JP2007049065A - Super-critical processor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a processor which can perform heating required to make substance super-critical state, and cooling for returning a pressure-resistant vessel to room temperature in a short time. <P>SOLUTION: In the processor, a vessel upper portion 100 is constituted by a lid 101 and top board 102, and prepares a space (upper space) 103 sealed by the lid 101 and top board 102; the lid 101 is constituted by for example stainless steel; the top board 102 is constituted by a low specific heat metal such as copper or aluminum or the like high in thermal conductivity, and its thickness is made to be 10 mm or so; and the top board 102 is arranged so that it may cover a concave portion of the lid 101, and in an interior of the space 103, an inside of the lid 101 and inside of the top board 102 are arranged so that they may have a spacing of 5 mm or so. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a supercritical processing apparatus used for, for example, formation of a substrate having a fine structure on the order of nm, cleaning, and drying.

  In order to fabricate large-scale and high-performance devices such as LSIs, extremely fine patterns are required. Such a pattern is a resist pattern formed through exposure, development, and cleaning (rinsing), and an etching pattern formed through etching and cleaning (water washing). A resist is a polymer material that is sensitive to light, X-rays, electron beams, and the like. However, a phenomenon that the pattern collapses at the formation stage of the ultrafine pattern occurs, and there is a problem that a pattern that satisfies the performance cannot be formed.

  This problem occurs not only in resist patterns and patterns etched using this as a mask, but also in silicon stencil masks (masks having a pattern formed by penetrating a Si substrate) used in lithography, the patterns are stretched by drying after washing with water. There was a problem with it. Also, in the field of micromachine and MEMS (Micro-Electro-Mechanical System) manufacturing, a thin silicon film sticks to the substrate, making it difficult to form a device with good performance.

  As shown in Non-Patent Document 1, these causes are caused by the action of external force (surface tension) generated by the rinse liquid remaining between fine patterns in the cleaning and cleaning process during formation. And being transformed. Since the surface of the liquid tends to shrink due to surface tension, an external force is applied to the fine pattern in contact with the slightly remaining liquid. Also, the greater the surface tension of the liquid used, the greater the force applied to the pattern, but the more likely the pattern will be deformed.

  Here, since the surface tension is generated at the interface (gas-liquid interface) with the liquid gas, the deformation of the pattern can be suppressed by preventing the formation of the gas-liquid interface. As a technique for realizing this, there is a process using a supercritical fluid. A supercritical fluid has both gas diffusivity and liquid solubility (high density), and can change its state from liquid to gas without an equilibrium line. For this reason, when the fluid is gradually released from the state filled with the supercritical fluid, a liquid / gas interface is not formed, and drying can be performed in a state where surface tension does not act on the pattern (non- Patent Document 2).

  In supercritical processing using such characteristics, carbon dioxide having a low critical point and easy handling is generally used as a supercritical fluid. In drying with carbon dioxide in a supercritical state (supercritical carbon dioxide), first, a substrate whose surface is covered with a predetermined cleaning liquid (rinsing liquid) is placed in a pressure vessel, and liquefied carbon dioxide is introduced into the substrate surface. Replacing the cleaning liquid in which the liquid is immersed with liquefied carbon dioxide. Carbon dioxide liquefies at about 6 MPa at room temperature (around 25 ° C.), and liquefies at a pressure of 6 MPa or less at a temperature lower than room temperature.

  After the inside of the pressure vessel is filled with liquefied carbon dioxide and the substrate is completely immersed in liquefied carbon dioxide, the internal temperature is raised to a temperature and pressure above the critical point (critical point of carbon dioxide; 31 ° C. 7.3 MPa) to convert liquefied carbon dioxide into supercritical carbon dioxide. After these, supercritical carbon dioxide is released to the outside while maintaining the internal temperature, and drying is completed if the internal pressure in the pressure-resistant period is set to atmospheric pressure.

  Examples of apparatuses that perform such supercritical processing include those disclosed in Patent Document 1, Patent Document 2, and Patent Document 3. These heat the pressure vessel or the substrate holder to bring the internal carbon dioxide to a temperature above the critical point and create a supercritical state. In such an apparatus, it is desirable that the temperature inside the pressure vessel is cooled to about room temperature or lower when the substrate is carried into the pressure vessel at the start of processing. When the substrate is carried in, if the internal temperature of the pressure vessel is high, the liquid adhering to the substrate to be processed is dried, and the pattern deformation due to the surface tension described above occurs.

  In order to prevent this, as described above, it is better to lower the temperature of the pressure-resistant container at the start of the processing to prevent the liquid adhering to the substrate to be processed from being dried. Also, from the viewpoint of introducing liquefied carbon dioxide into the pressure resistant container, it is better that the internal temperature of the pressure resistant container is lower at the start of processing, for example, the lower the internal temperature of the pressure resistant cool air, the faster the inside of the pressure resistant container. A state in which liquefied carbon dioxide is introduced into is obtained. In this way, in order to perform a quicker process in a pressure-resistant vessel (processing apparatus) that performs supercritical processing, cooling is performed at the start of processing, and heating (temperature increase) is performed in a shorter time at the stage of setting the supercritical state. Will do.

JP 2000-091180 A JP 2002-313773 A JP 2005-000853 A Applied Physics Letters, 66, 2655-2657, 1995. Journal of Vacuum Science and Technology, B18, 780-784, 2000.

