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Browse Prior Art Database

Calibration of Particulate Contamination Measurement Tool

IP.com Disclosure Number: IPCOM000049568D
Original Publication Date: 1982-Jun-01
Included in the Prior Art Database: 2005-Feb-09
Document File: 2 page(s) / 28K

Publishing Venue

IBM

Related People

Rosner, AJ: AUTHOR

Abstract

The addition of a photodetector coplanar with the wafer sample permits the camera aperture and shutter speed to be adjusted for variations in light intensity and film speed.

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Calibration of Particulate Contamination Measurement Tool

The addition of a photodetector coplanar with the wafer sample permits the camera aperture and shutter speed to be adjusted for variations in light intensity and film speed.

Particulate contamination is measured by a sub-micron particulate photographic technique (Sp(2)OT) wherein the wafer sample is illuminated by a high intensity lamp and a time exposure made. Particles on the wafer appear as bright specks on a dark background. Smaller particles may be detected by increasing the exposure time or by using a faster film.

The Sp(2)OT tool is conventionally calibrated by photographing a standard wafer with steps of predetermined dimensions. This is not only time consuming but does not detect and compensate for changes in the process (e.g., light intensity) during successive exposures.

By mounting a photodetector 10 in the vacuum chuck 11, coplanar with the wafer 12, the illumination from lamp 13 may be continuously monitored and the aperture and shutter speed of the camera 14 may be continuously adjusted, either manually or by a feedback servo loop, in the manner of an automatic camera exposure system.

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