oxygen and nitrogen.

In the case of oxygen alone, a strong bond cannot be obtained unless it is heated to about 200 ° C, but in the case of a mixture of oxygen and nitrogen, a strong bond can be made at 100 ° C or less, or even at room temperature.

(Sixth Embodiment) In the second embodiment, an example of bonding by hydrogen bonding by an OH group using oxygen plasma is given, but in the sixth embodiment, at least one of the objects to be bonded is Si, glass, or oxide. , The plasma reaction gas uses a different gas or a different compounding gas in the latter half of the plasma treatment.

By using a different gas or a different compounding gas in the latter half of the plasma treatment, it is possible to use a gas superior to the chemical treatment, which is preferable. For example, oxygen gas can be used in the first half and nitrogen gas can be used in the second half. Further, instead of simply using different gases, a mixed gas of oxygen and nitrogen may be used, and a large amount of oxygen may be mixed in the first half and a large amount of nitrogen may be mixed in the latter half.

The plasma reaction gas uses a reaction gas containing oxygen and is switched to a reaction gas containing nitrogen during plasma treatment in which the ion collision force is weakened. By using a gas containing nitrogen in a chemical treatment in which the ion collision force is weakened, not only OH groups but also groups containing O and N are generated. In addition, since some OH groups are attached even in the first half of the plasma treatment, the OH groups and N are replaced during the chemical treatment in which the ion collision force is weakened. As a result, compounds of Si, O, and N are generated at the interface at the time of bonding, and strong bonding is possible even at room temperature. The same good results as in Fig. 9 were obtained with this method as well.

Further, in the second to sixth embodiments, the plasma reaction gas can be treated individually by using a different gas for one object to be bonded and the other.

Further, in the second to sixth embodiments, although the wafer is raised as the object to be bonded in the above embodiment, it may be a chip and a substrate. The object to be bonded is not limited to a wafer, a chip, and a substrate, and may be in any form.

Further, in the second to sixth embodiments, the electrostatic chuck method is desirable as the holding means for the object to be joined, but a mechanical chucking method may also be used. Further, it is more preferable to first hold the vacuum suction and hold it in the atmosphere to bring it into close contact, and then mechanically chuck it to increase the adhesion.

Further, in the second to sixth embodiments, the head side has the alignment moving means and the elevating shaft, and the stage side has the slide shaft. However, how the alignment moving means, the elevating shaft, and the slide shaft are on the head side and the stage side. They may be combined or duplicated. Further, even if the head and the stage are not arranged vertically, it does not depend on the arrangement direction such as left-right arrangement or diagonal arrangement.

Further, in the second to sixth embodiments, when plasma treatment is performed in a state where the stage is slid, the electrode shapes of the head and the stage and the surrounding shapes are similar, so that the electric field environment is similar. Therefore, even if the matching box that automatically adjusts the plasma power supply is not used individually, the electrodes can be switched by one and the plasma processing can be sequentially performed on the head side and the stage side. By doing so, compactness and cost reduction can be achieved.

(7th Embodiment) In the 7th embodiment, the plasma processing means for switching the ion collision force is a means for switching between two decompression plasma irradiation means, and plasma treatment is performed by applying a power source to the object holding electrode side. The first plasma irradiation means for performing the above and the second plasma irradiation means for trapping the ions and irradiating the radicals with the plasma generated in the separate chamber in the latter half of the plasma treatment are switched to weaken the ion collision force and promote the chemical treatment. It is characterized by performing plasma processing.

As shown in FIG. 12, in a state where the wafer 503 to be bonded is held by the object holding electrode to be a plasma power source, first, an RF plasma power source 501 is applied to physically process the object to be bonded by ion collision. Do. Subsequently, the upper surface wave plasma irradiates the downflow with more radicals generated through the ion trap plate. Since the ions are trapped by the ion trap plate 502, more radicals can be irradiated and the chemical treatment is further promoted.

In FIG. 12, 500 is a surface wave plasma generating means, 504 is a radical, 505 is an ion, 506 is a vacuum chamber, 507 is a reaction gas supply port, 508 is an exhaust port, 509 is an object holding electrode, and 510 is a micro. The wave power supply, 511 is the surface wave plasma generation region, and 512 is the RF plasma generation region.

(Eighth Embodiment) The eighth embodiment in which atmospheric pressure plasma is used for chemical treatment in which the ion collision force is weakened will be described below with reference to the drawings. In the present embodiment, the chamber is closed while the wafer to be joined is held facing up and down, treated with oxygen plasma in a vacuum, the chamber wall is opened, and an atmospheric pressure plasma nozzle is inserted to insert an atmospheric pressure. It is plasma-treated and joined. In some cases, the strength may be increased by heating.

