Processing method

Description: TECHNICAL FIELD [Detailed description of the invention]

【0001】

[Technical field to which the invention belongs]

The present invention relates to a treatment method, and more particularly to a treatment method for removing an organic film layer formed on the surface of an object to be treated by generating plasma of a treatment gas in a vacuum treatment container, for example.

【0002】

[Conventional technology]

When forming the wiring of a semiconductor integrated circuit, for example, there is a step of forming a contact hole, a groove, or the like for wiring. In these steps, a resist film layer and an antireflection film layer are formed on an insulating film layer made of, for example, silicon oxide, and a contact hole or groove pattern is further formed by photolithography technology, and then a plasma processing apparatus is used. Etching is performed according to each shape to form a contact hole or a groove. After that, the resist film layer is removed by ashing using the same plasma processing apparatus or another plasma processing apparatus.

【0003】

For example, FIGS. 5A and 5B are diagrams showing a conventional ashing process. As shown in FIG. 5A, on the silicon layer 101 of the wafer, the photoresist film layer (PR film layer) 102 and the antireflection film layer (BARC (BOTTOM ANTI REFLECTION COATING) layer) 103 from the upper layer to the lower layer. , Silicon oxide film layer (SiO₂Membrane layer) 104 and silicon nitriding film layer (SiON film layer) 105 are formed, and further SiO₂Contact holes 106 are formed by etching in the film layer 104 and the SiON film layer 105. When ashing the PR film layer 202 shown in FIG. 5 (a), SiO is shown in FIG.₂The PR membrane layer 102 (including the BARC layer 103) on the membrane layer 104 is removed by ashing. For such a conventional treatment, for example, an aluminum chamber subjected to alumite treatment or an alumina chamber is used as a vacuum processing container (chamber) of the plasma processing apparatus.

【0004】

However, there is a problem that the chamber material is damaged by the plasma and particles are generated over time. In particular, when aluminum is contained in a chamber material such as aluminum or alumina, etching with a fluorine-based gas generates aluminum fluoride particles. Therefore, recently, for example, yttria (Y) is on the inner surface of the chamber.₂O₃) And other ceramics are sprayed to increase the plasma resistance of the chamber, and the regular cleaning cycle of the chamber is made as long as possible.

【0005】

[Problems to be Solved by the Invention]

However, etching is performed using a predetermined etching gas in a chamber subjected to ceramic spraying, for example, yttria spraying, and SiO is used as shown in FIG. 5 (a).₂A contact hole 106 is formed in the membrane layer 104, and subsequently, in the same chamber, for example, O₂When the PR film layer 102 is removed by ashing with a gas at a predetermined pressure (for example, 200 mTorr) as shown in (b) of the figure, SiO after ashing is performed.₂It has been found that crater-like depressions (hereinafter, simply referred to as "craters") 107 are generated by abnormal etching on the surface of the film layer 104, particularly around the contact hole 106.

【0006】

The present invention has been made to solve the above problems, and in order to enhance plasma resistance, ashing is performed in a vacuum processing container subjected to ceramic spraying containing a metal component such as yttria spraying to form an organic film layer under the organic film layer. It is an object of the present invention to provide a treatment method capable of remarkably suppressing the generation of craters due to abnormal etching in the lower film layer when it is removed from the film layer.

【0007】

[Means for solving problems]

The present invention has been made based on the above findings, and the treatment method according to claim 1 of the present invention is an organic film formed on the surface of an object to be treated by generating plasma of a treatment gas in a vacuum treatment container. In the treatment method for removing the layer, at least O is used as the treatment gas.₂A step of removing the organic film layer at the first pressure using a gas containing gas, and a step of removing the organic film layer at a second pressure higher than the first pressure using the same processing gas as this step. It is characterized by having a process of performing.

【0008】

Further, the processing method according to claim 2 of the present invention is characterized in that, in the invention according to claim 1, the first pressure is set to 100 mTorr or less.

【0009】

Further, in the treatment method according to claim 3 of the present invention, in the invention according to claim 1 or 2, the excess treatment rate of the organic film layer due to the first pressure is set to 15% or less. It is characterized by.

