JP2013201302A - Substrate processing apparatus and substrate processing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To remove a liquid sticking to a substrate, without damaging a pattern provided on the substrate, under an environment of a pressure which is lower than a pressure required for realizing a supercritical state.SOLUTION: An IPA liquid sticking to a surface of a substrate W is replaced with a liquid carbon dioxide LC, and then, the liquid carbon dioxide LC is phase-transformed to a solid carbon dioxide SC (solidification step), and further, the solid carbon dioxide is sublimated to carbon dioxide gas. Thus, no capillary force acts between patterns, and the substrate W can be dried while preventing falling of a pattern on the substrate surface. Further during the solidification step, normal temperature nitrogen gas GNn having a partial pressure equal to or more than the pressure of triple points of the carbon dioxide is supplied into a dry processing chamber 31 and is pressurized. Thus, a phase change can be stabilized when the liquid carbon dioxide LC on the substrate W is solidified, resulting in improved reliability of sublimation drying.

Description

  The present invention relates to a substrate processing apparatus and substrate processing for removing liquid adhering to various substrates (hereinafter simply referred to as “substrate”) such as semiconductor substrates, glass substrates for flat panel displays, optical disk substrates, solar cell panels and the like. It is about the method.

  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. For example, in development processing in photolithography, a chemical solution such as a developer is applied to a substrate on which a pattern has been transferred by exposure, and then cleaning with a rinsing liquid is performed to remove the chemical solution from the substrate. .

  However, in recent years, the pattern formed on the substrate surface tends to become finer. For this reason, when the liquid adhering to the substrate is removed and dried, the surface tension (capillary force) acting on the boundary surface between the liquid that has entered the fine structure of the pattern and the gas in contact with the liquid is adjacent in the pattern. There was a problem of pulling the protruding parts to collapse.

  Therefore, in order to prevent the collapse of the pattern due to such capillary force, after supplying carbon dioxide in the supercritical state to the pattern formed on the substrate surface, the technology is used to dry the substrate surface by vaporizing it. Has been proposed (see, for example, Patent Document 1).

JP 2008-72118 A

  However, as disclosed in Patent Document 1, even in the case of carbon dioxide that is relatively easy to realize the supercritical state, a high pressure environment of 73 atm or more must be provided in order to create the supercritical state. A device that realizes and maintains the above is indispensable. And a great deal of cost is required to provide an apparatus that satisfies this requirement.

  The present invention has been made in view of the above problems, and removes the liquid adhering to the substrate without damaging the pattern provided on the substrate under a pressure environment lower than the pressure necessary for realizing the supercritical state. It is an object of the present invention to provide a substrate processing apparatus and a substrate processing method that can be used.

  In order to achieve the above object, the substrate processing method according to the present invention supplies a sublimation material to a processing chamber containing a substrate to which a liquid is attached, and replaces the liquid on the substrate with a liquid sublimation material, and a processing step A solidification step of solidifying the liquid sublimation material on the substrate while pressurizing the chamber to a pressure higher than the triple point of the sublimation material, and a removal step of sublimating the solidified sublimation material and removing it from the substrate. It is said.

  In order to achieve the above object, a substrate processing apparatus according to the present invention includes a processing chamber for storing a substrate to which a liquid is attached, and a replacement for supplying a sublimation material to the processing chamber and replacing the liquid on the substrate with a liquid sublimation material. A solidification means for solidifying the liquid sublimation material on the substrate, a removal means for sublimating the solidified sublimation material to remove it from the substrate, and a solidification of the sublimation material in the treatment chamber by the solidification means. And pressurizing means for pressurizing to a pressure higher than the triple point of the sublimation material.

  In the invention thus configured (substrate processing method and substrate processing apparatus), the liquid sublimation material replaced with the liquid adhering to the substrate is solidified and then sublimated and removed from the substrate. For this reason, substrate drying is performed and removed while preventing capillary force from acting on the substrate. However, if the phase change follows the path of liquid phase-gas phase-solid phase when solidifying the liquid sublimation material, a capillary force acts when changing from the liquid phase to the gas phase. Therefore, in the present invention, during the solidification, the processing chamber is pressurized to a pressure higher than the triple point of the sublimation material, the liquid sublimation material is solidified without going through the gas phase, and it is ensured that the capillary force acts on the substrate. To prevent.

  Here, as one of specific means for pressurizing the processing chamber to a pressure higher than the triple point of the sublimation material, it is desirable to supply a gas having a partial pressure higher than the triple point of the sublimation material to the processing chamber. The liquid sublimation material is solidified without passing through the gas phase by cooling the liquid sublimation material on the substrate while pressurizing the processing chamber in this way.

  Moreover, about the cooling temperature, you may set to the temperature below the triple point of a sublimation material, for example. In order to sublimate the solidified sublimation material, for example, the processing chamber may be depressurized to a pressure lower than the triple point of the sublimation material, and the temperature of the processing chamber may be raised while maintaining the pressure to sublimate the sublimation material. The reduced pressure value at this time may be set to atmospheric pressure, for example, and the subsequent process can be performed smoothly by returning to atmospheric pressure.

