Substrate processing apparatus

Abstract

To reduce processing defects such as particle adhesion and pattern collapse that may occur due to a temperature decrease during introduction of a supercritical processing fluid into a processing chamber.SOLUTION: A substrate processing apparatus includes: a first supply unit for supplying a processing fluid to a processing chamber as a gas pressurized to a first pressure lower than a critical pressure; a second supply unit for supplying the processing fluid at a second pressure higher than the critical pressure; an introduction flow path for introducing the processing fluid into an internal space of the processing chamber; a first pipe connecting the first supply unit and the introduction flow path via a first valve; a second pipe connecting the second supply unit and the introduction flow path via a second valve; and a control unit for controlling the first valve and the second valve to selectively cause the processing fluid at the first pressure and the processing fluid at the second pressure to flow into the internal space, the second supply unit including a storage unit for storing the processing fluid in a liquid state and a pressurizing unit inserted in the second pipe extending from the storage unit to the second valve for pressurizing the processing fluid to the second pressure and sending out the processing fluid.SELECTED DRAWING: Figure 5

Description

[Technical Field]

[0001] The present invention relates to a technique for placing a substrate in a processing chamber and processing it with a processing fluid in a supercritical state. [Background technology]

[0002] Processing processes for various substrates, such as semiconductor substrates and glass substrates for display devices, include treating the surface of the substrate with various processing fluids. Wet processing using liquids such as chemicals and rinses as processing fluids has been widely used. In recent years, processing using processing fluids in a supercritical state has also been put to practical use to dry substrates after such wet processing. This is particularly useful in drying substrates having a patterned surface on which a fine pattern is formed. This is because processing fluids in a supercritical state have a lower surface tension than liquids and have the property of penetrating deep into the gaps in the pattern. Using such processing fluids enables efficient drying processing. It is also possible to reduce the risk of pattern collapse due to surface tension during drying.

[0003] For example, in the substrate processing apparatus described in Patent Document 1, a processing fluid is stored in a tank connected to a circulation line, and the processing fluid is kept in a liquid state by circulating through the circulation line with a capacitor inserted therein. A connection line branching from the circulation line is connected to a processing chamber, and the processing fluid is converted from a liquid to a supercritical state by heating from a heater provided in this flow path, and is supplied to the processing chamber. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2022-132400 Summary of the Invention [Problem to be solved by the invention]

[0005] In the above-described conventional substrate processing apparatus, the following problem remains to be solved in order to further reduce the risk of pattern collapse. Specifically, according to the findings of the present inventors, in a processing mode in which a supercritical processing fluid is supplied to a processing chamber housing a substrate as described above, a phenomenon that can cause pattern collapse may occur immediately after the supply of the processing fluid begins. Specifically, a sudden inflow of high-pressure processing fluid into a processing chamber at atmospheric pressure or a low pressure close to atmospheric pressure causes a temperature drop of the processing fluid due to adiabatic expansion. This may cause a partial phase change of the processing fluid from the supercritical state to a liquid or solid. If this liquefied or solidified processing fluid adheres to the substrate, it may result in particle residue on the substrate or pattern collapse.

[0006] The above-mentioned conventional techniques do not take this problem into consideration. In other words, it can be said that there is still room for improvement in the above-mentioned conventional techniques in terms of the objective of processing substrates well without causing problems such as particle adhesion and pattern collapse.

[0007] The present invention has been made in view of the above-mentioned problems, and aims to reduce processing defects such as particle adhesion and pattern collapse that may occur due to a temperature drop when the supercritical processing fluid is introduced into a processing chamber in a technology for processing a substrate with a supercritical processing fluid. [Means for solving the problem]

[0008] According to one aspect of the present invention, there is provided a substrate processing apparatus for processing a substrate with a supercritical processing fluid, the apparatus comprising: a processing chamber having an internal space capable of accommodating the substrate; a first supply unit for supplying the processing fluid as a gas pressurized to a first pressure lower than the critical pressure; a second supply unit for supplying the processing fluid at a second pressure higher than the critical pressure; an inlet flow path communicating with the internal space for introducing the processing fluid into the internal space; a first pipe connecting the first supply unit to the inlet flow path via a first valve; a second pipe connecting the second supply unit to the inlet flow path via a second valve; and a control unit controlling the first valve and the second valve to selectively introduce the processing fluid at the first pressure or the processing fluid at the second pressure into the internal space. Here, the second supply unit has a reservoir for storing the liquid processing fluid, and a pressurizer inserted in the second pipe extending from the reservoir to the second valve for pressurizing the processing fluid to the second pressure and delivering it.

[0009] In the invention configured as described above, a processing fluid at a relatively low first pressure and a processing fluid at a higher second pressure can be supplied to the processing chamber. 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 processing fluid at the second pressure exceeds the critical pressure and can be supplied to the processing chamber in a supercritical state by setting the temperature.

[0010] As in the above-described conventional technology, when a high-pressure processing fluid exceeding the critical pressure is directly introduced into a processing chamber whose internal pressure is approximately atmospheric pressure, there is a risk of processing defects due to partial liquefaction or solidification of the processing fluid. In contrast, in the present invention, for example, the internal space of the processing chamber is first filled with processing fluid from a first supply unit, thereby raising the internal space to an intermediate first pressure, and then the processing fluid in a supercritical state can be introduced from that state. Therefore, the temperature drop due to adiabatic expansion is more limited, making it possible to solve the problems of the conventional technology. [Effects of the Invention]

[0011] As described above, according to the present invention, the pressure in the internal space of the processing chamber can be increased to an intermediate first pressure before introducing the processing fluid in a supercritical state at the second pressure. By introducing the processing fluid in two stages in this manner, a rapid temperature drop of the processing fluid due to adiabatic expansion can be suppressed, and processing defects such as particle adhesion and pattern collapse due to partial liquefaction or solidification of the processing fluid can be prevented. [Brief explanation of the drawings]

[0012] [Figure 1] 1 is a diagram showing a schematic configuration of a substrate processing system equipped with an embodiment of a substrate processing apparatus according to the present invention; [Figure 2] 1 is a side view showing the overall configuration of a wet treatment apparatus. [Figure 3] 4A and 4B are diagrams for explaining the operation of the wet treatment apparatus. [Figure 4] FIG. 1 is a side view showing the configuration of a supercritical processing apparatus. [Figure 5] FIG. 2 is a diagram showing details of supply and discharge paths of processing fluids. [Figure 6] 1 is a flowchart showing a process executed by a supercritical processing apparatus. [Figure 7] 1A and 1B are diagrams showing pressure changes in a processing chamber and a storage tank. [Figure 8] 10A and 10B are diagrams illustrating the open and closed states of the valves during standby operation. [Figure 9] 10A and 10B are diagrams showing the open and closed states of the valve when gas is introduced. [Figure 10] FIG. 10 is a diagram showing the open and closed states of the valve when introducing a supercritical processing fluid. [Figure 11] 10A and 10B are diagrams illustrating the open and closed states of the valves when the processing fluid is replenished. [Figure 12] FIG. 1 is a phase diagram of carbon dioxide as a process fluid. DETAILED DESCRIPTION OF THE INVENTION

[0013] 1 is a diagram showing the schematic configuration of a substrate processing system equipped with one embodiment of a substrate processing apparatus according to the present invention. This substrate processing system 1 is a processing system for wet-processing various substrates, such as semiconductor wafers, by supplying a processing liquid to the upper surface of the substrate and then drying the substrate, and has a system configuration suitable for carrying out a substrate processing method according to the present invention. The substrate processing system 1 mainly comprises a wet-processing apparatus 2, a substrate transfer apparatus 3, a supercritical processing apparatus 4, and a control apparatus 9.

