JP2011198894A - Substrate processing method and substrate processing apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a technique for obtaining a high throughput and effectively removing particles etc., for a substrate processing method and a substrate processing apparatus configured to remove a contaminant such as particles sticking on a substrate surface.SOLUTION: A liquid film is formed on an upper surface of a substrate (step S101) and after a freezing nozzle which discharges, for example, low-temperature nitrogen gas as freezing gas is scanned to freeze the liquid film (steps S102, S103), a cooling nozzle which discharges a liquid having higher cooling capability than the freezing gas, for example, nitrogen gas having a lower temperature than the freezing gas is scanned to further cool the frozen liquid film down to a lower temperature (steps S104, S105). The particles are removed thereafter together with the frozen film through rinsing processing (step S107), and the substrate is dried (step S108).

Description

  The present invention relates to a substrate processing method for removing contaminants such as particles adhering to various substrate surfaces such as a semiconductor wafer, a photomask glass substrate, a liquid crystal display glass substrate, a plasma display glass substrate, and an optical disk substrate, and the like. The present invention relates to a substrate processing apparatus.

  Conventionally, a freeze cleaning technique is known as one of the processes for removing contaminants such as particles adhering to the substrate surface. In this technique, the liquid film formed on the substrate surface is frozen, and the frozen film is removed to remove particles and the like from the substrate surface together with the frozen film. For example, in the technique described in Patent Document 1, after DIW (deionized water) as a cleaning liquid is supplied to the substrate surface to form a liquid film, a nozzle that discharges cooling gas is scanned in the vicinity of the substrate surface. Particles are removed from the substrate surface by freezing the liquid film and supplying DIW again to remove the frozen film.

JP 2008-071875 A (FIG. 5)

  As a result of various experiments, the present inventors have found that there is a certain correlation between the temperature of the frozen film and the particle removal rate. Specifically, it is possible not only to freeze the liquid film but also to further improve the particle removal rate by further lowering the temperature of the frozen film. The above-described prior art freeze cleaning technology requires repeated cooling gas scans to sufficiently reduce the temperature of the frozen membrane, resulting in longer processing time and increased gas usage. There was a problem and there was room for further improvement in this regard.

  The present invention has been made in view of the above problems, and in a substrate processing method and a substrate processing apparatus for removing contaminants such as particles adhering to the substrate surface, high throughput can be obtained, and particles and the like can be effectively removed. It aims at providing the technology which can be removed.

  In order to achieve the above object, a substrate cleaning method according to the present invention includes a liquid film forming step of forming a liquid film on an upper surface of a substrate held in a substantially horizontal posture, and a liquid film forming the liquid film with respect to the liquid film A freezing step in which a freezing gas lower than the freezing point is supplied to freeze the liquid film, and a temperature of the solidified body formed by freezing the liquid film is lowered by a cooling fluid having a higher cooling capacity than the freezing gas. It is characterized by comprising a cooling step and a removing step of removing the solidified body from the substrate.

  In the invention configured as described above, an excellent removal effect on particles and the like can be obtained by freezing the liquid film formed on the upper surface of the substrate and removing the solidified body formed by freezing the liquid film from the substrate. Here, after the liquid film on the upper surface of the substrate is frozen with a freezing gas, the solidified body formed by freezing the liquid film with a cooling fluid having a higher cooling capacity is cooled. Thus, the following effects are acquired by freezing and further cooling of a liquid film in two steps.

  First, the processing time can be shortened and the amount of frozen gas used can be reduced. Even if the frozen gas is continuously supplied to the substrate even after the liquid film is frozen, the temperature of the solidified body is lowered, but the cooling capacity of the frozen gas, that is, the amount of heat taken from the liquid film per unit time cannot be increased too much. This is because the frozen gas is supplied to the liquid film formed on the upper surface of the substrate, and must be a substance that does not dissolve in the liquid film and may contaminate the substrate. This is because it is necessary to suppress the flow rate so that the film is not blown away to expose the substrate. For this reason, it takes time to cool the solidified body by continuously supplying the frozen gas, and the consumption of the frozen gas is increased. In the present invention, after the liquid film is frozen, the solidified body is cooled by the cooling fluid having a higher cooling capacity. Therefore, the solidified body can be cooled in a shorter time, and the amount of freezing gas used can be reduced.

  Second, the processing conditions for freezing the liquid film and the processing conditions for cooling the solidified body formed by freezing the liquid film can be individually optimized. That is, the processing conditions required until the liquid film is frozen are different from the processing conditions required after the liquid film is frozen. For example, the freezing gas for freezing the liquid film is required not to blow off the liquid film as described above and to contain no components that dissolve in the liquid film and contaminate the substrate. On the other hand, after freezing of the liquid film, there is no such limitation, but it is required to cool the solidified body in a shorter time. It is difficult to make these compatible in a single processing mode. Therefore, by separating the process of freezing the liquid film and the process of further cooling the frozen solidified body, the processing conditions for each can be set individually, and the time and cost required for processing can be optimized according to the purpose. can do.

  As described above, according to the present invention, the temperature of the solidified body formed by freezing the liquid film can be cooled to a desired temperature in a short time, so that high throughput can be obtained and particles and the like can be removed from the substrate surface. It can be effectively removed.

