US20080293335A1

US20080293335A1 - Methods and apparatus for substrate edge polishing using a polishing arm

Info

Publication number: US20080293335A1
Application number: US12/124,151
Authority: US
Inventors: Gary C. Ettinger; Paul D. Butterfield; Antoine P. Manens
Original assignee: Applied Materials Inc
Current assignee: Applied Materials Inc
Priority date: 2007-05-21
Filing date: 2008-05-21
Publication date: 2008-11-27
Also published as: TW200906545A; JP2008284684A

Abstract

Apparatus and methods adapted to polish an edge of a substrate include (1) a polishing tape having a polishing surface and a second surface and (2) a polishing arm having a longitudinal axis and adapted to force the polishing surface of the polishing tape into contact with an edge of a substrate. The polishing arm includes i) a polishing head adapted to contact the second surface of the polishing tape, ii) a rocker arm coupled to the polishing head and adapted to rotate the polishing head around the longitudinal axis of the polishing arm and iii) a load arm extending adjacent to the rocker arm and adapted to move the polishing head in a direction perpendicular to the longitudinal axis of the polishing arm. Numerous other aspects are provided.

Description

The present application claims priority from U.S. Provisional Patent Application Ser. No. 60/939,333 filed May 21, 2007, entitled “METHODS AND APPARATUS FOR SUBSTRATE EDGE POLISHING USING A POLISHING ARM” (Attorney Docket No. 11567/L) is hereby incorporated herein by reference in its entirety for all purposes.

CROSS-REFERENCE TO RELATED APPLICATIONS

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:
U.S. patent application Ser. No. 11/299,295, filed on Dec. 9, 2005 and entitled “METHODS AND APPARATUS FOR PROCESSING A SUBSTRATE” (Attorney Docket No. 10121);
U.S. patent application Ser. No. 11/298,555, filed on Dec. 9, 2005 and entitled “METHODS AND APPARATUS FOR PROCESSING A SUBSTRATE” (Attorney Docket No. 10414);
U.S. Patent Application Ser. No. 60/939,351, filed May 21, 2007, entitled “METHODS AND APPARATUS FOR POLISHING A NOTCH OF A SUBSTRATE USING AN INFLATABLE POLISHING WHEEL” (Attorney Docket No. 10674/L);
U.S. Patent Application Ser. No. 60/939,353, filed May 21, 2007, entitled “METHODS AND APPARATUS FOR FINDING A SUBSTRATE NOTCH CENTER” (Attorney Docket No. 11244/L);
U.S. Patent Application Ser. No. 60/939,343, filed May 21, 2007, entitled “METHODS AND APPARATUS TO CONTROL SUBSTRATE BEVEL AND EDGE POLISHING PROFILES OF EPITAXIAL FILMS” (Attorney Docket No. 11417/L);
U.S. Patent Application Ser. No. 60/939,219, filed May 21, 2007, entitled “METHODS AND APPARATUS FOR POLISHING A NOTCH OF A SUBSTRATE USING A SHAPED BACKING PAD” (Attorney Docket No. 11483/L);
U.S. Patent Application Ser. No. 60/939,342, filed May 21, 2007, entitled “METHODS AND APPARATUS FOR REMOVAL OF FILMS AND FLAKES FROM THE EDGE OF BOTH SIDES OF A SUBSTRATE USING BACKING PADS” (Attorney Docket No. 11564/L);
U.S. Patent Application Ser. No. 60/939,350, filed May 21, 2007, entitled “METHODS AND APPARATUS FOR USING A BEVEL POLISHING HEAD WITH AN EFFICIENT TAPE ROUTING ARRANGEMENT” (Attorney Docket No. 11565/L);
U.S. Patent Application Ser. No. 60/939,344, filed May 21, 2007, entitled “METHODS AND APPARATUS FOR USING A ROLLING BACKING PAD FOR SUBSTRATE POLISHING” (Attorney Docket No. 11566/L);
U.S. Patent Application Ser. No. 60/939,333, filed May 21, 2007, entitled “METHODS AND APPARATUS FOR SUBSTRATE EDGE POLISHING USING A POLISHING ARM” (Attorney Docket No. 11567/L);
U.S. Patent Application Ser. No. 60/939,212, filed May 21, 2007, entitled “METHODS AND APPARATUS FOR IDENTIFYING A SUBSTRATE EDGE PROFILE AND ADJUSTING THE PROCESSING OF THE SUBSTRATE ACCORDING TO THE IDENTIFIED EDGE PROFILE” (Attorney Docket No. 11695/L);
U.S. Patent Application Ser. No. 60/939,337, filed May 21, 2007, entitled “METHODS AND APPARATUS FOR HIGH PERFORMANCE SUBSTRATE BEVEL AND EDGE POLISHING IN SEMICONDUCTOR MANUFACTURE” (Attorney Docket No. 11809/L);
U.S. Patent Application Ser. No. 60/939,228, filed May 21, 2007, entitled “METHODS AND APPARATUS FOR POLISHING A NOTCH OF A SUBSTRATE BY SUBSTRATE VIBRATION” (Attorney Docket No. 11952/L); and
U.S. Patent Application Ser. No. 60/939,209, filed May 21, 2007, entitled “METHODS AND APPARATUS FOR CONTROLLING THE SIZE OF AN EDGE EXCLUSION ZONE OF A SUBSTRATE” (Attorney Docket No. 11987/L).

