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In-Situ, Real-Time Thin-Film Refractive Index and Thickness Monitor

IP.com Disclosure Number: IPCOM000049625D
Original Publication Date: 1982-Jun-01
Included in the Prior Art Database: 2005-Feb-09
Document File: 2 page(s) / 60K

Publishing Venue

IBM

Related People

Hewig, GH: AUTHOR [+2]

Abstract

An optical apparatus for the real-time, in-situ measurement of the refractive index and thickness of a thin film includes a low index film on a prism, as shown in Fig. 1. The apparatus 10 has a laser source 12 that passes a beam of light through a beam expander 14, a window 16 and lens 18 into the prism 20.

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In-Situ, Real-Time Thin-Film Refractive Index and Thickness Monitor

An optical apparatus for the real-time, in-situ measurement of the refractive index and thickness of a thin film includes a low index film on a prism, as shown in Fig. 1. The apparatus 10 has a laser source 12 that passes a beam of light through a beam expander 14, a window 16 and lens 18 into the prism 20.

The prism 20 has a low refractive index film 22 which is deposited on the prism 20 prior to the insertion of the prism 20 into the deposition chamber 24. The film 26C to be measured, is deposited on the film 22. The measurements are made by propagating light in the film 26C, which acts as a waveguide. The light is coupled through the prism 20, with the film 22 acting as a low-index coupling "gap". Examples of two suitable materials for film 22 are polymethylmethacrylate and polyvinyl alcohol.

In the chamber 24, films 26A 26B 26D and 26F will be deposited on substrates 28A, 28B, 28C and 28D, respectively. At the same time, film 26C will be deposited on the film 22. This apparatus will permit the real-time, in-situ measurement of the refractive index (n) and the thickness (t) of the film 26C as it is being deposited by computing n and t from the measured values of the synchronous angles (Gamma) for coupling monochromatic light into the film 26C.

To measure the coupling angles, the incident beam from the laser 12 is expanded and strongly focused on the prism 20 base, so that the incident light co...