  However, when a conventional supercritical drying apparatus is used, there is a problem that it takes much time to raise and lower the internal temperature of the pressure vessel. In supercritical drying equipment, a pressure vessel made of a thick stainless steel plate is used to withstand high pressure, but in the case of such a counter pressure vessel, heating and cooling to a predetermined temperature is required. Took more than 30 minutes. Although heating can be shortened by using a large-capacity heater, a time of 10 minutes or more is required even in this case. In addition, according to the method of heating only the substrate or the substrate holder that supports the substrate, the periphery of the substrate to be processed can be instantaneously heated (Patent Documents 2 and 3). However, this technique also requires 5 minutes or more for heating to the desired critical temperature.

  In contrast to the heating described above, cooling to room temperature requires more time and is more problematic. Until now, it has not been easy to shorten the time required for this cooling, and it has been difficult to shorten the processing time. Conventionally, for example, as shown in FIG. 12, cooling water is circulated through a cooling water pipe 1202 embedded in the pressure vessel 1201 to cool the pressure vessel 1201. It took more than a minute. In order to increase the cooling efficiency, it is sufficient to increase the number of cooling water circulation pipes into the pressure vessel. However, this causes a problem that the heating efficiency is lowered because heat at the time of heating escapes through the circulation pipes. . Further, even in the method of heating the substrate holder described above, no measures are taken for cooling, and therefore a cooling time of 20 minutes or more is required.

As described above, when a conventional supercritical processing apparatus is used, it takes a long time to control the temperature, and there is a problem that the processing capacity (processing time) is not practical. In particular, with regard to cooling for a short time, there has been no device ingenuity.
The present invention has been made to solve the above-described problems, and its purpose is to shorten the heating required to bring a substance into a supercritical state and the cooling required to return the pressure vessel to room temperature. It provides a device that can be done in time.

  A supercritical processing apparatus according to the present invention includes a lower part of a container having a processing space in which a substrate to be processed is accommodated, an upper part of the container that is bonded onto the lower part of the container to seal the processing space, A top plate arranged on the side of the upper processing space, an upper space formed between the top plate and the upper part of the container, and a supercritical material that becomes a supercritical state by setting a critical condition inside the processing space. At least a supercritical substance introducing means to be introduced into the chamber, a discharging means for discharging the fluid inside the processing space, and a heating means for heating the inside of the processing space.

  In the supercritical processing apparatus, a top plate temperature control means for controlling the temperature of the top plate disposed in the upper space may be provided. In this case, the top plate temperature control means may be a liquefied gas introduced into the upper space in order to cool the temperature of the top plate. Further, the top plate temperature control means may be constituted by a Peltier element. The heating means may include a top plate temperature control means.

  The supercritical processing apparatus may include a substrate mounting table disposed on the processing space side of the lower part of the container and a lower space formed between the substrate mounting table and the lower part of the container. Moreover, you may make it provide the mounting base temperature control means which controls the temperature of the board | substrate mounting base arrange | positioned in lower space. The mounting table temperature control means may be a liquefied gas introduced into the lower space in order to cool the temperature of the substrate mounting table. Further, the mounting table temperature control means may heat the substrate mounting table by resistance heating. Further, the mounting table temperature control means may be composed of a Peltier element. Further, the heating means includes a mounting table temperature control means.

  As described above, according to the present invention, since the upper space is provided between the top plate disposed on the processing space side of the upper portion of the container and the upper portion of the container, the material is brought into a supercritical state. An excellent effect is obtained in that an apparatus capable of performing necessary heating and cooling for returning the pressure vessel to room temperature in a shorter time can be provided.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. 1, 2, and 3 are cross-sectional views schematically showing a configuration example of a supercritical processing apparatus in an embodiment of the present invention. 1 and 2 show a partial configuration of a supercritical processing apparatus, FIG. 1 shows a container upper part 100, and FIG. 2 shows a container lower part that is joined to the container upper part 100 to form a sealed space therein. FIG. 3 shows a state in which the container upper part 100 is joined (attached) to the container lower part 200.

  First, the container upper portion 100 shown in FIG. 1 includes a lid portion 101 and a top plate 102, and includes a space (upper space) 103 that is sealed by the lid portion 101 and the top plate 102. The lid 101 is made of, for example, stainless steel. Further, the top plate 102 is made of a metal having a low specific heat and a high thermal conductivity such as copper and aluminum, and has a thickness of about 10 mm. The top plate 102 is disposed so as to close the concave portion of the lid 101, and inside the space 103, the inside of the lid 101 and the inside of the top plate 102 are spaced by about 5 mm. As will be described later, the top plate 102 may be made thinner as long as the pressure in the processing space can be maintained in a predetermined state (supercritical state).

  The container upper part 100 includes a liquefied gas supply pipe 104 and a liquefied gas discharge pipe 105 that pass through the lid 101 and communicate with the space 103, and each includes a valve 106 and a valve 107. For example, the top plate 102 can be instantaneously cooled by introducing the liquefied gas into the space 103 through the liquefied gas supply pipe 104.

  On the other hand, the container lower part 200 shown in FIG. 2 includes a container structure 201 and a substrate mounting table 202, and includes a space (lower space) 203 sealed by the container structure 201 and the substrate mounting table 202. A processing space 204 for storing the substrate W to be processed is provided on the mounting table 202. The processing space 204 is opened, and the processing space 204 is closed as the container upper part 100 is joined (crowded). The container structure 201 is made of, for example, stainless steel, and the substrate mounting table 202 is made of a low specific heat metal having high thermal conductivity such as copper or aluminum. In addition, the substrate mounting table 202 includes a heating mechanism 205.

