The present application claims priority from the following U.S. patent applications, each of which is hereby incorporated by reference herein in its entirety:
U.S. Provisional 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. Provisional 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); and
U.S. Provisional Patent Application Ser. No. 61/046,799, filed Apr. 21, 2008, entitled “APPARATUS AND METHODS FOR POLISHING A NOTCH OF A SUBSTRATE USING A POLISHING WHEEL” (Attorney Docket No. 11540/L).
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/PPC/CMP/CKIM);
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/PPC/CMP/CKIM);
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. 60/939,342, 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 cleaning a notch in an edge of a substrate.
BACKGROUND OF THE INVENTION Conventional systems, which contact a notch in the edge of a substrate with an abrasive film or tape to clean the notch, may not be able to contact all parts of the notch with the abrasive tape. As a result, these conventional systems may not be able to clean or polish all parts of the notch. Accordingly, effective methods and apparatus for cleaning or polishing all parts of notches in the edges of substrates are desired.
SUMMARY OF THE INVENTION In aspects of the invention, an apparatus is provided for polishing a notch of a substrate using a polishing tape. The apparatus comprises a polishing head adapted to apply the polishing tape against the notch of the substrate, including: a polishing pad having a cavity adapted to be filled with a pressure-controlled medium; and a tip region having a shape that corresponds to a shape of the notch, wherein the polishing pad is adapted to contact the polishing tape and press the polishing tape against the notch.
In other aspects of the invention, an apparatus is provided for polishing a notch of a substrate using a polishing tape. The apparatus comprises a polishing head adapted to apply the polishing tape against the notch of the substrate, comprising: a polishing pad having a tip region having a shape that corresponds to a shape of the notch, the polishing pad adapted to contact the polishing tape and press the polishing tape against the notch; and one or more guides which are adapted to prevent the polishing tape from moving out from between the polishing pad and the notch.
In yet other aspects of the invention, an apparatus for polishing a notch of a substrate using a polishing tape is provided. The apparatus comprises a polishing head adapted to apply the polishing tape against the notch of the substrate, including: a polishing pad including one or more slots for guiding the polishing tape; and a notch polishing pad embedded in the polishing pad and adapted to contact the polishing tape and press the polishing tape against the notch.
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 illustration of a cross-section of a portion of a substrate.
FIG. 2 is a schematic plan view of an embodiment of a system for polishing parts of a substrate, including major surfaces, edge, bevel, and notch in accordance with the present invention.
FIG. 3 is a schematic perspective view of a first embodiment of a polishing apparatus for polishing a substrate notch in accordance with the present invention.
FIG. 4 is a schematic perspective view of a second embodiment of a polishing apparatus for polishing a substrate notch in accordance with the present invention.
FIG. 5 is a schematic illustration of part of a substrate, including a substrate notch.
FIG. 6 is a schematic perspective view of a portion of an embodiment of the notch polishing apparatus of FIG. 3.
FIG. 7 is a schematic cross-sectional view of an embodiment of a polishing wheel in accordance with the present invention.
FIG. 8 is an enlarged schematic cross-sectional view of a portion of the polishing wheel of FIG. 7, in the region of FIG. 7 enclosed by a dashed circle and labeled FIG. 8.
FIGS. 9A and 9B are schematic perspective views of a portion of an embodiment of the notch polishing apparatus of FIG. 3.
FIG. 10A is a schematic plan view of an alternate embodiment of a notch polishing apparatus provided in accordance with the present invention.
FIG. 10B is a schematic plan view of another embodiment of the notch polishing apparatus of FIG. 10A.
FIG. 10C is a schematic side view of the notch polishing apparatus of FIG. 10A.
FIG. 11 is a schematic perspective view of an embodiment of a supporting polishing pad for polishing a substrate notch provided in accordance with the present invention.
FIG. 12 is a schematic perspective view of part of the embodiment of a polishing apparatus for polishing a substrate notch, similar to the polishing apparatus of FIG. 3, which employs the supporting polishing pad of FIG. 11.
FIG. 13 is a schematic cross-sectional view of the supporting polishing pad of FIG. 11.
FIG. 14 is a schematic cross-sectional view of an alternative embodiment of a supporting polishing pad, whose notch polishing pad contains a bore in accordance with the present invention.
FIG. 15 is a schematic cross-sectional view of a further embodiment of a supporting polishing pad in accordance with the present invention.
FIG. 16 is a schematic cross-sectional view of a further embodiment of a supporting polishing pad, whose notch polishing pad contains a bore in accordance with the present invention.
FIG. 17 is a flow chart of a method for polishing a substrate notch provided in accordance with the present invention.
FIG. 18 is a flow chart of an alternative method for polishing a substrate notch provided in accordance with the present invention.
DETAILED DESCRIPTION Substrates used in semiconductor processing often have films and/or surface defects which typically should be removed prior to subsequent processing steps. In some cases, these films and defects may occur on the edge of a substrate, including notches formed thereon.
The present invention provides apparatus and methods that effectively adapt to various shapes of notches found in different substrates, ensure good contact of a polishing tape or film with all sections of a substrate notch region, and remove thin films and surface defects at a substrate notch.
