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Process for Making Very Thin, Unwarped, Polished Wafers

IP.com Disclosure Number: IPCOM000051365D
Original Publication Date: 1981-Jan-01
Included in the Prior Art Database: 2005-Feb-10
Document File: 2 page(s) / 42K

Publishing Venue

IBM

Related People

Holley, BR: AUTHOR [+2]

Abstract

Very thin flat and unwarped semiconductor wafers, 0.002-0.004 inch thick, which are polished on both sides, are made by mounting the wafers to wax-impregnated tissue and polishing each side separately.

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Process for Making Very Thin, Unwarped, Polished Wafers

Very thin flat and unwarped semiconductor wafers, 0.002-0.004 inch thick, which are polished on both sides, are made by mounting the wafers to wax- impregnated tissue and polishing each side separately.

According to the process, flat, polished platen 1 is placed on hotplate 2, heated and completely covered with layer 3 of blocking wax. A porous, uniformly thick lens tissue 4 (Fig. 2) is placed over the molten wax on hot platen 1 and completely saturated with the wax. The excess wax which diffuses through the tissue is removed.

Tissue 4 is lifted off platen 1, platen 1 is cleaned of excess wax 5 (Fig. 3), and tissue 4 is repositioned on platen 1 (Fig. 4). Wafers 6 (Fig. 5) are positioned on tissue 4, and precision ground flat steel block 7 is placed over the wafers and allowed to cool.

The block is removed and the mounted wafers are polished on a single-side polisher. The process is repeated to polish the other side of the wafers. Breakage is avoided by handling the wax impregnated tissue rather than the wafer. Warpage is avoided due to the absence of excess wax under the wafers and parallelism is attained due to the uniform compressibility of the wax- saturated tissue.

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