Browse Prior Art Database

Wafer Flatness and Thin Film Stress Profiles Using a Film Thickness Analyzer

IP.com Disclosure Number: IPCOM000048172D
Original Publication Date: 1981-Dec-01
Included in the Prior Art Database: 2005-Feb-08
Document File: 2 page(s) / 44K

Publishing Venue

IBM

Related People

Barbee, SG: AUTHOR [+2]

Abstract

This is a proposal to enhance the IBM 7840 Film Thickness Analyzer (FTA) by additionally allowing for measurements of wafer flatness and residual film stress (*) with only minor modifications to the system. Briefly, this is achieved by incorporating the following: fiber optics for noncontacting displacement measurements, film thickness measurement, machined and aligned flat stage residual stress algorithm and the substrate thickness.

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Wafer Flatness and Thin Film Stress Profiles Using a Film Thickness Analyzer

This is a proposal to enhance the IBM 7840 Film Thickness Analyzer (FTA) by additionally allowing for measurements of wafer flatness and residual film stress (*) with only minor modifications to the system. Briefly, this is achieved by incorporating the following: fiber optics for noncontacting displacement measurements, film thickness measurement, machined and aligned flat stage residual stress algorithm and the substrate thickness.

By adding one or more pairs of fiber-optic bundles, whose light cone and scattering are known, to, or in place of, the single fiber bundle in the FTA, one can scan, rotationally or in a serpentine fashion, a wafer surface lying on a flat stage. Alternatively, many bundle pairs can be packed tightly to cover the entire stage area. The spatial resolution across the stage is determined by the bundle diameter of each pair. Each pair can then measure the distance at its radial position sequentially. To allow for nonorthogonality of the stage to the light cone, three or more distance measurements are taken from equally reflecting surfaces on the periphery of the stage and then stored and manipulated to correct subsequent measurements. A wafer scan at a large predetermined distance identifies any badly warped wafers or high regions which would affect how closely the probe would come down to the wafer (for greater sensitivity). The data collected during a scan are e...