JP2009081370A - Substrate cleaning method, and substrate cleaning device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a substrate cleaning method and substrate cleaning device that can clean a surface of a substrate to be processed at a superior particle removal rate without damaging the substrate. <P>SOLUTION: The substrate is subjected to light etching before freeze cleaning. A surface of the substrate is lightly etched away by the light etching and contact parts between particles and the substrate surface are decreased, so that DIW forming a frozen film reaches contact removal parts. Then the DIW at the contact removal parts is frozen to become portions of the frozen film and then removed. Consequently, the particle removal rate is improved. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a semiconductor wafer, a glass substrate for photomask, a glass substrate for liquid crystal display, a glass substrate for plasma display, a substrate for FED (Field Emission Display), a substrate for optical disk, a substrate for magnetic disk, and a magneto-optical disk. Substrate cleaning in which a liquid film adhering to various substrates such as substrates for use (hereinafter simply referred to as “substrate”) is frozen to form a frozen film, and the substrate is cleaned by removing the frozen film from the substrate The present invention relates to a method and a substrate cleaning apparatus.

  In the manufacturing process of electronic components such as semiconductor devices, the cleaning process for the substrate surface is indispensable, and the technical requirement level for the cleaning process is increasing. For example, according to the International Technology Roadmap for Semiconductors 2005 Edition (International Technology Roadmap for Semiconductors 2005 Edition) created in 2005 by the Technical Committee for Semiconductor Technology Roadmap, there is the following description of the technical requirements for the cleaning step (non-patent) References 1 and 2). As for silicon loss, “IC manufacturers currently have a target of 1.0 Å for each cleaning step in the 90 nm generation, and 0.5 Å for each cleaning step in the 65 nm generation. It is not clear which number is required or what is possible, so it was set to 0.4 angstroms in 2008 and kept constant until 45 nm generation, then 0.3 angstroms until 32 nm generation After that, it was set to 0.2 Å. ” As for oxide film loss, “the IC manufacturer currently has a target of 1.0 angstrom for each cleaning step in the 90 nm generation and 0.5 angstrom for each cleaning step in the 65 nm generation. It is not clear which number is required or what is possible, so it was set to 0.4 angstrom in 2008 and kept constant up to 45 nm generation, and then to 32 nm generation It was set to 0.3 angstroms and thereafter 0.2 angstroms. "

  Thus, for example, a method described in Patent Document 1 has been proposed in order to satisfy the requirements for the cleaning process. In this substrate cleaning method, after a liquid film (water film) made of pure water is attached to the substrate surface, the water film is frozen. Thereby, the adhesion between the particles (contamination particles) adhering to the substrate surface due to volume expansion of the water film and the substrate is weakened, or the particles are detached from the substrate surface. Thereafter, by removing the frozen water film (frozen film) from the substrate, particles in the water film whose adhesion to the substrate is weakened or detached from the substrate surface are easily removed.

JP 2006-332396 A (FIG. 6) Semiconductor Technology Roadmap Technical Committee, “International Semiconductor Technology Roadmap 2005 Edition (Japanese Translation) Front-end Process”, Japan Electronics and Information Technology Industries Association, April 2006 Semiconductor Technology Roadmap Technical Committee, “International Semiconductor Technology Roadmap 2005 Edition (Japanese Translation) Front End Process”, [online], March 2003, Japan Electronics and Information Technology Industries Association, [searched August 30, 2007] , Internet <URL: http://strj-jeita.elisasp.net/strj/ITRS05/pdf/08_2005FEP.pdf>

  When the substrate is cleaned using a freezing technique, silicon loss and oxide film loss do not occur on the surface to be processed of the substrate, and damage to the substrate can be suppressed. However, the rate at which contaminants such as particles are removed from the substrate (hereinafter referred to as “particle removal rate”) is not necessarily sufficient, and further improvement in the particle removal rate is required.

  This invention is made in view of the said subject, and provides the board | substrate cleaning method and board | substrate cleaning apparatus which can wash | clean the to-be-processed surface of a board | substrate with the outstanding particle removal rate, without damaging a board | substrate. Objective.

  In order to achieve the above object, a substrate cleaning method according to the present invention includes a light etching process for supplying a processing liquid for performing light etching on a substrate to a processing surface of the substrate, and a processing that has undergone the light etching process. And a freeze washing step of removing the frozen film after forming the frozen film on the surface.

  In order to achieve the above object, the substrate cleaning apparatus according to the present invention includes a substrate holding means for holding the substrate and a processing liquid for performing light etching on the substrate. A processing liquid supply means for supplying to the surface to be processed, a freezing means for freezing a liquid film formed on the surface to be processed light-etched with the processing liquid to form a frozen film, and a removing means for removing the frozen film from the substrate It is characterized by having.