  Here, as the cooling fluid having a higher cooling capacity than the frozen gas, for example, a fluid having a temperature lower than that of the frozen gas can be used. This fluid may be any of gas, liquid and mixtures thereof. It may have the same composition as the frozen gas. Further, as another aspect of the cooling fluid having a higher cooling capacity than the frozen gas, for example, a gas having a flow rate higher than that of the frozen gas can be used at a temperature equal to or lower than the frozen gas. By supplying a large amount of gas as a cooling fluid, the solidified body can reach a desired temperature in a short time. In these cases, the cooling fluid may be supplied to the solidified body on the upper surface of the substrate, or supplied to the lower surface of the substrate opposite to the surface on which the solidified body is formed and the solidified body via the substrate. It may be one that cools.

  Moreover, when the liquid which comprises a liquid film is water, it is desirable to cool a solidified body to minus 3 degrees C or less in a cooling process. According to the knowledge of the inventors of the present application, when the liquid film is water, it is known that the efficiency of removing particles and the like is greatly improved when the liquid film is cooled to minus 3 degrees Celsius or less. This is considered to be due to the fact that the crystal structure of ice formed by freezing water changes around minus 3 degrees Celsius.

  In order to achieve the above object, the substrate cleaning apparatus according to the present invention has a substrate holding means for holding the substrate in a horizontal state, and a liquid film for supplying a liquid to the substrate and forming a liquid film on the upper surface of the substrate. Forming means; freezing gas supply means for freezing the liquid film by supplying a freezing gas at a temperature lower than the freezing point of the liquid constituting the liquid film to the liquid film; and A cooling fluid supply means for supplying a cooling fluid having a high cooling capacity and reducing the temperature of the solidified body formed by freezing the liquid film is provided.

  In the invention configured as described above, similarly to the above-described invention of the substrate processing method, by cooling the temperature of the solidified body formed by freezing the liquid film formed on the upper surface of the substrate to a desired temperature in a short time, Particles and the like can be removed from the substrate surface with high throughput and excellent removal efficiency.

  Here, the freezing gas supply means may be configured to include, for example, a discharging unit that locally discharges the freezing gas with respect to the upper surface of the substrate, and a moving unit that moves the discharging unit relative to the upper surface of the substrate. By doing so, the frozen gas can be supplied only to a necessary place on the substrate, and the amount of gas used can be suppressed. The same applies to the cooling fluid supply means. That is, the cooling fluid supply means includes, for example, a second discharge unit that locally discharges the cooling fluid to the upper surface of the substrate, and a second moving unit that moves the second discharge unit relative to the upper surface of the substrate. It is good also as a structure to have. By doing so, the cooling fluid can be supplied only to a necessary place on the substrate.

  Further, for example, the cooling fluid supply unit may include a lower surface discharge unit that supplies the cooling fluid to the lower surface of the substrate. By doing so, the solidified body can be cooled via the substrate by supplying the cooling fluid to the lower surface of the substrate.

  According to another aspect of the substrate cleaning apparatus of the present invention, in order to achieve the above object, a substrate holding means for holding the substrate in a horizontal state, and supplying a liquid to the substrate to form a liquid film on the upper surface of the substrate. Liquid film forming means to be formed; supply means for selectively supplying a freezing gas having a temperature lower than the freezing point of the liquid constituting the liquid film and a cooling fluid having a higher cooling capacity than the freezing gas to the substrate; The freezing gas is supplied from the supply means to the liquid film formed on the upper surface of the substrate to freeze the liquid film, and then the solidified body formed by freezing the liquid film is supplied from the supply means to the liquid film. And a control means for supplying a cooling fluid.

  In the invention configured as described above, the solidified body after the liquid film is frozen can be cooled to a desired temperature in a short time, as in the above-described inventions, so that the removal efficiency is excellent with high throughput. Thus, particles and the like can be removed from the substrate surface.

  In these inventions, similar to the above-described substrate processing method, a fluid having a lower temperature than the freezing gas or a gas having a flow rate higher than that of the freezing gas can be used as the cooling fluid.

  In the substrate processing apparatus according to the present invention, the substrate holding means may rotate around the vertical axis while holding the substrate in a horizontal state. By doing so, it becomes easy to distribute a fluid such as a cooling fluid evenly to the substrate and the liquid film formed on the substrate by centrifugal force, and it is possible to perform uniform processing in the substrate surface. Become.

  According to the present invention, after the liquid film formed on the upper surface of the substrate is frozen by the freezing gas, the solidified body formed by freezing the liquid film by the fluid having a higher cooling capacity is cooled. Particles and the like adhering to the substrate surface can be removed due to the effect.

It is a figure showing one embodiment of a substrate processing device concerning this invention. It is a block diagram which shows the control structure of the substrate processing apparatus of FIG. It is a figure which shows the concept of the freeze washing process in this embodiment. It is a flowchart which shows the 1st aspect of a freeze washing process. It is a figure which shows typically the operation | movement in the process of FIG. It is a flowchart which shows the 2nd aspect of a freeze washing process. It is a figure which shows typically the operation | movement in the process of FIG. It is a figure which shows the example of the working fluid in two aspects of freeze washing.

  FIG. 1 is a view showing an embodiment of a substrate processing apparatus according to the present invention. FIG. 2 is a block diagram showing a control configuration of the substrate processing apparatus of FIG. This substrate processing apparatus is a substrate processing apparatus as a single wafer cleaning apparatus capable of executing a substrate cleaning process for removing contaminants such as particles adhering to the surface Wf of a substrate W such as a semiconductor wafer. .

