US20080293333A1

US20080293333A1 - Methods and apparatus for controlling the size of an edge exclusion zone of a substrate

Info

Publication number: US20080293333A1
Application number: US12/124,132
Authority: US
Inventors: Zhenhua Zhang; Eashwer Kollata; Sen-Hou Ko
Original assignee: Applied Materials Inc
Current assignee: Applied Materials Inc
Priority date: 2007-05-21
Filing date: 2008-05-20
Publication date: 2008-11-27
Also published as: TW200903619A; JP2008288600A

Abstract

In some embodiments, a method of controlling a width of an edge exclusion zone of a substrate is provided. The method includes determining a range of angles over which to rotate a polishing head; rotating the polishing head over the determined range of angles to achieve a preset width for an edge exclusion zone of the substrate; and polishing an edge of the substrate with the polishing head. Numerous other aspects are provided.

Description

The present application claims priority from U.S. Provisional 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) which is hereby incorporated by reference herein in its entirety.

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); and
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).

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, a buffer zone or ‘edge exclusion zone’ is provided between the device region and the edge of the substrate to protect the device region. Due to increasingly stringent requirements, precise control of the width of the edge exclusion zone has become a priority in order to optimize device yield. It has proven difficult to provide such precise control over the width of the edge exclusion zone. Accordingly, improved methods and apparatus for controlling polishing of an edge of a substrate to achieve control over the width of an edge exclusion zone are desired.

SUMMARY OF THE INVENTION

In a first aspect of the invention, a method of controlling a width of an edge exclusion zone on a substrate is provided. The method includes determining a range of angles over which to rotate a polishing head; rotating the polishing head over the determined range of angles to achieve a preset width for an edge exclusion zone of the substrate; and polishing an edge of the substrate with the polishing head.
In another aspect of the invention, a method of controlling a width of an edge exclusion zone on a substrate is provided. The method includes determining a radial position at which to place a polishing head with respect to a substrate so as to achieve a preset width of an edge exclusion zone for the substrate; moving the polishing head to the determined radial position; and polishing the substrate with the polishing head.
In yet another aspect of the invention, a method of controlling a width of an edge exclusion zone on a substrate is provided. The method includes providing a polishing head having a head spacer and a backing roller coupled to the head spacer at an off-center position and adapted to apply a polishing tape to a substrate during polishing; and applying the polishing tape to an edge exclusion zone of the substrate using the polishing head during polishing.
In another aspect of the invention, a system for controlling a width of an edge exclusion zone on a substrate is provided. The system comprises a polishing head having a head spacer, wherein the polishing head is adapted to contact the edge of a substrate; a backing pad coupled to the head spacer at an off-center position; a polishing arm coupled to the polishing head; and a controller adapted to operate the polishing head and polishing arm to control an edge exclusion zone of the substrate.
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 FIGURES

FIG. 1 is a schematic cross-sectional view of an edge of an exemplary substrate.

FIG. 2 is a schematic top view of an exemplary system for edge polishing according to an embodiment of the present invention.

FIG. 3 is a perspective view of an edge polishing apparatus according to an embodiment of the present invention.

FIG. 4 is a close-up perspective view of a polishing head according to an embodiment of the present invention.

FIG. 5A is a schematic cross-sectional view illustrating a method of controlling the width of the edge exclusion zone via the angular rotation of the polishing head according to an embodiment of the present invention.

FIG. 5B is a schematic cross-sectional view illustrating a method of controlling the width of the edge exclusion zone via the position of the polishing head over the substrate according to an embodiment of the present invention.

FIG. 5C is a schematic cross-sectional view illustrating a method of controlling the width of the edge exclusion zone via a head spacer offset according to an embodiment of the present invention.

FIG. 6 is a close-up perspective view of a head spacer according to an embodiment of the present invention.

FIG. 7 is a flow chart of an exemplary method of controlling the width of an edge exclusion zone via the angular rotation of a polishing head according to the present invention.

FIG. 8 is a flow chart of an exemplary method of controlling the width of an edge exclusion zone via the position of a polishing head over a substrate according to the present invention.