FIELD OF THE INVENTION

The present invention relates generally to substrate processing, and more particularly to methods and apparatus for polishing an edge of a substrate.

BACKGROUND OF THE INVENTION

In preparing a substrate for semiconductor device manufacturing, the edge of the substrate is generally cleaned and/or polished. Typically, an abrasive tape is applied with some degree of force to polish bevels on the edge of the substrate. A fluid may be supplied to assist in the polishing and/or to wash away dislodged particles. It has proven to be difficult to consistently control the force applied to the abrasive tape in such polishing processes. Additionally, the wet environment on the edge of the substrate due to the supply of fluid may contaminate portions of the polishing apparatus. Accordingly, improved methods and apparatus for polishing an edge of a substrate are desired.

SUMMARY OF THE INVENTION

In a first aspect of the invention, an apparatus adapted to polish an edge of a substrate is provided. The apparatus includes (1) a polishing tape having a polishing surface and a second surface and (2) a polishing arm having a longitudinal axis and adapted to force the polishing surface of the polishing tape into contact with an edge of a substrate. The polishing arm includes i) a polishing head adapted to contact the second surface of the polishing tape, ii) a rocker arm coupled to the polishing head and adapted to rotate the polishing head around the longitudinal axis of the polishing arm and iii) a load arm extending adjacent to the rocker arm and adapted to move the polishing head in a direction approximately perpendicular to the longitudinal axis of the polishing arm.
In another aspect of the invention, a system adapted to polish an edge of a substrate is provided. The system includes a housing; and one or more edge polishing apparatuses. The one or more apparatuses include (1) a polishing tape having a polishing surface and a second surface and (2) a polishing arm having a longitudinal axis and adapted to force the polishing surface of the polishing tape into contact with an edge of a substrate. The polishing arm includes i) a polishing head adapted to contact the second surface of the polishing tape, ii) a rocker arm coupled to the polishing head and adapted to rotate the polishing head around the longitudinal axis of the polishing arm and iii) a load arm extending adjacent to the rocker arm and adapted to move the polishing head in a direction approximately perpendicular to the longitudinal axis of the polishing arm.
In yet another aspect of the invention, a method for polishing an edge of a substrate is provided. The method includes retracting an actuator in a direction generally perpendicular to the longitudinal axis of a polishing arm, and away from a substrate; rotating a pivot mechanism (e.g., in a counter-clockwise direction) in response to the retraction of the actuator; extending a load arm forward towards the substrate in response to the movement of the pivot mechanism; and contacting an edge of the substrate with a polishing tape in response to the forward movement of the load arm.
Other features and aspects of the present invention will become more fully apparent from the following detailed description, the appended claims and the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic top view of an exemplary system for edge polishing according to an embodiment of the present invention.

FIG. 2 is a perspective view of an edge polishing apparatus according to an embodiment of the present invention.

FIG. 3 is a perspective view of a polishing arm and polishing head according to an embodiment of the present invention.

FIG. 4 is a schematic illustration depicting an example embodiment of a portion of an edge polishing apparatus in contact with the edge of the substrate according to the present invention.

