JP2013070098A - Substrate processing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a substrate processing method forming an opening which has a size that meets a demand of downsizing of a semiconductor device and is used for transferring the shape to a film to be etched in a mask film or an intermediate layer of a substrate to be processed.SOLUTION: In a silicon substrate 70 where a lower layer resist film 71 of amorphous carbon, an SiON film 72 serving as a hard mask, an anti-reflection film 73, and a photoresist film 74 are sequentially laminated, a shrink process where a depot 76 is deposited on a side wall surface of an opening 75 of the photoresist film 74 by plasma generated from a mixed gas, formed by a CFI gas and an Hgas, to shrink an opening width of the opening 75 and an etching process where the anti-reflection film 73 and the SiON film 72 are etched are performed in one step.

Description

  The present invention relates to a substrate processing method, and more particularly, to a substrate processing method for processing a substrate in which a processing target layer, an intermediate layer, and a mask layer are sequentially stacked.

  An oxide film containing impurities formed on a silicon substrate by CVD or the like, such as a TEOS (Tetra Ethyl Ortho Silicate) film, a conductive film such as a TiN film, an antireflection film (BARC film), and a photoresist film are sequentially stacked. A wafer for a semiconductor device is known (see, for example, Patent Document 1). The photoresist film is formed in a predetermined pattern by photolithography, and functions as a mask when the antireflection film and the conductive film are etched.

  In recent years, with the progress of miniaturization of semiconductor devices, it has become necessary to form circuit patterns on the wafer surface as described above more finely. In order to form such a fine circuit pattern, in the process of manufacturing a semiconductor device, the minimum dimension of the pattern in the photoresist film is reduced, and an opening (via hole or trench) having a small dimension is used as a film to be etched. Need to form.

JP 2006-190939 A

  However, although the minimum dimension of the pattern in the photoresist film is defined by the minimum dimension that can be developed by photolithography, there is a limit to the minimum dimension that can be mass-produced by photolithography due to variations in focal length. For example, the minimum dimension that can be mass-produced by photolithography is about 80 nm. On the other hand, the processing dimension that satisfies the demand for miniaturization of semiconductor devices is about 30 nm.

  As described above, the size required for downsizing of semiconductor devices is further reduced, and it is desired to develop a technique for forming an opening having a size satisfying the size reduction required in a film to be etched.

  SUMMARY OF THE INVENTION An object of the present invention is to provide a substrate processing for forming an opening in a mask film or an intermediate film, which has an opening having a size that satisfies the requirements for miniaturization of a semiconductor device with respect to a substrate to be processed. It is to provide a method.

  In order to achieve the above object, the substrate processing method according to claim 1, wherein a processing target layer, an intermediate layer, and a mask layer are sequentially laminated, and the mask layer has an opening that exposes a part of the intermediate layer. A substrate processing method for processing an opening width reducing step of depositing a deposit on a side wall surface of the opening of the mask layer by plasma generated from a mixed gas of an anisotropic etching gas and hydrogen gas; and A shrink etching step for performing the etching step for etching the intermediate layer forming the bottom of the opening in one step is provided.

  The substrate processing method according to claim 2 is the substrate processing method according to claim 1, wherein the anisotropic etching gas contains bromine (Br) or a halogen element having a larger atomic number than bromine (Br), carbon and fluorine. It is characterized by containing gas.

The substrate processing method according to claim 3 is the substrate processing method according to claim 2, wherein the anisotropic etching gas is CF ₃ I gas or CF ₃ Br gas.

  The substrate processing method according to claim 4 is the substrate processing method according to any one of claims 1 to 3, wherein a mixing ratio of the anisotropic etching gas and the hydrogen gas in the shrink etching step is 4. 1 to 2: 3.

  The substrate processing method according to claim 5 is the substrate processing method according to any one of claims 1 to 4, wherein a bias power of 100 W to 500 W is applied to the substrate in the shrink etching step. To do.

  The substrate processing method according to claim 6 is the substrate processing method according to any one of claims 1 to 5, wherein, in the shrink etching step, a pressure in a chamber accommodating the substrate is 2.6 Pa (20 mTorr) or more. It is characterized by adjusting to 2 × 10 Pa (150 mTorr).

  The substrate processing method according to claim 7 is the substrate processing method according to any one of claims 1 to 6, wherein the intermediate layer to be etched is laminated below the mask layer in the shrink etching step. The antireflection film and the silicon-containing film, the antireflection film and the metal film, or the silicon-containing organic film.

  The substrate processing method according to claim 8 is the substrate processing method according to any one of claims 1 to 7, wherein an opening corresponding to an opening of the mask layer, the opening width of which is reduced by the shrink etching step. And a processing target layer etching step of transferring the opening of the intermediate layer having a portion to the processing target layer.

  According to the substrate processing method of claim 1, the opening width reducing step of depositing the deposit on the side wall surface of the opening of the mask layer by the plasma generated from the mixed gas of the anisotropic etching gas and hydrogen gas, and the opening Since the etching step for etching the intermediate layer forming the bottom of the part is performed in a single step, the depositing action by the gas generated by the reaction between the anisotropic etching gas and the hydrogen gas, and the anisotropic etching By the synergistic action with the etching action of the gas, an opening pattern having a size that satisfies the miniaturization requirement of the semiconductor device and that is to be transferred to the processing target layer can be formed in the intermediate layer.

  According to the substrate processing method of claim 2, the anisotropic etching gas is bromine (Br) or a gas containing a halogen element having a larger atomic number than bromine (Br), carbon and fluorine. The plasma generated from the etching gas can reach the bottom of the opening, and thus, for example, the intermediate film can be etched while suppressing deposition of deposits on the bottom.

According to the substrate processing method of the third aspect, since the anisotropic etching gas is CF ₃ I gas or CF ₃ Br gas, the deposit deposition suppressing effect on the bottom of the opening and the intermediate film etching effect are improved. .

  According to the substrate processing method of claim 4, since the mixing ratio of the anisotropic etching gas and the hydrogen gas in the shrink etching step is set to 4: 1 to 2: 3, the depositing action of the deposit on the side wall of the opening is performed. And the intermediate film etching action at the bottom of the opening can be adjusted, whereby the opening width can be reduced and the intermediate film at the bottom of the opening can be etched.

  According to the substrate processing method of the fifth aspect, since a bias power of 100 W to 500 W is applied to the substrate in the shrink etching step, the deposition effect on the side wall of the opening and the etching effect of the bottom intermediate film can be obtained without difficulty. It is done.

  According to the substrate processing method of the sixth aspect, in the shrink etching step, the pressure in the chamber for accommodating the substrate is adjusted to 2.6 Pa (20 mTorr) to 2 × 10 Pa (150 mTorr). Can be prevented.

  According to the substrate processing method of claim 7, in the shrink etching step, the intermediate layer to be etched is an antireflection film and a silicon-containing film, an antireflection film and a metal film, or a silicon-containing organic layer laminated below the mask layer. Since the films are formed, openings having dimensions that satisfy the requirements for miniaturization of semiconductor devices similar to the mask layer can be formed in these intermediate layers.

  9. The substrate processing method according to claim 8, wherein the opening of the intermediate layer having the opening corresponding to the opening of the mask layer whose opening width is reduced by the shrink etching step is transferred to the processing target layer. Since the step is included, an opening having a size that satisfies the demand for miniaturization of the semiconductor device can be transferred to the processing target layer.

