JP5373429B2 - Substrate drying apparatus and substrate drying method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a substrate drier and a substrate drying method which are capable of successfully drying a substrate by removing a liquid attached on a substrate surface in an atmosphere at an atmospheric pressure. <P>SOLUTION: Nitrogen gas for freeze dry having a temperature lower than the freezing-point of DIW constructing a freezing film 12 and having a dew-point lower than the temperature of the freezing film 12 is continuously supplied toward the substrate surface Wf. Consequently, the partial pressure of the water vapor in the nitrogen gas for freeze dry is lower than the vapor pressure (sublimation pressure) of the freezing film 12, whereby sublimation dry goes on. In addition, the water vapor component generated by the sublimation is removed from the substrate surface Wf together with the flow of the nitrogen gas for freeze dry, whereby the water vapor component can securely be prevented from returning to the liquid phase and the solid phase and reattaching to the substrate surface Wf. In this manner, a rinse liquid attached on the substrate surface Wf can successfully be removed in an atmosphere at an atmospheric pressure for drying the substrate W. <P>COPYRIGHT: (C)2010,JPO&amp;INPIT

Description

  The present invention relates to a semiconductor wafer, a glass substrate for photomask, a glass substrate for liquid crystal display, a glass substrate for plasma display, a substrate for FED (Field Emission Display), an optical disk substrate, a magnetic disk substrate, a magneto-optical disk substrate, etc. The present invention relates to a substrate drying apparatus and a substrate drying method for drying various substrates (hereinafter simply referred to as “substrates”).

  The manufacturing process of an electronic component such as a semiconductor device or a liquid crystal display device includes a step of repeatedly forming a fine pattern by repeatedly performing processes such as film formation and etching on the surface of the substrate. Here, in order to perform fine processing satisfactorily, it is necessary to keep the substrate surface clean, and a cleaning process is performed on the substrate surface as necessary. After the cleaning process, it is necessary to remove the liquid such as DIW (deionized water) adhering to the substrate surface and dry the substrate. One of the important issues during drying is to dry the substrate without collapsing the pattern formed on the substrate surface. Sublimation drying techniques are attracting attention as a method for solving this problem. In this sublimation drying technique, as described in, for example, Patent Document 1 and Patent Document 2, after a liquid such as DIW adhering to the substrate surface is frozen in the processing chamber, the processing chamber is decompressed to freeze the frozen body. It is to sublimate.

JP-A-4-242930 (FIG. 2) Japanese Patent Laid-Open No. 4-331958 (FIG. 1)

  In the above prior art, the decompression process in the processing chamber is indispensable, the substrate cannot be dried at atmospheric pressure, and other substrate processes cannot be performed continuously in the same apparatus. For example, after cleaning a substrate using pure water such as DIW, it is difficult to dry the substrate immediately after cleaning the substrate. In addition, since it is necessary to reduce the pressure in the processing chamber, it is necessary to ensure airtightness in the processing chamber and to provide a vacuum pump or a valve for reducing the pressure in the processing chamber. As a result, the substrate drying apparatus is increased in size and cost.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide a substrate drying apparatus and a substrate drying method capable of satisfactorily drying a substrate by removing liquid adhering to the substrate surface in an atmospheric pressure atmosphere. And

In order to achieve the above object, a substrate drying apparatus according to the present invention freezes a liquid on a substrate surface and forms a frozen body of the liquid on the substrate surface, and a freezing point of the liquid toward the substrate surface. Sublimation drying means for continuously supplying a drying gas having a dew point lower than the temperature of the frozen body to sublimate and dry the frozen body, and a surface facing the substrate surface having a size equal to or larger than the substrate surface The drying gas is supplied to a space between the substrate surface and the blocking member disposed in proximity to the substrate surface . In order to achieve the above object, the substrate drying method according to the present invention freezes the liquid on the substrate surface and forms a frozen body of the liquid on the substrate surface, and then a substrate having a size equal to or larger than the substrate surface. A blocking member having a surface facing the surface and having an opening at the center is disposed close to the substrate surface, and has a dew point that is lower than the freezing point of the liquid and lower than the temperature of the frozen body from the opening toward the substrate surface. The drying gas is continuously supplied to sublimate and dry the frozen body.

