Substrate processing apparatus and substrate processing method

Abstract

To provide a technique that can reduce processing defects that may be caused by introducing a processing fluid at a high flow rate into a processing chamber, and can be executed in a short time.SOLUTION: A substrate processing method according to the present invention includes steps of: accommodating a substrate whose upper surface is covered with a liquid film in an internal space of a processing chamber in a state where the substrate is placed on a plate-like support member in a horizontal posture; filling the internal space with a processing fluid in a supercritical state; and discharging the processing fluid from the internal space. Supply of the processing fluid is started from a first discharge port that ejects the processing fluid in a horizontal direction toward a space between a bottom surface of a chamber wall surface and a lower surface of the support member. In addition, after an internal pressure of the internal space exceeds a critical pressure, supply of a pressurized processing fluid into the internal space is started from a second discharge port that ejects the processing fluid in the horizontal direction toward a space between a ceiling surface of the chamber wall surface and the upper surface of the substrate.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a technique for processing a substrate with a processing fluid in a supercritical state in a processing chamber, and more particularly to a supply sequence of the processing fluid to the processing chamber. [Background technology]

[0002] Processing processes for various substrates, such as semiconductor substrates and glass substrates for display devices, involve treating the surface of the substrate with various processing fluids. While processing using liquids, such as chemical solutions and rinse solutions, as processing fluids has been widely used for some time, processing using supercritical fluids has also come into practical use in recent years. In particular, when processing substrates having fine patterns formed on their surfaces, supercritical fluids, which have lower surface tension than liquids, can penetrate deep into the gaps in the patterns, enabling efficient processing and reducing the risk of pattern collapse due to surface tension during drying.

[0003] For example, in Patent Document 1, filed by the applicant of the present application, a substrate having a liquid film formed on its upper surface is placed on a flat support member and accommodated in a high-pressure processing chamber, and a processing fluid is introduced from the sides of the substrate onto the upper surface of the substrate and the lower surface of the support member. Furthermore, the processing fluid is discharged from the upper surface of the substrate and the lower surface of the support member on the opposite side of the substrate from the direction into which the processing fluid is introduced. This forms laminar flows of the processing fluid above the substrate and below the support member, and the liquid covering the substrate is replaced by the processing fluid and discharged together with the processing fluid, ultimately leaving the substrate in a dry state.

[0004] On the other hand, Patent Document 2 describes a technology that enhances the processing effect by supplying a processing fluid below the substrate to increase the pressure inside the processing container to a predetermined level, and then flowing the processing fluid along the upper surface of the substrate. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Publication No. 2023-036123 [Patent Document 2] Japanese Patent Publication No. 2023-017577 Summary of the Invention [Problem to be solved by the invention]

[0006] When a high-pressure processing fluid is introduced into a processing chamber containing a substrate covered with a liquid film, the high-velocity spray of the processing fluid may cause a partial loss of the liquid that constitutes the liquid film, especially in the initial stage of introduction. If this exposes the substrate surface, there is an increased risk of processing defects such as pattern collapse. Patent Document 1 does not mention how to address this problem.

[0007] Furthermore, the technology described in Patent Document 2 addresses this problem by supplying processing fluid only from below the substrate until the pressure inside the processing vessel reaches a sufficient high pressure. However, this configuration requires a long time to increase the pressure to a predetermined level. If the supply rate of processing fluid is increased to avoid this, the flow rate of the processing fluid will further increase, which may cause processing defects.

[0008] As described above, in the technology for processing a substrate by forming a laminar flow of a processing fluid around the substrate, no technology has been proposed that effectively suppresses the occurrence of processing defects such as pattern collapse caused by the loss of the liquid film on the substrate surface due to the introduction of the processing fluid. In this sense, it can be said that there is still room for improvement in the conventional technology.

[0009] The present invention has been made in consideration of the above-mentioned problems, and aims to provide a technology for processing a substrate with a processing fluid in a supercritical state in a processing chamber, which can reduce processing defects that may occur when a processing fluid is introduced at a high flow rate, and which can be performed in a short time. [Means for solving the problem]

[0010] One aspect of the present invention is a substrate processing method for processing a substrate with a processing fluid in a supercritical state, comprising a first step of placing the substrate, the upper surface of which is covered with a liquid film, in an internal space of a processing chamber while the substrate is placed in a horizontal position on a flat support member; a second step of filling the internal space with the processing fluid in a supercritical state; and a third step of discharging the processing fluid from the internal space.

[0011] Here, a first outlet port is provided on the side wall surface of the wall surface of the processing chamber that forms the internal space, for ejecting the processing fluid horizontally toward the space between the bottom surface of the wall surface and the lower surface of the support member, and a second outlet port is provided on the side wall surface of the processing chamber that ejects the processing fluid horizontally toward the space between the ceiling surface of the wall surface and the upper surface of the substrate.

[0012] Then, in the second step, the pressurized processing fluid is supplied from the first outlet to the internal space to increase the pressure of the internal space, and after the internal pressure of the internal space exceeds the critical pressure of the processing fluid, the supply of the pressurized processing fluid to the internal space from the second outlet is started in addition to the supply from the first outlet.

[0013] Another aspect of the present invention is a substrate processing apparatus that processes a substrate with a processing fluid in a supercritical state, comprising: a flat support member on which the substrate can be placed; a processing chamber having an internal space that can accommodate the support member together with the substrate in a horizontal position; a fluid supply unit that supplies the processing fluid to the internal space; a fluid discharge unit that discharges the processing fluid from the internal space; and a control unit that controls the fluid supply unit.

[0014] Here, a first outlet port is provided on the side wall surface of the wall surface of the processing chamber that forms the internal space, for ejecting the processing fluid horizontally toward the space between the bottom surface of the wall surface and the lower surface of the support member, and a second outlet port is provided on the side wall surface of the processing chamber that ejects the processing fluid horizontally toward the space between the ceiling surface of the wall surface and the upper surface of the substrate.