It is a top view which shows roughly the structure of the substrate processing system which performs the substrate processing method which concerns on this Embodiment. It is sectional drawing which follows the line II-II in FIG. FIG. 2 is a cross-sectional view schematically showing a configuration of a semiconductor wafer to be subjected to plasma processing in the substrate processing system of FIG. It is process drawing which shows the substrate processing method in the 1st Embodiment of this invention. It is process drawing which shows the substrate processing method in the 2nd Embodiment of this invention. It is process drawing which shows the substrate processing method in the 3rd Embodiment of this invention.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

  First, a substrate processing system that executes a substrate processing method according to an embodiment of the present invention will be described. This substrate processing system includes a plurality of process modules configured to perform an etching process or an ashing process using plasma on a semiconductor wafer Q (hereinafter simply referred to as “wafer Q”) as a substrate.

  FIG. 1 is a plan view schematically showing a configuration of a substrate processing system for executing a substrate processing method according to the present embodiment.

  In FIG. 1, a substrate processing system 10 has a hexagonal transfer module 11 in plan view, two process modules 12 and 13 connected to one side surface of the transfer module 11, and the two process modules 12 and 13. The two process modules 14 and 15 connected to the other side of the transfer module 11, the process module 16 adjacent to the process module 13 and connected to the transfer module 11, and the process module 15 adjacent to and connected to the transfer module 11. A process module 17, a loader module 18 serving as a rectangular transfer chamber, and two load / lock modules 19 and 20 arranged between the transfer module 11 and the loader module 18 to connect them. Provided.

  The transfer module 11 has a transfer arm 21 that can be bent and extended and disposed inside the transfer module 11, and the transfer arm 21 transfers the wafer Q between the process modules 12 to 17 and the load lock modules 19 and 20.

The process module 12 has a processing chamber container (chamber) that accommodates the wafer Q, and a CF-based deposition gas such as CHF ₃ gas and a halogen-based gas such as HBr gas is used as a processing gas in the chamber. The plasma is generated from the introduced processing gas by introducing and generating an electric field inside the chamber, and the wafer Q is etched by the plasma.

  2 is a cross-sectional view taken along line II-II in FIG.

In FIG. 2, the process module 12 includes a processing chamber (chamber) 22, a mounting table 23 for the wafer Q disposed in the chamber 22, and a shower disposed above the chamber 22 so as to face the mounting table 23. TM for exhausting the gas in the head 24 and the chamber 22
It has a P (Turbo Molecular Pump) 25 and an APC (Adaptive Pressure Control) valve 26 as a variable butterfly valve that is disposed between the chamber 22 and the TMP 25 and controls the pressure in the chamber 22.

  A first high-frequency power source 27 and a second high-frequency power source 35 are connected to the mounting table 23 via a first matcher (matcher) 28 and a second matcher (matcher) 36, respectively. The high frequency power source 27 applies a relatively high frequency, for example, 60 MHz high frequency power as excitation power to the mounting table 23, and the second high frequency power source 35 mounts a relatively low frequency, for example, 2 MHz high frequency power as a bias. Apply to the pedestal 23. Accordingly, the mounting table 23 functions as a lower electrode that applies high-frequency power to the processing space R between the mounting table 23 and the shower head 24. The matching units 28 and 36 reduce the reflection of the high frequency power from the mounting table 23 to maximize the supply efficiency of the high frequency power to the mounting table 23.

  The shower head 24 includes a disk-shaped lower layer gas supply unit 29 and a disk-shaped upper layer gas supply unit 30, and the upper layer gas supply unit 30 is stacked on the lower layer gas supply unit 29. The lower gas supply unit 29 and the upper gas supply unit 30 have a first buffer chamber 31 and a second buffer chamber 32, respectively. The first buffer chamber 31 and the second buffer chamber 32 communicate with the inside of the chamber 22 through gas vent holes 33 and 34, respectively.

The first buffer chamber 31 is connected to, for example, a CHF ₃ gas supply system (not shown). The CHF ₃ gas supply system supplies CHF ₃ gas to the first buffer chamber 31. The supplied CHF ₃ gas is supplied into the chamber 22 through the gas vent 33. The second buffer chamber 32 is connected to, for example, an HBr gas supply system (not shown). The HBr gas supply system supplies HBr gas to the second buffer chamber 32. The supplied HBr gas is supplied into the chamber 22 through the gas vent 34. A DC power supply 45 is connected to the shower head 24, and a DC voltage is applied to the shower head 24 by the DC power supply 45. Thereby, the applied DC voltage controls the ion distribution in the processing space R.

  In the chamber 22 of the process module 12, as described above, the mounting table 23 applies high frequency power to the processing space R, so that the processing gas supplied from the shower head 24 to the processing space R is converted into high-density plasma. Then, ions and radicals are generated, and the wafer Q is etched by the ions and radicals.

Returning to FIG. 1, the process module 13 has a processing chamber (chamber) that accommodates the wafer Q that has been etched in the process module 12, and a mixed gas of O ₂ gas and N ₂ gas is used as a processing gas inside the chamber. Then, plasma is generated from the introduced processing gas by generating an electric field inside the chamber, and the wafer Q is etched by the plasma. The process module 13 has the same configuration as the process module 12. For example, instead of the CHF ₃ gas supply system and the HBr gas supply system, the O ₂ gas supply system and the N ₂ gas supply system (both not shown). Is provided. Note that the etching process in the process module 13 may also serve as the ashing process.

The process module 14 has a processing chamber (chamber) that accommodates the wafer Q that has been subjected to the etching process in the process module 13, introduces O ₂ gas as a processing gas into the chamber, and generates an electric field inside the chamber. Plasma is generated from the processing gas introduced by the step, and an ashing process is performed on the wafer Q by the plasma. The process module 14 has the same configuration as that of the process module 12 and supplies O ₂ gas instead of the shower head 24 including the disk-shaped lower gas supply unit 29 and the disk-shaped upper gas supply unit 30. The system includes a shower head (none of which is shown) consisting only of a disk-shaped gas supply unit connected to a buffer chamber.

  The interiors of the transfer module 11 and the process modules 12 to 17 are maintained in a reduced pressure state, and the transfer module 11 and each of the process modules 12 to 17 are connected to each other via vacuum gate valves 12a to 17a.

  In the substrate processing system 10, the internal pressure of the loader module 18 is maintained at atmospheric pressure, while the internal pressure of the transfer module 11 is maintained at vacuum. Therefore, each load / lock module 19, 20 includes a vacuum gate valve 19 a, 20 a at a connection portion with the transfer module 11, and an atmospheric door valve 19 b, 20 b at a connection portion with the loader module 18. It is configured as a vacuum preliminary transfer chamber that can adjust the internal pressure. Each load / lock module 19, 20 has a wafer mounting table 19 c, 20 c for temporarily mounting the wafer Q delivered between the loader module 18 and the transfer module 11.

  In addition to the load / lock modules 19 and 20, the loader module 18 has, for example, three hoop mounting tables 38 on which hoops (Front Opening Unified Pods) 37 as containers for storing, for example, 25 wafers Q are respectively mounted. An orienter 39 for pre-aligning the position of the wafer Q unloaded from the hoop 37 is connected.

  The load / lock modules 19 and 20 are connected to the side wall along the longitudinal direction of the loader module 18 and are disposed so as to face the three hoop mounting tables 38 with the loader module 18 interposed therebetween. Arranged at one end in the longitudinal direction.

  The loader module 18 includes a scalar type dual arm type transfer arm 40 that transfers the wafer Q, and 3 as an inlet for the wafer Q that is arranged on the side wall so as to correspond to each hoop mounting table 38. And two load ports 41. The transfer arm 40 takes out the wafer Q from the hoop 37 placed on the hoop placement table 38 via the load port 41, and carries the taken-out wafer Q to the load / lock modules 19, 20 and the orienter 39.

  In addition, the substrate processing system 10 includes an operation panel 42 disposed at one end in the longitudinal direction of the loader module 18. The operation panel 42 has a display unit made up of, for example, an LCD (Liquid Crystal Display), and the display unit displays the operation status of each component of the substrate processing system 10.