FIG. 9 is a flow chart of a method of controlling the width of an edge exclusion zone via a head spacer offset according to the present invention.

DETAILED DESCRIPTION

The present invention provides improved methods and systems for controlling a width of an edge exclusion zone on a substrate. The width of the edge exclusion zone of a substrate may be different for different electronic device manufacturers. The edge exclusion zone is typically positioned between a production or device region of the substrate and the substrate edge. While it is often desirable to polish the substrate edge, polishing the substrate in production or device region is undesirable. Therefore, the present invention provides methods and systems to control the width (e.g., polished width) of the edge exclusion zone of a substrate.
In one embodiment of the invention, precise control over the width of an edge exclusion zone may be provided by angularly translating (‘rocking’ ) a polishing head at different angles (‘rocking angles’), where a larger angular sweep causes a larger amount of material to be removed during polishing, and accordingly, an increased exclusion zone width.
In another embodiment of the invention, precise control over the width of an edge exclusion zone may be provided by controlling the position at which a polishing head applies polishing tape onto a substrate, and in particular, by controllably moving a polishing arm, including the polishing head, toward or away from the center the substrate. Movement of the polishing arm toward the center of the substrate may increase the width of the edge exclusion zone and movement of the polishing arm away from the center of the substrate may decrease the width of the edge exclusion zone.
In yet another embodiment of the invention, precise control over the width of an edge exclusion zone may be provided by offsetting a position of a backing pad (e.g., pad, bladder, roller on the like) in the polishing head so as to control the position of the backing pad relative to the substrate surface. In some embodiments, the offsetting may be provided using an off-center polishing head spacer element. In one or more embodiments, these methods may be used to control the width of the exclusion zones to sub-millimeter accuracy.
Turning to FIG. 1, a schematic cross-sectional view of a portion of a substrate 100 is provided. The 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′ upon which devices may be fabricated, and an exclusion region 108, 108′ (termed ‘edge exclusion zone’ herein) upon which device fabrication is not meant to occur. (Typically however, only one of the two major surfaces 102, 102′ will include a device region and an exclusion region). The edge exclusion zones 108, 108′ may serve as a buffer between the device regions 106, 106′ 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, 108′ of the two major surfaces 102, 102′ and may have surfaces aligned at an angle with respect to the major surfaces 102, 102′. In an edge polishing process, the bevels 112, 114 and/or the edge exclusion zones 108, 108′ may be polished to remove defects or contaminants, to reduce film thickness and more generally to improve surface uniformity.
Because the edge exclusion zones 108, 108′ occupy space unavailable for device fabrication, the width of the edge exclusion zones 108, 108′ tends to be minimized to increase product yield. However, if the widths of the edge exclusion zones 108, 108′ are too small, the zones 108, 108′ may no longer operate adequately as buffers, and the device regions 106, 106′ may be accidentally polished or otherwise adversely affected by edge polishing processes due to the close proximity between the edge 104 and the device regions 106, 106′. Moreover, the optimal width of the edge exclusion zones 108, 108′ may vary based on the size and type of substrate, the fabrication processes to be performed on the substrate, and/or other end-user specifications, which may be stringent. Thus, it is useful to have precise control over the width of the edge exclusion zones 108, 108′ to avoid unnecessary losses in yield while still maintaining the buffering function of the zones 108, 108′, and also to meet any other end-use requirements.
FIG. 2 shows a top view of an exemplary edge polishing system or ‘module’ 200 according to the present invention. The edge polishing module 200 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 substrates, and one or more cleaning modules for removing any dust or particles from the substrate 100 in addition to polishing modules, such as the edge polishing module 200. The substrate preparation system may be used to condition substrates for subsequent processes, such as etching, deposition, etc., or after such processes.
