Substrate processing apparatus and substrate processing method

Abstract

To reduce an impurity existing on a front surface of a substrate after a processing.SOLUTION: A substrate processing apparatus comprises: a processing container having an opening for carrying a substrate in / from a processing container; a movable lid body that close the opening of the processing container; a lid body movement mechanism that makes the lid body move between a closed position for closing an opening with the lid body and an open position for opening it; a substrate holding part that holds a front surface in a horizontal way so as to set it to an upward direction in the processing container; a fluid supply mechanism that is constructed so that a treatment fluid in the supercritical state and a gaseous fluid made of a same material as the treatment fluid in the supercritical state can be supplied to the processing container, and contains at least one supply line and a flowing control device; and a control part that controls the fluid supply mechanism so that the treatment fluid in the supercritical state is supplied to the processing container when the substrate is held by the substrate holding part and when the lid body is in the closed position of a first state, and so that the gaseous fluid is supplied to the processing container when the lid body is in the open position of a second state.SELECTED DRAWING: Figure 4

Description

[Technical Field]

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

[0002] In the manufacture of semiconductor devices in which a laminated structure of integrated circuits is formed on the surface of a substrate such as a semiconductor wafer, liquid processing such as chemical cleaning or wet etching is performed. In order to more reliably prevent collapse of patterns that have become increasingly fine in recent years, a drying method using a processing fluid in a supercritical state has recently been used in the drying step, which is the final step of liquid processing (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2018-074103 Summary of the Invention [Problem to be solved by the invention]

[0004] The present disclosure provides techniques that can reduce impurities present on the surface of a processed substrate. [Means for solving the problem]

[0005] According to one embodiment of the present disclosure, there is provided a substrate processing apparatus for drying a substrate having a liquid attached to its surface using a supercritical drying technique, the apparatus comprising: a processing vessel having an opening for loading and unloading the substrate into and from the processing vessel; a movable lid for closing the opening of the processing vessel; a lid movement mechanism for moving the lid between a closed position for closing the opening and an open position for opening the opening; a substrate holder for holding the substrate horizontally with the surface facing upward in the processing vessel; and a processing fluid in a supercritical state and a gaseous fluid made of the same substance as the processing fluid in the supercritical state, configured to be able to supply the processing vessel with the processing fluid. Tarua control unit that controls the fluid supply mechanism so that the supercritical state processing fluid is supplied to the processing vessel when the substrate is held in the processing vessel by the substrate holder and the lid is in the closed position in a first state, and the gaseous state fluid is supplied to the processing vessel when the substrate is not held in the processing vessel by the substrate holder and the lid is in the open position in a second state. [Effects of the Invention]

[0006] According to the above embodiment, it is possible to reduce impurities present on the surface of the processed substrate. [Brief explanation of the drawings]

[0007] [Figure 1] 1 is a schematic vertical cross-sectional view of a supercritical drying unit according to an embodiment of the substrate processing apparatus. [Figure 2] FIG. 2 is a schematic cross-sectional view of the supercritical drying unit taken along line II-II in FIG. 1. [Figure 3] FIG. 2 is a schematic vertical cross-sectional view of the supercritical drying unit, showing a state in which a purging step is being performed in the supercritical drying unit. [Figure 4] FIG. 2 is a diagram of a piping system for supplying / discharging fluid to / from a processing vessel. [Figure 5A] FIG. 2 is a diagram showing one step of the supercritical drying process. [Figure 5B] FIG. 2 is a diagram showing one step of the supercritical drying process. [Figure 5C] FIG. 2 is a diagram showing one step of the supercritical drying process. [Figure 5D] FIG. 2 is a diagram showing one step of the supercritical drying process. [Figure 5E] FIG. 2 is a diagram showing one step of the supercritical drying process. [Figure 6] FIG. 2 is a schematic side view showing an example of the configuration inside a housing in which a supercritical drying unit is housed. [Figure 7]FIG. 10 is a schematic vertical cross-sectional view showing another configuration of the supercritical drying unit. DETAILED DESCRIPTION OF THE INVENTION

[0008] The configuration of a supercritical drying apparatus as one embodiment of a substrate processing apparatus will be described with reference to Figures 1 to 4. The supercritical drying apparatus can be used to perform supercritical drying processing on a substrate W having a liquid film (e.g., IPA (isopropyl alcohol)) attached to its surface, by using a processing fluid (e.g., carbon dioxide) in a supercritical state to dry it. The substrate W is, for example, a semiconductor wafer, but may also be other types of substrates (e.g., glass substrates, ceramic substrates) used in the technical field of semiconductor device manufacturing. The supercritical drying technique can be advantageously used to dry substrates on which fine patterns with high aspect ratios are formed, because surface tension that can cause pattern collapse does not act on the pattern.

[0009] In the following, to facilitate the explanation of directions and positions, an XYZ Cartesian coordinate system is set up, and explanations will be given with reference to this coordinate system as necessary. Note that the X direction is sometimes called the front-to-back direction (the positive X direction is forward), the Y direction is sometimes called the left-to-right direction (the positive Y direction is left), and the Z direction is sometimes called the up-to-down direction (the positive Y direction is upward).

[0010] The supercritical drying apparatus includes a processing unit 10. Supercritical drying processing is performed inside the processing unit 10. The processing unit 10 includes a processing vessel 11 and a substrate holding tray 12 (hereinafter simply referred to as "tray 12") that holds substrates W within the processing vessel 11.

[0011] The tray 12 has a lid 13 that closes an opening 11C provided in the side wall of the processing vessel 11, and a horizontally extending substrate holder 14 that is integrally connected to the lid (lid body) 13. The substrate holder 14 has a plate 15 and a plurality of support pins 16 provided on the upper surface of the plate 15. The substrate W is placed in a horizontal position on the support pins 16 with its front surface (the surface on which a device or pattern is formed) facing upward. When the substrate W is placed on the support pins 16, a gap 17 is formed between the upper surface of the plate 15 and the lower surface (rear surface) of the substrate W.

[0012] The plate 15 has an overall shape of, for example, a rectangle or a square. The area of ​​the plate 15 is larger than that of the substrate W. When the substrate W is placed at a predetermined position on the substrate holder 14, the plate 15 completely covers the substrate W when viewed from directly below.