  Furthermore, the cooling temperature may be set to a temperature not higher than the triple point of the sublimation material and not lower than the sublimation point of the sublimation material at atmospheric pressure. In this case, the sublimation material can be sublimated only by reducing the pressure in the processing chamber to atmospheric pressure. That is, the removal process can be performed only by pressure control, and temperature control is not necessary.

  As described above, according to the present invention, the liquid sublimation material replaced with the liquid attached to the substrate is solidified and then sublimated and removed from the substrate. For this reason, it is possible to remove the liquid from the substrate while preventing the capillary force from acting on the substrate. In addition, when the liquid sublimation material on the substrate is solidified in the processing chamber, the processing chamber is pressurized to a pressure higher than the triple point of the sublimation material, so that the liquid sublimation material is solidified via the gas phase. It is possible to reliably prevent the capillary force from acting on the substrate.

It is a top view which shows the layout of the substrate processing system equipped with 1st Embodiment of the substrate processing apparatus concerning this invention. It is a figure which shows the cross-section of the substrate drying apparatus which is 1st Embodiment of the substrate processing apparatus concerning this invention. It is a block diagram which shows the electrical structure of the board | substrate drying apparatus shown in FIG. It is a phase diagram of carbon dioxide showing change of temperature and pressure in a dry processing chamber (processing room) in a 1st embodiment of the present invention. It is a figure which shows typically the substitution process in the substrate processing method concerning 1st Embodiment of this invention. It is a figure which shows typically the solidification process in the substrate processing method concerning 1st Embodiment of this invention. It is a figure which shows typically the removal process in the substrate processing method concerning 1st Embodiment of this invention. It is a figure which shows typically the removal process in the substrate processing method concerning 1st Embodiment of this invention. It is a figure which shows typically the board | substrate temperature rising process in the substrate processing method concerning 1st Embodiment of this invention. It is a figure which shows the phase change path | route of the sublimation material in 2nd Embodiment of the substrate processing method concerning this invention.

A. First Embodiment FIG. 1 is a plan view showing a layout of a substrate processing system equipped with a first embodiment of a substrate processing apparatus according to the present invention. FIG. 2 is a view showing a sectional structure of the substrate drying apparatus which is the first embodiment of the substrate processing apparatus according to the present invention. FIG. 3 is a block diagram showing an electrical configuration of the substrate drying apparatus shown in FIG. The substrate processing system 1 is a system used in the development process of a semiconductor substrate W used as a material for a semiconductor device. The substrate processing system 1 mainly includes a substrate station 5, a substrate transfer device 20, a substrate developing device 10, and a substrate drying device 30. Equipped with. In the following description, the substrate processing system 1 has a form in which the substrates W are processed in a single wafer type, but is not limited to such a form, and may be in a form in which processing is performed in a batch type. .

  The substrate station 5 is partitioned from the substrate developing device 10 and the substrate drying device 30 by partition walls. In the substrate station 5, a plurality of cassettes 51 (three cassettes 51a, 51b, and 51c in this embodiment) can be placed. Each cassette 51 accommodates a plurality of substrates W that have already been subjected to exposure processing in a stacked state. Then, the substrate W in the cassette 51 is taken out by the substrate transport device 20, sequentially transported to the substrate developing device 10 and the substrate drying device 30, and finally returned to the cassette 51.

  In the substrate transfer apparatus 20, the base end portions of the two extendable arms 21 a and 21 b are attached to the apparatus main body 22 so as to be rotatable around the vertical axis. Further, hands 23a and 23b are supported at the distal ends of the telescopic arms 21a and 21b, respectively, so as to be rotatable about the vertical axis. Then, a driving mechanism unit (not shown) independently expands and contracts and swings the telescopic arms 21a and 21b with respect to the apparatus main body 22, and rotates the hands 23a and 23b with respect to the telescopic arms 21a and 21b. As described above, the substrate transport apparatus 20 can efficiently transport the two substrates W by independently driving the two substrate transport units.

  The substrate developing device 10 is a device that sequentially performs development processing, rinsing processing, and replacement processing on the substrate W taken out from the cassette 51 by the substrate transport device 20, that is, the substrate W that has already undergone exposure processing. The basic configuration of the substrate developing apparatus 10 is well known in the art and is configured as follows. That is, the substrate developing apparatus 10 has a spin chuck that rotates about the vertical axis while holding the substrate W loaded by the substrate transport apparatus 20. A first discharge nozzle is provided above the spin chuck, and an alkaline aqueous developer or the like is supplied from the first discharge nozzle to the substrate W held by the spin chuck to perform development processing. Depending on the type of photoresist applied on the upper surface of the substrate W, an organic developer such as butyl acetate may be used.

