Substrate processing device and substrate processing method

Abstract

This invention provides a technique for obtaining an index representing the concentration of a drying liquid in a mixed fluid. The substrate processing apparatus of this invention includes a processing container, a discharge line, and a density detection unit. The processing container is supplied with a supercritical fluid, and the substrate is dried by replacing the drying liquid contained on it with the supercritical fluid. The discharge line discharges a mixed fluid containing the supercritical fluid and the drying liquid from inside the processing container. The density detection unit detects the density of the mixed fluid flowing in the discharge line.

Description

[Technical Field]

[0001] This invention relates to a substrate processing apparatus and a substrate processing method. [Previous Technology]

[0002] The substrate processing apparatus described in Patent Document 1 includes a drying processing unit, a discharge line, an acquisition unit, and a detection unit. The drying processing unit contacts a substrate whose surface is wetted by a liquid with a supercritical fluid, and dries the substrate by displacing the liquid with the supercritical fluid. The discharge line is provided in the drying processing unit and discharges the fluid from the drying processing unit. The acquisition unit is provided in the discharge line and acquires optical information about the fluid discharged from the drying processing unit. The detection unit detects the presence or absence of liquid in the drying processing unit based on the optical information acquired by the acquisition unit. [Prior Art Documents] [Patent Documents]

[0003] [Patent Document 1] International Publication No. 2018 / 173861 [Summary of the Invention]

[0004] [The problem the invention aims to solve]

[0005] One aspect of the present invention provides a technique for obtaining an index representing the concentration of a drying liquid in a mixed fluid. [Means for Solving the Problem]

[0006] A substrate processing apparatus according to one aspect of the present invention includes a processing container, a discharge line, and a density detection unit. The processing container is supplied with a supercritical fluid, and the substrate is dried by replacing a drying liquid contained on it with the supercritical fluid. The discharge line discharges a mixed fluid containing the supercritical fluid and the drying liquid from inside the processing container. The density detection unit detects the density of the mixed fluid flowing in the discharge line. [Effects of the Invention]

[0007] Through one embodiment of the present invention, an index representing the concentration of the drying liquid in the mixed fluid can be obtained.

Implementation Method

[0009] Hereinafter, embodiments of the present invention will be described with reference to the drawings. Furthermore, identical or corresponding components will be indicated by the same symbols in the drawings, and descriptions may be omitted. In this specification, upstream refers to the flow direction of the supercritical fluid upstream, and downstream refers to the flow direction of the supercritical fluid downstream.

[0010] First, referring to Figures 1 and 2, the substrate processing apparatus 1 of this embodiment will be described. The substrate processing apparatus 1 dries the substrate W by replacing the drying liquid contained on the substrate W with a supercritical fluid. A supercritical fluid system is a fluid at a temperature above the critical temperature and a pressure above the critical pressure, and is a fluid in a state where it is impossible to distinguish between liquid and gas. Replacing the drying liquid with a supercritical fluid can suppress the appearance of liquid-gas interfaces in the uneven pattern of the substrate W. As a result, the generation of surface tension can be suppressed, and the collapse of the uneven pattern can be suppressed. The drying liquid is, for example, an organic solvent such as IPA (isopropanol), and the supercritical fluid is, for example, CO2.

[0011] As shown in FIG. 2, the substrate processing apparatus 1 includes a processing container 21, a holding part 22, and a cover 23. The processing container 21 houses a substrate W containing a drying liquid. An opening 24 is formed in the processing container 21 for moving the substrate W in and out. The holding part 22 horizontally holds the substrate W inside the processing container 21 with the liquid film of the drying liquid facing upwards. The cover 23 closes the opening 24 of the processing container 21. The cover 23 is connected to the holding part 22, and the holding part 22 and the cover 23 move together.

[0012] The processing container 21 forms an internal space. Supply ports 26A and 26B and a discharge port 28 are provided on the wall of the processing container 21. Supply ports 26A and 26B are connected to the supply line L1 shown in Figure 1. The supply line L1 supplies supercritical fluid to the processing container 21. The discharge port 28 is connected to the discharge line L2 shown in Figure 1.

[0013] Supply port 26A is connected to the side opposite to the opening 24 in the processing container 21. Supply port 26B is connected to the bottom surface of the processing container 21. Furthermore, discharge port 28 is connected to the lower side of the opening 24. Figures 1 and 2 illustrate two supply ports 26A and 26B and one discharge port 28, but the number and position of supply ports 26A and 26B and discharge port 28 are not particularly limited.

[0014] Furthermore, a supply pipe manifold 31A, 31B and a discharge pipe manifold 33 are provided inside the processing container 21. The supply pipe manifold 31A, 31B and the discharge pipe manifold 33 are all formed with multiple openings.