【0010】

Further, the treatment method according to claim 4 of the present invention is the invention according to any one of claims 1 to 3, wherein the excess treatment rate of the organic film layer due to the first pressure and the second It is characterized in that the total of the excess treatment rate of the organic film layer due to pressure is set to 100% or less.

【0011】

The treatment method according to claim 5 of the present invention is a treatment method for removing an organic film layer formed on the surface of an object to be treated by generating plasma of the treatment gas in a vacuum treatment container. As at least O₂It is characterized by having a step of removing the organic film layer at a pressure of 100 mTorr or less using a gas containing a gas.

【0012】

Further, the treatment method according to claim 6 of the present invention is characterized in that, in the invention according to claim 5, the excess treatment rate of the organic film layer is set to 15% or less.

【0013】

Further, the treatment method according to claim 7 of the present invention is at least O as the treatment gas in the invention according to claim 5 or 6.₂It is characterized by having a step of removing the organic film layer by switching a first pressure of 100 mTorr or less to a second pressure of more than 100 mTorr using a gas containing a gas.

【0014】

In addition, the treatment method according to claim 8 of the present invention is the overtreatment rate of the organic film layer by the first pressure and the overtreatment of the organic film layer by the second pressure in the invention according to claim 7. It is characterized in that the total with the rate is set to 100% or less.

【0015】

Further, the treatment method according to claim 9 of the present invention is described in the invention according to any one of claims 1 to 8, wherein the treatment gas is O.₂It is characterized by using gas.

【0016】

Further, in the processing method according to claim 10 of the present invention, in the invention according to any one of claims 1 to 9, the portion of the vacuum processing container that comes into contact with the plasma contains a metal component. It is characterized by that.

【0017】

Further, the processing method according to claim 11 of the present invention is characterized in that, in the invention according to claim 10, the metal component is yttrium.

【0018】

Further, the treatment method according to claim 12 of the present invention is characterized in that, in the invention according to claim 10, the portion containing the metal component is yttrium oxide.

【0019】

Further, the treatment method according to claim 13 of the present invention is characterized in that, in the invention according to any one of claims 1 to 12, the organic film layer is a resist layer. ..

【0020】

Further, in the treatment method according to claim 14 of the present invention, in the invention according to any one of claims 1 to 13, a silicon oxide film layer is formed under the organic film layer. It is characterized by.

【0021】

BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, the present invention will be described based on the embodiments shown in FIGS. 1 to 4. FIG. 1 is a cross-sectional view schematically showing a magnetron RIE type etching processing apparatus (hereinafter, simply referred to as processing apparatus) used when carrying out the processing method of the present invention. As shown in FIG. 1, for example, this processing device can move up and down to support an aluminum chamber 1 having itria spraying on the inner surface and a lower electrode 2 arranged in the chamber 1 via an insulating material 2A. Aluminum support 3 and a shower head (hereinafter, also referred to as "upper electrode" if necessary) 4 arranged above the support 3 and supplying process gas and also serving as an upper electrode. I have.

【0022】

The upper part of the chamber 1 is formed as a small-diameter upper chamber 1A, and the lower part is formed as a large-diameter lower chamber 1B. Upper chamber 1A is surrounded by a dipole ring magnet 5. The dipole ring magnet 5 is formed by accommodating a plurality of anisotropic segment columnar magnets in a casing made of a ring-shaped magnetic material, and forms a uniform horizontal magnetic field as a whole in the upper chamber 1A in one direction. .. An entrance / exit for loading / unloading the wafer W is formed in the upper part of the lower chamber 1B, and a gate valve 6 is attached to this entrance / exit. Further, a 13.56 MHz high frequency power supply 7 is connected to the lower electrode 2 via a matching unit 7A, a predetermined high frequency power is applied from the high frequency power supply 7 to the lower electrode 2, and the upper electrode 4 is provided in the upper chamber 1A. Form a vertical electric field with and. Therefore, in the upper chamber 1A, a magnetron discharge is generated by the electric field generated by the high-frequency power source 7 and the horizontal magnetic field generated by the dipole ring magnet 5 via the process gas, and plasma of the process gas supplied in the upper chamber 1A is generated.

