Substrate processing apparatus and substrate processing method

Abstract

To provide a substrate processing apparatus and a substrate processing method that suppresses collapse of patterns formed on the surface of the substrate.SOLUTION: A substrate processing apparatus 300 that dries a substrate W with fluid on its surface using a supercritical state processing fluid, performs: a process for supplying the processing fluid from a fluid supply tank 52, which is the supply source, into a processing vessel 301 to increase the pressure in the processing vessel to a process pressure higher than the critical pressure of the processing fluid; and a process for draining the processing fluid from the processing vessel while maintaining the pressure at which the supercritical state is maintained, and the process for increasing pressure to the process pressure includes a process for increasing the pressure in the processing vessel to a first pressure that is higher than the critical pressure and lower than the process pressure and a process for increasing from the first pressure to the process pressure.SELECTED DRAWING: Figure 6

Description

[Technical Field]

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

[0002] In the manufacturing process of a semiconductor device, in which a laminated structure of integrated circuits is formed on the surface of a substrate such as a semiconductor wafer (hereinafter referred to as a wafer), liquid processing such as chemical cleaning or wet etching is performed. In recent years, drying methods using a processing fluid in a supercritical state have been increasingly used to remove liquids and the like adhering to the wafer surface during such liquid processing.

[0003] Patent Document 1 discloses a substrate processing apparatus in which a first fluid supply unit is provided below a substrate held by a substrate holder, and a second fluid supply unit is provided to the side of the substrate held by the substrate holder. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 2018-74103 Summary of the Invention [Problem to be solved by the invention]

[0005] The present disclosure provides a substrate processing apparatus and a substrate processing method that can prevent collapse of a pattern formed on the surface of a substrate. [Means for solving the problem]

[0006] A substrate processing apparatus according to one aspect of the present disclosure is a substrate processing apparatus that dries a substrate having a liquid adhering to its surface using a processing fluid in a supercritical state, the substrate processing apparatus comprising: a processing vessel that accommodates the substrate; a substrate holding unit that holds the substrate horizontally in the processing vessel with the surface facing upward; a fluid supply unit that supplies the processing fluid into the processing vessel; a fluid discharge unit that discharges the processing fluid from the processing vessel; and a control unit that controls at least the operation of the fluid supply unit and the fluid discharge unit, wherein the control unit controls the operation of the fluid supply unit and the fluid discharge unit to supply the processing fluid into the processing vessel that accommodates the substrate having a liquid adhering to its surface, thereby increasing the pressure in the processing vessel to a processing pressure higher than the critical pressure of the processing fluid. and 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 of increasing the pressure in the processing vessel to the processing pressure includes the steps of increasing the pressure in the processing vessel to a first pressure that is higher than the critical pressure but lower than the processing pressure, and increasing the pressure in the processing vessel from the first pressure to the processing pressure, wherein the fluid supply unit includes a first path that supplies the processing fluid into the processing vessel at a first temperature and a second path that supplies the processing fluid into the processing vessel at a second temperature that is higher than the first temperature. a first fluid supply unit that supplies the processing fluid into the processing vessel from below the substrate held by the substrate holding unit; and a second fluid supply unit that supplies the processing fluid into the processing vessel from a side of the substrate held by the substrate holding unit. and the first fluid supply unit includes the first path and a portion of the second path, and the second fluid supply unit includes a portion of the second path; In the step of increasing the pressure in the processing vessel to the first pressure, the processing fluid is supplied into the processing vessel through the first path, and in the step of supplying the processing fluid to the processing vessel and discharging the processing fluid from the processing vessel, the processing fluid is supplied into the processing vessel through a portion of the second path, and the paths of the processing fluid do not overlap between the step of increasing the pressure in the processing vessel to the first pressure and the step of supplying the processing fluid to the processing vessel and discharging the processing fluid from the processing vessel. [Effects of the Invention]

[0007] According to the present disclosure, it is possible to prevent collapse of a pattern formed on the surface of a substrate. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is a cross-sectional plan view showing the overall configuration of a substrate processing system. [Figure 2] FIG. 2 is an external perspective view of a processing vessel of the supercritical processing apparatus. [Figure 3] FIG. 2 is a cross-sectional view of a processing vessel. [Figure 4] FIG. 2 is a piping diagram of a supercritical processing apparatus. [Figure 5] FIG. 1 is a diagram illustrating the drying mechanism of IPA. [Figure 6] FIG. 2 is a piping diagram of a supercritical processing apparatus included in the substrate processing apparatus according to the first embodiment. [Figure 7] FIG. 1 is a diagram (part 1) illustrating an outline of a drying method in the first embodiment. [Figure 8] FIG. 2 is a diagram (part 2) showing an outline of the drying method in the first embodiment. [Figure 9] FIG. 3 is a diagram (part 3) showing an outline of the drying method in the first embodiment. [Figure 10] FIG. 4 is a diagram (part 4) illustrating an outline of the drying method in the first embodiment. [Figure 11] FIG. 10 is a view showing a holding plate included in a substrate processing apparatus according to a second embodiment. [Figure 12] FIG. 1 is a schematic diagram showing the content of an experiment on cleaning efficiency. [Figure 13] FIG. 10 is a diagram showing changes in pressure during cleaning. DETAILED DESCRIPTION OF THE INVENTION

[0009] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. In the drawings, the same or corresponding components are denoted by the same or corresponding reference numerals, and the description thereof may be omitted.

[0010] [Configuration of substrate processing system] As shown in FIG. 1, the substrate processing system 1 includes a plurality of cleaning devices 2 (two cleaning devices 2 in the example shown in FIG. 1) that supply a cleaning liquid to wafers W to perform cleaning processing, and a plurality of supercritical processing devices 3 (six supercritical processing devices 3 in the example shown in FIG. 1) that remove an anti-drying liquid (IPA: isopropyl alcohol in this embodiment) adhering to the wafers W after the cleaning processing by contacting the liquid with a processing fluid in a supercritical state (CO2: carbon dioxide in this embodiment).

[0011] In this substrate processing system 1, a FOUP (Front-Opening Unified Pod) 100 is placed on a placement section 11, and a wafer W stored in this FOUP 100 is transferred to a cleaning processing section 14 and a supercritical processing section 15 via a load / unload section 12 and a transfer section 13. In the cleaning processing section 14 and the supercritical processing section 15, the wafer W is first loaded into a cleaning apparatus 2 provided in the cleaning processing section 14 to undergo a cleaning process, and then loaded into a supercritical processing apparatus 3 provided in the supercritical processing section 15 to undergo a drying process to remove IPA from the wafer W. In FIG. 1 , reference numeral "121" denotes a first transfer mechanism that transfers the wafer W between the FOUP 100 and the transfer section 13, and reference numeral "131" denotes a transfer shelf that serves as a buffer on which the wafer W is temporarily placed to be transferred between the load / unload section 12 and the cleaning processing section 14 or the supercritical processing section 15.