[0015] Then, when the support member on which the substrate is placed is accommodated in the internal space, the control unit controls the fluid supply unit to start supplying the processing fluid from the first outlet to the internal space to increase the pressure in the internal space, and once the internal pressure of the internal space exceeds the critical pressure of the processing fluid, starts supplying the processing fluid from the second outlet to the internal space in addition to supplying it from the first outlet.

[0016] In the invention configured as described above, in the initial stage of introducing the processing fluid into the processing chamber, the processing fluid is supplied to the space below the support member. Then, once the internal pressure of the processing chamber exceeds the critical pressure of the processing fluid, the supply of the processing fluid to the space above the substrate begins. At this point, the internal space of the processing chamber is filled with the processing fluid at or above the critical pressure, thereby avoiding the problem of the liquid film on the substrate being blown away by the processing fluid being supplied along the upper surface of the substrate. This effectively prevents the loss of the liquid film, which would expose the substrate surface and cause processing defects.

[0017] In a technology for processing a substrate with a processing fluid in a supercritical state, the internal pressure of the processing chamber is ultimately increased to a pressure sufficiently higher than the critical pressure. In this invention, the processing fluid can be supplied not only below the substrate but also above the substrate to further increase the pressure, thereby shortening the time required to increase the internal pressure to the pressure required for processing. [Effects of the Invention]

[0018] As described above, in the present invention, the supply of the processing fluid to the space below the substrate is started first, and the processing fluid is supplied to the space above the substrate after the internal pressure of the processing chamber exceeds the critical pressure, thereby shortening the time required for the internal pressure to reach the desired pressure and reducing processing defects caused by the spraying of the processing fluid. [Brief explanation of the drawings]

[0019] [Figure 1]1 is a diagram showing a schematic configuration of an example of a substrate processing apparatus according to the present invention; [Figure 2] 3 is a flowchart showing an outline of a process executed by the substrate processing apparatus. [Figure 3] 10 is a timing chart showing the state changes of each part of the device during this process. [Figure 4] 10 is a timing chart showing a first modified example of the supercritical drying process. [Figure 5] 10 is a timing chart showing a second modified example of the supercritical drying process. [Figure 6] 10 is a timing chart showing a third modified example of the supercritical drying process. DETAILED DESCRIPTION OF THE INVENTION

[0020] FIG. 1 is a diagram showing a schematic configuration of an example of a substrate processing apparatus according to the present invention. This substrate processing apparatus 1 is an apparatus for processing the surface of various substrates, such as semiconductor substrates, using a supercritical fluid. This substrate processing apparatus 1 has a configuration suitable for applying the method for determining the end of replacement and the substrate processing method according to the present invention. To unify the directions in the following figures, an XYZ Cartesian coordinate system is set as shown in FIG. 1. Here, the XY plane is a horizontal plane, and the Z direction represents the vertical direction. More specifically, the (-Z) direction represents the vertical downward direction.

[0021] Here, the "substrate" in this embodiment can be any of various substrates such as semiconductor wafers, glass substrates for photomasks, glass substrates for liquid crystal displays, glass substrates for plasma displays, substrates for FEDs (Field Emission Displays), substrates for optical disks, substrates for magnetic disks, substrates for magneto-optical disks, etc. The following description will be given with reference to the drawings, taking as an example a substrate processing apparatus used primarily for processing semiconductor wafers, but the invention can also be applied to processing the various substrates exemplified above.

[0022] The substrate processing apparatus 1 includes a processing unit 10, a supply unit 50, and a control unit 90. The processing unit 10 is the main body that performs the supercritical drying process, and the supply unit 50 supplies the processing unit 10 with chemical substances and power required for the process.

[0023] The control unit 90 controls each part of these devices to perform predetermined processing. For this purpose, the control unit 90 is equipped with a CPU 91 that executes various control programs, a memory 92 that temporarily stores processing data, a storage 93 that stores the control programs executed by the CPU 91, and an interface 94 for exchanging information with users and external devices. The operation of the devices, which will be described later, is achieved by the CPU 91 executing the control programs written in advance in the storage 93 and causing each part of the devices to perform predetermined operations.

[0024] The processing unit 10 includes a processing chamber 100. The processing chamber 100 includes a first member 11, a second member 12, and a third member 13, each formed from a metal block. The first member 11 and the second member 12 are joined in the vertical direction by a joining member (not shown), and the third member 13 is joined to the (+Y) side surface of the first member 11 and the second member 12 by a joining member (not shown), thereby forming the processing chamber 100 with a hollow structure. The hollow internal space serves as a processing space SP where processing is performed on a substrate S. The substrate S to be processed is loaded into the processing space SP and undergoes processing. A slit-shaped opening 101 extending elongatedly in the X direction is formed on the (-Y) side surface of the processing chamber 100, and the processing space SP communicates with the external space via the opening 101.

[0025] A lid member 14 is provided on the (-Y) side surface of the processing chamber 100 so as to close the opening 101. A flat support tray 15 is attached in a horizontal position to the (+Y) side surface of the lid member 14, and the upper surface of the support tray 15 serves as a support surface on which a substrate S can be placed. More specifically, the support tray 15 has a structure in which a recess 152 formed slightly larger than the planar size of the substrate S is provided on a substantially flat upper surface 151. The substrate S is held in a predetermined position on the support tray 15 by being accommodated in this recess 152. The substrate S is held with the surface Sa to be processed (hereinafter sometimes simply referred to as the "substrate surface") facing upward. In this case, it is preferable that the upper surface 151 of the support tray 15 and the substrate surface Sa are flush or substantially flush with each other.

[0026] The lid member 14 is supported by a support mechanism (not shown) so as to be horizontally movable in the Y direction. The lid member 14 can be moved forward and backward relative to the processing chamber 100 by an advance / retract mechanism 53 provided in the supply unit 50. Specifically, the advance / retract mechanism 53 has a linear motion mechanism such as a linear motor, a linear motion guide, a ball screw mechanism, a solenoid, or an air cylinder, and this linear motion mechanism moves the lid member 14 in the Y direction. The advance / retract mechanism 53 operates in response to a control command from the control unit 90.

