Abstract:
A substrate processing method includes the steps of cleaning a substrate in a processing tank, forming an organic solvent vapor atmosphere in a chamber, elevating the substrate to replace a rinse on a surface of the substrate with an organic solvent, draining the rinse from the processing tank, moving the substrate into the processing tank, making the surface of the substrate water-repellent, elevating the substrate and supplying an organic solvent vapor to the substrate to remove water repellent from the surface of the substrate, and drying the substrate with inert gas. The water repellent is removed above the processing tank, and thus the substrate can be dried while contamination of the substrate with particles that can be generated in the processing tank in this step is suppressed.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    1. Field of the Invention 
         [0002]    The present invention relates to a substrate processing method for processing a semiconductor wafer and a glass substrate for liquid crystal display (hereinafter, simply referred to as substrates) with processing liquid. 
         [0003]    2. Description of the Background Art 
         [0004]    A substrate processing apparatus including a processing tank, a substrate elevating mechanism, and a substrate drying mechanism is known. The processing tank is used to dip a substrate into chemical liquid, a rinse, and the like. The substrate elevating mechanism moves the substrate between the processing tank and space above the processing tank. The substrate drying mechanism blows inert gas and the like onto the substrate in the space above the processing tank to dry the rinse, such as pure water. When the rinse is dried in such a substrate processing apparatus, a pattern formed on the substrate might collapse due to capillary action of the rinse remaining in the pattern. 
         [0005]    To solve the problem, a technique of forming a water repellent protective film on the surface of the substrate in advance to reduce surface tension of liquid acting on the pattern during drying is known (e.g., US2009/0311874). In this technique, water repellent is supplied to the substrate in the processing tank to make the substrate water-repellent. An alcohol rinse is then performed by supplying IPA to the substrate in the processing tank to replace unreacted water repellent remaining on the surface of the substrate with the IPA and remove the unreacted water repellent. 
         [0006]    The substrate processing method according to US2009/0311874 can suppress the pattern collapse caused by drying. When the alcohol rinse is performed after water repellent processing, however, unreacted water repellent remaining in the storage tank might react with the IPA to generate particles, such as silica particles. As a result, the substrate in the processing tank might be contaminated with the particles. 
       SUMMARY OF THE INVENTION 
       [0007]    The present invention is directed to a substrate processing method. 
         [0008]    In one aspect of the present invention, the substrate processing method includes: the steps of: dipping a substrate into a rinse stored in a processing tank to clean a surface of the substrate with the rinse; supplying an organic solvent vapor into a chamber surrounding the processing tank to form an organic solvent vapor atmosphere inside the chamber including space above the processing tank; elevating the substrate to the space above the processing tank to replace the rinse adhering to the surface of the substrate with an organic solvent; draining the rinse in the processing tank; moving the substrate into the processing tank; supplying water repellent to the surface of the substrate having been moved into the processing tank to make the surface of the substrate water-repellent; elevating the substrate above the processing tank, and supplying an organic solvent vapor to the substrate above the processing tank to remove unreacted water repellent remaining on the surface of the substrate; and supplying inert gas to the substrate to dry the substrate. 
         [0009]    The water repellent processing is performed in the processing tank to make the surface of the substrate water-repellent. This prevents the pattern formed on the surface of the substrate from collapsing during drying performed by supplying the inert gas to the surface of the substrate. After the water repellent processing, the unreacted water repellent remaining on the surface of the substrate is removed above the processing tank. If the unreacted water repellent remaining in the processing tank reacts with the organic solvent used to remove the unreacted water repellent to generate particles after the water repellent processing, the substrate is located above the processing tank at the time. Contamination of the substrate is prevented or suppressed by removing the unreacted water repellent. As a result, the substrate can be dried while cleanliness of the substrate is maintained. 
         [0010]    The organic solvent is preferably IPA. 
         [0011]    The organic solvent vapor supplied to the substrate in removing the unreacted water repellent is preferably at a higher temperature than the water repellent supplied to the substrate in making the surface of the substrate water-repellent. 
         [0012]    It is an object of the present invention to provide a substrate processing method that enables drying of the substrate without causing the pattern collapse while maintaining cleanliness of the substrate. 