[0012] A wafer transfer path 162 is connected to the opening of the transfer section 13, and a cleaning processing section 14 and a supercritical processing section 15 are provided along the wafer transfer path 162. In the cleaning processing section 14, one cleaning apparatus 2 is disposed on each side of the wafer transfer path 162, for a total of two cleaning apparatuses 2. Meanwhile, in the supercritical processing section 15, three supercritical processing apparatuses 3, which function as substrate processing apparatuses performing a drying process to remove IPA from wafers W, are disposed on each side of the wafer transfer path 162, for a total of six supercritical processing apparatuses 3. A second transfer mechanism 161 is disposed on the wafer transfer path 162, and the second transfer mechanism 161 is movable within the wafer transfer path 162. The wafer W placed on the transfer shelf 131 is received by the second transfer mechanism 161, and the second transfer mechanism 161 transfers the wafer W to the cleaning apparatus 2 and the supercritical processing apparatus 3. The number and arrangement of the cleaning devices 2 and supercritical processing devices 3 are not particularly limited, and an appropriate number of cleaning devices 2 and supercritical processing devices 3 are arranged in an appropriate manner depending on the number of wafers W processed per unit time and the processing time of each cleaning device 2 and each supercritical processing device 3, etc.

[0013] The cleaning apparatus 2 is configured as a single-wafer processing apparatus that cleans wafers W one by one, for example, by spin cleaning. In this case, the wafer W is held horizontally and rotated about a vertical axis, while a cleaning chemical and a rinse liquid for rinsing the chemical are supplied to the processing surface of the wafer W at appropriate times, thereby performing the cleaning process on the wafer W. The chemical and rinse liquids used in the cleaning apparatus 2 are not particularly limited. For example, an alkaline chemical, SC1 liquid (i.e., a mixture of ammonia and hydrogen peroxide), can be supplied to the wafer W to remove particles and organic contaminants from the wafer W. Then, deionized water (DIW) can be supplied to the wafer W as a rinse liquid to rinse the SC1 liquid from the wafer W. Furthermore, an acidic chemical, dilution hydrofluoric acid (DHF), can be supplied to the wafer W to remove native oxide, and then DIW can be supplied to the wafer W to rinse the dilution hydrofluoric acid from the wafer W.

[0014] After completing the rinsing process with DIW, the cleaning apparatus 2 supplies IPA to the wafer W as a liquid to prevent drying while rotating the wafer W, and replaces the DIW remaining on the processed surface of the wafer W with IPA. Then, the rotation of the wafer W is gradually stopped. At this time, a sufficient amount of IPA has been supplied to the wafer W, and the surface of the wafer W on which the semiconductor pattern has been formed is covered with a puddle of IPA, and a liquid film of IPA is formed on the surface of the wafer W. The wafer W is transferred out of the cleaning apparatus 2 by the second transfer mechanism 161 while maintaining the puddle of IPA.

[0015] The IPA applied to the surface of the wafer W in this manner serves to prevent drying of the wafer W. In particular, to prevent so-called pattern collapse on the wafer W due to evaporation of IPA during transfer of the wafer W from the cleaning apparatus 2 to the supercritical processing apparatus 3, the cleaning apparatus 2 applies a sufficient amount of IPA to the wafer W so that an IPA film having a relatively large thickness is formed on the surface of the wafer W.

[0016] The wafer W transferred from the cleaning apparatus 2 is transferred by the second transfer mechanism 161 into the processing vessel of the supercritical processing apparatus 3 with the IPA still thereon, and is subjected to a drying process with the IPA in the supercritical processing apparatus 3.

[0017] [Supercritical processing equipment] Hereinafter, the configuration common to each embodiment of the supercritical processing apparatus 3 will be described with reference to FIGS.

[0018] As shown in Figures 2 and 3, the processing vessel 301 includes a vessel body 311 having an opening 312 for loading and unloading the wafer W, a holding plate 316 for holding the wafer W to be processed horizontally, and a lid member 315 for supporting the holding plate 316 and sealing the opening 312 when the wafer W is loaded into the vessel body 311.

[0019] The vessel body 311 is a vessel having a processing space formed therein that can accommodate, for example, a wafer W having a diameter of 300 mm. A fluid supply header 317 is provided at one end of the vessel body 311, and a fluid discharge header 318 is provided at the other end. In the illustrated example, the fluid supply header 317 is made of a block body having a number of openings, and the fluid discharge header 318 is made of a pipe having a number of openings (fluid discharge ports). It is preferable that the first fluid supply port of the fluid supply header 317 is located slightly higher than the upper surface of the wafer W held by the holding plate 316.

[0020] The configurations of the fluid supply header 317 and the fluid discharge header 318 are not limited to the illustrated example, and for example, the fluid discharge header 318 may be formed from a block body, and the fluid supply header 317 may be formed from a pipe.

[0021] When viewed from below, holding plate 316 covers almost the entire lower surface of wafer W. Holding plate 316 has opening 316a at the end on the lid member 315 side. Processing fluid in the space above holding plate 316 passes through opening 316a and is guided to fluid discharge header 318 (see arrow F5 in FIG. 3).

[0022] The fluid supply header 317 supplies the processing fluid into the vessel body 311 (processing vessel 301) in a substantially horizontal direction. The horizontal direction here refers to a direction perpendicular to the vertical direction in which gravity acts, and is usually a direction parallel to the direction in which the flat surface of the wafer W held on the holding plate 316 extends.

[0023] The fluid inside the processing vessel 301 is discharged to the outside of the processing vessel 301 via the fluid discharge header 318. The fluid discharged via the fluid discharge header 318 includes not only the processing fluid supplied into the processing vessel 301 via the fluid supply header 317, but also IPA adhering to the surface of the wafer W and dissolved in the processing fluid.

[0024] A fluid supply nozzle 341 is provided at the bottom of the vessel body 311 to supply a processing fluid into the processing vessel 301. In the illustrated example, the fluid supply nozzle 341 is an opening formed in the bottom wall of the vessel body 311. The fluid supply nozzle 341 is located below (e.g., directly below) the center of the wafer W, and supplies the processing fluid into the processing vessel 301 toward (e.g., vertically upward) the center of the wafer W.

[0025] The processing vessel 301 further includes a pressing mechanism (not shown). This pressing mechanism presses the lid member 315 toward the vessel body 311 against the internal pressure caused by the processing fluid in a supercritical state supplied into the processing space, thereby sealing the processing space. In addition, it is preferable to provide a heat insulating material, a tape heater, or the like (not shown) on the ceiling wall and bottom wall of the vessel body 311 so that the processing fluid supplied into the processing space can be kept at a supercritical temperature.

[0026] 4, the supercritical processing apparatus 3 has a fluid supply tank 51 which is a supply source of a processing fluid. A main supply line 50 is connected to the fluid supply tank 51. The main supply line 50 branches into a first supply line 63 connected to a fluid supply header 317 in the processing vessel 301 and a second supply line 64 connected to a fluid supply nozzle 341.

[0027] Between the fluid supply tank 51 and the fluid supply header 317 (i.e., in the main supply line 50 and the first supply line 63 connected thereto), a vaporizer 71 and an on-off valve 55a are provided in this order from the upstream side. The vaporizer 71 vaporizes the processing fluid supplied from the fluid supply tank 51 and supplies gas at a predetermined temperature downstream. The second supply line 64 branches off from the main supply line 50 at a position between the vaporizer 71 and the on-off valve 55a. The second supply line 64 is provided with an on-off valve 55b.

