JP5885794B2 - Substrate processing method and apparatus - Google Patents

Description

  Embodiments described herein relate generally to a substrate processing method and apparatus.

  Liquid that removes minute debris and natural oxide film on the surface of a substrate using a liquid such as a cleaning liquid in a manufacturing process of a semiconductor device that forms a laminated structure of an integrated circuit on the surface of a substrate such as a semiconductor wafer (hereinafter referred to as a wafer). Processing steps are provided.

  Along with the high integration of semiconductor devices, a so-called pattern collapse phenomenon has become a problem in such a liquid processing process. Pattern collapse means that when the liquid adhering to the pattern surface on the substrate is dried, the liquid vaporizes unevenly on the adjacent pattern surface on the substrate. This is a phenomenon that occurs and the pattern collapses due to the capillary force caused by the surface tension of the liquid.

  As a technique for drying the liquid adhering to the substrate surface while suppressing the occurrence of such pattern collapse, a method using a supercritical fluid is known. The supercritical fluid has a smaller viscosity than the liquid and has a high ability to extract the liquid. Therefore, by bringing the supercritical fluid into contact with the substrate surface wetted with the liquid, the liquid on the substrate surface can be extracted into the supercritical fluid, and the liquid can be easily replaced with the supercritical fluid. In the supercritical state, since the interface between the gas phase and the liquid phase does not exist, the supercritical fluid covering the substrate surface is instantaneously changed to a gas when the pressure is lowered after the liquid on the substrate surface is replaced with the supercritical fluid. As a result, the liquid on the substrate surface can be removed and dried without being affected by the surface tension.

  As a prior art, a supercritical drying method using a fluorine-containing organic solvent such as fluorinated alcohol, hydrofluoroether (HFE), chlorofluorocarbon (CFC), hydrofluorocarbon (HFC), perfluorocarbon (PFC) is known. . In the related art, after cleaning the substrate surface with a cleaning liquid, pure water and alcohol are sequentially supplied to the substrate surface, a fluorine-containing organic solvent is supplied to the substrate surface to replace the alcohol, and the fluorine-containing organic solvent is applied to the substrate surface. It is transported into the chamber without being dried as it is piled up, and the fluorine-containing organic solvent is heated to change the phase to a supercritical state.

  At this time, it is preferable to use a high boiling point solvent that does not volatilize when transporting the substrate to the chamber. However, since a high boiling point solvent has a high critical temperature, it is generally used in the chamber. When the supplied fluorine-containing organic solvent is phase-changed to a supercritical state in a high-temperature and high-pressure atmosphere, thermal decomposition occurs, fluorine atoms are generated, and the substrate is damaged by fluorine atoms.

JP2012-109301A

  The problem to be solved by the present invention is to provide a substrate processing method and apparatus capable of performing a supercritical drying process without causing problems such as pattern collapse.

  According to the substrate processing method according to the present embodiment, water is supplied to the surface of the substrate. A solvent containing IPA (isopropyl alcohol) is supplied to the surface of the substrate to which water has adhered. A solvent containing HFE (hydrofluoroether) is supplied to the surface of the substrate to which the solvent containing IPA is attached. A first solvent having a solubility in the solvent containing HFE and having a boiling point of 100 ° C. or higher containing PFC (perfluorocarbon) is supplied to the surface of the substrate to which the solvent containing HFE is attached. The substrate to which the first solvent is attached is introduced into the chamber, the first solvent on the surface of the substrate is replaced with the supercritical fluid, and then the pressure in the chamber is lowered to change the supercritical fluid into a gas. The substrate is discharged from the chamber.

The figure which shows an example of the liquid processing unit which concerns on 1st Embodiment. The figure which shows an example of the supercritical drying process unit which concerns on 1st Embodiment. FIG. 5 is a process flow diagram illustrating an example of a substrate processing method according to the first embodiment. The process flow figure showing an example of the substrate processing method concerning a 2nd embodiment. The process flow figure showing an example of the substrate processing method concerning a 3rd embodiment.

(First embodiment)
Hereinafter, a substrate processing method and apparatus according to a first embodiment of the present invention will be described with reference to the drawings. The substrate processing apparatus according to the present embodiment includes a liquid processing unit 10 that performs liquid processing with various processing liquids on a wafer W that is a substrate, and a liquid that adheres to the surface of the wafer W after the liquid processing as a supercritical fluid. And a supercritical drying processing unit 20 (supercritical drying means) that is brought into contact with each other for extraction and substitution.

