SUBSTRATE PROCESSING METHOD AND SUBSTRATE PROCESSING APPARATUS

Abstract

To provide technology that processes a substrate with a processing fluid in a supercritical state in a chamber, and can obtain stable processing efficiency especially when processing a plurality of substrates in order by appropriately controlling the temperature in the chamber after processing.SOLUTION: A substrate processing method according to the present invention includes a supercritical processing step of introducing a processing fluid into an internal space of a chamber storing a substrate and processing the substrate with the processing fluid in a supercritical state, a decompression step of discharging the processing fluid and decompressing the internal space, an unloading step of unloading the substrate from the chamber, and a temperature adjustment step of adjusting the temperature of the internal space to a target temperature by introducing and discharging the processing fluid into the internal space after the substrate is unloaded.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a technique for processing a substrate with a processing fluid in a supercritical state in a chamber, and more particularly to a process after the substrate has been processed with the supercritical processing fluid. [Background technology]

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

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

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

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

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

[0007] The present invention has been made in consideration of the above-mentioned problems, and aims to provide a technology for processing a substrate with a processing fluid in a chamber in a supercritical state, which can appropriately manage the temperature in the chamber after processing, thereby achieving stable processing efficiency, particularly when multiple substrates are processed in sequence. [Means for solving the problem]

[0008] One aspect of the present invention is a substrate processing method for processing a substrate with a processing fluid in a chamber in a supercritical state, and in order to achieve the above object, the method includes a supercritical processing step of introducing the processing fluid into an internal space of the chamber accommodating the substrate and processing the substrate with the processing fluid in a supercritical state, a depressurization step of discharging the processing fluid and depressurizing the internal space, a carrying-out step of unloading the substrate from the chamber, and a temperature adjustment step of adjusting a temperature of the internal space to a target temperature by introducing and discharging the processing fluid into the internal space after the substrate has been unloaded. In the temperature adjustment step, the processing fluid pressurized to a pressure higher than atmospheric pressure is adiabatically expanded in the internal space, thereby cooling a wall surface of the chamber facing the internal space. do.

[0009] Another aspect of the present invention is a substrate processing apparatus for processing a substrate with a processing fluid in a supercritical state, and in order to achieve the above object, the apparatus includes a chamber capable of accommodating the substrate in an internal space thereof, a fluid supply unit that supplies the processing fluid to the internal space of the chamber, a fluid discharge unit that discharges the processing fluid from the internal space, and a control unit that controls the fluid supply unit and the fluid discharge unit, and the control unit supplies a fluid to the internal space after the substrate that has been processed with the processing fluid is unloaded, Pressurized to higher than atmospheric pressure The processing fluid is supplied from the fluid supply unit and discharged to the fluid discharge unit. By this, adiabatic expansion is caused in the internal space, and a wall surface of the chamber facing the internal space is cooled. By this, a temperature adjustment process is executed to adjust the temperature of the internal space to a target temperature.

[0010] The "temperature of the internal space" here is a concept that refers to the temperature detected when a temperature measurement is performed in that space, but more specifically, it refers to the temperature of the wall surface of the chamber that faces the internal space. The reason why this can be considered will be explained later.

[0011] In the case of substrate processing using a processing fluid in a supercritical state, the inside of the chamber becomes hot, and the temperature may not drop sufficiently even after the processing fluid is discharged. In particular, in a process in which temperature control in the chamber at the end of the process is not taken into consideration, the temperature may differ from process to process. In this case, when multiple substrates are transported into the chamber in sequence and processed continuously, the processing results may vary due to the difference in initial temperature.

[0012] In view of this, in the invention configured as above, after the substrate is processed with the processing fluid, the processing fluid is introduced again into the chamber interior space, and the internal temperature is adjusted to a target temperature. In this way, since the temperature after processing of one substrate is completed is managed, it is possible to immediately load the next substrate into the chamber and process it thereafter. This improves the throughput of processing multiple substrates.

[0013] In addition, since the initial temperature in the processing of each substrate is stable, the processing results can also be stable. This is because the density of a supercritical fluid changes greatly with temperature, and differences in density cause large differences in processing efficiency. In the present invention, the initial temperature is stabilized, so that the temperature change in the subsequent processing is prevented from varying from process to process, making it possible to obtain stable processing results. Effect of the Invention

[0014] As described above, in the present invention, after the substrate processing is completed, the processing fluid is introduced and discharged again for the purpose of adjusting the temperature in the chamber. Therefore, the temperature in the chamber before the next substrate is loaded can be appropriately controlled, and even when a plurality of substrates are processed in sequence, the temperature variation of the supercritical processing fluid for each process can be suppressed, and stable processing efficiency can be obtained. [Brief description of the drawings]

[0015] [Figure 1] 1 is a diagram showing a schematic configuration of an embodiment of a substrate processing apparatus according to the present invention; [Diagram 2] 4 is a flowchart showing an outline of a process executed by the substrate processing apparatus. [Diagram 3] FIG. 2 is a diagram illustrating the operation of each part in supercritical processing. [Figure 4] 13 is a flowchart showing a temperature adjustment process. [Diagram 5] FIG. 4 is a diagram showing a schematic diagram of changes in pressure and temperature during a temperature adjustment process. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0016] Fig. 1 is a diagram showing a schematic configuration of one embodiment of a substrate processing apparatus according to the present invention. This substrate processing apparatus 1 is an apparatus for processing the surface of various substrates, such as semiconductor substrates, by using a supercritical fluid, and has an apparatus configuration suitable for carrying out a substrate processing method according to the present invention. In order to unify directions in the following description, an XYZ Cartesian coordinate system is set as shown in Fig. 1. Here, the XY plane is a horizontal plane, and the Z direction represents the vertical direction. More specifically, the (-Z) direction represents the vertical downward direction.

