JP2018078200A - Substrate processing method, substrate processing device and storage medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent occurrence of pattern collapse in an object to be processed in a unit under supercritical processing.SOLUTION: An object to be processed W subjected to liquid filling with a drying prevention liquid is carried in a container 3A for a super critical processing unit. A super critical processing fluid, which is different from drying prevention liquid and has solubility with the drying prevention liquid, is supplied into the container 3A for the super critical processing unit. The container 3A for the super critical processing unit is heated and the mixture of the drying prevention liquid and the super critical processing fluid is brought into a super critical state to dry the object to be processed.SELECTED DRAWING: Figure 5

Description

  The present invention relates to a substrate processing method, a substrate processing apparatus, and a storage medium for removing liquid adhering to the surface of a substrate using a fluid in a supercritical state.

  In the manufacturing process of a semiconductor device in which a laminated structure of integrated circuits is formed on the surface of a semiconductor wafer (hereinafter referred to as a wafer) as a substrate, a minute dust or a natural oxide film on the wafer surface is removed by a cleaning liquid such as a chemical solution. A liquid processing step for processing the wafer surface using a liquid is provided.

  As a technique for removing liquid adhering to the wafer surface, a method using a fluid in a supercritical state is known.

  For example, in Patent Document 1, fluorine is added to both the liquid for preventing drying and the fluid in the supercritical state from the viewpoint of high replacement of the liquid and the fluid in the supercritical state and suppression of moisture introduction during the liquid treatment. Contains organic solvent.

  Specifically, when moisture remains on the wafer surface, in order to remove the moisture, first, a water-soluble organic solvent is supplied to the wafer surface to replace the moisture, and then a liquid for preventing drying is applied to the wafer surface. Supply. The wafer with the liquid for preventing drying on the surface is then transferred into the supercritical processing unit container, and the supercritical processing fluid is in a supercritical state with respect to the wafer in the supercritical processing unit container. Is supplied and replaced with a liquid for preventing drying, and supercritical treatment is performed.

  However, when supercritical processing fluid is supplied to the wafer by supercritical processing fluid in a supercritical state and replaced with a liquid for preventing drying, the supercritical processing fluid in the supercritical state is super liquid. Since the density is lower than that of the critical processing fluid, a certain amount of replacement time is required to replace and remove the liquid for preventing drying of the wafer surface, and the processing time for removing the liquid becomes long.

Japanese Patent Laid-Open No. 2014-22566

  The present invention has been made in consideration of such points, and a substrate processing method, a substrate processing apparatus, and a storage medium that can shorten the time for removing the liquid adhering to the surface of the wafer by supercritical processing. The purpose is to provide.

    The present invention includes a step of transporting an object to be processed, which is liquid-filled with a liquid for preventing drying, into a container for a supercritical processing unit, and is different from the liquid for preventing drying on the object to be processed, and the drying Supplying a liquid for prevention and a supercritical processing fluid having solubility to form a mixture of the liquid for preventing drying and the fluid for supercritical processing on the object to be processed; A substrate processing method comprising: heating the mixed liquid above to form a supercritical fluid from the mixed liquid and performing a supercritical process on the object to be processed. .

  The present invention relates to a container for a supercritical processing unit that performs supercritical processing on an object to be processed, and a transport that transports the object to be processed that is filled with a liquid for preventing drying into the container for a supercritical processing unit. And a supercritical processing fluid that is different from the drying prevention liquid and has solubility with the drying prevention liquid on the object to be processed, and the drying prevention liquid on the object to be processed. In the supercritical processing unit container, and a supercritical processing fluid supply part that forms a mixture of the liquid and the supercritical processing fluid, and a heating part that heats the inside of the supercritical processing unit container. The substrate processing apparatus is characterized in that the mixed solution is heated by the heating unit to form a supercritical fluid from the mixed solution to perform supercritical processing on the object to be processed.

  The present invention relates to a storage medium for causing a computer to execute a substrate processing method. The substrate processing method includes a step of transporting an object to be processed, which is filled with a liquid for preventing drying, into a container for a supercritical processing unit; A supercritical processing fluid that is different from the drying prevention liquid and has solubility with the drying prevention liquid is supplied onto the object to be processed; Forming a liquid mixture of the supercritical processing fluid; heating the liquid mixture on the object to be processed; forming a fluid in a supercritical state from the liquid mixture; And a step of performing critical processing.

