Abstract:
A method and apparatus for cleaning a substrate after chemical mechanical planarizing (CMP) is provided. The apparatus comprises a housing, a substrate holder rotatable on a first axis and configured to retain a substrate in a substantially vertical orientation, a first pad holder having a pad retaining surface facing the substrate holder in a parallel and space apart relation, the first pad holder rotatable on a second axis rotatable parallel to the first axis, a first actuator operable to move the pad holder relative to the substrate holder to change a distance defined between the first axis and the second axis, and a second pad holder disposed in the housing, the second pad holder having a pad retaining surface facing the substrate holder in a parallel and spaced apart relation, wherein the second pad holder is couple with a rotary arm.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application is a divisional of U.S. patent application Ser. No. 14/198,150, filed Mar. 5, 2014, which claims benefit of U.S. Provisional Patent Application Ser. No. 61/794,875, filed Mar. 15, 2013, both of which are herein incorporated by reference in their entirety. 
     
    
     BACKGROUND 
       [0002]    Field 
         [0003]    Implementations of the present invention relate to a method and apparatus for cleaning a substrate after chemical mechanical planarization (CMP). 
         [0004]    Description of the Related Art 
         [0005]    In the process of fabricating modern semiconductor integrated circuits (ICs), planarizing surfaces prior to depositing subsequent layers is often necessary to ensure accurate formation of photoresist masks and to maintain stack tolerances. One method for planarizing a layer during IC fabrication is chemical mechanical planarizing (CMP). In general, CMP involves the relative movement of the substrate held in a polishing head against a polishing material to remove surface irregularities from the substrate. In a CMP process, the polishing material is wetted with a polishing fluid that may contain at least one of an abrasive or chemical polishing composition. This process may be electrically assisted to electrochemically planarize conductive material on the substrate. 
         [0006]    Planarizing hard materials such as oxides typically requires that the polishing fluid or the polishing material itself include abrasives. As the abrasives often cling or become partially embedded in the layer of material being polished, the substrate is processed on a buffing module to remove the abrasives from the polished layer. The buffing module removes the abrasives and polishing fluid used during the CMP process by moving the substrate, which is still retained in the polishing head against a buffing material in the presence of deionized water or chemical solutions. The buffing module is substantially identical to the CMP module except for the polishing fluids utilized and the material on which the substrate is processed. 
         [0007]    Once buffed, the substrate is transferred to a series of cleaning modules that further remove any remaining abrasive particles and/or other contaminants that cling to the substrate after the planarizing and buffing process before they can harden on the substrate and create defects. The cleaning modules may include, for example, a megasonic cleaner, a scrubber or scrubbers, and a dryer. The cleaning modules that support the substrates in a vertical orientation are especially advantageous, as they also utilize gravity to enhance removal of particles during the cleaning process, and are also typically more compact. 
         [0008]    Although present CMP processes have been shown to be robust and reliable systems, the configuration of the system equipment requires the buffing module to utilize critical space, which could alternatively be utilized for additional CMP modules. However, certain polishing fluids, for example those using cerium oxide, are particularly difficult to remove and conventionally require processing the substrate in buffing module before transferring the substrate to the cleaning module as conventional cleaning modules have not demonstrated the ability to satisfactorily remove abrasive particles from oxide surfaces that have not been buffed prior to cleaning. 
         [0009]    Therefore, there is a need in the art for an improved CMP process and cleaning module. 
       SUMMARY 
       [0010]    Implementations of the present invention relate to a method and apparatus for cleaning a substrate after chemical mechanical planarizing (CMP). In one implementation, a particle cleaning module is provided. The particle cleaning module comprises a housing, a substrate holder disposed in the housing, the substrate holder configured to retain a substrate in a substantially vertical orientation, the substrate holder rotatable on a first axis, a first pad holder disposed in the housing, the first pad holder having a pad retaining surface facing the substrate holder in a parallel and space apart relation, the first pad holder rotatable on a second axis rotatable parallel to the first axis, a first actuator operable to move the first pad holder relative to the substrate holder to change a distance defined between the first axis and the second axis, and a second pad holder disposed in the housing, the second pad holder having a pad retaining surface facing the substrate holder in a parallel and spaced apart relation, the second pad holder rotatable on a third axis parallel to the first axis and the second axis. 
         [0011]    In one implementation, a particle cleaning module is provided. The particle cleaning module comprises a housing, a substrate holder disposed in the housing, a first pad holder disposed in the housing, a second pad holder disposed in the housing, and a rotary arm assembly. The substrate holder is configured to retain a substrate in a substantially vertical orientation with the substrate holder rotatable on a first axis. The first pad holder has a pad retaining surface facing the substrate holder in a parallel and spaced apart relation, the first pad holder rotatable on a second axis rotatable parallel to the first axis. A first actuator is operable to move the first pad holder relative to the substrate holder to change a distance defined between the first axis and the second axis. The second pad holder has a pad retaining surface facing the substrate holder in a parallel and spaced apart relation, the second pad holder rotatable on a third axis parallel to the first axis and the second axis. The rotary arm assembly comprises a rotary arm coupled with the second pad holder and operable for sweeping the second pad holder across the surface of the substrate and a lateral actuator mechanism form moving the rotary arm toward the substrate. 
         [0012]    In another implementation, a method for cleaning a substrate is provided. The method comprises spinning a substrate disposed in a vertical orientation, providing a cleaning fluid to a surface of the spinning substrate, pressing a first pad against the spinning substrate, moving the first pad laterally across the substrate, providing a polishing fluid to an edge portion of the spinning substrate, pressing a second pad against the spinning substrate, and moving the second pad laterally across the edge of the substrate. Pressing the first pad against the spinning substrate may further comprise spinning the first pad. Pressing the first pad against the spinning substrate may further comprise spinning the first pad. The method may further comprise placing the substrate in a megasonic cleaning module prior to moving the first pad laterally across the substrate, placing the substrate in one or more brush modules after moving the second pad laterally across the edge of the substrate and placing the substrate in dryer after placing the substrate in the one or more brush modules. The method may further comprise planarizing a surface of the substrate prior to placing the substrate in the megasonic cleaning module. The method may further comprise providing the cleaning fluid to the substrate after moving the first pad laterally across the substrate and prior to placing the substrate in the one or more brush modules. 
         [0013]    In yet another implementation, a method for cleaning a substrate is provided. The method comprises spinning a substrate disposed in a vertical orientation, providing a cleaning fluid to a surface of the spinning substrate, pressing a first pad against the spinning substrate, moving the first pad across the substrate along a curved path, providing a polishing fluid to an exclusion region and/or edge portion of the spinning substrate, pressing a second pad against the spinning substrate and moving the second pad laterally across the edge of the substrate. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0014]    So that the manner in which the above recited features of the present invention can be understood in detail, a more particular description of the invention, briefly summarized above, may be had by reference to implementations, some of which are illustrated in the appended drawings. It is to be noted, however, that the appended drawings illustrate only typical implementations of this invention and are therefore not to be considered limiting of its scope, for the invention may admit to other equally effective implementations. 
