Substrate processing method

Abstract

The present invention is a substrate processing method for processing a substrate with a processing fluid in a supercritical state in a processing chamber, the substrate processing method including the following first and second steps. In the first step, a processing fluid is introduced into an internal space of a processing chamber in which a substrate is accommodated, and the internal space is pressurized to a first pressure as a gas pressurized to the first pressure lower than a critical pressure. In the second step, a processing fluid having a second pressure higher than the critical pressure is introduced into the internal space that has been pressurized to the first pressure, and the internal space is filled with the processing fluid in a supercritical state.

Description

TECHNICAL FIELD

[0001] The present application relates to a technology of housing a substrate in a processing chamber to be processed with a processing fluid in a supercritical state. BACKGROUND

[0002] In a processing procedure of various substrates such as semiconductor substrates, glass substrates for display devices, and the like, a procedure of processing a front surface of a substrate with various processing fluids is included. A wet processing using a liquid such as a chemical solution or a cleaning solution as a processing fluid has been widely performed. In recent years, a processing using a processing fluid in a supercritical state has been put into practical use in order to dry a substrate after the wet processing. In particular, in a drying processing of a substrate having a patterned surface in which a fine pattern is formed, a processing with a supercritical processing fluid is advantageous. This is because a processing fluid in a supercritical state has a characteristic of entering a deep portion of a gap of a pattern due to a low surface tension compared to a liquid. By using the processing fluid, a drying processing can be performed with high efficiency. In addition, a risk of pattern collapse due to surface tension at the time of drying can be reduced.

[0003] For example, in a substrate processing apparatus described in Japanese Patent Application Publication No. 2022-132400 (Patent Literature 1), a processing fluid is stored in a tank connected to a circulation line, and the processing fluid is maintained in a liquid state by being circulated in the circulation line in which a condenser is interposed. Further, a connection line branched from the circulation line is connected to a processing chamber, and a processing fluid in a supercritical state is supplied to the processing chamber by heating from a heater provided in the flow path. SUMMARY

[0004] [PROBLEMS TO BE SOLVED BY THE INVENTION]

[0005] In the substrate processing apparatus of the related art as described above, in order to further reduce the risk of pattern collapse, the following problem remains to be solved. That is, according to the present inventor's insight, as described above, in a processing mode in which a processing fluid in a supercritical state is supplied to a processing chamber in which a substrate is housed, a phenomenon that can cause pattern collapse sometimes occurs immediately after the processing fluid is supplied. That is, by the rapid inflow of a processing fluid at a high pressure into a processing chamber at a low pressure of atmospheric pressure or close to atmospheric pressure, a temperature reduction of the processing fluid due to adiabatic expansion occurs. Thereby, the processing fluid sometimes partially phase changes from a supercritical state to a liquid or a solid. In this case, if the liquefied or solidified processing fluid adheres to the substrate, particles can remain on the substrate or pattern collapse can occur.

[0006] In the related art, this problem has not been considered. That is, from the viewpoint of processing a substrate without causing particle adhesion or pattern collapse, it can be said that the related art leaves room for improvement.

[0007] [Technical means for solving the problem]

[0008] The present application has been achieved in view of the above-described problems, and reduces processing failures such as particle adhesion or pattern collapse that can occur due to a temperature decrease when supercritical processing fluid is introduced into a processing chamber, in a technique of processing a substrate with supercritical processing fluid.

[0009] One aspect of the present application is a substrate processing method of processing a substrate with processing fluid in a supercritical state in a processing chamber, including: a first step of introducing the processing fluid into an inner space of the processing chamber that houses the substrate, as a gas pressurized to a first pressure that is lower than a critical pressure, to pressurize the inner space to the first pressure; and a second step of introducing the processing fluid pressurized to a second pressure that is higher than the critical pressure into the inner space pressurized to the first pressure, to fill the inner space with the processing fluid in a supercritical state.

[0010] In the application thus configured, the processing chamber is sequentially supplied with processing fluid at the first pressure that is relatively low, and processing fluid at the second pressure that is higher than the first pressure. The processing fluid at the first pressure is supplied to the processing chamber as a gas at a pressure lower than the critical pressure. On the other hand, the second pressure exceeds the critical pressure, and by setting the temperature thereof, the processing fluid can be supplied to the processing chamber in a supercritical state.

[0011] If, as in the conventional technique, processing fluid at a high pressure exceeding the critical pressure is directly introduced into a processing chamber whose internal gas pressure is substantially atmospheric pressure, there is a concern that processing failures due to partial liquefaction or solidification of the processing fluid will occur. In contrast, in the present application, for example, the inner space of the processing chamber is first filled with processing fluid as a gas. Thereby, the inner space is pressurized in advance to an intermediate first pressure, and from this state, processing fluid in a supercritical state is introduced. Therefore, the temperature decrease due to adiabatic expansion is more limited, and the problems in the conventional technique can be eliminated.

[0012] [Effects of the invention]

[0013] As described above, according to the present application, the pressure of the inner space of the processing chamber can be increased in advance to an intermediate first pressure before processing fluid in a supercritical state is introduced at the second pressure. By thus introducing the processing fluid in two stages, the sharp temperature decrease of the processing fluid due to adiabatic expansion can be suppressed. As a result, processing failures such as particle adhesion or pattern collapse due to partial liquefaction or solidification of the processing fluid can be prevented.

[0014] The application will be more fully understood from the following detailed description, taken in Figure One The accompanying drawings are included to provide a further understanding of the application, and are incorporated in and constitute a part of this specification, but are not intended to limit the scope of the application. Attached Figure Description

[0015] Figure 1 This is a diagram illustrating a schematic configuration of a substrate processing system equipped with an embodiment of the substrate processing apparatus of the present invention.

[0016] Figure 2 This is a side view showing the overall structure of the wet treatment unit.

[0017] Figure 3 This diagram illustrates the operation of a wet scrubbing unit.

[0018] Figure 4 This is a side view showing the configuration of a supercritical processing unit.

[0019] Figure 5 It is a diagram showing the details of the supply and discharge paths of the processed fluid.

[0020] Figure 6 This is a flowchart representing the processing performed by the supercritical processing device.

[0021] Figure 7 It is a graph showing the pressure changes inside the processing chamber and storage tank.

[0022] Figure 8 This is a diagram showing the open and closed state of the valve during standby operation.

[0023] Figure 9 This is a diagram showing the opening and closing state of the valve when gas is introduced.

[0024] Figure 10 This is a diagram showing the opening and closing states of the valves when supercritical fluid is introduced.

[0025] Figure 11 This is a diagram showing the open and closed states of the valves when handling fluid replenishment.

[0026] Figure 12 This is a state diagram of the fluid being processed, which is carbon dioxide. Detailed Implementation

[0027] Figure 1 This diagram illustrates a schematic configuration of a substrate processing system equipped with an embodiment of the substrate processing apparatus of the present invention. The substrate processing system 1 is, for example, a processing system used to supply a processing solution to the upper surface of various substrates such as semiconductor wafers, wet-process the substrates, and then dry them. The substrate processing system 1 has a system configuration suitable for implementing the substrate processing method of the present invention. The substrate processing system 1 comprises a wet processing apparatus 2, a substrate conveying apparatus 3, a supercritical processing apparatus 4, and a control device 9 as its main components.