[0017] As the "substrate" in this embodiment, various substrates such as semiconductor wafers, glass substrates for photomasks, glass substrates for liquid crystal displays, glass substrates for plasma displays, substrates for FEDs (Field Emission Displays), substrates for optical disks, substrates for magnetic disks, and substrates for magneto-optical disks can be applied. In the following, a substrate processing apparatus used mainly for processing disc-shaped semiconductor wafers will be described with reference to the drawings. However, the present invention can be applied to the processing of the various substrates exemplified above. Various substrate shapes can also be applied.

[0018] The substrate processing apparatus 1 includes a processing unit 10, a transfer unit 30, a supply unit 50, and a control unit 90. The processing unit 10 is a main body that executes the supercritical drying process. The transfer unit 30 receives an unprocessed substrate S transported by an external transport device (not shown) and transports it into the processing unit 10, and also transfers the processed substrate S from the processing unit 10 to the external transport device. The supply unit 50 supplies chemical substances, power, energy, etc. required for processing to the processing unit 10 and the transfer unit 30.

[0019] The control unit 90 controls each part of these devices to realize predetermined processing. For this purpose, the control unit 90 is equipped with a CPU 91, a memory 92, a storage 93, an interface 94, and the like. The CPU 91 executes various control programs. The memory 92 temporarily stores processing data. The storage 93 stores the control programs executed by the CPU 91. The interface 94 exchanges information with a user and an external device. The operation of the devices described below is realized by the CPU 91 executing the control programs written in advance in the storage 93 and causing each part of the devices to perform a predetermined operation.

[0020] The processing unit 10 has a structure in which a processing chamber 12 is attached on a base 11. The processing chamber 12 is constructed by combining several metal blocks, and its interior is hollow to form a processing space SP. The substrate S to be processed is loaded into the processing space SP and processed. A slit-shaped opening 121 that is elongated and extends in the X direction is formed on the (-Y) side surface of the processing chamber 12. The processing space SP communicates with the outside space via the opening 121. The cross-sectional shape of the processing space SP is approximately the same as the opening shape of the opening 121. In other words, the processing space SP has a cross-sectional shape that is long in the X direction and short in the Z direction, and is a cavity that extends in the Y direction.

[0021] A lid member 13 is provided on the (-Y) side surface of the processing chamber 12 so as to close the opening 121. The lid member 13 closes the opening 121 of the processing chamber 12 to form an airtight processing container. This allows the substrate S to be processed under high pressure in the internal processing space SP. A flat support tray 15 is attached in a horizontal position to the (+Y) side surface of the lid member 13. An upper surface 151 of the support tray 15 serves as a support surface on which the substrate S can be placed. The lid member 13 is supported by a support mechanism (not shown) so as to be freely movable horizontally in the Y direction.

[0022] The lid member 13 can be moved forward and backward relative to the processing chamber 12 by an advance / retract mechanism 53 provided in the supply unit 50. Specifically, the advance / retract mechanism 53 has a linear motion mechanism such as a linear motor, a linear motion guide, a ball screw mechanism, a solenoid, an air cylinder, or the like. Such a linear motion mechanism moves the lid member 13 in the Y direction. The advance / retract mechanism 53 operates in response to a control command from the control unit 90.

[0023] When the cover member 13 moves in the (-Y) direction to move away from the processing chamber 12 and the support tray 15 is pulled out from the processing space SP through the opening 121 as shown by the dotted line, access to the support tray 15 becomes possible. That is, it becomes possible to place the substrate S on the support tray 15 and to remove the substrate S placed on the support tray 15. On the other hand, when the cover member 13 moves in the (+Y) direction, the support tray 15 is accommodated in the processing space SP. When the substrate S is placed on the support tray 15, the substrate S is carried into the processing space SP together with the support tray 15.

[0024] The lid member 13 moves in the (+Y) direction to close the opening 121, thereby sealing the processing space SP. A seal member 122 is provided between the (+Y) side surface of the lid member 13 and the (-Y) side surface of the processing chamber 12 to keep the processing space SP airtight. The seal member 122 is made of rubber, for example. The lid member 13 is fixed to the processing chamber 12 by a locking mechanism (not shown). Thus, in this embodiment, the lid member 13 can be switched between a closed state (solid line) in which the opening 121 is closed to seal the processing space SP, and a separated state (dotted line) in which the lid member 13 is significantly separated from the opening 121 to allow the substrate S to be inserted and removed.

[0025] With the airtight state of the processing space SP ensured, processing of the substrate S is performed in the processing space SP. In this embodiment, a processing fluid of a substance that can be used for supercritical processing, such as carbon dioxide, is delivered as the processing fluid from the fluid supply unit 57 provided in the supply unit 50. The processing fluid is supplied to the processing unit 10 in a gaseous, liquid or supercritical state. Carbon dioxide is a chemical substance suitable for supercritical drying processing in that it becomes supercritical at a relatively low temperature and pressure and has the property of dissolving organic solvents that are often used in substrate processing well. The critical point at which carbon dioxide becomes supercritical is an atmospheric pressure (critical pressure) of 7.38 MPa and a temperature (critical temperature) of 31.1°C.

