METHODS AND APPARATUS FOR CONTROLLING THE SIZE OF AN EDGE EXCLUSION ZONE OF A SUBSTRATE
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.
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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 APPLICATIONSThe 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 INVENTIONThe present invention relates generally to substrate processing, and more particularly to methods and apparatus for polishing an edge of a substrate.
BACKGROUND OF THE INVENTIONIn 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 INVENTIONIn 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.
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
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.
The edge polishing module 200 of
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
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
Turning to
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,
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
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
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.
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.
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).
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).
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:
- determining whether the preset width of the edge exclusion zone has been achieved; and
- 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.
Type: Application
Filed: May 20, 2008
Publication Date: Nov 27, 2008
Applicant: APPLIED MATERIALS, INC. (Santa Clara, CA)
Inventors: Zhenhua Zhang (San Jose, CA), Eashwer Kollata (Sunnyvale, CA), Sen-Hou Ko (Sunnyvale, CA)
Application Number: 12/124,132
International Classification: B24B 1/00 (20060101);