Abstract:
An apparatus is provided for scrubbing a substrate&#39;s edge. The apparatus comprises a stationary surface (i.e., a surface that does not rotate in a direction in which the substrate rotates) that is positioned so as to contact an edge (e.g., a circumferential edge, an edge portion of the substrate&#39;s major surface or a beveled surface of the substrate&#39;s edge) such that as the substrate rotates, a dragging force is generated between the stationary surface and the rotating substrate. In a preferred aspect the apparatus is adapted to support a substrate in a generally vertical orientation, and the stationary surface is positioned along a lower portion of the substrate&#39;s edge, such that fluid applied to the major surface of the substrate will flow onto, and thereby rinse, the stationary surface. Such a preferred configuration also may allow a substrate to be loaded and unloaded without needing to move the stationary surface. Preferably, when a substrate is loaded into the scrubbing apparatus, the substrate&#39;s edge will contact the stationary surface, and a separate step for positioning the stationary surface will not be needed.

Description:
[0001]    The present application claims priority from U.S. Provisional Patent Application Serial No. 60/390,765, filed Jun. 21, 2002, which is hereby incorporated by reference herein in its entirety. 
     
    
     
       FIELD OF THE INVENTION  
         [0002]    This invention is concerned with semiconductor manufacturing, and is more particularly concerned with apparatus for scrubbing substrates.  
         BACKGROUND OF THE INVENTION  
         [0003]    Fabrication of semiconductor devices entails performing a sequence of processes with regard to a substrate such as a silicon wafer. One process that may be required is cleaning the substrate to remove particles therefrom. If the particles were not removed, the devices to be formed on the substrate might be damaged by the particles.  
           [0004]    A known type of device for removing particles from a substrate is referred to as a “scrubber”. A conventional scrubber is schematically illustrated in side view in FIG. 1.  
           [0005]    In FIG. 1, reference numeral  11  generally indicates a conventional scrubber. Reference numeral  13  indicates a substrate that is being processed (scrubbed) by the scrubber  11 . The scrubber  11  includes a plurality of rollers  15  that are arranged to support the substrate  13  in a vertical orientation, while rotating the substrate, as indicated by the arrow  17 . The vertically oriented substrate  13  is positioned between two cylindrical brushes (of which only one brush  19  is shown in FIG. 1) which each contact a respective side of the substrate  13 . Each brush  19  is rotated about its longitudinal axis, as indicated by the arrow  21 . A cleaning fluid may be introduced to the surfaces of the substrate  13  via the brushes  19 , or via a spray nozzle (not shown).  
           [0006]    One area in which it is desirable to improve the performance of conventional scrubbers is in the removal of particles from the edge bevel of the substrate.  
         SUMMARY OF THE INVENTION  
         [0007]    An apparatus is provided for scrubbing a substrate&#39;s edge. The apparatus comprises a stationary surface (i.e., a surface that does not rotate in a direction in which the substrate rotates) that is positioned so as to contact an edge (e.g., a circumferential edge, an edge portion of the substrate&#39;s major surface or a beveled surface of the substrate&#39;s edge) such that as the substrate rotates, a dragging force is generated between the stationary surface and the rotating substrate. In a preferred aspect the apparatus is adapted to support a substrate in a generally vertical orientation, and the stationary surface is positioned along a lower portion of the substrate&#39;s edge, such that fluid applied to the major surface of the substrate will flow onto, and thereby rinse, the stationary surface. Such a preferred configuration also may allow a substrate to be loaded and unloaded without needing to move the stationary surface. Preferably, when a substrate is loaded into the scrubbing apparatus, the substrate&#39;s edge will contact the stationary surface, and a separate step for positioning the stationary surface will not be needed. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0008]    [0008]FIG. 1 is a schematic side view of a conventional substrate scrubber;  
         [0009]    [0009]FIG. 2 is a schematic side view of a scrubber provided according to a first aspect of the invention;  
         [0010]    [0010]FIG. 3 is an isometric view of one embodiment of the inventive scrubber of FIG. 2;  
         [0011]    [0011]FIG. 4 is a schematic partial side view of a scrubber provided in accordance with another aspect of the invention;  
         [0012]    [0012]FIG. 5 is a schematic partial top plan view of the inventive scrubber of FIG. 4;  
         [0013]    [0013]FIG. 6 is a cross-sectional view of a substrate, showing the beveled edges of the substrate in juxtaposition with a stationary brush member that is part of the inventive scrubber of FIGS. 4 and 5;  
         [0014]    [0014]FIG. 7 is a side view of an embodiment of the stationary brush member of FIG. 6; and  
         [0015]    [0015]FIG. 8 is a side schematic view of an embodiment of the invention comprising a stationary roller. 
