Substrate processing apparatus and substrate processing method

Abstract

The invention provides a substrate processing apparatus and a substrate processing method capable of suppressing collapse of a pattern formed on a surface of a substrate. The substrate processing apparatus performs: a step of supplying a processing fluid into a processing container in which a substrate having a liquid adhered to the surface thereof is accommodated, and raising the pressure in the processing container to a processing pressure higher than a critical pressure of the processing fluid; and supplying the processing fluid to the processing container and discharging the processing fluid from the processing container while maintaining the pressure in the processing container at a pressure at which the processing fluid is maintained in a supercritical state. The path of the processing fluid does not overlap between a step of increasing the pressure in the processing container to the first pressure and a step of supplying the processing fluid to the processing container and discharging the processing fluid from the processing container.

Description

[0001] This application is a divisional application of a Chinese patent application with an application date of November 18, 2020, an application number of 202011296423.4, and an invention title of "Substrate Processing Apparatus and Substrate Processing Method". Technical Field

[0002] The present disclosure relates to a substrate processing apparatus and a substrate processing method. Background Art

[0003] In a manufacturing process of a semiconductor device such as forming a stacked structure of an integrated circuit on the surface of a substrate such as a semiconductor wafer (hereinafter referred to as a wafer), liquid processing such as chemical solution cleaning or wet etching is performed. In removing liquids or the like attached to the surface of the wafer during such liquid processing, in recent years, a drying method using a supercritical state processing fluid has been adopted.

[0004] Patent Document 1 discloses a substrate processing apparatus in which a first fluid supply unit is provided below a substrate held by a substrate holding unit, and a second fluid supply unit is provided on the side of the substrate held by the substrate holding unit.

[0005] Prior Art Documents

[0006] Patent Documents

[0007] Patent Document 1: Japanese Unexamined Patent Application Publication No. 2018-74103 Summary of the Invention

[0008] Problems to be Solved by the Invention

[0009] The present disclosure provides a substrate processing apparatus and a substrate processing method capable of suppressing collapse of a pattern formed on the surface of a substrate.

[0010] Solutions for Solving the Problems

[0011] A substrate processing apparatus according to one aspect of the present disclosure is a substrate processing apparatus that dries a substrate having a liquid attached to its surface using a processing fluid in a supercritical state. The substrate processing apparatus includes: a processing container that houses the substrate; a substrate holding unit that horizontally holds the substrate in the processing container with the surface facing upward; a fluid supply unit that supplies the processing fluid into the processing container; a fluid discharge unit that discharges the processing fluid from the processing container; and a control unit that controls at least the operations of the fluid supply unit and the fluid discharge unit and the temperature of the substrate held by the substrate holding unit. The control unit performs the following processes by controlling the operations of the fluid supply unit and the fluid discharge unit: a process of supplying the processing fluid into the processing container housing the substrate having a liquid attached to its surface to raise the pressure in the processing container to a processing pressure higher than the critical pressure of the processing fluid; and a process of, after the pressure in the processing container has risen to the processing pressure, maintaining the pressure in the processing container at a pressure that keeps the processing fluid in a supercritical state, while supplying the processing fluid into the processing container and discharging the processing fluid from the processing container. The process of raising the pressure in the processing container to the processing pressure includes the following processes: a process of raising the pressure in the processing container to a first pressure that is higher than the critical pressure and lower than the processing pressure; and a process of raising the pressure in the processing container from the first pressure to the processing pressure. The control unit controls the temperature of the substrate to a first temperature in the process of raising the pressure in the processing container to the first pressure, and controls the temperature of the substrate to a second temperature higher than the first temperature in the process of raising the pressure in the processing container to the processing pressure.

[0012] Effects of the Invention

[0013] According to the present disclosure, collapse of a pattern formed on the surface of the substrate can be suppressed. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 is a cross-sectional top view showing the overall structure of a substrate processing system.

[0015] Figure 2 is an external perspective view of a processing container of a supercritical processing apparatus.

[0016] Figure 3 is a cross-sectional view of the processing container.

[0017] Figure 4 is a piping system diagram of a supercritical processing apparatus.

[0018] Figure 5The figures (a) to (d) are diagrams for explaining the drying mechanism of IPA.

[0019] Figure 6 It is a piping system diagram of the supercritical processing device included in the substrate processing device of the first embodiment.

[0020] Figure 7 It is a diagram (part 1) showing an outline of the drying method in the first embodiment.

[0021] Figure 8 It is a diagram (part 2) showing an outline of the drying method in the first embodiment.

[0022] Figure 9 It is a diagram (part 3) showing an outline of the drying method in the first embodiment.

[0023] Figure 10 It is a diagram (part 4) showing an outline of the drying method in the first embodiment.

[0024] Figure 11 The figures (a) and (b) are diagrams showing the holding plate included in the substrate processing device of the second embodiment.

[0025] Figure 12 The figures (a) to (d) are schematic diagrams showing the content of an experiment related to cleaning efficiency.

[0026] Figure 13 The figures (a) and (b) are diagrams showing the change in pressure during cleaning. Detailed Embodiments

[0027] Hereinafter, embodiments of the present disclosure will be described with reference to the accompanying drawings. In each drawing, the same or corresponding structures may be denoted by the same or corresponding reference numerals, and description thereof may be omitted.

[0028] [Structure of Substrate Processing System]

[0029] As Figure 1 shown, the substrate processing system 1 includes: a plurality of cleaning devices 2 (two cleaning devices 2 in the Figure 1 example shown), which supply a cleaning liquid to the wafer W to perform a cleaning process; and a plurality of supercritical processing devices 3 (six supercritical processing devices 3 in the Figure 1 example shown), which bring the liquid for preventing drying (IPA: isopropyl alcohol in the present embodiment) attached to the wafer W after the cleaning process into contact with a supercritical state processing fluid (CO2: carbon dioxide in the present embodiment) to remove it.

[0030] In the substrate processing system 1, a FOUP (Front-Opening Unified Pod) 100 is placed on the placement unit 11. The wafers W accommodated in the FOUP 100 are transferred to the cleaning processing unit 14 and the supercritical processing unit 15 through the feeding and discharging unit 12 and the transfer unit 13. In the cleaning processing unit 14 and the supercritical processing unit 15, first, the wafer W is fed into the cleaning device 2 provided in the cleaning processing unit 14 to receive a cleaning process, and then, it is fed into the supercritical processing device 3 provided in the supercritical processing unit 15 to receive a drying process for removing IPA from the wafer W. In Figure 1 , the reference numeral "121" indicates the first transfer mechanism for transferring the wafer W between the FOUP 100 and the transfer unit 13, and the reference numeral "131" indicates a transfer rack, which functions as a buffer unit that temporarily places the wafer W transferred between the feeding and discharging unit 12, the cleaning processing unit 14, and the supercritical processing unit 15.

