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Method and Apparatus for Removing Reactive Ion Etching Induced Surface Residues from Si Wafers Without Simultaneous Growth of Silicon Oxide

IP.com Disclosure Number: IPCOM000121270D
Original Publication Date: 1991-Aug-01
Included in the Prior Art Database: 2005-Apr-03
Document File: 2 page(s) / 58K

Publishing Venue

IBM

Related People

Clabes, JG: AUTHOR [+3]

Abstract

Disclosed is a method and apparatus for cleaning off reactive ion etching-induced contamination from Si wafers, yielding a clean surface. No thick SiO2 layer is formed by this new method.

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Method and Apparatus for Removing Reactive Ion Etching Induced Surface
Residues from Si Wafers Without Simultaneous Growth of Silicon Oxide

      Disclosed is a method and apparatus for cleaning off
reactive ion etching-induced contamination from Si wafers, yielding a
clean surface.  No thick SiO2 layer is formed by this new method.

      The removal of carbonaceous residues from reactive ion etching
processes by oxygen ashing is known to be highly effective since
volatile species are formed in the process. The formation of stable
SiO2 at the surface, however, prevents imbedded impurities to be
effectively removed and requires a post treatment for oxide
stripping.  The final state of the wafer surface undergoing an O2
plasma ashing process is determined by the balance between rapid
plasma-enhanced surface oxidation of silicon and the physical
sputtering effect.  Two methods, depicted in Figs. 1a and 1b, reduce
the oxide thickness grown under steady-state conditions by enhancing
the physical sputtering effect in two ways:  (i) the application of
extractor grids allows control of the physical sputtering rate
independent of the plasma conditions via the tunable bias voltage U0;
(ii) at an off-normal angle of incidence (a*) the sputtering yield
can be enhanced further, according to Fig. 2.

      The undesirable oxidation of Si in a conventional ashing
process is the result of an unfavorable ratio between growth rate and
removal rate.  The disclosed new proces...