[0014] The wet processing device 2 receives a substrate to be processed and performs a predetermined wet processing. The type of processing is not particularly limited. Wet processing includes development processing, cleaning processing, etc., and after the development processing, etc., a puddle of an organic solvent such as IPA liquid is created on the pattern-forming surface of the substrate. The substrate transport device 3 transports the substrate from the wet processing device 2 while maintaining the puddle state, and transports it into the supercritical processing device 4. The supercritical processing device 4 corresponds to the substrate processing device according to the present invention, and performs a drying process (supercritical drying process) on the transported substrate using a processing fluid in a supercritical state. These are installed in a clean room. Therefore, the substrate transport device 3 transports the substrate in the air atmosphere and at atmospheric pressure.

[0015] The control device 9 controls the operation of each of these devices to achieve predetermined processing. For this purpose, the control device 9 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 users and external devices. The operations of the devices described below are achieved by the CPU 91 executing control programs written in advance in the storage 93 and causing each part of the device to perform a predetermined operation.

[0016] When the CPU 91 executes a predetermined control program, functional blocks such as a wet processing control unit 95 that controls the operation of the wet processing apparatus 2, a transport control unit 96 that controls the operation of the substrate transport apparatus 3, and a supercritical processing control unit 97 that controls the operation of the supercritical processing apparatus 4 are realized in software in the control device 9. Note that at least a part of each of these functional blocks may be configured by dedicated hardware.

[0017] The "substrate" in this embodiment can be any of a variety of substrates, including 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. The following description will be given with reference to the drawings, taking as an example a substrate processing apparatus used primarily for processing disc-shaped semiconductor wafers. However, the present invention can be similarly applied to processing the various substrates exemplified above. Various substrate shapes can also be used.

[0018] In the following description, a substrate having a pattern formed on only one main surface will be used as an example. Here, the main surface on which a pattern or the like is formed will be referred to as the "front surface," and the opposite main surface on which no pattern is formed will be referred to as the "rear surface." Furthermore, the main surface of the substrate facing downward will be referred to as the "bottom surface," and the main surface of the substrate facing upward will be referred to as the "top surface." In the following description, the top surface will be referred to as the front surface.

[0019] 2 and 3 are diagrams showing an example of the configuration of a wet-processing apparatus. More specifically, FIG. 2 is a side view showing the overall configuration of the wet-processing apparatus, and FIG. 3 is a diagram for explaining the operation of the wet-processing apparatus. This wet-processing apparatus 2 is an apparatus that processes a substrate S by supplying a processing liquid to the upper surface of the substrate. The operation of the wet-processing apparatus 2 is controlled by a wet-processing control unit 95 of the control device 9.

[0020] The wet processing apparatus 2 supplies a processing liquid to the surface (pattern formation surface) Sa of the substrate S to perform wet processing such as surface processing and cleaning of the substrate S. For this purpose, the wet processing apparatus 2 includes a substrate holding unit 21, a splash guard 22, and processing liquid supply units 23 and 24 inside a processing chamber 200. The operations of these units are controlled by a wet processing control unit 95 provided in the control device 9. The substrate holding unit 21 has a disk-shaped spin chuck 211 having approximately the same diameter as the substrate S, and a plurality of chuck pins 212 are provided on the periphery of the spin chuck 211. The chuck pins 212 abut against the periphery of the substrate S to support the substrate S, allowing the spin chuck 211 to hold the substrate S in a horizontal position while spaced apart from its upper surface.

[0021] The spin chuck 211 is supported by a rotation support shaft 213 extending downward from the center of its lower surface so that its upper surface is horizontal. The rotation support shaft 213 is rotatably supported by a rotation mechanism 214 attached to the bottom of the processing chamber 200. The rotation mechanism 214 has a built-in rotation motor (not shown), and when the rotation motor rotates in response to a control command from the control device 9, the spin chuck 211 directly connected to the rotation support shaft 213 rotates around the rotation axis AX indicated by the dashed dotted line. In FIG. 2, the up-down direction is the vertical direction. As a result, the substrate S is rotated around the rotation axis AX while remaining in a horizontal position.

[0022] A splash guard 22 is provided to surround the substrate holding part 21 from the side. The splash guard 22 has a generally cylindrical cup 221 provided to cover the peripheral part of the spin chuck 211, and a liquid receiving part 222 provided below the outer periphery of the cup 221. The cup 221 moves up and down in response to a control command from the control device 9. The cup 221 moves up and down between a lower position where the upper end of the cup 221 is lowered below the peripheral part of the substrate S held by the spin chuck 211 as shown in FIG. 2, and an upper position where the upper end of the cup 221 is located above the peripheral part of the substrate S as shown in FIG. 3.

[0023] 2, when the cup 221 is in the lower position, the substrate S held by the spin chuck 211 is exposed to the outside of the cup 221. This prevents the cup 221 from becoming an obstacle when, for example, the substrate S is loaded onto or unloaded from the spin chuck 211.

[0024] 3, when the cup 221 is in the upper position, it surrounds the peripheral edge of the substrate S held by the spin chuck 211. This prevents the processing liquid shaken off from the peripheral edge of the substrate S during liquid supply, which will be described later, from scattering inside the chamber 200, making it possible to reliably collect the processing liquid. That is, droplets of the processing liquid shaken off from the peripheral edge of the substrate S as the substrate S rotates adhere to the inner wall of the cup 221 and flow downward, and are collected by the liquid receiving portion 222 arranged below the cup 221. In order to collect multiple processing liquids individually, multiple stages of cups may be provided concentrically.

[0025] The processing liquid supply unit 23 has a structure in which a nozzle 234 is attached to the tip of an arm 233 that extends horizontally from a pivotal support shaft 232 that is rotatably provided on a base 231 fixed to the processing chamber 200. The pivotal support shaft 232 rotates in response to a control command from the control device 9, causing the arm 233 to swing, and the nozzle 234 at the tip of the arm 233 moves between a retracted position retracted laterally from above the substrate S as shown in FIG. 2 and a processing position above the substrate S as shown in FIG.

[0026] The nozzle 234 is connected to a processing liquid supply source 238, and when an appropriate processing liquid is delivered from the processing liquid supply source 238, the processing liquid is ejected from the nozzle 234 toward the substrate S. As shown in FIG. 2B , the spin chuck 211 rotates at a relatively slow speed to rotate the substrate S, and a processing liquid L1 is supplied from the nozzle 234 positioned above the center of rotation of the substrate S, thereby processing the surface Sa of the substrate S with the processing liquid L1. The processing liquid L1 can be a liquid having various functions, such as a developer, an etching liquid, a cleaning liquid, or a rinse liquid, and the composition thereof is optional. Furthermore, processing may be performed using a combination of multiple types of processing liquids.

[0027] The other processing liquid supply unit 24 also has a configuration corresponding to that of the above-described first processing liquid supply unit 23. That is, the second processing liquid supply unit 24 has a base 241, a pivot shaft 242, an arm 243, a nozzle 244, etc., and these configurations are equivalent to those corresponding to those in the first processing liquid supply unit 23. The pivot shaft 242 rotates in response to a control command from the control device 9, causing the arm 243 to swing. The nozzle 244 at the tip of the arm 243 supplies the processing liquid to the surface Sa of the substrate S.

