Browse Prior Art Database

Gaas Film Monitoring

IP.com Disclosure Number: IPCOM000062801D
Original Publication Date: 1986-Dec-01
Included in the Prior Art Database: 2005-Mar-09
Document File: 1 page(s) / 11K

Publishing Venue

IBM

Related People

Hoh, PD: AUTHOR [+2]

Abstract

Since GaAs is transparent to electromagnetic radiation in the infrared (IR) region, this fact is used with an IR source and a detector to facilitate the measurement of the deposition rate of transparent films on GaAs. The measurement is accomplished by directing the IR light through the substrate from the backside. Monitoring the reflected intensity change of the light striking the water will permit determination of thickness variations through the wafer on the front surface. The changes in intensity are directly related to the thickness of the growing transparent film.

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Gaas Film Monitoring

Since GaAs is transparent to electromagnetic radiation in the infrared (IR) region, this fact is used with an IR source and a detector to facilitate the measurement of the deposition rate of transparent films on GaAs. The measurement is accomplished by directing the IR light through the substrate from the backside. Monitoring the reflected intensity change of the light striking the water will permit determination of thickness variations through the wafer on the front surface. The changes in intensity are directly related to the thickness of the growing transparent film.

Conversely, the end-point of the removal of any film from a GaAs substrate can be determined by monitoring the change of the reflected intensity from the backside of the wafer. The detection of the end-point of the removal of the film is not restricted to transparent films. Both metal and insulator end-p determination is possible. When the deposited film is completely removed from the substrate, the IR wavelengths will again be transmitted through the wafer and the total reflected intensity being detected will decrease.

The detector will consist of a fiber optic bundle under each wafer position, with both sending and receiving fibers. An IR laser will be the radiation source and a photo-diode will serve as the receiver.

Disclosed anonymously.

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