  The substrate processing apparatus includes a processing chamber 1 having a processing space for cleaning the substrate W therein, and the substrate W is placed in a substantially horizontal posture with the substrate surface Wf facing upward in the processing chamber 1. The spin chuck 2 that is held and rotated, the freezing nozzle 3a that discharges the freezing gas for freezing the liquid film toward the surface Wf of the substrate W held by the spin chuck 2, and thus formed on the surface of the substrate W A cooling nozzle 3b that discharges a cooling fluid for cooling the solidified body of the liquid film to a lower temperature, a two-fluid nozzle 5 that supplies droplets of the processing liquid to the substrate surface Wf, and a spin chuck 2 A chemical solution discharge nozzle 6 that discharges a chemical solution toward the surface Wf of the held substrate W and a blocking member 9 that is disposed to face the surface Wf of the substrate W held by the spin chuck 2 are provided. As the treatment liquid, a chemical liquid or a cleaning liquid such as pure water or DIW (deionized water) is used.

  The spin chuck 2 has a rotation support shaft 21 connected to a rotation shaft of a chuck rotation mechanism 22 including a motor, and can rotate around a rotation center A0 by driving the chuck rotation mechanism 22. A disc-shaped spin base 23 is integrally connected to the upper end portion of the rotation spindle 21 by a fastening component such as a screw. Therefore, the spin base 23 rotates around the rotation center A0 by driving the chuck rotation mechanism 22 in accordance with an operation command from the control unit 4 (FIG. 2) that controls the entire apparatus.

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

  When the substrate W is delivered to the spin base 23, the plurality of chuck pins 24 are released, and when the substrate W is cleaned, the plurality of chuck pins 24 are pressed. State. By setting the pressed state, the plurality of chuck pins 24 can grip the peripheral edge of the substrate W and hold the substrate W in a substantially horizontal posture at a predetermined interval from the spin base 23. As a result, the substrate W is held with the front surface (pattern forming surface) Wf facing upward and the back surface Wb facing downward.

  A first rotation motor 31 is provided outside the spin chuck 2. A first rotation shaft 33 is connected to the first rotation motor 31. A first arm 35 is connected to the first rotation shaft 33 so as to extend in the horizontal direction, and a freezing nozzle 3 a is attached to the tip of the first arm 35. Then, the first rotation motor 31 is driven according to the operation command from the control unit 4, so that the first arm 35 can be swung around the first rotation shaft 33.

  The freezing nozzle 3 a is connected to the gas supply unit 64 (FIG. 2), and the freezing gas is supplied from the gas supply unit 64 to the freezing nozzle 3 a in response to an operation command from the control unit 4. More specifically, the nitrogen gas supplied from the nitrogen gas storage unit 641 provided in the gas supply unit 64 is cooled to a temperature lower than the freezing point of DIW by the heat exchanger 642, and the nitrogen gas thus cooled is frozen. The gas is supplied to the freezing nozzle 3a. When the freezing nozzle 3a is disposed opposite to the substrate surface Wf, the freezing gas is locally discharged from the freezing nozzle 3a toward the substrate surface Wf. While the freezing gas is discharged from the freezing nozzle 3a, the control unit 4 moves the freezing nozzle 3a from the rotation center of the substrate toward the outer periphery while rotating the substrate W, so that the freezing gas is transferred to the substrate surface. It can be supplied over the entire surface of Wf. At this time, if a liquid film made of DIW is formed in advance on the substrate surface Wf as described later, it is possible to freeze the entire liquid film and generate a frozen film of DIW on the entire surface of the substrate surface Wf.

  Further, a second rotation motor 36 is further provided outside the spin chuck 2. A second rotation shaft 37 is connected to the second rotation motor 36. A second arm 38 is connected to the second rotating shaft 37 so as to extend in the horizontal direction, and a cooling nozzle 3 b is attached to the tip of the second arm 38. The second arm 38 can be swung around the second rotation shaft 37 by driving the second rotation motor 36 in accordance with an operation command from the control unit 4.

  And the nitrogen gas supplied from the nitrogen gas storage part 641 provided in the gas supply part 64 is cooled to a temperature lower than the above-mentioned freezing gas by the heat exchanger 643, and the nitrogen gas thus cooled is used as a cooling gas. It is supplied to the cooling nozzle 3b. When the cooling nozzle 3b is disposed opposite to the substrate surface Wf, the cooling gas is locally discharged from the cooling nozzle 3b toward the substrate surface Wf. In a state where the cooling gas is discharged from the cooling nozzle 3b, the control unit 4 moves the cooling nozzle 3b from the rotation center of the substrate toward the outer periphery while rotating the substrate W. It can be supplied over the entire surface of Wf. Thereby, the solidified body formed by freezing the liquid film on the substrate surface Wf is cooled to a further low temperature.

  A third rotation motor 51 is provided outside the spin chuck 2. A third rotation shaft 53 is connected to the third rotation motor 51, and a third arm 55 is connected to the third rotation shaft 53. A two-fluid nozzle 5 is attached to the tip of the third arm 55. Then, the two-fluid nozzle 5 can be swung around the third rotation shaft 53 by driving the third rotation motor 51 in accordance with an operation command from the control unit 4. This two-fluid nozzle is a so-called external mixing type two-fluid nozzle that generates DIW droplets by colliding DIW as a processing liquid and nitrogen gas in the air (outside the nozzle).