【0023】

An electrostatic chuck 8 is arranged on the upper surface of the lower electrode 2, and a high-voltage DC power supply 9 is connected to the electrode plate 8A of the electrostatic chuck 8. Therefore, by applying a high voltage from the high-voltage DC power supply 9 to the electrode plate 8A under high vacuum, the wafer W is electrostatically attracted by the electrostatic chuck 8. A focus ring 10 made of single crystal silicon is arranged on the outer periphery of the lower electrode 2, and the plasma generated in the upper chamber 1A is collected on the wafer W. Further, an exhaust ring 11 attached to the upper part of the support 3 is arranged below the focus ring 10. A plurality of holes are formed in the exhaust ring 11 at equal intervals in the circumferential direction over the entire circumference, and the gas in the upper chamber 1A is exhausted to the lower chamber 1B through these holes.

【0024】

The support 3 can be raised and lowered between the upper chamber 1A and the lower chamber 1B via the ball screw mechanism 12 and the bellows 13. Therefore, when the wafer W is supplied onto the lower electrode 2, the lower electrode 2 descends together with the support 3 to the lower chamber 1B via the ball screw mechanism 12, and the gate valve 6 is opened to convey a transfer mechanism (not shown). The wafer W is supplied onto the lower electrode 2 via. Then, when processing the wafer W, the lower electrode 2 rises together with the support 3 via the ball screw mechanism 12, and the gap between the lower electrode 2 and the shower head 4 is set to a distance suitable for processing the wafer W. .. Further, a refrigerant flow path 2B connected to the refrigerant pipe 14 is formed inside the lower electrode 2, and the refrigerant circulates in the refrigerant flow path 2B via the refrigerant pipe 14 to adjust the wafer W to a predetermined temperature. .. Further, a gas flow path 2C is formed in each of the support 3, the insulating material 2A, the lower electrode 2, and the electrostatic chuck 8, and the space between the electrostatic chuck 8 and the wafer W is narrowed from the gas introduction mechanism 15 via the gas pipe 15A. For example, He gas is supplied as a backside gas at a predetermined pressure in the gap, and the thermal conductivity between the electrostatic chuck 8 and the wafer W is enhanced through the He gas. 16 is a bellows cover.

【0025】

A gas introduction portion 4A is formed on the upper surface of the shower head 4, and a gas supply system 18 is connected to the gas introduction portion 4A via a pipe 17. Gas supply system 18 is CF₄Gas source 18A, C₄F₈Gas source 18B, CH₂F₂Gas source 18C, O₂It has a gas supply source 18D, an Ar gas supply source 18E, and a CO gas supply source 18F. These gas sources 18A, 18B, 18C, 18D, 18E, 18F supply their respective gases via valves 18G, 18H, 18I, 18J, 18K, 18L and mass flow controllers 18M, 18N, 18O, 18P, 18Q, 18R. A single gas or a plurality of types of gases are appropriately selected according to the processing stage of the wafer W and supplied to the shower head 4 at a predetermined flow rate. When a plurality of types of gases are selected, inside the shower head 4. It is adjusted as a mixed gas having a predetermined compounding ratio. A plurality of holes 4B are evenly arranged on the lower surface of the shower head 4 over the entire surface, and a mixed gas is supplied as a process gas from the shower head 4 into the upper chamber 1A through these holes 4B. In FIG. 1, 1C is an exhaust pipe, and 19 is an exhaust mechanism composed of a vacuum pump or the like connected to the exhaust pipe 1C.

【0026】

Next, an embodiment of the processing method of the present invention using the above processing apparatus will be described with reference to FIGS. 2 to 4. FIG. 2 is a process of forming a contact hole, FIG. 3 is a process of ashing a photoresist layer (PR film layer), and FIG. 4 is an explanatory diagram illustrating a shoulder portion of the contact hole.

