Patent Publication Number: US-2007119476-A1

Title: Substrate processing apparatus and substrate processing method

Description:
BACKGROUND OF THE INVENTION  
      1. Field of the Invention  
      The present invention relates to a substrate processing apparatus that performs a predetermined process on a substrate and a substrate processing method.  
      2. Description of the Background Art  
      Conventionally, in order to perform a variety of processes on a substrate such as a semiconductor wafer, glass substrate for a photomask, glass substrate for a liquid crystal display, glass substrate for an optical disc or the like, a substrate processing apparatus is used.  
      In a substrate processing apparatus, for example, by supplying a substrate with a chemical solution of BHF (buffered hydrofluoric acid), DHF (diluted hydrofluoric acid), hydrofluoric acid, hydrochloric acid, sulfuric acid, nitric acid, phosphoric acid, acetic acid, oxalic acid, ammonia or the like, or a mixture thereof, a surface process of the substrate (hereinafter, called“chemical solution process”) is performed.  
      As a substrate processing apparatus for performing a chemical solution process, a sheet-type substrate processing apparatus is disclosed in JP 2005-191144 A. In the following, description will be given for the structure and operation of a substrate processing apparatus shown in JP 2005-191144 A.  
      FIGS.  18  to  21  are views for explaining the structure and operation of a conventional substrate processing apparatus.  FIG. 18  shows the structure of a cleaning processing unit provided in a substrate processing apparatus of JP 2005-191144 A.  
      As shown in  FIG. 18 , a cleaning processing unit  900  includes a spin chuck  921  for allowing rotation of a substrate W about a vertical rotation axis passing through the center of the substrate W while keeping the substrate W horizontal. The spin chuck  921  is secured to the upper end of a rotary shaft  925  rotated by a chuck rotation-driving mechanism (not shown).  
      Above the spin chuck  921 , an oxidation processing nozzle  950  and an etching nozzle  970  are provided in a movable manner.  
      The oxidation processing nozzle  950  is supplied with ozone water. Thus, the ozone water can be supplied to the surface of the substrate W. The etching nozzle  970  is supplied with hydrogen fluoride water. Thus, the hydrogen fluoride water can be supplied to the surface of the substrate W.  
      When the ozone water is supplied to the surface of the substrate W, the oxidation processing nozzle  950  is situated above the substrate W, and when the hydrogen fluoride water is supplied to the surface of the substrate W, the oxidation processing nozzle  950  is retracted to a predetermined position.  
      When the ozone water is supplied to the surface of the substrate W, the etching nozzle  970  is retracted to a predetermined position, and when the hydrogen fluoride water is supplied to the surface of the substrate W, the etching nozzle  970  is positioned above the substrate W.  
      The spin chuck  921  is housed in a processing cup  923 . Inside the processing cup  923 , a cylindrical partition wall  933  is provided. Also, a drain space  931  provided for draining the ozone water used in the process of the substrate W is formed to surround the circumference of the spin chuck  921 . Further, between the processing cup  923  and the partition wall  933 , a solution recovery space  932  for recovering the hydrogen fluoride water used in the process of substrate W is formed to surround the drain space  931 .  
      A drain pipe  934  is connected to the drain space  931  for leading the ozone water to a drain processing device (not shown), and a recovery pipe  935  is connected to the solution recovery space  932  for leading the hydrogen fluoride water to a recovery processing device (not shown).  
      Above the processing cup  923 , a guard  924  is provided for preventing the ozone water or the hydrogen fluoride water from the substrate W from scattering outwardly. The guard  924  has a rotation symmetric shape with respect to the rotary shaft  925 . In the inner face of the upper end of the guard  924 , a drain guiding groove  941  having a generally V-shaped cross section is annularly formed.  
      Further, in the inner face of the lower end of the guard  924 , a recovery liquid guiding part  942  formed of a slant face which is inclined outwardly and downwardly is provided. Near the upper end of the recovery liquid guiding part  942 , a partition wall-housing groove  943  for receiving the partition wall  933  of the processing cup  923  is formed.  
      The guard  924  is supported so as to be movable up and down by a guard lifting mechanism (not shown) composed of a ball screw mechanism or the like.  
      The guard lifting mechanism moves up and down the guard  924  between a circulation position P 2  in which the recovery liquid guiding part  942  is opposite to the outer circumference of the substrate W held by the spin chuck  921  and a drain position P 3  in which the drain guiding groove  941  is opposite to the outer circumference of the substrate W held by the spin chuck  921 .  
      When the upper end of the guard  924  is in the circulation position P 2 , as shown in  FIG. 19 , the hydrogen fluoride water scattering outward from the substrate W is led to the solution recovery space  932  by the recovery liquid guiding part  942  and recovered through the recovery pipe  935 . On the other hand, when the upper end of the guard  924  is in the drain position P 3 , as shown in  FIG. 20 , the ozone water scattering outward from the substrate W is led to the drain space  931  by the drain guiding groove  941 , and drained out through the drain pipe  934 . With the above structure, the drainage of the ozone water and the recovery of the hydrogen fluoride water are achieved.  
      In the above substrate processing apparatus, the guard lifting mechanism moves the guard  924  so that the upper end of the guard  924  is in a position lower than the level of the substrate W held by the spin chuck  921  (carrying in and out position P 1 ) when the substrate W is carried in or carried out to/from the cleaning processing unit  900 , as shown in  FIG. 21 . In this state, the substrate W is carried onto the spin chuck  921 , or the substrata W is carried out from the spin chuck  921 .  
      The cleaning processing unit  900  having the structure as described above, however, has the following problem. The problem will be described with reference to  FIG. 22 .  
       FIG. 22  is a view for explaining the problem associated with the conventional cleaning processing unit  900 .  
      As described above, in the chemical solution process, the upper end of the guard  924  is moved to the circulation position P 2  in order to recover the chemical solution used in the process. In this case, the chemical solution scattering from the substrate W is received by the recovery liquid guiding part  942  of the guard  924  and flows down under guidance of the shape thereof.  
      Then the chemical solution having flown to the lower end of the guard  924  further flows down along the inner wall face of the processing cup  923  and is led to the recovery pipe  935 .  
      In the chemical solution process, a chemical solution containing a salt such as BHF which is a mixture solution of ammonium fluoride and hydrogen fluoride, and a mixture solution containing ammonium fluoride and phosphoric acid may be used as well as the aforementioned hydrogen fluoride water.  
      If the chemical solution containing a salt remains on the guard  924  and on the inner wall face of the processing cup  923 , or the atmosphere of the chemical solution containing a salt remains in the solution recovery space  932 , the chemical solution is gradually dried with the time, so that the salt contained in the chemical solution precipitates, and the precipitates (deposits J) adhere to members (peripheral members) provided in the periphery of the spin chuck  921 .  
      In this manner, the deposits J on the members (peripheral members) provided around the spin chuck  921  may be stripped off during the operation of the cleaning processing unit  900 .  
      Further, the deposits J of the chemical solution also adhere to the outer wall face of the guard  924  with which the chemical solution does not actually come into direct contact. When the guard  924  moves up or down in the presence of the deposits J on the outer wall face of the guard  924 , the deposits J may be stripped off the outer wall face.  
      When the deposits J on the peripheral members of the spin chuck  921  are stripped off as described above, the stripped deposits J may scatter in the form of particles, and adhere to the substrate W during the process or carrying. As a result, processing defects occur on the substrate W.  
      Therefore, in order to sufficiently prevent the processing defects in the substrate W, it is necessary to clean the peripheral members of the spin chuck  921 . For achieving this, conventionally, the peripheral members of the spin chuck  921  are cleaned while the operation of the substrate processing apparatus is stopped.  
      Stopping the operation of the substrate processing apparatus to clean the peripheral members of the spin chuck  921  will deteriorate the throughput of the substrate processing.  
     SUMMARY OF THE INVENTION  
      It is an object of the present invention to provide a substrate processing apparatus and a substrate processing method capable of sufficiently preventing processing defects of the substrate caused by adhesion of a chemical solution to members without reducing the throughput.  
      (1) A substrate processing apparatus according to one aspect of the present invention includes a substrate holding device that folds a substrate, a chemical solution supplying device that supplies the substrate held by the substrate holding device with a chemical solution, a member provided in the position where the chemical solution scattering from the substrate held by the substrate holding device adheres, a cleaning liquid supplying device that cleans the member by supplying the member with a cleaning liquid having the same ingredients as the chemical solution without being in contact with the substrate held by the substrate holding device, and a recovering device that recovers the chemical solution supplied by the chemical solution supplying device and the cleaning liquid supplied to the member by the cleaning liquid supplying device.  
      In this substrate processing apparatus, the substrate held by the substrate holding device is supplied with the chemical solution by the chemical solution supplying device for processing of the substrate. At this time the chemical solution supplied to the substrate scatters peripherally and adheres to the member.  
      The cleaning liquid having the same ingredients as the chemical solution is supplied by the cleaning liquid supplying device to the member to which the chemical solution adheres without being in contact with the substrate. In this way, the member is cleaned with the clean cleaning liquid.  
      Since the member is cleaned with the cleaning liquid having the same ingredients as the chemical solution, it is possible to clean the member at the time of processing the substrate, or at the time of supplying the substrate held by the substrate holding device with the chemical solution. Therefore, it is possible to clean the member efficiently without reducing the throughput of the substrate processing.  
      Even when the chemical solution remains on the member, by supplying the cleaning liquid having the same ingredients to the chemical solution that remains, it is possible to prevent the chemical solution from being dried. Thus, generation of precipitates from the chemical solution is prevented, and generation of particles from the precipitates of the chemical solution can be prevented.  
      Furthermore, when the precipitates from the chemical solution adhere to the member, the precipitates can be readily dissolved and washed out by the cleaning liquid having the same ingredients as the chemical solution. Thus, generation of particles from the precipitates of the chemical solution is prevented.  
      In this manner, processing defects on the substrate is sufficiently prevented by preventing generation of particles from the precipitates of the chemical solution.  
      Further, the chemical solution supplied to the substrate and the cleaning liquid supplied to the member are recovered by a recovering device. As a result, the recovered chemical solution and cleaning liquid can be reused. This reduces the production cost of the substrate.  
      (2) The concentration of the cleaning liquid supplied to the member by the cleaning liquid supplying device may be substantially equal to that of the chemical solution supplied to the substrate by the chemical solution supplying device.  
      In this case, the chemical solution and the cleaning liquid recovered by the recovering device can be reused easily for processing of the substrate without readjustment of concentrations thereof. Thus, the structure of the recovering device can be simplified, and the production cost of substrate can be sufficiently reduced.  
      (3) The cleaning liquid supplying device may supply the member with a cleaning liquid in which a gas is mixed. In this case, the bubbles compressed by the internal pressure of the cleaning liquid supplying device are expanded as they are supplied to the member from the cleaning liquid supplying device. Thus, the cleaning liquid is injected at a large spread angle from the cleaning liquid supplying device. Thus, a wide range of the member can be cleaned.  