  A fourth rotation motor 67 is provided outside the spin chuck 2. A fourth rotation shaft 68 is connected to the fourth rotation motor 67. Further, a fourth arm 69 is connected to the fourth rotation shaft 68 so as to extend in the horizontal direction, and a chemical liquid discharge nozzle 6 is attached to the tip of the fourth arm 69. Then, the fourth rotation motor 67 is driven in accordance with an operation command from the control unit 4 so that the chemical solution discharge nozzle 6 is retracted laterally from the discharge position and the discharge position above the rotation center A0 of the substrate W. It is possible to reciprocate between the standby position. The chemical solution discharge nozzle 6 is connected to the chemical solution supply unit 61, and a chemical solution such as an SC1 solution (mixed aqueous solution of ammonia water and hydrogen peroxide solution) is pumped to the chemical solution discharge nozzle 6 in accordance with an operation command from the control unit 4. Is done.

  As the freezing nozzle 3a, the two-fluid nozzle 5, the chemical solution discharge nozzle 6, the arm attached to them, and the rotation mechanism thereof, for example, those described in Patent Document 1 (Japanese Patent Laid-Open No. 2008-071875) described above. The same structure can be used. The structure of the cooling nozzle 3b is basically the same as that of the freezing nozzle 3a. Therefore, in this specification, a more detailed description of these configurations is omitted.

  A disc-shaped blocking member 9 having an opening at the center is provided above the spin chuck 2. The blocking member 9 has a lower surface (bottom surface) that faces the substrate surface Wf and is substantially parallel to the substrate surface Wf. The planar size of the blocking member 9 is equal to or greater than the diameter of the substrate W. The blocking member 9 is attached substantially horizontally to a lower end portion of a support shaft 91 having a substantially cylindrical shape, and the support shaft 91 is rotatably held around a vertical axis passing through the center of the substrate W by an arm 92 extending in the horizontal direction. . The arm 92 is connected to a blocking member rotating mechanism 93 and a blocking member lifting mechanism 94.

  The blocking member rotating mechanism 93 rotates the support shaft 91 around the vertical axis passing through the center of the substrate W in accordance with an operation command from the control unit 4. The blocking member rotating mechanism 93 is configured to rotate the blocking member 9 in the same rotational direction as the substrate W and at substantially the same rotational speed in accordance with the rotation of the substrate W held by the spin chuck 2.

  Further, the blocking member elevating mechanism 94 can cause the blocking member 9 to face the spin base 23 in the vicinity of the spin base 23 according to an operation command from the control unit 4, or to separate the blocking member 9. Specifically, the control unit 4 operates the blocking member elevating mechanism 94 so that when the substrate W is carried into and out of the substrate processing apparatus, the separation position above the spin chuck 2 (the position shown in FIG. 1). ) To raise the blocking member 9. On the other hand, when a predetermined process is performed on the substrate W, the blocking member 9 is lowered to a facing position set very close to the surface Wf of the substrate W held by the spin chuck 2.

  The support shaft 91 is finished in a hollow shape, and a gas supply path 95 communicating with the opening of the blocking member 9 is inserted into the support shaft 91. The gas supply path 95 is connected to the gas supply unit 64, and nitrogen gas supplied from the nitrogen gas storage unit 641 without passing through the heat exchanger is supplied as a dry gas. In this embodiment, nitrogen gas is supplied from the gas supply path 95 to the space formed between the blocking member 9 and the substrate surface Wf during the drying process after the cleaning process for the substrate W. A liquid supply pipe 96 communicating with the opening of the blocking member 9 is inserted into the gas supply path 95, and a nozzle 97 is coupled to the lower end of the liquid supply pipe 96. An appropriate processing liquid is passed through the liquid supply pipe 96 to supply the processing liquid to the back surface Wb of the substrate W.

  The DIW supply unit 62 includes a DIW storage unit 621 and a heat exchanger 622. The heat exchanger 622 cools the DIW supplied from the DIW storage unit 621 to a temperature near its freezing point. That is, the DIW supply unit 62 can supply normal temperature DIW supplied from the DIW storage unit 621 or low-temperature DIW cooled to a temperature near the freezing point by the heat exchanger 622.

  The rotation support shaft 21 of the spin chuck 2 is a hollow shaft. A processing liquid supply pipe 25 for supplying a processing liquid to the back surface Wb of the substrate W is inserted into the rotary spindle 21. A gap between the inner wall surface of the rotation spindle 21 and the outer wall surface of the processing liquid supply pipe 25 forms a cylindrical gas supply path 29. The processing liquid supply pipe 25 and the gas supply path 29 extend to a position close to the lower surface (back surface Wb) of the substrate W held by the spin chuck 2, and the front end of the processing liquid supply tube 25 and the gas supply path 29 are processed toward the lower surface central portion of the substrate W. A lower surface nozzle 27 for discharging liquid and gas is provided.

  The treatment liquid supply pipe 25 is connected to the chemical liquid supply part 61 and the DIW supply part 62, and various liquids such as a chemical liquid such as an SC1 solution supplied from the chemical liquid supply part 61 or DIW supplied from the DIW supply part 62 are provided. Selectively supplied. On the other hand, the gas supply path 29 is connected to the gas supply unit 64 and can supply nitrogen gas from the gas supply unit 64 to a space formed between the spin base 23 and the substrate back surface Wb.

  In the substrate processing apparatus configured as described above, the substrate W carried into the processing chamber 1 is held by the spin chuck 2, and a predetermined chemical processing is performed as necessary. In addition, after the liquid film is formed on the surface Wf of the substrate W and frozen, the substrate W is subjected to a freeze cleaning process for removing adhering substances together with the frozen film. Since the basic operation of the freeze cleaning process in the apparatus having the above-described configuration is described in Patent Document 1 (Japanese Patent Laid-Open No. 2008-071875), detailed description thereof is omitted, and here, the freeze cleaning process and the patent in this embodiment are described. Differences from the processing described in Document 1 will be mainly described.