[0026] The processing fluid is filled in the processing space SP, and when the processing space SP reaches an appropriate temperature and pressure, the processing space SP is filled with the processing fluid in a supercritical state. In this manner, the substrate S is processed by the supercritical fluid in the processing chamber 12. The supply unit 50 is provided with a fluid recovery part 55, and the fluid after processing is recovered by the fluid recovery part 55. The fluid supply part 57 and the fluid recovery part 55 are controlled by the control unit 90.

[0027] The processing space SP has a shape and volume capable of receiving the support tray 15 and the substrate S supported thereon. That is, the processing space SP has a roughly rectangular cross-sectional shape that is wider than the width of the support tray 15 in the horizontal direction and greater than the combined height of the support tray 15 and the substrate S in the vertical direction, and a depth capable of receiving the support tray 15. In this way, the processing space SP has a shape and volume sufficient to receive the support tray 15 and the substrate S. However, there is only a small gap between the support tray 15 and the substrate S and the inner wall surface of the processing space SP. Therefore, a relatively small amount of processing fluid is required to fill the processing space SP.

[0028] When the support tray 15 is accommodated in the processing space SP, the processing space SP is roughly divided into a space above and a space below the support tray 15. When the substrate S is placed on the support tray 15, the processing space SP is divided into a space above the upper surface of the substrate S and a space below the lower surface of the support tray 15.

[0029] The fluid supply unit 57 supplies the processing fluid to each of the space above the substrate S in the processing space SP and the space below the support tray 15, further on the (+Y) side than the (+Y) side end of the substrate S. Meanwhile, the fluid recovery unit 55 discharges the processing fluid from each of the space above the substrate S in the processing space SP and the space below the support tray 15, further on the (-Y) side than the (-Y) side end of the substrate S. As a result, a laminar flow of the processing fluid from the (+Y) side toward the (-Y) side is formed above the substrate S and below the support tray 15 in the processing space SP.

[0030] Detectors 173, 174 for detecting the pressure and temperature of the processing fluid discharged from the processing space SP are provided on the piping that serves as a discharge path for the processing fluid from the processing space SP to the fluid recovery unit 55. Specifically, a first detector 173 is provided on the piping that communicates with a space in the processing space SP above the support tray 15 and discharges the processing fluid from the space, and a second detector 174 is provided on the piping that communicates with a space below the support tray 15 and discharges the processing fluid from the space.

[0031] The detection units 173, 174 detect the pressure and temperature of the processing space SP, and in this sense, it is desirable to provide them inside the processing space SP. In particular, with regard to temperature, it would be ideal if the temperature of the chamber inner wall surface facing the processing space SP could be detected. However, it is necessary to avoid impeding the smooth flow of the processing fluid or becoming a source of contamination for the processing fluid. For this reason, as a simple alternative method, the detection units 173, 174 are provided in the processing fluid flow path that communicates with the processing space SP downstream of the substrate S in the flow direction of the processing fluid. That is, the detection results of the pressure and temperature of the processing fluid flowing through this flow path are considered to be the pressure and temperature of the processing space SP.

[0032] For this purpose, it is desirable that the piping constituting the flow path of the processing fluid from the processing space SP to the detection units 173 and 174 has a small pressure loss. Furthermore, as long as it does not affect the flow of the processing fluid, the detection unit may be disposed so as to directly face the processing space SP.

[0033] The control unit 90 determines the pressure and temperature in the processing space SP based on the outputs of the detection units 173, 174, and controls the fluid supply unit 57 and the fluid recovery unit 55 based on the results. This appropriately manages the supply of the processing fluid to the processing space SP and the discharge of the processing fluid from the processing space SP, and adjusts the pressure and temperature in the processing space SP in accordance with a predetermined processing recipe.

[0034] The transfer unit 30 is responsible for transferring the substrate S between an external transport device and the support tray 15. For this purpose, the transfer unit 30 includes a main body 31, a lifting member 33, a base member 35, and a plurality of lift pins 37. The lifting member 33 is a columnar member extending in the Z direction, and is supported by a support mechanism (not shown) so as to be movable in the Z direction relative to the main body 31. A base member 35 having a substantially horizontal upper surface is attached to the upper portion of the lifting member 33. A plurality of lift pins 37 are erected upward from the upper surface of the base member 35. Each of the lift pins 37 supports the substrate S in a horizontal position from below by abutting its upper end portion against the lower surface of the substrate S. In order to stably support the substrate S in a horizontal position, it is desirable to provide three or more lift pins 37 whose upper ends have the same height.

[0035] The lifting member 33 can be moved up and down by a lifting mechanism 51 provided in the supply unit 50. Specifically, the lifting mechanism 51 has a linear motion mechanism such as a linear motor, a linear motion guide, a ball screw mechanism, a solenoid, an air cylinder, etc., and such a linear motion mechanism moves the lifting member 33 in the Z direction. The lifting mechanism 51 operates in response to a control command from the control unit 90.

