JP2014241450A - Supercritical drying method of semiconductor substrate, and substrate processing apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a supercritical drying method of a semiconductor substrate, capable of reducing particles generated on the semiconductor substrate and reducing time required for drying processing.SOLUTION: A supercritical drying method of a semiconductor substrate, comprises the steps of: rinsing, by using pure water, the semiconductor substrate having a fine pattern formed thereon; thereafter replacing the pure water on a surface of the semiconductor substrate with a water-soluble organic solvent; then introducing the semiconductor substrate wet with the water-soluble organic solvent into a chamber; then increasing temperature in the chamber to bring the water-soluble organic solvent to a supercritical state; then decreasing pressure in the chamber while keeping the temperature in the chamber at temperature at which the pure water is not liquefied; changing the water-soluble organic solvent in the supercritical state into gas to discharge the gas out of the chamber; and drying the semiconductor substrate.

Description

  Embodiments described herein relate generally to a supercritical drying method for a semiconductor substrate.

  The manufacturing process of a semiconductor device includes various processes such as a lithography process, an etching process, and an ion implantation process. After completion of each process, before moving to the next process, a cleaning process and a drying process are performed to remove impurities and residues remaining on the wafer surface and clean the wafer surface.

  For example, in the wafer cleaning process after the etching process, a chemical solution for the cleaning process is supplied to the surface of the wafer, and then pure water is supplied to perform a rinsing process. After the rinsing process, a drying process for removing the pure water remaining on the wafer surface and drying the wafer is performed.

  As a method for performing a drying process, for example, a method is known in which pure water on a wafer is replaced with isopropyl alcohol (IPA) to dry the wafer. However, there has been a problem in that the pattern formed on the wafer collapses due to the surface tension of the liquid during the drying process.

In order to solve such a problem, supercritical drying in which the surface tension becomes zero has been proposed.
For example, in a chamber, a wafer whose surface is wet with IPA is immersed in carbon dioxide (supercritical CO ₂ fluid) in a supercritical state, so that IPA on the wafer becomes supercritical CO ₂ fluid. Dissolve. Then, the supercritical CO ₂ fluid in which IPA is dissolved is gradually discharged from the chamber. Thereafter, the pressure in the chamber is decreased / decreased, the supercritical CO ₂ fluid is phase-converted into gas (gas), and then discharged out of the chamber to dry the wafer.

However, when the pressure in the chamber is lowered and carbon dioxide is phase-converted from a supercritical state to a gas (gas), the IPA remaining in the chamber in a state dissolved in the supercritical CO ₂ fluid is There is a problem that the particles are re-adsorbed to form particles (dry marks). Moreover, to fully discharge the IPA dissolved in the supercritical CO ₂ fluid from the chamber, the supercritical CO ₂ fluid with continuously supplied to the chamber continues to discharge the supercritical CO ₂ fluid IPA is dissolved little by little Since this is necessary, there is a problem that the time required for the drying process becomes long.

JP 2003-92240 A

  An object of the present invention is to provide a supercritical drying method for a semiconductor substrate that can reduce particles generated on the semiconductor substrate and reduce the time required for the drying process.

  According to this embodiment, after rinsing the semiconductor substrate on which the fine pattern is formed with water, the surface of the semiconductor substrate is replaced with a water-soluble organic solvent, and the semiconductor substrate is introduced into the chamber while being wet with the water-soluble organic solvent. Then, the temperature in the chamber is raised to bring the water-soluble organic solvent into a supercritical state. Then, the pressure is lowered while maintaining the temperature at which pure water (rinse pure water mixed in the water-soluble organic solvent) does not liquefy in the chamber, and the water-soluble organic solvent in the supercritical state is changed to gas and discharged from the chamber. The semiconductor substrate is dried.

It is a state diagram which shows the relationship between pressure, temperature, and the phase state of a substance. It is a schematic block diagram of the supercritical drying apparatus which concerns on the 1st Embodiment of this invention. It is a flowchart explaining the supercritical drying method which concerns on the 1st embodiment. It is a graph which shows the vapor pressure curve of a water-soluble organic solvent and pure water. It is a flowchart explaining the supercritical drying method which concerns on the 2nd Embodiment of this invention. It is a graph which shows the vapor pressure curve of a water-soluble organic solvent and a water-insoluble organic solvent.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  (First Embodiment) First, supercritical drying will be described. FIG. 1 is a state diagram showing a relationship among pressure, temperature, and phase state of a substance. The functional material of the supercritical fluid used for supercritical drying has three existence states called a gas phase (gas), a liquid phase (liquid), and a solid phase (solid), which are called three states.

