JP6022829B2 - Substrate drying method and substrate drying apparatus - Google Patents

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 method and a substrate drying apparatus 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, for example, as described in Patent Document 1, a liquid of a sublimation substance adhering to the substrate surface is frozen to form a frozen film (solidified body), and then the liquid is directed toward the substrate surface. The frozen membrane is sublimated and dried by continuously supplying a dry gas having a dew point lower than the freezing temperature and lower than the temperature of the frozen membrane.

JP 2010-199261 A

  Patent Document 1 describes a technical matter in which a frozen film (solidified body) is sublimated and removed from a substrate surface using a dry gas under atmospheric pressure. However, other technical matters have not been sufficiently studied and there is room for improvement. In particular, in the substrate drying technology, it is important to improve the performance of suppressing the collapse of the pattern (hereinafter referred to as “drying performance”) as described above, and the time required for sublimation drying (hereinafter referred to as “sublimation drying time”). Is also important. Therefore, there is a demand for a technique that achieves both an improvement in drying performance and a reduction in sublimation drying time, but technical matters relating to this have not been sufficiently known.

  This invention is made | formed in view of the said subject, and it aims at providing the technique of drying a board | substrate in a short time, having the outstanding drying performance.

In one aspect of the substrate drying method according to the present invention, a sublimation substance solidified body having a thickness not less than the depth of the pattern on the substrate surface on which the pattern is formed has a first temperature lower than the freezing point of the sublimation substance. A first sublimation step of supplying a dry gas to sublimate a sublimation substance constituting the surface layer portion of the solidified body, and a residual portion remaining on the substrate surface after the surface layer portion is removed from the solidified body by the first sublimation step. And a second sublimation step of sublimating a sublimation material constituting the residual portion by supplying a drying gas having a second temperature lower than the first temperature, and the first sublimation step while the solidified body remains in the entire pattern This is a step of sublimating a sublimation material constituting the surface layer portion of the solidified body .

One aspect of a substrate drying apparatus according to the present invention is a substrate holding unit that holds a substrate having a pattern and a surface on which a solidified body of a sublimation substance is formed with a thickness greater than the depth of the pattern, and is held by the substrate holding unit. A first drying gas supply unit that supplies a drying gas having a first temperature below the freezing point of the sublimation substance to the substrate, and a drying gas having a second temperature lower than the first temperature is applied to the substrate held by the substrate holding unit. A second dry gas supply unit for supplying, and a control unit for controlling the first dry gas supply unit and the second dry gas supply unit, wherein the control unit supplies the dry gas at the first temperature to the solidified body. Then, the sublimation material constituting the surface layer portion of the solidified body is sublimated while the solidified body remains on the entire pattern , and the surface layer portion is removed from the solidified body and the remaining portion remaining on the substrate surface is dried at the second temperature. Sublimation material that forms a solidified body by supplying gas It is configured so as to Hana.

  When a solidified body of a sublimation substance is formed with a pattern and a thickness greater than the depth of the pattern on the substrate surface, the solidified body is supplied by supplying a dry gas having a temperature below the freezing point of the sublimation substance to the solidified body. It can be sublimated and removed from the substrate surface. This technical matter is known as described in Patent Document 1, but other technical matters have not been sufficiently known. Therefore, the present inventor conducted an experiment described later to clarify the influence of the temperature of the drying gas on the collapse of the pattern, and obtained the following knowledge. That is the knowledge that the lower the temperature during the sublimation of the solidified body by supplying the drying gas (hereinafter referred to as “temperature during drying”), the higher the drying performance. It was also found that the sublimation drying time becomes longer as the drying temperature is lowered. Therefore, improvement in drying performance and reduction in sublimation drying time are in a trade-off relationship with each other.

  Therefore, in the present invention, when the surface layer portion of the solidified body is removed, a dry gas having a relatively high temperature (first temperature) is supplied to the solidified body. For this reason, the surface layer portion is sublimated and dried in a short time. During this time, since the solidified body other than the surface layer portion, that is, the remaining portion remains in the pattern, the collapse of the pattern is effectively prevented. Then, after sublimation drying of the surface layer portion, a drying gas having a relatively low temperature (second temperature) is supplied to the remaining portion, and the remaining portion is sublimated and dried with excellent drying performance. Therefore, according to the present invention, compared with the case where the solidified body is sublimated and dried using only a relatively low temperature drying gas in order to obtain excellent drying performance, the time required for sublimation drying of the surface layer portion is shortened, The time required for sublimation drying of the entire solidified body, that is, the sublimation drying time is shortened.

  Here, before the surface layer portion is sublimated and dried (first sublimation step), the liquid of the sublimation substance adhering to the substrate surface may be cooled to form a solidified body thicker than the pattern depth on the substrate surface. . In this case, even if the formation process of the solidified body is slightly changed, it is possible to reliably prevent the solidified body before sublimation drying from being thinner than the depth of the pattern, that is, the top of the pattern is exposed from the solidified body. it can. As a result, excellent drying performance can be ensured more reliably. In addition, although the formation aspect of a solidified body is arbitrary, it is desirable to supply a refrigerant | coolant to the board | substrate back surface opposite to the substrate surface especially, and to form a solidified body. Thereby, the solidified body formed on the substrate surface can be stably formed, and the subsequent sublimation drying can also be performed stably.

  Further, as described above, when the solidified body is thicker than the depth of the pattern, it is preferable that the remaining portion has the same thickness as the depth of the pattern by performing sublimation drying of the surface layer portion. As a result, the time required for sublimation drying can be effectively shortened while the remaining portion remains in the entire pattern.

  Furthermore, after the solidified body is sublimated and dried, it is desirable to heat the substrate by supplying a gas having a temperature higher than the freezing point of the sublimation substance to the substrate, thereby preventing condensation on the substrate.

  As described above, according to the present invention, when the solidified body formed on the substrate surface with a thickness greater than the depth of the pattern is sublimated and dried, the temperature of the drying gas used in the surface layer portion and the remaining portion is switched. . That is, while the drying gas having a relatively high temperature (first temperature) is used for the surface layer portion that has little influence on the pattern collapse, the remaining portion that has a significant influence on the pattern collapse has a relatively low temperature (the second temperature). (Dry temperature). Therefore, the drying time of the substrate can be shortened while suppressing pattern collapse.

It is a graph which shows the relationship between the temperature at the time of drying, and a collapse rate. 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 flowchart which shows operation | movement of the substrate processing apparatus of FIG. It is a figure which shows typically operation | movement of the substrate processing apparatus of FIG. 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 block diagram which shows the control structure of the substrate processing apparatus of FIG. It is a figure which shows typically operation | movement of the substrate processing apparatus of FIG. It is a figure which shows typically operation | movement of the substrate processing apparatus of FIG. It is a figure which shows the substrate processing apparatus equipped with 3rd Embodiment of the substrate drying apparatus concerning this invention.

