Abstract:
Apparatus and methods are provided to polish a notch of a substrate. The invention includes a polishing head adapted to apply a polishing tape against the notch of the substrate, including: a plunger; and an actuator, wherein the actuator is adapted to move the plunger with respect to the polishing tape. Numerous other aspects are provided.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    The present application is related to the following commonly-assigned, co-pending U.S. Patent Applications, each of which is hereby incorporated herein by reference in its entirety for all purposes: 
         [0002]    U.S. patent application Ser. No. 12/124,137, filed May 20, 2008, entitled “METHODS AND APPARATUS FOR POLISHING A NOTCH OF A SUBSTRATE USING A POLISHING PAD” (Attorney Docket No. 10674); 
         [0003]    U.S. patent application Ser. No. ______, filed Oct. 24, 2008, entitled “METHODS AND APPARATUS FOR POLISHING AN EDGE AND/OR NOTCH OF A SUBSTRATE” (Attorney Docket No. 10671/L); 
         [0004]    U.S. patent application Ser. No. ______, filed Oct. 24, 2008, entitled “METHODS AND APPARATUS FOR POLISHING A NOTCH OF A SUBSTRATE WITH A MANDREL” (Attorney Docket No. 10672/L); and 
         [0005]    U.S. patent application Ser. No. ______, filed Oct. 24, 2008, entitled “METHODS AND APPARATUS FOR POLISHING A NOTCH OF A SUBSTRATE WITH AN ABRASIVE CORD” (Attorney Docket No. 10673/L). 
     
    
     FIELD OF THE INVENTION 
       [0006]    The present invention relates generally to substrate processing, and more particularly to methods and apparatus for cleaning a notch in an edge of a substrate. 
       BACKGROUND OF THE INVENTION 
       [0007]    Conventional systems, which contact a notch in the edge of a substrate with an abrasive tape to clean the notch, may not be able to contact all parts of the notch with the abrasive tape. As a result, these conventional systems may not be able to clean or polish all parts of the notch. Accordingly, effective methods and apparatus for cleaning or polishing all parts of notches in the edges of substrates are desired. 
       SUMMARY OF THE INVENTION 
       [0008]    In some aspects of the invention an apparatus is provided for polishing a notch of a substrate. The apparatus includes a polishing head adapted to apply a polishing tape against the notch of the substrate. The polishing head includes a plunger; and an actuator, wherein the actuator is adapted to move the plunger with respect to the polishing tape. 
         [0009]    In other aspects of the invention, a system is provided for polishing a notch of a substrate. The system includes a substrate support adapted to rotate a substrate; and a polishing head adapted to apply a polishing tape against the notch of the substrate. The polishing head includes a plunger; and an actuator, wherein the actuator is adapted to press the plunger into the polishing tape and thereby press the polishing tape against the notch. The system also includes a controller adapted to operate the rotation of the substrate and the actuator. 
         [0010]    In yet other aspects of the invention, a method is provided for polishing a notch of a substrate. The method includes (1) securing a substrate on a support; (2) aligning a substrate notch with a polishing head including a plunger; (3) pressing a polishing tape against a notch with the plunger; and (4) advancing the polishing tape as the polishing tape is pressed against the notch. 
         [0011]    Other features and aspects of the present invention will become more fully apparent from the following detailed description, the appended claim and the accompanying drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0012]      FIG. 1  is a schematic illustration of a cross-section of a portion of a substrate. 
           [0013]      FIG. 2  is a schematic plan view of an embodiment of a system for polishing parts of a substrate, including major surfaces, edge, bevel, and notch. 
           [0014]      FIG. 3  is a schematic perspective view of an embodiment of a polishing apparatus for polishing a substrate notch. 
           [0015]      FIG. 4  is a schematic illustration of part of a substrate, including a substrate notch. 
           [0016]      FIG. 5  is a schematic perspective view of a portion of an embodiment of the notch polishing apparatus of  FIG. 3 . 