  FIG. 3 is a diagram showing the concept of the freeze cleaning process in this embodiment. More specifically, FIG. 3A is a diagram showing the relationship between the liquid film temperature and the particle removal efficiency, and FIG. 3B is a diagram showing the change of the liquid film temperature in the process. Here, the temperature of the liquid film before freezing and the temperature of the solidified body formed by freezing the liquid film are collectively referred to as “liquid film temperature”. Although the conventional freeze-cleaning technique freezes the liquid film, the temperature of the liquid film after freezing has not been considered much. However, according to the experiments of the present inventors using a liquid film by DIW, as shown in FIG. 3 (a), not only the liquid film is frozen, but the temperature reached by the liquid film after freezing is lowered. It became clear that the particle removal efficiency was increased. Such a tendency was particularly remarkable when the liquid film temperature was about minus 3 ° C. or less. This is considered to be because the crystal structure of ice changes at about minus 3 ° C.

  Therefore, in this embodiment, after the DIW liquid film on the substrate is frozen by the freezing gas, the solidified body formed by freezing the liquid film is further cooled to enhance the cleaning effect. The specific method will be described below.

  In the process of the freeze cleaning process, as shown in FIG. 3B, when the supply of the freezing gas to the substrate on which the liquid film is formed is started, the liquid film temperature gradually starts to decrease. When the liquid film temperature reaches 0 ° C., freezing of the liquid film starts, and the liquid film temperature is maintained at approximately 0 ° C. until the entire liquid film is frozen. If the supply of the freezing gas is continued even after the entire liquid film is frozen, the liquid film temperature further decreases, but as shown by the broken line with the symbol A, the decrease in the liquid film temperature due to the freezing gas is relatively gradual. . Because the frozen gas is supplied to the unfrozen liquid film, it is necessary to reduce the flow rate so as not to blow off the liquid film or expose the substrate surface. This is because it is limited. In addition, it is necessary to select a freezing gas species that does not dissolve in the liquid film and contaminate the substrate, and the degree of freedom is not high. For these reasons, further cooling of the substrate by continuing the supply of the freezing gas takes time for the frozen liquid film to cool to a desired temperature, and the consumption of freezing gas is also large. The problem of becoming.

  Here, after the entire liquid film is frozen, the liquid film is less likely to be blown away, and the substrate surface is covered with a solidified body formed by freezing the liquid film, so that it is difficult to be contaminated. There are fewer restrictions. From this, it is possible to lower the liquid film temperature in a shorter time by using a fluid having a higher cooling capacity after the liquid film is completely frozen, as indicated by symbol B in FIG. It becomes possible. Such an object can be achieved by operating the substrate processing apparatus shown in FIG. 1 as follows.

  FIG. 4 is a flowchart showing a first aspect of the freeze cleaning process in this embodiment. FIG. 5 is a diagram schematically showing the operation in the process of FIG. In this apparatus, when an unprocessed substrate W is carried into the apparatus, the control unit 4 controls each part of the apparatus to execute a series of cleaning processes on the substrate W. Here, the substrate W is previously carried into the processing chamber 1 and held by the spin chuck 2 with the substrate W facing the surface Wf upward, and the blocking member 9 is disposed in close proximity to the upper surface of the substrate. Shall.

  The control unit 4 drives the chuck rotating mechanism 22 to rotate the spin chuck 2 and supplies room temperature DIW from the nozzle 97 to the substrate surface Wf. Centrifugal force accompanying the rotation of the substrate W acts on the DIW supplied to the substrate surface, and the substrate is uniformly spread outward in the radial direction of the substrate W, and a part of the DIW is shaken off the substrate. Thus, the thickness of the liquid film is uniformly controlled over the entire surface of the substrate surface Wf, and a liquid film (water film) having a predetermined thickness is formed on the entire surface of the substrate Wf (step S101). When forming the liquid film, it is not an essential requirement to shake off part of the DIW supplied to the substrate surface Wf as described above. For example, the liquid film may be formed on the substrate surface Wf without shaking the DIW from the substrate W with the rotation of the substrate W stopped or with the substrate W rotated at a relatively low speed.

  In this state, as shown in FIG. 5A, a paddle-like liquid film LP having a predetermined thickness is formed on the surface Wf of the substrate W. Thus, when the liquid film formation is completed, the control unit 4 retracts the blocking member 9 to the separated position. Here, the paddle-like liquid film LP may be formed by, for example, the SC1 liquid supplied from the chemical liquid discharge nozzle 6.

  Subsequently, the freezing nozzle 3a is moved above the rotation center of the substrate from the standby position (step S102). 5B, the freezing nozzle 3a is gradually directed toward the edge position of the substrate W while discharging the freezing gas from the freezing nozzle 3a toward the surface Wf of the rotating substrate W. It is moved (step S103). Thereby, the liquid film LP formed in the surface region of the substrate surface Wf is cooled and partially frozen, and the frozen region (frozen region FR) is the center of the substrate surface Wf as shown in FIG. Formed in the part. Then, the frozen region FR is expanded from the central portion to the peripheral portion of the substrate surface Wf by the scanning of the nozzle 3a in the direction Dn1, and finally, as shown in FIG. 5D, the entire surface of the liquid film on the substrate surface Wf. Freezes. When the entire liquid film is frozen, the freezing nozzle 3a is retracted, and instead, the cooling nozzle 3b is moved above the rotation center of the substrate (step S104). Then, as shown in FIG. 5 (e), the nozzle 3b is scanned in the direction Dn2 on the substrate while discharging a cooling gas having a temperature lower than that of the frozen gas from the cooling nozzle 3b (step S105). The membrane LP is further cooled to a predetermined temperature.