  FIG. 3 is a cross-sectional view schematically showing a configuration of a semiconductor wafer to be subjected to plasma processing in the substrate processing system of FIG.

  In FIG. 3, a wafer Q includes an amorphous carbon film (lower resist film) 51 as a processing target layer formed on the surface of a silicon substrate 50, and a SiON film (hard mask) 52 formed on the amorphous carbon film 51. And an antireflection film (BARC film) 53 formed on the SiON film 52 and a photoresist film 54 (mask layer) formed on the antireflection film 53.

The silicon substrate 50 is a disk-shaped thin plate made of silicon, and the amorphous carbon film 51 is formed on the surface by performing, for example, a CVD process. The amorphous carbon film 51 functions as a lower resist film. A CVD process or a PVD process is performed on the amorphous carbon film 51 to form a SiON film 52 on the surface, and an antireflection film 53 is formed on the SiON film 52 by, for example, a coating process. The antireflection film 53 is made of a polymer resin containing a dye that absorbs light of a specific wavelength, for example, ArF excimer laser light irradiated toward the photoresist film 54, and the ArF excimer transmitted through the photoresist film 54. This prevents the laser light from being reflected by the SiON film 52 and reaching the photoresist film 54 again. The photoresist film 54 is formed on the antireflection film 53 using, for example, a spin coater (not shown). The photoresist film 54 is made of a positive type photosensitive resin, and when irradiated with ArF excimer laser light, the photoresist film 54 is changed to alkali-soluble.

  The wafer Q having such a configuration is irradiated with ArF excimer laser light corresponding to a pattern inverted to a predetermined pattern by a stepper (not shown), and the ArF excimer laser light in the photoresist film 54 is irradiated with the ArF excimer laser light. The irradiated part is transformed into alkali-soluble. Thereafter, a strongly alkaline developer is dropped onto the photoresist film 54 to remove the portion that has been altered to alkali solubility. As a result, the portion corresponding to the pattern that is inverted to the predetermined pattern is removed from the photoresist film 54, so that a predetermined pattern is formed on the wafer Q, for example, a photoresist having an opening 55 at a position where a via hole is formed. The membrane 54 remains.

  By the way, in order to satisfy the demand for miniaturization of a semiconductor device, an opening (via hole or trench) having a small size, specifically, a width (CD (Critical Dimension) value) of about 25 to 30 nm is formed in a film to be etched. There is a need to. However, since the minimum dimension that can be mass-produced by photolithography is, for example, about 80 nm, it is difficult to form an opening having an opening width that satisfies the requirements for miniaturization of the semiconductor device in the etching target film in the etching process of the wafer Q. It was.

The present inventor conducted various experiments in order to find out a method for forming an opening having an opening width satisfying the above-described miniaturization requirement of the semiconductor device on the wafer Q. As a result, the amorphous carbon film 51 as the processing target layer, the hard In a wafer Q in which a SiON film 52 as a coating layer, an antireflection film (BARC film) 53, and a photoresist film 54 having an opening 55 exposing a part of the antireflection film 53 are sequentially laminated on a silicon substrate 50. The photoresist film 54 is subjected to plasma treatment using a CF-based deposition gas having a specific gas adhesion coefficient S (C _x H _y F _z , where x, y, z are 0 or a positive integer). It has been found that deposits are deposited on the side wall surface of the opening 55 provided in the substrate and the opening width is narrowed (shrinked).

From the above findings, the present inventor found that the opening width of the photoresist film after the shrink process finally becomes a predetermined width depending on the type of the deposition gas applied to the plasma process, in other words, the gas adhesion coefficient S. Based on this hypothesis, the convergence and the aperture width after convergence meet the above-mentioned requirements for miniaturization of semiconductor devices. Based on this hypothesis, the type of deposition gas applied to plasma processing and the gas adhesion coefficient As a result of various examinations on processing conditions, processing time, etc., plasma treatment is performed under predetermined conditions by applying a CF-based deposition gas having a gas adhesion coefficient S of S = 0.1 to 1.0, for example, CHF ₃ gas. As a result, it was found that a wafer Q provided with a photoresist film having a target opening width, for example, an opening of 25 nm to 30 nm was obtained, and the present invention was achieved.

  Hereinafter, the substrate processing method according to the first embodiment of the present invention will be described in detail.

  In this substrate processing method, the opening width of the opening 55 formed in the photoresist film 54 of the wafer Q is reduced by attaching a deposit based on the plasma processing to the side wall surface of the opening 55. Then, after the opening width is reduced, an etching step for transferring the pattern of the opening 55 with the reduced opening width to the amorphous carbon film 51 that is the processing target layer is included.

  FIG. 4 is a process diagram showing the substrate processing method according to the first embodiment of the present invention.

  In FIG. 4, first, an amorphous carbon film 51 as a lower resist film, an SiON film 52 as a hard mask, an antireflection film (BARC film) 53, and a photoresist film 54 are sequentially laminated on a silicon substrate 50. A wafer Q is prepared in which the film 54 has an opening 55 that exposes a part of the antireflection film 53 with an opening width, for example, 60 nm (FIG. 4A). Then, the wafer Q is carried into the chamber 22 of the process module 12 (see FIG. 2) and placed on the mounting table 23.

Next, the pressure in the chamber 22 is set to, for example, 1 × 10 Pa (75 mTorr) by the APC valve 26 or the like. Further, the temperature of the wafer Q is set to 50 ° C., for example. Then, CHF ₃ gas is supplied into the chamber 22 at a flow rate of, for example, 300 sccm from the lower layer gas supply unit 29 of the shower head 24. Then, 750 W as excitation power and 300 W as bias power are supplied to the mounting table 23, and a DC voltage of 300 V is applied to the shower head 24. At this time, the CHF ₃ gas is excited by the high-frequency power applied to the processing space R to become plasma, and ions and radicals are generated (FIG. 4B). These ions and radicals collide with and react with the surface of the photoresist film 54 or the side wall surface of the opening, and deposit the deposit 56 in that portion (FIG. 4C).

  The thickness of the deposition 56 gradually increases from the start of the process, and becomes 35 nm (opening width: 25 nm), for example, 3 minutes after the start of the process. Through this opening width reduction step (hereinafter, sometimes referred to as “shrink step”), the opening width of the opening 55 could be reduced from 60 nm to 25 nm.

  At this time, it is derived from the theoretical formula that the deposition rate of the deposit 56 deposited on the side wall surface of the opening 55 is proportional to the opening width W of the opening 55. That is, the deposition rate of the deposit on the side wall surface of the opening 55 is expressed by the following theoretical formula.

  Here, S is the gas adhesion coefficient, z is the distance from the bottom of the opening, W is the opening width, and L is the height (depth) of the opening.

  From the above theoretical formula, it can be seen that the deposition rate of the deposit 56 deposited on the side wall of the opening 55 depends on the width W of the opening. That is, if the gas adhesion coefficient is the same, the deposition rate of the deposit 56 increases as the opening width W of the opening 55 increases, and decreases as the opening width decreases. Further, if the gas deposition coefficient is the same, the deposit deposition thickness increases as the opening width W of the opening 55 increases, and decreases as the opening width decreases. The opening width of the opening 55 after depositing converges to a predetermined width depending on the type of deposition gas, that is, the gas deposition coefficient, with the processing time, and the shrinkage ratio in the portion where the initial opening width is large is the initial opening width. Is larger than the shrinkage ratio in the small portion. Therefore, in order to obtain the target opening width, it is effective to use a deposition gas having a gas adhesion coefficient that can obtain the opening width.

