Substrate processing device and substrate processing method

Abstract

A substrate processing device according to one aspect of the present disclosure comprises: a processing container that accommodates a substrate; a supply source that supplies a processing fluid into the processing container; a fluid supply path that connects the supply source and the processing container; a temperature adjustment unit that is provided in the fluid supply path and adjusts the temperature of the processing fluid; a pressure adjustment unit that adjusts the pressure inside the processing container; an opening / closing valve that is provided in the fluid supply path downstream of the temperature adjustment unit; a first temperature sensor that is provided in the fluid supply path downstream of the opening / closing valve; and a control circuit that controls the operation of the temperature adjustment unit. The control circuit controls at least one among the temperature adjustment unit and the pressure adjustment unit so that the temperature detected by the first temperature sensor is maintained at a critical temperature or higher.

Description

Substrate processing apparatus and substrate processing method

[0001] The present disclosure relates to a substrate processing apparatus and a substrate processing method.

[0002] A technique for drying a substrate using a supercritical fluid is known. Patent Document 1 discloses a configuration for switching the temperature of the supercritical fluid supplied to the substrate.

[0003] Japanese Patent Application Laid-Open No. 2021-086857

[0004] The present disclosure provides a technique that can suppress the generation of particles.

[0005] A substrate processing apparatus according to one aspect of the present disclosure includes a processing vessel for accommodating a substrate, a supply source for supplying a processing fluid into the processing vessel, a fluid supply path connecting the supply source and the processing vessel, a temperature adjustment unit provided in the fluid supply path for adjusting the temperature of the processing fluid, a pressure adjustment unit for adjusting the pressure within the processing vessel, an on-off valve provided in the fluid supply path downstream of the temperature adjustment unit, a first temperature sensor provided in the fluid supply path downstream of the on-off valve, and a control circuit for controlling the operation of the temperature adjustment unit, wherein the control circuit controls at least one of the temperature adjustment unit and the pressure adjustment unit so that the temperature detected by the first temperature sensor is maintained above a critical temperature.

[0006] According to the present disclosure, generation of particles can be suppressed.

[0007] FIG. 1 is a diagram showing a substrate processing apparatus according to a first embodiment. FIG. 2 is a flowchart showing a substrate processing method according to the first embodiment. FIG. 3 is a diagram showing pressure changes in a processing vessel in the substrate processing method of FIG. 2. FIG. 4 is a diagram showing a substrate processing apparatus according to a second embodiment. FIG. 5 is a flowchart showing a substrate processing method according to the second embodiment. FIG. 6 is a diagram showing pressure changes in a processing vessel in the substrate processing method of FIG. 5. FIG. 7 is a diagram (1) showing temperature changes of a processing fluid in a fluid supply path. FIG. 8 is a diagram (2) showing temperature changes of a processing fluid in a fluid supply path. FIG. 9 is a diagram for explaining pattern collapse.

[0008] Hereinafter, non-limiting exemplary embodiments of the present disclosure will be described with reference to the accompanying drawings. In all the accompanying drawings, the same or corresponding reference numerals are used to designate the same or corresponding members or components, and redundant descriptions will be omitted.

[0009] First Embodiment (Substrate Processing Apparatus) A substrate processing apparatus 10 according to a first embodiment will be described with reference to Fig. 1. Fig. 1 is a view showing the substrate processing apparatus 10 according to the first embodiment.

[0010] The substrate processing apparatus 10 includes a processing section 11, a supply section 12, a discharge section 13, and a control section 14.

[0011] The processing unit 11 has a processing vessel 111 and a holding unit 112. The processing vessel 111 is a vessel having a processing space formed therein that can accommodate a substrate W having a diameter of, for example, 300 mm. The substrate W may be, for example, a semiconductor wafer. The holding unit 112 is provided inside the processing vessel 111. The holding unit 112 holds the substrate W horizontally. The holding unit 112 is, for example, configured integrally with the processing vessel 111. The holding unit 112 may also be a holding plate configured separately from the processing vessel 111. The processing unit 11 has a temperature sensor T14 and a pressure sensor P14. The temperature sensor T14 detects the temperature inside the processing vessel 111. The pressure sensor P14 detects the pressure inside the processing vessel 111.

[0012] The supply unit 12 includes a fluid supply source S11 and a fluid supply path L11.

[0013] The fluid supply source S11 is a supply source of a processing fluid. The processing fluid is, for example, carbon dioxide (CO ２ ) may be.

[0014] The fluid supply path L11 is connected to a fluid supply source S11 at its upstream end and to a processing vessel 111 at its downstream end. The fluid supply path L11 is provided with a heating mechanism HE11, a temperature sensor T11, an on-off valve V11, an orifice OR11, a temperature sensor T13, and a pressure sensor P13, in this order from upstream to downstream. A line heater LH11 is provided downstream of the heating mechanism HE11 in the fluid supply path L11. On-off valves, temperature sensors, pressure sensors, and filters may also be provided at various positions on the fluid supply path L11. The filter filters the processing fluid flowing through the fluid supply path L11 and removes foreign matter contained in the processing fluid. This prevents particles from being generated on the surface of the substrate W during substrate processing using the processing fluid.