  In the invention thus configured (substrate cleaning method and apparatus), after the frozen film is formed on the surface to be processed of the substrate, the frozen film is removed and freeze cleaning is performed on the surface to be processed. Light etching is performed on the substrate before the freeze cleaning to improve the cleaning efficiency by freeze cleaning. That is, the surface to be processed of the substrate is lightly etched away by light etching, the contact portion between the particles and the surface to be processed is reduced, and the liquid component constituting the frozen film wraps around the contact removal portion. Then, the liquid component that has entered the contact removal portion is frozen and removed after becoming a part of the frozen film. As a result, the portion that contributes to freezing and cleaning is increased and the particle removal rate is improved. Note that “light etching” means that the surface to be processed is slightly etched within a range that does not affect the characteristics of the device formed on the substrate, and is a cleaning process described in Non-Patent Document 1. This means the etching level required in (1). For example, when the surface to be processed of the substrate is an oxide film, it means etching of 1.0 angstrom or less in the 90 nm generation and 0.5 angstrom or less in the 65 nm generation. Since light etching is performed at such an etching level to assist freeze cleaning, the particle removal rate can be improved without damaging the substrate.

  Here, in order to stop the light etching, the treatment liquid adhering to the surface to be treated may be replaced with a rinsing liquid. In this case, a rinsing liquid film can be formed after the replacement step, and the liquid film can be frozen to form a frozen film. Thus, the stop of the light etching can be accurately controlled by the replacement with the rinse liquid.

  In order to stop the light etching, the liquid film formed on the surface to be processed may be frozen by supplying the processing liquid without using the rinsing liquid. As described above, the light etching can be stopped and the frozen film can be simultaneously formed by the freezing process, the freezing washing process can be simplified, and the processing time can be shortened and the running cost can be reduced.

  Further, it is desirable to provide a liquid film forming step for forming the liquid film while adjusting the film thickness of the liquid film before the rinsing liquid or the processing liquid film is frozen as described above. Thus, the cleaning efficiency by freeze cleaning can be controlled by adjusting the film thickness.

  In addition, a cooling gas having a temperature lower than the freezing point of the liquid constituting the liquid film is locally discharged from the nozzle toward the surface to be processed, and at the same time, the nozzle is relative to the substrate along the surface to be processed. It may be moved to form a frozen film on the surface to be processed. According to this configuration, the cooling gas having a temperature lower than the freezing point of the liquid (for example, processing liquid or rinsing liquid) constituting the liquid film is locally discharged from the nozzle toward the processing surface of the substrate. Then, while discharging the cooling gas from the nozzle, the nozzle is moved relative to the substrate along the surface to be processed, and a frozen film is formed on the surface to be processed. That is, of the liquid adhering to the substrate with the relative movement, the region where the liquid is frozen spreads and a frozen film is formed on the surface to be processed. As described above, since the cooling gas supply part is limited to a partial region of the surface to be processed, the temperature reduction of the members provided around the substrate, such as a member for holding the substrate, is minimized. Can be stopped. Therefore, deterioration of those members can be suppressed.

  Further, the above-described light etching and freeze cleaning may be processed one by one in the same processing chamber. That is, while holding a single substrate by the single-wafer holding substrate holding means in the processing chamber, a processing liquid is supplied to the processing surface of the substrate to perform light etching, and a frozen film is formed on the processing surface of the substrate. And the frozen film may be removed from the substrate. In this way, a series of processes (light etching + freeze cleaning) can be continuously performed in the same processing chamber, and the substrate cleaning can be performed with a small space and high throughput.

  According to the present invention, since light etching is performed on the surface to be processed before freeze cleaning, particles can be effectively removed from the substrate and the particle removal rate can be improved.

  FIG. 1 is a view showing a first embodiment of a substrate cleaning apparatus according to the present invention. FIG. 2 is a block diagram showing a control configuration of the substrate cleaning apparatus of FIG. This apparatus uses a surface Wf of a substrate W such as a semiconductor wafer as a “surface to be processed” of the present invention, and performs a cleaning process for removing contaminants such as particles adhering to the substrate surface Wf. A substrate cleaning apparatus. In this apparatus, prior to performing a conventionally known freeze cleaning process, a light etching process is performed on the substrate surface Wf on which the fine pattern is formed. That is, the allowable range of silicon loss and oxide film loss described in Non-Patent Document 1, that is, etching of 1.0 angstrom or less in the 90 nm generation and 0.5 angstrom or less in the 65 nm generation is performed as “light etching” of the present invention. .