           [0015]      FIG. 1  is a schematic illustration of a cross-section of a portion of a substrate; 
           [0016]      FIG. 2  illustrates a top view of a semiconductor substrate chemical mechanical planarization system having a cleaning system which includes one implementation of a particle cleaning module according to implementations described herein; 
           [0017]      FIG. 3  is a front view of cleaning system depicted in  FIG. 2  according to implementations described herein; 
           [0018]      FIG. 4  is a cross-sectional view of the particle cleaning module depicted in  FIG. 2  according to implementations described herein; 
           [0019]      FIG. 5  is a cross-sectional view of the particle cleaning module taken along the section line  5 - 5  of  FIG. 4  according to implementations described herein; 
           [0020]      FIG. 6  is a cross-sectional view of the particle cleaning module taken along the section line  6 - 6  of  FIG. 4  according to implementations described herein; 
           [0021]      FIG. 7  is a top view of a pad holder engaging a pad with a substrate retained by the substrate holder within the particle cleaning module of  FIG. 2  according to implementations described herein; 
           [0022]      FIG. 8  is a top schematic view of the particle cleaning module having a pad conditioning assembly disposed therein; 
           [0023]      FIGS. 9A-9C  are schematic views of the disk pad holder according to implementations described herein; 
           [0024]      FIGS. 10A-10D  are schematic view of the disk pad holder according to implementations described herein; 
           [0025]      FIG. 11  is a schematic cross-sectional view of another implementation of a particle cleaning module according to implementations described herein; 
           [0026]      FIG. 12  is a cross-sectional schematic view of another implementation of a disk pad holder according to implementations described herein; 
           [0027]      FIG. 13  is another schematic view of the particle cleaning module of  FIG. 11  according to implementations described herein; 
           [0028]      FIG. 14  is another schematic view of the particle cleaning module of  FIG. 11  according to implementations described herein; 
           [0029]      FIG. 15  is a schematic view of a portion of a particle cleaning module illustrating another implementation of a pad conditioning assembly according to implementations described herein; and 
           [0030]      FIG. 16  is a schematic view of another implementation of an edge pad polishing assembly according to implementations described herein. 
       
    
    
       [0031]    To facilitate understanding, identical reference numerals have been used, wherever possible, to designate identical elements that are common to the Figures. Additionally, elements of one implementation may be advantageously adapted for utilization in other implementations described herein. 
       DETAILED DESCRIPTION 
       [0032]    Implementations of the present invention relate to a method and apparatus for cleaning a substrate after chemical mechanical planarizing (CMP). More specifically implementations of the present invention provide improved methods and apparatus for cleaning and/or polishing the exclusion region and/or edge of a substrate. Abrasive particles (e.g., cerium oxide (CeO)) used in oxide CMP are difficult to remove using traditional PVA brush scrubbing and often require performance of a buffing process on an additional platen on the polishing tool. However even with buffing on the polishing platen particles at the wafer edge (e.g. 2 mm) are very difficult to remove. 
         [0033]    Certain implementations described herein provide a clean process where slurry polishing is performed at the exclusion region and/or edge of a wafer after particle cleaning. Certain implementations of the current invention provide an apparatus where a slurry polishing process at the exclusion region and/or edge of a wafer is implemented without affecting the polishing performance in the device area. The apparatus, described below as a particle cleaning module, advantageously allows for increased utilization and throughput of the CMP system, while reducing the amount and cost of consumables needed to effectively clean a substrate as further described below. 
         [0034]    The particle cleaning module has a wafer chuck, which may support a full wafer size and a disk brush holder with a diameter of less than 50 mm. The wafer chuck speed may be more than 500 rpm and the disk brush holder speed may be more than 1000 rpm. A soft pad, such as politex type material, may be used as a cleaning pad. The cleaning pad may be adhered on top of the disk brush holder with a pressure sensitive adhesive. During the cleaning process, the wafer is rotated by the wafer chuck and the disk brush with the soft pad rotates and sweeps from the center of the wafer to the edge of the wafer or vice versa. The contact pressure and/or gap between the soft pad and the wafer may be controlled by a linear motor. This motion may be repeated several times until the abrasive particles are removed from most of the wafer surface, except the wafer edge at ≦2 mm edge exclusion. Afterward, a polishing step is performed where a polishing pad is moved to the edge of the wafer and the slurry is delivered next to the polishing pad where the wafer and the pad are rotated and contacted during the polishing. It is desirable to have the polishing pad only polish the exclusion region and/or edge region without touching the device region. The polishing pad may rotate at high speed as well as sweep back and forth at the edge of the wafer. In certain implementations it desirable to have separate pads, a first pad for removing particles from the surface of the wafer and a second pad for polishing at the wafer edge where a local slurry is delivered. 
         [0035]    In certain implementations, the particle cleaning module uses a rotary arm in place of the lateral linear motion design. The Disk/Pad/Fluid Jet module design uses the rotary arm motion concept to control the Disk/Pad/Fluid Jet to scan on the wafer surface. By using the rotary arm motion design, the processing tank sealing and servicing is easier and production costs are cheaper than the current lateral linear motion Disk/Pad/Fluid Jet design. 
         [0036]    In certain implementations, the particle cleaning module design provides a common design layout for multi-wafer processing. For example, by replacing the Disk, Pad or Fluid Jet, it can perform many kinds of wafer cleaning processes in this common module. The particle cleaning module also provides a flexible edge clean disk/pad for wafer edge cleaning and wafer bevel cleaning. The Disk/Pad/Fluid Jet may be moved in and out to control the processing force and distance to wafer surface. The Disk/Pad clean pressure force on the wafer may be set from 0˜5 Lb. Further, the wafer vacuum chuck design provides full wafer support for higher Disk/Pad processing force. The wafer gripper design provides wafer edge-contact for both sides of the wafer (front and back) during processing and rinsing. 
         [0037]    Implementations described herein will be described below in reference to a planarizing process and composition that can be carried out using chemical mechanical polishing process equipment, such as MIRRA™, MIRRA MESA™, REFLEXION®, REFLEXION LK™, and REFLEXION® GT™ chemical mechanical planarizing systems, available from Applied Materials, Inc. of Santa Clara, Calif. Other planarizing modules, including those that use processing pads, planarizing webs, or a combination thereof, and those that move a substrate relative to a planarizing surface in a rotational, linear, or other planar motion may also be adapted to benefit from the implementations described herein. In addition, any system enabling chemical mechanical polishing using the methods or compositions described herein can be used to advantage. The following apparatus description is illustrative and should not be construed or interpreted as limiting the scope of the implementations described herein. 
         [0038]      FIG. 1  is a schematic illustration of a cross-section of a portion of a substrate  100 . With reference to  FIG. 1 , a substrate  100  may include two major surfaces  102   a ,  102   b  and an edge  104 . Each major surface  102   a ,  102   b  of the substrate  100  may include a device region  106   a ,  106   b  and an exclusion region  108   a ,  108   b . (Typically however, only one of the two major surfaces  102   a ,  102   b  will include a device region and an exclusion region.) The exclusion regions  108   a ,  108   b  may serve as buffers between the device regions  106   a ,  106   b  and the edge  104 . The edge  104  of a substrate  100  may include an outer edge  110  and bevels  112 ,  114 . The bevels  112 ,  114  may be located between the outer edge  110  and the exclusion regions  108   a ,  108   b  of the two major surfaces  102   a ,  102   b . The present invention is adapted to clean and/or polish the outer edge  110  and at least one bevel  112 ,  114  of a substrate  100  without affecting the device regions  106   a ,  106   b . In some implementations, all or part of the exclusion regions  108   a ,  108   b  may be cleaned or polished as well. 
         [0039]      FIG. 2  illustrates a top view of a semiconductor substrate chemical mechanical planarization (CMP) system  200  having a cleaning system  216  that includes one implementation of a particle cleaning module  282  of the present invention. Although the exemplary configurations are provided for the CMP system  200  and cleaning system  216  in  FIG. 2 , it is contemplated that implementations of the particle cleaning module  282  of the present invention may be utilized alone, or with cleaning systems having alternative configurations and/or CMP systems having alternative configurations. 
         [0040]    In addition to the cleaning system  216 , the exemplary CMP system  200  generally includes a factory interface  202 , a loading robot  204 , and a planarizing module  206 . The loading robot  204  is disposed proximate the factory interface  202  and the planarizing module  206  to facilitate the transfer of substrates  100  therebetween. 
         [0041]    A controller  208  is provided to facilitate control and integration of the modules of the CMP system  200 . The controller  208  comprises a central processing unit (CPU)  210 , a memory  212  and support circuits  214 . The controller  208  is coupled to the various components of the CMP system  200  to facilitate control of, for example, the planarizing cleaning and transfer processes. 