[0036] The base member 35 moves up and down by the lifting member 33 moving up and down, and the multiple lift pins 37 move up and down integrally therewith. This allows the transfer of the substrate S between the transfer unit 30 and the support tray 15. More specifically, as shown by the dotted line in FIG. 1, the substrate S is transferred in a state in which the support tray 15 is pulled out of the chamber. For this purpose, the support tray 15 is provided with through holes 152 for inserting the lift pins 37. When the base member 35 moves up, the upper ends of the lift pins 37 reach a position higher than the support surface 151 of the support tray 15 through the through holes 152. In this state, the substrate S transferred by an external transfer device is transferred to the lift pins 37. When the lift pins 37 move down, the substrate S is transferred from the lift pins 37 to the support tray 15. The substrate S can be removed by reversing the above procedure.

[0037] FIG. 2 is a flow chart showing an outline of the process executed by this substrate processing apparatus. This substrate processing apparatus 1 executes a supercritical drying process, that is, a process for drying a substrate S that has been cleaned with a cleaning liquid in a pre-process. Specifically, the process is as follows. The substrate S to be processed is cleaned with a cleaning liquid in a pre-process executed in another substrate processing apparatus constituting a substrate processing system. Thereafter, the substrate S is transported to the substrate processing apparatus 1 with a liquid film formed on its surface using an organic solvent such as isopropyl alcohol (IPA).

[0038] For example, if a fine pattern is formed on the surface of the substrate S, the surface tension of the liquid remaining on the substrate S may cause the pattern to collapse. Also, watermarks may remain on the surface of the substrate S due to incomplete drying. Furthermore, exposure of the surface of the substrate S to the outside air may cause deterioration such as oxidation. To prevent such problems from occurring, the surface of the substrate S (the surface on which the pattern is formed) may be transported while covered with a liquid or solid surface layer.

[0039] For example, when the cleaning liquid is mainly composed of water, the substrate is transported in a state in which a liquid film is formed using a liquid having a lower surface tension and a lower corrosiveness to the substrate, such as an organic solvent such as IPA or acetone, etc. In other words, the substrate S is supported horizontally and transported to the substrate processing apparatus 1 in a state in which a liquid film is formed on its upper surface.

[0040] The substrate S transported by a transport device (not shown) is accommodated in the processing chamber 12 (step S101). Specifically, the substrate S is transported with the pattern-formed surface facing up and covered with a thin liquid film. As shown by the dotted line in FIG. 1, the lift pins 37 rise while the cover member 13 moves to the (-Y) side and the support tray 15 is pulled out. The transport device transfers the substrate S to the lift pins 37. The lift pins 37 are lowered, so that the substrate S is placed on the support tray 15. When the support tray 15 and the cover member 13 move together in the (+Y) direction, the support tray 15 supporting the substrate S is accommodated in the processing space SP in the processing chamber 12, and the opening 121 is closed by the cover member 13.

[0041] In this state, carbon dioxide as a processing fluid is introduced in a gas phase into the processing space SP (step S102). When the substrate S is loaded, outside air enters the processing space SP, but this can be replaced by introducing the gas phase processing fluid. Furthermore, the pressure inside the processing chamber 12 increases as the gas phase processing fluid is injected.

[0042] During the process of introducing the processing fluid, the processing fluid is continuously discharged from the processing space SP. That is, even while the processing fluid is being introduced by the fluid supply unit 57, the processing fluid is discharged from the processing space SP by the fluid recovery unit 55. This allows the processing fluid used for processing to be discharged without convection into the processing space SP, and prevents impurities such as residual liquid that have been taken in the processing fluid from adhering again to the substrate S.

[0043] If the supply rate of the processing fluid is greater than the discharge rate, the density of the processing fluid in the processing space SP increases, and the pressure inside the chamber increases. Conversely, if the supply rate of the processing fluid is less than the discharge rate, the density of the processing fluid in the processing space SP decreases, and the pressure inside the chamber is reduced. The supply of the processing fluid to the processing chamber 12 and the discharge of the processing fluid from the processing chamber 12 are performed based on a supply and discharge recipe created in advance. That is, the control unit 90 controls the fluid supply unit 57 and the fluid recovery unit 55 based on the supply and discharge recipe, thereby adjusting the supply and discharge timing and the flow rate of the processing fluid.

[0044] When the pressure of the processing fluid in the processing space SP increases and exceeds the critical pressure, the processing fluid becomes supercritical in the chamber. That is, the processing fluid transitions from the gas phase to the supercritical state due to a phase change in the processing space SP. The processing fluid in the supercritical state may be supplied from the outside. By introducing the supercritical fluid into the processing space SP, the organic solvent such as IPA covering the substrate S is replaced by the supercritical fluid. The organic solvent liberated from the surface of the substrate S is discharged from the processing chamber 12 together with the processing fluid in a state dissolved in the processing fluid, and is removed from the substrate S. That is, the processing fluid in the supercritical state has the function of replacing the organic solvent adhering to the substrate S as the replacement target liquid and discharging it outside the processing chamber 12. By continuing the state in which the processing space SP is filled with the processing fluid in the supercritical state for a predetermined time (step S103), the replacement target liquid adhering to the substrate S can be completely replaced and discharged outside the chamber.

[0045] When the replacement of the liquid to be replaced with the supercritical fluid in the processing chamber 12 is completed (step S104), the processing fluid in the processing space SP is discharged to dry the substrate S. Specifically, the amount of fluid discharged from the processing space SP is increased to reduce the pressure inside the processing chamber 12 filled with the processing fluid in a supercritical state (step S105).

