Appeal No. 1998-1728
Application 08/397,243
10µ m, whereas free Si grains existing in gaps of the MSi2 grains have a maximum grain size not greater
than 20µ m.
2. A refractory metal silicide target according to claim 1, wherein when the average value of a
Si/M atomic ratio in the entire sputtering is assumed to be X, the dispersion of the Si/M atomic ratio in
an arbitrary cross section of 1 mm2 in the mixed structure is in a range of X ± 0.02.
The appealed claims, as represented by claim 1,1 are drawn to a refractory metal silicide target
comprising at least a fine mixed structure composed of specified MSi2 (metal silicide) grains and Si
(silicon) grains. The metal silicide grains have an average grain size not greater than 10 µm and the free
silicon grains existing in gaps of the silicide grains have a maximum grain size not greater than 20 µm.
The number of metal silicide grains independently existing in a cross section of 0.01 mm2 of the mixed
structure is not greater than 15. In claim 2, the silicon/metal atomic ratio across the target can vary from
the average value of this ratio by ± 0.02. According to appellants, since silicon in a mixed
structure of the target is “more deeply eroded than” metal silicide during sputtering, it is preferable that
the mixed structure is “arranged such that [metal silicide] grains are coupled . . . like a chain and [silicon]
exist in the gaps of the [metal silicide] grains to reduce particles generated in a target because [metal
silicide] grains are liable to be removed or dropped from an eroded surface in a position where [metal
silicide] independently exists in [silicon] phase” (specification, page 15; see also, e.g., pages 9-12).
The reference relied on by the examiner is:
Satou et al. (Satou) 5,418,071 May 23, 1995
(filed Feb. 4, 1993)
The examiner has rejected the appealed claims under 35 U.S.C. § 103 as being unpatentable
over Satou. We affirm.
Rather than reiterate the respective positions advanced by the examiner and appellants, we refer
to the examiner’s answer and to appellants’ brief for a complete exposition thereof.
Opinion
We have carefully reviewed the record on this appeal and based thereon find ourselves in
agreement with the examiner that the claimed refractory metal silicide target encompassed by appealed
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