         [0042]    The factory interface  202  generally includes an interface robot  220  and one or more substrate cassettes  218 . The interface robot  220  is employed to transfer substrates  100  between the substrate cassettes  218 , the cleaning system  216  and an input module  224 . The input module  224  is positioned to facilitate transfer of substrates  100  between the planarizing module  206  and the factory interface  202  as will be further described below. 
         [0043]    Optionally, polished substrates exiting the cleaning system  216  may be tested in a metrology system  280  disposed in the factory interface  202 . The metrology system  280  may include an optical measuring device, such as the NovaScan 420, available from Nova Measuring Instruments, Inc. located in Sunnyvale, Calif. The metrology system  280  may include a buffer station (not shown) for facilitating entry and egress of substrates from the optical measuring device or other metrology device. One such suitable buffer is described in U.S. Pat. No. 6,244,931, issued Jun. 12, 2001 to Pinson, et al. 
         [0044]    The planarizing module  206  includes at least one CMP station. It is contemplated that the CMP station maybe configured as an electrochemical mechanical planarizing station. In the implementation depicted in  FIG. 2 , the planarizing module  206  includes a plurality of CMP stations, illustrated as a first station  228 , a second station  230  and a third station  232  disposed in an environmentally controlled enclosure  288 . The first station  228  includes a conventional CMP station configured to perform an oxide planarization process utilizing an abrasive containing polishing fluid. It is contemplated that CMP processes to planarized other materials may be alternatively performed, including the use of other types of polishing fluids. As the CMP process is conventional in nature, further description thereof has been omitted for the sake of brevity. The second station  230  and the third station  232  will be discussed in detail further below. 
         [0045]    The exemplary planarizing module  206  also includes a transfer station  236  and a carousel  234  that are disposed on an upper or first side  238  of a machine base  240 . In one implementation, the transfer station  236  includes an input buffer station  242 , an output buffer station  244 , a transfer robot  246  and a load cup assembly  248 . The loading robot  204  is configured to retrieve substrates from the input module  224  and transfer the substrates to the input buffer station  242 . The loading robot  204  is also utilized to return polished substrates from the output buffer station  244  to the input module  224 , from where the polished substrates are then advanced through the cleaning system  216  prior to being returned to the substrate cassettes  218  coupled to the factory interface  202  by the interface robot  220 . The transfer robot  246  is utilized to move substrates between the buffer stations  242 ,  244  and the load cup assembly  248 . 
         [0046]    In one implementation, the transfer robot  246  includes two gripper assemblies, each having pneumatic gripper fingers that hold the substrate by the substrate&#39;s edge. The transfer robot  246  may simultaneously transfer a substrate to be processed from the input buffer station  242  to the load cup assembly  248  while transferring a processed substrate from the load cup assembly  248  to the output buffer station  244 . An example of a transfer station that may be used to advantage is described in U.S. Pat. No. 6,156,124, issued Dec. 5, 2000 to Tobin. 
         [0047]    The carousel  234  is centrally disposed on the machine base  240 . The carousel  234  typically includes a plurality of arms  250 , each supporting a polishing head assembly  252 . Two of the arms  250  depicted in  FIG. 2  are shown in phantom such that a planarizing surface of a polishing pad  226  of the first station  228  and the transfer station  236  may be seen. The carousel  234  is indexable such that the polishing head assemblies  252  may be moved between the planarizing stations  228 ,  230 ,  232  and the transfer station  236 . One carousel that may be utilized to advantage is described in U.S. Pat. No. 5,804,507, issued Sep. 8, 1998 to Perlov, et al. 
         [0048]    The cleaning system  216  removes polishing debris, abrasives, polishing fluid, and/or excess deposited material from the polished substrates that remains after polishing. The cleaning system  216  includes a plurality of cleaning modules  260 , a substrate handler  266 , a dryer  262  and an output module  256 . The substrate handler  266  retrieves a processed substrate  100  returning from the planarizing module  206  from the input module  224  and transfers the substrate  100  through the plurality of cleaning modules  260  and dryer  262 . The dryer  262  dries substrates exiting the cleaning system  216  and facilitates substrate transfer between the cleaning system  216  and the factory interface  202  by the interface robot  220 . The dryer  262  may be a spin-rinse-dryer or other suitable dryer. One example of a suitable dryer  262  may be found as part of the MESA™ or Desica® Substrate Cleaners, both available from Applied Materials, Inc., of Santa Clara, Calif. 
         [0049]    In the implementation depicted in  FIG. 2 , the cleaning modules  260  utilized in the cleaning system  216  include a megasonic clearing module  264 A, the particle cleaning module  282 , a first brush module  264 B and a second brush module  264 C. However, it is to be appreciated that the particle cleaning module  282  of the present invention may be used with cleaning systems incorporating one or more modules having one or more types of modules. Each of the cleaning modules  260  is configured to process a vertically oriented substrate, i.e., one in which the polished surface is in a substantially vertical plane. The vertical plane is represented by the Y-axis, which is perpendicular to the X-axis and Z-axis shown in  FIG. 2 . The particle cleaning module  282  is discussed in detail further below with reference to  FIG. 4 . 
         [0050]    In operation, the CMP system  200  is initiated with the substrate  100  being transferred from one of the substrate cassettes  218  to the input module  224  by the interface robot  220 . The loading robot  204  then moves the substrate from the input module  224  to the transfer station  236  of the planarizing module  206 . The substrate  100  is loaded into the polishing head assembly  252  moved over and polished against the polishing pad  226  while in a horizontal orientation. Once the substrate is polished, polished substrates  100  are returned to the transfer station  236  from where the loading robot  204  may transfer the substrate  100  from the planarizing module  206  to the input module  224  while rotating the substrate to a vertical orientation. The substrate handler  266  then retrieves the substrate from the input module  224  transfers the substrate through the cleaning modules  260  of the cleaning system  216 . Each of the cleaning modules  260  is adapted to support a substrate in a vertical orientation throughout the cleaning process. Once cleaned, the cleaned substrate  100  is to the output module  256 . The cleaned substrate  100  is returned to one of the substrate cassettes  218  by the interface robot  220  while returning the cleaned substrate  100  to a horizontal orientation. Optionally, the interface robot  220  may transfer the cleaned substrate to the metrology system  280  prior to the substrate&#39;s return to one of the substrate cassettes  218 . 
         [0051]    Although any suitable substrate handler may be utilized, the substrate handler  266  depicted in  FIG. 2  includes a robot  268  having at least one substrate gripper (two substrate grippers  274 ,  276  are shown) that is configured to transfer substrates between the input module  224 , the cleaning modules  260  and the dryer  262 . Optionally, the substrate handler  266  may include a second robot (not shown) configured to transfer the substrate between the last cleaning module  260  and the dryer  262  to reduce cross contamination. 
         [0052]    In the implementation depicted in  FIG. 2 , the substrate handler  266  includes a rail  272  coupled to a partition  258  separating the substrate cassettes  218  and interface robot  220  from the cleaning system  216 . The robot  268  is configured to move laterally along the rail  272  to facilitate access to the cleaning modules  260 , dryer  262  and the input and output modules  224 ,  256 . 
         [0053]      FIG. 3  depicts a front view of the substrate handler  266  according to one implementation of the invention. The robot  268  of the substrate handler  266  includes a carriage  302 , a mounting plate  304  and the substrate grippers  274 ,  276 . The carriage  302  is slidably mounted on the rail  272  and is driven horizontally by an actuator  306  along a first axis of motion A 1  defined by the rail  272  which is parallel to the Z-axis. The actuator  306  includes a motor  308  coupled to a belt  310 . The carriage  302  is attached to the belt  310 . As the motor  308  advances the belt  310  around the sheave  312  positioned at one end of the cleaning system  216 , the carriage  302  moves along the rail  272  to selectively position the robot  268 . The motor  308  may include an encoder (not shown) to assist in accurately positioning the robot  268  over the input and output modules  224 ,  256  and the various cleaning modules  260 . Alternatively, the actuator  306  may be any form of a rotary or linear actuator capable of controlling the position of the carriage  302  along the rail  272 . In one implementation, the carriage  302  is driven by a linear actuator having a belt drive, such as the GL15B linear actuator commercially available from THK Co., Ltd. located in Tokyo, Japan. 