The edge polishing module 200 of FIG. 2 may include a housing 201 in which one or more edge polishing apparatuses 202, 204, 206 are positioned. Although the embodiment shown includes three (3) polishing apparatuses, other numbers of apparatuses may be used (e.g., 1, 2 or more than 3). The edge polishing apparatuses 202, 204, 206 are positioned surrounding a central platform 208 (shown in FIG. 3) upon which the substrate 100 may be mounted and supported. The central platform 208 may be rotatable by a driver 211 (e.g., motor, gear, belt, chain, etc.) (also shown in FIG. 3) and may include a vacuum chuck or other mechanism for holding the substrate 100 in place during rotation of the central platform 208. In the depicted embodiment, the substrate 100 is disk-shaped having major surfaces oriented in the horizontal plane. However, in alternative embodiments, the substrate 100 may have other shapes and orientations.
Each edge polishing apparatuses 202, 204, 206 may be coupled to, and supplied with, an abrasive polishing tape by a corresponding set of polishing tape spools 212, 214, 216. Each set of polishing tape spools 212, 214, 216 may include a supply spool and a take-up spool (shown in FIG. 3). The supply spools may store unused polishing tape available to be unwound and pulled into the corresponding polishing apparatuses 202, 204, 206 positioned adjacent to the substrate 100, 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 apparatuses 202, 204, 206.
The edge polishing module 200 may also include a controller 220 (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 202, 204, 206, the driver 211, and/or sets of spools 212, 214, 216. In one or more embodiments, each polishing apparatus 202, 204, 206 may be equipped with its own controller. The controller 220 may include or be coupled to memory resources (e.g., DRAM, ROM, flash memory, optical disk, local area network (LAN) storage) (not shown). In one or more embodiments, the controller 220 may be adapted to access data related to operation of the edge polishing module 200 which may be stored in query-accessible databases stored within the memory resources.
In addition, the edge polishing module 200 may include one or more sensors (e.g., optical sensors 300 such as light sources and detectors such as photometers) (not shown) adapted to measure the width of the edge exclusion zones 108, 108′ on the substrate 100. For example, the sensor 300 may direct a light beam toward the edge exclusion zone of the substrate 100. The amount of light reflected back to and detected by the sensor 300 may determine a width of the edge exclusion zone of the substrate. Alternatively, a camera may directly measure the width of the edge exclusion zone. Further, a camera may image the substrate and image processing software may determine the width of the edge exclusion zone based on the image. Any suitable measurement system may be used.
Each edge polishing apparatus 202, 204, 206 may be adapted to load the polishing tape forcibly into contact with the edge 104 of the substrate 100 when supplied with polishing tape from corresponding sets of spools 212, 214, 216, as described in greater detail below. The friction (e.g., abrading contact) between the polishing tape 306 (shown in FIG. 3) and the substrate edge 104 may include the torque exerted during rotation of the substrate 100 against the polishing tape 306 and the force exerted in pressing the polishing tape 306 onto the edge 104 of the substrate 100. In some embodiments, the combined force at the point(s) of contact may range from about 0.5 lbs. to about 2.0 lbs. Other amounts of force may be used.
Turning to FIG. 3, a schematic view of an edge polishing apparatus, e.g., 202, is depicted. The apparatus 202 may include a polishing arm 301 aligned in the horizontal plane approximately tangential to the edge 104 of the substrate 100. The polishing arm 301 may be supported by a frame 303. In other embodiments, the polishing arm 301 may be aligned differently, for example, vertically, or at an angle with respect to the horizontal plane. The polishing arm 301 may include a polishing head section 304 (‘head’) adapted to receive the polishing tape 306 from the a set of spools including a supply spool 308 and a take-up spool 310, and to forcibly apply the polishing tape 306 to the edge 104 of the substrate 100 as the substrate 100 is rotated by the central platform 208 or by some other mechanism (e.g., drive rollers). The spools 308, 310 may be driven by one or more drivers (e.g., servo motors) which may provide both an indexing capability to allow a specific amount of unused polishing tape 306 to be advanced or continuously fed to the substrate edge 104, and a tensioning capability to allow the polishing tape 306 to be stretched taught and to apply pressure to the substrate edge 104. In some embodiments, the spools 308, 310 may be approximately 1 inch in diameter, hold about 500 inches of polishing tape 306, and may be constructed from any suitable materials such as polyurethane, polyvinyl difluoride (PVDF), etc. Other materials and spool dimensions may be used. As shown in FIG. 3, the spools 308, 310 may be oriented vertically so that the footprint occupied by the entire edge polishing module 200 and polishing apparatus 202 may be minimized.