  As shown in FIG. 1, the above three phases are a vapor pressure curve (gas phase equilibrium line) indicating the boundary between the gas phase and the liquid phase, a sublimation curve indicating the boundary between the gas phase and the solid phase, and the solid phase and the liquid. It is delimited by a dissolution curve indicating the boundary with the phase. The triple point is where these three phases overlap. When the vapor pressure curve extends from this triple point to the high temperature side, it reaches a critical point where the gas phase and the liquid phase coexist. At this critical point, the gas phase and liquid phase densities are equal, and the gas-liquid coexistence interface disappears.

  In the state of higher temperature and higher pressure than the critical point, there is no distinction between the gas phase and the liquid phase, and the substance becomes a supercritical fluid. A supercritical fluid is a fluid compressed at a high density above the critical temperature. Supercritical fluids are similar to gases in that the diffusive power of solvent molecules is dominant. On the other hand, supercritical fluids are similar to liquids in that the influence of molecular cohesion cannot be ignored, and thus have the property of dissolving various substances.

  Supercritical fluids have a very high infiltration property compared to liquids, and easily penetrate into fine structures.

  Also, the supercritical fluid is dried so that it transitions directly from the supercritical state to the gas phase, so that there is no interface between gas and liquid, that is, the capillary force (surface tension) does not work, It can be dried without destroying the structure. Supercritical drying is to dry a substrate using the supercritical state of such a supercritical fluid.

  Next, a supercritical drying apparatus that performs supercritical drying of a semiconductor substrate will be described with reference to FIG. As shown in FIG. 2, the supercritical drying apparatus 10 includes a chamber 11 in which a heater 12 is built. The chamber 11 is a high-pressure vessel made of SUS or the like. The heater 12 can adjust the temperature in the chamber 11. Although FIG. 2 shows a configuration in which the heater 12 is built in the chamber 11, the heater 12 may be provided on the outer periphery of the chamber 11.

  Further, the chamber 11 is provided with a stage 13 that is a ring-shaped flat plate that holds a semiconductor substrate W to be subjected to supercritical drying.

  A pipe 15 is connected to the chamber 11, and the gas and supercritical fluid in the chamber 11 can be discharged to the outside through the pipe 15. The pipe 15 is provided with a control valve 16 that adjusts the valve opening while monitoring and controlling the internal pressure of the chamber 11. By closing the control valve 16, the inside of the chamber 11 can be sealed.

  Next, a method for cleaning and drying a semiconductor substrate according to the present embodiment will be described with reference to the flowchart shown in FIG.

(Step S101) A semiconductor substrate to be processed is carried into a cleaning chamber (not shown).
And a chemical | medical solution is supplied to the surface of a semiconductor substrate, and a washing process is performed. As the chemical solution, for example, sulfuric acid, hydrofluoric acid, hydrochloric acid, hydrogen peroxide, or the like can be used.

  Here, the cleaning process includes a process for removing the resist from the semiconductor substrate, a process for removing particles and metal impurities, a process for etching and removing a film formed on the substrate, and the like. A fine pattern is formed on the semiconductor substrate. This fine pattern may be formed before the cleaning process or may be formed by this cleaning process.

  (Step S102) After the cleaning process in step S101, a pure water rinse process is performed in which pure water is supplied to the surface of the semiconductor substrate and the chemical solution remaining on the surface of the semiconductor substrate is washed away with pure water.

  (Step S103) After the pure water rinsing process in step S102, the semiconductor substrate whose surface is wet with pure water is immersed in a water-soluble organic solvent, and the liquid on the surface of the semiconductor substrate is replaced with pure water from the water-soluble organic solvent. Replacement processing is performed.