           [0017]      FIG. 6  is a plan view of an example of polishing tape being pressed into a substrate notch by a plunger in accordance with some embodiments of the present invention. 
           [0018]      FIG. 7  is a plan view of an example of polishing tape being pressed into a substrate notch by an angled plunger in accordance with some embodiments of the present invention. 
           [0019]      FIG. 8  is a schematic perspective view of another embodiment of a polishing apparatus for polishing a substrate notch. 
           [0020]      FIG. 9  is a flow chart of a method for polishing a substrate notch in accordance with the present invention. 
       
    
    
     DETAILED DESCRIPTION 
       [0021]    Substrates used in semiconductor processing often have films and/or surface defects which it is helpful to remove prior to subsequent processing steps. These films and defects may occur on the edge of a substrate, including notches formed thereon. 
         [0022]    In some embodiments, the present invention provides apparatus and methods that effectively adapt to various shapes of notches found in different substrates, ensure good contact of a polishing or abrasive film or tape with all sections of a substrate notch region, and remove thin films and surface defects at a substrate notch. In one or more embodiments, a polishing plunger may be provided. The polishing plunger may be adapted to press a moving polishing tape against the substrate notch. The polishing plunger may substantially conform to the shape of the substrate notch, such that the polishing tape contacts all portions of the notch. 
         [0023]    Turning to  FIG. 1 , a substrate  100  may include two major surfaces  102 ,  102 ′ and an edge  104 . Each major surface  102 ,  102 ′ of the substrate  100  may include a device region  106 ,  106 ′ and an exclusion region  108 ,  108 ′. (Typically however, only one of the two major surfaces  102 ,  102 ′ will include a device region and an exclusion region.) The exclusion regions  108 ,  108 ′ may serve as buffers between the device regions  106 ,  106 ′ and the edge  104 . The edge  104  of the 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 ,  108 ′ of the two major surfaces  102 ,  102 ′. A notch  116  may be located in the outer edge  110  of the substrate  100 . In some embodiments, the present invention may be adapted for use with a system adapted to clean and/or polish the outer edge  110  and at least one bevel  112 ,  114  of the substrate  100  without affecting the device regions  106 ,  106 ′. In some embodiments, all or part of the exclusion regions  108 ,  108 ′ may be cleaned or polished as well. 
         [0024]      FIG. 2  is a schematic plan view of an embodiment of a system  200  for polishing parts of the substrate  100 , including the major surfaces  102 ,  102 ′, the edge  104 , and the notch  116 . The system  200  includes three polishing apparatuses  202 , each including a polishing head  204 . However, any number and type of apparatus  202 /heads  204  may be used in any practicable combination. In addition, in such multi-head embodiments, each head  204  may use a differently configured or type of a polishing tape (e.g., different grits, materials, tensions, pressures, etc.) to contact and polish the substrate edge  104  and/or notch  116 . Any number of heads  204  may be used concurrently, individually, and/or in any sequence. The heads  204  may be disposed in different positions and/or in different orientations (e.g., aligned with the substrate edge  104  and/or notch  116 , normal to the substrate edge  104  and/or notch  116 , angled relative to the substrate edge  104  and/or notch  116 , etc.) to allow polishing tape, pushed by a plunger in some embodiments ( FIG. 3 ), to polish different portions of the substrate edge  104  and/or notch  116 . 
         [0025]    In some embodiments, one or more of the heads  204  may be adapted to be oscillated or moved (e.g., pivoted or angularly translated about a tangential axis of the substrate  102  and/or circumferentially relative to the substrate  102 ) around or along the substrate edge  104  and/or notch  116  so as to polish different portions of the substrate edge  104  and/or notch  116 . In some embodiments, one or more of the heads  204  may be adapted to continuously or intermittently oscillate between the various positions. Alternatively, one or more of the heads  204  may be fixed and/or only adjusted while the substrate  102  is not being rotated. In yet other embodiments, the substrate  102  may be held fixed while one or more of the heads  204  oscillate (as described above) as well as rotate circumferentially around the substrate  102 . This movement may be under the direction of a programmed or user operated controller  206 , described below. Different heads  204  may be used for different substrates  100  or different types of substrates  100 . 