Additionally, the polishing tape 306 may further be pulled taught by one or more tensioning rollers 312 positioned on the head 304 (as shown) or in other locations. The tensioning roller(s) 312 may be adapted to apply a variable amount of tension to the substrate edge 104 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 100 as material is removed from the edge 104 and/or edge exclusion zones 108, 108′.
In one or more embodiments, the polishing tape 306 may be made from many different materials including aluminum oxide, silicon oxide, silicon carbide, etc. Other materials may also be used. In some embodiments, the abrasives used may range from about 0.5 microns up to about 3 microns in size although other sizes may be used. Different widths of polishing tape 306 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 306 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 (described below), and from about 3 to about 8 lbs. of tension in embodiments without a pad. Other polishing tapes 306 having different thicknesses and strengths may be used.
Edge polishing may be performed using one or more polishing apparatuses (e.g., 202, 204, 206). In one or more embodiments, a plurality of polishing apparatuses (e.g., 202, 204, 206) may be employed, in which each polishing apparatus may have similar or different characteristics and/or mechanisms. In the latter case, particular polishing apparatuses may be employed for specific operations. For example, one or more of a plurality of polishing apparatuses may be adapted to perform relatively rough polishing and/or adjustments while another one or more of the plurality of polishing apparatus may be adapted to perform relatively fine polishing and/or adjustments. For example, in some embodiments, the various polishing apparatus 202, 204, 206, of the edge polishing module 200 may support different types of polishing tape 306 (e.g., tapes of different abrasive grits) which may be used concurrently, in a predefined sequence, or at different times. The heads (e.g., 304) of the polishing apparatus 202, 204, 206 may also be disposed in different positions to allow the supported tapes to polish different portions of the edge 104 of the rotating substrate 100. In this manner, polishing apparatuses (e.g., 202, 204, 206) 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 (e.g., 202, 204, 206) may be located in a single chamber or module (e.g., 200), or alternatively, one or more polishing apparatuses 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 in the separate chambers may be used in series or otherwise.
The head 304 may be angularly translated around an axis tangential to the substrate edge 104, so as to apply force onto the substrate edge 104 at different angles. The angular translation may be oscillatory such that the head 304 ‘rocks’ back and forth over and under the substrate edge 104. For example, FIG. 4 shows a close-up perspective view of an exemplary polishing head 304 positioned to apply the polishing tape 306 to the edge 104 of the substrate 100 according to an embodiment of the present invention. The head 304 may be coupled (e.g., rigidly) to the polishing arm 301 of the polishing apparatus 202 via a rocker arm 402 (a portion of which is shown in FIG. 4) and/or other components of the polishing arm 301 such as an actuator or load arm (not shown). The head 304 includes a frame 401 coupled to the rocker arm 402 which supports tension rollers 406 (only one shown in the figure) adapted to receive and tension the polishing tape 306 delivered from the supply spool 308. The polishing tape 306 may be fed to a backing roller 408 while it is pulled taught by the tension rollers 406. The backing roller 408 may comprise a rotatable pad shaped in the form of a roller and may be pressed toward the substrate edge 104 (via an actuator, not shown). The pressure on the backing roller 408 may cause the backing roller 408 and/or the polishing tape 306 (or portions thereof) to contour to the substrate edge 104 during polishing. The backing roller 408 may provide reduced friction to the polishing tape 306 in comparison to stationary backing pads. However, other backing pads, rolling or stationary, may be used.
The backing roller 408 may be rotationally coupled to a head spacer 410 (e.g., by a pin joint, bolts, etc.), which, in turn may be coupled to the rocker arm 402. As depicted, the rocker arm 402 may have a c-shaped cross-section having an interior space in which the head spacer 410 may be positioned. In some embodiments of the present invention, the backing roller 408 may be coupled to the head spacer 410 at an off-center position of the head spacer 410. This off-center coupling may provide an additional degree of control over edge polishing, and in particular, the width of the edge exclusion zones 108, 108′ as discussed in greater detail below with reference to FIG. 6C.