      (4) The substrate processing apparatus may further includes a controller that controls supply of the cleaning liquid to the member, and the controller may control the cleaning liquid supplying device so that the cleaning liquid is supplied to the member while the chemical solution is supplied to the substrate by the chemical solution supplying device.  
      In this case, while the chemical solution is supplied to the substrate, the controller controls the cleaning liquid supplying device to supply the member with the cleaning liquid. Thus, the chemical solution adhering to the member is prevented from remaining and being dried. In addition, generation of precipitates from the chemical solution adhering to the member is prevented. As a result, generation of particles from the precipitates of the chemical solution is prevented.  
      Further, since the member is cleaned during processing of the substrate, reduction in throughput of the substrate processing is securely avoided.  
      (5) The substrate processing apparatus may further includes a controller that controls supply of the cleaning liquid to the member, and the controller may control the cleaning liquid supplying device to intermittently supply the member with the cleaning liquid.  
      In this case, since the cleaning liquid having the same ingredients as the chemical solution is intermittently supplied to the member to which the chemical solution adheres, it is possible to prevent the chemical solution adhering to the member from remaining and being dried. Further, generation of precipitates from the chemical solution adhering to the member is prevented. As a result, generation of particles from the precipitates of the chemical solution is prevented.  
      (6) The substrate processing apparatus may further includes a controller that controls supply of the cleaning liquid, and a detector that provides the controller with a detection signal indicating change in surface condition in a part of the member where the chemical solution scattering from the substrate held by the substrate holding device adheres, and the controller may control the cleaning liquid supplying device to supply the member with the cleaning liquid based on the detection signal provided by the detector.  
      In this case, change in surface condition in a part of the member where the chemical solution adheres is provided by the detector as a detection signal to the controller. Based on the detection signal, the controller controls the cleaning liquid supplying device to supply the member with the cleaning liquid. Thus, the member can be cleaned when precipitates of the chemical solution adhere to the member, so that wasteful consumption of the cleaning liquid can be prevented.  
      (7) The substrate processing apparatus may further include a dissolving liquid supplying device that supplies a part of the member and the cleaning liquid supplying device where the cleaning liquid supplied from the cleaning liquid supplying device adheres, with a dissolving liquid having different ingredients from the cleaning liquid supplied to the member by the cleaning liquid supplying device and capable of dissolving the cleaning liquid.  
      In this case, a part of the member and the cleaning liquid supplying device where the cleaning liquid supplied from the cleaning liquid supplying device adheres is supplied with a dissolving liquid having different ingredients. Thus, when the cleaning liquid remains on the member and on the cleaning liquid supplying device, the cleaning liquid can be dissolved by the dissolving liquid. As a result, the cleaning liquid remaining in the member is prevented from being dried, and generation of the precipitates from the cleaning liquid remaining on the member is prevented. As a result, generation of particles from the precipitates of the cleaning liquid is prevented, and processing defects of substrate is prevented.  
      (8) The cleaning liquid supplying device may have a discharge opening through which the cleaning liquid is discharged, and the dissolving liquid supplying device may supply the discharge opening of the cleaning liquid supplying device with the dissolving liquid.  
      In this case, the cleaning liquid is discharged through the discharge opening of the cleaning liquid supplying device. By the dissolving liquid supplying device, the dissolving liquid is supplied to the discharge opening of the cleaning liquid supplying device. Thus, the cleaning liquid adhering in the vicinity of the discharge opening of the cleaning liquid supplying device is washed out by the dissolving liquid. Thus, generation of particles from the precipitates of the cleaning liquid is prevented, and processing defects of substrate is prevented.  
      (9) The substrate processing apparatus may further include a rinse liquid supplying device that supplies the substrate held by the substrate holding device with a rinse liquid for washing out the chemical solution remaining on the substrate, and the dissolving liquid supplying device may supply the member and the cleaning liquid supplying device with the dissolving liquid at the time of supplying the rinse liquid.  
      In this case, the rinse liquid is supplied to the substrate by the rinse liquid supplying device. When the rinse liquid is supplied to the substrate, the dissolving liquid is supplied to the member and the cleaning liquid supplying device by the dissolving liquid supplying device.  
      Thus, it is possible to wash out the cleaning liquid remaining in the member and the cleaning liquid supplying device at the time of processing by the rinse liquid, so that reduction in throughput of substrate processing is securely prevented.  
      (10) The substrate processing apparatus may further include a rotation driving device that rotates the substrate holding device for drying the substrate, and the dissolving liquid supplying device may supply the dissolving liquid to the member and the cleaning liquid supplying device at the time of drying the substrate.  
      In this case, the substrate holding device is rotated by the rotation driving device. In this manner, the substrate held by the substrate holding device can be dried. At the time of drying the substrate, the dissolving liquid is supplied to the member and the cleaning liquid supplying device by the dissolving liquid supplying device.  
      Thus, it is possible to wash out the cleaning liquid remaining in the member and the cleaning liquid supplying device at the time of drying the substrate, and reduction in throughput of substrate processing is securely prevented.  
      (11) The substrate processing apparatus may further include a circulation system that returns the chemical solution recovered by the recovering device to the chemical solution supplying device, and the member may include a guiding member that leads the chemical solution supplied to the substrate by the chemical solution supplying device and the cleaning liquid supplied to the member by the cleaning liquid supplying device to the recovering device.  
      In this case, the chemical solution supplied to the substrate by the chemical solution supplying device and the cleaning liquid supplied to the member by the cleaning liquid supplying device are led to the recovering device by the guiding member. The chemical solution recovered by the recovery member is returned to the chemical solution supplying device by the circulation system. The chemical solution recovered by the recovery member can further be supplied to the substrate from the chemical solution supplying device.  
      In this manner, by reusing the chemical solution supplied to the substrate by the chemical solution supplying device and the cleaning liquid supplied to the member by the cleaning liquid supplying device for processing of a substrate, it is possible to sufficiently reduce the production cost of the substrate.  
      When the cleaning liquid is led to the recovery member by the guiding member, the guiding member is also cleaned by the cleaning liquid. Therefore, at the time of substrate processing, it is possible to clean the guiding member without deteriorating the throughput in substrate processing.  
      (12) The guiding member may include an anti-scattering member that is provided so as to surround the substrate holding device and receives a chemical solution scattering from the substrate held by the substrate holding device.  
      In this case, the chemical solution scattering from the substrate held by the substrate holding device is received by the anti-scattering member provided so as to surround the substrate holding device and led to the recovering device. Thus, the chemical solution scattering from the substrate is prevented from scattering still outwardly. Therefore, it is possible to securely lead the chemical solution scattering from the substrate to the recovering device.  
      When the cleaning liquid is led to the recovery member by the anti-scattering member of the guiding member, the anti-scattering member is also cleaned by the cleaning liquid. Therefore, it is possible to clean the anti-scattering member at the time of substrate processing without reducing the throughput of the substrate processing.  
      (13) The guiding member may further include a receiving member that is provided below the anti-scattering member and receives the chemical solution flowing down from the anti-scattering member and leads the chemical solution to the recovering device.  
      In this case, the chemical solution flowing down from the anti-scattering member is received by the receiving member and led to the recovering device. Thus, the chemical solution received by the anti-scattering member can be securely led to the recovering device.  
      When the cleaning liquid is led to the recovery member by the receiving member of the guiding member, the receiving member is also cleaned with the cleaning liquid. Therefore, it is possible to clean the receiving member at the time of substrate processing without reducing the throughput of the substrate processing.  
      (14) The cleaning liquid supplying device may include a cylindorical member provided along an inner wall face of the guiding member and having a plurality of cleaning liquid supply openings opposite to the inner wall face of the guiding member.  
      In this case, the cleaning liquid is supplied to the inner wall face of the guiding member through the plurality of the cleaning liquid supply openings. Thus, the inner wall face of the guiding member can be widely cleaned by the cylindorical member having a simple structure.  
      (15) The chemical solution may be a removing liquid that removes contaminants on the surface of the substrate. In this case, contaminants on the surface of the substrate are removed by the chemical solution supplied to the substrate. Thus, it is possible to clean the surface of the substrate.  
      By cleaning the member with the cleaning liquid having the same ingredients as the chemical solution, it is possible to remove the contaminants together with the chemical solution that adheres to the member.  
      (16) The chemical solution may be a solution containing a salt. Precipitates of salt are likely to occur as a result of drying of such a chemical solution. Therefore, by cleaning the member with the cleaning liquid having the same ingredients as the chemical solution, it is possible to dissolve and remove the precipitates of the chemical solution that adheres to the member.  
      (17) A substrate processing method according to another aspect of the present invention includes the steps of processing a substrate by supplying a substrate held by the substrate holding device with a chemical solution, cleaning the member by supplying a member provided in a position where the chemical solution scattering from the substrate adheres, with a cleaning liquid having the same ingredients as the chemical solution without being in contact with the substrate held by the substrate holding device, and recovering the chemical solution supplied to the substrate and the cleaning liquid supplied to the member.  
      In this substrate processing method, a substrate is processed while the chemical solution is supplied to the substrate held by the substrate holding device. At this time, the chemical solution supplied to the substrate scatters circumferentially and adheres to the member.  
      The cleaning liquid having the same ingredients as the chemical solution is supplied to the member to which the chemical solution adheres without being in contact with the substrate. Thus, the member is cleaned with a clean cleaning liquid.  
      Since the member is cleaned with the cleaning liquid having the same ingredients as the chemical solution, the member can be cleaned during the processing of the substrate, or during supply of the chemical solution to the substrate held by the substrate holding device. Thus, it is possible to clean the member efficiently without deteriorating the throughput of the substrate processing.  
      Even when the chemical solution remains on the member, by supplying the cleaning liquid having the same ingredients with the chemical solution that remains, the chemical solution is prevented from being dried. Thus, generation of particles from the dried matter of the chemical solution is prevented.  
      Furthermore, when precipitates of the chemical solution adhere to the member, the precipitates can be easily dissolved and washed out by the cleaning liquid having the same ingredients as the chemical solution. Thus, generation of particles from the precipitates of the chemical solution is prevented.  
      In this way, generation of particles from the precipitates of the chemical solution is prevented, so that the processing defects on the substrate is sufficiently prevented.  
      Further, the chemical solution supplied to the substrate and the cleaning liquid supplied to the member are recovered. Thus, the recovered chemical solution and cleaning liquid may be reused. As a result, the production cost for the substrate is reduced.  
      (18) The step of cleaning the member may further include a step of supplying a member with a cleaning liquid while the chemical solution is supplied to the substrate.  
      In this case, the cleaning liquid is supplied to the member while the chemical solution is supplied to the substrate. Thus, the chemical solution adhering to the member is prevented from remaining and being dried. Further, generation of the precipitates from the chemical solution adhering to the member is prevented. As a result, generation of particles from the precipitates of the chemical solution is prevented.  