         [0026]    As described above, the system  200  may further include the controller  206 , (e.g., a programmed computer, a programmed processor, a microcontroller, a gate array, a logic circuit, an embedded real time processor, etc.), which may control the driver(s) used to rotate the substrate  100  and/or the actuator(s) used to push a polishing plunger(s) ( FIG. 3 ) against the substrate edge  104  and/or notch  116 . Note that the controller  206  may be coupled (e.g., electrically, mechanically, pneumatically, hydraulically, etc.) to each of a plurality of actuators. Likewise, the controller  206  may be adapted to receive feedback signals from one or more drivers and/or actuators, that indicate the amount of energy being exerted to rotate the substrate  100  (e.g., rotate a vacuum chuck holding the substrate  100 ) and/or actuate the actuator(s) to push the polishing plunger ( FIG. 3 ) against the substrate notch  116 . As described further below, these feedback signals may be employed to determine when a particular layer of film has been removed from the edge  104  and/or notch  116  of the substrate  100  and/or whether a sufficient amount of substrate polishing has occurred. 
         [0027]    As mentioned above, substrate polishing may be performed using one or more polishing apparatuses  202 . In one or more embodiments, a plurality of polishing apparatuses  202  may be employed, in which each polishing apparatus  202  may have similar or different characteristics and/or mechanisms. In the latter case, particular polishing apparatuses  202  may be employed for specific operations. For example, one or more polishing apparatuses  202  may be adapted to perform relatively rough polishing and/or adjustments while another one or more polishing apparatus  202  may be adapted to perform relatively fine polishing and/or adjustments. Polishing apparatuses  202  may be used in sequence so that, for example, a rough polishing procedure may be performed initially and a fine polishing procedure may be employed subsequently as needed or according to a polishing recipe. The plurality of polishing apparatuses  202  may be located in a single chamber or module, as shown herein, or alternatively, one or more polishing apparatuses  202  may be located in separate chambers or modules. Where multiple chambers are employed, a robot or another type of transfer mechanism may be employed to move substrates  100  between the chambers so that polishing apparatuses  202  in the separate chambers may be used in series or otherwise. 
         [0028]    Substrate [edge/notch] polishing may be performed using one or more polishing apparatuses  202 . In one or more embodiments, a plurality of polishing apparatuses  202  may be employed, in which each polishing apparatus  202  may have similar or different characteristics and/or mechanisms. In the latter case, particular polishing apparatuses  202  may be employed for specific operations. For example, one or more of a plurality of polishing apparatuses  202  may be adapted to perform relatively rough polishing and/or adjustments while another one or more of the plurality of polishing apparatus  202  may be adapted to perform relatively fine polishing and/or adjustments. Polishing apparatuses  202  may be used in sequence so that, for example, a rough polishing procedure may be performed initially and a fine polishing procedure may be employed subsequently to make adjustments to a relatively rough polish as needed or according to a polishing recipe. The plurality of polishing apparatuses  202  may be located in a single chamber or module, as shown herein, or alternatively, one or more polishing apparatuses  202  may be located in separate chambers or modules. Where multiple chambers are employed, a robot or another type of transfer mechanism may be employed to move substrates  100  between the chambers so that polishing apparatuses  202  in the separate chambers may be used in series or otherwise. 