[0013] The plate 15 is formed with a plurality of through holes 18 that penetrate the plate 15 from top to bottom. The plurality of through holes 18 serve to allow a processing fluid supplied to the space below the plate 15 to flow into the space above the plate 15. Some of the plurality of through holes 18 also serve to allow lift pins (indicated by reference numeral 300 at the bottom of FIG. 6) that transfer the substrate W between the substrate holder 14 and a substrate transport mechanism (not shown) external to the processing unit 10 to pass through, but a detailed description of this point will be omitted in this specification.

[0014] The tray 12 can be moved in the horizontal direction (X direction) between a closed position (the position shown in FIGS. 1 and 2) and an open position by a tray moving mechanism 12M (schematically shown only in FIG. 1). Although not shown in detail, the tray moving mechanism 12M may include, for example, a guide rail extending in the X direction and a tray that is coupled to the lid 13 and moves along the guide rail. Movement It can be composed of a moving object.

[0015] When the tray 12 is in the closed position, the substrate holding part 14 is located within the internal space of the processing vessel 11, and the lid part 13 closes the opening in the sidewall of the processing vessel 11. When the tray 12 is in the open position, the substrate holding part 14 is located outside the processing vessel 11 (see FIG. 6), and the substrate W can be transferred between the substrate holding part 14 and a substrate transport arm (not shown) via the lift pins described above. Furthermore, when the tray 12 is in the open position, the lid part 13 opens the opening 11C in the sidewall of the processing vessel 11. Therefore, the tray moving mechanism 12M can also be said to be a lid opening and closing mechanism.

[0016] When the tray 12 is in the closed position, the plate 15 divides the internal space of the processing vessel 11 into an upper space 11A above the plate 15 in which the substrate W is present during processing, and a lower space 11B below the plate 15. However, the upper space 11A and the lower space 11B are not completely separated.

[0017] That is, in the illustrated embodiment, the upper space 11A and the lower space 11B communicate with each other through the aforementioned through-hole 18 and through the elongated hole 19 (which is also a through-hole) provided near the connection between the plate 15 and the lid 13. The upper space 11A and the lower space 11B also communicate with each other through a gap between the peripheral edge of the plate 15 and the inner wall surface of the processing vessel 11. It can be said that the above-mentioned gap, the through-hole 18, the elongated hole 19, etc. are communication paths that connect the upper space 11A and the lower space 11B.

[0018] Instead of the movable tray 12, a substrate mounting table (substrate holder) that is immovably fixed in the processing vessel 11 may be provided. In this case, with a lid (not shown) provided on the processing vessel 11 open, a substrate transport arm (not shown) enters the vessel body, and the substrate W is transferred between the substrate mounting table and the substrate transport arm.

[0019] The processing vessel 11 is provided with a first discharge part 21 and a second discharge part 22. The first discharge part 21 and the second discharge part 22 discharge a processing fluid (carbon dioxide (hereinafter, for convenience, also referred to as "CO2") in this example) supplied from a supply source 30 of a supercritical fluid (a processing fluid in a supercritical state) into the internal space of the processing vessel 11.

[0020] Please note that the ordinal numbers ("first," "second," etc.) placed before the names of components (e.g., "discharge section") described in the description of the embodiments do not necessarily match the ordinal numbers placed before the names of corresponding components described in the claims.

[0021] The first discharge unit 21 is provided below the plate 15 of the tray 12 when the tray 12 is in the closed position. The first discharge unit 21 discharges CO2 (processing fluid) into the lower space 11B toward the lower surface of the plate 15 (upward). The first discharge unit 21 may be configured as a through-hole formed in the bottom wall of the processing vessel 11. The first discharge unit 21 may also be a nozzle body attached to the bottom wall of the processing vessel 11.

[0022] The second discharge unit 22 is provided to be located in front of (a position in the positive X direction of) the substrate W placed on the substrate holder 14 of the tray 12 when the tray 12 is in the closed position. The second discharge unit 22 supplies CO2 into the upper space 11A. In the illustrated embodiment, the second discharge unit 22 is provided on the side wall of the processing vessel 11 opposite to the lid unit 13.

[0023] The second discharge part 22 is configured by a rod-shaped nozzle body. In detail, the second discharge part 22 is formed by drilling a plurality of discharge ports 22b in a pipe 22a extending in the width direction (Y direction) of the substrate W. The plurality of discharge ports 22b are arranged at equal intervals in the Y direction, for example. Each discharge port 22b has an opening 11C (roughly in the negative X direction), 11A CO2 is supplied to the inside.

[0024] The processing vessel 11 is further provided with a fluid discharge unit 24 that discharges the processing fluid from the internal space of the processing vessel 11. The fluid discharge unit 24 is configured as a header having substantially the same configuration as the second discharge unit 22. In detail, the fluid discharge unit 24 is formed by drilling a plurality of discharge ports 24b in a pipe 24a extending in the horizontal direction. The plurality of discharge ports 24b are aligned at equal intervals in the Y direction, for example. Each discharge port 24b faces upward and toward the elongated hole 19 in the plate 15.

[0025] In the illustrated embodiment, the fluid discharge part 24 is provided in a recess formed in the bottom wall of the processing vessel 11 near the opening 11C. As shown by arrow F in FIG. 1, CO2 flows through a region above the substrate W in the upper space 11A, then flows into the lower space 11B through a communication passage provided in the peripheral portion of the plate 15 (or through-holes 19 formed in the plate 15), and is then discharged from the fluid discharge part 24.

[0026] The arrangement of the second discharge unit 22 and the fluid discharge unit 24 is not limited to that shown in the figure, and they can be arranged at any position as long as CO2 supplied from the second discharge unit 22 into the processing vessel 11 passes substantially horizontally through an area above substantially the entire surface of the substrate W and then is discharged from the fluid discharge unit 24. Specifically, for example, the second discharge unit 22 and the fluid discharge unit 24 may be arranged on both sides of the substrate W in the left-right direction (Y direction), sandwiching the substrate W therebetween. Alternatively, instead of the fluid discharge unit 24 shown in FIG. 1, a fluid discharge unit having a similar configuration (but with its discharge port facing downward) may be provided on the ceiling wall of the processing vessel 11.

[0027] The processing unit 10 is provided with a locking mechanism 25 for fixing the tray 12 in the closed position. The locking mechanism 25 has a guide hole 25A formed in the processing vessel 11 and a bar-shaped locking member 25C that moves up and down (in the Z direction) along the guide hole 25A by an elevating mechanism 25B (e.g., an air cylinder or a ball screw). FIG. 3 shows the locking member 25C in the lowered position (unlocked position). After the tray 12 is moved to the closed position, if the locking member 25C is moved to the raised position (locked position) shown in FIG. 1, the tray 12 will not move in the open direction (negative X direction) even if the internal pressure of the processing vessel 11 increases.

