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Producing High Quality Epitaxial Silicon Over Impurity Diffused Substrates

IP.com Disclosure Number: IPCOM000080308D
Original Publication Date: 1973-Nov-01
Included in the Prior Art Database: 2005-Feb-27
Document File: 2 page(s) / 65K

Publishing Venue

IBM

Related People

Hall, FR: AUTHOR [+2]

Abstract

In this method, high quality epitaxial silicon can be grown while achieving alignment marking during the growing of an epitaxial layer.

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Producing High Quality Epitaxial Silicon Over Impurity Diffused Substrates

In this method, high quality epitaxial silicon can be grown while achieving alignment marking during the growing of an epitaxial layer.

Defects in the epitaxial silicon grown over a diffused silicon substrate are related to surface perfection of the substrate. The presence of defects such as precipitates of dopants in the silicon, crystallographic defects associated with these precipitates, defects resulting from stress relief and surface roughness, can all cause epitaxial defects to form during the epitaxial deposition. Modern integrated circuit technology requires high-doped regions in the base substrate for use as subcollectors. These regions in the substrate present autodoping problems during epitaxial growth.

In this method, a nasking layer 10 is deposited on silicon wafer 12 preferably by thermal oxidation. A diffusion window 14 is formed in layer 10 by conventional photolithographic techniques and differential etching. After opening 14 has been formed, the surface of wafer 12 is etched to delineate the diffused area for subsequent device processing. A nonpreferential etchant should be used to form depression 16 in wafer 12, so that a smooth surface is present for the later epitaxial deposition.

As shown in Fig. 2, the diffused region 18 is then formed utilizing layer 10 as a diffusion mask. As shown in Fig. 3, layer 10 is then stripped, leaving the wafer 12 ready for epitaxial depos...