Abstract:
Methods for cleaning an edge of a semiconductor substrate include providing a brush in a housing, the housing provides a volume for holding the brush. A cleaning fluid is inserted into the housing to at least partially fill the volume holding the brush, with the cleaning fluid. The cleaning fluid is removed from the volume of the housing while the cleaning fluid is being inserted. The brush is rotated within the housing while the cleaning fluid is inserted and removed. The edge of the semiconductor substrate is inserted into a slot of the housing. The edge of the semiconductor substrate inserted into the slot is maintained at a distance and for a period of time. The distance is configured such that the brush contacts the edge of the semiconductor substrate but continues to enable rotation of the brush within the housing.

Description:
CLAIM OF PRIORITY 
       [0001]    This application is a divisional application of U.S. application Ser. No. 11/429,574 entitled “Apparatus for Isolated Bevel Edge Clean and Method for Using the Same” filed on May 5, 2006, which is incorporated herein by reference. 
     
    
     FIELD OF THE INVENTION 
       [0002]    The present invention relates generally to semiconductor substrate processing, and more particularly, to a method and apparatus for cleaning substrate edges before, during and after fabrication operations. 
       DESCRIPTION OF THE RELATED ART 
       [0003]    Semiconductor chip fabrication is a complicated process that involves a coordinated series of fabrication operations. These operations can be broadly characterized to include steps such as layering, patterning, etching, doping, chemical mechanical polishing (CMP), etc. It is well known that during the various steps of these operations, the surfaces, edges, bevels and notches of the semiconductor substrate (wafer) become contaminated with a layer of residue comprised of particulates, organic materials, metallic impurities, etc. There is a need to clean the surface of the substrate of these contaminated particles in order to maximize the yield of contaminant-free chips. 
         [0004]    Some examples of operations that may result in unwanted substrate contamination include plasma etching and CMP. During plasma etching, the substrate is placed in a reaction chamber and exposed to charged plasma which physically or chemically removes layers of material off the substrate surface. After the etching process is complete, a post-etch cleaning step follows whereby contaminant residue deposited on the substrate during the etching process is removed. Typically, this involves the application of chemistry to the front and back surfaces of the substrate followed by rinsing and drying. When using the optimal chemistry and tool settings, this post-etch cleaning step significantly removes or reduces the amount of post-etch contaminant residue on the substrate. 
         [0005]    However, one type of post-etch residue that does not readily lend itself to removal by conventional post-etch chemical-based cleaning methods is organic ‘bevel’ polymer residue found on the substrate bevel edge, notch, and the portion of the backside of the substrate. Bevel polymers have unique properties, in that they are relatively inert and adhere to each other and to the substrate surface with a strong bond that is relatively hard to break. As semiconductor fabricators look towards shrinking the edge exclusion zone of the semiconductor substrate to increase the substrate&#39;s chip yield, it is becoming increasingly important to remove this type of residue. 
         [0006]    Mechanical cleaning tools such as brush scrubbers and edge scrubbers have been used with various degrees of success. Brush scrubbing and edge scrubbing tools use soft materials such as polyvinyl alcohol (TVA&#39;) that are designed to prevent scratching of the substrate surface. These tools are effective at removing some of the contaminants and certain types of residue on the front and back side of the substrate but are not capable of breaking the strong bond of the bevel polymers deposited on the substrate edges and notch. 
         [0007]    In view of the foregoing, there is a need for an apparatus and method for enhancing substrate edge cleaning. 
       SUMMARY 
       [0008]    The present invention fills the need by providing improved methods for cleaning bevel polymer deposited on a substrate edge. It should be appreciated that the present invention can be implemented in numerous ways, including as an apparatus, a system and a method. Several inventive embodiments of the present invention are described below. 
         [0009]    In one embodiment, a method for cleaning an edge of a semiconductor substrate is disclosed. The method includes providing a brush in a housing. The housing provides a volume for holding the brush. A cleaning fluid is inserted into the housing to at least partially fill the volume holding the brush, with the cleaning fluid. The cleaning fluid is removed from the volume of the housing while the cleaning fluid is being inserted. The brush is rotated within the housing while the cleaning fluid is inserted and removed. The edge of the semiconductor substrate is inserted into a slot of the housing. The edge of the semiconductor substrate inserted into the slot is maintained at a distance and for a period of time. The distance is configured such that the brush contacts the edge of the semiconductor substrate but continues to enable rotation of the brush within the housing. 
