SUBSTRATE PROCESSING METHOD AND SUBSTRATE PROCESSING APPARATUS

Abstract

To provide technology that processes a substrate with a processing fluid in a supercritical state in a chamber, and can obtain stable processing efficiency especially when processing a plurality of substrates in order by appropriately controlling the temperature in the chamber after processing.SOLUTION: A decompression process after processing a substrate with a processing fluid in the supercritical state in a chamber is divided into two steps. In a first decompression process, an internal space of the chamber is decompressed to a pressure lower than the critical pressure and higher than the atmospheric pressure while maintaining the temperature of the inner space of the chamber at or above the critical temperature of the processing fluid. In the second decompression process, the processing fluid is discharged at a higher discharge rate than in the first decompression step to decompress the internal space. At this time, the discharge speed is controlled such that the temperature of the internal space reaches a predetermined target temperature when the pressure of the internal space decreases to the atmospheric pressure.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 chamber, and more particularly to a process for exhausting the processing fluid from the chamber. [Background technology]

[0002] Processing of various substrates such as semiconductor substrates and glass substrates for display devices includes processing of the substrate surface with various processing fluids. Processing using liquids such as chemicals and rinsing liquids as processing fluids has been widely used in the past, but processing using supercritical fluids has also been put to practical use in recent years. In particular, in processing of substrates having fine patterns formed on their surfaces, supercritical fluids, which have lower surface tension than liquids, can penetrate deep into gaps in the patterns, making it possible to perform processing efficiently and reducing the risk of pattern collapse due to surface tension during drying.

[0003] For example, Patent Document 1 describes a substrate processing apparatus that replaces liquid adhering to a substrate with a supercritical fluid and performs a drying process on the substrate. More specifically, Patent Document 1 describes in detail the flow of a drying process when carbon dioxide is used as the supercritical processing fluid and IPA (isopropyl alcohol) is used as the liquid to be replaced by the supercritical processing fluid. That is, a chamber containing a substrate is filled with the processing fluid, and after maintaining a state in which the chamber exceeds both the critical pressure and the critical temperature of the processing fluid for a certain period of time, the chamber is depressurized and a series of processes is completed. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2018-081966 A Summary of the Invention [Problem to be solved by the invention]

[0005] In the above-mentioned conventional technology, the supercritical state is maintained mainly by pressure control that repeats pressure increase and decrease, but it is more preferable to maintain the temperature and pressure of the supercritical fluid constant during processing. This is because the density change of the supercritical fluid, particularly with temperature change, is very large, and for example, in processing aimed at replacing liquid, the processing efficiency changes greatly depending on the density of the processing fluid. More specifically, the higher the concentration of the supercritical processing fluid, the more other liquid it can take in, so the higher the liquid replacement efficiency becomes, and the lower the temperature of the supercritical processing fluid, the higher the concentration becomes. Therefore, it is preferable that the processing fluid is as low and constant as possible within the range in which the supercritical state can be maintained.

[0006] Since the temperature of the processing fluid is also affected by the temperature inside the chamber when the processing fluid is introduced into the chamber, it is required that the temperature inside the chamber at the time of introduction is kept constant and appropriate. However, the above-mentioned conventional technology does not take this into consideration, and the temperature inside the chamber is not controlled at times other than during processing, especially during the depressurization process. Therefore, especially when multiple substrates are processed in sequence, the processing efficiency may decrease and the processing results may vary if the next substrate and processing fluid are introduced into a chamber that has been heated by processing the previous substrate.

[0007] 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 chamber in a supercritical state, which can appropriately manage the temperature in the chamber after processing, thereby achieving stable processing efficiency, particularly when multiple substrates are processed in sequence. [Means for solving the problem]

[0008] One aspect of the present invention is a substrate processing method for processing a substrate with a processing fluid in a supercritical state in a chamber, which, in order to achieve the above object, includes a supercritical processing step of introducing the processing fluid into an internal space of the chamber accommodating the substrate, and processing the substrate by maintaining the pressure of the internal space higher than the critical pressure of the processing fluid and the temperature of the internal space higher than the critical temperature of the processing fluid, a first depressurization step of discharging the processing fluid from the chamber and depressurizing the internal space to a pressure lower than the critical pressure and higher than atmospheric pressure while maintaining the temperature of the internal space equal to or higher than the critical temperature of the processing fluid, and a second depressurization step of discharging the processing fluid at a discharge rate higher than that of the first depressurization step to depressurize the internal space. adiabatically expanding the treatment fluid in the internal space to reduce the temperature of the internal space; The discharge rate is controlled so that the temperature of the interior space is at a predetermined target temperature when the pressure in the interior space drops to atmospheric pressure.

[0009] Another aspect of the present invention is a substrate processing apparatus for processing a substrate with a processing fluid in a supercritical state, which, to achieve the above object, comprises a chamber for accommodating the substrate in an internal space, a fluid supply unit for supplying the processing fluid to the internal space of the chamber, a fluid discharge unit for discharging the processing fluid from the internal space, and a control unit for controlling the fluid supply unit and the fluid discharge unit. The control unit controls the fluid supply unit to supply the processing fluid to the internal space, to maintain a pressure in the internal space higher than the critical pressure of the processing fluid and a temperature in the internal space higher than the critical temperature of the processing fluid, and then controls the fluid discharge unit to discharge the processing fluid from the chamber, to reduce the pressure of the internal space to a pressure lower than the critical pressure and higher than atmospheric pressure while maintaining a temperature in the internal space equal to or higher than the critical temperature of the processing fluid, and further controls the fluid discharge unit to increase a discharge rate of the processing fluid by the fluid discharge unit, The processing fluid in the internal space is adiabatically expanded to lower the temperature of the internal space, The interior space is depressurized to atmospheric pressure and the evacuation rate is controlled so that the temperature of the interior space is at a predetermined target temperature when the pressure in the interior space is reduced to atmospheric pressure.

[0010] As used herein, "exhaust rate" refers to the mass of process fluid exhausted from the chamber per unit time.

[0011] In the invention configured as described above, after the substrate is processed with the processing fluid in a supercritical state where both the pressure and temperature exceed the critical points, the process for discharging the processing fluid from the chamber is divided into two stages. That is, in the first stage, the pressure inside the chamber is reduced to a pressure lower than the critical pressure while maintaining the temperature above the critical point. This causes the processing fluid to transition from the supercritical state to the gas phase without passing through the liquid phase. Therefore, even if a fine pattern is formed on the substrate, the problem of pattern collapse caused by the phase change from the liquid phase to the gas phase is avoided.