  In addition to the first discharge nozzle, the substrate developing apparatus 10 has a second discharge nozzle that discharges a rinsing liquid and an IPA (isopropyl alcohol) liquid toward the substrate W held by the spin chuck. ing. In the present embodiment, since the development process is performed using an alkaline aqueous solution as a developer, pure water, DIW (deionized water) or the like is used as a rinse solution. However, as will be described below, the substrate drying apparatus 30 is an apparatus that performs sublimation drying using carbon dioxide as the “sublimation material” of the present invention, and therefore transports the substrate W to which DIW has adhered to the substrate drying apparatus 30 as it is. In this embodiment, as a final process in the substrate developing apparatus 10, an IPA liquid having a physical property lower than the rinsing liquid is supplied to remove the rinsing liquid from the substrate W. The substrate W is kept wet with the IPA solution.

  The substrate drying apparatus 30 is an apparatus for removing the IPA liquid adhering to the substrate W and drying the substrate W. The substrate drying apparatus 30 mainly includes a drying processing chamber 31, a carbon dioxide supply mechanism 32, a first nitrogen gas supply mechanism 33, a liquid nitrogen supply mechanism 34, a second nitrogen gas supply mechanism 44, and a discharge mechanism 35.

  The drying processing chamber (processing chamber) 31 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 disposed on the lower side of the opening of the upper member 313, and constitutes an internal space of the drying processing chamber 31 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 drying processing chamber 31 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. 3) operates to open the drying processing chamber 31 in response to a chamber opening command from the control unit 50 (FIG. 3) that controls the entire apparatus, and the substrate processing apparatus 10 starts the drying processing chamber. It is possible to carry in the undried substrate W to 31 and carry out the dried substrate W from the drying processing chamber 31. On the other hand, the chamber opening / closing mechanism 317 is operated in response to a chamber closing command from the control unit 50 to close the drying processing chamber 31, so that the upper member 313 and the lower member 314 are in close contact with each other via the sealing material 315. Then, the drying processing chamber 31 is sealed. Sublimation drying is performed inside the dry processing chamber 31 thus sealed.

  A mounting table 39 on which the substrate W is mounted is provided inside the drying processing chamber 31. The substrate W is held on a substantially horizontal state by being placed on the upper surface of the placement table 39. A suction port (not shown) is provided on the upper surface of the mounting table 39, and the substrate W is held on the mounting table 39 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 36 protrudes downward (-Z) at the center of the lower surface of the mounting table 39. The support shaft 36 is inserted through the lower member 314 via a high pressure seal rotation introducing mechanism 37. Further, the rotating shaft 371 of the high pressure seal rotation introducing mechanism 37 is connected to the rotating mechanism 372. For this reason, when the rotation mechanism 372 is actuated according to the rotation command from the control unit 50, the substrate W is rotated around the support shaft 36 at an arbitrary number of rotations together with the mounting table 39.

  A first introduction pipe 40 is attached to the drying processing chamber 31. More specifically, as shown in FIG. 2, the first introduction pipe 40 is attached so as to penetrate the upper wall 311 of the upper member 313, and the lower end portion thereof is connected to the internal space of the drying processing chamber 31. On the other hand, the upper end of the first introduction pipe 40 is divided into a T-shape, one of which is connected to the carbon dioxide supply mechanism 32 and the other is connected to the first nitrogen gas supply mechanism 33. Among these, the carbon dioxide supply mechanism 32 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 40, and this pipe 322. And a valve 323 interposed therebetween. The first nitrogen gas supply mechanism 33 includes a first nitrogen gas supply unit 331 that supplies nitrogen gas, and a pipe 332 that connects the first nitrogen gas supply mechanism 33 to the other of the upper end portions of the first introduction pipe 40. And a valve 333 inserted in the pipe 332. Thus, in the present embodiment, the first introduction pipe 40 functions as two common introduction pipes. In other words, the first introduction pipe 40 functions as an introduction path for introducing the carbon dioxide gas supplied from the carbon dioxide supply mechanism 32 into the drying processing chamber 31 and is a room temperature nitrogen gas supplied from the first nitrogen gas supply mechanism 33. Also functions as an introduction path for introducing the liquid into the drying processing chamber 31.

  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 50, the carbon dioxide gas from the carbon dioxide supply unit 321 passes through the first introduction pipe 40. And supplied to the drying processing chamber 31. As will be described later, since the drying process chamber 31 is kept sealed during sublimation drying, the introduction of carbon dioxide gas is started soon after the introduction of carbon dioxide gas, and the inside of the drying process chamber 31 is oxidized by the accumulation of the introduced carbon dioxide gas. The pressure is higher than the pressure at which carbon condenses. For this reason, carbon dioxide is supplied in the vapor phase into the drying processing chamber 31 in the very initial stage, but liquid carbon dioxide is soon supplied onto the substrate W. In other words, the initial stage of supply of carbon dioxide is a stage of increasing the pressure in the drying process chamber 31 by vapor phase 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 substance for removing the IPA residual liquid from the substrate W according to the principle described later. Such materials used to remove liquids are also referred to as “sublimation materials”.

  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 50, room temperature nitrogen gas from the first nitrogen gas supply mechanism 33 is converted into the first introduction pipe 40. Is supplied to the drying processing chamber 31. In addition, it is good also as a structure by which the high temperature nitrogen gas heated by providing a heater in the piping 332 is supplied. Moreover, you may comprise so that normal temperature nitrogen gas and high temperature nitrogen gas may be supplied selectively.

