Substrate processing equipment

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

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[0001] This invention relates to a technique for accommodating a substrate in a processing chamber and processing it with a processing fluid in a supercritical state.

Background Art

[0002] In the processing steps of various substrates such as semiconductor substrates and glass substrates for display devices, there are those that process the surface of the substrate with various processing fluids. Wet processing using liquids such as chemical solutions and rinse solutions as the processing fluid has been widely performed conventionally. In recent years, in order to dry the substrate after the wet processing, processing using a processing fluid in a supercritical state has also been put into practical use. In particular, it is beneficial in the drying process of a substrate having a pattern formation surface on which a fine pattern is formed. This is because the processing fluid in the supercritical state has a lower surface tension than a liquid and has the property of entering deep into the gaps between the patterns. By using this processing fluid, it is possible to efficiently perform the drying process. It is also possible to reduce the risk of pattern collapse caused by 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 to which a circulation line is connected, and the processing fluid is kept in a liquid state by circulating through a circulation line in which a condenser is inserted. Then, a connection line branched from the circulation line is connected to the processing chamber, and the processing fluid that has become supercritical from a liquid is supplied to the processing chamber by heating from a heater provided in this flow path.

Prior Art Documents

[0006] The conventional technology described above does not take this problem into consideration. In other words, there is room for improvement in the conventional technology described above in terms of achieving good substrate processing without causing problems such as particle adhesion or pattern collapse.

[0007] This 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 the processing chamber in a technology for processing substrates with a supercritical processing fluid. [Means for solving the problem]

[0008] One aspect of this invention is a substrate processing apparatus for processing a substrate with a processing fluid in a supercritical state, comprising: a processing chamber having an internal space capable of accommodating the substrate; a first supply unit that supplies the processing fluid as a gas pressurized to a first pressure 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 channel communicating with the internal space and introducing the processing fluid into the internal space; a first pipe connecting the first supply unit and the introduction channel via a first valve; a second pipe connecting the second supply unit and the introduction channel via a second valve; and a control unit that controls the first valve and the second valve to selectively introduce the processing fluid at the first pressure and the processing fluid at the second pressure into the internal space. Here, the second supply unit has a storage unit for storing the liquid processing fluid and a pressurizing unit interposed in the second pipe from the storage unit to the second valve, which pressurizes the processing fluid to the second pressure and delivers it.

[0009] In this configuration, the processing chamber can be supplied with a processing fluid at a relatively low pressure (first pressure) and a processing fluid at a higher pressure (second 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 can be supplied to the processing chamber in a supercritical state depending on its temperature setting.

[0010] As in the conventional technology described above, directly introducing a high-pressure processing fluid exceeding the critical pressure into a processing chamber where the internal pressure is approximately atmospheric pressure may result in 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 increasing the internal pressure to an intermediate first pressure, and then the supercritical processing fluid is introduced from that state. Therefore, the temperature drop due to adiabatic expansion is more limited, and the problems in the conventional technology can be resolved. [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 raised to an intermediate first pressure prior to introducing the processing fluid in a supercritical state at a second pressure. By introducing the processing fluid in this two-stage 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 caused by partial liquefaction or solidification of the processing fluid can be prevented. [Brief explanation of the drawing]

[0012] [Figure 1] This figure shows a schematic configuration of a substrate processing system equipped with one embodiment of the substrate processing apparatus according to the present invention. [Figure 2] This is a side view showing the overall configuration of the wet processing apparatus. [Figure 3] This is a diagram illustrating the operation of a wet processing apparatus. [Figure 4] This is a side view showing the configuration of a supercritical fluid processing apparatus. [Figure 5] This figure shows the details of the supply and discharge routes for the processed fluid. [Figure 6] This flowchart shows the processes performed by the supercritical fluid processing unit. [Figure 7] This figure shows the pressure changes inside the processing chamber and storage tank. [Figure 8] This diagram shows the open / closed state of the valve during standby operation. [Figure 9] This diagram shows the open / closed state of the valve when gas is introduced. [Figure 10] This diagram shows the open / closed state of the valve when introducing a supercritical fluid. [Figure 11] This diagram shows the open / closed state of the valve when replenishing the processing fluid. [Figure 12] This is a phase diagram of carbon dioxide, the fluid being processed. [Modes for carrying out the invention]

[0013] FIG. 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. This substrate processing system 1 is a processing system for supplying a processing liquid onto the upper surface of various substrates such as semiconductor wafers, etc., wet-processing the substrates, and then drying the substrates, and has a system configuration suitable for implementing the substrate processing method according to the present invention. The substrate processing system 1 mainly includes a wet processing apparatus 2, a substrate transfer apparatus 3, a supercritical processing apparatus 4, and a control apparatus 9.

[0014] The wet processing apparatus 2 receives the substrate to be processed and executes a predetermined wet process. The content of the process is not particularly limited. The wet process includes a development process, a cleaning process, etc. After performing a development process or the like, a liquid-filled state in which an organic solvent such as IPA liquid is placed on the pattern formation surface of the substrate is created. The substrate transfer apparatus 3 carries out and transfers the substrate from the wet processing apparatus 2 while maintaining the liquid-filled state, and loads it into the supercritical processing apparatus 4. The supercritical processing apparatus 4 corresponds to the substrate processing apparatus according to the present invention, and executes a drying process (supercritical drying process) using a supercritical state processing fluid on the loaded substrate. These are installed in a clean room. Therefore, the substrate transfer apparatus 3 transfers the substrate in an air atmosphere and at atmospheric pressure.