[0028] A discharge line 65 is connected to the fluid discharge header 318 in the processing vessel 301. An on-off valve 55c and a pressure adjustment valve 55d are provided in this order from the upstream side on the discharge line 65. The opening degree of the pressure adjustment valve 55d is adjusted by the control unit 4. The control unit 4 performs, for example, PID control (Proportional-Integral-Differential Controller) of the opening degree of the pressure adjustment valve 55d.

[0029] A line heater H1 is provided between the vaporizer 71 and the on-off valves 55a and 55b. Line heaters H2 and H3 are provided between the on-off valve 55b and the fluid supply nozzle 341. The line heater H2 is provided upstream of the line heater H3. A line heater H4 is provided between the on-off valve 55a and the fluid supply header 317. The set temperatures of the line heaters H1 to H4 can be independently controlled by the control unit 4.

[0030] Pressure sensors for detecting the pressure in the lines and temperature sensors for detecting the temperature of the fluid are installed at various locations in the lines through which the fluid of the supercritical processing apparatus 3 flows. Furthermore, a pressure sensor 53 for detecting the pressure in the processing vessel 301 and a temperature sensor 54 for detecting the temperature of the fluid in the processing vessel 301 are provided.

[0031] The control unit 4 receives measurement signals from various sensors (such as the pressure sensor 53 and the temperature sensor 54) shown in FIG. 3 and transmits control signals (such as opening / closing signals for the on-off valves 55a to 55c and an opening degree signal for the pressure adjustment valve 55d) to various functional elements. The control unit 4 is, for example, a computer and includes an arithmetic unit 18 and a storage unit 19. The storage unit 19 stores programs for controlling various processes executed in the substrate processing system 1. The arithmetic unit 18 controls the operation of the substrate processing system 1 by reading and executing the programs stored in the storage unit 19. The programs may be recorded on a computer-readable storage medium and installed from the storage medium into the storage unit 19 of the control unit 4. 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.

[0032] [Supercritical drying process] Next, the drying mechanism of IPA using a processing fluid (for example, carbon dioxide (CO2)) in a supercritical state will be briefly described with reference to FIG.

[0033] Immediately after the processing fluid R in a supercritical state is introduced into the processing vessel 301, only IPA exists in the recesses of the pattern P on the wafer W, as shown in FIG. 5(a).

[0034] The IPA in the recessed portion comes into contact with the processing fluid R in a supercritical state, and gradually dissolves in the processing fluid R, and as shown in Fig. 5(b), is gradually replaced by the processing fluid R. At this time, in addition to the IPA and processing fluid R, a mixed fluid M in which the IPA and processing fluid R are mixed exists in the recessed portion.

[0035] As the replacement of IPA with processing fluid R progresses within the recess, the amount of IPA present within the recess decreases, and eventually, as shown in Figure 5(c), only processing fluid R in a supercritical state remains within the recess.

[0036] After the IPA is removed from the recesses, the pressure in the processing vessel 301 is reduced to atmospheric pressure, whereby the processing fluid R changes from a supercritical state to a gaseous state, and the recesses are occupied only by gas, as shown in Fig. 5(d). In this way, the IPA in the recesses of the pattern P is removed, and the drying process of the wafer W is completed.

[0037] On the other hand, pattern collapse may occur in the drying process using the processing fluid R in the substrate processing system 1 described above. As a result of extensive research by the present inventors into the cause of pattern collapse, it was found that before the IPA in the recesses is replaced with the processing fluid R, the temperature of the IPA in the recesses rises due to the heat of the processing fluid R, causing a portion of the IPA to evaporate. It was also found that when the drying process is performed at a temperature at which the IPA is unlikely to evaporate, the IPA is unlikely to dissolve in the supercritical processing fluid R, and the IPA is not sufficiently replaced by the supercritical processing fluid R, which makes it likely to cause pattern collapse.

[0038] Based on these findings, the inventors of the present application conducted further intensive studies and found that it is possible to suppress the temperature rise and evaporation of the IPA before replacement and to suppress pattern collapse by appropriately adjusting the temperature of the wafer W during the period in which the pressure in the processing vessel 301 is increased. For example, it was found that it is possible to suppress pattern collapse by setting the temperature of the wafer W to a first temperature until the pressure in the processing vessel 301 reaches a predetermined first pressure, and then setting the temperature of the wafer W to a second temperature higher than the first temperature after the pressure in the processing vessel 301 reaches the first pressure.

[0039] The first temperature may be a temperature at which IPA does not easily evaporate before replacement, for example, 80°C to 90°C. The second temperature may be a temperature at which IPA easily dissolves in the supercritical processing fluid R, for example, 100°C to 120°C. The first pressure may be a pressure higher than the critical pressure of the processing fluid R. When CO2 is used as the processing fluid R, the critical pressure of CO2 is about 7 MPa, and the first pressure may be, for example, about 8 MPa.

[0040] (First embodiment) A description will be given of a substrate processing apparatus according to a first embodiment, which has a configuration suitable for adjusting the temperature of a wafer W. Fig. 6 is a piping diagram of a supercritical processing apparatus included in the substrate processing apparatus according to the first embodiment.

[0041] 6, the supercritical processing apparatus 300 provided in the substrate processing apparatus according to the first embodiment includes a fluid supply tank 52 serving as a processing fluid supply source in addition to the components of the supercritical processing apparatus 3 shown in FIG. 4. A third supply line 66 is connected to the fluid supply tank 52. The third supply line 66 is connected to the second supply line 64 downstream of the on-off valve 55b. That is, the third supply line 66 is connected to the fluid supply nozzle 341.

[0042] Between the fluid supply tank 52 and the fluid supply nozzle 341 (i.e., on the third supply line 66), a vaporizer 72 and an on-off valve 55e are provided in this order from the upstream side. The vaporizer 72 vaporizes the processing fluid supplied from the fluid supply tank 52 and supplies gas at a predetermined temperature downstream. The third supply line 66 is connected to the second supply line 64 downstream of the on-off valve 55e.

[0043] A line heater H6 is provided between the vaporizer 72 and the on-off valve 55e. A line heater H5 is provided between the on-off valve 55e and a portion where the third supply line 66 is connected to the second supply line 64. The set temperatures of the line heaters H5 and H6 can be controlled independently by the control unit 4.

[0044] For example, the first path includes the third supply line 66 and a portion of the second supply line 64. The vaporizer 72 is an example of a first vaporizer. For example, the second path includes the main supply line 50, the first supply line 63, and the second supply line 64. The vaporizer 71 is an example of a second vaporizer. For example, the first fluid supply unit includes the main supply line 50, the second supply line 64, the third supply line 66, and the fluid supply nozzle 341. For example, the second fluid supply unit includes the main supply line 50, the first supply line 63, and the fluid supply header 317. For example, the fluid discharge unit includes the fluid discharge header 318 and the discharge line 65.

[0045] In the first embodiment, the vaporizer 71 converts the processing fluid supplied from the fluid supply tank 51 into a gas at a second temperature, for example, 100°C to 120°C, and the vaporizer 72 converts the processing fluid supplied from the fluid supply tank 52 into a gas at a first temperature, for example, 80°C to 90°C. The second temperature is higher than the first temperature.

