Browse Prior Art Database

Semiconductor Defect Resolution System

IP.com Disclosure Number: IPCOM000084415D
Original Publication Date: 1975-Nov-01
Included in the Prior Art Database: 2005-Mar-02
Document File: 2 page(s) / 25K

Publishing Venue

IBM

Related People

Hansen, AC: AUTHOR [+3]

Abstract

In semiconductor wafer processing, defect monitoring is important for general process and yield control.

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Semiconductor Defect Resolution System

In semiconductor wafer processing, defect monitoring is important for general process and yield control.

It appears that the minimum resolution of a monitoring system is limited by the ability to differentiate between varying light backgrounds and scattered light from particles. As the light intensity or vidicon sensitivity is increased, certain areas of the wafer begin to bloom with noise as the reflected background light becomes greater than the minimum sensitivity threshold. This appears to be due to the less than flat geometry of the wafer and the reflection of extraneous light, and other reasons.

The primary objective in improvement of defect resolution is to obtain a uniform (constant) threshold across the total wafer. This condition can be obtained by averaging techniques which will improve the signal-to-noise ratio and thus the minimum defect resolution. This can be accomplished by: 1) improvement of light uniformity on the surface of the wafer; and 2) automatic mapping of the observed image with respect to threshold sensitivity.

The system illustrated may be used to map the output image with respect to threshold of sensitivity. The mapping cycle starts with vidicon sensitivity or light intensity set to a low level with minimum noise on the display. The intensity or sensitivity is increased with each successive scan via control module in schematic. A high level of correlation between the averaged sweep and the raw in...