[0015] The control apparatus 9 controls the operations of these apparatuses to realize a predetermined process. For this purpose, the control apparatus 9 includes a CPU 91, a memory 92, a storage 93, and an interface 94, etc. 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 the user and external apparatuses. The operations of the apparatuses described later are realized by the CPU 91 executing the control programs written in advance in the storage 93 and causing each part of the apparatus to perform a predetermined operation.

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

[0017] As the "substrate" in the present embodiment, various substrates such as a semiconductor wafer, a glass substrate for a photomask, a glass substrate for a liquid crystal display, a glass substrate for a plasma display, a substrate for a FED (Field Emission Display), a substrate for an optical disk, a substrate for a magnetic disk, and a substrate for a magneto-optical disk can be applied. Hereinafter, a substrate processing apparatus mainly used for processing a disk-shaped semiconductor wafer will be taken as an example and described with reference to the drawings. However, it can be similarly applied to the processing of various substrates exemplified above. Also, various shapes of substrates can be applied.

[0018] In the following description, a substrate having a pattern formed only on one main surface is used as an example. Here, the side of the main surface on which a pattern or the like is formed is referred to as the "front surface", and the main surface on the opposite side where no pattern is formed is referred to as the "back surface". Also, the main surface of the substrate facing downward is referred to as the "lower surface", and the main surface of the substrate facing upward is referred to as the "upper surface". In the following, the upper surface will be described as the front surface.

[0019] FIG. 2 and FIG. 3 are diagrams showing a configuration example of the 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 supplies a processing liquid to the upper surface of the substrate S and processes the substrate. The operation of the wet processing apparatus 2 is controlled by the wet process control unit 95 of the control apparatus 9.

[0020] The wet processing apparatus 2 supplies a processing liquid to the surface (pattern forming surface) Sa of the substrate S to perform wet processing such as surface treatment and cleaning of the substrate S. For this purpose, the wet processing apparatus 2 is equipped with a substrate holding section 21, a splash guard 22, and processing liquid supply sections 23 and 24 inside the processing chamber 200. These operations are controlled by a wet processing control section 95 provided in the control device 9. The substrate holding section 21 has a disc-shaped spin chuck 211 with a diameter approximately the same as that of the substrate S, and a plurality of chuck pins 212 are provided on the periphery of the spin chuck 211. By having the chuck pins 212 contact the periphery of the substrate S and support the substrate S, the spin chuck 211 can hold the substrate S in a horizontal position with the substrate S spaced apart from its upper surface.

[0021] The spin chuck 211 is supported by a rotating support shaft 213 extending downward from the center of its lower surface, so that its upper surface is horizontal. The rotating support shaft 213 is rotatably supported by a rotating mechanism 214 attached to the bottom of the processing chamber 200. The rotating mechanism 214 incorporates a rotating motor (not shown), and when the rotating motor rotates in response to a control command from the control device 9, the spin chuck 211, which is directly connected to the rotating support shaft 213, rotates around the rotation axis AX shown by the dashed line. In Figure 2, the up and 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 so as to surround the substrate holding portion 21 from the side. The splash guard 22 has a roughly cylindrical cup 221 that is provided so as to cover the periphery of the spin chuck 211, and a liquid receiving portion 222 provided below the outer circumference of the cup 221. The cup 221 moves up and down in response to a control command from the control device 9. As shown in Figure 2, the cup 221 moves up and down between a lower position where the upper end of the cup 221 is below the periphery of the substrate S held by the spin chuck 211, and an upper position where the upper end of the cup 221 is above the periphery of the substrate S, as shown in Figure 3.

[0023] When the cup 221 is in the lower position, as shown in Figure 2, 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, loading or unloading the substrate S into or out of the spin chuck 211.

[0024] Furthermore, when the cup 221 is in the upper position, it surrounds the periphery of the substrate S held by the spin chuck 211, as shown in Figure 3. This prevents the processing liquid that is shaken off the periphery of the substrate S during liquid supply (described later) from scattering into the chamber 200, and ensures reliable collection of the processing liquid. In other words, droplets of processing liquid that are shaken off the periphery of the substrate S as the substrate S rotates adhere to the inner wall of the cup 221 and flow downward, where they are collected by the liquid receiving section 222 located below the cup 221. Multiple cups may be arranged concentrically to collect multiple processing liquids individually.

[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 pivot shaft 232 rotatably mounted on a base 231 fixed to the processing chamber 200. When the pivot shaft 232 rotates in response to a control command from the control device 9, the arm 233 swings, and the nozzle 234 at the tip of the arm 233 moves between a retracted position, where it is moved to the side from above the substrate S as shown in Figure 2, and a processing position above the substrate S as shown in Figure 3.

[0026] The nozzle 234 is connected to a processing liquid supply source 238. When an appropriate processing liquid is supplied from the processing liquid supply source 238, the processing liquid is discharged from the nozzle 234 toward the substrate S. As shown in Figure 2B, the spin chuck 211 rotates at a relatively low speed to rotate the substrate S, and the processing liquid L1 is supplied from the nozzle 234, which is 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 with various functions such as a developer, etching solution, washing solution, or rinsing solution, and its composition is arbitrary. In addition, a combination of multiple types of processing liquids may be used to perform the processing.