【0027】

First, a contact hole forming step using the above processing apparatus will be described with reference to FIGS. 2 (a) to 2 (c). On the silicon layer 201 of the wafer used in this step, as shown in FIG. 2 (a) in the previous step, the PR film layer 202 and the antireflection film layer (BARC layer) 203 are directed from the upper layer to the lower layer. , Silicon oxide film layer (SiO₂A film layer) 204 and a silicon oxynitride film layer (SiON film layer) 205 are formed, and a contact hole pattern 206 is further formed on the PR film layer 202 by a lithography technique.

【0028】

When forming a contact hole, the wafer W is etched with the above-mentioned processing apparatus under conventionally known etching conditions as shown in FIGS. 2A to 2C to form the contact hole. First, the BARC layer 203 is removed by etching. That is, the CF of the gas supply system 18₄Gas source 18A, O₂Open the valves 18G, 18J, 18K corresponding to the gas source 18D and Ar gas source 18E, connect these gas sources to the upper electrodes 4, and CF with the mass flow controllers 18M, 18P, 18Q.₄Gas, O₂The flow rate of gas and Ar gas is set to a predetermined flow rate (for example, CF).₄/ O₂Set to / Ar = 80/20 / 160sccm) and supply these process gases to the upper electrode 4. Further, the pressure in the chamber 1 is set to, for example, 40 mTorr via the exhaust mechanism 19. When a high frequency power of, for example, 1500 W is applied to the lower electrode 2 in this state, CF is applied between the lower electrode 2 and the upper electrode 4.₄Gas, O₂A plasma of a mixed gas of gas and Ar gas is generated, and the BARC layer 203 is etched and removed by this plasma (see (b) in FIG. 2).

【0029】

After the etching of the BARC layer 203 is completed, the residual gas is purged, the process gas is replaced, and SiO is used.₂A contact hole is formed in the membrane layer 204. C of gas supply system 18₄F₈Gas source 18B, O₂The gas supply source 18D and Ar gas supply source 18E are connected to the upper electrode 4 in the same manner as described above, and these process gases are passed through their respective flow rates (for example, C).₄F₈/ O₂/ Ar = 6/3 / 500sccm) and set the pressure in chamber 1 to, for example, 60m Torr. In this state, apply high-frequency power of, for example, 1500 W to the lower electrode 2, and C₄F₈Gas, O₂SiO by plasma of mixed gas of gas and Ar gas₂The film layer 204 is etched to form the contact hole 207 (see (c) in FIG. 2).

【0030】

SiO₂After the etching of the film layer 204 is completed, the residual gas is purged, the process gas is replaced, and SiO is used.₂The film layer 204 is overetched. For that, C₄F₈The gas supply source 18B, CO gas supply source 18F and Ar gas supply source 18E are connected to the upper electrode 4 in the same manner as described above, and these process gases are passed through their respective flow rates (for example, C).₄F₈(/ CO / Ar = 12/360 / 280sccm) and set the pressure in chamber 1 to, for example, 45m Torr. In this state, if a high frequency power of, for example, 1500 W is applied to the lower electrode 2, C₄F₈Plasma of mixed gas of gas, CO gas and Ar gas is generated, and SiO₂The film layer 204 is overetched. At this stage, the etching residue is attached to the SiON film layer 205 and the like.

【0031】

Therefore, the process gas is switched to remove the etching residue on the SiON film layer 205 by etching. For that, O₂The gas supply source 18D and Ar gas supply source 18E are connected to the upper electrode 4 in the same manner as described above, and these process gases are passed through their respective flow rates (for example, O).₂/ Ar = 20 / 100sccm) and set the pressure in chamber 1 to, for example, 40m Torr. In this state, apply high-frequency power of, for example, 500 W to the lower electrode 2, and O₂The deposits on the SiON film layer 205 are removed by etching for a short time with the plasma of a mixed gas of gas and Ar gas.