[0031] A wafer transfer path 162 is connected to the opening of the transfer unit 13, and the cleaning processing unit 14 and the supercritical processing unit 15 are arranged along the wafer transfer path 162. In the cleaning processing unit 14, one cleaning device 2 is arranged on each side of the wafer transfer path 162, and a total of two cleaning devices 2 are provided. On the other hand, in the supercritical processing unit 15, three supercritical processing devices 3 are arranged on each side of the wafer transfer path 162, and a total of six supercritical processing devices 3 are provided. The supercritical processing device 3 functions as a substrate processing device for performing a drying process for removing IPA from the wafer W. A second transfer mechanism 161 is arranged in the wafer transfer path 162 and is configured to be movable within the wafer transfer path 162. The wafer W placed on the transfer rack 131 is received by the second transfer mechanism 161, and the second transfer mechanism 161 feeds the wafer W into the cleaning device 2 and the supercritical processing device 3. In addition, the number and arrangement of the cleaning devices 2 and the 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 according to the number of wafers W processed per unit time and the processing time of each cleaning device 2 and each supercritical processing device 3.

[0032] The cleaning device 2 is configured as, for example, a single-sheet type device that cleans the wafer W one by one by rotational cleaning. In this case, while the wafer W is rotated about the vertical axis in a horizontally held state, a chemical solution for cleaning and a rinse liquid for rinsing the chemical solution can be supplied to the processing surface of the wafer W at appropriate times, thereby performing the cleaning process of the wafer W. The chemical solution and the rinse liquid used in the cleaning device 2 are not particularly limited. For example, an SC1 solution (i.e., a mixture of ammonia, hydrogen peroxide, and water), which is an alkaline chemical solution, can be supplied to the wafer W to remove fine particles and organic contaminants from the wafer W. After that, deionized water (DIW: DeIonized Water), which is used as a rinse liquid, can be supplied to the wafer W to rinse the SC1 solution from the wafer W. Further, a diluted hydrofluoric acid aqueous solution (DHF: DilutedHydroFluoric acid), which is an acidic chemical solution, is supplied to the wafer W to remove the native oxide film, and after that, DIW can also be supplied to the wafer W to rinse the diluted hydrofluoric acid aqueous solution from the wafer W.

[0033] Moreover, after the cleaning device 2 finishes the rinsing process with DIW, while rotating the wafer W, IPA is supplied to the wafer W as a liquid for preventing drying, and the DIW remaining on the processing surface of the wafer W is replaced with IPA. After that, the rotation of the wafer W is slowly stopped. At this time, a sufficient amount of IPA is supplied to the wafer W, and the surface of the wafer W on which a semiconductor pattern is formed is in a state filled with the IPA liquid, and a liquid film of IPA is formed on the surface of the wafer W. The wafer W maintains the state filled with the IPA liquid and is sent out from the cleaning device 2 by the second transfer mechanism 161.

[0034] The IPA thus imparted to the surface of the wafer W serves to prevent the drying of the wafer W. In particular, it prevents so-called pattern collapse from occurring on the wafer W due to the evaporation of IPA during the transfer of the wafer W from the cleaning device 2 to the supercritical processing device 3. Therefore, the cleaning device 2 imparts a sufficient amount of IPA to the wafer W so as to form an IPA film having a relatively large thickness on the surface of the wafer W.

[0035] The wafer W sent out from the cleaning device 2 is sent into the processing container of the supercritical processing device 3 in a state filled with the IPA liquid by the second transfer mechanism 161, and the drying process of IPA is performed in the supercritical processing device 3.

[0036] [Supercritical Processing Device]

[0037] Hereinafter, with reference to Figures 2 to 4 The structures common to each embodiment of the supercritical processing device 3 will be described.

[0038] As Figure 2 and Figure 3As shown, the processing container 301 includes: a container body 311 formed with an opening 312 for loading and unloading the wafer W; a holding plate 316 for horizontally holding the wafer W to be processed; and a lid member 315 for supporting the holding plate 316 and closing the opening 312 when the wafer W is loaded into the container body 311.

[0039] The container body 311 is a container having a processing space inside capable of accommodating a wafer W with a diameter of, for example, 300 mm. A fluid supply header 317 is provided at one end side inside the container body 311, and a fluid discharge header 318 is provided at the other end side. In the illustrated example, the fluid supply header 317 is composed of a block provided with many openings, and the fluid discharge header 318 is composed of a pipe provided with many openings (fluid discharge ports). Preferably, 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.

[0040] The structures of the fluid supply header 317 and the fluid discharge header 318 are not limited to the illustrated example. For example, the fluid discharge header 318 may also be formed of a block, and the fluid supply header 317 may also be formed of a pipe.

[0041] When the holding plate 316 is observed from below, the holding plate 316 covers substantially the entire area of the lower surface of the wafer W. The holding plate 316 has an opening 316a at the end on the lid member 315 side. The processing fluid in the space above the holding plate 316 is guided to the fluid discharge header 318 through the opening 316a (refer to Figure 3 arrow F5).

[0042] The fluid supply header 317 supplies the processing fluid into the container body 311 (processing container 301) substantially in the horizontal direction. Here, the so-called horizontal direction is 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 by the holding plate 316 extends.

[0043] The fluid in the processing container 301 is discharged to the outside of the processing container 301 through the fluid discharge header 318. In the fluid discharged through the fluid discharge header 318, in addition to the processing fluid supplied into the processing container 301 through the fluid supply header 317, it also contains IPA attached to the surface of the wafer W and dissolved in the processing fluid.

[0044] At the bottom of the container body 311, a fluid supply nozzle 341 for supplying a processing fluid into the processing container 301 is provided. In the illustrated example, the fluid supply nozzle 341 is constituted by an opening penetrating the bottom wall of the container body 311. The fluid supply nozzle 341 is located below (e.g., directly below) the central portion of the wafer W, and supplies the processing fluid into the processing container 301 toward the central portion of the wafer W (e.g., vertically upward).

[0045] The processing container 301 further includes a pressing mechanism (not shown). This pressing mechanism presses the lid member 315 toward the container body 311 against the internal pressure caused by the supercritical processing fluid supplied into the processing space, and functions to seal the processing space. In addition, it is preferable to provide heat insulating materials, strip heaters, etc. (not shown) on the top wall and the bottom wall of the container body 311 so that the processing fluid supplied into the processing space can maintain the temperature in the supercritical state.

[0046] As Figure 4 shown, the supercritical processing apparatus 3 has a fluid supply tank 51 as a supply source of the processing fluid. A main supply pipeline 50 is connected to the fluid supply tank 51. The main supply pipeline 50 branches midway into a first supply pipeline 63 connected to a fluid supply header 317 in the processing container 301 and a second supply pipeline 64 connected to the fluid supply nozzle 341.

[0047] Between the fluid supply tank 51 and the fluid supply header 317 (that is, in the main supply pipeline 50 and the first supply pipeline 63 connected thereto), a vaporizer 71 and an on-off valve 55a are provided in order from the upstream side. The vaporizer 71 vaporizes the processing fluid supplied from the fluid supply tank 51 and supplies a gas at a predetermined temperature to the downstream side. The second supply pipeline 64 branches from the main supply pipeline 50 at a position between the vaporizer 71 and the on-off valve 55a. An on-off valve 55b is provided in the second supply pipeline 64.

[0048] A discharge pipeline 65 is connected to a fluid discharge header 318 in the processing container 301. An on-off valve 55c and a pressure regulating valve 55d are provided in order from the upstream side in the discharge pipeline 65. The opening degree of the pressure regulating 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 regulating valve 55d.