[0027] When the cover member 14 moves in the (-Y) direction, the support tray 15 is pulled out from the processing space SP through the opening 101, allowing access to the support tray 15 from the outside. That is, it becomes possible to place the substrate S on the support tray 15 and to remove the substrate S placed on the support tray 15. On the other hand, when the cover member 14 moves in the (+Y) direction, the support tray 15 is accommodated in the processing space SP. When a substrate S is placed on the support tray 15, the substrate S is carried into the processing space SP together with the support tray 15.

[0028] In a supercritical drying process, the main purpose of which is to dry a substrate while preventing pattern collapse due to the surface tension of a liquid, the substrate S is carried in with its surface Sa covered with a liquid film to prevent the surface Sa from being exposed and causing pattern collapse. As the liquid that constitutes the liquid film, an organic solvent with a relatively low surface tension, such as isopropyl alcohol (IPA) or acetone, can be suitably used.

[0029] The lid member 14 moves in the (+Y) direction to close the opening 101, thereby sealing the processing space SP. A seal member 16 is provided between the (+Y) side surface of the lid member 14 and the (-Y) side surface of the processing chamber 100, maintaining the processing space SP in an airtight state. The seal member 16 may be an annular member made of an elastic resin material, such as rubber. In addition, the lid member 14 is fixed to the processing chamber 100 by a locking mechanism (not shown). With the processing space SP thus maintained in an airtight state, processing of the substrate S is performed in the processing space SP.

[0030] In this embodiment, a fluid of a substance usable for supercritical processing, such as carbon dioxide, is supplied to the processing unit 10 from a fluid supply section 57 provided in the supply unit 50 in a gaseous, liquid, or supercritical state. Carbon dioxide is a chemical substance suitable for supercritical drying processing because it reaches a supercritical state at relatively low temperatures and pressures and has the property of dissolving organic solvents commonly used in substrate processing. The critical point at which carbon dioxide reaches a supercritical state is an atmospheric pressure (critical pressure) of 7.38 MPa and a temperature (critical temperature) of 31.1°C.

[0031] More specifically, the fluid supply unit 57 outputs a supercritical fluid or a fluid that is supplied in gaseous or liquid form and subsequently becomes supercritical when subjected to a predetermined temperature and pressure as a processing fluid for processing the substrate S. For example, carbon dioxide heated above its critical temperature is output in a pressurized state. The processing fluid is pressure-fed to input ports 102 and 103, which are arranged vertically (in the Z direction) on the (+Y) side surface of the processing chamber 100 and which each receive a processing fluid supplied to the processing chamber 100 from the outside.

[0032] That is, fluid supply unit 57 and input port 102 are connected by piping 571, and a flow meter 573 and a valve 574 are inserted in piping 571. When valve 574 is opened in response to a control command from control unit 90, the processing fluid is sent from fluid supply unit 57 to processing chamber 100 via input port 102. Flow meter 573 measures the flow rate of the processing fluid sent through piping 571 and transmits the measurement result to control unit 90.

[0033] Similarly, fluid supply unit 57 and input port 103 are connected by piping 572, which has a flow meter 575 and a valve 576 inserted therein. When valve 576 is opened in response to a control command from control unit 90, the processing fluid is sent from fluid supply unit 57 to processing chamber 100 via input port 103. Flow meter 575 measures the flow rate of the processing fluid sent through piping 572 and transmits the measurement result to control unit 90.

[0034] The fluid flow path 17 extending from the input ports 102, 103 to the processing space SP functions as an introduction flow path that introduces the processing fluid supplied from the fluid supply unit 57 into the processing space SP. Specifically, a flow path 171 is connected to the input port 102, which is disposed above the input port 103. A buffer space 172 is provided at the end of the flow path 171 opposite the input port 102, and is formed so that the cross-sectional area of ​​the flow path suddenly increases.

[0035] A flow path 173 is further provided to connect the buffer space 172 and the processing space SP. The flow path 173 has a cross-sectional shape that is narrow in the vertical direction (Z direction) and long and wide in the horizontal direction (X direction), and the cross-sectional shape is approximately constant in the flow direction of the processing fluid. The end of the flow path 171 opposite the buffer space 172 is an outlet 174 that opens toward the processing space SP, and the processing fluid is introduced into the processing space SP from this outlet 174.

[0036] Desirably, the height of the flow path 173 is equal to the distance between the ceiling surface 110a of the processing space SP and the substrate surface Sa when the support tray 15 is accommodated in the processing space SP. The discharge port 174 opens facing the gap between the ceiling surface 110a of the processing space SP and the upper surface 151 of the support tray 15. For example, the ceiling surface of the flow path 173 and the ceiling surface 110a of the processing space SP can be flush with each other. In this way, the discharge port 174 opens in the shape of a horizontally elongated slit facing the processing space SP.

[0037] The flow path 171, buffer space 172, and flow path 173, which constitute the introduction flow path from the input port 102 to the discharge port 174, together form an "upper introduction flow path 17a" that supplies processing fluid to the space within the processing space SP that is sandwiched between the ceiling surface 110a, the upper surface 151 of the support tray 15, and the substrate surface Sa.

[0038] Similarly, a processing fluid flow path 17 (lower introduction flow path 17b) is formed below the support tray 15. Specifically, a flow path 175 is connected to an input port 103 disposed below the input port 102. A buffer space 176 is provided at the end of the flow path 175 opposite the input port 103, and is formed so that the cross-sectional area of ​​the flow path suddenly increases.

[0039] The buffer space 176 and the processing space SP are connected via a flow path 177. The flow path 177 has a cross-sectional shape that is narrow in the vertical direction (Z direction) and long and wide in the horizontal direction (X direction), and the cross-sectional shape is approximately constant in the flow direction of the processing fluid. The end of the flow path 177 opposite the buffer space 176 is an outlet 178 that opens into the processing space SP, and the processing fluid is introduced into the processing space SP from this outlet 178.