In one or more embodiments, a polishing wheel or pad may be provided. The polishing wheel or pad may be adapted to press a moving polishing tape against the substrate notch. The polishing wheel or pad may include a tip region that substantially conforms to the shape of the substrate notch.
In some embodiments, the polishing wheel or pad may be hollow and filled with a resilient material or be made entirely from a resilient material. In some embodiments the polishing pad may be made from PTFE, PEEK, Delrin, ceramics, or stainless steel, for example. Other suitable materials may be used. In some embodiments, the polishing pad may have a hardness of about 60-70 Shore A durometers, for example. Materials having more or less hardness may be used. In alternative embodiments, the polishing wheel or pad may be hollow and filled with a pressure-controlled fluid to effectively press the polishing tape against all sections of the substrate notch.
Turning to FIG. 1, a substrate 100 may include two major surfaces 102, 102′ and an edge 104. Each major surface 102, 102′ of the substrate 100 may include a device region 106, 106′ and an exclusion region 108, 108′. (Typically however, only one of the two major surfaces 102, 102′ will include a device region and an exclusion region.) The exclusion regions 108, 108′ may serve as buffers between the device regions 106, 106′ and the edge 104. The edge 104 of 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′. A notch 116 may be located in the edge 104 of the substrate 100, and used to align/position the substrate 100 during various processing steps (e.g., lithography, deposition, etching, cleaning, etc.). The present invention is adapted to polish the notch 116.
FIG. 2 is a schematic plan view of an exemplary embodiment of a system 200 for polishing parts of the substrate 100, including the major surfaces 102, 102′, the edge 104, and/or the notch 116. The system 200 of FIG. 2 includes three polishing apparatuses 202, each including a polishing head 204. However, any number and type of apparatus 202/heads 204 may be used in any practicable combination. In addition, in such multi-head embodiments, each head 204 may use a differently configured or type of a polishing tape (e.g., different grits, materials, tensions, pressures, etc.) to contact and polish the substrate notch 116. Any number of heads 204 may be used concurrently, individually, and/or in any sequence. The heads 204 may be disposed in different positions and in different orientations (e.g., aligned with the substrate notch 116, normal to the substrate notch 116, angled relative to the substrate notch 116, etc.) to allow polishing tape, pushed by a pad in some embodiments (FIG. 3), to polish different portions of the notch 116 of the substrate 100.
In some embodiments, one or more of the heads 204 may be adapted to be oscillated or moved (e.g., angularly translated about a tangential axis of the substrate 100 and/or circumferentially relative to the substrate 100) around or along the substrate notch 116 so as to polish different portions of the substrate notch 116. In some embodiments, one or more of the heads 204 may be adapted to continuously or intermittently oscillate between the various positions. Alternatively, one or more of the heads 204 may be fixed and/or only adjusted while the substrate 100 is not being rotated. In yet other embodiments, the substrate 100 may be held fixed while one or more of the heads 204 oscillate (as described above) as well as rotate circumferentially around the substrate 100. This movement may be under the direction of a programmed or user operated controller 205, described below. Different heads 204 may be used for different substrates 100 or different types of substrates 100.
As described above, the system 200 may further include the controller 205, (e.g., a programmed computer, a programmed processor, a microcontroller, a gate array, a logic circuit, an embedded real time processor, etc.), which may control the driver(s) used to rotate the substrate 100 and/or the actuator(s) used to push a polishing pad(s) (FIG. 3) against the substrate notch 116. Note that the controller 205 may be coupled (e.g., electrically, mechanically, pneumatically, hydraulically, etc.) to each of a plurality of actuators. Likewise, the controller 205 may be adapted to receive feedback signals from one or more drivers and/or actuators, that indicate the amount of energy being exerted to rotate the substrate 100 (e.g., rotate a vacuum chuck holding the substrate 100) and/or actuate the actuator(s) to push the polishing pad(s) against the substrate 100. These feedback signals may be employed to determine when a particular layer of film has been removed and/or whether a sufficient amount of polishing has occurred.
As mentioned above, substrate polishing may be performed using one or more polishing apparatuses 202. In one or more embodiments, a plurality of polishing apparatuses 202 may be employed, in which each polishing apparatus 202 may have similar or different characteristics and/or mechanisms. In the latter case, particular polishing apparatuses 202 may be employed for specific operations. For example, one or more polishing apparatuses 202 may be adapted to perform relatively rough polishing and/or adjustments while another one or more polishing apparatus 202 may be adapted to perform relatively fine polishing and/or adjustments. Polishing apparatuses 202 may be used in sequence so that, for example, a rough polishing procedure may be performed initially and a fine polishing procedure may be employed subsequently as needed or according to a polishing recipe. The plurality of polishing apparatuses 202 may be located in a single chamber or module, as shown herein, or alternatively, one or more polishing apparatuses 202 may be located in separate chambers or modules. Where multiple chambers are employed, a robot or another type of transfer mechanism may be employed to move substrates between the chambers so that polishing apparatuses 202 in the separate chambers may be used in series or otherwise.