[0015] The supply pipe header 31A is connected to the supply port 26A and is disposed adjacent to the side opposite to the opening 24 inside the processing container 21. Furthermore, a plurality of openings formed in the supply pipe header 31A face the opening 24.

[0016] The supply pipe header 31B is connected to the supply port 26B and is located in the center of the bottom surface inside the processing container 21. Furthermore, a plurality of openings formed in the supply pipe header 31B face upward.

[0017] The discharge manifold 33 is connected to the discharge port 28 and is located inside the processing container 21 adjacent to the side of the opening 24, and is situated further below the opening 24. Furthermore, a plurality of openings formed in the discharge manifold 33 face the supply manifold 31A.

[0018] Supply manifolds 31A and 31B supply supercritical fluid to the interior of the processing container 21. Discharge manifold 33 discharges the fluid from the interior of the processing container 21 to the outside. The fluid discharged to the outside through discharge manifold 33 includes supercritical fluid, and further includes vapor of a dried liquid dissolved in supercritical fluid.

[0019] As shown in FIG. 1, the substrate processing apparatus 1 has a supply line L1. The supply line L1 is connected to a fluid supply source and a processing container 21. A supercritical fluid is supplied to the supply line L1 by the fluid supply source. A heater H1 is provided in the supply line L1. The heater H1 maintains the supercritical fluid supplied to the processing container 21 above the critical temperature. The heater H1 is provided, for example, covering the entire supply line L1.

[0020] Supply line L1 has a common line L1a, a flow line L1b, and a booster line L1c. The upstream end of the common line L1a is connected to a fluid supply source, and the downstream end of the common line L1a is connected to the flow line L1b and the booster line L1c. The flow line L1b is connected to supply port 26A, and the booster line L1c is connected to supply port 26B.

[0021] An on / off valve 52a and a temperature sensor TS are provided in the flow line L1b. The on / off valve 52a opens and closes the flow path of the fluid. When the on / off valve 52a opens the flow path, the supercritical fluid is supplied to the interior of the processing container 21 through the supply port 26A and the supply pipe header 31A (see Figure 2). On the other hand, when the on / off valve 52a closes the flow path, the supply of supercritical fluid to the processing container 21 is stopped.

[0022] Similarly, an on / off valve 52b and a temperature sensor TS are provided on the booster line L1c. The on / off valve 52b opens and closes the flow path of the fluid. When the on / off valve 52b opens the flow path, the supercritical fluid is supplied to the interior of the processing container 21 through the supply port 26B and the supply manifold 31B (see Figure 2). On the other hand, when the on / off valve 52b closes the flow path, the supply of supercritical fluid to the processing container 21 is stopped.

[0023] Furthermore, in this embodiment, the flow pipeline L1b and the booster pipeline L1c are set separately, but they can also be integrated.

[0024] The substrate processing apparatus 1 has a discharge line L2. The discharge line L2 discharges the fluid inside the processing container 21. A heater H2 is provided in the discharge line L2. The heater H2 suppresses temperature changes in the fluid flowing in the discharge line L2 and thus suppresses fluid liquefaction. The heater H2 is provided, for example, to cover the entire discharge line L2.

[0025] The discharge pipeline L2 includes, for example, an opening and closing pipeline L2a, a first common pipeline L2c, a first intermediate pipeline L2d, a second intermediate pipeline L2e, a third intermediate pipeline L2f, and a second common pipeline L2g.

[0026] The on / off line L2a extends from the discharge port 28 of the processing container 21 to the upstream end of the first common line L2c. An on / off valve 52c, a temperature sensor TS, and a pressure sensor PS are provided on the on / off line L2a. The on / off valve 52c opens and closes the flow path of the fluid. When the on / off valve 52c opens the flow path, the fluid inside the processing container 21 is discharged to the outside of the substrate processing apparatus 1 through the discharge manifold 33 (see Figure 2) and the discharge port 28. On the other hand, when the on / off valve 52c closes the flow path, it stops the discharge of fluid from the processing container 21.

[0027] A pressure reducing valve 53, a flow meter 54, a temperature sensor TS, and a pressure sensor PS are provided on the first common pipeline L2c. The pressure reducing valve 53 lowers the fluid pressure downstream of the pressure reducing valve 53 compared to the fluid pressure upstream of the pressure reducing valve 53. The pressure upstream of the pressure reducing valve 53 is, for example, 14 MPa to 18 MPa, and the pressure downstream of the pressure reducing valve 53 is, for example, 0.1 MPa to 0.5 MPa. The flow meter 54 measures the flow rate of the fluid before pressure reduction, but can also measure the flow rate of the fluid after pressure reduction.