[0040] Desirably, the height of the flow path 177 is equal to the distance between the bottom surface 110b of the processing space SP and the lower surface of the support tray 15. The discharge port 178 opens facing the gap between the bottom surface 110b of the processing space SP and the lower surface of the support tray 15. For example, the bottom surface 110b of the flow path 177 and the bottom surface of the processing space SP can be made flush with each other. That is, the discharge port 178 opens in the shape of a horizontally elongated slit facing the processing space SP. The flow path 175, the buffer space 176, and the flow path 177, which constitute an introduction flow path from the input port 103 to the discharge port 178, form a "lower introduction flow path 17b" that supplies the processing fluid to the space sandwiched between the bottom surface 110b of the processing space SP and the lower surface of the support tray 15.

[0041] It is desirable that the positions of the flow paths 171 and 173 are different in the Z direction. When they are at the same height, part of the processing fluid that flows from the flow path 171 into the buffer space 172 flows straight into the flow path 173. This may cause a difference in the flow rate and flow velocity of the processing fluid flowing into the flow path 173 between the position corresponding to the flow path 171 and other positions in the width direction of the flow path, i.e., the X direction, which is perpendicular to the flow direction. This causes non-uniformity in the X direction in the flow of the processing fluid flowing from the flow path 173 into the processing space SP, resulting in turbulence.

[0042] By arranging the flow paths 171 and 173 at different positions in the Z direction, the processing fluid does not flow straight from the flow path 171 to the flow path 173, and the processing fluid can be introduced into the processing space SP as a uniform laminar flow in the width direction. The same concept can be applied to the positional relationship between the flow paths 175 and 177.

[0043] The processing fluid introduced from the inlet flow path 17 configured in this manner flows along the upper and lower surfaces of the support tray 15 within the processing space SP and is discharged to the outside of the processing vessel via the discharge flow path 18 configured as follows. On the (-Y) side of the substrate S, the ceiling surface of the processing space SP and the upper surface 151 of the support tray 15 both form horizontal planes, and they face each other parallel to each other with a certain gap between them. This gap functions as the upstream section 181 of the discharge flow path 18, which guides the processing fluid that has flowed along the upper surface 151 of the support tray 15 and the surface Sa of the substrate S to the fluid discharge section 55. This upstream section 181 has a cross-sectional shape that is narrow in the vertical direction (Z direction) and long and wide in the horizontal direction (X direction).

[0044] The end of the upstream section 181 opposite to the processing space SP is connected to a buffer space 182. The buffer space 182 is a space surrounded by the processing chamber 100, the cover member 14, and the seal member 16. The width of the buffer space 182 in the X direction is equal to or greater than the width of the upstream section 181, and the height of the buffer space 182 in the Z direction is greater than the height of the upstream section 181. Therefore, the buffer space 182 has a larger flow path cross-sectional area than the upstream section 181.

[0045] A downstream portion 183 of the upper discharge flow path is connected to the upper portion of the buffer space 182. The downstream portion 183 is a through-hole that penetrates the first member 11, which is the upper block that constitutes the processing chamber 100. The upper end of the downstream portion 183 forms the output port 104 that opens to the upper surface of the processing chamber 100, and the lower end opens facing the buffer space 182.

[0046] Similarly, the bottom surface of the processing space SP and the lower surface of the support tray 15 both form horizontal planes, and are parallel to each other with a certain gap between them. This gap functions as an upstream portion 185 of the discharge flow path 18 that guides the processing fluid flowing along the lower surface of the support tray 15 to the fluid discharge portion 55. The upstream portion 185 on the lower surface side of the support tray 15 is connected to a downstream portion 187 via a buffer space 186, similar to the upper surface side of the support tray 15.

[0047] The processing fluid that flows above the support tray 15 in the processing space SP is sent to the output port 104 via an upstream section 181, a buffer space 182, and a downstream section 183 that constitute the upper discharge flow path of the discharge flow path 18. The output port 104 is connected to the fluid discharge part 55 by a pipe 551, and a flow meter 552, a valve 553, and a pressure gauge 554 are inserted in the middle of the pipe 551. To reduce detection errors due to pressure loss in the flow path, it is desirable to install the flow meter 552 and the pressure gauge 554 as upstream as possible in the discharge flow path.

[0048] Similarly, the processing fluid that has flowed below the support tray 15 in the processing space SP is sent to the output port 105 via an upstream section 185, a buffer space 186, and a downstream section 187 that constitute the lower discharge flow path of the discharge flow path 18. The output port 105 is connected to the fluid discharge unit 55 by a pipe 555, and a flow meter 556 and a valve 557 are inserted in the middle of the pipe 555. Note that a pressure gauge may also be connected to the pipe 555, similar to the pipe 551.

[0049] The valves 553 and 557 are controlled by the control unit 90. When the valves 553 and 557 are opened in response to a control command from the control unit 90, the processing fluid in the processing space SP is collected in the fluid discharge part 55 via the pipes 551 and 555.

[0050] In this manner, in the substrate processing apparatus 1, the upstream portion 181, the buffer space 182, and the downstream portion 183 of the discharge flow path 18, together with the piping 551, constitute an "upper discharge flow path 18a" that discharges the processing fluid that passes through the upper surface side of the substrate S within the processing space SP. In addition, the upstream portion 185, the buffer space 186, and the downstream portion 187 of the discharge flow path 18, together with the piping 555, constitute a "lower discharge flow path 18b" that discharges the processing fluid that passes through the lower surface side of the support tray 15 within the processing space SP.

[0051] The upper discharge flow path 18a and the lower discharge flow path 18b are provided with flow meters 552 and 556, respectively, that detect the flow rate of the fluid. As the flow meters 552 and 556, it is possible to use meters based on various principles that can detect the flow rate of the fluid in the flow path, such as a mass flow meter, or more specifically, a Coriolis flow meter.