         [0010]    In another embodiment, a method for cleaning an edge of a semiconductor substrate is disclosed. The method includes providing a brush in a housing. The housing provides a volume for holding the brush. A cleaning fluid is inserted into the housing to at least partially fill the volume holding the brush, with the cleaning fluid. The cleaning fluid is removed from the volume of the housing while the cleaning fluid is being inserted. The brush is rotated within the housing while the cleaning fluid is inserted and removed. The edge of the semiconductor substrate is inserted into a slot of the housing while rotating the semiconductor substrate about a plane. The edge of the semiconductor substrate inserted into the slot is maintained at a distance and for a period of time. The distance is configured such that the brush contacts the edge of the semiconductor substrate but continues to enable rotation of the brush within the housing. 
         [0011]    In yet another embodiment, a method to clean an edge of a substrate is disclosed. The method includes placing the edge of the substrate within an opening defined in a housing. A brush having a plurality of outwardly extending vanes located within the housing is rotated around an axis of rotation such that a portion of the outwardly extending vanes contact the edge of the substrate to clean the edge of the substrate. 
         [0012]    Other advantages of the present invention will become apparent from the following detailed description, taken in conjunction with the accompanying drawings, illustrating the principles of the present invention. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0013]    The invention may best be understood by reference to the following description taken in conjunction with the accompanying drawings. These drawings should not be taken to limit the invention to the preferred embodiments, but are for explanation and understanding only. 
           [0014]      FIG. 1  is a simplified schematic diagram illustrating an edge of a substrate before a cleaning process is applied to the substrate, in accordance with an embodiment of the invention. 
           [0015]      FIG. 2  is a simplified schematic diagram illustrating a substrate with a bristle brush unit received within a notch of the substrate, in accordance with an embodiment of the invention. 
           [0016]      FIG. 3  illustrates a cross-sectional view of a cavity in a housing containing the bristle brush unit, in accordance with an embodiment of the invention. 
           [0017]      FIG. 4A  is a cross-sectional view illustrating a housing with a bristle brush unit contained therein and an upper and a lower drainage channel positioned over and under the bristle brush unit, in accordance with an embodiment of the invention. 
           [0018]      FIG. 4B  is an alternative embodiment to  FIG. 4A  illustrating two upper drainage channels over and a lower drainage channel under the bristle brush unit, in accordance with an embodiment of the invention. 
           [0019]      FIG. 5  illustrates a system with proximity head to introduce a liquid meniscus on a top surface of the substrate in accordance with an embodiment of the invention. 
           [0020]      FIG. 6  illustrates a substrate edge cleaning system in accordance with an embodiment of the invention. 
       
    
    
     DETAILED DESCRIPTION 
       [0021]    Several embodiments for an improved and more effective substrate edge cleaning apparatus, system and method will now be described. It will be obvious, however, to one skilled in the art, that the present invention may be practiced without some or all of these specific details. In other instances, well known process operations have not been described in detail in order not to unnecessarily obscure the present invention. 
         [0022]    Substrate edge cleaning apparatus, systems and methods are very important to the ultimate quality of the resulting semiconductor products, e.g., microchips. In the present invention, the bevel polymers deposited on the substrate edges are treated with mechanical and chemical scrubbing that cuts, tears and removes the bevel polymers from the substrate edge. 
         [0023]    In this document, a substrate is used to refer to a thin slice of a semi-conductor material (usually silicon), from which microchips are made. The substrate can also be a flat panel substrate, which typically takes on a rectangular or square shape. 
         [0024]      FIG. 1  shows a substrate  100  having an edge  101  and a notch  102 . As shown, the bevel polymer  103  forms in the notch  102  and on the outer curvature and back underside curvature of the edge  101  with more concentration on the back underside curvature of the edge  101  of the substrate  100 . This concentration of the bevel polymer  103  is common due to the nature of the fabrication operations and the placement of the substrate  100  in various tools during different stages of the fabrication process. 
         [0025]      FIG. 2  illustrates a simplified schematic diagram of a substrate  100  with the edge  101  and notch  102  of the substrate  100  being placed in contact with a bristle brush unit  200  mounted on a rotating shaft  202 . When rotated around the rotating shaft&#39;s axis, the vanes of the bristle brush unit  200  contacts the substrate  100  to clean the edge  101  and notch  102  of the substrate  100 . Although  FIG. 2  illustrates a single bristle brush unit  200  mounted on the rotating shaft  202 , a plurality of bristle brush units  200  could be mounted on the rotating shaft  202  to cover a wider cleaning area and aid in efficient cleaning. The bristle brush unit  200  efficiently cleans the edge  101  of the substrate  100  and any hard-to-reach areas of the substrate  100 , such as the notch  102 , where the bevel polymer  103  is deposited. 