[0012] The manner of decompression from a state in which the chamber is filled with gas-phase processing fluid below the critical pressure can be said to be relatively flexible as long as no phase transition to liquid phase occurs. For example, the processing fluid remaining in the chamber may be immediately discharged and the chamber may be decompressed to atmospheric pressure. This can shorten the time until the substrate is removed from the chamber after processing.

[0013] In contrast, in the second stage of the decompression process of the present invention, the temperature inside the chamber at the processing flow rate is controlled by utilizing the adiabatic expansion that occurs inside the chamber when the processing fluid is discharged. Specifically, the processing fluid is discharged at a higher discharge speed than in the first stage of decompression described above, causing the processing fluid in the chamber to expand in a short period of time, and causing adiabatic expansion, thereby lowering the temperature in the chamber internal space. Here, the "temperature of the internal space" is a concept that preferably refers to the temperature of the surface of a member facing the internal space, for example, the chamber wall surface, but can be more simply expressed by the temperature of the fluid inside the chamber.

[0014] In the second stage of depressurization, the discharge speed is controlled so that the internal temperature is a predetermined target temperature when the internal space is depressurized to atmospheric pressure. Therefore, the temperature inside the chamber is the target temperature when the pressure inside the chamber is depressurized to atmospheric pressure. In this way, by managing the depressurization using the temperature of the internal space of the chamber as an index, the temperature inside the chamber can be kept at an appropriate temperature when depressurization is completed. As a result, even when processing multiple substrates is performed continuously, the temperature inside the chamber can be kept constant when processing each substrate is started, and temperature variations in the processing fluid introduced can be suppressed, making it possible to stabilize the processing results. Effect of the Invention

[0015] As described above, in the present invention, the progress of the pressure reduction after the processing fluid in the chamber transitions from the supercritical state to the gas phase is managed using the temperature in the chamber as an index. Therefore, the temperature in the chamber after the processing of one substrate is completed can be appropriately managed, and even when multiple substrates are processed in sequence, the temperature variation of the supercritical processing fluid for each processing can be suppressed, and stable processing efficiency can be obtained. [Brief description of the drawings]

[0016] [Figure 1] 1 is a diagram showing a schematic configuration of an embodiment of a substrate processing apparatus according to the present invention; [Diagram 2] 3 is a flowchart showing an outline of a process executed by the substrate processing apparatus. [Diagram 3] FIG. 2 is a diagram showing a schematic diagram of a temperature change in a chamber during supercritical processing. [Figure 4] FIG. 2 is a phase diagram showing phase changes in the supercritical processing of the present embodiment. [Diagram 5] 4 is a timing chart showing state changes of each part during supercritical processing. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0017] Fig. 1 is a diagram showing a schematic configuration of one embodiment 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, by using a supercritical fluid, and has an apparatus configuration suitable for carrying out a substrate processing method according to the present invention. In order to unify directions in the following description, 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.

[0018] As the "substrate" in this embodiment, 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, and substrates for magneto-optical disks can be applied. In the following, a substrate processing apparatus used mainly for processing disc-shaped semiconductor wafers will be described with reference to the drawings. However, the present invention can be applied to the processing of the various substrates exemplified above. Various substrate shapes can also be applied.

[0019] The substrate processing apparatus 1 includes a processing unit 10, a transfer unit 30, a supply unit 50, and a control unit 90. The processing unit 10 is a main body that executes the supercritical drying process. The transfer unit 30 receives an unprocessed substrate S transported by an external transport device (not shown) and transports it into the processing unit 10, and also transfers the processed substrate S from the processing unit 10 to the external transport device. The supply unit 50 supplies chemical substances, power, energy, etc. required for processing to the processing unit 10 and the transfer unit 30.

[0020] The control unit 90 controls each part of these devices to realize predetermined processing. For this purpose, the control unit 90 is equipped with a CPU 91, a memory 92, a storage 93, an interface 94, and the like. The CPU 91 executes various control programs. The memory 92 temporarily stores processing data. The storage 93 stores the control programs executed by the CPU 91. The interface 94 exchanges information with a user and an external device. The operation of the devices described below is realized by the CPU 91 executing the control programs written in advance in the storage 93 and causing each part of the devices to perform a predetermined operation.

[0021] The processing unit 10 has a structure in which a processing chamber 12 is attached on a base 11. The processing chamber 12 is constructed by combining several metal blocks, and its interior is hollow to form a processing space SP. The substrate S to be processed is loaded into the processing space SP and processed. A slit-shaped opening 121 that is elongated and extends in the X direction is formed on the (-Y) side surface of the processing chamber 12. The processing space SP communicates with the outside space via the opening 121. The cross-sectional shape of the processing space SP is approximately the same as the opening shape of the opening 121. In other words, the processing space SP has a cross-sectional shape that is long in the X direction and short in the Z direction, and is a cavity that extends in the Y direction.

[0022] A lid member 13 is provided on the (-Y) side surface of the processing chamber 12 so as to close the opening 121. The lid member 13 closes the opening 121 of the processing chamber 12 to form an airtight processing container. This allows the substrate S to be processed under high pressure in the internal processing space SP. A flat support tray 15 is attached in a horizontal position to the (+Y) side surface of the lid member 13. An upper surface 151 of the support tray 15 serves as a support surface on which the substrate S can be placed. The lid member 13 is supported by a support mechanism (not shown) so as to be freely movable horizontally in the Y direction.

[0023] The lid member 13 can be moved forward and backward relative to the processing chamber 12 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, an air cylinder, or the like. Such a linear motion mechanism moves the lid member 13 in the Y direction. The advance / retract mechanism 53 operates in response to a control command from the control unit 90.

[0024] When the cover member 13 moves in the (-Y) direction to move away from the processing chamber 12 and the support tray 15 is pulled out from the processing space SP through the opening 121 as shown by the dotted line, access to the support tray 15 becomes possible. 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 13 moves in the (+Y) direction, the support tray 15 is accommodated in the processing space SP. When the 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.

[0025] The lid member 13 moves in the (+Y) direction to close the opening 121, thereby sealing the processing space SP. A seal member 122 is provided between the (+Y) side surface of the lid member 13 and the (-Y) side surface of the processing chamber 12 to keep the processing space SP airtight. The seal member 122 is made of rubber, for example. The lid member 13 is fixed to the processing chamber 12 by a locking mechanism (not shown). Thus, in this embodiment, the lid member 13 can be switched between a closed state (solid line) in which the opening 121 is closed to seal the processing space SP, and a separated state (dotted line) in which the lid member 13 is significantly separated from the opening 121 to allow the substrate S to be inserted and removed.

