JP2013051301A - Substrate processing apparatus and substrate processing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve particle removal efficiency in a substrate processing method and a substrate processing apparatus for removing contaminants, such as particles, which adhere to a substrate surface.SOLUTION: A liquid film LP, formed by a process liquid L where polystyrene fine particles P are dispersed in deionized water, is formed on a surface Wf of a substrate W. The substrate process apparatus allows a cooling gas discharge nozzle 3 to sweep and move relative to the substrate W while discharging a cooling gas to freeze the liquid film LP. The fine particles P mixed into the liquid film becomes a solidification core and the generation of an ice block IC is facilitated. Thus, the phase change time from the liquid phase to the solid phase is shortened and the particle removal efficiency is improved.

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)

  In this type of cleaning technology, further improvement in particle removal efficiency is required. The inventors of the present application have made various experiments to shorten the time required for the phase change when the liquid film formed on the substrate surface changes from the liquid phase to the solid phase by cooling (hereinafter referred to as “phase change time”). It was found that higher particle removal efficiency can be obtained. In order to achieve this in the above-described conventional technology, it is necessary to significantly increase the amount of cooling gas used or lower its temperature, which is not realistic because it increases processing costs.

  The present invention has been made in view of the above problems, and provides a technique capable of improving particle removal efficiency in a substrate processing method and a substrate processing apparatus for removing contaminants such as particles adhering to a substrate surface. For the purpose.

  In order to achieve the above object, the substrate processing method of the present invention forms a liquid film with a first processing liquid in which fine particles of polystyrene or silica are dispersed on the surface of the substrate, and the first processing liquid A freezing step in which the liquid film is frozen by a cooling gas lower in temperature than the freezing point, and a second treatment liquid is supplied to the surface of the substrate on which the liquid film has been frozen to remove the frozen film from the liquid film And a process.

  As described above, according to the knowledge of the present inventors, the particle removal efficiency can be improved by shortening the phase change time when changing the liquid film from the liquid phase to the solid phase. The inventors of the present application studied mixing fine particles that become solidification nuclei at the time of phase change in the liquid film in order to make the phase change in a short time. As a result, when a liquid film is formed with a treatment liquid (first treatment liquid) in which fine particles of polystyrene or silica are dispersed, the solidification of the liquid film proceeds in a short time with these fine particles as nuclei. It has been clarified that there are no problems such as contamination of the substrate due to adhesion of fine particles and remaining on the substrate after processing.

  That is, according to the present invention, since the fine particles dispersed in the first treatment liquid become nuclei and the phase change from the liquid phase to the solid phase occurs in a short time, the liquid film of the first treatment liquid is frozen, It is possible to improve the particle removal efficiency by removing. In addition, since the amount of cooling gas used to obtain the same particle removal effect can be reduced and the temperature can be increased, the processing cost can be reduced.

  In the present invention, as the first treatment liquid, for example, fine water may be added to any one of pure water, deionized water, and a mixed solution of ammonia water and hydrogen peroxide water. Any of these liquids can be suitably applied to freeze-cleaning technology, and by adding the above fine particles to this, the phase change time from the liquid phase to the solid phase is shortened, and the particle removal efficiency is improved. Further enhancement is possible.

  More specifically, for example, a first treatment liquid generation step of mixing a polystyrene latex liquid and any one of the above liquids to generate a first treatment liquid containing polystyrene fine particles may be provided. By mixing water or a liquid containing water as a main component with a polystyrene latex liquid in which polystyrene particles are dispersed in water, a first treatment liquid suitable for the present invention can be easily produced.

  Further, in the freezing process of the present invention, for example, cooling gas is discharged from a cooling nozzle that scans and moves relative to the surface of the substrate on which the liquid film is formed, and the cooling gas is supplied to the liquid film to freeze it. You may do it. The liquid film on the substrate surface can be efficiently frozen by scanning and moving the cooling nozzle relative to the substrate while discharging the cooling gas from the cooling nozzle. In this case, the scanning movement of the cooling nozzle may be performed while rotating the substrate.

