Local treatment device

Description: TECHNICAL FIELD [Detailed description of the invention]

【0001】

[Technical field to which the invention belongs]

The present invention relates to a surface treatment technique for etching, ashing, modifying or forming a thin film on the surface of an object to be treated, particularly using an excitationally active species generated in plasma at or near atmospheric pressure. It relates to a local treatment apparatus which performs surface treatment.

【0002】

[Conventional technology]

Conventionally, by using the excitationally active species generated by plasma discharge under the pressure near atmospheric pressure, the surface of the object to be treated can be treated in various ways at low cost without the need for vacuum equipment. Processing technology is known. For surface treatment with plasma under atmospheric pressure, a direct discharge method in which a gas discharge is directly generated between the electrodes and the object to be processed and the plasma is directly exposed to the generated plasma, and a plasma is generated by gas discharge between a pair of electrodes. There is an indirect discharge method in which the object to be treated is exposed to the excitationally active species produced thereby.

【0003】

The indirect discharge method has a lower processing rate than the direct discharge method, so that a high output may be required, but it is advantageous in that there is no risk of damage to the object to be processed due to charge-up. In Japanese Patent Application Laid-Open No. 6-190269, a high-frequency voltage is applied between a pair of electrodes from a power source to generate a discharge, and a gas such as helium or oxygen passing through a discharge region between the two electrodes is excited and ionized for activity. By generating seeds and ejecting the gas containing the active seeds as a reactive gas flow onto the object to be treated from the gas outlet, a local dry cleaning process is performed in response to the limitation of the shape and treatment range of the object to be treated. A surface treatment device having a gun structure has been proposed.

【0004】

Further, a typical example of a surface treatment apparatus particularly suitable for local surface treatment for such atmospheric pressure plasma is also disclosed in Japanese Patent Application Laid-Open No. 9-232293. This conventional device includes, for example, a thin discharge tube made of a dielectric material such as glass having a narrow cross section having an inner diameter of 1 mm or less, and a pair of electrodes arranged so as to sandwich the discharge tube, and is provided at the tip of the discharge tube. The nozzle portion is arranged so as to face the surface of the object to be processed. The surface of the object to be treated is a reactive gas containing an excitationally active species generated by generating a gas discharge between both electrodes while introducing a predetermined gas into the discharge tube from the gas supply source as a thin gas flow from the nozzle portion. To spray.

【0005】

[Problems to be Solved by the Invention]

However, in the past, there were the following problems.

【0006】

When gas discharge is continuously generated, the electrode portion generates heat, so that it reacts with the surrounding air and oxidizes, resulting in deterioration of the electrode portion. For this reason, the performance of the electrode portion is lowered, the efficiency of generating gas discharge is lowered, and the surface treatment efficiency is lowered, which has been a problem. In particular, this problem was remarkable when copper was used as the material of the electrode portion.

【0007】

Further, especially when gas discharge is caused by high frequency power having an output frequency of 30 MHz or more, high frequency power is conducted on the surface of the electrode portion, so that it is required to reduce the resistivity of the surface of the electrode portion to improve the conduction efficiency. Was there.

【0008】

An object of the present invention is to provide a local treatment apparatus capable of improving surface treatment efficiency by stably and efficiently generating gas discharge by protecting the electrode portion from deterioration due to oxidation.

【0009】

Furthermore, another object of the present invention is to provide a local treatment apparatus capable of increasing the conduction efficiency of high frequency power and improving the surface treatment efficiency.

【0010】

[Means for solving problems]

In order to achieve the above object, in the local processing apparatus according to the present invention, a pair of electrodes arranged so as to sandwich a discharge tube through which a processing gas flows, and a lead connecting one of the electrodes to a high frequency power supply. An electrode portion was formed by the above, and the surface of the electrode portion was plated. Therefore, even if gas discharge is continuously generated and the electrode portion generates heat, the surface of the electrode portion is protected by the plating treatment, so that the electrode portion can be protected from deterioration due to oxidation. In particular, even when the electrode portion is made of copper, oxidation of the surface of the electrode portion can be prevented and the performance can be reliably ensured. As a result, gas discharge can be generated stably and efficiently.

【0011】

In the above configuration, the plating may be gold-plated. As a result, the surface of the electrode portion can have a low electrical resistivity, the conduction efficiency can be increased, and the gas discharge generation efficiency can be increased.