  In the invention thus configured (substrate drying apparatus and substrate drying method), after the liquid on the substrate surface is frozen to form a frozen body, the frozen body is sublimated and substrate drying is performed. In common with the prior art. However, it is greatly different from the prior art in that the frozen body is sublimated in an atmospheric pressure atmosphere. In other words, in the present invention, the drying gas having a temperature lower than the freezing point of the liquid is supplied to the substrate surface to prevent the frozen body from returning to the liquid phase. As will be described in detail later, since the dew point of the drying gas is lower than the temperature of the frozen body, the partial pressure of water vapor in the drying gas is lower than the vapor pressure (sublimation pressure) of the frozen body and sublimates. Drying occurs. Moreover, although the partial pressure of water vapor in the drying gas near the frozen membrane may temporarily increase due to sublimation drying of the frozen body, since fresh drying gas is continuously supplied, The partial pressure of water vapor in the drying gas is maintained lower than the vapor pressure (sublimation pressure) of the frozen body, and sublimation drying continues. Moreover, since the liquid vapor component generated by sublimation is removed from the substrate surface by riding on the air flow of the drying gas, it is possible to reliably prevent the liquid vapor component from returning to the liquid phase or solid phase and reattaching to the substrate surface. it can. In this manner, the frozen body is sublimated from the solid phase to the gas phase without passing through the liquid phase in an atmospheric pressure atmosphere, and is removed from the substrate surface together with the drying gas to be dried.

  Here, for example, pure water can be used as the liquid. Further, for example, nitrogen gas can be used as the drying gas, and nitrogen gas having a temperature of −60 ° C. may be generated and supplied. Further, during the sublimation drying, the state in which the partial pressure of water vapor in the drying gas is lower than the vapor pressure of the frozen body is maintained, so that the sublimation drying is performed reliably and continuously.

  As described above, according to the present invention, the drying gas having a dew point lower than the freezing point of the liquid constituting the frozen body and lower than the temperature of the frozen body is continuously applied to the frozen body on the substrate surface. Since the frozen body is sublimated and dried by supplying the liquid, the liquid adhering to the substrate surface can be removed in an atmospheric pressure atmosphere to dry the substrate satisfactorily.

It is a figure which shows the substrate processing apparatus equipped with 1st Embodiment of the substrate drying apparatus concerning this invention. It is a block diagram which shows the control structure of the substrate processing apparatus of FIG. It is a figure which shows a gas cooling unit and a piping mechanism. It is a figure which shows typically operation | movement of the substrate processing apparatus of FIG. It is a vapor pressure curve of water and ice. It is a figure which shows the substrate processing apparatus equipped with 2nd Embodiment of the substrate drying apparatus concerning this invention. It is a figure which shows typically operation | movement of the substrate processing apparatus shown in FIG. It is a figure which shows typically operation | movement of 3rd Embodiment of the board | substrate drying apparatus concerning this invention. It is a figure which shows typically operation | movement of 4th Embodiment of the board | substrate drying apparatus concerning this invention.

  FIG. 1 is a diagram showing a substrate processing apparatus equipped with a first embodiment of a substrate drying apparatus according to the present invention, and FIG. 2 is a block diagram showing a control configuration of the substrate processing apparatus of FIG. This substrate processing apparatus is a single-wafer type substrate processing apparatus for rinsing the surface Wf of a substrate W such as a semiconductor wafer, and the substrate W is dried by sublimation drying after the rinsing process.

  The substrate processing apparatus includes a processing chamber 1 having a processing space for performing a cleaning process on the substrate W, and a control unit 4 for controlling the entire apparatus. In the processing chamber 1, a spin chuck 2, a DIW discharge nozzle 3, and a blocking member 9 are provided. The spin chuck 2 rotates the substrate W in a state where the surface Wf of the substrate W is held upward in a substantially horizontal posture. The DIW discharge nozzle 3 discharges DIW toward the surface Wf of the substrate W held by the spin chuck 2. The blocking member 9 is disposed above the spin chuck 2 so as to face the surface Wf of the substrate W held by the spin chuck 2.

  A disc-shaped spin base 23 is fixed to the upper end portion of the central shaft 21 of the spin chuck 2 by fastening parts such as screws. The central shaft 21 is connected to a rotation shaft of a chuck rotation mechanism 22 including a motor. When the chuck rotating mechanism 22 is driven in accordance with an operation command from the control unit 4, the spin base 23 fixed to the central shaft 21 rotates around the rotation center A0.

  Near the periphery of the spin base 23, a plurality of chuck pins 24 for holding the periphery of the substrate W are provided upright. Three or more chuck pins 24 may be provided to securely hold the circular substrate W, and are arranged at equiangular intervals along the peripheral edge of the spin base 23. Each of the chuck pins 24 includes a substrate support portion that supports the peripheral portion of the substrate W from below, and a substrate holding portion that holds the substrate W by pressing the outer peripheral end surface of the substrate W supported by the substrate support portion. ing. Each chuck pin 24 is configured to be switchable between a pressing state in which the substrate holding portion presses the outer peripheral end surface of the substrate W and a released state in which the substrate holding portion is separated from the outer peripheral end surface of the substrate W.