FIG. 3 is a schematic perspective view of a second exemplary embodiment of a polishing apparatus 300 for polishing a substrate notch 116. The polishing apparatus 300 may include a substrate driver 302 (e.g., a servomotor, gear, belt, chain, etc.), which may be mounted on a pedestal 304. A support 306 (e.g., a vacuum chuck) may be coupled (e.g., rigidly) to a shaft (not shown) of the substrate driver 302. The support 306 may support the substrate 100, for example. The substrate driver 302 may rotate the substrate 100, via the support 306, about a center 308 of the substrate 100 or another suitable axis. The substrate driver 302 may be connected to a substrate driver control unit, such as the controller 205, for example, which may control the angular displacement, angular velocity, and/or angular acceleration of the substrate 100. The polishing apparatus 300 may further include a polishing arm 310 aligned in the horizontal plane approximately tangential to an edge of the substrate 100 and supported by a frame 312. The frame 312 may be coupled at one end to a polishing head driver 309. In other embodiments, the polishing arm 310 may be aligned differently, for example, vertically or at an angle with respect to the horizontal plane. The polishing arm 310 may include a polishing head section 314 (‘head’). The polishing head 314 may include a backing or polishing pad 316. The polishing pad 316 may be wheel-shaped, as shown herein, or the polishing pad 416 may be relatively or substantially planar in shape, as shown in FIG. 4. Other shapes may be used. The polishing pad 316 may be moved toward or away from the substrate 100 by an actuator (e.g., hydraulic actuator, pneumatic actuator, servomotor, etc.) (not shown). Polishing tape 318, may wrap around the polishing head 314, and guide rollers 320, 322 and over the polishing pad 316, and be tensioned between spools 324, 326. The spools 324, 326 may be driven by spool drivers 328, 330 (e.g., servomotors), respectively. The spool drivers 328, 330, may be moved continuously or indexed to precisely control the amount of the polishing tape 318 that is advanced over the polishing head 314 from, for example, the spools 324, 326, in order to polish the substrate notch 116.
In one or more embodiments, the abrasive component of the polishing tape 318 may be made from many different materials, such as diamond, aluminum oxide, silicon oxide, silicon carbide, etc. Other materials may also be used. In some embodiments, abrasives used may range, for example, from about 0.5 microns up to about 3 microns in size or 0.1 microns to 10 microns in size, although other sizes may be used. Different widths of polishing tape 318 ranging from about 0.2 inches to about 1.5 inches may be used, although other polishing tape widths may be used. In one or more embodiments, the polishing tape 318 may be about 0.002 to about 0.02 inches thick and withstand about 1 to 5 lbs. in tension. Other tapes having different thicknesses and tensile strengths may be used. The spools 324, 326 may have a diameter of approximately 4 inches and be capable of holding about 5000 inches of polishing tape 318, or may have a diameter of approximately 10 inches and be capable of holding about 35,000 inches of polishing tape 318. Other spool dimensions may be used. The spools 324, 326 may be constructed from materials such as nylon, polyurethane, polyvinyl difluoride (PVDF), etc. Other materials may also be used.
Turning to FIG. 4, an alternate embodiment of the apparatus 300 shown in FIG. 3 is provided. The difference between FIG. 3 and FIG. 4 is that the wheel shaped polishing pad 316 is shown in FIG. 3 and the substantially planar polishing pad 416 is shown in FIG. 4. The different polishing pads 316 and 416 will be further described below.
With reference to FIG. 5, a part of the substrate 100 containing the notch 116 is schematically illustrated, not to scale. The notch 116 may include one or more notch sides 500. The notch 116 may also include a first notch corner or node 502 and a second notch corner or node 504. Each notch corner 502, 504 may be positioned at the intersection of the notch side 500 and the outer perimeter of the substrate 100. The notch 116 may further include a notch center 506, positioned at the intersection of the one or more notch sides 500. The notch center 506 may be used to align the substrate 100 during processing. A notch depth 508 is also indicated. As is apparent from the figure, the notch 116 may exhibit large changes in curvature as it is traced from the first notch corner 502 to the second notch corner 504, via the notch sides 500 and notch center 506. For this reason, to improve notch cleaning, it is advantageous to maintain consistent contact between the polishing tape 318 and all regions of the notch 116 indicated above.
FIG. 6 is a schematic perspective view, not to scale, of a portion of an embodiment of the notch polishing apparatus 300 shown in FIG. 3. For reasons of clarity, only the substrate 100, the backing pad 316, the polishing tape 318, and the spools 324, 326 are shown. In addition, it should be pointed out that the positioning of the spools 324, 326 shown herein is different than in the embodiment of the notch polishing apparatus 300 shown in FIG. 3.