         [0026]      FIG. 3  illustrates a cross-sectional view of a cavity  210  in a housing  205  containing a bristle brush unit  200 , in an embodiment of the invention. The housing  205  is used to: a) hold the bristle brush unit  200 , and b) receive the edge  101  of the substrate  100  for cleaning. The housing  205  may be made of a chemically resistant material such as PolyVinylidine DiFluoride (commonly marketed as KYNAR), Polytetrafluoroethylene (commonly marketed as TEFLON), Polypropolene, Polyethylene Terephthalate (PET), polyvinyl chloride (PVC), Acrylic, Polyetheretherketone (PEEK), Delrin, Acetal, or Polyphenylene Sulfide (PPS). Other chemically resistant materials may be used so long as the material is compatible with any cleaning chemistries provided herein. The cavity  210  in the housing  205  is a hollow area in which the bristle brush unit  200  is located. The bristle brush unit  200  is oriented so that portions of the outwardly extending vanes (vanes)  201  that make up the bristle brush unit  200  come in contact with the substrate  100  for efficient cleaning. 
         [0027]    As illustrated in  FIG. 3 , the bristle brush unit  200  inside the cavity  210  in the housing  205  is mounted on a rotating shaft  202 . The vanes  201  of the bristle brush unit  200  are placed in contact with the surface of the substrate  100  and as the bristle brush unit  200  rotates, the vanes  201  will hit the underside surface edge of the substrate  100  to forcibly abrade any deposited layer. The bristle brush unit  200  enables the delivery of fluids, such as a cleaning chemistry that aid in substrate edge cleaning. In one embodiment, the bristle brush unit  200 , including the vanes  201 , is made up of a porous material such as nylon with  1  micron alumina impregnated in the nylon. It should be noted that the bristle brush unit  200  is configured within the housing  205  such that the bristle brush unit  200  can be removed and replaced, thus bristle brush unit  200  is a consumable item. 
         [0028]    In one embodiment, an abrasive material is distributed within and throughout the bristle brush unit  200 , including the vanes  201 , to provide greater frictional contact and apply more abrasive force to the bevel polymer  103  on the surface of the substrate  100  during the cleaning process. The distribution of the abrasive material can be random or can be uniform. The amount and nature of abrasive material distributed throughout the bristle brush unit and the vanes  201  may depend on the nature of the bevel polymer deposit and the amount of frictional contact that is needed to scrape the bevel polymer from the edge  101  and notch  102  of the substrate. 
         [0029]    The abrasive material is chosen such that it is capable of removing the bevel polymer  103  from the edge  101  of substrate  100  without scratching or damaging the surface of the substrate  100 . In one embodiment, an abrasive material that has a hardness level greater than the hardness level of the bevel polymer  103  but less than the hardness level of the substrate  100 , is used. Keeping the hardness level of the abrasive material greater than the hardness level of the bevel polymer  103  facilitates in the scrubbing and removal of the bevel polymer  103  from substrate edge  101 . The hardness level of abrasive material, in this embodiment of the invention, is between about 3 Mohs and about 7 Mohs on the Mohs hardness scale. Examples of abrasive material used in this embodiment include titanium oxide (5.5-6.5 Mohs), zirconium oxide (6.5 Mohs), or amorphous silicon oxide (6.5-7 Mohs), and silicon (7 Mohs). In another embodiment, abrasive materials with hardness level greater than the hardness level of the substrate&#39;s surface have been shown to aid in removing bevel polymer without scratching or damaging the surface of the substrate  100 . The hardness level of abrasive material, in this embodiment of the invention, is between about 8 Mohs and 9 Mohs on the Mohs hardness scale. Example of abrasive material used in this embodiment include alumina (8-9 Mohs). 
         [0030]    Referring to  FIG. 3 , in an embodiment of the invention, the vanes  201  of the bristle brush unit  200  are configured with an angle of curvature. In one embodiment, the bristle brush unit  200  is rotated around the axis of rotation defined by the rotating shaft  202  in such a way that the direction of rotation of the bristle brush unit  200  is in a direction opposite to the direction of the angle of curvature of the vanes  201 . Other rotational directions may be implemented as long as the bristle brush unit is capable of making contact with the edge of the substrate  100  and efficiently cleaning the edge of the substrate  100 . It should be appreciated that while the curvature of the vanes  201  and the direction of rotation is specified here, this is not meant to be limiting as any suitable shape of vanes  201  and rotation direction may be applied such that the bevel polymer  103  deposited on the underside surface of the substrate  100  gets cleaned. 