[0028] A gas recovery unit 28 is provided in a position near the opening 11C of the processing vessel 11 (e.g., region 29A or 29B in FIG. 2) to suck and recover CO2 gas that has been supplied to the processing vessel 11 in a gaseous state and then flowed out of the opening 11C or that is about to flow out during a purge process described later. The main reason for providing the gas recovery unit 28 is to comply with safety regulations regarding CO2 concentration.

[0029] The gas recovery section 28 can be provided in an appropriate component of the processing unit 10 near the opening 11C (e.g., the lock member 25C, the wall of the processing vessel 11, the inside of the guide hole 25A, etc.). The gas recovery section 28 can be configured as a header having approximately the same configuration as the fluid discharge section 24.

[0030] 1 and 3 show gas recovery section 28 provided in region 29A in Fig. 2. Gas recovery section 28 described here is made up of a pipe (which has a plurality of suction ports that open upward and are aligned in the Y direction) that has a similar configuration to fluid discharge section 24 provided in a recess formed in region 29A shown in Fig. 2.

[0031] 2, the gas recovery unit 28 may be provided on a wall of the processing vessel 11 that faces the locking member 25C in the vertical direction, rather than on the locking member 25C. Although the gas recovery unit 28 may be provided on the upper surface of the locking member 25C, providing the gas recovery unit 28 on the locking member 25C, which is a movable member, makes the piping connecting to the gas recovery unit 28 more complicated.

[0032] The gas recovery unit 28 may be provided on the wall of the processing vessel 11 on the opposite side (upper side) from the position shown in FIGS. 1 and 3 (for example, at the position indicated by reference numeral 28' in FIG. 3).

[0033] The shielding gas is discharged downward at a position facing the gas recovery section 28 in the vertical direction. curtain A gas outlet 26 may be provided. curtain The gas discharge section 26 can also be configured as a header having substantially the same configuration as the gas recovery section 28 . curtain The shielding gas discharged from the gas discharge unit 26 can form a gas curtain in front of the opening 11C. By forming the gas curtain, it is possible to prevent the atmosphere (air) from entering the processing vessel 11 through the opening 11C when the tray 12 is in the open position. The shielding gas that forms the gas curtain is CO2 gas, which is the same gas as the processing fluid and the purge gas. The gas recovery unit 28 is provided on the upper side, curtain The gas discharge section 26 may also be provided on the lower side.

[0034] Next, a supply / discharge system for supplying and discharging CO2 to and from the processing vessel 11 in the supercritical drying apparatus will be described with reference to Fig. 4. Note that in Fig. 4, for the sake of simplicity, the processing unit 10 is depicted in a greatly simplified form, is reversed left and right relative to the processing unit 10 depicted in Figs. 1 to 3, and the fluid discharge unit 24 is depicted in a different position from the actual position.

[0035] In the piping diagram shown in Figure 4, the circled T indicates a temperature sensor, and the circled P indicates a pressure sensor. The OLF indicates an orifice (fixed throttle) that reduces the pressure of the CO2 flowing in the downstream piping to a desired value. The SV indicates a safety valve (relief valve) that prevents damage to the piping or the processing vessel 11 and other components of the supercritical drying device due to unexpected excessive pressure. The FL indicates a filter that removes particles and other contaminants from the CO2. The CV indicates a check valve. The FM indicates a flow meter. The H indicates a heater that regulates the temperature of the CO2. When it is necessary to distinguish one of the above components from another, a number is added to the end of the alphabet (e.g., "filter FL2"). Members designated by reference symbol VN (N is a natural number) are on-off valves, and 13 on-off valves V1 to V13 are depicted in FIG.

[0036] The supercritical drying apparatus has a supercritical fluid supply device (first fluid supply unit) 30 as a supply source (30) of a supercritical processing fluid (supercritical CO2). The supercritical fluid supply device 30 has a well-known configuration including, for example, a carbon dioxide gas cylinder, a pressure pump, a heater, etc. The supercritical fluid supply device 30 has the ability to deliver CO2 at a pressure exceeding the supercritical state guarantee pressure (specifically, approximately 16 MPa) described below.

[0037] A main supply line 32 is connected to the supercritical fluid supply device 30. CO2 is sent from the supercritical fluid supply device 30 to the main supply line 32 in a supercritical state, but may become gaseous due to subsequent pressure or temperature changes. In this specification, a member referred to as a "line" may be constituted by a pipe (a piping member).

[0038] The main supply line 32 branches into a first supply line 34 and a second supply line 36 at a branch point (first branch point) 33. The first supply line 34 is connected to a first discharge part 21 of the processing vessel 11. The second supply line 36 is connected to a second discharge part 22 of the processing vessel 11.

[0039] A discharge line 38 is connected to the fluid discharge unit 24 of the processing vessel 11. A valve (adjustable valve) 40 with an adjustable opening is provided in the discharge line 38. By adjusting the opening of the valve 40, the primary pressure of the valve 40 can be adjusted, and therefore the pressure inside the processing vessel 11 can be adjusted. By adjusting the opening of the valve 40, the discharge rate of the processing fluid from the processing vessel 11 can also be adjusted.

[0040] Although not shown in FIG. 4, the second supply line 36 branches into two branches near the connection to the second discharge unit 22 (downstream of the filter FL2), with the ends of the two branches connected to opposite ends 23A and 23B of the pipe 22a of the second discharge unit 22 shown in FIG. 2. This equalizes the pressure distribution along the length of the pipe 22a, allowing the treatment fluid to be ejected approximately uniformly from each outlet 22b. Similarly, the discharge line 38 branches into two branches near the connection to the fluid discharge unit 24 (upstream of the relief valve SV), with the ends of the two branches connected to opposite ends of the pipe 24a of the fluid discharge unit 24. This allows the treatment fluid to flow into the pipe 24a approximately uniformly from each outlet 24b. Note that the temperature sensor T and the pressure sensor PS12 need only be provided at one of the two branches.