Here, the deposition gas is a gas having a function of reducing the opening width by depositing the deposit 56 on the sidewall surface of the opening 55 of the photoresist film 54 as a mask layer, for example, by plasma treatment using the gas. Say. The CHF ₃ gas has a gas adhesion coefficient S of, for example, S = 0.5, and an aperture width convergence value of, for example, 20 to 25 nm.

  Next, for the wafer Q including the photoresist film 54 having the opening 55 whose opening width is reduced to 25 nm by the shrink step, the opening formed in the photoresist film 54 according to the normal condition is used as the processing target layer. An etching process for transferring to the amorphous carbon film 51 is performed.

That is, the pressure in the chamber 22 of the process module 12 containing the wafer Q in which the opening width of the opening film 55 of the photoresist film 54 is reduced to 25 nm is set to, for example, 1 × 10 Pa (75 mTorr) by the APC valve 26 or the like. After the temperature of the wafer Q is set to 50 ° C., for example, CF ₄ gas is supplied from the lower layer gas supply unit 29 of the shower head 24 into the chamber 22 at a flow rate of 220 sccm, and CHF ₃ gas is supplied from the upper layer gas supply unit 30 to a flow rate of 250 sccm. To supply into the chamber 22. Then, 750 W as excitation power and 0 W as bias power are supplied to the mounting table 23, and a DC voltage of 300 V is applied to the shower head 24. At this time, CF ₄ gas and CHF ₃ gas become plasma by the high-frequency power applied to the processing space R, and ions and radicals are generated. These ions and radicals collide with and react with a portion of the antireflection film 53 that is not covered by the photoresist film 54 to etch the antireflection film 53 and the portion of the SiON film 52 underneath (FIG. 4D). ). The antireflection film 53 and the SiON film 52 in the portion are etched until the amorphous carbon film 51 is exposed (FIG. 4E).

  In this way, the opening width of the opening 55 of the photoresist film 54 is reduced, and the wafer Q on which the antireflection film 53 and the SiON film 52 are etched is carried out of the chamber 22 of the process module 12 to transfer the transfer module. 11 is carried into the chamber of the process module 13 via 11 and placed on the mounting table.

Next, the pressure in the chamber is set to 2.6 Pa (20 mTorr) by an APC valve or the like. Then, O ₂ gas is supplied from the lower layer gas supply unit of the shower head into the chamber at a flow rate of 180 sccm, and N ₂ gas is supplied from the upper layer gas supply unit into the chamber at a flow rate of 20 sccm. Then, 1000 W of excitation power is supplied to the mounting table, and the bias power is set to 0 W. At this time, O ₂ gas and N ₂ gas become plasma by the high frequency power applied to the processing space R, and ions and radicals are generated. These ions and radicals are portions of the amorphous carbon film 51 that are not covered with the photoresist film 54, the deposit 56 deposited on the sidewall surface of the opening 55 of the photoresist film 54, and the antireflection film 53 and the SiON film 52. It reacts with and reacts with and etches the part (FIG. 4F). The portion of the amorphous carbon film 51 is etched until the silicon substrate 50 is exposed, and an opening having a width of 25 nm is formed in the amorphous carbon film 51. At this time, the photoresist film 54, the deposit 56 deposited on the side wall surface and the upper surface of the opening 55 of the photoresist film 54, and the antireflection film 53 are simultaneously removed (FIG. 4G).

  Thereafter, the wafer Q is unloaded from the chamber of the process module 13 and the process is terminated.

In this case, the shrinking step for depositing the deposit 56 on the inner wall surface of the opening 55 of the photoresist film 54 and the opening width of the opening 55 of the photoresist film 54 reduced by the shrinking step, the antireflection film 53. In addition, the etching step of transferring the opening width transferred to the SiON film 52 to the amorphous carbon film 51 can be continuously performed in the same chamber.

  According to the present embodiment, a plasma treatment is performed using a deposition gas having a gas adhesion coefficient S of S = 0.1 to 1.0, so that the deposition is performed on the sidewall surface of the opening 55 of the photoresist film 54. 56 can be deposited to reduce the opening width. If the deposit 56 is deposited on the side wall surface of the opening 55 of the photoresist film 54 and the width of the opening 60 nm is adjusted to, for example, 25 nm, the amorphous carbon film 51 as the processing target layer also has a width of 25 nm based on this. Thus, an opening having a size that satisfies the demand for miniaturization of the semiconductor device can be formed in the amorphous carbon film 51 as the processing target layer.

In the present embodiment, the deposition gas is represented by the general formula C _x H _y F _z (x, y, z is 0 or a positive integer), and the gas adhesion coefficient S is S = 0.1-1. 0, preferably S = 0.1 to 0.5. The CHF ₃ gas has a gas adhesion coefficient S of about S = 0.5, and the convergence aperture width is, for example, 20 to 25 nm. As the deposition gas, in addition to CHF ₃ gas, CH ₂ F ₂ gas, CH ₃ F gas, C ₅ F ₈ gas, C ₄ F ₆ gas, CF ₄ gas, CH ₄ gas, etc. can be used. The deposition gas can meet the recent demand for device miniaturization, and the opening width of the opening 55 formed in the photoresist film 54 of the wafer Q in the shrink step can be reduced and converged to, for example, 25 to 30 nm. .

  In this embodiment mode, the bias power during the etching process is preferably 100 W to 500 W. When the bias power is less than 100 W, deposition on the side wall of the opening is insufficient. On the other hand, when the bias power exceeds 500 W, the photoresist film 54 is roughened by sputtering. When the bias power is 100 W to 500 W, it is possible to reduce the opening width by suppressing the diffusion of the deposition gas and depositing the deposit 56 having a uniform thickness on the side wall surface of the opening. The treatment temperature is not particularly limited and is usually 20 ° C. to 100 ° C., but is preferably room temperature for practical use.

  In this embodiment, the etching process time is 0.5 minutes to 3 minutes. This is because the deposition rate is the fastest at the start of etching, then gradually slows down, and becomes almost zero after 3 minutes, and the opening width converges to a predetermined width. Therefore, it is possible to control the deposition thickness by controlling the processing time.

  In this embodiment, instead of the SiON film 52 as a hard mask and the antireflection film (BARC film) 53 made of an organic film, an antireflection function in which several tens percent of silicon (Si) is contained in the BARC of the organic film. A Si-ARC film having the same can also be applied.

Further, the wafer Q to which the substrate processing method according to the present embodiment is applied has the amorphous carbon film 51 as the processing target layer. However, the processing target layer is not limited to this, for example, a SiO ₂ film, a TiN film, or the like. There may be.

  In the present embodiment, the deposition speed of the deposit 56 is fast in the opening having a large opening width, and the deposition speed of the deposit 56 is small in the opening having a small opening width. Utilizing the characteristic that the opening width after deposition converges to a predetermined value peculiar to the applied gas, the variation in the opening width of the opening portion 55 of the photoresist film 54 that has initially varied in the etching is absorbed and uniformized. Can be planned.

  Next, a modification for clarifying the effect of absorbing variation in aperture width in the present embodiment will be described.

  As a first modification, plasma etching is performed on the wafer Q for 3 minutes under the same conditions as in the above embodiment except that the initial opening width of the opening 55 of the photoresist film 54 is 65 nm. When the treatment was performed, the thickness of the deposit 56 became 38 nm (opening width: 27 nm) 3 minutes after the start of the treatment. By this treatment, the aperture width of 65 nm could be reduced to 27 nm.

  Next, as a second modification, the wafer Q is processed in the same manner under the same conditions as in the above embodiment except that the initial opening width of the opening 55 of the photoresist film 54 is set to 70 nm. When the plasma etching process was performed for 1 minute, the thickness of the deposit 56 became 42 nm (opening width: 28 nm) 3 minutes after the start of the process. By this treatment, the opening width of 70 nm could be reduced to 28 nm.