  According to the present embodiment, the time for removing the liquid adhering to the surface of the wafer by supercritical processing can be shortened compared to the prior art.

FIG. 1 is a cross-sectional plan view of a liquid processing apparatus. FIG. 2 is a longitudinal side view of a liquid processing unit provided in the liquid processing apparatus. FIG. 3 is a configuration diagram of a supercritical processing unit provided in the liquid processing apparatus. FIG. 4 is an external perspective view of the processing container of the supercritical processing unit. FIG. 5 is a diagram showing a collapse result of the present embodiment. FIGS. 6A and 6B are views showing the operation of the present embodiment. FIGS. 7A and 7B are views showing the operation of the present embodiment. FIGS. 8A and 8B are views showing a method for supplying a fluid for supercritical processing. FIGS. 9A and 9B are diagrams showing another supply method of the supercritical processing fluid.

<Substrate processing equipment>
First, a substrate processing apparatus according to the present invention will be described. As an example of a substrate processing apparatus, a liquid processing unit 2 for supplying various processing liquids to a wafer W (object to be processed), which is a substrate, and performing liquid processing, and a drying prevention adhering to the wafer W after liquid processing. A liquid processing apparatus 1 including a supercritical processing unit 3 that transports liquid and performs supercritical processing on the wafer W will be described.

  FIG. 1 is a cross-sectional plan view showing the overall configuration of the liquid processing apparatus 1, and the left side is the front side in the figure. In the liquid processing apparatus 1, the FOUP 100 is mounted on the mounting unit 11, and a plurality of wafers W having a diameter of 300 mm, for example, stored in the FOUP 100 are transferred to the subsequent liquid processing unit via the loading / unloading unit 12 and the transfer unit 13. 14 is transferred to and from the supercritical processing unit 15 and is sequentially carried into the liquid processing unit 2 and the supercritical processing unit 3 to perform processing for removing the liquid for liquid processing and drying prevention. In the figure, reference numeral 121 denotes a first transfer mechanism for transferring the wafer W between the FOUP 100 and the transfer unit 13, and 131 denotes a wafer transferred between the carry-in / out unit 12, the liquid processing unit 14, and the supercritical processing unit 15. W is a delivery shelf that serves as a buffer on which W is temporarily placed.

  The liquid processing unit 14 and the supercritical processing unit 15 are provided with a transfer space 162 for the wafer W extending in the front-rear direction from the opening between the transfer unit 13 and the transfer unit 13. For example, four liquid processing units 2 are arranged along the transfer space 162 in the liquid processing unit 14 provided on the left hand side of the transfer space 162 when viewed from the front side. On the other hand, in the supercritical processing unit 15 provided on the right hand side of the transfer space 162, for example, two supercritical processing units 3 are arranged along the transfer space 162.

  The wafer W is transferred between the liquid processing unit 2, the supercritical processing unit 3, and the delivery unit 13 by the second transfer mechanism 161 disposed in the transfer space 162. The second transport mechanism 161 corresponds to a substrate transport unit. Here, the number of liquid processing units 2 and supercritical processing units 3 arranged in the liquid processing unit 14 and the supercritical processing unit 15 is the number of wafers W processed per unit time, the liquid processing unit 2 and the supercritical processing unit. 3 is selected as appropriate depending on the difference in processing time at 3 and the optimum layout is selected according to the number of the liquid processing units 2 and supercritical processing units 3 arranged.

  The liquid processing unit 2 is configured as a single-wafer type liquid processing unit 2 that cleans wafers W one by one, for example, by spin cleaning, and a liquid processing unit chamber that forms a processing space as shown in a vertical side view of FIG. An outer chamber 21, a wafer holding mechanism 23 that is disposed in the outer chamber 21 and rotates the wafer W around the vertical axis while holding the wafer W substantially horizontally, and the wafer holding mechanism 2 is surrounded from the side peripheral side. The inner cup 22 that receives the liquid splashed from the wafer W and is configured to be movable between an upper position of the wafer W and a position retracted from the inner cup 22, and a nozzle 241 provided at the tip thereof Arm 24.