【0012】

In the above configuration, the high frequency power supply may have an output frequency of 30 MHz or more. When the output frequency is 30 MHz or more, high frequency power is conducted on the surface of the electrode portion. By plating the surface portion with gold, the conduction efficiency of the surface portion of the electrode portion is improved, so that high-frequency power can be effectively conducted and the efficiency of gas discharge generation can be increased.

【0013】

BEST MODE FOR CARRYING OUT THE INVENTION

An embodiment of the local processing apparatus of the present invention will be described in detail with reference to the drawings.

【0014】

FIG. 1 is a cross-sectional view of the local processing apparatus 20 according to the present embodiment. The local treatment apparatus 20 in the present embodiment has a casing member 21. The casing member 21 is formed of an upper casing member 22, a middle casing member 24, a lower casing member 26, and a bottom casing member 28. The upper to bottom casing members 22, 24, 26, and 28 are each formed by hollowing out the center portion of a substantially prismatic block body into a substantially cylindrical shape. The casing member 21 is brought into close contact with the hollowed-out portions of the upper to bottom casing members 22, 24, 26, 28 so as to be centered. Therefore, since a part of the casing members 22, 24, 26, 28 can be omitted or added to the casing member 21, the size can be adjusted according to the member to be inserted into the casing member 21. This real In facilities embodiment, the casing member 21 is formed of aluminum. Therefore, it is possible to shield the electromagnetic wave to the outside of the casing member 21. The material of the casing member 21 is not limited to aluminum and may be any material having a shielding function.

【0015】

A straight tubular discharge tube 40 is arranged on the axis of the casing member 21. The upper end of the discharge pipe 40 is located on the axis of the upper casing member 22, and the lower end of the discharge pipe 40 faces the inner wall surface of the bottom casing member 28. On the other hand, a nozzle tip 44 is detachably provided on the facing surface of the bottom casing member 28 facing the lower end of the discharge tube 40 so that the nozzle tip 44 projects to the outside, and the lower end of the discharge tube 40 is attached to the nozzle tip 44. It is fitted. By forming the discharge tube 40 and the nozzle tip 44 in a separable manner in this way, the nozzle tip 44 can be replaced with one having a different hole diameter. Therefore, the surface treatment area can be adjusted. Further, as the material of the nozzle tip 44, stainless steel (SUS) or aluminum is preferable.

【0016】

The nozzle tip 44 has an upper end protruding into the bottom casing member 28. The upper end of the nozzle tip 44 is screwed to the nozzle holder 42 formed in a substantially cylindrical shape and fixedly held. As the material of the nozzle holder 42, stainless steel (SUS) or aluminum is preferable.

【0017】

The discharge tube 40 is covered with a protective member 36 around a surface facing the lower casing member 26. The protective member 36 has an inverted T shape in which a partition portion 39 is integrally vertically installed at a central portion of a receiving portion 37. The protective member 36 penetrates the discharge pipe 40 through the central shaft portion of the partition portion 39 to protect the discharge pipe 40. Then, the protective member 36 abuts the lower surface of the receiving portion 37 on the upper surface of the nozzle holder 42 and is supported by the nozzle holder 42.

【0018】

A pair of rod-shaped electrodes 46 and 48 are brought into contact with the vertical centers shown in FIG. 2 (a) of both sides 39a and 39b of the partition portion 39 of the protective member 36, respectively. The pair of rod-shaped electrodes 46 and 48 each have a substantially rectangular shape, and as shown in FIG. 2A, the pair of rod-shaped electrodes 46 and 48 are arranged so as to face each other so as to sandwich the partition portion 39 of the protective member 36 and form a straight line when viewed from above. There is. The discharge tube 40 penetrates in the vertical direction through the central portion of the partition portion 39 sandwiched between the rod-shaped electrodes 46 and 48, and causes a gas discharge in the penetrating portion of the discharge tube 40. In this way, the pair of rod-shaped electrodes 46 and 48 are arranged in the vicinity of the nozzle tip 44. As a result, the excitation active species such as plasma can be immediately discharged from the nozzle tip 44 to the outside. Therefore, sufficient excitation active species can reach the surface of the object to be treated.

【0019】

Further, the length of the receiving portion 37 in the longitudinal direction is formed longer than the length of the rod-shaped electrodes 46 and 48 in the longitudinal direction. As a result, the installation area of both electrodes 46 and 48 is secured. In particular, since the rod-shaped electrode 46 to which the high-frequency voltage is applied does not face the bottom casing member 28 in a straight line, it is possible to prevent the rod-shaped electrode 46 from being short-circuited with the bottom casing member 28. The protective member 36 is made of alumina and quartz, and retains the insulation of both electrodes 46 and 48. The material of the protective member 36 is not limited to this as long as it is an insulator material.