A. FIG. 1 is a graph showing the relationship between the temperature during drying and the collapse rate. The present inventor conducted the following experiment in order to investigate the influence of the temperature during drying on the collapse rate of the pattern when performing sublimation drying using a drying gas under atmospheric pressure. In the experiment, DIW was used as a sublimation substance, nitrogen gas of “0 [° C.]”, “−20 [° C.]” and “−40 [° C.]” was used as a dry gas, and the following steps (a ) To (e),
(a) forming a line and space pattern on the substrate surface;
(b) forming a liquid film of a liquid of sublimation material on the substrate surface;
(c) freezing the liquid film to form a frozen film (coagulum);
(d) supplying nitrogen gas to the frozen membrane and performing sublimation drying;
(e) measuring the pattern collapse rate on the substrate surface;
Went. The temperature at the time of drying substantially matches the temperature of nitrogen gas. The collapse rates at drying temperatures of 0 [° C], -20 [° C], and -40 [° C] were 90 [%], 94 [%], and 55 [%], respectively, and the measured data were plotted. The thing is a solid line in FIG.

  Further, tertiary butanol is used as a sublimation substance, and nitrogen gas of “0 [° C.]”, “−20 [° C.]”, and “−30 [° C.]” is used as a drying gas at each temperature. A drying treatment was performed in the above steps (a) to (e). As a result, the collapse rates at drying temperatures of 0 [° C.], −20 [° C.], and −30 [° C.] are 90 [%], 71 [%], and 9 [%], respectively. Is a broken line in FIG.

  As is apparent from FIG. 1, when performing sublimation drying while keeping the temperature during drying constant, the lower the temperature during drying, the more effectively the collapse of the pattern can be suppressed. That is, in order to improve the drying performance, it is preferable to set the temperature of the drying gas low. On the other hand, by using a low-temperature drying gas, the temperature during drying is lowered, and the sublimation drying time is lengthened. Thus, improvement in drying performance and reduction in sublimation drying time are in a trade-off relationship with each other.

  Here, during the sublimation drying, the sublimation substance gradually sublimates from the surface layer portion of the frozen membrane that comes into contact with the drying gas. Therefore, while sublimation drying of the surface layer portion is performed, the lower layer side than the surface layer portion is a residual portion where the sublimation material remains in a solidified state in the pattern, and the collapse of the pattern is effectively prevented by the presence of the residual portion. It is possible to prevent. Therefore, even if the surface layer portion is sublimated and dried using a drying gas having a relatively high temperature, that is, a temperature close to the freezing point, the time required for sublimation drying of the surface layer portion can be shortened without causing a decrease in drying performance. it can. On the other hand, when sublimation drying of the surface layer portion is completed, sublimation of the sublimation material constituting the remaining portion is started next, so it is necessary to reduce the temperature of the drying gas to improve the drying performance.

  Based on such considerations, the present inventor is effective to switch the temperature of the drying gas during sublimation drying of the frozen film (solidified body) in order to dry the substrate in a short time while having excellent drying performance. The conclusion that there is. Specifically, after the surface layer portion is sublimated and dried using a drying gas having a relatively high temperature (first temperature), the remaining portion is dried using a drying gas having a lower temperature (second temperature) than the drying gas. It was concluded that the above-mentioned purpose can be achieved by sublimation drying.

  Therefore, in the present invention, the substrate is dried in a short time while having excellent drying performance by configuring the substrate drying method and apparatus as follows based on the above knowledge and conclusion. Hereinafter, embodiments will be described in detail with reference to the drawings.

B. First Embodiment FIG. 2 is a view showing a substrate processing apparatus equipped with a first embodiment of a substrate drying apparatus according to the present invention, and FIG. 3 is a block diagram showing a control configuration of the substrate processing apparatus of FIG. . This substrate processing apparatus 100 is a single-wafer type substrate processing apparatus for rinsing the surface Wf of a substrate W such as a semiconductor wafer. After the rinsing process, the substrate W is dried by sublimating DIW as a sublimation substance.

  The substrate processing apparatus 100 includes a processing chamber 101 having a processing space for rinsing the substrate W therein, and a control unit 104 for controlling the entire apparatus. In the processing chamber 101, as shown in FIG. 2, a spin chuck 102, a DIW discharge nozzle 103, and a blocking member 109 are provided. The spin chuck 102 rotates the substrate W in a state where the surface Wf of the substrate W is held in a substantially horizontal posture with the surface Wf facing upward. The DIW discharge nozzle 103 is connected to the liquid supply unit 162. When the control unit 104 opens an opening / closing valve (not shown), DIW is pumped from the liquid supply unit 162 as a rinse liquid to the DIW discharge nozzle 103 and discharged toward the surface Wf of the substrate W held by the spin chuck 102. . The blocking member 109 is disposed above the spin chuck 102 so as to face the surface Wf of the substrate W held by the spin chuck 102.

  A disc-shaped spin base 123 is fixed to an upper end portion of the central shaft 121 of the spin chuck 102 by a fastening component such as a screw. The central shaft 121 is connected to a rotation shaft of a chuck rotation mechanism 122 including a motor. When the chuck rotating mechanism 122 is driven in accordance with an operation command from the control unit 104, the spin base 123 fixed to the central shaft 121 rotates about the rotational central axis A0.

  The central shaft 121 of the spin chuck 102 is a hollow shaft. A gas supply pipe 125 for supplying the freezing nitrogen gas to the back surface Wb of the substrate W is inserted into the center shaft 121. The gas supply pipe 125 extends to a position close to the lower surface (back surface Wb) of the substrate W held by the spin chuck 102, and the lower surface discharges freezing nitrogen gas toward the center of the lower surface of the substrate W at the tip thereof. A nozzle 127 is provided.

  Near the peripheral edge of the spin base 123, a plurality of chuck pins 124 for holding the peripheral edge of the substrate W are provided upright. Three or more chuck pins 124 may be provided to securely hold the circular substrate W, and are arranged at equiangular intervals along the peripheral edge of the spin base 123. Each of the chuck pins 124 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 124 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 123, each chuck pin 124 is set in a released state, and when the rinse process is performed on the substrate W, each chuck pin 124 is set in a pressed state. When each chuck pin 124 is in a pressed state, each chuck pin 124 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 123. 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 131 is provided on the outer side in the circumferential direction of the spin chuck 102 as a driving source for scanning the DIW discharge nozzle 103. A rotary shaft 133 is connected to the rotary motor 131, and an arm 135 is connected to the rotary shaft 133 so as to extend in the horizontal direction. The DIW discharge nozzle 103 is attached to the tip of the arm 135. When the rotary motor 131 is driven in accordance with an operation command from the control unit 104, the arm 135 swings around the rotary shaft 133.

  The blocking member 109 is formed in a disc shape having an opening at the center. The lower surface of the blocking member 109 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 109 is attached substantially horizontally to the lower end portion of the support shaft 191 having a substantially cylindrical shape. The support shaft 191 is held by an arm 192 extending in the horizontal direction. Further, the arm 192 is connected with a blocking member lifting mechanism 194, and the blocking member 109 is brought close to the spin base 123 or separated from the spin base 123 according to an operation command from the control unit 104. Specifically, the control unit 104 controls the operation of the blocking member lifting mechanism 194 to move the blocking member 109 apart above the spin chuck 102 when the substrate processing apparatus 100 loads and unloads the substrate W. While the substrate W is raised to the position (the position shown in FIG. 2), when the substrate W is subjected to a coagulation process, a sublimation drying process, and a dew condensation prevention process described later, the blocking member 109 of the substrate W held by the spin chuck 102 is Lower to an opposing position set very close to the surface Wf.