[0027] The other processing liquid supply unit 24 also has a configuration corresponding to the first processing liquid supply unit 23 described above. 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 of 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 processing liquid to the surface Sa of the substrate S.

[0028] In this embodiment, the second processing liquid supply unit 24 is used to form a liquid film on the substrate S after wet processing to prevent drying. That is, the substrate S after wet processing is transported to the supercritical processing apparatus 4 to undergo supercritical drying processing, but in order to prevent the surface of the substrate S from being exposed and oxidized during transport, or for the fine patterns formed on the surface to collapse, the substrate S is transported with its surface covered with a paddle-shaped liquid film.

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

[0030] Here, the wet processing apparatus 2 is provided with two sets of processing liquid supply units, but the number of processing liquid supply units, their structure, and function 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. Also, one processing liquid supply unit may be equipped with multiple nozzles. For example, multiple nozzles may be provided at the tip of a single arm. Furthermore, in addition to the mode in which the processing liquid is discharged with the nozzles positioned at a predetermined position as described above, a mode in which the processing liquid is discharged while the nozzles scan and move along the surface Sa of the substrate S may also be included.

[0031] Returning to Figure 1, let's continue the explanation. The substrate transport device 3 is equipped with a transport robot 30, which has a hand 31 at the end of an extendable and rotatable arm. The hand 31 can support the substrate by partially contacting the underside of the substrate, and as shown by the dotted line in Figure 1, it can move forward and backward relative to both the wet processing device 2 and the supercritical processing device 4. This allows for the loading and unloading of substrates to and from the wet processing device 2 and the supercritical processing device 4, respectively. The operation of the transport robot 30 is controlled by the transport control unit 96 of the control device 9. There are many known technologies for this type of transport robot, and in this embodiment, they can be appropriately selected and used, so a detailed explanation will be omitted.

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

[0033] The supercritical processing apparatus 4 comprises a processing unit 41, a transfer unit 43, and a supply unit 45. The processing unit 41 is the main unit for executing the supercritical drying process. The transfer unit 43 receives the wet-processed substrate S transported by the substrate transport device 3 and loads 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 the chemical substances, power, and energy necessary for the process to the processing unit 41 and the transfer unit 43. These operations are controlled by the control device 9, in particular by 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 composed of a combination of several metal blocks, and its interior is hollow, forming a processing space SP. The substrate S to be processed is brought into the processing space SP and processed. A slit-shaped opening 421 extending elongated in the X direction is formed on the (-Y) side of the processing chamber 412. The processing space SP and the external space are in communication through the opening 421. The cross-sectional shape of the processing space SP is generally the same as the opening shape of the opening 421. That is, 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 extending in the Y direction.

[0035] A lid member 413 is provided on the (-Y) side 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 mounted horizontally on the (+Y) side of the lid member 413. The upper surface of the support tray 415 is a support surface on which the substrate S can be placed. The lid member 413 is supported so as to be able to move horizontally in the Y direction by a support mechanism (not shown).

[0036] The lid member 413 is movable forward and backward relative to the processing chamber 412 by a forward / backward mechanism 453 provided on the supply unit 45. Specifically, the forward / backward mechanism 453 has a linear motion mechanism such as a linear motor, linear guide, ball screw mechanism, solenoid, or air cylinder. Such a linear motion mechanism moves the lid member 413 in the Y direction. The forward / backward mechanism 453 operates in response to control commands from the control device 9.

[0037] As the lid member 413 moves in the (-Y) direction, it separates from the processing chamber 412, and as shown by the dotted line, the support tray 415 is pulled out of the processing space SP through the opening 421, making the support tray 415 accessible. That is, it becomes possible to place a substrate S on the support tray 415 and to remove a substrate S that is placed on the support tray 415. On the other hand, as the lid member 413 moves in the (+Y) direction, the support tray 415 is housed inside the processing space SP. If a substrate S is placed on the support tray 415, the substrate S is transported into the processing space SP together with the support tray 415.

[0038] The processing space SP is sealed when the lid member 413 moves in the (+Y) direction and closes the opening 421. A sealing member 422 is provided between the (+Y) side surface of the lid member 413 and the (-Y) side surface of the processing chamber 412, maintaining the airtight state of the processing space SP. The sealing member 422 is made of rubber, for example. In addition, the lid member 413 is fixed to the processing chamber 412 by a locking mechanism (not shown). Thus, in this embodiment, the lid member 413 can be switched between a closed state (solid line) in which the opening 421 is closed and the processing space SP is sealed, and a separated state (dotted line) in which it is far enough away from the opening 421 that the substrate S can be inserted and removed.

[0039] With the processing space SP airtight, processing of the substrate S is performed within the processing space SP. In this embodiment, a fluid supply unit 457 provided in the supply unit 45 delivers a processing fluid of a substance usable for supercritical processing, such as carbon dioxide, as the processing fluid, and further pressurizes the processing fluid in the processing chamber 412 to bring it to a supercritical state. The processing fluid is supplied to the processing unit 41 in gaseous or liquid form. Carbon dioxide is a suitable chemical substance for supercritical drying processing because it becomes supercritical at relatively low temperatures and low pressures, and has the property of dissolving organic solvents, which are frequently used in substrate processing, well. The critical point at which carbon dioxide becomes supercritical is a pressure (critical pressure) of 7.38 MPa and a temperature (critical temperature) of 31.1°C.

