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Process of Free Polishing Semiconductor Wafers

IP.com Disclosure Number: IPCOM000047570D
Original Publication Date: 1983-Dec-01
Included in the Prior Art Database: 2005-Feb-07
Document File: 1 page(s) / 11K

Publishing Venue

IBM

Related People

Mendel, E: AUTHOR

Abstract

More consistently flat semiconductor wafers can be produced by this two-step free polishing method utilizing hard pads to achieve better flatness. Free polishing as normally practiced in the semiconductor technology is a single-step process for generating smooth, highly specular, damage-free surfaces. Relatively soft poromeric polishing pads are used for this purpose. In this improved process, a flatter surface on the semiconductor wafers can be generated using a two-step process. In the first stage of the two-step free polishing process, hard, flat, highly dense materials are used on the top and bottom platens of the free polishing machines. Typically, such pad materials use blown polyurethanes or rosin-impregnated synthetic felts.

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Process of Free Polishing Semiconductor Wafers

More consistently flat semiconductor wafers can be produced by this two-step free polishing method utilizing hard pads to achieve better flatness. Free polishing as normally practiced in the semiconductor technology is a single-step process for generating smooth, highly specular, damage-free surfaces. Relatively soft poromeric polishing pads are used for this purpose. In this improved process, a flatter surface on the semiconductor wafers can be generated using a two-step process. In the first stage of the two-step free polishing process, hard, flat, highly dense materials are used on the top and bottom platens of the free polishing machines. Typically, such pad materials use blown polyurethanes or rosin-impregnated synthetic felts. The pads are made flat before use by conventional machining or by working them against each other. Semiconductor wafers in the sliced, ground, lapped, or chemically etched state are first-stage polished. After the first-stage polishing, the wafers received a brief touch-up polish to remove haze and superficial surface damage. Soft poromeric polishing pads, low applied pressures, and thicker slurries are utilized for the second stage of touch-up polishing. Cycle times are kept to a minimum to keep stock removal low in order to preserve the flatness achieved during the first step of this two-step process.

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