Appeal No. 1998-1659
Application No. 08/486,635
Specifically, Lee teaches (column 3, lines 1-6) that d,
the minimum lithographic dimension, equals 2 microns.
Further, when Lee adds a smoothing layer to reduce the size of
the diameter to below d, the slope of the smoothing layer
forms an angle 2 greater than 20E from the vertical to the
substrate (see column 3, lines 7-57, and column 4, lines 21-
26). Figure 5 and the adjacent figure illustrate the result.
Here, d = 2µm,
2 > 20E, and y = the thickness of the material, which equals
7000D or 0.7µm
when d = 2µm. Thus, tan 2 = x/y = [(d-d')/2]/y = [(2-
d')/2]/0.7 = (2-d')/1.4. Since, tan 20E = 0.36397, and
tangent increases as the angle increases between 0E and 90E,
(2-d')/1.4 $ 0.36397, or d' # 1.49044. The ratio of the
lateral cross-sectional area for the
second aperture (with diameter d') to
that of the first aperture (with
diameter d) equals B(d'/2) /B(d/2) ,2 2
which reduces to (d') /d , which is less2 2
than or equal to (1.49044) /2 , or2 2
0.5554. In other words, Lee teaches
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