Abstract:
An apparatus causes a substrate to rotate and supplies a treatment liquid to a substrate surface to make a treatment, without concern that a mixed substance is eluted from a cup in the use for a long time, or a thin film comes off from an inside wall surface to be contamination-causing substances even if the cup made of a water-repellent material for collecting a treatment liquid becomes hydrophilic. A cup  16  disposed to surround the sides and underside of a substrate W rotating while being held by a spin chuck  10,  and serving to collect a treatment liquid diffused from the substrate to the surroundings, is made of a plastic material. Further, an inside wall surface of an upper-side cup part  24  of the cup  16,  being a portion on which the treatment liquid having been diffused from the substrate impinges, is roughened to be a hydrophilic surface.

Description:
BACKGROUND OF THE INVENTION  
       [0001]     1. Field of the Invention  
         [0002]     The present invention relates to a substrate rotation type treatment apparatus that holds substrates such as semiconductor wafers, liquid crystal display glass substrates, photo-mask glass substrates, optical disk substrates in a horizontal posture to cause the substrates to rotate about a vertical axis, and supplies to the substrate surface treatment liquids such as cleaning fluids, coating solutions, and developers to make the substrate treatment such as cleaning, coating, and development.  
         [0003]     2. Description of the Related Art  
         [0004]     When substrates such as semiconductor wafers are held in a horizontal posture with a spin chuck to be brought in rotation about a vertical axis, and a treatment liquid, for example, a cleaning fluid, e.g., pure water is supplied to the substrate surface to make the cleaning treatment of the substrates, the cleaning fluid having been supplied on the substrate surface spreads to the substrate edge due to a centrifugal force, and the cleaning fluid having been used is diffused from the substrate edge to the surroundings. There is provided around a substrate, which is held by a spin chuck, a cup so as to surround the sides and the under side of the substrate. The used cleaning fluid having been diffused from the substrate to the surroundings impinges on the inside wall surface of a cup to be collected, flows down on the cup inside wall surface to be collected at the cup bottom, and is discharged from a drain, which is provided in the cup bottom, through a drain pipe to be recycled.  
         [0005]     A cup for collecting a treatment liquid having been diffused from a substrate to the surroundings has been conventionally made of plastic materials such as fluororesin, e.g., polytetrafluoroethylene (PTFE), polyvinylchloride (PVC), and polypropylene (PP), or metal materials such as stainless steel. At present, however, most cups are made of resin. A main function of this cup is to prevent a treatment liquid having been diffused from the substrate to the surroundings from being diffused also to the outside of the substrate treatment section, as well as to collect the treatment liquid to cause it to flow to a drain in the cup bottom. Nevertheless, a plastic material, especially, fluororesin that forms a cup is water-repellent (hydrophobic), and an inside wall surface of the cup will be repellent to a hydrophilic treatment liquid such as cleaning fluid, e.g., pure water when the treatment liquid impinges thereon.  
         [0006]     FIGS.  4 -A and  4 -B are schematic diagrams showing the schematic construction of substrate rotation type treatment apparatuses. In the drawings, reference numeral  1  designates a spin chuck that holds a substrate W in a horizontal posture. Numeral  2  designates a rotary shaft that supports the spin chuck  1  holding a substrate W to cause it to rotate about a vertical axis. Numeral  3  designates a cup that collects a treatment liquid. Numeral  4  designates a drain portion that discharges the treatment liquid, and recycles it. When the cups  3  is made of a hydrophilic material, as shown in  FIG. 4 -B, a hydrophilic treatment liquid having been diffused from the surface of a substrate W to the surroundings to impinge on the inside wall surface of the cup  3  spreads forming a thin film on the inside wall surface to flow down to the bottom of the cup  3 , and is discharged through the drain portion  4 . In contrast, when the cup  3  is made of a water-repellent material, as shown in  FIG. 4 -A, a treatment liquid having been diffused from the surface of a substrate W to the surroundings to impinge on the inside wall surface of the cup  3  is splashed on the inside wall surface, and a part of it will adhere to the surface of a substrate W again. At this time, a problem arises in that when a treatment liquid such as used cleaning fluid contains impurities, the impurities in the treatment liquid becomes particles to be contamination-causing substances of a substrate W. Moreover, a further problem arises in that when a treatment liquid adheres to the inside wall surface of the cup  3  to be dried, and treatment liquid constituents are accumulated during the treatment of a number of substrates, the accumulated constituents become particles to adhere to the surface of a substrate W along with the treatment liquid having been splashed on the inside wall surface to be contamination-causing substances.  
