Appeal 2007-1884
Application 10/329,205
firmly establishes that it was known in the art to etch silicon with molecular
fluorine at elevated temperatures. Also, significantly, none of Mucha, Hiroi,
or Badmaeva discloses that molecular fluorine is in plasma form during the
etching of silicon.
As appreciated by the Examiner, Mucha, Hiroi, and Badmaeva do not
expressly teach that the elevated temperature within the chamber is effected
by heating the susceptor. However, as pointed out by the Examiner,
Takenaka evidences that it was known in the art to heat the susceptor during
silicon etching at elevated temperatures. Consequently, although Takenaka
utilizes fluorine compounds, but not molecular fluorine, we are satisfied that
one of ordinary skill in the art would have found it obvious to raise the
temperature of the chamber for etching silicon by heating the susceptor,
regardless of the particular etching gas employed. Appellants have apprised
us of no reason why the particular etching gas used would have played a role
in the means selected for heating the etching chamber.
Appellants maintain that the combination of references does not teach
heating the susceptor to about 450°C. However, Hiroi specifically teaches
etching silicon with molecular fluorine at a temperature below 580°C, which
encompasses the claimed value. Moreover, as explained by the Examiner, it
is a matter of obviousness for one of ordinary skill in the art to determine the
optimum value of a result-effective variable, such as temperature, in the
etching of silicon with molecular fluorine. Also, the Examiner correctly
points out that Appellants’ Specification attaches no criticality to the
4
Page: Previous 1 2 3 4 5 6 Next
Last modified: September 9, 2013