In the present embodiment and Modifications 1 and 2, the initial opening width of the photoresist film 54 on the wafer Q is 60 nm, 65 nm, and 70 nm, respectively, but the photoresist film 54 after the plasma etching process using CHF ₃ gas is used. The opening widths at 25 were 25 nm, 27 nm, and 28 nm, respectively. From now on, the plasma etching process using CHF ₃ gas as a deposition gas has a target opening having an opening width (60 nm to 70 nm) having an initial variation (± 5 nm: average 65 nm) in addition to the shrink effect that narrows the opening width. It can be seen that there is an effect of reducing the width to, for example, the vicinity of 27 nm and absorbing the variation of each initial opening width (variation after processing ± 2 nm).

Example 1
Using wafer Q provided with a photoresist film having an intermediate layer and an opening with an opening width of 60 nm on a silicon substrate, the pressure inside the chamber is set to 1 × 10 Pa (75 mTorr), and the temperature of wafer Q is set to 50 ° C. CHF ₃ gas as a deposition gas was supplied into the chamber at 300 sccm, plasma was generated with a bias power of 300 W, and a shrink process for reducing the opening of the photoresist film was performed. The deposit deposition thickness of 31 nm (opening width: 29 nm), the deposit deposition thickness after 1 minute of processing is 32 nm (opening width: 28 nm), and the deposition deposition thickness after 3 minutes of processing starts is 33 nm (opening). (Width: 27 nm).

  From this result, it can be seen that the effect of reducing the opening width of the opening of the photoresist film in the shrink process reaches a peak at about 0.5 minutes after the start of the process and almost converges at 3 minutes after the start of the process. Therefore, the treatment time is preferably 0.5 minutes to 3.0 minutes.

  Next, a second embodiment of the present invention will be described in detail.

  The present inventor, when performing a shrink process to narrow the opening width of the opening provided in the photoresist film in the wafer Q, deposits are deposited not only on the side wall surface of the opening but also on the bottom, Since the thickness of the deposit deposited on the bottom portion increases corresponding to the deposit thickness deposited on the side wall surface, the deposit thickness deposited on the bottom also varies depending on the difference in the initial opening width, and the deposit thickness at the bottom of the aperture It was found that even if the same etching process was applied, the bottom deposition deposit could not be punched out in the same way, which hindered the uniform process.

  Based on this finding, various studies were repeated, and as a result, a deposit gas that easily deposits deposits on the side wall surface of the opening, and the bottom of the opening by etching the bottom of the opening are difficult to diffuse in the lateral direction of the opening. It is possible to reduce the opening width of the opening of the photoresist film and to avoid the deposition of the deposit on the bottom of the opening by performing a plasma treatment in combination with an anisotropic etching gas that suppresses the deposition of the deposit on the opening. I found it.

  FIG. 5 is a process diagram showing a substrate processing method according to the second embodiment of the present invention.

  In FIG. 5, first, an amorphous carbon lower layer resist film 61, an SiON film 62 as a hard mask, an antireflection film (BARC film) 63, and a photoresist film 64 are sequentially laminated on a silicon substrate 60. Prepares a wafer Q having an opening 65 that exposes a part of the antireflection film 63 with an opening width, for example, 60 nm (FIG. 5A). Then, the wafer Q is carried into the chamber 22 of the process module 12 (see FIG. 2) and placed on the mounting table 23.

Next, the pressure in the chamber 22 is set to 2 × 10 Pa (150 mTorr), for example, by the APC valve 26 or the like. Further, the temperature of the wafer Q is set to 50 ° C., for example. Then, CHF ₃ gas is supplied from the lower layer gas supply unit 29 of the shower head 24 into the chamber 22 at a flow rate of 300 sccm, and CF ₃ I gas is supplied from the upper layer gas supply unit 30 into the chamber 22 at a flow rate of 200 sccm. At this time, the flow rate ratio between the CHF ₃ gas and the CF ₃ I gas is 3: 2. Then, 750 W of high frequency power is supplied to the mounting table 23 as excitation power, and 300 W of high frequency power is supplied as bias power. In addition, a DC voltage of 300 V is applied to the shower head 24.

At this time, the CHF ₃ gas and the CF ₃ I gas become plasma by the high-frequency power applied to the processing space R, and ions and radicals are generated (FIG. 5B). Ions and radicals generated from the CHF ₃ gas collide with and react with the surface of the photoresist film 64 or the side wall surface of the opening, and deposit 66 is deposited on that portion to narrow the opening width. At this time, the deposit 66 is easily deposited on the bottom of the opening. On the other hand, ions and radicals generated from the CF ₃ I gas do not easily diffuse in the lateral direction of the opening 65, and therefore do not collide with deposits deposited on the side wall surface of the opening 65, but proceed to the bottom and deposit on the bottom. The deposit is collided and removed, and the antireflection film 63 and the SiON film 62 as the underlayer are etched. That is, the ions and radicals generated from the CHF ₃ gas cooperate with the ions and radicals generated from the CF ₃ I gas to shrink the opening width of the opening 65, and the photoresist film 64 and the photoresist film 64. Etching is performed on the bottom of the opening not covered with the deposit 66 deposited in the opening (FIG. 5C) (shrink etching step).

  At this time, although the diameter around the opening entrance is slightly widened, the thickness of the deposit 66 on the side wall surface of the opening gradually increases from the start of the process, and is about 31 nm (opening width: 29 nm) about 0.5 minutes after the start of the process. Then, about 1 minute after the start of the treatment, the thickness became 32 nm (opening width: 28 nm), and then gradually increased to 33 nm (opening width: 27 nm) 3 minutes after the start of the treatment.

  Further, the antireflection film 63 and the SiON film 62 were etched with a shrunken opening width of 27 nm until the amorphous carbon film 61 as the lower resist film was exposed, and the amorphous carbon layer 61 was exposed.

  In this way, the opening width of the opening 65 is shrunk, and the wafer Q on which the antireflection film 63 and the SiON film 62 are etched is unloaded from the chamber 22 of the process module 12 and passes through the transfer module 11. In the process module 13, the amorphous carbon film 61 is etched by using the SiON film 62 as a hard mask and the antireflective film 63 in the amorphous carbon film 61 and the like, as in the first embodiment. The SiON film 62 and the photoresist film 64 and the portion not covered with the deposit 66 deposited in the opening of the photoresist film 64 are etched, and the photoresist film 64 and the deposit 66 deposited on the photoresist film 64 and the reflection are etched. Ashing the protective film 63 To end the.

In the amorphous carbon film 61, an opening having an opening width of 27 nm was formed. Note that the wafer Q provided with the amorphous carbon film 61 having the opening 65 having the shrinked opening width is separately subjected to an etching process by a known method to prepare a wafer Q having a target pattern size.

According to the present embodiment, the CHF ₃ gas that easily deposits the deposit 66 on the side wall of the opening as the deposition gas, and the deposition of the deposit on the bottom is suppressed although it is difficult to diffuse in the lateral direction of the opening. Since the CF ₃ I gas that easily etches the underlayer is used in combination, the opening width of the opening 65 of the photoresist film 64 can be narrowed to meet the recent demand for miniaturization of semiconductor devices, and CF ₃ I. The antireflection film 63 and the SiON film 62 that are not covered with the photoresist film 64 can be etched by the plasma generated from the gas. That is, the shrink process for reducing the opening width of the opening 65 and the etching process for etching the antireflection film 63 and the SiON film 62 as the intermediate layer can be performed as a one-step approach. Thereby, the productivity of the wafer Q is improved.