      Further, since the member is cleaned during the substrate processing, reduction in throughput of the substrate processing is securely prevented.  
      (19) The step of cleaning the member may include a step of intermittently supplying the cleaning liquid to the member. In this case, since the member to which the chemical solution adheres is intermittently supplied with the cleaning liquid having the same ingredients as the chemical solution, the chemical solution adhering to the member is prevented from remaining and being dried. Further, precipitation of the chemical solution adhering to the member is prevented. As a result, generation of particles from the precipitates of the chemical solution is prevented.  
      (20) The step of cleaning the member may include the steps of detecting change in surface condition of a part of the member where the chemical solution scattering from the substrate adheres, and controlling supply of the cleaning liquid to the member based on the detection of change in surface condition.  
      In this case, change in surface condition of a part of the member where the chemical solution adheres is detected, and supply of the cleaning liquid to the member is controlled based on the detection. Thus, wasteful consumption of the cleaning liquid is prevented because the member can be cleaned when the precipitates of the chemical solution adhere to the member.  
      Other features, elements, characteristics, and advantages of the present invention will become more apparent from the following description of preferred embodiments of the present invention with reference to the attached drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       FIG. 1  is a plan view of a substrate processing apparatus according to a first embodiment;  
       FIG. 2  is a view for explaining the structure of a cleaning processing unit in the substrate processing apparatus according to the first embodiment;  
       FIG. 3  is a view for explaining the structure of a guard cleaning nozzle of  FIG. 2 ;  
       FIG. 4  is a view for explaining attachment of the guard cleaning nozzles in  FIG. 2  to a processing cup;  
       FIG. 5  is an enlarged sectional view showing the state in which the guard cleaning nozzle is attached to the upper end of the processing cup;  
       FIG. 6  is a view showing a plurality of examples of timing of cleaning of a splash guard;  
       FIG. 7  is a view for explaining timing of cleaning when a deposit detector is used;  
       FIG. 8  is a view showing a cleaning process of the splash guard;  
       FIG. 9  is a view for explaining the effects of mixing a gas into the first cleaning liquid to be injected from the guard cleaning nozzle;  
       FIG. 10  is a system diagram of piping in the substrate processing apparatus of  FIG. 1 ;  
       FIG. 11  is a view for explaining nozzle cleaning nozzles provided for cleaning the guard cleaning nozzles of  FIG. 2 ;  
       FIG. 12  is a view for explaining a nozzle cleaning nozzle provided for cleaning a guard cleaning nozzle of  FIG. 2 ;  
       FIG. 13  is a view showing a plurality of examples of timing of cleaning of the guard cleaning nozzles;  
       FIG. 14  is a view for explaining the structure of a cleaning processing unit in a substrate processing apparatus according to a second embodiment;  
       FIG. 15  is a partial enlarged sectional view of the cleaning processing unit shown in  FIG. 14 ;  
       FIG. 16  is a view for explaining the structure of a cleaning processing unit in a substrate processing apparatus according to a third embodiment;  
       FIG. 17  is a partial enlarged sectional view of the cleaning processing unit shown in  FIG. 14 ;  
       FIG. 18  is a view for explaining the structure and operation of a conventional substrate processing apparatus;  
       FIG. 19  is a view for explaining the structure and operation of a conventional substrate processing apparatus;  
       FIG. 20  is a view for explaining the structure and operation of a conventional substrate processing apparatus;  
       FIG. 21  is a view for explaining the structure and operation of a conventional substrate processing apparatus; and  
       FIG. 22  is a view for explaining a problem in a conventional cleaning processing unit. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS  
      In the following, a substrate processing method and a substrate processing apparatus according to one embodiment of the present invention will be explained with reference to drawings.  
      In the following description, examples of a substrate include a semiconductor wafer, glass substrate for a liquid crystal display, glass substrate for a PDP (plasma display panel), glass substrate for a photomask, substrate for an optical disc, and the like.  
      Examples of a chemical solution include BHF (buffered hydrofluoric acid), DHF (diluted hydrofluoric acid), hydrofluoric acid, hydrochloric acid, sulfuric acid, nitric acid, phosphoric acid, acetic acid, oxalic acid, or an aqueous solution of ammonia or the like, as well as mixture solutions thereof.  
      Examples of a rinse liquid include pure water, carbonated water, ozone water, magnetic water, reduced water (hydrogen water) and ion water, as well as organic solvents such as IPA (isopropyl alcohol).  
     1. First Embodiment  
      (1) Structure of Substrate Processing Apparatus  
       FIG. 1  is a plan view of a substrate processing apparatus according to a first embodiment. As shown in  FIG. 1 , the substrate processing apparatus  100  has processing regions A, B, and a transporting region C between the regions A, B.  
      The processing region A includes a controller  4 , fluid boxes  2   a ,  2   b , and cleaning processing units  5   a ,  5   b.    
      The fluid boxes  2   a ,  2   b  shown in  FIG. 1  respectively house fluid related equipment such as pipes, joints, valves, flow meters, regulators, pumps, temperature controllers and process solution storage tanks involved in supply of the chemical solution or drain (discharge) of the rinse liquid to/from the cleaning processing units  5   a ,  5   b.    
      Each of the cleaning processing units  5   a ,  5   b  performs a cleaning process using a chemical solution (hereinafter, referred to as chemical solution process) and a cleaning process using a rinse liquid (hereinafter, referred to as a rinsing process). In the present embodiment, the chemical solution used in the cleaning processing units  5   a - 5   b  is, for example, BHF which is a mixture solution of ammonium fluoride and hydrogen fluoride, and the rinse liquid is pure water.  
      In the processing region B, fluid boxes  2   c ,  2   d  and cleaning processing units  5   c ,  5   d  are provided. Each of the fluid boxes  2   c ,  2   d  and the cleaning processing units  5   c ,  5   d  has a similar structure to that of the fluid boxes  2   a ,  2   b  and the cleaning processing units  5   a ,  5   b  as described above, and the cleaning processing units  5   c ,  5   d  perform the same process as the cleaning processing units  5   a ,  5   b.    
      Hereinafter, the cleaning processing units  5   a ,  5   b ,  5   c ,  5   d  will be collectively referred to as processing units. The transporting region C includes a substrate transporting robot CR.  
      On one end of the processing region A, B, an indexer ID for carrying in and out a substrate is provided. Inside the indexer ID an indexer robot IR is provided. On the indexer ID, carriers  1  for accommodating substrates W are placed.  
      The indexer robot IR of the indexer ID moves in the direction of an arrow U to take out a substrate W from a carrier  1 , and transfers the substrate W to the substrate transporting robot CR. Conversely, the indexer robot IR receives a substrate W subjected to a series of processes from the substrate transporting robot CR, and returns it to a carrier  1 .  
      The substrate transporting robot CR transports the substrate W transferred from the indexer robot IR to a specified processing unit, or transports the substrate W received from the processing unit to another processing unit or to the indexer robot IR.  
      In the present embodiment, after a chemical solution process or a rinsing process is performed on the substrate W in any one of the cleaning processing units  5   a - 5   d , the substrate W is carried out from the cleaning processing unit  5   a - 5   d  by the substrate transporting robot CR and carried into a carrier  1  via the indexer robot IR.  
      The controller  4  is composed of a computer having a CPU (central processing unit) and or like, and controls operations of the respective processing units in the processing regions A, B, operations of the substrate transporting robot CR in the transporting region C, and operations of the indexer robot IR of the indexer ID.  
      (2) Structure of cleaning Processing Unit  
       FIG. 2  is a view for explaining the structure of a cleaning processing unit  5   a - 5   d  in the substrate processing apparatus  100  according to the first embodiment.  
      The cleaning processing unit  5   a - 5   d  in  FIG. 2  performs a rinsing process after removing impurities such as organic substances that adhere to the surface of the substrate W by a chemical solution process.  
      As shown in  FIG. 2 , the cleaning processing unit  5   a - 5   d  includes a spin chuck  21  for allowing rotation of the substrate W about a vertical rotation axis passing through the center of the substrate W while keeping the substrate W horizontal. The spin chuck  21  is secured to the upper end of a rotary shaft  25  rotated by a chuck rotation-driving mechanism  36 .  
      The substrate W is rotated while being held horizontally by the spin chuck  21  during a chemical solution process and a rinsing process. As shown in  FIG. 2 , in the present embodiment, the spin chuck  21  is composed of a suction spin chuck, however, a spin chuck which holds the periphery of the substrate W may be employed.  
      A motor  60  is provided external to the spin chuck  21 . The motor  60  is connected with a rotation shaft  61 . The rotation shaft  61  is coupled to an arm  62  extending in the horizontal direction, of which end is provided with a chemical solution nozzle  50 .  
      The motor  60  allows the rotation shaft  61  to rotate and the arm  62  to swing, and thus the chemical solution nozzle  50  moves above the substrate W held by the spin chuck  21 .  
      A supply pipe  63  for chemical solution process is provided so as to pass through the inside of the motor  60 , the rotation shaft  61  and the arm  62 . The supply pipe  63  for chemical solution process is connected with the fluid box  2   a - 2   d.    
      The chemical solution nozzle  50  of the cleaning processing unit  5   a - 5   d  is supplied with a chemical solution (BHF) from the fluid box  2   a - 2   d  via the supply pipe  63  for chemical solution process. Thus, the chemical solution can be supplied to the surface of the substrate W.  
      The chemical solution is supplied to the surface of the substrate W when the chemical solution nozzle  50  is situated above the substrate W, whereas the chemical solution is not supplied to the surface of the substrate W when the chemical solution nozzle  50  is retracted to a predetermined position.  
      Also, a motor  71  is provided external to the spin chuck  21 . The motor  71  is connected with a rotation shaft  72 . The rotation shaft  72  is coupled with an arm extending in the horizontal direction, of which end is provided with a rinsing nozzle  50 .  
      The motor  71  allows the rotation shaft  72  to rotate and the arm  73  to swing, and thus the rinsing nozzle  50  moves above the substrate W held by the spin chuck  21 .  
      A supply pipe  74  for rinsing process is provided so as to pass through the inside of the motor  71 , the rotation shaft  72  and the arm  73 . The supply pipe  74  for rinsing process is connected with fluid box  2   a - 2   d.    
      The rinsing nozzle  50  of the cleaning processing unit  5   a - 5   d  is supplied with a rinse liquid (pure water) from the fluid box  2   a - 2   d  via the supply pipe  74  for rinsing process. Thus, the rinse liquid can be supplied to the surface of the substrate W.  
      The rinse liquid is supplied to the surface of the substrate W when the rinsing nozzle  50  is situated above the substrate W, whereas the rinse liquid is not supplied to the surface of the substrate W when the rinsing nozzle  50  is retracted to a predetermined position.  
