Browse Prior Art Database

Surface Defect Analyzer

IP.com Disclosure Number: IPCOM000080660D
Original Publication Date: 1974-Jan-01
Included in the Prior Art Database: 2005-Feb-27
Document File: 2 page(s) / 48K

Publishing Venue

IBM

Related People

Patrick, WJ: AUTHOR [+2]

Abstract

Submicron defects in semiconductor wafers is a problem, which ofttimes results in defective products before the problem is detected. Described is a surface defect analyzer which is particularly suited for determining, in a rapid manner, a quantitative analysis of wafer surface quality.

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Surface Defect Analyzer

Submicron defects in semiconductor wafers is a problem, which ofttimes results in defective products before the problem is detected. Described is a surface defect analyzer which is particularly suited for determining, in a rapid manner, a quantitative analysis of wafer surface quality.

As illustrated, a laser is used as an intense light source, and is directed upon the surface of a semiconductor wafer at an angle of approximately 45 degrees, the laser being mounted for movement so as to scan across the diameter of the wafer. The wafer is mounted on a vacuum chuck which is rotated at a predetermined speed, and a photomutiplier tube (PMT) is positioned perpendicular to the axis of the wafer.

Surface defects such as pits, mounds, particulates etc., cause the laser light to scatter or reflect in directions different from the specularly reflected beam. The amount of light received by the FMT then may be taken as a measure of surface imperfection (or perfection depending upon which end of the spectrum is being observed).

Additionally, by connecting the output of the PMT to suitable oscilloscopes, oscillographs and/or counters, exact positions of the defect and the nature thereof may be determined. It should be recognized that this information may be processed and then stored, for example, in a computer for further use.

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