FIGS. 5A through 5D are close-up perspective views of different embodiments of backing pads adapted for use with embodiments of the present invention.

FIG. 6A is a top cross-sectional view depicting the load arm in position to apply force on the edge of the substrate according to an embodiment of the present invention.

FIG. 6B is a top cross-sectional view depicting the load arm in a retracted position according to an embodiment of the present invention.

DETAILED DESCRIPTION

The present invention provides improved methods and apparatus for cleaning and/or polishing the edge of a substrate. The edge of a substrate may be polished by application of an abrasive polishing tape onto the edge as the substrate is rotated or otherwise moved (e.g., oscillated). The abrasive polishing tape may be applied to the edge of the substrate by a polishing head. According to the present invention, the polishing head may be positioned at an end of a polishing arm. The polishing arm may include a rocker arm, adapted to rotate the polishing head about an axis tangential to the edge of the substrate, providing control over the contact between the polishing tape and the edge of the substrate; the polishing arm may also include a pivotable load arm, adapted to drive the polishing head toward the substrate, forcing (‘loading’) the polishing tape to contact the edge of the substrate, when pivoted in a first direction, and to retract the polishing head away from contacting the edge of the substrate when pivoted in a second, opposite direction.
It has been found that loading the polishing tape in this manner improves force control, and provides for rapid removal/withdrawal of the polishing head from the edge of the substrate so as to prevent accumulation of particles and/or fluid on the polishing head, which may otherwise result from prolonged contact with the edge of the substrate.
FIG. 1 shows a top view of an exemplary substrate edge polishing system or ‘module’ (‘edge polishing module’) according to the present invention. The edge polishing module 100 may be integrated within a larger substrate preparation system (not shown) for use in an electronic device manufacturing facility. For example, the substrate preparation system may include a factory interface for receiving new, unprepared/unprocessed substrates, and one or more cleaning modules for removing any dust or particles from the substrate, in addition to polishing modules, such as the edge polishing module 100. The substrate preparation system may be used to condition substrates for subsequent processes, such as etching, deposition, etc.
The edge polishing module 100 may include a housing 101 in which one or more edge polishing apparatuses 102, 104, 106 are positioned. Although the embodiment shown includes three (3) apparatuses, other numbers of apparatus may be used (e.g., 1, 2, 4, 5, 6, or more). The edge polishing apparatuses 102, 104, 106 may be positioned surrounding a central platform 108 (shown in FIG. 2) upon which a substrate 110 may be mounted and supported. The central platform 108 may be rotatable by a driver 111 (e.g., motor, gear, belt, chain, etc.) (also shown in FIG. 2) and may include a vacuum chuck or other mechanism for holding the substrate 110 in place during rotation of the central platform 108. In the depicted embodiment, the substrate 110 is disk-shaped having major surfaces oriented in the horizontal plane. However, in alternative embodiments, the substrate 110 may have other shapes and orientations.
Each edge polishing apparatus 102, 104, 106, may be coupled to, and supplied with, an abrasive polishing tape (shown in FIG. 2) by a corresponding set of polishing tape spools 112, 114, 116. Each set of polishing tape spools 112, 114, 116 may include a supply spool and a take-up spool (shown in FIG. 2). The supply spools may store unused polishing tape available to be unwound and pulled into the corresponding polishing apparatus 102, 104, 106, positioned adjacent the substrate 110, while the take-up spools may be adapted to receive used and/or worn polishing tape. One or both of the supply and take-up spools may be indexed to precisely control the amount of polishing tape that is advanced to the corresponding edge polishing apparatus 102, 104, 106. In some embodiments, the polishing tape may be moved continuously between the spools.
The edge polishing module 100 may also include a controller 120 (e.g., a software driven computer, a programmed processor, a microcontroller, a gate array, a logic circuit, an embedded real time processor, etc.), adapted to direct the operation of the components of the edge polishing module, including the polishing apparatuses 102, 104, 106, the driver 111, and the sets of spools 112, 114, 116. In one or more embodiments, each polishing apparatus 102, 104, 106 may be equipped with its own controller. The controller 120 may include, or be coupled to, memory resources (e.g., RAM, ROM, flash memory, optical disk, local area network (LAN) storage) (not shown). In one or more embodiments, the controller 120 may be adapted to access data related to operation of the edge polishing module 100, which may be stored in query-accessible databases stored within the memory resources.