The water-soluble organic solvent used here is, for example, alcohol such as isopropyl alcohol (IPA) or ketone, and has a higher vapor pressure (lower boiling point) than pure water.
Hereinafter, the case where IPA is used as the water-soluble organic solvent will be described.

  Note that the surface of the semiconductor substrate is wetted by the IPA by this liquid replacement treatment, but it is considered that pure water is mixed into the IPA (although a small amount).

  (Step S104) After the liquid replacement process in step S103, the semiconductor substrate is unloaded from the cleaning chamber and introduced into the chamber 11 shown in FIG. 13 is fixed. Then, the control valve 16 is closed to make the inside of the chamber 11 sealed.

  (Step S105) The heater 12 is used to heat the IPA covering the surface of the semiconductor substrate in the sealed chamber 11. As the heated and vaporized IPA increases, the pressure in the chamber 11 which is sealed and has a constant volume increases according to the vapor pressure curve of the IPA shown by the broken line in FIG.

  Here, the actual pressure in the chamber 11 is the sum of the partial pressures of all the gas molecules existing in the chamber 11. In this embodiment, the partial pressure of the gas IPA is described as the pressure in the chamber 11. .

  As shown in FIG. 4, when the pressure in the chamber 11 reaches the critical pressure Pc of the IPA and the IPA is heated to the critical temperature Tc or higher, the IPA (gas IPA and liquid IPA) in the chamber 11 becomes supercritical. It becomes a state. Thereby, the inside of the chamber 11 is filled with supercritical IPA (supercritical IPA), and the surface of the semiconductor substrate is covered with the supercritical IPA.

  Note that until the IPA reaches a supercritical state, the liquid IPA covering the surface of the semiconductor substrate is not completely vaporized, that is, the semiconductor substrate is wetted with the liquid IPA, and the gas IPA and the liquid IPA coexist in the chamber 11. To.

  By substituting the temperature Tc, the pressure Pc, and the volume of the chamber 11 into the gas equation of state (PV = nRT; P is the pressure, V is the volume, n is the number of moles, R is the gas constant, and T is the temperature). When is in a supercritical state, the amount nc (mol) of IPA present in the gaseous state in the chamber 11 is obtained.

  Therefore, it is necessary that liquid IPA of nc (mol) or more exists in the chamber 11 before heating is started in step S105. When the amount of IPA on the semiconductor substrate introduced into the chamber 11 is less than nc (mol), liquid IPA is supplied into the chamber 11 from a chemical supply unit (not shown), and nc (mol) or more is supplied into the chamber 11. Make liquid IPA present.

  With the heating in step S105, the pure water mixed in the liquid IPA and existing on the surface of the semiconductor substrate is also vaporized, and the pure water is purified according to the vapor pressure curve of pure water shown by a solid line in FIG. The partial pressure increases. The pure water exists as a gas (water vapor) in an amount based on the temperature in the chamber 11, the vapor pressure of the pure water at that time, and the volume of the chamber 11, and otherwise exists as a liquid. Since the pure water mixed in the liquid IPA is a small amount, all or most of the pure water is considered to be steam.

  (Step S106) After the IPA enters the supercritical state in Step S105, the heater 12 is further heated to raise the temperature inside the chamber 11 to a predetermined temperature Tw or more (see arrow A1 in FIG. 4). The temperature Tw is the temperature (boiling point) of pure water when the saturated water vapor pressure becomes the critical pressure Pc of IPA. Since the critical pressure Pc of IPA is about 5.4 MPa, the temperature Tw is about 270 ° C. At this time, all the pure water in the chamber 11 exists as water vapor.

  (Step S107) After the heating in step S106, the control valve 16 is opened, the supercritical IPA in the chamber 11 is discharged, and the pressure in the chamber 11 is lowered (see arrow A2 in FIG. 4). At this time, the temperature in the chamber 11 is maintained at a predetermined temperature Tw or higher.

  When the pressure in the chamber 11 becomes equal to or lower than the critical pressure Pc of the IPA, the IPA changes from a supercritical fluid to a gas. Since the temperature in the chamber 11 is equal to or higher than Tw, the pure water remains a gas even after the phase change of the IPA, and reliquefaction can be prevented.

  (Step S <b> 108) After the pressure inside the chamber 11 is reduced to atmospheric pressure, the chamber 11 is cooled and the semiconductor substrate is unloaded from the chamber 11.