Since the apparatus configuration in this embodiment is basically the same as that in FIG. 1, duplicate description will be omitted. The difference from the description of the first embodiment is that when the chamber wall is opened, an atmospheric pressure plasma nozzle can be inserted to perform atmospheric pressure plasma treatment on the upper and lower wafers. Further, for efficiency, two nozzles may be provided on the upper and lower sides so that the upper and lower processing can be performed at the same time.

Explaining the processing procedure of the present embodiment with reference to FIG. 13, first, the upper wafer 7 is held by the upper electrode 6 in a state where the chamber wall 3 is raised as shown in FIG. 13 (a). There is also a mechanical chucking method for holding, but the electrostatic chuck method is preferable.

Subsequently, the lower wafer 8 is held by the lower electrode 9. Then, as shown in FIG. 13B, the chamber wall 3 is lowered and grounded to the chamber base 10 via the fixing packing 5. Since the chamber wall 3 is shielded from the atmosphere by the sliding packing 4, it is possible to increase the degree of vacuum in the chamber by opening the discharge valve 14 with the suction valve 13 closed and evacuating with the vacuum pump 15. it can.

Next, as shown in FIG. 13 (c), the inside of the chamber is filled with the reaction gas. The vacuum pump 15 can be filled with the reaction gas while maintaining a constant degree of vacuum, which is to control the discharge amount of the discharge valve 14 and the gas suction amount of the suction valve 13 while operating the vacuum pump 15. As shown in Figures (d) and (e), in this method, oxygen gas is first filled, and then 10^-2Plasma is generated by applying an alternating power supply plasma voltage to the lower electrode 9 with a vacuum degree of about Torr, and the surface of the lower wafer 8 is physically treated with oxygen plasma. Subsequently, the upper wafer 7 is physically processed by oxygen plasma by applying a similar alternating power source to the upper electrode 6.

Next, as shown in FIG. 13 (f), the chamber wall is opened, the atmospheric pressure plasma nozzle 29 is inserted, and the upper and lower wafers are chemically treated with atmospheric pressure plasma. After that, in some cases, a gas containing water is supplied to hydrophilize the surface. Subsequently, as shown in Fig. (G), the chamber wall is closed and the pressure is reduced, and as shown in Fig. (H), the piston type head 2 is in contact with the chamber wall 3 with the sliding packing 4 in a vacuum. It is lowered by the Z axis 1, and both chambers are brought into contact with each other in a vacuum and bonded by a hydrogen bonding force.

The inside of the chamber is shielded from the external atmosphere by the sliding packing 4 between the chamber wall 3 and the piston type head 2, and the piston type head portion can be lowered while being held in a vacuum. In some cases, the heaters installed in both electrodes simultaneously heat the temperature from 100 ° C to 200 ° C to increase the strength. After that, as shown in FIG. 13 (i), the atmosphere is supplied into the chamber, the pressure is returned to atmospheric pressure, the head portion is raised, and both the bonded wafers are taken out.

In some cases, the wafers may be joined after the positions of both wafers are aligned at the time of joining. Alignment before evacuation is performed as shown in FIG.

As shown in FIG. 3, the upper wafer 7 is provided with the upper markings 23 for alignment at two positions, and the lower wafer 8 is provided with the lower marks 24 for alignment at two similar positions. The two-field recognition means 25 is inserted between the two wafers, and the upper and lower mark positions are read by the recognition means. 2 The visual field recognition means 25 branches the upper and lower mark images by the prism 26, and separates and reads the upper mark recognition means 27 and the lower mark recognition means 28. 2 The field of view recognition means 25 is moved by a table having an XY axis and, in some cases, a Z axis, and can read a mark at an arbitrary position. After that, the position of the lower wafer 8 is corrected and moved to the position of the upper wafer 7 by the alignment table 20. After moving, it is also possible to insert the two-field recognition means 25 again and repeat the correction to improve the accuracy.

In addition, it can be aligned even after vacuuming and before joining. As shown in FIG. 4, the upper wafer 7 is provided with an alignment upper mark 23 at two locations, and the lower wafer 8 is provided with an alignment lower mark 24 at two locations. The upper and lower marks are shaped so that they can be recognized in the same field of view even if they overlap. Both wafers after plasma processing are brought close to each other, and the position is simultaneously recognized by the upper and lower alignment marks made of metal by passing through the lower wafer through the IR recognition means 22 through the mark reading transmission part 19 and the glass window 21. To read. If the depth of focus does not match, the IR recognition means 22 may be moved up and down to read. The IR recognition means 22 may be moved by a table having an XY axis and, in some cases, a Z axis so that the mark at an arbitrary position can be read. After that, the position of the lower wafer 8 is corrected and moved to the position of the upper wafer 7 by the alignment table 20. After the movement, the IR recognition means 22 can be used to make repeated corrections to improve the accuracy.

