U.S. patent application number 09/785858 was filed with the patent office on 2002-02-28 for method of forming an aluminum comprising line having a titanium nitride comprising layer thereon.
Invention is credited to Leiphart, Shane P..
Application Number | 20020025372 09/785858 |
Document ID | / |
Family ID | 23493580 |
Filed Date | 2002-02-28 |
United States Patent
Application |
20020025372 |
Kind Code |
A1 |
Leiphart, Shane P. |
February 28, 2002 |
Method of forming an aluminum comprising line having a titanium
nitride comprising layer thereon
Abstract
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.
Inventors: |
Leiphart, Shane P.; (Boise,
ID) |
Correspondence
Address: |
WELLS ST JOHN ROBERTS GREGORY AND MATKIN
SUITE 1300
601 W FIRST AVENUE
SPOKANE
WA
992013828
|
Family ID: |
23493580 |
Appl. No.: |
09/785858 |
Filed: |
February 16, 2001 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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09785858 |
Feb 16, 2001 |
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09378551 |
Aug 19, 1999 |
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6224942 |
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Current U.S.
Class: |
430/313 ;
257/E21.585; 427/250; 427/383.1; 427/404; 427/96.8; 427/97.2;
430/316; 430/318; 438/656; 438/667; 438/669 |
Current CPC
Class: |
H01L 2221/1078 20130101;
C23C 14/0641 20130101; C23C 14/541 20130101; C23C 14/14 20130101;
H01L 21/7685 20130101; H01L 21/76877 20130101; H01L 21/76867
20130101; H01L 21/76843 20130101 |
Class at
Publication: |
427/96 ; 427/250;
427/383.1; 427/404 |
International
Class: |
C23C 014/00; B05D
001/38; B05D 003/02 |
Claims
1. A method of forming an aluminum comprising line having a
titanium nitride comprising layer thereon, the method comprising:
forming a first layer comprising at least one of elemental aluminum
or an aluminum alloy over a substrate; forming a second layer
comprising an alloy of titanium and the aluminum from the first
layer, the alloy having a higher melting point than that of the
first layer; forming a third layer comprising titanium nitride over
the second layer; and forming the first, second and third layers
into a conductive line.
2. The method of claim 1 wherein the titanium nitride of the third
layer is formed in contact with the second layer.
3. The method of claim 1 wherein an outermost portion of the first
layer is deposited at a temperature of at least about 400.degree.
C.
4. The method of claim 1 wherein an outermost portion of the first
layer is deposited at a temperature of at least about 450.degree.
C.
5. The method of claim 1 comprising forming the second layer to
have a thickness of from about 50 Angstroms to about 150
Angstroms.
6. The method of claim 1 comprising forming the second layer to
have a thickness of from about 100 Angstroms to about 200
Angstroms.
7. The method of claim 1 wherein temperature of at least an outer
portion of the first layer is at least about 360.degree. C. during
forming of the second layer.
8. The method of claim 1 wherein temperature of at least an outer
portion of the first layer is at least about 360.degree. C. during
forming of the third layer.
9. The method of claim 1 wherein the first layer consists
essentially of elemental aluminum.
10. A method of forming an aluminum comprising line having a
titanium nitride comprising layer thereon, the method comprising:
physical vapor depositing a first layer comprising at least one of
elemental aluminum or an aluminum alloy over a substrate; physical
vapor depositing at least one of elemental titanium or a titanium
alloy on the first layer and forming therefrom a second layer
comprising an alloy of titanium and the aluminum from the first
layer, the alloy having a higher melting point than that of the
first layer; physical vapor depositing a third layer comprising
titanium nitride over the second layer; and photopatterning the
first, second and third layers into a conductive line.
11. The method of claim 10 wherein the titanium nitride of the
third layer is deposited in contact with the second layer.
12. The method of claim 10 wherein the second layer forms during
the elemental titanium deposition.
13. The method of claim 10 wherein essentially all the physical
vapor deposited titanium alloys with the aluminum of the first
layer.
14. The method of claim 10 comprising physical vapor depositing
each of the first layer, titanium, and third layer in different
deposition chambers of the same processing tool.
15. The method of claim 10 comprising physical vapor depositing the
titanium and third layer in the same deposition chamber.
16. The method of claim 10 comprising physical vapor depositing the
first layer in two different chambers of the same processing tool,
and physical vapor depositing the titanium and third layer in a
common chamber of the same processing tool.
17. The method of claim 10 comprising physical vapor depositing the
titanium and the third layer in the same deposition chamber without
moving the substrate therefrom intermediate the titanium and third
layer depositions.