Each edge polishing apparatus 102, 104, 106 may be adapted to load the polishing tape forcibly into contact with the edge of the substrate 110 when supplied with polishing tape from corresponding sets of spools 112, 114, 116. The sets of spools 112, 114, 116 may be oriented vertically so that the footprint occupied (i.e., the area occupied and allocated to the equipment within a manufacturing facility) by the sets of spools 112, 114, 116 is minimized.
Turning to FIG. 2, a schematic view of an edge polishing apparatus, e.g., 102, is depicted. The apparatus 102 may include a polishing arm 201, aligned in the horizontal plane approximately tangential to the edge 202 of the substrate 110 and supported by a frame 203. In other embodiments, the polishing arm 201 may be aligned differently, for example, vertically or at an angle with respect to the horizontal plane. The polishing arm 201 may include a polishing head section 204 (‘head’), adapted to forcibly apply the polishing tape 206 to the substrate edge 202 as the substrate 110 is rotated by the central platform 108, or by some other mechanism (e.g., drive rollers). The head 204 may be rotated and/or angularly translated around an axis tangential to the substrate edge 202 so as to apply force onto the substrate edge 202 at different angles. The angular translation may be oscillatory, such that the head 204 ‘rocks’ back and forth over and under the substrate edge 202. By such rotation and/or angular translation, the head 204 may bring the polishing tape 206 in contact with top and bottom bevels (i.e., angled surfaces) on the edge 202 of the substrate 110, as well as top and bottom exclusion regions, which may serve as buffers between the edge 202 and the portion of the substrate 110 allocated for device fabrication, without contacting portions of the substrate 110 allocated for device fabrication. The head 204 may include a backing and/or inflatable pad (‘backing pad’) 208, adapted to contact the polishing tape 206 as the polishing arm 201 forces the head 204 against the rotating substrate edge 202 via an actuator (not shown). The backing pad 208 may be soft and/or include or develop contours adapted to conform to the profile of the substrate edge 202. Exemplary embodiments of backing pads 208 are shown in FIGS. 5A-5D, and described below.
Edge polishing may be performed using one or more polishing apparatuses (e.g., 200). In one or more embodiments, a plurality of polishing apparatuses 200 may be employed, in which each polishing apparatus 200 may have similar or different characteristics and/or mechanisms. In the latter case, particular polishing apparatuses 200 may be employed for specific operations. For example, one or more of a plurality of polishing apparatuses 200 may be adapted to perform relatively rough polishing and/or adjustments, while another one or more of the plurality of polishing apparatuses 200 may be adapted to perform relatively fine polishing and/or adjustments. Polishing apparatuses 200 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 200 may be located in a single chamber or module (e.g., 100), or alternatively, one or more polishing apparatuses 200 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 between the chambers so that polishing apparatuses 200 in the separate chambers may be used in series or otherwise.
FIG. 3 shows a close-up view of an exemplary embodiment of the polishing arm 201 according to the present invention. The head 204 is positioned at a first, distal end of the polishing arm 201. As shown, the head 204 includes a backing block 302 (not visible in FIG. 3, but see FIG. 4) having an exposed, external surface (not shown) to which the backing pad 208 is firmly coupled. The head 204 is coupled (e.g., rigidly) to a rocker arm 304, which extends longitudinally along the polishing arm 201. The rocker arm 304 may be rotated or ‘rocked’ back and forth in a continuous or intermittent oscillatory motion around the longitudinal axis 306 (as shown by the curved arrow around axis 306) of the polishing arm 201. In the embodiment depicted, the rocker arm 304 is C-shaped in cross-section, and thus has a hollow interior. The rocker arm 304 may have other cross-sectional shapes. The rocker arm 304 may be coupled to a rocker motor 308, via a mounting bracket 310, and driven by the rocker motor 308 to rotate approximately plus and minus 90 degrees with respect to a ‘home’ (zero degree) position in which the backing pad 208 of the head 204 is oriented approximately perpendicular to the edge 202 of the substrate 110. The rocker arm 304 may be rotated at other angles.