[0028] The first intermediate pipeline L2d, the second intermediate pipeline L2e and the third intermediate pipeline L2f extend from the downstream end of the first common pipeline L2c to the upstream end of the second common pipeline L2g.

[0029] An on / off valve 52e, a check valve 55a, and an orifice 56 are provided on the first intermediate pipeline L2d. The on / off valve 52e opens and closes the flow path of the fluid. When the on / off valve 52e opens the flow path, the fluid inside the processing container 21 is discharged to the outside of the substrate processing apparatus 1 through the on / off valve 52e. On the other hand, when the on / off valve 52e closes the flow path, the discharge of fluid through the first intermediate pipeline L2d is stopped. The check valve 55a prevents backflow of the fluid.

[0030] Similarly, an on / off valve 52f and a check valve 55b are provided on the second intermediate pipeline L2e. The on / off valve 52f opens and closes the flow path of the fluid. When the on / off valve 52f opens the flow path, the fluid inside the processing container 21 is discharged to the outside of the substrate processing apparatus 1 through the on / off valve 52f. On the other hand, when the on / off valve 52f closes the flow path, the discharge of fluid through the second intermediate pipeline L2e is stopped. The check valve 55b prevents the backflow of fluid.

[0031] An on / off valve 52g is provided on the third intermediate pipeline L2f. The on / off valve 52g opens and closes the flow path of the fluid. When the on / off valve 52g opens the flow path, the fluid inside the processing container 21 is discharged to the outside of the substrate processing apparatus 1 through the on / off valve 52g. On the other hand, when the on / off valve 52g closes the flow path, the discharge of fluid through the third intermediate pipeline L2f is stopped.

[0032] Furthermore, in this embodiment, the first intermediate pipeline L2d, the second intermediate pipeline L2e, and the third intermediate pipeline L2f are installed separately, but they can also be integrated. However, in the former case, the fluid can be discharged through a plurality of on / off valves 52e, 52f, and 52g, thereby finely controlling the discharge flow rate of the fluid.

[0033] The substrate processing apparatus 1 includes a control device 90. The control device 90 is, for example, a computer, and includes a CPU (Central Processing Unit) 91 and a storage medium 92 such as memory. The storage medium 92 stores programs that control various processes executed in the substrate processing apparatus 1. The control device 90 controls the operation of the substrate processing apparatus 1 by causing the CPU 91 to execute the programs stored in the storage medium 92.

[0034] Next, referring to FIG3, the substrate processing method of this embodiment will be described. Steps S1 to S5 shown in FIG3 are performed under the control of the control device 90.

[0035] First, in step S1, a conveying device (not shown) moves the substrate W containing the drying liquid into the substrate processing apparatus 1. The holding part 22 picks up the substrate W from the conveying device and holds the substrate W horizontally with the liquid film of the drying liquid facing upwards. The substrate W is housed inside the processing container 21, and the cover 23 closes the opening 24 of the processing container 21.

[0036] Next, in step S2, the supply line L1 supplies supercritical fluid to the interior of the processing container 21 via the supply port 26B and the supply manifold 31B, thereby increasing the internal pressure of the processing container 21. At this time, supercritical fluid is supplied from below the substrate W to prevent it from interfering with the drying liquid contained on the substrate W. The internal pressure of the processing container 21 is increased to a set pressure above the critical pressure. During this period, the discharge line L2 does not discharge fluid from the interior of the processing container 21.

[0037] Next, in step S3, the supply line L1 supplies supercritical fluid to the interior of the processing container 21 via the supply port 26A and the supply header 31A, while the discharge line L2 discharges the fluid inside the processing container 21, allowing the supercritical fluid to circulate above the substrate W. The drying liquid dissolved in the supercritical fluid is discharged to the outside of the processing container 21, and the drying liquid contained on the substrate W is replaced with supercritical fluid to dry the substrate W. At this time, the supply flow rate and the discharge flow rate are equal, and the internal pressure of the processing container 21 is maintained at the set pressure.

[0038] Next, in step S4, the supply line L1 stops supplying supercritical fluid to the interior of the processing container 21, and the discharge line L2 discharges the fluid from the interior of the processing container 21, depressurizing the interior of the processing container 21. The internal pressure of the processing container 21 is reduced to approximately one atmosphere (0.1 MPa). Then, the cover 23 opens the opening 24 of the processing container 21, and the substrate W is removed to the outside of the processing container 21.

[0039] Finally, in step S5, the conveying device (not shown) takes the substrate W from the holding part 22 and moves the taken substrate W to the outside of the substrate processing device 1.