[0049] A pipeline heater H1 is provided between the vaporizer 71, the on-off valve 55a, and the on-off valve 55b. Pipeline heaters H2 and H3 are provided between the on-off valve 55b and the fluid supply nozzle 341. The pipeline heater H2 is provided at a position upstream of the pipeline heater H3. A pipeline heater H4 is provided between the on-off valve 55a and the fluid supply header 317. The set temperatures of the pipeline heaters H1 to H4 can be independently controlled by the control unit 4.

[0050] Pressure sensors for detecting the pressure inside the pipeline and temperature sensors for detecting the temperature of the fluid are provided at various locations such as the pipeline through which the fluid of the supercritical processing apparatus 3 flows. Further, a pressure sensor 53 for detecting the pressure inside the processing vessel 301 and a temperature sensor 54 for detecting the temperature of the fluid inside the processing vessel 301 are provided.

[0051] The control unit 4 receives measurement signals from Figure 4 the various sensors (such as the pressure sensor 53 and the temperature sensor 54) shown, and sends control signals (opening and closing signals of the on-off valves 55a to 55c, opening degree signals of the pressure regulating valve 55d, etc.) to the various functional elements. The control unit 4 is, for example, a computer, which includes an arithmetic unit 18 and a storage unit 19. Programs for controlling various processes to be performed in the substrate processing system 1 are stored in the storage unit 19. 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 are programs recorded on a computer-readable storage medium, or can also be programs loaded from the storage medium to the storage unit 19 of the control unit 4. Examples of computer-readable storage media include a hard disk (HD), a floppy disk (FD), a compact disc (CD), a magneto-optical disc (MO), a memory card, and the like.

[0052] [Supercritical drying process]

[0053] Next, with reference to Figure 5 the (a) to (d) of, the drying mechanism of IPA using a supercritical state processing fluid (for example, carbon dioxide (CO2)) will be briefly described.

[0054] After the supercritical state processing fluid R is just introduced into the processing vessel 301, as Figure 5 shown in (a) of, IPA only exists in the concave portions of the pattern P of the wafer W.

[0055] The IPA in the concave portion gradually dissolves in the processing fluid R by contacting the supercritical state processing fluid R, and is gradually replaced with the processing fluid R as Figure 5 shown in (b) of. At this time, in addition to IPA and the processing fluid R, a mixed fluid M in a state where IPA and the processing fluid R are mixed also exists in the concave portion.

[0056] As the replacement of IPA with the processing fluid R progresses within the recess, the IPA present within the recess decreases, and ultimately, as shown in (c) of Figure 5 , only the processing fluid R in the supercritical state exists within the recess.

[0057] After the IPA has been removed from within the recess, the pressure within the processing vessel 301 is reduced to atmospheric pressure, so that as shown in (d) of Figure 5 , the processing fluid R changes from the supercritical state to the gaseous state, and only gas occupies the recess. In this way, the IPA within the recess of the pattern P is removed, and the drying process of the wafer W is completed.

[0058] On the other hand, in the drying process using the processing fluid R of the substrate processing system 1 described above, pattern collapse sometimes occurs. The inventors of the present application repeatedly conducted in-depth research on the cause of pattern collapse, and as a result, it was found that: before the IPA within the recess is replaced by the processing fluid R, due to the heat of the processing fluid R, the temperature of the IPA within the recess rises, and a part of the IPA evaporates. In addition, it was found that: in the case where the drying process is performed by setting the temperature of the processing fluid R to a temperature at which evaporation of the IPA hardly occurs, the IPA is hardly soluble in the processing fluid R in the supercritical state, and the IPA is not sufficiently replaced by the processing fluid R in the supercritical state, and pattern collapse is likely to occur.

[0059] Based on these insights, the inventors of the present application further repeatedly conducted in-depth research, and as a result, it was also found that: by appropriately adjusting the temperature of the wafer W during the period when the pressure within the processing vessel 301 is increased, it is possible to suppress the temperature rise and evaporation of the IPA before replacement, and suppress pattern collapse. It was found that: for example, until the pressure within the processing vessel 301 reaches a preset first pressure, the temperature of the wafer W is set to a first temperature, and after the pressure within the processing vessel 301 has reached the first pressure, the temperature of the wafer W is set to a second temperature higher than the first temperature, thereby being able to suppress pattern collapse.

[0060] The first temperature can be set to a temperature at which it is difficult for the IPA to evaporate before replacement, for example, 80°C to 90°C. The second temperature can be set to a temperature at which the IPA is easily soluble in the processing fluid R in the supercritical state, for example, 100°C to 120°C. The first pressure can be set to a pressure higher than the critical pressure of the processing fluid R. In the case where CO2 is used as the processing fluid R, the critical pressure of CO2 is approximately 7 Mpa, and the first pressure can be set to, for example, around 8 Mpa.

[0061] (First Embodiment)

[0062] A substrate processing apparatus according to a first embodiment having a structure suitable for adjusting the temperature of the wafer W will be described. Figure 6It is a piping system diagram of the supercritical processing device included in the substrate processing device of the first embodiment.

[0063] As Figure 6 shown, the supercritical processing device 300 provided in the substrate processing device of the first embodiment has, in addition to the Figure 4 structure of the supercritical processing device 3 shown, a fluid supply tank 52 as a supply source of the processing fluid. A third supply pipeline 66 is connected to the fluid supply tank 52. The third supply pipeline 66 is connected to the second supply pipeline 64 at a position downstream of the on-off valve 55b. That is, the third supply pipeline 66 is connected to the fluid supply nozzle 341.

[0064] Between the fluid supply tank 52 and the fluid supply nozzle 341 (that is, the third supply pipeline 66), a vaporizer 72 and an on-off valve 55e are provided in order from the upstream side. The vaporizer 72 vaporizes the processing fluid supplied from the fluid supply tank 52 and supplies a gas at a predetermined temperature to the downstream side. The third supply pipeline 66 is connected to the second supply pipeline 64 at a position downstream of the on-off valve 55e.

[0065] A pipeline heater H6 is provided between the vaporizer 72 and the on-off valve 55e. A pipeline heater H5 is provided between the part where the third supply pipeline 66 is connected to the second supply pipeline 64 and the on-off valve 55e. The set temperatures of the pipeline heaters H5 and H6 can be independently controlled by the control unit 4.

[0066] For example, the first path includes a part of the second supply pipeline 64 and the third supply pipeline 66. The vaporizer 72 is an example of the first vaporizer. For example, the second path includes the main supply pipeline 50, the first supply pipeline 63, and the second supply pipeline 64. The vaporizer 71 is an example of the second vaporizer. For example, the first fluid supply unit includes the main supply pipeline 50, the second supply pipeline 64, the third supply pipeline 66, and the fluid supply nozzle 341. For example, the second fluid supply unit includes the main supply pipeline 50, the first supply pipeline 63, and the fluid supply manifold 317. For example, the fluid discharge unit includes the fluid discharge manifold 318 and the discharge pipeline 65.