The polishing arm 201 may further include one or more mechanical couplings (e.g., washers, rotating bearings, etc.,) (not shown) positioned within the mounting bracket 310, or between the mounting bracket 310 and the rocker arm 304, to facilitate the operation of the rocker motor 308. A sealing plate 312 may be positioned between the rocker arm 304 and the mechanical couplings to protect the mechanical couplings and the rocker motor 308 from contamination (e.g., substrate particles, cleaning fluids) resulting from the polishing process.
A load arm 314 may extend longitudinally along the polishing arm 201 adjacent to the rocker arm 304. In one or more embodiments in which the rocker arm 304 has a C-shaped cross-sectional profile, the load arm 314 may be positioned within the interior of the rocker arm 304. In such embodiments, the rocker arm 304 may rotate with the load arm 314 around the longitudinal axis 306 of the polishing arm 201. The distal end of the load arm 314 may be coupled (e.g., rigidly) to the backing block 302 and the proximal end of the load arm 314 may be coupled, via a pivot mechanism 316 (shown in FIG. 6A), to an actuator 318. The actuator 318 may comprise a pneumatic cylinder (as shown), a piezoelectric element, an electromagnetically-driven piston or any other device capable of extending or retracting in a linear direction. In one or more embodiments, the actuator 318 may be positioned at the proximal end of the polishing arm 201 some distance away from the substrate 110. It has been found that this configuration protects the actuator 318 from exposure to the wet environment and contaminants resulting from the polishing process.
As discussed below, with reference to FIGS. 6A and 6B, the movement of the actuator 318 may cause the load arm 314 to pivot in a direction opposite to the direction of movement of the actuator 318, toward or away from the edge 202 of the substrate 110. Due to the coupling between the load arm 314 and the backing block 302, the pivoting of the load arm 314 toward the substrate 110 moves the head 204 (e.g., the backing pad 208 of head 204) into contact with the edge 202 of the substrate 110, and the pivoting of the load arm 314 away from the substrate 110 causes the head 204 to retract and move away from the edge 202 of the substrate 110. It has been found that use of a longitudinally-extending load arm 314 to press the head 204 against the substrate edge 202 provides a more uniform angle between the head 204 and the substrate 110 during a stroke of the load arm 314 compared to conventional techniques.
Referring again to FIG. 2, as noted above, the polishing tape 206 may be supplied to the head 204 by a set of spools including a supply spool 209 and a take-up spool 210. The spools 209, 210 may be driven by one or more drivers (e.g., servo motors) which may provide an indexing capability to allow a specific amount of unused polishing tape 206 to be advanced or continuously fed to the substrate edge, and/or a tensioning capability to allow the polishing tape 206 to be stretched taught and to apply pressure to the substrate edge 202. Additionally, the polishing tape 206 may further be pulled taught by one or more tensioning rollers 212 positioned on the head 204 (as shown), or in other locations. The tensioning roller(s) 212 may be adapted to apply a variable amount of tension to the polishing tape 206, and thereby the substrate edge 202, so as to attain precise control over an edge polishing process which may be used to compensate for different edge geometries and changes in the substrate 110 as material is removed from the substrate edge 202.
In one or more embodiments, the abrasive component of the polishing tape 206 may be made from one or more different materials including, for example, diamond, aluminum oxide, silicon oxide, silicon carbide, etc. Other materials may also be used. In some embodiments, the abrasives used in the polishing tape 206 may range from about 0.25 microns up to about 3 microns in size, although other sizes may be used. Different widths of polishing tape 206, ranging from about 0.2 inches to about 1.5 inches, may be used (although other widths may be used). In one or more embodiments, the polishing tape 206 may be about 0.002 to about 0.02 of an inch thick, and be able to withstand about 1 to 5 lbs. of tension in embodiments that use a pad, and from about 3 to about 8 lbs. of tension in embodiments without a pad. Other tapes having different thicknesses and strengths may be used. In some embodiments, the spools 209, 210 may be approximately 1 inch to approximately 4 inches in diameter, hold up to approximately 5000 inches of polishing tape 206, and may be constructed from any practicable materials such as polyurethane, polyvinyl difloride (PVDF), etc. Other materials may be used. The spools 209, 210 may also have other dimensions and hold other amounts of polishing tape 206.