  The support shaft 191 is hollow, and a gas supply pipe 195 is inserted into the support shaft 191 and the gas supply pipe 196 is inserted into the gas supply pipe 195 to form a so-called double pipe structure. Both gas supply pipes 195 and 196 are connected to the nitrogen gas supply mechanism 105, and normal temperature nitrogen gas and sublimation drying nitrogen gas are supplied from the nitrogen gas supply mechanism 105 to the gas supply pipes 195 and 196, respectively. .

  As shown in FIG. 3, the nitrogen gas supply mechanism 105 receives room temperature nitrogen gas from a room temperature nitrogen gas supply source 151, which is one of the utilities of the factory where the substrate processing apparatus 100 is installed, via a pipe 152. The pipe 152 is connected to the upper end of the gas supply pipe 195, and another pipe 153 is branched in the middle of the pipe 152 and connected to the dehumidifying unit 154.

  The dehumidifying unit 154 cools the room temperature nitrogen gas supplied from the room temperature nitrogen gas supply source 151 to remove moisture contained in the nitrogen gas and lowers the dew point. More specifically, the dehumidifying unit 154 has a container (not shown) having a tank structure. The container is provided with a liquid nitrogen inlet for taking in liquid nitrogen, and liquid nitrogen is introduced into the container from the liquid nitrogen supply unit 107 via the inlet. Inside the container, a coiled heat exchange pipe formed of a metal tube such as stainless steel or copper is provided as a gas passage. The heat exchange pipe is immersed in liquid nitrogen stored in a container, and normal temperature nitrogen gas is supplied from the normal temperature nitrogen gas supply source 151 through the piping 152 and the piping 153. As a result, the room temperature nitrogen gas is cooled by liquid nitrogen, and the moisture contained in the nitrogen gas is trapped as frost on the inner surface of the heat exchange pipe, and the dew point of the nitrogen gas is lowered to the dew point equivalent to the temperature of liquid nitrogen. In this way, the nitrogen gas having a low dew point is supplied to the three temperature adjusting units 155 to 157.

  Each of the temperature adjusting units 155 to 157 has a thermostat (not shown), and adjusts the temperature of the nitrogen gas cooled to a temperature close to the temperature of liquid nitrogen by the dehumidifying unit 154 to a desired temperature. That is, the temperature adjusting unit 155 has a temperature of nitrogen gas supplied from the dehumidifying unit 154 that is equal to or lower than the freezing point of DIW, and a temperature T1 suitable for the first sublimation process for sublimating and drying the surface layer portion of the frozen film (coagulated body). Adjust to [℃]. In the temperature adjustment unit 155, the constant temperature liquid stored in the constant temperature bath is controlled to a constant temperature by a temperature adjustment element such as a Peltier element. In addition, a coiled heat exchange pipe formed of a metal pipe such as stainless steel or copper is provided as a gas passage inside the thermostatic bath, and is immersed in a temperature-controlled thermostatic liquid. And nitrogen gas is supplied to the heat exchange pipe from the dehumidification part 154, and heat exchange is carried out between constant temperature liquids. Thereby, nitrogen gas is adjusted to 1st temperature T1, and nitrogen gas is supplied to the upper end part of the gas supply pipe | tube 196 as nitrogen gas for 1st sublimation drying.

  Further, the temperature adjusting unit 156 lowers the temperature of the nitrogen gas supplied from the dehumidifying unit 154 to a temperature T1 suitable for the first sublimation process, and performs a second sublimation process for sublimating and drying the remaining part of the frozen film (solidified body). The temperature is adjusted to T2 [° C.] suitable for the temperature. The thermostat of the temperature adjuster 156 is also configured in the same manner as the temperature adjuster 155, and heat exchange is performed between the nitrogen gas from the dehumidifier 154 and the thermostat stored in the thermostat. Thereby, nitrogen gas is adjusted to 2nd temperature T2, and it supplies to the upper end part of the gas supply pipe | tube 196 as nitrogen gas for 2nd sublimation drying.

  Further, the temperature adjusting unit 157 adjusts the temperature of the nitrogen gas supplied from the dehumidifying unit 154 to a freezing temperature that is equal to or lower than the freezing point of DIW and suitable for the solidifying process for freezing the rinse liquid. The thermostat of the temperature adjuster 157 is also configured in the same manner as the temperature adjuster 155, and nitrogen gas from the dehumidifier 154 is heat exchanged with the thermostat stored in the thermostat. As a result, the nitrogen gas is adjusted to the freezing temperature and supplied to the lower end of the gas supply pipe 125 as the freezing nitrogen gas. In the present embodiment, an independent temperature adjustment unit 157 is provided to generate the freezing nitrogen gas. However, the first sublimation drying nitrogen gas and the second sublimation drying nitrogen gas are used as the freezing nitrogen gas. You may comprise as follows.

  Returning to FIG. 2, the description will be continued. A lower end portion of the gas supply pipe 196 extends to the opening of the blocking member 109, and a nitrogen gas discharge nozzle 197 for sublimation drying is provided at the tip thereof. Then, as will be described next, low-temperature sublimation drying nitrogen gas is supplied toward the substrate surface Wf in the coagulation process for freezing the liquid film and the sublimation drying process for sublimating and drying the liquid film.

  On the other hand, the other gas supply pipe 195 forming the double pipe structure is connected to the room temperature nitrogen gas supply source 151 via the pipe 152 as described above. Then, during the dew condensation prevention process performed after the sublimation drying process for the substrate W, the room temperature nitrogen gas is supplied from the gas supply pipe 195 toward the space formed between the blocking member 109 and the surface Wf of the substrate W. In this embodiment, the room temperature nitrogen gas is supplied from the room temperature nitrogen gas supply source 151 as the dew condensation preventing gas, but 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 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. This also applies to later embodiments.

  In the substrate processing apparatus 100 configured as described above, according to a program stored in a memory (not shown) of the control unit 104, the control unit 104 controls each part of the apparatus as described below to execute a series of processes. To do. Hereinafter, the operation of the substrate processing apparatus 100 will be described with reference to FIGS. 4 and 5.

  FIG. 4 is a flowchart showing the operation of the substrate processing apparatus of FIG. FIG. 5 is a diagram schematically showing the operation of the substrate processing apparatus of FIG. In the substrate processing apparatus 100 of FIG. 2, when the substrate is carried in, the blocking member 109 is retracted to a spaced position above the spin chuck 102 to prevent interference with the substrate W, and the substrate surface Wf is directed upward. The substrate W whose surface Wf has been treated with a chemical solution such as hydrofluoric acid is carried into the apparatus and held by the spin chuck 102. Then, the control unit 104 reads out and sets the recipe selected by the user or operator from the memory (not shown) (step S11), and sets various control data (rotation parameters such as the number of rotations and rotation time of the substrate) defined by the recipe. , A rinsing process, a sublimation drying process, and a dew condensation prevention process are performed on the substrate W by controlling each part of the apparatus based on the flow rate of DIW, the temperature T1, T2, etc.

  After the substrate W is loaded, the chuck rotating mechanism 122 is driven to rotate the spin chuck 102, and the rotation motor 131 is driven to move the DIW discharge nozzle 103 to the rotation center position above the rotation center AO of the substrate W. The control unit 104 opens a valve (not shown) of the liquid supply unit 162, supplies DIW from the DIW discharge nozzle 103 to the substrate surface Wf, and performs a rinsing process (step S12).