[0046] Next, a drying method (substrate processing method) performed using supercritical processing apparatus 300 in the first embodiment will be described. The drying method described below is automatically performed under the control of control unit 4 based on a processing recipe and a control program stored in storage unit 19. Figures 7 to 10 are diagrams showing an outline of the drying method (substrate processing method) in the first embodiment.

[0047] <Delivery process> The wafer W that has been subjected to cleaning processing in the cleaning apparatus 2 is carried out of the cleaning apparatus 2 by the second transfer mechanism 161 in a state in which the recesses of the pattern on the surface of the wafer W are filled with IPA and puddles of IPA are formed on the surface of the wafer W. The second transfer mechanism 161 places the wafer W on the holding plate 316, and then the holding plate 316 on which the wafer W is placed enters the container body 311, and the lid member 315 is hermetically engaged with the container body 311. This completes the loading of the wafer W.

[0048] After the loading step, for example, CO2 is supplied into the processing vessel 301 as the processing fluid R, and the wafer W is dried using CO2.

[0049] <First pressure increase step> First, a first pressurization step is performed. In the first pressurization step, CO2 as the processing fluid R is supplied from the fluid supply tank 52 into the processing vessel 301. Specifically, as shown in FIG. 7, the on-off valve 55e is opened, and the on-off valves 55a, 55b, and 55c are closed. As a result, CO2 at the first temperature is discharged from the fluid supply tank 52 toward the underside of the holding plate 316 from the fluid supply nozzle 341 located directly below the center of the wafer W. By supplying CO2 at the first temperature into the processing vessel 301, the temperature of the wafer W changes to the first temperature.

[0050] CO2 (see arrow F1 in FIG. 3) discharged from the fluid supply nozzle 341 collides with the holding plate 316 covering the underside of the wafer W, then spreads radially along the underside of the holding plate 316 (see arrow F2 in FIG. 3), and then flows into the space above the wafer W through the gap between the edge of the holding plate 316 and the sidewall of the vessel body 311 and the opening 316a in the holding plate 316 (see arrow F3 in FIG. 3). Because the on-off valve 55c is closed, CO2 does not flow out of the processing vessel 301. Therefore, the pressure inside the processing vessel 301 gradually increases.

[0051] In the first pressure increase step, the pressure of CO2 flowing into the processing vessel 301 is lower than the critical pressure (e.g., approximately 7 MPa). Therefore, CO2 flows into the processing vessel 301 in a gaseous state. Thereafter, as the processing vessel 301 is filled with CO2, the pressure inside the processing vessel 301 increases. When the pressure inside the processing vessel 301 exceeds the critical pressure, the CO2 present inside the processing vessel 301 becomes supercritical. When the CO2 inside the processing vessel 301 becomes supercritical, the IPA on the wafer W begins to dissolve into the CO2 in the supercritical state. As a result, the mixture ratio of IPA and CO2 in the mixed fluid consisting of CO2 and IPA changes.

[0052] The pressure inside the processing vessel 301 is detected by the pressure sensor 53, and the first pressure increase step is continued until the pressure inside the processing vessel 301 reaches a first pressure, for example, 8 MPa.

[0053] <Second pressure increase step> When the pressure inside the processing vessel 301 reaches a first pressure, for example, 8 MPa, the first pressurization step ends and the processing transitions to a second pressurization step. In the second pressurization step, the supply path of CO2 into the processing vessel 301 is changed. Specifically, as shown in FIG. 8, the on-off valve 55b is opened, and the on-off valves 55a, 55c, and 55e are closed. As a result, CO2 at the second temperature is discharged from the fluid supply tank 51 toward the underside of the holding plate 316 through the fluid supply nozzle 341 located directly below the center of the wafer W. In other words, the temperature of the CO2 supplied into the processing vessel 301 is quickly increased. By supplying CO2 at the second temperature into the processing vessel 301, the temperature of the wafer W is quickly changed to the second temperature.

[0054] The mixture ratio of IPA and CO2 is not necessarily uniform across the entire surface of the wafer W. To prevent pattern collapse due to unintended vaporization of the mixed fluid, the pressure in the processing vessel 301 is increased to a pressure (here, 15 MPa) that ensures that the CO2 in the processing vessel 301 reaches a supercritical state regardless of the CO2 concentration in the mixed fluid. Here, the "pressure that ensures that the CO2 reaches a supercritical state" refers to a pressure higher than the maximum critical pressure in a graph showing the change in critical pressure versus critical temperature. This pressure (15 MPa) is called the "processing pressure." The first pressure is lower than the processing pressure. While the pressure in the processing vessel 301 increases from the first pressure (8 MPa) to the processing pressure (15 MPa), CO2 at the second temperature continues to be supplied into the processing vessel 301 from the fluid supply nozzle 341 through the on-off valve 55b.

[0055] <Distribution process> After the second pressure increase process, a flow process is performed. In the flow process, CO2 at the second temperature is supplied from the fluid supply tank 51 through the on-off valve 55a and the fluid supply nozzle 341 into the processing vessel 301. Specifically, as shown in FIG. 9, the on-off valves 55a and 55c are opened, and the on-off valves 55b and 55e are closed. This allows CO2 at the second temperature to be supplied from the fluid supply tank 51 into the processing vessel 301 using the fluid supply header 317 (see arrow F4 in FIG. 3). The fluid supply header 317 can supply CO2 at a higher flow rate than the fluid supply nozzle 341. In the flow process, the pressure inside the processing vessel 301 is maintained at a pressure sufficiently higher than the critical pressure, so that drying does not occur even if a large amount of CO2 impinges on the surface of the wafer W or flows near the surface of the wafer W. For this reason, the fluid supply header 317 is used to prioritize shortening the processing time. Furthermore, the temperature of the wafer W is maintained at the second temperature during the flow process.

[0056] In the flow process, CO2 is supplied into the processing vessel 301 via the fluid supply header 317 and exhausted from the processing vessel 301 via the fluid exhaust header 318, so that a laminar flow of CO2 is formed within the processing vessel 301, flowing approximately parallel to the surface of the wafer W (see arrow F6 in Figure 3).

[0057] The flow process promotes the replacement of IPA with CO2 in the recesses of the pattern on the wafer W. As the replacement of IPA with CO2 progresses in the recesses, the critical pressure of the mixed fluid decreases.

[0058] <Discharge process> After the flow process has completed the replacement of IPA with CO2 within the recesses of the pattern, the exhaust process is performed. In the exhaust process, as shown in FIG. 10, the on-off valve 55c is opened, and the on-off valves 55a, 55b, and 55e are closed. When the pressure within the processing vessel 301 becomes lower than the critical pressure of CO2 as a result of the exhaust process, the CO2 in the supercritical state vaporizes and escapes from the recesses of the pattern. This completes the drying process for one wafer W.

[0059] According to the first embodiment, in the first and second pressure increase steps, CO is supplied into the processing vessel 301 from the fluid supply nozzle 341 below the wafer W. This makes it possible to more reliably prevent the pattern from collapsing. This point will be described below.

