Etching a substrate: processes – Gas phase etching of substrate – Etching inorganic substrate
Reexamination Certificate
2000-08-31
2003-04-15
Gulakowski, Randy (Department: 1746)
Etching a substrate: processes
Gas phase etching of substrate
Etching inorganic substrate
C216S049000, C216S067000, C216S072000, C216S080000, C438S710000, C438S723000
Reexamination Certificate
active
06547979
ABSTRACT:
TECHNICAL FIELD
The invention pertains to methods of enhancing selectivity of silicon dioxide relative to one or more organic materials, and further pertains to reaction chamber configurations.
BACKGROUND OF THE INVENTION
Semiconductor processing frequently involves etching of silicon-oxide-containing materials, such as, for example, silicon dioxide, borophosphosilicate glass (BPSG), etc. Semiconductor processing also frequently involves patterning etched materials with organic photoresist masking materials. Organic photoresist materials can be either positive or negative photoresists, and can include, for example, novolac and cyclized synthetic rubber resin. A difficulty which can occur in etching silicon-oxide-containing materials results from limited selectivity of present etch methods for silicon-oxide-containing materials relative to organic masking materials. Such difficulty is described with reference to
FIGS. 1-3
.
Referring first to
FIG. 1
, a semiconductor wafer fragment
10
is illustrated. Wafer fragment
10
comprises a substrate
12
having a silicon-oxide-containing layer
14
thereover. Substrate
12
can comprise, for example, monocrystalline silicon lightly-doped with a p-type background dopant. To aid in interpretation of the claims that follow, the terms “semiconductive substrate” and “semiconductor substrate” are 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.
Layer
14
can comprise, for example, silicon dioxide; can consist essentially of silicon dioxide, or can consist of silicon dioxide. Also layer
14
can comprise a doped silicon oxide, such as, for example, BPSG.
A patterned masking layer
16
is shown formed over silicon-oxide-containing layer
14
. Masking layer
16
can comprise, for example, an organic photoresist material, and can be patterned by photolithographic processing.
Referring to
FIG. 2
, wafer fragment
10
is subjected to etching conditions which etch into silicon-oxide-containing material
14
to form an opening
18
extending therein. A suitable etch for silicon-oxide-containing material
14
is a plasma etch utilizing one or more of CF
4
, C
2
F
6
, H
2
, C
3
F
8
, and CHF
3
.
FIG. 2
shows a thickness of masking layer
16
reduced during the etching of oxide layer
14
. Such reduction in thickness occurs due to non-selectivity of the etch conditions for oxide material
14
relative to masking material
16
. Generally, the etching conditions will have some selectivity for oxide layer
14
, in that the material of oxide layer
14
will etch faster than will the material of organic masking layer
16
. However, the selectivity is not absolute, and accordingly some of the organic material of layer
16
etches during the etching of the silicon oxide of layer
14
.
Referring to
FIG. 3
, wafer fragment
10
is shown after continued etching of layer
14
. Such continued etching has removed layer
16
(
FIG. 2
) from over layer
14
. Such removal of layer
16
can be problematic in further processing steps.
It would be desirable to develop alternative methods for etching silicon-oxide-containing materials with enhanced selectivity for the silicon-oxide-containing materials relative to organic materials.
SUMMARY OF THE INVENTION
In one aspect, the invention encompasses a method of enhancing selectivity of etching silicon dioxide relative to one or more organic substances. A material comprising one or more elements selected from Group VIII of the periodic table is provided within a reaction chamber; and a substrate is provided within the reaction chamber. The substrate has both a silicon-oxide-containing composition and at least one organic substance thereover. The silicon-oxide-containing composition is plasma etched within the reaction chamber. The plasma etching of the silicon-oxide-containing composition has increased selectivity for the silicon oxide of the composition relative to the at least one organic substance than would plasma etching conducted without the material in the chamber.
In another aspect, the invention encompasses a plasma reaction chamber assembly. The assembly comprises at least one interior wall, and at least one liner along the at least one interior wall. The liner comprises one or more of Ru, Fe, Co, Ni, Rh, Pd, Os, W, Ir, Pt and Ti.
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patent: 6117786 (2000-09-01), Khajehnouri et al.
patent: 6251216 (2001-06-01), Okamura et al.
patent: 6265318 (2001-07-01), Hwang et al.
patent: 6284146 (2001-09-01), Kim et al.
patent: 6368517 (2002-04-01), Hwang et al.
patent: 6368518 (2002-04-01), Vaartstra
Hineman Max F.
Li Li
Gulakowski Randy
Kornakov M.
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