  The container lower part 200 includes a liquefied gas supply pipe 206 and a liquefied gas discharge pipe 207 that pass through the lower part of the container structure 201 and communicate with the space 203, and each includes a valve 208 and a valve 209. For example, the substrate mounting table 202 can be instantaneously cooled by introducing the liquefied gas into the space 203 through the liquefied gas supply pipe 206. Further, the container lower part 200 includes a supercritical material supply pipe 211 and a discharge pipe 212 that penetrate the side of the container structure 201 and communicate with the processing space 204, and each includes a valve 213 and a valve 214.

  In the supercritical processing apparatus configured as described above, first, as shown in FIG. 2, after the substrate W to be processed is placed on the substrate mounting table 202, the container lower part 200 (container structure 201), the processing space 204 can be hermetically sealed as shown in FIG. Further, when the processing space 204 is sealed, the valve 213 is opened with the valve 214 closed, and liquefied carbon dioxide is introduced into the processing space 204 from the supercritical material supply pipe 211, so that the processing space 204 becomes liquefied carbon dioxide. It can be in a state filled with carbon. At this time, the substrate W is immersed in the filled liquefied carbon dioxide, and for example, the rinsing liquid attached to the substrate W is replaced with liquefied carbon.

  When the substrate mounting table 202 is heated by operating the heating mechanism 205 in this state, the substrate mounting table 202 is immediately heated because the specific heat is small. In addition, since the substrate mounting table 202 includes the space 203 in the lower portion, the heat of the substrate mounting table 202 is difficult to conduct to the pressure resistant container 1201 and is heated in a state where there is little heat loss. This means that the substrate mounting table 202 quickly enters a thermal equilibrium state, and indicates that the processing space 204 is rapidly heated. Similarly, the top plate 102 disposed on one side of the processing space 204 is also provided with the space 103 between the lid 101 and the temperature inside the processing space 204 is not easily conducted to the lid 101. The heat loss is suppressed. The space 103 and the space 203 may be in a state where heat conduction is further suppressed by evacuating and reducing the pressure. For example, by using the liquefied gas discharge pipe 105, the inside of the space 103 can be exhausted and depressurized.

  As described above, according to the supercritical processing apparatus shown in FIG. 3, the substrate mounting table 202 is heated, so that the liquefied carbon dioxide filled in the processing space 204 is heated in a state where heat loss is suppressed. Will come to be. If the liquefied carbon dioxide filled in the processing space 204 is heated and exceeds a critical condition to be in a supercritical state, the liquefied carbon dioxide on the substrate W to be processed becomes supercritical carbon dioxide 301. . Thus, supercritical processing can be performed on the substrate W. Next, if the pressure in the processing space 204 is reduced by closing the valve 213 and opening the valve 214 to discharge the fluid inside the processing space 204 to the outside, the supercritical carbon dioxide 301 above the substrate W is removed. As a result, the substrate W is dried. According to these, on the surface of the substrate W, the drying is performed in a state where no gas-liquid interface is formed.

  Thereafter, the operation of the heating mechanism 205 is stopped, the valve 208 is opened, and, for example, liquefied carbon dioxide is introduced into the space 203 through the liquefied gas supply pipe 206, whereby the substrate mounting table 202 can be rapidly cooled. . Similarly, the top plate 102 can be quickly cooled by opening the valve 106 and introducing, for example, liquefied carbon dioxide into the space 103 through the liquefied gas supply pipe 104. Thus, if the top plate 102 and the substrate mounting table 202 are cooled, the inside of the processing space 204 of the supercritical processing apparatus is substantially cooled. In the supercritical processing apparatus shown in FIGS. 1 and 3, the top plate 102 constituting the processing space 204 can be rapidly cooled by introducing a low-temperature fluid (refrigerant) into the space 103. In this case, the low temperature fluid introduced into the space 103 serves as a cooling means for cooling the top plate 102.

  Similarly, in the supercritical processing apparatus shown in FIGS. 2 and 3, the substrate mounting table 202 constituting the processing space 204 can be rapidly cooled by introducing a low-temperature fluid into the space 203. In this case, the low temperature fluid introduced into the space 203 serves as a cooling means for cooling the substrate mounting table. Further, for example, the liquefied gas (liquefied carbon dioxide) introduced into the space 103 is abruptly released from the liquefied gas discharge pipe 105 by opening the valve 107, thereby vaporizing the liquefied gas in the space 103. The top plate 102 may be rapidly cooled by the heat of vaporization. Similarly, the liquefied gas introduced into the space 203 is abruptly released from the liquefied gas discharge pipe 207 by opening the valve 209, and the liquefied gas in the space 203 is vaporized. You may make it cool rapidly.

  As described above, according to the supercritical processing apparatus shown in FIGS. 1, 2, and 3, since the space 103 is provided in the upper part 100 of the container, the heat loss inside the processing space 204 is reduced, It is easy to raise the temperature inside the processing space 204 more quickly. Further, by introducing a cooling means such as a low-temperature fluid into the space 103, the top plate 102 constituting the processing space 204 can be cooled more quickly. The same applies to the container lower part 200. As for cooling, a gas such as air or nitrogen may be introduced, but if liquefied carbon dioxide is used as a low-temperature fluid, it is very simple and easy to handle.

  Next, another supercritical processing apparatus in the embodiment of the present invention will be described. FIG. 4 is a cross-sectional view schematically showing a configuration example of another supercritical processing apparatus according to the embodiment of the present invention. The supercritical processing apparatus shown in FIG. 4 includes a container upper part 400 and a container lower part 500. First, the container upper portion 400 includes a lid portion 401 and a top plate 402, and includes a space 403 that is sealed by the lid portion 401 and the top plate 402. A Peltier element 404 is fixed on the top plate 402 inside the space 403. The Peltier element 404 is connected to an element control unit (not shown), and a predetermined voltage is applied under the control of the element control unit. The top plate 402 can be instantaneously cooled by the Peltier element 404. The lid 401 is made of stainless steel, for example. The top plate 402 is made of a metal with low specific heat and high thermal conductivity, such as copper and aluminum, and has a thickness of about 10 mm.