[0015] The heating mechanism HE11 heats the processing fluid supplied from the fluid supply source S11 and supplies the heated fluid downstream.

[0016] The temperature sensor T11 is provided in the fluid supply path L11 downstream of the heating mechanism HE11 and upstream of the on-off valve V11. The temperature sensor T11 detects the temperature of the processing fluid flowing through the fluid supply path L11.

[0017] The on-off valve V11 is a valve that switches the flow of the processing fluid on and off. When the on-off valve V11 is open, the processing fluid flows to the downstream orifice OR11, and when it is closed, the processing fluid does not flow to the downstream orifice OR11.

[0018] The orifice OR11 has a function of reducing the flow velocity of the processing fluid and adjusting the pressure thereof, and the orifice OR11 allows the processing fluid with the adjusted pressure to flow into the downstream processing vessel 111.

[0019] The temperature sensor T13 is provided in the fluid supply path L11 downstream of the orifice OR11 and upstream of the processing vessel 111. The temperature sensor T13 detects the temperature of the processing fluid flowing through the fluid supply path L11 immediately before the processing vessel 111.

[0020] The pressure sensor P13 is provided in the fluid supply path L11 downstream of the orifice OR11 and upstream of the processing vessel 111. The pressure sensor P13 detects the pressure in the fluid supply path L11 immediately before the processing vessel 111.

[0021] The line heater LH11 heats the fluid supply path L11 downstream of the heating mechanism HE11. The line heater LH11 suppresses a decrease in temperature of the treatment fluid heated to the first temperature by the heating mechanism HE11 as it flows through the fluid supply path L11.

[0022] The discharge unit 13 has a discharge flow path L13. The discharge flow path L13 is connected to the processing vessel 111. An on-off valve V13 and a back pressure valve BV13 are provided in this order from upstream to downstream in the discharge flow path L13. A line heater LH13 is provided in the discharge flow path L13. On-off valves, temperature sensors, and pressure sensors may be further provided at various positions in the discharge flow path L13.

[0023] The on-off valve V13 is a valve that switches the flow of the treatment fluid on and off. When the on-off valve V13 is open, the treatment fluid flows to the downstream back pressure valve BV13, and when it is closed, the treatment fluid does not flow to the downstream back pressure valve BV13.

[0024] When the primary pressure of the discharge flow path L13 exceeds a set pressure, the back pressure valve BV13 adjusts the valve opening to allow the treatment fluid to flow to the secondary side, thereby maintaining the primary pressure at the set pressure. For example, the set pressure of the back pressure valve BV13 is adjusted by the control unit 14.

[0025] The line heater LH13 heats the exhaust flow path L13.

[0026] The control unit 14 receives measurement signals from various sensors (such as temperature sensors T11, T13, and T14, and pressure sensors P13 and P14) and transmits control signals to various functional elements. The control signals include, for example, open / close signals for the on-off valves V11 and V13, a set pressure signal for the back pressure valve BV13, and temperature signals for the line heaters LH11 and LH13.

[0027] The control unit 14 is, for example, a computer, and includes an arithmetic unit 141 and a storage unit 142. The storage unit 142 stores programs for controlling various processes executed in the substrate processing apparatus 10. The arithmetic unit 141 controls the operation of the substrate processing apparatus 10 by reading and executing the programs stored in the storage unit 142. The programs may be recorded on a computer-readable storage medium and installed from the storage medium into the storage unit 142 of the control unit 14. Examples of computer-readable storage media include a hard disk (HD), a flexible disk (FD), a compact disk (CD), a magnetic optical disk (MO), and a memory card.

[0028] 2 and 3, a substrate processing method executed using the substrate processing apparatus 10 will be described. The substrate processing method described below is automatically executed under the control of the control unit 14 based on the processing recipe and control program stored in the storage unit 142.

[0029] Fig. 2 is a flowchart showing the substrate processing method according to the first embodiment. Fig. 3 is a diagram showing pressure changes in the processing vessel 111 during the substrate processing method according to the first embodiment. In Fig. 3, the horizontal axis represents processing time, and the vertical axis represents the pressure in the processing vessel 111 detected by the pressure sensor P14.

[0030] 2, the substrate processing method according to the first embodiment includes a preparation step ST11, a pressure increase step ST12, a circulation step ST13, and a pressure reduction step ST14. Each step will be described below.

[0031] In the preparation step ST11, the substrate W is loaded into the processing container 111. The substrate W is subjected to a cleaning process, and is placed on the holder 112 in a state in which recesses of the pattern on the surface are filled with isopropyl alcohol (IPA).

[0032] The pressurization step ST12 is performed after the preparation step ST11. In the pressurization step ST12, the on-off valve V11 is opened, and the on-off valve V13 is closed. As a result, the processing fluid from the fluid supply source S11 is supplied into the processing vessel 111 via the fluid supply path L11. In the pressurization step ST12, the on-off valve V13 is closed, so the processing fluid does not flow out of the processing vessel 111. Therefore, as shown in FIG. 3 , the pressure in the processing vessel 111 gradually increases. In the pressurization step ST12, the pressure of the processing fluid supplied into the processing vessel 111 is lower than the critical pressure. Therefore, the processing fluid is supplied into the processing vessel 111 in a gaseous state. Thereafter, as the processing vessel 111 is filled with the processing fluid, the pressure in the processing vessel 111 increases. When the pressure in the processing vessel 111 exceeds the critical pressure, the processing fluid present in the processing vessel 111 becomes supercritical. In the pressurizing step ST12, when the pressure inside the processing vessel 111 reaches a processing pressure higher than the critical pressure, the pressurizing step ST12 is terminated and the process proceeds to the flowing step ST13.

