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Concurrently Measuring the Thickness of Each of Two Superimposed Thin Films on a Semiconductor Wafer

IP.com Disclosure Number: IPCOM000083865D
Original Publication Date: 1975-Aug-01
Included in the Prior Art Database: 2005-Mar-01
Document File: 1 page(s) / 11K

Publishing Venue

IBM

Related People

Chang, YE: AUTHOR [+4]

Abstract

This composite film thickness measurement system includes an optical/ control circuitry coupling the mechanical assembly to the computer, and an output display device coupled thereto.

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Concurrently Measuring the Thickness of Each of Two Superimposed Thin Films on a Semiconductor Wafer

This composite film thickness measurement system includes an optical/ control circuitry coupling the mechanical assembly to the computer, and an output display device coupled thereto.

A polarized beam of light is directed at a precise angle to the wafer under test. The intensity of the reflected light from the wafer is digitized and recorded by the computer. Each test cycle generates two groups of data for transmission to the computer. The first group of data is generated with a polarizer in the "S" plane of incidence and the second group with the polarizer in the "P" plane of incidence.

A rotating filter scans through its range of wavelengths for each polarizer position. The unequal incident light intensity at various wavelengths is cancelled out when product wafer data are divided by the calibration wafer data.

The computer generates curves for the P data and S data, and compares them to theoretical curves. A best-fit curve is chosen by the computer and the thin film thickness results are displayed on the display terminal.

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