      The spin chuck  21  is housed in the processing cup  23 . Inside the processing cup  23  is provided a cylindorical partition wall  33 . Also a drain space  31  for collecting and draining the rinse liquid used in the rinsing process of the substrate W is formed to surround the circumference of the spin chuck  21 . The drain space  31  is formed into a circular and groove form so as to follow the outer circumference of the spin chuck  21 .  
      Furthermore, a liquid circulation space  32  for recovering a chemical solution used in the chemical solution process of the substrate W and allowing it to circulate in the substrate processing apparatus  100  is provided between the processing cup  23  and the partition wall  33  so as to surround the drain space  31 . The liquid circulation space  32  is formed into a circular and groove form so as to follow the outer circumference of the drain space  31 .  
      The drain space  31  is connected with a drain pipe  34  for leading the rinse liquid to a drain system pipe  130  in  FIG. 8  as will be described later, and the liquid circulation space  32  is connected with a recovery pipe  35  for leading a chemical solution to a circulation system pipe  120 A in  FIG. 8  as will be described later.  
      Above the processing cup  23 , a splash guard  24  is provided for preventing the chemical solution or the rinse liquid from the substrate W from scattering outwardly. This splash guard  24  has a rotation symmetric shape with respect to the rotary shaft  25 . In the inner face of the upper end of the splash guard  24 , a drain guiding groove  41  having a generally V-shaped cross section is annularly formed.  
      In the inner face of the lower end of the splash guard  24 , a recovery liquid guiding part  42  formed of a slant face which is inclined outwardly and downwardly is provided. Near the upper end of the recovery liquid guiding part  42 , a partition wall-housing groove  43  for receiving the partition wall  33  of the processing cup  23  is formed.  
      The splash guard  24  is supported by a guard lifting mechanism  37  composed of a ball screw mechanism or the like. The guard lifting mechanism  37  moves up and down the splash guard  24  among a carrying in and out position P 1  in which the upper end of the splash guard  24  is at approximately the same level or lower than the upper end of the spin chuck  21 , a circulation position P 2  in which the recovery liquid guiding part  42  is opposite to the outer circumference of the substrate W held by the spin chuck  21 , and a drain position P 3  in which the drain guiding groove  41  is opposite to the outer circumference of the substrate W held by the spin chuck  21 .  
      When the substrate W is carried on the spin chuck  21  and when the substrate W is carried out from the spin chuck  21 , the splash guard  24  descends to the carrying in and out position P 1 .  
      When the splash guard  24  is in the circulation position P 2 , the chemical solution scattering outwardly from the substrate W is led to the liquid circulation space  32  by the recovery liquid guiding part  42  and fed to the circulation system pipe  120 A via the recovery pipe  35 .  
      On the other hand, when the splash guard  24  is in the drain position P 3 , the rinse liquid scattering outwardly from the substrate W is led to the drain space  31  by the drain guiding groove  41  and drained out through the drain pipe  34 .  
      On the upper end of the processing cup  23 , guard cleaning nozzles  81  having a circular shape are provided along the outer circumference of the processing cup  23 . The guard cleaning nozzles  81  are supplied with a first cleaning liquid from the fluid box  2   a - 2   d  via guard cleaning supply pipes  82 . The guard cleaning nozzles  81  inject (discharges) the first cleaning liquid to an outer wall face  24 W of the splash guard  24 . Thus, the outer wall face  24 W of the splash guard  24  is cleaned.  
      The first cleaning liquid injected to the outer wall face  24 W of the splash guard  24  flows down along the outer wall face  24 W and then led to the liquid circulation space  32  directly or along an inner wall face  23 I of the processing cup  23 . Thus, the members (such as inner wall face of the processing cup  23 ) are also cleaned which are located in the path through which the first cleaning liquid flows. The details will be described later.  
      In the present embodiment, as the first cleaning liquid to be injected to the splash guard  24 , for example, the chemical solution (BHF) which is used for the chemical solution process is used.  
      Further, the first cleaning liquid may be mixed with a gas such as air or an inert gas. In the present embodiment, as the first cleaning liquid to be injected to the splash guard  24 , the chemical solution used in the chemical solution process is used, and the first cleaning liquid is mixed with N 2  which is an inert gas. The details will be described later.  
      (3) Structure of Guard Cleaning Nozzle and Attachment to Processing Cup  
      The details of the structure of a guard cleaning nozzle  81  and the details of the cleaning operation of the splash guard  24  by the guard cleaning nozzle  81  will be explained.  
       FIG. 3  is a view for explaining a structure of a guard cleaning nozzle  81  of  FIG. 2 , and  FIG. 4  is a view for explaining attachment of the guard cleaning nozzles  81  of  FIG. 2  to the processing cup  23 .  
       FIG. 3 ( a ) is a top view of the guard cleaning nozzle  81 . The guard cleaning nozzle  81  used in the present embodiment is made from a tube of, for example, a fluorine resin such as PTFE (polytetrafluoroethylene) or PFA (tetrafluoroethylene perfluoroalkoxy vinyl ether copolymer).  
      Further, the guard cleaning nozzle  81  has a guard opposite part  81   a  extending in a semicircular shape, and a supply pipe connecting part  81   b  which extends outwardly from an approximate the center of the guard opposite part  81   a  and is connected to the guard cleaning supply pipe  82  shown in  FIG. 2 .  
      As shown in  FIG. 4 , on the upper end of the processing cup  23 , two guard cleaning nozzles  81  are provided so as to be opposite to each other.  
      More specifically, a plurality of nozzle holders  81 H are attached to the upper end of the processing cup  23  by means of, for example, screws. Then the two guard cleaning nozzles  81  are attached to the nozzle holders  81 H.  
      The nozzle holders  81 H have a block-C shaped cross section, and attachment of the guard cleaning nozzles  81  to the nozzle holders  81 H is achieved by fitting the guard opposite parts  81   a  of the guard cleaning nozzles  81  into the nozzle holders  81 H.  
       FIG. 3 ( b ) is an enlarged view of the inner peripheral side of the guard opposite part  81   a  shown in  FIG. 3 ( a ). As can be seen in the figure, a plurality of cleaning liquid injection openings  811  are provided at predetermined intervals on the inner circumferential side of the guard opposite part  81   a.    
      An outer diameter LL of the semicircle formed in the guard opposite part  81   a  is selected depending on the size of the processing cup  23 . In the present embodiment, the outer diameter LL of the guard opposite part  81   a  is set, for example, at about 460 mm.  
      A tube outer diameter DC of the guard opposite part  81   a  is, for example, 8 mm. In this case, a hole diameter LH of the plurality of cleaning liquid injection openings  811  formed in the guard opposite part  81   a  is preferably set within the range of 0.5 mm to 1.5 mm, and more preferably set at the 1.0 mm.  
      An interval CL between adjacent cleaning liquid injection openings  811  is preferably set within the range from 2.5 mm to 10.0 mm, and more preferably it is set at 5.0 mm.  
       FIG. 5  is an enlarged sectional view showing the state in which the guard cleaning nozzle  81  is attached to the upper end of the processing cup  23 .  
      As shown in  FIG. 5 , a nozzle holder  81 H having a block C-shaped cross section is attached to the upper end of the processing cup  23  by a screw N, and the guard cleaning nozzle  81  is fitted into the nozzle holder  81 H.  
      The nozzle holder  81 H is provided such that a part thereof protrudes from the inner wall face  23 I of the processing cup  23  toward the outer wall face  24 W of the splash guard  24 . A clearance CD is formed between the nozzle holder  81 H and the outer wall face  24 W of the splash guard  24 . The clearance CD is set, for example, at about 2 mm.  
      In this state, the cleaning liquid injection openings  811  of the guard cleaning nozzle  81  is opposite to the outer wall face  24 W of the splash guard  24 . The first cleaning liquid is supplied through the aforementioned guard cleaning supply pipe  82  ( FIG. 2 ) injected from the cleaning liquid injection openings  811  of the guard cleaning nozzle  81 .  
      The first cleaning liquid injected through the cleaning liquid injection openings  811  comes into collision with the outer wall face  24 W of the splash guard  24  to remove the precipitates (hereinafter, referred to as “deposit”) of the chemical solution adhering to the outer wall face  24 W of the splash guard  24 .  
      The first cleaning liquid having come into collision with the outer wall face  24 W flows down along both or either one of the inner wall face  23 I of the processing cup  23  and the outer wall face  24 W of the splash guard  24 , and then is led to the liquid circulation space  32  in  FIG. 2 .  
      When the first cleaning liquid having come into collision with the outer wall face  24 W flows down along the inner wall face  23 I of the processing cup  23 , the deposit on the inner wall face  23 I is washed out downwardly by the first cleaning liquid.  
      When the first cleaning liquid having come into collision with the outer wall face  24 W flows along the outer wall face  24 W of the splash guard  24 , the deposit on the outer wall face  24 W is washed out downwardly by the first cleaning liquid.  
      As described above, in the present embodiment, a liquid having the same ingredients as the chemical solution used in the chemical solution process is employed as the first cleaning liquid. Thus, the first cleaning liquid led to the liquid circulation space  32  can be fed to the circulation system pipe  120 A via the recovery pipe  35  as is the case with the recovery of the chemical solution.  
      Now, explanation will be made of timing of cleaning of the outer wall face  24 W of the splash guard  24  by the guard cleaning nozzles  81 .  
      (4) Timing of Cleaning of Splash Guard  
      The cleaning of the splash guard  24  by the guard cleaning nozzle  81  is performed, for example, in the following timing.  FIG. 6  is a view showing a plurality of examples of timing of cleaning of the splash guard  24 .  
      In  FIG. 6 , a plurality of timings a-d of cleaning are shown chronologically together with the timing of the chemical solution process. In  FIG. 6 , the symbol T 0  denotes an operation starting time of the substrate processing apparatus  100 , and the symbol T 1  denotes a start (ON) time of a chemical solution process, and the symbol T 2  denotes an end (OFF) time of the chemical solution process.  
      The timings a-d of cleaning are set, for example, in the controller  4  of  FIG. 1 . Thus, the controller  4  controls the constituent elements of each of the cleaning processing units  5   a - 5   d  based on the set timing of cleaning to perform a cleaning process of the splash guard  24 .  
      According to the timing a of cleaning in  FIG. 6 , cleaning of the splash guard  24  is always performed during operation of the substrate processing apparatus  100 . In this case, cleaning of the splash guard  24  is started (ON) concurrently with starting of operation of the substrate processing apparatus  100 . The cleaning of the splash guard  24  (ON state) is kept without being influenced by start (ON) and end (OFF) of the chemical solution process.  
      When the timing a of cleaning is set in the manner as described above, it is possible to sufficiently prevent a chemical solution from adhering to the outer wall face  24 W of the splash guard  24  or to the inner wall face  23 I of the processing cup  23  to generate precipitates of the chemical solution. Thus, generation of particles from deposit of the chemical solution is prevented.  