  The nozzle 241 includes a treatment liquid supply unit 201 that supplies various chemical solutions (chemical solutions such as DHF) and DIW, a rinse solution supply unit 202 that supplies a rinse solution (IPA), and a liquid for preventing drying on the surface of the wafer W. The first fluorine-containing organic solvent supply unit 203a (first fluorine-containing organic solvent supply unit) that supplies the first fluorine-containing organic solvent and the second fluorine that supplies the second fluorine-containing organic solvent A contained organic solvent supply unit 203b (second fluorine-containing organic solvent supply unit) is connected. The first fluorine-containing organic solvent and the second fluorine-containing organic solvent are different from the fluorine-containing organic solvent for supercritical processing used in the supercritical processing described later, and the first fluorine-containing organic solvent is used. A solvent, a second fluorine-containing organic solvent, and a fluorine-containing organic solvent for supercritical processing, which have a predetermined relationship at the boiling point or critical temperature, are employed. Will be described later.

Further, the outer chamber 21 is provided with an FFU (Fan Filter Unit) 205, and air purified from the FFU 205 is supplied into the outer chamber 21. More outer chamber 21, a low humidity _{N 2} gas supply unit 206 is provided, a low humidity _{N 2} gas is supplied into the outer chamber 21 from the low humidity _{N 2} gas supply unit 206.

  Further, the chemical liquid supply path 231 may be formed inside the wafer holding mechanism 23, and the back surface of the wafer W may be cleaned with the chemical liquid and the rinsing liquid supplied therefrom. At the bottom of the outer chamber 21 and the inner cup 22, there are provided an exhaust port 212 for exhausting the internal atmosphere and drain ports 221 and 211 for discharging the liquid shaken off from the wafer W.

  A first fluorine-containing organic solvent and a second fluorine-containing organic solvent, which are liquids for preventing drying, are supplied to the wafer W that has been subjected to the liquid processing in the liquid processing unit 2. In the state covered with the liquid of the second fluorine-containing organic solvent, it is transported to the supercritical processing unit 3 by the second transport mechanism 161. In the supercritical processing unit 3, the wafer W is brought into contact with the supercritical processing fluid of the fluorine-containing organic solvent for supercritical processing to remove the liquid of the second fluorine-containing organic solvent, and the wafer W is dried. Is done. Hereinafter, the configuration of the supercritical processing unit 3 will be described with reference to FIGS.

  The supercritical processing unit 3 includes a processing container 3A as a container for a supercritical processing unit in which processing for removing the liquid of the second fluorine-containing organic solvent adhering to the surface of the wafer W is performed, and supercritical processing is performed on the processing container 3A. And a supercritical processing fluid supply unit 414 for supplying a fluorine-containing organic solvent.

  As shown in FIG. 4, the processing container 3 </ b> A includes a housing-like container body 311 in which an opening 312 for carrying in / out the wafer W is formed, and a wafer tray 331 that can hold the wafer W to be processed horizontally. And a lid member 332 that supports the wafer tray 331 and seals the opening 312 when the wafer W is carried into the container main body 311.

  The container main body 311 is a container in which a processing space of about 200 to 10000 cm 3 that can accommodate, for example, a wafer W having a diameter of 300 mm is formed, and a supercritical processing fluid is supplied into the processing container 3A on the upper surface thereof. The supercritical processing fluid supply line 351 is connected to a discharge line 341 (discharge unit) provided with an on-off valve 342 for discharging the fluid in the processing container 3A. Further, the processing container 3A has a pressing mechanism (not shown) for pressing the lid member 332 toward the container body 311 against the internal pressure received from the supercritical processing fluid in the processing space and sealing the processing space. Is provided.

  The container main body 311 is provided with a heater 322 which is a heating unit made of, for example, a resistance heating element, and a temperature detection unit 323 including a thermocouple for detecting the temperature in the processing container 3A. By heating the main body 311, the temperature in the processing container 3 </ b> A can be heated to a preset temperature, thereby heating the internal wafer W. The heater 322 can change the amount of generated heat by changing the power supplied from the power supply unit 321, and sets the temperature in the processing container 3 </ b> A in advance based on the temperature detection result acquired from the temperature detection unit 323. Adjust to the adjusted temperature.

  The supercritical processing fluid supply unit 414 is connected to the upstream side of the supercritical processing fluid supply line 351 having an on-off valve 352 interposed therebetween. The supercritical processing fluid supply unit 414 is for supplying a fluorine-containing organic solvent liquid for supercritical processing onto the wafer W accommodated in the processing container 3A.

The supercritical processing fluid supply unit 414 includes a tank 414A for storing the fluorine-containing organic solvent for supercritical processing in a liquid state, a high-pressure pump for liquid supply 414B, an N ₂ gas supply line 414C, a flow rate adjusting mechanism, and the like. (See FIG. 8).

