Appeal No. 2001-1090
Application No. 09/477,821
OPINION
We have carefully considered the entire record before us, and we will reverse the
obviousness rejection of claims 1 through 20.
As the title indicates, Nogami recognizes the problem of copper (Cu) electromigration1 from
Cu interconnects into surrounding device structures. Nogami’s method of semiconductor
manufacture starts with the deposit of undoped Cu 13 into hole 12 in dielectric layer 10 (Figure 1).
The undoped Cu 13 is not “co-planar with” the upper surface of the dielectric layer 10. “A layer of
doped Cu 14 is then sputter deposited on the undoped Cu layer 13" (column 5, lines 64 and 65). An
annealing step is then performed to diffuse dopant element atoms from the doped Cu layer 14 into
the undoped Cu layer 13 to thereby transform the undoped Cu layer 13 into a doped Cu layer 20
(Figure 2; column 5, line 66 through column 6, line 2). According to Nogami (column 6, lines 2
through 5), “[b]y annealing to diffuse dopant element atoms from doped Cu layer 14 into undoped
Cu layer 13, the electromigration resistance of Cu layer 20 filling via hole 12 is significantly
improved.” Thereafter, a chemical-mechanical polishing (CMP) step is performed to make the
surface of electromigration resistant Cu via 20 “co-planar with” the upper surface of dielectric layer
10 (Figure 3; column 6, lines 5 through 8).
Appellants and the examiner all recognize that the steps of the claimed invention require
making the in-laid Cu and the surface of the dielectric layer “co-planar with” each other prior to the
1 The same problem is addressed by appellants (specification, page 4, lines 7 through 9).
3
Page: Previous 1 2 3 4 5 6 7 Next
Last modified: November 3, 2007