Browse Prior Art Database

Four Way Illumination Inspection System

IP.com Disclosure Number: IPCOM000088242D
Original Publication Date: 1977-May-01
Included in the Prior Art Database: 2005-Mar-04
Document File: 2 page(s) / 29K

Publishing Venue

IBM

Related People

Loeffel, W: AUTHOR [+3]

Abstract

Inspection of wafers and masks for particle contamination is important in order to increase yields. In the past, oblique light has been used for this type of inspection using a single light source from one direction. This method is not too good because of the uneven light distribution.

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Four Way Illumination Inspection System

Inspection of wafers and masks for particle contamination is important in order to increase yields. In the past, oblique light has been used for this type of inspection using a single light source from one direction. This method is not too good because of the uneven light distribution.

The approach here shown produces even illumination over the complete wafer or mask by illuminating the wafer with a high intensity collimated single light source at a low angle from four directions (90 degrees). The particles then can be sensed by a silicon photocell which will be set up in an accept or reject mode.

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