[0052] FIG. 2 is a flowchart showing an outline of the processing executed by this substrate processing apparatus. FIG. 3 is a timing chart showing the state changes of each part of the apparatus during this processing. This substrate processing apparatus 1 executes a supercritical drying process, i.e., a process for drying a substrate S that has been cleaned with a cleaning liquid in a pre-process. Specifically, this process is as follows. The substrate S to be processed is cleaned with a cleaning liquid in a pre-process executed in another substrate processing apparatus constituting the substrate processing system. Thereafter, the substrate S is transported to the substrate processing apparatus 1 with a liquid film of an organic solvent, such as isopropyl alcohol (IPA), formed on its surface.

[0053] For example, if a fine pattern is formed on the surface of the substrate S, the surface tension of the liquid remaining on the substrate S may cause the pattern to collapse. Also, incomplete drying may leave watermarks on the surface of the substrate S. Furthermore, exposure of the surface of the substrate S to the outside air may cause deterioration such as oxidation. To prevent such problems from occurring, the surface of the substrate S (the surface on which the pattern is formed) may be transported while covered with a liquid or solid surface layer.

[0054] For example, if the cleaning liquid is mainly water, the substrate S is transported in a state in which a liquid film is formed using a liquid that has a lower surface tension and is less corrosive to the substrate, such as an organic solvent such as IPA or acetone. That is, the substrate S is supported horizontally and transported to the substrate processing apparatus 1 in a state in which a liquid film is formed on its upper surface.

[0055] The substrate S transported by a transport device (not shown) is accommodated in the processing chamber 100 (step S101). Specifically, the substrate S is transported with the pattern-formed surface facing up and the upper surface covered with a thin liquid film. The substrate S is transferred to the support tray 15 via lift pins (not shown). That is, with the lid member 14 moving toward the (-Y) side and the support tray 15 pulled out, the lift pins advance above the upper surface 151 of the support tray 15 through through-holes (not shown) provided in the support tray 15. The transport device transfers the substrate S to the lift pins, and the lift pins descend, placing the substrate S on the support tray 15. When the support tray 15 and the lid member 14 move together in the (+Y) direction, the support tray 15 supporting the substrate S is accommodated in the processing space SP within the processing chamber 100, and the opening 101 is closed by the lid member 14.

[0056] In Figure 3, the period before time T0 corresponds to the substrate loading process. When the support tray 15 is pulled out of the chamber and the substrate S is loaded, all of the valves 553, 557, 574, and 576 are closed. Therefore, the supply and discharge amounts of processing fluid to the processing space SP are zero. Also, at this time, the pressure within the processing space SP (hereinafter referred to as the "chamber pressure") is atmospheric pressure Pa, and the processing space SP is in an atmospheric atmosphere.

[0057] From this state, carbon dioxide as a processing fluid is introduced into the processing space SP. Specifically, this is as follows. Of the two discharge ports provided facing the processing space SP in the vertical direction, the processing fluid starts to be discharged first from the lower discharge port, i.e., the discharge port 178 (step S102, time T0). Specifically, the valve 576 is opened, and the processing fluid is sent from the pipe 572 toward the discharge port 178. As a result, the processing fluid is supplied to the processing space SP at a predetermined flow rate from the lower introduction flow path 17b (simply referred to as "lower" in FIG. 3), and the processing fluid is discharged toward the space below the support tray 15 in the processing space SP.

[0058] When the high-pressure processing fluid flows into the lower-pressure processing space SP, the fluid pressure temporarily drops and the processing fluid changes phase to gas or liquid, but as the supply continues, the chamber pressure gradually increases. This state is maintained until the chamber pressure reaches the critical pressure Pc of the processing fluid (step S103). The chamber pressure can be detected by a pressure gauge 554. The determination in step S103 can be made by comparing the detection result of the pressure gauge 554 with a threshold value set to the critical pressure Pc or a value slightly higher than that (e.g., 7.5 MPa).

[0059] Although it is preferable in principle to determine time T1 from the detection result of the chamber pressure, if the amount of processing fluid introduced into the processing space SP is appropriately controlled, it is possible to reproducibly estimate the timing at which the chamber pressure will reach the critical pressure Pc. Therefore, for example, a processing recipe may be set by experimentally determining in advance the time from when the introduction of the processing fluid begins until the chamber pressure reaches the critical pressure Pc, and it may be determined that the chamber pressure has reached the critical pressure Pc when that time has elapsed since the start of the supply of the processing fluid.

[0060] After time T1 when the pressure inside the chamber reaches the critical pressure Pc, the valve 574 is opened, and the processing fluid that has been fed through the upper inlet flow path 17a (simply referred to as "upper" in FIG. 3) at a predetermined flow rate is discharged from the upper discharge port 174 (step S104). The discharged processing fluid flows in the (-Y) direction in the space between the ceiling surface 110a of the processing space SP and the substrate surface Sa. That is, a laminar flow of the processing fluid is formed along the substrate surface Sa. Because the pressure inside the chamber exceeds the critical pressure Pc, a laminar flow of the processing fluid in a supercritical state is formed.

[0061] In this way, the processing fluid is supplied above the substrate S and below the support tray 15, respectively, thereby further increasing the pressure inside the chamber. Once the pressure inside the chamber reaches the preset target pressure Pt, that state is maintained for a predetermined time (step S105, times T2 to T3). For example, by setting the pressure of the processing fluid output from the fluid supply unit 57 to the target pressure Pt in advance, the pressure inside the chamber can be maintained at the target pressure Pt. The value of the target pressure Pt is set to a value sufficiently larger than the critical pressure Pc; for example, for carbon dioxide, whose critical pressure Pc is 7.38 MPa, the target pressure Pt can be set to approximately 10 to 12 MPa.

[0062] 3, the period from time T0 to time T2 is a "pressure-up process" in which the chamber internal pressure is increased over time. During the pressure-up process, before the chamber internal pressure reaches the critical pressure Pc, the processing fluid is discharged only from the lower outlet 178. After the chamber internal pressure reaches the critical pressure Pc, the processing fluid is discharged from the upper outlet 174 in addition to the lower outlet 178.