  The substrate cleaning apparatus includes a processing chamber 1 having a processing space for cleaning a 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, and a cooling 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 (corresponding to the “nozzle” of the present invention) The blocking member 5 is provided so as to face the surface Wf of the substrate W held by the spin chuck 2.

  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 its front surface (pattern forming surface) Wf facing upward and the back surface Wb facing downward. Thus, in this embodiment, the plurality of chuck pins 24 hold one substrate W and function as the “substrate holding means” and the “sheet holding substrate holding means” of the present invention.

  A rotation motor 31 is provided outside the spin chuck 2. A rotation shaft 33 is connected to the rotation motor 31. A scan arm 35 is connected to the rotation shaft 33 so as to extend in the horizontal direction, and the cooling nozzle 3 is attached to the tip of the scan arm 35. The scan motor 35 can be swung around the rotation shaft 33 by driving the rotation motor 31 in accordance with an operation command from the control unit 4.

  FIG. 3 is a view showing the operation of the cooling nozzle provided in the substrate cleaning apparatus of FIG. Here, FIG. 4A is a side view and FIG. 4B is a plan view. When the rotation motor 31 is driven to swing the scan arm 35, the cooling nozzle 3 faces the substrate surface Wf and moves from the movement locus T in FIG. It moves along the trajectory T toward the edge position Pe. Here, the rotation center position Pc of the substrate W is set above the substrate surface Wf and on the rotation center A0 of the substrate W. Further, the cooling nozzle 3 is movable to a standby position Ps retracted to the side of the substrate W. Thus, in this embodiment, the rotation motor 31 functions as a “drive mechanism” that moves the cooling nozzle 3 relative to the substrate W along the substrate surface Wf.

  The cooling nozzle 3 is connected to the cooling gas supply unit 15 (FIG. 2) and supplies the cooling gas from the cooling gas supply unit 15 to the cooling nozzle 3 in accordance with an operation command from the control unit 4. For this reason, when the cooling nozzle 3 is disposed to face the substrate surface Wf, the cooling gas is locally discharged from the cooling nozzle 3 toward the substrate surface Wf. Therefore, in a state where the cooling gas is discharged from the cooling nozzle 3, the control unit 4 moves the cooling nozzle 3 along the movement trajectory T while rotating the substrate W, so that the cooling gas is spread over the entire surface Wf of the substrate. Can supply. As a result, the entire liquid film 11 adhering to the substrate surface Wf can be frozen to form the frozen film 13 on the entire surface of the substrate surface Wf. Thus, in this embodiment, the cooling nozzle 3 and the rotation motor 31 function as “freezing means” of the present invention.

  The height of the cooling nozzle 3 from the substrate surface Wf varies depending on the supply amount of the cooling gas, but is set to, for example, 50 mm or less, preferably about several mm. The height of the cooling nozzle 3 and the supply amount of the cooling gas from the substrate surface Wf are as follows: (1) From the viewpoint of efficiently imparting the cold heat of the cooling gas to the liquid film 11, (2) The liquid film by the cooling gas It is determined experimentally from the viewpoint of stably freezing the liquid film so that the liquid level of the liquid is not disturbed.

  As the cooling gas, a gas having a temperature lower than the freezing point of the liquid constituting the liquid film 11 formed on the substrate W, such as nitrogen gas, oxygen gas, and clean air, is used. According to such a cooling gas, it is easy to remove contaminants contained in the cooling gas using a filter or the like before supplying the gas to the substrate W. Therefore, it is possible to prevent the substrate W from being contaminated when the liquid film 11 is frozen. In this embodiment, a liquid film 11 composed of DIW (deionized water) is formed as described later. Therefore, the cooling gas adjusted to a temperature lower than the freezing point of DIW constituting the liquid film 11 is used.

  Thus, in this embodiment, the cooling gas is locally discharged from the cooling nozzle 3 toward the substrate surface Wf. Then, while the substrate W is rotated, the cooling nozzle 3 is moved between the rotation center position Pc of the substrate W and the edge position Pe of the substrate W to form the frozen film 13 on the substrate surface Wf. For this reason, the supply region of the cooling gas is limited to a minute region on the substrate surface Wf, and the temperature decrease of the substrate peripheral member such as the spin chuck 2 can be minimized. Therefore, the frozen film 13 can be formed on the substrate surface Wf while suppressing the deterioration of the durability of the substrate peripheral member. As a result, even if the substrate peripheral member is formed of a resin material (resin material having chemical resistance) that is difficult to ensure cold resistance, deterioration of the material of the substrate peripheral member due to cold can be suppressed.