[0041] figure 4 1, a control unit 100 performs feedback control of the opening degree (specifically, the position of the valve element) of the valve 40 based on the deviation between the measured value (PV) of the pressure in the processing vessel 11 and the set value (SV) so that the pressure in the processing vessel 11 is maintained at the set value. 41, the detection value of a pressure sensor designated by reference symbol PS, which is provided between the on-off valve V3 of the exhaust line 38 and the processing vessel 11, can be used. That is, the pressure inside the processing vessel 11 may be measured directly by a pressure sensor provided inside the processing vessel 11, or may be measured indirectly by a pressure sensor (PS12) provided outside the processing vessel 11 (on the exhaust line 38). The valve 40 can be set to a fixed opening based on a command value from the control unit 100 (rather than being feedback controlled).

[0042] The control unit 100 is, for example, a computer, and includes an arithmetic unit 101 and a memory unit 102. The memory unit 102 stores programs that control various processes executed in the supercritical drying apparatus (or a substrate processing system including the supercritical drying apparatus). The arithmetic unit 101 controls the operation of the supercritical drying apparatus by reading and executing the programs stored in the memory unit 102. The programs may be recorded on a computer-readable storage medium and installed from the storage medium into the memory unit 102 of the control unit 100. 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.

[0043] A bypass line 44 branches off from the first supply line 34 at a branch point 42 set on the first supply line 34. The bypass line 44 is connected to the discharge line 38 at a connection point (junction) 46 set on the discharge line 38. The connection point 46 is located upstream of the control valve 40.

[0044] At a branch point 48 set in the discharge line 38 upstream of the control valve 40, a branch discharge line 50 branches off from the discharge line 38 and rejoins the discharge line 38. At a branch point 52 set in the discharge line 38, two branch discharge lines 54, 56 branch off from the discharge line 38. The downstream ends of the branch discharge lines 54, 56 rejoin the discharge line 38. The downstream end of the discharge line 38 is connected to, for example, a fluid recovery device (not shown). Useful components (e.g., IPA (isopropyl alcohol)) contained in the CO2 recovered by the fluid recovery device are separated as appropriate and reused. The downstream end of the branch discharge line 50 may be open to the atmosphere without merging with the discharge line 38.

[0045] A discharge line 66 for discharging the treatment fluid branches off from a branch point (second branch point) 64 set on the main supply line 32 immediately upstream of the branch point (first branch point) 33.

[0046] A purge gas supply line 62 is connected to a junction 60 set in the first supply line 34 between the branch point 42 and the processing vessel 11. A purge gas supply source (second fluid supply unit) 64 is connected to the purge gas supply line 62. Purge gas supply source 81 The purge gas can be supplied to the processing chamber 11 from the purge gas supply line 62, the junction 60, the first supply line 34, and the first discharge part 21. 81 The gas supplied from the purge gas supply source is the same substance as the processing fluid used in supercritical drying, only the phase is different. Specifically, in this case, the processing fluid used in the supercritical drying process is CO2 in a supercritical state (supercritical phase), and 81 The purge gas supplied from is CO2 in gaseous state (vapor phase).

[0047] Purge Gas Supply Source 81The purge gas supply line 62 (including a check valve CV and an on-off valve V11) may be connected to a junction 74 of the second supply line 36 (see (B) in FIG. 4). In this case, the purge gas flows into the processing vessel 11 from the second discharge part 22.

[0048] A gas recovery line 70 having an on-off valve V12 installed therein is connected to the gas recovery section 28, and this gas recovery line can be connected to the discharge line 38, for example, downstream of the on-off valve V5. In Fig. 4, for ease of viewing, the gas recovery line 70 is shown as being divided at (A).

[0049] The curtain gas discharge section 26 can be supplied with CO2 in a gaseous state (gas phase) (CO2 gas) from a curtain gas supply source 71 (third fluid supply section) via a curtain gas supply line 72 in which an on-off valve V13 is installed. 81 CO2 in a gaseous state (gas phase) (CO2 gas) may be supplied from the purge gas supply line 62 to the curtain gas discharge unit 26. In this case, for example, a curtain gas supply line (not shown) provided with an on-off valve may be branched from the purge gas supply line 62 and connected to the curtain gas discharge unit 26.

[0050] Next, an example of a supercritical drying method (substrate processing method) using the above-mentioned supercritical drying apparatus will be briefly described. The procedure described below is automatically executed under the control of the control unit 100 based on the processing recipe and control program stored in the storage unit 102.

[0051] [Purge process and substrate loading process] Before the substrates W such as semiconductor wafers are loaded into the processing chamber 11, the tray 12 moves to the open position. That is, the cover (cover body) 13 of the tray 12 opens the opening 11C of the processing chamber 11. Next, the substrates W on the tray 12 in the open position are removed by a known method. retentionThe substrate W is placed on the section 14. For example, the lift pins in the raised position (see the lift pins 300 in the lowered position shown in FIG. 6) receive the substrate W from a substrate transport arm (not shown) and then lower to lift the substrate W. retention A substrate W can be placed on the section 14 .

[0052] The substrate W placed on the tray 12 has been subjected, for example, to a single-wafer cleaning apparatus (not shown) in which (1) chemical processing such as wet etching and chemical cleaning, (2) a rinse process in which the chemical liquid is washed away with a rinse liquid, and (3) an IPA substitution process in which the rinse liquid is replaced with IPA to form an IPA puddle (liquid film). The substrate W is placed on the tray 12 in a state in which the IPA puddle is formed on the surface of the substrate W.

[0053] A purge process is performed to purge the internal space of the processing vessel 11 with CO gas after the tray 12 moves to the open position and before the tray 12 holding the substrates W returns to the closed position. The purge process will be described in detail later.

[0054] After the purging step is performed, the tray 12 holding the substrates W is returned to the closed position, and the processing vessel 11 is hermetically sealed with the lid 13, at which point the supercritical processing begins. Each step of the supercritical processing will be briefly explained below with reference to FIGS. 5A to 5E. In FIGS. 5A to 5E, on-off valves shaded in gray are in the closed state, and on-off valves that are not shaded are in the open state. To simplify the drawings, gas lines and flow control devices (on-off valves, etc.) related to the purging step are omitted from FIGS. 5A to 5E.

[0055] [Pressure increase process] First, a boosting process is carried out, which is divided into an initial deceleration boosting stage and a subsequent normal boosting stage.

[0056] <Deceleration boost stage> First, each on-off valve is set to the state shown in FIG. 5A, and the opening degree of the control valve 40 is fixed to an appropriate fixed opening degree, for example, 2.5%. A portion (for example, about 35%) of the CO2 sent in a supercritical state from the supercritical fluid supply device 30 to the main supply line 32 is discharged through the depressurization line 66 provided with the orifice OLF, and the remainder flows into the first supply line 34. A portion (for example, about 35%) of the CO2 that has flowed into the first supply line 34 flows into the processing vessel 11 via the first discharge part 21. The remainder of the CO2 that has flowed through the first supply line 34 does not flow into the processing vessel 11 but flows into the discharge lines 38 and 50 through the bypass line 44 and is blocked by the on-off valves V5 to V8, which are in a closed state.