  Then, when the substrate W is delivered to the spin base 23, each chuck pin 24 is in a released state, and when the rinse process is performed on the substrate W, each chuck pin 24 is in a pressed state. When each chuck pin 24 is in a pressed state, each chuck pin 24 grips the peripheral edge of the substrate W, and the substrate W is held in a substantially horizontal posture at a predetermined interval from the spin base 23. As a result, the substrate W is held with the front surface Wf facing upward and the back surface Wb facing downward. In this embodiment, a fine pattern is formed on the surface Wf of the substrate W, and the surface Wf is a pattern formation surface.

  A nozzle driving rotary motor 31 is provided on the outer side in the circumferential direction of the spin chuck 2 as a driving source for scanning the DIW discharge nozzle 3. A rotary shaft 33 is connected to the rotary motor 31, and an arm 35 is connected to the rotary shaft 33 so as to extend in the horizontal direction, and the DIW discharge nozzle 3 is attached to the tip of the arm 35. When the rotary motor 31 is driven in accordance with an operation command from the control unit 4, the arm 35 swings around the rotary shaft 33.

  The blocking member 9 is formed in a disc shape having an opening at the center. The lower surface of the blocking member 9 is a substrate facing surface that faces the surface Wf of the substrate W substantially in parallel, and is formed to have a size equal to or larger than the diameter of the substrate W. The blocking member 9 is attached substantially horizontally to the lower end portion of the support shaft 91 having a substantially cylindrical shape. The support shaft 91 is held by an arm 92 extending in the horizontal direction. The arm 92 is connected to a blocking member elevating mechanism 94, and the blocking member 9 is brought close to the spin base 23 or separated from the spin base 23 according to an operation command from the control unit 4. Specifically, the control unit 4 controls the operation of the blocking member elevating mechanism 94 to move the blocking member 9 away from the spin chuck 2 when the substrate W is carried in and out of the substrate processing apparatus. While the substrate W is raised (position shown in FIG. 1), the surface Wf of the substrate W held by the spin chuck 2 is used when the substrate W is subjected to a freezing process, a drying process, and a dew condensation prevention process described later. Lower to the opposite position set in the immediate vicinity.

  The support shaft 91 is hollow, and the gas supply pipe 95 is inserted into the support shaft 91, and the gas supply pipe 96 is inserted into the gas supply pipe 95 to form a so-called double pipe structure. A nitrogen gas supply unit 64 for lyophilization is connected to the gas supply pipe 96. The freeze-drying nitrogen gas supply unit 64 is at a temperature lower than the freezing point of the liquid film of the rinsing liquid (DIW) in response to an operation command from the control unit 4 and is formed as described later. A freeze-drying nitrogen gas having a dew point lower than the temperature (for example, −20 ° C.), for example, −60 ° C. nitrogen gas is supplied to the gas supply pipe 96 to obtain the freeze-drying nitrogen gas. The gas cooling unit 640 is included.

  FIG. 3 shows a gas cooling unit and a piping mechanism. In the gas cooling unit 640, the container 641 has a tank structure that stores liquid nitrogen therein, and is formed of a material that can withstand the liquid nitrogen temperature, such as glass, quartz, or HDPE (High Density Polyethylene). Has been. In addition, you may employ | adopt the double structure which covers the container 641 with a heat insulation container. In this case, the outer container is made of a highly heat-insulating material such as foamable resin or PVC (polyvinyl chloride) in order to suppress heat transfer between the atmosphere outside the processing chamber and the container 641. It is preferable to form by.

  The container 641 is provided with a liquid nitrogen inlet 643 for taking in liquid nitrogen. Then, liquid nitrogen is introduced into the container 641 from the liquid nitrogen supply unit (not shown) through the introduction port 643. A liquid level sensor (not shown) is provided in the container 641 to keep the amount of liquid nitrogen in the container constant.

  In addition, a coil-shaped heat exchange pipe 647 formed of a metal pipe such as stainless steel or copper is provided as a gas delivery path inside the container 641. The heat exchange pipe 647 is immersed in liquid nitrogen stored in the container 641, and nitrogen gas is supplied into the inside from a nitrogen gas supply unit (not shown). As a result, the nitrogen gas is cooled by liquid nitrogen and output as lyophilized nitrogen gas. That is, in this embodiment, the container 641 for storing liquid nitrogen and the heat exchange pipe 647 provided therein constitute a heat exchanger.