[0028] The wet processing apparatus 2 receives the substrate to be processed and performs a prescribed wet processing. The processing content is not particularly limited. Wet processing includes developing or washing processes, but after developing, the substrate is filled with a liquid, such as an organic solvent (IPA, Iso-Propyl Alcohol), on the patterned surface. The substrate transport apparatus 3, while maintaining the liquid filling state, moves the substrate from the wet processing apparatus 2 and transports it into the supercritical processing apparatus 4. The supercritical processing apparatus 4 corresponds to the substrate processing apparatus of this invention, and performs a drying process (supercritical drying process) on the transported substrate using a supercritical processing fluid. These apparatuses are installed in a cleanroom. Therefore, the substrate transport apparatus 3 transports the substrate under atmospheric atmosphere and atmospheric pressure.

[0029] The control device 9 controls the actions of each of the devices to achieve the prescribed processing. For this purpose, the control device 9 includes a CPU (Central Processing Unit) 91, a memory 92, a storage device 93, and an interface 94. The CPU 91 executes various control programs. The memory 92 temporarily stores processed data. The storage device 93 stores the control programs executed by the CPU 91. The interface 94 exchanges information with the user or external devices. The actions of the devices described below are achieved by the CPU 91 executing the control programs pre-written into the storage device 93, causing each part of the device to perform the prescribed actions.

[0030] The CPU 91 executes a prescribed control program, and the software of the control device 9 implements functional blocks such as the wet processing control unit 95 for controlling the operation of the wet processing device 2, the transport control unit 96 for controlling the operation of the substrate transport device 3, and the supercritical processing control unit 97 for controlling the operation of the supercritical processing device 4. Furthermore, at least a portion of each of these functional blocks may also be constructed using dedicated software.

[0031] As the "substrate" in this embodiment, various substrates can be used, such as semiconductor wafers, photomask glass substrates, liquid crystal display glass substrates, plasma display glass substrates, FED (Field Emission Display) substrates, optical disc substrates, magnetic disk substrates, and magneto-optical disk substrates. Hereinafter, a substrate processing apparatus for processing disk-shaped semiconductor wafers will be used as an example, with reference to the accompanying drawings. However, the processing of the various substrates illustrated above can also be applied in the same way. Furthermore, various shapes of substrates can be used.

[0032] Furthermore, in the following explanation, a substrate with a pattern formed on only one main surface is used as an example. Here, the main surface with the pattern formed is referred to as the "front side," and the main surface opposite it without a pattern is referred to as the "back side." Additionally, the main surface of the substrate facing downwards is referred to as the "lower surface," and the main surface of the substrate facing upwards is referred to as the "upper surface." Furthermore, the upper surface will be described as the front side in the following explanation.

[0033] Figure 2 and Figure 3 This is a diagram illustrating an example of the configuration of a wet scrubbing apparatus. More specifically, Figure 2 This is a side view showing the overall structure of the wet scrubbing unit. Figure 3 This diagram illustrates the operation of the wet processing apparatus. The wet processing apparatus 2 is a device for processing the substrate S by supplying a processing solution to the upper surface of the substrate S. The operation of the wet processing apparatus 2 is controlled by the wet processing control unit 95 of the control device 9.

[0034] The wet processing apparatus 2 supplies processing liquid to the front side (pattern forming surface) Sa of the substrate S to perform wet processing such as front side treatment or cleaning of the substrate S. For this purpose, the wet processing apparatus 2 includes a substrate holding part 21, a splash guard 22, and processing liquid supply parts 23 and 24 inside the processing chamber 200. These operations are controlled by a wet processing control part 95 provided in the control device 9. The substrate holding part 21 has a circular plate-shaped rotating chuck 211 with a diameter approximately equal to that of the substrate S, and a plurality of chuck pins 212 are provided on the periphery of the rotating chuck 211. By abutting against the periphery of the substrate S with the chuck pins 212, the substrate S is supported, and the rotating chuck 211 can hold the substrate S in a horizontal position with its upper surface separated from it.

[0035] The upper surface of the rotating chuck 211 is horizontal, supported by a rotating shaft 213 extending downward from the center of its lower surface. The rotating shaft 213 is rotatably supported by a rotating mechanism 214 mounted at the bottom of the processing chamber 200. The rotating mechanism 214 houses a rotating motor (not shown). The rotating motor rotates according to control commands from the control device 9, causing the rotating chuck 211, directly connected to the rotating shaft 213, to rotate about the rotation axis AX indicated by the dashed line. Figure 2 In the middle, the vertical direction is the up-down direction. Therefore, the substrate S maintains a horizontal orientation and rotates around the rotation axis AX.

[0036] A splash guard 22 is provided to surround the substrate holding portion 21 from the side. The splash guard 22 has a generally cylindrical cup 221 that covers the periphery of the rotating chuck 211, and a liquid receiving portion 222 located below the outer periphery of the cup 221. The cup 221 rises and falls according to control commands from the control device 9. The cup 221... Figure 2 The position shown below is the same asFigure 3 The cup 221 moves up and down between the upper and lower positions shown. In the lower position, the upper end of the cup 221 is lowered below the periphery of the substrate S held in the rotating chuck 211. In the upper position, the upper end of the cup 221 is above the periphery of the substrate S.

[0037] When cup 221 is in the lower position, as Figure 2 As shown, the substrate S held in the rotating chuck 211 becomes exposed outside the cup 221. Therefore, the cup 221 becomes an obstacle, for example, to prevent the substrate S from being moved into and out of the rotating chuck 211.

[0038] Also, when cup 221 is in the upper position, as Figure 3 As shown, the peripheral portion of the substrate S, which is held in the rotating chuck 211, is surrounded. This prevents the processing liquid, thrown off the peripheral portion of the substrate S, from splashing into the chamber 200 during liquid supply (described later), and ensures reliable recovery of the processing liquid. In other words, droplets of processing liquid thrown off the peripheral portion of the substrate S by the rotation of the substrate S adhere to the inner wall of the cup 221, flow downwards, and are collected and recovered by the liquid receiving section 222 disposed below the cup 221. Multiple cups can be arranged concentrically to individually recover multiple processing liquids.

[0039] The processing fluid supply unit 23 has the following structure: a rotating support shaft 232 is rotatably mounted relative to a base 231 fixed in the processing chamber 200, and a nozzle 234 is mounted at the front end of an arm 233 extending horizontally from the rotating support shaft 232. The arm 233 swings as the rotating support shaft 232 rotates according to a control command from the control device 9. Thus, the nozzle 234 at the front end of the arm 233... Figure 2 The shown retreat position is the one that retreats laterally from the top of the substrate S, and is similar to... Figure 3 The processing positions above the substrate S shown are moved between them.

[0040] Nozzle 234 is connected to processing liquid supply source 238. When appropriate processing liquid is supplied from processing liquid supply source 238, processing liquid is ejected from nozzle 234 onto substrate S. Figure 3 As shown, while the substrate S is rotated at a relatively low speed by rotating the chuck 211, a processing liquid L1 is supplied from a nozzle 234 positioned above the center of rotation of the substrate S. Thus, the front surface Sa of the substrate S is processed by the processing liquid L1. The processing liquid L1 can be any liquid with various functions, such as developer, etchant, cleaning solution, or washing solution, and its composition is arbitrary. Furthermore, multiple processing liquids can be combined to perform the processing.

[0041] Another set of processing liquid supply units 24 also has a configuration corresponding to the first processing liquid supply unit 23. That is, the second processing liquid supply unit 24 has a base 241, a rotating support shaft 242, an arm 243, and a nozzle 244, etc. These configurations are the same as those in the first processing liquid supply unit 23. The rotating support shaft 242 rotates according to the control command from the control device 9, and the arm 243 swings. The nozzle 244 at the front end of the arm 243 supplies processing liquid to the front surface Sa of the substrate S.