     
    
     DETAILED DESCRIPTION  
       [0016]    In accordance with the invention, the rotary brushes of the conventional scrubber are supplemented by an additional stationary brush member which contacts one or both of the edge bevels of the substrate and applies a brushing action to the edge bevel or edge bevels of the substrate resulting from the rotation of the substrate against the stationary brush member. In this way, removal of particles from the edge bevel is improved.  
         [0017]    [0017]FIG. 2 is a schematic side view, similar to FIG. 1, of a scrubber  23  which is provided in accordance with an aspect of the invention. The inventive scrubber  23  of FIG. 2 may include all of the components of a conventional scrubber, such as those referred to in connection with the conventional scrubber  11  described in connection with FIG. 1. In addition, the inventive scrubber  23  includes a stationary brush arrangement  25  which may include one or more brush members positioned between two of the rollers  15  (e.g., adjacent the bottom of the vertically oriented substrate  13 ) and in contact with one or both of the front and back side edge bevels (not separately shown) of the substrate  13 . The rotation of the substrate  13  results in a scrubbing or dragging action applied to the edge bevel or edge bevels of the substrate  13  by the stationary brush arrangement  25  which is in contact with the edge bevel or bevels.  
         [0018]    It will be understood that when the stationary brush arrangement  25  is employed instead of employing a third substrate support roller  15  (as shown in FIG. 1), the stationary brush arrangement  25  will contact both the front and back side of the edge bevel so as to aid in support of the substrate  13 . The stationary brush arrangement  25  may be adapted to extend along an arc that corresponds to a portion of the substrate  13 &#39;s circumference. In this manner, a larger portion of the substrate&#39;s circumference is scrubbed than that achieved with conventional edge brushes or abrasive support rollers. Further, because the stationary brush arrangement  25  is stationary and does not rotate with the substrate as the substrate rotates, greater dragging force is thereby applied to the substrate. Additionally, when the stationary brush arrangement  25  is positioned below the brushes  19 , fluid applied to the substrate  13  (e.g., via spray nozzles (not shown) or through the brushes  19 ) may flow onto the stationary brush arrangement  25  during substrate cleaning, and thereby rinse particles therefrom. Thus, in a preferred aspect, the conventional need for a dedicated fluid source for cleaning the edge brush mechanism is eliminated. In one aspect, as shown in FIG. 8, the edge cleaning arrangement  25  may comprise a stationary roller  61  (i.e., a roller that remains stationary and does not roll or rotate with the substrate  13 ) having an easily deformable material  63  (such as PVA) positioned along a bottom and/or along the lower edges of the roller groove  65 .  
         [0019]    [0019]FIG. 3 is a partial isometric view of an embodiment of the inventive scrubber  23  of FIG. 2. The conventional rotary brushes  19 , of which one is shown in FIG. 2, are omitted to simplify FIG. 3. However, rotary brush mounts  27  for the rotary brushes are shown. The stationary brush arrangement  25  is constituted, in the embodiment of FIG. 3, by a pair of cylindrical brush members  29 . The brush members  29  may be formed of an easily deformable material such as polyvinyl alcohol (PVA). In one embodiment, each brush member  29  is one-and-a-half inches long and has a diameter of one inch.  
         [0020]    It will be observed that the brush members are mounted at the bottom of the vertically oriented substrate  13 , between the rollers  15  which support the substrate  13 . The brush members  29  are mounted in proximity to each other, such that, when the substrate  13  is supported on the rollers  15 , each of the brush members  29  is in contact with a respective edge bevel of the substrate  13 .  