[0060] If liquid IPA present on the surface of the wafer W is exposed to a flow of gaseous CO2, the IPA will evaporate, which may cause the pattern to collapse. In the first and second pressurization steps, if gaseous CO2 is supplied into the processing vessel 301 from the fluid supply header 317 located to the side of the wafer W, the relatively high-velocity CO2 flow will directly collide with the IPA puddle or pass near the IPA puddle, which tends to cause the IPA to evaporate.

[0061] In contrast, in this embodiment, CO2 discharged from the fluid supply nozzle 341 does not flow directly toward the surface of the wafer W or the space near the surface. Instead, it collides with the center of the lower surface of the holding plate 316, spreads radially along the lower surface of the holding plate 316, and then flows into the space above the wafer W. That is, in this embodiment, there is no flow of CO2 directly from the processing fluid discharge port toward the surface of the wafer W or the space near the surface. This significantly reduces the evaporation of IPA caused by supplying gaseous CO2 into the processing vessel 301. Note that when gaseous CO2 flows into the space above the wafer W, the flow rate of CO2 is significantly slower than when it is discharged from the fluid supply nozzle 341. This further reduces the evaporation of IPA.

[0062] Furthermore, since the temperature of the CO2 supplied into the processing vessel 301 in the first pressure increase step is the first temperature at which the IPA is less likely to evaporate, the temperature of the wafer W is also the first temperature, and the IPA is less likely to evaporate due to the heat of the CO2. Therefore, pattern collapse due to the evaporation of the IPA can be further suppressed.

[0063] Furthermore, the temperature of the CO supplied into the processing vessel 301 in the second pressure increase step and the flow step is higher than the first temperature, and is the second temperature at which IPA is easily dissolved in CO in a supercritical state, so the temperature of the wafer W becomes the second temperature, and IPA is easily dissolved in CO in a supercritical state. Therefore, pattern collapse due to insufficient substitution can be suppressed.

[0064] Furthermore, since CO2 at the first temperature is supplied from the vaporizer 72 and CO2 at the second temperature is supplied from the vaporizer 71, the temperature of CO2 supplied into the processing chamber 301 can be quickly changed, thereby quickly changing the temperature of the wafer W. By quickly changing the temperature of the wafer W, the waiting time until the temperature stabilizes can be shortened, ensuring good productivity. Furthermore, since IPA gradually evaporates even while the temperature of the wafer W is changing, the longer the waiting time, the more IPA can evaporate. According to the first embodiment, by quickly changing the temperature, the waiting time can be shortened and the evaporation of IPA can be suppressed.

[0065] In the first embodiment, CO2 is supplied into the processing vessel 301 only from the fluid supply nozzle 341 throughout the entire period of the first and second pressurization steps, but this is not limiting. For example, in the second pressurization step, CO2 may be supplied into the processing vessel 301 from the fluid supply header 317, or CO2 may be supplied into the processing vessel 301 from both the fluid supply header 317 and the fluid supply nozzle 341. In these cases, pattern collapse can also be prevented.

[0066] However, it is preferable to supply CO2 into the processing vessel 301 only from the fluid supply nozzle 341 throughout the entire period of the first and second pressurization steps, as in the first embodiment. This is because if CO2 is supplied into the processing vessel 301 from the fluid supply header 317, the supplied CO2 directly collides with the paddles made of IPA or a mixture of IPA and CO2 fluid, stirring the paddles and tending to generate particles. This is also because it is possible to more reliably prevent pattern collapse.

[0067] Since the use of the fluid supply header 317 can increase the pressure increase rate compared to the use of the fluid supply nozzle 341, depending on the required particle level, CO2 may be supplied into the processing vessel 301 using the fluid supply header 317 in the second pressure increase step, with an emphasis on throughput.

[0068] (Second embodiment) A description will be given of a substrate processing apparatus according to a second embodiment, which has a configuration suitable for adjusting the temperature of a wafer W. Figure 11 shows a holding plate included in the substrate processing apparatus according to the second embodiment, where (a) is a top view showing the holding plate, and (b) is a cross-sectional view showing a cooling device that cools the holding plate.

[0069] The supercritical processing apparatus 3 provided in the substrate processing apparatus according to the second embodiment is, for example, the supercritical processing apparatus 3 shown in Fig. 4. In the second embodiment, the vaporizer 71 converts the processing fluid supplied from the fluid supply tank 51 into a gas at a third temperature. The third temperature may be equal to the first temperature or the second temperature, or may be higher than the first temperature and lower than the second temperature.

[0070] 11(a), a holding plate 316 provided in the substrate processing apparatus according to the second embodiment has a temperature control element 319. The temperature control element 319 controls the temperature of the holding plate 316. The temperature control element 319 includes, for example, a heater and a Peltier element. The temperature control element 319 is an element that can control at least the temperature of the holding plate 316 to a first temperature and a second temperature.

[0071] 11(b), the lid member 315 and the holding plate 316 can be positioned outside the container body 311 while waiting for the transfer of the wafer W. In the second embodiment, a cooling device 320 is provided to cool the holding plate 316 while the holding plate 316 is waiting outside the container body 311. The cooling device 320 is, for example, a blower that blows dry air 321 onto the holding plate 316. The temperature of the dry air 321 is, for example, room temperature, between 10°C and 30°C.

[0072] The position at which the temperature control element 319 is installed is not limited, but in order to uniformly adjust the temperature of the wafer W, it is preferable that multiple temperature control elements 319 are installed at equal intervals along the circumferential direction of the wafer W on a circumference equidistant from the center of the wafer W.

[0073] Next, in the second embodiment, a drying method (substrate processing method) performed using the supercritical processing apparatus 3 shown in Fig. 4 will be described. The drying method described below is automatically performed under the control of the control unit 4 based on the processing recipe and control program stored in the storage unit 19.

[0074] <Delivery process> As in the first embodiment, a wafer W, whose surface has recesses of a pattern filled with IPA and whose surface has puddles of IPA formed thereon, is placed on a holding plate 316. Thereafter, the holding plate 316 on which the wafer W is placed enters the container body 311, and the lid member 315 hermetically engages with the container body 311. Note that the holding plate 316 is positioned outside the container body 311 until the wafer W is placed thereon, and dry air 321 is blown onto the holding plate 316 by a cooling device 320. As a result, when the wafer W is placed thereon, the temperature of the holding plate 316 is at room temperature, between 10°C and 30°C.

[0075] After the loading step, for example, CO2 is supplied into the processing vessel 301 as the processing fluid R, and the wafer W is dried using CO2.

[0076] <First pressure increase step> First, a first pressurization step is performed. In the first pressurization step, CO2 as the processing fluid R is supplied from the fluid supply tank 51 into the processing vessel 301. That is, the on-off valve 55b is opened, and the on-off valves 55a and 55c are closed. As a result, CO2 at the third temperature is discharged from the fluid supply tank 51 toward the underside of the holding plate 316 from the fluid supply nozzle 341 located directly below the center of the wafer W. The controller 4 also controls the output of the temperature adjustment element 319, which adjusts the temperature of the holding plate 316 to the first temperature. By adjusting the temperature of the holding plate 316 to the first temperature, the temperature of the wafer W changes to the first temperature. The temperature of the wafer W is affected by the heat of the CO2 supplied into the processing vessel 301, but is more significantly affected by the temperature of the holding plate 316 that holds the wafer W.

