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High Temperature Anneal Process for Improving Epitaxially Grown Silicon

IP.com Disclosure Number: IPCOM000088640D
Original Publication Date: 1977-Jul-01
Included in the Prior Art Database: 2005-Mar-04
Document File: 1 page(s) / 11K

Publishing Venue

IBM

Related People

Goth, GR: AUTHOR

Abstract

In a semiconductor process which requires a pre-epitaxial boron isolation diffusion, the following process reduces defects in the epitaxial layer and improves pipe-limiting yields: 1. Cycle mixtures of Ar/O(2)/BBr(3) and O(2) gases through the chamber at low temperature ( 1000 degrees C) to provide a shallow diffusion (tilde 0.5u) of the desired sheet resistance. 2. Remove the borosilicate glass formed at the substrate with a suitable preferential etch. 3. Anneal at high temperature ( 1150 degrees C) using an O(2)/Ar cycle sufficient to maintain the desired sheet resistance and achieve the desired diffusion depth of the isolation (i.e., 5-15 minutes O(2)/Ar cycle at 1150 degrees C).

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High Temperature Anneal Process for Improving Epitaxially Grown Silicon

In a semiconductor process which requires a pre-epitaxial boron isolation diffusion, the following process reduces defects in the epitaxial layer and improves pipe-limiting yields: 1. Cycle mixtures of Ar/O(2)/BBr(3) and O(2) gases through the

chamber at low temperature ( 1000 degrees C) to provide a shallow

diffusion (tilde 0.5u) of the desired sheet resistance.

2. Remove the borosilicate glass formed at the substrate with

a suitable preferential etch.

3. Anneal at high temperature ( 1150 degrees C) using an O(2)/Ar cycle

sufficient to maintain the desired sheet resistance and

achieve the desired diffusion depth of the isolation

(i.e., 5-15 minutes O(2)/Ar cycle at 1150 degrees C).

The mechanism for defect reduction is apparently an improved gettering efficiency of either precipitated oxygen or the boron diffusion. The improvement in epitaxy quality is observed to be dependent on the maximum temperature of the anneal cycle rather than the time at temperature. In processes where an arsenic subcollector has also been diffused in the substrate, any arsenic dopant which has piled up at the SiO(2)-silicon interface, due to the subcollector reoxidation, is redistributed. This effect will reduce epitaxial autodoping and lower the subcollector final sheet resistance.

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