Coating processes – Coating by vapor – gas – or smoke – Plural coatings applied by vapor – gas – or smoke
Reexamination Certificate
1999-08-19
2001-05-01
Meeks, Timothy (Department: 1762)
Coating processes
Coating by vapor, gas, or smoke
Plural coatings applied by vapor, gas, or smoke
C427S099300, C427S124000, C427S250000, C427S264000, C427S270000, C427S271000, C427S405000, C427S419100, C427S419700, C204S192150
Reexamination Certificate
active
06224942
ABSTRACT:
TECHNICAL FIELD
This invention relates to methods of forming aluminum comprising lines having a titanium nitride comprising layer thereon.
BACKGROUND OF THE INVENTION
Conductive metal lines and contacts are two of the many components typically fabricated in semiconductor processing of integrated circuitry. One example process of doing so, and problems associated therewith, is described with reference to FIG.
1
. There illustrated is a semiconductor wafer fragment
10
comprised of a bulk monocrystalline silicon substrate
12
. In the context of this document, the term “semiconductor substrate” or “semiconductive substrate” is defined to mean any construction comprising semiconductive material, including, but not limited to, bulk semiconductive materials such as a semiconductive wafer (either alone or in assemblies comprising other materials thereon), and semiconductive material layers (either alone or in assemblies comprising other materials). The term “substrate” refers to any supporting structure, including, but not limited to, the semiconductive substrates described above. An exemplary insulating layer
14
is formed over substrate
12
. A titanium layer
16
is formed over layer
14
. An example thickness for layer
16
is 400 Angstroms. An aluminum or aluminum alloy layer
18
is formed over layer
16
. An example thickness is 6000 Angstroms.
Metal layers
16
and
18
in one aspect of the prior art can be conventionally deposited using physical vapor deposition semiconductor processing tools, such as the Applied Materials Endura 5500™ physical vapor deposition tool. Such a tool comprises multiple processing chambers within which various processing, such as pre-clean, deposition and cooling, are conducted. For example, titanium layer
16
could be deposited in a processing chamber of the tool having a titanium sputtering target received therein. Layer
18
would typically likewise be deposited in another chamber having an aluminum or an aluminum alloy sputtering target received therein. Layer
18
might also be deposited in one or multiple depositions in the same or different aluminum deposition chambers. Typically, a lattermost of such depositions, where multiple depositions are conducted, includes a high temperature sputter deposition at a temperature of, for example, 450° C.
After the aluminum deposition, the wafer is typically moved to another chamber for deposition of a titanium nitride comprising layer
20
. An example thickness for layer
20
is from about 150 Angstroms to about 250 Angstroms. Layer
20
is typically provided to function as an antireflective coating layer which facilitates subsequent photolithographic processing. However, it has been discovered that defects in the form of bright, circular areas or formations
22
have been forming atop layer
20
when viewed by a scanning electron microscope. These defect areas
22
have been determined to be one or combination of aluminum or aluminum oxide apparently resulting from migration of aluminum from layer
18
through cracks formed in layer
20
which exist at least during its deposition. Formation of these defect regions
22
is undesirable. It has been surmised the aluminum migrates through cracks in layer
20
.
A prior art solution to the existing problem has been to position the wafer into a dedicated cooling chamber within the processing tool prior to conducting the titanium nitride deposition in a different chamber. However, the cooling takes a considerable amount of time, and effectively lengthens the amount of time it ultimately takes to process a batch of wafers utilizing the processing tool.
Accordingly, it would desirable to develop alternate methods of eliminating or at least reducing formation of defect regions
22
, preferably without appreciably significantly increasing the overall processing time for a batch of wafers.
SUMMARY
The invention includes methods of forming aluminum containing lines having titanium nitride containing layers thereon, and preferably by physical vapor deposition. In one aspect, a first layer including at least one of elemental aluminum or an aluminum alloy is formed over a substrate. A second layer including an alloy of titanium and the aluminum from the first layer is formed. The alloy has a higher melting point than that of the first layer. A third layer including titanium nitride is formed over the second layer. The first, second and third layers are formed into a conductive line. In one aspect, a method of forming an aluminum containing line having a titanium nitride containing layer thereon includes physical vapor depositing a first layer having at least one of elemental aluminum or an aluminum alloy over a substrate. At least one of elemental titanium or a titanium alloy is physical vapor deposited on the first layer, and formed therefrom is a second layer comprising an alloy of titanium and the aluminum from the first layer. The alloy has a higher melting point than that of the first layer. A third layer comprising titanium nitride is physical vapor deposited over the second layer. The first, second and third layers are photopatterned into a conductive line.
REFERENCES:
patent: 5582881 (1996-12-01), Besser et al.
patent: 5646449 (1997-07-01), Nakamura et al.
patent: 5909635 (1999-06-01), Marieb et al.
patent: 5925227 (1999-07-01), Kobayashi et al.
patent: 5925933 (1999-07-01), Colgan et al.
patent: 6010965 (2000-01-01), Shields
patent: 6028003 (2000-02-01), Frisa et al.
patent: 4-34939 (1992-02-01), None
Barr Michael
Meeks Timothy
Micro)n Technology, Inc.
Wells, St. John, Roberts Gregory & Matkin P.S.
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