[0057] Immediately after the start of the deceleration pressure increase stage, the pressure of the CO2 delivered in a supercritical state from the supercritical fluid supply device 30 gradually decreases, but the decrease is particularly large when the CO2 flows into the processing vessel 11, which has a relatively large volume and is at atmospheric pressure. That is, at the beginning of the introduction of CO2 into the processing vessel 11, the pressure of CO2 in the processing vessel 11 is lower than the critical pressure (e.g., about 8 MPa), so the CO2 is in a gaseous state. Because the difference between the pressure in the first supply line 34 and the pressure in the processing vessel 11 at atmospheric pressure is very large, the gaseous CO2 flows into the processing vessel 11 at a high flow rate, which may disturb the IPA puddle on the surface of the substrate W and cause pattern collapse.

[0058] During the deceleration / pressurization stage, a portion of the CO2 flowing through the main supply line 32 is vented to the depressurization line 66, and a portion of the CO2 flowing through the first supply line 34 is vented to the bypass line 44, thereby reducing the flow rate of CO2 into the processing vessel 11. The orifice (OLF) in the first supply line 34 also contributes to reducing the flow rate of CO2 flowing into the processing vessel 11. Furthermore, CO2 flowing into the processing vessel 11 from the first discharge unit 21 collides with the plate 15 of the tray 12, then bypasses the plate 15 and enters the upper space 11A where the substrate W is located, thereby reducing the flow rate of CO2 gas flowing near the substrate W. These measures significantly reduce the possibility of pattern collapse.

[0059] When the pressure inside the processing vessel 11 increases to a certain level, the flow rate of CO2 flowing into the processing vessel 11 decreases, and pattern collapse caused by CO2 flowing at a high flow rate around the substrate W becomes less likely to occur. When this occurs, the process moves to the normal pressure increase stage. <Normal pressure boost stage>

[0060] That is, first, each on-off valve is set to the state shown in Figure 5B, and the discharge of CO2 from the main supply line 32 via the depressurization line 66 is stopped. As a result, the pressure inside the treatment vessel 11 increases at a higher pressure increase rate than in the deceleration pressure increase stage. At the same time, the pressure inside the lines 44, 38, 50, 54, and 56, whose downstream ends are blocked by the on-off valves V5 to V8, also increases. By doing so, the pressure inside the treatment vessel 11 does not suddenly drop immediately after the transition to the circulation process.

[0061] When the pressure inside the processing vessel 11 exceeds the critical pressure of CO2 (approximately 8 MPa), the CO2 (CO2 not mixed with IPA) present inside the processing vessel 11 becomes supercritical. When the CO2 inside the processing vessel 11 becomes supercritical, the IPA on the substrate W begins to dissolve into the CO2 in the supercritical state. The pressure increase stage is usually continued until the pressure inside the processing vessel 11 reaches a pressure (supercritical state guarantee pressure) that guarantees that the mixed fluid (CO2 + IPA) on the substrate W is maintained in a supercritical state, regardless of the IPA concentration in the mixed fluid and the temperature of the mixed fluid. The supercritical state guarantee pressure is generally about 16 MPa.

[0062] <Distribution process> When the pressure sensor PS12 detects that the pressure inside the processing vessel 11 has reached the supercritical state guarantee pressure (16 MPa), the on-off valves are set to the state shown in Fig. 5C and the operation mode of the regulator valve 40 is switched to the feedback control mode. At this time, the control unit 100 (or its subordinate controller) executes feedback control to adjust the opening degree (operated variable MV) of the regulator valve 40 based on the deviation between the pressure inside the processing vessel 11 (measured value PV) detected by the pressure sensor PS12 and the set value SV so that the pressure inside the processing vessel 11 is maintained at the set value (set value SV = 16 MPa).

[0063] In the flow process, supercritical CO2 supplied from the second discharge unit 22 into the processing vessel 11 flows in the region above the substrate and is then discharged from the fluid discharge unit 24. At this time, a laminar flow of supercritical CO2 flowing approximately parallel to the surface of the substrate W is formed in the processing vessel 11. IPA in the mixed fluid (IPA+CO2) on the surface of the substrate W exposed to the laminar flow of supercritical CO2 is gradually replaced with supercritical CO2. Eventually, almost all of the IPA on the surface of the substrate W is replaced with supercritical CO2.

[0064] The mixed fluid consisting of IPA and supercritical CO discharged from the fluid discharge portion 24 flows through the discharge line 38 (and the branch discharge lines 54, 56) and is then recovered. The IPA contained in the mixed fluid can be separated and reused.

[0065] <Discharge process> Once the replacement of IPA with supercritical CO2 is complete, the on-off valves are returned to the state shown in FIG. 5D, the supply of CO2 to the processing vessel 11 is stopped, and the set pressure of the processing vessel 11 is lowered to atmospheric pressure. This significantly increases the opening of the control valve 40, and the pressure inside the processing vessel 11 is gradually lowered to atmospheric pressure. As a result, the supercritical CO2 that was within the pattern on the substrate W becomes gas and escapes from the pattern, and the gaseous CO2 is discharged from the processing vessel 11. Finally, the on-off valves are returned to the state shown in FIG. 5E, and the CO2 remaining between on-off valves V1 and V4 is evacuated. This completes the drying of the substrate W.

[0066] <Substrate unloading process> The tray 12 carrying the dried substrate W is moved to the open position, and the substrate W is removed from the processing unit 10 (from inside the housing in which the processing unit 10 is installed) by a known method. At this time, for example, the above-mentioned lift pins may lift the substrate W on the tray 12 in the open position, and then a substrate transport arm (not shown) may receive the substrate W from the lift pins. The substrate transport arm may place the next substrate W on the lift pins, and continue the substrate loading process for the next substrate W. In this case, too, the purging process is carried out while the tray 12 is in the open position.