[0042] In this embodiment, the second processing liquid supply unit 24 is used for the purpose of forming a liquid film to prevent drying of the wet-processed substrate S. That is, the wet-processed substrate S is transported to the supercritical processing apparatus 4 for supercritical drying treatment. At this time, in order to prevent the front side of the substrate S from being exposed and oxidized during transport, or the collapse of the fine patterns formed on the front side, the substrate S is transported with the front side covered by a paddle-shaped liquid film.

[0043] The liquid constituting the liquid film is a substance with a surface tension less than that of water, which is the main component of the treatment liquid used for the cleaning process. Examples of such organic solvents include isopropanol (IPA) or acetone. These organic solvents are supplied from organic solvent supply source 248.

[0044] Here, the wet processing apparatus 2 is provided with two sets of processing liquid supply units, but the number, structure, and function of the processing liquid supply units are not limited to this. For example, there may be only one set of processing liquid supply units, or there may be three or more sets. In addition, one processing liquid supply unit may have multiple nozzles. For example, multiple nozzles may be provided at the front end of one arm. Furthermore, in addition to the aspect of spraying processing liquid from the nozzles in a state of being positioned at a predetermined position as described above, there may also be the aspect of spraying processing liquid while the nozzles scan and move along the front side Sa of the substrate S.

[0045] Back Figure 1 Continuing the explanation, in the substrate conveying device 3, a conveying robot 30 is provided with a hand 31 at the front end of a telescopic and rotatable arm. The hand 31 supports the substrate by abutting against the lower surface portion of the substrate, such as... Figure 1 As shown by the dashed line, the transfer robot 30 can move freely forward and backward relative to both the wet processing unit 2 and the supercritical processing unit 4. This allows for the loading and unloading of substrates in both the wet processing unit 2 and the supercritical processing unit 4. The movement of the transfer robot 30 is controlled by the transfer control unit 96 of the control device 9. Many well-known technologies exist for this type of transfer robot, and since these technologies can be appropriately selected and used in this embodiment, detailed descriptions are omitted.

[0046] Figure 4This is a side view showing the configuration of the supercritical processing apparatus. The supercritical processing apparatus 4 corresponds to the first embodiment of the substrate processing apparatus of the present invention, and is an apparatus for performing drying treatment on a substrate S after wet processing using a supercritical processing fluid. More specifically, the supercritical processing apparatus 4 is an apparatus that receives the substrate S after wet processing, replaces the liquid remaining in the substrate S with a supercritical processing fluid, and then discharges the processing fluid, thereby ultimately bringing the substrate S to a dry state.

[0047] The supercritical processing apparatus 4 includes a processing unit 41, a transfer unit 43, and a supply unit 45. The processing unit 41 is the main body for performing supercritical drying processing. The transfer unit 43 receives the wet-processed substrate S transferred from the substrate transfer device 3 and transfers it into the processing unit 41. Furthermore, it transfers the processed substrate S from the processing unit 41 to an external transfer device. The supply unit 45 supplies the chemical substances, power, and energy required for processing to the processing unit 41 and the transfer unit 43. These operations are controlled by a control device 9, particularly a supercritical processing control unit 97.

[0048] The processing unit 41 has a structure in which a processing chamber 412 is mounted on a pedestal 411. The processing chamber 412 is composed of a combination of several metal blocks, and its interior forms a cavity, constituting a processing space SP. The substrate S to be processed is moved into the processing space SP for processing. On the (-Y) side of the processing chamber 412, a slit-like opening 421 extending elongated in the X direction is formed. Through the opening 421, the processing space SP communicates with the external space. The cross-sectional shape of the processing space SP is approximately the same as the opening shape of the opening 421. That is, the processing space SP is a cavity with a cross-sectional shape that is longer in the X direction and shorter in the Z direction, extending in the Y direction.

[0049] On the (-Y) side of the processing chamber 412, a cover member 413 is provided to close the opening 421. By closing the opening 421 of the processing chamber 412 with the cover member 413, an airtight processing container is formed. This allows for high-pressure processing of the substrate S within the internal processing space SP. On the (+Y) side of the cover member 413, a flat support tray 415 is mounted horizontally. The upper surface of the support tray 415 serves as a support surface for placing the substrate S. The cover member 413 is supported by a support mechanism (not shown) that allows for free horizontal movement in the Y direction.

[0050] The cover component 413 can move forward and backward relative to the processing chamber 412 via a forward / backward mechanism 453 provided in the supply unit 45. Specifically, the forward / backward mechanism 453 may be a linear motor, a direct-acting guide, a ball screw mechanism, a solenoid, or a cylinder, etc. This direct-acting mechanism moves the cover component 413 in the Y direction. The forward / backward mechanism 453 operates according to control commands from the control device 9.

[0051] The cover member 413 moves away from the processing chamber 412 by moving in the (-Y) direction. As shown by the dashed line, the support tray 415 can be received when it is pulled out of the processing space SP through the opening 421. That is, it is possible to place the substrate S on the support tray 415 and remove the substrate S placed on the support tray 415. On the other hand, the support tray 415 is housed in the processing space SP by moving the cover member 413 in the (+Y) direction. With the substrate S placed on the support tray 415, the substrate S is moved into the processing space SP together with the support tray 415.

[0052] The cover member 413 moves in the (+Y) direction to cover the opening 421, sealing the processing space SP. A sealing member 422 is provided between the (+Y) side of the cover member 413 and the (-Y) side of the processing chamber 412 to maintain the airtight state of the processing space SP. The sealing member 422 is, for example, made of rubber. In addition, the cover member 413 is fixed relative to the processing chamber 412 by a locking mechanism (not shown). Thus, in this embodiment, the cover member 413 switches between a closed state (solid line) in which the opening 421 is closed and the processing space SP is sealed, and a separated state (dashed line) in which the substrate S can enter and exit the opening 421.

[0053] Under conditions ensuring the airtightness of the processing space SP, the processing of the substrate S is performed within the processing space SP. In this embodiment, a processing fluid, such as carbon dioxide, capable of being used for supercritical processing, is supplied by the fluid supply section 457 of the supply unit 45. Furthermore, the processing fluid reaches a supercritical state by being pressurized within the processing chamber 412. The processing fluid is supplied to the processing unit 41 in either a gaseous or liquid state. Carbon dioxide reaches a supercritical state at relatively low temperatures and pressures, and also possesses the property of readily dissolving organic solvents commonly used in substrate processing, making it a suitable chemical substance for supercritical drying processing. The critical points for carbon dioxide to reach a supercritical state are a gas pressure (critical pressure) of 7.38 MPa and a temperature (critical temperature) of 31.1 °C.

[0054] When the processing fluid fills the processing space SP, and the processing space SP reaches an appropriate temperature and pressure, the processing space SP is filled with processing fluid in a supercritical state. In this way, the substrate S is processed in the processing chamber 412 using processing fluid in a supercritical state. A fluid recovery unit 455 is provided in the supply unit 45 to recover the processed fluid. The fluid supply unit 457 and the fluid recovery unit 455 are controlled by the supercritical processing control unit 97.