  Alternatively, after the pressure inside the chamber 11 is reduced to atmospheric pressure, the semiconductor substrate may be transferred to a cooling chamber (not shown) while being kept at a high temperature and cooled. In this case, since the chamber 11 can always be kept at a certain high temperature, the time required for the drying process of the semiconductor substrate can be shortened.

  As described above, in this embodiment, the IPA covering the surface of the semiconductor substrate is replaced from the liquid IPA to the supercritical IPA, and then the supercritical IPA in the chamber 11 is dried so as to directly change the phase to the gas IPA. Therefore, capillary force (surface tension) does not act on the fine pattern on the semiconductor substrate, and the semiconductor substrate can be dried without destroying the fine pattern.

  Further, when the pressure inside the chamber 11 is reduced to change the phase of the supercritical IPA into the gas IPA, the temperature in the chamber 11 is set to a temperature at which the vapor pressure of pure water is higher than the critical pressure of IPA. The pure water in the chamber 11 is left as a gas (water vapor) to prevent it from becoming a liquid. Therefore, it is possible to prevent the water vapor in the chamber 11 from being liquefied and adsorbed onto the semiconductor substrate, thereby generating particles (dry spots).

In this embodiment, the IPA in the chamber 11 is heated to a supercritical state, and the semiconductor substrate is dried by reducing the pressure in the chamber 11 while maintaining the temperature in the chamber 11 at Tw or higher.
On the other hand, in the conventional supercritical drying method, the supercritical CO ₂ fluid is continuously supplied to the chamber over a long period of time, IPA on the semiconductor substrate and in the chamber is sufficiently dissolved, and gradually discharged from the chamber. After exhausting IPA sufficiently, the pressure in the chamber was lowered / hardened. In the present embodiment, since it is not necessary to perform time-consuming processing such as discharging the supercritical CO ₂ fluid in which IPA is dissolved little by little from the chamber as in the conventional supercritical drying method, the time required for the drying processing is shortened. be able to.

  As described above, according to the supercritical drying method of the semiconductor substrate according to the present embodiment, it is possible to reduce the particles generated on the semiconductor substrate and to shorten the time required for the drying process.

  In the first embodiment, the example in which IPA is used as the water-soluble organic solvent has been described. However, the same treatment can be performed even when a water-soluble organic solvent other than IPA is used.

  In the first embodiment, the temperature in the chamber 11 is raised to the temperature Tw or higher in step S106, and then the pressure in the chamber 11 is lowered in step S107. However, the supercritical IPA changes to the gas IPA. Sometimes, the temperature in the chamber 11 only needs to be equal to or higher than Tw, so the pressure reduction and temperature increase in the chamber 11 may be performed in parallel.

  (Second Embodiment) In the first embodiment, after the pure water rinsing process for the semiconductor substrate (step S102), the liquid replacement process (step for replacing the liquid on the surface of the semiconductor substrate with pure water from a water-soluble organic solvent) (step S102). In step S104, the semiconductor substrate whose surface is wet with a water-soluble organic solvent is introduced into the chamber 11 (step S104). In this embodiment, the liquid on the surface of the semiconductor substrate is replaced with pure water from a water-soluble organic solvent. Then, before introducing the semiconductor substrate into the chamber 11, the liquid on the surface of the semiconductor substrate is replaced with a water-insoluble organic solvent from a water-soluble organic solvent. By using a nonflammable water-insoluble organic solvent, the cost of the chamber 11 can be reduced as compared with the first embodiment using a flammable water-soluble organic solvent.

  A method for cleaning and drying a semiconductor substrate according to the present embodiment will be described with reference to the flowchart shown in FIG. Note that steps S201, S202, and S203 in FIG. 5 are the same as steps S101, S102, and S103 in FIG. 3 in the first embodiment, and thus description thereof is omitted.

  (Step S204) After the liquid replacement process in step S203, the semiconductor substrate whose surface is wetted with a water-soluble organic solvent (IPA) is immersed in a water-insoluble organic solvent, and the liquid on the surface of the semiconductor substrate is made water-insoluble from IPA. A liquid replacement process for replacing with an organic solvent is performed.