[0063] On the other hand, the period from time T2 to time T3 is a "constant pressure processing step" in which the chamber internal pressure is maintained at the target pressure Pt. During this time, the processing space SP is filled with the processing fluid in a supercritical state, so that the liquid film covering the substrate surface Sa is replaced by the processing fluid, and the liquid detached from the substrate S is dissolved in the processing fluid. The constant pressure processing step continues until the liquid is completely replaced.

[0064] After the constant-pressure processing step continues for a predetermined time, a "depressurization step" is performed in which the processing fluid is discharged from the processing space SP to reduce the pressure inside the chamber (step S106, time T3). Specifically, valves 574 and 576 are closed to stop the discharge of the processing fluid from the discharge ports 174 and 178, and instead valves 553 and 555 are opened to discharge the processing fluid from the processing space SP. Liquid components and contaminants that have detached from the substrate S and are dissolved in the processing fluid are also discharged outside the chamber together with the processing fluid. In the figure, the upper discharge flow path 18a and the lower discharge flow path 18b are simply abbreviated as "upper" and "lower," respectively.

[0065] At this time, the discharge amount is relatively small, and the pressure inside the chamber decreases gradually. This prevents the processing fluid from liquefying or solidifying due to a temperature drop caused by a sudden pressure reduction. Note that, in this case, both valves 553 and 555 are opened, and the processing fluid is discharged from both the upper discharge flow path 18a and the lower discharge flow path 18b. However, the processing fluid may be discharged from either the upper or lower side.

[0066] When it is determined that the pressure inside the chamber has dropped to the critical pressure Pc (step S107, time T4), the discharge rate of the processing fluid is increased (step S108). This increases the depressurization rate. Because the processing fluid has changed from a supercritical state to a gas phase when the pressure drops below the critical pressure Pc, increasing the depressurization rate will not liquefy the processing fluid and create a gas-liquid interface. This reduces the time required for the depressurization process. In this case, the pressure inside the chamber may be determined based on the detection result of the pressure gauge 554 or based on a preset time.

[0067] After time T5 when the pressure inside the chamber drops to approximately atmospheric pressure Pa, the processed substrate S can be unloaded from the processing chamber 100 (step S109). This completes the drying process for one substrate S. If there is a new substrate to be processed next, the process returns to step S101 to accept the new substrate S, and the above process is repeated (step S110).

[0068] As described above, in the supercritical drying process of this embodiment, the supply of processing fluid is started to the space below the support tray 15 that supports the substrate S in the processing space SP, and after the chamber internal pressure exceeds the critical pressure Pc in this state, the processing fluid is additionally supplied above the substrate S. Therefore, in the initial stage of introducing the processing fluid, that is, when the pressure in the processing chamber 100 is low, the high-velocity processing fluid is prevented from spraying onto the liquid film covering the substrate S. This makes it possible to prevent processing defects such as pattern collapse that occur when the liquid film is lost and the substrate surface Sa is exposed.

[0069] The problem of pattern collapse due to spraying of the processing fluid and the solution of supplying the processing fluid from below the substrate are also described in the aforementioned Patent Document 2. However, in the conventional technology of Patent Document 2, the pressure is increased to a target pressure sufficiently higher than the critical pressure only by supplying the processing fluid from below. In contrast, in this embodiment, when the pressure inside the chamber reaches the critical pressure Pc, the processing fluid is also supplied to the space above the substrate S. Therefore, it is possible to further shorten the time required to reach the target pressure.

[0070] When the processing fluid is close to but not yet in a supercritical state, for example, when the chamber internal pressure is about 5 to 6 MPa, a phenomenon has been observed in which a large amount of processing fluid dissolves in the liquid that makes up the liquid film, significantly reducing the viscosity of the liquid, causing the liquid film to no longer be maintained and spill off the substrate. If this phenomenon occurs when the surrounding area is not filled with supercritical fluid, the substrate surface may be exposed, resulting in processing defects.

[0071] On the other hand, in an environment filled with a supercritical processing fluid, which has extremely low surface tension and dissolves liquids well, the liquid dissolves quickly into the processing fluid, and even if the liquid film breaks, it does not cause damage to the substrate. In other words, the reason why pattern collapse occurs due to the spraying of the processing fluid is thought to be that the processing fluid, which is sprayed at such a high flow rate, is in a liquid or gas state due to a pressure drop. Therefore, once the processing fluid becomes supercritical, damage due to the spraying of the processing fluid does not need to be a concern. From this perspective, in this embodiment, the flow of the processing fluid above the substrate S begins when the chamber internal pressure exceeds the critical pressure Pc, thereby shortening the processing time compared to conventional techniques.

[0072] Furthermore, in the above-described conventional technology, once the chamber pressure reaches the target pressure, the supply of processing fluid from below is stopped and the processing fluid is stirred above the substrate, thereby improving processing efficiency. In contrast, in this embodiment, the processing fluid is supplied to form a horizontal, unidirectional laminar flow both above the substrate S and below the support tray 15. Supplying the processing fluid in this manner suppresses the generation of turbulence around the substrate S and enables liquid, contaminants, and the like that have detached from the substrate S to be quickly moved away from the substrate S, preventing reattachment. Thus, this embodiment differs from the above-described conventional technology in terms of the action of the processing fluid flowing along the substrate surface.

[0073] In the supercritical drying process of the above embodiment, the processing fluid is not discharged during the pressurization step. However, as shown in the following modified example, a small amount of processing fluid may be discharged in parallel, for example, to purge the processing space SP of residual outside air or contaminants.

[0074] 4 to 6 are timing charts showing modified examples of the supercritical drying process, in which only the timing of the start of discharge, indicated by the outline arrow, differs from the process shown in FIG.

