JP2009008774A - Resist separation method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a resist separation method capable of satisfactorily separating a resist attached to a substrate on whose surface a low dielectric film (porous Low-k film) is formed from the substrate without damaging the porous low dielectric film. <P>SOLUTION: A reinforcement treating fluid is prepared by mixing a reinforcement agent essentially including a silylation agent with SCCO2 and supplied to a treatment chamber. Accordingly, the porous Low-k film formed on the substrate W is silylated. A separation agent essentially including a fluoride component is then mixed with the SCCO2 to prepare a separation treating fluid, and the separation treating fluid is supplied to the treatment chamber. Because etching resistance to the separation agent of the porous Low-k film is enhanced by the silylation, the resist can be separated and removed without damaging the porous Low-k film. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a resist stripping method for stripping a resist adhering to a substrate on which a porous low dielectric constant film is formed. Here, the substrate may be a semiconductor wafer, a liquid crystal display substrate, a plasma display substrate, an FED (Field Emission Display) substrate, an optical disk substrate, a magnetic disk substrate, a magneto-optical disk substrate, a photomask substrate, or the like. Is included.

  In a device manufacturing process using a so-called photoengraving method, a fine pattern is formed using a resist. However, a cleaning process for removing an unnecessary resist from the substrate after the pattern formation is an essential process. Therefore, as one of resist stripping methods for stripping the resist from the substrate, a resist stripping method for stripping the resist from the substrate by bringing a high-pressure fluid such as a supercritical fluid into contact with the surface of the substrate has been proposed (for example, Patent Document 1). reference). In the resist stripping method described in Patent Document 1, the resist is stripped using a processing fluid in which a fluoride component such as hydrogen fluoride and ammonium fluoride is mixed with a high-pressure fluid.

JP-T-2003-513342 (paragraph 0062)

  However, when the fluoride component is used as a peeling component, the following problems may occur. That is, in recent years, a porous low dielectric constant (Low-k) film is often formed on a substrate. When the above-described cleaning process is performed with a processing fluid (high-pressure fluid + fluoride component) on the substrate on which the porous low dielectric constant film is formed, not only the resist but also the porous Low-k film is caused by the processing fluid. It was sometimes etched and damaged. Further, such a problem may occur in the same manner as described above even when a chemical solution containing a fluoride component is used as a peeling component without using a high-pressure fluid. It has been difficult to sufficiently cope with these problems by the conventional processing method.

  The present invention has been made in view of the above-mentioned problems, and prevents the resist attached to the substrate having a porous low dielectric constant film on the surface from damaging the porous low dielectric constant film. It is an object of the present invention to provide a resist stripping method that can be satisfactorily stripped from a substrate.

  The present invention relates to a resist stripping method for stripping a resist adhering to a substrate having a porous low dielectric constant film formed on the surface thereof from the surface of the substrate. A silylation step of silylating a low dielectric constant film formed on a substrate using a reinforcing agent that essentially contains a substrate, and a resist substrate using a release agent that essentially contains a fluoride component after execution of the silylation step And a resist removing process for removing the resist from the substrate.

According to this structure, a resist is removed from a board | substrate using the peeling agent which essentially contains a fluoride component (resist removal process). Here, among the chemical species generated from the fluoride component contained in the release agent, the chemical species [F ⁻ ] greatly contributes to the removal and removal of the resist, while the chemical species [HF ₂ ⁻ ] was formed on the substrate. The porous low dielectric constant film is etched. That is, the porous low dielectric constant film has many chemically active defect sites. Therefore, these defect sites are the starting point of etching, and the porous low dielectric constant film is susceptible to etching by the chemical species [HF ₂ ⁻ ]. Therefore, in the present invention, defects existing in a porous low dielectric constant film are obtained by silylating the low dielectric constant film using a reinforcing agent that essentially contains a silylating agent before the resist removal step. The site is terminated (silylation process). Thereby, the etching resistance with respect to the peeling agent of a porous low dielectric constant film | membrane can be strengthened. Then, the resist is removed from the substrate by the release agent in such a state that the etching resistance of the porous low dielectric constant film is enhanced. For this reason, it is possible to peel the resist well from the substrate while preventing damage to the porous low dielectric constant film.

  Here, in the resist removing step, it is preferable to remove the resist from the substrate by bringing a peeling treatment fluid in which a release agent and a high-pressure fluid are mixed into contact with the substrate. According to this configuration, the resist can be effectively removed from the substrate while avoiding deterioration of the dielectric characteristics of the porous low dielectric constant film due to moisture absorption.

  In the silylation step, the low dielectric constant film may be silylated by bringing a reinforcing treatment fluid in which a reinforcing agent and a high-pressure fluid are mixed into contact with the substrate, or the reinforcing agent and an inert gas are mixed. The mixed fluid mixture may be brought into contact with the substrate to silylate the low dielectric constant film. In any case, the etching resistance of the porous low dielectric constant film to the release agent can be enhanced without adversely affecting the dielectric properties of the porous low dielectric constant film. In the former case, when the resist removal step is a step of removing the resist from the substrate by bringing the peeling processing fluid into contact with the substrate, the silylation step and the resist removal step are performed in this order in the same processing chamber. It is preferable to carry out continuously. According to this configuration, the solvent component to be mixed with the high-pressure fluid is switched, that is, the reinforcing agent is mixed with the high-pressure fluid in the silylation step, and the release agent is mixed with the high-pressure fluid in the resist removal step. For this reason, the processing content can be changed only by switching the solvent mixed with the high-pressure fluid. Therefore, the interval between the silylation process and the resist removal process can be shortened to improve the throughput.