  In the present embodiment, the deposition rate of the deposit 66 deposited on the side wall surface of the opening 65 depends on the width W of the opening, and increases as the opening width W of the opening 65 increases and decreases as the opening width decreases. Become. The opening width of the opening 65 after depositing is applied because it converges to a predetermined width depending on the gas deposition coefficient of the mixed gas of the deposition gas and the anisotropic etching gas with the processing time. The opening width can be adjusted by adjusting the type of gas, the mixing ratio, and the like.

In this embodiment, deposition gases have the general formula _{C x H y F z (x} , y, z is an integer including zero) are those represented by, CHF ₃ is preferably used. CHF ₃ has a gas adhesion coefficient S of about S = 0.5 and a convergence aperture width of, for example, 20 to 25 nm, which meets the recent demand for device miniaturization. As the deposition gas, in addition to CHF ₃ gas, for example, CH ₂ F ₂ gas, CH ₃ F gas, C ₅ F ₈ gas, and C ₄ F ₆ gas can be applied.

On the other hand, CF ₃ I gas is preferably used as the anisotropic etching gas. Since CF ₃ I gas is less toxic than HBr gas, it is easy to handle. As the anisotropic etching gas, CF ₃ Br gas, CF ₃ At gas, HI gas, HBr gas, or the like other than CF ₃ I gas can be applied. Further, instead of the halogen element in the anisotropic etching gas, an element that is a group 16 element of the periodic table and has a molecular weight larger than S and S can also be applied. Gases containing these halogen elements and group 16 elements of the periodic table are also low in volatility, difficult to diffuse in the lateral direction of the opening, and deposit the bottom layer by etching without depositing a deposit. Which can be used in combination with a deposition gas. The anisotropic etching gas has low volatility, reacts with carbon to form a bonding film to protect the side surface of the opening 65, and diffuses toward the bottom of the opening by an ionic force. It is thought that the film is etched.

  In the present embodiment, the mixing ratio between the deposition gas and the anisotropic etching gas is preferably 6: 1 to 1: 1, and more preferably 4: 3 to 3: 2. When the flow rate of the anisotropic etching gas is larger than the flow rate of the deposition gas, it becomes difficult to obtain a sufficient shrink effect. On the other hand, when the flow rate of the anisotropic etching gas is smaller than 1/6 of the flow rate of the deposition gas, the antireflection film 63 and the SiON film 62 are not sufficiently etched. In the present embodiment using the mixed gas of the deposition gas and the anisotropic etching gas, it is considered that the deposition amount on the side wall surface of the opening is slightly smaller than when the deposition gas alone is used. .

  In the present embodiment, the bias power during the etching process is 100 W to 500 W. If the bias power is less than 100 W, the opening bottom etching effect is insufficient. On the other hand, when the bias power exceeds 500 W, the photoresist film 65 is roughened by sputtering.

  In this embodiment mode, the pressure in the chamber during the etching process is 2.6 Pa (20 mTorr) to 2 × 10 Pa (150 mTorr), preferably 1 × 10 Pa (75 mTorr to 2 × 10 Pa (150 mTorr). If it is too low, the substrate surface will be roughened, while if the processing pressure is too high, the substrate surface will be worn.

  In the present embodiment, the temperature of the wafer Q during the etching process is not particularly limited, but is 20 ° C. to 100 ° C.

In the present embodiment, the intermediate layer etched simultaneously with the shrinkage of the opening width of the opening 65 of the photoresist film 64 is the antireflection film 63 and the SiON film 62 as the silicon-containing film, but the silicon-containing film is SiON. The film is not limited to a film, and other than the SiON film, for example, a SiO ₂ film, a SiN film, a SiC film, a SiOC film, or a SiCN film can be used. The intermediate layer is not limited to the antireflection film and the silicon-containing film. The intermediate layer is a combination of an antireflection film and a metal film such as a Ti film or a TiN film, or BARC as an organic film and silicon (Si It is also possible to apply a Si-BARC film or the like having the function of an antireflection film to which several tens of percent of () is added.

In addition, although the processing target layer in the present embodiment is the lower resist film 61, the processing target layer is not limited to this, and may be, for example, a SiO ₂ film or a TiN film.

  In the present embodiment, the etching processing time is 0.5 minutes to 3 minutes. When the etching time is shorter than 0.5 minutes, it is difficult to obtain a sufficient shrink effect, and when the processing time is about 3 minutes, the shrink effect converges and the etching of the intermediate layer is completed. Even so, it is difficult to obtain more effects.

  In the present embodiment, the opening width of the opening 65 can be reduced, and the shrink etching step for etching the intermediate layer and the etching step for etching the amorphous carbon film 61 can be continuously performed in the same chamber.

[Examples 2 to 15] and [Comparative Examples 1 and 2]
For the wafer Q having the photoresist film 64 having an initial opening width of 60 nm, the antireflection film 63, and the SiON film 62, CHF ₃ gas as a deposition gas and CF ₃ I gas as an anisotropic etching gas, Shrink and intermediate layer etching processes (one-step approach process) were performed while changing the bias power and gas flow ratio, and the surface of the photoresist film 1 minute after the start of the process and the surface of the lower resist layer after the ashing process were observed. .

  The conditions and observation results are shown in Table 1.

  Table 1 shows the following.

In Examples 2 to 11, the pressure in the chamber is 2.6 Pa (20 mTorr) to 2 × 10 Pa (150 mTorr), the bias power is 100 W to 500 W, and the gas flow ratio (CHF ₃ / CF ₃ I) is 6: 1. The etching effect for punching the antireflection film 63 and the SiON film 62 was recognized simultaneously with a sufficient shrink effect. Further, in Example 9, the opening width that was 60 nm on average in the initial state could be shrunk to 25 nm on average. At this time, the average value of the variation Δ was changed from 13.9 nm to 3.7 nm.

  In Example 12, since the pressure in the chamber was low, the surface of the photoresist film 64 was rough, but it was practical. In Example 13, the gas flow ratio was 4: 5, and the shrink effect was insufficient, but it was practical. In Example 14, the gas flow rate ratio was 7.3: 1, and the intermediate layer etching effect was insufficient, but it was practical.

Comparative Example 1 was based on CF ₃ I gas alone, and this also showed an intermediate layer etching effect, but a sufficient amount of shrinkage could not be obtained. In Comparative Example 2, since using a CHF ₃ gas alone is deposition gas as the processing gas, but shrink effect is obtained, not possible to punch the intermediate layer also depot attached to the bottom of the opening It was.

  In Example 15, although the bias power was too high and the surface of the photoresist film 64 was worn, it was practically usable.

[Example 16]
Deposition gas: CHF ₃ gas, anisotropic etching gas: CF ₃ I, flow ratio: CHF ₃ / CF ₃ I = 4: 1, chamber pressure: 2 × 10 Pa (150 mTorr), bias power: 750 + 300 W, wafer temperature : Wafer Q having a photoresist film 64 having an initial opening width of 75 nm at 60 ° C. is subjected to a one-step approach process, and 30 seconds, 60 seconds, 90 seconds, 120 seconds, 150 seconds, 180 seconds and 300 seconds after the start of the test. When the shrinkage amount and the etching state of the antireflection film 63 and the SiON film 62 were observed, the deposit (polymer) continued to be deposited on the side wall while the antireflection film 63 was being removed 30 to 90 seconds after the start of the test. The thickness gradually increased. Further, the shrinkage further progressed 90 to 120 seconds after the start of the test, and the etching of the SiON film 62 started. Thereafter, after 120 to 180 seconds from the start of the test, the SiON film 62 was completely removed and the shrinkage amount was converged.

  From this result, it can be seen that the treatment time is preferably 0.5 minutes to 3.0 minutes.