[0040] Next, referring to FIG4, the discharge line L2 according to this embodiment will be described. In step S3 above, the discharge line L2 discharges a mixed fluid containing supercritical fluid and a dried liquid dissolved in the supercritical fluid from the inside of the processing container 21.

[0041] As described above, the discharge pipeline L2 includes an on / off pipeline L2a and a first common pipeline L2c. A pressure sensor PS1, a temperature sensor TS1, and an on / off valve 52c are sequentially provided on the on / off pipeline L2a from upstream to downstream. Furthermore, a density detection unit 54a and a pressure reducing valve 53 are sequentially provided on the first common pipeline L2c from upstream to downstream.

[0042] The density detection unit 54a detects the density of the mixed fluid flowing in the discharge pipeline L2, using it as an indicator of the concentration of the drying liquid in the mixed fluid flowing in the discharge pipeline L2. The higher the concentration of the drying liquid in the mixed fluid, the greater the density of the mixed fluid. Therefore, by detecting the density of the mixed fluid, the concentration of the drying liquid can be determined. That is, an indicator representing the concentration of the drying liquid can be obtained.

[0043] The density detection unit 54a is, for example, located upstream of the pressure reducing valve 53. Almost no pressure loss occurs upstream of the pressure reducing valve 53. Furthermore, almost no temperature change occurs due to pressure loss. Therefore, the density of the mixed fluid can be detected at the same temperature and pressure as inside the processing container 21, thus more accurately measuring the concentration of the drying liquid inside the processing container 21.

[0044] The density detection unit 54a can be any unit capable of detecting the density of a mixed fluid. As the density detection unit 54a, a density meter for high temperature and high pressure applications can be used. For example, a gamma-ray density meter that measures density using gamma rays can be used.

[0045] The density detection unit 54a detects the density D1 of the mixed fluid flowing in the discharge pipeline L2 every unit time. As a result, the time-varying data is shown as solid lines in Figure 8(A). In Figure 8(A), the horizontal axis represents the elapsed time since the start of step S3, and the vertical axis represents the density (kg / m3).

[0046] Next, the time-varying data of the density D1 of the mixed fluid, represented by the solid line in Figure 8(A), will be explained. After the start of step S3, the mixed fluid of the supercritical fluid and the dried liquid dissolved in the supercritical fluid is discharged from the processing container 21 to the discharge line L2. The density D1 increases over time and reaches a peak value.

[0047] The peak value of density D1 and its arrival time depend on the amount of drying liquid pre-filled on the substrate W. The more drying liquid is coated, the more the drying liquid dissolves in the supercritical fluid, and the larger the peak value of density D1. Furthermore, the more drying liquid is coated, the longer it takes for the drying liquid to dissolve in the supercritical fluid, and the longer the arrival time of density D1 until it reaches its peak value.

[0048] After density D1 reaches its peak, as the drying liquid is replaced by supercritical fluid on the top surface of substrate W, the concentration of the drying liquid in the mixed fluid discharged from processing container 21 to discharge line L2 decreases. As a result, density D1 decreases. The decrease in density D1 indicates the degree of replacement of the drying liquid with supercritical fluid, and thus the degree of drying of substrate W. The more the drying of substrate W proceeds, the less residual drying liquid remains, and the more gradual the rate of decrease in density D1.

[0049] Next, the function of the control device 90 will be described with reference to FIG7. The functional blocks shown in FIG7 are schematic and do not necessarily have to be physically configured in the manner shown. All or part of each functional block can be functionally or physically distributed or integrated in any unit. All or any part of each processing function performed in each functional block can be implemented in a program executed by the CPU, or can be implemented as hardware formed by wiring logic. The control device 90 includes, for example, a storage unit 95, a reference density calculation unit 96, a density difference calculation unit 97, a drying end detection unit 98, and a drying abnormality detection unit 99.

[0050] The storage unit 95 stores the time-varying data of density D1 detected by the density detection unit 54a. Furthermore, the storage unit 95 stores the time-varying data of pressure detected by the pressure detection unit 101 and temperature detected by the temperature detection unit 102. The pressure detection unit 101 detects the pressure of the mixed fluid flowing in the discharge line L2. The pressure detection unit 101 includes, for example, the pressure sensor PS1 shown in FIG. 4. On the other hand, the temperature detection unit 102 detects the temperature of the mixed fluid flowing in the discharge line L2. The temperature detection unit 102 includes, for example, the temperature sensor TS1 shown in FIG. 4. The pressure sensor PS1 and the temperature sensor TS1 are, for example, located further downstream of the processing container 21 and further upstream of the on / off valve 52c.