  When the rinsing process is completed, the control unit 104 closes the valve of the liquid supply unit 162 while stopping the substrate W, and stops the DIW supply from the DIW discharge nozzle 103. Further, the rotary motor 131 is driven to move the DIW discharge nozzle 103 to a retracted position separated from the substrate W. A part of DIW on the substrate surface Wf is shaken out of the substrate W, and as shown in FIG. 5A, a liquid film (DIW film) 11 is formed on the substrate surface Wf. In this embodiment, the control unit 104 controls the rotation speed of the substrate W to adjust the thickness so that the thickness H1 of the liquid film 11 exceeds the depth of the pattern 12 on the substrate surface Wf, that is, the height H2. (Step S13).

  When the liquid film having the desired thickness H1 is formed, the rotation of the substrate W is stopped, and the blocking member 109 is lowered to the opposing position and is disposed close to the substrate surface Wf. As a result, the substrate surface Wf is covered in a state of being close to the substrate facing surface of the blocking member 109 and is blocked from the ambient atmosphere of the substrate W. Subsequently, a coagulation process is executed. That is, the nitrogen gas supply mechanism 105 sends the room temperature nitrogen gas supplied from the room temperature nitrogen gas supply source 151 to the dehumidifying unit 154 to generate the low dew point nitrogen gas. The nitrogen gas supply mechanism 105 further sends low dew point nitrogen gas to the temperature adjustment unit 157 to raise the temperature to a temperature suitable for freezing of the liquid film 11 to generate freezing nitrogen gas. The freezing nitrogen gas is supplied to the lower end portion of the gas supply pipe 125 and supplied from the lower surface nozzle 127 to the substrate back surface Wb. As a result, as shown in FIG. 5B, the liquid film 11 on the substrate surface Wf is frozen to form a frozen film 13 (coagulation step: step S14).

  After the formation of the frozen film 13, the nitrogen gas supply mechanism 105 stops supplying the freezing nitrogen gas and sends a low dew point nitrogen gas to the temperature adjustment unit 155 to be suitable for sublimation drying of the surface layer part 13 a of the frozen film 13. The temperature is raised to the first temperature T1 to generate the first sublimation drying nitrogen gas. The first sublimation drying nitrogen gas is supplied to the upper end of the gas supply pipe 196 and supplied from the gas discharge nozzle 197 to the substrate surface Wf. As a result, as shown in FIG. 5B, DIW is gradually sublimated from the surface layer portion 13a of the frozen film 13 on the substrate surface Wf (first sublimation step: step S15). At this time, since the water vapor component generated by sublimation is removed from the substrate surface Wf by riding on the first sublimation drying nitrogen gas stream, the water vapor component generated by sublimation from the frozen film 13 returns to the liquid phase or solid phase. Reattachment to the surface Wf can be reliably prevented. As the sublimation drying progresses, the frozen film 13 becomes gradually thinner. In the figure, the alternate long and short dash line indicates the initial surface level of the frozen film 13.

  When a predetermined time has elapsed from the start of the sublimation drying process (first sublimation process) using the first nitrogen gas for sublimation drying (“YES” in step S16), the thickness of the frozen film 13 is the depth (height) H2 of the pattern 12 And the surface of the frozen film 13 is flush with the top of the pattern 12 as shown in FIG. Therefore, in the present embodiment, the predetermined time is obtained for each recipe based on experiments and verifications in advance and stored in the memory of the control unit 104. The control unit 104 reads the time corresponding to the recipe as the predetermined time, and switches to the sublimation drying process (second sublimation process) using the second sublimation drying nitrogen gas based on the passage of time. That is, at this timing, the nitrogen gas supply mechanism 105 stops supplying the first sublimation drying nitrogen gas and ends the sublimation drying of the surface layer portion 13a of the frozen film 13. At this point, the frozen film 13 having the thickness H2 remains on the substrate surface Wf, which is referred to as “residual portion 13b”, and the description of the second sublimation process will be continued.

  When the supply of nitrogen gas for the first sublimation drying is stopped and replaced, the nitrogen gas supply mechanism 105 sends the low dew point nitrogen gas to the temperature adjustment unit 156 to raise the temperature to T2 (<T1) suitable for sublimation drying of the residual portion 13b. To generate nitrogen gas for second sublimation drying. The second sublimation drying nitrogen gas is supplied to the substrate surface Wf in the same manner as the first sublimation drying nitrogen gas, and DIW is gradually sublimated from the remaining portion 13b as shown in FIG. 2 Sublimation step: Step S17). Also. The water vapor component generated by the sublimation is removed from the substrate surface Wf by riding on the second sublimation drying nitrogen gas stream.

  When the sublimation drying is completed, the control unit 104 supplies the room temperature nitrogen gas to the substrate surface Wf instead of stopping the supply of the second sublimation drying nitrogen gas to return the temperature of the substrate W to near the room temperature (condensation prevention). Process: Step S18). As a result, it is possible to reliably prevent condensation on the substrate W. The dew condensation prevention step corresponds to the “substrate heating step” of the present invention, but is not an essential step in the substrate drying process, and may be appropriately employed as necessary. Finally, after the blocking member 109 is retracted to the separation position above the spin chuck 102, the processed substrate W is unloaded from the processing chamber 101.

  As described above, when removing the surface layer portion 13a of the frozen film 13, that is, in the first sublimation step, the first sublimation drying nitrogen gas having a relatively high temperature T1 is left with the residual portion 13b remaining in the pattern 12. Since it is used as a drying gas, the surface layer portion 13a can be sublimated and dried in a short time without causing pattern collapse. Then, when the surface layer portion 13a is sublimated and dried and the remaining portion 13b has the same thickness as the pattern 12, the drying gas is switched to the second sublimation drying nitrogen gas having a temperature lower than that of the first sublimation drying nitrogen gas. Sublimation drying of the remaining part 13b is performed. For this reason, the remaining part can be sublimated and dried with excellent drying performance. In addition, compared with the case where the frozen film 13 is sublimated and dried using only a drying gas having a relatively low temperature, the time required for the sublimation drying of the frozen film 13 is reduced by the amount of time required for the sublimation drying of the surface layer portion 13a. Can be shortened.

  In the present embodiment, the frozen film 13 thicker than the depth of the pattern 12 is formed on the substrate surface Wf. Therefore, even if various processes executed in the coagulation step are slightly changed, the frozen film 13 before sublimation drying becomes thinner than the depth of the pattern 12, that is, the top of the pattern 12 is exposed from the frozen film 13. It can be surely prevented.

  Further, the frozen film 13 is formed by supplying freezing nitrogen gas as a refrigerant to the back surface Wb of the substrate. That is, the liquid film 11 is solidified without directly supplying the coolant to the liquid film 11. Therefore, it is possible to prevent the liquid film 11 from being disturbed by the refrigerant during the solidification process, and the frozen film 13 having a uniform thickness can be stably formed over the entire substrate surface Wf. As a result, sublimation drying can be performed stably, and more excellent drying performance can be obtained.

  In the first embodiment, the surface layer portion 13a is sublimated and dried so that the residual portion 13b has the same thickness H2 as the depth of the pattern 12. However, the technical matter is an essential component of the present invention. is not. It suffices if the residual portion 13b remains between the patterns 12 to the extent that the pattern 12 is prevented from collapsing when the temperature of the drying gas is switched. Therefore, even if the thickness of the frozen film 13 formed by the solidification process is the same as the depth of the pattern 12, the present invention can be applied.