Non-water-soluble organic solvents include those having a higher vapor pressure (lower boiling point) than water-soluble organic solvents, such as fluorinated alcohols, hydrofluoroethers (HFE (for example, AE-3000 (CF ₃ CH ₂ OCF ₂ CHF ₂ ))), Chlorofluorocarbon (CFC), hydrofluorocarbon (HFC), perfluorocarbon (PFC), and the like. Hereinafter, the case where HFE is used as the water-insoluble organic solvent will be described.

  By this liquid replacement treatment, the surface of the semiconductor substrate becomes wet with HFE, but it is considered that IPA is mixed into this HFE (although a small amount).

  (Step S205) After the liquid replacement process in step S204, the semiconductor substrate is unloaded from the cleaning chamber and introduced into the chamber 11 shown in FIG. 13 is fixed. Then, the control valve 16 is closed to make the inside of the chamber 11 sealed.

  (Step S206) The heater 12 is used to heat the HFE covering the surface of the semiconductor substrate in the sealed chamber 11. As the heated and vaporized HFE increases, the pressure in the sealed chamber 11 having a constant volume increases according to the vapor pressure curve of the HFE indicated by the broken line in FIG.

  Here, the actual pressure in the chamber 11 is the sum of the partial pressures of all the gas molecules existing in the chamber 11. In the present embodiment, the partial pressure of the gas HFE will be described as the pressure in the chamber 11. .

  As shown in FIG. 6, when HFE is heated to a critical temperature Tc ′ or higher in a state where the pressure in the chamber 11 has reached the critical pressure Pc ′ of HFE, the HFE (gas HFE and liquid HFE) in the chamber 11 is It becomes a supercritical state. As a result, the chamber 11 is filled with supercritical HFE (supercritical HFE), and the surface of the semiconductor substrate is covered with the supercritical HFE.

  It should be noted that until the HFE is in a supercritical state, the liquid HFE covering the surface of the semiconductor substrate is not completely vaporized, that is, the semiconductor substrate is wetted with the liquid HFE, and the gas HFE and the liquid HFE coexist in the chamber 11. To.

  By substituting the temperature Tc ′, the pressure Pc ′, and the volume of the chamber 11 into the gas equation of state (PV = nRT; P is the pressure, V is the volume, n is the number of moles, R is the gas constant, and T is the temperature). When the HFE enters the supercritical state, the amount nc ′ (mol) of HFE existing in the gaseous state in the chamber 11 is obtained.

  Therefore, before heating is started in step S206, it is necessary that liquid HFE of nc ′ (mol) or more exists in the chamber 11. When the amount of HFE on the semiconductor substrate introduced into the chamber 11 is less than nc ′ (mol), liquid HFE is supplied into the chamber 11 from a chemical supply unit (not shown), and nc ′ (mol) is supplied into the chamber 11. The liquid HFE is made to exist.

  With the heating in step S206, the IPA mixed in the liquid HFE and existing on the surface of the semiconductor substrate is also vaporized, and the IPA partial pressure is changed according to the vapor pressure curve of the IPA shown by the solid line in FIG. To rise. The IPA exists as a gas in an amount based on the temperature in the chamber 11, the vapor pressure of the IPA at that time, and the volume of the chamber 11, and otherwise exists as a liquid. Since the IPA mixed in the liquid HFE is a small amount, it is considered that all or most of the IPA is in a gas state.

  (Step S207) After the HFE enters the supercritical state in Step S206, the heater 12 is further heated to raise the temperature inside the chamber 11 to a predetermined temperature Ts or higher (see arrow A3 in FIG. 6). The temperature Ts is the temperature (boiling point) of IPA when the vapor pressure of IPA becomes the critical pressure Pc ′ of HFE. Since the critical pressure Pc ′ of HFE is about 2.4 MPa, the temperature Ts is about 200 ° C. At this time, all of the IPA in the chamber 11 exists as a gas.

  (Step S208) After heating in step S207, the control valve 16 is opened, the supercritical HFE in the chamber 11 is discharged, and the pressure in the chamber 11 is lowered (see arrow A4 in FIG. 6). At this time, the temperature in the chamber 11 is maintained at a predetermined temperature Ts or higher.

