Browse Prior Art Database

Adiabatically Stable Thickness Monitor

IP.com Disclosure Number: IPCOM000087534D
Original Publication Date: 1977-Feb-01
Included in the Prior Art Database: 2005-Mar-03
Document File: 2 page(s) / 55K

Publishing Venue

IBM

Related People

Gartner, HM: AUTHOR [+2]

Abstract

Shown is an adiabatically stable quartz film laser-optical film thickness monitor in which the variable quartz film thickness cut-off is eliminated by adiabatic isolation of photodetectors from surrounding thermal energy sources.

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Adiabatically Stable Thickness Monitor

Shown is an adiabatically stable quartz film laser-optical film thickness monitor in which the variable quartz film thickness cut-off is eliminated by adiabatic isolation of photodetectors from surrounding thermal energy sources.

In the system shown, the photodetector A which senses the magnitude of laser light reflected from a semiconductor wafer surface is very sensitive to heat energy exchange from surrounding sources F. To eliminate this problem and maintain a thermally stable environment for the photo-detector A, an enclosure is fabricated from a high thermal insulator E, and coated with an aluminized film D on both inside and outside surfaces. A strip chart recorder is used to monitor the stable sine wave signal.

This improved system can be used to measure quartz film thicknesses on a real-time basis, as quartz is deposited by a sputtering process.

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