  The gas cooling unit 640 configured as described above is connected to the gas supply pipe 96 via the double pipe 71 of the pipe mechanism 7. As shown in FIG. 3, the double pipe 71 is composed of an inner pipe 711 for passing a freeze-drying nitrogen gas and an outer pipe 712 formed of a heat insulating resin. Before reaching 96, the temperature of the freeze-drying nitrogen gas is prevented from rising. More specifically, the outer tube 712 has a flexible cube structure having a bellows structure made of PFA (tetrafluoroethylene and perfluoroalkylvinylether), and the outer tube 712 has a PFA. The made inner tube 711 is loosely inserted, and a spacer (not shown) prevents the inner tube 711 from being in the center of the outer tube 712 and coming into contact with the outer tube 712. Of the open ends of the double pipe 71, the open end on the cooling unit side is connected to the gas cooling unit 640 by the connectors 73 and 75 and the union 74, while the open end on the blocking member side is made of PFA. It is connected to the gas supply pipe 96 by a single union 76, a PTFE (polytetrafluoroethylene) sleeve cap 77, and PFA connectors 78 and 79, and both ends of the double pipe 71 are sealed. . The inside of the double pipe 71, that is, the inside of the outer pipe 712 is exhausted and depressurized, thereby improving the heat insulation. Thus, the freeze-drying nitrogen gas can be supplied to the gas supply pipe 96 while suppressing the temperature rise of the freeze-drying nitrogen gas cooled by the gas cooling unit 640.

  Returning to FIG. A lower end portion of the gas supply pipe 96 extends to the opening of the blocking member 9, and a freeze-drying nitrogen gas discharge nozzle 97 is provided at the tip thereof. Then, as described below, low-temperature lyophilization nitrogen gas is supplied toward the substrate surface Wf in the freezing process for freezing the liquid film and the drying process for sublimating and drying the liquid film.

  On the other hand, the other gas supply pipe 95 forming the double pipe structure is connected to the room temperature nitrogen gas supply section 65. The room temperature nitrogen gas supply unit 65 supplies room temperature nitrogen gas, and is a space formed between the blocking member 9 and the surface Wf of the substrate W during the dew condensation prevention process performed after the drying process on the substrate W. The nitrogen gas at room temperature is supplied from the gas supply pipe 95 toward the head. In this embodiment, the room temperature nitrogen gas is supplied from the room temperature nitrogen gas supply unit 65 as the dew condensation preventing gas. However, room temperature air or other inert gas may be supplied. Further, the temperature of the dew condensation preventing gas is not limited to room temperature, and a heated gas as shown in the second embodiment may be used. That is, air at room temperature or higher or an inert gas (including nitrogen gas) can be used as the dew condensation preventing gas.

  Next, the operation of the substrate processing apparatus configured as described above will be described with reference to FIGS. FIG. 4 is a diagram schematically showing the operation of the substrate processing apparatus of FIG. FIG. 5 is a vapor pressure curve of water and ice. In this apparatus, as shown in FIG. 4A, when the substrate is carried in, the blocking member 9 is retracted to a separated position above the spin chuck 2 to prevent interference with the substrate W, and the substrate surface Wf is moved upward. The substrate W on which the surface Wf has been treated with a chemical solution such as hydrofluoric acid is loaded into the apparatus and held by the spin chuck 2.

  When the substrate loading is completed, the DIW discharge nozzle 3 is moved to the rotation center position above the rotation center AO of the substrate W to execute the rinsing process. In this rinsing step, the control unit 4 drives the chuck rotating mechanism 22 to rotate the substrate W together with the spin chuck 2 at 300 rpm, for example, and supplies DIW from the DIW discharge nozzle 3 to the substrate surface Wf for 10 seconds, for example. The DIW supplied to the substrate surface is subjected to a centrifugal force accompanying the rotation of the substrate W, and is uniformly spread outward in the radial direction of the substrate W, so that the rinsing process is performed on the substrate surface Wf. In this embodiment, since lyophilization is performed after the rinsing step, it is preferable to use DIW whose temperature is adjusted to about 0 to 2 ° C. in the rinsing step. This is because when the temperature of the water film is relatively high, the water film evaporates before freezing the water film, resulting in problems such as pattern collapse. Therefore, when the low temperature DIW is used, the temperature of the liquid film 11 on the substrate W and the substrate surface Wf becomes near the freezing point of the DIW, and the pattern collapses by suppressing the liquid film 11 from evaporating before the liquid film 11 is frozen. Risk can be reduced. In addition, the time required for the freezing process described later can be shortened.

  When the rinsing process is completed, the DIW supply from the DIW discharge nozzle 3 is stopped while the substrate W is rotated at 300 rpm, and the DIW discharge nozzle 3 is moved to a retracted position (for example, the position shown in FIG. 9) separated from the substrate W. . Part of DIW on the substrate surface Wf is shaken off to the outside of the substrate W (swing-off process), and a liquid film (water film) 11 having a predetermined thickness is formed on the entire substrate surface Wf (FIG. 4B). . In this embodiment, the thickness of the liquid film is adjusted to about 20 μm by performing the swing-off step. However, the liquid film 11 can be adjusted to an arbitrary value by controlling the rotation speed of the substrate W. it can.