C. Second Embodiment In the first embodiment, DIW is used as the rinse liquid and the sublimation substance, but other substances such as carbon dioxide can be used. However, when carbon dioxide is used, pressure control in the processing chamber becomes practically inevitable in order to form a solidified body. Hereinafter, the second embodiment will be described in detail with reference to FIGS.

  FIG. 6 is a diagram 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 block diagram showing a control configuration of the substrate processing apparatus of FIG. The substrate processing apparatus 300 mainly includes a processing chamber 310, a carbon dioxide supply mechanism 320, a first nitrogen gas supply mechanism 330, a liquid nitrogen supply mechanism 340, a second nitrogen gas supply mechanism 440, and a discharge mechanism 350. Then, after rinsing the surface Wf of the substrate W such as a semiconductor wafer with carbon dioxide, the substrate processing apparatus 300 sublimates the carbon dioxide as a sublimation substance to dry the substrate W.

  The processing chamber 310 includes a cylindrical upper member 313 and a disk-shaped lower member 314. Among these, the upper member 313 is a structure in which a circular upper wall 311 and a side wall 312 provided around the upper wall 311 are integrated, and has an opening that opens downward (−Z). ing. On the other hand, the lower member 314 has a lower wall 316 arranged on the lower side of the opening of the upper member 313, and constitutes an internal space of the processing chamber 310 by closing the opening. Further, the upper surface of the lower wall 316, that is, the surface that defines the bottom surface of the internal space of the processing chamber 310 is inclined. The upper member 313 and the lower member 314 configured as described above are configured to be able to move relative to each other in the up-down direction Z while coming into contact with and away from each other.

  Then, the chamber opening / closing mechanism 317 (FIG. 7) operates to open the processing chamber 310 in response to a chamber opening command from the control unit 500 (FIG. 7) that controls the entire apparatus, and the substrate W is loaded into the processing chamber 310. In addition, the substrate W can be unloaded from the processing chamber 310. On the other hand, the chamber opening / closing mechanism 317 is operated in response to a chamber closing command from the control unit 500 to close the processing chamber 310, so that the upper member 313 and the lower member 314 are in close contact with each other via the sealing material 315. The process chamber 310 is sealed. A rinsing process and a sublimation drying process are performed inside the process chamber 310 thus sealed.

  Inside the processing chamber 310, a mounting table 390 for mounting the substrate W is provided. The substrate W is held in a substantially horizontal state by being mounted on the upper surface of the mounting table 390. A suction port (not shown) is provided on the upper surface of the mounting table 390, and the substrate W is held on the mounting table 390 by sucking the lower surface of the substrate W on which the suction port is mounted. In addition, the holding | maintenance aspect of the board | substrate W is not limited to this, For example, you may hold | maintain by a mechanical chuck system.

  A support shaft 360 protrudes downward (−Z) from the center of the lower surface of the mounting table 390. The support shaft 360 is inserted into the lower member 314 via a high pressure seal rotation introducing mechanism 370. Further, the rotating shaft 371 of the high pressure seal rotation introducing mechanism 370 is connected to the rotating mechanism 372. For this reason, when the rotation mechanism 372 operates according to the rotation command from the control unit 500, the mounting table 390 that holds the substrate W rotates around the support shaft 360 at an arbitrary number of rotations.

  A first introduction pipe 400 is attached to the processing chamber 310. More specifically, as shown in FIG. 6, the first introduction pipe 400 is attached so as to penetrate the upper wall 311 of the upper member 313, and its lower end is connected to the internal space of the processing chamber 310. On the other hand, the upper end of the first introduction pipe 400 is divided into a T-shape, one of which is connected to the carbon dioxide supply mechanism 320 and the other is connected to the first nitrogen gas supply mechanism 330. Among these, the carbon dioxide supply mechanism 320 includes a carbon dioxide supply part 321 that supplies carbon dioxide gas, a pipe 322 that connects the carbon dioxide supply part 321 to one of the upper ends of the first introduction pipe 400, and the pipe 322. And a valve 323 interposed therebetween. The first nitrogen gas supply mechanism 330 includes a first nitrogen gas supply unit 331 that supplies nitrogen gas, and a pipe 332 that connects the first nitrogen gas supply mechanism 330 to the other of the upper end portions of the first introduction pipe 400. And a valve 333 inserted in the pipe 332. As described above, in the present embodiment, the first introduction pipe 400 functions as two common introduction pipes. That is, the first introduction pipe 400 functions as an introduction path for introducing the carbon dioxide gas supplied from the carbon dioxide supply mechanism 320 into the processing chamber 310, and the room temperature nitrogen gas supplied from the first nitrogen gas supply mechanism 330 is used. It also functions as an introduction path for introduction into the processing chamber 310.

  When the valves 323 and 333 enter the “open state” and the “closed state”, respectively, according to the valve opening / closing command from the control unit 500, the carbon dioxide gas from the carbon dioxide supply unit 321 passes through the first introduction pipe 400. To the processing chamber 310. As will be described later, since the processing chamber 310 is hermetically sealed during sublimation drying, carbon dioxide is accumulated in the processing chamber 310 due to accumulation of the introduced carbon dioxide gas soon after the introduction of carbon dioxide gas is started. The pressure becomes higher than the pressure to condense. For this reason, carbon dioxide is supplied into the processing chamber 310 in a very early stage, but liquid carbon dioxide is soon supplied onto the substrate W. In other words, the initial stage of supplying carbon dioxide is a stage of increasing the pressure in the processing chamber 310 by the gaseous carbon dioxide, and thereafter, the stage of supplying liquid carbon dioxide. In this embodiment, carbon dioxide supplied from the carbon dioxide supply unit 321 is used as a rinsing substance for rinsing and removing a processing solution such as IPA (isopropyl alcohol) from the substrate W according to the principle described later. However, it also functions as a sublimation substance used for sublimation drying.

  On the other hand, when the valves 323 and 333 enter the “closed state” and the “open state”, respectively, according to the valve opening / closing command from the control unit 500, nitrogen gas is supplied from the first nitrogen gas supply mechanism 330 through the first introduction pipe 400. To the processing chamber 310. The first nitrogen gas supply mechanism 330 is configured in the same manner as the nitrogen gas supply mechanism 105 of the first embodiment, and generates and selects room temperature nitrogen gas, first sublimation drying nitrogen gas, and second sublimation drying nitrogen gas. Supply is possible.

  The liquid nitrogen supply mechanism 340 includes a second introduction pipe 341, a liquid nitrogen supply unit 342, a pipe 345, and a valve 343. The second introduction pipe 341 passes through the lower wall 316 of the lower member 314, and its upper end extends to the inside of the processing chamber 310. One end of the second introduction pipe 341 inside the processing chamber 310 faces the lower surface of the mounting table 390. The other end of the second introduction pipe 341 is connected to the liquid nitrogen supply unit 342 by a pipe 345, and a valve 343 is inserted into the pipe 345. For this reason, when the valve 343 is opened in response to a valve opening command from the control unit 500, liquid nitrogen is supplied into the processing chamber 310 from the second introduction pipe 341.