The rocker arm 402 may be adapted to rotate around a longitudinal axis tangential to the edge 104 of the substrate 100. The longitudinal axis may be coincident with the rotational axis of the backing roller 408 or, more preferably, may be positioned some distance therefrom so that when the head 304 is rotated at a sufficient rocking angle, the backing roller 408 may be angularly translated (as opposed to simply rotated) above or below the substrate 100. The present invention provides adjustability of the rocking angle and thereby provides control over the angular translation of the backing roller 408 (and thus, the polishing tape 306) with respect to the surface of the substrate 100 to be polished. It has been found such adjustability enables precise control over the level of polishing at or near the edge exclusion zones 108, 108′.
The rocking angle may be defined with respect to a reference line (Y-Y′) (shown in FIG. 5A) along the frame 401 of the polishing head 304. In the embodiment of the polishing head 304 depicted in FIG. 4 the reference line (Y-Y′) (shown in FIG. 5A) is aligned perpendicular to the longitudinal rotational axis of the head 304. When the reference line is vertically aligned (e.g., when reference line (Y) is perpendicular to the horizontal plane of substrate 100, as shown in FIG. 5A) with the backing roller 408 pointed toward the substrate edge 104, the rocking angle is defined as zero. In FIG. 5A, a positive rocking angle may be defined as a clockwise rotation from zero (indicated by the bold dashed curved arrow in FIG. 5A) in which the backing roller 408 (or a portion thereof) is angularly translated over the top surface 102 of the substrate 100. A negative rocking angle may be defined as a counterclockwise rotation from zero in which the backing roller 408 (or a portion thereof) is angularly translated under the bottom major surface 102′ of the substrate 100. Thus, FIG. 4 depicts the head 304 at a negative rocking angle with the rolling pad 408 and portions of the frame 401 positioned beneath (and obscured by) the bottom major surface 102′ of the substrate 100.
FIG. 5A is a schematic cross-sectional view illustrating an inventive method of controlling edge exclusion width by controlling the angular rotation of the polishing arm 301. As shown, when the head 304, including the rocking arm 402 and backing roller 408, is in the first position at an angle (θ₁) with respect to the (Y-Y′) line, the backing roller 408 and associated polishing tape (not shown) is positioned over the bevel 112 portion of the substrate 100 and is not in position to polish the edge exclusion region 108 of the substrate 100. The rocker arm 402 may be rotated to sweep from the first position at angle θ₁to a second position at angle θ₂. As can be discerned, when the rocker arm 402 is rotated to the second position at angle (θ₂) with respect to the (Y-Y′) line (shown in phantom), the backing roller 408 and associated polishing tape (not shown) are positioned directly over the edge exclusion zone 108, and may be applied to polish the substrate 100 at this position. In this manner, the angular sweep of the rocking arm 402 and the polishing head 304 may determine the width of the edge exclusion zone 108. For example, by sweeping the head 304 from 60 degrees to 80 degrees, as opposed to sweeping the head 304 from 60 degrees to 70 degrees, a greater amount of material may be removed, and consequently the width of the edge exclusion zone 108 may be increased approximately one millimeter, for example.
The controller 220 may determine a suitable angular sweep to achieve a preset desired edge exclusion zone width based on known polishing profiles, which relate expected (e.g., experimentally determined) amounts of material removed during polishing at various substrate positions to angular sweep. Such profiles may be stored, for example, in one or more databases accessible by the controller 220. The controller 220 may then send control signals to operate the rocker arm 402, based on the determined suitable angular sweep.
FIG. 5B is a schematic cross-sectional view illustrating an alternative method of controlling edge exclusion width via the position of the polishing arm 301 over the substrate 100. The polishing arm 301 may be moved, and/or rotated, such that the head 304 is moved in a radial direction toward or away from the center of the substrate 100. As shown in FIG. 5B, a centerline (bold dashed line) of the head 304 (e.g., backing roller 408) can be moved inwardly from a first position (X1) to a second position (X2), thereby moving the head 304 and backing roller 408 (shown in phantom) closer to the center of the substrate 100. If, for example, position X1 represents a first end of the edge exclusion zone 108, the distance from X1 to X2 (Δ) may represent a corresponding change (e.g., increase) in the polished width of the edge exclusion zone 108 as the backing roller 408 and associated polishing tape (not shown) is applied to polish the edge exclusion zone 108 of the major surface 102 of the substrate 100. In this manner, the distance that the head 304 is moved in a radial direction may determine the width of the edge exclusion zone 108. According to embodiments of this method, the controller 220 may control the movement and/or rotation of the polishing arm 301 and position of the head 304 to achieve the preset desired exclusion zone width.