  When the liquid film 11 having a desired thickness is formed in this manner, the rotation of the substrate W is stopped, and the blocking member 9 is lowered to the facing position and is disposed close to the substrate surface Wf. As a result, the substrate surface Wf is covered in the state of being close to the substrate facing surface of the blocking member 9 and is blocked from the ambient atmosphere of the substrate W. Subsequently, a freezing process is executed. That is, nitrogen gas is fed into the gas cooling unit 640 to generate, for example, −60 ° C. freeze-dried nitrogen gas. Then, the freeze-drying nitrogen gas is supplied from the nozzle 97 to the substrate surface Wf. As a result, lyophilization nitrogen gas is supplied to the entire surface Wf of the substrate to freeze the liquid film 11 to form the frozen film 12 (FIG. 4C).

Even after the formation of the frozen film 12, the nitrogen gas for lyophilization is continuously supplied to the substrate surface Wf. Then, the frozen film 12 sublimes with time. This is the same phenomenon as the ice in the freezer gets smaller and smaller. That is, in this embodiment, the temperature at which the nitrogen gas is lowered by the gas cooling unit 640 and the water vapor in the freeze-drying nitrogen gas begins to condense, that is, the dew point is about −60 ° C. As shown in FIG. 5, the partial pressure is reduced to about 1 Pa (7.5 × 10 ⁻³ Torr). On the other hand, the temperature of the frozen membrane 12 is higher than the temperature of the freeze-drying nitrogen gas, and is about −20 ° C. as measured by the inventor of the present application. This is presumably because the back surface of the substrate W faces a normal temperature atmosphere, and the temperature drop of the frozen film 12 is suppressed by heat transfer from the back surface of the substrate to the substrate surface Wf. However, since the freeze-drying nitrogen gas is continuously supplied to the substrate surface Wf, the frozen film 12 does not change to the liquid phase, and the temperature Tg of the freeze-drying nitrogen gas (in this embodiment, −60 °). C) and the temperature Ts (−20 ° C. in this embodiment) between the freezing point of DIW. Therefore, the vapor pressure (sublimation pressure) of the frozen film 12 at the temperature Ts, for example, about 100 Pa at −20 ° C., the partial pressure of water vapor in the freeze-drying nitrogen gas is as low as about 1 Pa as described above. Sublimation evaporation occurs to fill this vapor pressure difference. Moreover, in this embodiment, since the freeze-drying nitrogen gas is continuously supplied, the situation in which the partial pressure of water vapor in the freeze-drying nitrogen gas is lower than the vapor pressure of the frozen film 12 is maintained, and sublimation drying is performed. Progress. In addition, since the water vapor component generated by sublimation is removed from the substrate surface Wf by riding on the freeze-drying nitrogen gas stream, the water vapor component generated by sublimation from the frozen film 12 returns to the liquid phase or solid phase and returns to the substrate surface Wf. Reattachment can be surely prevented. As described above, in the present embodiment, the frozen film 12 is sublimated into the gas phase without passing through the liquid phase in the atmospheric pressure atmosphere and is removed from the substrate surface Wf together with the freeze-drying nitrogen gas to dry the substrate W. (FIG. 4D)).

  At the time when the frozen film 12 is completely removed from the substrate surface Wf and the drying process is completed, the temperature of the substrate W is below the freezing point of DIW, and if the substrate W is carried out in a low temperature state, dew condensation occurs on the entire surface of the substrate. Resulting in. Therefore, in this embodiment, the condensation prevention process is executed after the drying process is completed. In this dew condensation prevention process, the supply of room temperature nitrogen gas from the room temperature nitrogen gas supply unit 65 to the gas supply pipe 95 is started instead of the supply of the lyophilization nitrogen gas from the gas cooling unit 640 being stopped ( FIG. 4 (e)). In this way, the room temperature nitrogen gas is supplied to the substrate surface Wf, whereby the temperature of the substrate W is returned to near the room temperature. For this reason, it is possible to reliably prevent dew condensation on the substrate W. Finally, after the blocking member 9 is retracted to the separation position above the spin chuck 2, the processed substrate W is unloaded from the processing chamber 1.

  As described above, in this embodiment, nitrogen gas for lyophilization at a temperature lower than the freezing point of DIW constituting the frozen film 12 is supplied to the substrate surface Wf to prevent the frozen film 12 from returning to the liquid phase. By setting the dew point of the freeze-drying nitrogen gas to be lower than the temperature of the freeze membrane 12, the partial pressure of water vapor in the freeze-drying nitrogen gas is lowered below the vapor pressure (sublimation pressure) of the freeze membrane 12 to perform sublimation drying. Running. In addition, although the partial pressure of water vapor in the freeze-drying nitrogen gas may increase momentarily due to sublimation drying, since the fresh freeze-drying nitrogen gas is continuously supplied to the substrate surface Wf, the frozen film The partial pressure of water vapor in the freeze-drying nitrogen gas covering 12 is always low, and sublimation drying proceeds. In addition, since the water vapor component generated by sublimation is removed from the substrate surface Wf by riding on the lyophilization nitrogen gas stream, the water vapor component can be reliably prevented from returning to the liquid phase or solid phase and reattaching to the substrate surface Wf. be able to. As described above, the rinsing liquid (DIW) attached to the substrate surface Wf in the atmospheric pressure atmosphere can be satisfactorily removed and the substrate W can be dried.