  Further, in the lower member 314 constituting the processing chamber 310, the third introduction pipe 441 penetrates the lower member 314 and the upper end portion extends to the inside of the processing chamber 310, similarly to the second introduction pipe 341. ing. The third introduction pipe 441 constitutes a second nitrogen gas supply mechanism 440 together with the third introduction pipe 441, the second nitrogen gas supply unit 442, the heater 444, the valve 443, and the pipe 445. That is, one end of the third introduction pipe 441 inside the processing chamber 310 faces the lower surface of the mounting table 390. The other end of the third introduction pipe 441 is connected to the second nitrogen gas supply unit 442 by a pipe 445. Further, a heater 444 and a valve 443 are inserted from the second nitrogen gas supply unit 442 side into the pipe 445. In the second nitrogen gas supply mechanism 440 configured as described above, the temperature of the nitrogen gas supplied from the second nitrogen gas supply unit 442 is raised by the heater 444. Then, as the valve 443 is opened in response to the valve opening command from the control unit 500, the high-temperature nitrogen gas heated by the heater 444 is supplied into the processing chamber 310. Note that the second nitrogen gas supply unit 442 and the first nitrogen gas supply unit 331 can be combined into one.

  A fluid dispersion mechanism 380 is provided above the inside of the processing chamber 310. The fluid dispersion mechanism 380 is provided with a plurality of flow holes 382 penetrating vertically with respect to a disk-shaped closing plate 381 fitted inside the processing chamber 310. Thereby, carbon dioxide and nitrogen gas supplied to the processing chamber 310 via the first introduction pipe 400 are rectified, and uniform fluid supply to the upper surface of the substrate W is possible.

  A discharge mechanism 350 is connected to the lower member 314 constituting the processing chamber 310. The discharge mechanism 350 includes a plurality of discharge pipes 351, pipes 354, and valves 353. In the present embodiment, as shown in FIG. 6, a plurality of inclined surfaces are formed on the upper surface of the lower member 314, and a trough portion formed by these inclined surfaces, that is, the uppermost surface in the vertical direction Z. The upper end portion of each discharge pipe 351 communicates with the lowest position. For this reason, the liquid that has flowed down from the substrate W is collected in the valley along the inclined surface of the lower member 314, and is discharged out of the processing chamber 310 through the discharge pipe 351. Further, the gas in the processing chamber 310 can also be discharged out of the processing chamber 310 via the discharge pipe 351.

  The liquid and gas discharged from the processing chamber 310 through the discharge pipe 351 are reduced in pressure by passing through the valve 353, then sent to the separation tank 355, and separated into liquid and gas in the separation tank 355. Then, the separated gas and liquid are sent to a predetermined device so as to be reused or reprocessed, respectively.

  A temperature sensor 610 (FIG. 7) and a pressure sensor 620 (FIG. 7) are provided in the processing chamber 310, and the temperature and pressure in the processing chamber 310 can be measured by these sensors 610 and 620, respectively. Yes. The temperature data and pressure data measured by these sensors 610 and 620 are input to the control unit 500. The control unit 500 can adjust the temperature and pressure in the processing chamber 310 by adjusting the opening and closing of the valves 323, 333, 343, 443, and 353 according to these measurement results. The configuration of the control unit 500 as hardware is the same as that of a general computer, and is controlled by controlling each part of the substrate processing apparatus 300 according to a program stored in advance in a memory (not shown). The substrate W is sublimated and dried by executing the series of operations. Hereinafter, the operation of the substrate processing apparatus 300 will be described with reference to FIGS. 4, 8 and 9.

  8 and 9 are diagrams schematically showing the operation of the substrate processing apparatus of FIG. The substrate processing apparatus 300 in FIG. 6 executes a process similar to each process shown in the flowchart in FIG. 4 to perform a rinse process, a sublimation drying process, and a dew condensation prevention process on the substrate W. In the substrate processing apparatus 300, the substrate W is loaded into the mounting table 390 of the substrate processing apparatus 300 and held on the mounting table 390 in a state where the substrate surface Wf is completely covered with a processing liquid such as an IPA liquid. At the time of this transfer, the processing chamber 310 of the substrate processing apparatus 300 is opened by the chamber opening / closing mechanism 317. The control unit 500 reads and sets a recipe selected by the user or operator from a memory (not shown) (step S11), and sets various control data (rotation parameters of the number of rotations of the substrate, rotation time parameters, dioxide dioxide) defined by the recipe. Each part of the apparatus is controlled as follows based on the flow rate of carbon, the temperature T1, T2, etc. of the nitrogen gas for sublimation drying.

  After the loading of the substrate W into the processing chamber 310 is completed, the upper member 313 and the lower member 314 are fitted by the chamber opening / closing mechanism 317. Note that at this stage, the valves 323, 333, 343, 443, and 353 are all closed, and the processing chamber 310 is hermetically sealed when the fitting operation is completed. At this stage, the internal atmosphere of the processing chamber 310 is normal temperature and pressure.

  When the inside of the processing chamber 310 is hermetically sealed, the valve 323 is opened, and the carbon dioxide gas supplied from the carbon dioxide supply unit 321 is supplied into the processing chamber 310 via the first introduction pipe 400. Further, the valve 353 is opened in response to the supply of the carbon dioxide gas. As a result, the air in the processing chamber 310 is discharged from the valve 353, and the processing chamber 310 is replaced with carbon dioxide gas.

  When a predetermined time elapses, the valve 353 is closed, and the inside of the processing chamber 310 is returned to a sealed state. On the other hand, since the valve 323 remains open, the supply of carbon dioxide gas to the processing chamber 310 is continued. For this reason, the pressure in the processing chamber 310 gradually increases, and the processing chamber 310 eventually has a temperature of −56.6 [° C.], which is a triple point of carbon dioxide, and a pressure of 5.1 atm (0.517 [MPa). ]) At a higher temperature and pressure. The carbon dioxide gas is liquefied in the processing chamber 310 when the pressure exceeds a predetermined pressure. The predetermined pressure at this time is a pressure determined based on a vapor pressure curve representing the relationship between the pressure and temperature at which the liquid phase and the gas phase coexist at the temperature in the processing chamber 310.

  As described above, the carbon dioxide supplied from the carbon dioxide supply unit 321 into the processing chamber 310 is supplied as a gas at the start of supply, and thereafter, the pressure in the processing chamber 310 exceeds 5.1 atm. When a predetermined condensing pressure is reached, the liquid state is reached. Thereafter, carbon dioxide is supplied to the substrate W in a liquid state. Accordingly, liquid carbon dioxide is substantially supplied to the processing chamber 310 except for the portion that once passes through the gas state in the initial stage.

Such a region where carbon dioxide exists as a liquid is
1) Triple point temperature is −56.6 [° C.], and the pressure is higher than the pressure of 5.1 atm.
2) The temperature is less than 31.1 [° C.] and less than 72.8 atm (7.38 [MPa]). This is not in the supercritical region and is maintained in a non-supercritical state. Has been. Then, the valve 353 is opened in this non-supercritical state, and the rotation mechanism 372 drives the mounting table 390 to rotate. As a result, the treatment liquid such as the IPA liquid and the liquid carbon dioxide existing on the surface of the substrate W flow toward the outer periphery of the substrate W due to the centrifugal force of the rotation of the substrate W. Then, the IPA liquid and the liquid carbon dioxide flow down to the bottom surface (upper surface of the lower wall 316) in the processing chamber 310 and are discharged out of the processing chamber 310 through the discharge pipe 351. As described above, in the present embodiment, the IPA liquid is efficiently rinsed and removed by the liquid carbon dioxide by rotating the substrate W (step S12).