  Returning to FIG. 1, the description will be continued. The rotation support shaft 21 of the spin chuck 2 is a hollow shaft. A processing liquid supply pipe 25 for supplying DIW to the back surface Wb of the substrate W is inserted into the rotary spindle 21. The processing liquid supply tube 25 passes through an opening provided at the center of the spin base 23 and extends to a position close to the lower surface (back surface Wb) of the substrate W held by the spin chuck 2. A nozzle 27 that discharges the processing liquid toward the center of the lower surface of the substrate W is provided at the tip of the processing liquid supply pipe 25. The processing liquid supply pipe 25 is connected to the DIW supply unit 17, and DIW is supplied from the DIW supply unit 17.

  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 gas supply path 29 is connected to the dry gas supply unit 18 and can supply nitrogen gas as a dry gas to a space formed between the spin base 23 and the substrate back surface Wb. In this embodiment, nitrogen gas is supplied as the dry gas from the dry gas supply unit 18, but air, other inert gas, or the like may be discharged instead of the nitrogen gas.

  Further, a disc-shaped blocking member 5 having an opening at the center is provided above the spin chuck 2. The blocking member 5 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 5 is equal to or larger than the diameter of the substrate W. The blocking member 5 is mounted substantially horizontally on the lower end portion of the support shaft 51 having a substantially cylindrical shape, and the support shaft 51 is held rotatably about a vertical axis passing through the center of the substrate W by an arm 52 extending in the horizontal direction. . The arm 52 is connected to a blocking member rotating mechanism 53 and a blocking member lifting mechanism 54.

  The blocking member rotating mechanism 53 rotates the support shaft 51 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 53 is configured to rotate the blocking member 5 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 54 can cause the blocking member 5 to be close to and opposed to the spin base 23 in accordance with an operation command from the control unit 4, or to be separated. Specifically, the control unit 4 operates the blocking member elevating mechanism 54 so that when the substrate W is loaded into and unloaded from the apparatus, the control unit 4 is moved to a separation position (position shown in FIG. 1) above the spin chuck 2. The blocking member 5 is raised. On the other hand, when a predetermined process is performed on the substrate W, the blocking member 5 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 51 is finished to be hollow, and a gas supply path 55 communicating with the opening of the blocking member 5 is inserted into the support shaft 51. The gas supply path 55 is connected to the dry gas supply unit 18, and nitrogen gas is supplied from the dry gas supply unit 18. In this embodiment, nitrogen gas is supplied from the gas supply path 55 to the space formed between the blocking member 5 and the substrate surface Wf during the drying process after the freeze cleaning process for the substrate W. A liquid supply pipe 56 communicating with the opening of the blocking member 5 is inserted into the gas supply path 55, and a nozzle 57 is coupled to the lower end of the liquid supply pipe 56. The liquid supply pipe 56 is connected to the processing liquid supply unit 16 and the DIW supply unit 17 so that the processing liquid or DIW can be selectively supplied from the nozzle 57 to the substrate surface Wf in accordance with an operation command from the control unit 4. ing. In this embodiment, light etching is performed on the substrate surface Wf using hydrofluoric acid (hydrofluoric acid) as the processing liquid.

  Next, a cleaning process operation in the substrate cleaning apparatus configured as described above will be described with reference to FIGS. FIG. 4 is a flowchart showing the operation of the substrate cleaning apparatus of FIG. 5 and 6 are schematic views showing the operation of the substrate cleaning apparatus of FIG. In this apparatus, when an unprocessed substrate W is carried into the processing chamber 1, the control unit 4 controls each part of the apparatus to perform a series of processes (light etching + freezing cleaning + drying) on the surface Wf of the substrate W. Execute. Here, a fine pattern may be formed on the substrate surface Wf. That is, the substrate surface Wf is a pattern formation surface. Therefore, in this embodiment, the substrate W is carried into the processing chamber 1 with the substrate surface Wf facing upward, and is held by the chuck pins 24 of the spin chuck 2 (step S1). Note that the blocking member 5 is located at 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 5 is lowered to the facing position and is disposed close to the substrate surface Wf. As a result, the substrate surface Wf is covered in the state of being close to the substrate facing surface of the blocking member 5 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. Further, hydrofluoric acid is supplied from the nozzle 57 to the substrate surface Wf as the “treatment liquid” of the present invention. As a result, as shown in FIG. 5A, light etching for the substrate surface Wf is started (step S2). Then, the supply of the processing liquid from the nozzle 57 is stopped and the freezing cleaning process (step S3) is executed to stop the light etching and the freezing cleaning with the effort that the etching amount reaches the upper limit of the allowable range.