[0033] The flowing process ST13 is performed after the pressure increasing process ST12. In the flowing process ST13, the on-off valves V11 and V13 are opened. As a result, the processing fluid from the fluid supply source S11 is supplied into the processing container 111 via the fluid supply path L11. The processing fluid supplied into the processing container 111 is discharged from the processing container 111 via the discharge path L13. In the flowing process ST13, the processing fluid is simultaneously supplied into the processing container 111 and discharged from the processing container 111. Therefore, as shown in FIG. 3 , the pressure inside the processing container 111 is maintained substantially constant. By performing the flowing process ST13, replacement of the IPA with the processing fluid in the recesses of the pattern on the substrate W is promoted. When replacement of the IPA with the processing fluid in the recesses of the pattern is completed, the flowing process ST13 is terminated, and the process proceeds to the depressurization process ST14.

[0034] The depressurization step ST14 is performed after the flow step ST13. In the depressurization step ST14, the on-off valve V13 is opened and the on-off valve V11 is closed. As a result, the processing fluid is discharged from the processing vessel 111 without being supplied into the processing vessel 111. Therefore, as shown in FIG. 3, the pressure inside the processing vessel 111 gradually decreases. When the pressure inside the processing vessel 111 becomes lower than the critical pressure of the processing fluid by the depressurization step ST14, the processing fluid in the supercritical state vaporizes and escapes from the recesses of the pattern. This completes the drying process for one substrate W.

[0035] From the viewpoint of suppressing pattern collapse during the drying process, it is preferable to lower the temperature of the processing fluid, because if the temperature of the processing fluid is high, the heat of the processing fluid will increase the temperature of the IPA in the recesses before the IPA in the recesses is replaced with the processing fluid, causing part of the IPA to evaporate, which is likely to cause pattern collapse.

[0036] On the other hand, if the temperature of the processing fluid is too low, the processing fluid will turn into a liquid, which will cause particles to be generated. When the fluid supply source S11 supplies the processing fluid into the processing vessel 111 via the fluid supply path L11, an on-off valve V11, an orifice OR11, etc. are provided in the fluid supply path L11. The cross-sectional area of ​​the flow path is large immediately after the on-off valve V11 or immediately after the orifice OR11. Therefore, the processing fluid flowing through the fluid supply path L11 is likely to undergo adiabatic expansion and drop in temperature when it passes through the on-off valve V11 or the orifice OR11.

[0037] As a result of extensive research, the inventors have found that by maintaining the temperature of the processing fluid flowing through the fluid supply path L11 immediately before the processing vessel 111 at or above the critical temperature, it is possible to prevent the processing fluid from liquefying and suppress the generation of particles. ２ When CO is used, ２ The critical temperature of CO is about 30° C., and the CO ２ By maintaining the temperature at 30°C or higher, ２ This prevents the liquid from liquefying and suppresses the generation of particles.

[0038] Therefore, in the first embodiment, the control unit 14 controls at least one of the temperature adjustment unit and the pressure adjustment unit in the pressure increase step ST12 so that the temperature detected by the temperature sensor T13 is maintained at or above the critical temperature. In this case, liquefaction of the processing fluid flowing through the fluid supply path L11 downstream of the orifice OR11 can be prevented, thereby suppressing the generation of particles. This can suppress adhesion of particles to the surface of the substrate W in the processing vessel 111. The temperature adjustment unit includes, for example, a heating mechanism HE11. The temperature adjustment unit may also include a line heater LH11. The pressure adjustment unit includes, for example, a back pressure valve BV13.

[0039] The control unit 14 may control at least one of the temperature adjustment unit and the pressure adjustment unit so that the temperature detected by the temperature sensor T11 provided in the fluid supply path L11 upstream of the on-off valve V11 is maintained at or above the critical temperature. In this case, liquefaction of the processing fluid flowing through the fluid supply path L11 immediately after the heating mechanism HE11 can be prevented, and generation of particles can be suppressed.

[0040] Furthermore, when the processing fluid flows into the processing vessel 111 from the fluid supply path L11, the temperature of the processing fluid may drop due to pressure loss or the like, causing the processing fluid to liquefy. Therefore, the control unit 14 may control at least one of the temperature adjustment unit and the pressure adjustment unit so that the temperature detected by the temperature sensor T14 provided in the processing vessel 111 is maintained at or above the critical temperature. In this case, liquefaction of the processing fluid in the processing vessel 111 can be prevented, and particle generation can be suppressed.