  On the other hand, the container lower part 500 includes a container structure 501 and a substrate mounting table 502, and includes a space 503 sealed by the container structure 501 and the substrate mounting table 502. The processing space 506 for accommodating the substrate W is provided. It should be noted that the processing space 506 is opened, and the processing space 506 is a sealed space when the container upper portion 400 is joined (crowded). In addition, the container structure 501 is made of, for example, stainless steel, and the substrate mounting table 502 is made of a low specific heat metal having high thermal conductivity such as copper or aluminum.

  In addition, a Peltier element 505 is fixed to the substrate mounting table 502 inside the space 503. The Peltier element 505 is connected to an element control unit (not shown), and a predetermined voltage is applied under the control of the element control unit. The substrate mounting table 502 is heated or cooled by the Peltier element 505. Further, the container lower part 500 includes a supercritical material supply pipe 511 and a discharge pipe 512 that pass through the side portion of the container structure 501 and communicate with the processing space 506, and includes a valve 513 and a valve 514, respectively.

  The supercritical processing using the supercritical processing apparatus shown in FIG. 4 configured as described above will be briefly described. First, the substrate W to be processed is loaded into the processing space 506 and the substrate W is placed on the substrate mounting table 502. It shall be in the state mounted on. Next, the container upper part 400 (lid part 401) is crowned on the container lower part 500 (container structure 501) so that the processing space 506 is sealed. Next, if the valve 513 is opened while the valve 514 is closed and liquefied carbon dioxide is introduced into the processing space 506 from the supercritical material supply pipe 511, the processing space 506 is filled with liquefied carbon dioxide. Can do. For example, the processing space 506 is filled with liquefied carbon dioxide in a state where the pressure is 8 MPa by pumping using a pumping pump (not shown) or the like. At this time, the substrate W is immersed in the filled liquefied carbon dioxide, and for example, the rinsing liquid attached to the substrate W is replaced with liquefied carbon.

  In this state, when the Peltier element 505 is operated in a heated state to heat the substrate mounting table 502, the substrate mounting table 502 is immediately heated because the specific heat is small. At the same time, since the Peltier element 404 is also operated in a heated state, the top plate 403 is also immediately heated. In addition, since the substrate mounting table 502 includes the space 503 in the lower part, the heat of the substrate mounting table 502 is difficult to conduct to the pressure resistant container 1501 and is heated in a state where there is little heat loss. This means that the substrate mounting table 502 quickly enters a thermal equilibrium state, and indicates that the processing space 506 is heated quickly. Similarly, the top plate 402 disposed on one side of the processing space 506 also includes a space 403 between the lid 401 and the temperature inside the processing space 506 is difficult to conduct to the lid 401. The heat loss is suppressed.

  In this way, by heating the substrate mounting table 502, the liquefied carbon dioxide filled in the processing space 506 is heated in a state where heat loss is suppressed. Since the pressure of the liquefied carbon dioxide filled in the processing space 506 is about 8 MPa, the liquefied carbon dioxide on the substrate W to be processed becomes supercritical when heated to about 40 ° C. above the critical temperature. Carbon becomes supercritical carbon dioxide 301 (FIG. 5). Thus, supercritical processing can be performed on the substrate W. Next, if the valve 513 is closed and the valve 514 is opened, and the pressure inside the processing space 506 is reduced by discharging the fluid inside the processing space 506 to the outside, the supercritical carbon dioxide 301 above the substrate W is reduced. As a result, the substrate W is dried (FIG. 6). According to these, on the surface of the substrate W, the drying is performed in a state where no gas-liquid interface is formed.

  Thereafter, if the operation of the Peltier element 505 is changed to a cooling state, for example, by applying a reverse current, the substrate mounting table 502 can be rapidly cooled. Similarly, the top plate 402 can be quickly cooled by operating the Peltier element 404 in a cooled state. Thus, if the top plate 402 and the substrate mounting table 502 are cooled, the inside of the processing space 506 of the supercritical processing apparatus is substantially cooled. The top plate 402 and the substrate mounting table 502 only need to withstand the pressure used in the processing space 506. For example, when processing is performed at a pressure of 8 MPa, it is only necessary to withstand a pressure of about 10 MPa. If a pressure safety release valve that operates at a pressure of 10 MPa is provided, the top plate 402 and the substrate mounting table 502 can be prevented from being damaged. Therefore, as described above, the top plate may be thinner than about 10 mm as long as it can withstand a pressure of about 10 MPa. On the other hand, the high-pressure container composed of the container upper part 400 and the container lower part 500 is capable of withstanding up to 15 MPa, which is 1.5 times the legally stipulated portion of the container structure composed of the lid 401 and the container structure 501. It is only necessary to be designed and manufactured.