  In this freeze cleaning process (step S3), as shown in FIG. 5B, DIW is discharged from the nozzle 57 as a rinse liquid toward the substrate surface Wf, and the process liquid on the substrate surface Wf is washed away by the DIW. Is replaced with DIW (step S31). When the replacement process is completed in this manner, the substrate W is rotated at a predetermined rotation speed so that the DIW (rinse liquid) supplied to the substrate surface Wf is uniformly spread outward in the radial direction of the substrate W, and part of the substrate W Shake it out. As a result, as shown in FIG. 5C, the thickness of the liquid film is uniformly controlled over the entire surface of the substrate surface Wf, and a liquid film (film made of DIW) 11 having a predetermined thickness on the entire surface of the substrate Wf. Is formed (step S32: liquid film forming process).

  Thus, when the liquid film 11 composed of DIW is formed on the substrate surface Wf, the gap between the particles adhering to the substrate surface Wf and the substrate surface Wf is filled with DIW. In particular, in this embodiment, since the light etching process (step S2) is performed prior to the freeze cleaning process (step S3), the substrate surface Wf is lightly removed by etching and the particles adhering to the substrate surface Wf are removed from the substrate. The portion in contact with the surface Wf is reduced. For this reason, DIW also enters the contact portion where the liquid film has been reduced by light etching during the formation of the liquid film.

  Thus, when the liquid film forming process is completed, the liquid film freezing process is performed on the substrate W held on the spin chuck 2 with the liquid film 11 attached to the substrate surface Wf (step S33). That is, the control unit 4 disposes the blocking member 5 at the separated position, and discharges the cooling gas from the cooling nozzle 3 while moving the cooling nozzle 3 from the standby position Ps to the cooling gas supply start position, that is, the rotation center position Pc of the substrate W. Move. Then, the cooling nozzle 3 is gradually moved toward the edge position Pe of the substrate W while discharging the cooling gas toward the surface Wf of the substrate W being rotationally driven. As a result, the liquid film 11 formed on the substrate surface Wf is locally frozen and, as shown in FIG. 3 and FIG. 6A, the region (freezing) in which the liquid film 11 is frozen in the surface area of the substrate surface Wf. (Region) is expanded from the central part of the substrate surface Wf to the peripheral part. As a result, the entire liquid film 11 formed on the substrate surface Wf is frozen, and a frozen film 13 is formed on the entire surface of the substrate surface Wf (liquid film freezing process).

  When the liquid film freezing process is performed in this manner, the volume of the liquid film 11 entering between the substrate surface Wf and the particles adhering to the substrate surface Wf increases, and the particles are separated from the substrate surface Wf by a minute distance. Leave. In particular, in this embodiment, as described above, the portion where the DIW forming the liquid film 11 enters is expanded by the light etching process, so that the removal effect by volume expansion is enhanced. Even when a fine pattern is formed on the substrate surface Wf, the pressure applied to the pattern by the volume expansion of the liquid film 11 is equal in all directions, that is, the force applied to the pattern is offset. Therefore, only particles can be selectively removed from the substrate surface Wf without peeling or collapsing the pattern.

  When the freezing of the liquid film is completed, the control unit 4 moves the cooling nozzle 3 to the standby position Ps. Subsequently, a film removal process is performed on the substrate W (step S34). That is, the blocking member 5 is disposed at the opposing position, and the blocking member 5 is rotated together with the spin chuck 2. Also, before the frozen film 13 is melted, DIW is supplied from the nozzle 57 and the nozzle 27 to the front and back surfaces Wf and Wb of the substrate W that is rotationally driven. As a result, as shown in FIG. 6B, the supply of DIW to the front and back surfaces Wf and Wb of the substrate W being rotated is started, and the film removal process by DIW is executed. As a result, the frozen film 13 containing particles is melted and removed from the substrate surface Wf (film removal process). Thus, in this embodiment, the nozzle 57 functions as the “removing means” of the present invention.

  In this way, when the film removal process is completed, it is determined whether or not the freeze cleaning process for the substrate W is completed (step S35). If it is determined that the process is completed (YES in step S35), the process proceeds to step S4 described below, and the drying process of the substrate W is executed. On the other hand, if it is determined that the freeze cleaning process has not been completed (NO in step S35), the process returns to step S33, and the liquid film freezing process (step S33) and the film removing process (step S34) are repeatedly executed. That is, depending on the surface state of the surface Wf of the substrate W, which is the surface to be processed, or the particle size and type of the particles to be removed, the particles cannot be sufficiently removed from the surface Wf of the substrate W by one freeze cleaning process. In such a case, it is determined that it has not been completed. Thus, particles are removed from the surface Wf of the substrate W by repeatedly executing the liquid film freezing process and the film removing process a predetermined number of times. It should be noted that such a repeated execution number may be defined in advance as a process recipe, and the freeze cleaning process may be repeated for the number of executions defined by an appropriately selected process recipe.