         [0013]    These and other objects, features, aspects and advantages of the present invention will become more apparent from the following detailed description of the present invention when taken in conjunction with the accompanying drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0014]      FIG. 1  is a schematic diagram illustrating the structure of a substrate processing apparatus according to one embodiment of the present invention; 
           [0015]      FIG. 2  is a flow chart describing operations of substrate processing performed by the substrate processing apparatus  1 ; 
           [0016]      FIG. 3  is a schematic diagram illustrating operation of the substrate processing apparatus in step S 1  of  FIG. 2 ; 
           [0017]      FIG. 4  is a schematic diagram illustrating operation of the substrate processing apparatus in step S 2  of  FIG. 2 ; 
           [0018]      FIG. 5  is a schematic diagram illustrating operation of the substrate processing apparatus in step S 3  of  FIG. 2 ; 
           [0019]      FIG. 6  is a schematic diagram illustrating operation of the substrate processing apparatus in step S 4  of  FIG. 2 ; 
           [0020]      FIG. 7  is a schematic diagram illustrating operation of the substrate processing apparatus in step S 5  of  FIG. 2 ; 
           [0021]      FIG. 8  is a schematic diagram illustrating operation of the substrate processing apparatus in step S 6  of  FIG. 2 ; 
           [0022]      FIG. 9  is a schematic diagram illustrating operation of the substrate processing apparatus in step S 7  of  FIG. 2 ; 
           [0023]      FIG. 10  is a schematic diagram illustrating operation of the substrate processing apparatus in step S 8  of  FIG. 2 ; 
           [0024]      FIG. 11  is a schematic diagram illustrating operation of the substrate processing apparatus in step S 9  of  FIG. 2 ; 
           [0025]      FIG. 12  is a schematic diagram illustrating operation of the substrate processing apparatus in step S 10  of  FIG. 2 ; and 
           [0026]      FIG. 13  is a schematic diagram illustrating operation of the substrate processing apparatus in step S 11  of  FIG. 2 . 
       
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0027]    The following describes a substrate processing apparatus according to one embodiment of the present invention with reference the drawings. In the following description, a substrate refers to a semiconductor wafer, a glass substrate for liquid crystal display, a glass substrate for plasma display panel (PDP), a glass substrate for photomask, a substrate for optical disc, and the like. 
       Structure of Main Components of Substrate Processing Apparatus 
       [0028]      FIG. 1  is a front view of a substrate processing apparatus  1  according to an embodiment of the present invention. 
         [0029]    The substrate processing apparatus  1  blows IPA, which is an organic solvent, onto a substrate having been rinsed with pure water to dry the substrate. The substrate processing apparatus  1  mainly includes: a chamber  10 ; a processing tank  20 ; a holding mechanism  30 ; an elevating mechanism  40 ; nozzles  51  to  55 ; valves  61  to  65  for opening and closing the nozzles; an inert gas supply source  71  for supplying inert gas, such as nitrogen gas, to the nozzles  51 ; an IPA supply source  72  for supplying IPA vapors to the nozzles  52 ; an IPA supply source  73  for supplying IPA vapors to the nozzles  53 ; a water repellent supply source  74  for supplying water repellent to the nozzles  54 ; a processing liquid supply source  75  for supplying a rinse, such as pure water, to the processing liquid supply nozzle  55 ; and a controller  80 . 
         [0030]    The chamber  10  is an enclosure for housing therein the processing tank  20 , the elevating mechanism  40 , the nozzles  51  to  55 , and the like. An upper part  11  of the chamber  10  can be opened and closed. When the upper part  11  of the chamber  10  is opened, substrates W can be transported through the opening part. When the upper part  11  of the chamber  10  is closed, space inside the chamber  10  is closed space. 
         [0031]    The processing tank  20  is used to store chemical liquid, such as fluorinated acid, or a rinse, such as pure water, (hereinafter, collectively referred to as “processing liquid”) to sequentially process the surfaces of the substrates, and is housed in the chamber  10 . The nozzle  55  is disposed near the bottom of the processing tank  20 , and processing liquid can be supplied from the processing liquid supply source  75  to the processing tank  20  through the nozzle  55 . The processing liquid is supplied from the bottom of the processing tank  20 , and flows out of the processing tank  20  from an opening  20 P. The processing tank  20  can drain the processing liquid stored in the processing tank  20  to a drain line by opening a drain valve  66 . 