[0067] In the first embodiment, the vaporizer 71 makes the processing fluid supplied from the fluid supply tank 51 into a gas at the second temperature, for example, 100°C to 120°C, and the vaporizer 72 makes the processing fluid supplied from the fluid supply tank 52 into a gas at the first temperature, for example, 80°C to 90°C. The second temperature is higher than the first temperature.

[0068] Next, in the first embodiment, a drying method (substrate processing method) performed using the supercritical processing apparatus 300 will be described. Further, based on the processing process and control program stored in the storage unit 19, the drying method described below is automatically executed under the control of the control unit 4. Figures 7 to 10 FIG. is a diagram showing an outline of the drying method (substrate processing method) in the first embodiment.

[0069] <Supply Step>

[0070] The wafer W that has undergone the cleaning process in the cleaning apparatus 2 is sent out from the cleaning apparatus 2 by the second transfer mechanism 161 in a state where the recesses of the patterns on its surface are filled with IPA and liquid masses of IPA are formed on its surface. The second transfer mechanism 161 places the wafer W on the holding plate 316. Thereafter, the holding plate 316 on which the wafer W is placed enters the container main body 311, and the lid member 315 is sealingly engaged with the container main body 311. Through the above, the supply of the wafer W is completed.

[0071] After the supply step, a processing fluid R such as CO2 is supplied into the processing container 301, and a drying process of the wafer W using CO2 is performed.

[0072] <First Pressure Increase Step>

[0073] First, the first pressure increase step is performed. In the first pressure increase step, CO2 as the processing fluid R is supplied from the fluid supply tank 52 into the processing container 301. Specifically, as Figure 7 shown, the on-off valve 55e is set to the open state, and the on-off valves 55a, 55b, and 55c are set to the closed state. Thus, CO2 at the first temperature is ejected from the fluid supply nozzle 341 located directly below the central portion of the wafer W toward the lower surface of the holding plate 316. By supplying CO2 at the first temperature into the processing container 301, the temperature of the wafer W changes to the first temperature.

[0074] The CO2 ejected from the fluid supply nozzle 341 (refer to the arrow F1 in Figure 3 ) collides with the holding plate 316 covering the lower surface of the wafer W, and then spreads radially along the lower surface of the holding plate 316 (refer to the arrow F2 in Figure 3 ). Thereafter, it flows into the space on the upper surface side of the wafer W through the gap between the edge of the holding plate 316 and the side wall of the container main body 311 and the opening 316a of the holding plate 316 (refer to the arrow F3 in Figure 3 ). Since the on-off valve 55c is in the closed state, CO2 does not flow out of the processing container 301. Therefore, the pressure inside the processing container 301 gradually rises.

[0075] In the first pressure increasing step, the pressure of the CO2 flowing into the processing container 301 is lower than the critical pressure (for example, about 7 MPa). Therefore, the CO2 flows into the processing container 301 in a gas state. After that, as the filling of CO2 into the processing container 301 proceeds, the pressure in the processing container 301 gradually increases. When the pressure in the processing container 301 exceeds the critical pressure, the CO2 present in the processing container 301 becomes a supercritical state. When the CO2 in the processing container 301 becomes a supercritical state, the IPA on the wafer W begins to dissolve in the supercritical CO2. Thus, the mixing ratio of IPA and CO2 in the mixed fluid composed of CO2 and IPA gradually changes.

[0076] The pressure in the processing container 301 is detected by the pressure sensor 53, and the first pressure increasing step is continued until the pressure in the processing container 301 reaches the first pressure, for example, 8 Mpa.

[0077] <Second pressure increasing step>

[0078] When the pressure in the processing container 301 reaches the first pressure, for example, 8 Mpa, the first pressure increasing step ends and the process proceeds to the second pressure increasing step. In the second pressure increasing step, the supply path of CO2 into the processing container 301 is changed. Specifically, as Figure 8 shown, the on-off valve 55b is set to the open state, and the on-off valves 55a, 55c, and 55e are set to the closed state. Thereby, from the fluid supply tank 51, the CO2 at the second temperature is ejected from the fluid supply nozzle 341 directly below the central portion of the wafer W toward the lower surface of the holding plate 316. That is, the temperature of the CO2 supplied into the processing container 301 rapidly increases. By supplying the CO2 at the second temperature into the processing container 301, the temperature of the wafer W rapidly changes to the second temperature.

[0079] The mixing ratio of IPA and CO2 may not be uniform over the entire surface of the wafer W. To prevent pattern collapse caused by the unexpected vaporization of the mixed fluid, in the second pressure increasing step, the pressure in the processing container 301 is increased to the following pressure, which is a pressure that ensures the CO2 in the processing container 301 becomes a supercritical state regardless of the CO2 concentration in the mixed fluid. Here, it is 15 MPa. Here, the "pressure ensuring supercritical state" means a pressure higher than the maximum value of the critical pressure in a graph showing the change of the critical pressure with respect to the critical temperature. This pressure (15 MPa) is called the "processing pressure". The first pressure is lower than the processing pressure. During the period when the pressure in the processing container 301 rises from the first pressure (8 MPa) to the processing pressure (15 MPa), the CO2 at the second temperature is continuously supplied into the processing container 301 from the fluid supply nozzle 341 via the on-off valve 55b.

[0080] <Circulation step>

[0081] After the second boosting step, a circulation step is performed. In the circulation step, CO2 at the second temperature is supplied from the fluid supply tank 51 to the inside of the processing container 301 via the on-off valve 55a from the fluid supply header 317. Specifically, as Figure 9 shown, the on-off valves 55a and 55c are set to the open state, and the on-off valves 55b and 55e are set to the closed state. Thereby, CO2 at the second temperature is supplied from the fluid supply tank 51 to the inside of the processing container 301 using the fluid supply header 317 (refer to Figure 3 arrow F4). The fluid supply header 317 can supply CO2 at a flow rate larger than that of the fluid supply nozzle 341. In the circulation step, the pressure inside the processing container 301 is maintained at a pressure sufficiently higher than the critical pressure. Therefore, even if a large flow rate of CO2 collides with the surface of the wafer W or flows near the surface of the wafer W, there will be no problem of drying. Therefore, the fluid supply header 317 is used while emphasizing the shortening of the processing time. In addition, during the circulation step, the temperature of the wafer W is maintained at the second temperature.

[0082] In the circulation step, CO2 is supplied into the processing container 301 via the fluid supply header 317, and the CO2 is exhausted from the processing container 301 via the fluid discharge header 318. Therefore, a laminar flow of CO2 that flows substantially parallel to the surface of the wafer W is formed inside the processing container 301 (refer to Figure 3 arrow F6).

[0083] By performing the circulation step, the replacement from IPA to CO2 inside the recesses of the pattern on the wafer W is promoted. As the replacement from IPA to CO2 inside the recesses proceeds, the critical pressure of the mixed fluid gradually decreases.

[0084] <Exhaust step>

[0085] After the replacement from IPA to CO2 inside the recesses of the pattern is completed by the circulation step, an exhaust step is performed. In the exhaust step, as Figure 10 shown, the on-off valve 55c is set to the open state, and the on-off valves 55a, 55b, and 55e are set to the closed state. If the pressure inside the processing container 301 becomes lower than the critical pressure of CO2 by the exhaust step, the supercritical CO2 gasifies and escapes from inside the recesses of the pattern. Thereby, the drying process for one wafer W is completed.

