Appeal No. 2000-1702
Application No. 08/841,908
art to treat such plasma deposited TEOS silicon oxide films with an ozone and oxygen
plasma to remove these carbonaceous impurities (col. 12, liner 55 to col. 13, line 3), it
would have been obvious to treat the plasma deposited TEOS silicon oxide film of Nguyen
et al. Prior to depositing the further layers to remove said carbon impurities from said
film.” See Answer page 3. We disagree.
Nguyen is directed to an improved method of depositing silicon oxide. See column
1, lines 6-7. In particular, we find the invention is directed to a method of depositing
silicon oxide layers by thermal decomposition of tetraethoxysilane (TEOS) and ozone. See
column 1, lines 8-10. Nguyen discusses the reasons for surface sensitivity when silicon
oxide films are deposited on silicon oxide. See column 2, lines 29-30. Nguyen states
that this sensitivity is believed to be due to the presence of Si-OH species on hydrophilic
surfaces. See column 2, lines 31-32. Inasmuch as TEOS molecules are hydrophobic they
do not adhere well to the underlying hydrophilic surface and are repelled by such
hydrophilic surfaces. See column 2, lines 33-35. Nguyen solves this problem by
substituting nitrogen atoms in the first layer of deposited TEOS silicon oxide film which
prevents hydrogen bonding to the surface of water or -OH radicals. See column 2, lines
43-47. Stated otherwise, the first layer deposited is rendered hydrophobic. Thereafter a
second layer of silicon oxide is deposited over the nitrogen containing silicon oxide under
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