  The liquid nitrogen supply mechanism 34 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 drying processing chamber 31. One end of the second introduction pipe 341 inside the drying processing chamber 31 faces the lower surface of the mounting table 39. 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 accordance with a valve opening command from the control unit 50, liquid nitrogen is supplied into the drying processing chamber 31 from the second introduction pipe 341.

  Further, in the lower member 314 constituting the drying processing chamber 31, the third introduction pipe 441 penetrates the lower member 314, and the upper end of the third introduction pipe 441 extends to the inside of the drying processing chamber 31, similarly to the second introduction pipe 341. It is installed. The third introduction pipe 441 constitutes a second nitrogen gas supply mechanism 44 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 drying processing chamber 31 faces the lower surface of the mounting table 39. 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 44 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 a valve opening command from the control unit 50, the high-temperature nitrogen gas heated by the heater 444 is supplied into the drying processing chamber 31. 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 38 is provided above the inside of the drying processing chamber 31. The fluid dispersion mechanism 38 is provided with a plurality of flow holes 382 penetrating vertically with respect to a disc-shaped closing plate 381 fitted inside the drying processing chamber 31. Thereby, carbon dioxide and nitrogen gas supplied to the drying processing chamber 31 via the first introduction pipe 40 are rectified, and a uniform fluid supply to the upper surface of the substrate W is possible.

  A discharge mechanism 35 is connected to the lower member 314 constituting the drying processing chamber 31. The discharge mechanism 35 includes a plurality of discharge pipes 351, pipes 354, and valves 353. In the present embodiment, as shown in FIG. 2, a plurality of inclined surfaces are formed on the upper surface of the lower member 314, and a valley 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 drying processing chamber 31 through the discharge pipe 351. Further, the gas in the drying process chamber 31 can also be discharged out of the drying process chamber 31 via the discharge pipe 351.

  The liquid and gas discharged from the drying chamber 31 through the discharge pipe 351 are reduced in pressure by passing through the valve 353, and then sent to the separation tank 355, where they are 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 61 (FIG. 3) and a pressure sensor 62 (FIG. 3) are provided in the drying processing chamber 31, and the temperature and pressure in the drying processing chamber 31 can be measured by these sensors 61 and 62, respectively. It has become. Temperature data and pressure data measured by these sensors 61 and 62 are input to the control unit 50. And the control part 50 can adjust the temperature and pressure in the drying process chamber 31 by adjusting the opening and closing and the opening degree of the valves 323, 333, 343, 443, and 353 according to these measurement results. The configuration of the control unit 50 as hardware is the same as that of a general computer, and is controlled by controlling each unit of the substrate drying apparatus 30 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.

  Next, after describing the outline operation of the substrate processing system 1, a sublimation drying method by the substrate drying apparatus 30 which is a characteristic part of the present invention will be described with reference to FIGS.

  In the substrate processing system 1, one unprocessed substrate W is taken out from the cassette 51 placed in the substrate station 5 by the substrate transport device 20 and transported to the substrate developing device 10. In the substrate developing apparatus 10, development processing is performed with an alkaline aqueous solution that is a developer. In addition, the substrate W after the development processing is rinsed with DIW, which is a rinse solution. Further, the IPA liquid as a replacement liquid is supplied to the substrate W immediately after the rinsing process in which DIW remains, and the DIW adhering to the substrate W is rinsed from the substrate W to be completely replaced with the IPA liquid. .

  When a series of processing (development-rinse-IPA replacement) in the substrate developing device 10 is completed, the substrate transport device 20 takes out the developed substrate W from the substrate developing device 10 and transports it to the substrate drying device 30. At this time, the substrate W is transported in a state where the surface of the substrate W is completely covered with the IPA liquid that is the replacement liquid. At the time of this transfer, the drying processing chamber 31 of the substrate drying apparatus 30 is opened by the chamber opening / closing mechanism 317, and the substrate transfer apparatus 20 places the substrate W on the mounting table 39 of the substrate drying apparatus 30.

  Then, the substrate drying apparatus 30 removes the IPA liquid from the substrate W by executing a series of processes (replacement step-solidification step-removal step-substrate heating step) according to the program in the memory as described in detail below. To dry the substrate W. Finally, the substrate transport apparatus 20 takes out the dried substrate W from the substrate drying apparatus 30 and returns it to the cassette 51.

  FIG. 4 is a phase diagram of carbon dioxide showing changes in temperature and pressure in the drying processing chamber (processing chamber) in the first embodiment of the present invention. FIG. 5 is a diagram schematically showing a replacement process in the substrate processing method according to the first embodiment of the present invention. FIG. 6 is a schematic diagram showing a solidification process in the substrate processing method according to the first embodiment of the present invention. FIG. 7 and FIG. 8 are diagrams schematically showing a removal step in the substrate processing method according to the first embodiment of the present invention, and FIG. 9 is a substrate processing according to the first embodiment of the present invention. It is a figure which shows typically the board | substrate temperature rising process in a method. 5 to 9, the substrate drying apparatus 30 is shown in a schematic configuration to facilitate understanding of the flow of implementation, but in actuality, the substrate drying apparatus 30 shown in FIG. 2 is used. The process is performed by. Moreover, the vertical axis | shaft of FIG. 4 is a logarithmic scale.