[0051] The reference density calculation unit 96 calculates the density of a supercritical fluid having the same temperature and pressure as the mixed fluid flowing in the discharge pipeline L2, i.e., the reference density D2. The reference density D2 is the density of the pure supercritical fluid. When comparing the density D1 of the mixed fluid with the reference density D2 at the same temperature and pressure, the reference density D2 is smaller. The density difference ΔD between the density D1 of the mixed fluid and the reference density D2 represents the concentration of the drying liquid in the mixed fluid. The higher the concentration of the drying liquid, the larger the density difference ΔD. Furthermore, the calculation of the reference density D2 is performed every unit time, and the time-varying data of the reference density D2, represented by the dashed line in Figure 8(A), is obtained.

[0052] Figure 9 shows an example of the relationship between the density of a pure supercritical fluid and pressure and temperature. As shown in Figure 9, when the pressure is constant, the higher the temperature, the lower the density. Conversely, when the temperature is constant, the higher the pressure, the higher the density. The relationship between the density of a supercritical fluid and pressure and temperature is determined in advance through experiments and stored in the storage medium 92. This relationship can also be stored in the form of an equation. Equations are generally called equations of state. The reference density calculation unit 96 calculates the reference density D2 by referring to the equation stored in the storage medium 92.

[0053] Furthermore, the density detection unit 54a detects the density D1 of the mixed fluid as it passes through the density detection unit 54a. Therefore, the reference density calculation unit 96 calculates a reference density D2 compared with the density D1 based on the pressure and temperature of the mixed fluid as it passes through the density detection unit 54a. For example, the reference density calculation unit 96 calculates the reference density D2 based on the pressure detected by the pressure detection unit 101 and the temperature detected by the temperature detection unit 102.

[0054] The reference density calculation unit 96 can directly use the pressure detected by the pressure sensor PS1 as the pressure of the mixed fluid when it passes through the density detection unit 54a. Alternatively, the reference density calculation unit 96 can also consider the pressure loss that occurs between the pressure sensor PS1 and the density detection unit 54a to calculate the pressure of the mixed fluid when it passes through the density detection unit 54a.

[0055] Similarly, the reference density calculation unit 96 can also use the temperature detected by the temperature sensor TS1 directly as the temperature of the mixed fluid when it passes through the density detection unit 54a. Alternatively, the reference density calculation unit 96 can also calculate the temperature of the mixed fluid when it passes through the density detection unit 54a by taking into account the temperature change that occurs between the temperature sensor TS1 and the density detection unit 54a.

[0056] Almost no pressure loss occurs upstream of the pressure reducing valve 53. On the other hand, heat flows out both upstream and downstream of the pressure reducing valve 53. Upstream of the pressure reducing valve 53, the error in the reference density D2 is mainly due to temperature changes corresponding to the travel distance.

[0057] As shown in FIG4, a pressure sensor PS1 and a temperature sensor TS1 are provided on the downstream side of the processing container 21 and the upstream side of the opening and closing valve 52c. On the other hand, as shown in FIG5, a pressure sensor PS2 and a temperature sensor TS2 may be provided on the downstream side of the opening and closing valve 52c and the upstream side of the density detection unit 54a.

[0058] If the pressure detection unit 101 includes a pressure sensor PS2, the pressure of the mixed fluid can be detected closer to the density detection unit 54a compared to the case where a pressure sensor PS1 is included. Similarly, if the temperature detection unit 102 includes a temperature sensor TS2, the temperature of the mixed fluid can be detected closer to the density detection unit 54a compared to the case where a temperature sensor TS1 is included. As a result, the reference density D2 can be calculated with high accuracy.

[0059] As shown in Figure 6, a temperature sensor TS3 may also be installed downstream of the density detection unit 54a and upstream of the pressure reducing valve 53. The temperature sensor TS3 is installed next to the density detection unit 54a. Alternatively, a pressure sensor PS3 and a temperature sensor TS4 may be installed inside the density detection unit 54a. The temperature sensor TS4 can detect the temperature of the mixed fluid, and the temperature of the mixed fluid can be detected by detecting the temperature of the pipe through which the mixed fluid flows.

[0060] The temperature detection unit 102 may include at least one of the three temperature sensors TS2, TS3, and TS4, or it may include all of them. By using all of the three temperature sensors TS2, TS3, and TS4, the temperature of the mixed fluid when it passes through the density detection unit 54a can be calculated more accurately.

[0061] The density difference calculation unit 97 calculates the density difference ΔD between the density D1 of the mixed fluid detected by the density detection unit 54a and the reference density D2 calculated by the reference density calculation unit 96. The density difference ΔD is calculated every unit of time, and the time-varying data of the density difference ΔD, represented by the solid line in Figure 8(B), is obtained.