  In the present invention, the first treatment liquid may contain a surfactant. It is possible to further increase the particle removal efficiency by forming a liquid film with a liquid containing a surfactant, freezing it, and removing it.

  In addition, the substrate processing apparatus according to the present invention includes a substrate holding means for holding the substrate substantially horizontally, pure liquid, deionized water, and a mixed solution of ammonia water and hydrogen peroxide water, and a polystyrene. Alternatively, a slurry containing fine particles of silica is mixed to supply a first processing liquid generating unit that generates a first processing liquid, and supplying the first processing liquid to the surface of the substrate held by the substrate holding unit, A first processing liquid supply means for forming a liquid film of the first processing liquid on the surface of the substrate; and a cooling gas having a temperature lower than a freezing point of the first processing liquid on the surface of the substrate on which the liquid film has been formed. A cooling gas supply means for supplying and freezing the liquid film, and a second processing liquid supply for supplying a second processing liquid to the surface of the substrate on which the liquid film is frozen and removing the frozen film of the liquid film. Means.

  In the invention configured as described above, a first treatment liquid in which fine particles that act as solidification nuclei at the time of cooling are dispersed in water or a liquid containing water as a main component is generated and supplied to the surface of the substrate. Since the film is formed and frozen, the substrate can be cleaned with high particle removal efficiency as described above.

  In this case, the substrate holding unit may rotate the substrate around the vertical axis, while the cooling gas supply unit may include a cooling nozzle that scans and moves along the surface of the substrate while discharging the cooling gas. The liquid film on the surface of the substrate can be efficiently frozen by scanning and moving the cooling nozzle that discharges the cooling gas while rotating the substrate. At this time, since the fine particles serving as solidification nuclei are dispersed in the liquid film, the phase change from the liquid phase to the solid phase of the liquid film is further promoted. Thereby, the phase change proceeds in a short time, and high particle removal efficiency can be obtained.

  According to the present invention, a liquid film is formed by the first processing liquid containing fine particles that become nuclei at the time of freezing, and the liquid film is frozen and removed, so that the substrate can be processed with high particle removal efficiency. Can do. Further, the same particle removal effect can be obtained at a lower processing cost.

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 relationship between the cooling rate of a liquid film, and particle removal efficiency. It is a figure which shows typically the principle of the liquid film freezing in this embodiment. It is a flowchart which shows the washing | cleaning process operation | movement in this embodiment.

  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. A spin chuck 2 that is held and rotated, a cooling gas discharge nozzle 3 that discharges a cooling gas for freezing the liquid film toward the surface Wf of the substrate W held on the spin chuck 2, and a processing liquid on the substrate surface Wf. On the surface Wf of the substrate W held on the spin chuck 2, the chemical solution discharge nozzle 6 that discharges the chemical toward the surface Wf of the substrate W held on the spin chuck 2, and the surface Wf of the substrate W held on the spin chuck 2. A blocking member 9 disposed oppositely is 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 cooling gas discharge nozzle 3 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 cooling gas discharge nozzle 3 is connected to a gas supply unit 64 (FIG. 2), and a cooling gas is supplied from the gas supply unit 64 to the cooling gas discharge nozzle 3 in accordance with 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 cooled. The gas is supplied to the cooling gas discharge nozzle 3 as a gas. When the cooling gas discharge nozzle 3 is disposed opposite to the substrate surface Wf, the cooling gas is locally discharged from the cooling gas discharge nozzle 3 toward the substrate surface Wf. While the cooling gas is discharged from the cooling gas discharge nozzle 3, the control unit 4 moves the cooling gas discharge nozzle 3 from the rotation center of the substrate toward the outer periphery while rotating the substrate W, so that the cooling gas is transferred to the substrate. It can be supplied over the entire surface 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.