(Liquid processing unit)
FIG. 1 is a diagram illustrating an example of the liquid processing unit 10. The liquid processing unit 10 is configured as, for example, a single-wafer type liquid processing unit that cleans wafers W one by one by spin cleaning, or a batch-type liquid processing unit that simultaneously performs liquid processing of a plurality of wafers W. The liquid processing unit 10 includes a liquid processing chamber 11, a wafer holding unit 12, a cleaning liquid supply unit 13, an ultrapure water supply unit 14, a first solvent supply unit 15, and an intermediate solvent supply unit 16.

  The liquid processing chamber 11 forms a processing space in which liquid processing by the liquid processing unit 10 is performed. A drainage pipe 17 is provided at the bottom of the liquid processing chamber 11 for draining the cleaning liquid used for the liquid processing.

  The wafer holding unit 12 is disposed in the liquid processing chamber 11 and holds the wafer W substantially horizontally. By rotating the wafer holding unit 12 while holding the wafer W, the liquid processing unit 10 can spin-clean the wafer W.

  The cleaning liquid supply unit 13 is provided on the surface of the wafer W held by the wafer holding unit 12 so that a cleaning liquid for cleaning the surface of the wafer W can be supplied. The cleaning liquid supply unit 13 includes, for example, a storage unit 131 that stores the cleaning liquid and a nozzle that supplies the cleaning liquid stored in the storage unit to the surface of the wafer W. As the cleaning liquid, for example, SC1 (mixed liquid of ammonia and hydrogen peroxide solution) that is an alkaline cleaning liquid, dilute hydrofluoric acid (DHF) that is an acidic cleaning liquid, and the like are supplied.

  The ultrapure water supply unit 14 is provided on the surface of the wafer W held by the wafer holding unit 12 so that ultrapure water for rinsing the surface of the wafer W can be supplied. The ultrapure water supply unit 14 includes, for example, a storage unit 141 that stores ultrapure water, and a nozzle that supplies the ultrapure water stored in the storage unit to the surface of the wafer W. For example, deionized water (DIW) is supplied as the ultrapure water.

  The first solvent supply unit (first solvent supply unit) 15 is provided on the surface of the wafer W held by the wafer holding unit 12 so that the first solvent for preventing the surface of the wafer W from being dried can be supplied. It is done. The first solvent supply unit 15 includes, for example, a storage unit 151 that stores the first solvent, and a nozzle that supplies the first solvent stored in the storage unit to the surface of the wafer W. For example, a fluorine-containing organic solvent is used as the first solvent. The solvent used as the first solvent is selected based on the relationship with the second solvent described later. Details of the first solvent will be described later.

  The intermediate solvent supply unit (fluorinated alcohol-containing solvent supply unit) 16 is provided on the surface of the wafer W held by the wafer holding unit 12 so that the intermediate solvent can be supplied. The intermediate solvent supply unit 16 includes, for example, a storage unit 161 that stores the intermediate solvent, and a nozzle that supplies the intermediate solvent stored in the storage unit to the surface of the wafer W. In the liquid processing, after rinsing the surface of the wafer W by supplying ultrapure water to the surface of the wafer W, an intermediate solvent is supplied to the surface of the wafer W, and the ultrapure water adhering to the surface of the wafer W is removed from the intermediate solvent. Further, the first solvent is supplied to the surface of the wafer W, and the intermediate solvent is replaced with the first solvent. That is, the intermediate solvent is a solvent that is used intermediately to replace the ultrapure water adhering to the surface of the wafer W with the first solvent. Therefore, a solvent having solubility in ultrapure water and solubility in the first solvent is used as the intermediate solvent. Details of the intermediate solvent will be described later.

  A processing liquid supply path connected to the cleaning liquid supply unit 13, the ultrapure water supply unit 14, the first solvent supply unit 15, and the intermediate solvent supply unit 16 is formed inside the wafer holding unit 12. Also good. With such a configuration, various processing liquids such as a cleaning liquid, ultrapure water, a first solvent, and an intermediate solvent can be supplied via the processing liquid supply path, and liquid processing on the back surface of the wafer W can be realized.

(Supercritical drying unit)
FIG. 2 is a diagram illustrating an example of the supercritical drying processing unit 20. The supercritical drying processing unit 20 performs a drying process using a supercritical fluid on the wafer W that has been subjected to the liquid processing by the liquid processing unit 10. The supercritical drying processing unit 20 includes a chamber 21, a heater 22, a stage 23, a second solvent supply unit 24, and a second solvent recovery unit 25.