[0062] Next, the time-varying data of the density difference ΔD, represented by the solid line in Figure 8(B), will be explained. After the start of step S3, the mixture of supercritical fluid and the dried liquid dissolved in this supercritical fluid is discharged from the processing container 21 to the discharge line L2. The density difference ΔD increases over time and reaches its peak value.

[0063] The peak value of the density difference ΔD and its arrival time depend on the amount of drying liquid pre-coated on the substrate W. The more drying liquid is coated, the more the drying liquid dissolves in the supercritical fluid, and the larger the peak value of the density difference ΔD. Furthermore, the more drying liquid is coated, the longer it takes for the drying liquid to dissolve in the supercritical fluid, and the longer the arrival time of the density difference ΔD until it reaches its peak value.

[0064] After the density difference ΔD reaches its peak, as the drying liquid is replaced with supercritical fluid on the top surface of the substrate W, the concentration of the drying liquid in the mixed fluid discharged from the processing container 21 to the discharge pipeline L2 decreases. As a result, the density difference ΔD decreases. The decrease in density difference ΔD indicates the degree of replacement of the drying liquid with supercritical fluid, and thus the degree of drying of the substrate W. The more the drying of the substrate W progresses, the less residual drying liquid remains, and the more gradual the rate of decrease in density difference ΔD becomes.

[0065] The drying completion detection unit 98 monitors the density D1 or density difference ΔD stored in the storage unit 95, and detects the completion of drying of the substrate W based on its change over time. The completion of drying of the substrate W refers to the completion of replacing the drying liquid on the top surface of the substrate W with supercritical fluid. After detecting that the drying of the substrate W has ended, step S4 is performed.

[0066] For example, the drying end detection unit 98 detects the end of drying of the substrate W by detecting whether the density D1 falls below a critical value. Alternatively, the drying end detection unit 98 detects the end of drying of the substrate W by detecting whether the density difference ΔD falls below a critical value. The detection of the end of drying of the substrate W can be performed after the elapsed time t from step S3 reaches a set time t0. The set time t0 is preset according to the amount of drying liquid pre-filled on the substrate W.

[0067] Next, an example of the processing performed by the drying end detection unit 98 will be described with reference to FIG10. Also, in FIG10, the drying end detection unit 98 determines whether drying is complete based on the density difference ΔD, but it can also determine whether drying is complete based on density D1. In the latter case, simply replace the density difference ΔD with density D1 in FIG10.

[0068] First, in step S101, the drying end detection unit 98 checks whether the elapsed time t has reached the set time t0. If the elapsed time t has not reached the set time t0 (step S101, no), the drying end detection unit 98 performs the above step S101 again after a unit time has elapsed.

[0069] On the other hand, if the set time t0 is reached after time t (step S101, yes), the drying end detection unit 98 calculates the density difference ΔD through the density difference calculation unit 97 (step S102). Then, the drying end detection unit 98 determines whether the density difference ΔD measured in step S102 is below the critical value ΔD0 (step S103).

[0070] If the density difference ΔD exceeds the critical value ΔD0 (step S103, no), the concentration of the drying liquid in the mixed fluid is high, so the drying end detection unit 98 determines that the drying of the substrate W has not been completed (step S105). Then, the flow of step S3 is extended, and the drying end detection unit 98 performs the above step S102 again.

[0071] On the other hand, if the density difference ΔD is below the critical value ΔD0 (step S103, yes), the concentration of the drying liquid in the mixed fluid is low, so the drying end detection unit 98 determines that the drying of the substrate W is complete (step S104). Then, the drying end detection unit 98 ends this process. Then, the depressurization in step S4 begins.

[0072] The drying of substrate W is carried out inside the processing container 21, so the drying process of substrate W cannot be directly observed. Therefore, in order to ensure that the drying of substrate W is completed before the depressurization begins in step S4, the flow time in step S3 has been set to be longer in the past, resulting in wasted time.

[0073] By detecting the drying end of the substrate W by the drying end detection unit 98 in this embodiment, the start time of depressurization in step S4 can be advanced earlier than before, thereby increasing the processing capacity.

[0074] Alternatively, the start of depressurization in step S4 can be prohibited until the drying end detection unit 98 detects that the drying of the substrate W has ended. This start time can be optimized if the start time of depressurization in step S4 is mistakenly set too early.