【0032】

After removing the upper deposits on the SiON film layer 205, the residual gas is purged, the process gas is replaced, and the SiON film layer 205 is etched. For that, CH₂F₂Gas source 18C, O₂The gas supply source 18D and Ar gas supply source 18E are connected to the upper electrode 4 in the same manner as described above, and these process gases are passed through their respective flow rates (for example, CH).₂F₂/ O₂/ Ar = 20/10/100 sccm) and set the pressure in chamber 1 to, for example, 80m Torr. In this state, apply high-frequency power of, for example, 500 W to the lower electrode 2, and CH₂F₂Gas, O₂The SiON film layer 205 shown in FIG. 2 (c) is removed by etching with a plasma of a mixed gas of gas and Ar gas, and a contact hole 207 is formed as shown in FIG. 3 (a).

【0033】

After forming the contact holes, the residual gas is purged, the process gas is replaced, and the PR film layer 202 is ashed in the same chamber 1 by the treatment method of the present invention. For that, O₂Connect the gas supply source 18D to the upper electrode 4 in the same way as above, and O₂The gas pressure and flow rate are set to predetermined values for carrying out the processing method of the present invention, respectively. In this state, apply high-frequency power of, for example, 300 W to the lower electrode 2, and O₂The PR film layer 202 is ashed by gas plasma to completely remove the state shown in FIG. 3 (a) to the state shown in FIG. 3 (b). In this embodiment, O is used as the processing gas.₂Although gas alone is used, NH is used as the processing gas.₃Gas alone or N₂Gas and H₂A mixed gas of gas may be used.

【0034】

In the treatment method of the present invention, it is preferable to ash the PR film layer 202 in two steps. That is, the processing method of the present invention is O.₂The first step of ashing the PR film layer 202 at the first pressure using gas, and O₂It consists of a second step of ashing the PR film layer 202 with a gas at a second pressure higher than the first pressure. The first pressure is preferably 100 mTorr or less, which is much lower than the conventional pressure (for example, 200 mTorr), and more preferably 50 to 20 mTorr. Since the first pressure is set to 100 mTorr or less, even if metal contamination by yttria on the PR layer 202 due to the yttria spraying part in chamber 1 occurs, abnormal etching due to yttrium is prevented and the contact hole 207 The PR film layer 202 can be removed without generating craters in the periphery. If the first pressure exceeds 100 mTorr, craters around the contact hole 206 due to yttrium contamination may occur, and if the first pressure is too low, craters may be prevented, but in Fig. 4 ( As shown in a), the shoulder loss 207A may increase.

【0035】

The shoulder loss 207A is quantitatively defined as follows. That is, as shown in (b) of FIG. 4, the extension line from the side wall of the contact hole 207 is L.₁And the extension line from the open end of the contact hole 207 is L₂And. And both extension lines L₁, L₂L the bisector of the suspended angle (approximately 90 °)₃And. This bisector L₃And shoulder intersection C, both extension lines L₁, L₂Bisection line L between the intersection of₃The length δ is the size of shoulder loss 207A. Therefore, the contact hole 207 should have a small shoulder loss as described above.

【0036】

The second pressure is preferably a high pressure, for example, a pressure exceeding 100 mTorr, preferably 200 to 300 mTorr, in order to suppress shoulder loss. The time when the first pressure is switched to the second pressure is the time when the PR film layer 202 is 100% ashed (hereinafter referred to as "just ashing") by the first pressure in order to suppress the shoulder loss 207A. preferable. At the time of overetching, CO is used by a conventionally known end point detector (not shown).₂It can be judged by detecting a change in a specific wavelength of a plasma active species such as. Further, if the pressure is switched to the second pressure before just ashing at the first pressure (100 mTorr or less), craters may be generated, which is not preferable.

【0037】

Therefore, the overtreatment rate of the PR film layer 202 due to the first pressure is preferably 15% or less, more preferably 0 to 10%. The excess treatment rate of the PR film layer 202 means a value obtained by dividing the amount of overashing of the PR film layer 202 by the film thickness of the PR film layer 202 as a percentage. If this excess treatment rate exceeds 15%, the shoulder loss 207A becomes large, which is not preferable. Further, the total of the excess treatment rate of the PR film layer 202 due to the first pressure and the excess treatment rate of the PR film layer 202 due to the second pressure is preferably 100% or less, more preferably 50 to 100%. If this total value exceeds 100%, the shoulder loss 207A becomes large, which is not preferable.