However, the positioning of the spools 324, 326 may be arranged in different ways and may not have a large effect on the polishing of the notch 116. Additionally, as shown herein, the polishing pad 316 may be supported on a polishing pad axle 332, which may be mounted to the polishing head 314 or the support arm 310 in a manner that allows the polishing pad axle 332 to rotate freely about an axis tangential to the substrate 100. The polishing pad axle 332 may also be driven by a polishing pad driver (e.g., a servomotor), not shown. The polishing pad axle 332 may be made out of materials such as stainless steel or PEEK. Other materials may be used. In some embodiments, the polishing pad 316 may be hollow and filled with a pressurizable gas (e.g., air, nitrogen, carbon dioxide, etc.) or liquid (e.g., hydraulic fluid), or other suitable fluid.
In other embodiments, the polishing pad 316 may be filled with a resilient material, such as polyurethane foam or silicone rubber, for example. Other suitable materials may be used. In either case, the polishing pad 316 may include an outer skin 334 (FIG. 7) made of a resilient material such as polyurethane, silicone rubber or Viton, for example. Other suitable materials may be used. As mentioned above with regard to FIG. 3, the polishing pad 316 may be moved toward or away from the substrate 100 by an actuator (not shown). When moved toward the substrate 100 by the actuator, the polishing pad 316 may press the polishing tape 318 into the notch 116 and cause the polishing tape 318 to contact all of the regions of the notch 116 (FIG. 5). The actuator may include an actuator force sensor (not shown) or actuator pressure sensor (not shown) for measuring a force or a pressure exerted by the actuator on the polishing pad 316. The actuator may also be coupled to an actuator control unit (not shown). The actuator control unit may receive a signal from the actuator force sensor or actuator pressure sensor indicative of the force or pressure exerted on the polishing pad 316 by the actuator. The actuator control unit may also regulate the force or pressure exerted by the actuator as a function of this signal.
FIG. 7 is a schematic cross-sectional view of an embodiment of the polishing pad 316 of FIG. 6, which is supported on the polishing pad axle 332. The polishing pad axle 332 may rotate about an axis A-A. The polishing pad 316 may be fixedly or rotationally mounted to the polishing pad axle 332. In embodiments in which the polishing pad 316 is filled with a gas or liquid, the polishing pad 316 and the polishing pad axle 332 may be connected to form a seal between them. The seal may allow an interior region 336 of the polishing pad 316 to withstand a fluid pressure of up to approximately 80 lb/in2, for example, without leaking or bursting. Other pressures may be used. The polishing pad axle 332 may include a fluid channel 338 that may lead from a pressurized liquid or gas reservoir (not shown) to the interior region 336 of the polishing pad 316. A pressure sensor (not shown) may be situated in the interior region 336 or the fluid channel 338 or the liquid or gas reservoir. A pressure control unit (not shown) may be electrically connected to the pressure sensor and the liquid or gas reservoir. The pressure control unit may receive a signal from the pressure sensor that is indicative of a pressure in the liquid or gas reservoir, a pressure in the fluid channel 338, or a pressure in the interior region 336 of the polishing pad 316. The pressure control unit may regulate the pressure in any or all of these areas as a function of this signal.
In some embodiments, a portion of the polishing pad 316 under the outer skin 334 may include a ridge region 340. The ridge region 340 may include a tip region 342 (FIG. 8), further described below. The ridge region 340 may be substantially in relief (or thinner) compared to the rest of the polishing pad and the tip region 342. The relief portion may allow the polishing pad 316 to better conform to the notch 116, and in particular to the first and second nodes 502, 504 of the notch 116. In other embodiments, the outer skin 334 may include ridges or an alternate profile (FIG. 10B) to apply the force to the polishing tape 318 and notch 116 in a different manner. The polishing tape 318 may travel over at least part of this ridge region 340 while being indexed or moved continuously between the spools 324, 326.
FIG. 8 is an enlarged schematic cross-sectional view of the polishing pad 316 of FIG. 7 in the region of FIG. 7 enclosed by a dashed circle and labeled FIG. 8. As can be seen in this figure, when the polishing pad 316 is moved in the direction of the substrate 100, the polishing tape 318 may be pressed into the notch 116 by the ridge region 340, and in particular the tip region 342 of ridge region 340, which may have a shape corresponding to a shape of the notch 116. In addition, the tip region 342 may be provided with a radius that may ensure sufficient contact between the polishing tape 318 and all of the sections of the notch 116 shown in FIG. 5. For example, if a minimum notch radius r1 is 0.035 inches and a thickness t of polishing tape 318 is approximately 0.004 inches, then a maximum radius r2 of the tip region 342 may be approximately 0.03 inches to ensure sufficient contact between the polishing tape 318 and the notch 116. This contact may allow the polishing tape 318 to effectively polish the substrate notch 116 when indexed between the spools 324, 326. Other tip region radii may be used.