[0086] According to the first embodiment, in the first boosting step and the second boosting step, CO2 is supplied into the processing container 301 from the fluid supply nozzle 341 located below the wafer W. Therefore, it is possible to more reliably prevent the collapse of the pattern. This will be described below.

[0087] If the IPA in a liquid state existing on the surface of the wafer W is exposed to the flow of CO2 in a gaseous state, the IPA evaporates, and in this case, pattern collapse may occur. In the first pressure increasing step and the second pressure increasing step, if CO2 in a gaseous state is supplied into the processing container 301 from the fluid supply header 317 located on the side of the wafer W, the flow of CO2 at a relatively high flow rate directly collides with the liquid mass of IPA or passes near the liquid mass of IPA. Therefore, there is a tendency for the evaporation of IPA to easily occur.

[0088] In contrast, in the present embodiment, the CO2 ejected from the fluid supply nozzle 341 does not flow directly toward the surface of the wafer W or the space near the surface, but after colliding with the central portion of the lower surface of the holding plate 316, it radially expands along the lower surface of the holding plate 316 and then flows into the space on the upper surface side of the wafer W. That is, in the present embodiment, there is no flow of CO2 directly from the processing fluid ejection port toward the surface of the wafer W or the space near the surface. Therefore, the evaporation of IPA due to the supply of CO2 in a gaseous state into the processing container 301 is significantly suppressed. In addition, when the CO2 in a gaseous state flows into the space on the upper surface side of the wafer W, the flow rate of the CO2 becomes significantly smaller than the flow rate of the CO2 ejected from the fluid supply nozzle 341. Thereby, the evaporation of IPA is further suppressed.

[0089] In addition, the temperature of the CO2 supplied into the processing container 301 in the first pressure increasing step is the first temperature at which IPA is difficult to evaporate. Therefore, the temperature of the wafer W becomes the first temperature, and it is also difficult for IPA to evaporate due to the heat of CO2. Thus, the pattern collapse accompanied by the evaporation of IPA can be more suppressed.

[0090] Moreover, the temperature of the CO2 supplied into the processing container 301 in the second pressure increasing step and the circulation step is higher than the first temperature and is the second temperature at which IPA is easily dissolved in supercritical CO2. Therefore, the temperature of the wafer W becomes the second temperature, and IPA is easily dissolved in supercritical CO2. Thus, the pattern collapse accompanied by insufficient replacement can be suppressed.

[0091] In addition, the CO2 at the first temperature is supplied from the vaporizer 72, and the CO2 at the second temperature is supplied from the vaporizer 71. Therefore, the temperature of the CO2 supplied into the processing container 301 can be rapidly changed, and the temperature of the wafer W can be rapidly changed. By rapidly changing the temperature of the wafer W, the standby time until the temperature stabilizes can be shortened, and good productivity can be ensured. In addition, during the period when the temperature of the wafer W is changing, the IPA also gradually evaporates. Therefore, the longer the standby time, the more IPA may evaporate. According to the first embodiment, by rapidly changing the temperature, the standby time can be shortened and the evaporation of IPA can be suppressed.

[0092] In the first embodiment, CO2 was supplied only from the fluid supply nozzle 341 into the processing container 301 throughout the entire period spanning the first pressure boosting step and the second pressure boosting step. However, it is not limited thereto. For example, in the second pressure boosting step, CO2 may also be supplied from the fluid supply header 317 into the processing container 301. Additionally, CO2 may be supplied from both the fluid supply header 317 and the fluid supply nozzle 341 into the processing container 301. In these cases, pattern collapse can also be prevented.

[0093] However, it is preferable that, as in the first embodiment, CO2 is supplied only from the fluid supply nozzle 341 into the processing container 301 throughout the entire period spanning the first pressure boosting step and the second pressure boosting step. The reason is that if CO2 is supplied from the fluid supply header 317 into the processing container 301, the supplied CO2 directly collides with the liquid mass composed of IPA or a mixed fluid of IPA and CO2 and stirs the liquid mass, so there is a tendency to easily generate fine particles. Additionally, the reason is that pattern collapse can be more reliably prevented.

[0094] When comparing the case of using the fluid supply header 317 with the case of using the fluid supply nozzle 341, the pressure boosting speed can be increased. Therefore, it may also be that, depending on the required fine particle level, importance is attached to productivity and CO2 is supplied from the fluid supply header 317 into the processing container 301 in the second pressure boosting step.

[0095] (Second Embodiment)

[0096] A substrate processing apparatus according to a second embodiment having a structure suitable for adjusting the temperature of the wafer W will be described. Figure 11 (a) and (b) of FIG. are diagrams showing a holding plate included in the substrate processing apparatus according to the second embodiment. Figure 11 (a) of FIG. is a top view showing the holding plate, Figure 11 (b) of FIG. is a cross-sectional view of a cooling device for cooling the holding plate.

[0097] The supercritical processing apparatus 3 provided in the substrate processing apparatus according to the second embodiment is, for example Figure 4 the supercritical processing apparatus 3 shown in FIG.. In the second embodiment, the vaporizer 71 turns 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 exceed the first temperature and be less than the second temperature.

[0098] As shown in Figure 11As shown in (a) of FIG. , the holding plate 316 provided in the substrate processing apparatus of the second embodiment has a temperature adjusting element 319. The temperature adjusting element 319 is used to adjust the temperature of the holding plate 316. The temperature adjusting element 319 includes, for example, a heater and a Peltier element. The temperature adjusting element 319 is an element capable of adjusting the temperature of at least the holding plate 316 to a first temperature and a second temperature.

[0099] As shown in Figure 11 As shown in (b) of FIG. , the lid member 315 and the holding plate 316 can be located outside the container body 311 during the standby period of wafer W transfer. In the second embodiment, there is a cooling device 320 for cooling the holding plate 316 during the standby period of the holding plate 316 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 such as 10°C to 30°C.

[0100] The position where the temperature adjusting element 319 is provided is not limited. Preferably, in order to uniformly adjust the temperature of the wafer W, a plurality of temperature adjusting elements 319 are provided at equal intervals along the circumferential direction of the wafer W on a circumference equidistant from the center of the wafer W.

[0101] Next, a drying method (substrate processing method) performed using the supercritical processing apparatus 3 shown in Figure 4 will be described. In addition, based on the processing process and control program stored in the storage unit 19, the drying method described below is automatically executed under the control of the control unit 4.

[0102] <Feed-in process>

[0103] Similar to the first embodiment, the wafer W with IPA filled in the concave portions of the surface pattern and liquid masses of IPA formed on its surface is placed on the holding plate 316. Then, the holding plate 316 with the wafer W thereon enters the container body 311, and the lid member 315 is sealingly engaged with the container body 311. In addition, until the wafer W is placed, the holding plate 316 is disposed outside the container body 311, and dry air 321 is blown onto the holding plate 316 by the cooling device 320. As a result, when the wafer W is placed, the temperature of the holding plate 316 becomes room temperature such as 10°C to 30°C.

[0104] After the feed-in process, for example, CO2 is supplied into the processing container 301 as the processing fluid R, and a drying process of the wafer W using CO2 is performed.