  A second rotation motor 51 is provided outside the spin chuck 2. A second rotation shaft 53 is connected to the second rotation motor 51, and a second arm 55 is connected to the second rotation shaft 53. A two-fluid nozzle 5 is attached to the tip of the second arm 55. The two-fluid nozzle 5 can be swung around the second rotation shaft 53 by driving the second 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 third rotation motor 67 is provided outside the spin chuck 2. A third rotation shaft 68 is connected to the third rotation motor 67. A third arm 69 is connected to the third 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 third arm 69. Then, the third 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.

  The cooling gas discharge nozzle 3, the two-fluid nozzle 5, the chemical liquid discharge nozzle 6, and the arm associated therewith and the rotation mechanism thereof are described in, for example, the above-mentioned Patent Document 1 (Japanese Patent Laid-Open No. 2008-071875). The thing of the same structure as a thing can be used. 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 642 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. The liquid supply pipe 96 is connected to the processing liquid supply unit 62, and a first processing liquid or DIW, which will be described later, supplied from the processing liquid supply unit 62 can be selectively discharged from the nozzle 97 toward the substrate surface Wf. It has become.

  The treatment liquid supply unit 62 includes a DIW storage unit 621 that stores DIW and a slurry storage unit 622 that stores a slurry in which polystyrene fine particles or silica fine particles are dispersed in water. As will be described in detail later, for example, a polystyrene latex (PSL) liquid can be used as the slurry.

  The room-temperature DIW stored in the DIW storage unit 621 is sent to the liquid supply pipe 96 via the open / close valve 626. More specifically, when the opening / closing valve 626 is opened, room-temperature DIW delivered from the DIW reservoir 621 is supplied from the nozzle 97 to the substrate surface Wf as a rinse liquid via the liquid supply pipe 96.

  Further, a part of DIW supplied from the DIW storage unit 621 is supplied to the mixer 623 into which the slurry supplied from the slurry storage unit 622 is fed. The mixer 623 mixes and agitates the DIW supplied from the DIW storage unit 621 and the slurry supplied from the slurry storage unit 622 at a predetermined ratio to disperse the above-described fine particles in the DIW. Is generated. The first treatment liquid thus generated is cooled to a temperature near the freezing point of DIW by the heat exchanger 624 and sent to the liquid supply pipe 96 through the open / close valve 625. More specifically, when the opening / closing valve 625 is opened, the cooled first processing liquid is supplied from the nozzle 97 toward the substrate surface Wf via the liquid supply pipe 96.

  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 processing liquid supply pipe 25 is connected to the chemical liquid supply section 61 and the processing liquid supply section 62, and a chemical liquid such as an SC1 solution supplied from the chemical liquid supply section 61 or a room temperature DIW supplied from the processing liquid supply section 62 is selected. 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. More specifically, nitrogen gas (dry gas) that does not contain water at normal temperature and cooling gas supplied from the gas supply unit 64 are supplied to the gas supply path 29 via valves.

  Next, a cleaning process operation in the substrate processing apparatus configured as described above will be described. First, the principle of the cleaning processing operation in this embodiment will be described with reference to FIG. FIG. 3 is a diagram showing the relationship between the cooling rate of the liquid film and the particle removal efficiency. FIG. 3A is a diagram schematically showing a temperature change of the liquid film (and an ice film formed by solidifying the liquid film) when the liquid film formed on the substrate surface is cooled with a constant cooling capacity. As shown in the figure, when the liquid film is cooled, its temperature T gradually decreases. Then, when reaching the vicinity of the freezing point Tf of the liquid constituting the liquid film, the phase change from the liquid phase to the solid phase starts gradually. In a state where the liquid phase and the solid phase coexist, the temperature T of the liquid film hardly changes near the freezing point Tf, and starts to decrease again when the change to the solid phase is completed. Here, “phase change time tc” means that the time required for the phase change to be completed is the time from the start of the phase change from the liquid phase to the solid phase until the completion of the phase change. Called.

  FIG. 3 (b) shows a conventional freeze cleaning technique, that is, a technique in which a liquid film formed on a substrate surface is frozen with a cooling gas and rinsed to remove the frozen film, and the phase change time tc is changed by variously changing the cooling capacity. It is a figure which shows the result of having changed and investigating the correlation of the phase change time tc at that time, and particle removal efficiency PRE. As shown in the figure, the result was obtained that the particle removal efficiency PRE was higher as the phase change time tc from the liquid phase to the solid phase was shorter.