  Here, as the freezing gas, for example, nitrogen gas at −150 ° C. and 50 L / min can be used. Further, as the cooling gas, for example, nitrogen gas of −170 ° C. and 100 L / min can be used. Moreover, as target temperature of the liquid film after freezing, it can be set to -30 degreeC, for example. When the scan of the cooling gas is completed, the blocking member 9 is again placed close to the substrate surface Wf (step S106), and the DIW at room temperature is directed from the nozzle 97 provided on the blocking member 9 toward the frozen liquid film on the substrate surface Wf. Is supplied for rinsing (step S107).

  At the time when the processes so far are executed, DIW is supplied to the surface of the substrate W in a state where the substrate W rotates while being sandwiched between the blocking member 9 and the spin base 23. Here, instead of supplying room temperature DIW to the substrate surface Wf, a droplet of DIW may be supplied from the two-fluid nozzle 5. Subsequently, the supply of DIW to the substrate is stopped, and a spin drying process for drying the substrate by high-speed rotation is performed (step S108). That is, by rotating the substrate W at a high speed while discharging nitrogen gas from the nozzle 97 provided on the blocking member 9 and the lower surface nozzle 27 provided on the spin base 23, the DIW remaining on the substrate W is shaken off. Dry. The nitrogen gas supplied at this time acts as a dry gas, and is a normal temperature gas that does not pass through a heat exchanger. When the drying process is completed in this manner, the processed substrate W is carried out to complete the process for one substrate.

  The cleaning effect obtained by the above treatment will be described. When the liquid film is frozen as described above, the volume of the liquid film entering between the substrate surface Wf and the particles increases (when water at 0 ° C. becomes ice at 0 ° C., the volume is about 1.1. The particles are separated from the substrate surface Wf by a minute distance. As a result, the adhesion force between the substrate surface Wf and the particles is reduced, and further, the particles are detached from the substrate surface Wf. At this time, even if a fine pattern is formed on the substrate surface Wf, the pressure applied to the pattern by the volume expansion of the liquid film is equal in all directions, that is, the force applied to the pattern is canceled out. Therefore, it is possible to peel only the particles from the substrate surface Wf while preventing the pattern from peeling or collapsing. Then, by removing the liquid film frozen by newly supplied DIW, particles and the like can also be removed from the substrate surface Wf. Further, as described above, the particle removal efficiency can be increased by further lowering the temperature reached by the liquid film after freezing.

  Here, the cooling gas is the same nitrogen gas as the freezing gas, while the gas temperature is lower than the freezing gas, so that the cooling capacity is higher than the freezing gas, that is, the amount of heat taken from the liquid film per unit time. Is getting a big cooling gas. Alternatively, the cooling capacity of the cooling gas may be increased by making the flow rate of the cooling gas larger than that of the frozen gas. As described above, it is necessary to suppress the flow rate of the freezing gas to such an extent that the liquid film on the substrate is not blown off. However, since there is no such problem with the cooling gas, it is possible to increase the flow rate. As a result, the cooling capacity can be increased.

  In addition, after freezing the liquid film, the substrate surface Wf is covered with the frozen liquid film, and since there is little possibility of impurities or the like entering the frozen liquid film, a low-temperature liquid is used instead of the cooling gas. May be supplied to the liquid film. That is, the cooling fluid for further cooling the frozen liquid film is not limited to gas. For example, liquid nitrogen may be directly supplied to the liquid film to cool the liquid film. By doing so, a higher cooling capacity than that of the gas can be obtained, so that the temperature of the liquid film can be lowered in a shorter time.

  In this embodiment, the freezing nozzle 3a for discharging the freezing gas and the cooling nozzle 3b for discharging the cooling gas are individually provided. As a configuration in which the temperature or flow rate of the gas discharged from the nozzle 3a) can be changed, the function of the freezing nozzle and the function of the cooling nozzle may be combined into one nozzle.

  Two more specific examples will be described. Here, a case is considered in which both the function of the freezing nozzle and the function of the cooling nozzle are realized by the freezing nozzle 3a. In this case, the configuration of the cooling nozzle 3b and the operation mechanism associated therewith in the configuration of FIG. 1 can be omitted.

  In the first example, the freezing gas supplied from the heat exchanger 642 of the gas supply unit 64 and the cooler cooling gas supplied from the heat exchanger 643 to the freezing nozzle 3a are not shown. Selectively supplied. Thereby, the freezing nozzle 3a can selectively discharge two types of nitrogen gas (frozen gas and cooling gas) having different temperatures. The basic flow of the freeze cleaning process is as shown in the flowchart of FIG. 4, but in step S104, the freezing nozzle 3a is again disposed above the substrate W and supplied from the freezing nozzle 3a from the heat exchanger 643. The cooling gas to be discharged is discharged. Thus, the temperature of the frozen liquid film LP is further lowered by scanning the substrate W while discharging the cooling gas supplied from the heat exchanger 643 by the freezing nozzle 3a.