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

[0041] The processing space SP has a shape and volume that can accommodate the support tray 415 and the substrate S supported therein. Specifically, the processing space SP has a roughly rectangular cross-sectional shape that is wider horizontally than the width of the support tray 415 and greater vertically than the combined height of the support tray 415 and the substrate S, and has a depth that can accommodate the support tray 415. Thus, the processing space SP has a shape and volume that can accommodate 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.

[0042] The fluid supply unit 457 supplies processing fluid to the processing space SP further to the (+Y) side than the (+Y) side end of the substrate S. On the other hand, the fluid recovery unit 55 discharges the processing fluid that has flowed through the space above the substrate S and the space below the support tray 415 within the processing space SP, further to the (-Y) side than the (-Y) side end of the substrate S. As a result, a laminar flow of processing fluid is formed within the processing space SP, both above the substrate S and below the support tray 415, moving from the (+Y) side to the (-Y) side.

[0043] The supercritical fluid processing control unit 97 of the control device 9 determines the pressure and temperature in the processing space SP based on the detection results of a detection unit (not shown), and controls the fluid supply unit 457 and the fluid recovery unit 455 based on these results. This ensures that the supply of processing fluid to the processing space SP and the discharge of processing fluid from the processing space SP are appropriately managed, and the pressure and temperature in the processing space SP are adjusted according to 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 comprises a main body 431, a lifting member 433, a base member 435, and a plurality of 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 upper part of the lifting member 433. A plurality of 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 its upper end contacting 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 end heights are equal to each other.

[0045] The lifting member 433 is movable 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, linear guide, ball screw mechanism, solenoid, or air cylinder, and such a linear motion mechanism moves the lifting member 433 in the Z direction. The lifting mechanism 451 operates in response to control commands from the control device 9.

[0046] The base member 435 moves up and down as the lifting member 433 moves up and down, and multiple lift pins 437 move up and down in conjunction with it. This enables 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 Figure 4, the substrate S is transferred when the support tray 415 is pulled out 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 rises, the upper ends of the lift pins 437 reach above the upper surface of the support tray 415 through the through holes 419. In this state, the substrate S being transported by the transport robot 30 is transferred from the hand 31 of the transport robot 30 to the lift pins 437. As the lift pins 437 descend, the substrate S is transferred from the lift pins 437 to the support tray 415. The substrate S can be unloaded by the reverse procedure described above.

[0047] Next, the supply path for the processing fluid to the processing chamber 412 and the discharge path for the processing fluid from the processing chamber 412 will be described in more detail. Briefly above, it was explained that the processing fluid is supplied from the fluid supply unit 457 to the processing chamber 412, and the processing fluid is recovered from the processing chamber 412 to the fluid recovery unit 455. In the actual apparatus, the fluid supply unit 457 and the fluid recovery unit 455 have the following configurations.

[0048] Figure 5 shows the details of the supply and discharge paths of the processing fluid. Note that in Figure 5, for illustrative purposes, the orientation of the processing chamber 412 is reversed compared to Figure 4. That is, in Figure 4, the processing fluid is introduced into the processing chamber 412 from the right side of the page and discharged to the left side. On the other hand, in Figure 5, the opposite is true: the processing fluid is introduced into the processing chamber 412 from the left side of the page and discharged to the right side. In other words, the side of the processing chamber 412 in Figure 5 is shown as being opposite to the side of the processing chamber 412 in Figure 4.

[0049] 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 groups of piping 730 and 740 connecting them. These operate in response to control commands from the supercritical processing control unit 97.

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

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

[0052] Valve V70 allows the processed fluid at a pressure specified by a control command from the supercritical fluid processing control unit 97 to flow through piping 731. The purifier 711 and filter 712 remove impurities contained in the processed fluid and improve its purity. The condenser 713 condenses the processed fluid that is sent out as a gas from the fluid supply source 700. When valves V71 and V72 are opened, the processed fluid is output from piping 731.

[0053] Piping 731 merges with piping 735, which is connected to the storage tank 717 (described later), on the output side of valve V72. After the merge, piping 732 is equipped with a condenser 714, a pressure pump 715, and a filter 716. The condenser 714 is provided to more reliably maintain the liquid phase state of the processing fluid. The pressure pump 715 pressurizes and delivers the liquid processing fluid. The filter 716 removes impurities from the processing fluid.

[0054] Piping 732 branches into two pipes 733 and 734 at the output side of filter 716. Piping 733 is connected to the top of storage tank 717, with valve V74, which is an on / off valve, inserted along its length. Piping 734 also has valve V75, which is an on / off valve, inserted along its length.

[0055] The storage tank 717 is a high-pressure vessel that has the function of storing pressurized liquid processing fluid. The storage tank 717 is equipped with a level sensor 718 to manage the liquid level. Therefore, the internal space of the storage tank 717 is not liquid-tight, and vaporized processing fluid is stored in the space above the liquid level under a pressure similar to that of the liquid. In addition, a heater 719 is attached to the storage tank 717, and in response to control commands from the supercritical processing control unit 97, the heater 719 can heat the processing fluid inside the tank.