[0041] After extensive investigation, the inventors have found that the relationship between the density of the processing fluid in the processing vessel 111 and the density of the processing fluid in the fluid supply path L11 at the start of the flow process ST13 affects the number of particles adhering to the surface of the substrate W in the processing vessel 111. Specifically, they have found that the number of particles adhering to the surface of the substrate W in the processing vessel 111 can be reduced by making the density of the processing fluid in the processing vessel 111 greater than the density of the processing fluid in the fluid supply path L11 at the start of the flow process ST13. The density of the processing fluid in the processing vessel 111 can be calculated based on the temperature detected by the temperature sensor T14 and the temperature detected by the pressure sensor P14, for example, using a Mollier diagram. The density of the processing fluid in the fluid supply path L11 can be calculated based on the temperature detected by the temperature sensor T13 and the temperature detected by the pressure sensor P13, for example, using a Mollier diagram.

[0042] The reason why the number of particles adhering to the surface of the substrate W in the processing vessel 111 can be reduced by making the density of the processing fluid in the processing vessel 111 greater than the density of the processing fluid in the fluid supply path L11 at the start of the flowing process ST13 is believed to be as follows: If the solubility of the solute in the processing fluid in the processing vessel 111 is lower than the solubility of the solute in the processing fluid in the fluid supply path L11 at the start of the flowing process ST13, the solute condenses in the processing vessel 111 and easily adheres to the surface of the substrate W. The solute includes, for example, IPA and impurities. On the other hand, if the solubility of the solute in the processing fluid in the processing vessel 111 is higher than the solubility of the solute in the processing fluid in the fluid supply path L11 at the start of the flowing process ST13, the solute is less likely to condense in the processing vessel 111. Therefore, particles are less likely to adhere to the surface of the substrate W in the processing vessel 111. Here, the density of the processing fluid is proportional to the solubility of the solute in the processing fluid. Furthermore, when the pressure of the processing fluid is constant, as the temperature increases, the density decreases. That is, the processing fluid is supplied into the processing vessel 111 at a temperature higher than the temperature inside the processing vessel 111 in the fluid supply path L11 connected to the processing vessel 111. Therefore, it is considered that the number of particles adhering to the surface of the substrate W in the processing vessel 111 can be reduced by making the density of the processing fluid in the processing vessel 111 higher than the density of the processing fluid in the fluid supply path L11 at the start of the flowing process ST13.

[0043] Second Embodiment (Substrate Processing Apparatus) A substrate processing apparatus 20 according to a second embodiment will be described with reference to Fig. 4. Fig. 4 is a view showing the substrate processing apparatus 20 according to the second embodiment.

[0044] The substrate processing apparatus 20 includes a processing section 21 , a supply section 22 , a discharge section 23 , and a control section 24 .

[0045] The processing unit 21 has a processing vessel 211 and a holding unit 212. The processing vessel 211 is a vessel having an internal processing space capable of accommodating a substrate W having a diameter of, for example, 300 mm. The substrate W may be, for example, a semiconductor wafer. The holding unit 212 is provided inside the processing vessel 211. The holding unit 212 holds the substrate W horizontally. The holding unit 212 is, for example, configured integrally with the processing vessel 211. The holding unit 212 may also be a holding plate configured separately from the processing vessel 211. The processing unit 21 has a temperature sensor T24 and a pressure sensor P24. The temperature sensor T24 detects the temperature inside the processing vessel 211. The pressure sensor P24 detects the pressure inside the processing vessel 211.

[0046] The supply unit 22 has a fluid supply source S21, a first fluid supply path L21, and a second fluid supply path L22.

[0047] The fluid supply source S21 is a supply source of a processing fluid, which may be, for example, carbon dioxide in a liquid state.

[0048] The first fluid supply path L21 is connected to a fluid supply source S21 at its upstream end and to the processing vessel 211 at its downstream end. The first fluid supply path L21 is provided with, in order from upstream, a heating mechanism HE21, a temperature sensor T21, an on-off valve V21, an orifice OR21, a temperature sensor T23, and a pressure sensor P23. A line heater LH21 is provided downstream of the heating mechanism HE21 in the first fluid supply path L21. On-off valves, temperature sensors, pressure sensors, and filters may also be provided at various positions on the first fluid supply path L21. The filter filters the processing fluid flowing through the first fluid supply path L21 to remove foreign matter contained in the processing fluid. This prevents particles from being generated on the surface of the substrate W during substrate processing using the processing fluid.

[0049] The heating mechanism HE21 heats the processing fluid supplied from the fluid supply source S21 to a first temperature and supplies the fluid at the first temperature downstream. The first temperature is 40° C. or higher and 100° C. or lower, for example, 60° C.

[0050] The temperature sensor T21 is provided in the first fluid supply path L21 downstream of the heating mechanism HE21 and upstream of the on-off valve V21. The temperature sensor T21 detects the temperature of the processing fluid flowing through the first fluid supply path L21.

[0051] The on-off valve V21 is a valve that switches the flow of the processing fluid on and off. When the on-off valve V21 is open, the processing fluid flows to the downstream orifice OR21, and when it is closed, the processing fluid does not flow to the downstream orifice OR21.

[0052] The orifice OR21 has a function of reducing the flow rate of the processing fluid and adjusting the pressure thereof, and the orifice OR21 allows the processing fluid with the adjusted pressure to flow into the processing vessel 211 downstream.