         [0031]    As shown in  FIG. 3 , a fluid distributor channel  301  in the housing  205  introduces cleaning chemistry to the vanes  201 . In this embodiment of the invention, the cleaning chemistry is conducted through the fluid distributor channel  301  and introduced into the cavity  210  and sprayed directly onto the vanes  201  when rotating. In another embodiment of the invention, the fluid distributor channel  301  may be part of the rotating shaft  202  and introduce the cleaning chemistry directly into the bristle brush unit  200  and distributed throughout the vanes  201  while rotating. It should be appreciated that the fluid distributor channel  301  can be positioned anywhere in the housing  205  so long as the function of introducing cleaning chemistry to the vanes  201  of the bristle brush unit  200  is met. The cleaning chemistry introduced into the vanes  201  acts as a lubricant on the surface of the substrate and also assists in the breakdown of bevel polymer  103 . Continuous exposure to the cleaning chemistry along with the abrasive forces provided by the bristle brush unit  200  breaks down the bevel polymer  103  deposited on the surface of the substrate  100 . 
         [0032]    Some examples of cleaning chemistries that may be applied to the substrate edge cleaning process of the present embodiment include about 0.049% to about 49% by weight of Hydrogen fluoride to de-ionized water, about 1% to about 50% by weight of Ammonia to de-ionized water or about 1% to about 100% by weight of one or more amines including Triethlamine, Triethanolamine, Hydroxyethlmorpholine, Hydroxylamine, Dimethylformamide, Dimethylacetamide, Methyldiethanolamine, Diglycolamine, Polymethyldiethylenetriamine to de-ionized water. Ammonia solutions may also contain about 0% to about 50% Ammonium Fluoride or about 0% to about 50% Hydrogen Peroxide. The amine solutions may also include about 0% to about 70% of Catechol, about 0% to about 70% Phenol, about 0% to about 50% Ammonium Fluoride or about 0% to about 10% of Iminodiacetic acid. 
         [0033]    As shown in  FIG. 3 , the cavity  210  inside the housing  205  holding the bristle brush unit  200  further includes a lower drainage channel  303  to receive and remove the chemicals and particles from cleaning. The lower drainage channel  303  is located inside the cavity  210  under the bristle brush unit  200  so that the chemicals and particles released during the cleaning process are directed towards an opening of the lower drainage channel  303  and removed. In an embodiment of the invention, the lower drainage channel  303  is positioned in such a way that the opening of the lower drainage channel  303  inside the cavity  210  is under at least a portion of the bristle brush unit  200  so that the chemicals and particles released during the cleaning process are captured and removed. The lower drainage channel  303  is operatively connected to a vacuum source to allow efficient removal of the particles and chemicals. The lower drainage channel  303  can be positioned anywhere in the housing  205  so long as the function of removing chemicals and particles released during the cleaning from under the bristle brush unit  200  is met. 
         [0034]      FIGS. 4A and 4B  illustrate two variations of a housing with a bristle brush unit  200  contained therein and channels positioned over and under the bristle brush unit. As shown in  FIG. 4A , the cavity  210  inside the housing  205  holding the bristle brush unit  200  further includes an upper drainage channel  401  to receive and remove the chemicals and particles released during cleaning. The upper drainage channel  401  is positioned over the bristle brush unit  200  inside the cavity  210  so that the chemicals and particles released during the cleaning process are directed towards an opening of the upper drainage channel  401  and removed. In an embodiment of the invention, the upper drainage channel  401  is located tangentially over the surface of the substrate to direct the particles and chemicals released during cleaning into the opening of the upper drainage channel  401 . In another embodiment, the upper drainage channel  401  is located inside the cavity  210  over the bristle brush unit  200  such that the opening of the upper drainage channel  401  inside the cavity  210  is over at least a portion of the bristle brush unit  200 . The upper drainage channel  401  is operatively connected to a vacuum source to allow efficient removal of the particles and chemicals. The upper drainage channel  401  can be positioned anywhere in the housing  205  so long as the function of removing the chemicals and particles released during the cleaning process from over the bristle brush unit  200  is met. 