  When the freeze cleaning process is completed, the control unit 4 increases the rotation speeds of the motors of the chuck rotating mechanism 22 and the blocking member rotating mechanism 53 to rotate the substrate W and the blocking member 5 at high speed. Thereby, the drying process (spin drying) of the substrate W is executed (step S4). After the drying process of the substrate W, the rotation of the substrate W and the blocking member 5 is stopped and the supply of nitrogen gas to the substrate W is stopped. Thereafter, the processed substrate W is unloaded from the processing chamber 1 (step S5).

  As described above, since the light etching is performed on the substrate W before the freeze cleaning process (step S3), the cleaning efficiency by the freeze cleaning can be increased. Moreover, although the surface (surface to be processed) Wf of the substrate W is removed by light etching, the etching amount is kept within the allowable range. Therefore, according to the first embodiment, the particle removal rate by freeze cleaning can be improved without damaging the pattern or the like formed on the substrate surface Wf by the light etching process (step S2).

  Moreover, in the said embodiment, it is what is called a single-wafer | sheet-fed board | substrate washing | cleaning apparatus which conveys the untreated board | substrate W to the process chamber 1 one by one, and wash | cleans it. Since the light etching process and the freeze cleaning process are continuously performed in the same processing chamber 1, the substrate cleaning can be performed in a small space and with a high throughput. In addition, since the present embodiment is a single-wafer method and light etching and freeze cleaning are continuously performed, the etching amount can be accurately controlled. Therefore, the amount of etching of the substrate surface Wf by the light etching process can be surely kept within an allowable range and damage to the substrate W can be prevented.

  Note that the etching amount by the light etching process (step S2) is desirably set according to the design value of the device formed on the substrate W. That is, when this embodiment is applied to the substrate W on which a device having a line width of 90 nm (90 nm generation) is formed, the light etching process is performed under the following conditions, for example, and it is excellent without causing damage. The surface Wf of the substrate W can be cleaned with a particle removal rate.

<Light etching conditions for 90 nm generation>
Treatment liquid concentration: Dilute hydrofluoric acid diluted 1000 times with DIW Treatment liquid temperature: 23 ° C
Treatment liquid flow rate: 2.0 l / min Substrate rotation speed: 800 rpm
Etching time: 10 seconds In addition, when this embodiment is applied to a substrate W on which a device having a line width of 65 nm (65 nm generation) is formed, for example, by performing a light etching process under the following conditions, damage is caused. The surface Wf of the substrate W can be cleaned with an excellent particle removal rate without giving it.

<Light etching conditions for 65 nm generation>
Treatment liquid concentration: Dilute hydrofluoric acid diluted 1000 times with DIW Treatment liquid temperature: 23 ° C
Treatment liquid flow rate: 2.0 l / min Substrate rotation speed: 800 rpm
Etching time: 5 seconds Even when other devices are formed, the light etching conditions can be set appropriately. Further, since the allowable range of light etching differs depending on the device to be formed on the substrate W, the light etching conditions corresponding to the type of the substrate W are stored in advance in a storage unit (not shown) of the control unit 4 and processed. You may comprise so that the light etching conditions according to the board | substrate W conveyed by the chamber 1 may be read from a memory | storage part. Thereby, it can respond to various board | substrates W, and can improve the versatility of an apparatus.

  FIG. 7 is a flowchart showing the operation of the second embodiment according to the present invention. FIG. 8 is a schematic diagram showing the operation of the second embodiment. The second embodiment is largely different from the first embodiment in that the replacement process (step S31) is omitted, and other configurations are basically the same. Therefore, in the following, the operation of the second embodiment will be described focusing on the differences.

  In this embodiment, when the substrate W is carried into the processing chamber 1 with the substrate surface Wf facing upward and is held by the spin chuck 2 (step S1), the substrate surface is the same as in the first embodiment. Light etching is performed on Wf (step S2: FIG. 8A). Then, before the etching amount reaches the upper limit of the allowable range, the supply of the processing liquid from the nozzle 57 is stopped, and the substrate W is rotated at a predetermined rotation speed so that the thickness of the liquid film is made uniform over the entire surface of the substrate surface Wf. To control. As a result, a liquid film (film made of a processing liquid) 11 having a predetermined thickness is formed on the entire substrate surface Wf (step S32: liquid film forming process).