  When the substrate W is mounted on the mounting table 39 of the substrate drying apparatus 30 by the substrate transport apparatus 20, the control unit 50 controls each part of the substrate drying apparatus 30 as follows according to the program in the memory. Execute the process. After the loading of the substrate W into the drying processing chamber 31 is completed, the upper member 313 and the lower member 314 are fitted by the chamber opening / closing mechanism 317. At this stage, the valves 323, 333, 343, 443, and 353 are all closed, and the inside of the drying processing chamber 31 is hermetically sealed by the completion of the fitting operation. At this stage, the internal atmosphere of the drying processing chamber 31 is normal temperature and pressure.

  When the inside of the drying processing chamber 31 is sealed, the valve 323 is opened. For this reason, carbon dioxide gas supplied from the carbon dioxide supply unit 321 is supplied into the drying processing chamber 31 via the first introduction pipe 40. Further, the valve 353 is opened in response to the supply of the carbon dioxide gas. Thereby, the air in the drying process chamber 31 is exhausted from the valve 353, and the inside of the drying process chamber 31 is replaced with carbon dioxide gas.

  When a predetermined time elapses, the valve 353 is closed and the inside of the drying processing chamber 31 is returned to a sealed state. On the other hand, since the valve 323 remains open, the supply of carbon dioxide gas to the drying processing chamber 31 is continued. For this reason, the pressure in the drying processing chamber 31 gradually rises, and eventually the temperature inside the drying processing chamber 31 is 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 drying processing chamber 31 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 drying processing chamber 31.

  As described above, the carbon dioxide supplied from the carbon dioxide supply unit 321 into the drying process chamber 31 is supplied as a gas at the start of supply, and thereafter, the pressure in the drying process chamber 31 is reduced to 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. Therefore, the liquid carbon dioxide LC is substantially supplied to the drying processing chamber 31 as shown in FIG.

Such a region where carbon dioxide exists as a liquid is shown in FIG.
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 39 to rotate. As a result, the IPA liquid (not shown in FIG. 5) and the liquid carbon dioxide LC 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 LC flow down to the bottom surface in the drying processing chamber 31 (the top surface of the lower wall 316) and are discharged out of the drying processing chamber 31 through the discharge pipe 351. As described above, in this embodiment, by rotating the substrate W, the IPA liquid is efficiently replaced with the liquid carbon dioxide LC.

  Further, the liquid carbon dioxide LC supplied from the first introduction pipe 40 into the drying processing chamber 31 is supplied uniformly to the surface of the substrate W by the fluid dispersion mechanism 38 although not shown in FIG. Is done. Since the surface tension of the liquid carbon dioxide LC is smaller than the surface tension of the IPA liquid, the liquid carbon dioxide LC easily enters the gap between the patterns formed on the surface of the substrate W. Such supply of the liquid carbon dioxide LC is performed until a predetermined time elapses so that the surface of the substrate W is completely replaced with the liquid carbon dioxide LC. Thus, in the state (A) in FIG. 4, the IPA liquid adhering to the substrate W is replaced with the liquid carbon dioxide LC (substitution step).

  Following this replacement step, the valve 323 is closed and the supply of the liquid carbon dioxide LC into the drying process chamber 31 is stopped. Further, the valve 353 is closed, the inside of the drying processing chamber 31 is returned to the sealed state, and the non-supercritical state is maintained. Subsequently, the valve 343 is opened, and liquid nitrogen LN is supplied into the drying processing chamber 31 and sprayed directly on the lower surface of the mounting table 39. For this reason, the temperature of the mounting table 39 rapidly decreases, and the substrate W held on the mounting table 39 is cooled. That is, the mounting table 39 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 nitrogen gas GNn having a partial pressure equal to or higher than the triple point pressure of carbon dioxide, which is a sublimation material, is supplied into the drying processing chamber 31 through the first introduction pipe 40. As a result, even during the cooling of the substrate W by the liquid nitrogen LN, the pressure in the drying processing chamber 31 is maintained at or above the triple point pressure. Further, in this embodiment, the pressure is not only increased to the triple point or more by simply supplying the nitrogen gas GNn, but the valve 353 is opened while the opening degree is adjusted, and the pressure in the drying processing chamber 31 is kept constant above the triple point. Maintained at the value.

  Thus, the pressure is kept constant at 5.1 atm or higher, and the liquid carbon dioxide LC on the surface of the substrate W is solidified as the temperature is lowered (FIG. 6: solidification step). Specifically, in FIG. 4, the temperature and pressure change along a solid line connecting the state (A) and the state (B), and the temperature in the drying processing chamber 31 is lower than a predetermined temperature. Liquid carbon dioxide LC undergoes phase transition to solid carbon dioxide SC. The predetermined temperature at this time is a temperature determined based on a melting curve representing the relationship between the pressure and temperature at which the liquid phase and the solid phase coexist in the pressure in the drying processing chamber 31. Thus, in this embodiment, in order to solidify the liquid carbon dioxide LC, liquid nitrogen as a refrigerant is directly supplied into the drying processing chamber 31. For this reason, heat is removed through the surface of the mounting table 39 with which the substrate W is in contact, and the substrate W can be efficiently cooled to solidify the liquid carbon dioxide LC to obtain the solid carbon dioxide SC.