【0020】

The height of the partition portion 39 of the protective member 36 is formed higher than that of the rod-shaped electrodes 46 and 48, as shown in FIG. 2 (b). Further, the partition portions 39a and 39b of the protective member 36 are formed sufficiently long in the thickness direction of the rod-shaped electrodes 46 and 48. As a result, the rod-shaped electrodes 46 and 48 do not face each other in a straight line. If the rod-shaped electrodes 46 and 48 face each other in a straight line, when the rod-shaped electrodes 46 and 48 are applied to the rod-shaped electrodes 46 and 48, a creepage discharge may occur in which the rod-shaped electrodes 46 and 48 are conducted along the surface (creeping surface) of the protective member 36. When creeping discharge occurs, the gas discharge in the discharge tube 40 does not occur or the generated gas discharge is stopped. As described above, since the partition portion 39 of the protective member 36 is formed sufficiently long in the thickness direction of the rod-shaped electrodes 46 and 48, creeping discharge can be prevented. Therefore, the gas discharge through the discharge pipe 40 can be surely generated, and the generated gas discharge can be stably maintained. The rod-shaped electrodes 46 and 48 are made of aluminum, and their surfaces are gold-plated. As a result, corrosion and oxidation of the rod-shaped electrodes 46 and 48 can be prevented. Since gold has high conductivity, the conduction efficiency of the rod-shaped electrode can be improved. In addition, deterioration of the performance of the rod-shaped electrodes 46 and 48 can be prevented.

【0021】

A holder member 50 is interposed between the back surface of the rod-shaped electrode 46 and the inner wall surface of the casing member 21. The base end portion of the holder member 50 is in contact with the inner wall surface of the lower casing member 26, and the tip end portion of the holder member 50 is in contact with the back surface portion of the rod-shaped electrode 46. As a result, the rod-shaped electrode 46 is positioned and held on the protective member 36 side. Alumina or quartz can be preferably used as the material of the holder member 50, but the material is not limited to this as long as it is an insulator material.

【0022】

On the other hand, the other rod-shaped electrode 48 is integrally connected to the extension electrode 49 exposed to the outer surface of the lower casing member 21. The extension electrode 49 is connected to a ground path (not shown). As a result, the rod-shaped electrode 48 is ensured to be grounded, and a short circuit can be prevented in the casing member 21.

【0023】

An intermediate member 34 having a substantially cylindrical shape is arranged on the protective member 36. The intermediate member 34 is arranged so that the side surface portion faces the inner wall surface of the central casing member 24. Then, the lower surface of the intermediate member 34 is in contact with the upper surface of the partition portion 39 of the protective member 36 to position the protective member 36. Further, a through hole is provided in the central shaft portion of the intermediate member 34, and the discharge pipe 40 is inserted into the through hole to protect the discharge pipe 40. The intermediate member 34 is made of Teflon or mica-based ceramics, whereby insulation to the outside of the discharge tube 40 is maintained. The intermediate member 34 is preferably Teflon or mica-based ceramics, but is not limited to this as long as it is an insulator material.

【0024】

An insulating member 32 is arranged above the intermediate member 34. The insulating member 32 has a substantially cylindrical shape corresponding to the hollowed out portion of the upper casing member 22. The insulating member 32 is fitted in a hollowed portion of the upper casing member 32. As a result, the casing member 21 is sealed in the upper surface direction, and a closed space can be formed inside the casing member 21. The upper surface of the insulating member 32 is formed in a concave shape in cross section, and the lower surface of the concave portion is formed so as to correspond to the upper surface of the intermediate member 34. The lower surface of the insulating member 32 is formed in the shape of a reverse convex portion having a cross section protruding downward, and the lower surface of the reverse convex portion is in contact with the upper surface of the intermediate member 34. The insulating member 32 has a gas inflow hole 33 opened in the peripheral surface portion. A gas inflow pipe 62 connected to a gas supply source (not shown) is also provided on one side surface of the upper casing member 22, and the tip of the gas inflow pipe 62 corresponds to the upper opening of the gas inflow hole 33. There is. The gas inflow hole 33 extends from the upper opening toward the axial center of the insulating member 32, and bends downward along the axial center at the axial center. The gas inflow hole 33 reaches the lower surface of the insulating member 32, and has a lower opening at the lower surface portion. The upper end of the discharge pipe 40 is inserted into the lower opening of the gas inflow hole 33 on the lower surface of the insulating member 32. Therefore, the processing gas flowing in from the gas inflow pipe 62 is sent out to the upper part of the discharge pipe 40 through the gas inflow hole 33. Further, a cylindrical pressing member 35 is formed on the inner wall surface of the opening below the gas inflow hole 33. An inner flange is formed on the holding member 35, and the inner flange abuts on the upper portion of the discharge pipe 40 and urges it downward. Therefore, the discharge tube 40 can be positioned. The insulating member 32 is made of Teflon to maintain insulation. The insulating member 32 is not limited to this as long as it is an insulating material.