         [0029]      FIG. 3  is a schematic perspective view of an embodiment of a polishing apparatus  300  for polishing a substrate edge  104  and/or notch  116 . The polishing apparatus  300  may include a substrate driver  302  (e.g., a servomotor, gear, belt, chain, etc.), which may be mounted on a pedestal  304 . A support  306  (e.g., a vacuum chuck) may be coupled (e.g., rigidly) to a shaft (not shown) of the substrate driver  302 . The support  306  may support the substrate  100 , for example. The substrate driver  302  may rotate the substrate  100 , via the support  306 , about a center  308  of the substrate  100  or another suitable axis. The substrate driver  302  may be connected to a substrate driver control unit, such as the controller  206  ( FIG. 2 ), for example, which may control the angular displacement, angular velocity, and angular acceleration of the substrate  100 . The polishing apparatus  300  may further include a polishing arm  310  aligned in the horizontal plane approximately tangential to the substrate edge  104  and supported by a frame  312 . The frame  312  may be coupled at one end to a polishing head driver  309 . In other embodiments, the polishing arm  310  may be aligned differently, for example, vertically or at an angle with respect to the horizontal plane. The polishing arm  310  may include a polishing head section  314  (‘head’). The polishing head  314  may include a plunger  316 . The plunger  316  may be shaped to correspond to the shape of the notch  116 , described further below. The plunger  316  may be moved towards or away from the substrate  100  by an actuator ( FIG. 5 ) (e.g., hydraulic actuator, pneumatic actuator, servomotor, etc.). Polishing tape  318 , may wrap around the polishing head  314 , and guide rollers  320 ,  322  and over the plunger  316 , and be tensioned between supply and take-up spools  324 ,  326 . The supply and take-up spools  324 ,  326  may be driven by supply and take-up spool drivers  328 ,  330  (e.g., servomotors), respectively. The supply and take-up spool drivers  328 ,  330 , may be moved continuously or indexed to precisely control the amount of the polishing tape  318  that is advanced over the polishing head  314  from, for example, the supply and take-up spools  324 ,  326 , in order to polish the substrate notch  116 . In some embodiments, as the polishing tape  318  advances, the polishing tape  318  may vibrate, in either a horizontal or vertical orientation, for example. Other suitable orientations may be used. 
         [0030]    In one or more embodiments, the polishing tape  318  may be made from many different materials, such as aluminum oxide, silicon oxide, silicon carbide, etc. Other materials may also be used. In some embodiments, abrasives used may range, for example, from about 0.1 microns up to about 10 microns in size or, for example, 0.5 microns to 3 microns in size, although other sizes may be used. Different widths of polishing tape  318  ranging from about 0.55 inch to about 1.5 inches may be used, although other polishing tape widths may be used. In one or more embodiments, the polishing tape  318  may be about 0.002 to about 0.02 inches thick and withstand about 1 to 5 lbs. in tension. Other polishing tapes having different thicknesses and tensile strengths may be used. The supply and take-up spools  324 ,  326  may have a diameter of approximately 3 inches and be capable of holding about 30,000 inches of polishing tape  318 , or, for example, may have a diameter of approximately 1 inch and be capable of holding about 500 inches of polishing tape  318 . Other spool dimensions may be used. The supply and take-up spools  324 ,  326  may be constructed from materials such as nylon, polyurethane, polyvinyl difluoride (PVDF), etc. Other materials may also be used. 
         [0031]    With reference to  FIG. 4 , a part of the substrate  100  containing the notch  116  is schematically illustrated, not to scale. The notch  116  may include one or more notch sides  400 . The notch  116  may also include a first notch corner or node  402  and a second notch corner or node  404 . Each notch corner  402 ,  404  may be positioned at the intersection of the notch side  400  and the outer perimeter of the substrate  100 . The notch  116  may further include a notch center  406 , positioned at the intersection of the one or more notch sides  400 . The notch center  406  may be used to align the substrate  100  during processing. As is apparent from the figure, the notch  116  may exhibit large changes in curvature as it is traced from the first notch corner  402  to the second notch corner  404 , via the notch sides  400  and notch center  406 . For this reason, it is advantageous to maintain consistent contact between the polishing tape  318  and all regions of the notch  116  indicated above during polishing. 
         [0032]    Turning to  FIG. 5 , a schematic perspective view of a portion of an embodiment of the notch polishing apparatus  300  of  FIG. 3  is provided. For reasons of clarity, only the substrate  100 , the plunger  316 , the polishing tape  318 , and the supply and take-up spools  324 ,  326  are shown. In addition, it should be pointed out that the positioning of the supply and take-up spools  324 ,  326  shown herein is different than in the embodiment of the notch polishing apparatus  300  shown in  FIG. 3 . 