[0028] In this embodiment, the second processing liquid supply unit 24 is used for the purpose of forming a liquid film for preventing drying on the substrate S after wet processing. That is, the substrate S after wet processing is transported to the supercritical processing device 4 and subjected to supercritical drying processing, but in order to prevent the surface of the substrate S from being exposed and oxidized during transportation or the fine pattern formed on the surface from collapsing, the substrate S is transported with its surface covered with a puddle-shaped liquid film.

[0029] The liquid that constitutes the liquid film is a substance with a surface tension lower than that of water, which is the main component of the processing liquid used in the cleaning process, such as an organic solvent such as isopropyl alcohol (IPA) or acetone, which is supplied from an organic solvent supply source 248.

[0030] Here, two sets of processing liquid supply units are provided in the wet processing apparatus 2, but the number of processing liquid supply units provided, their structures, and functions are not limited to this. For example, only one set of processing liquid supply units may be provided, or three or more sets may be provided. Furthermore, one processing liquid supply unit may be provided with multiple nozzles. For example, multiple nozzles may be provided at the tip of one arm. Furthermore, in addition to the above-mentioned mode in which the processing liquid is discharged while the nozzle is positioned at a predetermined position, for example, a mode in which the nozzle discharges the processing liquid while scanning and moving along the surface Sa of the substrate S may also be included.

[0031] Returning to FIG. 1, the explanation will be continued. The substrate transfer device 3 is provided with a transfer robot 30 having a hand 31 attached to the tip of an extendable and rotatable arm. The hand 31 can support the substrate by partially abutting against the underside of the substrate, and as shown by the dotted line in FIG. 1, is movable toward and away from both the wet treatment device 2 and the supercritical treatment device 4. This allows substrates to be loaded into and unloaded from both the wet treatment device 2 and the supercritical treatment device 4. The operation of the transfer robot 30 is controlled by a transfer control unit 96 of the control device 9. There are many well-known technologies for this type of transfer robot, and any of these can be appropriately selected and used in this embodiment, so a detailed description will be omitted.

[0032] 4 is a side view showing the configuration of a supercritical processing apparatus. The supercritical processing apparatus 4 corresponds to a first embodiment of the substrate processing apparatus according to the present invention, and is an apparatus that performs a drying process using a processing fluid in a supercritical state on a substrate S after wet processing. More specifically, the supercritical processing apparatus 4 is an apparatus that receives the substrate S after wet processing, replaces the liquid remaining on the substrate S with the processing fluid in a supercritical state, and then discharges the processing fluid, thereby finally bringing the substrate S to a dry state.

[0033] 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 unit that performs the supercritical drying process. The transfer unit 43 receives the substrate S after wet processing that is transported by the substrate transport device 3 and transports it into the processing unit 41, and also transfers the processed substrate S from the processing unit 41 to an external transport device. The supply unit 45 supplies chemical substances, power, energy, etc. required for processing to the processing unit 41 and the transfer unit 43. These operations are controlled by the control device 9, particularly the supercritical processing control unit 97.

[0034] The processing unit 41 has a structure in which a processing chamber 412 is mounted on a base 411. The processing chamber 412 is constructed by combining several metal blocks, and its interior is hollow, constituting a processing space SP. The substrate S to be processed is loaded into the processing space SP and undergoes processing. A slit-shaped opening 421 that is elongated in the X direction is formed on the (-Y) side surface of the processing chamber 412. The processing space SP communicates with the outside space via the opening 421. The cross-sectional shape of the processing space SP is approximately the same as the opening shape of the opening 421. 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.

[0035] A lid member 413 is provided on the (-Y) side surface of the processing chamber 412 so as to close the opening 421. By closing the opening 421 of the processing chamber 412 with the lid member 413, an airtight processing container is formed. This makes it possible to process the substrate S under high pressure in the internal processing space SP. A flat support tray 415 is attached in a horizontal position to the (+Y) side surface of the lid member 413. The upper surface of the support tray 415 forms a support surface on which the substrate S can be placed. The lid member 413 is supported by a support mechanism (not shown) so as to be freely movable horizontally in the Y direction.

[0036] The lid member 413 can be moved toward and away from the processing chamber 412 by an advancing / retracting mechanism 453 provided in the supply unit 45. Specifically, the advancing / retracting mechanism 453 has a linear motion mechanism such as a linear motor, a linear motion guide, a ball screw mechanism, a solenoid, or an air cylinder. Such a linear motion mechanism moves the lid member 413 in the Y direction. The advancing / retracting mechanism 453 operates in response to a control command from the control device 9.

[0037] When the cover member 413 moves in the (-Y) direction to move away from the processing chamber 412 and the support tray 415 is pulled out from the processing space SP through the opening 421 as shown by the dotted line, access to the support tray 415 becomes possible. That is, it becomes possible to place the substrate S on the support tray 415 and to remove the substrate S placed on the support tray 415. On the other hand, when the cover member 413 moves in the (+Y) direction, the support tray 415 is accommodated in the processing space SP. When a substrate S is placed on the support tray 415, the substrate S is carried into the processing space SP together with the support tray 415.

[0038] The lid member 413 moves in the (+Y) direction to close the opening 421, thereby sealing the processing space SP. A seal member 422 is provided between the (+Y) side surface of the lid member 413 and the (-Y) side surface of the processing chamber 412, thereby maintaining the processing space SP in an airtight state. The seal member 422 is made of, for example, rubber. In addition, the lid member 413 is fixed to the processing chamber 412 by a locking mechanism (not shown). As described above, in this embodiment, the lid member 413 can be switched between a closed state (solid line) in which the lid member 413 closes the opening 421 to seal the processing space SP, and a separated state (dotted line) in which the lid member 413 is separated significantly from the opening 421 to allow the substrate S to be inserted or removed.

[0039] The processing space SP is kept airtight while the substrate S is processed within the processing space SP. In this embodiment, the fluid supply unit 457 in the supply unit 45 delivers a processing fluid, such as carbon dioxide, that is a substance suitable for supercritical processing. The processing fluid is then pressurized within the processing chamber 412 to bring it to a supercritical state. The processing fluid is supplied to the processing unit 41 in a gaseous or liquid state. Carbon dioxide is a chemical suitable for supercritical drying because it reaches a supercritical state at relatively low temperatures and pressures and has the property of dissolving organic solvents commonly used in substrate processing. The critical point at which carbon dioxide reaches a supercritical state is an atmospheric pressure (critical pressure) of 7.38 MPa and a temperature (critical temperature) of 31.1°C.

[0040] When the processing space SP is filled with the processing fluid and 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 processing fluid in the processing chamber 412. The supply unit 45 is provided with a fluid recovery part 455, and the processed fluid is recovered by the fluid recovery part 455. The fluid supply part 457 and the fluid recovery part 455 are controlled by the supercritical processing control part 97.

[0041] The processing space SP has a shape and volume that can accommodate the support tray 415 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 415 in the horizontal direction and greater than the combined height of the support tray 415 and the substrate S in the vertical direction, and a depth that can accommodate the support tray 415. In this way, the processing space SP has a shape and volume that can accommodate the support tray 415 and the substrate S. However, there is only a small gap between the support tray 415 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.

[0042] The fluid supply unit 457 supplies the processing fluid to the processing space SP further to the (+Y) side than the (+Y) side end of the substrate S. Meanwhile, the fluid recovery unit 55 discharges the processing fluid that flows through the space above the substrate S and the space below the support tray 415 in the processing space SP further to the (-Y) side than the (-Y) side end of the substrate S. As a result, laminar flows of the processing fluid from the (+Y) side to the (-Y) side are formed above the substrate S and below the support tray 415 in the processing space SP.