[0105] <First pressure boosting process>

[0106] First, the first pressure boosting process is performed. In the first pressure boosting process, CO2 as the processing fluid R is supplied from the fluid supply tank 51 into the processing container 301. That is, the on-off valve 55b is set to the open state, and the on-off valves 55a and 55c are set to the closed state. Thus, from the fluid supply tank 51, the CO2 at the third temperature is ejected from the fluid supply nozzle 341 directly below the central portion of the wafer W toward the lower surface of the holding plate 316. In addition, the control unit 4 controls the output of the temperature control element 319 so that the temperature of the holding plate 316 is adjusted to the first temperature by the temperature control element 319. By adjusting the temperature of the holding plate 316 to the first temperature, the temperature of the wafer W changes to the first temperature. Although the temperature of the wafer W is also affected by the heat of the CO2 supplied into the processing container 301, the temperature of the holding plate 316 that holds the wafer W has a greater influence on the temperature of the wafer W.

[0107] Similar to the first embodiment, CO2 is ejected from the fluid supply nozzle 341, so that the pressure inside the processing container 301 gradually rises. And when the pressure inside the processing container 301 exceeds the critical pressure, the CO2 inside the processing container 301 becomes in a supercritical state, and the IPA on the wafer W begins to dissolve in the supercritical CO2, and the mixing ratio of IPA and CO2 in the mixed fluid composed of CO2 and IPA gradually changes.

[0108] The pressure inside the processing container 301 is detected by the pressure sensor 53, and the first pressure boosting process is continued until the pressure inside the processing container 301 reaches the first pressure, for example, 8 Mpa.

[0109] <Second pressure boosting process>

[0110] When the pressure inside the processing container 301 reaches the first pressure, for example, 8 Mpa, the first pressure boosting process ends and the second pressure boosting process is started. In the second pressure boosting process, 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 control unit 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. Thus, the temperature of the holding plate 316 rapidly increases. Since the temperature of the holding plate 316 increases, the temperature of the wafer W rapidly changes to the second temperature. In the second pressure boosting process, the on-off valve 55b remains in the open state, the on-off valves 55a and 55c remain in the closed state, and from the fluid supply tank 51, the CO2 at the third temperature continues to be ejected from the fluid supply nozzle 341 toward the lower surface of the holding plate 316.

[0111] Also in the second embodiment, the pressure in the processing container 301 is increased to a pressure that ensures that CO2 in the processing container 301 is in a supercritical state regardless of the CO2 concentration in the mixed fluid. Here, it is 15 MPa. During the period when the pressure in the processing container 301 rises from the first pressure (8 MPa) to the processing pressure (15 MPa), CO2 at the third temperature is continuously supplied into the processing container 301 from the fluid supply nozzle 341 via the on-off valve 55b.

[0112] <Circulation process>

[0113] 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 into the processing container 301 via the on-off valve 55a from the fluid supply manifold 317. Specifically, the on-off valves 55a and 55c are set to the open state, and the on-off valve 55b is set to the closed state. Thereby, CO2 at the third temperature is supplied from the fluid supply tank 51 into the processing container 301 using the fluid supply manifold 317 (refer to the arrow F4 in Figure 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 held at the second temperature.

[0114] <Discharge process>

[0115] After the replacement from IPA to CO2 in the concave portions of the pattern is completed by the circulation process, a discharge process is performed. In the discharge process, the on-off valve 55c is set to the open state, and the on-off valves 55a and 55b are set to the closed state. In the discharge process, the temperature control element 319 can also be disconnected. That is, the adjustment of the temperature of the holding plate 316 can also be stopped. If the pressure in the processing container 301 is lower than the critical pressure of CO2 by the discharge process, the supercritical CO2 gasifies and escapes from the concave portions of the pattern. Thus, the drying process for one wafer W is completed.

[0116] After the discharge process, the holding plate 316 on which the wafer W is placed moves outside the container main 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 around room temperature.

[0117] During the drying process for one wafer W, the set temperatures of the heaters H1 to H4 can be set to a constant value. The set temperatures of the heaters H1 to H4 can be equal to each other, or some or all of them can be different.

[0118] Also according to the second embodiment, since the temperature of the wafer W is appropriately adjusted in the first pressure increase process and the second pressure increase process, the same effects as those of the first embodiment can be obtained.

[0119] In addition, during the standby period of the wafer W, the holding plate 316 is cooled to a temperature around room temperature. Therefore, it is possible to suppress the temperature deviation of the holding plate 316 at the start of the first boosting process. Therefore, at the time of the first boosting process, it is easy to adjust the temperature of the holding plate 316 to the first temperature.

[0120] (Third Embodiment)

[0121] A substrate processing apparatus according to a third embodiment having a structure suitable for adjusting the temperature of the wafer W will be described. Similarly to the second embodiment, the supercritical processing apparatus 3 provided in the substrate processing apparatus according to the third embodiment is, for example Figure 4 the supercritical processing apparatus 3 shown. Also in the third embodiment, the vaporizer 71 can turn the processing fluid supplied from the fluid supply tank 51 into a gas at the third temperature. In the third embodiment, the set temperatures of the heaters H1 to H4 are appropriately changed.

[0122] A drying method (substrate processing method) performed using Figure 4 the supercritical processing apparatus 3 shown in the third embodiment will be described. In addition, based on the processing process and control program stored in the storage unit 19, the drying method described below is automatically executed under the control of the control unit 4.

[0123] <Feed-in Process>

[0124] Similarly to the first embodiment, the wafer W in which the recesses of the pattern on the surface are filled with IPA and liquid masses of IPA are formed on the surface thereof is placed on the holding plate 316. After that, the holding plate 316 on which the wafer W is placed enters the container main body 311, and the lid member 315 is sealingly engaged with the container main body 311.

[0125] After the feed-in process, for example, CO2 is supplied as the processing fluid R into the processing container 301, and drying processing of the wafer W using CO2 is performed.

[0126] <First Boosting Process>

[0127] First, the first pressure boosting process is performed. CO2 as the processing fluid R is supplied from the fluid supply tank 51 into the processing container 301. That is, the on-off valve 55b is set to the open state, and the on-off valves 55a and 55c are set to the closed state. Thus, from the fluid supply tank 51, CO2 is ejected from the fluid supply nozzle 341 directly below the central portion of the wafer W toward the lower surface of the holding plate 316. In addition, the combination of the set temperatures of the heaters H1 to H4 is set to the first combination. The first combination is the combination of the set temperatures of the heaters H1 to H4 that makes the temperature of the CO2 supplied into the processing container 301 via the main supply line 50 provided with the heaters H1, H2, and H3 and the second supply line 64 the first temperature. The control unit 4 controls the outputs of the heaters H1 to H4 and supplies CO2 at the first temperature into the processing container 301. By supplying CO2 at the first temperature into the processing container 301, the temperature of the wafer W changes to the first temperature.

[0128] Similar to the first embodiment, CO2 is ejected from the fluid supply nozzle 341, so that the pressure inside the processing container 301 gradually rises. And when the pressure inside the processing container 301 exceeds the critical pressure, the CO2 inside the processing container 301 becomes in a supercritical state, and the IPA on the wafer W begins to dissolve in the supercritical CO2, and the mixing ratio of IPA and CO2 in the mixed fluid composed of CO2 and IPA gradually changes.