  The chamber 21 forms a processing space where the supercritical drying processing unit 20 performs a supercritical drying process on the wafer W. For example, the processing space is configured to store a wafer W having a diameter of 300 mm. The second solvent used as the supercritical fluid is supplied to the chamber 21 in a liquid state, and then subjected to a heat treatment to change into a supercritical state. Alternatively, the second solvent whose phase has been changed to the supercritical state in advance may be directly supplied to the chamber 21. Alternatively, a gaseous second solvent heated to a temperature higher than the critical temperature in advance may be supplied to the chamber 21, and the phase may be changed to a supercritical state by pressurization. The chamber 21 is configured as a pressure vessel formed of, for example, stainless steel.

  The heater 22 raises the temperature of the processing space in the chamber 21. When the processing space is heated by the heater 22, the temperature and pressure of the second solvent supplied to the surface of the wafer W rise, and the second solvent changes into a supercritical state. As shown in FIG. 2, the heater 22 may be embedded in the side surface of the chamber 21, may be embedded in the upper surface or the lower surface of the chamber 21, and may be provided inside or outside the chamber 21. The heater 22 is composed of, for example, a resistance heating element. By controlling ON / OFF of the heater 22 by a control unit (not shown), the temperature of the processing space can be adjusted.

  The stage 23 is provided inside the chamber 21 and holds the wafer W introduced into the processing space. The stage 23 is configured as a disk-shaped holding member made of, for example, stainless steel.

  The second solvent supply unit 24 includes a storage unit 241 that stores the second solvent, and a liquid feeding unit that feeds the second solvent stored in the storage unit 241. A pressure-resistant pump or the like can be used as the liquid feeding means. The second solvent supply unit 24 is connected to the chamber 21 via the solvent supply path 26, and the second solvent sent out by the liquid feeding means is supplied into the chamber 21 via the solvent supply path 26. A valve 27 that opens and closes the solvent supply path 26 is provided on the solvent supply path 26.

  The 2nd solvent collection | recovery part 25 is equipped with the storage part 251 which stores the 2nd solvent collect | recovered after completion | finish of a supercritical drying process. The second solvent recovery unit 25 is connected to the chamber 21 via the solvent discharge path 28, and the second solvent used for the supercritical drying process is recovered to the second solvent recovery unit 25 via the solvent discharge path 28. Is done. A valve 29 that opens and closes the solvent discharge path 28 is provided on the solvent discharge path 28.

  A cooling unit for cooling the second solvent may be provided on the second solvent recovery unit 25 or the solvent discharge path 28. Thereby, the second solvent discharged from the chamber 21 as a supercritical state or gas can be recovered in a liquid state. In addition, a flow path for the second solvent is provided between the second solvent supply unit 24 and the second solvent recovery unit 25, and a predetermined regeneration process is performed on the second solvent in the second solvent recovery unit 25. May be. Accordingly, the second solvent recovered by the second solvent recovery unit 25 can be regenerated, and the regenerated second solvent can be supplied again from the second solvent supply unit 24. Therefore, the second solvent can be reused.

  The substrate processing apparatus transports the wafer W into the liquid processing chamber 11 of the liquid processing unit 10 or transports the wafer W subjected to the liquid processing into the chamber 21 of the supercritical drying processing unit 20. Means may be provided.

(Intermediate solvent, first solvent, and second solvent)
Next, the intermediate solvent, the first solvent, and the second solvent used in the substrate processing method according to this embodiment will be described. In the substrate processing method according to this embodiment, the intermediate solvent, the first solvent, and the second solvent are used in this order. More specifically, after cleaning with the cleaning liquid, the wafer W is rinsed in the order of ultrapure water, an intermediate solvent, and the first solvent, and a supercritical drying process is performed in a state where the first solvent is accumulated on the surface. Is done. In the supercritical drying process, the second solvent is used as a supercritical fluid. In the substrate processing method, the first solvent is selected according to the second solvent used as the supercritical fluid, and the intermediate solvent is selected according to the first solvent. Therefore, in the following, the second solvent, the first solvent, and the intermediate solvent will be described in this order.

  The second solvent is, for example, a fluorine-containing organic solvent. More specifically, the second solvent is a fluorine-containing organic solvent that becomes a supercritical fluid at a relatively low temperature and is soluble in the first solvent. The critical temperature of the second solvent is preferably lower than the critical temperature of the first solvent. By performing the supercritical drying process using such a fluorine-containing organic solvent, the liquid adhering to the surface of the wafer W can be removed and the surface of the wafer W can be dried without causing pattern collapse. .