  As described above, in this embodiment, the room temperature nitrogen gas supply unit 65 and the gas supply pipe 95 function as the “substrate temperature adjusting means” of the present invention to prevent dew condensation on the substrate W. Further, the freeze-drying nitrogen gas supply section 64, the gas supply pipe 96, and the freeze-drying nitrogen gas discharge nozzle 97 function as the “sublimation drying means” of the present invention. Gas ”is supplied to the substrate surface Wf. The freeze-drying nitrogen gas is supplied to the substrate surface Wf after the rinsing process to freeze the liquid film. The freeze-drying nitrogen gas supply unit 64, the gas supply pipe 96, and the freeze-drying nitrogen gas discharge nozzle 97 are used. Also functions as the “freezing means” of the present invention. Of course, as described below, “sublimation drying means” and “freezing means” may be provided separately.

  FIG. 6 is a view showing a substrate processing apparatus equipped with a second embodiment of the substrate drying apparatus according to the present invention, and FIG. 7 is a view schematically showing the operation of the substrate processing apparatus shown in FIG. The second embodiment is greatly different from the first embodiment in the following points. First, while the nitrogen gas supply unit 64, the gas supply pipe 96, and the nitrogen gas discharge nozzle 97 function only as the “sublimation drying means” of the present invention, the “freezing” “Means” are added. This “freezing means” includes a freezing nitrogen gas supply unit (not shown), a gas supply pipe 25, and a freezing nitrogen gas discharge nozzle 27. That is, as shown in FIG. 6, the central axis 21 of the spin chuck 2 is hollow with a cylindrical cavity, and the freezing nitrogen gas is supplied to the back surface Wb of the substrate W inside the central axis 21. A cylindrical gas supply pipe 25 is inserted therethrough. The gas supply pipe 25 extends to a position close to the back surface Wb, which is the lower surface side of the substrate W held by the spin chuck 2, and has a freezing nitrogen gas supply unit at its tip toward the center of the lower surface of the substrate W. A gas discharge nozzle 27 for discharging a freezing nitrogen gas, for example, a nitrogen gas at −20 ° C., is provided. Thus, in the second embodiment, the freezing nitrogen gas corresponds to the “freezing gas” of the present invention, which is lower than the freezing point of DIW and higher than the temperature of the drying nitrogen gas (drying gas). Nitrogen gas for freezing is supplied to the substrate back surface Wf to freeze the liquid film. Therefore, the temperature of the frozen film 12 thus formed is lower than the freezing point of DIW and higher than the dew point of the drying nitrogen gas (drying gas).

  The second difference is that there is provided substrate temperature adjusting means for supplying heated nitrogen gas to the dried substrate W to raise the temperature of the substrate W to the ambient temperature or higher. The “substrate temperature adjusting means” has a heated nitrogen gas supply unit (not shown) for supplying heated nitrogen gas. The heated nitrogen gas supply unit is connected to a gap between the inner wall surface of the central shaft 21 of the spin chuck 2 and the outer wall surface of the gas supply pipe 25, that is, a gas supply path 29 having a ring-shaped cross section. Then, heated nitrogen gas is supplied to the substrate back surface Wb. Thereby, the substrate W is heated to a temperature equal to or higher than room temperature.

  Since the other configuration is basically the same as that of the substrate processing apparatus shown in FIG. 1, the same reference numerals are given in the following description and the description of the configuration is omitted.

  Next, the operation of the second embodiment configured as described above will be described with reference to FIG. Also in the second embodiment, the rinsing process and the swing-off process are performed in the same manner as in the first embodiment. Thereafter, the next freezing step, drying step, and dew condensation prevention step are performed.

  In this freezing step, as shown in FIG. 7A, the freezing nitrogen gas is supplied from the freezing nitrogen gas supply unit while the substrate W is rotated and the blocking member 9 is retracted to the separation position above the spin chuck 2. (For example, −20 ° C.) is supplied from the nozzle 27 to the substrate back surface Wb. As a result, the entire substrate W is cooled and the liquid film (water film) on the substrate surface Wf is frozen. Thus, since the freezing process is performed without supplying the freezing nitrogen gas directly to the liquid film on the substrate surface Wf, it is possible to reliably prevent the liquid film from being dried during the freezing process. . In addition, since the substrate W is not cooled more than necessary as compared with the first embodiment in which the cryogenic nitrogen gas is supplied during the freezing process, the energy efficiency for forming the frozen film 12 can be improved. it can.