         [0033]    However, the positioning of the supply and take-up spools  324 ,  326  may be arranged in different ways and may not have a large effect on the polishing of the notch  116 . The plunger  316  may be a solid piece, resilient material, or inflatable, for example. The resilient material may be polyurethane foam or silicone rubber, for example. Other suitable materials may be used. The plunger  316  may be inflated with a pressurizable gas (e.g., air, nitrogen, carbon dioxide, etc.) or liquid (e.g., hydraulic fluid), or other suitable fluid. The plunger  316  may also be soft, rigid, and/or include or develop contours to conform to the shape of the notch  116 . The radius of the plunger  316  may be selected to ensure that the polishing tape  318  is fully pushed into the notch  116  by the plunger  316 . In some embodiments, the maximum radius of the plunger  316  is approximately less than 0.05 inches. In other embodiments, the maximum radius of the plunger  316  is approximately 0.03 inches or less. Any other suitable radius or dimensions may be used. 
         [0034]    As mentioned above, the plunger  316  may be coupled to an actuator  500 . The actuator  500  may be a pneumatic slide, hydraulic actuator, servomotor or any other suitable actuator  500 . The actuator  500  may be mounted to the polishing head  314  or the support arm  310  for example. The operation of the actuator  500  may be controlled by the controller  206 , for example. As described above with regard to  FIG. 3 , the plunger  316  may be moved toward or away from the substrate  100  by the actuator  500 . When moved toward the substrate  100  by the actuator  500 , the plunger  316  may press the polishing tape  318  into the notch  116  and cause the polishing tape  318  to conform to the shape of the notch  116  and therefore contact all of the regions of the notch  116  ( FIG. 4 ). The actuator  500  may include an actuator force or pressure sensor  502  for measuring a force or a pressure exerted by the actuator  500  on the plunger  316 . The actuator  500  may also be coupled to an actuator control unit, such as the controller  206 , for example. The actuator control unit may receive a signal from the actuator force or pressure sensor  502  indicative of the force or pressure exerted on the plunger  316  by the actuator  500 . The actuator control unit may also regulate the force or pressure exerted by the actuator  500  as a function of this signal. Depending on the amount of force applied to the plunger  316 , the rigidity of the plunger  316  selected, the amount of inflation of the inflatable plunger  316 , and/or amount of tension on the polishing tape  318 , a controlled amount of pressure may be applied to polish the notch  116  as the polishing head  314  is rotated about the substrate  100 . 
         [0035]    As described above, the polishing head  314  (and therefore the plunger  316 ) may pivot about the substrate edge  104  and/or the notch  116 . In some embodiments a center of rotation  600  ( FIG. 6 ) of the polishing head  314  may be positioned about 0.5 inches from the substrate, on a plane that goes through a center of the thickness of the substrate  100  and is parallel to a tangent line to the circumference of the substrate  100 . Other suitable center of rotation positions may be used. By positioning the center of rotation  600  a distance from the tangent line the plunger  316  may create a flatter or less acute tape face than if the center of rotation  600  were not a distance from the tangent line. By positioning the center of rotation  600  a distance from the tangent line, the notch  116  may be more effectively polished as the polishing head  314  pivots about the notch  116 . For example, in  FIG. 7 , the polishing head  314  has pivoted such that the polishing tape  318  is pressed into the notch  116  by an angled plunger  316 . Additionally, this center of rotation position may more efficiently and effectively use the polishing tape  318 , in that a greater surface area of the polishing tape  318  may contact, and therefore polish, the notch  116 . 