  In the freeze cleaning technique, in order to shorten the phase change time tc, it is conceivable to increase the cooling capability of the liquid film by the cooling gas. For this purpose, for example, it is effective to increase the supply amount of the cooling gas or to lower the temperature of the cooling gas. However, in this case, the amount of gas used and the energy consumption required for cooling increase, which increases the processing cost. Therefore, the inventors of the present invention previously mixed fine particles in the liquid film, and promoted the phase change from the liquid phase to the solid phase by causing the fine particles to function as solidification nuclei during cooling, resulting in a phase change time. A method for shortening tc was examined.

  FIG. 4 is a diagram schematically showing the principle of liquid film freezing in this embodiment. In this embodiment, as shown in FIG. 4A, the first processing liquid L in which the fine particles P are dispersed in the liquid is rotated from the nozzle 97 of the blocking member 9 while rotating the substrate W held on the spin chuck 2. Supply toward the substrate surface Wf. Thus, a liquid film of the first processing liquid L containing the fine particles P is formed on the substrate surface Wf. Next, as shown in FIG. 4B, while the rotation of the substrate W is maintained, the cooling gas discharge nozzle 3 is scanned and moved from the center of rotation of the substrate W toward the peripheral portion, so that the cooling gas flows onto the substrate surface Wf. Supply to the liquid membrane LP. Thereby, the freezing area | region FR in which the 1st process liquid was frozen spreads toward the peripheral part from the center of a board | substrate.

  Immediately below the cooling gas discharge nozzle 3 to which the cooling gas is directly blown, a small ice block IC is formed in the liquid film LP due to cooling and grows, whereby the liquid film is frozen. At this time, if the fine particles P are dispersed in the liquid film LP, they become solidification nuclei and promote the formation of ice blocks IC. This action is expected to shorten the phase change time tc.

  Finally, as shown in FIG. 4C, the freezing region FR spreads over the entire liquid film on the substrate surface Wf, and the entire liquid film freezes. Thereafter, a rinse liquid is supplied to the substrate W to remove the frozen film, whereby contaminants such as particles adhering to the substrate surface Wf are washed away together with the frozen film, and the substrate is cleaned.

  The conditions that the fine particles P to be dispersed in the first treatment liquid should have are as follows. First, it must be insoluble in the liquid that is the main component of the first processing liquid. If the added fine particles are dissolved in the liquid, further energy is required for freezing the liquid film due to the lowering of the freezing point of the liquid. Next, it needs to act effectively as a solidification nucleus for the liquid. Further, it is desirable that the substrate W is not contaminated by contacting the substrate W, can be easily washed away by rinsing, and does not remain on the substrate surface Wf.

  The inventors of the present invention have made various studies on the fine particles satisfying these conditions. As a result, when the polystyrene or silica fine particles P are added to a liquid mainly composed of water, the phase change time tc is shortened. It was found that high particle removal efficiency PRE can be obtained. Therefore, in this embodiment, a mixture of polystyrene latex liquid, which is a slurry suspension in which polystyrene fine particles are dispersed in water, and DIW is used as a first treatment liquid for forming a liquid film on the substrate surface Wf. doing.

  FIG. 5 is a flowchart showing the cleaning processing operation in this embodiment. 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, when the substrate has a fine pattern formed on its surface Wf, the substrate W is loaded into the processing chamber 1 with the substrate surface Wf facing upward and held by the spin chuck 2 ( Step S101). At this time, the blocking member 9 is in a separated position to prevent interference with the substrate W.