[0053] The temperature sensor T23 is provided in the first fluid supply path L21 downstream of the orifice OR21 and upstream of the processing vessel 211. The temperature sensor T23 detects the temperature of the processing fluid flowing through the first fluid supply path L21 immediately before the processing vessel 211.

[0054] The pressure sensor P23 is provided in the first fluid supply path L21 downstream of the orifice OR21 and upstream of the processing vessel 211. The pressure sensor P23 detects the pressure of the first fluid supply path L21 immediately before the processing vessel 211.

[0055] The line heater LH21 heats the first fluid supply path L21 downstream of the heating mechanism HE21. The line heater LH21 suppresses a decrease in temperature of the treatment fluid heated to the first temperature by the heating mechanism HE21 as it flows through the first fluid supply path L21.

[0056] The second fluid supply path L22 is arranged in parallel with the first fluid supply path L21. The second fluid supply path L22 branches off from the first fluid supply path L21 upstream of the heating mechanism HE21 and merges with the first fluid supply path L21 downstream of the on-off valve V21 and upstream of the orifice OR21. The second fluid supply path L22 is provided with a heating mechanism HE22, a temperature sensor T22, and an on-off valve V22, in this order from upstream to downstream. A line heater LH22 is provided downstream of the heating mechanism HE22 in the second fluid supply path L22. On-off valves, temperature sensors, pressure sensors, and filters may also be provided at various positions on the second fluid supply path L22. The filter filters the processing fluid flowing through the second fluid supply path L22 to remove foreign matter contained in the processing fluid. This prevents particles from being generated on the surface of the substrate W during substrate processing using the processing fluid.

[0057] The heating mechanism HE22 heats the processing fluid supplied from the fluid supply source S21 to a second temperature and supplies the fluid at the second temperature downstream. The second temperature is higher than the first temperature. The second temperature is equal to or higher than 100°C and equal to or lower than 150°C, for example, 120°C.

[0058] The temperature sensor T22 is provided in the second fluid supply path L22 downstream of the heating mechanism HE22 and upstream of the on-off valve V22. The temperature sensor T22 detects the temperature of the processing fluid flowing through the second fluid supply path L22.

[0059] The on-off valve V22 is a valve that switches the flow of the processing fluid on and off. When the on-off valve V22 is open, the processing fluid flows to the downstream orifice OR21, and when it is closed, the processing fluid does not flow to the downstream orifice OR21.

[0060] The line heater LH22 heats the second fluid supply path L22 downstream of the heating mechanism HE22. The line heater LH21 suppresses a decrease in temperature of the treatment fluid heated to the second temperature by the heating mechanism HE22 as it flows through the second fluid supply path L22.

[0061] In the supply unit 22, when the on-off valve V22 is closed and the on-off valve V21 is opened, the processing fluid heated to a first temperature by the heating mechanism HE21 is supplied into the processing vessel 211 through the first fluid supply path L21. When the on-off valve V21 is closed and the on-off valve V22 is opened, the processing fluid heated to a second temperature by the heating mechanism HE22 is supplied into the processing vessel 211 through the second fluid supply path L22. In this manner, the temperature of the processing fluid flowing through the processing vessel 211 can be changed by exclusively opening and closing the on-off valves V21 and V22. When both the on-off valves V21 and V22 are opened, the processing fluid heated to the first temperature by the heating mechanism HE21 and the processing fluid heated to the second temperature by the heating mechanism HE22 are mixed and supplied into the processing vessel 211. In this case, a processing fluid at an intermediate temperature between the first temperature and the second temperature can be supplied into the processing vessel 211. In this way, by controlling the opening and closing of the on-off valves V21 and V22, the temperature of the fluid flowing through the processing vessel 211 can be changed in three stages.

[0062] The discharge unit 23 has a discharge flow path L23. The discharge flow path L23 is connected to the processing vessel 211. An on-off valve V23 and a back pressure valve BV23 are provided in this order from upstream to downstream in the discharge flow path L23. A line heater LH23 is provided in the discharge flow path L23. On-off valves, temperature sensors, and pressure sensors may be further provided at various positions in the discharge flow path L23.

[0063] The on-off valve V23 is a valve that switches the flow of the treatment fluid on and off. When the on-off valve V23 is open, the treatment fluid flows to the downstream back pressure valve BV23, and when it is closed, the treatment fluid does not flow to the downstream back pressure valve BV23.

[0064] When the primary pressure of the discharge flow path L23 exceeds a set pressure, the back pressure valve BV23 adjusts the valve opening to allow the treatment fluid to flow to the secondary side, thereby maintaining the primary pressure at the set pressure. For example, the set pressure of the back pressure valve BV23 is adjusted by the control unit 24.

[0065] The line heater LH23 heats the exhaust flow path L23.

[0066] The control unit 24 receives measurement signals from various sensors (such as temperature sensors T21, T22, T23, and T24, and pressure sensors P23 and P24) and transmits control signals to various functional elements. The control signals include, for example, opening / closing signals for the on-off valves V21, V22, and V23, a set pressure signal for the back pressure valve BV23, and temperature signals for the line heaters LH21, LH22, and LH23. For example, the control unit 24 is configured to change the temperature of the fluid flowing through the processing vessel 211 by controlling the opening / closing of the on-off valves V21 and V22 in accordance with the processing state of the substrate W in the processing vessel 211.

