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Thickness Monitor for Opaque Materials

IP.com Disclosure Number: IPCOM000090526D
Original Publication Date: 1969-May-01
Included in the Prior Art Database: 2005-Mar-05
Document File: 2 page(s) / 34K

Publishing Venue

IBM

Related People

Genovese, FC: AUTHOR

Abstract

This thickness monitor is used when end point techniques are impossible or elaborate thickness measuring systems are not warranted. Thin glass slide 10 is placed in holder 12 included in an evaporation apparatus not shown. Slide 10 is disposed at a preselected angle to receive the deposited material, The quantity of deposit can be varied by the 1 distance from the source and the angle of the glass surface with respect to the source direction. Optical density is related to thickness independently since it depends on the deposited material characteristics.

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Thickness Monitor for Opaque Materials

This thickness monitor is used when end point techniques are impossible or elaborate thickness measuring systems are not warranted. Thin glass slide 10 is placed in holder 12 included in an evaporation apparatus not shown. Slide 10 is disposed at a preselected angle to receive the deposited material, The quantity of deposit can be varied by the 1 distance from the source and the angle of the glass surface with respect to the source direction. Optical density is related to thickness independently since it depends on the deposited material characteristics.

Light from constant intensity lamp 14 passes through collimating telescope 16 to measuring photocell 18, typically cadmium sulfide. Slide 10 intercepts the light path. As a deposit builds up on slide 10, the light intensity is reduced, effecting the output of Photocell 18. Ohmmeter 20 is calibrated in film thickness and receives the output of photocell 18. Accuracy of film measurement is of the order of +/- 50 angstroms.

A separate slide 10 must be used for each deposit. The measurement is not effected by ambient or stray light from the evaporation source because of optically black shield 22.

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