  When the unprocessed substrate W is held on the spin chuck 2, the blocking member 9 is lowered to the opposing position and is disposed close to the substrate surface Wf (step S102). As a result, the substrate surface Wf is covered in the state of being close to the substrate facing surface of the blocking member 9 and is blocked from the ambient atmosphere of the substrate W. Then, the control unit 4 drives the chuck rotating mechanism 22 to rotate the spin chuck 2 and supplies the first processing liquid cooled from the nozzle 97 to the substrate surface Wf. As shown in FIG. 4A, the centrifugal force accompanying the rotation of the substrate W acts on the first processing liquid supplied to the substrate surface, and the first processing solution is uniformly spread outward in the radial direction of the substrate W. Is shaken off the substrate. Thereby, the thickness of the liquid film is uniformly controlled over the entire surface of the substrate surface Wf, and the liquid film of the first processing liquid having a predetermined thickness is formed on the entire surface of the substrate Wf (step S103). In forming the liquid film, it is not essential to shake off part of the first processing liquid 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 liquid from the substrate W in a state where the rotation of the substrate W is stopped or in a state where the substrate W is rotated at a relatively low speed.

  In this state, a paddle-like liquid film of the first processing liquid 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 (step S104). Thereafter, the cooling gas discharge nozzle 3 is moved from the standby position to above the rotation center of the substrate. Then, while the cooling gas is discharged from the cooling gas discharge nozzle 3 toward the surface Wf of the rotating substrate W, the cooling gas discharge nozzle 3 is gradually scanned toward the edge position of the substrate W (step S105). ). As a result, as shown in FIG. 4B, ice blocks are formed in the liquid film LP cooled by the cooling gas, and the liquid film LP partially freezes as this grows, and the frozen region ( A freezing region FR) is formed at the center of the substrate surface Wf. At this time, the formation of ice blocks is promoted by the fine particles P dispersed in the liquid film LP serving as nuclei, and the time required for the phase change from the liquid phase to the solid phase is shortened.

  Then, the freezing region FR is expanded from the central portion to the peripheral portion of the substrate surface Wf by the scanning of the nozzle 3 in the direction Ds, and finally the entire liquid film on the substrate surface Wf as shown in FIG. Freezes. When the entire liquid film is frozen, the cooling gas discharge nozzle 3 is retracted and the blocking member 9 is disposed close to the substrate surface Wf (step S106).

  Subsequently, a rinse process using DIW is performed on both surfaces of the substrate W (step S107). That is, room temperature DIW is discharged from the nozzle 97 of the blocking member 9 and the lower surface nozzle 27 disposed close to the substrate surface Wf, and both surfaces of the substrate W are rinsed by DIW. The fine particles used in the present embodiment are polystyrene particles or silica particles. According to the knowledge of the inventors of the present application, these fine particles can be washed away from the substrate W relatively easily by the DIW rinsing process, and hardly remain on the substrate after rinsing.

  Thereafter, the supply of DIW to both sides of the substrate is stopped, and a drying process for drying the substrate is performed (step S108). That is, by rotating the substrate W at a high speed while discharging nitrogen gas (dry gas) at room temperature from the nozzle 97 provided on the blocking member 9 and the lower surface nozzle 27 provided on the spin base 23, the substrate W remains on the substrate W. The DIW to be shaken off and the substrate W is dried. The nitrogen gas supplied at this time acts as a dry gas, and is a room temperature gas that does not pass through the heat exchanger 642. When the drying process is completed in this way, the process for one substrate is completed by carrying out the processed substrate W (step S109).

  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.

  As described above, in this embodiment, in the freeze cleaning technique in which a liquid film is formed on the substrate surface Wf, frozen with a cooling gas, and the frozen film is removed to clean the substrate, the liquid constituting the liquid film The fine particles that act as solidification nuclei are dispersed. By doing so, in the liquid film cooled by the cooling gas, an ice lump is easily formed with the fine particles as nuclei, and the phase change from the liquid phase to the solid phase of the liquid film occurs in a short time. According to the knowledge of the inventors of the present application, it is possible to improve the particle removal efficiency by shortening the phase change time tc from the liquid phase to the solid phase of the liquid film. Even in this embodiment, the particle removal efficiency is high. Can be obtained.