[0067] The control unit 24 is, for example, a computer, and includes an arithmetic unit 241 and a storage unit 242. The storage unit 242 stores programs for controlling various processes executed in the substrate processing apparatus 20. The arithmetic unit 241 controls the operation of the substrate processing apparatus 20 by reading and executing the programs stored in the storage unit 242. The programs may be recorded on a computer-readable storage medium and installed from the storage medium into the storage unit 242 of the control unit 24. Examples of computer-readable storage media include a hard disk, a flexible disk, a compact disk, a magnetic optical disk, and a memory card.

[0068] 5 and 6, a substrate processing method executed using the substrate processing apparatus 20 will be described. The substrate processing method described below is automatically executed under the control of the control unit 24 based on the processing recipe and control program stored in the storage unit 242.

[0069] Fig. 5 is a flowchart showing the substrate processing method according to the second embodiment. Fig. 6 is a diagram showing pressure changes in the processing vessel 211 during the substrate processing method according to the second embodiment. In Fig. 6, the horizontal axis represents processing time, and the vertical axis represents the pressure in the processing vessel 211 detected by the pressure sensor P24.

[0070] 5, the substrate processing method according to the second embodiment includes a preparation step ST21, a first pressure increase step ST22, a second pressure increase step ST23, a circulation step ST24, and a depressurization step ST25. Each step will be described below.

[0071] The preparation step ST21 may be the same as the preparation step ST11.

[0072] The first pressurization step ST22 is performed after the preparation step ST21. In the first pressurization step ST22, the on-off valve V21 is opened, and the on-off valves V22 and V23 are closed. As a result, the processing fluid from the fluid supply source S21 is supplied into the processing vessel 211 via the first fluid supply path L21. The processing fluid is heated to a first temperature by a heating mechanism HE21 provided along the first fluid supply path L21, and then supplied into the processing vessel 211. By supplying the processing fluid at the first temperature into the processing vessel 211, the temperature of the substrate W changes to the first temperature. In the first pressurization step ST22, the pressure of the processing fluid supplied into the processing vessel 211 is lower than the critical pressure. Therefore, as shown in FIG. 6 , the pressure in the processing vessel 211 gradually increases.

[0073] The pressure inside the processing vessel 211 is detected by a pressure sensor P24, and the first pressurization step ST22 continues until the pressure inside the processing vessel 211 reaches the first pressure. When the pressure inside the processing vessel 211 reaches the first pressure, the first pressurization step ST22 ends and the process moves to the second pressurization step ST23. The first pressure is lower than the critical pressure. In this case, liquefaction of the processing fluid inside the first fluid supply path L21 and the processing vessel 211 can be prevented, and the generation of particles can be suppressed. CO is used as the processing fluid. ２ When CO is used, ２ The critical pressure of CO is about 7 MPa, and the first pressure may be 3 MPa or more and less than 7 MPa. In this case, it is easy to prevent the processing fluid from liquefying in the first fluid supply path L21. ２ When the first pressure is used, the first pressure may be equal to or greater than 6 MPa and less than 7 MPa. In this case, pattern collapse can be easily suppressed.

[0074] The second pressurization step ST23 is performed after the first pressurization step ST22. In the second pressurization step ST23, the supply path of the processing fluid into the processing vessel 211 is changed. Specifically, the on-off valve V22 is opened, and the on-off valves V21 and V23 are closed. As a result, the processing fluid from the fluid supply source S21 is supplied into the processing vessel 211 via the second fluid supply path L22. The processing fluid is heated to the second temperature by the heating mechanism HE22 provided midway along the second fluid supply path L22 and supplied into the processing vessel 211. As a result, the temperature of the processing fluid supplied into the processing vessel 211 is quickly increased. By supplying the processing fluid at the second temperature into the processing vessel 211, the temperature of the substrate W is quickly changed to the second temperature. In the second pressurization step ST23, since the on-off valve V23 is closed, the pressure in the processing vessel 211 gradually increases, as shown in FIG. 6 . In the second pressurization step ST23, the pressure of the processing fluid supplied into the processing vessel 211 is lower than the critical pressure. Therefore, the processing fluid is supplied into the processing vessel 211 in a gaseous state. Thereafter, as the processing vessel 211 is filled with the processing fluid, the pressure inside the processing vessel 211 increases, and when the pressure inside the processing vessel 211 exceeds the critical pressure, the processing fluid present in the processing vessel 211 becomes a supercritical state. In the second pressurization step ST23, when the pressure inside the processing vessel 211 reaches a processing pressure higher than the critical pressure, the second pressurization step ST23 is terminated, and the processing proceeds to the flow step ST24.