  Further, the liquid carbon dioxide supplied from the first introduction pipe 400 into the processing chamber 310 is uniformly supplied to the surface of the substrate W by the fluid dispersion mechanism 380. Since the surface tension of the liquid carbon dioxide is smaller than the surface tension of the IPA liquid, the liquid carbon dioxide easily enters the gap between the patterns formed on the surface of the substrate W. Such supply of liquid carbon dioxide is performed until a predetermined time elapses so that the surface of the substrate W is completely replaced with liquid carbon dioxide.

  When the rinsing process is completed, the control unit 500 closes the valve 323 while the substrate W is rotated, and stops the supply of liquid carbon dioxide into the processing chamber 310. As a result, part of the liquid carbon dioxide on the substrate surface Wf is shaken out of the substrate W, and a carbon dioxide liquid film 14 is formed on the substrate surface Wf as shown in FIG. In this embodiment, the control unit 500 controls the number of rotations of the substrate W to adjust the thickness so that the thickness H1 of the liquid film 14 exceeds the depth of the pattern 12 on the substrate surface Wf, that is, the height H2. (Step S13).

  When the liquid film having the desired thickness H1 is formed, the valve 353 is closed, and the inside of the processing chamber 310 returns to a sealed state. Subsequently, the valve 343 is opened, and liquid nitrogen is supplied into the processing chamber 310 and blown directly onto the lower surface of the mounting table 390. For this reason, the temperature of the mounting table 390 rapidly decreases, and the substrate W held on the mounting table 390 is cooled. That is, the mounting table 390 cools the substrate W over the entire surface in contact with the substrate W like a cool plate. At this time, the valve 333 is opened, and room temperature carbon dioxide gas having a partial pressure equal to or higher than the triple point pressure of carbon dioxide, which is a sublimation substance, is supplied into the processing chamber 310 through the first introduction pipe 400. As a result, even during the cooling of the substrate W with liquid nitrogen, the pressure in the processing chamber 310 is maintained at or above the triple point pressure. In this embodiment, the pressure is not only increased to the triple point or more simply by the supply of carbon dioxide gas, but the valve 353 is opened while the opening degree is adjusted, and the pressure in the processing chamber 310 is set to a constant value equal to or higher than the triple point. Maintained.

  Thus, while the pressure is kept constant at 5.1 atm or higher and the temperature is lowered, the liquid film 14 of carbon dioxide formed on the surface of the substrate W is solidified (FIG. 8B: solidification step). ). As described above, in this embodiment, in order to solidify the liquid film 14 of carbon dioxide, liquid nitrogen as a refrigerant is directly supplied into the processing chamber 310. Therefore, heat is removed through the surface of the mounting table 390 with which the substrate W is in contact, and the frozen film 15 can be obtained by efficiently cooling the substrate W and solidifying the liquid film 14. In the solidification step, the first sublimation drying nitrogen gas or the second sublimation drying nitrogen gas may be supplied instead of the room temperature nitrogen gas. In these cases, the solidification time can be further shortened. Further, the supply of nitrogen gas may be stopped during the solidification process. In this case, it is possible to prevent disturbance of the liquid film 14 due to nitrogen gas during the solidification process, and the frozen film 15 having a uniform thickness can be stably formed over the entire substrate surface Wf. As a result, sublimation drying can be performed stably, and more excellent drying performance can be obtained.

  Thus, after the substrate surface Wf is covered with the carbon dioxide freezing film 15, the valves 333 and 343 are closed and the valve 353 is completely opened. As a result, the pressure in the processing chamber 310 drops to 1 atmosphere, which is the atmospheric pressure.

  Then, when the pressure in the processing chamber 310 becomes atmospheric pressure, the nitrogen gas supply unit 331 raises the temperature to a temperature T1 suitable for sublimation drying of the surface layer portion 15a of the frozen film 15 and performs the first sublimation drying nitrogen gas. And the valve 333 is opened again. Thus, the first sublimation drying nitrogen gas is introduced into the processing chamber 310 from the first introduction pipe 400 as shown in FIG. As a result, carbon dioxide is gradually sublimated from the surface layer portion 15a of the frozen film 15 on the substrate surface Wf (first sublimation step: step S15). At this time, the carbon dioxide gas generated by sublimation is removed from the substrate surface Wf by riding on the first sublimation drying nitrogen gas stream, so that the carbon dioxide gas generated by sublimation from the frozen film 15 becomes liquid phase or solid phase. Reattachment to the return substrate surface Wf can be reliably prevented. As the sublimation drying proceeds, the frozen film 15 gradually becomes thinner. In the figure, the alternate long and short dash line indicates the initial surface level of the frozen film 15.

  When a predetermined time has elapsed from the start of the sublimation drying process (first sublimation process) using the first nitrogen gas for sublimation drying (“YES” in step S16), the thickness of the frozen film 15 is the depth (height) H2 of the pattern 12 And the surface of the frozen film 15 is flush with the top of the pattern 12 as shown in FIG. Therefore, also in the second embodiment, similarly to the first embodiment, the control unit 500 switches to the sublimation drying process (second sublimation process) using the second sublimation drying nitrogen gas based on the passage of the predetermined time. That is, at this timing, the nitrogen gas supply unit 331 stops supplying the first sublimation drying nitrogen gas and ends the sublimation drying of the surface layer portion 15a of the frozen film 15. At this time, the frozen film 15 having the thickness H2 remains on the substrate surface Wf, and this is referred to as “residual portion 15b” and the description of the second sublimation process will be continued.

  When the supply of the first sublimation drying nitrogen gas is stopped and replaced, the nitrogen gas supply unit 331 raises the temperature to the temperature T2 (<T1) suitable for the sublimation drying of the residual portion 13b to generate the second sublimation drying nitrogen gas. . The second sublimation drying nitrogen gas is supplied to the substrate surface Wf in the same manner as the first sublimation drying nitrogen gas, and carbon dioxide is gradually sublimated from the residual portion 15b as shown in FIG. Second sublimation step: Step S17). Also. The carbon dioxide gas generated by the sublimation is removed from the substrate surface Wf by riding on the second sublimation drying nitrogen gas stream.

  When the sublimation drying is completed, the first nitrogen gas supply unit 331 opens the valve 443 in parallel with the supply of the room temperature nitrogen gas from the first introduction pipe 400 instead of the supply stop of the first sublimation drying nitrogen gas. Then, the high-temperature nitrogen gas heated by the heater 444 is blown directly from the third introduction pipe 441 to the lower surface of the mounting table 390. As a result, the heat of the high-temperature nitrogen gas is transmitted to the substrate W via the mounting table 390, so that the temperature of the substrate W is increased, and condensation on the surface of the substrate W can be prevented (condensation prevention step: step S18). The dew condensation prevention step corresponds to the “substrate heating step” of the present invention, but is not an essential step in the substrate drying process, and may be appropriately employed as necessary.