[0055] The processing space SP has a shape and volume capable of receiving the support tray 415 and the substrate S supported on the support tray 415. Specifically, the processing space SP has a generally rectangular cross-sectional shape that is wider in the horizontal direction than the width of the support tray 415 and greater in the vertical direction than the combined height of the support tray 415 and the substrate S, and a depth capable of receiving the support tray 415. Thus, the processing space SP has a shape and volume that only receives the support tray 415 and the substrate S. However, the gap between the support tray 415 and the substrate S and the inner wall surface of the processing space SP is small. Therefore, the amount of processing fluid required to fill the processing space SP is relatively small.

[0056] The fluid supply unit 457, located further to the (+Y) side than the substrate S, supplies processing fluid to the processing space SP. Conversely, the fluid recovery unit 455, located further to the (-Y) side than the substrate S, discharges processing fluid flowing in the processing space SP above the substrate S and below the support tray 415. Thus, within the processing space SP, laminar flow of processing fluid from the (+Y) side to the (-Y) side is formed in each of the areas above the substrate S and below the support tray 415.

[0057] The supercritical processing control unit 97 of the control device 9 controls the fluid supply unit 457 and the fluid recovery unit 455 based on the detection results of the detection unit (not shown) and the pressure and temperature within the specific processing space SP. This appropriately manages the supply of processing fluid to the processing space SP and the discharge of processing fluid from the processing space SP. The pressure and temperature within the processing space SP are adjusted according to a predetermined processing formula.

[0058] The transfer unit 43 is responsible for transferring the substrate S between the substrate transfer device 3 and the support tray 415. For this purpose, the transfer unit 43 includes a body 431, a lifting member 433, a base member 435, and multiple lifting pins 437. The lifting member 433 is a columnar member extending in the Z direction, supported by a support mechanism (not shown), which allows it to move freely in the Z direction relative to the body 431. The base member 435, having a generally horizontal upper surface, is mounted on the upper part of the lifting member 433. Multiple lifting pins 437 are erected facing upwards from the upper surface of the base member 435. Each lifting pin 437 abuts against the lower surface of the substrate S at its upper end, supporting the substrate S in a horizontal position from below. To stably support the substrate S in a horizontal position, it is desirable to provide three or more lifting pins 437 with equal upper end heights.

[0059] The lifting component 433 can be moved up and down via a lifting mechanism 451 provided in the supply unit 45. Specifically, the lifting mechanism 451 may be a linear motor, a direct-acting guide, a ball screw mechanism, a solenoid, or a cylinder, etc. This direct-acting mechanism causes the lifting component 433 to move in the Z direction. The lifting mechanism 451 operates according to control commands from the control device 9.

[0060] The base component 435 moves up and down due to the lifting mechanism 433, and multiple lifting pins 437 move up and down together with it. This achieves the transfer of the substrate S between the transfer unit 43 and the support tray 415. More specifically, as... Figure 4 As shown by the dashed line, the substrate S is transferred when the support tray 415 is pulled out of the cavity. For this purpose, the support tray 415 is provided with a through hole 419 for inserting the lifting pin 437. When the base component 435 rises, the upper end of the lifting pin 437 reaches above the upper surface of the support tray 415 through the through hole 419. In this state, the substrate S, which has been transported by the transfer robot 30, is transferred from the hand 31 of the transfer robot 30 to the lifting pin 437. As the lifting pin 437 descends, the substrate S is transferred from the lifting pin 437 to the support tray 415. The substrate S can be removed in the reverse order.

[0061] Next, the supply path of the processing fluid to the processing chamber 412 and the discharge path of the processing fluid from the processing chamber 412 will be described in more detail. Above, the supply of processing fluid from the fluid supply unit 457 to the processing chamber 412 and the recovery of processing fluid from the processing chamber 412 to the fluid recovery unit 455 were briefly described. In the actual device, the fluid supply unit 457 and the fluid recovery unit 455 have the following configuration.

[0062] Figure 5 It is a diagram showing the details of the supply and discharge paths for the processed fluid. Additionally, Figure 5In the diagram, for ease of illustration, the orientation of the processing chamber 412 is shown in the figure. Figure 4 On the contrary, that is to say, Figure 4 In the middle, the processing fluid is introduced into the processing chamber 412 from the right side of the paper and discharged to the left side of the paper. On the other hand, Figure 5 Conversely, the flow becomes one where the processing fluid is introduced into the processing chamber 412 from the left side of the paper and discharged to the right side of the paper. That is to say, Figure 5 In the processing chamber 412, a diagram showing the relationship with... Figure 4 The processing chamber 412 is on the opposite side.

[0063] First, the detailed structure of the fluid supply unit 457 will be described. The fluid supply unit 457 mainly consists of a fluid supply source 700, a purification unit 710, a supply unit 720, and piping groups 730 and 740 connecting these. These operate according to control commands from the supercritical processing control unit 97.

[0064] The fluid supply source 700 outputs the substance used as a processing fluid in the supercritical process (carbon dioxide in this embodiment) as needed. The fluid supply source 700 may also be provided as part of the substrate processing system 1 and may be constituted by a container for storing the substance, such as a high-pressure gas cylinder. Alternatively, it may be an external supply source separately provided with the substrate processing system 1.

[0065] At the fluid supply source 700, a portion of the piping group 730, namely piping 731, is connected. The processed fluid delivered from the fluid supply source 700... Figure 5 The fluid flows through piping 731 from center to right. In piping 731, along the flow direction of the processed fluid, valves V70 and V71, purifier 711, filter 712, condenser 713, and valve V72 are sequentially arranged. Valve V70 is, for example, a pressure regulating valve that functions to adjust the pressure of the processed fluid flowing through piping 731. The other valves, V71 and V72, are on / off valves that switch the flow of fluid.

[0066] Valve V70 allows the flow of the processed fluid at a pressure specified by the control command from the supercritical processing control unit 97 into piping 731. Purifier 711 and filter 712 remove impurities from the processed fluid, increasing its purity. Condenser 713 condenses the processed fluid supplied as gas from fluid supply source 700. When valves V71 and V72 are opened, the processed fluid is output from piping 731.

[0067] Pipeline 731 merges with pipe 735, which connects to storage tank 717 (described later), at the output side of valve V72. A condenser 714, a booster pump 715, and a filter 716 are installed in pipe 732 after the merger. The condenser 714 is installed to more reliably maintain the processed fluid in a liquid phase. The booster pump 715 pressurizes and delivers the liquid processed fluid. The filter 716 removes impurities from the processed fluid.

[0068] Pipe 732 branches into two pipes 733 and 734 on the output side of filter 716. Pipe 733 is connected to the upper part of storage tank 717, and an on / off valve, namely valve V74, is inserted along it. In addition, an on / off valve, namely valve V75, is inserted into pipe 734.

[0069] Storage tank 717 is a high-pressure vessel capable of storing pressurized liquid processed fluid. A level sensor 718 is installed in storage tank 717 to manage the liquid level. Therefore, the internal space of storage tank 717 is not liquid-tight; the vaporized processed fluid is stored in the space above the liquid surface at a pressure similar to that of the liquid. Furthermore, a heater 719 is installed in storage tank 717, which heats the processed fluid in the tank according to control commands from the supercritical processing control unit 97.