  When the liquid film on the substrate surface Wf is frozen, the rotation of the substrate and the supply of the nitrogen gas for freezing are stopped, and the blocking member 9 is lowered to the facing position and is placed close to the substrate surface Wf. As a result, the substrate surface Wf is covered in the state of being close to the substrate facing surface of the blocking member 9 and is blocked from the ambient atmosphere of the substrate W. Subsequently, the drying process is executed in the same manner as in the first embodiment. That is, nitrogen gas is fed into the gas cooling unit 640 to generate, for example, −60 ° C. drying nitrogen gas. Then, the drying nitrogen gas is continuously supplied from the nozzle 97 to the substrate surface Wf. As a result, the frozen film 12 sublimes with time. (FIG. 7B)).

  When the drying process is completed, supply of the freeze-drying nitrogen gas from the gas cooling unit 640 is stopped, and supply of the room temperature nitrogen gas from the room temperature nitrogen gas supply unit 65 to the gas supply pipe 95 is started (FIG. 7). (C)). In the second embodiment, nitrogen gas is supplied not only to the substrate front surface Wf side but also to the substrate back surface Wb side. Moreover, since the nitrogen gas on the back side is heated nitrogen gas supplied from the heated nitrogen gas supply unit, the substrate W is heated to a temperature higher than room temperature. For this reason, it can prevent more reliably that dew condensation generate | occur | produces on the board | substrate W. FIG. Of course, the heated nitrogen gas may also be supplied to the substrate surface Wf side. Finally, after the blocking member 9 is retracted to the separation position above the spin chuck 2, the processed substrate W is unloaded from the processing chamber 1.

  The present invention is not limited to the above-described embodiment, and various modifications other than those described above can be made without departing from the spirit of the present invention. “Freezing means” or “substrate temperature adjusting means” having a configuration different from that employed in the above embodiment may be used. For example, as shown in FIG. 8, a spin base 23 equipped with a heating / cooling mechanism 23a may be used. The spin base 23 corresponds to the “base portion” of the present invention, and the substrate W is brought into direct contact with the upper surface of the spin base 23, or the freezing process is performed with the substrate W placed close to the upper surface of the spin base 23. You may perform a dew condensation prevention process.

  FIG. 8 is a diagram schematically showing the operation of the third embodiment of the substrate drying apparatus according to the present invention. In the third embodiment, the rinsing process and the swing-off process are performed in the same manner as in the first embodiment. Thereafter, the next freezing step, drying step, and dew condensation prevention step are performed.

  In this freezing step, as shown in FIG. 8A, the heating / cooling mechanism 23a built in the spin base 23 is rotated while the substrate W is rotated and the blocking member 9 is retracted to the separation position above the spin base 23. The cooling portion of the spin base 23 operates to cool the spin base 23 to a temperature lower than the freezing point of DIW (lowering of the spin base 23). As a result, the entire substrate W is cooled and the liquid film (water film) on the substrate surface Wf is frozen.

  Thereafter, the rotation of the substrate is stopped, and the blocking member 9 is lowered to the facing position and is disposed close to the substrate surface Wf. The heating / cooling mechanism 23a operates as it is to control the temperature of the substrate W and the frozen film 12 to a temperature lower than the freezing point of DIW and higher than the dew point of the drying nitrogen gas. And a drying process is performed like 1st Embodiment. That is, nitrogen gas is fed into the gas cooling unit 640 to generate, for example, −60 ° C. drying nitrogen gas. Then, the drying nitrogen gas is continuously supplied from the nozzle 97 to the substrate surface Wf. As a result, the frozen film 12 sublimes with time. (FIG. 8B)).

  When the drying process is completed, the supply of the freeze-drying nitrogen gas from the gas cooling unit 640 is stopped. In addition, the heating unit operates to stop and replace the cooling unit of the heating / cooling mechanism 23a to heat the spin base 23 to heat the substrate W to room temperature or higher. For this reason, it can prevent more reliably that dew condensation generate | occur | produces on the board | substrate W. FIG. Finally, after the blocking member 9 is retracted to the separation position above the spin base 23, the processed substrate W is unloaded from the processing chamber 1.

  In the above embodiment, the nitrogen film for drying is continuously supplied from the nozzle 97 to the substrate surface Wf in a state where the blocking member 9 is disposed close to the substrate surface Wf to dry the frozen film 12. For example, FIG. As shown in FIG. 5, the frozen film 12 may be dried by causing the nozzle 5 for discharging the drying nitrogen gas to scan the surface Wf of the rotating substrate W and supplying the drying nitrogen gas to the entire substrate surface Wf. . That is, a rotation motor 51 is provided on the outer side in the circumferential direction of the spin chuck 2 in order to scan the nozzle 5. A rotary shaft 53 is connected to the rotary motor 51, and an arm 55 is connected to the rotary shaft 53 so as to extend in the horizontal direction, and the drying nitrogen gas discharge nozzle 5 is attached to the tip of the arm 55. ing. When the rotary motor 51 is driven in accordance with an operation command from the control unit 4, the arm 55 swings around the rotary shaft 53, and the nozzle 5 moves along the substrate surface Wf.