  In general, a fluorine-containing organic solvent may decompose under a high-temperature and high-pressure atmosphere in a supercritical state to generate fluorine atoms. Fluorine atoms may damage the wafer W by etching the surface of the wafer W or entering the inside of the wafer W. Therefore, the second solvent is preferably a fluorine-containing organic solvent having a low thermal decomposability that satisfies a fluorine atom content of 100 ppm by weight or less even when processed at a high temperature and high pressure above the critical point. By using such a fluorine-containing organic solvent as the second solvent, damage to the wafer W due to fluorine atoms can be suppressed.

  From the above viewpoint, for example, PFC (perfluorocarbon) is used as the second solvent. PFC is a fluorine-containing organic solvent in which all hydrogen contained in hydrocarbon is replaced with fluorine. As a suitable PFC, Fluorinert (registered trademark) FC-72 (hereinafter simply referred to as “FC-72”) manufactured by Sumitomo 3M Limited may be mentioned. FC-72 has a boiling point of about 56 ° C and a critical temperature of about 177 ° C. The second solvent can be arbitrarily selected from fluorine-containing organic solvents, and is not limited to PFC.

  The first solvent is a solvent that prevents the surface of the wafer W from drying before the second solvent introduced into the chamber 21 reaches a supercritical state in the chamber 21 and the surface of the wafer W. . Since the wafer W is introduced into the chamber 21 with the first solvent on its surface and subjected to supercritical drying, the first solvent is soluble in the second solvent. Is required. As such a first solvent, for example, a fluorine-containing organic solvent is used similarly to the second solvent. By using a fluorine-containing organic solvent as the first solvent, it is possible to suppress moisture from entering the wafer W. Furthermore, the fluorine-containing organic solvent is also suitable as a solvent for preventing drying because it is flame retardant.

  The first solvent is preferably a fluorine-containing organic solvent having a sufficiently high boiling point, for example, a boiling point of 100 ° C. or higher. The chamber 21 is heated to a temperature equal to or higher than the critical temperature of the second solvent in order to change the phase of the second solvent to the supercritical state. At this time, it is necessary to prevent the first solvent accumulated on the surface of the wafer W from being completely vaporized from the surface of the wafer W before being replaced with the supercritical fluid of the second solvent. . This is because the pattern collapse may occur if the first solvent accumulated on the substrate surface is completely vaporized before being replaced with the supercritical fluid of the second solvent. When the boiling point of the first solvent is sufficiently high, the risk of drying the surface of the wafer W filled with the first solvent before the phase change of the second solvent to the supercritical state is reduced. Can do.

  On the other hand, the boiling point of the first solvent is preferably a temperature not higher than the critical temperature of the second solvent. This is because when the first solvent accumulated on the surface of the wafer W is replaced with the second solvent in the chamber 21, the pressure in the chamber 21 is reduced to vaporize the second solvent. This is to prevent the solvent from adhering again to the surface of the wafer W. When the boiling point of the first solvent is higher than the critical temperature of the second solvent, when the second solvent is vaporized and discharged from the chamber 21, the first solvent remains in the liquid state and reattaches to the surface of the wafer W. There is a fear. The first solvent reattached causes particle defects and pattern collapse of the fine pattern. On the other hand, when the boiling point of the first solvent is equal to or lower than the critical temperature of the second solvent, the second solvent changes into a gas due to the decompression of the chamber 21, and the first solvent also turns into a gas. Since the phase changes, the liquid of the first solvent can be prevented from reattaching to the surface of the wafer W.

  From the above viewpoint, it is preferable that the first solvent has a sufficiently high boiling point in a range not higher than the critical temperature of the second solvent. For example, the boiling point is higher than the boiling point of the second solvent and the critical temperature of the second solvent. Lower is preferred. As such a first solvent, for example, PFC having a sufficiently high boiling point is used. When the second solvent is FC-72, Fluorinert (registered trademark) FC-43 (hereinafter simply referred to as “FC-43”) manufactured by Sumitomo 3M Limited can be used as the first solvent. The boiling point of FC-43 is about 174 ° C., which is sufficiently higher than the boiling point of FC-72, which is the second solvent, about 56 ° C. The critical temperature of FC-43 is about 294 ° C., which is higher than the critical temperature of FC-72 of about 177 ° C. Thus, when the boiling point of the first solvent is sufficiently high in the range below the critical temperature of the second solvent, the first solvent is completely consumed until the phase of the second solvent changes to the supercritical state. Therefore, drying of the surface of the wafer W can be suppressed. Further, since the vapor pressure of the first solvent is increased at the time when the phase of the second solvent changes to the supercritical state, the first solvent exhibits high solubility in the supercritical fluid. Note that the first solvent is not limited to PFC, and can be arbitrarily selected from fluorine-containing organic solvents having solubility in the second solvent.