[0070] Pipeline 735 is connected to the lower part of storage tank 717. Pipeline 735 merges with pipeline 731 and connects to pipeline 732. When the on / off valve V73, which is inserted in pipeline 735, is opened, the liquid of the processing fluid in storage tank 717 flows into pipeline 732 through pipeline 735. If valve V74 on pipeline 733 is further opened, a return flow path is formed from storage tank 717 through pipes 735, 732, and 733 back to storage tank 717. If the processing fluid is circulated in the return flow path while the processing fluid is pressurized by pressurization pump 715, the pressure of the processing fluid can be increased in stages. Finally, the processing fluid is stored in storage tank 717 at a pressure specified by the control command from supercritical processing control unit 97.

[0071] An output pipe 736 is connected to the upper part of the storage tank 717. Pipe 736 merges with pipe 734 via an on / off valve, namely valve V76. Processing fluid that fills the upper part of the internal space of the storage tank 717 is output from pipe 736. After merging with pipes 734 and 736, pipe 741 selectively receives either the gaseous processing fluid when valve V76 is open or the liquid processing fluid when valve V75 is open.

[0072] Thus, the refining unit 710 of the fluid supply section 457 has the following function: after removing impurities from the processing fluid supplied by the fluid supply source 700, it selectively outputs the phase required for subsequent processing, specifically, the gas phase and the liquid phase of the processing fluid.

[0073] Pipe 741 is part of a piping group 740 that forms the inlet flow path for introducing the processed fluid from the refining unit 710 to the processing chamber 412. Pipe 741 branches into two pipes 743 and 744 downstream of the on / off valve, namely valve V77, and filters 721 and 722 are installed on each pipe. These pipes 743 and 744 temporarily merge to form pipe 745, which further branches into two pipes 747 and 748.

[0074] In piping 747, along the flow direction of the processed fluid (to the right in the figure), a flow meter 723, a heater 725, an on / off valve (valve V78), and a filter 727 are sequentially inserted. Piping 747 is finally connected to the processing chamber 412. More specifically, piping 747 is located on the support tray 415 of the support substrate S (… Figure 4 Above, it communicates with the internal space SP. On the other hand, along the flow direction of the processed fluid, a flow meter 724, a heater 726, an on / off valve (valve V79), and a filter 728 are sequentially inserted in the piping 748. Furthermore, the piping 748 is located above the support tray 415 of the support substrate S. Figure 4 Below, it communicates with the internal space SP of the processing chamber 412. Thus, processing fluid is supplied to the spaces above and below each of the substrate S placed on the support tray 415 in the internal space SP.

[0075] Flow meters 723 and 724 measure the flow rate of the processed fluid at various locations and send the results to the supercritical processing control unit 97. Heaters 725 and 726 heat the processed fluid to a specified temperature according to control commands from the supercritical processing control unit 97. Filters 727 and 728 ultimately remove impurities from the processed fluid introduced into the processing chamber 412.

[0076] Thus, the fluid supply unit 457 can supply the processing chamber 412 with purified processing fluid, the temperature of which is adjusted to a predetermined target value. The sequence of supplying the processing fluid from the fluid supply unit 457 to the processing chamber 412 will be described in detail below.

[0077] The processing fluid supplied to the processing chamber 412 is discharged from the storage tank 717, and the processing fluid pressurized by the booster pump 715 is stored in the storage tank 717. Therefore, the pressure of the processing fluid discharged from the fluid supply source 700 can also be lower than the pressure required for processing. Furthermore, if the fluid supply source 700 can stably discharge processing fluid at a pressure suitable for processing, such as... Figure 5 As shown by the dashed line, the gaseous processing fluid can also be supplied directly from the fluid supply source 700 via piping 737, without needing to obtain it from the storage tank 717. Alternatively, the pressure-regulated processing fluid can be supplied from the output side of valve V70.

[0078] Next, the detailed structure of the fluid recovery unit 455 will be described. The fluid recovery unit 455 mainly consists of a high-pressure exhaust tank 505, a low-pressure exhaust tank 508, and a piping group 530 connecting these exhaust tanks. These operate according to control commands from the supercritical processing control unit 97.

[0079] At the upper part of the processing chamber 412, a pipe 531, which forms part of the piping group 530, is connected. On the other hand, a pipe 532 is connected to the lower part of the processing chamber 412. These pipes 531 and 532 respectively discharge the processing fluid flowing above and below the support tray 415 within the internal space SP from the processing chamber 412 to the outside. A pressure gauge 503 is installed on the pipe 531.

[0080] In piping 531, a flow meter 501 and an on / off valve (valve V51) are sequentially inserted along the flow direction of the processed fluid. Conversely, in piping 532, a flow meter 502 and an on / off valve (valve V52) are sequentially inserted along the flow direction of the processed fluid. Pipes 531 and 532 merge on the output side of valves V51 and V52. In the merged piping 533, a pressure regulating valve (valve V53) and an on / off valve (valve V54) are inserted.

[0081] Pipe 533 is connected to high-pressure exhaust tank 505, and the processing fluid discharged from processing chamber 412 is contained in high-pressure exhaust tank 505 via pipe 533. A heater 506 is provided in high-pressure exhaust tank 505 to maintain the temperature of the processing fluid stored inside appropriately.

[0082] A piping 544 is connected to the upper part of the high-pressure exhaust tank 505. An on / off valve (valve V55), a pressure regulating valve (valve V56), and a heater 507 are interposed within the piping 544. The piping 544 ultimately connects to the low-pressure exhaust tank 508. Therefore, the processed fluid, which is the gas after appropriate pressure and temperature adjustment, flows into the low-pressure exhaust tank 508. The processed fluid in the low-pressure exhaust tank 508 is ultimately recovered via piping 545 by an external recovery device (not shown). Piping 545 is equipped with a heater 509 for adjusting the temperature of the gas discharged to the outside, and a pressure gauge 510 for detecting the gas pressure.

[0083] Furthermore, a piping 546 is connected to the lower part of the high-pressure exhaust tank 505, and a piping 547 is connected to the lower part of the low-pressure exhaust tank 508. These piping lines merge to form piping 548, which is connected to an on / off valve, namely valve V57. When valve V57 is opened, the treated fluid of the liquid stored in the high-pressure exhaust tank 505 and the low-pressure exhaust tank 508 is discharged to an external recovery device.

[0084] refer to Figure 6 and Figure 7The operation of the supercritical processing apparatus 4 configured as described above will be explained. The supercritical processing apparatus 4 performs a process using a supercritical processing fluid to bring the wet-processed substrate S to a dry state, which is called supercritical drying. This process is achieved by the CPU 91 of the control device 9 executing a pre-prepared control program, thereby controlling each part of the device.

[0085] Figure 6 This is a flowchart illustrating the processes performed by the supercritical processing unit. Furthermore, Figure 7 This is a diagram showing the pressure changes within the processing chamber and storage tank during the process. The fluid supply unit 457 supplies gaseous and liquid processing fluids from the storage tank 717, which stores the processing fluids, to the processing chamber 412. Therefore, the pressure within the processing space SP of the processing chamber 412 (hereinafter referred to as "chamber pressure") and the pressure within the internal space of the storage tank 717 (hereinafter referred to as "tank pressure") change as the process progresses.

[0086] First, the substrate transfer device 3, in cooperation with the supercritical processing device 4, transfers the substrate S into the processing chamber 412 (step S101). Specifically, the transfer robot 30 of the substrate transfer device 3 holds the substrate S after the liquid film formation process in the wet processing device 2 and places the substrate S on the support tray 415, which is pulled out from the processing chamber 412. More precisely, the substrate S is first transferred from the hand 31 of the transfer robot 30 to the lifting pin 437 of the supercritical processing device 4, and then the substrate S is transferred from the lifting pin 437 to the support tray 415.