         [0021]    Each brush member  29  may be mounted on a respective pin  31  coinciding with a longitudinal axis of the respective brush member  29 . Each pin  31  may be mounted in a horizontal orientation, parallel to the plane of the substrate  13 , by a pair of mounting blocks  33 . The mounting arrangement for the brush members  29  may be such that the distance between the pins  31  can be adjusted to adjust a degree of compression imparted to the brush members  29  by the substrate  13  when the substrate  13  is present.  
         [0022]    Although the brush members  29  are stationary during processing (scrubbing) of the substrate  13  by the inventive scrubber  23 , the brush members  29  may be mounted so as to allow rotation thereof (e.g., by hand, when no substrate is present) so that a fresh portion of the brush members  29  may be presented for contact with the substrate  13 .  
         [0023]    As an alternative to maintaining the brush members  29  stationary during scrubbing of the substrate  13 , it is also contemplated to rotate the brush members  29  about pin  21  during scrubbing of the substrate.  
         [0024]    In operation, the substrate  13  is positioned so as to be supported in a vertical orientation on the rollers  15 . The positioning of the substrate  13  on the rollers  15  brings an edge bevel (or both edge bevels as in the embodiment shown in FIG. 3) of the substrate  13  into contact with the stationary brush arrangement  25 . The rotary brushes represented by the brush  19  in FIG. 2 are brought into contact with respective surfaces of the substrate  13 . The substrate  13  is rotated (as indicated by the arrow  17 ) by, e.g., a motor (not shown) coupled to one or more of the rollers  15 . At the same time, the rotary brushes  19  (FIG. 2) are caused to rotate as indicated by the arrow  21 . Scrubbing of the major surfaces of the substrate  13  is performed by action of the rotary brushes  19 . At the same time, a scrubbing action is applied to the edge bevel or edge bevels of the substrate  13  by virtue of the motion of the substrate  13  relative to the stationary brush arrangement  25  which is in contact with the edge bevel or edge bevels of the substrate  13 . Cleaning fluid applied to the substrate  13  via the rotary brushes may flow down the substrate  13  to the stationary brush arrangement  25  (e.g., to the brush members  29 ), and may thereby enhance the scrubbing effect of the stationary brush arrangement  25  upon the edge bevels of the substrate  13 . Because of the interaction of the stationary brush arrangement  25  with the edge bevel or edge bevels of the substrate  13 , superior cleaning of the edge bevel or edge bevels may be achieved.  
         [0025]    Although not shown in the drawings, a mechanism may be provided to direct a jet of fluid to the brush members  29  to rinse particles out of the brush members  29 .  
         [0026]    A scrubber provided in accordance with a second aspect of the invention will now be described with reference to FIGS.  4 - 6 . FIG. 4 is a partial side schematic view of a scrubber  35  provided in accordance with the second aspect of the invention. FIG. 5 is a partial schematic top plan view of the inventive scrubber  35  according to the second aspect of the invention. The inventive scrubber  35  may have all of the components of a conventional scrubber, including those of the conventional scrubber  11  described in conjunction with FIG. 1. However, to simplify the drawings, the rotary brushes represented by the brush  19  in FIG. 1 are not shown in FIGS. 4 and 5.  
         [0027]    The inventive scrubber  35  includes a finger  37  which may be mounted adjacent to the bottom of the substrate  13 . The finger  37  has a first end  39  that extends away from the substrate  13  and a second end  41  which extends toward the substrate  13 . The finger  37  also has a central portion  43  at which the finger  37  is pivotally mounted by means of a pivot  45 . The finger  37  may balance on the pivot  45  in such a manner that the second end  41  of the finger  37  tilts upwardly when the substrate  13  is not present. In addition, or alternatively, a spring or other biasing mechanism (not shown) may be provided to bias the finger  37  such that the second end  41  of the spring  37  tilts upwardly when the substrate  13  is not present.  