  The liquid processing apparatus 1 including the liquid processing unit 2 and the supercritical processing unit 3 having the above-described configuration is connected to the control unit 5 as shown in FIGS. The control unit 5 includes a computer having a CPU and a storage unit 5a (not shown). The operation of the liquid processing apparatus 1, that is, the wafer W is taken out from the FOUP 100 and processed in the liquid processing unit 2 in the storage unit 5a. Next, a program in which a group of steps (commands) related to the control from the process of drying the wafer W in the supercritical processing unit 3 to the loading of the wafer W into the FOUP 100 is recorded. This program is stored in a storage medium such as a hard disk, a compact disk, a magnetic optical disk, or a memory card, and installed in the computer therefrom.

Next, the first fluorine-containing organic solvent and the second fluorine-containing organic solvent as the drying preventing liquid supplied to the surface of the wafer W by the liquid processing unit 2 and the drying preventing liquid are supplied to the wafer W. The fluorine-containing organic solvent for supercritical processing supplied to the processing vessel 3A for removal from the surface will be described. Here, the first fluorine-containing organic solvent and the second fluorine-containing organic solvent for preventing drying and the fluorine-containing organic solvent for supercritical treatment are all fluorine-containing organic solvents containing fluorine atoms in hydrocarbon molecules. It is.
When a fluorine-containing organic solvent is selected as the fluorine-containing organic solvent for supercritical processing, the second fluorine-containing organic solvent has a higher boiling point (lower vapor pressure) than the fluorine-containing organic solvent for supercritical processing Things are chosen. As a result, compared with the case where a fluorine-containing organic solvent for supercritical processing is adopted as the liquid for preventing drying, the surface of the wafer W is transferred while being transferred from the liquid processing unit 2 to the supercritical processing unit 3. The amount of the fluorine-containing organic solvent that volatilizes can be reduced.

    More preferably, the boiling point of the first fluorine-containing organic solvent is around 100 ° C., and the boiling point of the second fluorine-containing organic solvent is preferably 100 ° C. or higher, which is higher than the boiling point of the first fluorine-containing organic solvent. . The second fluorine-containing organic solvent having a boiling point of 100 ° C. or more has a smaller volatilization amount during the transfer of the wafer W. Can maintain the wet state of the surface of the wafer W for about several tens of seconds to 10 minutes by supplying a small amount of a fluorine-containing organic solvent of about 0.02 to 10 cc. For reference, in order to keep the surface of the wafer W wet for the same time by IPA, a supply amount of about 10 to 50 cc is required.

    Further, when a fluorine-containing organic solvent for supercritical processing and a second fluorine-containing organic solvent are selected, the level of the boiling point corresponds to the level of the supercritical temperature. Therefore, a supercritical fluid can be formed at a low temperature by selecting a fluorine-containing organic solvent for supercritical processing used as a supercritical processing fluid that has a lower boiling point than the second fluorine-containing organic solvent. A possible fluorine-containing organic solvent can be used, and release of fluorine atoms due to decomposition of the fluorine-containing organic solvent can be suppressed.

<Operation of the present embodiment>
Next, the operation of the present embodiment having such a configuration will be described with reference to FIGS. 1 to 8A and 8B.

    In the present embodiment, for example, HFE7300 (Sumitomo 3M Co., Ltd. Novec (registered trademark) 7300, boiling point 98 ° C.) is used as the first fluorine-containing organic solvent, and FC43 (Sumitomo 3M Co., Ltd.) is used as the second fluorine-containing organic solvent. For example, FC72 (Sumitomo 3M Fluorinert (registered trademark) FC-72 boiling point 56 ° C.) as a fluorine-containing organic solvent for supercritical processing using a liquid for preventing drying containing Fluorinert (registered trademark) FC-43 boiling point 174 ° C. ) Will be described.

  First, the wafer W taken out from the FOUP 100 is loaded into the outer chamber 21 of the liquid processing unit 14 via the loading / unloading unit 12 and the transfer unit 13 and transferred to the wafer holding mechanism 23 of the liquid processing unit 2. Next, various processing liquids are supplied to the surface of the rotating wafer W to perform liquid processing.

  As such liquid processing, chemicals supplied from the processing liquid supply unit 201, for example, removal of particles and organic contaminants by DHF (dilute hydrofluoric acid) which is an acidic chemical, and supplied from the processing liquid supply unit 201 are used. DIW cleaning with deionized water (DeIonize DI Water: DIW) is performed (see FIG. 5).