  In the present invention, the term “porous” means that the material constituting the film contains a large number of nanometer-sized fine pores, and is called “low dielectric constant film”. Indicates a film having a relative dielectric constant of 2.5 or less.

  In the present invention, the high-pressure fluid used is preferably carbon dioxide from the viewpoints of safety, cost, and easy supercritical state. In addition to carbon dioxide, water, ammonia, nitrous oxide, ethanol and the like can also be used. The reason why the high-pressure fluid is used is that the dissolved contaminants can be dispersed in the medium. When the high-pressure fluid is used as a supercritical fluid, it has an intermediate property between gas and liquid, The diffusion coefficient approaches a gas and can penetrate well into fine pattern portions. Further, the density of the high-pressure fluid is close to that of a liquid and can contain a much larger amount of auxiliary agent (added agent) than gas.

  Here, the “high pressure fluid” in the present invention is a fluid having a pressure of 1 MPa or more. The high-pressure fluid that can be preferably used is a fluid in which high-density, high-solubility, low-viscosity, and high-diffusibility properties are observed, and more preferable is a fluid in a supercritical state or a subcritical state. In order to use carbon dioxide as a supercritical fluid, the temperature may be 31 ° C. and 7.4 MPa or more. From this point of view, in the present invention, it is preferable to use supercritical carbon dioxide of 8 to 30 MPa as high-pressure carbon dioxide.

  As described above, according to the present invention, the porous layer formed on the substrate using the reinforcing agent that essentially contains the silylating agent before the resist removal using the release agent that essentially contains the fluoride component. The low dielectric constant film is silylated. For this reason, the etching resistance with respect to the peeling agent of a porous low dielectric constant film | membrane can be strengthened. Therefore, by removing the resist using a release agent after silylation of the porous low dielectric constant film, it is possible to remove the resist well from the substrate while preventing damage to the porous low dielectric constant film. Can do.

<First Embodiment>
FIG. 1 is a view showing a resist stripping apparatus capable of carrying out a first embodiment of a resist stripping method according to the present invention. FIG. 2 is a block diagram showing an electrical configuration for controlling the resist stripping apparatus of FIG. The resist stripping apparatus 100 introduces supercritical carbon dioxide (hereinafter referred to as “SCCO 2”) or a mixture of SCCO 2 and a chemical as a processing fluid into a processing chamber 11 formed inside the high-pressure vessel 1. 2 is a device that peels off the resist adhering to the surface of the substrate W such as a substantially circular semiconductor wafer held in FIG. The substrate W has a layer to be processed which essentially includes a porous low dielectric constant film (hereinafter referred to as “porous low-k film”) as a resist underlayer on its surface. Hereinafter, the configuration and operation will be described in detail.

  This resist stripping apparatus 100 is roughly divided into three units, (1) a processing fluid supply unit A for preparing a processing fluid and supplying it to the processing chamber 11, and (2) a high-pressure vessel 1. A cleaning unit B for cleaning the substrate W by removing the resist adhering to the substrate W by the processing fluid in the processing chamber 11; and (3) a storage unit C for recovering and storing carbon dioxide used for the cleaning processing. I have.

  Among these units, the processing fluid supply unit A includes a high-pressure fluid supply unit 2 that pumps SCCO2 toward the high-pressure vessel 1 as a “high-pressure fluid” of the present invention, and a silylation for the porous Low-k film. A reinforcing agent supply unit 3 for supplying a reinforcing agent, a peeling agent supply unit 4 for supplying a release agent suitable for peeling and removing the resist, and a rinsing liquid supply unit 5 for supplying a rinsing liquid are provided. Yes.

  The high-pressure fluid supply unit 2 includes a high-pressure fluid storage tank 21 and a high-pressure pump 22. When SCCO 2 is used as the high-pressure fluid as described above, liquefied carbon dioxide is usually stored in the high-pressure fluid storage tank 21. Further, the fluid may be cooled in advance with a supercooler (not shown) to prevent gasification in the high-pressure pump 22. And if this fluid is pressurized with the high-pressure pump 22, high-pressure liquefied carbon dioxide can be obtained. The outlet side of the high-pressure pump 22 is connected to the inlet IP of the high-pressure vessel 1 by a high-pressure pipe 26 having a first heater 23, a high-pressure valve 24 and a second heater 25 interposed therebetween. Then, by opening the high-pressure valve 24 in accordance with an opening / closing command from the controller 10 that controls the entire apparatus, the high-pressure liquefied carbon dioxide pressurized by the high-pressure pump 22 is heated by the first heater 23 as high-pressure carbon dioxide. While obtaining SCCO2, this SCCO2 is directly pumped to the high-pressure vessel 1. Thereby, the processing fluid containing SCCO2 is supplied to the inside of the high-pressure vessel 1, that is, the processing chamber 11 through the inlet IP. Note that the high-pressure pipe 26 branches three branch pipes 31, 41, 51 between the high-pressure valve 24 and the second heater 25. The branch pipe 31 is connected to the reinforcing agent storage tank 32 of the reinforcing agent supply unit 3, the branch pipe 41 is connected to the release agent storage tank 42 of the release agent supply unit 4, and the branch pipe 51 is connected to the rinse liquid supply unit 5. A rinse liquid storage tank 52 is connected.