         [0028]    A brush member  47  is mounted on the second end of the finger  37  and is adapted to contact the edge bevels of the substrate  13  when the substrate  13  is supported on the rollers  15 . The brush member  47  may, for example, be formed of PVA, or any other easily deformable and suitably low particle material. As shown in FIG. 4, when the inventive scrubber  35  is in operation, the finger  37  may be in a substantially horizontal position.  
         [0029]    [0029]FIG. 6 is a partial cross-sectional view of the substrate  13 , showing the substrate  13  in juxtaposition with the brush member  47 . Edge bevels  49  of the substrate  13  are shown in FIG. 6.  
         [0030]    As shown in FIG. 6, the brush member  47  may have a slotted profile, such as that provided by the V-shaped slot  51  illustrated in FIG. 6. The V-shaped slot  51  includes opposed sides  53 , each of which is adapted to contact a respective one of the edge bevels  49  of the substrate  13 , and is comprised of an easily deformable material such as PVA or any conventional polishing pad material. It will be appreciated that, in practice, the substrate  13  is lowered from the position shown in FIG. 6 so that the edge bevels  49  of the substrate  13  are brought into contact with the opposed sides  53  of the brush member  47 . As the substrate  13  is rotated, the brush member  47  applies a scrubbing action to the edge bevels  49  of the substrate  13  to remove particles from the edge bevels  49 .  
         [0031]    [0031]FIG. 7 is a side view of an embodiment of the brush member  47 . To increase an area of contact between the brush member  47  and the substrate  13  in the circumferential direction of the substrate  13  (thereby improving scrubbing of the substrate  13  by the brush member  47 ), the brush member  47  may be provided with a curved profile, as indicated at  55  in FIG. 7, in the direction of the circumference of the substrate  13 , to substantially conform to the curvature of the substrate  13  in the circumferential direction of the substrate  13 . The curved profile  55  of the brush member  47  may correspond, for example, to substantially 5° of the arc of the substrate  13 . Like the embodiment of FIG. 6, the curved profile of the brush member is comprised of a deformable material such as PVA or any conventional polishing pad material.  
         [0032]    Except for the substitution of the brush member  47  for the brush arrangement  25  of the scrubber  23  of FIGS. 2 and 3, the inventive scrubber  35  of the second aspect of the invention functions in substantially the same manner as the scrubber  23  of FIGS. 2 and 3. Accordingly, operation of the scrubber  35  need not be further described. Like the embodiments of FIGS. 2 and 3, fluid that cleans the substrate  13  may flow therefrom onto the brush member  47  to thereby clean the brush member  47 .  
         [0033]    Instead of being arranged to contact both edge bevels of the substrate  13 , the brush member  47  may be arranged to contact only one of the edge bevels. A respective finger with brush member mounted thereon may be provided for each of the edge bevels of the substrate  13 .  
         [0034]    An amount of force by which the brush member  47  is urged against the edge bevels of the substrate  13  may be adjusted by adjusting a position of a weight (e.g., a screw  57 , FIGS. 4 and 5) that may be carried by the first end  39  of the finger  37 , or by otherwise applying a downward force on the first end  39  of the finger  37 .  
         [0035]    It will be apparent that any of the embodiments described above may be positioned at any location along the edge bevel of the substrate, and may be used to clean a substrate in any orientation (e.g., vertical or horizontally oriented substrates, etc.). It will be apparent that the embodiment of FIGS. 4 and 5 could be easily modified for scrubbing substrates that are positioned in other orientations. For example, when scrubbing a horizontally oriented substrate, the finger mechanism of FIGS. 4 and 5 could be modified so as to pivot about a vertical axis (rather than about a horizontal axis, as shown), to thereby press against the edge bevel of the substrate.  
         [0036]    As used herein a stationary surface refers to a surface that, during cleaning, does not move on the direction the substrate rotates. Such a stationary surface may therefore be moved into and out of contact with the substrate and/or may rotate about an axis perpendicular to the substrate&#39;s axis of rotation.  
         [0037]    Accordingly, while the present invention has been disclosed in connection with exemplary embodiments thereof, it should be understood that other embodiments may fall within the spirit and scope of the invention, as defined by the following claims.