[0067] [Purge process] Next, the purging process will be described in detail. The purging process is performed while the tray 12 is in the open position for loading the substrate W into the processing vessel 11. When the opening 11C of the processing vessel 11 is opened, the ambient atmosphere (usually the air atmosphere) of the processing vessel 11 enters the processing vessel 11, for example, by interdiffusion. The air contains gases other than the carbon dioxide (CO2) processing fluid, such as oxygen (O2), nitrogen (N2), water vapor (H2O), and ammonia (for convenience of explanation, gases other than carbon dioxide gas are referred to as "impurity gases"). If the supercritical drying process is started when impurity gases are present in the processing vessel 11, there is a risk that foreign matter originating from the impurity gas will remain on the surface of the substrate after the supercritical drying process. In particular, water and ammonia have higher critical temperatures and pressures than carbon dioxide, which may result in defects such as pattern collapse. To solve this potential problem, in the purge step, CO 2 gas is supplied as a purge gas into the processing vessel 11 while the processing vessel 11 is open in order to reduce the concentration of impurity gases inside the processing vessel 11.

[0068] <First embodiment of purging process> In the first embodiment, the purge gas supply source 81 From the gas supply line 62, the junction 60, the first supply line 34, and the first discharge portion 21, CO2 gas (purge gas 4. That is, on-off valves V1, V2, V3, and V4 are closed, and on-off valve V11 is open. The other on-off valves (on-off valves not directly involved in the flow of fluid into or out of the processing vessel) may be in any state, and may be set to a state that allows for a smooth transition to the next step, the pressurization step, for example.

[0069] The CO gas flowing into the processing vessel 11 from the first discharge unit 21 spreads throughout the processing vessel 11 as shown by arrow F2 in FIG. 3, and then flows out of the opening 11C of the processing vessel 11 as shown by arrow F3. This increases the concentration of CO gas in the processing vessel 11, while decreasing the concentration of impurity gases.

[0070] At this time, the on-off valves V5, V6, V7, and V8 may be closed, and the on-off valve V12 may be open. discharge Since the line 38 is connected to a fluid recovery device (not shown) and is under negative pressure, a suction force acts on the gas recovery unit 28. Therefore, the CO2 gas flowing out from the opening 11C of the processing vessel 11, which is indicated by an arrow F3, is sucked into the gas recovery unit 28 and flows through the gas recovery line 70 and discharge The gas flows into the fluid recovery device through the line 38. In order to apply a stronger suction force to the gas recovery section 28, a negative pressure generating device such as a suction pump or an ejector may be provided in the gas recovery line 70 or in the flow path downstream thereof.

[0071] At this time, the on-off valve V13 may be opened to discharge CO2 gas (shielding gas) from the curtain gas discharge section 26. The CO2 gas discharged from the curtain gas discharge section 26 flows toward the gas recovery section 28 as shown by the arrow F4 in FIG. 3, forming a gas curtain between the curtain gas discharge section 26 and the gas recovery section 28. This prevents air outside the gas curtain from penetrating inside the gas curtain, thereby improving purging efficiency.

[0072] <Second embodiment of purging process> In the second embodiment, CO gas (purge gas) is supplied from the purge gas supply source to the processing vessel 11 via the junction 74, the second supply line 36, and the second outlet 22 (see FIG. 4B). In this case, the on-off valves V1, V2, V3, and V4 may be closed, and the other on-off valves (on-off valves not directly involved in the flow of fluid into and out of the processing vessel) may be in any state.

[0073] In this case, the CO gas flows into the processing vessel 11 from the second discharge part 22, flows toward the opening 11C of the processing vessel 11 as shown by the arrow F1 in Fig. 3, and then flows out from the opening 11C. According to the second embodiment, the CO gas is discharged toward the opening 11C from the position farthest from the opening 11C (the position farthest from the opening 11C in the X direction), thereby improving the purge efficiency.

[0074] In the second embodiment, the gas recovery unit 28 and the curtain gas discharge unit 26 may be operated in the same manner as in the first embodiment.

[0075] <Third embodiment of purging process> In the third embodiment, the curtain gas discharge part 26 is also used as a discharge part for purge gas, and the first discharge part 21 is used as a gas recovery part. By closing the on-off valves V1, V2, V3, V6, V7, and V8 and opening the on-off valves V4 and V5, the first discharge part 21 is used to discharge the purge gas through a part of the first supply line 34 and the bypass line 44. discharge By connecting to the line 38, a negative pressure can be applied to the first discharge part 21. As a result, as shown by the arrow F6 in Fig. 3, the CO2 gas can be discharged from the processing vessel 11 via the first discharge part 21, and the CO2 gas discharged by the curtain gas discharge part 26 can be drawn into the processing vessel 11. This also allows the processing vessel 11 to be purged with CO2 gas.

[0076] <Fourth embodiment of purging process> No. 4 In this embodiment, the processing fluid (CO2) supplied from the supercritical fluid supply device 30 is gasified and used as a purge gas. By closing the on-off valves V2, V3, and V4 and opening the on-off valves V9 and V1, gaseous CO2 can be discharged as a purge gas from the first discharge part 21 into the processing vessel 11, similar to the initial stage of the pressurization step. The second embodiment may be the same as the first embodiment, except that the processing fluid (CO2) supplied from the supercritical fluid supply device 30 is gasified and used as a purge gas.

[0077] It is also possible to discharge a purge gas obtained by gasifying the processing fluid supplied from the supercritical fluid supply device 30 into the processing vessel 11 from the second discharge part 22. In this case, however, the filter FL2, which does not have an orifice OLF on the upstream side, may be damaged by the pressure difference. Therefore, it is preferable to provide an appropriate pressure reducing means (for example, a valve with an adjustable opening) on ​​the upstream side of the filter FL2.

[0078] When the fluid discharge part 24 is located near the opening 11C of the processing vessel 11, the fluid discharge part 24 can be used as a gas recovery part in the first to fourth embodiments of the purging process. In this case, by opening the on-off valves V3 and V5 and fixing the opening of the control valve 40 to an appropriately large opening during the purging process, a suction force acts on the fluid discharge part 24. In this case, the CO2 gas discharged from the curtain gas discharge part 26 is drawn into the processing vessel 11, and the CO2 gas discharged from the first discharge part 21 (or the second discharge part 22) also flows toward the fluid discharge part 24, so that gas purging of the processing vessel 11 can be performed without any problems.

[0079] [Timing of purging process completion] In one embodiment, when it is detected that the CO2 concentration in the processing vessel 11 exceeds a predetermined threshold (e.g., 80%), the control unit 100 ends the purging process, moves the tray 12 on which the substrates W are placed to the closed position, accommodates the substrates W in the processing vessel 11, and closes the opening 11C of the processing vessel 11. Thereafter, the control unit 100 executes a pressure increase process.