  The reinforcing agent supply unit 3 supplies a reinforcing agent for silylating the porous Low-k film, and includes a reinforcing agent storage tank 32 for storing the reinforcing agent. The reinforcing agent storage tank 32 is connected to the high-pressure pipe 26 by a branch pipe 31. In addition, a feed pump 33 and a high-pressure valve 34 are inserted in the branch pipe 31. For this reason, by controlling the opening / closing operation of the high-pressure valve 34 in accordance with the opening / closing command from the controller 10, the reinforcing agent in the reinforcing agent storage tank 32 is fed into the high-pressure pipe 26 and the reinforcing processing fluid (SCCO2 + reinforcing agent) is supplied. Prepared. Then, the processing fluid for reinforcement is supplied to the processing chamber 11 of the high-pressure vessel 1.

  In this embodiment, the toughening agent essentially contains a silylating agent. As silylating agents, n-butyldimethylchlorosilane (BDMCS), bromomethyldimethylchlorosilane (BMDMCS), N, O-bis-trimethylsilylacetamide (BSA), N, O-bis (trimethylsilyl) trifluoroacetamide (BSTFA), Bis (trimethylsiloxy) methylsilane (BTMS), N, O-bis (trimethylsilyl) acetamide (BTSA), chloromethyldimethylchlorosilane (CMDMCS), 1,3-bis (chloromethyl) tetramethyldisilazane (CMTMDS), n- Decyldimethylchlorosilane (DDMCS), hexamethyldisilazane (HMDS), N-methyl-N-trimethylsilyltrifluoroacetamide (MSTFA), N-methyl-N- (t-butyldimethylsilyl) trifluoroacetamide (MTBSTFA), N -Methyl-N- (trimethylsilyl Acetamide (MTMSA), n-octadecyldimethylchlorosilane (ODDMCS), n-octyldimethylchlorosilane (ODMCS), octamethyltrisiloxane (OMTS), t-butyldimethylchlorosilane (TBDMCS), triethylchlorosilane (TECS), trimethylbromosilane (TECS) TMBS), trimethylchlorosilane (TMCS), 2,4,6,8-tetramethylcyclotetrasiloxane (TMCTS), tetramethyldisilazane (TMDS), N-trimethylsilylacetamide (TMSA), N, N-diethylaminotrimethylsilane ( TMSDEA), N, N-dimethylaminotrimethylsilane (TMSDMA), allyltrimethylsilane (ATMS), bis (dimethylamino) methylsilane (B [DMA] DS), bis (dimethylamino) dimethylsilane (B [DMA] MS) , N, N-dimethylamino-1,2-dimethyl Disilane (DMADMDS), dimethylaminopentamethyldisilane (DMAPMDS), dimethylsilyldiethylamine (DMSDEA), dimethylsilyldimethylamine (DMSDMA), 1,3-divinyltetramethyldisiloxane (DVTMDS), heptamethyldisilazane (Hepta MDS) 2,2,4,4,6,6-hexamethylcyclotrisilazane (HMCTS), hexamethyldisilane (HMD Silane), hexamethyldisiloxane (HMDSO), 2,2,5,5-tetramethyl-2 , 5-disila-1-azacyclopentane (TDACP), 2,2,5,5-tetramethyl-2,5-disila-1-oxocyclopentane (TDOCP), trimethyliodosilane (TMIS), trimethylsilylimidazole ( TMSI), N-trimethylsilylimidazole (TSIM) can be used. These may be used alone or in combination of two or more.

  Further, the reinforcing agent may contain an organic solvent in addition to the silylating agent. Examples of organic solvents include methanol, ethanol, propanol, butanol, acetonitrile, acrylonitrile, formamide, methylformamide, dimethylformamide, methylacetamide, N, N-dimethylacetamide (DMAC), ethylene carbonate (EC), propylene carbonate (PC) , Ethylene glycol, prolene glycol, diethylene glycol, trimethylene glycol, dipropylene glycol, octylene glycol, butanediol, pentamethylene glycol, dimethyl sulfoxide (DMSO), N-methyl-2-pyrrolidinone (NMP), acetic acid, tetrahydrofuran ( THF), acetone, toluene, pyridine, hexane, xylene, 2-methylpyrrolidone, n-decane, n-heptane. These may be used alone or in combination of two or more.