[0129] The pressure inside the processing container 301 is detected by the pressure sensor 53, and the first pressure boosting process is continued until the pressure inside the processing container 301 reaches the first pressure, for example, 8 Mpa.

[0130] <Second pressure boosting process>

[0131] When the pressure inside the processing container 301 reaches the first pressure, for example, 8 Mpa, the first pressure boosting process ends and the second pressure boosting process is started. In the second pressure boosting process, the combination of the set temperatures of the heaters H1 to H4 is changed to the second combination. The second combination is the combination of the set temperatures of the heaters H1 to H4 that makes the temperature of the CO2 supplied into the processing container 301 via the main supply line 50 provided with the heaters H1, H2, and H3 and the second supply line 64 the second temperature. The control unit 4 controls the outputs of the heaters H1 to H4 and supplies CO2 at the second temperature into the processing container 301. By supplying CO2 at the second temperature into the processing container 301, the temperature of the wafer W changes to the second temperature. In the second pressure boosting process, the on-off valve 55b remains in the open state, the on-off valves 55a and 55c remain in the closed state, and from the fluid supply tank 51, CO2 at the third temperature continues to be ejected from the fluid supply nozzle 341 toward the lower surface of the holding plate 316.

[0132] Also in the third embodiment, the pressure in the processing container 301 is increased to a pressure that ensures that the CO2 in the processing container 301 is in a supercritical state regardless of the CO2 concentration in the mixed fluid. Here, it is 15 MPa. During the period when the pressure of CO2 in the processing container 301 rises from the first pressure (8 MPa) to the processing pressure (15 MPa), CO2 at the second temperature is continuously supplied from the fluid supply nozzle 341 to the processing container 301 via the on-off valve 55b.

[0133] <Circulation process>

[0134] After the second pressure increase process, the circulation process is performed. In the circulation process, CO2 at the third temperature is supplied from the fluid supply tank 51 to the processing container 301 via the on-off valve 55a from the fluid supply header 317. Specifically, the on-off valves 55a and 55c are set to the open state, and the on-off valve 55b is set to the closed state. In addition, the combination of the set temperatures of the heaters H1 to H4 is set to the third combination. The third combination is the combination of the set temperatures of the heaters H1 to H4 that makes the temperature of the CO2 supplied to the processing container 301 via the main supply line 50 provided with the heaters H1 and H4 and the first supply line 63 the second temperature. The third combination may also be the same as the second combination. Thus, CO2 at the second temperature is supplied to the processing container 301 using the fluid supply header 317 (refer to Figure 3 arrow F4). During the circulation process, the temperature of the wafer W is maintained at the second temperature.

[0135] <Discharge process>

[0136] After the replacement from IPA to CO2 in the concave portion of the pattern is completed by the circulation process, the discharge process is performed. In the discharge process, the on-off valve 55c is set to the open state, and the on-off valves 55a and 55b are set to the closed state. In the discharge process, the combination of the set temperatures of the heaters H1 to H4 may also be changed to the first combination. If the pressure in the processing container 301 is lower than the critical pressure of CO2 by the discharge process, the supercritical state CO2 gasifies and detaches from the concave portion of the pattern. Thus, the drying process for one wafer W is completed.

[0137] Also according to the third embodiment, since the temperature of the wafer W is appropriately adjusted in the first pressure increase process and the second pressure increase process, pattern collapse can be suppressed in the same manner as in the first embodiment.

[0138] In addition, in the second and third embodiments, it is also possible to use Figure 6 the supercritical processing apparatus 300 shown in Figure 4The supercritical treatment device 3 shown. For example, in the first pressure increasing step, while supplying CO2 at the first temperature using the vaporizer 72, the output of the temperature adjusting element 319 may be controlled, or the outputs of the pipeline heaters H1, H2, H3, H5, and H6 may be controlled. Additionally, it may be possible to combine the second embodiment and the third embodiment to control the output of the temperature adjusting element 319 while controlling the outputs of the pipeline heaters H1, H2, and H3.

[0139] (Cleaning method)

[0140] In any of the embodiments, there is a case where fine particles adhere to the wafer during the drying process. The inventors of the present application repeatedly conducted in-depth research to suppress the adhesion of fine particles to the wafer. As a result, it was found that it is effective to perform cleaning inside the processing container 301 using a processing fluid in a supercritical state between drying processes. The inventors of the present application further conducted in-depth research to improve the cleaning efficiency. As a result, it was found that the cleaning efficiency of repeatedly increasing and decreasing the pressure is excellent compared to continuously flowing the processing fluid while maintaining the pressure inside the processing container 301 at a constant level during cleaning.

[0141] The experiments related to the cleaning efficiency conducted by the inventors of the present application will be described. Figure 12 (a) to (d) are schematic diagrams showing the content of the experiment related to the cleaning efficiency.

[0142] First, as Figure 12 shown in (a), a wafer W having a liquid mass of IPA41 formed on its surface was placed on the holding plate 316, and the wafer W was transported into the container main body 311. Next, as Figure 12 shown in (b), the IPA41 was vaporized by natural drying inside the container main body 311. A part of the vaporized IPA41 adhered to the container main body 311 and the discharge pipeline 65. Next, as Figure 12 shown in (c), the container main body 311 and the discharge pipeline 65 were cleaned using the processing fluid 42. This cleaning was performed in two methods. Figure 13 (a) and (b) are diagrams showing the change in pressure during cleaning. In the first method, as Figure 13 shown in (a), while maintaining the pressure inside the processing container 301 at a constant processing pressure, the processing fluid 42 was continuously flowed. In the second method, as Figure 13 shown in (b), the pressure was repeatedly increased and decreased with respect to the processing pressure. Supercritical CO2 was used as the processing fluid 42. An example of repeatedly increasing and decreasing the pressure 3 times is shown in (b). After cleaning, as Figure 13 ​Figure 12 As shown in FIG. (d), a drying process was performed on another wafer W having a liquid mass of IPA41 formed on its surface. In this drying process, regardless of pattern collapse, the temperature of the wafer W in the pressure boosting step was set to be constant.

[0143] Moreover, after the drying process, the number of fine particles was counted, and the case where the number of fine particles increased after the drying process was less than a preset threshold was defined as Evaluation A, and the case where it was equal to or more than the threshold was defined as Evaluation B.

[0144] In the first method, the circulation time was set to 0 seconds, 100 seconds, 400 seconds, 500 seconds, and 600 seconds. In the second method, the number of times of pressure boosting and pressure reducing was set to 0, 2, 3, 4, and 5. Five evaluations were continuously performed under each condition (circulation time, number of repetitions). The number of times of Evaluation A and the number of times of Evaluation B under each circulation time in the first method are shown in Table 1, and the number of times of Evaluation A and the number of times of Evaluation B under each number of repetitions in the second method are shown in Table 2.