         [0054]    The mounting plate  304  is coupled to the carriage first  302 . The mounting plate  304  includes at least two parallel tracks  316 A-B along which the positions of the substrate grippers  274 ,  276  are independently actuated along a second and third axes of motion A 2 , A 3 . The second and third axes of motion A 2 , A 3  are oriented perpendicular to the first axis A 1  and are parallel to the Y-axis. 
         [0055]      FIG. 4  depicts a cross-sectional view of the particle cleaning module  282  of  FIG. 2 . The particle cleaning module  282  includes a housing  402 , a substrate rotation assembly  404 , a first pad actuation assembly  406  and a second pad actuation assembly  470 . Although a first pad actuation assembly  406  and a second pad actuation assembly  470  are shown, it should be understood that the implementations described herein may be performed with a single pad actuation assembly. For example, the first pad actuation assembly  406  and the second pad actuation assembly  470  may be positioned in separate housings. The housing  402  includes an opening  408  at a top of the housing and a substrate receiver  410  at a bottom  418  of the housing. A drain  468  is formed through the bottom  418  of the housing  402  to allow fluids to be removed from the housing  402 . The opening  408  allows the robot  268  (not shown in  FIG. 4 ) to vertically transfer the substrate to an internal volume  412  defined within the housing  402 . The housing  402  may optionally include a lid  430  that can open and close to allow the robot  268  in and out of the housing  402 . 
         [0056]    The substrate receiver  410  has a substrate receiving slot  432  facing upwards parallel to the Y-axis. The substrate receiving slot  432  is sized to accept the perimeter of the substrate  100 , thereby allowing the one of the substrate grippers  274 ,  276  of the substrate handler  266  to place the substrate  100  in the substrate receiving slot  432  in a substantially vertical orientation. The substrate receiver  410  is coupled to a Z-Y actuator  411 . The Z-Y actuator  411  may be actuated to move the substrate receiver  410  upwards in the Y-axis to align a centerline of the substrate  100  disposed in the substrate receiver  410  with a centerline of the substrate rotation assembly  404 . Once the centerline of the substrate  100  is aligned with the centerline of the substrate rotation assembly  404 , the Z-Y actuator  411  may be actuated to move the substrate receiver  410  in the Z-axis to contact the substrate  100  against the substrate rotation assembly  404 , which then actuates to chuck the substrate  100  to the substrate rotation assembly  404 . After the substrate  100  has been chucked to the substrate rotation assembly  404 , the Z-Y actuator  411  may be actuated to move the substrate receiver  410  in the Y-axis clear of the substrate  100  and the substrate rotation assembly  404  so that the substrate  100  held by the substrate rotation assembly  404  may be rotated without contacting the substrate receiver  410 . 
         [0057]    The substrate rotation assembly  404  is disposed in the housing  402  and includes a substrate holder  414  coupled to a substrate rotation mechanism  416 . The substrate holder  414  may be an electrostatic chuck, a vacuum chuck, a mechanical gripper or any other suitable mechanism for securely holding the substrate  100  while the substrate is rotated during processing within the particle cleaning module  282 . Preferably, the substrate holder  414  is either an electrostatic chuck or a vacuum chuck. 
         [0058]      FIG. 5  is a cross-sectional view of the particle cleaning module  282  taken along the section line  5 - 5  of  FIG. 4  thus illustrating a face  504  of the substrate holder  414 . Referring to both  FIG. 4  and  FIG. 5 , the face  504  of the substrate holder  414  includes one or more apertures  502  fluidly coupled to a vacuum source  497 . The vacuum source  497  is operable to apply a vacuum between the substrate  100  and the substrate holder  414 , thereby securing the substrate  100  and the substrate holder  414 . Once the substrate  100  is held by the substrate holder  414 , the substrate receiver  410  moves downward in a vertical direction parallel to the Y-axis towards the bottom  418  of the housing  402  to be clear of the substrate, as seen in  FIG. 5 . The substrate receiver  410  may move in a horizontal direction towards an edge  420  of the housing  402  to be further clear of the substrate. 
         [0059]    The substrate holder  414  is coupled to the substrate rotation mechanism  416  by a first shaft  423  that extends through a hole  424  formed through the housing  402 . The hole  424  may optionally include sealing members  426  to provide a seal between the first shaft  423  and the housing  402 . The substrate holder  414  is controllably rotated by the substrate rotation mechanism  416 . The substrate rotation mechanism  416  may be an electrical motor, an air motor, or any other motor suitable for rotating the substrate holder  414  and substrate  100  chucked thereto. The substrate rotation mechanism  416  is coupled to the controller  208 . In operation, the substrate rotation mechanism  416  rotates the first shaft  423 , which rotates the substrate holder  414  and the substrate  100  secured thereto. In one implementation the substrate rotation mechanism  416  rotates the substrate holder  414  (and substrate  100 ) at a rate of at least 500 revolutions per minute (rpm). 
         [0060]    The first pad actuation assembly  406  includes a pad rotation mechanism  436 , a pad cleaning head  438 , and a lateral actuator mechanism  442 . The pad cleaning head  438  is located in the internal volume  412  of the housing  402  and includes a first pad holder  434  that holds a pad  444  and a fluid delivery nozzle  450 . The fluid delivery nozzle  450  is coupled to a fluid delivery source  498  that provides deionized water, a chemical solution or any other suitable fluid to the pad  444  during cleaning the substrate  100 . The lid  430  may be moved to a position that closes the opening  408  of the housing  402  above the fluid delivery nozzle  450  to prevent fluids from being spun out of the housing  402  during processing. 
         [0061]    A centerline of the first pad holder  434  may be aligned with the centerline of the substrate holder  414 . The first pad holder  434  (and pad  444 ) has a diameter much less than that of the substrate  100 , for example at least less than half the diameter of the substrate or even as much as less than about one eighth the diameter of the substrate. In one implementation, the first pad holder  434  (and pad  444 ) may have a diameter of less than about 25 mm. The first pad holder  434  may holds the pad  444  utilizing clamps, vacuum, adhesive or other suitable technique that allows for the pad  444  to periodically be replaced as the pad  444  becomes worn after cleaning a number of substrates  100 . 
         [0062]    The pad  444  may be fabricated from a polymer material, such as porous rubber, polyurethane and the like, for example, a POLYTEX™ pad available from Rodel, Inc. of Newark, Del. In one implementation, the pad holder  434  may be used to a hold a brush or any other suitable cleaning device. The first pad holder  434  is coupled to the pad rotation mechanism  436  by a second shaft  446 . The second shaft  446  is oriented parallel to the Z-axis and extends from the internal volume  412  through an elongated slit formed through the housing  402  to the pad rotation mechanism  436 . The pad rotation mechanism  436  may be an electrical motor, an air motor, or any other suitable motor for rotating the first pad holder  434  and pad  444  against the substrate. The pad rotation mechanism  436  is coupled to the controller  208 . In one implementation, the pad rotation mechanism  436  rotates the first pad holder  434  (and pad  444 ) at a rate of at least about 1000 rpm. 
         [0063]    The pad rotation mechanism  436  is coupled to bracket  454  by an axial actuator  440 . The axial actuator  440  is coupled to the controller  208  or other suitable controller and is operable to move the first pad holder  434  along the Z-axis to move the pad  444  against and clear of the substrate  100  held by the substrate holder  414 . The axial actuator  440  may be a pancake cylinder, linear actuator or any other suitable mechanism for moving the first pad holder  434  in a direction parallel to the Z-axis. In operation, after the substrate holder  414  is in contact with and holding the substrate, the axial actuator  440  drives the first pad holder  434  in a z-direction to make contact with the substrate  100 . 