[0043] The supercritical processing control unit 97 of the control device 9 determines the pressure and temperature in the processing space SP based on the detection results from a detection unit (not shown), and controls the fluid supply unit 457 and the fluid recovery unit 455 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.

[0044] The transfer unit 43 is responsible for transferring the substrate S between the substrate transport device 3 and the support tray 415. For this purpose, the transfer unit 43 includes a main body 431, a lifting member 433, a base member 435, and multiple lift pins 437. The lifting member 433 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 431. A base member 435 having a substantially horizontal upper surface is attached to the top of the lifting member 433. Multiple lift pins 437 are erected upward from the upper surface of the base member 435. Each of the lift pins 437 supports the substrate S in a horizontal position from below by abutting its upper end with 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 437 whose upper ends have the same height.

[0045] The lifting member 433 can be moved up and down by a lifting mechanism 451 provided in the supply unit 45. Specifically, the lifting mechanism 451 has a linear motion mechanism such as a linear motor, a linear motion guide, a ball screw mechanism, a solenoid, or an air cylinder, and this linear motion mechanism moves the lifting member 433 in the Z direction. The lifting mechanism 451 operates in response to a control command from the control device 9.

[0046] The base member 435 moves up and down as the lifting member 433 moves up and down, and the plurality of lift pins 437 move up and down integrally therewith. This allows the transfer of the substrate S between the transfer unit 43 and the support tray 415. More specifically, as shown by the dotted line in FIG. 4 , the substrate S is transferred with the support tray 415 pulled out to the outside of the chamber. For this purpose, the support tray 415 is provided with through holes 419 for inserting the lift pins 437. When the base member 435 moves up, the upper ends of the lift pins 437 pass through the through holes 419 and reach a position higher than the upper surface of the support tray 415. In this state, the substrate S transferred by the transfer robot 30 is transferred from the hand 31 of the transfer robot 30 to the lift pins 437. When the lift pins 437 move down, the substrate S is transferred from the lift pins 437 to the support tray 415. The substrate S can be removed by reversing the above procedure.

[0047] Next, a more detailed description will be given of 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. In the above, it has been simply explained that the processing fluid is supplied from the fluid supply unit 457 to the processing chamber 412 and recovered from the processing chamber 412 to the fluid recovery unit 455. In an actual device, the fluid supply unit 457 and the fluid recovery unit 455 have the following configurations.

[0048] FIG. 5 is a diagram showing the details of the supply and discharge paths of the processing fluid. Note that in FIG. 5, for convenience of illustration, the orientation of the processing chamber 412 is opposite to that in FIG. 4. That is, in FIG. 4, the processing fluid is introduced into the processing chamber 412 from the right side of the page and discharged to the left side of the page. On the other hand, in FIG. 5, the processing fluid is introduced into the processing chamber 412 from the left side of the page and discharged to the right side of the page, which is the opposite of the above. That is, the processing chamber 412 in FIG. 5 shows the side opposite to that of the processing chamber 412 in FIG. 4.

[0049] First, we will explain the detailed structure of fluid supply unit 457. Fluid supply unit 457 mainly comprises a fluid supply source 700, a refinement unit 710, a supply unit 720, and piping groups 730 and 740 that connect these. These operate in response to control commands from supercritical process control unit 97.

[0050] The fluid supply source 700 outputs a substance (carbon dioxide in this embodiment) that acts as a processing fluid in supercritical processing as needed. The fluid supply source 700 may be provided as a part of the substrate processing system 1 and may be configured as a container, such as a cylinder, that stores the substance. Alternatively, the fluid supply source 700 may be an external supply source provided separately from the substrate processing system 1.

[0051] A pipe 731, which is part of a pipe group 730, is connected to the fluid supply source 700. The processing fluid delivered from the fluid supply source 700 passes through the pipe 731 in a rightward direction in FIG. 1. Valves V70, V71, a purifier 711, a filter 712, a condenser 713, and a valve V72 are inserted in this order in the processing fluid flow direction of the pipe 731. The valve V70 is, for example, a pressure regulating valve that has the function of adjusting the pressure of the processing fluid passed through the pipe 731. The other valves V71, V72 are on-off valves that switch the flow of the fluid on and off.

[0052] Valve V70 circulates the processing fluid at a pressure specified by a control command from the supercritical processing control unit 97 through pipe 731. Purifier 711 and filter 712 remove impurities from the processing fluid to improve its purity. Condenser 713 condenses the processing fluid sent out as a gas from fluid supply source 700. When valves V71 and V72 are opened, the processing fluid is output from pipe 731.

[0053] Pipe 731 merges with pipe 735, which is connected to a storage tank 717 (described later), on the output side of valve V72. Pipe 732 after the merger is equipped with a condenser 714, a pressure pump 715, and a filter 716. Condenser 714 is provided to more reliably maintain the processing fluid in a liquid state. Pressure pump 715 pressurizes the liquid processing fluid and sends it out. Filter 716 removes impurities from the processing fluid.

[0054] Pipe 732 branches into two pipes 733 and 734 on the output side of filter 716. Pipe 733 is connected to the top of storage tank 717, and has valve V74, which is an on-off valve, inserted midway through. Also, pipe 734 has valve V75, which is an on-off valve, inserted therein.

[0055] The storage tank 717 is a high-pressure vessel capable of storing pressurized liquid processing fluid. A level sensor 718 is provided in the storage tank 717 to control the liquid level. Therefore, the internal space of the storage tank 717 is not liquid-tight, and the vaporized processing fluid is stored in the space above the liquid level under pressure similar to that of the liquid. The storage tank 717 is also equipped with a heater 719, which can heat the processing fluid in the tank in response to a control command from the supercritical processing control unit 97.

[0056] A pipe 735 is connected to the bottom of the storage tank 717, and the pipe 735 merges with the pipe 731 and is connected to the pipe 732. When a valve V73, which is an on-off valve inserted in the pipe 735, is opened, the liquid processing fluid in the storage tank 717 flows into the pipe 732 via the pipe 735. If a valve V74 on the pipe 733 is also opened, a reflux path is formed that refluxes the processing fluid from the storage tank 717 via the pipes 735, 732, and 733 back to the storage tank 717. If the pressure pump 715 pressurizes the processing fluid while circulating it through this reflux path, the pressure of the processing fluid can be increased in stages. Finally, the processing fluid is stored in the storage tank 717 at a pressure increased to a pressure designated by a control command from the supercritical processing control unit 97.

[0057] An output pipe 736 is connected to the top of the storage tank 717, and the pipe 736 merges with the pipe 734 via the valve V76, which is an on-off valve. The gaseous treatment fluid that fills the upper part of the internal space of the storage tank 717 is output from the pipe 736. The gaseous treatment fluid flows into the pipe 741 after the pipes 734 and 736 are merged, and when the valve V76 is opened, the gaseous treatment fluid flows into the pipe 741, and when the valve V75 is opened, the liquid treatment fluid flows into the pipe 741.

[0058] In this way, the purification unit 710 of the fluid supply section 457 has the function of removing impurities from the processing fluid supplied from the fluid supply source 700 and selectively outputting the processing fluid in the phase required for subsequent processing, specifically the gas phase and liquid phase.