      According to this timing a of cleaning, since supply of the first cleaning liquid from the guard cleaning nozzle  81  is kept without being influenced by start/end of the chemical solution process, a problem of consumption of the first cleaning liquid may arise. However, since the chemical solution and the first cleaning liquid have the same ingredients, the first cleaning liquid can be recovered and reused by providing a mechanism for recovering and reusing the chemical solution and the first cleaning liquid (a path consisting of a recovery pipe  35 , circulation system pipes  120 A,  120 B, a recovery tank RTA, a pump  120 P, a chemical solution storage tank TA and the like as shown in later-described  FIG. 10  (hereinafter, referred to as a recovery path)). Therefore, wasteful consumption of the first cleaning liquid can be prevented.  
      According to the timing b of cleaning in  FIG. 6 , in the cleaning processing unit  5   a - 5   d , cleaning of the splash guard  24  is performed at least during the period in which the chemical solution process is performed (ON period). In this case, cleaning of the splash guard  24  is started (ON) before a predetermined time DT 1  from time T 1  at which the chemical solution process starts (ON), for example. Cleaning of the splash guard  24  (ON state) is kept until a lapse of a predetermined time DT 2  from time T 2  at which the chemical solution process ends (OFF). When the predetermined time DT 2  has lapsed from time T 2 , cleaning of the splash guard  24  ends (OFF).  
      When the timing b of cleaning is set in the manner as described above, it is possible to sufficiently prevent the chemical solution from adhering to the outer wall face  24 W of the splash guard  24  or to the inner wall face  23 I of the processing cup  23  to generate precipitates of the chemical solution. As a result, generation of particles from deposits of the chemical solution is prevented. The predetermined time DT 1  is preferably set at 1 sec., for example, and the predetermined time DT 2  is preferably set at 5 sec., for example.  
      According to the timing b of cleaning, supply of the first cleaning liquid from the guard cleaning nozzle  81  is kept at least during the period in which the chemical solution process is performed, however, similarly to the timing a of cleaning as described above, the first cleaning liquid may be recovered and reused by providing a recovery path as described above. Therefore, wasteful consumption of the first cleaning liquid can be avoided.  
      According to the timing c of cleaning in  FIG. 6 , in the cleaning processing unit  5   a - 5   d , the splash guard  24  is cleaned during a predetermined period from the end (OFF) of the chemical solution process. In this case, for example, cleaning of the splash guard  24  is started (ON) at time T 2  when the chemical solution process ends (OFF). Cleaning of the splash guard  24  (ON state) is kept until a predetermined time DT 3  has lapsed from the time T 2  when the chemical solution process ends (OFF).  
      When the timing c of cleaning is set in the manner as described above, wasteful consumption of the first cleaning liquid is prevented. Further, it is possible to prevent the chemical solution from adhering to the outer wall face  24 W of the splash guard  24  or to the inner wall face  23 I of the processing cup  23  to generate precipitates of the chemical solution. The predetermined time DT 3  is preferably set, for example, within the range of 1-5 sec.  
      In the timing c of cleaning, by providing a recovery path similarly to the cases of the above timings a, b of cleaning, wasteful consumption of the first cleaning liquid can be further prevented. When such a recovery path is provided, since the amount of the first cleaning liquid is small compared to the cases of the timings a, b of cleaning, it is possible to prevent the first cleaning liquid from being oxidized by the atmosphere and deteriorated, compared to the cases of timings a, b of cleaning.  
      According to the timing d of cleaning in  FIG. 6 , the splash guard  24  is intermittently cleaned in the cleaning processing unit  5   a - 5   d  regardless of the timing of the chemical solution process. In the example of  FIG. 6 , cleaning of the splash guard  24  starts (ON) at intervals of the time DT 4 , and cleaning of the splash guard  24  ends (OFF) when the predetermined time DT 5  has lapsed.  
      When the timing d of cleaning is set in the manner as described above, wasteful consumption of the first cleaning liquid is prevented. Further, it is possible to prevent the chemical solution from adhering to the outer wall face  24 W of the splash guard  24  or to the inner wall face  23 I of the processing cup  23  to generate precipitates of the chemical solution. As a result, generation of particles from deposits of the chemical solution is prevented. The predetermined time DT 4  is preferably set, for example, at 5 min., and the predetermined time DT 5  is preferably set, for example, within the range of 1-5 sec.  
      Also in the timing d of cleaning, by providing a recovery path similarly to the cases of the above timings a, b of cleaning, wasteful consumption of the first cleaning liquid can be further prevented. When such a recovery path is provided, it is possible to prevent the first cleaning liquid from being oxidized by the atmosphere and deteriorated, compared to the cases of timings a, b of cleaning.  
      Besides the above, the cleaning processing unit  5   a - 5   d  shown in  FIG. 2  may be provided with a deposit detector that detects deposits on the splash guard  24 , and the timing of cleaning may be set based on the detection by the deposit detector.  
       FIG. 7  is a view for explaining the timing of cleaning when a deposit detector is used.  
       FIG. 7 ( a ) shows a diagram of the cleaning processing unit  5   a - 5   d  to which a deposit detector SN is attached. Here, the deposit detector SN is a detector that detects change in surface condition of the outer wall face  24 W of the splash guard  24 , and, for instance, the deposit detector SN detects presence/absence of deposits Q based on change in color of the outer wall face  24 W or change in reflectivity of the outer wall face  24 W.  
      The deposit detector SN provides the controller  4  with a detection signal of logical “ 1 ” indicative of presence of deposits Q on the outer wall face  24 W when it detects change in surface condition of the outer wall face  24 W exceeding a predetermined threshold. Also, the deposit detector SN provides the controller  4  with a detection signal of logical “0” indicative of absence of deposits Q on the outer wall face  24 W when it detects change in surface condition of the outer wall face  24 W not exceeding the predetermined threshold.  
       FIG. 7 ( b ) shows in a time series a plurality of timings e, f of cleaning based on detection signals together with the detection signals. In  FIG. 7 ( b ), the symbols T 0  denotes an operation starting time of the substrate processing apparatus  100 , the symbols TS 1  denotes time when the deposit detector SN detects presence of deposits Q (logical “1”), the symbols TS 2  denotes time when the deposit detector SN no longer detects presence of deposits Q (logical “0”).  
      According to the timing e of cleaning in  FIG. 7 , in the cleaning processing unit  5   a - 5   d , the splash guard  24  is cleaned at least during the period in which deposits Q on the outer wall face  24 W are detected. In this case, cleaning of the splash guard  24  is started (ON) when the deposit detector SN provides the controller  4  with the detection signal of logical “1”, for example. Cleaning of the splash guard  24  (ON state) is continued until the detection signal of logical “0” from the deposit detector SN is provided to the controller  4 . Therefore, cleaning of the splash guard  24  is stopped (OFF) when the deposit detector SN provides the controller  4  with the detection signal of logical “0”.  
      When such a timing e of cleaning is set in this manner, wasteful consumption of the first cleaning liquid is prevented. Further, it is possible to prevent the chemical solution from adhering to the outer wall face  24 W of the splash guard  24  or to the inner wall face  23 I of the processing cup  23  to generate precipitates of the chemical solution. As a result, generation of particles from deposits of the chemical solution is prevented.  
      According to the timing f of cleaning in  FIG. 7 , in the cleaning processing unit  5   a - 5   d , cleaning of the splash guard  24  is performed for a predetermined period DT 6  from the time when deposits Q are detected on the outer wall face  24 W or on the inner wall face  23 I of the processing cup  23 . In this case, for example, cleaning of the splash guard  24  is started (ON) when the deposit detector SN provides the controller  4  with the detection signal of logical “1”. Cleaning of the splash guard  24  (ON state) is stopped (OFF) after the predetermined period DT 6  has lapsed.  
      When such a timing f of cleaning is set in this manner, wasteful consumption of the first cleaning liquid is prevented. Further, it is possible to prevent the chemical solution from adhering to the outer wall face  24 W of the splash guard  24  or to the inner wall face  23 I of the processing cup  23  to generate precipitates of the chemical solution. As a result, generation of particles from deposits of the chemical solution is prevented. The predetermined time DT 6  is preferably set within the range of 10 to 60 sec.  
      (5) Details of Cleaning of Splash Guard  
      Here, an explanation of the cleaning process of the splash guard  24  will be made when the splash guard  24  is elevated by the guard lifting mechanism  37  in the state that the timing a of cleaning described above is set, and cleaning of the splash guard  24  is continuously performed during the operation of the substrate processing apparatus  100 .  
       FIG. 8  is a view showing a cleaning process of the splash guard  24 .  
      In the cleaning processing unit  5   a - 5   d  of  FIG. 2  in this example, a substrate W is first carried on the spin chuck  21 . Then the substrate W held by the spin chuck  21  is provided with the chemical solution, and the chemical solution process is performed. Then the rinse liquid is supplied to the substrate W and the rinsing process is performed. The substrate W subjected to the rinsing process is rotated by the spin chuck  21  and dried by shaking off (hereinafter, referred to as drying process). Then the substrate W is carried out from the spin chuck  21 . The splash guard  24  is always supplied with the first cleaning liquid from the starting of operation of the substrate processing apparatus  100 .  
      The splash guard  24  is moved up or down by the guard lifting mechanism  37  in accordance with such predetermined process steps.  
      FIGS.  8 ( a )-( c ) show in a time series positional relationships between the processing cup  23  and the splash guard  24  before starting of the chemical solution process after carrying of the substrate W onto the spin chuck  21 .  
      As shown in  FIG. 8 ( a ), in performing the chemical solution process, first, the splash guard  24  starts elevating from the carrying in and out position P 1 . Thus, the vicinity of the upper end of the outer wall face  24 W of the splash guard  24  is cleaned with the first cleaning liquid.  
      The first cleaning liquid injected from the guard cleaning nozzle  81  will flow down along the inner wall face  23 I of the processing cup  23  after coming into collision with the outer wall face  24 W of the splash guard  24  and reflecting toward the inner wall face  23 I of the processing cup  23 . Thus, the inner wall face  23 I of the processing cup  23  is also cleaned with the first cleaning liquid.  
      As shown in  FIG. 8 ( b ), as the splash guard  24  elevates, almost the center of the outer wall face  24 W is cleaned with the first cleaning liquid injected from the guard cleaning nozzle  81 .  
      Thus, when the splash guard  24  elevates to the circulation position P 2 , the first cleaning liquid is injected to the entire region of the outer wall face  24 W in the vertical direction as shown in  FIG. 8 ( c ), and thus the entire region of the outer wall face  24 W is cleaned.  
      Further, by continuously supplying the first cleaning liquid from the guard cleaning nozzle  81 , the chemical solution remaining in the vicinity of the lower end of the inner wall face  23 I of the processing cup  23  (liquid circulation space  32 ) is washed out to the recovery pipe  35  by the first cleaning liquid.  