         [0007]     To overcome this problem, it has been carried out that a cup made of a water-repellent material is made hydrophilic. Several methods of making hydrophilic include, for example, as disclosed in the Japanese Patent Publication (unexamined) No. 258249/1998, a method that material properties itself is improved to be hydrophilic by mixing a substance for making hydrophilic into resin material at the time of making a cup of a plastic material by molding, or another method that the inside wall surface of a cup is made hydrophilic by a hydrophilic material being deposited on the inside wall surface of a cup forming a thin film.  
         [0008]     However, in a cup which material properties itself is improved to be hydrophilic by mixing a substance into resin material, a problem still exists in that the mixed substances will be eluted in the use of a long time period to become contamination-causing substances of a substrate. Moreover, in a cup on the inside wall surface of which a hydrophilic material is deposited forming a thin film, a problem exists in that the thin film of hydrophilic material comes off from the inside wall surface in the use of a long time period to become contamination-causing substances of a substrate.  
       SUMMARY OF THE INVENTION  
       [0009]     The present invention was made in view of the problems as describe above, and has an object of providing a substrate rotation type treatment apparatus without any concern that a mixed substance is eluted from a cup in the use of a long time period, or a thin film comes off from an inside wall surface to be contamination-causing substances even if a cup made of a water-repellent material is made hydrophilic.  
         [0010]     An invention as defined in claim  1 , being a substrate rotation type treatment apparatus causing a substrate to rotate to make substrate treatment, includes:  
         [0011]     substrate holding means for holding the substrate in a horizontal posture;  
         [0012]     substrate rotation means for causing the substrate that is held by the mentioned substrate holding means to rotate about a vertical axis;  
         [0013]     treatment liquid supply means for supplying a treatment liquid to a surface of the substrate held by the mentioned substrate holding means; and  
         [0014]     a cup having a container shape of which top is open, and which is disposed so as to surround the sides and the under side of the substrate held by the mentioned substrate holding means, and which serves to collect a treatment liquid to be diffused from the substrate to the surroundings;  
         [0015]     in which the mentioned cup is made of a plastic material, and at least a portion of an inside wall surface of this cup on which a treatment liquid having been diffused from the substrate to the surroundings impinges is roughened to be a hydrophilic surface.  
         [0016]     An invention as defined in claim  2 , being the substrate rotation type treatment apparatus according to claim  1 , is characterized in that the inside wall surface of the mentioned cup is roughened so that a contact angle is not more than 10°.  
         [0017]     An invention as defined in claim  3 , being the substrate rotation type treatment apparatus according to claim  1  or claim  2 , is characterized in that there are mixed hydrophilic surface and hydrophobic surface at least at the portion of the inside wall surface of the mentioned cup on which a treatment liquid having been diffused from the surface to the surroundings impinges.  
         [0018]     An invention as defined in claim  4 , being the substrate rotation type treatment apparatus according to claim  3 , is characterized in that there are mixed hydrophilic surface and hydrophobic surface in a striped pattern extending horizontally.  
         [0019]     An invention as defined in claim  5 , being the substrate rotation type treatment apparatus according to claim  3 , is characterized in that there are mixed hydrophilic surface and hydrophobic surface in a checkered pattern.  
         [0020]     In the substrate rotation type treatment apparatus of the invention according to claim  1 , the inside wall surface of a cup is made to be a hydrophilic surface, so that a treatment liquid having been diffused from a substrate to the surroundings to impinge on the inside wall surface of the cup spreads forming a thin film on the inside wall surface to flow down to the bottom of the cup to be drained. Therefore, it is possible to prevent a treatment liquid having been diffused from the substrate from being splashed on the inside wall surface of the cup to adhere to a surface of the substrate again resulting in the contamination of the substrate.  
         [0021]     Furthermore, in the substrate rotation type treatment apparatus of the invention according to claim  1 , the inside wall surface of a cup is made to be a hydrophilic surface by roughening, so that there is no worry at all that a mixed substance is eluted form the cup in the use of a long time period, or a thin film comes off from an inside wall surface to be contamination-causing substances.  
         [0022]     In the substrate rotation type treatment apparatus of the invention according to claim  2 , any hydrophilic treatment liquid is not splashed at all on the inside wall surface of a cup, and the treatment liquid having been diffused from the substrate to impinge on the inside wall surface of the cup spreads in the thinner film condition on the inside wall surface, and flows down to the bottom of the cup to be drained.  
