Semiconductor device manufacturing: process – Coating with electrically or thermally conductive material – To form ohmic contact to semiconductive material
Reexamination Certificate
2001-09-27
2003-02-11
Chaudhari, Chandra (Department: 2813)
Semiconductor device manufacturing: process
Coating with electrically or thermally conductive material
To form ohmic contact to semiconductive material
C438S626000, C438S627000, C438S638000, C438S687000, C438S786000
Reexamination Certificate
active
06518171
ABSTRACT:
BACKGROUND
1. Field of Invention
The invention relates to the field of forming interconnect layers in semiconductor integrated circuits, particularly in connection with damascene process.
2. Prior Art
Low k dielectrics are favored in the formation of interconnect layers in integrated circuits because they reduce the parasitic capacitance between the conductors in these layers. In some cases, the low k dielectric materials are difficult to etch, for instance, they etch slowly and costly equipment is required for their etching. This is the case for a carbon-doped oxide.
FIGS. 1A-1D
show typical prior art processing which requires etching twice through the trench region of an interlayer dielectric (ILD). As shown in
FIG. 1A
, a first opening
10
is formed to define the vias. Now, another low k dielectric etching step is needed as shown in
FIG. 1B
, to define the trench
11
over the underlying via opening. Then as shown in
FIG. 1C
, the dielectric etchant stop used between the interconnect layers is removed to expose the underlying conductor.
FIG. 1D
illustrates the formation of a conductive barrier material to line the via and trench opening. As can be seen, the trench region of the ILD is etched through twice, once as shown in FIG.
1
A and again, as shown in FIG.
1
C. This is both time consuming and costly for some otherwise desirable low k dielectrics.
REFERENCES:
patent: 5705430 (1998-01-01), Avanzino et al.
patent: 5753967 (1998-05-01), Lin
patent: 6114259 (2000-09-01), Sukharev et al.
patent: 6245690 (2001-06-01), Yau et al.
patent: 6251770 (2001-06-01), Uglow et al.
patent: 6277728 (2001-08-01), Ahn et al.
patent: 6287961 (2001-09-01), Liu et al.
Blakely , Sokoloff, Taylor & Zafman LLP
Chaudhari Chandra
Intel Corporation
Smoot Stephen W.
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