         [0032]    The holding mechanism  30  holds a plurality of substrates W separated from one another in an X direction with their main surfaces (circuit formation surfaces) being vertical. The elevating mechanism  40  can elevate and lower the holding mechanism  30  in a vertical direction (Z direction) to move the substrates W held by the holding mechanism  30  between a position (a position shown in solid lines in  FIG. 1 , and referred to as a lower position) where the substrates W are dipped in the processing liquid stored in the processing tank  20  and a position (a position shown in imaginary lines in  FIG. 1 , and referred to as an upper position) where the substrates W have been elevated from the processing liquid. 
         [0033]    The nozzles  53  and  54  are disposed near the opening  20 P in the space above the processing tank  20 . 
         [0034]    The nozzles  53  are hollow tubular members extending in the X direction, and each have a plurality of discharge holes (not illustrated) arranged at equal intervals in the X direction. The nozzles  53  are two nozzles arranged in a Y direction along upper corners of the processing tank  20  so as to be in parallel to each other. IPA vapors are discharged from the above-mentioned discharge holes of the nozzles  53  to the opening  20 P of the processing tank  20  to form an atmosphere containing the IPA vapors inside the processing tank  20 . 
         [0035]    The IPA vapors are supplied from the IPA supply source  73  external to the chamber  10  to the nozzles  53 . The valve  63  is disposed along a duct between the nozzles  53  and the IPA supply source  73 , and the quantity of the IPA vapors discharged from the nozzles  53  can be controlled by adjusting opening of the valve  63 . 
         [0036]    The nozzles  54  are hollow tubular members extending in the X direction, and each have a plurality of discharge holes (not illustrated) arranged at equal intervals in the X direction. The nozzles  54  are two nozzles arranged in the Y direction along the upper corners of the processing tank  20  so as to be in parallel to each other. Water repellent is discharged from the above-mentioned discharge holes of the nozzles  54  to the opening  20 P of the processing tank  20  to store liquid-phase water repellent in the processing tank  20  and to form an atmosphere containing a mist of the water repellent inside the processing tank  20 . 
         [0037]    The water repellent is silicon-based water repellent that makes silicon itself and a compound containing silicon hydrophobic, or metal-based water repellent that makes metal itself and a compound containing metal hydrophobic. 
         [0038]    The metal-based water repellent contains at least one of amine having a hydrophobic group and an organic silicon compound, for example. 
         [0039]    The silicon-based water repellent is a silane coupling agent, for example. The silane coupling agent contains at least one of hexamethyldisilazane (HMDS), tetramethylsilane (TMS), fluorinated alkylchlorosilane, alkyldisilazane, and non-chloro water repellent, for example. 
         [0040]    The non-chloro water repellent contains at least one of dimethylsilyldimethylamine, dimethylsilyldiethylamine, hexamethyldisilazane, tetramethyldisilazane, bis(dimethylamino)dimethylsilane, N,N-dimethylaminotrimethylsilane, N-(trimethylsilyl) dimethylamine, and an organosilane compound, for example. 
         [0041]    It is desirable to use water repellent diluted with a solvent that is mutually soluble with a hydrophilic organic solvent, such as IPA. In this case, it is desirable to mix the water repellent and the solvent that is mutually soluble with the hydrophilic organic solvent, such as IPA, together immediately before the nozzles  54 , and then supply the mixture to the nozzles  54 . 
         [0042]    In the space above the processing tank  20 , the nozzles  51  and  52  are disposed above the above-mentioned nozzles  53  and  54 . 
         [0043]    Nitrogen gas is supplied from the inert gas supply source  71  external to the chamber  10  to the nozzles  51 . It is desirable to heat the nitrogen gas to room temperature or higher. The valve  61  is disposed along a duct between the nozzles  51  and the inert gas supply source  71 , and the quantity of the nitrogen gas discharged from the nozzles  51  is controlled by adjusting opening of the valve  61 . The nozzles  51  are directed to the substrates W elevated to the upper position. The nitrogen gas is discharged from the nozzles  51  to fill the space inside the chamber  10  including the space above the processing tank  20  with the nitrogen gas, and the substrates W located at the upper position are dried (described in detail later). 