[0056] A pipe 735 is connected to the bottom of the storage tank 717, and pipe 735 merges with pipe 731 and connects to pipe 732. When valve V73, an on / off valve inserted in pipe 735, is opened, the liquid of the processing fluid in the storage tank 717 flows into pipe 732 via pipe 735. If valve V74 on pipe 733 is further opened, a recirculation channel is formed that allows the fluid to return from the storage tank 717 to the storage tank 717 via pipes 735, 732, and 733. By circulating the processing fluid through this recirculation path and pressurizing the processing fluid with a pressure pump 715, 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 specified 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 pipe 736 merges with pipe 734 via a valve V76, which is an on / off valve. From pipe 736, a gaseous processing fluid that fills the upper part of the internal space of the storage tank 717 is output. From pipe 741, where pipes 734 and 736 merge, a gaseous processing fluid flows in when valve V76 is open, and a liquid processing fluid flows in when valve V75 is open.

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

[0059] Pipe 741 is part of a group of pipes 740 that constitute an introduction channel for introducing the processing fluid from the purification unit 710 to the processing chamber 412. Pipe 741 branches into two pipes 743 and 744, each equipped with filters 721 and 722, respectively. These pipes 743 and 744 merge to form pipe 745, which then branches into two more pipes 747 and 748.

[0060] In piping 742, a flow meter 723, a heater 725, and a valve V78 (which acts as an on-off valve) are inserted in that order along the direction of fluid flow (to the right in the figure), and piping 742 is ultimately connected to the processing chamber 412. More specifically, piping 742 communicates with the internal space SP above the support tray 415 (Figure 4) that supports the substrate S. On the other hand, in piping 743, a flow meter 723, a heater 726, and a valve V79 (which acts as an on-off valve) are inserted in that order along the direction of fluid flow. And piping 742 communicates with the internal space SP of the processing chamber 412 below the support tray 415 (Figure 4) that supports the substrate S. As a result, the processing fluid is supplied to the spaces above and below the substrate S placed on the support tray 415 in the internal space SP.

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

[0062] In this way, the fluid supply unit 457 can supply the processing chamber 412 with a cleaned processing fluid whose temperature and pressure have been adjusted to predetermined target values. The sequence of supplying 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 the processing chamber 412 is delivered from the storage tank 717, and the processing fluid is stored in the storage tank 717 under pressure from the pressure pump 715. Therefore, the pressure of the processing fluid delivered from the fluid supply source 700 may be lower than the pressure required for processing. If the fluid supply source 700 can stably deliver processing fluid at a pressure suitable for processing, the gaseous processing fluid may be supplied directly from the fluid supply source 700 via the piping 737, as shown by the dotted line in Figure 5, instead of taking it from the storage tank 717. Alternatively, the pressure-regulated processing fluid may be supplied from the output side of valve V70.

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

[0065] A pipe 531, which forms part of a piping group 530, is connected to the upper part of the processing chamber 412. On the other hand, a pipe 532 is connected to the lower part of the processing chamber 412. These pipes 531 and 532 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 pipe 531.

[0066] In piping 531, a flow meter 501 and a valve V51 (which acts as an on-off valve) are inserted in that order along the direction of flow of the processed fluid. On the other hand, in piping 532, a flow meter 502 and a valve V52 (which acts as an on-off valve) are inserted in that order along the direction of flow of the processed fluid. At the output side of valves V51 and V52, piping 531 and 532 merge. In piping 533 after the merger, a pressure regulating valve V53 and a valve V54 (which acts as an on-off valve) are inserted.

[0067] The piping 533 is connected to the high-pressure exhaust tank 505, and the processed fluid discharged from the processing chamber 412 is contained in the high-pressure exhaust tank 505 via the piping 533. The high-pressure exhaust tank 505 is equipped with a heater 506 to maintain the temperature of the processed fluid stored inside at an appropriate level.

[0068] A pipe 544 is connected to the top of the high-pressure exhaust tank 505. A valve V55 (an on / off valve), a valve V56 (a pressure regulating valve), and a heater 507 are interposed in the pipe 544, and the pipe 544 is finally connected to the low-pressure exhaust tank 508. Thus, the processed fluid, as a gas with appropriately adjusted pressure and temperature, flows into the low-pressure exhaust tank 508. The processed fluid in the low-pressure exhaust tank 508 is finally recovered via a pipe 545 by an external recovery device (not shown). A pressure sensor 510 is provided in the pipe 545 for detecting the pressure of the gas being discharged to the outside.

[0069] Furthermore, piping 546 is connected to the lower part of the high-pressure exhaust tank 505, while piping 547 is connected to the lower part of the low-pressure exhaust tank 508. These pipes merge to form piping 548, to which valve V57, 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 explained with reference to Figures 6 and 7. The supercritical processing apparatus 4 performs a process to dry the substrate S after wet processing using a processing fluid in a supercritical state, that is, a supercritical drying process. This process is realized by the CPU 91 of the control unit 9 executing a pre-prepared control program to control each part of the apparatus.