[0026] With the airtight state of the processing space SP ensured, processing of the substrate S is performed in the processing space SP. In this embodiment, a processing fluid of a substance that can be used for supercritical processing, such as carbon dioxide, is delivered as the processing fluid from the fluid supply unit 57 provided in the supply unit 50. The processing fluid is supplied to the processing unit 10 in a gaseous, liquid or supercritical state. Carbon dioxide is a chemical substance suitable for supercritical drying processing in that it becomes supercritical at a relatively low temperature and pressure and has the property of dissolving organic solvents that are often used in substrate processing well. The critical point at which carbon dioxide becomes supercritical is an atmospheric pressure (critical pressure) of 7.38 MPa and a temperature (critical temperature) of 31.1°C.

[0027] The processing fluid is filled in the processing space SP, and when the processing space SP reaches an appropriate temperature and pressure, the processing space SP is filled with the processing fluid in a supercritical state. In this manner, the substrate S is processed by the supercritical fluid in the processing chamber 12. The supply unit 50 is provided with a fluid recovery part 55, and the fluid after processing is recovered by the fluid recovery part 55. The fluid supply part 57 and the fluid recovery part 55 are controlled by the control unit 90.

[0028] The processing space SP has a shape and volume capable of receiving the support tray 15 and the substrate S supported thereon. That is, the processing space SP has a roughly rectangular cross-sectional shape that is wider than the width of the support tray 15 in the horizontal direction and greater than the combined height of the support tray 15 and the substrate S in the vertical direction, and a depth capable of receiving the support tray 15. In this way, the processing space SP has a shape and volume sufficient to receive the support tray 15 and the substrate S. However, there is only a small gap between the support tray 15 and the substrate S and the inner wall surface of the processing space SP. Therefore, a relatively small amount of processing fluid is required to fill the processing space SP.

[0029] When the support tray 15 is accommodated in the processing space SP, the processing space SP is roughly divided into a space above and a space below the support tray 15. When the substrate S is placed on the support tray 15, the processing space SP is divided into a space above the upper surface of the substrate S and a space below the lower surface of the support tray 15.

[0030] The fluid supply unit 57 supplies the processing fluid to each of the space above the substrate S in the processing space SP and the space below the support tray 15, further on the (+Y) side than the (+Y) side end of the substrate S. Meanwhile, the fluid recovery unit 55 discharges the processing fluid from each of the space above the substrate S in the processing space SP and the space below the support tray 15, further on the (-Y) side than the (-Y) side end of the substrate S. As a result, a laminar flow of the processing fluid from the (+Y) side toward the (-Y) side is formed above the substrate S and below the support tray 15 in the processing space SP.

[0031] Detectors 173, 174 for detecting the pressure and temperature of the processing fluid discharged from the processing space SP are provided on the piping that serves as a discharge path for the processing fluid from the processing space SP to the fluid recovery unit 55. Specifically, a first detector 173 is provided on the piping that communicates with a space in the processing space SP above the support tray 15 and discharges the processing fluid from the space, and a second detector 174 is provided on the piping that communicates with a space below the support tray 15 and discharges the processing fluid from the space.

[0032] The detection units 173, 174 detect the pressure and temperature of the processing space SP, and in this sense, it is desirable to provide them inside the processing space SP. In particular, with regard to temperature, it would be ideal if the temperature of the chamber inner wall surface facing the processing space SP could be detected. However, it is necessary to avoid impeding the smooth flow of the processing fluid or becoming a source of contamination for the processing fluid. For this reason, as a simple alternative method, the detection units 173, 174 are provided in the processing fluid flow path that communicates with the processing space SP downstream of the substrate S in the flow direction of the processing fluid. That is, the detection results of the pressure and temperature of the processing fluid flowing through this flow path are considered to be the pressure and temperature of the processing space SP.

[0033] For this purpose, it is desirable that the piping constituting the flow path of the processing fluid from the processing space SP to the detection units 173 and 174 has a small pressure loss. Furthermore, as long as it does not affect the flow of the processing fluid, the detection unit may be disposed so as to directly face the processing space SP.

[0034] The control unit 90 determines the pressure and temperature in the processing space SP based on the outputs of the detection units 173, 174, and controls the fluid supply unit 57 and the fluid recovery unit 55 based on the results. This appropriately manages the supply of the processing fluid to the processing space SP and the discharge of the processing fluid from the processing space SP, and adjusts the pressure and temperature in the processing space SP in accordance with a predetermined processing recipe.

[0035] The transfer unit 30 is responsible for transferring the substrate S between an external transport device and the support tray 15. For this purpose, the transfer unit 30 includes a main body 31, a lifting member 33, a base member 35, and a plurality of lift pins 37. The lifting member 33 is a columnar member extending in the Z direction, and is supported by a support mechanism (not shown) so as to be movable in the Z direction relative to the main body 31. A base member 35 having a substantially horizontal upper surface is attached to the upper portion of the lifting member 33. A plurality of lift pins 37 are erected upward from the upper surface of the base member 35. Each of the lift pins 37 supports the substrate S in a horizontal position from below by abutting its upper end portion against the lower surface of the substrate S. In order to stably support the substrate S in a horizontal position, it is desirable to provide three or more lift pins 37 whose upper ends have the same height.

[0036] The lifting member 33 can be moved up and down by a lifting mechanism 51 provided in the supply unit 50. Specifically, the lifting mechanism 51 has a linear motion mechanism such as a linear motor, a linear motion guide, a ball screw mechanism, a solenoid, an air cylinder, etc., and such a linear motion mechanism moves the lifting member 33 in the Z direction. The lifting mechanism 51 operates in response to a control command from the control unit 90.

[0037] The base member 35 moves up and down by the lifting member 33 moving up and down, and the multiple lift pins 37 move up and down integrally therewith. This allows the transfer of the substrate S between the transfer unit 30 and the support tray 15. More specifically, as shown by the dotted line in FIG. 1, the substrate S is transferred in a state in which the support tray 15 is pulled out of the chamber. For this purpose, the support tray 15 is provided with through holes 152 for inserting the lift pins 37. When the base member 35 moves up, the upper ends of the lift pins 37 reach a position higher than the support surface 151 of the support tray 15 through the through holes 152. In this state, the substrate S transferred by an external transfer device is transferred to the lift pins 37. When the lift pins 37 move down, the substrate S is transferred from the lift pins 37 to the support tray 15. The substrate S can be removed by reversing the above procedure.

