Method for lapping a wafer
First Claim
1. A method for lapping first and second opposed major surfaces of a wafer comprising:
- initially lapping the major surfaces with a first slurry;
introducing a second slurry having abrasive particles that are smaller on average than those of the first slurry; and
continuing to lap the major surfaces with the second slurry, wherein introducing the second slurry occurs while continuing to lap the major surfaces such that the major surfaces are exposed to both the first and second slurries for at least a period of time, wherein lapping the major surfaces with the first slurry removes more material than that removed by continuing to lap the major surfaces with the second slurry, and wherein lapping the major surfaces with the first and second slurries collectively removes no more than about 90 microns in thickness.
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Accused Products
Abstract
An improved method for lapping the opposed major surfaces of a wafer is provided. In this regard, a multi-step lapping process is provided in which lapping continues while transitioning from a first slurry having larger abrasive particles to a second slurry having smaller abrasive particles so as to reduce the overall length of the lapping process. In addition, the multi-step lapping process is optimized so as to remove no more than about 90 microns in total thickness from the opposed major surfaces of the wafer. By completing the lapping with slurry having smaller abrasive particles, subsequent etching of the wafers produces shallower surface pitting. As such, the wafers generally require less polishing than required by conventional processes.
18 Citations
21 Claims
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1. A method for lapping first and second opposed major surfaces of a wafer comprising:
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initially lapping the major surfaces with a first slurry;
introducing a second slurry having abrasive particles that are smaller on average than those of the first slurry; and
continuing to lap the major surfaces with the second slurry, wherein introducing the second slurry occurs while continuing to lap the major surfaces such that the major surfaces are exposed to both the first and second slurries for at least a period of time, wherein lapping the major surfaces with the first slurry removes more material than that removed by continuing to lap the major surfaces with the second slurry, and wherein lapping the major surfaces with the first and second slurries collectively removes no more than about 90 microns in thickness. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. A method for lapping first and second opposed major surfaces of a wafer comprising:
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initially lapping the major surfaces with a first slurry so as to remove material from the major surfaces at a first removal rate;
introducing a second slurry; and
continuing to lap the major surfaces while introducing the second slurry, wherein continuing to lap the major surfaces comprises lapping the major surfaces with a combination of both the first and second slurries upon the initial introduction of the second slurry and thereafter lapping the major surfaces predominantly with the second slurry, and wherein lapping the major surfaces predominantly with the second slurry removes material from the major surfaces at a second removal rate less than the first removal rate and lapping the major surfaces with a combination of both the first and second slurries removes material from the major surfaces at a removal rate that transitions between the first and second removal rates, and wherein lapping the major surfaces with the first and second slurries collectively removes no more than about 90 microns in thickness. - View Dependent Claims (10, 11, 12, 13, 14, 15, 16)
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17. A method for lapping first and second opposed major surfaces of a wafer comprising:
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initially lapping the major surfaces with a first slurry that is no more than 1200 grit so as to have abrasive particles with an average size of at least about 8 microns;
introducing a second slurry that is at least 1500 grit so as to have abrasive particles with an average size of no greater than about 6 microns continuing to lap the major surfaces with the second slurry, wherein introducing the second slurry occurs while continuing to lap the major surfaces such that the major surfaces are exposed to both the first and second slurries for at least a period of time, wherein lapping the major surfaces with the first and second slurries collectively removes no more than about 90 microns in thickness; and
wherein continuing to lap the major surfaces once the second slurry is introduced removes no more than about 25 microns in thickness. - View Dependent Claims (18, 19, 20, 21)
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Specification