  In the second example, by changing the gas flow rate, the gas having the same temperature is selectively used as the freezing gas and the cooling gas. In this example, the heat exchanger 643 of the gas supply unit 64 can be omitted, while the flow rate adjustment capable of changing the gas flow rate on the gas supply path from the heat exchanger 642 to the discharge port of the freezing nozzle 3a. A mechanism (not shown) is provided. The basic flow of the freeze cleaning process in this case is also as shown in the flowchart of FIG. 4, but in step S103, a gas having a relatively low flow rate is supplied to the substrate W as the frozen gas, while in step S105, the gas at the same temperature The cooling capacity is increased by increasing the flow rate to obtain a cooling gas.

  In these two examples, the frozen gas and the cooling gas can be switched by changing the temperature or flow rate of the gas discharged from a single nozzle. In either example, the frozen liquid film is the same as in the above embodiment. Can be cooled to a desired temperature in a short time, and a high particle removal effect can be obtained. Note that both the temperature and the flow rate of the gas may be changed.

  FIG. 6 is a flowchart showing a second aspect of the freeze cleaning process in this embodiment. FIG. 7 is a diagram schematically showing the operation in the process of FIG. In the second mode, after the liquid film LP is formed on the substrate W and frozen in the same manner as in the first mode, a low-temperature cooling fluid is supplied from the lower side of the substrate W to the back surface Wb. The frozen liquid film is cooled. Therefore, the cooling nozzle 3b and the configuration associated therewith can be omitted.

  In this embodiment, a liquid film is formed on the substrate (step S201, FIG. 7A), and the liquid film is frozen by scanning the freezing nozzle 3a from the rotation center of the substrate (steps S202 and S203, FIG. 7 (b) and FIG. 7 (c)), which are the same as the first aspect described above. After the entire liquid film is thus frozen (FIG. 7D), subsequently, as shown in FIG. 7E, a low-temperature cooling fluid is discharged from the lower surface nozzle 27 and supplied to the substrate back surface Wb (step S204). ). As a result, the frozen liquid film is cooled via the substrate W. At this time, it is desirable to send low-temperature nitrogen gas (frozen gas or cooling gas) to the gas supply path 29 so that the cooling fluid flows along the substrate back surface Wb. Thereafter, the rinsing process and the spin drying process are performed (steps S206 and S207), which is the same as the first mode.

  FIG. 8 is a diagram showing examples of fluids used in two modes of freeze cleaning. In the freeze cleaning process of the two aspects of the present embodiment described above, a freezing gas for freezing the liquid film LP formed on the surface Wf of the substrate W and a cooling fluid for further cooling the frozen liquid film Is used. FIG. 8 shows examples of fluids that can be used for these. First, in order to freeze a liquid film, it is necessary to make it gaseous in order to avoid mixing with the liquid film. As shown in FIG. 8, it is necessary to use nitrogen gas, oxygen gas, argon gas, air, or the like. it can. Oxygen gas or air may oxidize the substrate, but in such an application, the upper surface of the substrate W is covered with a liquid film and can be used. It is desirable to keep the temperature of the liquid film as low as possible in order to prevent these from dissolving into the liquid.

  Further, as the cooling fluid used after freezing the liquid film, either gas or liquid can be used, and the fluid may be supplied to either the upper surface or the lower surface of the substrate. Such a gas can be the same as the frozen gas and can be used at a lower temperature or a larger flow rate. Further, as the liquid, various liquids having a sufficiently lower freezing point than the liquid constituting the liquid film (DIW in the present embodiment) can be used. For example, liquid nitrogen, polyhydric alcohol such as ethylene glycol or propylene glycol can be used. Various alcohols, hydrofluoroethers (HFE), and the like can be preferably used.

  As described above, in this embodiment, after the liquid film is frozen by supplying a low temperature gas to the liquid film formed on the upper surface of the substrate, the liquid solidified by supplying a cooling fluid having a higher cooling capacity. Further reduce the temperature of the membrane. Then, by removing the solidified body of the liquid film thus cooled together with the rinse liquid (DIW), the substrate can be cleaned with high particle removal efficiency in this embodiment. In addition, by cooling the frozen liquid film with a cooling fluid with a high cooling capacity, the temperature of the liquid film can be lowered to a predetermined temperature in a short time, processing time can be shortened, and processing can be performed with high throughput. Can do.

  As described above, in this embodiment, the spin chuck 2 functions as the “substrate holding unit” of the present invention, and the nozzle 97 provided on the blocking member 9 serves as the “liquid film forming unit” of the present invention. It is functioning. Further, in this embodiment, the freezing nozzle 3a and the gas supply unit 64 function integrally as the “freezing gas supply means” of the present invention. In the first aspect of the freezing cleaning process, the cooling nozzle 3b is “ It functions as a “cooling fluid supply means”. Further, the freezing nozzle 3a and the cooling nozzle 3b also have the functions as the “discharge section” and the “second discharge section” of the present invention, respectively, and the rotation motors 31 and 36 for scanning these respectively are the present invention. Are functioning as a “moving part” and a “second moving part”. In the second aspect of the freeze cleaning process of this embodiment, the lower surface nozzle 27 functions as the “cooling fluid supply means” and the “lower surface discharge section” of the present invention.

  Further, the temperature or flow rate of the nitrogen gas delivered from the gas supply unit 64 and discharged from the freezing nozzle 3a is changed by the control unit 4 so that the freezing gas and the cooling gas are discharged from a single nozzle. In this configuration, the freezing nozzle 3a and the gas supply unit 64 correspond to the “supply unit” of the present invention, and the control unit 4 corresponds to the “control unit” of the present invention.