[0038] FIG. 2 is a flow chart showing an outline of the process executed by this substrate processing apparatus. This substrate processing apparatus 1 executes a supercritical drying process, that is, a process for drying a substrate S that has been cleaned with a cleaning liquid in a pre-process. Specifically, the 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 a substrate processing system. Thereafter, the substrate S is transported to the substrate processing apparatus 1 with a liquid film formed on its surface using an organic solvent such as isopropyl alcohol (IPA).

[0039] 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, watermarks may remain on the surface of the substrate S due to incomplete drying. 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.

[0040] For example, when the cleaning liquid is mainly composed of water, the substrate is transported in a state in which a liquid film is formed using a liquid having a lower surface tension and a lower corrosiveness to the substrate, such as an organic solvent such as IPA or acetone, etc. In other words, 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.

[0041] The substrate S transported by a transport device (not shown) is accommodated in the processing chamber 12 (step S101). Specifically, the substrate S is transported with the pattern-formed surface facing up and covered with a thin liquid film. As shown by the dotted line in FIG. 1, the lift pins 37 rise while the cover member 13 moves to the (-Y) side and the support tray 15 is pulled out. The transport device transfers the substrate S to the lift pins 37. The lift pins 37 are lowered, so that the substrate S is placed on the support tray 15. When the support tray 15 and the cover member 13 move together in the (+Y) direction, the support tray 15 supporting the substrate S is accommodated in the processing space SP in the processing chamber 12, and the opening 121 is closed by the cover member 13.

[0042] In this state, carbon dioxide as a processing fluid is introduced in a gas phase into the processing space SP (step S102). When the substrate S is loaded, outside air enters the processing space SP, but this can be replaced by introducing the gas phase processing fluid. Furthermore, the pressure inside the processing chamber 12 increases as the gas phase processing fluid is injected.

[0043] During the process of introducing the processing fluid, the processing fluid is continuously discharged from the processing space SP. That is, even while the processing fluid is being introduced by the fluid supply unit 57, the processing fluid is discharged from the processing space SP by the fluid recovery unit 55. This allows the processing fluid used for processing to be discharged without convection into the processing space SP, and prevents impurities such as residual liquid that have been taken in the processing fluid from adhering again to the substrate S.

[0044] If the supply rate of the processing fluid is greater than the discharge rate, the density of the processing fluid in the processing space SP increases, and the pressure inside the chamber increases. Conversely, if the supply rate of the processing fluid is less than the discharge rate, the density of the processing fluid in the processing space SP decreases, and the pressure inside the chamber is reduced. The supply of the processing fluid to the processing chamber 12 and the discharge of the processing fluid from the processing chamber 12 are performed based on a supply and discharge recipe created in advance. That is, the control unit 90 controls the fluid supply unit 57 and the fluid recovery unit 55 based on the supply and discharge recipe, thereby adjusting the supply and discharge timing and the flow rate of the processing fluid.

[0045] When the pressure of the processing fluid in the processing space SP increases and exceeds the critical pressure, the processing fluid becomes supercritical in the chamber. That is, the processing fluid transitions from the gas phase to the supercritical state due to a phase change in the processing space SP. The processing fluid in the supercritical state may be supplied from the outside. By introducing the supercritical fluid into the processing space SP, the organic solvent such as IPA covering the substrate S is replaced by the supercritical fluid. The organic solvent liberated from the surface of the substrate S is discharged from the processing chamber 12 together with the processing fluid in a state dissolved in the processing fluid, and is removed from the substrate S. That is, the processing fluid in the supercritical state has the function of replacing the organic solvent adhering to the substrate S as the replacement target liquid and discharging it outside the processing chamber 12. By continuing the state in which the processing space SP is filled with the processing fluid in the supercritical state for a predetermined time (step S103), the replacement target liquid adhering to the substrate S can be completely replaced and discharged outside the chamber.

[0046] When the replacement of the liquid to be replaced with the supercritical fluid in the processing chamber 12 is completed (step S104), the processing fluid in the processing space SP is discharged to dry the substrate S. Specifically, the amount of fluid discharged from the processing space SP is increased to reduce the pressure inside the processing chamber 12 filled with the processing fluid in a supercritical state (steps S105 and S106). In this embodiment, a two-stage depressurization process, i.e., a first depressurization step (step S105) and a second depressurization step (step S106), is performed, and the processing space SP is finally depressurized to atmospheric pressure. The difference between these two depressurization steps will be described in detail later.

[0047] In the depressurization process, the supply of the processing fluid may be stopped, or a small amount of the processing fluid may be continuously supplied. By depressurizing the processing space SP from a state filled with supercritical fluid, the processing fluid changes phase from the supercritical state to a gas phase. By discharging the vaporized processing fluid to the outside, the substrate S becomes a dry state. At this time, the depressurization speed is adjusted so that a solid phase and a liquid phase are not generated due to a sudden temperature drop. As a result, the processing fluid in the processing space SP is directly vaporized from the supercritical state and discharged to the outside. Therefore, the formation of a gas-liquid interface on the substrate S with the surface exposed after drying is avoided.

[0048] As described above, in the supercritical drying process of this embodiment, the processing space SP is filled with a processing fluid in a supercritical state, and then the processing fluid is changed into a gas phase and discharged, thereby efficiently replacing the liquid adhering to the substrate S and preventing it from remaining on the substrate S. Moreover, the substrate can be dried while avoiding problems caused by the formation of a gas-liquid interface, such as contamination of the substrate due to the adhesion of impurities and pattern collapse.

[0049] After processing, the substrate S is discharged to a subsequent process (step S107). That is, the support tray 15 is pulled out from the processing chamber 12 to the outside by moving the cover member 13 in the (-Y) direction, and the substrate S is delivered to an external transport device via the transfer unit 30. At this time, the substrate S is in a dry state. The content of the subsequent process is arbitrary. If there is no substrate to be processed next (NO in step S108), the process ends. If there is another substrate to be processed (YES in step S108), the process returns to step S101 to accept a new substrate S, and the above process is repeated.

[0050] When processing of the next substrate S is to be performed after processing of one substrate S is completed, the tact time can be shortened by doing the following: After the support tray 15 is pulled out and the processed substrate S is taken out, a new unprocessed substrate S is placed on it, and then the support tray 15 is housed in the processing chamber 12. In addition, by reducing the number of times the cover member 13 is opened and closed in this manner, it is possible to obtain the effect of suppressing temperature changes in the processing chamber 12 caused by the entry of outside air.