[0080] The CO2 concentration can be detected, for example, by a CO2 concentration meter (concentration sensor) installed in the treatment vessel 11 or between the treatment vessel 11 and the on-off valve V3 on the exhaust line 38. In Figure 4, the CO2 concentration meter installed in the treatment vessel 11 is indicated by a circled S.

[0081] Alternatively, the CO concentration may be considered to have exceeded a predetermined threshold value when CO gas has been supplied to the processing vessel 11 for a predetermined time. The "predetermined time" can be determined through experiments using an actual supercritical processing apparatus.

[0082] The supply of CO2 gas (purge gas) into the processing chamber 11 is performed by the tray holding the substrate W. 12 It is preferable to continue supplying CO2 gas to the processing vessel 11 at a flow rate that does not adversely affect the IPA puddle on the substrate W while the tray holding the substrate W is closed. 12 can also be moved to a closed position.

[0083] [First Modified Embodiment of Processing Unit] As shown in FIG. 6, a means for creating a CO gas atmosphere around the opening 11C of the processing vessel 11 may be provided. In the configuration example shown in FIG. 6, a gas discharge unit 102 is installed inside a housing 100 surrounding the processing unit 10 (e.g., in the ceiling of the housing 100). The gas discharge unit 102 is located above the tray 12 in the open position and can discharge CO gas downward toward the tray 12. The downflow of CO gas from the gas discharge unit 102 creates a CO gas atmosphere around the tray 12 and around the opening 11C of the processing vessel 11. Therefore, in this case, the curtain gas discharge unit 26 may not be provided. This configuration is advantageous in that it reduces the amount of impurity gas flowing into the processing vessel 11 between the time the supply of CO gas (purge gas) into the processing vessel 11 is stopped and the time the tray 12 carrying the substrates W is moved to the closed position.

[0084] A gas recovery unit 104 is provided below the tray 12 when it is in the open position, and is designed to recover gas within the housing 100. This prevents high-concentration CO2 gas from leaking outside the housing 100. If the gas recovery unit 104 is provided, the gas recovery unit 28 may be omitted. The gas recovery units (28, 104) are provided primarily for the purpose of complying with safety regulations regarding hazardous gases, and the means by which CO2 gas is recovered is optional.

[0085] Clean air can also be discharged from the gas discharge portion 102. When it is necessary to create an atmosphere inside the housing 100 that is harmless to humans during maintenance or the like, the inside of the housing 100 can be purged by collecting gas in the gas recovery portion 104 while discharging clean air from the gas discharge portion 102.

[0086] 6, the atmosphere around the opening 11C of the processing vessel 11 can be filled with CO2 gas, which makes it possible to efficiently perform the purge processes according to the first to fourth embodiments, particularly the purge process according to the third embodiment. In the purge process according to the third embodiment, the atmosphere inside the processing vessel 11 is sucked from the first discharge unit 21, thereby drawing the CO2 gas around the opening 11C into the processing vessel 11, thereby purging the processing vessel 11 with CO2 gas.

[0087] 6 are lift pins that can lift the substrate W on the tray 12. The lift pins 300 can move up and down through the through holes 18 of the tray 12. The substrate W that has been lifted above the tray 12 by the lift pins can be received by a substrate transport arm (not shown) that has entered the housing 100. When loading the substrate W, the substrate transport arm (not shown) places the substrate W on the lift pins 300 that are in the raised position, and then the lift pins 300 are lowered to below the tray 12, thereby placing the substrate W on the tray 12. [Second Modified Embodiment of Processing Unit]

[0088] A second modified embodiment of the processing unit is shown in Figure 7. In Figure 7, reference numerals indicating components that perform similar functions to those in the embodiments shown in Figures 1 to 4 have been increased by 200.

[0089] The processing unit 200 shown in Figure 7 has a cylindrical processing vessel 211 having an opening 211C at the top, and a movable lid 213 that closes the opening 211C of the processing vessel 211. The lid 213 is provided with a substrate holder 214 that holds a substrate W. In Figure 7, the lid 213 in the closed position is shown by a solid line, and the lid 213 in the open position is shown by a dashed line. When the lid 213 is in the open position, the substrate W can be transferred between the substrate holder 214 and a substrate transfer arm (not shown). Supercritical drying processing is performed with the lid 213, with the substrate W held by the substrate holder 214, in the closed position.

[0090] A first discharge part 221 and a fluid discharge part 224 are provided at the bottom of the processing vessel 211. A second discharge part 222 is provided on the lid 213. A baffle plate 215 is provided above the first discharge part 221 to prevent the processing fluid discharged from the first discharge part 221 from being directed directly toward the substrate W. During supercritical drying processing, the first discharge part 221 plays the same role as the first discharge part 21 of the processing unit 10 described above, the second discharge part 222 plays the same role as the first discharge part 22 of the processing unit 10 described above, and the fluid discharge part 224 plays the same role as the fluid discharge part 24 of the processing unit 10 described above.

[0091] In the processing unit 200 shown in FIG. 7, CO2 purging can be performed in the same manner as in the processing unit 10 described above. For this purpose, the processing fluid ( superA gas line 262 can be connected to a supply line 234 that supplies supercritical CO2. With the lid 213 in the open position, CO2 gas is supplied from the CO2 gas supply source 264 through the gas line 262 and the supply line 234 to the first discharge unit 221 into the processing vessel 211. This allows the gas inside the processing vessel 211 to be purged. At this time, a gas recovery unit 228 is provided around the gap between the opening 211C of the processing vessel 211 and the lid 213 to recover CO2 gas leaking from the gap.

[0092] 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.