         [0064]    The bracket  454  is coupled to a base  462  by the lateral actuator mechanism  442  by a carriage  456  and rail  458  that allows the pad cleaning head  438  to move laterally in a direction parallel to the X-axis, as depicted in  FIG. 6 . The carriage  456  is slidably mounted on the rail  458  and is driven horizontally by the lateral actuator mechanism  442  to scan the pad  444  across the substrate  100 . The lateral actuator mechanism  442  may be a lead screw, a linear actuator or any other suitable mechanism for moving the pad cleaning head  438  horizontally. The lateral actuator mechanism  442  is coupled to controller  208  or other suitable controller. 
         [0065]    The second pad actuation assembly  470  includes a pad rotation mechanism  472 , a pad polishing head  474 , and a lateral actuator mechanism  476 . The pad polishing head  474  is located in the internal volume  412  of the housing  402  and includes a second pad holder  478  that holds a polishing pad  480  and a fluid delivery nozzle  482 . The fluid delivery nozzle  450  is coupled to a fluid delivery source  484  that provides polishing slurry, deionized water, a chemical solution or any other suitable fluid to the polishing pad  480  during polishing of the exclusion region and/or edge region of the substrate  100 . The lid  430  may be moved to a position that closes the opening  408  of the housing  402  above the fluid delivery nozzle  482  to prevent fluids from being spun out of the housing  402  during processing. 
         [0066]    A centerline of the second pad holder  478  may be aligned with the edge of the substrate  100 . The second pad holder  478  (and polishing pad  480 ) has a diameter much less than that of the substrate  100 , for example at least less than half the diameter of the substrate or even as much as less than about one eighth the diameter of the substrate. In one implementation, the second pad holder  478  (and polishing pad  480 ) may have a diameter of less than about 50 mm. The second pad holder  478  may hold the polishing pad  480  utilizing clamps, vacuum, adhesive or other suitable techniques that allow for the polishing pad  480  to periodically be replaced as the polishing pad  480  becomes worn after polishing the edge of a number of substrates  100 . 
         [0067]    The polishing pad  480  may be fabricated from a polymer material, such as porous rubber, polyurethane and the like, for example, a POLYTEX™ pad available from Rodel, Inc. of Newark, Del. The polishing pad  480  may be a fixed abrasive pad. The second pad holder  478  is coupled to the pad rotation mechanism  472  by a third shaft  486 . The third shaft  486  is oriented parallel to the Z-axis and extends from the internal volume  412  through an elongated slit formed through the housing  402  to the pad rotation mechanism  472 . The pad rotation mechanism  472  may be an electrical motor, an air motor, or any other suitable motor for rotating the second pad holder  478  and polishing pad  480  against the substrate  100 . The pad rotation mechanism  472  is coupled to the controller  208 . In one implementation, the pad rotation mechanism  472  rotates the second pad holder  478  (and polishing pad  480 ) at a rate of at least about 1000 rpm. 
         [0068]    The pad rotation mechanism  472  is coupled to bracket  488  by an axial actuator  490 . The axial actuator  490  is coupled to the controller  208  or other suitable controller and is operable to move the second pad holder  478  along the Z-axis to move the polishing pad  480  against and clear of the substrate  100  held by the substrate holder  414 . The axial actuator  490  may be a pancake cylinder, linear actuator or any other suitable mechanism for moving the second pad holder  478  in a direction parallel to the Z-axis. In operation, after the substrate holder  414  is in contact with and holding the substrate, the axial actuator  490  drives the second pad holder  478  in a z-direction to make contact with the substrate  100 . 
         [0069]    The bracket  488  is coupled to a base  492  by the lateral actuator mechanism  476  by a carriage  494  and rail  496  that allows the pad polishing head  474  to move laterally in a direction parallel to the X-axis, as depicted in  FIG. 6 . The carriage  494  is slidably mounted on the rail  496  and is driven horizontally by the lateral actuator mechanism  476  to scan the polishing pad  480  across the substrate  100 . The lateral actuator mechanism  476  may be a lead screw, a linear actuator or any other suitable mechanism for moving the pad polishing head  474  horizontally. The lateral actuator mechanism  476  is coupled to controller  208  or other suitable controller. 
         [0070]    Scanning the pad  444  across the substrate  100  in the particle cleaning module  282  has effectively demonstrated the ability to effectively remove particles, such as abrasives from the polishing fluid, from the surface of the substrate  100 . Further, scanning the polishing pad  480  across the exclusion region and/or edge region has demonstrated the ability to effectively remove particles, such as abrasives, excess deposited material, and/or polishing slurry from the surface of the substrate  100 , for example, the exclusion region and/or edge region of the substrate. Thus, the inclusion of a polishing step at the wafer edge in addition to particle cleaning has effectively demonstrated edge defect improvement. Accordingly, the need for a dedicated buffing station on the polishing module is substantially eliminated. 
         [0071]      FIG. 7  is a side view of the first pad holder  434  and the second pad holder  478  engaging pad  444  and pad  480  respectively with the substrate  100  retained by the substrate holder  414 . In operation, with respect to the first pad holder  434 , the axial actuator  440  urges the pad  444  against the substrate  100  rotated by the substrate rotation mechanism  416  while the pad rotation mechanism  436  spins the pad  444 . The lateral actuator mechanism  442  moves the first pad holder  434  and pad  444  in a horizontal direction across the surface of the substrate  100 . While the pad  444  is in contact with the substrate  100 , the fluid delivery nozzle  450  provides at least one of deionized water, a chemical solution or any other suitable fluid to the surface of the substrate  100  being processed by the pad  444 . Accordingly, the pad  444  cleans the surface of the substrate with minimal movement. 
         [0072]    In operation, with respect to the second pad holder  478 , the axial actuator  490  urges the polishing pad  480  against the substrate  100  rotated by the substrate rotation mechanism  416  while the pad rotation mechanism  472  spins the polishing pad  480 . The lateral actuator mechanism  476  moves the second pad holder  478  and the polishing pad  480  in a horizontal direction across the surface of the substrate  100 . While the polishing pad  480  is in contact with the exclusion region and/or edge region of the substrate  100 , the fluid delivery nozzle  482  provides at least one of polishing slurry, deionized water, a chemical solution or any other suitable fluid to the surface of the substrate  100  being processed by the polishing pad  480 . Accordingly, the pad  444  cleans the edge of the substrate with minimal movement. 
         [0073]    It should be understood that although  FIG. 7  depicts pad  444  and polishing pad  480  simultaneously contacting the substrate  100 , the implementations described herein do not require simultaneous contact of the substrate by the pad  444  and the polishing pad  480 . For example, the particle cleaning process performed by pad  444  may be performed sequentially (e.g., prior to and/or after) with respect to the edge polishing process performed by polishing pad  480 . 
         [0074]    One advantage of the invention is the relatively small size of the pads  444  and  480  compared to the size of the substrate  100 . Conventional systems use large pads positioned on the polishing module to clean smaller substrates, where the substrate is in 100 percent contact with the pad. Large pads are prone to trapping abrasives and particulates, which often cause scratches and defects in the substrate. However, the smaller pad of the present invention is significantly less prone to abrasive and particulate trapping, which advantageously results in a cleaner pad and substrates with less scratches and defects. Additionally, the smaller pad of the present invention significantly reduces the cost of consumables, both in the amount of fluid utilized during processing and the cost of replacement pads. Furthermore, the smaller pad of the present invention significantly allows the pad to be easily removed or replaced. 
         [0075]    Referring back to  FIG. 6 , once the substrate is cleaned and the edge of the substrate has been polished, the pad actuation assemblies  406 ,  470  retract the pad holders  434 ,  478  and pads  444 ,  480  away from the substrate  100  (shown in phantom). The first pad holder  434  and pad  444  may be moved linearly in a direction parallel to the X-axis away from the substrate and out of the internal volume  412  of the housing  402  into a pocket  604  coupled to the housing  402 . Positioning the first pad holder  434  and pad  444  in the pocket  604  as shown in phantom in  FIG. 6  and out of the internal volume  412  of the housing  402  advantageously provides more space for the robot  268  to enter the housing  402  and transfer the substrate without risk of damaging either the pad  444  or the substrate  100 , while allowing the housing  402  to be smaller and less expensive. 