  After the liquid treatment with the chemical solution and the DIW cleaning are completed, IPA as a water-soluble organic solvent is supplied from the rinse liquid supply unit 202 (IPA supply unit) to the surface of the rotating wafer W, and the DIW remaining on the surface of the wafer W Replace with When the liquid on the surface of the wafer W is sufficiently replaced with IPA, the first fluorine-containing organic solvent (HFE7300) is supplied from the first fluorine-containing organic solvent supply unit 203a to the surface of the rotating wafer W. Thereafter, the wafer W is subsequently rotated, and a second fluorine-containing organic solvent containing FC43 as a liquid for preventing drying is supplied from the second fluorine-containing organic solvent supply unit 203b to the surface of the rotating wafer W. Thereafter, the rotation of the wafer W is stopped. The surface of the wafer W after the rotation is stopped is covered with the second fluorine-containing organic solvent containing FC43. In this case, since IPA is highly soluble in DIW and HFE7300, DIW can be replaced by IPA, and then IPA can be replaced by HFE7300. Next, HFE7300 can be replaced with a second fluorine-containing organic solvent containing FC43 as a liquid for preventing drying.

During this period, that is, during the supply of DHF, the supply of DIW, the supply of IPA, the supply of the first fluorine-containing organic solvent, and the supply of the second fluorine-containing organic solvent, the humidity in the outer chamber 21 is continuously reduced. Low humidity (dew point −70 ° C. or lower) N ₂ gas is supplied from the N ₂ gas supply unit 206, and the inside of the outer chamber 21 is maintained in a low humidity N ₂ gas atmosphere. At this time, the humidity in the outer chamber 21 is preferably 3% or less.

In the above-described embodiment, the outer chamber is continuously provided during the supply of DHF, the supply of DIW, the supply of IPA, the supply of the first fluorine-containing organic solvent, and the supply of the second fluorine-containing organic solvent. 21 shows an example in which the low humidity N2 gas supply unit 206 supplies low humidity N2 gas from the low humidity N2 gas supply unit 206. However, the present invention is not limited to this, and at the time of supplying DHF, DIW, the first fluorine-containing organic solvent, and At the time of supplying the second fluorine-containing organic solvent, the control unit 5 controls the FFU 205 to supply clean air from the FFU 205 into the outer chamber 21, and only when supplying IPA, the control unit 5 controls the low humidity N2 gas supply unit 206. The low-humidity N2 gas may be supplied from the low-humidity N2 gas supply unit 206 into the outer chamber 21. Alternatively, during the supply of IPA and the supply of the first fluorine-containing organic solvent, or during the supply of IPA and the supply of the first fluorine-containing organic solvent and the supply of the second fluorine-containing organic solvent, the control unit 5 Thus, the low humidity N 2 gas supply unit 206 may be controlled to supply the low humidity N 2 gas from the low humidity N 2 gas supply unit 206 into the outer chamber 21. Thereby, the usage-amount of the low humidity N2 gas supplied in the outer chamber 21 can be reduced.

Thus, by maintaining the inside of the outer chamber 21 in a low humidity N ₂ gas atmosphere, moisture absorption into the IPA can be suppressed, and pattern collapse of the wafer W can be prevented during supercritical processing as will be described later. be able to.

  The wafer W that has been subjected to the liquid processing in this way is unloaded from the liquid processing unit 2 by the second transfer mechanism 161 and transferred to the supercritical processing unit 3. At this time, the second fluorine-containing organic solvent containing FC43 as a liquid for preventing drying remains on the wafer W in a state where the liquid is accumulated. Since the liquid for preventing drying contains the second fluorine-containing organic solvent containing FC43 having a high boiling point, the amount of the second fluorine-containing organic solvent containing FC43 that volatilizes from the surface of the wafer W during the transfer period is reduced. It is possible to prevent the upper surface of the wafer W from drying.

  Next, as shown in FIGS. 3 and 4, when the wafer W is loaded into the container main body 311 of the processing container 3A, the lid body 332 of the container main body 11 is closed and the inside of the processing container 3A is hermetically sealed. . Thereafter, before the liquid for preventing drying on the surface of the wafer W is dried, the on-off valve 352 of the supercritical processing fluid supply line 351 is opened, and the liquid supercritical processing fluid (FC72) is supplied from the supercritical processing fluid supply unit 414. ).

