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Deoxygenated HF Acid Solutions for Precleaning of Silicon Wafers Prior To Low Temperature Epitaxy

IP.com Disclosure Number: IPCOM000108028D
Original Publication Date: 1992-Jan-01
Included in the Prior Art Database: 2005-Mar-22
Document File: 1 page(s) / 52K

Publishing Venue

IBM

Related People

Agnello, PD: AUTHOR [+4]

Abstract

This article describes the use of deoxygenated HF acid solutions to etch/preclean silicon wafers prior to epitaxy by low temperature chemical vapor deposition techniques, e.g., UHVCVD. The use of deoxygenated HF solutions results in a lowering of the residual interfacial oxygen levels. The liquid HF etches may be deoxygenated by bubbling pure, oxygen-free argon gas, i.e., liquid argon boil-off, prior to and while etching the silicon wafers.

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Deoxygenated HF Acid Solutions for Precleaning of Silicon Wafers Prior To Low Temperature Epitaxy

       This article describes the use of deoxygenated HF acid
solutions to etch/preclean silicon wafers prior to epitaxy by low
temperature chemical vapor deposition techniques, e.g., UHVCVD.  The
use of deoxygenated HF solutions results in a lowering of the
residual interfacial oxygen levels. The liquid HF etches may be
deoxygenated by bubbling pure, oxygen-free argon gas, i.e., liquid
argon boil-off, prior to and while etching the silicon wafers.

      Low temperature techniques, such as UHVCVD, do not depend on an
in-situ substrate precleaning step to provide an oxide-free surface
for epitaxy, but, instead, rely on ex-situ etching and hydrogen
passivation of the silicon surface by a conventional (10.0) HF
solution (1,2).

      However, this conventional etch does not result in a perfectly
passivated silicon surface entirely free of oxygen.  Typically,
residual oxygen levels equivalent to a coverage of the silicon
surface by several hundredths of a monolayer are detected at the
interface after low temperature epitaxial growth.  Reduction of these
oxygen levels may improve the quality of the epitaxial growth. Even
though the detailed chemistry which results in these residual oxygen
levels is not well understood, some of the residual oxygen originates
from oxygen dissolved in the etch solution from the atmospheric
ambient.  Using deoxygenated (10.1) HF soluti...