[0077] As in the first embodiment, the pressure inside the processing vessel 301 gradually increases as CO2 is discharged from the fluid supply nozzle 341. When the pressure inside the processing vessel 301 exceeds the critical pressure, the CO2 inside the processing vessel 301 becomes supercritical, the IPA on the wafer W starts to dissolve in the CO2 in the supercritical state, and the mixture ratio of IPA and CO2 in the mixed fluid consisting of CO2 and IPA changes.

[0078] The pressure inside the processing vessel 301 is detected by the pressure sensor 53, and the first pressure increase step is continued until the pressure inside the processing vessel 301 reaches a first pressure, for example, 8 MPa.

[0079] <Second pressure increase step> When the pressure inside the processing vessel 301 reaches a first pressure, for example, 8 MPa, the first pressurization step ends and the process moves to a second pressurization step. In the second pressurization step, the set temperature of the temperature control element 319 is changed. Specifically, the set temperature of the temperature control element 319 is set to the second temperature, and the controller 4 controls the output of the temperature control element 319, so that the temperature of the holding plate 316 is adjusted to the second temperature by the temperature control element 319. This causes the temperature of the holding plate 316 to rise quickly. As the temperature of the holding plate 316 rises, the temperature of the wafer W quickly changes to the second temperature. In the second pressurization step, the on-off valve 55b remains open, and the on-off valves 55a and 55c remain closed, and CO2 at the third temperature continues to be discharged from the fluid supply tank 51 through the fluid supply nozzle 341 toward the underside of the holding plate 316.

[0080] In the second embodiment, the pressure inside the processing vessel 301 is also increased to a pressure, here 15 MPa, that ensures that CO2 in the processing vessel 301 reaches a supercritical state regardless of the CO2 concentration in the mixed fluid. While the pressure inside the processing vessel 301 increases from the first pressure (8 MPa) to the processing pressure (15 MPa), CO2 at the third temperature continues to be supplied into the processing vessel 301 from the fluid supply nozzle 341 through the on-off valve 55b.

[0081] <Distribution process> After the second pressure increase process, a circulation process is performed. In the circulation process, CO2 at the third temperature is supplied from the fluid supply tank 51 through the on-off valve 55a and the fluid supply nozzle 341 into the processing vessel 301. Specifically, the on-off valves 55a and 55c are opened, and the on-off valve 55b is closed. As a result, CO2 at the third temperature is supplied from the fluid supply tank 51 into the processing vessel 301 using the fluid supply header 317 (see arrow F4 in FIG. 3). During the circulation process, the set temperature of the temperature control element 319 is maintained at the second temperature, and the temperature of the wafer W is maintained at the second temperature.

[0082] <Discharge process> Once the replacement of IPA with CO2 in the recesses of the pattern is completed by the flow process, the exhaust process is performed. In the exhaust process, the on-off valve 55c is opened, and the on-off valves 55a and 55b are closed. In the exhaust process, the temperature control element 319 may be turned off. That is, adjustment of the temperature of the holding plate 316 may be stopped. When the pressure inside the processing vessel 301 becomes lower than the critical pressure of CO2 by the exhaust process, the CO2 in the supercritical state vaporizes and escapes from the recesses of the pattern. This completes the drying process for one wafer W.

[0083] After the discharge step, the holding plate 316 on which the wafer W is placed moves to the outside of the container body 311, and the wafer W is transferred to the second transfer mechanism 161. Thereafter, the cooling device 320 blows dry air 321 onto the holding plate 316. As a result, the temperature of the holding plate 316 becomes approximately room temperature.

[0084] The heaters H1 to H4 can be set to constant temperatures during the drying process for one wafer W. The heaters H1 to H4 may be set to the same temperatures, or some or all of them may be set to different temperatures.

[0085] According to the second embodiment, the temperature of the wafer W is also appropriately adjusted in the first and second pressure increasing steps, and therefore, the same effects as those of the first embodiment can be obtained.

[0086] Furthermore, since the holding plate 316 is cooled to a temperature approximately equal to room temperature while the wafer W is waiting, it is possible to suppress variations in the temperature of the holding plate 316 at the start of the first pressure increase step. This makes it easy to adjust the temperature of the holding plate 316 to the first temperature during the first pressure increase step.

[0087] (Third embodiment) A substrate processing apparatus according to a third embodiment, which has a configuration suitable for adjusting the temperature of a wafer W, will be described. As in the second embodiment, the supercritical processing apparatus 3 provided in the substrate processing apparatus according to the third embodiment is, for example, the supercritical processing apparatus 3 shown in FIG. 4. In the third embodiment, the vaporizer 71 can convert the processing fluid supplied from the fluid supply tank 51 into a gas at a third temperature. In the third embodiment, the set temperatures of the heaters H1 to H4 are changed as appropriate.

[0088] In the third embodiment, a drying method (substrate processing method) performed using the supercritical processing apparatus 3 shown in Fig. 4 will be described. The drying method described below is automatically performed under the control of the control unit 4 based on the processing recipe and control program stored in the storage unit 19.

[0089] <Delivery process> As in the first embodiment, a wafer W, whose surface pattern recesses are filled with IPA and whose surface has puddles of IPA formed thereon, is placed on a holding plate 316, and then the holding plate 316 carrying the wafer W enters the container body 311, and the lid member 315 sealably engages with the container body 311.

[0090] After the loading step, for example, CO2 is supplied into the processing vessel 301 as the processing fluid R, and the wafer W is dried using CO2.

[0091] <First pressure increase step> First, a first pressurization step is performed. CO2 as the processing fluid R is supplied from the fluid supply tank 51 into the processing vessel 301. Specifically, the on-off valve 55b is opened, and the on-off valves 55a and 55c are closed. This causes CO2 from the fluid supply tank 51 to be discharged toward the underside of the holding plate 316 from the fluid supply nozzle 341 located directly below the center of the wafer W. The set temperatures of the heaters H1 to H4 are set to a first combination. The first combination is a combination of set temperatures of the heaters H1 to H4 such that the temperature of CO2 supplied into the processing vessel 301 through the main supply line 50 and the second supply line 64, to which the heaters H1, H2, and H3 are connected, is a first temperature. The controller 4 controls the outputs of the heaters H1 to H4, and CO2 at the first temperature is supplied into the processing vessel 301. By supplying CO2 at the first temperature into the processing vessel 301, the temperature of the wafer W changes to the first temperature.

[0092] As in the first embodiment, the pressure inside the processing vessel 301 gradually increases as CO2 is discharged from the fluid supply nozzle 341. When the pressure inside the processing vessel 301 exceeds the critical pressure, the CO2 inside the processing vessel 301 becomes supercritical, the IPA on the wafer W starts to dissolve in the CO2 in the supercritical state, and the mixture ratio of IPA and CO2 in the mixed fluid consisting of CO2 and IPA changes.

[0093] The pressure inside the processing vessel 301 is detected by the pressure sensor 53, and the first pressure increase step is continued until the pressure inside the processing vessel 301 reaches a first pressure, for example, 8 MPa.