      (6) Injecting of First Cleaning Liquid by Guard Cleaning Nozzle  
      As described above, a gas such as air or an inert gas is mixed into the first cleaning liquid to be injected to the outer wall face  24 W of the splash guard  24  from the guard cleaning nozzle  81 .  
       FIG. 9  is a view for explaining the effects of mixing a gas into the first cleaning liquid to be injected from the guard cleaning nozzle  81 .  
      As shown in  FIG. 9 ( a ), a gas/liquid mixer  84  having at least either one of an in-line mixer or a mixing valve is connected to the guard cleaning supply pipe  82  connected to the guard cleaning nozzle  81 . This gas/liquid mixer  84  is supplied with the chemical solution (BHF) used in the chemical solution process as the first cleaning liquid and with N 2  (nitrogen) gas as an inert gas. This makes it possible to supply the guard cleaning nozzle  81  with a mixture fluid of the first cleaning liquid and the inert gas which is generated in the gas/liquid mixer  84 .  
      Here, the mixing condition of the first cleaning liquid and the inert gas is adjusted such that microbubbles of the inert gas are dispersed in the first cleaning liquid. In this case, the bubbles compressed by the inner pressure of the guard cleaning nozzle  81  will be expanded by being injected through the first cleaning liquid injection openings  811 . Accordingly, as shown in  FIG. 9 ( a ), the first cleaning liquid is injected at a large spread angle from the plurality of cleaning liquid injection openings  811 . Thus, it is possible to inject the first cleaning liquid circumferentially of the outer wall face  24 W of the splash guard  24  without leaving any spaces. Thus, it is possible to clean the entire face of the outer wall face  24 W by elevation of the splash guard  24 .  
      In contrast, as shown in  FIG. 9 ( b ), when only the first cleaning liquid is supplied to the guard cleaning nozzle  81 , the first cleaning liquid supplied to the guard cleaning nozzle  81  is injected linearly toward the outer wall face  24 W from the cleaning liquid injection openings  811 .  
      In this case, although the portions of the outer wall face  24 W of the splash guard  24  opposite to the cleaning liquid injection openings  811  of guard cleaning nozzle  81  can be cleaned, the other regions RE are difficult to be cleaned. Therefore, even when the splash guard  24  elevates, deposits Q on the splash guard  24  are likely to remain in the regions extending vertically in stripes. In this case, by increasing the flow amount of the first cleaning liquid to be injected from the cleaning liquid injection openings  811  of the guard cleaning nozzle  81 , it is possible to clean the entire face of the splash guard  24 .  
      As the gas/liquid mixer  84 , an in-line mixer or a mixing valve are exemplified, however, any joining members that can join the chemical solution and the inert gas, for example, T-shaped joint with which a supply pipe of chemical solution, a supply pipe of inert gas, and the guard cleaning supply pipe  82  is connected can be used.  
      (7) Reuse and Drain of Various Chemical Solutions  
       FIG. 10  is a system diagram of piping of the substrate processing apparatus  100  in  FIG. 1 .  
      As shown in  FIG. 10 , to the rinse nozzle  50  of the cleaning processing unit  5   a - 5   d , the supply pipe  74  for rinsing process extending to the fluid box  2   a - 2   d  is connected.  
      A valve  75  is inserted in the supply pipe  74  for rinsing process. In the fluid box  2   a - 2   d , pure water is supplied as the rinse liquid to the supply pipe  74  for rinsing process. Thus, the rinse liquid can be supplied to the substrate W by operating the valve  75 .  
      To the chemical solution nozzle  50  of the cleaning processing unit  5   a - 5   d , the supply pipe  63  for chemical solution process extending to the chemical solution storage tank TA in the fluid box  2   a - 2   d  is connected.  
      The valve  64  is inserted in the supply pipe  63  for chemical solution process, and in the fluid box  2   a - 2   d , a filter F, a pump  74 P and a temperature controller  210  are inserted in the supply pipe  63  for chemical solution process in this order from the valve  64 . In the chemical solution storage tank TA, BHF is stored as the chemical solution.  
      When the pump  74 P inserted in the supply pipe  63  for chemical solution process is operated, the chemical solution in the chemical solution storage tank TA is fed to the temperature controller  210  where it is controlled to have a predetermined temperature. Then the chemical solution of which temperature has been adjusted is fed to the valve  64  via the pump  74 P and the filter F. Accordingly, the chemical solution can be supplied to the substrate W by operating the valve  64 .  
      In the fluid bo  2   a - 2   d , one end of the pipe  76  is connected to a portion between the valve  64  and the pump  74 P of the supply pipe  63  for chemical solution process. The other end of the pipe  76  extends to the chemical solution storage tank TA. A valve  77  is inserted in the pipe  76 .  
      Further, in the fluid box  2   a - 2   d , one end of pipe  85  is connected to a portion between the valve  64  and the pump  74 P of the supply pipe  63  for chemical solution process the gas/liquid mixer  84  is connected to the other end of the pipe  85 . A valve  86  is inserted in the pipe  85 .  
      When the valve  77  is opened while the valve  64  and the valve  86  are closed, the chemical solution pumped from the chemical solution storage tank TA will be stored again in the chemical solution storage tank TA without being fed to the cleaning processing unit  5   a - 5   d . In this manner, since the chemical solution circulates the chemical solution storage tank TA, the supply pipe  63  for chemical solution process, the pump  74 P, the filter F, the temperature controller  210  and the pipe  76 , the chemical solution in the chemical solution storage tank TA is kept at a predetermined temperature by the temperature controller  210  and kept clean by the filter F.  
      As described above, to two guard cleaning nozzles  81  of the cleaning processing unit  5   a - 5   d , the guard cleaning supply pipe  82  is connected. The guard cleaning supply pipe  82  extends to the fluid box  2   a - 2   d.    
      In this example, the guard cleaning supply pipe  82  is a branched pipe made up of one main pipe and two branched pipes. To each of two guard cleaning nozzles  81 , a branched pipe of the guard cleaning supply pipe  82  is connected.  
      The main pipe of the guard cleaning supply pipe  82  is connected to the gas/liquid mixer  84  in the fluid box  2   a - 2   d . This gas/liquid mixer  84  is supplied with BHF as the first cleaning liquid by opening the valve  86 . Further, the gas/liquid mixer  84  is supplied with N 2  gas serving as the inert gas.  
      In this way, it is possible to supply the two guard cleaning nozzles  81  with the mixture fluid of the first cleaning liquid of the inert gas. Accordingly, it is possible to inject the first cleaning liquid to the outer wall face  24 W of the splash guard  24  ( FIG. 2 ) at a large spread angle.  
      To the drain space  31  in the processing cup  23 , one end of the drain pipe  34  is connected. The other end of the drain pipe  34  is connected to a drain system pipe  130  which will be described later.  
      To the liquid circulation space  32  in the processing cup  23 , one end of the recovery pipe  35  is connected. The other end of the recovery pipe  35  is connected to a three-way valve  110 . To this three-way valve  110 , the circulation system pipe  120 A and the drain system pipe  130  are connected.  
      The circulation system pipe  120 A is connected with a recovery tank RTA provided in the fluid box  2   a - 2   d , and the chemical solution introduced to the circulation system pipe  120 A is temporarily stored in the recovery tank RTA.  
      To the recovery tank RTA, the circulation system pipe  120 B is connected, and the circulation system pipe  120 B extends from the recovery tank RTA to the chemical solution storage tank TA in the fluid box  2   a - 2   d . In the fluid box  2   a - 2   d , a pump  120 P is inserted in the circulation system pipe  120 B, and two filters F are inserted therein so as sandwich the pump  120 P.  
      The drain system pipe  130  extends from the cleaning processing unit  5   a - 5   d  to the inside of the fluid box  2   a - 2   d  or to the drain device (not shown) provided external to the substrate processing apparatus  100 .  
      The three-way valve  110  is controlled so as to lead the chemical solution and the first cleaning liquid flowing into the recovery pipe  35  to the circulation system pipe  120 A during the chemical solution process of the substrate W and during the cleaning of the outer wall face  24 W of the splash guard  24  and the inner wall face  23 I of the processing cup  23 . In this way, the internal space of the recovery pipe  35  and the internal space of the circulation system pipe  120 A communicate via the three-way valve  110 . In this case, the chemical solution and the first cleaning liquid will not flow to the drain system pipe  130 .  
      The chemical solution and the first cleaning liquid introduced to the circulation system pipe  120 A is temporarily stored in the recovery tank RTA. The chemical solution stored in the recovery tank RTA is fed to the chemical solution storage tank TA by the pump  120 P through the circulation system pipe  120 B and cleaned through the filter F. Thus, the chemical solution used for the chemical solution process and the first cleaning liquid used for the cleaning of the splash guard  24  are stored again in the chemical solution storage tank TA.  
      In the present embodiment, operations of the aforementioned three-way valve  110 , valves  64 ,  75 ,  77 , pumps  74 P,  120 P and temperature controller  210  are controlled by the controller  4  shown in  FIG. 1 .  
      As described above, in the substrate processing apparatus  100  according to the present embodiment, the chemical solution used in the chemical solution process is circulated and reused. Therefore, by reusing the chemical solution which is more expensive than the rinse liquid, production cost of the substrate W is reduced.  
      Further, in the present embodiment, as described above, as the first cleaning liquid for the splash guard  24 , the one having the same ingredients with the chemical solution used in the chemical solution process is used. Thus, the chemical solution used in the chemical solution process can be reused as the first cleaning liquid for the splash guard  24 , or the first cleaning liquid used in the cleaning of the splash guard  24  can be used as the chemical solution for the chemical solution process. Therefore, production cost of the substrate W will not rise even when the chemical solution is used for the cleaning of the splash guard  24 .  
      In the present embodiment, the three-way valve  110  may not be provided, and the circulation system pipe  120 A may be directly connected to the other end of the recovery pipe  35  instead of the three-way valve  110 .  
      (8) Effects  
      In the substrate processing apparatus  100  according to the present embodiment, the process of the substrate W is performed while the chemical solution is supplied to the substrate W held by the spin chuck  21  by the chemical solution nozzle  50 . At this time, the chemical solution supplied to the substrate W scatters around and adheres to the members (the processing cup  23  and the splash guard  24 ) located in the periphery of the substrate W.  
      Such adhesion of the chemical solution to the peripheral members of the substrate W may cause adhesion of precipitates of the chemical solution on the outer wall face  24 W of the splash guard  24  and the inner wall face  23 I of the processing cup  23 .  
      In view of this, the first cleaning liquid having the same ingredients with the chemical solution is supplied from the guard cleaning nozzles  81  to the outer wall face  24 W of the splash guard  24  and the inner wall face  23 I of the processing cup  23  without being in contact with the substrate W. Thus, the outer wall face  24  W of the splash guard  24  and the inner wall face  23 I of the processing cup  23  are cleaned with the clean first cleaning liquid.  
