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Reduction of B Cristobalites in Semiconductors by Use of HCl/O(2)

IP.com Disclosure Number: IPCOM000083886D
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

Fuertinger, RE: AUTHOR [+2]

Abstract

In an arsenic-doped oxide subcollector process, the subcollector is formed by opening a window in a thick thermal oxide. A 700 Angstroms screen oxide is then grown and the arsenic-doped oxide (ASG) is deposited at a low temperature. After a high temperature drive-in, all of the ASG thermal oxide is removed. The wafer is then reoxidized to delineate the subcollector area.

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Reduction of B Cristobalites in Semiconductors by Use of HCl/O(2)

In an arsenic-doped oxide subcollector process, the subcollector is formed by opening a window in a thick thermal oxide. A 700 Angstroms screen oxide is then grown and the arsenic-doped oxide (ASG) is deposited at a low temperature. After a high temperature drive-in, all of the ASG thermal oxide is removed. The wafer is then reoxidized to delineate the subcollector area.

It has been observed that after the drive-in process, B-cristobalites appear in the ASG film. While the ASG film is continuous, the B-cristobalites are found all over the surface of the wafer. These B-cristobalites are crystalline clusters that can lead to pipes, shorts, leakages, low yields and surface defects.

The screen oxide is normallg grown in an ambient of pure oxygen at a given temperature. The use of an HCl-O(2) ambient during the screen oxide formation reduces the number of B-cristobalites significantly. The optimum range is 4-8% HCl-O(2). Higher percentages will result in surface corrosion due to preferential etching.

A further advantage is that the growth rate of the screen oxide in an ambient of HCl-O(2) is faster than pure oxygen, thereby decreasing overall processing time.

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