  Next, another supercritical processing apparatus in the embodiment of the present invention will be described. FIG. 7 is a cross-sectional view schematically showing a configuration example of another supercritical processing apparatus in the embodiment of the present invention. The supercritical processing apparatus shown in FIG. 7 includes a container upper part 400 and a container lower part 700. The container upper portion 400 is the same as the supercritical processing apparatus shown in FIG. 4, and includes a lid portion 401 and a top plate 402, and includes a space 403 that is sealed by the lid portion 401 and the top plate 402. The lid 401 is made of stainless steel, for example. The top plate 402 is made of a metal with low specific heat and high thermal conductivity, such as copper and aluminum, and has a thickness of about 10 mm. A Peltier element 404 is fixed on the top plate 402 inside the space 403. The Peltier element 404 is connected to an element control unit (not shown), and a predetermined voltage is applied under the control of the element control unit. The top plate 402 can be instantaneously cooled by the Peltier element 404.

  On the other hand, the container lower part 700 is composed of a container structure 701 and an induction heating element 705 built in the container structure 701, and a substrate W to be processed is accommodated above the bottom part where the induction heating element 705 is embedded. A processing space 706 is provided. Note that the processing space 706 is opened and the container upper portion 400 is joined (crowded) so that the processing space 706 is a sealed space. The container structure 701 is made of, for example, stainless steel. The container lower portion 700 includes a pipe 711 that penetrates the side portion of the container structure 701 and communicates with the processing space 706, and the pipe 711 is provided with a pressure control valve 712.

  The supercritical processing using the supercritical processing apparatus shown in FIG. 7 configured as described above will be briefly described. First, the substrate holder 801 in which the substrate W to be processed is accommodated is loaded into the processing space 706 and the substrate W is loaded. Are arranged in the processing space 706 (FIG. 8). The substrate holder 801 is made of, for example, a metal that is heated by dielectric heating. Next, the container upper part 400 (lid part 401) is crowned on the container lower part 700 (container structure 701) so that the processing space 706 is sealed (FIG. 9).

  Next, when the pressure adjustment valve 712 is opened, a liquefied carbon dioxide supply unit (not shown) is connected to the pipe 711, and liquefied carbon dioxide is introduced into the processing space 706 via the pipe 711, the processing space 706 is created. It can be set as the state filled with the liquefied carbon dioxide. For example, the processing space 706 is filled with liquefied carbon dioxide in a state where the pressure is 8 MPa by pumping using a pumping pump (not shown) or the like. At this time, the substrate W is immersed in the filled liquefied carbon dioxide, and for example, the rinsing liquid attached to the substrate W is replaced with liquefied carbon.

  In this state, the induction heating element 705 is operated to bring the substrate holder 801 into a heated state. In addition, the Peltier element 404 is operated in the heated state so that the top plate 402 is heated. The liquefied carbon dioxide filled in 706 is heated in a state where heat loss is suppressed. The top plate 402 disposed on the container upper portion 400 side of the processing space 706 is provided with a space 403 between the lid 401 and the temperature inside the processing space 706 is difficult to conduct to the lid 401, Loss is suppressed. This means that the processing space 706 is quickly brought into a thermal equilibrium state, and indicates that heating by the substrate holder 801 in the processing space 706 is performed quickly.

  Since the pressure of the liquefied carbon dioxide filled in the processing space 706 is about 8 MPa, the liquefied carbon dioxide on the substrate W to be processed becomes supercritical when heated to about 40 ° C. above the critical temperature. Carbon becomes supercritical carbon dioxide (FIG. 9). Thus, supercritical processing can be performed on the substrate W. Next, a liquefied carbon dioxide supply unit (not shown) is disconnected from the pipe 711, the pressure control valve 712 is gradually opened, and the pressure inside the processing space 706 is gradually discharged by gradually discharging the fluid inside the processing space 706 to the outside. When the temperature is lowered, the supercritical carbon dioxide on the upper portion of the substrate W is vaporized, and a state where the substrate W is dried is obtained. According to these, on the surface of the substrate W, the drying is performed in a state where no gas-liquid interface is formed.

  Thereafter, the container upper part 400 is separated from the container lower part 700, the substrate holder 801 is taken out of the processing space 706, and placed on a cooling table (not shown), whereby the substrate holder 801 is cooled. Moreover, the top plate 402 can be rapidly cooled by operating the Peltier element 404 in the cooled state. As described above, according to the supercritical processing apparatus shown in FIG. 7, the lower part 700 of the container is not heated so much, so if the top plate 402 is cooled, the processing space 706 of the supercritical processing apparatus is substantially obtained. The inside is quickly cooled.

  Further, if a supercritical substance in a liquid state is used at a room temperature of about 20 to 25 ° C., the supercritical substance liquid is accommodated in the substrate holder 801, and the substrate W to be processed is accommodated therein. Then, the substrate holder 801 may be carried into the processing target space 706 (container structure 701). From this state, the container upper part 400 (lid part 401) is crowned on the container lower part 700 (container structure 701), the processing space 706 is sealed, and the substrate holder is operated by the induction heating element 705. If 801 is in a heated state, the supercritical substance can be brought into a supercritical state. In the sealed processing space 706, the heated supercritical material is vaporized, and thus the pressure in the processing space 706 can be made higher than the critical pressure of the supercritical material.

  As shown in FIG. 10, a pipe 414 and a pipe 415 that pass through the lid 401 and communicate with the space 403 may be provided, and a valve 416 and a valve 417 may be provided respectively. For example, if the cooling gas is introduced from the pipe 414 and the gas in the space 403 is discharged from the pipe 415, heat does not easily accumulate in the space 403. Note that a valve 416 and a valve 417 may be provided, and when the high-pressure fluid on the processing space side leaks from the top plate 402, these valves may be automatically closed.