  Next, a description will be given of a third embodiment of the present invention as a modification of the second embodiment. The third embodiment uses a mixed gas of anisotropic etching gas and hydrogen gas as a processing gas, and reduces the opening width reducing step of depositing a deposit on the sidewall surface of the opening 75 of the photoresist film 74, and the opening. The etching step for etching the antireflection film 73 and the SiON film 72 as an intermediate layer forming the bottom of 75 is performed in one step (shrink etching step).

  FIG. 6 is a process diagram showing a substrate processing method according to the third embodiment of the present invention.

  In FIG. 6, first, an amorphous carbon lower layer resist film 71, an SiON film 72 as a hard mask, an antireflection film (BARC film) 73, and a photoresist film 74 are sequentially laminated on a silicon base material 70. Prepares a wafer Q having an opening 75 that exposes a part of the antireflection film 73 with an opening width, for example, 60 nm (FIG. 6A). Then, the wafer Q is carried into the chamber 22 of the process module 12 (see FIG. 2) and placed on the mounting table 23.

Next, the pressure in the chamber 22 is set to, for example, 1 × 10 Pa (75 mTorr) by the APC valve 26 or the like. Further, the temperature of the wafer Q is set to 40 ° C., for example. Then, CF ₃ I gas is supplied from the upper gas supply unit 30 into the chamber 22 at a flow rate of 150 sccm, and H ₂ gas is supplied from the lower gas supply unit 29 of the shower head 24 into the chamber 22 at a flow rate of 100 sccm. At this time, the flow rate ratio between the CF ₃ I gas and the H ₂ gas is 3: 2. Then, 750 W of high frequency power is supplied to the mounting table 23 as excitation power, and 300 W of high frequency power is supplied as bias power. Further, a direct current voltage of 50 V is applied to the shower head 24.

At this time, it reacts a part and _{H 2} gas is CF ₃ I gas, F component of CF ₃ I gas is withdrawn as HF, part of the CF ₃ I gas relatively F component is reduced Functions as deposit gas. That is, a high-frequency gas in which a reaction product gas of CF ₃ I gas and H ₂ gas (hereinafter referred to as “CF ₃ I · H ₂ reaction product gas”) and unreacted CF ₃ I gas are applied to the processing space R. Plasma is generated by electric power, and ions and radicals are generated (FIG. 6B). Ions and radicals generated from the CF ₃ I · H ₂ reaction product gas collide with and react with the surface of the photoresist film 74 or the side wall surface of the opening, and deposit a deposit 76 in the portion to narrow the opening width. At this time, the deposit 76 is easily deposited on the bottom of the opening. On the other hand, ions and radicals generated from the unreacted CF ₃ I gas are difficult to diffuse in the lateral direction of the opening 75, and the periphery of the opening 75 is slightly etched to form a tapered wall surface, and the opening The deposit advances to the bottom of the portion 75 and collides with the deposit deposited on the bottom, and the deposit is removed. Further, the antireflection film 73 and the SiON film 72 which are the underlayer are etched. Thus, ions and radicals generated from the CF ₃ I · H ₂ reaction product gas cooperate with ions and radicals generated from the unreacted CF ₃ I gas while shrinking the opening width of the opening 75. Then, the antireflection film 73 and the SiON film 72 at the bottom of the opening not covered with the photoresist film 74 and the deposit 76 deposited on the photoresist film 74 are etched (FIG. 6C).

  At this time, the thickness of the deposit 76 on the side wall surface of the opening gradually increased from the start of the process, and was 29 nm (opening width: 31 nm) in total on both sides 150 sec after the start of the process. The antireflection film 73 and the SiON film 72 are etched with a shrunken opening width of 31 nm until the amorphous carbon film 71 as a lower resist film is exposed, and the amorphous carbon corresponding to the opening width of the opening 75 is formed. Layer 71 was exposed.

  In this way, the wafer Q in which the opening width of the opening 75 is shrunk and the antireflection film 73 and the SiON film 72 are etched is carried out of the chamber 22 of the process module 12 and processed through the transfer module 11. Thereafter, the amorphous carbon film 71 is etched by using the SiON film 72 as a hard mask, and the antireflection film 73 and the SiON of the amorphous carbon film 71 are carried into the chamber of the module 13, as in the second embodiment described above. The film 72, the photoresist film 74, and the portion not covered by the deposit 76 deposited in the opening of the photoresist film 74 are etched, and an ashing process is performed to complete the present process.

  An opening corresponding to the opening width 31 nm of the opening 75 was formed in the amorphous carbon film 71. Note that the wafer Q provided with the amorphous carbon film 71 having the opening 75 having the shrinked opening width is separately subjected to an etching process by a known method to prepare the wafer Q having a target pattern size.

  According to the present embodiment, the shrink process for reducing the opening width of the opening 75 and the etching process for etching the antireflection film 73 and the SiON film 72 as an intermediate film are performed as a one-step approach (shrink etching step). Thus, as in the second embodiment, it is possible to meet the recent demand for miniaturization of semiconductor devices and to improve the productivity of the wafer Q.

According to the present embodiment, a mixed gas of CF ₃ I gas, which is an anisotropic etching gas, and H ₂ gas is used as the processing gas, and the flow ratio CF ₃ I: H _{2 is set} to 3: 2. Therefore, a part of the CF ₃ I gas and the H ₂ gas react to form a CF ₃ I · H ₂ reaction product gas in which F is extracted as HF from a part of the CF ₃ I gas. The CF ₃ I · H ₂ reaction product gas is a gas in which the ratio of the F component is relatively decreased and the ratio of the C component is relatively increased as compared with the CF ₃ I gas, and functions as a deposition gas. . That is, CF ₃ I gas is an anisotropic etching gas, and since the proportion of the F component is large, it cannot exhibit deposition properties. However, H ₂ gas is added to this to extract the F component as HF. As a result, the C component becomes relatively large, so that the deposition function is exhibited. In this way, the CF ₃ I · H ₂ reaction product gas that easily deposits the deposit 76 on the side wall of the opening, and the deposition of the deposit on the bottom is suppressed while being difficult to diffuse in the lateral direction of the opening, and etching the base layer An unreacted CF ₃ I gas that is easy to perform is used as a one-step approach for a shrink process for reducing the opening width of the opening 75 and an etching process for etching the antireflection film 73 and the SiON film 72 as intermediate films ( (Shrink etching step). Note that the HF gas generated when the F component is extracted from the CF ₃ I gas by the reaction between the CF ₃ I gas and the H ₂ gas is discarded outside the system, and therefore does not adhere to the components in the chamber. No problem.

In the present embodiment, the anisotropic etching gas is bromine (Br) or a gas containing a halogen element having a larger atomic number than bromine (Br), carbon, and fluorine, among which CF ₃ I gas or CF ₃ Br Gas is preferably used. CF ₃ I gas and CF ₃ Br gas / H ₂ gas have a smaller global temperature increasing coefficient (GWP) than the CHF ₃ gas / CF ₄ gas used in the prior art. Therefore, according to the present embodiment, it is possible to significantly reduce the environmental burden as compared with the conventional technique using a mixed gas of CHF ₃ gas and CF ₄ gas as the processing gas.

In the present embodiment, the mixing ratio of the anisotropic etching gas and the H ₂ gas is preferably 4: 1 to 2: 3, and particularly preferably 2: 1 to 4: 3. If the flow rate of H ₂ gas is smaller than ¼ of the flow rate of anisotropic etching gas, the CF ₃ I · H ₂ reaction product gas that functions as a deposition gas is insufficient, and it becomes difficult to obtain a sufficient shrink effect. On the other hand, when the flow rate of H ₂ gas is larger than 3/2 of the flow rate of anisotropic etching gas, the amount of unreacted anisotropic etching gas that does not react with H ₂ gas is insufficient, and antireflection film 73 and SiON Etching of the film 72 is insufficient. Note that the optimum mixing ratio of the anisotropic etching gas and the H ₂ gas is considered to depend on the processing pressure and the like.