         [0076]    Substrate transfer begins after cleaning by having the substrate receiver  410  move upward in a direction parallel to the Y-axis to engage the substrate  100  in the substrate receiving slot  432 . Once the substrate is disposed in the substrate receiving slot  432 , the substrate holder  414  releases the substrate  100  by turning off the vacuum provided by the vacuum source  497 , and optionally providing a gas through the apertures  502  of the substrate holder  414  to separate the substrate from the substrate holder  414 . The substrate receiver  410  with the substrate  100  disposed in the substrate receiving slot  432  is then moved laterally away from the substrate holder  414  in a direction parallel to the Z-axis to clear the substrate  100  from the substrate holder  414 . One of the substrate grippers  274 ,  276  of the robot  268  retrieves the substrate  100  from the substrate receiver  410  and removes the substrate  100  from the housing  402 . An optional top spray bar  464  and bottom spray bar  466  are positioned across the internal volume  412  and may spray the substrate  100  with deionized water or any other suitable fluid to clean the substrate  100  as the substrate  100  is removed from the particle cleaning module  282  by the robot  268 . At least one of the spray bars  464 ,  466  may be utilized to wet the substrate  100  prior to chucking against the substrate receiver  410  to remove particles that may potentially scratch the backside of the substrate and/or to improve chucking by the substrate receiver  410 . The spray bars  464 ,  466  may be coupled to different fluid sources  499 ,  500  so that different fluids may be provided to each of the spray bars  464 ,  466 , or both spray bars  464 ,  466  may be coupled to a single fluid delivery source. 
         [0077]    Referring back to the planarizing module  206  of  FIG. 2 , both of the second and third station  230 ,  232  may be used to perform CMP process as the particle cleaning module  282  substantially eliminates the need for a buffing pad disposed in one of the second and third stations  230 ,  232  as required in conventional systems. Since the second and third station,  230 ,  232  are to be used for CMP processes; the use of the particle cleaning module  282  advantageously increases the throughput of the CMP system  200 . The vertical substrate orientation of the particle cleaning module  282  is also beneficial, as it removes particles in a more compact footprint as compared to traditional horizontal designs utilized on the polishing module. 
         [0078]    Furthermore, the particle cleaning module  282  effectively cleans the substrate and decreases the loading of particulate on the brushes of the first brush module  264 B and second brush module  2640 . Therefore, the lifespan of the brushes in the first brush module  264 B and second brush module  2640  are advantageously increased. Thus, the particle cleaning module removes particularly difficult to remove polishing fluids without requiring a buffing station in the polishing module and simultaneously frees the second and or third station for additional CMP stations to increase throughput of the planarizing system. 
         [0079]    In some implementations, the driver(s) used to rotate the substrate  100  and the actuator used to push the pads and/or polishing film against the surface of the substrate or edge of the substrate edge may be controlled by the controller  208 . Likewise, operation of the fluid delivery nozzles  450 ,  482  may also be under the direction of the controller  208 . The controller  208  may be adapted to receive feedback signals from the driver and/or actuator that indicate: (1) an amount of energy and/or torque being exerted to drive the substrate  100  (e.g., rotate a vacuum chuck holding the substrate  100 ) and/or (2) an amount of force applied to the actuators to push the pads  444 ,  480  against the substrate  100 , respectively. These feedback signals may be employed to determine an amount of material that has been removed from the substrate  100 , which may include, for example, whether a particular layer of material has been removed and/or whether an intended edge profile has been reached. For example, a reduction in the torque of the rotating substrate  100  (or energy expended in rotating the substrate  100 ) during a polishing procedure may indicate a reduction in friction between the substrate  100  and the pad  444 ,  480 . The reduction in torque or rotational energy may correspond to an amount of material removed from the edge of the substrate  100  at or near points of contact between the substrate  100  and the pad  444 ,  480  and/or a characteristic edge profile (e.g., a shape, curvature or smoothness level at the edge of the substrate  100 ). 
         [0080]    Alternatively or additionally, a friction sensor positioned in contact with the edge of the substrate  100  may provide signals indicative of an amount of material that has been removed from the edge of the substrate  100 . 
         [0081]    In some implementations, the pad  444 ,  480  may have an adjustable amount of ability to conform to the substrate&#39;s edge. In certain implementations, the pad material may be selected such that the pad  444 ,  480  has an adjustable amount of ability to conform to the substrate&#39;s edge. In certain implementations, the pad  444 ,  480  may be or include an inflatable bladder such that by adding more air or liquid or other fluid, the pad becomes harder and by reducing the amount of air or liquid or other fluid in the bladder, the pad becomes more conforming. In some implementations, the fluid supply may inflate/deflate the bladder under the direction of an operator or a programmed and/or user operated controller. In such implementations, an elastomeric material such as silicon rubber or the like may be used for the bladder to further enhance the pad&#39;s ability to stretch and conform to the substrate&#39;s edge. Such an implementation would allow an operator/controller to precisely control how far beyond the exclusion region  108   a  and/or  108   b  and into the bevels  112 ,  114  (if at all) (See  FIG. 1 ) the polishing pad  480  is made to contact the substrate  100  by, e.g., limiting the amount of fluid pumped into the bladder. For example, once a substrate outer edge  110  is placed against the pad  444  with a deflated bladder, the bladder may be inflated so that the pad  444  is forced to wrap around and conform to the outer edge  110  and bevel(s)  112 ,  114  of the substrate  100  without wrapping around to the device region  106   a ,  106   b  of the substrate  100 . 
         [0082]      FIG. 8  is a top schematic view of the particle cleaning module  282  having a pad conditioning assembly  810  for conditioning the pad  444  and a zero gap calibration sensor having sensor heads  820   a ,  820   b  positioned for detecting the position of the pad  444  disposed therein. The particle cleaning module  282  also includes a pair of cleaning nozzles  830   a  and  830   b  for directing a cleaning fluid (e.g., DI water) toward various components of the particle cleaning module  282  and a spray nozzle  840  for directing a cleaning fluid (e.g., DI water) toward the polishing pad  480  to condition and remove debris from the polishing pad  480 . As depicted in  FIG. 11 , the second pad actuation assembly  1170  does not move in a lateral direction like the second pad actuation assembly  470  depicted in  FIG. 4 . 
         [0083]    The sensor heads  820   a ,  820   b  of the zero gap calibration sensor may be coupled with the controller  208 . The zero gap calibration sensor is configured to detect the position of the pad  444  relative to the surface of the substrate  100 . 
         [0084]      FIGS. 9A-9C  are schematic views of the first pad actuation assembly  406  according to implementations described herein.  FIGS. 10A-10D  are schematic views of the first pad actuation assembly  406  according to implementations described herein. 
         [0085]      FIG. 9A  is a partial schematic view of the particle cleaning module  282  where the pad conditioning assembly  810  includes a high pressure spray nozzle  905  for directing a cleaning fluid toward the pad  444  of the first pad actuation assembly  406 . The pad conditioning assembly  810  is positioned adjacent to the substrate holder  414  such that the first pad actuation assembly  406  may move laterally along rail  458  to the side of the substrate holder  414  where the pad  444  may be accessed by the pad conditioning assembly  810 . 
         [0086]    With reference to  FIGS. 9B, 9C, 10B, 10C and 10D , the first pad actuation assembly  406  includes a first pad holder assembly  910 , an adapter  920  for coupling the first pad holder  434  with the first pad holder assembly  910 . The first pad holder assembly  910  may be coupled with a motor shaft  925  of the pad rotation mechanism  436 . The first pad holder assembly  910  may be coupled with the pad rotation mechanism  436  via one or more attachment mechanisms  930 , for example, clamping screws. The adapter  920  may be coupled with the first pad holder assembly  910  via one or more attachment mechanisms  940 , for example, a locking pin. The first pad holder  434  may be coupled with the adapter  920  via one or more attachment mechanisms  950 , e.g., a locking screw. 