In some embodiments, the polishing apparatuses 102, 104, 106 of the edge polishing module 100 may support different types of polishing tapes (e.g., tapes of different abrasive grits) which may be used concurrently, in a predefined sequence, or at different times. The heads 204 of the polishing apparatuses 102, 104, 106 may also be disposed in different positions to allow the supported tapes to polish different portions of the edge 202 of the rotating substrate 110.
Turning to FIG. 4, a schematic close-up illustration of a polishing contact between the polishing tape 206 and the edge 202 of the substrate 110 is depicted. As shown, the polishing tape 206 may be pressed against (e.g., as indicated by arrow 402) and contour to the edge 202 of the substrate 110. The substrate 110 may be rotated against the polishing tape 206 at a rate ranging from about 50 to about 1000 RPM, for example, although other rates may be used. The polishing tape 206 may contact the edge 202 of the substrate 110 for about 15 to 150 seconds, depending on the type of tape used, the grit of the tape, the rate of rotation, the amount of polishing required, etc. More or less time may be used. As shown, the polishing tape 206 is supported by the backing pad 208, disposed adjacent a backside (e.g., a non-abrasive side) of the polishing tape 206. The backing pad 208 may be pressed toward the substrate edge 202 by the backing block 302 (which may, in turn, be forced by an actuator 318 (shown in FIG. 3)). The pressure on the backing pad 208 may cause the backing pad 208 and/or the polishing tape 206 to contour to the substrate edge 202. Thus, the friction (i.e., abrading contact) between the polishing tape 206 and the substrate edge 202 may include two elements: the torque exerted during rotation of the substrate 110 against the polishing tape 206, and the force exerted in pressing the polishing tape 206 onto the edge 202 of the substrate 110. In some embodiments, the combined force at the point(s) of contact may range from about 0.5 lbs. to about 4 lbs. Other amounts of force may be used.
In some embodiments, one or more fluid channels 404 (e.g., a spray nozzle or bar) may be provided to deliver chemicals and/or water to aid in the polishing/cleaning of the substrate edge 202, lubricate the substrate 110, and/or to wash away removed material. The fluid channel 404 may be adapted to deliver fluid to the substrate 110, to the polishing tape 206, and/or to the pad 208. 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 substrate edge 202 to supplement the cleaning. Fluid may also be delivered through the polishing tape 206 and/or pad 208 to the substrate edge 202.
Turning to FIGS. 5A-5D, different exemplary embodiments of backing pads 208A, 208B, 208C and 208D are depicted. In addition to the backing pad 208 (as shown FIG. 4) that has a flat surface co-planar with the polishing tape 206 when the substrate 110 is not present, the backing pad 208A (shown in FIG. 5A) may include a concave surface that matches the contour of the edge 202 of the substrate 110. Alternatively, as shown in FIG. 5B, the backing pad 208B (shown in FIG. 5B) may include a double concave surface to better match the contour of the edge 202 of the substrate 110.
In some embodiments, as shown in FIG. 5C, the backing pad 208C may have an adjustable amount of ability to conform to the substrate's edge 202. For example, the backing pad 208C may include an inflatable bladder 501, such that by adding more air or liquid or other fluid, the pad 208C may become harder, and by reducing the amount of air or liquid or other fluid in the bladder 501, the pad 208C may become more conforming. The bladder 501 may be filled (and/or emptied) via a fluid channel 502 with fluid from a fluid supply 504. In some embodiments, the fluid supply 504 may inflate/deflate the bladder 501 under the direction of an operator or a programmed and/or user operated controller. In such embodiments, an elastomeric material, such as silicon rubber or the like, may be used for the bladder 501 to further enhance the pad's 208C ability to stretch and conform to the substrate edge 202. Such an embodiment may allow an operator/controller to precisely control the surface area of contact between the polishing tape 206 and the substrate edge 202 by, e.g., limiting the amount of fluid pumped into the bladder 501. For example, once the substrate edge 202 is placed against the pad 208C with a deflated bladder 501, the bladder 501 may be inflated so that the pad 208C is forced to wrap around, and conform to, the polished and/or cut surfaces of the substrate edge 202, such as bevels or outer edges, and excluded regions (‘edge exclusion zone’) without wrapping around, or extending to, regions of the substrate 110 reserved for device fabrication. Note that in some embodiments, multiple bladders may be used in the pad 208, and that differently shaped inflatable bladders 501 may be used within differently shaped pads (e.g., 208, 208A, 208B).