[0093] The substrate is not limited to a semiconductor wafer, but may be any other type of substrate used in the manufacture of semiconductor devices, such as a glass substrate or a ceramic substrate. [Explanation of symbols]

[0094] W substrate 11 Processing container 12M Lid movement mechanism 13 Lid 14 Board holding part 34, 36, 62 etc. Supply lines V1~V13, FM, OLF, etc. Flow control equipment 100 control section

Claims

1. A substrate processing apparatus that dries a substrate having a liquid attached to its surface using a supercritical drying technique, a processing vessel having an opening for loading and unloading the substrate into and from the processing vessel; a movable lid that closes the opening of the processing vessel; a lid movement mechanism that moves the lid between a closed position that closes the opening and an open position that opens the opening; a substrate holder configured to horizontally hold the substrate with the surface facing upward in the processing chamber; a fluid supply mechanism configured to supply a processing fluid in a supercritical state and a gaseous fluid of the same substance as the processing fluid in the supercritical state to the processing vessel, the fluid supply mechanism including at least one supply line and a flow control device; a control unit that controls the fluid supply mechanism so that the supercritical processing fluid is supplied to the processing vessel when the substrate is held in the processing vessel by the substrate holding unit and the lid is in the closed position in a first state, and so that the gaseous fluid is supplied to the processing vessel when the substrate is not held in the processing vessel by the substrate holding unit and the lid is in the open position in a second state; Equipped with a first fluid supply unit capable of supplying the processing fluid in a supercritical state and a second fluid supply unit capable of supplying the gaseous fluid are connected to the fluid supply mechanism; the control unit controls the fluid supply mechanism so that the processing fluid is supplied from the first fluid supply unit to the processing vessel in the first state, and the gaseous fluid is supplied from the second fluid supply unit to the processing vessel in the second state; the processing vessel includes a first discharge unit provided at a lower portion of the processing vessel and a second discharge unit configured to discharge the processing fluid toward the opening from a position away from the opening, a first supply line and a second supply line are connected to the first fluid supply unit; the first supply line is connected to the first discharge portion, the second supply line is connected to the second outlet, the second fluid supply is connected to a second supply line; The control unit controls the fluid supply mechanism so that the gaseous fluid is supplied to the processing vessel through the second discharge unit in the second state.

2. 2. The substrate processing apparatus of claim 1, wherein the control unit controls the fluid supply mechanism so that the gaseous fluid is supplied to the processing vessel in the second state, and then the substrate is loaded into the processing vessel and the lid is closed to enter the first state.

3. 3. The substrate processing apparatus according to claim 1, further comprising a fluid recovery unit provided near the opening for sucking and recovering the gaseous fluid that has flowed out of the opening after being supplied to the processing vessel or the gaseous fluid that is about to flow out.

4. 4. The substrate processing apparatus of claim 3, wherein the processing vessel is configured so that the substrate is loaded and unloaded horizontally through the opening, the fluid recovery unit is provided below a movement trajectory of the substrate when loaded and unloaded into the processing vessel, and the gaseous fluid flowing out from the opening flows downward into the fluid recovery unit.

5. 5. The substrate processing apparatus according to claim 1, further comprising: a curtain gas discharge unit that discharges the processing fluid near the opening to form a gas curtain that suppresses an inflow of outside air into the opening.

6. a concentration sensor for measuring a concentration of the processing fluid in the processing vessel; 6. A substrate processing apparatus as described in any one of claims 1 to 5, wherein the control unit controls the fluid supply mechanism to stop the supply of the gaseous fluid to the processing vessel when the value of the concentration sensor becomes greater than or equal to a predetermined threshold value while the gaseous fluid is being supplied to the processing vessel in the second state.

7. a concentration sensor for measuring a concentration of the processing fluid in the processing vessel; 7. A substrate processing apparatus according to claim 1, wherein when the gaseous fluid is being supplied to the processing vessel in the second state and the value of the concentration sensor becomes equal to or greater than a predetermined threshold, the control unit controls the lid moving mechanism to move the lid to the closed position and transition to the first state.

8. 8. A substrate processing apparatus according to claim 1, wherein the lid body and the substrate holding part are integrally connected, and the substrate held by the substrate holding part is transported into the processing vessel by moving the lid body to a closed position.

9. The substrate processing apparatus according to claim 8 , wherein the substrate held by the substrate holder is carried into the processing chamber in a horizontal direction.

10. the processing vessel has the opening at its upper end, The substrate processing apparatus according to claim 8 , wherein the substrate held by the substrate holder is carried into the processing chamber in a vertical direction.

11. The substrate processing apparatus of claim 10, further comprising a fluid recovery unit provided around the opening, which recovers the gaseous fluid that is supplied to the processing vessel and then flows out of the opening when the lid is in the open position.

12. A substrate processing method performed by a substrate processing apparatus, comprising: a processing vessel having an opening for loading and unloading a substrate into and from the processing vessel; a movable lid that closes the opening of the processing vessel; a substrate holder configured to horizontally hold the substrate with its surface facing upward in the processing chamber; a fluid supply mechanism configured to supply a processing fluid in a supercritical state and a gaseous fluid of the same substance as the processing fluid in the supercritical state to the processing vessel, the fluid supply mechanism including at least one supply line and a flow control device; Equipped with a first fluid supply unit capable of supplying the processing fluid in a supercritical state and a second fluid supply unit capable of supplying the gaseous fluid are connected to the fluid supply mechanism; the processing vessel includes a first discharge unit provided at a lower portion of the processing vessel and a second discharge unit configured to discharge the processing fluid toward the opening from a position away from the opening, a first supply line and a second supply line are connected to the first fluid supply unit; the first supply line is connected to the first discharge portion, the second supply line is connected to the second outlet, The second fluid supply is connected to a second supply line. The substrate processing method performed by the substrate processing apparatus, a supercritical drying process including the step of carrying the substrate having a liquid adhering to the surface into the processing vessel by the substrate holder, supplying a processing fluid in a supercritical state into the processing vessel by the first fluid supply unit and circulating the processing fluid within the processing vessel, thereby replacing the liquid with the processing fluid in the supercritical state; a purging step in which, before the supercritical drying step, when the lid body opens the opening to load the substrate into the processing vessel, the second fluid supply unit supplies a purge gas into the processing vessel via the second discharge unit to create a purge gas atmosphere inside the processing vessel.

13. 13. The substrate processing method according to claim 12, further comprising the steps of: stopping the supply of purge gas into the processing vessel; loading the substrate into the processing vessel; closing the lid; and then performing the supercritical drying process.

14. 14. The substrate processing method of claim 13, wherein when a concentration sensor detects that the purge gas concentration in the processing vessel has reached a predetermined threshold or higher, the supply of purge gas into the processing vessel is stopped and the substrate is loaded into the processing vessel.

15. 13. The substrate processing method according to claim 12, wherein the purging step includes sucking and recovering the purge gas that has been supplied into the processing vessel and then flowed out through the opening or that is about to flow out.

16. 13. The substrate processing method of claim 12, wherein in the purging step, the purge gas is supplied from a purge gas supply source to a supply line for supplying the supercritical processing fluid to the processing vessel, and the purge gas is supplied to the processing vessel via the supply line.

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