[0071] Figure 6 is a flowchart showing the process performed by the supercritical fluid processing apparatus. Figure 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 from the storage tank 717, which stores the processing fluid, to the processing chamber 412. Therefore, the pressure in the processing space SP of the processing chamber 412 (hereinafter referred to as "chamber pressure") and the pressure in the internal space of the storage tank 717 (hereinafter referred to as "tank 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 after the liquid film formation process has been completed in the wet processing device 2, and places the substrate S on the support tray 415, which 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 pin 437 of the supercritical processing device 4, and then from the lift pin 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. This completes the loading of the substrate S. Since the processing chamber 412 is opened to the atmosphere for loading 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 Figure 7.

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

[0075] After the substrate S is brought in, the introduction of the gaseous processing fluid is started from the fluid supply unit 457 (step S103; time T1), which causes the chamber pressure to gradually rise. When the chamber pressure 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 instead of the gas (step S105; time T3).

[0076] As a result, the processing space SP of the processing chamber 412 is filled with a supercritical processing fluid, and the chamber pressure is maintained at a constant second pressure P2 which is greater than the first pressure P1 and the critical pressure of the processing fluid (times T4-T5). Meanwhile, any liquid remaining on the substrate S is replaced by the supercritical processing fluid, dissolves into the processing fluid, and is removed from the surface of the substrate S.

[0077] Once the chamber pressure has been maintained at approximately pressure P2 for a predetermined period of time (step S106), the discharge of the processing fluid from the processing chamber 412 begins (step S107; time T5), thereby reducing the pressure in the processing space SP. After time T7, when the chamber pressure has dropped to near atmospheric pressure Pa, the substrate S is unloaded by the transport robot 30 (step S108), completing the processing for one substrate S. If there is another substrate to be processed, the process returns to step S101 (step S109), and the above process is repeated.

[0078] As shown in the lower part of Figure 7, the internal pressure of the storage tank 717 gradually decreases as the processing fluid stored in the tank is consumed. To restore this pressure, a standby operation is performed to replenish the pressurized processing fluid in the storage tank 717 (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 Figure 7, it is possible to start the standby operation while the pressure inside the processing chamber 412 is being reduced.

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

[0080] Figures 8 through 11 show the state of the valves at each stage of the process. In these figures, the flow of the process fluid as a gas is indicated by thick dotted arrows, and the flow of the process fluid as a liquid is indicated by thick solid arrows. In particular, in Figure 10, the flow of the process fluid in a supercritical state is indicated by a white, thick dotted arrow.

[0081] Furthermore, in these diagrams, among the valves that are on-off valves, those marked with a white circle (〇) near the symbol and a single underline under the symbol indicate that the valve is open. On the other hand, those marked with a black circle (●) near the symbol and a double underline under the symbol indicate that the valve is closed. Valves that do not have these markings do not directly affect the processes described below, and therefore their open / closed state is not specifically 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 pressurizing pump 715 and introduced into the storage tank 717, thereby raising the tank internal pressure to the 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 whose pressure is adjusted by the valve V70, is pressurized to a predetermined pressure by the pressurizing 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 processing fluid continues until a predetermined amount of liquid at a predetermined pressure is accumulated. In addition, the temperature of the processing fluid in the tank is adjusted by the heater 719.

[0084] Thus, during the waiting 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 Figure 7), a process is performed as a standby operation to maintain the liquid volume, pressure, and temperature in the tank at predetermined values. The target pressure is the first pressure P1 or slightly higher, which in this embodiment is 6 MPa. The target temperature in this embodiment is 20°C. The target liquid volume is set to an amount sufficient to adequately supply the processing fluid to the processing chamber 412 in the supercritical drying process described above.

[0085] Figure 9 shows the open and closed states of the valves when gas is introduced. In step S103 (times T1-T2), a gaseous processing fluid is introduced into the processing chamber 412, and the pressure inside the chamber is increased. During this pressure-boosting stage, valves V72, V74, etc., on the path supplying the processing fluid to the storage tank 717 are closed, blocking the supply path, while valve V76 on the piping 736 connected to the top of the tank and valves V77, etc., provided in the piping group 740 are opened. Therefore, the gaseous processing fluid filling the area above the liquid level inside the storage tank 717 is supplied to the processing chamber 412 via the piping group 740.

[0086] As a result, the chamber pressure shown in the upper part of Figure 7 rises from atmospheric pressure Pa to the first pressure P1. At this time, the tank pressure shown in the lower part of Figure 7 begins to decrease at time T1 when the output of the processed fluid starts. However, the decrease in tank pressure gradually becomes more gradual as heater 719 operates to compensate for the temperature drop inside the tank caused by the rapid pressure drop.

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

[0088] Furthermore, the chamber pressure can be indirectly measured by a pressure gauge 503 installed in the piping 531 on the discharge channel communicating with the processing space SP. Therefore, in step S106, the chamber pressure can be determined using the measurement result 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 takes for the chamber pressure to reach the target value. For this reason, in actual equipment, it is possible to omit the actual measurement of the chamber pressure by determining the length of time for which the valve V76 that controls the delivery of gas is open. In other words, a judgment based on elapsed time can be adopted, similar to step S106.

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

[0090] A pressurizing pump 715 is provided in the flow path of the processing fluid, and the processing fluid is transported through the piping group 740 with its pressure raised to a pressure exceeding the critical pressure (second pressure P2 in this embodiment). Heaters 725 and 726 provided in the flow path heat the processing fluid to 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 processing fluid in a supercritical state.