      Further, since the outer wall face  24 W of the splash guard  24  and the inner wall face  23 I of the processing cup  23  are cleaned with the first cleaning liquid having the same ingredients as the chemical solution, it is possible to clean the lower end of the outer wall face  24 W of the splash guard  24  and the inner wall face  23 I of the processing cup  23  during the process of the substrate W, namely when the chemical solution is supplied to the substrate W held by the spin chuck  21 . Therefore, it is possible to efficiently clean the lower end of the outer wall face  24 W of the splash guard  24  and the inner wall face  23 I of the processing cup  23  without deterioration in throughput of the substrate processing.  
      Even when the chemical solution remains in the liquid circulation space  32 , drying and precipitation of the chemical solution can be prevented by supplying the first cleaning liquid having the same ingredients as the chemical solution that remains. Thus, generation of particles due to adhesion of precipitates of the chemical solution in the vicinity of the liquid circulation space  32  of the processing cup  23  can be prevented.  
      In this way, processing defects of the substrate W are sufficiently prevented by preventing generation of particles from the precipitates of the chemical solution.  
      Further, the chemical solution supplied to the substrate W and the first cleaning liquid supplied to the outer wall face  24 W of the splash guard  24  and the inner wall face  23 I of the processing cup are reused. Accordingly, production cost of the substrate W is reduced.  
      (9) Chemical Solution and First Cleaning Liquid Used in Substrate Processing Apparatus  
      In the present embodiment, BHF is used, for example, for etching and cleaning the surface of the substrate W. Other examples of the chemical solution will be listed below.  
      As the chemical solution, a solution containing ammonium fluoride for removing polymer formed on the surface of the substrate W, for example, a mixture solution containing ammonium fluoride and phosphoric acid can be used.  
      When a solution containing a salt generated by mixing of an alkaline solution and an acidic solution, such as BHF used in the present embodiment or the mixture solution containing ammonium fluoride and phosphoric acid is used, precipitates is likely to occur.  
      Therefore, the present substrate processing apparatus offers a significant effect when the mixture solution of an alkaline solution and an acidic solution is used as the chemical solution.  
      An alkaline solution such as TMAH (tetra methyl ammonium hydroxide) or an acidic solution such as butyl acetate may also be used as the chemical solution for performing a development process of the substrate W.  
      Further, sulfuric acid/hydrogen peroxide mixture or ozone water may be used as a chemical solution for a removing resist formed on the surface of the substrate W.  
      Also BHF, DHF (diluted hydrofluoric acid), hydrofluoric acid, hydrochloric acid, sulfuric acid, nitric acid, phosphoric acid, acetic acid, oxalic acid, ammonia, citric acid, hydrogen peroxide water, or an aqueous solution of TMAH or the like, as well as mixtures thereof may be used as the chemical solution for etching or cleaning the surface of substrate W.  
      In the present embodiment, although the chemical solution used in the chemical solution process and the first cleaning liquid used in the cleaning of the splash guard  24  are the same, the first cleaning liquid having at least the same ingredients as the chemical solution used in the chemical solution process can be used, and these two solutions may have different temperatures and concentrations. Preferably, the concentration of the first cleaning liquid is substantially the same as that of the chemical solution used in the chemical solution process.  
      The expression “the same ingredients as the chemical solution” means that the proportions of ingredients other than pure water contained in the chemical solution are the same. When the concentration of the chemical solution differs from that of the first cleaning liquid, they may be reused in the chemical solution process or the cleaning process of the splash guard  24  by adjusting the concentration of either the chemical solution or the first cleaning liquid.  
      Therefore, when the concentrations of the chemical solution and the first cleaning liquid are set to be substantially equal in advance, they can be easily reused in the chemical solution process and in the cleaning process of the splash guard  24  without necessity of adjusting the concentration of the chemical solution or the concentration of the first cleaning liquid separately.  
      (10) Other Exemplary Structures  
      In the substrate processing apparatus  100  according to the present embodiment, the cleaning processing unit  5   a - 5   d  shown in  FIG. 2  may further include the following elements.  
      (10-a) Nozzle Cleaning Nozzle  
       FIGS. 11 and 12  are views for explaining nozzle cleaning nozzles  181  for cleaning the guard cleaning nozzles  81  shown in  FIG. 2 . The nozzle cleaning nozzles  181  are attached to the upper end of the processing cup  23  together with the guard cleaning nozzles  81  in a similar manner as the guard cleaning nozzle  81 .  
       FIG. 11  shows the appearance of the nozzle cleaning nozzles  181  and how the nozzle cleaning nozzles  181  are attached to the processing cup  23 .  FIG. 12  is an enlarged sectional view of the state in which a guard cleaning nozzle  81  and a nozzle cleaning nozzle  181  are attached to the upper end of the processing cup  23 .  
      As shown in  FIG. 11 , in the present example, the nozzle cleaning nozzles  181  having substantially the same shape as the guard cleaning nozzles  81  are attached right above the guard cleaning nozzles  81 .  
      Each nozzle cleaning nozzle  181  is provided with a plurality of cleaning liquid injection openings  181   a  similarly to the case of the guard cleaning nozzle  81 , and the plurality of cleaning liquid injection openings  181   a  are formed in downwardly biased positions on the inner circumferential side of the nozzle cleaning nozzle  181 .  
      Thus, when each nozzle cleaning nozzle  181  is attached to the processing cup  23  together with the guard cleaning nozzle  81  by the nozzle holder  81 H as shown in  FIG. 12 , the plurality of cleaning liquid injection openings  181   a  face the vicinity of the cleaning liquid injection openings  811  of the guard cleaning nozzle  81  located right below the same.  
      The nozzle cleaning nozzles  181  are supplied with a second cleaning liquid (a liquid having ingredients different from that of the chemical solution for the chemical solution process and capable of dissolving the first cleaning liquid) from a second cleaning liquid supplier  184  provided in the fluid box  2   a - 2   d  through the nozzle cleaning supply pipes  182 . In the present example, the second cleaning liquid is, for example, pure water.  
      Each nozzle cleaning nozzle  181  injects (discharges) the supplied second cleaning liquid to the vicinity of the plurality of cleaning liquid injection openings  811  of the guard cleaning nozzle  81 . Thus, the vicinity of the cleaning liquid injection openings  811  of the guard cleaning nozzle  81  is cleaned.  
      Precipitates may be generated generate from the first cleaning liquid adhering to the vicinity of the cleaning liquid injection openings  811  of the guard cleaning nozzle  81  by cleaning of the outer wall face  24 W of the splash guard  24 .  
      In view of this, by cleaning the vicinity of the cleaning liquid injection openings  811  with the second cleaning liquid as described above, deposits Q of the cleaning liquid injection openings  811  are removed. As a result, generation of particles from deposits Q of the first cleaning liquid is prevented, and processing defects of substrate W are prevented.  
      In the present example, as shown in  FIG. 12 , the second cleaning liquid injected from the nozzle cleaning nozzle  181  passes through the vicinity of the cleaning liquid injection openings  811  of the guard cleaning nozzle  81  and comes into collision with the outer wall face  24 W of the splash guard  24 .  
      The second cleaning liquid having come into collision with the outer wall face  24 W of the splash guard  24  flows down downwardly while being supplied to the inner wall face  23 I of the processing cup  23 . Accordingly, the outer wall face  24 W of the splash guard  24  and the inner wall face  23 I of the processing cup  23  are also cleaned with the second cleaning liquid. As a result, deposits Q of the chemical solution and the first cleaning liquid are removed from the outer wall face  24 W of the splash guard  24  and the inner wall face  23 I of the processing cup  23 .  
      (10-b) Timing of Cleaning of Guard Cleaning Nozzle  
      In the present embodiment, cleaning of the guard cleaning nozzles  81  by the nozzle cleaning nozzles  181  is performed, for example in the following timing.  FIG. 13  is a view showing a plurality of examples of timing of cleaning of the guard cleaning nozzles  81 .  
      In  FIG. 13 , two timings A, B of cleaning are shown in a time series together with the timings of the rinsing process and the drying process.  
      In  FIG. 13 , the symbols T 0  denotes an operation starting time of the substrate processing apparatus  100 , the symbols TR 1  denotes a starting (ON) time of the rinsing process, and the symbols TR 2  denotes an ending (OFF) time of the rinsing process. The reference numeral TD 1  denotes a starting (ON) time of the drying process, and the symbols TD 2  denotes an ending (OFF) time of the drying process.  
      The timings A, B of cleaning are set in the controller  4 , as shown in  FIG. 1 , for example. Thus, the controller  4  controls the elements of each of the cleaning processing units  5   a - 5   d  based on the set timing of cleaning to perform the cleaning process of the guard cleaning nozzles  81 .  
      According to the timing A of cleaning shown in  FIG. 13 ( a ), at least during the period in which the rinsing process is performed (ON) in the cleaning processing unit  5   a - 5   d , the guard cleaning nozzles  81  are cleaned. In this case, for example, at the time TR 1  at which the rinsing process starts (ON), cleaning of the guard cleaning nozzles  81  starts (ON). Then at the time TR 2  at which the rinsing process ends (OFF), the cleaning of the guard cleaning nozzle  81  ends (OFF).  
      When the timing A of cleaning is set as described above, it is possible to sufficiently prevent adhesion of the first cleaning liquid to the guard cleaning nozzles  81 , and generation of precipitates of the first cleaning liquid. As a result, generation of particles from the deposits of the first cleaning liquid is prevented.  
      According to the timing B of cleaning shown in  FIG. 13 ( b ), at least during the period in which the drying process is performed (ON) in the cleaning processing unit  5   a - 5   d , the guard cleaning nozzles  81  are cleaned. In this case, for example, at the time TD 1  at which the drying process starts (ON), cleaning of the guard cleaning nozzles  81  starts (ON). Then at the time TD 2  at which the drying process ends (OFF), cleaning of the guard cleaning nozzles  81  ends (OFF).  
      When the timing B of cleaning is set as described above, it is possible to sufficiently prevent adhesion of the first cleaning liquid to the guard cleaning nozzles  81 , and generation of precipitates of the first cleaning liquid. As a result, generation of particles from deposits of the first cleaning liquid is prevented.  
      Besides the above, cleaning of the guard cleaning nozzles  81  by the nozzle cleaning nozzles  181  may be performed, for example, in a period in which none of the chemical solution process, the rinsing process, and the drying process is performed on substrate W. More specifically, it may be performed at the time of carrying in and out of the substrate W to/from the cleaning processing unit  5   a - 5   d , or when a substrate W to be processed next is not carried in yet after the processed substrate W has been carried out.  
      When cleaning of the guard cleaning nozzles  81  with the second cleaning liquid is performed at a timing different from the timing perform of the chemical solution process on the substrate W as described above, it is preferred to drain the second cleaning liquid through the drain system pipe  130  shown in  FIG. 10 .  
      Thus, the second cleaning liquid having different ingredients from those of the chemical solution is no longer reused in the process of substrate W, so that the second cleaning liquid is prevented from being mixed into the chemical solution. As a result, reduction in life of the chemical solution is prevented.  