[0046] In the depressurization process, the supply of the processing fluid may be stopped, or a small amount of the processing fluid may be continuously supplied. By depressurizing the processing space SP from a state filled with supercritical fluid, the processing fluid changes phase from the supercritical state to a gas phase. By discharging the vaporized processing fluid to the outside, the substrate S becomes a dry state. At this time, the depressurization speed is adjusted so that a solid phase and a liquid phase are not generated due to a sudden temperature drop. As a result, the processing fluid in the processing space SP is directly vaporized from the supercritical state and discharged to the outside. Therefore, the formation of a gas-liquid interface on the substrate S with the surface exposed after drying is avoided.

[0047] As described above, in the supercritical drying process of this embodiment, the processing space SP is filled with a processing fluid in a supercritical state, and then the processing fluid is changed into a gas phase and discharged, thereby efficiently replacing the liquid adhering to the substrate S and preventing it from remaining on the substrate S. Moreover, the substrate can be dried while avoiding problems caused by the formation of a gas-liquid interface, such as contamination of the substrate due to the adhesion of impurities and pattern collapse.

[0048] After processing, the substrate S is discharged to a subsequent process (step S106). That is, the support tray 15 is drawn out from the processing chamber 12 by moving the cover member 13 in the (-Y) direction, and the substrate S is transferred to an external transport device via the transfer unit 30. At this time, the substrate S is in a dry state. The content of the subsequent process is arbitrary. If there is no substrate to be processed next (NO in step S107), the process ends. If there is another substrate to be processed (YES in step S107), the temperature adjustment process (step S108) described below is performed, and then the process returns to step S101 to accept a new substrate S, and the above process is repeated.

[0049] When processing of the next substrate S is to be performed after processing of one substrate S is completed, the tact time can be shortened by doing the following: After the support tray 15 is pulled out and the processed substrate S is taken out, a new unprocessed substrate S is placed on it, and then the support tray 15 is housed in the processing chamber 12. In addition, by reducing the number of times the cover member 13 is opened and closed in this manner, it is possible to obtain the effect of suppressing temperature changes in the processing chamber 12 caused by the entry of outside air.

[0050] Next, the temperature adjustment process of step S108 will be described. The density of a fluid in a supercritical state changes greatly with temperature. Specifically, the lower the temperature of the fluid, the higher the density, and even a slight increase in temperature causes a large decrease in density. In light of the purpose of supercritical processing, which is to replace the liquid remaining on the substrate with a supercritical processing fluid, it is desirable to perform processing with a high-density processing fluid that can take in more liquid.

[0051] However, the inside of the chamber is hot after processing, and if no temperature control is performed, the temperature may vary from process to process. If a new substrate is received and processed in this state, the temperature of the processing fluid introduced may change significantly, resulting in problems such as poor processing results and different processing quality for each substrate.

[0052] To solve this problem, in this embodiment, after the supercritical processing of one substrate is completed, the temperature adjustment process described below is performed to adjust the temperature inside the chamber to the target temperature before a new substrate is accepted.

[0053] Fig. 3 is a diagram showing a schematic diagram of the operation of each part in the supercritical processing. Fig. 4 is a flowchart showing the temperature adjustment processing. When the processing of one substrate with the supercritical processing fluid is completed (step S105 in Fig. 2), the substrate S is accommodated in the processing space SP while being supported by the support tray 15, as shown in Fig. 3(a). In step S106, as shown in Fig. 3(b), the cover member 13 moves in the (-Y) direction, and the support tray 15 is pulled out, and the substrate S is carried out to the outside, for example, by the hand H of a transport robot (not shown).

[0054] In the temperature adjustment process performed after the substrate is unloaded, the cover member 13 is closed as shown in Fig. 3(c), thereby blocking the processing space SP containing the support tray 15 without the substrate S placed thereon (step S201). Then, as shown in Fig. 3(d), the fluid supply unit 57 supplies a processing fluid into the processing space SP based on a predetermined supply and discharge recipe, and the fluid recovery unit 55 discharges the processing fluid from the processing space SP, thereby cooling the processing space SP (step S204).

[0055] The processing fluid is introduced at this time for the purpose of cooling the processing chamber 12 and lowering the temperature inside the chamber. The temperature of the processing space SP is detected when a temperature detector is installed in the processing space SP and is measured, and can be typically represented by, for example, the temperature of the chamber inner wall surface facing the processing space SP. The processing chamber 12 is required to be resistant to high pressure, and is formed, for example, from a thick metal block. Therefore, the heat capacity is large, and due to radiation and conduction from the wall surface, the temperature detected in the processing space SP is considered to be approximately equal to the temperature of the wall surface.

[0056] However, since it may be a source of contamination for the substrate to be processed, it may be difficult to arrange the temperature detector facing the processing space SP. In this case, the temperature detector is provided in a space communicating with the processing space SP, particularly in the space downstream of the substrate S in the flow direction of the processing fluid, and the temperature of the fluid filling this space can be simply regarded as the temperature of the processing space SP. The detection units 173, 174 of this embodiment are suited to such a purpose.

[0057] The simplest method of adjusting the temperature of the processing space SP to a target temperature using a processing fluid is to supply the processing space SP with a processing fluid whose temperature has been adjusted based on the target temperature. In general, a processing fluid with a lower temperature is supplied from inside the chamber to cool the chamber that has become hot. By circulating a sufficient amount of processing fluid, it is possible to bring the temperature of the chamber inner wall surface facing the processing space SP close to the target temperature.