         [0036]    In some embodiments, one or more fluid channels (not shown) (e.g., a spray nozzle or bar) may be provided to deliver chemicals and/or water to aid in the polishing/cleaning of the notch  116 , lubricate the substrate  100 , and/or to wash away removed material. The fluid channel may be adapted to deliver fluid to the substrate  100  and/or to the polishing tape  318 . In some embodiments, the fluid may be delivered directly to the notch  116 . For example, one or more channels may be provided to direct chemicals or water to the notch  116  to assist in the polishing and/or to wash away particles resulting from the polishing. The chemicals may be sprayed directly onto the substrate  100 , at the substrate/polishing tape interface. The fluids may be sprayed from either or both sides of the substrate  100  and the present invention may employ gravity or suction to cause the runoff not to contaminate or contact other parts of the substrate  100  or apparatus of the invention. Fluid also may be delivered through the moveable polishing tape  318  to the notch  116 . The fluids may include deionized water which may serve as a lubricant and to flush particles away. A surfactant and/or other known cleaning chemistries may also be included. In some embodiments, sonic (e.g., megasonic) nozzles may be used to deliver sonicated fluids to the notch  116  or substrate edge  104  to supplement the cleaning. 
         [0037]    Turning to  FIG. 8 , an alternate embodiment of the apparatus  300  shown in  FIG. 3  is provided. The difference between  FIG. 3  and  FIG. 8  is that the supply and take-up spools  324 ,  326  and supply and take-up spool drivers  328 ,  330  shown in  FIG. 3  are oriented such that as the substrate  100  rotates in the xy plane, the polishing tape  318  advances in a longitudinal direction in the plus or minus z-plane. In  FIG. 8  the spools  324 ,  326  and spool drivers  328 ,  330  are oriented such that the polishing tape  318  advances in a longitudinal direction in the plus or minus y-plane. 
         [0038]    An exemplary method  900  for cleaning and polishing the substrate notch  116  is provided in  FIG. 9 . In step S 902 , the substrate  100  may be positioned and secured on the support. In step S 904 , the substrate  100  is rotated until the notch  116  is in alignment with the polishing head  314 , e.g., in alignment with the plunger  316 . In step S 906 , the plunger  316  is moved in the direction of the substrate  100  by the actuator  500 , until a portion of the plunger  316  is in contact with the substrate notch  116  via the polishing tape  318 , and the plunger  316  presses the polishing tape  318  against the substrate notch  116 . In step S 908 , the polishing tape  318  may advance via the supply and take-up spool drivers  328 ,  330 . 
         [0039]    Further with respect to the method  900  for cleaning and polishing the substrate notch  116 , the pressure with which the polishing tape  318  is pressed into contact with, and against, the substrate notch  116  may be determined by the force or pressure applied to the plunger  316  by the actuator  500 , the pressure of the fluid in the plunger  316 , and/or the resilience of the plunger  316  and the polishing tape  318 . As the polishing tape  318  is advanced over the substrate notch  116 , films and imperfections on the substrate notch  116  may be removed and eliminated by abrasion. The force or pressure applied by the actuator  500 , and/or the pressure of the fluid in the plunger  316 , may be adjusted by an actuator control unit and a pressure control unit, respectively, as needed. In step S 910 , a polishing-head driver or the controller  112  may rotate or pivot the polishing head  314  about the substrate notch  116  in a plane approximately perpendicular to major surfaces  102 ,  102 ′ of the substrate  100 , in order to effectively clean and polish parts of the substrate notch  116  adjacent to major surfaces  102 ,  102 ′ of the substrate  100 . The speed, direction, tension, pressing force, etc. of the polishing tape  318  may be adjustable, as may be the rotational displacement, speed, and/or acceleration of the polishing head  314  about the substrate  100 . For instance, the polishing tape  318  may be advanced at one speed for a certain length, and then another speed for another length. In addition, the polishing tape  318  may be translated or oscillated, or both, with constant or variable tensions and pressing forces. 
         [0040]    The foregoing description discloses only exemplary embodiments of the invention. Modifications of the above disclosed apparatus and methods which fall within the scope of the invention will be readily apparent to those of ordinary skill in the art. 
         [0041]    Accordingly, while the present invention has been disclosed in connection with exemplary embodiments thereof, it should be understood that other embodiments may fall within the spirit and scope of the invention, as defined by the following claim.