Turning to FIGS. 9A and 9B, a schematic perspective view, not to scale, of a portion of an embodiment of the notch polishing apparatus 300 shown in FIG. 3 is provided. Similarly to FIG. 6, for reasons of clarity, only the substrate 100, the polishing head 314, the polishing pad 316, the polishing tape 318, and the spools 324, 326 are shown. In addition, it should be pointed out that unlike the embodiment of the polishing apparatus 300 shown in FIG. 3, the spools 324, 326 of the embodiment of the polishing apparatus 300 shown in FIGS. 9A and 9B may be considered to be part of the polishing head 314. However, the other positioning of the spools 324, 326 may not be used during the operation of the notch polishing apparatus 300. Further with respect to FIGS. 9A and 9B, the polishing head 314 may be connected to the polishing-head driver 309 via the support arm 310 and the frame 312 (see FIG. 3). The polishing head driver 309 may rotate the polishing head 314, and hence the polishing pad 316 (and in some embodiments the spools 324, 326,) about the substrate notch 116 in a plane approximately perpendicular to major surfaces 102, 102′ of the substrate 100. This rotation of the polishing head 314 about the substrate notch 116 may be accomplished using a combination of vertical, horizontal and rotational displacements of the polishing head 314 in a plane perpendicular to the major surfaces 102, 102′ of the substrate 100. The actuator (not shown) used to move the polishing pad 316 toward and away from the substrate notch 116 may also be used to horizontally position the polishing pad 316 during the rotation of the polishing head 314. The above-described rotation of the polishing head 314 may allow the polishing apparatus 300 to effectively clean and polish parts of the notch 116 adjacent to major surfaces, i.e., to upper and lower major surface 102, 102′, of the substrate 100.
Specifically, FIG. 9A shows the polishing head 314 rotated into a position allowing the parts of the notch 116 adjacent to the lower major surface 102′ of the substrate 100 to be cleaned and polished. FIG. 9B, in turn, shows the polishing head 314 rotated into a position allowing the parts of the notch 116 adjacent to the upper major surface 102 of the substrate 100 to be cleaned and polished.
FIG. 10A is a schematic plan view (not necessarily to scale) of an embodiment of the polishing apparatus of the invention. The polishing pad 316 may be supported on the polishing pad axle 332, which in turn may be supported by a pair of support blocks 900, 902. As shown herein, in some embodiments the polishing pad 316 may have a different profile compared to the polishing pad 316 described above with respect to FIGS. 7 and 8, for example. As indicated by the “raised” portion of the outer skin 334 covering the ridge region, the ridge region may just include the tip region, instead of the relief portion and the tip region shown in FIGS. 7 and 8. Polishing tape 318 (depicted in cross section such that the length of the polishing tape 318 would extend into and out of the page) may be interposed between the polishing pad 316 and the substrate 100, such that the polishing pad 316 may press the polishing tape 318 into and/or against the notch 116. Support blocks 900, 902 may have guides 904, 906, respectively, into which polishing tape 318 may be threaded. Guides 904, 906 may prevent side to side motion of the polishing tape 318 (e.g., motion perpendicular to the plane of rotation of the polishing pad 316 and in the plane of the page) and thus prevent the polishing tape 318 from slipping out from between the polishing pad 316 and the notch 116. Such prevention of side to side motion may be effected by the bottoms 904a and 906a of the guides 904 and 906, respectively. The sideways motion of the polishing tape 318 may be halted by the contact of the polishing tape 318 with either of the bottoms 904a, 906a. Support blocks 900, 902 may be made from metals, polymeric materials and/or any other material which is strong enough to hold the polishing pad axle 332 and which may be made smooth enough to allow the polishing tape 318 to move freely across a surface of the guides 904, 906 without sustaining an undesirable amount of wear over a predetermined period of time. Such a predetermined period of time may be, for example, the effective lifetime of grit on a polishing surface of the polishing tape 318.
FIG. 10B depicts another embodiment of the polishing apparatus of FIG. 10A. In this embodiment, the guides 904, 906 may be attached to the support blocks 900, 902, rather than formed in the support blocks 900, 902. In yet other embodiments (not shown), the guides 904, 906 may be separate from (e.g., not mounted on) support blocks 900, 902. Guides 904 and 906 may be mounted in any suitable position and/or orientation which is effective to prevent the polishing tape 318 from moving out from between polishing pad 316 and notch 116, thereby preventing the polishing pad 316 from making direct contact with the notch 116.
The guides 904, 906, as depicted in FIGS. 10A and 10B, are located such that a plane of the major surface 102 of the substrate 100 intersects the guides 904, 906, but the guides 904, 906 may be located in any plane and in any location which is effective to prevent the polishing tape 318 from moving out from between polishing pad 316 and notch 116. In other embodiments, more than two guides may be used in more than one plane.
FIG. 10C is a schematic side view of one embodiment of the polishing apparatus depicted in FIG. 10A. In FIG. 10C, it may be seen that the polishing tape 318 may extend from a tape source, such as the spool 324 shown in FIG. 3, around the polishing pad 316, and to a tape take-up, such as the spool 326 shown in FIG. 3. Polishing tape 318 is depicted in FIG. 10C as folded over the polishing pad 316 such that only one half of the polishing tape 318 is visible, the other half being obscured by the visible portion of the polishing tape 318 and the polishing pad 316. An edge of the polishing pad 316, obscured by the polishing tape 318 is indicated by dotted line 316a. In FIG. 10C, it may also be seen that an edge 318a of polishing tape 318 may pass through guide 906. The polishing tape edge 318a is depicted in dotted line form where the polishing tape edge 318a passes through and is obscured by the guide 906. The bottom of guide 906 is indicated by a dashed line 906a.