[0094] <Second pressure increase step> When the pressure inside the processing vessel 301 reaches a first pressure, for example, 8 MPa, the first pressurization step ends and the processing transitions to a second pressurization step. In the second pressurization step, the combination of set temperatures of the heaters H1 to H4 is changed to a second combination. The second combination is a combination of set temperatures of the heaters H1 to H4 such that the temperature of CO2 supplied into the processing vessel 301 through the main supply line 50 and the second supply line 64, on which the heaters H1, H2, and H3 are installed, is set to a second temperature. The controller 4 controls the outputs of the heaters H1 to H4, and CO2 at the second temperature is supplied into the processing vessel 301. By supplying CO2 at the second temperature into the processing vessel 301, the temperature of the wafer W changes to the second temperature. In the second pressurization step, the on-off valve 55b remains open, and the on-off valves 55a and 55c remain closed, and CO2 at the third temperature continues to be discharged from the fluid supply tank 51 through the fluid supply nozzle 341 toward the underside of the holding plate 316.

[0095] In the third embodiment, the pressure inside the processing vessel 301 is also increased to a pressure, here 15 MPa, that ensures that CO2 in the processing vessel 301 reaches a supercritical state regardless of the CO2 concentration in the mixed fluid. While the CO2 pressure inside the processing vessel 301 increases from the first pressure (8 MPa) to the processing pressure (15 MPa), CO2 at the second temperature continues to be supplied into the processing vessel 301 from the fluid supply nozzle 341 through the on-off valve 55b.

[0096] <Distribution process> After the second pressure increase process, a flow process is performed. In the flow process, CO2 at a third temperature is supplied from the fluid supply tank 51 through the on-off valve 55a and the fluid supply nozzle 341 into the processing vessel 301. Specifically, the on-off valves 55a and 55c are opened, and the on-off valve 55b is closed. A third combination is a combination of the set temperatures of the heaters H1 to H4. The third combination is a combination of the set temperatures of the heaters H1 to H4 such that the temperature of CO2 supplied into the processing vessel 301 through the main supply line 50 and the first supply line 63, to which the heaters H1 and H4 are connected, is the second temperature. The third combination may be the same as the second combination. Thus, CO2 at the second temperature is supplied into the processing vessel 301 using the fluid supply header 317 (see arrow F4 in FIG. 3). During the flow process, the temperature of the wafer W is maintained at the second temperature.

[0097] <Discharge process> After the flow process has completed the replacement of IPA with CO2 within the recesses of the pattern, the exhaust process is performed. In the exhaust process, the on-off valve 55c is opened, and the on-off valves 55a and 55b are closed. In the exhaust process, the combination of set temperatures of the heaters H1 to H4 may be changed to the first combination. When the pressure within the processing vessel 301 becomes lower than the critical pressure of CO2 as a result of the exhaust process, the CO2 in the supercritical state vaporizes and escapes from the recesses of the pattern. This completes the drying process for one wafer W.

[0098] According to the third embodiment, the temperature of the wafer W is also appropriately adjusted in the first and second pressure increasing steps, and therefore, pattern collapse can be suppressed in the same way as in the first embodiment.

[0099] In the second and third embodiments, supercritical processing apparatus 300 shown in Fig. 6 may be used instead of supercritical processing apparatus 3 shown in Fig. 4. For example, in the first pressure increase step, the output of temperature adjustment element 319 may be controlled, and the outputs of line heaters H1, H2, H3, H5, and H6 may be controlled, while supplying CO2 at a first temperature using vaporizer 72. Furthermore, the second and third embodiments may be combined, and the outputs of line heaters H1, H2, and H3 may be controlled while controlling the output of temperature adjustment element 319.

[0100] (Cleaning method) In any of the embodiments, particles may adhere to the wafer during the drying process. The inventors of the present application have conducted extensive research to prevent particle adhesion to the wafer. As a result, it has been found that cleaning the inside of the processing vessel 301 using a processing fluid in a supercritical state between drying processes is effective. The inventors of the present application have conducted further extensive research to improve cleaning efficiency. As a result, it has been found that repeated pressurization and depressurization during cleaning provides superior cleaning efficiency compared to continuously circulating the processing fluid while maintaining a constant pressure inside the processing vessel 301.

[0101] An experiment on cleaning efficiency conducted by the inventors of the present invention will now be described. Figure 12 is a schematic diagram showing the details of the experiment on cleaning efficiency.

[0102] First, as shown in FIG. 12(a), a wafer W having a puddle of IPA 41 formed on its surface was placed on a holding plate 316 and transferred into the container body 311. Next, as shown in FIG. 12(b), the IPA 41 was evaporated by natural drying in the container body 311. Some of the evaporated IPA 41 adhered to the container body 311 and the exhaust line 65. Next, as shown in FIG. 12(c), the container body 311 and the exhaust line 65 were cleaned using the processing fluid 42. This cleaning was performed using two different methods. FIG. 13 shows pressure changes during cleaning. In the first method, as shown in FIG. 13(a), the processing fluid 42 was continuously circulated while maintaining the pressure inside the processing container 301 at a constant processing pressure. In the second method, as shown in FIG. 13(b), pressurization to the processing pressure and depressurization were repeated. Supercritical CO2 was used as the processing fluid 42. FIG. 13(b) illustrates an example in which pressurization and depressurization were repeated three times. After cleaning, a drying process was carried out on another wafer W having a puddle of IPA 41 formed on its surface, as shown in Fig. 12(d). In this drying process, the temperature of the wafer W was kept constant during the pressure increase process without taking into consideration pattern collapse.

[0103] After the drying process, the particles were counted, and if the number of particles increased from before the drying process was less than a predetermined threshold, it was rated as A, and if it was equal to or greater than the threshold, it was rated as B.

[0104] In the first method, the flow time was set to 0, 100, 400, 500, and 600 seconds, and in the second method, the number of repetitions of pressure increase and depressurization was set to 0, 2, 3, 4, and 5. Five consecutive evaluations were performed for each condition (flow time, number of repetitions). The number of evaluations A and B for each flow time in the first method is shown in Table 1, and the number of evaluations A and B for each number of repetitions in the second method is shown in Table 2.

[0105] [Table 1]

[0106] [Table 2]

[0107] In this experiment, in the first method, by setting the flow time to 500 seconds or more, the increase in the number of particles was able to be kept below the threshold in all drying treatments. In the second method, by repeating pressurization and depressurization three or more times, the increase in the number of particles was able to be kept below the threshold in all drying treatments. In the first method, pressurization is required before flow and depressurization is required after flow. The total processing time when pressurization and depressurization were repeated three times using the second method was approximately 57% of the total processing time obtained by adding the 500-second flow time and the pressurization and depressurization times in the first method. Furthermore, the total CO2 consumption when pressurization and depressurization of the processing fluid (CO2) used in the drying treatment were repeated three times using the second method was approximately 33% of the total CO2 consumption obtained by adding the CO2 consumption during pressurization and depressurization during the 500-second flow time and the CO2 consumption during pressurization and depressurization in the first method.

[0108] Thus, the second method can significantly reduce the total processing time required to suppress an increase in particles and the total consumption of processing fluid compared to the first method, which means that the second method can achieve better cleaning efficiency than the first method.