         [0087]    The first pad holder  434  is removable from the adapter  920  for replacement. In order to replace the pad  444 , the attachment mechanism  950  only needs to be loosened and the first pad holder  434  and pad  444  may be removed without removing the first pad holder assembly  910  and adapter  920 . In certain implementations, the first pad holder assembly  910  is coupled directly with the first pad holder  434  without the use of an adapter. A force control mechanism  960  (e.g., a compression spring) may be positioned between the adapter  920  and the first pad holder  434 . 
         [0088]      FIG. 10A  is a schematic perspective view of one implementation of the first pad actuation assembly  406 . The first pad actuation assembly  406  is coupled with the rail  458 . As depicted by arrow  1010 , the first pad actuation assembly  406  is movable along rail  458 . The first pad actuation assembly  406  is also coupled with a second rail  1030  for movement of the first pad actuation assembly  406  in the direction shown by arrow  1020 . Movement in the direction shown by arrow  1020  allows for the pad  444  to contact the substrate  100  for polishing and cleaning the substrate and also allows the pad  444  to contact the pad conditioning assembly  810  for conditioning of the pad  444 . 
         [0089]      FIG. 11  is a schematic cross-sectional view of another implementation of a particle cleaning module  1100  according to implementations described herein. The particle cleaning module  1100  may be used in place of the particle cleaning module  282  in and of the previously discussed implementations. Similar to particle cleaning module  282 , particle cleaning module  1100  includes a housing  1102 , a substrate rotation assembly  404 , a first pad actuation assembly  1106  and a second pad actuation assembly  1170 . However, unlike particle cleaning module  282 , the first pad actuation assembly  1106  of particle cleaning module  1100  includes a rotary arm assembly  1108  and the second pad actuation assembly  1170  is stationary (e.g. does not move laterally along a track like the second actuation assembly  470 .) Although the first pad actuation assembly  1106  and the second pad actuation assembly  1170  are shown, it should be understood that the implementations described herein may be performed with a single pad actuation assembly. For example, the first pad actuation assembly  1106  and the second pad actuation assembly  1170  may be positioned in separate housings. The housing  1102  includes an opening (not shown) at a top of the housing and a substrate receiver  410  at a bottom  1118  of the housing  1102 . A drain  1168  is formed through the bottom  1118  of the housing  1102  to allow fluids to be removed from the housing  1102 . The opening allows the robot  268  (not shown in  FIG. 11 ) to vertically transfer the substrate to an internal volume  1112  defined within the housing  1102 . The housing  1102  may optionally include a lid  1104  that can open and close to allow the robot  268  in and out of the housing  1102 . 
         [0090]    The substrate receiver  410  has a substrate receiving slot (not shown in  FIG. 11 ) facing upwards parallel to the Y-axis. The receiving slot is sized to accept the perimeter of the substrate  100 , thereby allowing the one of the substrate grippers  274 ,  276  of the substrate handler  266  (See  FIG. 3 ) to place the substrate  100  in the receiving slot in a substantially vertical orientation. The substrate receiver  410  is coupled to a Z-Y actuator  411 . The Z-Y actuator  411  may be actuated to move the substrate receiver  410  upwards in the Y-axis to align a centerline of the substrate  100  disposed in the substrate receiver  410  with a centerline of the substrate rotation assembly  404 . Once the centerline of the substrate  100  is aligned with the centerline of the substrate rotation assembly  404 , the Z-Y actuator  411  may be actuated to move the substrate receiver  410  in the Z-axis to contact the substrate  100  against the substrate rotation assembly  404 , which then actuates to chuck the substrate  100  to the substrate rotation assembly  404 . After the substrate  100  has been chucked to the substrate rotation assembly  404 , the Z-Y actuator  411  may be actuated to move the substrate receiver  410  in the Y-axis clear of the substrate  100  and the substrate rotation assembly  404  so that the substrate  100  held by the substrate rotation assembly  404  may be rotated without contacting the substrate receiver  410 . 
         [0091]    The substrate rotation assembly  404  is disposed in the housing  1102  and includes a substrate holder  414  coupled to a substrate rotation mechanism  416 . The substrate holder  414  may be an electrostatic chuck, a vacuum chuck, a mechanical gripper or any other suitable mechanism for securely holding the substrate  100  while the substrate is rotated during processing within the particle cleaning module  1100 . Preferably, the substrate holder  414  is either an electrostatic chuck or a vacuum chuck. 
         [0092]    The first pad actuation assembly  1106  includes the pad rotation mechanism  436 , a pad cleaning head  438 , and the rotary arm assembly  1108 . The pad cleaning head  438  is located in the internal volume  1112  of the housing  1102  and includes the first pad holder  434  that holds the pad  444  and a fluid delivery nozzle  450 . The fluid delivery nozzle  450  is coupled to a fluid delivery source  498  that provides deionized water, a chemical solution or any other suitable fluid to the pad  444  during cleaning the substrate  100 . 
         [0093]    The first pad holder  434  (and pad  444 ) has a diameter much less than that of the substrate  100 , for example at least less than half the diameter of the substrate or even as much as less than about one eighth the diameter of the substrate. In one implementation, the first pad holder  434  (and pad  444 ) may have a diameter of less than about 25 mm. The first pad holder  434  may hold the pad  444  utilizing clamps, vacuum, adhesive or other suitable technique that allows for the pad  444  to periodically be replaced as the pad  444  becomes worn after cleaning a number of substrates  100 . 
         [0094]    The pad  444  may be fabricated from a polymer material, such as porous rubber, polyurethane and the like, for example, a POLYTEX™ pad available from Rodel, Inc. of Newark, Del. In one implementation, the first pad holder  434  may be used to a hold a brush or any other suitable cleaning device. The first pad holder  434  is coupled to the pad rotation mechanism  436  by a second shaft  446 . The second shaft  446  is oriented parallel to the Z-axis and extends from the internal volume  1112  through an elongated slit formed through the housing  402  to the pad rotation mechanism  436 . The pad rotation mechanism  436  may be an electrical motor, an air motor, or any other suitable motor for rotating the first pad holder  434  and pad  444  against the substrate. The pad rotation mechanism  436  is coupled to the controller  208 . In one implementation, the pad rotation mechanism  436  rotates the first pad holder  434  (and pad  444 ) at a rate of at least about 1000 rpm. 
         [0095]    The pad rotation mechanism  436  is coupled to bracket  454  by an axial actuator  440 . The axial actuator  440  is coupled to the controller  208  or other suitable controller and is operable to move the first pad holder  434  along the Z-axis to move the pad  444  against and clear of the substrate  100  held by the substrate holder  414 . The axial actuator  440  may be a pancake cylinder, linear actuator or any other suitable mechanism for moving the first pad holder  434  in a direction parallel to the Z-axis. In operation, after the substrate holder  414  is in contact with and holding the substrate, the axial actuator  440  drives the first pad holder  434  in a z-direction to make contact with the substrate  100 . 
         [0096]    The rotary arm assembly  1108  includes a rotary arm  1180 , a rotary arm rotation motor  1150 , a lateral actuator mechanism  1182  for moving the rotary arm  1180  toward the substrate  100 . The lateral actuator mechanism  1182  may comprise a disk pad arm in/out cylinder coupled  1184  with a spring  1186  for force control and damping. 
         [0097]    The second pad actuation assembly  1170  includes a pad rotation mechanism  472 , and a pad polishing head  474 . The pad polishing head  474  is located in the internal volume  1112  of the housing  1102  and includes the second pad holder  478  that holds a pad  480  and a fluid delivery nozzle  482 . The fluid delivery nozzle  482  is coupled to a fluid delivery source  484  that provides polishing slurry, deionized water, a chemical solution or any other suitable fluid to the pad  480  during polishing of the exclusion region and/or edge region of the substrate  100 . 