  Moreover, as shown in FIG. 10, the top plate 402 may be fixed to the lid 401 via a heat insulating member 1001 having a low thermal conductivity. The heat insulating member 1001 is preferably made of a plastic material that has a heat insulating effect and can perform pressure sealing. The heat insulating member 1001 may be made of, for example, a resin material such as silicon rubber or fluororubber, or a ceramic such as alumina or silicon nitride. By using the heat insulating member 1001, the temperature inside the processing space is suppressed from being conducted to the lid 401 via the top plate 402, and a state in which heat loss is further suppressed is obtained.

  Further, as shown in the plan view of FIG. 11, the radiating fins 441 provided in the Peltier element 404 may be corrugated. The heat radiation fins 411 are provided for heat exchange. However, since the heat exchange speed increases as the surface area increases, the heat radiation fins 411 have a larger area in a certain region by using a waveform. Can be provided.

  Next, an example of a processing method using the above-described supercritical processing apparatus will be described in more detail.

[Processing method example 1]
First, a 300 nm thick SiO ₂ film and a 600 nm thick polycrystalline silicon film are formed on a single crystalline silicon substrate, the formed polycrystalline silicon film is patterned by known photolithography, and the used resist pattern is ashed. After removal, the pattern of the formed polycrystalline silicon film is used as a mask, and etching is performed with a hydrofluoric acid aqueous solution so that a beam structure pattern is formed on the SiO ₂ film. After a predetermined pattern was formed on the single crystal silicon substrate in this way, the etching solution was washed away with water, the water adhering to the substrate was replaced with ethanol, and the surface was covered with ethanol. The silicon substrate in a state is carried onto the substrate mounting table 202 of the supercritical processing apparatus shown in FIGS. 1, 2, and 3, and the container upper part 100 (lid part 101) is placed on the container lower part 200 (container structure 201). ) And the processing space 204 is sealed. In the initial state, the interiors of the space 103 and the space 203 are in a state of about 5 Pa due to exhaust of a diaphragm pump (not shown).

  Next, in a state where liquefied carbon dioxide is supplied from the liquefied gas supply pipe 104, the opening and closing of the valve 106 and the valve 107 is controlled, and introduction and discharge of the liquefied carbon dioxide into the space 103 are repeated, It is set as the state cooled to 10 degrees C or less. Similarly, in the state in which liquefied carbon dioxide is supplied from the liquefied gas supply pipe 206, the opening and closing of the valve 208 and the valve 209 are controlled, and the introduction and discharge of the liquefied carbon dioxide into the space 203 are repeated, so that the substrate mounting table 202 is provided. Is cooled to 10 ° C. or lower. The time required for these cooling is 1-2 minutes.

  Subsequently, by introducing (pressure feeding) liquefied carbon dioxide from the supercritical material supply pipe 211, the inside of the sealed processing space 204 is filled with liquefied carbon dioxide at a pressure of about 8 MPa. For example, in the state where liquefied carbon dioxide is being pumped, the opening of the valve 214 is controlled and the liquefied carbon dioxide in the processing space 204 is gradually discharged, and the internal pressure of the processing space 204 is about 8 MPa. You should make it. As described above, by maintaining the state where the pressure is 8 MPa inside the processing space 204 and the liquefied carbon dioxide is introduced and discharged for a predetermined time, the ethanol adhering to the surface of the silicon substrate becomes liquefied carbon dioxide. The state is replaced.

  Next, the liquefied carbon dioxide inside the space 103 and the space 203 is discharged, and the inside of the space 103 and the space 203 is brought to a state of about 5 Pa by exhaust of a diaphragm pump (not shown). Subsequently, by operating the heating mechanism 205 to heat the substrate mounting table 202, the temperature of the silicon substrate mounted thereon is set to 40 ° C. By this heating, the liquefied carbon dioxide in contact with the silicon substrate is also heated to 40 ° C., and becomes a supercritical state. The state described above is reached in about 2 minutes after the start of heating. Next, the valve 213 is closed and the valve 214 is opened, so that the carbon dioxide that has reached the supercritical state is immediately discharged, and the processing space 204 is brought to atmospheric pressure. At this time, the operation of the heating mechanism 205 is stopped.

  In addition, after the above-described discharging operation, the opening and closing of the valve 106 and the valve 107 are controlled while the liquefied carbon dioxide is supplied from the liquefied gas supply pipe 104 again, and the introduction and discharge of the liquefied carbon dioxide into the space 103 is performed. The top plate 103 is cooled to 10 ° C. or lower. Similarly, in the state in which liquefied carbon dioxide is supplied from the liquefied gas supply pipe 206, the opening and closing of the valve 208 and the valve 209 are controlled, and the introduction and discharge of the liquefied carbon dioxide into the space 203 are repeated, so that the substrate mounting table 202 is provided. Is cooled to 10 ° C. or lower. In this state, the container upper part 100 is separated from the container lower part 200, and the silicon substrate is unloaded from the substrate mounting table 202. As a result, a good beam structure pattern can be obtained. Further, since the top plate 103 and the substrate mounting table 202 are cooled to room temperature or lower when the substrate is carried out, it is possible to immediately start processing the next substrate to be processed.

[Processing method example 2]
Next, another example of the processing method using the above-described supercritical processing apparatus will be described in detail. First, an electron beam positive resist (ZEP-7000: manufactured by Nippon Zeon Co., Ltd.) is applied on a silicon substrate to form a resist film having a thickness of about 500 nm. Next, the resist film is patterned by known electron beam lithography to form a resist pattern having a width of 50 to 300 nm. In this patterning, normal hexyl acetate was used for development, and rinsing was performed using 2-propanol.