18. The method of claim 10 wherein an outermost portion of the
first layer is deposited at a temperature of at least about
400.degree. C.
19. The method of claim 10 wherein an outermost portion of the
first layer is deposited at a temperature of at least about
450.degree. C.
20. The method of claim 10 comprising depositing the second layer
to have a thickness of from about 50 Angstroms to about 150
Angstroms.
21. The method of claim 10 comprising depositing the second layer
to have a thickness of from about 100 Angstroms to about 200
Angstroms.
22. The method of claim 10 wherein the first layer consists
essentially of elemental aluminum, an aluminum alloy, or a mixture
thereof.
23. The method of claim 10 wherein the first layer consists
essentially of elemental aluminum.
24. The method of claim 10 wherein the physical vapor depositing at
least one of elemental titanium or a titanium alloy comprises
physical vapor depositing elemental titanium.
25. The method of claim 10 wherein temperature of at least an outer
portion of the first layer is at least about 360.degree. C. during
the physical vapor depositing of the elemental titanium.
26. The method of claim 10 wherein temperature of at least an outer
portion of the first layer is at least about 360.degree. C. during
the physical vapor depositing of the third layer.
27. A method of forming an aluminum comprising line having a
titanium nitride comprising layer thereon, the method comprising:
in a processing tool, physical vapor depositing a first layer
comprising at least one of elemental aluminum or an aluminum alloy
over a substrate in a first chamber; physical vapor depositing at
least one of elemental titanium or a titanium alloy on the first
layer in a second chamber of the processing tool while at least an
outer portion of the first layer is at a temperature of at least
about 360.degree. C., and forming therefrom a second layer
comprising an alloy of titanium and the aluminum from the first
layer in the second chamber during said depositing, the alloy
having a higher melting point than that of the first layer;
physical vapor depositing a third layer comprising titanium nitride
on the second layer in the second chamber of the processing tool;
removing the substrate from the processing tool after depositing
the third layer; and photopatterning the first, second and third
layers into a conductive line.
28. The method of claim 27 wherein essentially all the physical
vapor deposited titanium alloys with the aluminum of the first
layer.
29. The method of claim 27 comprising depositing the second layer
to have a thickness of from about 50 Angstroms to about 150
Angstroms.
30. The method of claim 27 comprising depositing the second layer
to have a thickness of from about 100 Angstroms to about 200
Angstroms.
31. The method of claim 27 wherein the first layer consists
essentially of elemental aluminum, an aluminum alloy, or a mixture
thereof.
32. The method of claim 27 wherein the first layer consists
essentially of elemental aluminum.
33. The method of claim 27 wherein the physical vapor depositing as
at least one of elemental titanium or a titanium alloy comprises
physical vapor depositing elemental titanium.
34. The method of claim 27 wherein temperature of at least an outer
portion of the first layer is at least about 360.degree. C. during
the physical vapor depositing of the third layer.
Description
TECHNICAL FIELD
[0001] This invention relates to methods of forming aluminum
comprising lines having a titanium nitride comprising layer
thereon.
BACKGROUND OF THE INVENTION
[0002] Conductive metal lines and contacts are one 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.
[0003] 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.TM. 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.degree.
C.
[0004] 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.
[0005] 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.
[0006] 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
[0007] 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.
BRIEF DESCRIPTION OF THE DRAWINGS
[0008] Preferred embodiments of the invention are described below
with reference to the following accompanying drawings.
[0009] FIG. 1 is a diagrammatic sectional view of a semiconductor
wafer fragment processed in accordance with the prior art, and is
discussed in the "Background" section above.
[0010] FIG. 2 is a diagrammatic sectional view of a semiconductor
wafer fragment at one processing step in accordance with an aspect
of the invention.
[0011] FIG. 3 is a view of the FIG. 2 wafer at a processing step
subsequent to that shown by FIG. 2.
[0012] FIG. 4 is a view of the FIG. 2 wafer at a processing step
subsequent to that shown by FIG. 3.
[0013] FIG. 5 is a view of the FIG. 2 wafer fragment at a
processing step subsequent to that shown by FIG. 4.
[0014] FIG. 6 is a view of the FIG. 2 wafer fragment at a
processing step subsequent to that shown by FIG. 5.
[0015] FIG. 7 is a view of the FIG. 2 wafer fragment at a
processing step subsequent to that shown by FIG. 6.