  In the present embodiment, the bias power during the etching process is 100 W to 500 W. If the bias power is less than 100 W, the opening bottom etching effect is insufficient. On the other hand, when the bias power exceeds 500 W, the photoresist film 65 is roughened by sputtering.

  In this embodiment mode, the pressure in the chamber during the etching process is 2.6 Pa (20 mTorr) to 2 × 10 Pa (150 mTorr), preferably 1 × 10 Pa (75 mTorr to 2 × 10 Pa (150 mTorr). If it is too low, the surface of the substrate will be roughened, while if the processing pressure is too high, the surface of the substrate will be abraded. ° C.

In the present embodiment, the intermediate layer is the antireflection film 73 and the SiON film 72 as the silicon-containing film. However, the silicon-containing film is not only the SiON film, but, for example, a SiO ₂ film, a SiN film, a SiC film, a SiOC film, or It may be a SiCN film. The intermediate layer is not limited to the antireflection film and the silicon-containing film. The intermediate layer is a combination of an antireflection film and a metal film such as a Ti film or a TiN film, or BARC as an organic film and silicon (Si Si-ARC film or the like having the function of an antireflection film to which several tens of percent of () is added.

Further, although the processing target layer in the present embodiment is the lower resist film 71, the processing target layer is not limited to this, and may be, for example, a SiO ₂ film or a TiN film.

  In the present embodiment, the etching processing time is 0.5 minutes to 3 minutes. When the etching time is shorter than 0.5 minutes, it is difficult to obtain a sufficient shrink effect, and when the processing time is about 3 minutes, the shrink effect converges and the etching of the intermediate layer is completed. Even so, it is difficult to obtain more effects.

  In the present embodiment, the opening width of the opening 75 can be reduced and the shrink etching step for etching the intermediate layer and the etching step for the amorphous carbon film 71 can be continuously performed in the same chamber.

[Examples 17 to 19] and [Comparative Examples 3 to 7]
For the wafer Q having the photoresist film 74 having an initial opening width of 60 nm, the antireflection film 73, and the SiON film 72, a mixed gas of CF ₃ I gas and H ₂ gas is used as a processing gas, and the chamber pressure, bias power, Shrink etching treatment was performed while changing the gas flow rate ratio and the treatment time, and the surface of the photoresist film after the treatment and the surface of the lower resist layer after the ashing treatment were observed.

  Table 2 shows the conditions and the observation results.

  Table 2 shows the following.

In Examples 17 to 19, the flow rate ratio of CF ₃ I gas, which is an anisotropic etching gas, and H ₂ gas is 4: 1 to 2: 3, the pressure in the chamber is 1 × 10 Pa (75 mTorr), Since the bias power is 300 W and the processing times are 60, 120 and 150 seconds, respectively, and each condition is within the scope of the present invention, a sufficient shrink effect is obtained, and the antireflection film 73 and the SiON film 72 are formed. The etching effect of the punched intermediate layer was observed. In Example 18, the opening width of the opening 75 that averaged 60 nm in the initial state could be shrunk to an average of 31 nm, and the variation in hole diameter was extremely small.

Comparative Example 3 was based on the CF ₃ I gas alone, and this also confirmed the intermediate layer etching effect. However, since it was not the processing gas defined in the present invention, a sufficient shrink amount could not be obtained. In Comparative Example 4, CF ₄ gas, which is an anisotropic etching gas, was used alone as the processing gas, and the intermediate layer could be punched out. However, the processing gas is not a processing gas specified in the present invention, and thus shrink. The effect was not demonstrated.

In Comparative Examples 5 to 7, CF ₄ gas and CHF ₃ gas were used as the processing gas, and the shrink effect was exhibited as the ratio of the CHF ₃ gas flow rate to the CF ₄ gas flow rate was increased. Since it is not a processing gas specified in the invention, the top shape of the opening is rough and the variation in hole diameter is large, so that it cannot be practically used.

  In each of the embodiments described above, the substrate on which the plasma treatment is performed is not limited to a wafer for a semiconductor device, but various substrates used for FPD (Flat Panel Display) including LCD (Liquid Crystal Display), photomasks, CDs, and the like. A board | substrate, a printed circuit board, etc. may be sufficient.

  Another object of the present invention is to supply a storage medium storing software program codes for realizing the functions of the above-described embodiments to a system or apparatus, and the computer of the system or apparatus (or CPU, MPU, or the like). Is also achieved by reading and executing the program code stored in the storage medium.

  In this case, the program code itself read from the storage medium realizes the functions of the above-described embodiments, and the program code and the storage medium storing the program code constitute the present invention. .

  Examples of the storage medium for supplying the program code include a floppy (registered trademark) disk, a hard disk, a magneto-optical disk, a CD-ROM, a CD-R, a CD-RW, a DVD-ROM, a DVD-RAM, and a DVD. An optical disc such as RW or DVD + RW, a magnetic tape, a nonvolatile memory card, a ROM, or the like can be used. Alternatively, the program code may be downloaded via a network.

  Further, by executing the program code read by the computer, not only the functions of the above-described embodiments are realized, but also an OS (Operating System) running on the computer based on the instruction of the program code. Includes a case where the functions of the above-described embodiments are realized by performing part or all of the actual processing.

  Furthermore, after the program code read from the storage medium is written to a memory provided in a function expansion board inserted into the computer or a function expansion unit connected to the computer, the expanded function is based on the instruction of the program code. This includes a case where a CPU or the like provided on the expansion board or the expansion unit performs part or all of the actual processing and the functions of the above-described embodiments are realized by the processing.

10 Substrate processing system 12, 13, 14 Process module 50, 60, 70 Silicon substrate 51, 61, 71 Amorphous carbon film (lower resist film)
52, 62, 72 SiON films 53, 63, 73 Antireflection films 54, 64, 74 Photoresist films 55, 65, 75 Openings 56, 66, 76 Depot

Claims (8)

A processing target layer, an intermediate layer, and a mask layer are sequentially stacked, and the mask layer is a substrate processing method for processing a substrate having an opening exposing a part of the intermediate layer,
An opening width reduction step of depositing a deposit on the side wall surface of the opening of the mask layer by plasma generated from a mixed gas of anisotropic etching gas and hydrogen gas, and the intermediate layer forming the bottom of the opening A substrate processing method comprising a shrink etching step for performing an etching step for etching the substrate in one step.   2. The substrate processing method according to claim 1, wherein the anisotropic etching gas is bromine (Br) or a gas containing a halogen element having a larger atomic number than bromine (Br), carbon, and fluorine. The substrate processing method according to claim 2, wherein the anisotropic etching gas is CF ₃ I gas or CF ₃ Br gas.   4. The substrate processing according to claim 1, wherein a mixing ratio of the anisotropic etching gas and the hydrogen gas in the shrink etching step is 4: 1 to 2: 3. 5. Method.   The substrate processing method according to claim 1, wherein a bias power of 100 W to 500 W is applied to the substrate in the shrink etching step.   6. The substrate according to claim 1, wherein, in the shrink etching step, a pressure in a chamber accommodating the substrate is adjusted to 2.6 Pa (20 mTorr) to 2 × 10 Pa (150 mTorr). Processing method.   In the shrink etching step, the intermediate layer to be etched is an antireflection film and a silicon-containing film, an antireflection film and a metal film, or a silicon-containing organic film laminated under the mask layer. Item 7. The substrate processing method according to any one of Items 1 to 6.   A processing target layer etching step of transferring the opening of the intermediate layer having an opening corresponding to the opening of the mask layer whose opening width is reduced by the shrink etching step to the processing target layer; The substrate processing method according to any one of claims 1 to 7.

Images