         [0023]     In the substrate rotation type treatment apparatus of the invention according to claim  3  or  5 , as compared with a cup in which an overall portion of the inside wall surface of a cup on which a treatment liquid having been diffused from the surface to the surroundings impinges is a hydrophobic surface, splashing of a hydrophilic treatment liquid is decreased, as well as a treatment liquid having impinged on the hydrophobic surface to be diffused on the surface rapidly flows to the adjacent hydrophilic surface to aggregate on the hydrophilic surface, so that splashing of a treatment liquid is unlikely to occur. Originally splashing of the treatment liquid impinged on the hydrophobic surface does not easily take place in itself. Thus, it is prevented that a treatment liquid having been diffused from the surface to impinge on the inside wall surface of a cup is splashed on the inside wall surface, and that a part of the used treatment liquid adheres to a surface of the substrate. On the other hand, when a treatment liquid having impinged on a hydrophilic surface to spread forming a thin film, or having flowed from a hydrophobic surface to a hydrophilic surface to aggregate, grows up to a certain size of droplets, it flows down from the hydrophilic surface to the adjacent hydrophobic surface, so that a time period of a treatment liquid being retained on the hydrophilic surfaces comes to be shorter. Consequently, it is prevented that a treatment liquid adheres to the inside wall surface of a cup to be dried, and that impurities or treatment liquid constituents are accumulated on the inside wall surface of the cup.  
         [0024]     As described above, with the use of a substrate rotation type treatment apparatus according to claim  3  or claim  5 , it is prevented that a treatment liquid having been diffused from the surface of a rotating substrate is splashed on the inside wall surface of a cup, as well as that a treatment liquid adheres to the inside wall surface of the cup to be dried, and that impurities or treatment liquid constituents are accumulated on the cup inside wall surface. As a result, it is possible to eliminate the causes of substrate contamination resulted from the cup.  
         [0025]     The foregoing 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  
       [0026]      FIG. 1  shows one example of preferred embodiments according to the present invention, and is a longitudinal section showing a schematic construction of an essential part of a substrate rotary cleaning apparatus, being a substrate rotation type treatment apparatus.  
         [0027]      FIG. 2  shows another embodiment of the invention, and is a view showing in a developed state an upper cup part of a cup, being a component of the substrate rotary cleaning apparatus.  
         [0028]      FIG. 3  shows a further embodiment of the invention, and is a view showing in a developed state an upper cup part of a cup, being a component of the substrate rotary cleaning apparatus.  
         [0029]      FIG. 4 -A is a schematic view showing a schematic construction of the substrate rotation type treatment apparatus to explain the situation in which a hydrophilic treatment liquid having been diffused from the surface of a substrate to the surroundings impinges on the water-repellent cup inside wall surface.  
         [0030]      FIG. 4 -B is a schematic diagram showing a schematic construction of the substrate rotation type treatment apparatus to explain the situation in which a hydrophilic treatment liquid having been diffused from the surface of a substrate to the surroundings impinges on the hydrophilic cup inside wall surface. 
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0031]     Several preferred embodiments according to the present invention are hereinafter described referring to  FIG. 1 .  
         [0032]      FIG. 1  shows one example of preferred embodiments according to the invention, and is a longitudinal section showing a schematic construction of an essential part of a substrate rotation type treatment apparatus, for example, a substrate rotary cleaning apparatus (spin scrubber).  
         [0033]     This cleaning apparatus includes a spin chuck  10  that holds a substrate W such as semiconductor wafers in a horizontal posture. The substrate W, which is held by the spin chuck  10 , is made to rotate in a horizontal plane about a vertical axis by a spin motor  14  that is connected to a rotary shaft  12  supporting the spin chuck  10 . There is provided around the substrate W a cup  16  that is formed in a container shape which top is open, and which surrounds the sides and the under side of the substrate W held by the spin chuck  10 . There is provided a baffle member  18  of a truncated cone shape under the substrate W that is held by the spin chuck  10  in an internal part of the cup  16 . A support cylinder  20  is integrally fixed to the central portion of the baffle member  18 . Further, a rotary shaft  12  is inserted through in a internal part of the support cylinder  20 . The cup  16  and the baffle member  18  are connected as an integral whole so that a bottom wall of the cup  16  is bended to come around the bottom face of the baffle member  18 . The support cylinder  20  and the rotary shaft  12  are not connected together. Thus, the cup  16 , the baffle member  18  and the support cylinder  20  can move upward and downward as an integral whole with respect to the spin chuck  10 , the rotary shaft  12  and the spin motor  14 , and are arranged to move up and down between the position at the time of substrate cleaning as shown and the lower position at the time of carrying the substrate in and out by a hoisting and lowering mechanism, not shown.  