  After the resist pattern is formed as described above, the silicon substrate wet with the rinse liquid is carried onto the substrate mounting table 502 of the supercritical processing apparatus shown in FIG. In the initial state, the top plate 402 is cooled to 20 ° C. or less by the Peltier element 404, and the substrate mounting table 502 is also cooled to 20 ° C. or less by the Peltier element 505. In this state, the container upper part 400 (lid part 401) is crowned on the container lower part 500 (container structure 501) so that the processing space 506 is sealed.

  Next, by introducing (pressure feeding) liquefied carbon dioxide from the supercritical material supply pipe 511, the inside of the sealed processing space 506 is filled with liquefied carbon dioxide having a pressure of about 8 MPa. For example, in a state where liquefied carbon dioxide is being pumped, the opening of the valve 514 is controlled to gradually discharge the liquefied carbon dioxide in the processing space 506, and the internal pressure of the processing space 506 is about 8 MPa. You should make it. Thus, by maintaining the state where the pressure is 8 MPa in the processing space 506 and the liquefied carbon dioxide is introduced and discharged for a predetermined time, the 2-propanol attached to the surface of the silicon substrate is liquefied. The carbon is substituted.

  Subsequently, a current is supplied so that the Peltier element 404 and the Peltier element 505 are in a heated state, and the top plate 402 and the substrate mounting table 502 are heated to 40 ° C. or higher. The time required for these to reach a temperature of 40 ° C. or higher is about 90 seconds. By this heating, the carbon dioxide in the processing space 506 becomes a supercritical state. In this way, after the carbon dioxide in the processing space 506 is brought into the supercritical state, immediately after the valve 513 is closed and the valve 514 is opened, the fluid inside the processing space 506 is discharged, It is assumed that the internal pressure of the processing space 506 is reduced to about atmospheric pressure.

  Subsequently, the state of the current applied to the Peltier element 404 and the Peltier element 505 is switched to a cooling state, and the top plate 402 and the substrate mounting table 502 are cooled. In this state, the container upper portion 400 is moved to the container lower portion. The substrate is removed from the substrate 500 and unloaded from the substrate mounting table 502. By the above supercritical drying treatment, the resist pattern formed on the substrate is formed without falling down. Moreover, the top plate 402 and the substrate mounting table 502 are cooled to room temperature or less within 5 minutes, and the next processing can be performed immediately after taking out the substrate.

[Processing method example 3]
Next, another example of the processing method using the above-described supercritical processing apparatus will be described in detail. Hereinafter, a processing example using the supercritical processing apparatus shown in FIG. 7 will be described. First, a 300 nm thick SiO ₂ film and a 600 nm thick polycrystalline silicon film are formed on a single crystalline silicon substrate, the formed polycrystalline silicon film is patterned by known photolithography, and the used resist pattern is ashed. After removal, the pattern of the formed polycrystalline silicon film is used as a mask, and etching is performed with a hydrofluoric acid aqueous solution so that a beam structure pattern is formed on the SiO ₂ film.

After etching, the substrate is washed with water, and subsequently the substrate wet with water is accommodated in the substrate holder 801, and a fluorine compound in which 5% ethanol is added to HCF ₂ CF ₂ OCH ₂ CF ₃ The mixed liquid is introduced and vibration is applied. Thus, the water adhering to the substrate is replaced with the fluorine compound mixed liquid, and the water is separated onto the fluorine compound mixed liquid in the substrate holder 801 due to the difference in specific gravity. After removing the separated water from the inside of the substrate holder 801, the substrate holder 801 is carried into the processing space 706 of the lower portion 700 of the container, and the upper portion 400 (lid portion 401) of the container is placed on the lower portion 700 (container structure 701). ) So that the processing space 706 is sealed.

Next, in this state, the induction heating element 705 is operated so that the substrate holder 801 is heated, and the substrate holder 801 is heated to 200 ° C. or higher. Further, the opening degree of the pressure control valve 712 is controlled so that the inside of the processing space 706 is about 3 MPa. In addition, the top plate 402 is heated to about 150 ° C. by operating the Peltier element 404 in a heated state. As a result, HCF ₂ CF ₂ OCH ₂ CF ₃ accommodated in the substrate holder 801 is vaporized, the inside of the processing space 706 is filled with the gas of HCF ₂ CF ₂ OCH ₂ CF ₃ , and the processing space 706 is also filled. The pressure of HCF ₂ CF ₂ OCH ₂ CF ₃ vaporized inside becomes about 3 MPa. As a result, the processing space inside 706 becomes a critical condition of the _{HCF 2 CF 2 OCH 2 CF 3} , HCF 2 CF 2 OCH 2 CF 3 becomes a supercritical state. The time required for these is several minutes.

As described above, the inside of the processing space 706 is filled with the supercritical HCF ₂ CF ₂ OCH ₂ CF ₃ , and the silicon substrate is immersed in the supercritical HCF ₂ CF ₂ OCH ₂ CF ₃ . It is assumed that Then, immediately after the pressure control valve 712 is opened, the fluid in the processing space 706 is discharged, and the pressure in the processing space 706 is reduced to about atmospheric pressure. As a result, the beam structure pattern made of the SiO ₂ film formed on the silicon substrate is dried without forming a gas-liquid interface, and a good beam structure pattern is obtained without deformation. be able to. Thereafter, the substrate holder 801 is moved to an external cooling table at 10 ° C. for cooling. Thus, the substrate holder 801 is cooled to about room temperature in about 10 minutes. Moreover, the top plate 402 is rapidly cooled by operating the Peltier element 404 in the cooled state. As a result, the top plate 402 is cooled to about room temperature within 10 minutes, and the next substrate can be immediately processed.