  Thus, when the liquid film forming process is completed, the liquid film 11 made of the processing liquid is attached to the substrate surface Wf with respect to the substrate W held on the spin chuck 2 in the same manner as in the first embodiment. A liquid film freezing process is executed (step S33: FIG. 8C). As a result, the liquid film 11 is frozen to form a frozen film, but at the same time, the progress of the light etching is stopped. That is, in the first embodiment, the light etching is stopped by the replacement process, whereas in the second embodiment, the light etching is stopped simultaneously with the formation of the frozen film.

  After forming the frozen film in this manner, the substrate W is dried (step S4) after the film removal process (step S34: FIG. 8D) is performed on the substrate W, as in the first embodiment. ). Thereafter, the processed substrate W is unloaded from the processing chamber 1 (step S5).

  As described above, in the second embodiment as well, as in the first embodiment, light etching is performed on the substrate W before the freeze cleaning process (step S3), so that the second embodiment is formed on the substrate surface Wf. The cleaning efficiency by freeze cleaning can be increased without damaging the pattern or the like. Further, in the second embodiment, in order to stop the light etching, the light film 11 formed on the substrate surface Wf is frozen by supplying the processing liquid without using the rinse liquid to stop the light etching and form the frozen film. Going at the same time. Therefore, the freeze cleaning process can be simplified, and the processing time can be shortened and the running cost can be reduced.

  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-described embodiment, hydrofluoric acid is used as the processing liquid, but any chemical liquid that can perform light etching on the substrate W can be used. For example, a mixed solution (SC1 solution) containing ammonia water and hydrogen peroxide water can be used as the treatment liquid. As the mixing ratio, for example, (ammonia water: hydrogen peroxide water: DIW) = (1: 1: 50) may be set.

  In the above-described embodiment, the film removal process (step S34) is performed using DIW, but the film removal process may be performed using a liquid other than DIW. For example, an SC1 solution may be used, and in this case, the following effects can be obtained. The zeta potential (electrokinetic potential) of the solid surface in the alkaline processing liquid such as the SC1 solution has a relatively large value (negative value). Therefore, when the SC1 solution is supplied to the substrate surface Wf and the space between the substrate surface Wf and the particles on the substrate surface Wf is filled with the SC1 solution, a large repulsive force acts between the substrate surface Wf and the particles. . Thereby, the detachment of particles from the substrate surface Wf can be promoted. Further, it is possible to prevent particles once separated from the substrate W from reattaching to the substrate W due to a repulsive force due to the zeta potential. In this way, when the film removal process is performed with the SC1 solution or the like, the drying process is performed after the rinse process with a rinse liquid such as DIW.

  In the above embodiment, the surface Wf (pattern forming surface) of the substrate W is the “surface to be processed” of the present invention, and the substrate surface Wf is subjected to the freeze cleaning process. However, the present invention can be applied to an apparatus that performs a freeze cleaning process on the back surface Wb of the substrate W or on the front and back surfaces Wf and Wb of the substrate W.

  In the above embodiment, the frozen film is formed on the substrate surface by moving the cooling nozzle 3 relative to the substrate W along the substrate surface while discharging the cooling gas from the cooling nozzle 3. The forming method (liquid film freezing method) is not limited to this. For example, the liquid film may be frozen using a facing member having a substrate facing surface that can face the non-frozen film forming surface opposite to the surface to be processed (frozen film forming surface) of the substrate W. In this case, the liquid film can be frozen by disposing the counter member in close proximity to the substrate W and setting the surface temperature of the substrate facing surface to a temperature lower than the freezing point of the liquid constituting the liquid film.

  In addition, although a frozen film is formed for each substrate W, the freeze cleaning process may be performed in the form of a batch process in which a plurality of substrates W are processed simultaneously.

  This invention adheres to all substrates including semiconductor wafers, photomask glass substrates, liquid crystal display glass substrates, plasma display glass substrates, FED substrates, optical disk substrates, magnetic disk substrates, magneto-optical disk substrates, etc. The obtained liquid film is frozen to form a frozen film, and the frozen film is removed from the substrate, whereby the substrate can be applied to a substrate cleaning method and a substrate cleaning apparatus that perform a cleaning process on the substrate.

BRIEF DESCRIPTION OF THE DRAWINGS It is a figure which shows 1st Embodiment of the board | substrate cleaning apparatus concerning this invention. It is a block diagram which shows the control structure of the board | substrate cleaning apparatus of FIG. It is a figure which shows operation | movement of the cooling nozzle with which the board | substrate cleaning apparatus of FIG. 1 was equipped. It is a flowchart which shows operation | movement of the board | substrate cleaning apparatus of FIG. It is a schematic diagram which shows operation | movement of the board | substrate cleaning apparatus of FIG. It is a schematic diagram which shows operation | movement of the board | substrate cleaning apparatus of FIG. It is a flowchart which shows operation | movement of 2nd Embodiment concerning this invention. It is a schematic diagram which shows operation | movement of 2nd Embodiment.