FIG. 5D shows an embodiment of a ‘rolling’ backing pad 208D, which is formed in the shape of a wheel. The rolling backing pad 208D may be inflatable and/or rigid or inflatable and/or conforming. The rolling backing pad 208D may affect (e.g., increase or decrease) the frictional forces acting on the motion of the polishing tape 206 by rotating as the polishing tape 206 is indexed, and may thereby improve polishing performance.
The backing pads 208, 208A, 208B, 208C, 208D may be made of materials such as, for example, an acetal resin (e.g., Delrin® manufactured by DuPont Corporation), PVDF, polyurethane closed cell foam, silicon rubber, etc. Other materials may be used. Such materials may have resilience, or an ability to conform, that is a function of the thickness or density of the pad 208. The material may be selected based upon its resilience. The desired resilience may be selected based upon the type of polishing required. Any or all of the backing pads 208, 208A, 208B, 208C and 208D may be mounted off-center on the polishing head 204 to, for example, polish different areas on top and bottom surface of the substrate 110 or substrate edge 202.
As noted above with respect to FIG. 5C, in some embodiments, fluids used to aid in the polishing may be delivered to the substrate edge 202 via the pads 208, 208A, 208B, 208C, 208D. While the fluid channel 502 shown in FIG. 5C is coupled to the bladder 501, in alternate embodiments, the fluid channel 502 may be provided to drip or spray the fluid on or into the pads. Alternatively, the bladder 501 shown in FIG. 5C may have a semi-permeable membrane that allows fluid to be slowly released and transmitted to the polishing tape 206 (e.g., through the pad). In such embodiments, the pads 208, 208A, 208B, 208C, 208D may be covered by, made of, and/or include material that absorbs and/or retains the fluids used (e.g., polyvinyl alcohol (PVA), etc.).
FIG. 6A is a cross-sectional top view illustrating the load arm 314 of the polishing arm 201 according to an embodiment of the present invention, positioned to apply force onto the polishing tape 206 (not shown) and substrate edge 202 via the polishing head 204 and backing pad 208. As shown, in operation, when the actuator 318 (e.g., pneumatic cylinder) retracts in a direction (shown by the arrow on the right hand side of FIG. 6A) generally perpendicular to the longitudinal axis of the polishing arm 201 and away from the substrate 110 (for example, in response to an electrical or electromechanical signal), the retraction may cause a counter-clockwise motion of the pivot mechanism 316. In turn, the counter-clockwise motion of the pivot mechanism 316 may cause a forward motion of the load arm 314 towards the substrate 110 (as shown by the arrow on the left hand side of FIG. 6A). The forward motion of the load arm 314 may bring the head 204, backing pad 208, and polishing tape 206 (not shown) into contact with the edge 202 of the substrate 110. In other words, the load arm 314 may move the head 204 in a direction perpendicular, or substantially perpendicular, to the longitudinal axis 306 of the polishing arm 201. In some embodiments, the perpendicular motion may be achieved with a linear load arm, or may be approximated by a rotary load arm.
FIG. 6B is a cross-section top view illustrating the load arm 304 in a retracted position. In operation, when the actuator 318 extends in a direction perpendicular to the longitudinal axis of the polishing arm 201 and towards the substrate 110 (for example, in response to an electrical or electromechanical signal), the extension may cause a clockwise motion of the pivot mechanism 316. In turn, the clockwise motion of the pivot mechanism 316 may cause a backward motion of the load arm 314 away from the substrate 110, retracting the head 204 and backing pad 208. In this retracted position, no force is applied by the head 204 onto the polishing tape 206, and polishing does not occur.
The operation of the actuator 318 may be directed by the controller 120, which may be adapted to determine an amount of force to apply to the substrate 110, and amount of time to apply such force, etc.
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. For example, while the rotational axis of the rocker arm 304 has been shown to be coplanar and tangential to the edge 202 of the substrate 110, the rotational axis may be offset towards or away from the center of the substrate 110 to change polishing characteristics at or near the edge exclusion zone of the substrate 110.
Moreover, although only examples of cleaning a round substrate are disclosed, the present invention could be modified to clean substrates having other shapes (e.g., a glass or polymer plate for flat panel displays). Further, although processing of a single substrate by the module is shown above, in some embodiments, the module may process a plurality of substrates concurrently.
Accordingly, while the present invention has been disclosed in connection with exemplary embodiments thereof, it should be understood that other embodiments may fall within the spirit and scope of the invention, as defined by the following claims.