[0051] Next, the reason why the depressurization step is performed in two stages in this embodiment will be described. In the depressurization step after the supercritical processing, it is sufficient that the processing fluid in the supercritical state is phase-transferred to the gas phase without passing through the liquid phase and discharged outside the chamber. Therefore, if only one substrate is processed, it can be said that there is no need to particularly manage the temperature inside the chamber at the end of the processing. However, as will be described next, when multiple substrates are processed continuously, the temperature inside the chamber at the end of the processing of one substrate affects the processing result of the substrate to be processed next.

[0052] FIG. 3 is a diagram showing a schematic diagram of a temperature change in a chamber during supercritical processing. From an initial temperature Ti immediately after the substrate S is accommodated in the processing space SP of the processing chamber 12, a processing fluid is introduced into the processing space SP, and the pressure in the chamber is increased, and the temperature in the chamber gradually rises. Then, the temperature in the chamber is maintained at a temperature Tm exceeding the critical temperature of the processing fluid for a certain period of time, whereby the substrate S is subjected to supercritical processing. The density of the supercritical processing fluid varies greatly depending on the temperature, and the change in density leads to a change in the replacement efficiency. For this reason, it is desirable that the temperature during processing of one substrate S is constant. Also, in order to stabilize the processing quality of multiple substrates, it is desirable that the temperature during processing of each substrate is the same.

[0053] After the processing with the supercritical processing fluid, the processing space SP is depressurized and finally the temperature in the chamber decreases as the pressure in the processing space SP decreases to atmospheric pressure. At this time, as shown by the solid line in the figure, if the temperature at the end of the depressurization is the same as the initial temperature Ti, it is considered that the temperature change in the processing of other substrates performed subsequently will be approximately the same. On the other hand, if the temperature in the chamber during the depressurization is not properly managed, the processing may end at a temperature higher than the initial temperature Ta as shown by the dotted line, or at a temperature lower than the initial temperature Ta as shown by the dashed line.

[0054] In this case, the initial temperature in the process for the next substrate will be different from that in the process for the previous substrate, and the temperature in the subsequent processes will also change differently. As a result, the processing quality may differ for each substrate. In particular, if the process is completed at a temperature higher than the initial temperature, the temperature of the supercritical processing fluid in the process for the next substrate will be too high, the density of the processing fluid will be low, and the replacement efficiency will decrease, that is, the processing quality will deteriorate. In addition, each time the process is repeated, thermal energy will accumulate in the processing chamber 12, and the temperature of the processing space SP will gradually rise.

[0055] In order to solve this problem, in this embodiment, the progress of decompression is controlled so that the temperature inside the chamber will be at an appropriate value when the decompression is completed, specifically, when the pressure inside the chamber drops to atmospheric pressure. Specific aspects of the decompression process of this embodiment will be described in more detail below.

[0056] FIG. 4 is a phase diagram showing phase changes in the supercritical processing of this embodiment. When filling the chamber with supercritical fluid to perform supercritical processing, a processing fluid that has been previously made supercritical may be introduced into the processing chamber. However, as described above, since the density of a supercritical fluid changes greatly due to changes in temperature and pressure, it is more practical to introduce the supercritical fluid in a liquid or gas phase, which is easier to handle. That is, the processing fluid is introduced in a gas or liquid phase and is phase-transitioned to a supercritical state in the chamber. In this case, various modes of pressure and temperature changes of the processing fluid are possible, as shown by arrows a to c in FIG. 3.

[0057] In the figure, the white circle represents the critical point of carbon dioxide, which is the processing fluid in this embodiment. The symbols Pc and Tc represent the critical pressure and critical temperature, respectively. Point P1 represents the target pressure and temperature in supercritical processing. From the viewpoint of processing efficiency, it is preferable that point P1 is close to the critical point (white circle).

[0058] The arrow a corresponds to the case where a liquid-phase processing fluid is introduced. More specifically, the arrow a indicates the case where a liquid processing fluid at a pressure lower than the critical pressure Pc and a temperature lower than the critical temperature Tc is pressurized and heated in a chamber to transition to a supercritical state. At this time, the pressure and temperature of the processing fluid are controlled so that a phase transition to a gas phase does not occur. Note that the pressure of the liquid processing fluid introduced may be higher than the critical pressure Pc.

[0059] Additionally, arrows b and c correspond to cases where a gas-phase processing fluid is introduced. More specifically, arrows b and c indicate cases where a gas-phase processing fluid with a pressure lower than the critical pressure Pc and a temperature lower than the critical temperature Tc is pressurized and heated in a chamber to transition to a supercritical state. Among these, arrow b indicates a case where the supercritical state transition occurs via the gas phase to the liquid phase, and arrow c indicates a case where the supercritical state transition occurs from the gas phase to the supercritical state without passing through the liquid phase.

[0060] Thus, there are various methods for bringing the introduced processing fluid into a supercritical state (point P1) where the pressure is higher than the critical pressure Pc and the temperature is higher than the critical temperature Tc. On the other hand, it is desirable to take the following three points into consideration in the decompression process after the supercritical processing is completed. (1) The treatment fluid undergoes a phase transition from a supercritical state to a gas phase without passing through a liquid phase; (2) The temperature inside the chamber at the end of decompression is at an appropriate value. (3) The pressure should be reduced to atmospheric pressure in as short a time as possible while still satisfying (1) and (2) above.

[0061] The above requirement (1) is based on the objective of preventing pattern collapse even on substrates on which fine patterns are formed, the requirement (2) is based on the objective of stabilizing the processing quality for multiple substrates, and the requirement (3) is based on the objective of improving processing throughput.

[0062] Therefore, in this embodiment, the depressurization process is divided into two stages corresponding to the above objectives (1) and (2), respectively, and each stage is individually optimized to achieve the above objective (3). That is, in the first stage of the depressurization process (first depressurization process shown in step S105 of FIG. 2), in order to achieve the above objective (1), the progress of depressurization is controlled with the goal that the temperature inside the chamber does not fall below the critical temperature Tc. Specifically, as shown by the dashed arrow d in FIG. 4, the depressurization is controlled so that the state of the processing fluid transitions from point P1 where "both the pressure and the temperature exceed the critical points (i.e., the processing fluid is in a supercritical state)" to point P2 where "the temperature is higher than the critical temperature Tc and the pressure is lower than the critical pressure Pc". As a result, the processing fluid undergoes a phase transition from the supercritical state to the gas phase without passing through a liquid phase.

[0063] On the other hand, in the second stage of the depressurization process (second depressurization process shown in step S106 in FIG. 2), in order to achieve the above-mentioned objective (2), the depressurization is controlled using the temperature inside the chamber at the end of the depressurization as an index. That is, in the state transition from point P2 to point P3 shown by the dashed arrow e in FIG. 4, the progress of the depressurization is adjusted so that the temperature at point P3 becomes the preset target temperature Tt. At this point, since the pressure inside the chamber is below the critical pressure Pc, there is no need to take into consideration the transition of the processing fluid to the liquid phase unless an operation that causes an extremely drastic drop in temperature is performed.