  When the pressure in the chamber 11 becomes equal to or lower than the critical pressure Pc ′ of HFE, the HFE changes from a supercritical fluid to a gas. Since the temperature in the chamber 11 is equal to or higher than Ts, the IPA remains a gas even after the phase change of the HFE, and reliquefaction can be prevented.

  (Step S209) The pressure inside the chamber 11 is reduced to atmospheric pressure, the chamber 11 is cooled, and the semiconductor substrate is carried out of the chamber 11.

  Alternatively, after the pressure inside the chamber 11 is reduced to atmospheric pressure, the semiconductor substrate may be transferred to a cooling chamber (not shown) while being kept at a high temperature and cooled. In this case, since the chamber 11 can always be kept at a certain high temperature, the time required for the drying process of the semiconductor substrate can be shortened.

  As described above, in this embodiment, the HFE that covers the surface of the semiconductor substrate is replaced with the supercritical HFE from the liquid HFE, and thereafter, the supercritical HFE in the chamber 11 is dried so as to undergo a phase change directly to the gas HFE. Therefore, capillary force (surface tension) does not act on the fine pattern on the semiconductor substrate, and the semiconductor substrate can be dried without destroying the fine pattern.

  In addition, by lowering the pressure in the chamber 11 and changing the supercritical HFE to the gas HFE, the temperature in the chamber 11 is set to a temperature at which the vapor pressure of IPA is higher than the critical pressure of HFE. The IPA in the chamber 11 is left as a gas to prevent it from becoming a liquid. Therefore, it is possible to prevent the gas IPA in the chamber 11 from being liquefied and adsorbed on the semiconductor substrate to generate particles.

In the present embodiment, the HFE in the chamber 11 is heated to a supercritical state, and the semiconductor substrate is dried by reducing the pressure in the chamber 11 while maintaining the temperature in the chamber 11 at Ts or higher. On the other hand, in the conventional supercritical drying method, the supercritical CO ₂ fluid is continuously supplied to the chamber over a long period of time, IPA on the semiconductor substrate and in the chamber is sufficiently dissolved, and gradually discharged from the chamber. After exhausting IPA sufficiently, the pressure in the chamber was lowered / hardened. In the present embodiment, since it is not necessary to perform time-consuming processing such as discharging the supercritical CO ₂ fluid in which IPA is dissolved little by little from the chamber as in the conventional supercritical drying method, the time required for the drying processing is shortened. be able to.

As described above, according to the supercritical drying method of the semiconductor substrate according to the present embodiment, it is possible to reduce the particles generated on the semiconductor substrate and to shorten the time required for the drying process.
Furthermore, the cost of the chamber 11 used for drying can be reduced.

  In the second embodiment, an example in which IPA is used as the water-soluble organic solvent and HFE is used as the water-insoluble organic solvent has been described. However, a water-soluble organic solvent other than IPA and a water-insoluble organic solvent other than HFE were used. Even in this case, the same processing can be performed.

  In the second embodiment, the temperature in the chamber 11 is raised to the temperature Ts or higher in step S207, and then the pressure in the chamber 11 is lowered in step S208. However, when the supercritical HFE changes to gas HFE, the chamber 11 Since the temperature in the chamber 11 only needs to be equal to or higher than Ts, the pressure reduction and the temperature increase in the chamber 11 may be performed in parallel.

  Note that the present invention is not limited to the above-described embodiment as it is, and can be embodied by modifying the constituent elements without departing from the scope of the invention in the implementation stage. In addition, various inventions can be formed by appropriately combining a plurality of components disclosed in the embodiment. For example, some components may be deleted from all the components shown in the embodiment. Furthermore, constituent elements over different embodiments may be appropriately combined.

10 Supercritical dryer 11 Chamber 12 Heater 13 Stage 15 Piping 16 Control valve

Embodiments described herein relate generally to a supercritical drying method and a substrate processing apparatus for a semiconductor substrate.

This embodiment provides a supercritical drying method and a substrate processing apparatus of a semiconductor substrate which can shorten the time required for the drying process as well as reduce particles generated on the semiconductor substrate.