【0025】

Further, the reed 30 is inserted and arranged from the axial center direction of the upper surface of the upper casing member 22. The lead 30 bends in the radial direction near the upper surface of the insulating member 32. Then, it descends along the inner wall surface of the upper surface recess of the insulating member 32 and penetrates the insulating member 32. As described above, since the bottom surface of the upper surface recess of the insulating member 32 is formed corresponding to the upper surface of the intermediate member 34, the lead 30 penetrating the insulating member 32 descends so as to abut on the side surface of the intermediate member 34. As a result, the lead 30 can be protected by the intermediate member 34. The lead 30 extends further downward and connects to the rod-shaped electrode 46. As a result, the lead 30 is ensured to be electrically conductive with the rod-shaped electrode 46. Then, the lower end of the lead 30 comes into contact with the receiving portion 37a of the protective member 36 to improve the conduction efficiency.

【0026】

The lead 30 is formed of a plurality of plate-shaped members, and the plurality of plate-shaped members are laminated and arranged. In the present embodiment, the lead 30 has three plate-shaped members laminated and arranged. Then, in the present embodiment, the upper end portion of the lead 30 is connected to a high frequency power supply (not shown). In this embodiment, a high frequency voltage having a frequency of 40.68 MHz is used. High-frequency power generated by a high-frequency power source (not shown) is conducted from the upper end of the lead 30, but such high-frequency power is conducted to the rod-shaped electrode 46 through the surface of the lead 30 instead of inside the lead 30. As described above, the reed 30 has a plurality of plate-shaped members laminated and arranged, but high-frequency power is conducted on the surface portion through the gaps between the plate-shaped members. In the present embodiment, since the three plate-shaped members are laminated and arranged, the conduction efficiency of high-frequency power can be tripled. As a result, a high frequency voltage can be efficiently applied to the rod-shaped electrode 46, and gas discharge can be performed at the high frequency voltage. By applying a high-frequency voltage to the rod-shaped electrodes 46 in this way, electrons vibrate at high frequencies between the rod-shaped electrodes 46 and 48, and the processing gas is turned into plasma by the collision of the electrons and becomes an excitation active species. Therefore, high-density plasma can be generated at a high generation rate, and abnormal discharge can be made less likely to occur. Further, even if the volume of the entire lead 30 is reduced, the electric power can be efficiently transmitted by increasing the surface area of the lead 30, and the local processing apparatus 20 can be made compact. Further, by using a high-frequency voltage having a frequency of 30 MHz or more, electrons vibrate between the rod-shaped electrodes 46 and 48 while maintaining the conduction efficiency of the high-frequency voltage, so that the electrons collide with the rod-shaped electrodes 46 and 48. Therefore, high-density plasma can be generated without damaging it, and processing efficiency can be improved.

【0027】

The lead 30 is made of copper and has a gold-plated surface. As a result, oxidation of the lead 30 can be prevented and high-frequency power can be stably conducted.

【0028】

Further, a hollow region 60 is formed between the casing member 21, the lead 30, the rod-shaped electrode 46, and the protective member 36 and the intermediate member 34. A form in which a dielectric material such as mica-based ceramics is arranged in the hollow region 60 to insulate is also conceivable. However, as shown in Fig. 3 (b), the relative permittivity of mica-based ceramics, which is a dielectric (insulator), is five times or more higher than that in the atmospheric atmosphere. As described above, it is possible to effectively maintain the insulation when conducting high-frequency power by providing a hollow region to form an insulating space rather than by filling the casing member 21 with a dielectric material. The inventor paid attention. Since the hollow region 60 is formed in this way, the insulation can be effectively maintained and the leakage current can be minimized. As a result, creeping discharge can be prevented more effectively, and the efficiency of producing excited active species such as plasma can be increased.