[0075] The flowing process ST24 is performed after the second pressurization process ST23. In the flowing process ST24, the on-off valves V22 and V23 are opened, and the on-off valve V21 is closed. As a result, the processing fluid from the fluid supply source S21 is supplied into the processing container 211 via the second fluid supply path L22. The processing fluid supplied into the processing container 211 is discharged from the processing container 211 via the discharge path L23. In the flowing process ST24, the processing fluid is simultaneously supplied into the processing container 211 and discharged from the processing container 211. Therefore, as shown in FIG. 6 , the pressure inside the processing container 211 is maintained substantially constant. By performing the flowing process ST24, replacement of the IPA with the processing fluid in the recesses of the pattern on the substrate W is promoted. When replacement of the IPA with the processing fluid in the recesses of the pattern is completed, the flowing process ST24 is terminated, and the process proceeds to the depressurization process ST25.

[0076] The depressurization step ST25 is performed after the flow step ST24. In the depressurization step ST25, the on-off valve V23 is opened, and the on-off valves V21 and V22 are closed. As a result, the processing fluid is discharged from the processing container 211 without being supplied into the processing container 211. Therefore, as shown in FIG. 6 , the pressure inside the processing container 211 gradually decreases. When the pressure inside the processing container 211 becomes lower than the critical pressure of the processing fluid by the depressurization step ST25, the processing fluid in the supercritical state vaporizes and escapes from the recesses of the pattern. This completes the drying process for one substrate W.

[0077] According to the second embodiment, the processing fluid at a first temperature is supplied from the fluid supply source S21 into the processing vessel 211, and when the pressure inside the processing vessel 211 reaches the first pressure, the processing fluid at a second temperature is supplied from the fluid supply source S21 into the processing vessel 211. In this case, liquefaction of the processing fluid inside the first fluid supply path L21 and the processing vessel 211 can be prevented, and generation of particles can be suppressed. This point will be described below.

[0078] 7 and 8 are diagrams showing temperature changes of the processing fluid in the first fluid supply line L21. Fig. 7 shows the temperature changes of the processing fluid when the temperature of the processing fluid is maintained at a first temperature while the processing fluid is supplied into the processing vessel 211 to increase the pressure therein above the critical pressure. Fig. 8 shows the temperature changes of the processing fluid when the temperature of the processing fluid is changed from the first temperature to a second temperature when the pressure therein reaches the first pressure while the processing fluid is supplied into the processing vessel 211 to increase the pressure therein above the critical pressure. In Figs. 7 and 8, the horizontal axis represents the time since the supply of the processing fluid into the processing vessel 211 began, and the vertical axis represents the temperature detected by the temperature sensor T23.

[0079] Consider a case where the temperature of the processing fluid is maintained at a first temperature when the processing fluid is supplied into the processing vessel 211 to increase the pressure therein to above the critical pressure. In this case, as shown in FIG. 7 , the temperature of the processing fluid in the first fluid supply path L21 may become lower than the critical temperature due to pressure loss or the like. This may result in the processing fluid liquefying, which may easily generate particles.

[0080] 8 , when the processing fluid is supplied into the processing vessel 211 to increase the pressure therein to above the critical pressure, the temperature of the processing fluid is changed from the first temperature to the second temperature at time t1 when the pressure therein reaches the first pressure. In this case, the temperature of the processing fluid in the first fluid supply path L21 can be increased before the temperature of the processing fluid drops below the critical temperature. This prevents the processing fluid in the processing vessel 211 from liquefying and suppresses particle generation.

[0081] According to the second embodiment, CO is used as the treatment fluid. ２ When the first pressure is used, the first pressure may be equal to or greater than 6 MPa and less than 7 MPa. In this case, pattern collapse is easily suppressed. This point will be described below.

[0082] 9 is a diagram illustrating pattern collapse. In FIG. 9, the horizontal axis represents the pressure [MPa] inside the processing vessel 211 detected by the pressure sensor P24, and the vertical axis represents the correlation coefficient between the temperature detected by the temperature sensor T23 and the number of pattern collapses. The correlation coefficient between the temperature detected by the temperature sensor T23 and the number of pattern collapses can be calculated by a preliminary experiment.

[0083] As shown in FIG. 9 , when the pressure in the processing vessel 211 is 6 MPa or less, the correlation coefficient is positive. This means that when the pressure in the processing vessel 211 is 6 MPa or less, the pattern collapse is reduced as the temperature detected by the temperature sensor T23 decreases. In contrast, when the pressure in the processing vessel 211 is 7 MPa or more, the correlation coefficient is negative. This means that when the pressure in the processing vessel 211 is 7 MPa or more, the pattern collapse is reduced as the temperature detected by the temperature sensor T23 increases. From this result, it can be said that pattern collapse is easily suppressed by lowering the temperature of the processing fluid when the pressure in the processing vessel 211 is 6 MPa or less and by raising the temperature of the processing fluid when the pressure in the processing vessel 211 is 7 MPa or more. In other words, it can be said that pattern collapse is easily suppressed by setting the first pressure to be 6 MPa or more and 7 MPa or less.

[0084] In the above embodiment, the heating mechanism HE21 is an example of a first temperature adjustment unit, the heating mechanism HE22 is an example of a second temperature adjustment unit, the temperature sensors T13 and T23 are an example of a first temperature sensor, the temperature sensors T11, T21, and T22 are an example of a second temperature sensor, and the temperature sensors T14 and T24 are an example of a third temperature sensor.