The method of supercritical drying of a semiconductor substrate according to this embodiment includes a step of cleaning a substrate using a chemical solution, a step of rinsing the substrate using pure water after the cleaning, and a surface of the substrate after the rinsing. Supplying a water-soluble organic solvent, replacing the liquid covering the surface of the substrate from pure water with the water-soluble organic solvent, and after the replacement, supplying a water-insoluble organic solvent to the surface of the substrate; Replacing the liquid covering the surface of the substrate with the water-insoluble organic solvent from the water-soluble organic solvent, introducing the substrate whose surface is wetted with the water-insoluble organic solvent into the chamber, and the chamber Raising the temperature of the water-insoluble organic solvent above the critical temperature of the water-insoluble organic solvent to bring the water-insoluble organic solvent into a supercritical state, and bringing the water-insoluble organic solvent into a supercritical state, The temperature in the chamber is adjusted to the water-soluble organic While maintaining a predetermined temperature higher than the boiling point of the medium reducing the pressure in the chamber, wherein the water-insoluble organic solvent in the supercritical state by varying the gas, and a step of discharging from said chamber.

Claims (8)

Cleaning the semiconductor substrate using a chemical solution;
Rinsing the semiconductor substrate with pure water after the cleaning;
After the rinsing, supplying a water-soluble organic solvent to the surface of the semiconductor substrate, replacing the liquid covering the surface of the semiconductor substrate from pure water with the water-soluble organic solvent;
Introducing the semiconductor substrate whose surface is wetted with the water-soluble organic solvent into the chamber;
Raising the temperature in the chamber above the critical temperature of the water-soluble organic solvent to bring the water-soluble organic solvent into a supercritical state;
After the water-soluble organic solvent is brought into a supercritical state, the pressure in the chamber is lowered while keeping the temperature in the chamber at a predetermined temperature at which pure water does not liquefy, and the water-soluble organic solvent in the supercritical state is changed to a gas. Draining from the chamber;
A method for supercritical drying of a semiconductor substrate comprising:   2. The method of supercritical drying of a semiconductor substrate according to claim 1, wherein the predetermined temperature is a temperature at which a vapor pressure of pure water is higher than a critical pressure of the water-soluble organic solvent.   The method for supercritical drying of a semiconductor substrate according to claim 1 or 2, wherein the water-soluble organic solvent has a higher vapor pressure than pure water.   The method for supercritical drying of a semiconductor substrate according to claim 3, wherein the water-soluble organic solvent contains alcohol or ketone. Cleaning the semiconductor substrate using a chemical solution;
Rinsing the semiconductor substrate with pure water after the cleaning;
After the rinsing, supplying a water-soluble organic solvent to the surface of the semiconductor substrate, replacing the liquid covering the surface of the semiconductor substrate from pure water with the water-soluble organic solvent;
After the replacement, supplying a water-insoluble organic solvent to the surface of the semiconductor substrate and replacing the liquid covering the surface of the semiconductor substrate from the water-soluble organic solvent to the water-insoluble organic solvent;
Introducing the semiconductor substrate whose surface is wetted with the water-insoluble organic solvent into the chamber; raising the temperature in the chamber to a critical temperature of the water-insoluble organic solvent; A step of bringing the solvent into a supercritical state;
After bringing the water-insoluble organic solvent into a supercritical state, the pressure in the chamber is lowered while maintaining the temperature in the chamber at a predetermined temperature at which the water-soluble organic solvent does not liquefy, Changing the solvent to a gas and discharging from the chamber;
A method for supercritical drying of a semiconductor substrate comprising:   6. The semiconductor substrate supercritical drying method according to claim 5, wherein the predetermined temperature is a temperature at which a vapor pressure of the water-soluble organic solvent is higher than a critical pressure of the water-insoluble organic solvent.   The method of supercritical drying of a semiconductor substrate according to claim 5 or 6, wherein the water-insoluble organic solvent has a higher vapor pressure than the water-soluble organic solvent.   The water-soluble organic solvent includes alcohol or ketone, and the water-insoluble organic solvent is any one of fluorinated alcohol, hydrofluoroether (HFE), chlorofluorocarbon (CFC), hydrofluorocarbon (HFC), and perfluorocarbon. The method of supercritical drying of a semiconductor substrate according to claim 7, comprising:

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