  The release agent supply unit 4 supplies a release agent for removing the resist from the substrate W, and includes a release agent storage tank 42 for storing the release agent. The release agent storage tank 42 is connected to the high-pressure pipe 26 by a branch pipe 41. In addition, a feed pump 43 and a high-pressure valve 44 are inserted in the branch pipe 41. For this reason, by controlling the opening / closing operation of the high-pressure valve 44 in accordance with the opening / closing command from the controller 10, the release agent in the release agent storage tank 42 is fed into the high-pressure pipe 26 and the release processing fluid (SCCO 2 + release agent) is supplied. Prepared. Then, the peeling processing fluid is supplied to the processing chamber 11 of the high-pressure vessel 1.

  In this embodiment, the release agent essentially contains a fluoride component. Fluoride components include hydrogen fluoride, ammonium fluoride, tetramethylammonium fluoride (TMAF), tetraethylammonium fluoride (TEAF), tetrapropylammonium fluoride (TPAF), tetrabutylammonium fluoride (TBAF), choline Fluoride of (trimethyl 2-hydroxyethylammonium hydroxide) and other amine fluorides can be used. These may be used alone or in combination of two or more.

  Further, the release agent may contain an organic solvent in addition to the fluoride component. Examples of organic solvents include methanol, ethanol, propanol, butanol, acetonitrile, acrylonitrile, formamide, methylformamide, dimethylformamide, methylacetamide, N, N-dimethylacetamide (DMAC), ethylene carbonate (EC), propylene carbonate (PC) , Ethylene glycol, prolene glycol, diethylene glycol, trimethylene glycol, dipropylene glycol, octylene glycol, butanediol, pentamethylene glycol, dimethyl sulfoxide (DMSO), N-methyl-2-pyrrolidinone (NMP), acetic acid, tetrahydrofuran ( THF) and acetone. These may be used alone or in combination of two or more. By containing these organic solvents, the compatibility between the fluoride component and the high-pressure fluid can be improved.

  Further, the release agent contains ammonia, an amine compound (primary amine, secondary amine, tertiary amine, quaternary amine) or a mixture thereof in addition to the fluoride component and the organic solvent. You may make it do. Examples of amine compounds include tetramethylammonium hydroxide (TMAH), tetraethylammonium hydroxide (TEAH), tetrapropylammonium hydroxide (TPAH), tetrabutylammonium hydroxide (TBAH), choline, methylaminoethanol, pentamethyldiethylenetriamine (PMDETA), triethanolamine, triethylamine, triisopropylamine, diglycolamine, diethylene glycolamine, diisopropylamine, and monoethanolamine. These may be used alone or in combination of two or more. Further, the release agent may contain moisture.

  The rinsing liquid supply unit 5 supplies a rinsing liquid for rinsing the substrate W, and includes a rinsing liquid storage tank 52 that stores the rinsing liquid. The rinse liquid storage tank 52 is connected to the high-pressure pipe 26 by a branch pipe 51. In addition, a feed pump 53 and a high-pressure valve 54 are inserted in the branch pipe 51. Therefore, by controlling the opening / closing operation of the high-pressure valve 54 in accordance with the opening / closing command from the controller 10, the rinsing liquid in the rinsing liquid storage tank 52 is fed into the high-pressure pipe 26, and the rinsing processing fluid (SCCO 2 + rinsing liquid) is generated. Prepared. Then, the rinsing processing fluid is supplied to the processing chamber 11 of the high-pressure vessel 1. For example, ethanol is used as the rinse liquid.

  In the cleaning unit B, the discharge port OP of the high-pressure vessel 1 is communicated with the storage unit 8 of the storage unit C by the high-pressure pipe 12. In addition, a pressure regulating valve 13 is inserted in the high pressure pipe 12. For this reason, when the pressure adjustment valve 13 is opened in response to an opening / closing command from the controller 10, the processing fluid in the high-pressure vessel 1, that is, the processing chamber 11 is discharged from the discharge port OP to the storage unit 8, while When 13 is closed, the processing fluid can be confined in the high-pressure vessel 1. It is also possible to adjust the pressure in the processing chamber 11 by controlling the opening and closing of the pressure adjustment valve 13.

  As the storage unit 8 of the storage unit C, for example, a gas-liquid separation container or the like may be provided, and the SCCO2 is separated into a gas part and a liquid part using the gas-liquid separation container and discarded through separate paths. Alternatively, each component may be recovered (and purified if necessary) and reused. In addition, you may discharge | emit the gas component and liquid component which were isolate | separated by the gas-liquid separation container out of the system through a separate path | route.

  Next, the resist stripping operation by the resist stripping apparatus 100 configured as described above will be described with reference to FIGS. FIG. 3 is a flowchart showing a first embodiment of the resist stripping method according to the present invention. FIG. 4 is a flowchart showing the procedure of the silylation process. FIG. 5 is a flowchart showing the procedure of resist removal processing. FIG. 6 is a schematic diagram for explaining the resist peeling operation. In the initial state of this device, all the valves 13, 24, 34, 44, 54 are closed and the pumps 22, 33, 43, 53 are also stopped.

