Browse Prior Art Database

Dry Wafer Cleaning by Use of a Reducing Plasma

IP.com Disclosure Number: IPCOM000121512D
Original Publication Date: 1991-Sep-01
Included in the Prior Art Database: 2005-Apr-03
Document File: 1 page(s) / 42K

Publishing Venue

IBM

Related People

Drew, JE: AUTHOR

Abstract

An improved method is shown for removal of inorganic metallic residuals from semiconductor wafer surfaces post O2 plasma resist strip.

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Dry Wafer Cleaning by Use of a Reducing Plasma

      An improved method is shown for removal of inorganic
metallic residuals from semiconductor wafer surfaces post O2 plasma
resist strip.

      Post O2 plasma ash of resist wet chemical cleaning is utilized
to remove metallic contaminants from wafer surfaces. Metallic
contaminants can interfere with FET operation and cause other defects
such as peppery polysilicon. A new method is shown that utilizes an
RF-generated plasma of reducing gases (5% H2/95% N2) or (4% H2/96%
He) for post O2 plasma resist strip cleaning.

      Reducing plasma cleaning is performed in a vacuum system at low
pressure (4 Torr) using reducing gas and striking a plasma with a
13.5 MHz RF signal. The plasma is upstream and baffled from the
wafer. The effectiveness of metallic removal using this method is
shown below.  All measurements x 10E12 atoms/cm2 . Null Hypothesis:
Metal concentration difference between preclean and postclean
readings equal zero.
                               H2/N2 PLASMA
           PRECLEAN            POST CLEAN          STATISTICS
METAL     x    s    n         x    s    n         t   tcrit null
Cr      0.45  0.31  6       0.53  0.39  24      0.45  2.326 Accept
Fe      1.557 0.71  6       1.75  0.64  24      0.63  2.326 Accept
Cu      0.416 0.49  6       0.198 0.48  24 ...