【0038】

Also, O for crater generation₂Besides the gas pressure, O₂Gas residence time, that is, O in chamber 1₂It is presumed that the residence time of the gas is involved. And O₂When the gas is at the first pressure (pressure of 100 mTorr or less), the longer the residence time is, the more the phenomenon of preventing the generation of craters is observed.₂On the contrary, when the gas has a second pressure (pressure exceeding 100 mTorr), the shorter the residence time, the more the phenomenon of preventing the generation of craters is observed. Also, O₂When the gas is at the first pressure, the phenomenon that the shoulder loss increases as the residence time becomes longer is observed. The residence time (τ) can be calculated by the following formula. τ = V / S = pV / Q (m seconds) However, V is the volume (L) obtained by multiplying the area of the wafer by the gap between the upper and lower electrodes, S is the exhaust velocity (L / sec) of the exhaust mechanism 19, p is the pressure in the chamber (Torr), and Q. Indicates the total gas flow rate (sccm). In addition, 1 Torr L / sec = 79.05 sccm.

【0039】

Further, the ashing and over-ashing of the PR film layer 202 can be performed only with the first pressure, that is, the pressure of 100 mTorr or less. In this case, it is possible to prevent the generation of craters around the contact hole 207. However, O₂As the gas residence time becomes longer, the shoulder loss of the contact hole 207 may increase as described above.

【0040】

As described above, according to the present embodiment, the plasma of the processing gas is generated in the chamber 1 in which the inner surface is sprayed with ceramics such as yttria spraying to remove the PR film layer 202 formed on the surface of the wafer W. When doing, O as a processing gas₂After removing the PR membrane layer 202 with a gas at a first pressure, eg 100 mTorr or less, O₂Since the PR film layer 202 was removed using a gas at a second pressure higher than the first pressure, for example, a pressure exceeding 100 mTorr, ceramic spraying containing metal components such as yttria spraying was performed in order to increase plasma resistance. SiO in the provided chamber 1₂After forming the contact hole 207 in the membrane layer 204, ashing is performed to SiO₂SiO when removing the resist film layer 202 from the film layer 204₂It is possible to prevent the generation of craters 107 (see FIG. 5 (b)) due to abnormal etching on the film layer 204, especially around the contact hole 207.

【0041】

Further, according to the present embodiment, the excess treatment rate of the PR film layer 202 due to the first pressure, for example, a pressure of 100 mTorr or less is set to 15% or less, so that the shoulder loss of the contact hole 207 is surely suppressed. be able to. Further, the total of the excess treatment rate of the PR film layer 202 due to the first pressure, for example, a pressure of 100 mTorr or less and the overtreatment rate of the PR film layer 202 due to the pressure of the second pressure, for example, 100 mTorr or less is set to 100% or less. Therefore, it is possible to prevent the generation of craters and suppress the shoulder loss 207A of the contact hole 207. In addition, the processing by the second pressure is omitted and O₂Even if the gas is set to a pressure of 100 mTorr or less and the PR film layer 202 is removed only by this pressure, the generation of craters around the contact hole 207 can be prevented. Also, O in chamber 1₂When the portion of the gas in contact with the plasma contains a metal component such as yttrium or yttria, it is possible to prevent the generation of craters around the contact hole 207. And SiO₂When the BARC layer 203 and the PR film layer 202 are formed as an organic film layer on the film layer 204, the contact hole 207 can be formed reliably and with high accuracy.

【0042】

[Example]

In this embodiment, the processing apparatus is set to the following process conditions, and SiO in which the contact hole 207 is formed is formed.₂The PR membrane layer 202 and the BARC layer 203 on the membrane layer 204 were ashed. At this time, the processing time at the first pressure and the processing time at the second pressure were changed, and the final overashing amount due to the first and second pressures was set to 340%. The total film thickness of the PR film layer 202 and the BARC layer 203 was 780 nm. The ashing rate at the first pressure was 936 nm / min and the ashing rate at the second pressure was 1140 nm / min.