Next, supercritical processing in the supercritical processing unit 3 will be described in detail with reference to FIGS.
As shown in FIGS. 8A and 8B, the supercritical processing fluid supply unit 414 includes a tank 414A for storing liquid FC72, a high-pressure pump 414B for liquid supply, and an N ₂ gas supply line 414C. doing.

When supplying the FC72 liquid from the supercritical processing fluid supply unit 414, the on-off valve 352 is opened to supply _{N 2} gas from the _{N 2} gas supply line 414C into the tank 414A. As a result, the FC 72 in the tank 414A is released from the tank 414A, and is pressurized by the liquid feeding high-pressure pump 414B in the supercritical processing fluid supply line 351 and supplied into the processing container 3A (see FIG. 8A). .

  A wafer mounting table 311a for mounting a wafer W is provided in the container main body 311 in the processing container 3A, and the wafer W is mounted on the wafer mounting table 311a in the processing container 3A.

  The FC 72 supplied into the processing container 3A from the supercritical processing fluid supply line 351 is supplied from the upper part 311A of the container main body 311 onto the wafer W mounted on the wafer mounting table 311a (FIG. 8B). reference). In this case, the wafer W has a pattern WP on the surface thereof, and FC43 as a liquid for preventing drying remains in the pattern WP. As a supercritical processing fluid supplied on the wafer W, The FC 72 is deposited on the wafer W so as to cover the FC 43 remaining in the pattern WP.

  Thereafter, the FC 43 remaining in the pattern WP of the wafer W and the FC 72 supplied on the wafer W are mixed to form a mixed fluid, and the processing container 3A is heated to heat the mixed fluid to a supercritical state. As a result, the surface of the wafer W can be dried.

Hereinafter, with reference to FIGS. 6A to 6C and FIGS. 7A to 7C, a behavior in which a mixed fluid is formed by FC43 and FC72 to be in a supercritical state will be described.
First, as shown in FIG. 6A, the wafer W having the pattern WP is placed on the wafer placement table 311a of the processing container 3A. In this case, the liquid FC 43 as the liquid for preventing drying remains in the pattern WP of the wafer W.

  Next, as described above, liquid FC72 as a supercritical processing fluid is supplied onto the wafer W from the upper part of the container main body 311 of the processing container 3A (see FIG. 6B). In this case, before the FC 43 in the pattern WP of the wafer W volatilizes and collapses, that is, in a state where the FC 43 remains in the pattern WP, the FC 72 is supplied onto the wafer W, and the FC 72 remains in the pattern WP. So as to cover the wafer W.

  Next, as shown in FIG. 6C, on the wafer W, the liquid FC 43 and the liquid FC 72 are mixed to form a mixed fluid (mixed liquid). In this case, since the liquid FC43 and the liquid FC72 have high solubility to each other, they are easily and quickly mixed to form a mixed liquid. As a result, the pattern WP of the wafer W is also in a mixed liquid state.

  Since the liquid FC72 has a higher density than the supercritical FC72, the liquid FC43 can be mixed more rapidly with the liquid FC72 than when the liquid FC43 is replaced with the supercritical FC72.

  After the supercritical processing fluid is supplied from the supercritical processing fluid supply unit 414, the on-off valve 352 of the supercritical processing fluid supply line 351 is closed. Next, the heater 322 is operated to heat the inside of the processing container 3A (see FIG. 7A).

  Thus, after forming the liquid mixture of FC43 and FC72 on the wafer W, the inside of the processing container 3A is heated.

  In this way, by heating the mixed liquid of FC43 and FC72 on the wafer W, a part of the liquid is volatilized, thereby increasing the pressure in the container 3A. Next, as shown in FIG. 7 (b), the pressure in the container 3A rises by continuing heating, and when the predetermined temperature and pressure are reached, the liquid mixture becomes supercritical in the container 3A, and the wafer W The FC 43 remaining in the pattern WP is removed. The supercritical FC43 and FC72 may be a two-phase supercritical state of FC72 and FC43, or a state in which FC43 is dissolved in the supercritical FC72.