FIG. 5C is a schematic cross-sectional view illustrating an inventive method of controlling edge exclusion width via the polishing head spacer 410 in an offset position. FIG. 6 is a perspective view of an example embodiment of the head spacer 410 according to the present invention. The head spacer 410 comprises a first section 602 and a second section 604. The second section 604 may be conjoined longitudinally in a staggered fashion to the first section 602 at a first end (not shown) and having a free second end 606. The free end 606 may include an opening 608 adapted to receive and rotatably couple the backing roller 408. In one or more embodiments, the opening 608 may be positioned off-center transverse to the longitudinal direction (e.g., the direction in which the first and second sections 602, 604 of the head spacer 410 are joined). In some embodiments, as shown in FIG. 5C, when the opening 608 is positioned centrally on the free end 606 of the head spacer 410, the centerline of the backing roller 408 is positioned at a first position (X3) (shown in FIG. 5C). When the opening 608 is offset a distance (D) toward the center of the substrate 100, the centerline of the head moves a corresponding distance (D) to a position (X4) (shown in FIG. 5D) closer to the center of the substrate 100 (shown in phantom). Alternatively, the amount by which the first and second sections 602, 604 are staggered may be adjusted while leaving the opening 608 centrally positioned in the free end 606 of the head spacer 402 to similarly move the opening 608 by the distance (D). The distance (D) of the offset of opening 608 may cause a corresponding change (e.g., increase) in the polished width of the edge exclusion zone 108, as the backing roller 408 and associated polishing tape (not shown) are applied to polish the edge exclusion zone 108. In this manner, the offset distance (D) of the opening 608 may determine the width or change in width of the edge exclusion zone 108.
It is noted that the change in the width of the edge exclusion zone 108 may not precisely correspond to (e.g., may be different than) the offset distance (D), due, for example, to rotational and/or angular movements of the polishing arm 301 and head 304 when applied to the substrate 100 during polishing operations. Known profiles relating expected (e.g., experimentally-determined) amounts of material removed during polishing at various offset distances (D) may be stored in one or more databases (not shown) accessible by the controller 220, and used to determine positional adjustments, such as the rotational and positional changes described above, that may be made to achieve the preset desired exclusion zone width.
Accordingly, each of the methods described above may be used alone or in combination, and in sequence or concurrently, to achieve a preset desired exclusion zone width.
FIG. 7 is a flow chart illustrating an example method 700 of controlling the width of the edge exclusion zone via angular rotation of the polishing head according to the present invention. In step S702, the method 700 beings. In step S704, a desired edge exclusion zone width is preset. A user may pre-set the edge exclusion zone width by inputting a width value into the controller 220, or the pre-set edge exclusion zone width may be determined automatically, based on input values, such as, the substrate size and the type(s) of devices to be fabricated on the substrate 100. In step S706, a range of rocking angles (e.g., the angular sweep) of the polishing arm 301 and head 304 may be determined by the controller 220, based on the preset edge exclusion zone width. As noted above, the controller 220 may access one or more databases having polishing profile information in making this determination. In step S708, the controller 220 sends control signals to the polishing arm 301 and head 304 to rotate at the determined rocking angles during polishing.
In step S710, it is determined, by the controller 220, whether the edge exclusion zone width has been attained, or is within a tolerance range of being reached. The determination may be made by measuring the actual edge exclusion width, using sensors for example, and comparing the measured edge exclusion zone width to the preset desired edge exclusion zone width, for example. Other measurement means may be used. If in step S710, the edge exclusion width has not been attained, and is not within the tolerance range, the method proceeds to step S712, in which the controller 220 determines an adjustment to be made to the rocking angle range of the polishing arm 301 and head 304 to attain the preset edge exclusion zone width (e.g., based on a difference between a measured exclusion zone width and the preset exclusion zone width). In step S714, the controller 220 sends control signals to the polishing arm 301 and head 304 to operate at the adjusted range of rocking angles during polishing. After step S714, the method cycles back to step S710. If in step S710, it is determined, by the controller 220, that the edge exclusion zone width has been attained, or is within a tolerance range, the method ends in step S716. In some embodiments, actual edge exclusion width is not checked for each substrate (e.g., is only checked initially, periodically or at some other time(s), if at all).