  Thus, in this embodiment, carbon dioxide is used as the sublimation material, and the carbon dioxide is solidified at a temperature much lower than the freezing point of the rinse liquid (DIW). Therefore, in the substrate developing apparatus 10, there is a great technical significance in that the rinse liquid is finally replaced with the IPA liquid. This is because if the substrate W with the rinsing liquid remaining on the surface is subjected to sublimation drying, the remaining rinsing liquid (DIW) is solidified prior to the solidification of carbon dioxide, resulting in sublimation drying. The technical significance of is lost. On the other hand, for example, if the solidification temperature of the replacement liquid is −56.6 [° C.], which is the solidification temperature of carbon dioxide, as in the case of IPA liquid, the replacement liquid solidifies prior to the solidification of carbon dioxide. Can be prevented.

  Thus, after the surface of the substrate W is covered with the solid carbon dioxide SC, the valves 333 and 343 are closed and the valve 353 is completely opened. As a result, the pressure in the drying processing chamber 31 drops to 1 atmosphere, which is the atmospheric pressure (FIG. 7). At this time, the temperature in the drying processing chamber 31 further decreases due to adiabatic expansion (changes along the solid line connecting the state (B) and the state (C) in FIG. 4).

  Then, when the pressure in the drying process chamber 31 becomes atmospheric pressure, the valve 333 is opened again, and as shown in FIG. 8, the nitrogen gas GNn at room temperature is supplied from the first introduction pipe 40 into the drying process chamber 31. To be introduced. Since the inside of the drying process chamber 31 is lower than the temperature of the room temperature nitrogen gas GNn and the valve 353 is opened, the supply of the room temperature nitrogen gas GNn causes the pressure in the drying process chamber 31 to be increased. The atmospheric temperature in the drying process chamber 31 rises while maintaining the atmospheric pressure. Then, when the temperature in the drying processing chamber 31 reaches −78.5 [° C.] or higher, the solid carbon dioxide SC sublimates and changes into the carbon dioxide gas GC (in FIG. C) and temperature change along the solid line connecting state (D). Thus, the solid carbon dioxide SC is removed from the surface of the substrate W (removal step). Note that the temperature at which sublimation starts is a temperature determined based on a sublimation curve representing the relationship between the pressure and temperature at which the solid phase and the gas phase coexist in the pressure in the drying processing chamber 31. Since the carbon dioxide gas GC diffuses from the surface of the substrate W into the atmosphere, the surface of the substrate W is not attached with liquid.

  Thus, the liquid carbon dioxide LC that has permeated between the patterns of the substrate W becomes a solid state by cooling, and then undergoes a phase transition to a gas state. Therefore, since carbon dioxide does not pass through the liquid state before becoming a gas state, the capillary force peculiar to the liquid does not occur, and the collapse of the convex portion of the pattern formed on the substrate W can be prevented. . Similarly, the treatment can be performed under a low-pressure atmosphere (environment) as compared with a drying technique using a supercritical fluid that does not pass through a liquid state before a gas state. For this reason, compared with the equipment for realizing a supercritical state that requires a high-pressure environment, the apparatus cost can be reduced. In addition, since it is not necessary to wait until the high pressure environment is reached, the processing time can be shortened.

  When a series of processes (substitution process-solidification process-removal process) is performed as described above, the temperature of the substrate W tends to be lowered. In this case, since there is a temperature difference between the substrate W and the atmosphere outside the drying processing chamber 31, when the substrate W is carried out of the drying processing chamber 31 for a subsequent process, dew condensation occurs on the surface of the substrate W. May occur. Therefore, in the present embodiment, as shown in FIG. 9, in parallel with the supply of the room temperature nitrogen gas GNn from the first introduction pipe 40, the valve 443 is opened and the high temperature nitrogen gas GNh heated by the heater 444 is supplied. Spray directly onto the lower surface of the mounting table 39 from the third introduction pipe 441. As a result, the heat of the high-temperature nitrogen gas GNh is transmitted to the substrate W via the mounting table 39, so that the temperature of the substrate W is increased, and condensation on the surface of the substrate W can be prevented (substrate temperature increasing step). Note that this substrate temperature raising step is not an essential step in the substrate drying process, and may be appropriately adopted as necessary.

  As described above, in the first embodiment, after replacing the IPA liquid adhering to the surface of the substrate W with the liquid carbon dioxide LC, the liquid carbon dioxide LC is phase-transferred to the solid carbon dioxide SC, and further the solid carbon dioxide SC. Is sublimated to carbon dioxide gas GC. For this reason, the capillary force does not act between the patterns, and the substrate W can be dried while preventing the pattern on the substrate surface from collapsing.