[0059] Pipe 741 is part of a group of pipes 740 that constitutes an introduction flow path for introducing a processing fluid from purification unit 710 to processing chamber 412. Pipe 741 branches into two pipes 743 and 744, each of which is provided with filters 721 and 722. These pipes 743 and 744 merge to form pipe 745, which further branches into two pipes 747 and 748.

[0060] A flow meter 723, a heater 725, and a valve V78 which is an on-off valve are inserted in this order into the pipe 742 along the flow direction of the processing fluid (toward the right in the figure), and the pipe 742 is ultimately connected to the processing chamber 412. More specifically, the pipe 742 communicates with the internal space SP above the support tray 415 (FIG. 4) that supports the substrate S. Meanwhile, a flow meter 723, a heater 726, and a valve V79 which is an on-off valve are inserted in this order into the pipe 743 along the flow direction of the processing fluid. The pipe 742 communicates with the internal space SP of the processing chamber 412 below the support tray 415 (FIG. 4) that supports the substrate S. As a result, in the internal space SP, the processing fluid is supplied to the spaces above and below the substrate S placed on the support tray 415.

[0061] Flow meters 723 and 725 measure the flow rates of the processing fluids at their respective positions and transmit the results to the supercritical processing control unit 97. Heaters 725 and 726 heat the processing fluids to a predetermined temperature in response to control commands from the supercritical processing control unit 97. Filters 727 and 728 finally remove impurities from the processing fluids introduced into the processing chamber 412.

[0062] In this manner, the fluid supply unit 457 can supply a processing fluid that has been purified and whose temperature and pressure have been adjusted to predetermined target values ​​to the processing chamber 412. The supply sequence of the processing fluid from the fluid supply unit 457 to the processing chamber 412 will be described in detail later.

[0063] The processing fluid supplied to processing chamber 412 is delivered from storage tank 717, which stores processing fluid pressurized by pressure pump 715. Therefore, the pressure of the processing fluid delivered from fluid supply source 700 may be lower than the pressure required for processing. If fluid supply source 700 can stably deliver processing fluid at a pressure appropriate for processing, the gas-phase processing fluid may be supplied directly from fluid supply source 700 via piping 737, as shown by the dotted line in Figure 5, rather than being taken from storage tank 717. Alternatively, pressure-regulated processing fluid may be supplied from the output side of valve V70.

[0064] Next, we will explain the detailed structure of the fluid recovery unit 455. The fluid supply unit 455 mainly comprises a high-pressure exhaust tank 505, a low-pressure exhaust tank 508, and a group of pipes 530 connecting these. These operate in response to control commands from the supercritical process control unit 97.

[0065] A pipe 531, which is part of a pipe group 530, is connected to the upper part of the processing chamber 412. Meanwhile, a pipe 532 is connected to the lower part of the processing chamber 412. These pipes 531, 532 respectively discharge the processing fluid that has flowed above and below the support tray 415 in the internal space SP from the processing chamber 412 to the outside. A pressure gauge 503 is provided on the pipe 531.

[0066] A flow meter 501 and a valve V51, which is an on-off valve, are inserted in this order into pipe 531 along the flow direction of the processing fluid. On the other hand, a flow meter 502 and a valve V52, which is an on-off valve, are inserted in this order into pipe 532 along the flow direction of the processing fluid. Pipes 531 and 532 join at the output sides of valves V51 and V52. After joining, pipe 533 has valve V53, which is a pressure adjustment valve, and valve V54, which is an on-off valve, inserted therein.

[0067] The pipe 533 is connected to a high-pressure exhaust tank 505, and the processing fluid discharged from the processing chamber 412 is stored in the high-pressure exhaust tank 505 via the pipe 533. The high-pressure exhaust tank 505 is provided with a heater 506, which maintains the temperature of the processing fluid stored therein at an appropriate level.

[0068] A pipe 544 is connected to the top of the high-pressure exhaust tank 505, and a valve V55 which is an on-off valve, a valve V56 which is a pressure adjusting valve, and a heater 507 are inserted in the pipe 544, and the pipe 544 is finally connected to a low-pressure exhaust tank 508. Therefore, a processing fluid as a gas whose pressure and temperature have been appropriately adjusted flows into the low-pressure exhaust tank 508. The processing fluid in the low-pressure exhaust tank 508 is finally recovered by an external recovery device (not shown) via the pipe 545. A pressure sensor 510 is provided in the pipe 545 to detect the pressure of the gas discharged to the outside.

[0069] Furthermore, a pipe 546 is connected to the bottom of the high-pressure exhaust tank 505, while a pipe 547 is connected to the bottom of the low-pressure exhaust tank 508. These pipes join to form pipe 548, to which a valve V57, which is an on-off valve, is connected. When valve V57 is opened, the liquid treatment fluid stored in the high-pressure exhaust tank 505 and the low-pressure exhaust tank 508 is discharged to an external recovery device.

[0070] The operation of the supercritical processing apparatus 4 configured as described above will be described with reference to Figures 6 and 7. The supercritical processing apparatus 4 performs a process of drying the substrate S after wet processing using a processing fluid in a supercritical state, i.e., a supercritical drying process. This process is realized by the CPU 91 of the control unit 9 executing a prepared control program and controlling each part of the apparatus.

[0071] Fig. 6 is a flowchart showing the process performed by the supercritical processing apparatus. Fig. 7 is a diagram showing the pressure changes in the processing chamber and storage tank during this process. The fluid supply unit 457 supplies gaseous and liquid processing fluids to the processing chamber 412 from a storage tank 717 that stores the processing fluids. Therefore, the pressure in the processing space SP of the processing chamber 412 (hereinafter referred to as "chamber internal pressure") and the pressure in the internal space of the storage tank 717 (hereinafter referred to as "tank internal pressure") change as the process progresses.

[0072] First, the substrate transfer device 3 and the supercritical processing device 4 work together to load 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 that has undergone the liquid film formation process in the wet processing device 2, and places the substrate S on the support tray 415 that has been pulled out of the processing chamber 412. More precisely, the substrate S is first transferred from the hand 31 of the transfer robot 30 to the lift pins 437 of the supercritical processing device 4, and then the substrate S is transferred from the lift pins 437 to the support tray 415.

[0073] The support tray 415 on which the substrate S is placed is housed in the processing chamber 412. The lid member 413 closes the opening 421 of the processing chamber 412, thereby sealing the processing space SP inside the processing chamber 412. In this way, the loading of the substrate S is completed. Since the processing chamber 412 is opened to the atmosphere in order to load the substrate S, the internal pressure of the processing chamber 412 is atmospheric pressure Pa in the initial state, as shown in the upper part of FIG.

[0074] While the substrate S is being transferred in this manner, a predetermined standby operation is performed in the fluid supply unit 457 (step S102). As will be described in detail later, the standby operation is an operation for preparing a required amount of processing fluid at a temperature and pressure suitable for use in subsequent processing in the fluid supply unit 457. As will be described later, in this embodiment, gaseous carbon dioxide at a temperature of 20°C and a pressure of 6 MPa and carbon dioxide heated to a temperature of 20°C and a pressure of 11 MPa to become supercritical are used for processing.

[0075] After the substrate S is loaded, the fluid supply unit 457 starts to introduce a gaseous processing fluid (step S103; time T1), which gradually increases the pressure inside the chamber. When the pressure inside the chamber increases to a predetermined first pressure P1 (step S104; time T2), the fluid supply unit 457 supplies a supercritical processing fluid, instead of the gas, into the processing chamber 412 (step S105; time T3).