When the FC43, which is a liquid for preventing drying, is replaced with the supercritical FC72, the FC43 must not be dried from the wafer W until the FC43 is replaced with the FC72. However, since the container 3A is heated to the supercritical temperature of FC72, evaporation of FC43 occurs. The FC 43 may be dried during the time required to fill the container 3A with the supercritical FC 72.
In the present invention, liquid FC 72 is supplied onto the wafer W before the FC 43 is dried. The time for supplying the liquid FC72 onto the wafer W is shorter than that for filling the container 3A with FC72 supercriticality. The liquid mixture of liquids FC72 and FC43 on the wafer W is heated and volatilized in the container 3A. When the pressure of the mixed gas in the container caused by volatilization reaches the vapor pressure of the mixed gas according to the wafer temperature, It cannot volatilize more. Therefore, the supercriticality is reached if the amount of the liquid mixture on the wafer W is equal to or larger than the amount required to make the inside of the container 3A into the supercritical state of the mixed fluid calculated from the volume of the container 3A × the critical density. By this time, the wafer W will not dry and the pattern will not collapse.

  In this way, by heating the inside of the processing container 3A, the FC 43 as a liquid for preventing drying is removed from the surface of the wafer W, and the mixed flow of FC 43 and FC 72 is a supercritical fluid around the pattern WP. It becomes. Further, by forming a mixed liquid of FC43 and FC72 and making this mixed liquid a fluid in a supercritical state, the FC43 in the pattern WP can be removed, so that the inside of the pattern WP is not damaged without damaging the pattern WP or the like. It can be surely dried.

  Thus, when the time necessary for removing the FC 43 from the pattern WP on the surface of the wafer W has elapsed, the on-off valve 342 of the discharge line 341 is opened to discharge the supercritical fluid from the processing container 3A. At this time, the inside of the processing vessel 3A is maintained at a temperature equal to or higher than the critical temperature of the mixed fluid by the heater 322, for example. As a result, the mixed fluid FC72 can be discharged in a supercritical state or in a gas state without liquefying the supercritical liquid, and the occurrence of pattern collapse at the time of fluid discharge can be avoided (see FIG. 7C). .

  When the processing with the supercritical fluid is completed, the dried wafer W from which the liquid has been removed is taken out by the second transfer mechanism 161 and stored in the FOUP 100 via the transfer unit 13 and the loading / unloading unit 12. Finish the process. In the liquid processing apparatus 1, the above processing is continuously performed on each wafer W in the FOUP 100.

  As described above, according to the present embodiment, a supercritical processing fluid is supplied onto the wafer W on which the drying prevention liquid remains to form a mixed fluid, and the mixed fluid is heated to be in a supercritical state. In order to remove the anti-drying liquid by forming a fluid, in order to remove the anti-drying liquid compared to supplying a supercritical processing fluid in a supercritical state to the anti-drying liquid. Such processing time can be shortened.

<Modification of the present invention>
Next, a modification of the present invention will be described with reference to FIGS.
In the modification shown in FIGS. 9A and 9B, the same parts as those in the embodiment shown in FIGS. 1 to 8A and 8B are denoted by the same reference numerals, and detailed description thereof is omitted.

As shown in FIGS. 9A and 9B, the supercritical processing fluid supply unit 414 includes a tank 414A for storing liquid FC72, a high-pressure pump for liquid supply 414B, and an N ₂ gas supply line 414C. doing.

When supplying FC72 from the supercritical processing fluid supply section 414 of the liquid, supplying the _{N 2} gas from the _{N 2} gas supply line 414C into the tank 414A. As a result, the FC 72 in the tank 414A is released from the tank 414A, and is pressurized by the liquid feeding high-pressure pump 414B of the supercritical processing fluid supply line 351 and supplied into the processing container 3A (see FIG. 9A). .

  A wafer mounting table 311a for mounting a wafer W is provided in the container main body 311 in the processing container 3A, and the wafer W is mounted on the wafer mounting table 311a in the processing container 3A.

  The FC 72 supplied into the processing container 3A from the supercritical processing fluid supply line 351 is supplied from the upper part 311A of the container main body 311 onto the wafer W mounted on the wafer mounting table 311a (FIG. 9B). reference). In this case, the wafer W has a pattern WP on the surface thereof, and FC43 as a liquid for preventing drying remains in the pattern WP. As a supercritical processing fluid supplied on the wafer W, The FC 72 is deposited on the wafer W so as to cover the FC 43 remaining in the pattern WP.

  Thereafter, the FC 43 remaining in the pattern WP of the wafer W, the FC 43 supplied on the wafer W, and the soluble FC 72 are mixed to form a mixed fluid, and the processing fluid 3A is heated to heat the mixed fluid. By setting the supercritical state, the surface of the wafer W can be dried.