[0145]

Table 1

[0146]

[0147]

Table 2

[0148]

[0149] In this experiment, in the first method, when the circulation time was set to 500 seconds or more, the increase in the number of fine particles could be made less than the threshold in all drying processes. In addition, in the second method, when the pressure boosting and pressure reducing were repeated 3 times or more, the increase in the number of fine particles could be made less than the threshold in all drying processes. In the first method, it was necessary to boost the pressure before circulation and reduce the pressure after circulation. Moreover, in the case where the pressure boosting and pressure reducing were repeated 3 times each in the second method, the total processing time was about 57% of the total processing time obtained by adding the 500 - second circulation time in the first method, the pressure - boosting time, and the pressure - reducing time. In addition, in the case where the pressure boosting and pressure reducing were repeated 3 times each in the second method for the processing fluid (CO2) used in the drying process, the total consumption of CO2 was about 33% of the total consumption of CO2 obtained by adding the consumption of CO2 during the 500 - second circulation time in the first method, the consumption of CO2 during pressure boosting, and the consumption of CO2 during pressure reducing.

[0150] Thus, according to the second method, compared with the first method, the total processing time and the total consumption of the processing fluid required to suppress the increase in fine particles can be significantly reduced. That is, according to the second method, a cleaning efficiency superior to that of the first method can be obtained.

[0151] In addition, in each of the above-described embodiments, the position of the fluid supply nozzle 341 is set, for example, directly below the center of the wafer W accommodated in the processing container 301, but is not limited thereto. Preferably, the position of the fluid supply nozzle 341 is below the holding plate 316, that is, a position where the fluid supply nozzle 341 cannot be seen 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 CO2 gas ejected from the fluid supply nozzle 341 collides with the lower surface of the holding plate 316 or the back surface (lower surface) of the wafer W.

[0152] However, if the position of the fluid supply nozzle 341 is significantly deviated from directly below the center of the wafer W, the flow of the CO2 gas in the processing container 301 becomes uneven, and the flow of the CO2 gas may go around to the surface of the wafer W. Therefore, it is desirable that the fluid supply nozzle 341 be disposed at a position close to directly below the center of the wafer W. In addition, from the viewpoint of preventing or suppressing the flow of the CO2 gas from going around to the surface of the wafer W, it is desirable that the fluid supply nozzle 341 eject the CO2 upward in the vertical direction or substantially upward in the vertical direction.

[0153] A holding step may also be performed between the second pressure boosting step and the circulation step. For example, it may be that after the pressure in the processing container 301 has risen to the processing pressure (15 MPa), instead of immediately proceeding to the circulation step, the pressure in the processing container 301 is maintained.

[0154] In addition, in each of the above-described embodiments, the process is changed according to the change in the pressure in the processing container 301, but it may also be that the relationship between the elapsed time of the process and the change in the pressure in the processing container 301 is obtained in advance, and the process is changed according to the elapsed time. In this case, the change in the pressure in the processing container 301 is also substantially associated with the change of the process.

[0155] As described above in detail, the preferred embodiments and the like have been described, but are not limited to the above-described embodiments and the like, and various modifications and substitutions can be made to the above-described embodiments and the like as long as they do not depart from the scope described in the claims.

[0156] For example, the processing fluid used for the drying process may also be a fluid other than CO2 (for example, a fluorine-based fluid), and any fluid that can remove the liquid for preventing drying filled in the substrate in a supercritical state can be used as the processing fluid. In addition, the liquid for preventing drying is not limited to IPA, and any liquid that can be used as the liquid for preventing drying can be used. The substrate to be processed is not limited to the above-described semiconductor wafer W, and may also be other substrates such as an LCD glass substrate and a ceramic substrate.

Claims

1. A substrate processing apparatus that dries a substrate with a liquid attached to its surface using a processing fluid in a supercritical state, wherein, The substrate processing apparatus includes: a processing container that houses the substrate; a substrate holding unit that horizontally holds the substrate in the processing container with the surface facing upward; a fluid supply unit that supplies a processing fluid into the processing container; a fluid discharge unit that discharges the processing fluid from the processing container; and a control unit that controls at least the operations of the fluid supply unit and the fluid discharge unit, wherein the control unit executes the following processes by controlling the operations of the fluid supply unit and the fluid discharge unit: a process of supplying the processing fluid into the processing container housing the substrate having a liquid adhered to the surface, and raising the pressure in the processing container to a processing pressure higher than the critical pressure of the processing fluid; and a process of, after the pressure in the processing container has risen to the processing pressure, maintaining the pressure in the processing container at a pressure that keeps the processing fluid in a supercritical state, while supplying the processing fluid into the processing container and discharging the processing fluid from the processing container, the process of raising the pressure in the processing container to the processing pressure includes the following processes: a process of raising the pressure in the processing container to a first pressure that is higher than the critical pressure and lower than the processing pressure; and a process of raising the pressure in the processing container from the first pressure to the processing pressure, the fluid supply unit includes: a first path that supplies the processing fluid into the processing container at a first temperature; and a second path that supplies the processing fluid into the processing container at a second temperature higher than the first temperature, in the process of raising the pressure in the processing container to the first pressure, the processing fluid is supplied into the processing container via the first path, in the process of supplying the processing fluid into the processing container and discharging the processing fluid from the processing container, the processing fluid is supplied into the processing container via a part of the second path, between the process of raising the pressure in the processing container to the first pressure and the process of supplying the processing fluid into the processing container and discharging the processing fluid from the processing container, the path of the processing fluid does not repeat.

2. The substrate processing apparatus according to claim 1, wherein, The fluid supply unit includes: a first fluid supply unit that supplies the processing fluid into the processing container from below the substrate held by the substrate holding unit; and a second fluid supply unit that supplies the processing fluid into the processing container from the side of the substrate held by the substrate holding unit, the first fluid supply unit includes a part of the second path and the first path, the second fluid supply unit includes a part of the second path.

3. The substrate processing apparatus according to claim 1 or 2, wherein, The substrate processing apparatus has a temperature adjusting element that is provided on the substrate holding unit and is controlled by the control unit.

4. A substrate processing method, wherein, The substrate processing method includes the following processes: a process of housing a substrate having a liquid adhered to the surface in a processing container; A step of supplying a processing fluid into the processing container containing a substrate having a liquid attached to the surface thereof to increase the pressure in the processing container to a processing pressure higher than the critical pressure of the processing fluid; and After the pressure in the processing container has risen to the processing pressure, a step of supplying the processing fluid into the processing container while maintaining the pressure in the processing container at a pressure that keeps the processing fluid in a supercritical state, and discharging the processing fluid from the processing container, The step of increasing the pressure in the processing container to the processing pressure includes the following steps: A step of increasing the pressure in the processing container to a first pressure higher than the critical pressure and lower than the processing pressure; and A step of increasing the pressure in the processing container from the first pressure to the processing pressure, The step of increasing the pressure in the processing container to the first pressure has a step of supplying the processing fluid into the processing container via a first path, wherein the first path supplies the processing fluid into the processing container at a first temperature, The step of supplying the processing fluid into the processing container and discharging the processing fluid from the processing container has a step of supplying the processing fluid into the processing container via a part of a second path, wherein the second path supplies the processing fluid into the processing container at a second temperature higher than the first temperature, Between the step of increasing the pressure in the processing container to the first pressure and the step of supplying the processing fluid into the processing container and discharging the processing fluid from the processing container, the path of the processing fluid does not repeat.

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