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Wafer Inspection Technique

IP.com Disclosure Number: IPCOM000078684D
Original Publication Date: 1973-Feb-01
Included in the Prior Art Database: 2005-Feb-26
Document File: 1 page(s) / 11K

Publishing Venue

IBM

Related People

Howard, LF: AUTHOR

Abstract

It is known to test the quality of silicon semiconductor wafers with regard to leakage currents, by growing an oxide on the wafers, depositing aluminum dots on the oxide, applying a sufficient potential to the dots to bias the wafers into deep depletion, and measuring the time for the wafers to recover. Difficulties associated with this procedure, are that it is destructive and that the results obtained depend on the quality of the grown oxide.

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Wafer Inspection Technique

It is known to test the quality of silicon semiconductor wafers with regard to leakage currents, by growing an oxide on the wafers, depositing aluminum dots on the oxide, applying a sufficient potential to the dots to bias the wafers into deep depletion, and measuring the time for the wafers to recover. Difficulties associated with this procedure, are that it is destructive and that the results obtained depend on the quality of the grown oxide.

This test may be made nondestructive by using a temporary, easily removed insulator over the wafer surface in place of thermally grown silicon dioxide. Such a temporary insulator may be a vacuum deposited, spun, or sprayed polyester or polyimide film. Aluminum dots may then be deposited on the film for the test. Alternatively, an insulating plastic film can be carried by a tip of a flat probe, which is pressed against the wafer surface. In this approach, it is important that the probe tip and wafer surface be parallel, so that a constant insulator thickness is provided across the wafer surface.

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