[0016] FIG. 8 is a diagrammatic plan view of a semiconductor wafer
processor utilizable in fabrication of the exemplary semiconductor
wafer depicted in the FIGS. 2-7 embodiment.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0017] This disclosure of the invention is submitted in furtherance
of the constitutional purposes of the U.S. Patent Laws "to promote
the progress of science and useful arts" (Article 1, Section
8).
[0018] Referring initially to FIG. 2, a semiconductor wafer
fragment in process is indicated generally with reference numeral
30. Such comprises a bulk monocrystalline silicon substrate 32
having a diffusion region 34 formed therein. An insulating layer 36
has been formed thereover, with a contact opening 38 having been
formed therethrough to diffusion region 34. In accordance with a
most preferred aspect of the invention, processing would then be
conducted for deposition of subsequent metal layers in a physical
vapor deposition semiconductor processing tool, such as tool 70
depicted in FIG. 8. Such comprises an example processing tool, such
as the Applied Materials Endura 5500.TM. system. Alternate
processing tools are, of course, usable. The depicted system 70
comprises a buffering high vacuum chamber 72 and an ultra-high
transfer chamber 74. Such are interconnected by selectively
openable and closable pass-through sections 76. Buffer chamber 72
is connected with a pair of load-lock chambers 78 within which a
plurality of wafers for processing can be received. A pair of
degassing chambers 80 are also associated with buffer chamber 72.
Wafers, prior to depositions using the tool, can be processed here
to remove water or other materials therefrom. Another pair of
pre-clean or deposition chambers 82 are also associated with buffer
chamber 72. Pre-cleaning of the wafers prior to transfer through
one of passthroughs 76 to transfer chamber 74 can occur here, such
as sputter cleaning using an inert gas.
[0019] Transfer chamber 74 is shown as having five discrete
processing chambers 84, 86, 88, 90, and 92 associated therewith.
Their exemplary functions and operations in accordance with best
mode principles of the invention are described relative to the
processing of the exemplary embodiment wafer from FIGS. 2 through
6.
[0020] Referring to FIG. 3, the FIG. 2 wafer is positioned within
chamber 84 (FIG. 8) for deposition of a titanium layer 40.
Deposition of layer 40 is preferred to provide silicide formation
(not shown) in contact opening 70 at the interface with silicon
material 32/34. Further, such titanium layer provides a wetting
layer to subsequently deposited metal layers. The deposition in the
depicted tool would be by physical vapor deposition (i.e.,
sputtering) using a titanium target. An example would be to provide
2500 watts of power on the target, argon flow of 35 sccm at ambient
temperature, and a pressure of 1.5 mTorr. An exemplary deposition
time is for 15 seconds to produce a layer 40 having a thickness of
approximately 400 Angstroms.
[0021] The FIG. 3 wafer would then be removed from chamber 84 and
positioned within chamber 86. Chamber 86 preferably includes an
elemental aluminum or an aluminum alloy target therein. A layer
comprising at least one of elemental aluminum or an aluminum alloy
is then physical vapor deposited over the substrate. The wafer is
then preferably removed from chamber 86 and positioned within
another aluminum deposition chamber 88. Physical vapor deposition
of aluminum within chamber 88 is then conducted at a higher
temperature, with the desired goal being the ultimate production of
a layer 42 (FIG. 4) having an exemplary thickness of 6000
Angstroms. In the context of this document, layer 42 is referred to
as a first layer, and most preferably consists essentially of
elemental aluminum, an aluminum alloy or a mixture thereof.
Exemplary processing for both the chamber 86 and chamber 88
depositions include argon flow of from 15 to 50 sccm and pressure
at from 0.5 to 5 mTorr. Temperature during the first chamber 86
deposition is preferably at 100.degree. C. or less, while
temperature during deposition in chamber 88 is at 400.degree. C.,
and more preferably at 450.degree. C. or greater. Power during the
first chamber 86 deposition is preferably at from 10,000 Watts to
15,000 Watts, while power during the second chamber 88 deposition
if preferably at from 1000 watts to 2000 watts. Thus, an outermost
portion of layer 42 is preferably deposited at a temperature of at
least about 400.degree. C., and more preferably at a temperature of
at least about 450.degree. C.