After atmospheric pressure plasma treatment, H₂As a method of joining after substituting with a gas containing O, H, or OH groups, a gas containing water is easy, but H₂O molecular beam, hydrogen gas, etc. can also be used.

As a method of decompression plasma treatment, it is preferable to treat the wafer on the alternating electrode surface in terms of efficiency, but in some cases, the electrode is placed in a place other than the wafer to treat the wafer in order to reduce uniformity and damage.

In addition, since the surface is activated by plasma treatment to join, the heating temperature at the time of joining can be lowered to 200 ° C or less from the conventional method of heating Si to 400 ° C or more to join. It becomes. In addition, solid layer bonding can be performed at 180 ° C or lower, which is the melting temperature of tin-lead solder of 183 ° C or lower. Further, it is more preferable because it is possible at 100 ° C. or lower and at room temperature.

In addition, at least one of the objects to be joined is Si, SiO.₂In the case of glass or ceramic, when treated with oxygen plasma, the bonding surface is hydrophilized, bonded by hydrogen bonds, and then heated at a low temperature of about 200 ° C for about 1 hour to release water molecules. It can be converted into a strong eutectic bond. Further, as shown in FIG. 2 (g), water molecules can be efficiently removed by applying a high voltage of about 500 V in a state where both objects to be joined are in contact with each other.

Further, since the above method can be bonded at a low temperature, it is preferable for semiconductors that are sensitive to heat and MEMS devices that dislike thermal strain. Further, since bonding at a low temperature becomes possible and ions are released when the ions are implanted and then heated at a high temperature, this method is suitable for heat-sensitive semiconductor devices.

<figref num="1">It is a schematic block diagram of the apparatus in 1st Embodiment of this invention.</figref><figref num="2">It is a process drawing which shows the joining procedure of 1st Embodiment.</figref><figref num="3">2 It is an alignment block diagram in the atmosphere using the visual field recognition means.</figref><figref num="4">It is an alignment block diagram in vacuum using an IR recognition means.</figref><figref num="5">SiO₂It is explanatory drawing of the bonding principle by the hydrophilization treatment of Si and Si.</figref><figref num="6">It is a bonding principle diagram by the conventional hydrophilization treatment with an organic substance.</figref><figref num="7">It is a schematic block diagram of the apparatus in the 2nd Embodiment of this invention.</figref><figref num="8">It is a process drawing which shows the joining procedure of 2nd Embodiment.</figref><figref num="9">It is a comparative explanatory view of the junction strength by the plasma processing method of 1st Embodiment.</figref><figref num="10">It is a waveform diagram of the RF plasma power source in the 3rd Embodiment of this invention.</figref><figref num="11">It is a waveform figure of the pulse wave plasma power source in 4th Embodiment of this invention.</figref><figref num="12">It is a schematic block diagram of the apparatus in 7th Embodiment of this invention.</figref><figref num="13">It is a process drawing which shows the joining procedure of 8th Embodiment of this invention.</figref><figref num="14">It is a comparative explanatory view of the junction strength by the plasma treatment method of 2nd to 8th Embodiment.</figref>

Code description

1 Z-axis 2 Piston type head 3 Chamber wall 4 Sliding packing 5 Fixed packing 6 Upper electrode 7 Upper wafer 8 Lower wafer 9 Lower electrode 10 Chamber stand 11 Suction port 12 Discharge port 13 Suction valve 14 Discharge valve 15 Vacuum pump 16 Gas switching Valve 17 Gas A18 Gas B19 Mark reading transmission 20 Alignment table 21 Glass window 22 IR recognition means 23 Upper mark 24 Lower mark 25 2 Field recognition means 26 Prism 27 Upper mark recognition means 28 Lower mark recognition means 201 Torque control type elevating drive Motor 202 Z-axis elevating mechanism 203 θ-axis rotation mechanism 204 Pressure detection means 205 Bellows 206 XY alignment table 207 Head 208 Stage 209 Lower wafer 210 Upper wafer 211 Vacuum chamber 212 Head side recognition means 213 Stage side recognition means 214 Glass window 215 Exhaust pipe 216 Exhaust valve 217 Vacuum pump 218 Intake pipe 219 Intake valve 220 Intake gas switching valve 221 Ar222 O₂223 Atmosphere 227 Upper alignment mark 228 Lower alignment mark 229 Slide moving means 500 Surface wave plasma generating means 501 RF Plasma power supply 502 Ion trap plate 503 Wafer 504 Radical 505 Ion 506 Vacuum chamber 507 Reaction gas supply port 508 Exhaust port 509 Joint holding electrode 510 Microwave power supply 511 Surface wave plasma generation area 512 RF plasma generation area