Claims

1. An apparatus adapted to polish an edge of a substrate comprising:

a polishing tape having a polishing surface and a second surface; and

a polishing arm having a longitudinal axis and adapted to force the polishing surface of the polishing tape into contact with an edge of a substrate, the polishing arm including:

a polishing head adapted to contact the second surface of the polishing tape;

a rocker arm coupled to the polishing head and adapted to rotate the polishing head around the longitudinal axis of the polishing arm; and

a load arm extending adjacent to the rocker arm and adapted to move the polishing head in a direction substantially perpendicular to the longitudinal axis of the polishing arm.

2. The apparatus of claim 1 wherein the polishing head is adapted to oscillate as it forces the polishing surface of the polishing tape into contact with the edge of the substrate.

3. The apparatus of claim 2, wherein the oscillation may be at least one of continuous and intermittent.

4. The apparatus of claim 1 further comprising a polishing pad coupled to the polishing head and adapted to contact the second surface of the polishing tape.

5. The apparatus of claim 4 further comprising a backing block adapted to couple the polishing pad to the polishing head.

6. The apparatus of claim 1 further comprising a rocker motor coupled to the rocker arm.

7. The apparatus of claim 6 wherein the rocker motor is adapted to rotate the rocker arm.

8. The apparatus of claim 1 further comprising an actuator coupled to the load arm.

9. The apparatus of claim 8, wherein the actuator is adapted to extend and retract the load arm, such that the polishing surface of the polishing tape is forced into contact with the edge of the substrate.

10. The apparatus of claim 9 further comprising a pivot mechanism adapted to couple the actuator to the load arm.

11. A system adapted to polish an edge of a substrate comprising:

a housing; and

one or more edge polishing apparatus, wherein the edge polishing apparatus comprises:

a polishing tape having a polishing surface and a second surface; and

a polishing head adapted to contact the second surface of the polishing tape;

12. The system of claim 11 further comprising a central platform positioned centrally to the one or more edge polishing apparatus.

13. The system of claim 12 wherein the central platform is adapted to support the substrate.

14. The system of claim 11 further comprising a controller.

15. The system of claim 14 wherein the controller is adapted to direct the operation of the system.

16. The system of claim 11 wherein the polishing head is adapted to oscillate as it forces the polishing surface of the polishing tape into contact with the edge of the substrate.

17. The system of claim 11 further comprising a rocker motor coupled to the rocker arm and adapted to rotate the rocker arm.

18. The system of claim 11 further comprising an actuator coupled to the load arm.

19. The system of claim 18 wherein the actuator is adapted to extend and retract the load arm, such that the polishing surface of the polishing tape is forced into contact with the edge of the substrate.

20. A method for polishing an edge of a substrate comprising:

retracting an actuator in a direction substantially perpendicular to the longitudinal axis of a polishing arm, and away from a substrate;

moving a pivot mechanism in a counter-clockwise direction in response to the retraction of the actuator;

extending a load arm forward towards the substrate in response to the movement of the pivot mechanism; and

contacting an edge of the substrate with a polishing tape in response to the forward movement of the load arm.

21. The method of claim 20 further comprising contacting the polishing tape with a backing pad in response to the forward movement of the load arm such that the polishing tape contacts the edge of the substrate.

22. The method of claim 21 wherein the backing pad is coupled to a head portion of the polishing arm.

23. The method of claim 22 further comprising oscillating the polishing head as it forces the polishing tape into contact with the edge of the substrate.

24. The method of claim 20 wherein an actuator is coupled to the load arm and adapted to extend the load arm.

25. The method of claim 20 wherein an actuator is coupled to the load arm and adapted to retract the load arm.