[0085] The embodiments disclosed herein should be considered to be illustrative in all respects and not restrictive, and the above-described embodiments may be omitted, substituted, or modified in various ways without departing from the scope and spirit of the appended claims.

[0086] In the present disclosure, the control units 14, 24 are electronic circuits such as a CPU (Central Processing Unit), FPGA (Field Programmable Gate Array), ASIC (Application Specific Integrated Circuit), etc., which perform the various control operations described in this specification by executing instruction codes stored in a memory or by being designed as a circuit for a specific application.

[0087] This international application claims priority based on Japanese Patent Application No. 2023-116085, filed on July 14, 2023, the entire contents of which are incorporated herein by reference.

[0088] 10, 20 Substrate processing apparatus 14, 24 Control unit 111, 211 Processing vessel S11, S21 Fluid supply source L11 Fluid supply path L21 First fluid supply path L22 Second fluid supply path HE11, HE21, HE22 Heating mechanism BV13, BV23 Back pressure valve V11, V21, V22 Open / close valve T13, T23 Temperature sensor W Substrate

Claims

1. A substrate processing apparatus comprising: a processing vessel for accommodating a substrate; a supply source for supplying a processing fluid into the processing vessel; a fluid supply path connecting the supply source to the processing vessel; a temperature adjustment unit provided in the fluid supply path for adjusting a temperature of the processing fluid; a pressure adjustment unit for adjusting the pressure within the processing vessel; an on-off valve provided in the fluid supply path downstream of the temperature adjustment unit; a first temperature sensor provided in the fluid supply path downstream of the on-off valve; and a control circuit for controlling the operation of the temperature adjustment unit, wherein the control circuit controls at least one of the temperature adjustment unit and the pressure adjustment unit so that the temperature detected by the first temperature sensor is maintained above a critical temperature.

2. The substrate processing apparatus according to claim 1, further comprising a discharge passage for discharging the processing fluid within the processing vessel, wherein the pressure adjustment unit includes a back pressure valve provided in the discharge passage.

3. The substrate processing apparatus of claim 1, wherein the control circuit controls at least one of the temperature adjustment unit and the pressure adjustment unit so that the temperature detected by the first temperature sensor is maintained above the critical temperature from the time when the on-off valve is switched from a closed state to an open state to the time when the processing fluid in the processing vessel transitions to a supercritical state.

4. The substrate processing apparatus of claim 1, further comprising a second temperature sensor provided in the fluid supply path upstream of the on-off valve, and the control circuit controls at least one of the temperature adjustment unit and the pressure adjustment unit so that the temperature detected by the second temperature sensor is maintained at or above a critical temperature.

5. The substrate processing apparatus according to claim 1, wherein the control circuit controls the temperature adjustment unit based on a magnitude relationship between the density of the processing fluid in the processing vessel and the density of the processing fluid in the fluid supply path.

6. The substrate processing apparatus according to claim 1, further comprising a third temperature sensor for detecting a temperature inside the processing vessel, wherein the control circuit controls at least one of the temperature adjustment unit and the pressure adjustment unit so that the temperature detected by the third temperature sensor is maintained at or above a critical temperature.

7. A substrate processing apparatus as claimed in any one of claims 1 to 6, further comprising a pressure sensor for detecting the pressure within the processing vessel, wherein the control circuit executes a step of supplying the processing fluid into the processing vessel to increase the pressure within the processing vessel to a processing pressure higher than a critical pressure of the processing fluid, wherein the step of increasing to the processing pressure comprises: increasing the pressure within the processing vessel to a first pressure lower than the critical pressure; and increasing the pressure within the processing vessel from the first pressure to the processing pressure, wherein the step of increasing to the first pressure comprises controlling a temperature of the processing fluid in the fluid supply path to a first temperature, and wherein the step of increasing to the processing pressure comprises controlling the temperature of the processing fluid in the fluid supply path to a second temperature higher than the first temperature.

8. The substrate processing apparatus according to claim 7, wherein the temperature adjustment unit includes: a first temperature adjustment unit that adjusts the processing fluid to the first temperature; and a second temperature adjustment unit that adjusts the processing fluid to the second temperature.

9. A substrate processing method comprising: (a) accommodating a substrate having a liquid adhering to its surface in a processing vessel; (b) supplying a processing fluid into the processing vessel containing the substrate to increase the pressure in the processing vessel to a processing pressure higher than the critical pressure of the processing fluid; and (c) after the pressure in the processing vessel has increased to the processing pressure, supplying the processing fluid to the processing vessel and discharging the processing fluid from the processing vessel while maintaining the pressure in the processing vessel at a pressure at which the processing fluid maintains a supercritical state, wherein the step (b) comprises: (b1) increasing the pressure in the processing vessel to a first pressure lower than the critical pressure; and (b2) increasing the pressure in the processing vessel from the first pressure to the processing pressure, wherein the step (b1) comprises controlling a temperature of the processing fluid to a first temperature; and the step (b2) comprises controlling a temperature of the processing fluid to a second temperature higher than the first temperature.

10. The method of claim 9, wherein step (c) comprises supplying the processing fluid into the processing vessel at a temperature higher than a temperature inside the processing vessel.

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