[0075] The drying anomaly detection unit 99 monitors the density D1 or density difference ΔD stored in the storage unit 95 and detects drying anomalies in the substrate W based on its time-varying data. Drying anomalies in the substrate W may include, for example, an abnormality in the amount of drying liquid pre-filled on the substrate W. If too much drying liquid is applied, particles will be generated. Conversely, if too little drying liquid is applied, the raised pattern will collapse.

[0076] Furthermore, the drying anomaly detection unit 99 can also detect an anomaly in the drying time of the substrate W as a drying anomaly of the substrate W. The drying time is the elapsed time t until the density D1 or density difference ΔD reaches a critical value. If the drying time is too long, it may be due to excessive coating of the drying liquid pre-filled on the substrate W, or a problem in the substrate processing apparatus 1.

[0077] Next, an example of the processing performed by the drying anomaly detection unit 99 will be described with reference to FIG11. Also, in FIG11, the drying anomaly detection unit 99 determines whether the condition is normal or abnormal based on the density difference ΔD, but it can also determine whether the condition is normal or abnormal based on density D1. In the latter case, it is only necessary to replace the density difference ΔD with density D1 in FIG11.

[0078] First, in step S201, the drying anomaly detection unit 99 checks whether the elapsed time t has reached the set time t1. The set time t1 is set to the time when the density difference ΔD reaches its peak value when there is no drying anomaly. If the elapsed time t has not reached the set time t1 (step S201, no), the drying anomaly detection unit 99 performs the above step S201 again after a unit of time has elapsed.

[0079] On the other hand, when the set time t1 is reached after time t (step S201, Yes), the drying anomaly detection unit 99 calculates the density difference ΔD through the density difference calculation unit 97 (step S202). Next, the drying anomaly detection unit 99 determines whether the density difference ΔD measured at the time point t = t1 is above the lower limit ΔD1min and below the upper limit ΔD1max (step S203).

[0080] If the density difference ΔD at time t = t1 is above the lower limit ΔD1min and below the upper limit ΔD1max (step S203, yes), the density difference ΔD is within the allowable range, so the drying anomaly detection unit 99 determines that the coating amount of the drying liquid pre-filled on the substrate W is normal (step S204). Then, the drying anomaly detection unit 99 performs step S206.

[0081] On the other hand, if the density difference ΔD at time t = t1 is lower than the lower limit ΔD1min or higher than the upper limit ΔD1max (step S203, no), the density difference ΔD is outside the allowable range, so the drying anomaly detection unit 99 determines that the coating amount of the drying liquid pre-filled on the substrate W is abnormal (step S205). Then, the drying anomaly detection unit 99 performs step S206.

[0082] In step S206, the drying anomaly detection unit 99 checks whether the elapsed time t has reached the set time t2. The set time t2 is set to the time when the concentration of the drying liquid in the mixed fluid is below a critical value when there is no drying anomaly. The set time t2 can be the same as the set time t0 shown in Figure 10. If the elapsed time t has not reached the set time t2 (step S206, no), the drying anomaly detection unit 99 performs step S206 again after a unit of time has elapsed.

[0083] On the other hand, if the set time t2 is reached after time t (step S206, yes), the drying anomaly detection unit 99 calculates the density difference ΔD through the density difference calculation unit 97 (step S207). Next, the drying anomaly detection unit 99 determines whether the density difference ΔD measured at the time point t = t2 is below the critical value ΔD2 (step S208). The critical value ΔD2 may be the same as the critical value ΔD0 shown in FIG10.

[0084] If the density difference ΔD at time point t = t2 is below the critical value ΔD2 (step S208, yes), the drying anomaly detection unit 99 determines that the length of the drying time is normal (step S209). Then, the drying anomaly detection unit 99 ends the current process.

[0085] On the other hand, if the density difference ΔD at the time point t = t2 is higher than the critical value ΔD2 (step S208, no), the drying anomaly detection unit 99 determines that the length of the drying time is abnormal (step S210). Then, the drying anomaly detection unit 99 ends the current process.

[0086] Also, when the density difference ΔD at the time point t=t2 is higher than the critical value ΔD2 (step S208, no), the flow in step S3 can be extended, as in Figure 10.

[0087] If the drying time is too long, it may be due to excessive application of the drying solution or a problem in the substrate processing apparatus 1. The cause can be determined by checking the results of step S203.

[0088] That is, if the inspection result of step S203 determines that the coating amount of the drying liquid is normal, and the inspection result of step S208 determines that the length of the drying time is abnormal, it can be considered that a problem has occurred in the substrate processing device 1.

[0089] The subsequent processing is terminated when the substrate W that is detected as having a drying abnormality by the drying abnormality detection unit 99 is regarded as a defective product, which can prevent unnecessary processing of defective products.