         [0044]    The IPA vapors are supplied from the IPA supply source  72  external to the chamber  10  to the nozzles  52 . The valve  62  is disposed along a duct between the nozzles  52  and the IPA supply source  72 , and the quantity of the IPA vapors discharged from the nozzles  52  is controlled by adjusting opening of the valve  62 . The nozzles  52  are directed to the substrates W elevated to the upper position. The IPA vapors are discharged from the nozzles  52  to fill the space inside the chamber  10  including the space above the processing tank  20  with the IPA vapors, and excess water repellent can be removed from the substrates W located at the upper position by the IPA vapors (described in detail later). 
         [0045]    The above-mentioned valves  61  to  66 , elevating mechanism  75 , supply sources  71  to  75  operate through control performed by the controller  80 . 
       Substrate Processing Performed by Substrate Processing Apparatus  1   
       [0046]    The substrate processing performed using the substrate processing apparatus  1  is described next.  FIG. 2  is a flow chart describing operations of the substrate processing performed by the substrate processing apparatus  1 .  FIGS. 3 to 13  are schematic diagrams describing the substrate processing performed by the substrate processing apparatus  1 . 
         [0047]    The controller  80  stores chemical liquid, such as fluorinated acid, in the processing tank  20  in a state where the holding mechanism  30  is located at the lower position in the processing tank  20  to perform chemical liquid processing, such as cleaning, with respect to the substrates W held by the holding mechanism  30  (step S 1  in  FIG. 2 , and  FIG. 3 ). 
         [0048]    The controller  80  then opens the valve  65  to introduce pure water from the processing liquid supply source  75  to the nozzle  55  while opening the valve  66  to drain the chemical liquid stored in the processing tank  20 . As a result, the chemical liquid stored in the processing tank  20  is gradually replaced with the pure water to perform a rinse of cleaning the surfaces of the substrates W with the pure water (step S 2  in  FIG. 2 , and  FIG. 4 ). 
         [0049]    The controller  80  then opens the valve  62  to supply IPA vapors from the nozzles  52  to the space above the processing tank  20 . The controller  80  also opens the valve  63  to supply IPA vapors from the nozzles  53  to the opening  20 P of the processing tank  20 . As a result, an IPA vapor atmosphere is formed inside the chamber  10  surrounding the processing tank  20  (step S 3  in  FIG. 2 , and  FIG. 5 ). 
         [0050]    The controller  80  then controls the elevating mechanism  40  to move the holding mechanism  30  located at the lower position to the upper position above the processing tank  20  while continuing supplying the IPA vapors from the nozzles  52  and  53 . The substrates W held by the holding mechanism  30  are exposed to the IPA vapors supplied from the nozzles  52  and  53  while the holding mechanism  30  is elevated from the lower position to the upper position. As a result, the pure water adhering to the substrates W is replaced with the IPA (step S 4  in  FIG. 2 , and  FIG. 6 ). 
         [0051]    The controller  80  then opens the valve  66  to drain the pure water stored in the processing tank  20  (step S 5  in  FIG. 2 , and  FIG. 7 ). 
         [0052]    The controller  80  then controls the valves  62  and  63  to adjust (reduce) the quantity of the IPA vapors discharged from the nozzles  52  and  53 . The controller  80  also closes the valve  66  so that a fluid can be stored in the processing tank  20 . The controller  80  then opens the valve  64  to start supplying water repellent from the nozzles  54  to the processing tank  20 . As a result, the water repellent is stored in the processing tank  20  (step S 6  in  FIG. 2 , and  FIG. 8 ). The water repellent is not limited to liquid water repellent, and may be in the form of a vapor or a mist. The water repellent may be supplied to the processing tank  20  from the nozzle  55  in the processing tank  20  in place of (or in addition to) the nozzles  54 . 
         [0053]    When the substrate to which moisture adheres is brought into direct contact with the water repellent, modifying performance can be reduced, and foreign matter can be generated. In the present embodiment, replacement with IPA (step S 4 ) is performed before the water repellent processing in step S 7  to remove moisture from the surfaces of the substrates W. As described above, the water repellent processing (step S 7 ) is performed with respect to the substrates W from which moisture has been removed. Generation of foreign matter during the water repellent processing can thus be prevented or suppressed. 
