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A Gap on a Stage Holding the Wafer Introduces a Non-Uniformity During the Annealing of Wafers

IP.com Disclosure Number: IPCOM000030141D
Publication Date: 2004-Jul-29
Document File: 2 page(s) / 67K

Publishing Venue

The IP.com Prior Art Database

Abstract

Disclosed is a method that eliminates the notch or gap in the chuck; this notch or gap can introduce non-uniformities for the annealing of a wafer.

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A Gap on a Stage Holding the Wafer Introduces a Non-Uniformity During the Annealing of Wafers

Disclosed is a method that eliminates the notch or gap in the chuck; this notch or gap can introduce non-uniformities for the annealing of a wafer.

Background

Currently, the chuck that is used for loading wafers has a notch that is used for withdrawing the wafer wand after loading a wafer, or for introducing the wand while unloading the wafers (see Figure 1).

The presence of this notch introduces non-uniformity in the temperature attained by the wafer during annealing. This is confirmed by measuring the sheet resistance of boron-doped wafers (see Figure 2). The sheet resistance at the notch part of the chuck (when loaded) is ~10 ohm/sq lower than that at similar radii measured in the no-notch part of the chuck. A contour plot of percentage changes in Rs normalized (with respect to lowest sheet resistance on the wafer) clearly highlights the notch in the chuck (see Figure 4).

General Description

In the disclosed method, wafers are loaded on a different chuck without a notch and processed at a similar power density to obtain similar temperatures on the wafer. The sheet resistance data does not show any correlation with a radius (see Figure 3). Using this measurement technique, the number of data points at the inner radii is smaller in number when compared with the outer radii. Nevertheless, the mean at each radius does not show any correlation, suggesting that the annealing temperatur...