【0043】

Example 1 In this example, O₂The first pressure of the gas is set to 20 mTorr, the PR film layer 202 and the BARC layer 203 are ashed (just Ashed) for 50 seconds under this pressure, then the second pressure is set to 200 mTorr, and the PR film is set under this pressure. Layer 202 and BARC layer 203 were ashed for 2 minutes and 19 seconds. As a result, no crater was generated around the contact hole 207. The shoulder loss 207A of the contact hole 207 at this time was 30.4 nm.

[Process conditions] 1. Lower electrode: 13.56MHz, 300W 2. Gap size between upper and lower electrodes: 27mm 3. O at the first pressure (20 m Torr)₂Gas flow rate = 50sccm O₂Gas residence time = 26.8msec 4. O at the second pressure (200m Torr)₂Gas flow rate = 900sccm O₂Gas residence time = 14.9msec 5. T and W / B temperatures: 60 ° C / 60 ° C However, T is the temperature of the upper electrode, W is the temperature of the chamber wall surface, and B is the temperature of the lower electrode. 6. Backside gas pressure (central / peripheral): 7/40 Torr [0044]

Example 2 In this example, O₂After setting the first and second pressures of the gas and the gas flow rate at each pressure to be the same as in the case of Example 1, and ashing the PR film layer 202 and the BARC layer 203 under the first pressure for 60 seconds, The PR film layer 202 and the BARC layer 203 were ashed under the second pressure for 2 minutes and 11 seconds. As a result, no crater was generated around the contact hole 207. The shoulder loss 207A of the contact hole 207 at this time was 34.1 nm, which was larger than that of Example 1.

【0045】

Example 3 In this example, O₂After setting the first and second pressures of the gas and the gas flow rate at each pressure to be the same as in the case of Example 1, and ashing the PR film layer 202 and the BARC layer 203 under the first pressure for 40 seconds, The PR film layer 202 and the BARC layer 203 were ashed under the second pressure for 2 minutes and 27 seconds. As a result, craters were slightly generated around the contact hole 207, but the craters could be significantly suppressed as compared with the conventional case. The shoulder loss 207A of the contact hole 207 at this time was 29.5 nm, which was smaller than that of Example 1.

【0046】

Example 4 In this example, O₂Set the gas pressure to a low pressure of 20 mTorr, which is the first pressure, and O₂The gas flow rate was set to 50 sccm in the same manner as in Examples 1 to 3, and 340% overashing was performed only under a pressure of 20 m Torr. As a result, no crater was generated around the contact hole 207. Further, the shoulder loss 207A of the contact hole 207 at this time was 62 nm, and the shoulder loss was larger than that in the case of Example 1.

【0047】

Example 5 In this example, O₂The ashing treatment was performed under the same conditions as in Example 4 except that the gas flow rate was changed to 150 sccm. At this time, the residence time is 8.9 msec. As a result, no crater was generated around the contact hole 207. The shoulder loss 207A of the contact hole 207 at this time was 45 nm, which was smaller than that of Example 4.

【0048】

Example 6 In this reference example, O₂The ashing treatment was performed under the same conditions as in Example 3 except that the gas flow rate was changed to 250 sccm. At this time, the residence time is 5.4 msec. As a result, a small amount of craters were generated around the contact hole 207, but the craters could be significantly suppressed as compared with the conventional case. The shoulder loss 207A of the contact hole 207 at this time was 35.3 nm, which was smaller than that of Examples 4 and 5.

【0049】

Also, from the viewpoint of suppressing the generation of craters, O at the first pressure₂The gas residence time is preferably 5 msec or more, and more preferably 10 msec or more. Further, in the above example, the first pressure was set to 20 mTorr, but it was confirmed that even at 60 mTorr, the shoulder loss tends to be suppressed as in the above example.

【0050】

Comparative example 1 In this comparative example, the PR layer film 202 and the BARC layer 203 were ashed by the conventional treatment method. That is, O₂Set the gas pressure to 200m Torr and O₂The gas flow rate was set to 900 sccm, and the treatment was performed for 3 minutes to perform 340% overashing. As a result, many clear craters with deep depressions were generated around the contact hole 207. However, the shoulder loss 207A of the contact hole 207 at this time was 18.8 nm, and the shoulder loss was smaller than that in each of the above examples. At this time, as a result of investigating the cases where the overashing was set to 30%, 50%, 100%, and 200%, it was confirmed that the larger the amount of overashing, the more remarkable the occurrence of craters.