[0064] 4, the target temperature Tt is higher than the critical temperature Tc, but it may be lower. From the viewpoint of bringing the processing fluid into a supercritical state in a short time during the pressure increase process, it is desirable that the target temperature Tt is higher than the critical temperature Tc. On the other hand, since a temperature rise inevitably occurs during the pressure increase process and, from the viewpoint of replacement efficiency, it is preferable that the temperature of the processing fluid during the supercritical processing is low, the temperature inside the chamber at the start of processing may be lower than the critical temperature Tc.

[0065] Furthermore, from the viewpoint of preventing the processing fluid introduced into the processing space SP from undergoing a phase transition due to a sudden temperature change, it is preferable that the difference between the temperature of the processing fluid to be introduced and the temperature inside the chamber is small. From this viewpoint, the target temperature Tt and the temperature of the processing fluid may be determined. In this manner, various ideas are possible regarding the setting of the target temperature Tt. The main focus of this embodiment is to perform pressure reduction control using the target temperature Tt thus set as an index.

[0066] In order to stably process multiple substrates, it is preferable that the initial temperature Ti at the start of processing and the target temperature Tt at the end of processing are the same. This allows the temperature changes in multiple processing steps to be uniform, and the processing quality to be stable. Furthermore, when processing of the previous substrate is completed, the temperature inside the chamber is suitable for receiving the next substrate, so processing of the next substrate can be started immediately. This improves throughput.

[0067] In order to lower the temperature inside the chamber, which has become high due to the supercritical processing, the temperature drop due to the adiabatic expansion of the processing fluid can be used. That is, the processing fluid that fills the processing space SP as a high-pressure gas is discharged at a relatively high discharge speed to rapidly expand the processing fluid and lower the temperature of the processing fluid. This makes it possible to cool the inner wall surface of the chamber facing the processing space SP. By appropriately setting the discharge speed, it is possible to control the rate at which the temperature drops, and ultimately lower the temperature inside the chamber to the target temperature Tt.

[0068] In the decompression treatment, which focuses on transitioning from a supercritical state to a gas phase without passing through a liquid phase, the discharge speed of the treatment fluid needs to be relatively slow in order to prevent transition to a liquid phase due to a drop in temperature. Therefore, if the pressure reduction is continued while maintaining the discharge speed at this time, it will take a long time to reduce the pressure to atmospheric pressure.

[0069] On the other hand, the processing fluid after transitioning to the gas phase can be discharged at a higher discharge rate, thereby shortening the time required for depressurization. In addition, by actively utilizing the temperature drop caused by the adiabatic expansion of the processing fluid at this time, it is possible to optimize the temperature inside the chamber at the end of depressurization. To make this possible, the above-mentioned two-stage depressurization is performed in this embodiment.

[0070] Fig. 5 is a timing chart showing state changes of each part during supercritical processing. More specifically, Fig. 5 shows the relationship between the timing of supply and discharge of processing fluid based on a predetermined supply and discharge recipe and the associated state changes in processing chamber 12. First, the supply and discharge recipe that specifies the timing and amount of supply and discharge of processing fluid will be described with reference to Fig. 5(a).

[0071] In the initial state, the cover member 13 is open to accommodate the substrate S in the processing chamber 12, and the processing space SP is open to the atmosphere. That is, the pressure inside the chamber is approximately atmospheric pressure Pa, which is sufficiently lower than the critical pressure Pc. Meanwhile, since the critical temperature Tc of carbon dioxide as the processing fluid is close to room temperature, the initial temperature Ti inside the chamber is close to the critical temperature Tc. In the figure, the initial temperature Ti is slightly higher than the critical temperature Tc, but there may be cases where it is lower than the critical temperature Tc.

[0072] After the substrate S is accommodated, at time T1, the gas phase processing fluid begins to be introduced into the processing space SP at a predetermined flow rate. At this time, a constant amount of the processing fluid is also discharged. By increasing the supply flow rate relative to the discharge flow rate, the pressure inside the chamber gradually increases. At time T2, when the pressure inside the chamber reaches the critical pressure Pc, if the temperature inside the chamber is above the critical temperature Tc, the processing fluid undergoes a phase transition to a supercritical state.

[0073] At time T3, the supply amount of the processing fluid is adjusted to an amount that maintains the pressure in the chamber approximately constant. This maintains the pressure and temperature in the chamber filled with the processing fluid in a supercritical state approximately constant. Then, depressurization begins at time T4. That is, the supply amount of the processing fluid is greatly reduced while the discharge amount is increased, resulting in over-discharge and a drop in the pressure in the chamber. As the processing fluid expands, the temperature in the chamber also drops, but the depressurization is performed at a relatively slow depressurization speed so that the temperature does not fall below the critical temperature Tc. The depressurization speed can be adjusted by controlling the discharge speed of the processing fluid according to the change in pressure in the chamber. The depressurization process at this time is the "first depressurization step" and is indicated as "depressurization (1)" in FIG. 5.

[0074] At time T5 when the pressure in the chamber drops below the critical pressure Pc, the processing fluid undergoes a phase transition to a gas phase. Thereafter, at time T6, the discharge rate of the processing fluid is increased, and the depressurization process transitions to a "second depressurization step". In FIG. 5, the depressurization step of stage 2 is indicated as "depressurization (2)". For example, the transition from the first depressurization step to the second depressurization step can be realized by controlling the discharge rate of the processing fluid to increase when the detected value of the pressure in the chamber reaches a specified value lower than the critical pressure Pc. Alternatively, the discharge rate of the processing fluid may be increased when the detected value of the pressure in the chamber is lower than the critical pressure Pc and the detected value of the temperature in the chamber falls to a specified value higher than the critical temperature Tc.

[0075] After time T7 when the pressure inside the chamber drops to approximately atmospheric pressure Pa, the processing space SP can be opened to the atmosphere and the substrate S can be removed. The rapid pressure reduction reduces the temperature inside the chamber, and the pressure reduction rate (the rate at which the processing fluid is discharged) is adjusted so that the temperature inside the chamber reaches the target temperature Tt at time T7.

[0076] In this example, the target temperature Tt and the initial temperature Ti are set to be equal, and therefore the temperature inside the chamber returns to the initial temperature Ti at the end of the depressurization process. Therefore, even if a new unprocessed substrate is immediately received and processed after the processed substrate is unloaded, the temperature conditions in each process are the same, and the same processing results can be achieved. In other words, in this embodiment, it is possible to process multiple substrates with stable processing quality.