         [0034]     There is disposed a cleaning fluid supply nozzle  22  that supplies a cleaning fluid such as pure water onto the surface of a substrate W above the substrate W held by the spin chuck  10 . The cleaning supply nozzle  22  can be restored outside the cup  16  from the position as shown. Moreover, although not shown, there is provided a rotary cleaning brush that makes a scrub cleaning while scanning the surface of the substrate W above the substrate W held by the spin chuck  10 , and this rotary cleaning brush is supported so as to be capable of moving upward and downward.  
         [0035]     The cup  16  comprises an upper-side cup part  24  of which perimeter is formed in a truncated cone shape, and of which inside wall is broadened downward, a lower-side cup part  26  that is connected to the lower end of this upper-side cup part  24  to be formed in a cylindrical shape and includes a bottom wall bended so as to come around the bottom face of the baffle member  18 , and an annular part  28  that is connected to the upper end of the upper-side cup  24  to horizontally overhang inward from this upper end. These parts form an integral whole of a container shape. The upper-side cup part  24  is disposed at the height including a horizontal plane where a substrate W held by the spin chuck  10  is positioned at the time of substrate cleaning, and a cleaning fluid having been diffused from the surface of the substrate W to the surroundings impinges on an inside wall surface of the upper-side cup part  24 . There is formed a drain  30  in the bottom wall of the lower-side cup part  26 , and a drainpipe  32  is connected to the drain  30 . Furthermore, there is provided an air release pipe  34  open at a position opposite to the lower face of the baffle member  18 , and the discharge of air in the cup  16  is performed through this air release pipe  34 .  
         [0036]     The cup  16  constructed described above is made of a plastic material such as fluororesin, e.g., PTFE, polyvinyl chloride or polypropylene. Further, at least the upper-side cup part  24  of the cup  16 , that is the whole or a part of the inside wall surface of the upper-side cup part  24 , being a portion on which a cleaning fluid having been diffused from the surface of a substrate W to the surroundings, impinges is roughened uniformly, whereby an inside wall surface of the upper-side cup part  24  becomes a hydrophilic surface. Preferably, the inside wall surface of the upper-side cup part  24  is roughened so as to be a hydrophilic surface having a contact angle of not more than 10°. The methods of roughening include, for example, physically roughening an inside wall surface using, e.g., extremely smooth-cut file; plasma treatment, i.e., using a nozzle having a plasma generating part at the tip, and scanning an inside wall surface with this nozzle tip to roughen the inside wall surface; or using a chemical agent, and applying this chemical agent to an inside wall surface to roughen the inside wall surface. However, the roughening method may be any one of the conventional methods. In addition, a part or the whole of an inside wall surface of the lower-side cup pat  26  other than the upper-side cup part  24  may be roughened to form a hydrophilic surface.  
         [0037]     In this substrate rotary cleaning apparatus, since an inside wall surface of the upper-side cup part  24  of the cup  16  is roughened to be a hydrophilic surface, at the time of substrate cleaning, a used cleaning fluid such as pure water having been diffused from the surface of a rotating substrate W to the surroundings due to the centrifugal force impinges on the inside wall surface of the upper-side cup part  24  of the cup  16 , spreads forming a thin film on the inside wall surface without being flashed, and flows down to the lower-side cup part  26 . Then, the cleaning fluid rapidly flows down on the inside wall surface of the lower-side cup part  26 , being a hydrophobic surface to be collected at the inner bottom, flows from the inner bottom of the lower-side cup part  26  toward the drain  30 , and is discharged outside the cup  16  from the drain  30  through the drain pipe  32  to be recycled. In this manner, a cleaning fluid having been diffused from the substrate W is prevented from impinging on the inside wall surface of the cup  16  and adhering to a surface of the substrate W again, resulting in the contamination of a substrate.  
