Appeal No. 2000-1243
Application 08/826,112
reflectivities of the Sb2S3 partially reflective layer 56 as
measured at 650 nm and of the AlCr highly reflective layer 60 as
measured at 780 nm (the Figure 5 embodiment). For Sb 2S3 layer
thicknesses ranging between 128 and 140 nm, the reflectivities of
the highly reflective layer and the partially reflective layer
are greater than 70% and 20%, respectively, as required by the
CD-ROM and DVD-ROM specifications. Id. at 11, ll. 15-27.
The specification
states that Sb2S3 is
also desirable because of its relatively high melting point,
which simplifies the process of coating by sputtering and makes
the resulting film thermally stable. Id. at 11, ll. 28-30.
Appellants attribute the success of using antimony sulfide
as the partially reflecting layer to the fact that its index of
refraction has a high (>3.0) real component (n) for a range of
wavelengths from 600 to 740 nm and a very low imaginary component
4
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