[0090] The above describes embodiments of the substrate processing apparatus and substrate processing method according to the present invention, but the present invention is not limited to the above embodiments. Various changes, modifications, substitutions, additions, deletions, and combinations can be made within the scope described in the claims. Such modifications and modifications naturally fall within the technical scope of the present invention. [Simplified Explanation of the Diagram]

[0008] Figure 1 is a diagram showing a substrate processing apparatus according to an embodiment. Figure 2 is a perspective view of the processing container of Figure 1. Figure 3 is a flowchart showing a substrate processing method according to an embodiment. Figure 4 is a diagram showing a discharge pipeline according to an embodiment. Figure 5 is a diagram showing a discharge pipeline according to a first modification. Figure 6 is a diagram showing a discharge pipeline according to a second modification. Figure 7 is a diagram showing an example of the components of a control device represented by functional blocks. Figure 8(A) is a diagram showing an example of the change between the density of a mixed fluid and a reference density; Figure 8(B) is a diagram showing an example of the change between the density of a mixed fluid and the density difference between a reference density. Figure 9 is a diagram showing an example of the relationship between the density of a pure supercritical fluid and pressure and temperature. Figure 10 is a flowchart showing an example of the processing performed by the drying end detection unit. Figure 11 is a flowchart showing an example of the processing performed by the drying abnormality detection unit.

Claims

1. A substrate processing apparatus, comprising: a processing container supplied with a supercritical fluid, wherein the substrate is dried by replacing a drying liquid contained on the substrate with the supercritical fluid; a discharge line discharging a mixed fluid comprising the supercritical fluid and the drying liquid from inside the processing container; a density detection unit for detecting the density of the mixed fluid flowing in the discharge line; a reference density calculation unit for calculating the density of the supercritical fluid having the same temperature and pressure as the mixed fluid flowing in the discharge line, i.e., a reference density; and a density difference calculation unit for calculating the density difference between the density of the mixed fluid detected by the density detection unit and the reference density calculated by the reference density calculation unit.

2. The substrate processing apparatus as claimed in claim 1 further comprises: one or more pressure detection units for detecting the pressure of the mixed fluid flowing in the discharge line; and one or more temperature detection units for detecting the temperature of the mixed fluid flowing in the discharge line; and a reference density calculation unit for calculating the reference density based on the pressure detected by the pressure detection unit and the temperature detected by the temperature detection unit.

3. The substrate processing apparatus as described in claim 2, wherein, The temperature detection unit detects the temperature of the mixed fluid inside the density detection unit.

4. The substrate processing apparatus as described in claim 1 further includes: a drying end detection unit that monitors the density difference calculated by the density difference calculation unit and detects the drying end of the substrate by detecting whether the density difference has fallen below a critical value.

5. The substrate processing apparatus as claimed in claim 1 further includes: a drying anomaly detection unit, which detects an anomaly in the amount of the drying liquid pre-filled on the substrate by determining whether the density difference is within an allowable range at a time point when the time elapsed after the mixed fluid is discharged through the discharge pipeline reaches a set time.

6. The substrate processing apparatus as described in any one of claims 1 to 3 further includes: a drying end detection unit, which detects the drying end of the substrate based on time-varying data of the density change of the mixed fluid detected by the density detection unit.

7. The substrate processing apparatus as described in any one of claims 1 to 3 further includes: a drying abnormality detection unit, which detects a drying abnormality of the substrate based on time-varying data of the density change of the mixed fluid detected by the density detection unit.

8. A substrate processing method comprising the following steps: supplying a supercritical fluid into the interior of a processing container and drying the substrate by replacing a drying liquid contained on the substrate with the supercritical fluid; discharging a mixed fluid containing the supercritical fluid and the drying liquid from the interior of the processing container into a discharge pipeline; and detecting the density of the mixed fluid flowing in the discharge pipeline using a density detection unit.

9. The substrate processing method as described in claim 8 further includes the following step: calculating the density of the supercritical fluid having the same temperature and pressure as the mixed fluid flowing in the discharge pipeline, i.e., the reference density, using a reference density calculation unit.

10. The substrate processing method as described in claim 9 further includes the following steps: calculating the density difference between the density of the mixed fluid detected by the density detection unit and the reference density calculated by the reference density calculation unit using a density difference calculation unit.

11. The substrate processing method according to any one of claims 8 to 10 further includes the following step: detecting the end of drying of the substrate based on the time-varying data of the density of the mixed fluid detected by the density detection unit.

12. The substrate processing method according to any one of claims 8 to 10 further includes the following step: detecting a drying abnormality of the substrate based on the time-varying data of the density of the mixed fluid detected by the density detection unit.

Images