[0109] In the above embodiments, the fluid supply nozzle 341 is located, for example, directly below the center of the wafer W accommodated in the processing vessel 301, but is not limited to this. The fluid supply nozzle 341 is preferably located below the holding plate 316, that is, at a position where the fluid supply nozzle 341 is not visible when the holding plate 316 on which the wafer W is placed is viewed from directly above. In other words, it is preferable that the CO gas discharged from the fluid supply nozzle 341 collides with the lower surface of the fluid supply nozzle 341 or the back surface (lower surface) of the wafer W.

[0110] However, if the fluid supply nozzle 341 is positioned far away from directly below the center of the wafer W, the flow of CO2 gas within the processing vessel 301 becomes uneven, and the CO2 gas flow may circulate around onto the surface of the wafer W. For this reason, it is desirable to position the fluid supply nozzle 341 close to directly below the center of the wafer W. Furthermore, from the viewpoint of preventing or suppressing the CO2 gas flow from circulating around onto the surface of the wafer W, it is desirable for the fluid supply nozzle 341 to eject CO2 in a vertically upward direction or a substantially vertically upward direction.

[0111] A holding step may be performed between the second pressure increasing step and the flowing step. For example, after the pressure in the processing vessel 301 is increased to the processing pressure (15 MPa), the pressure in the processing vessel 301 may be maintained instead of immediately proceeding to the flowing step.

[0112] In addition, in each of the above embodiments, the process transitions in response to a change in the pressure inside the processing vessel 301. However, the process transition may be configured to occur in response to the elapsed time by previously acquiring the relationship between the elapsed time of the process and the change in the pressure inside the processing vessel 301. In this case, the change in the pressure inside the processing vessel 301 and the process transition are also substantially related to each other.

[0113] The above describes in detail preferred embodiments, but the present invention is not limited to the above-described embodiments, and various modifications and substitutions can be made to the above-described embodiments without departing from the scope of the claims.

[0114] For example, the processing fluid used in the drying process may be a fluid other than CO (e.g., a fluorine-based fluid), and any fluid capable of removing the anti-drying liquid piled on the substrate in a supercritical state may be used as the processing fluid. The anti-drying liquid is not limited to IPA, and any liquid usable as an anti-drying liquid may be used. The substrate to be processed is not limited to the semiconductor wafer W described above, but may also be other substrates such as LCD glass substrates and ceramic substrates. [Explanation of symbols]

[0115] H1~H6 Line heaters W wafer 4. Control Unit 51, 52 Fluid supply tank 71, 72 Carburetor 316 Holding plate 317 Fluid Supply Header 318 Fluid Discharge Header 319 Temperature control element 320 Cooling device 321 Dry Air 341 Fluid supply nozzle

Claims

1. 1. A substrate processing apparatus that dries a substrate having a liquid attached to its surface by using a processing fluid in a supercritical state, a processing vessel that accommodates the substrate; a substrate holder configured to horizontally hold the substrate with the surface facing upward in the processing chamber; a fluid supply unit that supplies a processing fluid into the processing vessel; a fluid discharge unit that discharges a processing fluid from the processing vessel; a control unit that controls at least the operation of the fluid supply unit and the fluid discharge unit; and The control unit controls the operation of the fluid supply unit and the fluid discharge unit, supplying the processing fluid into the processing vessel containing the substrate having the liquid attached to the surface thereof, and increasing the pressure in the processing vessel to a processing pressure higher than the critical pressure of the processing fluid; 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; Run The step of increasing the pressure in the processing vessel to the processing pressure includes: increasing the pressure in the processing vessel to a first pressure that is higher than the critical pressure and lower than the processing pressure; increasing the pressure in the processing vessel from the first pressure to the processing pressure; Including, The fluid supply unit a first path for supplying the processing fluid into the processing vessel at a first temperature; a second path for supplying the processing fluid into the processing vessel at a second temperature higher than the first temperature; a first fluid supply unit that supplies the processing fluid into the processing vessel from below the substrate held by the substrate holder; a second fluid supply unit that supplies the processing fluid into the processing vessel from a side of the substrate held by the substrate holding unit; and the first fluid supply unit includes the first path and a portion of the second path, the second fluid supply unit includes a part of the second path, In the step of increasing the pressure in the processing vessel to the first pressure, the processing fluid is supplied into the processing vessel through the first path, In the step of supplying the processing fluid to the processing vessel and discharging the processing fluid from the processing vessel, the processing fluid is supplied into the processing vessel through a part of the second path, a first pressure supplying step for supplying the processing fluid to the processing vessel and discharging the processing fluid from the processing vessel;

2. A substrate processing apparatus that dries a substrate having a liquid adhering to its surface by using a processing fluid in a supercritical state, comprising: a processing vessel that accommodates the substrate; a substrate holder configured to horizontally hold the substrate with the surface facing upward in the processing chamber; a fluid supply unit that supplies a processing fluid into the processing vessel; a fluid discharge unit that discharges a processing fluid from the processing vessel; a control unit that controls at least the operation of the fluid supply unit and the fluid discharge unit; and The control unit controls the operation of the fluid supply unit and the fluid discharge unit, supplying the processing fluid into the processing vessel containing the substrate having the liquid attached to the surface thereof, and increasing the pressure in the processing vessel to a processing pressure higher than the critical pressure of the processing fluid; 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; Run The step of increasing the pressure in the processing vessel to the processing pressure includes: increasing the pressure in the processing vessel to a first pressure that is higher than the critical pressure and lower than the processing pressure; increasing the pressure in the processing vessel from the first pressure to the processing pressure; Including, The fluid supply unit a first path for supplying the processing fluid into the processing vessel at a first temperature; a second path for supplying the processing fluid into the processing vessel at a second temperature higher than the first temperature; and In the step of increasing the pressure in the processing vessel to the first pressure, the processing fluid is supplied through the first path into the processing vessel from below the substrate held by the substrate holder, In the step of supplying the processing fluid into the processing vessel and discharging the processing fluid from the processing vessel, the processing fluid passes through a part of the second path and is supplied into the processing vessel from a side of the substrate held by the substrate holder, a first pressure supplying step for supplying the processing fluid to the processing vessel and discharging the processing fluid from the processing vessel;

3. 3. The substrate processing apparatus according to claim 1, further comprising a temperature control element provided on the substrate holder and controlled by the control unit.

4. placing the substrate having the liquid attached to its surface in a processing vessel; supplying a processing fluid into the processing vessel containing the substrate having the liquid attached to the surface thereof, and increasing the pressure in the processing vessel to a processing pressure higher than the critical pressure of the processing fluid; 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; and The step of increasing the pressure in the processing vessel to the processing pressure includes: increasing the pressure in the processing vessel to a first pressure that is higher than the critical pressure and lower than the processing pressure; increasing the pressure in the processing vessel from the first pressure to the processing pressure; Including, the step of increasing the pressure in the processing vessel to the first pressure includes the step of supplying the processing fluid into the processing vessel from below the substrate through a first path that supplies the processing fluid into the processing vessel at a first temperature; the step of supplying the processing fluid into the processing vessel and discharging the processing fluid from the processing vessel includes the step of supplying the processing fluid into the processing vessel from a side of the substrate through a part of a second path that supplies the processing fluid into the processing vessel at a second temperature higher than the first temperature; a first pressure supplying step for supplying the processing fluid to the processing vessel and discharging the processing fluid from the processing vessel;

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