         [0098]    A centerline of the second pad holder  478  may be aligned with the edge of the substrate  100 . The second pad holder  478  (and polishing pad  480 ) has a diameter much less than that of the substrate  100 , for example at least less than half the diameter of the substrate or even as much as less than about one eighth the diameter of the substrate. In one implementation, the second pad holder  478  (and polishing pad  480 ) may have a diameter of less than about 50 mm. The second pad holder  478  may hold the polishing pad  480  utilizing clamps, vacuum, adhesive or other suitable techniques that allow for the polishing pad  480  to periodically be replaced as the polishing pad  480  becomes worn after polishing the edge of a number of substrates  100 . 
         [0099]    The polishing pad  480  may be fabricated from a polymer material, such as porous rubber, polyurethane and the like, for example, a POLYTEX™ pad available from Rodel, Inc. of Newark, Del. The polishing pad  480  may be a fixed abrasive pad. The second pad holder  478  is coupled to the pad rotation mechanism  472  by a third shaft  486 . The third shaft  486  is oriented parallel to the Z-axis and extends from the internal volume  1112  through an elongated slit formed through the housing  1102  to the pad rotation mechanism  472 . The pad rotation mechanism  472  may be an electrical motor, an air motor, or any other suitable motor for rotating the second pad holder  478  and polishing pad  480  against the substrate  100 . The pad rotation mechanism  472  is coupled to the controller  208 . In one implementation, the pad rotation mechanism  472  rotates the second pad holder  478  (and polishing pad  480 ) at a rate of at least about 1000 rpm. 
         [0100]    The pad rotation mechanism  472  is coupled to bracket  488  by an axial actuator  490 . The axial actuator  490  is coupled to the controller  208  or other suitable controller and is operable to move the second pad holder  478  along the Z-axis to move the polishing pad  480  against and clear of the substrate  100  held by the substrate holder  414 . The axial actuator  490  may be a pancake cylinder, linear actuator or any other suitable mechanism for moving the second pad holder  478  in a direction parallel to the Z-axis. In operation, after the substrate holder  414  is in contact with and holding the substrate, the axial actuator  490  drives the second pad holder  478  in a z-direction to make contact with the substrate  100 . 
         [0101]    Scanning the pad  444  across the substrate  100  in the particle cleaning module  1100  has effectively demonstrated the ability to effectively remove particles, such as abrasives from the polishing fluid, from the surface of the substrate  100 . Further, scanning the polishing pad  480  across the exclusion region and/or edge region has demonstrated the ability to effectively remove particles, such as abrasives, excess deposited material, and/or polishing slurry from the surface of the substrate  100 , for example, the exclusion region and/or edge region of the substrate. Thus, the inclusion of a polishing step at the wafer edge in addition to particle cleaning has effectively demonstrated edge defect improvement. Accordingly, the need for a dedicated buffing station on the polishing module is substantially eliminated. 
         [0102]      FIG. 12  is a cross-sectional schematic view of another implementation of a disk pad holder according to implementations described herein. 
         [0103]      FIG. 13  is another schematic view of the particle cleaning module  1100  of  FIG. 11  according to implementations described herein.  FIG. 13  depicts the sweep motion of the rotary arm  1180  along a curved path as shown by arrow  1310 . 
         [0104]      FIG. 14  is another schematic view of the particle cleaning module  1100  of  FIG. 11  according to implementations described herein.  FIG. 14  depicts the sweep motion of the rotary arm  1180  and the attached pad  444  along arrow  1310  to interact with the pad conditioning assembly  810  and pad clean spray nozzle  1402  for delivering a cleaning fluid (e.g., DI water) to surface of the pad  444 . A sensor  1404  for detecting the presence of substrate  100  is positioned on the substrate receiver  410 . 
         [0105]      FIG. 15  is a schematic view of a portion of a particle cleaning module illustrating another implementation of the pad conditioning assembly  810  according to implementations described herein. The pad conditioning assembly  810  includes a conditioning pad actuation assembly  1570  for rotating a conditioning pad  1580  and moving the conditioning pad  1580  in an axial direction  1504  toward the pad to be conditioned. The conditioning pad  1580  may be a conditioning disk. The conditioning pad actuation assembly  1570  includes a pad rotation mechanism  1572  and a pad polishing head  1574 . The pad polishing head  1574  is located in the internal volume  1112  of the housing  1102  and includes a pad holder  1578  that holds the conditioning pad  1580  and a fluid delivery nozzle  1502 . The fluid delivery nozzle  1502  is coupled to a fluid delivery source  1584  that provides polishing slurry, deionized water, a chemical solution or any other suitable fluid to the conditioning pad  1580  during conditioning of the pad  444 . 
         [0106]      FIG. 16  is a schematic view of another implementation of an edge pad polishing assembly  1600  according to implementations described herein. The edge pad polishing assembly  1600  may be used in place of either the second pad actuation assembly  470  or the second pad actuation assembly  1170 . The edge pad polishing assembly  1600  is adjustable between 1 and 10 degrees as shown by arrow  1602 , which provides better access to the edge of substrate  100  for improved cleaning. 
         [0107]    The edge pad polishing assembly  1600  includes a pad rotation mechanism  1672 , a pad polishing head  1674  and an axial actuator mechanism  1690 . The pad polishing head  1674  is located in the internal volume  1112  of the housing  1102  and includes an edge pad holder  1678  that holds a polishing pad  1680  and a fluid delivery nozzle. The fluid delivery nozzle is coupled to a fluid delivery source that provides polishing slurry, deionized water, a chemical solution or any other suitable fluid to the polishing pad  1680  during polishing of the exclusion region and/or edge region of the substrate  100 . 
         [0108]    A centerline of the edge pad holder  1678  may be aligned with the edge of the substrate  100 . The edge pad holder  1678  (and polishing pad  1680 ) has a diameter much less than that of the substrate  100 , for example at least less than half the diameter of the substrate or even as much as less than about one eighth the diameter of the substrate. In one implementation, the edge pad holder  1678  (and polishing pad  1680 ) may have a diameter of less than about 50 mm. The edge pad holder  1678  may hold the polishing pad  1680  utilizing clamps, vacuum, adhesive or other suitable techniques that allow for the polishing pad  1680  to periodically be replaced as the polishing pad  1680  becomes worn after polishing the edge of a number of substrates  100 . 
         [0109]    The polishing pad  1680  may be fabricated from a polymer material, such as porous rubber, polyurethane and the like, for example, a POLYTEX™ pad available from Rodel, Inc. of Newark, Del. The polishing pad  1680  may be a fixed abrasive pad. The edge pad holder  1678  is coupled to the pad rotation mechanism  1672  by a shaft  1686 . The pad rotation mechanism  1672  may be an electrical motor, an air motor, or any other suitable motor for rotating the edge pad holder  1678  and polishing pad  1680  against the substrate  100 . The pad rotation mechanism  1672  is coupled to the controller  208 . In one implementation, the pad rotation mechanism  1672  rotates the edge pad holder  1678  (and polishing pad  1680 ) at a rate of at least about 1000 rpm. 
         [0110]    The pad rotation mechanism  1672  may be coupled to a bracket (not shown) by an axial actuator  1690 . The axial actuator  1690  is coupled to the controller  208  or other suitable controller and is operable to move the edge pad holder  1678  along the Z-axis to move the polishing pad  1680  against the edge of the substrate  100  held by the substrate holder  414 . The axial actuator  1690  may be a pancake cylinder, linear actuator or any other suitable mechanism for moving the edge pad holder  1678  in a direction parallel to the Z-axis. In operation, after the substrate holder  414  is in contact with and holding the substrate, the axial actuator  1690  drives the edge pad holder  1678  in a z-direction to make contact with the substrate  100 . 
         [0111]    While the foregoing is directed to implementations of the present invention, other and further implementations of the invention may be devised without departing from the basic scope thereof, and the scope thereof is determined by the claims that follow.