  When one substrate W, which is an object to be processed, is loaded into the processing chamber 11 by a handling device such as an industrial robot or a transport mechanism (Step S1), the processing chamber 11 is closed to complete the processing preparation (Step S2). ). In this embodiment, as shown in FIG. 6A, a layer to be processed F patterned in a predetermined pattern is formed on the surface of the substrate W. The processed layer F includes a porous Low-k film. Further, a used resist R used as a mask for patterning the processed layer into a predetermined pattern by etching or the like adheres on the processed layer F. That is, a layer F to be processed including a porous Low-k film as a base film of the resist R is formed on the surface of the substrate W by covering the surface with the resist R. Therefore, in the resist stripping process, it is required to strip only the resist R from the surface of the substrate W without damaging the layer F to be processed including the porous Low-k film.

However, if the resist R is simply removed from the substrate W using a release agent (a resist removal step is performed), the porous Low-k film included in the layer F to be processed is partially etched by the release agent. This is due to the following reason. That is, the fluoride component contained in the release agent, the chemical species [F ^-] with species [HF 2 ^_-] is generated. Of these chemical species, the chemical species [F ⁻ ] greatly contributes to resist removal, while the chemical species [HF ₂ ⁻ ] etches the porous Low-k film. This is because a lot of chemically active defect sites exist in the porous Low-k film, and these defect sites serve as starting points for etching by the chemical species [HF ₂ ⁻ ].

  Therefore, in this embodiment, the silylation process is performed before the resist removal process using the release agent (step S3). That is, the high pressure valve 24 is opened so that SCCO2 can be pumped from the high pressure fluid supply unit 2 to the processing chamber 11, and then the high pressure pump 22 is activated to start pumping SCCO2 to the processing chamber 11 (step S31). . As a result, SCCO2 is pumped to the processing chamber 11, and the pressure in the processing chamber 11 gradually increases. At this time, the processing pressure in the processing chamber 11 is maintained at a predetermined value (for example, 20 MPa) by controlling the pressure regulating valve 13 according to an opening / closing command from the controller 10. The pressure adjustment by the opening / closing control is continued until the decompression process described later is completed. Further, when it is necessary to adjust the temperature of the processing chamber 11, a temperature suitable for the surface treatment is set by a heater (not shown) provided near the high-pressure vessel 1. Here, the temperature and pressure of SCCO2 can be set as follows. That is, in order to use carbon dioxide as a supercritical fluid, the temperature may be 31 ° C. and 7.4 MPa or more. From this point of view, it is preferable to use SCCO2 of 8 to 30 MPa. Moreover, about temperature, it is more preferable to process at 50-120 degreeC.

  Next, the feed pump 33 is operated. As a result, a reinforcing agent for silylating the porous Low-k film is sent from the reinforcing agent storage tank 32 to the high-pressure pipe 26 via the branch pipe 31, and a reinforcing treatment fluid is prepared by mixing the reinforcing agent with SCCO2. (Step S32). At this time, the amount of reinforcing agent mixed can be adjusted by controlling the amount of liquid fed by the feed pump 33. Here, when adjusting the processing fluid for strengthening (SCCO2 + TMCTS) using, for example, TMCTS (2,4,6,8-tetramethylcyclotetrasiloxane) as the reinforcing agent (silylating agent), In order to satisfactorily silylate the porous Low-k film, the concentration of TMCTS in the reinforcing treatment fluid is preferably set to 1% by weight.

  The silylation process starts with the start of feeding of the reinforcing agent. At this time, SCCO2 and the reinforcing agent are continuously fed. In this way, the processing fluid for strengthening (SCCO 2 + strengthening agent) is supplied to the processing chamber 11, and the silylation processing is performed on the layer F to be processed including the porous Low-k film (FIG. 6B). That is, the reinforcing agent comes into contact with the porous Low-k film, and the porous Low-k film is silylated. As a result, defect sites existing in the porous Low-k film are terminated. As a result, the etching resistance to the release agent for the porous Low-k film can be enhanced. Further, the reinforcing treatment fluid used in the silylation treatment is sent to the storage unit 8 of the storage unit C through the high-pressure pipe 12.

  When the silylation of the porous Low-k film is completed (YES in step S33), the high pressure valve 34 is closed and the feed pump 33 is stopped. Thereby, the feeding of the reinforcing agent is stopped (step S34). However, the pumping of SCCO2 is continued as it is, and only SCCO2 is supplied to the processing chamber 11, and the rinsing process by SCCO2 is executed. When a silylating agent mixed with an organic solvent is used as the reinforcing agent, a processing fluid (SCCO2 + organic) mixed with SCCO2 and an organic solvent after silylation treatment with a reinforcing processing fluid (SCCO2 + reinforcing agent). It is preferable to perform the rinsing process using a solvent.

  Thus, when the rinsing process is completed (YES in step S35), a resist removal process is subsequently executed (step S4). That is, the feed pump 43 is operated in a state where the SCCO2 pressure feed is continued without being stopped. As a result, a stripping agent for stripping and removing the resist is sent from the stripping agent storage tank 42 to the high-pressure pipe 26 via the branch pipe 41, and a stripping processing fluid is prepared by mixing the stripping agent with SCCO2 (step). S41). At this time, the amount of the release agent mixed can be adjusted by controlling the amount of liquid fed by the feed pump 43. As the release agent, a composition containing a fluoride component, for example, a composition containing hydrogen fluoride, monoethanolamine, ethylene carbonate, and ethanol is used. In this case, the concentration of hydrogen fluoride is preferably 0.001 to 0.05% by weight, but more preferably, the concentration of hydrogen fluoride may be set to 0.01 to 0.03% by weight. The flow rate ratio of the release agent to SCCO2 is most preferably about 5% by weight.