  The intermediate solvent is a solvent for replacing the ultrapure water adhering to the surface of the wafer W with the first solvent. Therefore, the intermediate solvent is required to be soluble in ultrapure water and also soluble in the first solvent. Since general fluorine-containing organic solvents have little or no solubility in ultrapure water, it is difficult to directly replace the ultrapure water adhering to the surface of the wafer W with the first solvent. It is. Therefore, a solvent having solubility in both ultrapure water and the first solvent is used as the intermediate solvent.

  From the above viewpoint, for example, a fluorinated alcohol is used as the intermediate solvent. Since the fluorinated alcohol is not only soluble in ultrapure water and a fluorine-containing organic solvent, but also has no or low flammability, an explosion-proof facility is not required, and the configuration of the substrate processing apparatus can be simplified. The fluorinated alcohol includes a fluorinated alcohol having 1 to 6 carbon atoms. In particular, HFIP (Hexa Fluoro Isopropyl Alchol: 1,1,1,3,3,3-hexafluoro-2-propanol) is mentioned as a suitable fluorinated alcohol.

  HFIP has solubility in ultrapure water and also solubility in fluorine-containing organic solvents (for example, FC-43). HFIP is also suitable as an intermediate solvent because it is flame retardant. The intermediate solvent can be arbitrarily selected from solvents having solubility in ultrapure water and a fluorine-containing organic solvent (first solvent), and is not limited to a fluorinated alcohol.

(Substrate processing method)
Hereinafter, the substrate processing method according to the present embodiment will be described with reference to FIG. FIG. 3 is a process flow diagram of the substrate processing method according to the present embodiment.

  First, the wafer W is transferred into the liquid processing unit 10. The wafer holding unit 12 holds the transferred wafer W in a substantially horizontal state. Next, a cleaning liquid such as SC1 is supplied from the cleaning liquid supply unit 13, and the wafer W is cleaned (step S1). Thereby, particles and organic contaminants attached to the surface of the wafer W are removed.

  Next, ultrapure water is supplied from the ultrapure water supply unit 14, and the surface of the wafer W is rinsed with ultrapure water (step S2). As a result, the residue attached to the surface of the wafer W and the cleaning liquid such as SC1 are removed. Further, a cleaning liquid such as DHF is supplied from the cleaning liquid supply unit 13, and the surface of the wafer W is cleaned (step S3). Thereby, the natural oxide film formed on the surface of the wafer W is removed. Then, ultrapure water is again supplied from the ultrapure water supply unit 14, and the surface of the wafer W is rinsed with ultrapure water (step S4). As a result, cleaning liquid such as residues and DHF adhering to the surface of the wafer W is removed. The above cleaning process may be performed using another cleaning liquid, and the type and number of cleaning liquids used are also arbitrary.

  Next, the intermediate solvent is supplied from the intermediate solvent supply unit 16, and the surface of the wafer W is rinsed with the intermediate solvent (step S5). Since the intermediate solvent is soluble in ultrapure water, the ultrapure water adhering to the surface of the wafer W is replaced with the intermediate solvent. As described above, the intermediate solvent is, for example, a fluorinated alcohol.

  Further, the first solvent is supplied from the first solvent supply unit 15, and the surface of the wafer W is rinsed with the first solvent (step S6). Since the intermediate solvent is soluble in the first solvent, the intermediate solvent adhering to the surface of the wafer W is replaced with the first solvent. As described above, the first solvent is, for example, a high-boiling fluorine-containing organic solvent.

  As a result of the above liquid treatment, the surface of the wafer W is filled with the first solvent. The liquid-processed wafer W is introduced into the chamber 21 of the supercritical drying processing unit 20 (step S7). The substrate processing apparatus preferably includes a transfer unit that transfers the wafer W from the liquid processing unit 10 to the supercritical drying processing unit 20. Here, when the first solvent is a high-boiling fluorine-containing organic solvent, it is possible to prevent the first solvent from evaporating during the transfer of the wafer W and drying the surface of the wafer W.

  When the wafer W is introduced into the processing space in the chamber 21, the wafer W is held by the stage 23. Next, the second solvent is supplied in a liquid state from the second solvent supply unit 24 through the solvent supply path 26 into the chamber 21 (step S8).

  Note that the supercritical drying processing unit 20 may raise the temperature of the chamber 21 in advance before the wafer W is introduced. If the temperature is raised in advance, the time required for the supercritical drying process can be shortened. In addition, before the wafer W is introduced, the supercritical drying processing unit 20 preliminarily fills the casing of the supercritical drying processing unit 20 including the chamber 21 with an inert gas such as nitrogen gas or a rare gas. Also good. Thereby, oxygen and moisture are excluded from the inside of the supercritical drying processing unit 20, and thermal decomposition of the second solvent can be suppressed.