         [0035]      FIG. 4B  illustrates a variation of the housing in  FIG. 4A . As shown in  FIG. 4B , a pair of upper drainage channels  401 A and  401 B are located inside the cavity  210  of the housing  205  and positioned over the bristle brush unit  200  so that the chemicals and particles released during the cleaning process are directed towards an opening in each of the upper drainage channels  401 A and  401 B and removed. The upper drainage channels  401 A and  401 B can be positioned anywhere in the housing  205  so long as the function of removing the chemicals and particles released during the cleaning process from over the bristle brush unit  200  is met. Additional upper drainage channels may be used for effective removal of the chemicals and particles from over the bristle brush unit  200 . 
         [0036]    As illustrated in  FIG. 3  and  FIG. 4A , in an embodiment of the invention, a nozzle  305  is provided to introduce fluids, such as de-ionized water, or gases, such as gaseous nitrogen, onto a top surface of the substrate  100 . The fluids or gases are introduced onto the top surface of the substrate  100  to remove any cleaning chemistry that may make their way on to the top surface of substrate  100  during the cleaning process. In one embodiment, the fluid acts as a fluid curtain to prevent any material from migrating to a top surface of the substrate being cleaned. It should be appreciated that as the substrate is rotating, centrifugal force will assist in the removal of cleaning chemistry from the top surface of the substrate. In an embodiment of the invention, the nozzle  305  maybe used to spray fluids, such as de-ionized water, or gases, such as gaseous nitrogen, onto the top surface of the substrate. Other fluids or gases may also be used to clean the surface of the substrate  100  as long as these fluids or gases are compatible with the top surface of the substrate  100  and the cleaning chemistry used. The nozzle  305  can be placed anywhere in the apparatus so long as it is able to efficiently introduce fluids or gases which assist in the removal of any unwanted chemicals that may make their way onto the top surface of the substrate  100 . It should be appreciated that the liquid or gas acting as a curtain will reduce any possibility of a chemical reaction between the top surface of the substrate and the cleaning chemistry, by preventing any migration of unwanted chemicals from the bevel edge to the top surface. 
         [0037]    An alternative way of reducing the presence of cleaning chemistry on the top surface edge of the substrate  100  is to provide a liquid meniscus barrier at all times during the cleaning process, as illustrated in  FIG. 5 .  FIG. 5  shows the presence of a proximity head  500  over the top surface edge  101  of the substrate  100  in the housing  205  that aids in introducing a liquid meniscus over the immediate top surface edge of the substrate  100 . The location of the proximity head  500  is not constrained to the location illustrated in  FIG. 5 . The proximity head  500  can be located anywhere within the housing  205  so long as it is able to introduce liquid meniscus over the immediate top surface edge of the substrate  100 . In another embodiment of the invention, the proximity head  500  can be located to the side of the surface edge of the substrate  100 . The liquid meniscus provides a continuous barrier over the immediate top surface of the substrate  100  and prevents any cleaning chemistry or other impurities in the form of particles from reaching the top surface edge of the substrate  100 . The meniscus barrier, thus, prevents interaction between the cleaning chemistry and exposed metal lines present on the top of the substrate  100 , thereby reducing damage to the top surface of the substrate  100 . The proximity head  500  includes the capability to continuously introduce liquid, such as de-ionized water, to form a meniscus. A vacuum source to aid in the formation of the meniscus and an optimal drying agent such as isopropylalcohol are also included. The proximity head  500  has been described in detail in other co-pending application of the assignee, referenced below. 
         [0038]    For additional information with respect to the proximity head, reference can be made to an exemplary proximity head, as described in the U.S. Pat. No. 6,616,772, issued on Sep. 9, 2003 and entitled “METHODS FOR WAFER PROXIMITY CLEANING AND DRYING.” This U.S. Patent Application, which is assigned to Lam Research Corporation, the assignee of the subject application, is incorporated herein by reference. 
         [0039]    For additional information about top and bottom menisci, reference can be made to the exemplary meniscus, as disclosed in U.S. patent application Ser. No. 10/330,843, filed on Dec. 24, 2002 and entitled “MENISCUS, VACUUM, IPA VAPOR, DRYING MANIFOLD.” This U.S. Patent Application, which is assigned to Lam Research Corporation, the assignee of the subject application, is incorporated herein by reference. 
         [0040]    For additional information about menisci, reference can be made to U.S. Pat. No. 6,998,327, issued on Jan. 24, 2005 and entitled “METHODS AND SYSTEMS FOR PROCESSING A SUBSTRATE USING A DYNAMIC LIQUID MENISCUS,” and U.S. Pat. No. 6,998,326, issued on Jan. 24, 2005 and entitled “PHOBIC BARRIER MENISCUS SEPARATION AND CONTAINMENT.” These U.S. Patents, which are assigned to the assignee of the subject application, are incorporated herein by reference in their entirety for all purposes. 