[0075] 4, when the supply of the processing fluid from the upper inlet flow path 17a starts in the pressure increase step, the discharge of the processing fluid through the upper outlet flow path 18a starts. Since the liquid that constituted the liquid film is dissolved in the processing fluid flowing above the substrate S, by starting the discharge from the upper outlet flow path 18a after the processing fluid becomes supercritical, the liquid components that have separated from the substrate S can be quickly discharged outside the chamber. This reduces the amount of liquid components remaining in the chamber in the subsequent constant pressure processing step, improving replacement efficiency.

[0076] 5, when the supply of the processing fluid from the upper inlet flow path 17a starts during the pressurization step, the discharge of the processing fluid starts via the lower discharge flow path 18b instead of the upper discharge flow path 18a. In the processing space SP, below the support tray 15, some of the liquid constituting the liquid film may fall due to a decrease in viscosity caused by vibrations during substrate loading or by the inclusion of processing fluid. By discharging the liquid from the space below the support tray 15, it is possible to quickly remove such liquid components.

[0077] 6, the first and second modifications are combined to discharge the treatment fluid from both the upper discharge flow path 18a and the lower discharge flow path 18b, thereby achieving the effects of both the first and second modifications.

[0078] Furthermore, the pressure increase rate can be controlled by adjusting the balance between the supply and discharge rates of the processing fluid during the pressure increase step. Moreover, such adjustments can be performed separately for the space above the substrate S and the space below the support tray 15 within the processing space SP. In either example, it is not preferable to discharge the processing fluid before time T1 when the processing fluid becomes supercritical, because this reduces the pressure increase rate before the processing fluid reaches the supercritical state, thereby increasing the risk of liquid film breakdown.

[0079] As described above, in the substrate processing apparatus 1 of the above embodiment, the processing space SP inside the processing chamber 100 corresponds to the "internal space" of the present invention. In the processing chamber 100, the lower discharge port 178 corresponds to the "first discharge port" of the present invention, and the upper discharge port 174 corresponds to the "second discharge port" of the present invention. The lower discharge flow path 18b and the upper discharge flow path 18a function as the "first discharge flow path" and the "second discharge flow path" of the present invention, respectively.

[0080] In the above embodiment, the support tray 15 functions as a "support member" of the present invention. The control unit 90 functions as a "controller" of the present invention. In the supercritical drying process of FIG. 2, step S101 corresponds to the "first step" of the present invention, steps S102 to S105 correspond to the "second step" of the present invention, and steps S106 to S108 correspond to the "third step" of the present invention. In the above embodiment, the critical pressure Pc corresponds to the "first pressure" of the present invention, and the target pressure Pt corresponds to the "second pressure" of the present invention.

[0081] The present invention is not limited to the above-described embodiment, and various modifications other than those described above are possible without departing from the spirit of the present invention. For example, in the above-described embodiment, the critical pressure Pc of carbon dioxide, which is the processing fluid, is used as the value corresponding to the "first pressure" of the present invention in order to explain the principle. However, in actual processing, it is preferable to use a value slightly higher than the critical pressure (e.g., 7.5 MPa compared to the critical pressure of carbon dioxide of 7.38 MPa) for the first pressure to more reliably ensure that the processing fluid is in a supercritical state regardless of the influence of measurement error, etc.

[0082] For example, in the supercritical drying process of the above embodiment, a constant pressure process and a depressurization process are provided after the pressure increase process, and the depressurization rate is changed in two stages in the depressurization process. However, the present invention is characterized by the process when the pressure inside the chamber is increased from approximately atmospheric pressure to a target pressure higher than the critical pressure, and the processing contents before and after this are not limited to those described above.

[0083] Furthermore, the substrate processing apparatus 1 of the above embodiment is provided with instruments for measuring the flow rate and pressure of the processing fluid. However, if the processing can be performed with high reproducibility by using a processing recipe created based on the results of preliminary experiments, at least some of these instruments may be omitted. Of course, these instruments can be used to monitor whether the processing is being performed according to the recipe.

[0084] Furthermore, the various chemical substances and set values ​​used in the processing of the above-described embodiment are only examples, and various other substances can be used instead as long as they are consistent with the technical concept of the present invention described above.

[0085] As described above by way of example of specific embodiments, in the substrate processing method of the present invention, for example, the second step may be configured to start supplying the processing fluid from the second outlet after the pressure in the internal space reaches a first pressure that is equal to or greater than the critical pressure after the supply of the processing fluid from the first outlet has started, and the third step may be performed after the pressure in the internal space reaches a second pressure that is greater than the first pressure after the supply of the processing fluid from the second outlet has started.

[0086] With this configuration, the timing to start ejection from the second ejection port and the timing to start the third step can be determined based on a comparison between the internal pressure of the processing chamber and predetermined values ​​(first pressure, second pressure).

[0087] Alternatively, for example, the third step may be performed after the pressure in the internal space has been equal to or greater than the second pressure for a predetermined period of time. By maintaining the pressure inside the processing chamber at a pressure greater than the critical pressure in this manner, the liquid adhering to the substrate can be sufficiently replaced and removed from the substrate.

[0088] Alternatively, for example, the processing fluid may be pressurized to a pressure higher than the critical pressure and supplied to the first and second outlets. With this configuration, the processing fluid is supplied at a sufficiently high pressure, and a supercritical state can be achieved in the internal space of the processing chamber in a short period of time.

[0089] In this case, the processing fluid may be supplied to the first outlet and the second outlet at a temperature higher than the critical temperature. With this configuration, the processing fluid in a supercritical state can be immediately supplied to the internal space, and the processing fluid can be changed to any phase by adjusting the pressure as needed.

[0090] Furthermore, for example, in the third step, the processing fluid may be discharged from the inner space on the opposite side of the substrate from the first discharge port, or the processing fluid may be discharged from the inner space on the opposite side of the substrate from the second discharge port. With this configuration, the processing fluid forms a laminar flow that flows in one direction in the inner space, and therefore, liquid components and contaminants that have migrated from the substrate to the processing fluid can be prevented from adhering again to the substrate.