[0087] A support tray 415 carrying the substrate S is housed in a processing chamber 412. The processing space SP inside the processing chamber 412 is sealed by closing the opening 421 of the processing chamber 412 with a cover member 413. Thus, the loading of the substrate S is completed. Since the processing chamber 412 is open to the atmosphere for loading the substrate S, ... Figure 7 As shown in the upper section, the internal pressure of the processing chamber 412 is atmospheric pressure Pa in the initial state.

[0088] Thus, during the transfer of substrate S, the fluid supply unit 457 performs a predetermined standby operation (step S102). Details are described below; the standby operation is the process in the fluid supply unit 457 used to prepare the required amount of processing fluid at the appropriate temperature and pressure for subsequent processing. As described later, in this embodiment, gaseous carbon dioxide at 20°C and 6 MPa, and carbon dioxide supercriticalized from 20°C and 11 MPa by heating, are used for processing.

[0089] After the substrate S is placed in, a gaseous processing fluid is introduced from the fluid supply unit 457 (step S103; time T1), thereby gradually increasing the pressure inside the chamber. When the pressure inside the chamber rises to a predetermined first pressure P1 (step S104; time T2), a supercritical processing fluid is supplied from the fluid supply unit 457 to the processing chamber 412 to replace the gas (step S105; time T3).

[0090] Thus, the processing space SP of the processing chamber 412 is filled with a supercritical processing fluid, and the internal pressure of the chamber is maintained at a first pressure P1 and a certain second pressure P2 (at times T4 to T5) that is greater than the critical pressure of the processing fluid. During this period, the liquid remaining attached to the substrate S is replaced by the supercritical processing fluid, dissolved into the processing fluid, and removed from the front side of the substrate S.

[0091] When the pressure inside the chamber is maintained at approximately pressure P2 for a predetermined time (step S106), the processing fluid begins to be discharged from the processing chamber 412 (step S107; time T5), thereby depressurizing the processing space SP. After the pressure inside the chamber decreases to near atmospheric pressure Pa at time T7, the substrate S is removed by the transfer robot 30 (step S108), and the processing of one substrate S is completed. Then, if there are substrates to be processed, return to step S101 (step S109) and repeat the process.

[0092] like Figure 7 As shown in the next section, the pressure inside the tank gradually decreases as the processing fluid stored in the tank 717 is consumed. To restore it, pressurized processing fluid is replenished to the tank 717; for this purpose, a standby operation (step S111) is performed. The standby operation can be performed after the moment T6 when the supply of processing fluid from the tank 717 to the processing chamber 412 stops. Therefore, as... Figure 7 As shown, during the decompression process within the processing chamber 412, a standby operation can be initiated.

[0093] When performing supercritical drying on substrate S, it is desirable to pre-increase the tank pressure to the same level as or slightly higher than the first pressure P1 during standby operation, in a manner that allows the chamber pressure to be increased to the first pressure P1 in step S103 of the process.

[0094] Figures 8 to 11 These are diagrams illustrating the status of valves at each stage of the process. In these diagrams, the flow of the process fluid as a gas in the flow path is represented by thick dashed arrows, and the flow of the process fluid as a liquid is represented by thick solid arrows. Furthermore, especially... Figure 10 In the diagram, the flow of the supercritical fluid is represented by a hollow arrow.

[0095] Furthermore, in these diagrams, valves marked with a white circle (○) near the symbol and a single underline on the symbol indicate that the valve is open. Conversely, valves marked with a black circle (●) near the symbol and a double underline on the symbol indicate that the valve is closed. Valves not marked with these symbols do not directly affect the processing described below; therefore, their open / closed states are not specifically defined here.

[0096] Figure 8 This shows the valve's open / closed state during standby operation. During standby operation, the processing fluid output from the fluid supply source 700 is pressurized by the booster pump 715 and flows into the storage tank 717. This raises the pressure inside the tank to the target value. For the stated purpose, as... Figure 8 As shown, valves V71, V72, and V74 are opened, while valves V73, V75, and V76 are closed.

[0097] Therefore, the processed fluid, output from the fluid supply source 700 and whose pressure is adjusted by valve V70, is stored in the storage tank 717 as a liquid pressurized to a specified pressure by the booster pump 715. The liquid level in the tank is monitored by the level sensor 718. The processed fluid continues to be supplied until a predetermined amount of liquid at a predetermined pressure has been accumulated. In addition, the temperature of the processed fluid in the tank is adjusted by the heater 719.

[0098] Thus, during standby periods when no processing fluid is supplied from storage tank 717 to processing chamber 412 ( Figure 7 Before time T1 and after time T6, a standby operation is performed to maintain the liquid volume, pressure, and temperature in the tank at specified values. The target pressure is a pressure of the first pressure P1 or slightly higher, which is 6 MPa in this embodiment. The target temperature is 20°C in this embodiment. Furthermore, the target liquid volume is set to the amount of processing fluid sufficient to supply the processing chamber 412 during the supercritical drying process.

[0099] Figure 9 The opening and closing states of the valves during gas introduction are shown. In step S103 (times T1 to T2), a gaseous processing fluid is introduced into the processing chamber 412 to increase the internal pressure. During this pressurization phase, valves V72, V74, etc., on the path supplying the processing fluid to the storage tank 717 are closed, cutting off the supply path. On the other hand, valve V76, connected to the piping 736 above the tank, and valves V77 to V79, etc., installed in the piping group 740 are opened. Therefore, the gas inside the storage tank 717, which is filled with the processing fluid above the liquid level, is supplied to the processing chamber 412 through the piping group 740.

[0100] thus, Figure 7The pressure inside the chamber shown in the upper section rises from atmospheric pressure Pa to the first pressure P1. At this time, Figure 7 The pressure inside the tank shown in the lower section begins to decrease at the moment T1 when the processed fluid begins to be discharged. However, the decrease in pressure inside the tank gradually slows down as the heater 719 operates to compensate for the decrease in temperature inside the tank caused by the rapid pressure drop.

[0101] On the other hand, in the fluid recovery unit 455, valves V51 to V57 installed in the piping group 530 are opened to form a discharge path for the processed fluid. Therefore, during the pressurization stage, a certain amount of processed fluid is also discharged. As a result, the atmosphere, liquid, impurities, etc. remaining in the processing chamber 412 are also discharged outside the chamber.

[0102] Furthermore, the internal pressure of the chamber can be indirectly measured via a pressure gauge 503 installed on a pipe 531 connected to the processing space SP in the discharge flow path. Therefore, in step S106, the internal pressure of the chamber can be determined using the measurement result of the pressure gauge 503. However, if the correlation between the amount of processing fluid supplied to the processing chamber 412 and the internal pressure of the chamber is determined in advance, the time until the internal pressure of the chamber reaches the target value can be predicted. Therefore, in a practical device, by pre-determining the length of the period during which the valve V76 controlling the gas delivery is opened, the actual measurement of the internal pressure of the chamber can be omitted. In other words, as explained above, in step S106, a judgment based on elapsed time can be used.

[0103] Figure 10 The opening and closing states of the valves during the introduction of supercritical processing fluid are shown. In step S105 (times T3 to T5), supercritical processing fluid is supplied to processing chamber 412. Therefore, it is necessary to ensure that the temperature of the supplied processing fluid is higher than the critical temperature and the pressure is higher than the critical pressure. Therefore, the gas supply is stopped by closing valve V76, and instead, valves V73 and V75 are opened, thereby supplying the liquid processing fluid stored in storage tank 717 to processing chamber 412.