[0077] 5(a), the temperature in the chamber gradually decreases as the pressure is reduced in the second depressurization step, and at time T7 when the pressure is reduced to atmospheric pressure, the temperature in the chamber also drops to the target temperature Tt. However, what is required is that the temperature in the chamber reaches the target temperature Tt at the timing when the processing space SP can be opened to the atmosphere, that is, when the processed substrate S can be removed from the processing chamber 12. In this sense, the time when the pressure in the chamber drops to atmospheric pressure and the time when the temperature in the chamber reaches the target temperature Tt do not need to be the same.

[0078] 5(b), the temperature in the chamber may be decreased to the target temperature Tt before the time T7 when the pressure in the chamber is decreased to atmospheric pressure. In this case, after the time T8 when the temperature in the chamber reaches the target temperature Tt, it is preferable to reduce the discharge rate of the processing fluid in order to suppress a further decrease in temperature due to adiabatic expansion of the processing fluid.

[0079] 5(c), even if the pressure in the chamber is higher than atmospheric pressure at time T8 when the temperature in the chamber reaches the target temperature Tt, the pressure can be reduced to atmospheric pressure in one go if the difference is not too large. For example, the processing space SP may be opened to the atmosphere by opening the cover member 13, and the pressure in the chamber becomes atmospheric pressure. In this way, if the pressure in the chamber is sufficiently reduced to a pressure close to atmospheric pressure in advance, it is considered that a large temperature change will not occur even if the pressure changes due to subsequent release to the atmosphere. Therefore, if the pressure in the chamber has sufficiently reduced at the time when the temperature in the chamber reaches the target temperature Tt, it is also possible to open the processing space SP to the atmosphere without waiting for the pressure to decrease to atmospheric pressure.

[0080] In this case, the pressure and temperature in the chamber are monitored, and if the pressure in the chamber is below a specified value at time T8 when the temperature in the chamber reaches the target temperature Tt, the controlled decompression is stopped and the processing space SP is immediately opened to the atmosphere. If the pressure in the chamber is higher than the specified value at time T8, the decompression can be stopped when it drops to the specified value.

[0081] As described above, in this embodiment, the depressurization process after the execution of the supercritical processing is performed in two stages: the first depressurization process, the main purpose of which is to transition the processing fluid in a supercritical state to a gas phase without passing through a liquid phase, and the second depressurization process, which utilizes the cooling effect caused by the adiabatic expansion of the processing fluid after transition to the gas phase to depressurize the inside of the chamber to atmospheric pressure while maintaining an appropriate temperature inside the chamber after processing. The control factors (pressure, temperature) and the discharge speed of the processing fluid that are focused on for the depressurization control are different between these two processing stages.

[0082] In this manner, the supercritical processing fluid can be directly transferred to a gas phase and then discharged to obtain good processing results, and the temperature inside the chamber after processing can be kept appropriate to obtain stable processing results for multiple substrates. Therefore, in this embodiment, multiple substrates can be processed with good and stable processing quality.

[0083] As described above, in the substrate processing apparatus 1 of the above embodiment, the processing chamber 12 functions as the "chamber" of the present invention, and the opening 121 corresponds to the "opening" of the present invention. The processing space SP corresponds to the "internal space" of the present invention. The support tray 15 and the cover member 13 function as the "support tray" and the "cover" of the present invention, respectively. The fluid supply unit 57, the fluid recovery unit 55, and the control unit 90 function as the "fluid supply unit," the "fluid discharge unit," and the "control unit" of the present invention, respectively. The detection units 173 and 174 function as the "detection unit" of the present invention.

[0084] In the substrate processing method of the above embodiment (FIG. 2), steps S101 to S104 correspond to the “supercritical processing step” of the present invention, and steps S105 and S106 correspond to the “first depressurization step” and the “second depressurization step” of the present invention, respectively.

[0085] The present invention is not limited to the above-mentioned embodiment, and various modifications can be made without departing from the spirit of the present invention. For example, the pressure reduction control in the first and second pressure reduction steps is not limited to the above-mentioned embodiment in which the discharge speed of the processing fluid is adjusted based on the detection results of the detection units 173 and 174, and can be more simply as follows.

[0086] In the supercritical processing of the above embodiment, the temperature in the chamber after processing is managed, so that the temperature change profile can be made almost the same when processing multiple substrates sequentially. In other words, the temperature change in the chamber from the introduction to the discharge of the processing fluid is reproducible. Therefore, if the pressure and temperature change in the chamber are measured in advance by a preliminary experiment, it is possible to experimentally determine the discharge speed and duration of the processing fluid in each of the first and second depressurization steps from the results. If the discharge control is performed using these results, it is possible to realize the same depressurization control as in the above embodiment, even if the detection results of the pressure and temperature during processing are not used.

[0087] Moreover, in the above embodiment, there is no mention of controlling the initial temperature when processing the first substrate when processing a plurality of substrates in sequence. However, when considering the stability of the processing, it is desirable that the initial temperature at this time is also maintained at an appropriate temperature. For this purpose, and also to suppress temperature changes caused by disturbances, the substrate processing apparatus 1 may further be provided with a configuration for stabilizing temperature. For example, a heater may be provided on the surface or inside the processing chamber 12. Also, the support tray 15 may have a built-in heater.

[0088] In addition, the various chemical substances used in the treatment of the above-mentioned embodiments are only some examples, and various substances can be used instead as long as they are in accordance with the technical concept of the present invention described above.

[0089] As described above by way of example of specific embodiments, in the substrate processing method according to the present invention, the temperature of the internal space can be lowered by adiabatic expansion of the processing fluid in the internal space in the second depressurization step. Although the temperature drop due to adiabatic expansion is a phenomenon that inevitably occurs in the depressurization step, by performing depressurization control taking this into account, the temperature in the chamber can be set to a target temperature and the depressurization can be terminated.

[0090] Also, for example, the target temperature may be equal to or higher than the critical temperature. When processing of a next substrate is performed after processing of one substrate is completed, if the temperature in the chamber is maintained at or higher than the critical temperature, the processing fluid to be introduced can be brought to a supercritical state in a short time, and processing can be performed efficiently.

[0091] Also, for example, in the first depressurization step, the second depressurization step can be started when the pressure in the internal space drops to a specified value lower than the critical pressure. In the first depressurization step, the depressurization is performed so that the temperature in the chamber does not fall below the critical temperature. Therefore, when the pressure in the internal space becomes lower than the critical pressure, it can be said that the processing fluid in the chamber transitions from the supercritical state to the gas phase without passing through the liquid phase. By performing the second depressurization step at this timing, the pressure and temperature of the processing fluid can be further reduced while avoiding the transition to the liquid phase.