[0058] However, the temperature inside the chamber after processing is not necessarily constant, and it is not practical to adjust the temperature of the processing fluid in order to cool the inside of the chamber. Therefore, in this embodiment, the processing space SP is filled with pressurized processing fluid, and then the processing chamber 12 is cooled by utilizing the temperature drop caused by adiabatic expansion during pressure reduction.

[0059] Specifically, the temperature inside the chamber is acquired (step S202), a supply and exhaust recipe is determined based on the result (step S203), and the supply (step S204) and exhaust (step S205) of the processing fluid to the processing space SP are controlled based on the determined supply and exhaust recipe, thereby adjusting the temperature inside the chamber.

[0060] By creating an oversupply state in which the supply rate of the processing fluid to the processing space SP is greater than the discharge rate, the processing fluid is pressurized and compressed in the processing space SP, causing the temperature to rise. On the other hand, in an overdischarge state in which the discharge rate is greater than the supply rate, the processing space SP is depressurized. At this time, if the discharge rate is high, the processing fluid expands rapidly in the processing space SP, and the temperature drops due to adiabatic expansion. By rapidly lowering the temperature of the processing fluid in the processing space SP in this way, it is possible to cool the inner wall surface of the chamber.

[0061] 5 is a diagram showing the change in pressure and temperature in the chamber during the temperature adjustment process. The temperature Te in the chamber at time T0 immediately after the substrate S is unloaded can take various values ​​for each process, but it is assumed to be higher than the target temperature Tt at the start of the next process. At this time, the pressure in the chamber is atmospheric pressure Pa.

[0062] At time T1, the supply of the processing fluid begins. The processing fluid at this time may be in either gas or liquid phase. When the processing fluid is introduced in an excess supply state, the processing fluid is compressed, and the pressure and temperature inside the chamber rise. After the pressure inside the chamber is maintained at the maximum pressure Pm for a certain period of time (times T2 to T3), the chamber is depressurized by making the chamber into an excess discharge state. The adiabatic expansion of the processing fluid causes a temperature drop, which also cools the inner wall surface of the chamber. The pressure is reduced until the temperature inside the chamber reaches the target temperature Tt (time T4). Eventually, a state is achieved in which the pressure inside the chamber is atmospheric pressure Pa and the temperature is the target temperature Tt.

[0063] Since this is simply an operation for adjusting the temperature inside the chamber, it is not necessary to make the processing fluid supercritical. Also, the period for maintaining the pressure constant may be short. The cooling of the processing chamber 12 in the temperature adjustment process is not intended to cool the entire processing chamber 12, but rather to cool the wall surface facing the processing space SP and the adjacent parts thereof to a degree that does not affect the temperature of the processing fluid introduced in the subsequent processing.

[0064] The temperature Te in the chamber at the start of the temperature adjustment process is not necessarily constant. Therefore, in order to make the final temperature the target temperature Tt regardless of the temperature Te at this time, it is necessary to change the supply and discharge recipe that specifies the supply and discharge of the processing fluid according to the temperature Te. For example, as shown by the dashed line in FIG. 4, if the supply and discharge recipe is changed to increase the maximum pressure Pm during pressure increase, the temperature rise in the chamber will be greater, which is effective, for example, when the temperature Te is relatively low. The same effect can be obtained by reducing the discharge speed of the processing fluid during pressure reduction to suppress the temperature drop due to adiabatic expansion.

[0065] 4, for example, when the discharge speed of the processing fluid is increased, the temperature drop due to adiabatic expansion becomes more significant, and the cooling effect of the processing chamber 12 becomes stronger. Therefore, it is effective when the temperature Te is relatively high. The same effect can be obtained by reducing the supply amount during pressure increase to suppress the temperature rise.

[0066] In this way, it is desirable that the supply and drainage recipe in the temperature adjustment process is changed according to the chamber temperature Te at the start of operation and the final target temperature Tt. In this embodiment, a plurality of supply and drainage recipes that define the supply speed and supply timing of the processing fluid to the processing space SP and the discharge speed and discharge timing of the processing fluid from the processing space SP are prepared in advance, and a supply and drainage recipe selected from them is executed based on the temperature acquisition result at the start of operation (steps S202 and S203), thereby making it possible to maintain the final chamber temperature at the target temperature Tt even if the temperature Te at the start of operation is different.

[0067] These supply and drainage recipes can be prepared by performing preliminary experiments in which the processing fluid is supplied to and drained from the closed processing space SP containing the support tray 15 not supporting the substrate S at various start-of-operation temperatures Te, and measuring the temperature change in the chamber at that time. From these, a supply and drainage recipe that can change the temperature Te from the start-of-operation temperature to the target temperature Tt can be selected. If the target temperature Tt is changeable, the supply and drainage recipe can be determined based on a combination of the start-of-operation temperature Te and the target temperature Tt.

[0068] In this way, the next substrate S is received with the temperature inside the chamber adjusted to the target temperature Tt, and the processing fluid is introduced, so that the temperature inside the chamber is stabilized at the start of processing, density changes caused by temperature changes in the processing fluid are suppressed, and stable processing quality can be obtained.