[0076] As a result, the processing space SP of the processing chamber 412 is filled with the processing fluid in a supercritical state, and the chamber internal pressure is maintained at a constant second pressure P2 that is greater than the first pressure P1 and the critical pressure of the processing fluid (times T4 to T5). During this time, the liquid remaining on the substrate S is replaced by the supercritical processing fluid, dissolved in the processing fluid, and removed from the surface of the substrate S.

[0077] After a predetermined time has elapsed while the chamber internal pressure is maintained at approximately pressure P2 (step S106), discharge of the processing fluid from the processing chamber 412 begins (step S107; time T5), thereby depressurizing the processing space SP. After time T7, when the chamber internal pressure has decreased to near atmospheric pressure Pa, the transfer robot 30 unloads the substrate S (step S108), completing the processing of one substrate S. If there is another substrate to be processed, the process returns to step S101 (step S109), and the above processing is repeated.

[0078] 7, as the processing fluid stored in the storage tank 717 is consumed, the pressure inside the tank gradually decreases. To restore this pressure, a standby operation is performed to replenish the storage tank 717 with pressurized processing fluid (step S111). The standby operation can be performed after time T6, when the supply of processing fluid from the storage tank 717 to the processing chamber 412 is stopped. Therefore, as shown in FIG. 7, the standby operation can be started while the processing chamber 412 is being depressurized.

[0079] When performing supercritical drying processing on a substrate S, it is desirable to increase the tank internal pressure to a pressure that is approximately the same as or slightly higher than the first pressure P1 during the standby operation so that the chamber internal pressure can be increased to the first pressure P1 in step S103 of the processing.

[0080] Figures 8 to 11 show the state of valves at each stage of processing. In these figures, the flow of processing fluid flowing in a gaseous state through the flow path is indicated by a thick dotted arrow, and the flow of processing fluid in a liquid state is indicated by a thick solid arrow. In particular, in Figure 10, the flow of processing fluid in a supercritical state is indicated by a hollow arrow with a thick dotted arrow.

[0081] Furthermore, in these figures, among the valves that are on-off valves, a white circle (◯) next to the symbol and a single underline on the symbol indicates that the valve is open. On the other hand, a black circle (●) next to the symbol and a double underline on the symbol indicates that the valve is closed. Valves that do not have these marks do not directly affect the processing described below, and therefore their open / closed state is not particularly limited here.

[0082] Figure 8 shows the open and closed states of the valves during standby operation. During standby operation, the processing fluid output from the fluid supply source 700 is pressurized by the pressure pump 715 and allowed to flow into the storage tank 717, thereby increasing the tank internal pressure to a target value. For this purpose, as shown in Figure 8, valves V71, V72, and V74 are opened, while valves V73, V75, and V76 are closed.

[0083] Therefore, the processing fluid output from the fluid supply source 700 and having its pressure adjusted by the valve V70 is pressurized to a predetermined pressure by the pressure pump 715 and stored in the storage tank 717. The amount of liquid in the tank is monitored by the level sensor 718, and the supply of the processing fluid continues until a predetermined amount of liquid at a predetermined pressure has accumulated. In addition, the temperature of the processing fluid in the tank is adjusted by the heater 719.

[0084] Thus, during the standby period when no processing fluid is supplied from the storage tank 717 to the processing chamber 412 (before time T1 and after time T6 in FIG. 7), a process for maintaining the liquid volume, pressure, and temperature in the tank at predetermined values ​​is performed as a standby operation. The target pressure value is the first pressure P1 or a pressure slightly higher than this, which is 6 MPa in this embodiment. The target temperature is 20°C in this embodiment. The target liquid volume value is set to an amount that is sufficient to supply the processing fluid to the processing chamber 412 in the supercritical drying process described above.

[0085] 9 shows the open / closed states of the valves during gas introduction. In step S103 (times T1 to T2), a gaseous processing fluid is introduced into the processing chamber 412, increasing the pressure inside the chamber. During this pressure increase stage, valves V72, V74, etc. on the path supplying the processing fluid to the storage tank 717 are closed to block the supply path, while valve V76 on the pipe 736 connected to the top of the tank and valves V77, etc. on the pipe group 740 are opened. Therefore, the gaseous processing fluid filling the interior of the storage tank 717 above the liquid level is supplied to the processing chamber 412 via the pipe group 740.

[0086] 7 increases from atmospheric pressure Pa to a first pressure P1. At the same time, the tank internal pressure, shown in the lower part of FIG. 7, begins to decrease at time T1 when the output of the processing fluid begins. However, the decrease in the tank internal pressure gradually becomes gentler as the heater 719 operates to compensate for the temperature drop in the tank caused by the sudden pressure drop.

[0087] Meanwhile, in the fluid recovery unit 455, the valves V51 to V57 provided in the piping group 530 are opened to form a discharge flow path for the processing fluid. Therefore, a certain amount of processing fluid is discharged even during the pressurization stage. As a result, the air, liquid, impurities, etc. remaining in the processing chamber 412 are also discharged to the outside of the chamber.

[0088] The chamber pressure can be indirectly measured by a pressure gauge 503 installed in the pipe 531 on the exhaust flow path communicating with the processing space SP. Therefore, in step S106, the chamber pressure can be determined using the measurement results of the pressure gauge 503. However, if the correlation between the amount of processing fluid sent into the processing chamber 412 and the chamber pressure is determined in advance, it becomes possible to predict the time it will take for the chamber pressure to reach the target value. Therefore, in an actual apparatus, it is possible to omit actual measurement of the chamber pressure by determining the length of time for which the valve V76, which controls the gas discharge, is open. That is, as in step S106, a determination based on the elapsed time can be adopted.

[0089] 10 shows the open / closed states of the valves when introducing the supercritical processing fluid. In order to supply the processing fluid in a supercritical state to the processing chamber 412 in step S105 (times T3 to T5), the temperature of the processing fluid being fed must exceed the critical temperature, and the pressure of the processing fluid must exceed the critical pressure. Therefore, valve V76 is closed to stop the gas from being sent out, and instead valves V73 and V75 are opened to send the processing fluid liquid stored in storage tank 717 toward the processing chamber 412.

[0090] At this time, a pressure pump 715 is provided in the flow path of the processing fluid, and the processing fluid is sent through the piping group 740 at a pressure increased to a pressure exceeding the critical pressure (second pressure P2 in this embodiment). Heaters 725 and 726 provided on the flow path heat the processing fluid to a temperature above the critical temperature, so that the processing fluid flows into the processing chamber 412 in a supercritical state. In this way, the processing space SP is filled with the processing fluid in a supercritical state.

[0091] Even in this case, the discharge flow path is open to discharge a small amount of processing fluid from the processing chamber 412. Therefore, the liquid and the like that have been replaced by the processing fluid and separated from the substrate S are discharged to the outside together with the processing fluid, preventing them from re-adhering to the substrate S. The pressure inside the tank drops sharply as the liquid starts to be discharged, but the degree of pressure drop is reduced by heating by the heater 719.

[0092] At time T5, the flow rate of the processing fluid output from the pressure pump 715 is reduced, causing the chamber pressure to begin to decrease. To prevent a rapid decrease in pressure from liquefying or solidifying the processing fluid and damaging the substrate S, the pressure reduction rate is adjusted so that the processing fluid changes phase directly from the supercritical state to the gas phase. Once the chamber pressure has sufficiently decreased (e.g., below the critical pressure) and the risk of liquefaction and solidification is eliminated, the supply of processing fluid to the processing chamber 412 can be stopped and the exhaust flow rate increased to exhaust any remaining processing fluid, thereby rapidly reducing the pressure.

