 Handicap accessible stair |
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| Tube bundle support |
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| Portable shelter |
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| Vent assemblies |
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| Underlay for tile floor of shower |
| OF THE ILLUSTRATED EMBODIMENTS One preferred embodiment of a segmented underlay in accordance with ... |
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| Domed roof structures for easy assembly and dismantling |
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| Collapsable dam |
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| Controlling method for a grinding machine |
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| Auxiliary insulated roof system |
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| Building construction |
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Semiconductor polishing pad
| Details |
Inventors: Allen, Franklin L.; Smith, William L.; Debner, Thomas G.; Olmstead, Dennis L.;
Assignee: Texas Instruments Incorporated (Dallas, TX)
Primary Examiner: Lavinder; Jack W.
Assistant Examiner:
Attorney, Agent or Firm: Franz; Warren L., Brady III; Wade J., Donaldson; Richard L.
The invention is to a polishing pad 14 that has a polishing surface 19 in which portions 17 and 18 of the polishing surface 19 have been removed. The removed areas 17 and 18 are annular rings adjacent an outer 15 and inner 16 edges of the polishing pad 14. The non-polishing surfaces 18 and 19 taper 17a and 18a downward from the polishing surface 19. |
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DETAILED DESCRIPTION The invention provides an improved polishing pad and its method of use.
The polishing pad has portions of the polishing surface removed by reducing the pad thickness, so that the parts of a wafer surface passing over the reduced thickness non-polishing portions of the pad are not polished as much as other parts of the wafer surface.
The paths of the wafer surface contacting the polishing pad are predictable, therefore it is known which part of the wafer surface will receive minimum polishing.
The parts of the pad surface removed are predetermined so that the polishing will not cause tapering of the wafer edges.
In an embodiment of the invention described below, an annular circular pad has two strips of the pad polishing surface removed by locally reducing the thickness of the pad, one strip adjacent the outer circumferential edge of the pad, and another strip adjacent the inner circumferential edge of the polishing pad.
The motion of the wafers around the pad, and the rotation of the wafers in the wafer holder puts the edges of the wafers over the reduced portions of the pad more than the central portions of the wafers, are put over the same portion.
This removes less surface of the outer edges of the wafer, thereby avoiding the non-flatness which occurs when the wafers are polished with pads not having the rings of the pad polishing surface removed.
The reduced portions may be continuous rings, or segmented rings which add more strength to the polish pad than the continuous ring configuration.
Edges of the removed strips are tapered to prevent tearing or binding on teeth of the wafer holder.
The technical advance represented by the invention, as well as the objects thereof, will become apparent from the following description of a preferred embodiment of the invention when considered in conjunction with the accompanying drawings, and the novel features set forth in the appended claims.
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Gutter-related 