  The fine particles added to the liquid film are polystyrene particles or silica particles. When these particles are used, there is no adverse effect caused by the fine particles touching the substrate, and they can be easily removed by rinsing with DIW. There is no problem of remaining on the substrate later.

  As described above, according to the present embodiment, it is possible to improve the particle removal efficiency in the freeze cleaning process, and also increase the amount of cooling gas used to improve the particle removal efficiency or lower the gas temperature. Therefore, it is possible to suppress an increase in processing cost.

The amount of fine particles mixed into the first treatment liquid can be set based on, for example, the following knowledge of the present inventors. When a liquid film made of DIW that does not contain microparticles as solidification nuclei is frozen, the typical size of ice blocks generated in the frozen film is small and about 150 μm in diameter. Assuming that ice pieces of this size are generated almost uniformly in the liquid film, the number of ice pieces per 1 cm ² of the liquid film when viewed from above is about 5.7 × 10 ³ . In order to make the effect of mixing the fine particles more certain, it is desirable to generate a larger number of ice blocks than the ice blocks generated when the fine particles are not included. Therefore, the number of the fine particles included per 1 cm ^{2 of} the liquid film. For example, it is conceivable to set the number to be equal to or greater than the number of ice blocks.

  As described above, in this embodiment, the spin chuck 2 functions as the “substrate holding means” of the present invention. Further, the processing liquid supply unit 62, in particular, the DIW storage unit 621, the slurry storage unit 622, the mixer 623, and the like function as a “first processing liquid generation unit” of the present invention. Further, the on-off valve 625, the liquid supply pipe 96, the nozzle 97 and the like function as a “first processing liquid supply means” of the present invention, and the on-off valve 626, the liquid supply pipe 96, the nozzle 97 and the like of the present invention are integrated. Functioning as “second processing liquid supply means”. That is, in this embodiment, DIW as the rinsing liquid corresponds to the “second processing liquid” of the present invention.

  In this embodiment, the cooling gas discharge nozzle 3 functions as the “cooling nozzle” of the present invention, and the nozzle 3 and the gas supply unit 64 function as the “cooling gas supply means” of the present invention.

  In the process of FIG. 5, steps S103, S105, and S107 correspond to the “liquid film forming step”, “freezing step”, and “removal step” of the present invention, respectively. Further, the process of previously mixing DIW and slurry in the mixer 623 to generate the first processing liquid corresponds to the “first processing liquid generation step” 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, a mixed liquid of DIW and slurry is used as the “first processing liquid” of the present invention, and DIW is used as the “second processing liquid” of the present invention. It is not limited to. For example, what can be used other than DIW as the main component of the first treatment liquid includes pure water, a mixed solution of ammonia water and hydrogen peroxide solution (SC-1 solution), and a small amount of surfactant added to these. There is something that was done. In particular, when the SC-1 solution is used, a zeta potential difference is generated between the substrate, the particles adhering to the substrate, and the fine particles added to the solution, so that the reattachment of the separated particles and fine particles to the substrate is more effective. Therefore, it is possible to obtain a better particle removal effect. Further, the “second treatment liquid” is not limited to DIW, and the above-described liquid types can be used similarly. Further, the liquid type that is the main component of the first treatment liquid and the second treatment liquid may be different.

  Moreover, in the said embodiment, although nitrogen gas supplied from the same nitrogen gas storage part and having mutually different temperature is used as cooling gas and drying gas, drying gas and cooling gas are not limited to nitrogen gas. For example, one or both of the dry gas and the cooling gas may be dry air or other inert gas. In particular, since the cooling gas cools the cleaning liquid and does not directly touch the substrate, dry air can be suitably used as the cooling gas.

  Further, in each of the above embodiments, the processing liquid discharge port that discharges DIW and the gas discharge port that discharges the cooling gas have a coaxial structure. However, the present invention is not limited to this structure. While the processing liquid discharge port for discharging the cleaning liquid is provided above, the gas discharge port for discharging the cooling gas may be arranged side by side next to the processing liquid discharge port. In such a structure, the cooling gas is discharged asymmetrically with respect to the substrate rotation axis. However, since the substrate is rotated, processing is performed substantially isotropically.