In this way, the resist removing process starts by the start of feeding of the release agent. At this time, the supply of SCF and the release agent is continuously performed. In this way, the peeling processing fluid (SCCO 2 + release agent) is supplied to the processing chamber 11, the release agent contacts the surface of the substrate W, and unnecessary substances including the resist adhering to the substrate W are removed. Here, the chemical species [HF ₂ ⁻ ] that causes damage to the porous Low-k film are generated at the same time as the chemical species [F ⁻ ] that contribute to the removal of the resist in the stripping treatment fluid. The low-k film has enhanced etching resistance by chemical species [HF ₂ ⁻ ] in advance by silylation treatment. Therefore, it is possible to peel and remove the resist R satisfactorily while preventing damage to the layer F to be processed including the porous Low-k film (FIG. 6C). Further, the separation processing fluid accompanied by unnecessary substances is sent to the storage unit 8 of the storage unit C through the high-pressure pipe 12.

  When the resist removal from the substrate W is completed (YES in step S42), the high pressure valve 44 is closed and the feed pump 43 is stopped. Thereby, the supply of the release agent is stopped (step S43). Subsequently, the feed pump 53 is operated. Thus, the rinse liquid is sent from the rinse liquid storage tank 52 to the high pressure pipe 26 via the branch pipe 51. During this time, the pumping of SCCO2 is continued as it is, and a rinsing processing fluid (SCCO2 + rinsing liquid) is prepared by mixing the rinsing liquid into SCCO2 (step S44). At this time, the amount of rinse liquid mixed can be adjusted by controlling the amount of liquid fed by the feed pump 53. When the rinsing processing fluid is supplied to the processing chamber 11, the release agent remaining in the processing chamber 11 is discharged out of the processing chamber 11 (first rinsing step).

  When the first rinsing process is completed (YES in step S45), the high-pressure valve 54 is closed and the feed pump 53 is stopped. As a result, the supply of the rinse liquid is stopped (step S46). However, the pumping of SCCO2 is continued as it is, and only SCCO2 is supplied to the processing chamber 11, and the rinsing process by SCCO2 is executed (second rinsing process). Thereby, the cleaning component including the rinse liquid is discharged out of the processing chamber 11.

  When this second rinsing process is completed (YES in step S47), the high-pressure pump 22 is stopped and the SCCO2 pumping is stopped (step S48). And the inside of the process chamber 11 is returned to a normal pressure by controlling opening and closing of the pressure regulating valve 13 (step S5). In this decompression process, the SCCO2 remaining in the processing chamber 11 becomes a gas and evaporates, so that the substrate W can be dried without causing defects such as spots on the substrate surface. Moreover, in recent years, a fine pattern is often formed on the surface of the substrate, and the problem that the fine pattern is destroyed during the drying process has been highlighted. However, the above problem can be solved by using supercritical reduced pressure drying. It can be solved.

  When the processing chamber 11 returns to normal pressure, the processing chamber 11 is opened (step S6), and the processed substrate W is unloaded by a handling device such as an industrial robot or a transport mechanism (step S7). Thus, a series of resist stripping processes, that is, a silylation process + resist removal process + drying process is completed. Then, when the next unprocessed substrate is transported, the above operation is repeated.

  As described above, according to this embodiment, the silylating agent is applied to the porous Low-k film formed on the substrate W before the resist removal process using the release agent that essentially contains the fluoride component. Silylation treatment is performed using a reinforcing agent that essentially contains. For this reason, the etching tolerance with respect to the peeling agent of a porous Low-k film | membrane can be improved. Since the resist is removed from the substrate W by using the release agent in such a state that the etching resistance to the release agent of the porous Low-k film is increased, the porous Low-k film is prevented from being damaged. However, the resist can be peeled off from the substrate W satisfactorily. In addition, since the porous Low-k film is silylated using the reinforcing agent in this way, the porous Low-k film is not adversely affected by the dielectric properties of the porous Low-k film and the resist is attached to the substrate W. It is possible to enhance the etching resistance of the k film.

  Further, according to this embodiment, after the silylation treatment is performed using the reinforcing treatment fluid in which the reinforcing agent and the high pressure fluid are mixed, the peeling processing fluid in which the release agent and the high pressure fluid are mixed is used. The resist is removed. In other words, since the resist stripping process is performed without performing the wet process, the resist can be effectively stripped from the substrate W while avoiding deterioration of the dielectric properties of the porous low dielectric constant film due to moisture absorption. Can do.