  When a predetermined amount of the second solvent is supplied into the chamber 21, the valves 27 and 29 are closed and the inside of the chamber 21 is sealed. The heater 22 raises the temperature of the processing space in the chamber 21 and the temperature of the wafer W so as to be higher than the critical point of the second solvent. For example, when the second solvent is FC-72, the temperature is raised so that the temperature in the chamber 21 is about 200 ° C. As a result, the second solvent is heated and expanded in the sealed chamber 21. Due to the expansion of the second solvent, the internal pressure of the chamber 21 rises, and the second solvent changes into a supercritical state. That is, a supercritical fluid by the second solvent is generated in the chamber 21 (step S9). At this time, the first solvent is selected so that the first solvent attached to the surface of the wafer W is not completely volatilized before the supercritical fluid is generated under high temperature and pressure.

  Note that the second solvent may be supplied into the chamber 21 in a supercritical state after the wafer W is introduced into the processing space in the chamber 21. In this case, the second solvent is supplied in a state where the valve 29 is closed, and after a predetermined amount of the second solvent is supplied into the chamber 21, the valve 27 is closed. In addition, after the wafer W is introduced into the processing space in the chamber 21, the gas-state second solvent heated to a temperature equal to or higher than the critical temperature may be supplied into the chamber 21. In this case, in a state where the valve 29 is closed, the second solvent in a gaseous state is supplied by a pump, and after a predetermined amount of the second solvent is supplied into the chamber 21, the valve 27 is closed. At this time, the second solvent is supplied until the pressure in the chamber 21 becomes equal to or higher than the critical pressure of the second solvent.

  After the second solvent changes to a supercritical state and a supercritical fluid is generated, the first solvent adhering to the surface of the wafer W is extracted into the supercritical fluid, and the first solvent on the surface of the wafer W is extracted. Is replaced by a supercritical fluid. Thereafter, after a predetermined time has elapsed, the valve 29 is opened, the inside of the chamber 21 is depressurized all at once, and the supercritical fluid changes to a gas (step S10). In addition, since the boiling point of the first solvent is equal to or lower than the critical temperature of the second solvent, the first solvent also changes to a gas by the reduced pressure. Then, the first solvent and the second solvent that have changed into a gas are discharged from the chamber 21 and are recovered by the solvent recovery unit 25 via the solvent recovery path 28. Therefore, it is possible to prevent the first solvent from reattaching to the surface of the wafer W, and to prevent particle defects and pattern collapse of the fine pattern.

  There is no interface between the supercritical state and the gas phase, and the phase change from supercritical fluid to gas occurs instantaneously. For this reason, the surface of the wafer W is instantaneously and uniformly dried by vaporizing the second solvent. Therefore, the surface of the wafer W can be dried without causing pattern collapse due to the influence of the surface tension. In addition, even when the second solvent is processed at a high temperature and high pressure above the critical point, by using a fluorine-containing organic solvent having a low thermal decomposability satisfying a fluorine atom content of 100 ppm by weight or less, the supercriticality can be obtained. Little release of fluorine atoms from the second solvent due to the drying process occurs. For this reason, it is possible to dry the wafer W while suppressing damage to the wafer W due to fluorine atoms.

  After the internal pressure of the chamber 21 becomes approximately the same as the atmospheric pressure, the wafer W is discharged from the chamber 21 (step S11). The substrate processing apparatus may include a transfer unit for discharging the wafer W from the chamber 21.

  As described above, according to the present embodiment, the liquid (first solvent) on the surface of the wafer W can be removed using the supercritical fluid (second solvent). The surface of the wafer W can be dried while being suppressed. Further, since the supercritical drying process is performed in a state where the first solvent having a sufficiently high boiling point is accumulated on the surface of the wafer W, drying of the surface of the wafer W can be suppressed. Furthermore, by using the first solvent having a boiling point equal to or lower than the critical temperature of the second solvent, the supercritical fluid is replaced after the first solvent is replaced with a supercritical fluid at a temperature higher than the boiling point of the first solvent. When the pressure is reduced from the high pressure state to the atmospheric pressure in order to change the phase of the fluid into a gas, the first solvent extracted and replaced with the supercritical fluid changes into a gas without being liquefied. The solvent does not re-adhere, and particle defects and pattern collapse of fine patterns can be prevented.