  In addition, the substrate processing apparatus of each of the above embodiments incorporates the DIW storage unit 621 and the nitrogen gas storage unit 641 inside the apparatus, but the cleaning liquid and the gas supply source may be provided outside the apparatus. For example, an existing cleaning liquid or gas supply source in the factory may be used. Further, when there are existing facilities for cooling them, a cleaning liquid or gas cooled by the facilities may be used.

  Further, the substrate processing apparatus of each of the above embodiments has the blocking member 9 disposed close to the upper side of the substrate W, but the present invention is also applicable to an apparatus having no blocking member. In addition, although the apparatus of these embodiments holds the substrate W by the chuck pins 24 that abut on the peripheral edge thereof, the substrate holding method is not limited to this, and the substrate is held by other methods. The present invention can also be applied to an apparatus that performs the above.

  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 processing an entire substrate including the substrate.

2 Spin chuck (substrate holding means)
3 Cooling gas discharge nozzle 9 Blocking member 62 Processing liquid supply unit (first processing liquid generating means)
64 Gas supply part (cooling gas supply means)
96 liquid supply pipe (first processing liquid supply means, second processing liquid supply means)
97 nozzle (first processing liquid supply means, second processing liquid supply means)
621 DIW reservoir (first treatment liquid generating means)
622 Slurry reservoir (first treatment liquid generating means)
623 Mixer (first treatment liquid generating means)
625 On-off valve (first processing liquid supply means)
626 On-off valve 626 (second processing liquid supply means)
S103 Liquid film formation process S105 Freezing process S107 Removal process W Substrate Wf Substrate surface Wb Substrate back surface

Claims (7)

A liquid film forming step of forming a liquid film by a first treatment liquid in which polystyrene or silica fine particles are dispersed on the surface of the substrate;
A freezing step of freezing the liquid film with a cooling gas having a temperature lower than the freezing point of the first treatment liquid;
A substrate processing method comprising: a removing step of supplying a second processing liquid to the surface of the substrate on which the liquid film is frozen to remove the frozen film on the liquid film.   2. The substrate processing method according to claim 1, wherein the first processing liquid is obtained by adding the fine particles to any one of pure water, deionized water, and a mixed solution of ammonia water and hydrogen peroxide solution.   The substrate processing method of Claim 2 provided with the 1st process liquid production | generation process which mixes a polystyrene latex liquid and the said liquid, and produces | generates the said 1st process liquid containing the polystyrene fine particle as said microparticles | fine-particles.   In the freezing step, the cooling gas is discharged from a cooling nozzle that scans and moves relative to the surface of the substrate on which the liquid film is formed, and the cooling gas is supplied to the liquid film to supply the liquid film. The substrate processing method according to claim 1, wherein the substrate is frozen.   The substrate processing method according to claim 1, wherein the first processing liquid contains a surfactant. Substrate holding means for holding the substrate substantially horizontally;
A first treatment liquid for producing a first treatment liquid by mixing a slurry containing fine particles of polystyrene or silica with any one of pure water, deionized water, and a mixed solution of ammonia water and hydrogen peroxide water. Generating means;
First processing liquid supply means for supplying the first processing liquid to the surface of the substrate held by the substrate holding means to form a liquid film of the first processing liquid on the substrate surface;
A cooling gas supply means for supplying a cooling gas having a temperature lower than the freezing point of the first processing liquid to the surface of the substrate on which the liquid film is formed, and freezing the liquid film;
A substrate processing apparatus, comprising: a second processing liquid supply unit configured to supply a second processing liquid to the surface of the substrate on which the liquid film has been frozen and remove the frozen film of the liquid film. The substrate holding means rotates the substrate around a vertical axis,
The substrate processing apparatus according to claim 6, wherein the cooling gas supply unit includes a cooling nozzle that scans and moves along the surface of the substrate while discharging the cooling gas.

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