         [0041]    For additional information about the proximity vapor clean and dry system, reference can be made to an exemplary system described in the U.S. Pat. No. 6,488,040, issued on Dec. 3, 2002 and entitled “CAPILLARY PROXIMITY HEADS FOR SINGLE WAFER CLEANING AND DRYING.” This U.S. Patent Application, which is assigned to Lam Research Corporation, the assignee of the subject application, is incorporated herein by reference. 
         [0042]      FIG. 6  illustrates an edge cleaning system in one embodiment of the invention. The substrate edge cleaning system, as illustrated in  FIG. 6 , includes a substrate supporting device and a bristle brush applicator. The supporting device is provided to receive and support the substrate on a selected plane. The substrate supporting device includes a pair of drive rollers  602  distributed along the circumference of the substrate  100  to receive the edge  101  of the substrate  100 , in one embodiment of the invention. These drive rollers  602  fit the profile of the substrate edge  101  and assist in spinning the substrate  100  around to expose different areas of the substrate edge  101  to the bristle brush unit  200 . Different configurations and positions for the drive rollers  602  are possible. The drive rollers  602  and the substrate  100  could be rotated along their axes by use of a motor (not shown) or by other mechanical means. 
         [0043]    The substrate supporting device also includes one or more stabilizer wheels  604  distributed along the circumference of the substrate  100 , to stabilize the substrate  100  along the selected plane of rotation during the cleaning process. In this embodiment, a pair of stabilizer wheels  604  has been used. Different configurations and positions for the stabilizer wheels  604  are possible as long as the stabilizer wheels  604  are able to stabilize and maintain the substrate  100  in the selected plane of rotation, during the cleaning process. 
         [0044]    A bristle brush applicator is provided to the underside of the substrate  100 . The bristle brush applicator includes a housing  205  and a bristle brush unit  200  inside a cavity  210  in the housing  205 . As mentioned earlier, the bristle brush unit  200  is made up of a plurality of outwardly extending vanes  201  and mounted on a rotating shaft  202  so that the vanes  201  of the bristle brush unit  200  are in contact with the edge  101  of the substrate  100 . It should be noted that the bristle brush unit  200  is configured within the housing  205  such that the bristle brush unit  200  can be removed and replaced with a newer and fresher bristle brush unit  200 . 
         [0045]    A fluid distributor channel  301  introduces cleaning chemistry into the vanes  201  of the bristle brush unit  200 . In one embodiment, a nozzle  305 , to spray or introduce fluids, such as de-ionized water, or gases, such as gaseous Nitrogen, onto the top surface of the substrate  100 , is provided within the housing  205 . The nozzle  305  is capable of varying the pressure of gases or fluids introduced over the top surface of the substrate  100 . Alternatively, in another embodiment of the invention, a proximity head  500  to introduce liquid meniscus layer over the immediate top surface edge of the substrate  100  is provided. An upper drainage channel  401  positioned over the bristle brush unit  200  and a lower drainage channel  303  positioned under the bristle brush unit  200  and each connected to a vacuum source assist in removing the cleaning chemistry and particles released during the cleaning process from over and under the bristle brush unit  200 . 
         [0046]    Optionally, an underside roller brush  606  is placed in contact with the underside of the substrate  100  to assist in the removal of cleaning chemistry and particles from the underside of the substrate  100 . The underside roller brush  606  is made of a porous material such as PVA. The underside roller brush  606  is rotated around its axis along the under surface of the substrate  100  using a motor (not shown) or some other mechanical means, to assist in the removal of chemicals and particles that settle on the under surface of the substrate  100 . The rotational speed of the underside roller brush  606  can be varied to provide for efficient cleaning of the underside of the substrate  100 . Cleaning chemistry maybe introduced into the underside roller brush  606  using a fluid distributor channel through the underside roller brush  606 . The cleaning chemistry provides the lubrication and assists in the chemical break-down of particles that settle on the underside of the substrate  100 . 
         [0047]    A method to clean an edge  101  of a substrate  100  is explained in great detail in one embodiment, with reference to the system illustrated in  FIG. 6 . In this embodiment, the substrate is received and supported on a supporting device and a bristle brush applicator is applied to the edge  101  of the substrate  100 . The bristle brush applicator includes a housing  205 , to receive the edge  101  of the substrate  100  in a particular plane. The housing also includes a cavity  210  within which a bristle brush unit  200  with outwardly extending vanes (vanes)  201  is received. The bristle brush unit  200  is mounted on a rotating shaft  202  such that the vanes  201  are in contact with the edge  101  of the substrate  100  when the bristle brush applicator is applied to the edge  101  of the substrate  100 . 