In the processing method example 1 and the processing method example 2, carbon dioxide is used as the supercritical substance, but the present invention is not limited to this. For example, any substance such as CHF ₃ or N ₂ O that is a gas at normal temperature (20 to 25 ° C.) and atmospheric pressure and is in a supercritical state at 200 ° C. or less can be used. Further, in the processing method example 3, HCF ₂ CF ₂ OCH ₂ CF ₃ is used as a supercritical material, but the present invention is not limited to this. For example, CF ₃ CF ₂ CH ₂ OCHF ₂ , CF ₃ CF ₂ OCH ₂ CF ₃ , C ₃ F ₇ OCH ₃ , CHF ₂ CF ₂ OCH ₂ CF ₃ , CF ₃ CHFCF ₂ OCH ₂ CF ₃ , CF ₃ CHFOCHF ₂ , CF ₃ CHFCF ₂ CH ₂ OCHF ₂ , CF ₃ CHFCF ₂ OCH ₂ CF ₂ Use hydrofluoroethers such as CF ₃ and CF ₃ CHFCF ₂ OCH ₂ CF ₂ CHF ₂ , hydrofluoroesters such as CHF ₂ COOCH ₂ CH ₃ and (CF ₃ ) ₂ CHCOOCH ₃ , and fluorinated hydroxy acid compounds thereof You may do it.

  Further, in the processing method example 3, the substrate holder is heated by induction heating, but is not limited to this, and other heating methods such as a method of circulating hot water or steam or a resistance heating method are used. It may be.

  In the above description, supercritical drying has been described as an example of supercritical processing. However, the present invention is not limited to this, and the above-described supercritical processing apparatus can be used for other processing using a supercritical fluid. Needless to say, it can be done.

It is sectional drawing which shows typically the structural example of the supercritical processing apparatus in embodiment of this invention. It is sectional drawing which shows typically the structural example of the supercritical processing apparatus in embodiment of this invention. It is sectional drawing which shows typically the structural example of the supercritical processing apparatus in embodiment of this invention. It is sectional drawing which shows typically the structural example of the other supercritical processing apparatus in embodiment of this invention. It is sectional drawing which shows typically the structural example of the other supercritical processing apparatus in embodiment of this invention. It is sectional drawing which shows typically the structural example of the other supercritical processing apparatus in embodiment of this invention. It is sectional drawing which shows typically the structural example of the other supercritical processing apparatus in embodiment of this invention. It is sectional drawing which shows typically the structural example of the other supercritical processing apparatus in embodiment of this invention. It is sectional drawing which shows typically the structural example of the other supercritical processing apparatus in embodiment of this invention. It is sectional drawing which shows typically the example of a partial structure of the other supercritical processing apparatus in embodiment of this invention. It is sectional drawing which shows typically the example of a partial structure of the other supercritical processing apparatus in embodiment of this invention. It is sectional drawing which shows a partial structure of the conventional supercritical processing apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 100 ... Container upper part, 101 ... Cover part, 102 ... Top plate, 103 ... Space, 104 ... Liquefied gas supply piping, 105 ... Liquefied gas discharge piping, 106, 107 ... Valve, 200 ... Container lower part, 201 ... Container structure, 202 ... Substrate mounting table, 203 ... Space, 204 ... Processing space, 205 ... Heating mechanism, 206 ... Liquefied gas supply pipe, 207 ... Liquefied gas discharge pipe, 208, 209 ... Valve, 211 ... Supercritical substance supply pipe, 212 ... Discharge piping, 213, 214 ... valve.

Claims (11)

A lower part of the container having a processing space in which a substrate to be processed is stored;
An upper part of the container that is bonded onto the lower part of the container to seal the processing space;
A top plate disposed on the processing space side above the vessel;
An upper space formed between the top plate and the upper part of the container;
A supercritical material introduction means for introducing a supercritical material that becomes a supercritical state by setting the critical condition into the processing space;
Discharging means for discharging the fluid inside the processing space;
A supercritical processing apparatus comprising: at least a heating unit configured to heat the inside of the processing space. The supercritical processing apparatus according to claim 1,
A supercritical processing apparatus comprising: a top plate temperature control means for controlling the temperature of the top plate disposed in the upper space. In the supercritical processing apparatus according to claim 2,
The supercritical processing apparatus, wherein the top plate temperature control means is a liquefied gas introduced into the upper space in order to cool the temperature of the top plate. In the supercritical processing apparatus according to claim 2,
The top plate temperature control means is configured by a Peltier element. In the supercritical processing apparatus according to claim 4,
The supercritical processing apparatus, wherein the heating means includes the top plate temperature control means. In the supercritical processing apparatus according to any one of claims 1 to 5,
A substrate mounting table disposed on the processing space side at the bottom of the container;
A supercritical processing apparatus comprising: a lower space formed between the substrate mounting table and the lower part of the container. The supercritical processing apparatus according to claim 6, wherein
A supercritical processing apparatus comprising: a mounting table temperature control unit configured to control the temperature of the substrate mounting table disposed in the lower space. The supercritical processing apparatus according to claim 7,
The supercritical processing apparatus, wherein the mounting table temperature control means is a liquefied gas introduced into the lower space in order to cool the temperature of the substrate mounting table. The supercritical processing apparatus according to claim 7 or 8,
The mounting table temperature control means includes one that heats the substrate mounting table by resistance heating. The supercritical processing apparatus according to claim 7,
The supercritical processing apparatus, wherein the mounting table temperature control means includes a Peltier element. In the supercritical processing apparatus according to claim 9 or 10,
The supercritical processing apparatus, wherein the heating means includes the mounting table temperature control means.

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