Explanation of symbols

2 ... Spin chuck (substrate holding means, single wafer holding means)
3. Cooling nozzle (nozzle, freezing means)
DESCRIPTION OF SYMBOLS 11 ... Liquid film 13 ... Frozen film 16 ... Process liquid supply part (process liquid supply means)
17 ... DIW supply unit (rinse solution supply means)
24... Chuck pin (substrate holding means, single wafer holding substrate holding means)
31 ... Rotation motor (drive mechanism, freezing means)
57 ... Nozzle (removing means)
W ... Board

Claims (11)

A light etching step of supplying a processing liquid for performing light etching on the substrate to the surface to be processed;
A substrate cleaning method comprising: a freeze cleaning step of removing the frozen film after forming the frozen film on the surface to be processed that has undergone the light etching step.   The freeze cleaning step includes a replacement step of replacing the treatment liquid with a rinsing liquid, and a liquid that forms a frozen film by freezing a liquid film formed on the surface to be processed by supplying the rinse liquid in the replacement step The substrate cleaning method according to claim 1, comprising a film freezing step and a frozen film removing step for removing the frozen film.   The freeze cleaning step includes a liquid film freezing step of freezing a liquid film formed on the surface to be processed by supplying the processing liquid in the light etching step to stop the progress of light etching and forming a frozen film. The substrate cleaning method according to claim 1, further comprising a frozen film removing step of removing the frozen film.   4. The substrate cleaning method according to claim 2, wherein the freeze cleaning step further includes a liquid film forming step of forming the liquid film while adjusting a film thickness of the liquid film before the liquid film freezing step.   The liquid film freezing step includes a cooling gas discharge step of locally discharging a cooling gas having a temperature lower than the freezing point of the liquid constituting the liquid film from the nozzle toward the processing surface, and the cooling gas discharge step. 5. The method according to claim 1, further comprising a relative movement step of forming the frozen film on the surface to be processed by moving the nozzle relative to the substrate along the surface to be processed in parallel. Substrate cleaning method.   6. The substrate cleaning method according to claim 1, wherein the light etching step is a step of etching and removing the surface to be processed by 1 angstrom or less with the processing solution.   The substrate cleaning method according to claim 1, wherein the treatment liquid is hydrofluoric acid. Substrate holding means for holding the substrate;
A processing liquid supply means for supplying a processing liquid for performing light etching on the substrate to a surface to be processed of the substrate held by the substrate holding means;
Freezing means for forming a frozen film by freezing a liquid film formed on the surface to be processed light-etched by the processing liquid;
A substrate cleaning apparatus, comprising: removal means for removing the frozen film from the substrate. A rinsing liquid supply means for replacing the processing liquid with the rinsing liquid by supplying a rinsing liquid to the surface to be processed to form a liquid film of the rinsing liquid on the surface to be processed;
The freezing means includes a nozzle that locally discharges a cooling gas having a temperature lower than the freezing point of the rinse liquid toward the surface to be processed, and the nozzle is moved relative to the substrate along the surface to be processed. 9. The frozen film is formed on the processing surface by moving the nozzle relative to the substrate by the drive mechanism while discharging the cooling gas from the nozzle. Substrate cleaning equipment.   The freezing means includes a nozzle that locally discharges a cooling gas having a temperature lower than a freezing point of the processing liquid toward the processing surface, in which light etching with the processing liquid is in progress, and the nozzle to the processing target. A drive mechanism that moves relative to the substrate along a processing surface, and the nozzle moves the nozzle relative to the substrate by the drive mechanism while discharging the cooling gas from the nozzle. The substrate cleaning apparatus according to claim 8, wherein the liquid film formed on the surface to be processed is frozen by supplying the liquid to stop the progress of light etching and form the frozen film. Further comprising a processing chamber;
The substrate holding means is a single wafer holding substrate holding means for holding one substrate,
The processing liquid supply means supplies the processing liquid to a surface to be processed of the substrate held by the substrate holding means for holding a single wafer in the processing chamber,
The freezing means forms a frozen film on the surface to be processed of the substrate held by the single wafer holding substrate holding means in the processing chamber,
11. The substrate cleaning apparatus according to claim 8, wherein the removing unit removes the frozen film from the substrate held by the single-wafer holding substrate holding unit in the processing chamber.

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