In operation, back and forth motion of the polishing tape 318 (e.g., motion having a component which is perpendicular to a plane of rotation of the polishing pad 316) may be stopped and/or restrained by a bottom 906a of the guide 906 and a mirror image bottom and guide on the other side of (and obscured by) polishing pad 316. The back and forth motion may also be described as motion which would tend to move the polishing tape edge 318a (or a mirror image edge which is obscured in FIG. 10C) of polishing tape 318 between the polishing pad edge 316a and the notch 116, such that the polishing pad 316 may contact the notch 116 of the substrate 100 directly. Such restraint of motion may prevent the polishing tape 318 from moving from between the polishing pad 316 and the notch 116 in the substrate 116. The surfaces of guides 906, 908 may be smoothened or polished to reduce wear on the polishing tape 318 and on the guides 904, 906. In some embodiments the direction of the polishing tape 318 movement may be reversible, such that the polishing tape source may become the polishing tape take-up and the polishing tape take-up may become the polishing tape source. In other embodiments, the polishing tape may be a continuous loop of polishing tape.
Turning to FIG. 11, a schematic perspective view of an exemplary embodiment of the polishing pad 416 shown in FIG. 4 is depicted. The polishing pad 416 may further include a notch polishing pad 418. The notch polishing pad 418 may have a protruding portion 420, whose shape roughly corresponds to the shape of the substrate notch 116. The notch polishing pad 418 may be a contoured pad made of a soft material, such as polyurethane, for example. Other suitable materials may be used. In some embodiments, the material making up the notch polishing pad 418 may have a hardness less than about Shore A 70 durometer, for example. However, materials having different hardnesses may be employed. The polishing pad 416 may be made of soft materials or rigid materials. The notch polishing pad 418 may be press-fitted to the polishing pad 416 or may be attached to the polishing pad 416 in another suitable manner. The notch polishing pad 418 may be easily replaced with a differently-shaped notch polishing pad in order to polish notches having a different shape than that of the notch 116, shown herein. In other embodiments, the notching polishing pad 418 and the polishing pad 416 may be integrally formed as a single continuous pad. The polishing pad 416 may also includes slots 422, 424 adapted to guide the polishing tape 318 as the polishing tape 318 is advanced through the substrate notch 116. The protruding portion 420 of the notch polishing pad 418 may conform to the shape of the notch 116 when pressed into the notch 116. The conformance may thereby cause the polishing tape 318 to contact the notch corners 502, 504, the notch sides 500, and the notch center 506, shown in FIG. 5.
Turning to FIG. 12, a schematic perspective view of part of the embodiment of the polishing apparatus 400 shown in FIG. 4 is provided. As described above, the polishing head 314, which may be supported by the support arm 310, may include the polishing pad 416 and the notch polishing pad 418 (obscured in FIG. 12 by the polishing tape 318, and shown above in FIG. 11), and guide rollers 320, 322. The polishing tape 318 may wrap around the polishing head 314, that is, around guide roller 320, notch polishing pad 418, and guide roller 322, while simultaneously being tensioned between spool 324 and spool 326. As is apparent from the figure, the protruding portion 420 of the notch polishing pad 418 may have a cross section similar in shape to the substrate notch 116. As described above, and shown herein, the polishing tape 318 may cover this protruding portion 420 when wrapped around the polishing head 314 and tensioned between the spools 324, 326.
As described above with respect to FIG. 3, the polishing pad 416 may be moved in a direction towards or away from the substrate 100 by an actuator (not shown). In operation, when the polishing pad 416 is moved towards the substrate 100 by the actuator, the notch pad protruding portion 420 may contact the substrate notch 116. As the protruding portion 420 contacts the notch 116, it may cause the section of polishing tape 318 overlaying the protruding portion 420 to conform to the shape of the notch 116 and contact all parts of the notch 116 (i.e. notch sides 500, first and second corners 502, 504, and notch center 506). The conformance of the polishing tape 318 to the shape of the notch 116 may allow the polishing tape 318 to effectively clean and polish the notch 116.
Turning to FIG. 13, a schematic cross-sectional view of an exemplary embodiment of the polishing pad 416 shown in FIGS. 11 and 12 is provided. The conformance of the protruding portion 420 of the notch polishing pad 418 to the shape of the substrate notch 116 is shown more clearly herein.
Turning to FIG. 14, a schematic cross-sectional view of an alternative embodiment of a relatively or substantially planar polishing pad 516 is provided. Similarly to the embodiment shown in FIG. 13, the polishing pad 516 may include slots 518, 520, adapted to guide the polishing tape 318. The notch polishing pad 522 and polishing pad 516 may be made of the same or similar materials as the notch polishing pad 418 and polishing pad 416 described above with respect to FIG. 11. Other materials may be used. As described above, the notch polishing pad 522 may include a protruding portion 524, which may conform to the shape of substrate notch 116 when the notch polishing pad 522 is pressed into the substrate notch 116. In the embodiment shown herein, the notch polishing pad 522 may also include a bore 526 or through-hole. In some embodiments, the bore 526 may extend along an entire length dimension of the notch polishing pad 522, and/or the bore 526 may have a circular cross-section.