[0069] If the supercritical processing and the subsequent exhaust process are configured to keep the chamber temperature Te constant at the end of the processing, it is possible to execute the temperature adjustment process using a single supply / exhaust recipe determined by the temperature Te at that time and the target temperature Tt. In other words, in this case, steps S202 and S203 can be omitted.

[0070] As described above, in this embodiment, in consideration of the fact that the temperature inside the chamber becomes high after the supercritical processing and that the temperature is not constant, the processing fluid is supplied again into the chamber after the processing and then discharged, thereby optimizing the temperature inside the chamber. As a result, in this embodiment, it is possible to suppress the fluctuation in replacement efficiency caused by the large change in density of the processing fluid depending on the temperature, and to process multiple substrates with stable processing quality.

[0071] The temperature adjustment process is performed with the support tray 15 not supporting the substrates S housed in the processing space SP and the cover member 13 closing the opening 121. This allows the supplied processing fluid to be efficiently used for temperature adjustment, and also allows processing involving pressurization. Furthermore, not only the chamber inner wall surface facing the processing space SP, but also the support tray 15 can be adjusted to a target temperature.

[0072] As described above, in the substrate processing apparatus 1 of the above embodiment, the processing chamber 12 functions as the "chamber" of the present invention, and the opening 121 corresponds to the "opening" of the present invention. The processing space SP corresponds to the "internal space" of the present invention. The support tray 15 and the cover member 13 function as the "support tray" and the "cover" of the present invention, respectively. The fluid supply unit 57, the fluid recovery unit 55, and the control unit 90 function as the "fluid supply unit," the "fluid discharge unit," and the "control unit" of the present invention, respectively.

[0073] In the substrate processing method of the above embodiment (FIG. 2), steps S101 to S104 correspond to the "supercritical processing step" of the present invention, step S105 corresponds to the "pressure reduction step" of the present invention, step S106 corresponds to the "unloading step" of the present invention, and step S108 corresponds to the "temperature adjustment step" of the present invention.

[0074] The present invention is not limited to the above-mentioned embodiment, and various modifications can be made without departing from the spirit of the present invention. For example, in the above-mentioned embodiment, the temperature adjustment process is performed by selecting and applying an optimal supply and discharge recipe from among previously prepared recipes. Instead of this, for example, during the temperature adjustment process, a real-time control may be performed to bring the temperature in the chamber to the target temperature Tt by feedback control based on the temperature detection result of the processing fluid.

[0075] In the temperature adjustment process of the above embodiment, the processing fluid introduced into the processing space SP in a gas or liquid phase is not assumed to transition to a supercritical state, but may be discharged after transitioning to a supercritical state, for example, to shorten the processing time. At this time, since the substrate S is not present in the processing space SP, a phase change from the supercritical state to the liquid phase is allowed to occur.

[0076] In addition, the above embodiment does not mention the control of the initial temperature when processing the first substrate when processing multiple substrates in sequence. However, when considering the stability of the processing, it is desirable that the initial temperature at this time is also maintained at an appropriate temperature. For this purpose, and also to suppress temperature changes caused by disturbances, the substrate processing apparatus 1 may be further provided with a configuration for stabilizing temperature. For example, the temperature adjustment process of this embodiment may be performed before processing the first substrate, thereby optimizing the temperature inside the chamber. Also, for example, a heater may be provided on the surface or inside the processing chamber 12. Also, the support tray 15 may have a built-in heater.

[0077] In addition, the various chemical substances used in the treatment of the above-mentioned embodiments are only some examples, and various substances can be used instead as long as they are in accordance with the technical concept of the present invention described above.

[0078] As described above by way of example of specific embodiments, in the substrate processing method according to the present invention, for example, the temperature adjustment step can be configured to cool the wall surface of the chamber facing the internal space by adiabatic expansion of the processing fluid pressurized to a pressure higher than atmospheric pressure in the internal space. The temperature drop due to adiabatic expansion is a phenomenon that inevitably occurs in the depressurization step, but by performing depressurization control taking this into account, it can be utilized to adjust the temperature inside the chamber to a target temperature.

[0079] In this case, the discharge speed of the processing fluid when it is discharged from the internal space can be set based on, for example, the target temperature or the temperature of the internal space immediately before the processing fluid is introduced. The cooling effect due to adiabatic expansion can be controlled by the discharge speed of the processing fluid from the internal space. Therefore, it is reasonable to set the discharge speed based on at least one of the temperature at the start of processing and the target temperature to be finally reached.

[0080] More specifically, for example, a plurality of supply and discharge recipes that define the change in the introduction and discharge of the processing fluid into and from the internal space are set in advance, and in the temperature adjustment process, the introduction and discharge of the processing fluid into and from the internal space can be controlled based on one supply and discharge recipe selected based on the temperature of the internal space immediately before the processing fluid is introduced. With this configuration, even if the temperature of the processing space before the temperature adjustment is not constant, it is possible to finally adjust it to a target temperature.

[0081] As another method, in the temperature adjustment step, a processing fluid whose temperature has been adjusted according to a target temperature can be introduced into the internal space. More specifically, a processing fluid whose temperature is lower than the temperature of the internal space can be introduced to cool the wall surface of the chamber facing the internal space. In this way, in addition to the method using adiabatic expansion, it is possible to adjust the temperature by making the processing fluid act as a heat transport medium.