         [0048]    The supporting device includes a pair of stabilizer wheels  604  to support the substrate  100  along a selected plane. A pair of drive rollers  602  receives the edge  101  of the substrate  100  and rotates the substrate  100  along the selected plane. A nozzle  305  to spray or introduce fluid or gas onto the top surface of the substrate  100  or a proximity head to introduce a liquid meniscus to the immediate top surface of the substrate is provided. Cleaning chemistry is applied to the vanes  201  of the bristle brush unit  200  through a fluid distributor channel  301 . Applying the cleaning chemistry to the vanes  201  includes introducing the cleaning chemistry through the fluid distributor channel  301  and spraying the cleaning chemistry directly onto the vanes  201  of the bristle brush unit  200 . An alternate way of applying cleaning chemistry to the vanes  201  is by conducting the cleaning chemistry through the fluid distributor channel  301  into the bristle brush unit  200  directly and then distributing it throughout the vanes  201 . The cleaning chemistry assists in lubricating the surface of the substrate  100  and in breaking-down the bevel polymer  103  deposited on the edge of the substrate  100 . 
         [0049]    During the cleaning process, the bristle brush unit  200  is rotated along its axis at a velocity v 1  with the vanes  201  making contact with the edge of the substrate  100  which is rotating at a velocity v 2  along the substrate&#39;s selected plane of rotation. In this embodiment of the invention, the bristle brush unit&#39;s axis of rotation is perpendicular to the surface of the substrate  100 . The stabilizer wheels  604  keep the substrate  100  steady along the selected plane of rotation and drive rollers  602  provide the force for the substrate  100  to rotate along the selected plane. The rotation of substrate  100 , bristle brush unit  200 , drive rollers  602  can be achieved by use of one or more motors (not shown) or by any other mechanical means. 
         [0050]    The cleaning chemistry in the vanes  201  of the bristle brush unit  200  interfaces with the edge  101  of the substrate  100  providing the lubrication to the surface of substrate  100 . Simultaneously, the cleaning chemistry interacts with the bevel polymer  103  on the edge of substrate  100  to cut the bond binding the bevel polymer  103  to the edge  101  of substrate  100 . An abrasive material distributed in the vanes  201  of the bristle brush unit  200  exposed to the edge  101  of the substrate  100  contact the edge of the substrate  100  during rotation and simultaneously works to cut and tear the bevel polymer  103  from the edge  101  of substrate  100 . Continuous exposure to cleaning chemistry weakens the bond binding the bevel polymer  103  to the edge  101  of substrate  100  and the continuous frictional contact of the abrasive material exposed to the edge  101  of the substrate  100  abrades the bevel polymer  103  from the edge  101  of substrate  100  resulting in a substantially or completely bevel-polymer-free substrate edge  101 . The torn bevel polymer  103  along with any cleaning chemistry released during the cleaning process are directed towards the upper and lower drainage channels and suctioned out of the housing  205 . 
         [0051]    Referring to  FIG. 6 , a nozzle  305  is provided to introduce fluids, such as de-ionized water, or gases, such as gaseous nitrogen, using variable pressure onto the top surface of the substrate  100 . The fluids or gases introduced using variable pressure further assist in creating a barrier for the cleaning chemistry and other particle debris thereby preventing the cleaning chemistry and particles from reaching the top surface of the substrate and chemically reacting with the metal lines on the top surface of the substrate  100 . Alternatively, a liquid meniscus is introduced through a proximity head onto the immediate top surface of the substrate  100  creating a liquid barrier. The liquid meniscus prevents any cleaning chemistry and particle debris released during the cleaning process to reach the top surface of the substrate  100 . 