  The present invention is not limited to the above-described embodiment, and various modifications other than those described above can be made without departing from the spirit of the present invention. For example, in the above embodiment, the “liquid film” of the present invention is formed by DIW, but the liquid constituting the liquid film is not limited to this. For example, carbonated water, hydrogen water, dilute ammonia water (for example, about 1 ppm), dilute hydrochloric acid or the like, or DIW added with a small amount of surfactant may be used.

  Moreover, in the said embodiment, although nitrogen gas supplied from the same nitrogen gas storage part and having mutually different temperature is used as freezing gas and cooling gas, these are not limited to nitrogen gas. For example, the freezing gas and the cooling gas may be different gas types, and those described in FIG. 8 may be appropriately combined.

  Further, the substrate processing apparatus of the above embodiment incorporates the DIW storage unit 621 and the nitrogen gas storage unit 641 inside the apparatus, but the processing liquid and the gas supply source may be provided outside the apparatus. For example, you may make it utilize the supply source of the existing process liquid and gas in a factory. Further, when there are existing facilities for cooling them, liquid or gas cooled by the facilities may be used.

  Moreover, although the substrate processing apparatus of the said embodiment has the shielding member 9 arrange | positioned close to the upper direction of the board | substrate W, this invention is applicable also to the apparatus which does not have a shielding member. In the apparatus of this embodiment, the substrate W is held by the chuck pins 24 that come into contact with the peripheral edge thereof. However, the substrate holding method is not limited to this, and the substrate is held by another method. The present invention can also be applied to an apparatus.

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

2 Spin chuck (substrate holding means)
3a Freezing nozzle (freezing gas supply means, discharge part, supply means)
3b Cooling nozzle (cooling fluid supply means, second discharge part)
4 Control unit (control means)
31 Rotating motor (moving part)
36 Rotating motor (second moving part)
27 Lower surface nozzle (cooling fluid supply means, lower surface discharge part)
64 Gas supply section (freezing gas supply means, supply means)
97 Nozzle (Liquid film forming means)
W ... Substrate Wf ... Substrate surface (pattern formation surface)
Wb ... Back side of substrate

Claims (14)

A liquid film forming step of forming a liquid film on the upper surface of the substrate held in a substantially horizontal posture;
A freezing step of freezing the liquid film by supplying a freezing gas having a temperature lower than the freezing point of the liquid constituting the liquid film to the liquid film;
A cooling step in which the temperature of the solidified body formed by freezing the liquid film is lowered by a cooling fluid having a higher cooling capacity than the frozen gas;
And a removing step of removing the solidified body from the substrate.   The substrate processing method according to claim 1, wherein in the cooling step, the cooling fluid is supplied to the solidified body.   The substrate processing method according to claim 1, wherein in the cooling step, the cooling fluid is supplied to a lower surface of the substrate.   4. The substrate processing method according to claim 1, wherein in the cooling step, a fluid having a temperature lower than that of the frozen gas is used as the cooling fluid.   4. The substrate processing method according to claim 1, wherein in the cooling step, a gas having a flow rate higher than that of the frozen gas at a temperature lower than the frozen gas is used as the cooling fluid.   The substrate processing method according to claim 1, wherein the liquid constituting the liquid film is water, and the solidified body is cooled to −3 degrees Celsius or less in the cooling step. Substrate holding means for holding the substrate in a horizontal state;
Liquid film forming means for supplying a liquid to the substrate and forming a liquid film on the upper surface of the substrate;
A freezing gas supply means for freezing the liquid film by supplying a freezing gas having a temperature lower than the freezing point of the liquid constituting the liquid film to the liquid film;
A cooling fluid supply means for supplying a cooling fluid having a higher cooling capacity than the freezing gas to the substrate to reduce a temperature of a solidified body formed by freezing the liquid film. Processing equipment.   The said freezing gas supply means has a discharge part which discharges the said freezing gas locally with respect to the upper surface of the said board | substrate, and a moving part which moves the said discharge part relatively with respect to the upper surface of the said board | substrate. Substrate processing equipment.   The cooling fluid supply means includes a second discharge unit that locally discharges the cooling fluid to the upper surface of the substrate, and a second moving unit that moves the second discharge unit relative to the upper surface of the substrate. The substrate processing apparatus of Claim 7 or 8 which has these.   The substrate processing apparatus according to claim 7, wherein the cooling fluid supply unit includes a lower surface discharge unit that supplies the cooling fluid to the lower surface of the substrate. Substrate holding means for holding the substrate in a horizontal state;
Liquid film forming means for supplying a liquid to the substrate and forming a liquid film on the upper surface of the substrate;
Supply means for selectively supplying a freezing gas having a temperature lower than the freezing point of the liquid constituting the liquid film and a cooling fluid having a higher cooling capacity than the freezing gas to the substrate;
The frozen gas is supplied from the supply means to the liquid film formed on the upper surface of the substrate to freeze the liquid film, and then the solidified body formed by freezing the liquid film is cooled from the supply means. And a control means for supplying a working fluid.   The substrate processing apparatus according to claim 7, wherein the cooling fluid has a temperature lower than that of the frozen gas.   The substrate processing apparatus according to claim 7, wherein the cooling fluid is a gas having a flow rate higher than that of the frozen gas at a temperature lower than the frozen gas.   The substrate processing apparatus according to claim 7, wherein the substrate holding unit rotates the substrate about a vertical axis while holding the substrate in a horizontal state.

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