[0093] 10, a sequence can be adopted in which valve V75 is closed at time T6 and valve V74 is opened instead. In this case, the processing fluid delivered from pressure pump 715 is returned to storage tank 717, thereby suppressing a decrease in the tank internal pressure. Furthermore, after delivery of processing fluid to processing chamber 412 stops, processing fluid can be replenished from fluid supply source 700 to storage tank 717.

[0094] 11 shows the open and closed states of the valves during replenishment of the processing fluid. Even if the depressurization process is ongoing in the fluid recovery unit 455, after the supply of processing fluid to the processing chamber 412 stops, that is, after time T6 when valve V75 is closed, the supply of processing fluid from the fluid supply source 700 can be resumed and the processing fluid can be supplied to the storage tank 717 via the pressure pump 715. This allows the internal pressure and liquid volume of the tank to be restored, allowing the processing of the next substrate to be prepared.

[0095] 8 and 11, the operation of the fluid supply unit 457 at this time is the same as the standby operation. That is, the standby operation by the fluid supply unit 457 can be performed in parallel with the depressurization operation in the fluid recovery unit 455 and the subsequent processing such as carrying out the substrate S by the transfer robot 31. Therefore, after the processed substrate is carried out, a new substrate can be quickly received and processed.

[0096] As described above, in the supercritical drying process of this embodiment, first, gaseous carbon dioxide (20°C, 6 MPa) is introduced as the processing fluid into the processing chamber 412 to increase the pressure in the processing space SP, and then liquid carbon dioxide (20°C, 11 MPa) is heated to become supercritical and introduced into the processing chamber 412. The reason for supplying the processing fluid in two stages in this manner will be explained below.

[0097] 12 is a phase diagram of carbon dioxide, which is the processing fluid. Point C in the diagram represents the critical point of carbon dioxide, where the critical pressure Pc of carbon dioxide is 7.38 MPa and the critical temperature Tc is 31.1°C. Point A represents the state of the processing fluid introduced in the initial stage of the supercritical drying process. As described above, the processing fluid at this time has a pressure (first pressure P1) of 6 MPa and a temperature of 20°C, and is introduced into the processing chamber 412 as a gas.

[0098] As can be seen from the phase diagram, point A, which is determined by this pressure and temperature, is located at the boundary between the liquid and gas phases, i.e., slightly inside the gas phase region from the gas-liquid equilibrium state. In other words, the pressure at this point is lower than the critical temperature Tc and slightly lower than the maximum pressure that the gas-phase processing fluid can assume. In other words, the first pressure P1 is set to satisfy these conditions. It is more preferable that point A be as close to the critical point C as possible without causing the processing fluid to liquefy or become supercritical.

[0099] After the chamber internal pressure is increased to a first pressure P1, the processing fluid in a supercritical state 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 higher than the critical pressure Pc, which in this embodiment is 11 MPa (second pressure P2). The temperature is also set to an appropriate value above the critical temperature Tc.

[0100] The reason for this two-stage pressurization, i.e., first filling the processing chamber 412 with a gaseous processing fluid at a relatively low pressure and then introducing a processing fluid in a supercritical state at a higher pressure, is as follows: When a high-pressure supercritical processing fluid is directly introduced into a processing chamber at atmospheric pressure, as in the prior art, processing defects can occur, such as particle adhesion and pattern collapse, resulting in damage to the substrate. According to the inventors' findings, this is because when a high-pressure, high-density processing fluid flows into a low-pressure processing chamber, a portion of the processing fluid is cooled by adiabatic expansion, solidifies, or liquefies, and adheres to the substrate.

[0101] To avoid this phenomenon, in this embodiment, a gaseous processing fluid is first introduced into the processing chamber 412 to raise the chamber pressure to a pressure slightly lower than the critical pressure Pc, and then a higher-pressure supercritical processing fluid is introduced into the processing chamber 412. Increasing the chamber pressure in two stages in this manner prevents the processing fluid from liquefying and solidifying in the chamber.

[0102] Furthermore, when the gas phase processing fluid comes into contact with the liquid film of organic solvent covering the surface of the substrate S, the processing fluid dissolves in the liquid, which has the effect of reducing the surface tension of the liquid. By initially introducing the processing fluid into the processing chamber 412 as a gas, the surface tension of the liquid is reduced, thereby improving the replacement efficiency when the supercritical processing fluid is introduced.

[0103] According to experiments conducted by the inventors of the present application, when a supercritical processing fluid with a pressure of 11 MPa is directly introduced into the processing chamber 412 or when the pressure of the gas introduced in advance is 4 to 5 MPa, processing defects that damage the substrate may occur. On the other hand, when the gas pressure (first pressure P1) is set to 6 MPa, such processing defects can be effectively suppressed. Increasing the pressure actually increases the risk of the processing fluid liquefying.

[0104] When the first pressure P1 is 6 MPa and the second pressure P2 is 11 MPa, the pressure difference when the gaseous processing fluid is used to increase the pressure from atmospheric pressure Pa to the first pressure P1 is larger than the pressure difference when the supercritical processing fluid is used to increase the pressure from the first pressure P1 to the second pressure P2. In other words, the gaseous processing fluid is responsible for increasing the pressure equivalent to more than half of the pressure difference from atmospheric pressure Pa to the final target second pressure P2. This prevents liquefaction and solidification that may occur when introducing a processing fluid with a large pressure difference.

[0105] In this embodiment, the process fluid is switched between gaseous and liquid by selectively opening the valves V75 and V76, and these fluids share the same flow path through the piping group 740. This simplifies the piping configuration and reduces the intrusion of impurities due to the piping system including the valves.

[0106] As described above, in the above embodiment, the supercritical processing apparatus 4 corresponds to the "substrate processing apparatus" of the present invention, and the processing chamber 412 having the processing space SP as the "internal space" functions as the "processing chamber" of the present invention. Also, the fluid supply unit 457 functions as both the "first supply unit" and the "second supply unit" of the present invention.

[0107] More specifically, storage tank 717 functions as the "storage section" of the present invention, and pressure pump 715 functions as the "pressurizing section" of the present invention. Furthermore, pipe 736 corresponds to the "first pipe" of the present invention, and valve V76 functions as the "first valve" of the present invention. Furthermore, pipe 732 and valve V75 function as the "second pipe" and "second valve" of the present invention, respectively. Furthermore, pipe group 740 constitutes the "inlet flow path" of the present invention.

[0108] Storage tank 717 functions as a "first supply unit" of the present invention when it delivers a gaseous processing fluid via pipe 736, and functions as a "second supply unit" of the present invention when it delivers a liquid processing fluid via pipe 732. Note that, when the gaseous processing fluid is delivered from fluid supply source 700 via pipe 737 to processing chamber 412 as shown by the dotted line in Figure 5, fluid supply source 700 corresponds to the "first supply unit" of the present invention, and pipe 737 corresponds to the "first pipe."

[0109] Furthermore, the control device 9 of the above embodiment, more specifically the supercritical processing control unit 97, functions as the "control unit" of the present invention. Furthermore, the heaters 725 and 726 correspond to the "first heater" of the present invention, while the heater 719 corresponds to the "second heater" of the present invention. Furthermore, the valve V74 functions as the "third valve" of the present invention, and the pipe 733 functions as the "reflux pipe" of the present invention.