         [0052]    The material used to make the bristle brush unit  200 , including the vanes  201 , maybe porous and formed from materials such as nylon. The abrasive material used in this embodiment are selected from a group consisting of titanium oxide, zirconium oxide, amorphous silicon oxide, silicon and alumina. The cleaning chemistry that may be applied to the substrate include about 0.049% to about 49% by weight of Hydrogen fluoride to de-ionized water, about 1% to about 50% by weight of Ammonia to de-ionized water or about 1% to about 100% by weight of one or more amines including Triethlamine, Triethanolamine, Hydroxyethlmorpholine, Hydroxylamine, Dimethylformamide, Dimethylacetamide, Methyldiethanolamine, Diglycolamine, Polymethyldiethylenetriamine to de-ionized water. Ammonia solutions may also contain about 0% to about 50% Ammonium Fluoride or about 0% to about 50% Hydrogen Peroxide. The amine solutions may also include about 0% to about 70% of Catechol, about 0% to about 70% Phenol, about 0% to about 50% Ammonium Fluoride or about 0% to about 10% of Iminodiacetic acid. The housing  205  may be made of a chemically resistant material such as PolyVinylidine DiFluoride (commonly marketed as KYNAR), Polytetrafluoroethylene (commonly marketed as TEFLON), Polypropolene, Polyethylene Terephthalate (PET), polyvinyl chloride (PVC), Acrylic, Polyetheretherketone (PEEK), Delrin, Acetal, or Polyphenylene Sulfide (PPS). 
         [0053]    The velocity of the bristle brush unit v 1  in one embodiment illustrated in  FIG. 6  is between about 5000 rotations per minute (rpm) to about 20,000 rpm and the velocity of the substrate v 2  along the plane of rotation of the substrate  100  is between about 1 rpm to 20 rpm. The flow rate resulting from the vacuum source in one embodiment of the invention is about 90 standard liters per minute (slm). 
         [0054]    In an alternate embodiment, the substrate  100  is subjected to a cleaning cycle that includes a series of cleaning steps. The system used in this embodiment is similar to the system illustrated in  FIG. 6 . In the first step of the cleaning process in this embodiment, a trimmed underside roller brush  606  is used to remove bevel polymer  103  that was deposited on the under side of the substrate during fabrication process. In this step, the underside roller brush  606  is rotated at a velocity relative to the velocity at which the substrate is rotated along the substrate&#39;s axis of rotation and applied along the underside surface of the substrate  100 . The underside roller brush  606  helps in removing the bevel polymer  103 , chemicals and particles that may have settled on the underside of the substrate  100  during fabrication and cleaning process. The underside roller brush  606  is made of a porous material similar to the bristle brush unit  200  explained earlier. 
         [0055]    In the second step, the substrate is exposed to the bristle brush unit  200  rotating at about 10,000 rotations per minute. As explained earlier, the bristle brush unit  200  in this embodiment, including the vanes  201 , is made of porous material to enable distribution of cleaning chemistry throughout the bristle brush unit  200 . The cleaning chemistry in the bristle brush unit  200  provides the lubrication to the substrate during the cleaning process. The bristle brush unit  200  works on the bevel polymer  103  deposited in the notch and backside edge of the substrate  100 , cuts and releases the bevel polymer  103  from the edge and notch of the substrate  100 . The released bevel polymer, cleaning chemistry and other particles are removed by the upper drainage channel  401  and lower drainage channel  303  provided within the system. 
         [0056]    In the next step, the substrate  100  is then subjected to cleaning using a porous polyurethane impregnated polyester polishing pads such as commercially available SUBA pads from Rodel, Inc. The porosity of the polishing pad enables distribution of cleaning chemistry such as Ammonium Hydroxide throughout the polishing pad. The cleaning chemistry provides the lubrication to the surface of the substrate during the cleaning process and further helps in breaking down the bevel polymer  103  deposited along the edge of the substrate. 
         [0057]    The final step in this cleaning cycle is to remove the chemicals and particles, including bevel polymers  103 , released during the cleaning process. The chemicals and particles are removed from the surface of the substrate using the confinement step. In one embodiment, the chemicals and particles are confined to the underside and edge of the substrate and removed as soon as they are released using an upper drainage channel  401  and lower drainage channel  303  each connected to an external vacuum source. The vacuum source helps in suctioning the chemicals and particles. In this embodiment, the top surface of the substrate is kept dry. The strength of vacuum source can be adjusted depending on the cleaning requirements and on the chemicals and particles released during the cleaning process. 
         [0058]    In an alternative embodiment, a barrier such as gaseous nitrogen or de-ionized water or a liquid meniscus is introduced to the immediate top surface of the substrate. This acts as a curtain and prevents the chemicals and particles released during the cleaning process from making their way to the top surface of the substrate  100 . At the end of this cleaning cycle, the substrate  100  is substantially clean. 
         [0059]    Although the foregoing invention has been described in some detail for purposes of clarity of understanding, it will be apparent that certain changes and modifications can be practiced within the scope of the appended claims. Accordingly, the present embodiments are to be considered as illustrative and not restrictive, and the invention is not to be limited to the details given herein, but may be modified within the scope and equivalents of the appended claims.