【0029】

Further, an air supply pipe 52 is provided on one side surface of the lower casing member 26, and an air discharge pipe 54 is provided on the other side surface of the lower casing member 26. The cooling air is guided into the casing member 21 from the air supply pipe 52. Then, heat is exchanged inside the casing member 21 through the hollow region 60 inside the casing member 21, and the heat is discharged from the air discharge pipe 54 to the outside of the casing member 21. As a result, it is possible to prevent an overheated state in the plasma generation process of the electrode, keep the temperature inside the casing member 21 constant, and stabilize the discharge. Then, it is possible to prevent the electrode portions (rod-shaped electrodes 46, 48, extension electrodes 49, leads 30) from being damaged due to thermal expansion or the like. The structure is not particularly limited to the above structure as long as the electrode portion in the casing member 21 can be air-cooled.

【0030】

The operation of the local processing device 20 configured as described above is as follows. In the local treatment device 20, the tip of the nozzle tip 44 faces above an object to be processed (not shown).

【0031】

The processing gas flows into the opening of the discharge pipe 40 provided on the side wall of the upper casing member 22. The processing gas travels in the discharge pipe 40 and descends in the casing member 21. In the lower casing member 26, a high frequency voltage is applied to the rod-shaped electrodes 46 and 48, and a gas discharge is generated in the discharge tube 40. In the present embodiment, since the voltage is applied at a high frequency, a high-density excitation active species can be generated. Since the excited active species are immediately sent onto the object to be treated from the nozzle tip 44, sufficient excited active species can be sent onto the object to be treated to perform surface treatment. Examples of the object to be processed include a semiconductor chip and a wafer. The treatment step includes etching, ashing, modification, thin film formation, and the like, but the application is not particularly limited to this.

【0032】

FIG. 3A shows a comparison diagram of the ashing rate between the local processing apparatus 20 of the example and the local processing apparatus of the comparative example. An example is a local treatment apparatus 20 in which the electrode portions (rod-shaped electrodes 46, 48, extension electrodes 49, leads 30) are plated with gold, and a comparative example is a local treatment apparatus in which the electrode portions are not plated. As the processing conditions, the He flow rate is 2 l / min, and O₂The flow rate is 30 ml / min. The distance from the tip of the nozzle tip to the object to be processed is about 0.5 mm. The outer diameter of the nozzle tip is 3.0 mm and the inner diameter is 1.5 mm. Comparing the ashing rates in the examples and the comparative examples under the above processing conditions, it can be seen that the efficiency can be increased more than three times even with the same output as shown in FIG. 3 (a).

【0033】

[Effect of the invention]

As described above, in the local processing apparatus according to the present invention, a pair of electrodes arranged to face each other so as to sandwich a discharge tube through which a processing gas flows, and a lead connecting one of the electrodes to a high frequency power source. An electrode portion was formed, and the surface of the electrode portion was plated. Therefore, even if gas discharge is continuously generated and the electrode portion generates heat, the surface of the electrode portion is protected by the plating treatment, so that the electrode portion can be protected from deterioration due to oxidation. In particular, even when the electrode portion is made of copper, oxidation of the surface of the electrode portion can be prevented and the performance can be reliably ensured. As a result, gas discharge can be generated stably and efficiently.

【0034】

Further, by using gold plating for the plating, the surface of the electrode portion can have a low electrical resistivity, the conduction efficiency can be increased, and the gas discharge generation efficiency can be increased.

【0035】

Further, by assuming that the high frequency power supply has an output frequency of 30 MHz or more, high frequency power can be effectively conducted and the efficiency of gas discharge generation can be increased.

【0036】

[Simple explanation of drawings]

[Figure 1]

It is sectional drawing which shows the local processing apparatus in embodiment of this invention.

[Figure 2]

It is the top view and the perspective view of the main part of the local processing apparatus in embodiment of this invention.

[Fig. 3]

It is explanatory drawing which shows the processing efficiency of the local processing apparatus in this invention, and the relative permittivity of a material.

[Explanation of symbols]

20 ......... Local surface treatment equipment 21 ......... Casing member 22 ......... Upper casing member 24 ......... Central casing member 26 ......... Lower casing member 28 ......... Bottom casing member 30 ......... Reed 32 ......... Insulation member 33 ......... Gas inflow hole 34 ......... Intermediate member 35 ......... Presser member 36 ......... Protective member 37 ......... Receiving part 39 ......... Partition 40 ......... Discharge tube 42 ......... Nozzle holder 44 ......... Nozzle tip 46 ......... Rod-shaped electrode 48 ......... Rod-shaped electrode 49 ......... Extension electrode 50 ......... Holder member 52 ......... Air supply pipe 54 ......... Air discharge pipe 60 ......... Hollow area 62 ......... Gas inflow pipe