[0091] In this case as well, a discharge channel is opened to discharge a small amount of processing fluid from the processing chamber 412. Therefore, liquids that have been replaced by the processing fluid and separated from the substrate S are discharged to the outside along with the processing fluid, preventing them from re-adhering to the substrate S. The pressure inside the tank drops sharply when the liquid is 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 pressurizing pump 715 is reduced, causing the chamber pressure to begin to decrease. To prevent the processing fluid from liquefying or solidifying due to rapid depressurization and damaging the substrate S, the depressurization rate is adjusted so that the processing fluid undergoes a direct phase change from the supercritical state to the gas phase. Once the chamber pressure has decreased sufficiently (for example, to below the critical pressure) and the risk of liquefaction and solidification is eliminated, 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, thereby rapidly reducing the pressure.

[0093] For example, from the state shown in Figure 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 the pressurizing pump 715 will be returned to the storage tank 717, thereby suppressing the decrease in tank pressure. Furthermore, after the delivery of processing fluid to the processing chamber 412 is stopped, processing fluid can be replenished from the fluid supply source 700 to the storage tank 717.

[0094] Figure 11 shows the open and closed states of the valve when replenishing the processing fluid. In the fluid recovery unit 455, even if the depressurization process is ongoing, after the supply of processing fluid to the processing chamber 412 has stopped, that is, after time T6 when valve V75 is closed, the delivery 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 pressurizing pump 715. This restores the tank pressure and fluid volume, preparing for processing the next substrate.

[0095] As can be seen by comparing Figure 8 and Figure 11, the operation of the fluid supply unit 457 at this time is the same as the standby operation. In other words, the standby operation of 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 the removal of the substrate S by the transport robot 31. Therefore, after the removal of the processed substrate, it becomes possible to quickly receive and process a new substrate.

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

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

[0098] As can be seen from the phase diagram, point A, specified by this pressure and temperature, is located at the boundary between the liquid and gas phases, that is, slightly within 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 gaseous fluid being processed can take. In other words, the first pressure P1 is set to satisfy these conditions. It is more preferable that point A is as close to the critical point C as possible without the fluid being liquefied or supercritical.

[0099] After the chamber pressure 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, and in this embodiment it is 11 MPa (second pressure P2). The temperature is set to an appropriate value that exceeds the critical temperature Tc.

[0100] The reason for performing the two-stage pressure increase, 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: When a high-pressure, supercritical processing fluid is directly introduced into a processing chamber at atmospheric pressure, as in the conventional technique, processing defects such as particle adhesion and pattern collapse may occur on the substrate. According to the inventors of this application, the cause is that when a high-pressure, high-density processing fluid flows into a low-pressure processing chamber, a portion of the processing fluid, 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 introduced into the processing chamber 412 in advance 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. By raising the chamber pressure in two stages in this way, liquefaction and solidification of the processing fluid inside the chamber can be prevented.

[0102] Furthermore, when the gaseous processing fluid comes into contact with the liquid film of organic solvent covering the surface of the substrate S, the processing fluid dissolves into the liquid, reducing the surface tension of the liquid. By initially introducing the processing fluid as a gas into the processing chamber 412, the surface tension of the liquid is reduced, which improves the substitution efficiency when introducing the supercritical processing fluid.

[0103] According to the inventor's experiments, when a supercritical fluid with a pressure of 11 MPa was directly introduced into the processing chamber 412, or when the pressure of the gas introduced beforehand was 4-5 MPa, processing defects that damaged the substrate sometimes occurred. On the other hand, when the gas pressure (first pressure P1) was set to 6 MPa, such processing defects could be effectively suppressed. Increasing the pressure further would actually increase 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 increases the pressure from atmospheric pressure Pa to the first pressure P1 is greater than the pressure difference when the supercritical processing fluid increases 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 by more than half of the pressure difference from atmospheric pressure Pa to the final target second pressure P2. In this way, liquefaction and solidification that can occur when introducing a processing fluid with a large pressure difference are avoided.

[0105] In this embodiment, the gaseous and liquid processing fluids are switched by selectively opening valves V75 and V76, and the piping group 740 is shared as the flow path for both. This simplifies the piping configuration and reduces the inclusion of impurities caused by the piping system, including the valves.

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

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

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

[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. Also, heaters 725 and 726 correspond to the "first heater" of the present invention, while heater 719 corresponds to the "second heater" of the present invention. In addition, valve V74 functions as the "third valve" of the present invention, and piping 733 functions as the "recirculation piping" of the present invention.

[0110] It should be noted that the present invention is not limited to the embodiments described above, and various modifications can be made without departing from the spirit of the invention. For example, the fluid supply unit 457 of the above embodiment includes many components that are commonly provided in the flow path of the processed fluid, such as flow meters and filters, but are not directly related to the present invention. The present invention can still be established even if these are omitted.

[0111] Furthermore, in the above embodiment, for example, the introduction of the processing fluid into the processing chamber 412 and the discharge of the processing fluid from the processing chamber 412 are performed separately for the upper and lower sides of the support tray 415, respectively. However, this is not a mandatory requirement.

[0112] Furthermore, in the above embodiment, the gaseous and liquid processing fluids are taken 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 processing of the above embodiments are merely examples, and various other substances can be used as substitutes, as long as they are consistent with the technical concept of the present invention as described above.