  Moreover, in this embodiment, since the silylation process and the resist removal process are continuously performed in this order in the same processing chamber 11, the following effects can be obtained. That is, the solvent to be mixed with SCCO2 is switched, that is, the reinforcing agent is mixed with SCCO2 in the silylation step (step S32), and the release agent is mixed in the resist removal step (step S41). Thus, the processing content can be changed only by switching the solvent component to be mixed with SCCO2, and the interval between the silylation step and the resist removal step can be shortened. As a result, the throughput of the apparatus can be greatly improved. In addition, since processing is always performed using SCCO2 that is chemically inert to the substrate W as a carrier medium, processing can be performed stably and satisfactorily.

Second Embodiment
FIG. 7 is a diagram showing a resist stripping system that can implement the second embodiment of the resist stripping method according to the present invention. In this resist stripping system, a substrate W is interposed between a high-pressure processing apparatus 100A that performs high-pressure processing on the substrate W using a high-pressure fluid and a silylation apparatus 200 that silylates a porous Low-k film formed on the substrate W. A transport apparatus 300 is disposed for transporting the. The configuration of the high-pressure processing apparatus 100A is basically the same as that of the resist stripping apparatus 100 shown in FIG. 1, but since the silylation apparatus 200 is provided separately from the high-pressure processing apparatus 100A, the reinforcing agent for supplying the reinforcing agent The supply part 3 can be made unnecessary. In addition, the transfer apparatus 300 transfers the unprocessed substrate W to the silylation apparatus 200 and also transfers the substrate W that has undergone the silylation process in the silylation apparatus 200 to the high-pressure processing apparatus 100A.

  FIG. 8 is a diagram showing an example of the configuration of the silylation apparatus. The silylation apparatus 200 includes a processing vessel 201 having a processing chamber 211 for executing a silylation process inside, and a heating plate 203 disposed on the inner bottom of the processing chamber 211. The processing vessel 201 is provided with an inlet 205, and a mixed fluid of an inert gas such as nitrogen gas or a reinforcing agent essentially containing a silylating agent and an inert gas is selectively passed through the inlet 205. Supply to the processing chamber 211 is possible. That is, the fluid supply unit 206 communicates with the processing chamber 211 through the introduction port 205, and the inert gas or mixed fluid (reinforcing agent) is supplied from the fluid supply unit 206 in accordance with an operation command from the controller 400 that controls the entire system. + Inert gas) is selectively introduced into the processing chamber 211. Here, the mixed fluid can be generated, for example, by introducing nitrogen gas into a storage tank that stores the reinforcing agent and bubbling the nitrogen gas into the reinforcing agent in the storage tank. Further, the processing container 201 is provided with an exhaust port 207 so that the gas component in the processing chamber 211 can be exhausted from the processing chamber 211.

  The heating plate 203 incorporates a heater 209 and is configured such that the heater 209 generates heat in response to an electrical signal supplied from the controller 400. Further, in the heating plate 203, a plurality of support pins (not shown) can be moved up and down, and after the support pins protrude from the upper surface of the heating plate 203 and receive the substrate W from the transfer device 300, the support pins are heated. The substrate W is placed on the upper surface of the heating plate 203 by descending and retreating into the plate 203. The heating plate 203 is provided with a plurality of suction holes, and can hold the substrate W placed as described above by vacuum suction. Further, as the support pins are raised, the substrate W on the heating plate 203 is lifted from the heating plate 203, and the substrate W can be carried out from the silylation apparatus 200 by the transfer device 300.

  Next, a resist stripping process by the resist stripping system configured as described above will be described with reference to FIG. FIG. 9 is a flowchart showing a second embodiment of the resist stripping method according to the present invention. The substrate W to be processed in the silylation apparatus 200 is carried into the silylation apparatus 200 by the transfer apparatus 300 and transferred to the heating plate 203 (step S11). The heater 209 is already turned on (driving state).

  When the substrate W is held by the heating plate 203, the mixed fluid (reinforcing agent + inert gas) is introduced into the processing chamber 211 from the introduction port 205. As a result, the processing chamber 211 is filled with an inert gas atmosphere containing a reinforcing agent. Further, the substrate W held on the heating plate 203 is heated by heat generated from the heater 209. At this time, the controller 400 drives and controls the heater 209 so that the temperature of the substrate W becomes 200 ° C. or higher and a predetermined processing temperature of 500 ° C. or lower, for example, 400 ° C. Thereby, the porous Low-k film is silylated by the reinforcing agent that comes into contact with the porous Low-k film (step S12). As a result, the etching resistance to the release agent for the porous Low-k film can be enhanced. Note that the pressure in the processing chamber 211 is maintained at a normal pressure.

  When the silylation for the porous Low-k film is completed, the introduction of the reinforcing agent into the processing chamber 211 is stopped. That is, only the inert gas is introduced into the processing chamber 211 through the introduction port 205, and the reinforcing agent remaining in the processing chamber 211 is discharged out of the processing chamber 211.

  The substrate W thus subjected to the silylation process is unloaded from the silylation apparatus 200 by the transfer apparatus 300 and is loaded into the high-pressure processing apparatus 100A (step S13). That is, the substrate W that has undergone the silylation treatment is loaded into the processing chamber 11. Thereafter, the processing chamber 11 is closed (step S14), and a resist removal process (step S15) and a reduced pressure drying process (step S16) are performed. In addition, since the operation | movement of step S13-S18 is the same as the operation | movement of step S1, S2 and step S4-S7 (FIG. 4) in 1st Embodiment, description is abbreviate | omitted here.