Other suitably shaped cross-sections may be used. In some embodiments, the bore 526 may be hollow. In some embodiments, the bore 526 may be filled with a material having greater or lesser elasticity than that of the notch polishing pad 522. The bore 526 may allow the protruding portion 524 of the notch polishing pad 522 to more effectively conform to the shape of the notch 116, when the protruding portion 524 is pressed into or contacts the notch 116.
Turning to FIG. 15, a schematic cross-sectional view of another exemplary embodiment of a polishing pad 616 is provided. The polishing pad 616 may be held by a support arm 614. The polishing pad 616 may include a notch polishing pad 618 and slots 620 and 622 for guiding the polishing tape 318. The notch polishing pad 618 and polishing pad 616 may be made of the same materials as the notch polishing pad 418 and polishing pad 416, described above with respect to FIG. 11. Other materials may be used. The notch polishing pad 618 may also include a protruding portion 624 and plateau regions 626, 628. The shape of the protruding portion 624 may substantially correspond to the shape of the substrate notch 116. The height h of the protruding portion 624 may be the distance between one of the plateau region 626, 628 and a rounded tip 630 of the protruding portion 624. The polishing pad 616 may be moved in a direction toward, and in a direction away from, the substrate notch 116 by an actuator (not shown). The actuator may press the protruding portion 624 into contact with the substrate notch 116. When the protruding portion 624 contacts the substrate notch 116, the protruding portion 624 may conform to the shape of the substrate notch 116, and may cause the polishing tape 318 to contact the notch corners 502, 504, the notch sides 500, and the notch center 506 (FIG. 5). In some embodiments, the height h of the protruding portion 624 may be slightly larger than a typical notch depth (see FIG. 5). Since the notch depth may vary on different substrates 100, the height h of the protruding portion 624 may allow the notch polishing pad 618 to adapt to various substrate notch 116 heights. The plateau regions 626, 628 may be oriented in a direction approximately perpendicular to a radius (not shown) of the substrate 100 bisecting the substrate notch 116. However, the plateau regions 626, 628 may also be oriented in a direction not perpendicular to the radius of the substrate 100 bisecting the substrate notch 116. When the protruding portion 624 of the notch polishing pad 618 is pressed into contact with the substrate notch 116, the plateau regions 626, 628 may allow the polishing tape 318 to make effective contact with the notch corners 502, 504 (FIG. 5), and effectively polish them.
The slots 620, 622 of the notch polishing pad 618 may guide and approximately center the polishing tape 318 on the protruding portion 624, as the polishing tape 318 is advanced through the substrate notch 116. The slots 620, 622 may allow the polishing tape 318 to be easily conformed to, and pushed into contact with, the substrate notch 116 by the protruding portion 624 of the notch polishing pad 618.
Turning to FIG. 16, a schematic cross-sectional view of another embodiment of a polishing pad 716 including a notch polishing pad 718 having a bore or through-hole 720 is provided. The notch polishing pad 718 shown herein may be made from the same or similar materials having substantially similar elastic properties as the notch polishing pad 418 shown in FIG. 11. Other materials may be used. The notch polishing pad 718 may include a protruding portion 722 with a shape corresponding to that of the substrate notch 116, and may have plateau regions 724, 726 for effectively conforming the polishing tape 318 to the notch corners 502, 504 (FIG. 5). In addition, the polishing pad 716 may be made of the same or substantially similar materials as the polishing pad 416 described above with respect to FIG. 11. In some embodiments, the height h of the protruding portion 722 may be slightly larger than a typical notch depth, in order to allow the notch polishing pad 718 to adapt to the shapes of various substrate notches 116. Similarly to the bore 526 shown in FIG. 14, in one or more embodiments, the bore 720 shown herein may extend along an entire length dimension of the notch polishing pad 718, and/or the bore 720 may have a circular cross-section. The cross-section of the bore 720 may have other suitable shapes. As described above, in some embodiments, the bore 720 may be hollow. In other embodiments, the bore 720 may be filled with a material having greater or lesser elasticity than that of the notch polishing pad 718. The bore 720 may allow the protruding portion 722 on the notch polishing pad 718 to more effectively conform to the shape of the substrate notch 116, when the protruding portion 722 is pressed into contact with the substrate notch 116.