[0104] A pressurizing pump 715 is installed in the flow path of the processing fluid, and the processing fluid is conveyed in the piping group 740 at a pressure increased to above the critical pressure (the second pressure P2 in this embodiment). The processing fluid is heated to above the critical temperature by heaters 725 and 726 installed in the flow path, and the processing fluid flows into the processing chamber 412 in a supercritical state. In this way, the processing space SP is filled with the supercritical processing fluid.

[0105] In this case, the discharge path for discharging a small amount of processing fluid from the processing chamber 412 is opened. Therefore, liquids that have been displaced by the processing fluid and detached from the substrate S are discharged to the outside along with the processing fluid, preventing re-adhesion onto the substrate S. The pressure inside the tank decreases sharply as liquid begins to be discharged, but the degree of pressure reduction is reduced by heating by the heater 719.

[0106] At time T5, the flow rate of the processing fluid output from the pressurized pump 715 decreases, thereby causing the chamber pressure to decrease. To prevent damage to the substrate S due to liquefaction or solidification of the processing fluid caused by rapid decompression, the decompression rate is adjusted by directly changing the processing fluid from a supercritical state to a gaseous phase. If the chamber pressure is sufficiently reduced (e.g., below the critical pressure), the risk of liquefaction and solidification disappears, then the supply of processing fluid to the processing chamber 412 is stopped, and the discharge flow rate is increased to discharge any remaining processing fluid. This allows for rapid decompression.

[0107] For example, it is possible to adopt methods such as from Figure 10 As shown, at time T6, valve V75 is closed, and valve V74 is opened instead. Thus, the processing fluid supplied from the pressurization pump 715 flows back to the storage tank 717, thereby suppressing the decrease in pressure within the tank. Furthermore, after stopping the supply of processing fluid to the processing chamber 412, it is possible to replenish processing fluid to the storage tank 717 from the fluid supply source 700.

[0108] Figure 11 The valve's open / closed state during fluid replenishment is shown. In the fluid recovery unit 455, even during the depressurization process, after the supply of process fluid to the processing chamber 412 is stopped—that is, after valve V75 is closed at time T6—the flow of process fluid from the fluid supply source 700 can resume. This allows process fluid to be supplied to the storage tank 717 via the pressurization pump 715. This restores the tank's pressure and volume, preparing for the processing of the next substrate.

[0109] The operation of the fluid supply unit 457 at this time is compared as follows: Figure 8 and Figure 11 As can be seen, this is the same as the standby operation. That is, the standby operation of the fluid supply unit 457 can be performed simultaneously with the decompression operation in the fluid recovery unit 455 and the subsequent removal of the substrate S by the transfer robot 31. Therefore, after the processed substrate is removed, a new substrate can be quickly received and processed.

[0110] As described above, in the supercritical drying process of this embodiment, gaseous carbon dioxide (20°C, 6 MPa) is first introduced into the processing chamber 412 as a processing fluid to pressurize the processing space SP. Then, liquid carbon dioxide (20°C, 11 MPa) is heated to supercriticality and introduced into the processing chamber 412. The reason for supplying the processing fluid in this two-stage manner will be explained below.

[0111] Figure 12 This is a state diagram of the processing fluid, namely carbon dioxide. In the diagram, point C represents the critical point of carbon dioxide, with a critical pressure Pc of 7.38 MPa and a critical temperature Tc of 31.1 °C. The state of the processing fluid introduced in the initial stage of the supercritical drying process is represented by point A. As mentioned above, the pressure (first pressure P1) of the processing fluid at this time is 6 MPa, and the temperature is 20 °C. Therefore, the processing fluid is introduced as a gas into the processing chamber 412.

[0112] As shown in the state diagram, point A, specified by the pressure and temperature, is located at the boundary between the liquid and gas phases, that is, in the region slightly transitioning from the state of gas-liquid equilibrium to the gas phase side. In other words, the pressure at this point is slightly less than the maximum pressure achievable by the gas phase processing fluid, which is lower than the critical temperature Tc. In other words, the first pressure P1 is set in a manner that satisfies this condition. More preferably, point A is as close as possible to the critical point C within a range where the processing fluid does not liquefy or becomes supercritical.

[0113] After the pressure inside the chamber rises to the first pressure P1, the supercritical processing fluid is introduced into the processing chamber 412. The state of the processing fluid at this time is represented by point B. The pressure of the processing fluid is greater than the critical pressure Pc, which is 11 MPa (the second pressure P2) in this embodiment. In addition, the temperature is set to an appropriate value exceeding the critical temperature Tc.

[0114] Thus, the rationale for using a two-stage pressurization process—that is, first filling the processing chamber 412 with a relatively low-pressure, gaseous processing fluid, and then introducing a higher-pressure, supercritical processing fluid—is as follows. In conventional techniques, when a high-pressure supercritical processing fluid is directly introduced into a processing chamber at atmospheric pressure, poor processing results sometimes occur, such as particle adhesion to the substrate or pattern collapse. According to the inventors of this invention, this is because when a high-pressure, high-density processing fluid flows into a low-pressure processing chamber, a portion of the cooling processing fluid due to adiabatic expansion solidifies or liquefies and adheres to the substrate.

[0115] To avoid this phenomenon, in this embodiment, the gaseous processing fluid is pre-introduced into the processing chamber 412, and the internal pressure of the chamber is pre-raised to a pressure slightly below the critical pressure Pc. Under this condition, a higher-pressure supercritical processing fluid is introduced. By increasing the internal pressure of the chamber in two stages in this way, liquefaction and solidification of the processing fluid within the chamber can be prevented.

[0116] Furthermore, by contacting the gaseous processing fluid with the liquid film of the organic solvent on the front side of the substrate S, the processing fluid dissolves into the liquid, which has the effect of reducing the surface tension of the liquid. First, by introducing the processing fluid as a gas into the processing chamber 412, the surface tension of the liquid is reduced in advance, which can improve the displacement efficiency when introducing the supercritical processing fluid.

[0117] According to the inventors' experiments, when a supercritical processing fluid at a pressure of 11 MPa is directly introduced into the processing chamber 412, or when the pressure of the pre-introduced gas is 4 to 5 MPa, processing defects that damage the substrate sometimes occur. On the other hand, setting the gas pressure (first pressure P1) to 6 MPa can effectively suppress such processing defects. If the pressure is increased further, the risk of liquefaction of the processing fluid actually increases.

[0118] With the first pressure P1 set to 6 MPa and the second pressure P2 set to 11 MPa, the pressure difference when the gaseous processing fluid is pressurized from atmospheric pressure (Pa) to the first pressure P1 is greater than the pressure difference when the supercritical processing fluid is pressurized from the first pressure P1 to the second pressure P2. In other words, the gaseous processing fluid bears more than half of the pressure increase from atmospheric pressure (Pa) to the final target second pressure P2. Therefore, liquefaction or solidification that might occur due to the introduction of a processing fluid with a large pressure difference is prevented.

[0119] In this embodiment, by selectively opening valves V75 and V76, the gas processing fluid and the liquid processing fluid are switched, sharing the piping group 740 as their flow path. This simplifies the piping configuration and reduces the introduction of impurities caused by piping systems containing valves.

[0120] As described above, in this embodiment, the supercritical processing apparatus 4 corresponds to the "substrate processing apparatus" of the present invention. Furthermore, the processing chamber 412, which has a processing space SP as its "internal space," functions as the "processing chamber" of the present invention. Additionally, the storage tank 717 functions as the "storage section" of the present invention, and its internal space corresponds to the "storage space."