  As described above, although the second embodiment is different from the first embodiment in that carbon dioxide is used as the sublimation substance, the same effects as the first embodiment can be obtained. That is, in the first sublimation step, the first sublimation drying nitrogen gas having a relatively high temperature T1 is used as the drying gas while the remaining portion 15b remains in the pattern 12, so that the surface layer can be formed without causing pattern collapse. The part 15a can be sublimated and dried in a short time. Then, when the surface layer portion 15a is sublimated and dried and the remaining portion 15b has the same thickness as the pattern 12, the drying gas is switched to the second sublimation drying nitrogen gas having a temperature lower than that of the first sublimation drying nitrogen gas. The remaining portion 15b is sublimated and dried. For this reason, the remaining part can be sublimated and dried with excellent drying performance. Therefore, compared with the case where the frozen film 15 is sublimated and dried using only a drying gas having a relatively low temperature, the time required for sublimating and drying the frozen film 15 is reduced by the amount of time required for sublimation drying of the surface layer portion 15a. Can be shortened.

D. Third Embodiment In the first embodiment and the second embodiment, the coagulation process, the sublimation drying process, and the dew condensation prevention process are continuously performed in one processing chamber. However, these processes are performed separately. You may comprise. The substrate processing apparatus 700 may include a coagulation apparatus 710 and a substrate drying apparatus 720 that perform a coagulation process, for example, as shown in FIG. In this case, a frozen film 13 (or 15) of a sublimation material having a thickness equal to or greater than the depth of the pattern 12 is formed on the substrate surface Wf in a processing chamber (not shown) of the coagulation apparatus 710. The substrate W is carried into a processing chamber (not shown) of the substrate drying apparatus 720 and subjected to a first sublimation process and a second sublimation process. As a result, after the sublimation substance is sublimated from the substrate surface Wf, a dew condensation preventing process is performed.

E. Others As described above, in the above embodiment, the spin chuck 102 of the first embodiment and the mounting table 390 of the second embodiment function as the “substrate holding portion” of the present invention. Further, the first sublimation drying nitrogen gas and the second sublimation drying nitrogen gas function as the “drying gas” of the present invention. Further, the nitrogen gas supply mechanism 105 of the first embodiment and the first nitrogen gas supply unit 331 of the second embodiment both have the functions of the “first dry gas supply unit” and the “second dry gas supply unit” of the present invention. Have both. The dehumidifying unit 154 and the temperature adjusting unit 155 correspond to the “first dry gas supply unit” of the present invention, and the dehumidifying unit 154 and the temperature adjusting unit 156 correspond to the “second dry gas supply unit” of the present invention. Furthermore, the control units 104 and 500 function as the “control unit” of the present invention.

  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. For example, in the above embodiment, nitrogen gas is used as the “drying gas” of the present invention, but the present invention is not limited to this, and for example, other inert gas may be used.

  In the above embodiment, DIW or carbon dioxide is used as the “sublimation substance” of the present invention. However, the present invention is not limited thereto. For example, tertiary butanol, camphor, paradichlorobenzene, Tetrachlorodifluoroethane, naphthalene, or the like may be used.

  In the above-described embodiment, the thickness H1 of the frozen films (solidified bodies) 13 and 15 exceeds the depth of the pattern 12 on the substrate surface Wf, that is, the height H2. The same effect as the above embodiment can be obtained.

  Moreover, in the said embodiment, although the end point of the 1st sublimation process is determined based on the elapsed time after starting a 1st sublimation process, the thickness of the frozen films | membranes 13 and 15 is directly or indirectly determined by a sensor etc. The end point may be determined based on the measurement result.

  Further, in the first and second embodiments, the substrate drying apparatus is incorporated in the substrate processing apparatus, and the substrate after the rinsing process is dried. In the third embodiment, the substrate on which the frozen film (solidified body) is formed in advance is dried. However, the application target of the present invention is not limited to these. For example, the present invention can also be applied to an apparatus in which a chemical processing means in a pretreatment process is incorporated in a substrate drying apparatus and a series of processes from chemical processing to drying processing is continuously performed in the apparatus.

  The present invention can be applied to all substrate drying techniques in which a solidified sublimation substance formed on the surface of various substrates is sublimated to dry the substrate.

12 ... Pattern 13, 15 ... Frozen membrane (coagulated body)
13a, 15a ... Surface layer part 13b, 15b ... Remaining part 102 ... Spin chuck (substrate holding part)
104, 500 ... Control unit (control unit)
105 ... Nitrogen gas supply mechanism (first dry gas supply unit, second dry gas supply unit)
154 ... Dehumidifying section (first drying gas supply section, second drying gas supply section)
155 ... Temperature adjustment unit (first drying gas supply unit)
156 ... Temperature adjustment unit (second drying gas supply unit)
330... First nitrogen gas supply mechanism (first dry gas supply unit, second dry gas supply unit)
331 ... Nitrogen gas supply unit (first dry gas supply unit, second dry gas supply unit)
720 ... Substrate dryer T1 ... First temperature T2 ... Second temperature W ... Substrate Wb ... Substrate back surface Wf ... Substrate surface

Claims (6)

A dry gas having a first temperature not higher than the freezing point of the sublimation substance is supplied to a solidified body of the sublimation substance formed on the substrate surface on which the pattern is formed with a thickness greater than or equal to the depth of the pattern. A first sublimation step of sublimating the sublimation material constituting the surface layer portion;
The residual portion is removed from the solidified body by the first sublimation step and supplied with a dry gas having a second temperature lower than the first temperature to the residual portion remaining on the substrate surface. the sublimation material constituting a second sublimation step of sublimating,
In the substrate drying method , the first sublimation step is a step of sublimating the sublimation substance constituting the surface layer portion of the solidified body while the solidified body remains in the entire pattern . The substrate drying method according to claim 1,
Prior to the first sublimation step, the substrate drying method further includes a solidification step of cooling the liquid of the sublimation substance adhering to the substrate surface to form the solidified body thicker than the depth of the pattern on the substrate surface. It is a substrate drying method of Claim 2, Comprising: The said solidification process is a board | substrate drying method which is a process of supplying a refrigerant | coolant to the substrate back surface opposite to the said substrate surface, and forming the said solidified body. A substrate drying method according to claim 2 or 3,
In the substrate drying method, the first sublimation step is a step of sublimating the sublimation material constituting the surface layer portion of the solidified body so that the remaining portion has the same thickness as the depth of the pattern. A substrate drying method according to any one of claims 1 to 4,
A substrate drying method further comprising a substrate heating step of heating the substrate by supplying a gas having a temperature higher than a freezing point of the sublimation substance to the substrate after the second sublimation step. A substrate holding part for holding a substrate having a pattern and a surface on which a solidified body of a sublimation substance is formed with a thickness equal to or greater than the depth of the pattern;
A first drying gas supply unit for supplying a drying gas having a first temperature below the freezing point of the sublimation substance to the substrate held by the substrate holding unit;
A second drying gas supply unit for supplying a drying gas having a second temperature lower than the first temperature to the substrate held by the substrate holding unit;
A controller that controls the first dry gas supply unit and the second dry gas supply unit,
The controller is
Sublimating the sublimation material constituting the surface layer portion of the solidified body while supplying the drying gas at the first temperature to the solidified body and leaving the solidified body throughout the pattern ,
The substrate drying apparatus which sublimates the sublimation substance which comprises the said solidification body by supplying the drying gas of said 2nd temperature with respect to the residual part which the said surface layer part removes from the said solidification body, and remains on the said substrate surface.

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