FIG. 8 is a flow chart illustrating an example method 800 of controlling the width of the edge exclusion zone via the position of the polishing arm 301 over the substrate 100 according to the present invention. In step S802 the method 800 beings. In step S804, a desired edge exclusion zone width is preset. As described above with respect to FIG. 7, a user may pre-set the edge exclusion zone width by inputting a width value into the controller 220, or the pre-set edge exclusion zone width may be determined automatically, based on input values, such as, the substrate size and the type(s) of devices to be fabricated on the substrate 100. In step S806, a radial position of the polishing arm 301 and head 304, with respect to the substrate 100, is determined by the controller 220, based on the preset edge exclusion zone width. In step S808, the controller 220 sends control signals to the polishing arm 301 to move and/or rotate the polishing arm 301 (e.g., in the horizontal plane), thereby moving the head 304, to the determined radial position. Polishing then is performed.
In step S810, it is determined, by the controller 220, whether the edge exclusion zone width has been attained, or is within a tolerance range of being reached. The determination may be made by measuring the actual edge exclusion width, using sensors, for example, and comparing the measured edge exclusion zone width to the preset desired edge exclusion zone width, for example. If in step S810, the edge exclusion width has not been attained, and is not within the tolerance range, the method proceeds to step S812, in which the controller 220 determines an adjustment to be made to the radial position of the head 304, adapted to attain the preset edge exclusion zone width (e.g., based on a difference between a measured exclusion zone width and the preset exclusion zone width). In step S814, the controller 220 sends control signals to the polishing arm 301 and head 304 to move to the adjusted radial position; and polishing is performed. After step S814, the method cycles back to step S810. If in step S810, it is determined, by the controller 220, that the edge exclusion zone width has been attained, or is within a tolerance range, the method ends in step S816. In some embodiments, actual edge exclusion width is not checked for each substrate (e.g., is only checked initially, periodically or at some other time(s), if at all).
FIG. 9 is a flow chart illustrating an example method 900 of controlling the width of the edge exclusion zone via a head spacer offset according to the present invention. In step S902 the method 900 beings. In step S904, a desired edge exclusion zone width is preset. As described above with respect to FIGS. 7 and 8, a user may pre-set the edge exclusion zone width by inputting a width value into the controller 220, or the pre-set edge exclusion zone width may be determined automatically, based on input values, such as, the substrate size and the type(s) of devices to be fabricated on the substrate 100. In step S906, a head spacer 410, having an offset opening 608 adapted to couple to a backing roller 408, is provided, in which the offset distance (D) is comparable to the edge exclusion width. In step S908, the controller 220 sends control signals to operate the polishing arm 301 and head 304, with the backing roller 408 at the offset position.
In step S910, it is determined, by the controller 220, whether the edge exclusion zone width has been attained, or is within a tolerance range of being reached. The determination may be made by measuring the actual edge exclusion width, using sensors, for example, and comparing the measured edge exclusion zone width to the preset desired edge exclusion zone width. If in step S910, the edge exclusion width has not been attained, and is not within the tolerance range, the method proceeds to step S912, in which the controller 220 determines an adjustment to be made to one or more of, a rocking angle range, or a radial head position, adapted to attain the preset edge exclusion zone width. In step S914, the controller 220 sends control signals to the polishing arm 301 and head 304 to move and/or rotate according to the determined adjustment. Polishing may then be performed. After step S914, the method cycles back to step S910. If in step S910, it is determined, by the controller 220, that the edge exclusion zone width has been attained, or is within a tolerance range, the method ends in step S916. In some embodiments, actual edge exclusion width is not checked for each substrate (e.g., is only checked initially, periodically or at some other time(s), if at all).
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 instance, 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 apparatus is shown above, in some embodiments, the apparatus 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. A method of controlling a width of an edge exclusion zone on a substrate comprising:

determining a range of angles over which to rotate a polishing head;

rotating the polishing head over the determined range of angles to achieve a preset width for an edge exclusion zone of the substrate; and

polishing an edge of the substrate with the polishing head.

2. The method of claim 1 further comprising:

determining whether the preset width of the edge exclusion zone has been achieved; and

adjusting the range of angles over which to rotate the polishing head to achieve the preset width for the edge exclusion zone based on the determination of whether the preset width of the edge exclusion zone has been achieved.

3. The method of claim 1 further comprising:

applying a polishing tape to the substrate via the polishing head during polishing to achieve the preset width of the edge exclusion zone.

4. The method of claim 1 further comprising:

operating the polishing head via a controller.

5. The method of claim 1 wherein the polishing head includes a backing roller.

6. The method of claim 5 further comprising:

pressing the backing roller against a polishing tape to contact the substrate.

7. The method of claim 2 further comprising:

measuring an actual edge exclusion width to determine whether the preset width of the edge exclusion zone has been achieved.

8. The method of claim 7 further comprising:

comparing the actual edge exclusion width to the preset edge exclusion width to determine whether the preset width of the edge exclusion zone has been achieved.

9. The method of claim 7, further comprising measuring the actual edge exclusion width via one or more sensors.

10. A method of controlling a width of an edge exclusion zone on a substrate comprising:

determining a radial position at which to place a polishing head with respect to a substrate so as to achieve a preset width of an edge exclusion zone for the substrate;

moving the polishing head to the determined radial position; and

polishing the substrate with the polishing head.

11. The method of claim 10 further comprising:

adjusting the radial position of the polishing head to achieve the preset width of the edge exclusion zone based on the determination of whether the preset width of the edge exclusion zone has been achieved.

12. The method of claim 10 further comprising:

rotating the polishing head when the polishing head is in contact with the substrate.

13. The method of claim 12 further comprising:

applying a polishing tape to the substrate via the rotating polishing head to achieve the preset width of the edge exclusion zone.

14. A method of controlling a width of an edge exclusion zone on a substrate comprising:

providing a polishing head having a head spacer and a backing roller coupled to the head spacer at an off-center position and adapted to apply a polishing tape to a substrate during polishing; and

applying the polishing tape to an edge exclusion zone of the substrate using the polishing head during polishing.

15. The method of claim 14 further comprising:

determining whether a preset width of the edge exclusion zone has been attained; and

adjusting at least one of a range of angles over which to rotate the polishing head and a radial position of the polishing head based on the determination of whether the preset width of the edge exclusion zone has been attained.

16. The method of claim 14 further comprising:

operating the polishing head via a controller.

17. The method of claim 15 further comprising:

measuring an actual edge exclusion width to determine whether the preset width of the edge exclusion zone has been attained.

18. A system for controlling a width of an edge exclusion zone on a substrate comprising:

a polishing head having a head spacer, wherein the polishing head is adapted to contact an edge of a substrate;

a backing pad coupled to the head spacer at an off-center position;

a polishing arm coupled to the polishing head; and

a controller adapted to operate the polishing head and polishing arm to control an edge exclusion zone of the substrate.

19. The system of claim 18 further comprising a polishing tape, wherein the polishing head is adapted to press the polishing tape against the edge of the substrate.

20. The system of claim 18 wherein the polishing head is adapted to angularly translate at different angles about the edge of the substrate.

21. The system of claim 18 wherein the polishing arm is adapted to move to accommodate exclusion zones with different widths.

22. The system of claim 18 wherein the backing roller is adapted to apply a polishing tape to the substrate edge during polishing.