[0121] Furthermore, the supercritical drying process described in the embodiment ( Figure 6In this process, steps S103 and S104 correspond to the "first step" of the present invention, and steps S105 and S106 correspond to the "second step" of the present invention. Furthermore, step S107 corresponds to the "third step" of the present invention. Moreover, steps S102 and S111 correspond to the "storage step" of the present invention.

[0122] Furthermore, the present invention is not limited to the described embodiments, and various modifications can be made beyond the scope thereof without departing from its spirit. For example, the fluid supply unit 457 of the described embodiment includes a number of flow meters or filters, which are generally provided in the flow path of the fluid being processed, but are not directly related to the present invention. Even if these are omitted, the present invention can still be established.

[0123] Furthermore, as in the described embodiment, the introduction of processing fluid into the processing chamber 412 and the discharge of processing fluid from the processing chamber 412 are performed individually on each of the upper and lower sides of the support tray 415. However, this is not a necessary requirement for the technical concept of the present invention.

[0124] Furthermore, in the aforementioned embodiment, the gas and liquid processing fluids are extracted from a single storage tank 717. However, the gas and liquid supply sources can also be configured as independent components. For example, they can be stored separately as individual gas and liquid storage units.

[0125] Furthermore, the various chemical substances used in the processing of the described embodiments are only a subset of examples. If a chemical substance is consistent with the technical concept of the present invention, then various chemical substances can be used to replace it.

[0126] As illustrated above with specific embodiments, the substrate processing method of the present invention may, for example, be configured such that the first pressure is lower than the pressure at which the processing fluid liquefies when the temperature is lower than that of the processing fluid supplied to the processing chamber in the first step. With this configuration, the processing fluid delivered in the first step can be reliably maintained in a gaseous state.

[0127] Furthermore, according to the inventors of this case, by introducing gas to sufficiently increase the internal pressure of the processing chamber beforehand, liquefaction or solidification is prevented when the critical processing fluid is subsequently introduced. For example, the pressure difference between atmospheric pressure and the first pressure can be set in a manner greater than the pressure difference between the first pressure and the second pressure.

[0128] Furthermore, for example, the second step can be configured to heat the liquid of the processing fluid, which is pressurized to a second pressure, to a supercritical state, and then allow it to flow into the internal space. With this configuration, the processing fluid, which is being delivered as liquid to the flow path, can be supercritically charged directly in front of the processing chamber, and the temperature and pressure of the processing fluid flowing into the internal space can be precisely controlled.

[0129] Alternatively, the device can be configured such that the processing fluid, which is a liquid pressurized to a first pressure, is pre-stored in the storage space of the storage unit. In the first step, the gaseous processing fluid is pumped from the storage space above the liquid surface of the processing fluid into the processing chamber. On the other hand, in the second step, the liquid processing fluid, which is taken from the storage space below the liquid surface, is pressurized and pumped into the processing chamber. With this configuration, the processing fluid, which is both gaseous and liquid, can be stored in a single storage unit, simplifying the configuration of the apparatus used to implement the invention.

[0130] In this case, a storage step may also be included before the first step. This storage step receives the processing fluid at a pressure lower than the first pressure, pressurizes it to the first pressure, and stores it in a storage unit. With this configuration, since the processing fluid can be pressurized and stored in the storage unit, the processing fluid supplied from a more upstream side can itself be at a pressure lower than the first pressure. In other words, the processing fluid has a greater degree of freedom relative to the supply source.

[0131] The storage process can be performed simultaneously with the process of moving the substrate into the processing chamber. Furthermore, after the second process, there is a third process that discharges the processing fluid and depressurizes the internal space. When processing multiple substrates sequentially, the storage process can begin while the third process is being performed on one substrate. Since the storage process can be performed even without removing the processing fluid from the storage unit, by performing it simultaneously with processes such as substrate movement or depressurization of the internal space, processing time can be shortened.

[0132] Furthermore, for example, the first and second processes can be configured to discharge the processing fluid from the processing chamber at a discharge rate less than the inflow rate of the processing fluid flowing into the processing chamber. With this configuration, a portion of the processing fluid is discharged simultaneously with the supply of high-pressure processing fluid to the internal space of the processing chamber. Therefore, it is possible to discharge unavoidably entering external air or impurities detached from the substrate along with the processing fluid to the outside, preventing substrate contamination.

[0133] The invention has been described above with reference to specific embodiments, but this description is not intended to be limited in meaning. When referring to the description of the invention, various variations of the disclosed embodiments will become apparent to those skilled in the art, as with other embodiments of the invention. Therefore, the appended claims are considered to encompass the said variations or embodiments without departing from the true scope of the invention.

[0134] [Industry availability]

[0135] This invention can be applied to the entire technology of processing substrates with supercritical processing fluids in a processing chamber.

[0136] [Symbol Explanation]

[0137] 4. Supercritical treatment unit

[0138] 412 Processing Chamber

[0139] 457 Fluid Supply Department

[0140] 700 Fluid Supply Source

[0141] 715 Booster Pump

[0142] 717 Storage Tank (Storage Section)

[0143] SP processing space (internal space).

Claims

1. A substrate processing method, comprising processing a substrate with a supercritical processing fluid within a processing chamber, comprising: In the first step, the processing fluid is introduced into the internal space of the processing chamber containing the substrate, as a gas pressurized to a first pressure lower than the critical pressure, thereby increasing the pressure of the internal space to the first pressure; and In the second step, the internal space, which has been pressurized to the first pressure, is filled with the processing fluid at a second pressure higher than the critical pressure, thus filling the internal space with the processing fluid in a supercritical state.

2. The substrate processing method according to claim 1, wherein the first pressure is lower than the pressure at which the processing fluid liquefies when it is at a temperature lower than that at which the processing fluid is introduced into the processing chamber in the first step.

3. The substrate processing method according to claim 1, wherein the pressure difference between atmospheric pressure and the first pressure is greater than the pressure difference between the first pressure and the second pressure.

4. The substrate processing method according to claim 1, wherein in the second step, the liquid of the processing fluid pressurized to the second pressure is heated to a supercritical state and then allowed to flow into the internal space.

5. The substrate processing method according to any one of claims 1 to 4, wherein the processing fluid, which is a liquid pressurized to the first pressure, is pre-stored in the storage space of the storage unit. In the first step, the gas of the processed fluid is delivered from the storage space above the liquid surface of the processed fluid into the processing chamber. On the other hand, In the second step, the liquid of the processing fluid taken from the storage space below the liquid surface is pressurized and sent to the processing chamber.

6. The substrate processing method according to claim 5, wherein prior to the first step, a storage step is provided, the storage step receiving the processing fluid at a pressure lower than the first pressure, pressurizing it to the first pressure, and storing it in the storage unit.

7. The substrate processing method according to claim 6, wherein, prior to the first step, the steps of moving the substrate into the processing chamber and the storage step are performed simultaneously.

8. The substrate processing method according to claim 6, wherein after the second step, a third step is performed to discharge the processing fluid and depressurize the internal space. In the case of processing multiple substrates in sequence, the storage process begins during the execution of the third process on one of the substrates.

9. The substrate processing method according to claim 1, wherein in the first step and the second step, the processing fluid is discharged from the processing chamber at a discharge rate less than the inflow rate of the processing fluid flowing into the processing chamber.

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