         [0038]     An experiment using the substrate rotary cleaning apparatus was carried out to compare degrees of splashing of a cleaning fluid (pure water) from the cup inside wall surface between a PVC cup (inside diameter: 400 mm) of which inside wall surface is not roughened yet by plasma treatment, and that of which inside wall surface has been roughened. When a wafer (diameter: 300 mm) was rotated at a speed of 1000 rpm and was dripped with back-rinse at the flow rate of 300 ml/min at the central portion thereof, the number of water droplets of a size of not less than 12 μm that were adherent to a wafer surface due to splashing of pure water on the cup inside wall surface was counted. As are result, while the number of water droplets before plasma treatment of the inside wall surface of a cup was 1000, it was 10 after the plasma treatment. From this result, it was actually acknowledged that splashing of a cleaning fluid from the inside wall surface of a cup is significantly decreased by the inside wall surface of a cup made of PVC being plasma-treated to be roughened.  
         [0039]     In the case where the whole or a part of the inside wall surface of the upper-side cup part  24  is roughened to be a hydrophilic surface, it is preferable that the whole or a part of the inside wall surface of the upper-side cup part  24  is made to be uniformly a hydrophilic surface, or to be mixed hydrophilic surfaces and hydrophobic surfaces. For example, as a development view of an inside wall surface of the upper-side cup part shown in  FIG. 2 , it is preferable that an inside wall surface of the upper-side cup part  24 a is roughened so that there are mixed hydrophilic surfaces  36  and hydrophobic surfaces  38  in a horizontally extending striped pattern. In addition, as a development view of an inside wall surface of the upper-side cup part shown in  FIG. 3 , it is preferable that an inside wall surface of the upper-side cup part  24  is roughened so that there are mixed hydrophilic surfaces  42  and hydrophobic surfaces  44  in a checkered pattern. Furthermore, it is preferable to be in the other forms, for example, in a scaled pattern of the combination of triangles, or in a honeycomb pattern of the combination of hexagons.  
         [0040]     As shown in  FIG. 2  and  FIG. 3 , when there are mixed hydrophilic surfaces  36 ,  42  and hydrophobic surfaces  38 ,  44  on the inside wall surface of the upper-side cup parts  24   a,    24   b,  since a cleaning fluid having impinged on the hydrophobic surfaces  38 ,  44  of the inside wall surface of the upper-side cup parts  24   a,    24   b  to be diffused on the surface rapidly flows to the adjacent hydrophilic surfaces  36 ,  42  above and below to aggregate on the hydrophilic surfaces  36 ,  42 , splashing of a cleaning fluid is unlikely to occur. Further, a cleaning fluid having impinged on the hydrophilic surfaces  36 ,  42  on the inside wall surface of the upper-side cup parts  24   a,    24   b  spreads forming a thin film, so that originally splashing is unlikely to occur. Accordingly, a cleaning fluid having been diffused from a substrate W to impinge on the inside wall surface of the upper-side cup parts  24   a,    24   b  is not splashed on the inside wall surface to prevent a part of used cleaning fluid from adhering to a surface of the substrate W again. Thus, there will be no fear of impurities that are contained in the used cleaning fluid coming to be particles to contaminate the substrate W.  
         [0041]     On the other hand, when a cleaning fluid having impinged on the hydrophilic surfaces  36 ,  42  on the inside wall surface of the upper-side cup parts  24   a,    24   b  to spread forming a thin film, or having flowed from the hydrophobic surfaces  28 ,  44  to the hydrophilic surfaces  36 ,  42  to aggregate grows up to a droplet of a certain size, it flows down from the hydrophilic surfaces  36 ,  42  to the hydrophobic surfaces  38 ,  44  adjacent to the lower side thereof, so that a time period of being retained on the hydrophilic surfaces  36 ,  42  becomes shorter. Accordingly, it is prevented that a cleaning fluid adheres to the inside wall surface of the upper-side cup parts  24   a,    24   b  to be dried, and that impurities in the used cleaning fluid are accumulated on the inside wall surface of the upper-side cup parts  24   a,    24   b.    
         [0042]     According to the above-mentioned embodiments, the case where this invention is applied to a substrate rotary cleaning apparatus is described. However, the invention may be likewise applied to the other substrate rotation type treatment apparatuses, for example, developers (spin developer), or coaters (spin coater). It is preferable to apply this invention in order to cause the inside wall surface of a cup that is made of a hydrophilic material to be more hydrophilic (making contact angles still smaller). Furthermore, the structure of a cup is not limited to that described in the above-mentioned embodiment.  
         [0043]     While the presently preferred embodiments of the present invention have been shown and described. It is to be understood that these disclosures are for the purpose of illustration and that various changes and modifications may be made without departing from the scope of the invention as set forth in the appended claims.