【0051】

Comparative example 2 In this comparative example, O of Comparative Example 1₂The same treatment as in Comparative Example 1 was performed except that the gas flow rate was set to 300 mTorr. O at this time₂The gas residence time is 44.7 msec. As a result, more craters with clear dents were generated than the craters of Comparative Example 1.

【0052】

Further, as a result of performing the treatment up to immediately before ashing using a dummy wafer for metal contamination evaluation with a silicon oxide film separately from each of the above Examples and Each Comparative Example, in the yttria spraying chamber used in each of the above Examples. Yttria contamination of the dummy wafer surface is 10 in the treatment of¹¹Atom / cm²It was a stand. Yttria pollution is 10¹⁰Atom / cm²We also confirmed the occurrence of craters on the platform. On the other hand, as a result of performing the same treatment using the same dummy wafer in a chamber not subjected to yttria spraying, yttria contamination was 4.3 × 10.⁸Atom / cm²It was below (lower limit of measurement). In the case of the chamber without yttria spraying, no crater was generated regardless of the pressure.

【0053】

Based on the above Examples and Comparative Examples, the present inventors have created a crater after removing the PR film layer by ashing in a chamber in which plasma resistance is enhanced by ceramic spraying containing a metal component such as yttria. As a result of examining the cause of, the following reasoning was obtained. That is, SiO₂When the film layer 104 is etched, a deposited film (deposition) of an etching by-product (hereinafter referred to as "depot") is formed inside the chamber where yttria spraying is performed as ceramic spraying containing a metal component. Then, during the ashing of the PR film layer 102, the depot drops and accumulates on the wafer together with yttrium, and the metal components such as yttrium are SiO after the PR film layer is removed.₂It remains on the film layer 104, and that portion is selectively etched to generate craters. So O₂As a result of performing a series of treatments by variously changing the treatment conditions of the treatment gas such as gas as in each of the above examples, when the treatment gas was set to a lower pressure than the conventional (comparative example), yttrium was contained during ashing. Even if the depot falls on the PR film layer 102, the generation of craters can be prevented.

【0054】

The present invention is not limited to the above embodiment. For example, the present invention can be applied even when yttria thermal spraying is applied to other parts inside the chamber such as the upper electrode. In short, when removing an organic film layer such as a PR film layer formed on the surface of an object to be treated in a vacuum processing container containing a metal component in a portion in contact with plasma, at least O₂Any processing method may be used in which the pressure of the processing gas containing the gas is set to a low pressure remarkably lower than the conventional pressure (for example, 200 mTorr), and such an invention is included in the present invention.

【0055】

[Effect of the invention]

According to the inventions of claims 1 to 14, of the present invention, in order to enhance plasma resistance, ashing is performed in a vacuum treatment container subjected to ceramic spraying containing a metal component such as Itria spray to form an organic film layer. It is possible to provide a treatment method capable of remarkably suppressing the generation of craters due to abnormal etching in the lower layer film layer when removing from the lower layer film layer.

[Simple explanation of drawings]

[Figure 1]

It is a block diagram which shows the magnetron RIE type etching processing apparatus used in the processing method of this invention.

[Figure 2]

It is a process drawing which shows the process of forming a contact hole by using the etching process apparatus shown in FIG.

[Fig. 3]

It is a process diagram which shows the process of ashing a PR film layer by the processing method of this invention using the etching processing apparatus shown in FIG.

[Fig. 4]

It is explanatory drawing for demonstrating the shoulder loss of the contact hole formed in the process shown in FIG. 2 and FIG.

[Fig. 5]

It is a process diagram which shows the process of ashing a PR film layer by a conventional processing method using the etching processing apparatus shown in FIG.

[Explanation of symbols]

1 chamber W wafer (processed object) 202 PR Membrane Layer (Organic Membrane Layer) 203 BARC layer (organic film layer) 204 SiO₂Membrane layer 207 contact hole