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Process for Producing and Maintaining Oxide-Free Silicon Surfaces and for Controllably Removing Hyperthin Silicon Oxide Films

IP.com Disclosure Number: IPCOM000102398D
Original Publication Date: 1990-Nov-01
Included in the Prior Art Database: 2005-Mar-17
Document File: 2 page(s) / 74K

Publishing Venue

IBM

Related People

Gerath, H: AUTHOR [+3]

Abstract

This article describes a process for controllably removing hyperthin silicon oxide films from silicon surfaces by HF gas mixed with weakly polar solvent vapors rather than steam.

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This is the abbreviated version, containing approximately 53% of the total text.

Process for Producing and Maintaining Oxide-Free Silicon Surfaces and for Controllably Removing Hyperthin Silicon Oxide Films

       This article describes a process for controllably
removing hyperthin silicon oxide films from silicon surfaces by HF
gas mixed with weakly polar solvent vapors rather than steam.

      The figure shows the etch rate as a function of the etch time
for flow reactor etching using nitrogen (N2) and hydrofluoric acid
(HF), in addition to steam, methanol and isopropanol vapor.  In each
of these cases, there is an identical flow of nitrogen and
hydrofluoric acid, so that etching differs only with regard to the
type and amount of solvent vapor, the latter varying according to the
vapor pressure applied.

      The figure shows that when steam is used, the etch rate varies
from about 2 nm/s at t = 5 s to about 16.5 nm/s at t
= 6 s to drop slowly to a relatively constant value of about 6 nm/s.
For methanol vapor, the curve of the etch rate is noticeably
smoother, rising from about 2 nm/s at t = 5 to about 7 nm/s at
t = 6, with a constant rate of about 2.4 nm/s being obtained at t
= 12 s. For isopropanol vapor, the curve of the etch rate is
monotonous within the range of the measuring errors, with a value of
1 nm/s being obtained at t = 10.

      The position of the etch rate maximum varies for different
oxides and oxide surfaces.  Therefore, if steam is used for etching,
the amount of material removed varies irreproducibly by severa...