     2. Second Embodiment  
      A substrate processing apparatus according to the second embodiment differs in structure from the substrate processing apparatus  100  according to the first embodiment in the following points.  
      The substrate processing apparatus according to the present embodiment has a structure for removing precipitates of the chemical solution adhering to the recovery liquid guiding part  42  of the splash guard  24 , or to the inner wall face  23 I of the processing cup  23  in the cleaning processing unit  5   a - 5   d  shown in  FIG. 2 .  
       FIG. 14  is a view for explaining the structure of the cleaning processing unit  5   a - 5   d  in the substrate processing apparatus according to the second embodiment.  
      As shown in  FIG. 14 , in the present embodiment, in place of the guard cleaning nozzles  81  shown in  FIG. 2  provided on the upper end of the processing cup  23  in the first embodiment, member cleaning nozzles  91  are attached to the upper end of the partition wall  33 . The member cleaning nozzles  91  have generally the same shape as the guard cleaning nozzles  81 , however, a plurality of cleaning liquid injection openings are formed in positions different from those for the case of the guard cleaning nozzles  81 .  
      As shown in  FIG. 14 , the member cleaning nozzles  91  are connected to member cleaning supply pipes  92 . The member cleaning nozzles  91  are supplied with the first cleaning liquid from the fluid box  2   a - 2   d  via the member cleaning supply pipes  92 .  
       FIG. 15  is a partial enlarged sectional view of the cleaning processing unit  5   a - 5   d  shown in  FIG. 14 .  
       FIG. 15 ( a ) shows one exemplary structure for cleaning the recovery liquid guiding part  42  of the splash guard  24 .  
      As described above, the member cleaning nozzle  91  is attached to the upper end of the partition wall  33  of the processing cup  23 . In the present example, a plurality of cleaning liquid injection openings  911  are formed so as to face the upper position of the recovery liquid guiding part  42  of the splash guard  24  when the splash guard  24  is positioned in the circulation position P 2 .  
      In this case, the first cleaning liquid is injected toward the upper position of the recovery liquid guiding part  42  from the plurality of cleaning liquid injection openings  911  of the member cleaning nozzle  91 .  
      Thus, deposits Q on the recovery liquid guiding part  42  of the splash guard  24  are washed out by the first cleaning liquid.  
      Further, the first cleaning liquid flowing down from the recovery liquid guiding part  42  flows down along the inner wall face  23 I of the processing cup  23 . Thus, deposits Q on the inner wall face  23 I are also washed out by the first cleaning liquid.  
      As described above, in this example, the member cleaning nozzle  91  provided in the upper end of the partition wall  33  enables the precipitates of the chemical solution adhering to the recovery liquid guiding part  42  of the splash guard  24  and to the inner wall face  23 I of the processing cup  23  to be securely removed when the splash guard  24  is positioned in the circulation position P 2 , namely during the chemical solution process.  
       FIG. 15 ( b ) shows one exemplary structure for cleaning the inner wall face  23 I of the processing cup  23 .  
      As describe above, the member cleaning nozzle  91  is attached to the upper end of the partition wall  33  of the processing cup  23 . In the present example, a plurality of cleaning liquid injection openings  911  are formed so as to face the inner wall face  23 I of the processing cup  23  when the splash guard  24  is positioned in the circulation position P 2 .  
      In this case, the first cleaning liquid is injected toward the inner wall face  23 I of the processing cup  23  from the plurality of cleaning liquid injection openings  911  of the member cleaning nozzle  91 .  
      Thus, deposits Q on the inner wall face  23 I of the processing cup  23  are washed out by the first cleaning liquid.  
      As described above, in this example, the member cleaning nozzle  91  provided in the upper end of the partition wall  33  enables the precipitates of the chemical solution adhering to the inner wall face  23 I of the processing cup  23  to be securely removed when the splash guard  24  is positioned in the circulation position P 2 , namely during a chemical solution process.  
      Preferably, the first cleaning liquid to be injected from the member cleaning nozzle  91  is also mixed with a gas such as air or the inert gas. The cleaning liquid mixed with the gas is injected at large spread angle from the plurality of cleaning liquid injection openings  911 . As a result, much higher cleaning efficiency is realized.  
      Similarly to the first embodiment, also in the present embodiment, nozzle cleaning nozzles for cleaning the member cleaning nozzles  91  may further be provided. In this case, precipitates of the first cleaning liquid adhering to the member cleaning nozzles  91  are removed by the second cleaning liquid supplied from the nozzle cleaning nozzles. Thus, generation of particles from deposits on the member cleaning nozzles  91  is prevented.  
      In the present embodiment, the guard cleaning nozzles  81  described in the first embodiment and shown in  FIG. 2  may further be provided on the upper end of the processing cup  23 .  
      Thus, since the outer wall face  24 W of the splash guard  24 , as well as the recovery liquid guiding part  42  of the splash guard  24  or the inner wall face  23 I of the processing cup  23  is cleaned, generation of particles caused by deposits Q of the chemical solution is prevented more sufficiently. As a result, processing defects of the substrate W are securely prevented.  
     3. Third Embodiment  
      A substrate processing apparatus according to the third embodiment differs in structure from the substrate processing apparatus  100  according to the first embodiment in the following points.  
      The substrate processing apparatus according to the present embodiment has structure for removing precipitates of the chemical solution adhering to the vicinity of the lower end of the inner wall face  23 I of the processing cup  23  in the cleaning processing unit  5   a - 5   d  shown in  FIG. 2 .  
       FIG. 16  is a view for explaining the structure of the cleaning processing unit  5   a - 5   d  in the substrate processing apparatus according to the third embodiment.  
      As shown in  FIG. 16 , in the present embodiment, in place of the guard cleaning nozzles  81  shown in  FIG. 2  provided on the upper end of the processing cup  23  in the first embodiment, member cleaning nozzles  93  are attached to the vicinity of the lower end of the partition wall  33 . The member cleaning nozzles  93  have generally the same shape as the guard cleaning nozzles  81 , however, a plurality of cleaning liquid injection openings are formed in positions different from those for the case of the guard cleaning nozzles  81 .  
      As shown in  FIG. 16 , the member cleaning nozzles  93  are connected to member cleaning supply pipes  94 . The member cleaning nozzles  93  are supplied with the first cleaning liquid from the fluid box  2   a - 2   d  via the member cleaning supply pipes  94 .  
       FIG. 17  is a partial enlarged sectional view of the cleaning processing unit  5   a - 5   d  shown in  FIG. 16 .  
       FIG. 17  shows one exemplary structure for cleaning the vicinity of the lower end of the inner wall face  23 I of the processing cup  23 .  
      As describe above, the member cleaning nozzle  93  is attached to the vicinity of the lower end of the partition wall  33  of the processing cup  23 . In the present example, a plurality of cleaning liquid injection openings  939  are formed so as to face the vicinity of the lower end of the inner wall face  23 I of the processing cup  23 .  
      In this case, the first cleaning liquid is injected toward the vicinity of the lower end of the inner wall face  23 I of the processing cup  23  from the plurality of cleaning liquid injection openings  939  of the member cleaning nozzle  93 .  
      Thus, the deposits Q in the vicinity of the lower end of the inner wall face  23 I of the processing cup  23  are washed out by the first cleaning liquid.  
      As described above, in this example, the member cleaning nozzle  93  provided in the vicinity of the lower end of the partition wall  33  enables the precipitates of the chemical solution adhering to the vicinity of the lower end of the inner wall face  23 I of the processing cup  23  to be securely removed.  
      Preferably, the first cleaning liquid to be injected from the member cleaning nozzle  93  is also mixed with a gas such as air or the inert gas. The cleaning liquid mixed with the gas is injected at a large spread angle from the plurality of cleaning liquid injection openings  939 . As a result, much higher cleaning efficiency is realized.  
      Similarly to the first embodiment, also in the present embodiment, nozzle cleaning nozzles for cleaning the member cleaning nozzles  93  may further be provided. In this case, precipitates of the first cleaning liquid adhering to the member cleaning nozzles  93  are removed by the second cleaning liquid supplied from the nozzle cleaning nozzles. Thus, generation of particles from deposits on the member cleaning nozzles  93  is prevented.  
      In the present embodiment, the guard cleaning nozzles  81  described in the first embodiment and shown in  FIG. 2 , and the member cleaning nozzles  91  described in the second embodiment and shown in  FIG. 14  may further be provided.  
      In this case, since the recovery liquid guiding part  42  of the splash guard  24 , the inner wall face  23 I of the processing cup  23  and the outer wall face  24 W of the splash guard  24 , as well as the vicinity of the lower end of the inner wall face  23 I of the processing cup  23  are cleaned, generation of particles caused by deposits Q of the chemical solution is prevented more sufficiently. As a result, processing defects of substrate W is securely prevented.  
     4. Correspondence Between Elements in Claims and Parts in Embodiment  
      In the first to third embodiments described above, the spin chuck  21  corresponds to a substrate holding device, the chemical solution nozzle  50  corresponds to a chemical solution supplying device, the processing cup  23  and the splash guard  24  correspond to a member, the first cleaning liquid corresponds to a cleaning liquid having the same ingredients as the chemical solution, and the guard cleaning nozzles  81  and the member cleaning nozzles  91 ,  93  correspond to a cleaning liquid supplying device.  
      The recovery pipe  35 , circulation system pipes  120 A,  120 B, recovery tank RTA, pump  120 P and chemical solution storage tank TA correspond to a recovering device, air or an inert gas such as N 2  gas corresponds to a gas, the controller  4  corresponds to a controller, the deposit detector SN corresponds to a detector, the second cleaning liquid corresponds to a dissolving liquid, and the nozzle cleaning nozzles  181  correspond to a dissolving liquid supplying device.  
      The plurality of cleaning liquid injection openings  811 ,  911 ,  939  correspond to discharge openings, the rinse nozzle  70  corresponds to a rinse liquid supplying device, the chuck rotation-driving mechanism  36  corresponds to a rotation driving device, the supply pipe  63  for chemical solution process and the pump  74 P correspond to a circulation system, the processing cup  23  and the splash guard  24  correspond to a guiding member.  
      The splash guard  24  corresponds to an anti-scattering member, the processing cup  23  corresponds to a receiving member, the inner wall face of the splash guard  24  or the inner wall face  23 I of the processing cup  23  corresponds to an inner wall face of the guiding member, the guard opposite parts  81   a  and corresponding parts of the guard opposite parts  81   a  of the member cleaning nozzles  91 ,  93  correspond to a cylindorical member, and BHF corresponds to a solution containing a removing liquid and a salt.  
      While preferred embodiments of the present invention have been described above, it is to be understood that variations and modifications will be apparent to those skilled in the art without departing the scope and spirit of the present invention. The scope of the present invention, therefore, is to be determined solely by the following claims.