Appeal 2007-1295
Application 10/109,713
high aspect ratios (i.e., deep trenches having narrow trench widths), poor
step coverage (non-uniform surface coverage), and void formation in the
barrier, seed, and bulk interconnect layers of the damascened process (col. 2,
ll. 52-65).
Lopatin teaches the interconnect structure comprising a tungsten
nitride barrier layer 401, formed using atomic layer deposition (ALD),
which has excellent step coverage and adhesion characteristics to the
underlying low dielectric constant layer (col. 5, ll. 19-40). Lopatin discloses
that typically, the ALD process is performed using a Chemical Vapor
Deposition (CVD) process tool (col. 4, ll. 32-34).
Kikkawa describes multilevel Cu interconnect including a
methylsilsesquiazane (MSZ) layer having a low dielectric constant. MSZ is
disclosed to be directly patterned by use of electron beam lithograph or
ultraviolet lithography. This lithography permits a small feature size of 50
nm for damascene lines and provides that via holes could be directly
patterned without using photoresist and dry etching for interlayer dielectric
formation (See p. 253, left column, p. 254, third paragraph).
APA, specification page 8, line 13 to page 9, line 11, teaches the low
k dielectric constant material, methylsilsesquiazane (MSZ), which can be
conveniently patterned by direct patterning, e.g., by direct EB or UV
lithography. Thus, need for using a photoresist and dry etching is
eliminated. Appellants assert that the teaching of the APA is the same as
Kikkawa (Br. 11).
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