  Furthermore, by using fluorinated alcohol as an intermediate solvent, the ultrapure water adhering to the surface of the wafer W can be easily replaced with a fluorine-containing organic solvent (first solvent). Thereby, it is possible to simplify the process until the ultrapure water adhering to the surface of the wafer W is replaced with the first solvent, and the liquid processing cost can be reduced. Further, if fluorinated alcohol is used as the intermediate solvent, an explosion-proof facility or the like is not required, and the substrate processing apparatus can be simplified.

  In the present embodiment, the substrate processing apparatus may be configured by integrating the liquid processing unit 10 and the supercritical drying processing unit 20, or may be configured by combining independent apparatuses. .

(Second Embodiment)
In the substrate processing method according to the first embodiment, when the ultrapure water is replaced with the first solvent, the intermediate solvent is used. However, a configuration in which the intermediate solvent is not used is also possible. That is, in the substrate processing method according to the present embodiment, the ultrapure water is directly replaced with the first solvent.

  Here, FIG. 4 is a process flow diagram showing an example of the substrate processing method according to the second embodiment. In FIG. 4, the same steps as those in FIG. 3 are given the same step numbers, and the differences will be mainly described below.

  In FIG. 4, the process of step S5 of FIG. 3 is omitted. The first solvent used in step S6 in FIG. 4 has solubility in, for example, ultrapure water and is dissolved in a second solvent (fluorine-containing organic solvent such as FC-72) used as a supercritical fluid. It is a fluorinated alcohol having properties. By using such a first solvent, ultrapure water and the first solvent can be directly replaced. Then, the wafer W is introduced into the chamber 21 in a state where the first solvent is accumulated (step S7), and the supercritical drying process similar to that of the first embodiment is performed (steps S8 to S11).

  When the second solvent is FC-72, HFIP can be used as the first solvent. HFIP has solubility in ultrapure water and FC-72. HFIP has a boiling point of about 59 ° C. and a critical temperature of about 182.9 ° C. That is, the boiling point of HFIP is higher than that of FC-72 (about 56 ° C.) and lower than the critical temperature of FC-72 (about 182 ° C.).

  According to the present embodiment, the liquid processing step of the wafer W can be simplified as compared with the first embodiment, and the number of solvents used for the liquid processing can be reduced, so that the liquid processing cost can be further reduced.

(Third embodiment)
In the substrate processing method according to the first embodiment, only the fluorinated alcohol is used as the intermediate solvent, but a configuration using two types of intermediate solvents is also possible. Here, FIG. 5 is a process flow diagram showing an example of the substrate processing method according to the third embodiment. In FIG. 5, the same step numbers are assigned to the steps common to FIG. 3, and the differences will be mainly described below.

  In FIG. 5, after the step S4, the surface of the wafer W is rinsed with the first intermediate solvent (step S12) and further rinsed with the second intermediate solvent (step S13). The subsequent steps are the same as those after step S6 in FIG.

  The first intermediate solvent is a solvent for replacing the ultrapure water adhering to the surface of the wafer W with the second intermediate solvent. Therefore, the first intermediate solvent is required to be soluble in ultrapure water and the second intermediate solvent. As such a first intermediate solvent, for example, IPA (Iso Propyl Alcohol) is used. IPA not only has solubility in ultrapure water, but also is inexpensive and can reduce liquid processing costs.

  The second intermediate solvent is a solvent for replacing the first intermediate solvent (IPA) attached to the surface of the wafer W with the first solvent (fluorine-containing organic solvent). Therefore, the second intermediate solvent is required to be soluble in the first intermediate solvent and the first solvent. As such a second intermediate solvent, for example, HFE (Hydro Fluoro Ether) is used. When the first solvent is FC-43, the second intermediate solvent is preferably Novec (registered trademark) HFE7300 (hereinafter, simply referred to as “HFE7300”) manufactured by Sumitomo 3M Limited. HFE7300 is suitable for an intermediate solvent because it is soluble in IPA and FC43 and is nonflammable.

  As for the first intermediate solvent and the second intermediate solvent, the first intermediate solvent is soluble in ultrapure water, and the second intermediate solvent is soluble in the first solvent (fluorine-containing organic solvent). The first intermediate solvent and the second intermediate solvent can be arbitrarily selected from a combination of solvents that are soluble in each other. In addition, as an intermediate solvent in the first embodiment, a mixed liquid of a first intermediate solvent (IPA) and a second intermediate solvent (HFE) may be used. The mixing ratio of the first intermediate solvent and the second intermediate solvent can be arbitrarily selected from ratios in which the mixed solution is soluble in ultrapure water and the first solvent.

