Appeal No. 95-2231
Application No. 08/114,285
Claims 31 and 32 are illustrative of the subject matter
on appeal and read as follows:
31. A method of extending the continuous operating life
of an excimer laser containing a lasing gas or gas mixture
selected from the group consisting of XeF, KrF and ArF, by
removing an amount of CF impurity therefrom during operation
4
of said excimer laser, which is sufficient to minimize loss of
laser power output and to extend the continuous operating life
of said excimer laser, which comprises:
a) introducing oxygen into said lasing gas or gas
mixture, and reacting said oxygen with said CF impurity which
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accumulates
in said lasing gas or gas mixture, said oxygen being
introduced
in an amount effective to produce one or more compounds which
are condensable with refrigeration means; and
b) condensing said one or more or more compounds
produced in step a) in cryogenic trap, with refrigeration
means and at a temperature sufficient to condense said one or
more compounds substantially without condensing said lasing
gas or gas mixture therewith, thereby removing said CF4
impurity from said lasing gas or gas mixture, thereby
extending the operating life of the excimer laser.
32. A method of extending the continuous operating life
of an excimer laser containing a lasing gas or gas mixture
selected from the group consisting of XeF, KrF and ArF, by
removing an amount of oxygen impurity therefrom during
operation of said excimer laser, which is sufficient to
minimize loss of laser power output and to extend the
continuous operating life of said excimer laser, which
comprises:
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