  In addition, compared to drying technology that uses supercritical fluid that can achieve the same effect, it can be performed in a low-pressure environment, so there is no need for equipment to realize a high-pressure environment, thus reducing equipment costs. Can do. In addition, since it is not necessary to wait until the high pressure state reaches the supercritical state, the processing time can be further shortened.

  In addition, as shown in FIG. 6, during the solidification process, room temperature nitrogen gas GNn having a partial pressure equal to or higher than the triple point pressure of carbon dioxide is supplied into the drying treatment chamber 31 for pressurization. An effect is also obtained. That is, the pressure of the drying process chamber 31 is equal to or higher than the triple point pressure at the start of the coagulation process, and the drying process chamber 31 is adjusted by adjusting the opening of the valve 353 in parallel with the cooling by supplying the liquid nitrogen LN. It is theoretically possible to set the pressure inside the triple point or higher. However, in reality, it is difficult to stably control the phase change. On the other hand, in the first embodiment, as described above, the phase change when the liquid carbon dioxide LC on the substrate W is solidified can be stabilized by pressurization by the nitrogen gas supply during the solidification step, The reliability of sublimation drying can be increased.

  Furthermore, when performing a solidification process without supplying nitrogen gas, it is also conceivable to make the transition from the state (A) to the state (B) in FIG. 4 relatively far from the triple point. In this case, since the state (A) is brought closer to the supercritical state side, the above-described technical advantage (effect of reducing the apparatus cost and processing time) is reduced. On the other hand, since the first embodiment can stably control the phase change as described above, the transition from the state (A) to the state (B) in FIG. 4 is relatively close to the triple point. Compared with the case where the solidification process is performed without supplying nitrogen gas, the apparatus has an advantage in terms of apparatus cost and processing time.

  Thus, in the first embodiment, the drying processing chamber 31 corresponds to the “processing chamber” of the present invention. The carbon dioxide supply mechanism 32 corresponds to the “substitution unit” of the present invention. The liquid nitrogen supply mechanism 34 corresponds to the “coagulation means” of the present invention. Further, the discharge mechanism 35 functions as the “removing means” of the present invention. The first nitrogen gas supply mechanism 33 functions as the “pressurizing means” of the present invention.

B. Second Embodiment FIG. 10 is a diagram showing a phase change path of a sublimation material in a second embodiment of the substrate processing method according to the present invention. In the second embodiment, similarly to the first embodiment, the substrate W wetted with the IPA liquid is sublimated and dried by the substrate drying apparatus 30 shown in FIG. 2. The main difference from the first embodiment is that after the coagulation step. And the contents of the removal step. Other configurations are basically the same as those in the first embodiment. Hereinafter, the second embodiment will be described with reference to FIG.

  Also in the second embodiment, as in the first embodiment, the replacement step is executed, and the replacement of the IPA liquid with the liquid carbon dioxide LC is performed on the surface of the substrate W. Subsequently, the supply of liquid nitrogen LN to the mounting table 39 while supplying the room temperature nitrogen gas GNn having a partial pressure equal to or higher than the triple point pressure of carbon dioxide into the drying processing chamber 31 through the first introduction pipe 40. The substrate W is cooled. More specifically, while maintaining the pressure constant at 5.1 atm or higher, the temperature is higher than the sublimation point of carbon dioxide at atmospheric pressure (−78.5 [° C.]) and the temperature at the triple point (− 56.6 [° C.]) or less. That is, in FIG. 10, the temperature and pressure change along the solid line connecting the state (A) and the state (B ′), and the liquid in the stage where the temperature in the drying processing chamber 31 is lower than the predetermined temperature. Carbon dioxide LC undergoes a phase transition to solid carbon dioxide SC.

  When the solidification of the liquid carbon dioxide LC is completed in this way, the valve 333 that controls the supply of the nitrogen gas GN is closed to stop the supply of the room temperature nitrogen gas. Further, the valve 343 is closed to stop the supply of liquid nitrogen LN. This prevents the temperature in the drying processing chamber 31 from dropping below the sublimation point, is lower than the triple point temperature (−56.6 [° C.]), and is sublimation point (−78.5 [° C.]). ]) Higher than that. Thereafter, the valve 353 of the discharge mechanism 35 is completely opened. As a result, the pressure in the drying processing chamber 31 drops to 1 atmosphere, which is the atmospheric pressure. At this time, in the drying processing chamber 31, although the temperature slightly decreases due to adiabatic expansion, the pressure does not decrease to the sublimation point of carbon dioxide at atmospheric pressure (−78.5 [° C.]), and the pressure is increased between the solid phase and gas. At a stage below the sublimation curve CV representing the relationship between the pressure and temperature at which the phases coexist, the solid carbon dioxide SC sublimates and transitions to the carbon dioxide gas GC (as shown in FIG. 10). Sublimation starts when the solid line connecting the state (B ′) and the state (C ′) crosses the sublimation curve CV). Thus, the solid carbon dioxide SC is removed from the surface of the substrate W (removal step).