  In the above embodiment, pure water such as DIW attached to the substrate surface Wf is removed and dried. However, the object to be dried is not limited to DIW, and the same applies to other liquids. Can be removed. Further, the liquid film is not limited, and even a droplet can be similarly removed.

  Furthermore, in the above embodiment, the substrate drying apparatus is incorporated in the substrate processing apparatus, and the substrate after the rinsing process is dried by the substrate drying apparatus. However, the application target of the present invention is not limited to this, and the substrate surface The present invention can be applied to all substrate drying apparatuses that remove the liquid adhering to the substrate and dry the substrate. Further, the present invention can also be applied to an apparatus configured such that a chemical processing means in a pretreatment process is incorporated in a substrate drying apparatus and a series of processing from chemical processing to drying processing is continuously performed in the apparatus.

  The present invention relates to a semiconductor wafer, a glass substrate for photomask, a glass substrate for liquid crystal display, a glass substrate for plasma display, a substrate for FED (Field Emission Display), a substrate for optical disk, a substrate for magnetic disk, a substrate for magneto-optical disk, etc. The present invention can be applied to a substrate drying apparatus and a substrate drying method for drying the entire surface of the substrate including the substrate.

11 ... Liquid film 12 ... Frozen film 23 ... Spin base (base part)
23a ... Heating / cooling mechanism (freezing means, substrate temperature adjusting means)
25 ... Gas supply pipe (freezing means)
27 ... Nitrogen gas discharge nozzle for freezing (freezing means)
64 ... Nitrogen gas supply section (sublimation drying means, freezing means)
65. Room temperature nitrogen gas supply unit (substrate temperature control means)
95 ... Gas supply pipe (substrate temperature control means)
96 ... Gas supply pipe (sublimation drying means, freezing means)
97 ... Nitrogen gas discharge nozzle (sublimation drying means, freezing means)
640 ... Gas cooling unit (sublimation drying means, freezing means)
W ... Substrate Wb ... Substrate back surface Wf ... Substrate surface

Claims (10)

Freezing means for freezing liquid on a substrate surface and forming a frozen body of the liquid on the substrate surface;
Sublimation drying means for continuously supplying a drying gas having a dew point lower than the freezing point of the liquid toward the substrate surface and lowering the temperature of the frozen body to sublimate and dry the frozen body ;
A blocking member having a surface facing the substrate surface having a size equal to or larger than the substrate surface;
Equipped with a,
The substrate drying apparatus, wherein the drying gas is supplied to a space between the substrate surface and the blocking member disposed in proximity to the substrate surface . The blocking member has an opening in the center,
The substrate drying apparatus according to claim 1, wherein the drying gas is supplied to the vicinity of the center of the substrate surface from the opening. 3. The substrate drying apparatus according to claim 1, wherein the freezing unit forms the frozen body at a temperature lower than a freezing point of the liquid and higher than a dew point of the drying gas. 4. The substrate drying apparatus according to claim 3, wherein the freezing means supplies a freezing gas having a temperature lower than a freezing point of the liquid and higher than a dew point of the drying gas to the substrate to freeze the liquid. 4. The substrate drying apparatus according to claim 3 , wherein the freezing means includes a base portion that is in contact with or close to the back surface of the substrate, and a cooling portion that cools the base portion to a temperature lower than a freezing point of the liquid. The substrate drying apparatus according to any one of claims 1 to 5 , further comprising substrate temperature adjusting means for raising the temperature of the frozen body to a temperature higher than an ambient temperature by sublimation drying. After the liquid on the substrate surface is frozen and the frozen body of the liquid is formed on the substrate surface, it has a surface facing the substrate surface that is equal to or larger than the substrate surface and has an opening at the center. A blocking member is disposed close to the substrate surface, and a drying gas having a dew point lower than the freezing point of the liquid and lower than the temperature of the frozen body is continuously supplied from the opening toward the substrate surface. And drying the frozen body by sublimation drying. The substrate drying method according to claim 7 , wherein the liquid is pure water and the drying gas is nitrogen gas. The substrate drying method according to claim 8 , wherein nitrogen gas having a temperature of −60 ° C. is generated and supplied. The substrate drying method according to claim 7, wherein the sublimation drying maintains a state in which a partial pressure of water vapor in the drying gas is lower than a vapor pressure of the frozen body.

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