An exemplary method 1700 for cleaning and polishing the substrate notch 116 is provided in FIG. 17. In step S1710, the substrate 100 may be positioned and secured on the support. Then, in step S1720, the substrate 100 is rotated until the notch 116 is in alignment with the polishing head 314, i.e., in alignment with the ridge section 340 of the polishing pad 316. In step S1730, the polishing pad 316 is then moved in the direction of the substrate 100 by an actuator (not shown), until the tip region 342 of the ridge region 340 of the polishing pad 316 is in contact with the substrate notch 116, and presses the polishing tape 318 against the substrate notch 116. In step S1740, the polishing tape 318 may then be advanced by spool driver 328, 330 e.g., either of spools 324, 326 may be used as a take-up spool and a supply spool. As the polishing tape 318 is advanced on the polishing pad 316 and through the substrate notch 116, in some embodiments, the polishing pad 316 may rotate with a circumferential speed substantially equal to a rate of advance of the polishing tape 318. This means that the polishing tape 318 may advance on the polishing pad 316 without substantial slippage, and that the friction between the polishing pad 316 and the polishing tape 318 may include substantially rolling friction and almost no sliding friction. The advantage of rolling friction between the polishing pad 316 and a back side of the polishing tape 318 over sliding friction between the same may be a lower required tension of the polishing tape 318, more reliable tracking of the polishing tape 318, less wear to the back side of the polishing tape 318 and to the polishing pad 316, less heat generation, and less damage (e.g., plastic deformation) to the polishing tape 318 due to overheating.
Further with respect to the method 1700 for cleaning and polishing the substrate notch 116, the pressure with which the polishing tape 318 is pressed into contact with, and against, the substrate notch 116 may be determined by the force or pressure applied to the polishing pad 316 by the actuator, the pressure of the fluid in the polishing pad 316, and/or the resilience of the polishing tape 318. As the polishing tape 318 is advanced over the substrate notch 116, films and imperfections on the substrate notch 116 may be removed and eliminated by abrasion. The force or pressure applied by an actuator, and/or the pressure of the fluid in the polishing pad 316, may be adjusted by an actuator control unit and a pressure control unit, respectively, as needed. In step S1750, a polishing-head driver may rotate the polishing head 314 about the substrate notch 116 in a plane approximately perpendicular to major surfaces 102, 102′ of the substrate 100, in order to effectively clean and polish parts of the substrate notch 116 adjacent to major surfaces 102, 102′ of the substrate 100. During the above-described rotation of the polishing head 314, the pressure of the fluid in the polishing pad 316 may be adjusted by a pressure control unit to effectively conform the shape of the ridge region 340 and tip region 342 to changing geometry of the substrate notch 116. The speed, direction, tension, pressing force, etc. of the polishing tape 318 may be adjustable, as may be the rotational displacement, speed, and/or acceleration of the polishing head 314 about the substrate 100. For instance, the polishing tape 318 may be advanced at one speed for a certain length, and then another speed for another length. In addition, the polishing tape 318 may be translated or oscillated, or both, with constant or variable tensions and pressing forces.
Turning to FIG. 18, a second method 1800 for cleaning and polishing the substrate notch 116 is provided. The method of FIG. 18 is similar to the method described with reference to FIG. 17, but has the additional step of threading polishing tape through guides of a polishing pad as described below.
In step S1802 the substrate 100 may be positioned and secured on the support. In step S1804, the substrate 100 is rotated until the substrate notch 116 is in alignment with the polishing head 314, e.g., in alignment with the ridge section 340 of the polishing pad 316. In step S1806, which may be performed at any time prior to step S1808, the polishing tape 318 may be threaded through guides 904 and 906 and around the polishing pad 316. Such threading may be performed manually, or automatically. In step S1808, the polishing pad 316 may then be moved in the direction of the substrate 100 by an actuator, until the tip region 342 of the ridge region 340 of the polishing pad 316 is in the substrate notch 116 and presses the polishing tape 318 against the substrate notch 116. In step S1810, the polishing tape 318 may then be advanced by spool driver 328, 330, e.g., either of spools 324, 326 may be used as a take-up spool and a supply spool. All of the variations described above with respect to step S1740 of FIG. 17 may be used with the method 1800 of FIG. 18. In step S1812, a polishing head driver may rotate the polishing head 314 about the substrate notch 116 in a plane approximately perpendicular to major surfaces 102, 102′ of the substrate 100, in order to more effectively clean and polish parts of the notch 116 adjacent to major surfaces 102, 102′ of the substrate 100. Once again, all of the variations described above with respect to method step S1750 (FIG. 17) are available for use in the method 1800 of FIG. 18.
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, in some embodiments, the polishing-tape guides may project from close to the outer skin 334 of the polishing pad 316 and run concentrically with the tip region 342. The polishing tape guides may keep the polishing tape 318 approximately centered with respect to the tip section 342 of the ridge section 340, while the polishing tape 318 is indexed through the substrate notch 116. Furthermore, steps, such as applying a coating to the outer skin 334 over the ridge region 340, roughening the outer skin 334 over the ridge region 340, or otherwise increasing a tackiness of the outer skin 334 over the ridge region 340, may be undertaken, in order to increase the coefficient of friction between the backing side of the polishing tape 318 and the polishing pad 316 and decrease a likelihood of slippage of the polishing tape 318 on the polishing pad 316 during notch polishing.
Accordingly, while the present invention has been disclosed in connection with exemplary embodiments thereof, it should be understood that other embodiments may fall within the spirit and scope of the invention, as defined by the following claim.