[0114] As described above with specific embodiments, in the substrate processing apparatus according to the present invention, the control unit may be configured to, for example, open the first valve to fill the internal space with a processing fluid at a first pressure, then close the first valve and open the second valve to fill the internal space with a processing fluid at a second pressure. With such a configuration, the switching from the processing fluid at the first pressure to the processing fluid at the second pressure can be reliably performed.

[0115] Alternatively, for example, the storage unit may be configured to store a liquid processing fluid pressurized to a first pressure, with a first pipe connected to communicate with the space above the liquid surface of the processing fluid, while a second pipe is connected to communicate with the space below the liquid surface, thereby functioning as a first supply unit by supplying the gaseous processing fluid above the liquid surface to the first pipe. With such a configuration, it becomes possible to store the processing fluid as both gas and liquid in a single storage unit, thereby simplifying the device configuration.

[0116] In this case, the pressurizing unit may be configured to pressurize the first-pressure processed fluid, which is sent from the storage unit to the second piping, up to the second pressure and output it. With such a configuration, the first-pressure processed fluid as a gas and the second-pressure processed fluid as a liquid can be supplied from a single storage unit.

[0117] For example, the second supply unit may be configured to have a return piping connected to a second pipe between the pressurizing unit and the second valve, and connected to the storage unit via a third valve. In this case, with the second valve closed and the third valve open by the control unit, the pressurizing unit may be configured to pressurize the processing fluid supplied from an external supply source and allow it to flow into the storage unit. With such a configuration, the processing fluid can be pressurized in the pressurizing unit before being stored in the storage unit, so the processing fluid itself supplied from further upstream may be at a lower pressure than the first pressure. In other words, the degree of freedom regarding the supply source of the processing fluid is increased.

[0118] Alternatively, for example, a first heater may be provided to heat the processing fluid flowing from the second pipe through the introduction channel. With such a configuration, it is possible to make the processing fluid supercritical by heating it and raising its temperature above the 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 such a configuration, the decrease in 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 discharged processing fluid can be stably maintained.

[0120] Alternatively, for example, the first pressure may be configured to be lower than the pressure at which the processed fluid liquefies at the temperature of the processed fluid delivered by the first supply unit. With such a configuration, the processed fluid delivered from the first supply unit can be reliably maintained in a gaseous state.

[0121] Furthermore, according to the inventors' knowledge, by sufficiently increasing the internal pressure of the processing chamber through gas introduction, liquefaction or solidification during the subsequent introduction of the critical processing fluid 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] This invention can be applied to all techniques for processing substrates using a supercritical processing fluid in a processing chamber. [Explanation of Symbols]

[0123] 4. Supercritical fluid 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 section) 717 Storage Tank (Storage Section, First Supply Section, Second Supply Section) 719 Heater (2nd Heater) 725,726 Heater (1st Heater) 732 Piping (Second Piping) 736 Piping (First Piping) 733 Piping (recirculation piping) 737 Piping (First Piping) 740 Piping Group (Inlet Channel) SP processing space (internal space) V74 valve (3rd valve) V75 valve (second valve) V76 Valve (1st Valve)

Claims

1. In a substrate processing apparatus that processes a substrate using a processing fluid in a supercritical state, A processing chamber having an internal space capable of accommodating the aforementioned substrate, A first supply unit supplies the processing fluid as a gas pressurized to a first pressure 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 channel that communicates with the internal space and introduces the processing fluid into the internal space, A first piping that connects the first supply unit and the introduction channel via a first valve, A second pipe connecting the second supply unit and the introduction channel via a second valve, A control unit that controls the first valve and the second valve to selectively introduce the processing fluid at the first pressure and the processing fluid at the second pressure into the internal space. Equipped with, The second supply unit is, A storage section for storing the liquid processing fluid, A pressurizing unit is inserted into the second piping leading from the storage unit to the second valve, and pressurizes the processing fluid to a second pressure before sending it out. A substrate processing apparatus having

2. The substrate processing apparatus according to claim 1, wherein the control unit opens the first valve to fill the internal space with the processing fluid at the first pressure, 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 liquid processing fluid pressurized to the first pressure is stored, and the first pipe is connected to communicate with the space above the liquid surface of the processing fluid, while the second pipe is connected to communicate with the space below the liquid surface. The substrate processing apparatus according to claim 1, wherein the gaseous processing fluid above the liquid surface is supplied 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 sent from the storage unit to the second pipe, to the second pressure and outputs it.

5. The substrate processing apparatus according to any one of claims 1 to 4, wherein the second supply unit has a recirculation pipe connected to the second piping between the pressurizing unit and the second valve, and connected to the storage unit via a third valve.

6. The substrate processing apparatus according to claim 5, wherein, with the second valve closed and the third valve open by the control unit, the pressurizing unit pressurizes the processing fluid supplied from an external supply source and causes it to flow into the storage unit.

7. A substrate processing apparatus according to any one of claims 1 to 4, further comprising a first heater for heating the processing fluid flowing from the second pipe through the introduction channel.

8. The substrate processing apparatus according to any one of claims 1 to 4, further comprising a second heater for heating the processing fluid stored in the storage section.

9. The substrate processing apparatus according to any one of claims 1 to 4, wherein the first pressure is lower than the pressure at which the processing fluid liquefies at the temperature of the processing fluid delivered by the first supply unit.

10. A substrate processing apparatus according to any one of claims 1 to 4, 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.

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