[0110] The present invention is not limited to the above-described embodiment, and various modifications other than those described above are possible without departing from the spirit of the present invention. For example, the fluid supply unit 457 in the above embodiment includes many components, such as a flow meter and a filter, that are generally provided in the flow path of the processing fluid but are not directly related to the present invention. The present invention can be realized even if these components are omitted.

[0111] Also, for example, in the above embodiment, the processing fluid is introduced into and discharged from the processing chamber 412 separately from the upper and lower sides of the support tray 415. However, this is not an essential requirement.

[0112] In the above embodiment, the gas and liquid processing fluids are extracted from a single storage tank 717, and the storage tank 717 also functions as the "first supply unit" and the "second supply unit" of the present invention. However, these may be provided as independent configurations. For example, the gas and liquid may be stored separately.

[0113] Furthermore, the various chemical substances used in the treatment of the above-described embodiments are only examples, and various substances can be used instead as long as they are consistent with the technical concept of the present invention described above.

[0114] As described above with reference to specific embodiments, in the substrate processing apparatus according to the present invention, the control unit may be configured to, for example, open a first valve to fill the internal space with a processing fluid at a first pressure, and then close the first valve and open a second valve to fill the internal space with a processing fluid at a second pressure. This configuration ensures that the processing fluid at the first pressure can be switched to the processing fluid at the second pressure.

[0115] For example, the storage unit may be configured to store a liquid treatment fluid pressurized to a first pressure, to have a first pipe connected to a space above the liquid level of the treatment fluid, and to have a second pipe connected to a space below the liquid level, and to function as a first supply unit by sending the gaseous treatment fluid above the liquid level to the first pipe. Such a configuration makes it possible to store the treatment fluid in both gaseous and liquid forms in a single storage unit, thereby simplifying the device configuration.

[0116] In this case, the pressurizing unit may be configured to pressurize the process fluid at the first pressure delivered from the reservoir to the second pipe to the second pressure and output the pressurized process fluid. With this configuration, the process fluid as a gas at the first pressure and the process fluid as a liquid at the second pressure can be supplied from a single reservoir.

[0117] Furthermore, for example, the second supply unit may be configured to have a return pipe connected to the second pipe between the pressurizing unit and the second valve and connected to the reservoir via a third valve. In this case, the pressurizing unit may be configured to pressurize the treatment fluid supplied from an external supply source and cause it to flow into the reservoir when the control unit closes the second valve and opens the third valve. With this configuration, the treatment fluid can be pressurized by the pressurizing unit before being stored in the reservoir, so the treatment fluid itself supplied from further upstream may be at a lower pressure than the first pressure. In other words, there is greater flexibility in the supply source of the treatment fluid.

[0118] Furthermore, for example, a first heater may be provided to heat the processing fluid flowing from the second pipe through the inlet flow path. With this configuration, the processing fluid can be made supercritical by heating it to a temperature equal to or higher than its critical temperature, so the second supply unit does not need to output the processing fluid in a supercritical state.

[0119] Furthermore, for example, a second heater may be provided to heat the processing fluid stored in the storage section. With this configuration, a decrease in the internal pressure of the storage section that may occur as the stored processing fluid is consumed can be compensated for by heating, and the pressure of the processing fluid being delivered can be maintained stably.

[0120] Furthermore, for example, the first pressure may be configured to be lower than the pressure at which the processing fluid is liquefied at the temperature of the processing fluid delivered by the first supply unit. With this configuration, the processing fluid delivered from the first supply unit can be reliably maintained in a gaseous state.

[0121] Furthermore, according to the findings of the present inventors, by sufficiently increasing the internal pressure of the processing chamber by introducing a gas, liquefaction or solidification of the critical processing fluid when the critical processing fluid is subsequently introduced can be prevented. For example, the pressure difference between atmospheric pressure and the first pressure can be set to be greater than the pressure difference between the first pressure and the second pressure. [Industrial Applicability]

[0122] The present invention can be applied to any technique for processing a substrate with a processing fluid in a supercritical state in a processing chamber. [Explanation of symbols]

[0123] 4. Supercritical processing equipment (substrate processing equipment) 97 Supercritical Processing Control Unit (Control Unit) 412 Processing Chamber 457 Fluid supply section (first supply section, second supply section) 700 Fluid supply source (1st supply section) 715 Pressure pump (pressurizing part) 717 Storage tank (reservoir, first supply section, second supply section) 719 Heater (Second Heater) 725,726 Heater (1st heater) 732 Piping (Second Piping) 736 Piping (1st Piping) 733 Piping (return piping) 737 Piping (1st Piping) 740 Piping group (inlet flow path) SP Processing space (internal space) V74 valve (third valve) V75 valve (second valve) V76 valve (first valve)

Claims

1. 1. A substrate processing apparatus for processing a substrate with a processing fluid in a supercritical state, a processing chamber having an interior space capable of accommodating the substrate; a first supply unit that supplies the processing fluid as a gas pressurized to a first pressure that is lower than the critical pressure; a second supply unit that supplies the processing fluid at a second pressure higher than the critical pressure; an introduction flow path that is in communication with the internal space and introduces the treatment fluid into the internal space; a first pipe connecting the first supply unit and the introduction flow path via a first valve; a second pipe connecting the second supply unit and the introduction flow path via a second valve; a control unit that controls the first valve and the second valve to selectively allow the processing fluid at the first pressure and the processing fluid at the second pressure to flow into the internal space; Equipped with The second supply unit is a storage section for storing the liquid treatment fluid; a pressurizing unit that is inserted in the second pipe extending from the reservoir unit to the second valve and pressurizes the treatment fluid to the second pressure and delivers the treatment fluid; The substrate processing apparatus has:

2. 2. The substrate processing apparatus of claim 1, wherein the control unit opens the first valve to fill the internal space with the processing fluid at the first pressure, and then closes the first valve and opens the second valve to fill the internal space with the processing fluid at the second pressure.

3. The storage section is the treatment fluid in a liquid state pressurized to the first pressure is stored, the first pipe is connected to communicate with a space above a liquid level of the treatment fluid, and the second pipe is connected to communicate with a space below the liquid level; The substrate processing apparatus according to claim 1 , wherein the processing fluid is in a gaseous state above the liquid surface and is fed to the first pipe, thereby functioning as the first supply unit.

4. The substrate processing apparatus according to claim 3 , wherein the pressurizing unit pressurizes the processing fluid at the first pressure, which is delivered from the reservoir unit to the second pipe, to the second pressure and outputs the pressurized processing fluid.

5. 5. The substrate processing apparatus according to claim 1, wherein the second supply unit has a return pipe connected to the second pipe between the pressurizing unit and the second valve and connected to the reservoir unit via a third valve.

6. 6. The substrate processing apparatus of claim 5, wherein, when the control unit closes the second valve and opens the third valve, the pressurizing unit pressurizes the processing fluid supplied from an external supply source and causes the processing fluid to flow into the storage unit.

7. 5. The substrate processing apparatus according to claim 1, further comprising a first heater for heating the processing fluid flowing from the second pipe through the inlet flow path.

8. 5. The substrate processing apparatus according to claim 1, further comprising a second heater for heating the processing fluid stored in the storage section.

9. 5. The substrate processing apparatus according to claim 1, wherein the first pressure is lower than a pressure at which the processing fluid is liquefied at a temperature of the processing fluid delivered by the first supply unit.

10. 5. The substrate processing apparatus according to claim 1, wherein a pressure difference between the atmospheric pressure and the first pressure is larger than a pressure difference between the first pressure and the second pressure.

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