Appeal No. 95-2728
Application 07/735,668
APPENDIX
21. A plasma etching method for etching a sample with a
gas plasma, the sample being cooled to a temperature not
higher than OEC, the method comprising the steps of:
generating an acceleration voltage for accelerating ions
in the gas plasma toward the sample to etch the sample; and
changing the acceleration voltage between a high
acceleration voltage and a low acceleration voltage;
wherein the high acceleration voltage is selected to
remove a residue from etched portions of the sample, the
residue occurring as a result of the sample being cooled to a
temperature not higher than OEC while being etched, the high
acceleration voltage being generated for a time sufficient to
remove the residue from the etched portions of the sample, and
wherein the low acceleration voltage is selected to etch the
sample with a high selectivity ratio.
29. A plasma etching apparatus including a vacuum
vessel, a sample table disposed in the vacuum vessel, means
for supplying a coolant to the sample table for cooling the
sample table and a sample disposed on the sample table to a
temperature not higher than OEC, and means for generating a
gas plasma for etching the sample disposed on the sample
table, the apparatus comprising:
means for generating an acceleration voltage for
accelerating ions in the gas plasma toward the sample to etch
the sample; and
control means for changing the acceleration voltage
between a high acceleration voltage and a low acceleration
voltage;
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Last modified: November 3, 2007