[0092] Also, for example, in the second depressurization step, the exhaust rate may be reduced after the temperature of the internal space has dropped to the target temperature. If the exhaust rate is continued more rapidly in this state, the temperature inside the chamber will drop further. By reducing the exhaust rate, the pressure in the internal space can be reduced while preventing a further drop in temperature.

[0093] On the other hand, for example, in the second depressurization step, the internal space may be opened to the atmosphere after the temperature of the internal space has been reduced to the target temperature. Even if the internal space has not been depressurized to atmospheric pressure at this point, if the difference with the atmospheric pressure is small, further temperature reduction due to opening to the atmosphere is minor. Therefore, by opening to the atmosphere at the point when the temperature of the internal space has been reduced to the target temperature, it is possible to shorten the processing time.

[0094] This substrate processing method may also be configured to process multiple substrates in sequence by unloading the substrate after the internal space is opened to the atmosphere and loading an unprocessed substrate into the chamber to perform the supercritical processing step. In the present invention, the temperature in the chamber at the time when processing of one substrate is completed is managed, so that the initial temperature when processing the next substrate can be set to an appropriate value. Therefore, when processing multiple substrates in sequence in this way, the processing results can be stable.

[0095] Furthermore, the substrate processing apparatus according to the present invention may include, for example, a detection unit that detects the pressure and temperature of the internal space, and the control unit may control the fluid supply unit and the fluid discharge unit based on the detection results of the detection unit. With this configuration, the progress of decompression is controlled using at least one of the detection results of the pressure and temperature of the internal space, so that the substrate can be processed well, and the temperature inside the chamber at the end of processing can be appropriately controlled, making it possible to stably process multiple substrates.

[0096] Also, for example, an opening communicating with the internal space may be provided on the side of the chamber, a support tray that supports the substrate in a horizontal position and can enter the internal space through the opening, and a lid that closes the opening when the support tray is housed in the internal space. With this configuration, the substrate can be loaded and unloaded by moving the support tray into and out of the internal space. Furthermore, by closing the opening with the lid, the internal space can be made airtight to perform high-pressure processing. Furthermore, by moving the lid away from the opening, the internal space can be opened to the atmosphere. [Industrial Applicability]

[0097] The present invention can be applied to any process for processing a substrate using a processing fluid introduced into a chamber, for example, single-wafer substrate processing in which substrates such as semiconductor substrates are processed one by one in sequence using a supercritical fluid. [Explanation of symbols]

[0098] 1. Substrate Processing Equipment 12 Processing chamber (chamber) 13 Lid member (lid part) 15 Support Tray 55 Fluid recovery section (fluid discharge section) 57 Fluid supply section 90 Control unit (control section) 121 Aperture 173,174 Detector S-substrate S102~S104 Supercritical processing process S105 First decompression step S106 Second decompression step SP Processing space (internal space)

Claims

1. 1. A substrate processing method for processing a substrate with a processing fluid in a supercritical state in a chamber, comprising: a supercritical processing step of introducing the processing fluid into an internal space of the chamber containing the substrate, and processing the substrate by maintaining a pressure in the internal space higher than a critical pressure of the processing fluid and a temperature in the internal space higher than a critical temperature of the processing fluid; a first depressurization step of discharging the processing fluid from the chamber and depressurizing the internal space to a pressure lower than the critical pressure and higher than atmospheric pressure while maintaining a temperature of the internal space equal to or higher than the critical temperature of the processing fluid; a second depressurization step of depressurizing the internal space by discharging the processing fluid at a higher discharge rate than in the first depressurization step; Equipped with a second pressure reduction step of controlling the exhaust rate so that the temperature of the internal space reaches a predetermined target temperature when the pressure of the internal space is reduced to atmospheric pressure by adiabatic expansion of the processing fluid in the internal space to reduce the temperature of the internal space.

2. The method of claim 1 , wherein the target temperature is equal to or greater than the critical temperature.

3. 3. The substrate processing method according to claim 1, wherein the second depressurization step is started when the pressure in the internal space drops to a specified value lower than the critical pressure in the first depressurization step.

4. 4. The substrate processing method according to claim 1, wherein the discharge speed is reduced after the temperature of the internal space is reduced to the target temperature in the second depressurization step.

5. 4. The substrate processing method according to claim 1, wherein the internal space is opened to the atmosphere after the temperature of the internal space is lowered to the target temperature in the second depressurization step.

6. 6. The substrate processing method according to claim 5, further comprising the steps of: after the internal space is opened to the atmosphere, unloading the substrate; loading an unprocessed substrate into the chamber; and performing the supercritical processing step, thereby processing a plurality of the substrates in sequence.

7. 1. A substrate processing apparatus for processing a substrate with a processing fluid in a supercritical state, a chamber for accommodating the substrate in an internal space; a fluid supply unit that supplies the processing fluid to an internal space of the chamber; a fluid discharge portion that discharges the processing fluid from the internal space; a control unit for controlling the fluid supply unit and the fluid discharge unit; Equipped with The control unit is The fluid supply unit supplies the treatment fluid to the internal space, and the pressure in the internal space is maintained higher than the critical pressure of the treatment fluid and the temperature in the internal space is maintained higher than the critical temperature of the treatment fluid. Discharging the processing fluid from the chamber through the fluid discharge section, while maintaining a temperature of the internal space at or above a critical temperature of the processing fluid, depressurizing the internal space to a pressure lower than the critical pressure and higher than atmospheric pressure; and increasing a discharge rate of the treatment fluid by the fluid discharge unit to adiabatically expand the treatment fluid in the internal space, thereby lowering the temperature of the internal space and reducing the pressure of the internal space to atmospheric pressure; The discharge rate is controlled so that the temperature of the internal space when the pressure of the internal space drops to atmospheric pressure is a predetermined target temperature. Substrate processing equipment.

8. A detection unit for detecting a pressure and a temperature of the internal space is provided, The substrate processing apparatus according to claim 7 , wherein the control unit controls the fluid supply unit and the fluid discharge unit based on a detection result of the detection unit.

9. An opening communicating with the internal space is provided on a side surface of the chamber, a support tray capable of supporting the substrate in a horizontal position and entering the internal space through the opening; a lid portion that closes the opening when the support tray is accommodated in the internal space; The substrate processing apparatus according to claim 7 or 8, comprising:

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