  A substrate processing apparatus that realizes a substrate processing method according to the present embodiment includes a first intermediate solvent supply unit (IPA-containing solvent supply unit) that supplies a first intermediate solvent and a second intermediate solvent that supplies a second intermediate solvent to a solvent supply unit. 2 intermediate solvent supply part (HFE-containing solvent supply part) can be provided.

  According to the present embodiment, since the liquid (first solvent) on the surface of the wafer W can be removed using the supercritical fluid (second solvent), the wafer collapses while suppressing the occurrence of pattern collapse. The surface of W can be dried.

  Note that the present invention is not limited to the above-described embodiments as they are, and can be embodied by modifying the components without departing from the scope of the invention in the implementation stage. Moreover, various inventions can be formed by appropriately combining a plurality of constituent elements disclosed in the above embodiments. Further, for example, a configuration in which some components are deleted from all the components shown in each embodiment is also conceivable. Furthermore, you may combine suitably the component described in different embodiment.

W: wafer, 10: liquid processing unit, 11: liquid processing chamber, 12: wafer holding unit, 13: cleaning liquid supply unit, 14: ultrapure water supply unit, 15: first solvent supply unit, 16: intermediate solvent supply unit , 17: drainage pipe, 20: supercritical drying processing unit, 21: chamber, 22: heater, 23: stage, 24: second solvent supply unit, 25: second solvent recovery unit, 26: solvent supply path, 27 : Valve, 28: Second solvent discharge path, 29: Valve

Claims (12)

Supplying water to the surface of the substrate;
Supplying a solvent containing IPA (isopropyl alcohol) to the surface of the substrate to which the water has adhered;
Supplying a solvent containing HFE (hydrofluoroether) to the surface of the substrate to which the solvent containing IPA is attached;
A first solvent having a solubility in the solvent containing HFE and having a boiling point of 100 ° C. or more containing PFC (perfluorocarbon) is supplied to the surface of the substrate to which the solvent containing HFE is attached. And a process of
The substrate to which the first solvent is attached is introduced into the chamber, the first solvent on the surface of the substrate is replaced with a supercritical fluid containing fluorine, and then the pressure in the chamber is lowered. Changing the supercritical fluid into a gas;
Discharging the substrate from the chamber;
A substrate processing method comprising: The boiling point of the first solvent, the substrate processing method according to claim 1, characterized in that below the critical temperature of the supercritical fluid. The boiling point of the first solvent, the substrate processing method according to claim 1 or 2, characterized in that higher than the boiling point of the supercritical fluid. After introducing the substrate with the first solvent attached thereto into the chamber,
Supplying a second solvent into the chamber;
Producing a supercritical fluid by changing the phase of the second solvent;
The substrate processing method according to any one of claims 1 to 3 further comprising a. The substrate processing method according to claim 4 , wherein the second solvent is a solvent containing PFC (perfluorocarbon). Solvent, the substrate processing method according to any one of claims 1 to 5, wherein the non-combustible containing the HFE. A water supply unit for supplying water to the surface of the substrate;
An IPA-containing solvent supply unit for supplying a solvent containing IPA (isopropyl alcohol) to the surface of the substrate to which the water has adhered;
An HFE-containing solvent supply unit for supplying a solvent containing HFE (hydrofluoroether) to the surface of the substrate to which the solvent containing IPA is attached;
A first solvent having a solubility in the solvent containing the HFE and having a boiling point of 100 ° C. or more containing PFC (perfluorocarbon) is supplied to the surface of the substrate to which the HFE-containing solvent is attached. 1 solvent supply section;
The substrate to which the first solvent is attached is introduced into the chamber, the first solvent on the surface of the substrate is replaced with a supercritical fluid containing fluorine, and then the pressure in the chamber is lowered. A supercritical drying treatment means for changing the supercritical fluid into a gas;
A substrate processing apparatus comprising: The substrate processing apparatus according to claim 7 , wherein a boiling point of the first solvent is lower than a critical temperature of the supercritical fluid. The substrate processing apparatus according to claim 7 , wherein a boiling point of the first solvent is higher than a boiling point of the supercritical fluid. A second solvent supply unit for supplying a second solvent into the chamber;
The substrate processing apparatus according to claim 7 , wherein the supercritical drying processing unit generates the supercritical fluid by changing the phase of the second solvent to a supercritical state. The substrate processing apparatus according to claim 10 , wherein the second solvent is a solvent containing PFC (perfluorocarbon). 12. The substrate processing apparatus according to claim 7 , wherein the solvent containing HFE is nonflammable.

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