[0091] In the substrate processing apparatus according to the present invention, the first and second outlets are preferably arranged in the same direction as seen from the substrate in a side view. With this configuration, in the internal space, a flow of processing fluid is formed in the same direction above the substrate and below the support member, thereby suppressing the generation of turbulence that may cause substrate contamination.

[0092] In this case, a first discharge flow path may be provided in the internal space to discharge the processing fluid from the opposite side of the first outlet with the substrate sandwiched therebetween, and a second discharge flow path may be provided in the internal space to discharge the processing fluid from the opposite side of the second outlet with the substrate sandwiched therebetween, and the fluid discharge unit may be configured to discharge the processing fluid from the internal space via the first discharge flow path and the second discharge flow path. With this configuration, the flow of the processing fluid that forms a laminar flow can be made smoother, and contamination of the substrate due to turbulence can be more effectively prevented.

[0093] Furthermore, the control unit may be configured to control the fluid discharge unit to independently discharge the processing fluid through the first discharge flow path and the second discharge flow path, which allows the processing fluid to be selectively discharged from the space above the substrate and the space below the support member depending on the purpose. [Industrial Applicability]

[0094] The present invention can be applied to general substrate processing techniques using supercritical processing fluids in a processing chamber, for example, to a substrate drying process in which a substrate such as a semiconductor substrate is dried using a supercritical fluid. [Explanation of symbols]

[0095] 1. Substrate processing equipment 15 Support tray (support member) 18a Upper discharge flow path (second discharge flow path) 18b Lower discharge channel (first discharge channel) 90 Control unit (control section) 100 processing chamber 174 Discharge port (second discharge port) 178 Discharge port (1st discharge port) Pc Critical pressure (first pressure) Pt Target pressure (second pressure) S board S101 1st process S102~S105 2nd process S106~S108 3rd process SP Processing space (internal space)

Claims

1. 1. A substrate processing method for processing a substrate with a processing fluid in a supercritical state, comprising: a first step of placing the substrate, the upper surface of which is covered with a liquid film, in a horizontal position on a flat support member and accommodating the substrate in an internal space of a processing chamber; a second step of filling the internal space with the processing fluid in a supercritical state; a third step of discharging the treatment fluid from the internal space; Equipped with a first outlet port that discharges the processing fluid horizontally toward a space between a bottom surface of the wall surface and a lower surface of the support member, and a second outlet port that discharges the processing fluid horizontally toward a space between a ceiling surface of the wall surface and an upper surface of the substrate, the first outlet port being provided on a side wall surface of the wall surface that constitutes the internal space; In the second step, supplying the pressurized processing fluid from the first discharge port to the internal space to increase the pressure in the internal space; a supply of the pressurized processing fluid from the second outlet to the internal space after the internal pressure of the internal space exceeds a critical pressure of the processing fluid, in addition to the supply from the first outlet, of the processing fluid.

2. In the second step, after the supply of the processing fluid from the first discharge port is started, the supply of the processing fluid from the second discharge port is started after the pressure in the internal space reaches a first pressure that is equal to or higher than the critical pressure, 2. The substrate processing method according to claim 1, wherein the third step is performed after the pressure in the internal space reaches a second pressure higher than the first pressure after the supply of the processing fluid from the second outlet is started.

3. The substrate processing method according to claim 2 , wherein the third step is performed after a period during which the pressure in the internal space is equal to or higher than the second pressure has continued for a predetermined time.

4. 2. The substrate processing method according to claim 1, wherein the processing fluid is pressurized to a pressure higher than the critical pressure and supplied to the first outlet and the second outlet.

5. 5. The substrate processing method according to claim 4, wherein the processing fluid is supplied to the first outlet and the second outlet at a temperature higher than a critical temperature.

6. 2. The substrate processing method according to claim 1, wherein in the third step, the processing fluid is discharged from a side of the internal space opposite to the first discharge port with the substrate sandwiched therebetween.

7. 7. The substrate processing method according to claim 1, wherein in the third step, the processing fluid is discharged from a side of the internal space opposite to the second discharge port with the substrate sandwiched therebetween.

8. 1. A substrate processing apparatus for processing a substrate with a processing fluid in a supercritical state, a flat support member on which the substrate can be placed; a processing chamber having an internal space capable of accommodating the support member together with the substrate in a horizontal position; a fluid supply unit that supplies the processing fluid to the internal space; a fluid discharge portion that discharges the processing fluid from the internal space; a control unit that controls the fluid supply unit; Equipped with a first outlet port that discharges the processing fluid horizontally toward a space between a bottom surface of the wall surface and a lower surface of the support member, and a second outlet port that discharges the processing fluid horizontally toward a space between a ceiling surface of the wall surface and an upper surface of the substrate, the first outlet port being provided on a side wall surface of the wall surface that constitutes the internal space; When the support member on which the substrate is placed is accommodated in the internal space, the control unit controls the fluid supply unit, supplying the processing fluid from the first outlet to the internal space to increase the pressure in the internal space; When the internal pressure of the internal space exceeds a critical pressure of the processing fluid, in addition to the supply from the first outlet, the supply of the processing fluid to the internal space from the second outlet is started. Substrate processing equipment.

9. The substrate processing apparatus according to claim 8 , wherein the first discharge port and the second discharge port are provided in the same direction as seen from the substrate in a side view.

10. a first discharge flow path that discharges the processing fluid from an opposite side of the first discharge port across the substrate in the internal space, and a second discharge flow path that discharges the processing fluid from an opposite side of the second discharge port across the substrate in the internal space, The substrate processing apparatus of claim 8 , wherein the fluid discharge unit discharges the processing fluid from the internal space through the first discharge flow path and the second discharge flow path.

11. 11. The substrate processing apparatus of claim 10, wherein the control unit controls the fluid discharge unit and causes the discharge of the processing fluid via the first discharge flow path and the discharge of the processing fluid via the second discharge flow path to be performed independently.

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