Further, the supercritical processing fluid supply line 351 branches off the downstream side of the liquid-feeding high-pressure pump 414B to form a branch line 351A (FIG. 9A).
For this reason, when opening the on-off valve 352 from the supercritical fluid supply line 351 and supplying the FC 72 onto the wafer W via the upper part 311A of the container body 311, the on-off valve 352A is opened from the branch line 351A at the same time. FC72 can be supplied into the container body 311 via the lower part 311B.

  Since the lower part 311B of the container body 311 has a higher temperature than the surface of the wafer W when the processing container 3A is heated, the FC 72 supplied from the lower part 311B into the container body 311 contacts the inner surface of the lower part 311B. It immediately volatilizes to produce FC72 vapor in the container body 311. As a result, the volatilization of the FC 72 from the wafer W is suppressed by the vapor pressure of the FC 72 in the container body 311. For this reason, the mixed fluid accumulated on the wafer W can be maintained on the wafer W again.

  In this embodiment, the method of supplying the liquid FC72 in the container 3A is exemplified. However, the liquid FC72 is supplied onto the wafer W covered with the FC43 outside the container 3A and covered with the mixed liquid of FC43 and FC72. The broken wafer W may be inserted into the container 3A.

W wafer 1 liquid processing apparatus 2 liquid processing unit 3 supercritical processing unit 3A processing vessel 5 control unit 5a storage unit 21 outer chamber 121 first transfer mechanism 161 second transfer mechanism 201 process liquid supply unit 202 rinse liquid supply unit 203a First fluorine-containing organic solvent supply unit 203b Second fluorine-containing organic solvent supply unit 311 Container body 311A Upper part 311B Lower part 311a Wafer mounting table 322 Heater 351 Supercritical processing fluid supply line 351A Branch line 414 Supercritical processing fluid supply 414A Tank 414B High-pressure pump for liquid supply 141C N ₂ gas supply line

Claims (9)

A step of transporting the object to be processed, which is filled with a liquid for preventing drying, into the container for the supercritical processing unit;
A supercritical processing fluid that is different from the drying prevention liquid and has solubility with the drying prevention liquid is supplied onto the object to be processed; Forming a mixture of the supercritical fluids;
Heating the mixed liquid on the object to be processed, forming a supercritical fluid from the mixed liquid, and performing a supercritical process on the object to be processed. Processing method.   2. The substrate processing method according to claim 1, wherein the supercritical processing fluid is supplied onto the target object in the supercritical processing unit container.   2. The substrate processing method according to claim 1, wherein the supercritical processing fluid is supplied onto the target object outside the supercritical processing unit container.   When supplying the supercritical processing fluid onto the target object in the supercritical processing unit container, the supercritical processing fluid is also supplied into the supercritical processing unit container at the same time. The substrate processing method according to claim 2.   5. The substrate processing method according to claim 1, wherein the supercritical processing fluid is supplied to a portion of the supercritical processing unit container heated to a higher temperature than the target object.   2. The substrate processing method according to claim 1, wherein the drying prevention liquid and the supercritical processing fluid contain a fluorine-containing organic solvent.   The supply amount of the supercritical processing fluid is calculated from “the volume of the supercritical processing unit container” × “the critical density of the mixed liquid”, and the vapor pressure of the mixed liquid is critical in the supercritical processing unit container. 2. The substrate processing method according to claim 1, wherein the substrate processing amount is equal to or greater than a predetermined amount necessary to reach the point. A container for a supercritical processing unit that performs supercritical processing on an object to be processed;
A transport means for transporting the object to be processed, which is filled with a liquid for preventing drying, into the container for the supercritical processing unit;
A supercritical processing fluid that is different from the drying prevention liquid and has solubility with the drying prevention liquid is supplied onto the object to be processed; A supercritical processing fluid supply unit for forming a mixture of the supercritical processing fluid;
A heating unit for heating the inside of the container for the supercritical processing unit,
A substrate characterized in that the mixed liquid is heated by the heating unit in the supercritical processing unit container to form a supercritical fluid from the mixed liquid to perform a supercritical process on the object to be processed. Processing equipment. In a storage medium for causing a computer to execute a substrate processing method,
The substrate processing method includes a step of conveying an object to be processed, which is filled with a liquid for preventing drying, into a container for a supercritical processing unit,
A supercritical processing fluid that is different from the drying prevention liquid and has solubility with the drying prevention liquid is supplied onto the object to be processed; Forming a mixture of the supercritical fluids;
And a step of heating the mixed liquid on the object to be processed, forming a supercritical fluid from the liquid mixture, and performing a supercritical process on the object to be processed. Medium.

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