[0082] Furthermore, after the temperature adjustment step, a new unprocessed substrate is received and the supercritical processing step is performed, thereby making it possible to process a plurality of substrates in sequence. By performing the temperature adjustment step, the temperature of the internal space of the chamber is maintained at a target temperature, so that the processing quality of the supercritical processing step performed thereafter can be maintained good and stable. Thus, the present invention has a particularly remarkable effect when a plurality of substrates are processed in sequence using a supercritical processing fluid.

[0083] Furthermore, the substrate processing apparatus according to the present invention may be configured, for example, such that an opening communicating with the internal space and through which the substrate can pass is provided on the side of the chamber, and further includes a lid for opening and closing the opening, and in the temperature adjustment process, the processing fluid is introduced with the opening closed by the lid after the substrate is unloaded. With such a configuration, by introducing the processing fluid into the closed space formed by closing the opening, processing involving pressurization can be performed, and the processing fluid can be used efficiently. Furthermore, since the substrate is not present in the processing space, processing conditions can be determined without being restricted by the effect on the substrate.

[0084] In addition, for example, a support tray that supports the substrate in a horizontal position and can enter the internal space through the opening may be further provided, and the temperature adjustment process may be performed with the support tray housed in the internal space. With this configuration, the support tray can also be adjusted to the same temperature.

[0085] In this case, the support tray may further be attached to the lid. With this configuration, the support tray can be moved integrally with the lid into and out of the processing space by moving the lid toward and away from the opening. [Industrial Applicability]

[0086] The present invention can be applied to any process for processing a substrate using a processing fluid introduced into a chamber, for example, single-wafer substrate processing in which substrates such as semiconductor substrates are processed one by one in sequence using a supercritical fluid. [Explanation of symbols]

[0087] 1. Substrate Processing Equipment 12 Processing chamber (chamber) 13 Lid member (lid part) 15 Support Tray 55 Fluid recovery section (fluid discharge section) 57 Fluid supply section 90 Control unit (control section) 121 Aperture 173,174 Detector S-substrate S102~S104 Supercritical processing process S105 Decompression process S106 Unloading process S108 Temperature adjustment process SP Processing space (internal space)

Claims

1. 1. A substrate processing method for processing a substrate with a processing fluid in a supercritical state in a chamber, comprising: a supercritical processing step of introducing the processing fluid into an internal space of the chamber containing the substrate and processing the substrate with the processing fluid in a supercritical state; a depressurization step of discharging the processing fluid and depressurizing the internal space; a step of unloading the substrate from the chamber; a temperature adjustment step of adjusting a temperature of the internal space to a target temperature by introducing and discharging the processing fluid into the internal space after the substrate is unloaded; Equipped with In the temperature adjustment step, the processing fluid pressurized to a pressure higher than atmospheric pressure is adiabatically expanded in the internal space, thereby cooling a wall surface of the chamber facing the internal space.

2. The substrate processing method according to claim 1 , wherein in the temperature adjusting step, a discharge rate at which the processing fluid is discharged from the internal space is set based on the target temperature.

3. 2. The substrate processing method according to claim 1, wherein in the temperature adjusting step, a discharge rate at which the processing fluid is discharged from the internal space is set based on a temperature of the internal space immediately before the processing fluid is introduced.

4. 2. The substrate processing method of claim 1, wherein a plurality of supply / drain recipes are pre-set, each defining a manner in which the processing fluid is introduced into and discharged from the internal space, and in the temperature adjustment process, the introduction and discharge of the processing fluid into and from the internal space are controlled based on one of the supply / drain recipes selected based on the temperature of the internal space immediately before the processing fluid is introduced.

5. The substrate processing method according to claim 1 , wherein the temperature adjusting step includes introducing the processing fluid, the temperature of which is adjusted in accordance with the target temperature, into the internal space.

6. 6. The substrate processing method according to claim 5, further comprising the step of introducing the processing fluid having a temperature lower than that of the internal space to cool a wall surface of the chamber facing the internal space.

7. 7. The substrate processing method according to claim 1, further comprising the steps of: receiving a new unprocessed substrate and performing the supercritical processing step after the temperature adjustment step, thereby processing a plurality of the substrates in sequence.

8. 1. A substrate processing apparatus for processing a substrate with a processing fluid in a supercritical state, a chamber capable of accommodating the substrate in an internal space; a fluid supply unit that supplies the processing fluid to an internal space of the chamber; a fluid discharge portion that discharges the processing fluid from the internal space; a control unit for controlling the fluid supply unit and the fluid discharge unit; Equipped with The control unit performs a temperature adjustment process to adjust the temperature of the internal space to a target temperature by supplying the processing fluid pressurized to a pressure higher than atmospheric pressure from the fluid supply unit to the internal space after the substrate treated with the processing fluid is removed and discharging it to the fluid discharge unit, thereby causing adiabatic expansion in the internal space and cooling a wall surface of the chamber facing the internal space.

9. an opening communicating with the internal space and through which the substrate can pass is provided on a side surface of the chamber; Further comprising a lid portion for opening and closing the opening, The substrate processing apparatus according to claim 8 , wherein in the temperature adjustment process, after the substrate is unloaded, the processing fluid is introduced in a state in which the opening is closed by the lid portion.

10. a support tray that supports the substrate in a horizontal position and is capable of entering the internal space through the opening, The substrate processing apparatus according to claim 9 , wherein the temperature adjustment process is performed with the support tray accommodated in the internal space.

11. The substrate processing apparatus of claim 10 , wherein the support tray is attached to the lid.

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