  In addition, following the completion of the removal step, the valve 333 is opened to supply the room temperature nitrogen gas GNn from the first introduction pipe 40 to the drying processing chamber 31 in order to prevent dew condensation in order to prevent condensation. The high temperature nitrogen gas GNh heated by the heater 444 by opening the 443 is blown directly from the third introduction pipe 441 to the lower surface of the mounting table 39.

  As described above, according to the second embodiment, not only the effects can be obtained as in the first embodiment, but also the cost required for the coagulation process can be increased by changing the state (B) to the state (B ′). Reduction and time reduction are possible. Further, the contents of the removal process can be simplified, and the cost and time required for the removal process can be reduced.

C. Others The present invention is not limited to the above-described embodiment, and various modifications can be made to the above-described one without departing from the gist thereof. For example, in the above-described embodiment, the present invention is applied to a substrate processing technique in which a developed substrate is sublimated and dried, but the scope of application is not limited thereto. That is, the present invention can be applied to all substrate processing techniques for drying a substrate W that has been wet-processed.

  In the above embodiment, as the “coagulation means” for solidifying the liquid carbon dioxide LC on the substrate W, the refrigerant is a gas, and the refrigerant gas is directly applied to the surface of the substrate W without going through the mounting table 39. It may be in the form of spraying. Regardless of whether it is a liquid or a gas, the temperature of the supplied refrigerant may be a temperature lower than the solidification temperature of carbon dioxide at the pressure in the drying processing chamber 31.

  Moreover, in the said 1st Embodiment, although the state (C) of FIG. 4 exists on the line of 1 atmosphere, if it is a pressure lower than a triple point and exists in a solid phase area | region, it may not be 1 atmosphere. However, it is preferable that the state (C) is on the line of 1 atm because pressure control becomes easy.

  In the above embodiment, carbon dioxide is used as the sublimation material. However, if the triple point (that is, the temperature and pressure in a state where the solid phase, the liquid phase and the gas phase coexist) is 1 atm or more, Other substances may be used as the sublimation material. Further, instead of the nitrogen gas supplied to the drying processing chamber 31, other inert gas can be used.

  Furthermore, in the said embodiment, although the 2nd nitrogen gas supply mechanism 44 was provided, it is not restricted to such a form. The second nitrogen gas supply mechanism 44 may not necessarily be provided. If the first nitrogen gas supply mechanism 33 is provided with a heater so as to switch between the supply of warmed nitrogen and the supply of room temperature nitrogen, it is possible to have this role.

  The present invention can be applied to all substrate processing techniques in which liquids adhering to various substrates such as semiconductor substrates, glass substrates for flat panel displays, optical disk substrates, and solar cell panels are removed from the substrates and dried.

30 ... Substrate drying apparatus (substrate processing apparatus)
31 ... Drying processing chamber (processing room)
32 ... Carbon dioxide supply mechanism (substitution means)
33 ... First nitrogen gas supply mechanism (pressurizing means)
34 ... Liquid nitrogen supply mechanism (coagulation means)
35 ... Ejection mechanism (removal means)
GNn ... Nitrogen gas LC ... Liquid carbon dioxide (liquid sublimation material)
W ... Board

Claims (8)

A substituting step of supplying a sublimation material to a processing chamber containing a substrate to which a liquid is adhered and replacing the liquid on the substrate with the liquid sublimation material;
A solidification step of solidifying the liquid sublimation material on the substrate while pressurizing the processing chamber to a pressure higher than the triple point of the sublimation material;
And a removing step of sublimating and removing the solidified sublimation material from the substrate. The substrate processing method according to claim 1,
The solidification step is a substrate processing method for cooling and solidifying the liquid sublimation material on the substrate while supplying and pressurizing a gas having a partial pressure equal to or higher than the triple point of the sublimation material to the processing chamber. The substrate processing method according to claim 2,
The solidification step is a substrate processing method in which the sublimation material is solidified by cooling to a temperature below the triple point of the sublimation material. A substrate processing method according to any one of claims 1 to 3,
The removing step is a substrate processing method in which the processing chamber is depressurized to a pressure lower than the triple point of the sublimation material, and then the processing chamber is heated to sublimate the sublimation material. The substrate processing method according to claim 4,
The substrate processing method in which the pressure lower than the triple point of the sublimation material in the removing step is atmospheric pressure. The substrate processing method according to claim 3,
The solidification step is a substrate processing method in which the sublimation material is solidified by cooling to a temperature equal to or higher than the sublimation point of the sublimation material at atmospheric pressure. The substrate processing method according to claim 6, comprising:
The removal process is a substrate processing method in which the sublimation material is sublimated by reducing the processing chamber to atmospheric pressure. A processing chamber for storing a substrate to which a liquid is attached;
Replacing means for supplying a sublimation material to the processing chamber and replacing the liquid on the substrate with the liquid sublimation material;
Solidifying means for solidifying the liquid sublimation material on the substrate;
Removing means for sublimating and removing the solidified sublimation material from the substrate;
A substrate processing apparatus, comprising: a pressurizing unit that pressurizes the processing chamber to a pressure higher than a triple point of the sublimation material when the sublimation material is solidified in the processing chamber by the solidification unit.

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