         [0054]    The controller  80  then controls the elevating mechanism  40  to move the holding mechanism  30  located at the upper position to the lower position in the processing tank  20 . As a result, the surfaces of the substrates W held by the holding mechanism  30  are modified to be water-repellent by the water repellent (the water repellent processing, step S 7  in  FIG. 2 , and  FIG. 9 ). The controller  80  may control the elevating mechanism  40  to rock the holding mechanism  30  in the processing tank  20  when the water repellent processing is performed in step S 7 . As a result, the surfaces of the substrates W are more evenly modified. 
         [0055]    The controller  80  then controls the valve  64  to stop supplying the water repellent from the nozzles  54  (step S 8  in  FIG. 2 , and  FIG. 10 ). 
         [0056]    The controller  80  then controls the elevating mechanism  40  to move the holding mechanism  30  located at the lower position to the upper position above the processing tank  20 . As a result, the substrates W whose surfaces have been modified to be water repellent are elevated to the upper position above the processing tank  20 . Unreacted water repellent adhering to the substrates W is removed by the IPA vapors from the nozzles  52  and  53  (step S 9  in  FIG. 2 , and  FIG. 11 ). The holding mechanism  30  is moved from the lower position to the upper position in a relatively short time (e.g., in approximately  10  seconds), and thus only a few particles, such as silica particles, are generated if the unreacted water repellent adhering to the substrates W reacts with the IPA. The surfaces of the substrates W are therefore kept clean. 
         [0057]    The controller  80  then opens the valve  66  while continuing supplying the IPA vapors from the nozzles  52  and  53 . As a result, the water repellent is removed from the surfaces of the substrates W. In addition, the unreacted water repellent adhering to an inner wall and the like of the processing tank  20  is removed by the IPA vapors from the nozzles  53 , and is drained from the drain line to the outside of the processing tank  20  (step S 10  in  FIG. 2 , and  FIG. 12 ). The unreacted water repellent adhering to the inner wall and the like of the processing tank  20  can react with the IPA vapors to generate particles, such as silica particles, in the processing tank  20 . The substrates W, however, have been elevated above the processing tank  20  in the stage preceding step S 10 . This suppresses or prevents adhesion of particles, such as silica particles, that can be generated in the processing tank  20  to the substrates W. Air currents of the IPA vapors are formed by the nozzles  53  from above the processing tank  20  to the bottom of the processing tank  20 . This suppresses or prevents contamination of the substrates W located above the processing tank  20  with the particles generated in the processing tank  20  and passing through the opening  20 P. 
         [0058]    When step S 10  is further continued, the unreacted water repellent adhering to the inner wall and the like of the processing tank  20  and the particles, such as silica particles, generated by reaction of the water repellent with the IPA vapors are removed by the IPA vapors from the nozzles  52  and  53 , and are drained to the drain line. As a result, the inside of the processing tank  20  has been cleaned when step S 10  is completed. 
         [0059]    It is desirable that the IPA vapors supplied from the nozzles  52  and  53  in step S 10  be at a higher temperature than the water repellent supplied from the nozzles  54  in the water repellent processing performed in step S 7 . As a result, the water repellent can efficiently be removed from the surfaces of the substrates W. 
         [0060]    The controller  80  then closes the valves  62 ,  63 , and  64 , and opens the valve  61 . As a result, heated inert gas is supplied from the nozzles  51  to the substrates W located at the upper position. The surfaces of the substrates W are thereby eventually dried. 
       Modifications 
       [0061]    Although the IPA vapors and the nitrogen gas are discharged from separate supply nozzles in the present embodiment, the IPA vapors and the nitrogen gas may be discharged from the same nozzle. 
         [0062]    In the above-mentioned embodiment, the IPA is used when moisture is removed from the surfaces of the substrates W (step S 4 ), or when the water repellent is removed from the substrates (step S 10 ). Any organic solvent, other than the IPA, that can be replaced with the rinse, such as water, and a solvent used in the water repellent can be used. 
         [0063]    The present invention can effectively be used for processing of a substrate. 
         [0064]    While the invention has been shown and described in detail, the foregoing description is in all aspects illustrative and not restrictive. It is therefore understood that numerous modifications and variations can be devised without departing from the scope of the invention.