Appeal No. 2003-1162 Page 2
Application No. 09/468,292
INTRODUCTION
Appellant’s claims are directed to a method for providing volatile precursor molecules to
a chemical vapor deposition (CVD) process (specification, p. 1, ll. 4-6). In the CVD process, the
provided precursors are vapor phase reactants that react to form a thin film on a substrate
(specification, p. 1, ll. 9-13). Solid precursors must be vaporized before delivery to the CVD
chamber for reaction. One conventional method of vaporizing involves dissolving a solid
precursor in a solvent and placing the solution in a bubbler device (specification, p. 3, ll. 7-9).
The solution is heated in a reservoir (specification, p. 3, ll. 9-10). A carrier gas is directed over
or bubbled through the solution so that the carrier gas picks up the vaporized precursor molecules
and transports them to the CVD process chamber (specification, p. 3, ll. 10-13).
The main difference between Appellant’s process and that of the prior art resides in the
identity of the solvent: Appellant’s solvent is an ionic liquid, i.e., a liquid comprising ions
(specification, p. 4, ll. 18-23). According to Appellant, “an ionic liquid means a salt compound
having the following characteristics: (1) a melting point of less than about 250°C, (2)
substantially no measurable vapor pressure (i.e., less than about 1 Torr and preferably less than
0.01 Torr), (3) a liquid range of about at least 100°C, and, preferably about at least 200°C, and
(4) functions as a solvent for a wide range of desirable CVD precursor elements and
compounds.” (specification, p. 13, ll. 22-28).
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