  As described above, according to this embodiment, since the porous Low-k film is silylated using the reinforcing agent before the resist removal process using the release agent is performed, the same action as the first embodiment is achieved. An effect is obtained. In addition, after silylation treatment is performed using a mixed fluid in which a reinforcing agent and an inert gas are mixed, the resist is removed using a stripping treatment fluid in which a stripping agent and a high-pressure fluid are mixed. That is, since the resist stripping process is performed without performing the wet process, the resist can be stripped from the substrate W satisfactorily while avoiding deterioration of the dielectric properties of the porous Low-k film due to moisture absorption.

  Further, according to this embodiment, after the silylation process is executed in the silylation apparatus 200, the substrate W that has been subjected to the silylation process by the transfer apparatus 300 is transferred to the high-pressure processing apparatus 100A, and the high-pressure fluid is supplied to the high-pressure processing apparatus 100A. The resist removal process using is performed. Therefore, the resist can be satisfactorily peeled from the substrate W while the silylation process and the high-pressure process using the high-pressure fluid are performed professionally.

<Others>
The present invention is not limited to the above-described embodiment, and various modifications other than those described above can be made without departing from the spirit of the present invention. For example, in the above embodiment, in the resist removal step, the resist removal is performed using a stripping treatment fluid in which a stripping agent and a high-pressure fluid are mixed. However, the use of a high-pressure fluid is not essential. For example, the present invention can be applied to a case where a wet treatment is performed using a chemical solution containing a fluoride component as a peeling component without using a high-pressure fluid. That is, even in such a case, the porous Low-k film may be etched by the fluoride component contained in the drug. Accordingly, by silylating the porous Low-k film before the resist removing step, the etching resistance of the porous Low-k film to the chemical solution can be increased, and the porous Low-k film can be prevented from being damaged.

  In the above-described embodiment, the present invention is applied to the single-wafer resist stripping method for processing the substrates W one by one. The present invention can also be applied to a method.

  In the second embodiment, the substrate W is directly placed on the heating plate 203 and heated to a predetermined processing temperature. However, the substrate W is held in a position directly above the heating plate 203. W may be heated. For example, the substrate W may be configured to be heated in a state where the substrate W is supported on the proximity pins and separated from the heating plate 203 by a minute distance. Furthermore, a heat source such as an infrared lamp heater may be disposed in the vicinity of the substrate W, and the temperature of the atmosphere surrounding the substrate W may be raised to a predetermined processing temperature by this heat source.

  The present invention can be applied to all resist stripping methods in which a resist stripping process for stripping a resist adhering to a substrate on which a porous low dielectric constant film is formed from the substrate is performed.

It is a figure which shows the resist peeling apparatus which can implement 1st Embodiment of the resist peeling method concerning this invention. It is a block diagram which shows the electrical structure for controlling the resist peeling apparatus of FIG. It is a flowchart which shows 1st Embodiment of the resist peeling method concerning this invention. It is a flowchart which shows the procedure of a silylation process. It is a flowchart which shows the procedure of a resist removal process. It is a schematic diagram for demonstrating resist peeling operation | movement. It is a figure which shows the resist stripping system which can implement 2nd Embodiment of the resist stripping method concerning this invention. It is a figure which shows an example of a structure of a silylation apparatus. It is a flowchart which shows 2nd Embodiment of the resist peeling method concerning this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... High pressure vessel 2 ... High pressure fluid supply part 3 ... Strengthening agent supply part 4 ... Release agent supply part 5 ... Rinse solution supply part 11 ... Processing chamber R ... Resist W ... Substrate

Claims (5)

In a resist stripping method for stripping a resist adhering to a substrate having a porous low dielectric constant film formed on the surface from the surface of the substrate,
A silylation step of silylating the low dielectric constant film formed on the substrate using a reinforcing agent essentially containing a silylating agent;
A resist stripping method comprising: a resist removal step of removing the resist from the substrate using a stripper that essentially contains a fluoride component after the silylation step.   The resist removing method according to claim 1, wherein the resist removing step is a step of removing the resist from the substrate by bringing a peeling treatment fluid in which the release agent and a high-pressure fluid are mixed into contact with the substrate.   3. The resist stripping method according to claim 1, wherein the silylation step is a step of silylating the low dielectric constant film by bringing a reinforcing treatment fluid obtained by mixing the reinforcing agent and a high-pressure fluid into contact with the substrate. . The resist removing step is a step of removing the resist from the substrate by bringing a peeling treatment fluid obtained by mixing the release agent and a high-pressure fluid into contact with the substrate.
The resist removal method according to claim 3, wherein the silylation step and the resist removal step are successively performed in this order in the same processing chamber. 3. The resist stripping method according to claim 1, wherein the silylation step is a step of silylating the low dielectric constant film by bringing a mixed fluid obtained by mixing the reinforcing agent and an inert gas into contact with the substrate.

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