[0022] The FIG. 4 wafer is removed from chamber 88 and positioned
within another deposition chamber 90. Here, at least one of
elemental titanium or a titanium alloy is physical vapor deposited
on first layer 42, and a second layer 44 (FIG. 5) is formed
therefrom to comprise an alloy of the depositing titanium and
aluminum from first layer 42. Preferably, alloy second layer 44
forms during and upon contact by the titanium deposition. Further
preferably, essentially all of the titanium deposited alloys with
aluminum of first layer 42. An example and preferred thickness for
layer 44 is from about 50 Angstroms to about 150 Angstroms, and
even more preferably from about 100 Angstroms to about 200
Angstroms. Greater deposition thicknesses are of course possible,
with a less desired result being ultimate formation of a thicker
line layer and possibly an elemental titanium layer being received
over the titanium aluminum alloy layer 44. Example deposition
conditions for layer 44 include a titanium target powered at 1000
watts, argon gas flow rate at 35 sccm, ambient steady state
temperature, and a pressure of 1.5 mTorr to provide a preferred
deposition thickness of from about 100 Angstroms to about 200
Angstroms.
[0023] Where deposition is conducted as typical within chamber 90
as soon as removing the wafer from chamber 88, the wafer will
typically not have cooled down by much more than 25.degree. C., and
perhaps less. Accordingly, at least an outer portion of first layer
42 in such circumstances will have a temperature of at least about
360.degree. C. during the physical vapor depositing of titanium to
form titanium-aluminum alloy layer 44. However, titanium and
aluminum will form an alloy having a significantly higher melting
point than that of first layer 42, and thus preferably effectively
form a shield to migration of aluminum through layer 44 during or
after it's formation, particularly where subsequent processing
occurs at temperatures below the melting point of titanium-aluminum
alloy layer 44.
[0024] Referring to FIG. 6, a third layer 46 comprising titanium
nitride is physical vapor deposited over and preferably on (i.e.,
in contact with) second layer 44. Such processing, preferably is
conducted in the same processing chamber 90 within which layer 44
was formed. Such will also thereby typically be conducted while at
least an outer portion of layer 42 is at a temperature of at least
360.degree. C. An example and preferred thickness for layer 46 is
from about 150 Angstroms to about 250 Angstroms. Example deposition
conditions for forming layer 46 include 6000 watts of power on a
titanium target within chamber 90, an N.sub.2 or other nitrogen
containing gas flow rate of 35 sccm, argon flow rate of 15 sccm,
ambient steady state temperature, and a pressure of 2.0 mTorr.
Accordingly in the preferred embodiment, physical vapor deposition
of titanium to form layer 44 and the physical vapor deposition to
form third layer 46 occur in the same deposition chamber, and
without moving the substrate therefrom intermediate the elemental
titanium and third layer depositions. Alternately but less
preferred, such depositions could be conducted in different
chambers.
[0025] Subsequently, the FIG. 6 wafer would be removed from
deposition chamber 90 and inserted in a cooling chamber 92. Example
cooling would be to flow argon gas therethrough at room temperature
for from 45 seconds to 60 seconds. Thereafter, the substrate would
be removed from processing chamber 92, through one of passageways
76, and ultimately out of buffer chamber 72 through one of
load-lock chambers 78. Accordingly, the substrate is ultimately
removed from processing tool 70.
[0026] Referring to FIG. 7, layers 46, 44, 42 and 40 are preferably
photopatterned (i.e., using photolithography) to form a conductive
line 50 having a contacting plug therebelow making electrical
connection with diffusion region 34. Thus by way of example only,
an aluminum comprising line having a titanium nitride comprising
layer thereon is fabricated.
[0027] Consider, by way of example only, one alternate processing
using processing tool 70. The wafer after completion of processing
in chamber 88 could be moved back into chamber 84, with the next
new wafer to be processed waiting in one of the pass-through
chambers 76. Third layer 46 could be deposited onto the substrate
within chamber 84. Further, one or both of pass-through chambers 76
could be used as cooling chambers.
[0028] The above-described and preferred processing is all
associated with physical vapor deposition, and preferably in a
single processing tool for fabrication of the metal layers over the
substrate, and further using subsequent photopatterning. However,
the invention also contemplates other methods of forming the
depicted and described first, second and third layers, such as by
way of example only, chemical vapor deposition or other techniques
developed or yet to be developed. Further, existing or
to-be-developed processing other than photopatterning could be used
to form an ultimate desired line shape.
[0029] In compliance with the statute, the invention has been
described in language more or less specific as to structural and
methodical features. It is to be understood, however, that the
invention is not limited to the specific features shown and
described, since the means herein disclosed comprise preferred
forms of putting the invention into effect. The invention is,
therefore, claimed in any of its forms or modifications within the
proper scope of the appended claims appropriately interpreted in
accordance with the doctrine of equivalents.
* * * * *