U.S. patent application number 09/943146 was filed with the patent office on 2002-10-17 for methods, complexes, and system for forming metal-containing films.
This patent application is currently assigned to Micron Technology, Inc.. Invention is credited to Vaartstra, Brian A..
Application Number | 20020151159 09/943146 |
Document ID | / |
Family ID | 24913015 |
Filed Date | 2002-10-17 |
United States Patent
Application |
20020151159 |
Kind Code |
A9 |
Vaartstra, Brian A. |
October 17, 2002 |
METHODS, COMPLEXES, AND SYSTEM FOR FORMING METAL-CONTAINING
FILMS
Abstract
A method of forming a film on a substrate using Group III metal
complexes. The complexes and methods are particularly suitable for
the preparation of semiconductor structures using chemical vapor
deposition techniques and systems.
Inventors: |
Vaartstra, Brian A.; (Nampa,
ID) |
Correspondence
Address: |
HARNESS, DICKEY & PIERCE, P.L.C.
P.O. BOX 828
BLOOMFIELD HILLS
MI
48303
US
|
Assignee: |
Micron Technology, Inc.
|
Prior
Publication: |
|
Document Identifier |
Publication Date |
|
US 0009864 A1 |
January 24, 2002 |
|
|
Family ID: |
24913015 |
Appl. No.: |
09/943146 |
Filed: |
August 30, 2001 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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09943146 |
Aug 30, 2001 |
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09309825 |
May 11, 1999 |
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6326505 |
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09309825 |
May 11, 1999 |
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08725064 |
Oct 2, 1996 |
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5924012 |
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Current U.S.
Class: |
438/584 ;
257/E21.17; 257/E21.585 |
Current CPC
Class: |
C23C 16/18 20130101;
H01L 21/76877 20130101; C07F 5/066 20130101; C07F 5/00 20130101;
H01L 21/28556 20130101; C07F 5/065 20130101; C23C 16/301
20130101 |
Class at
Publication: |
438/584 |
International
Class: |
H01L 021/20 |
Claims
What is claimed is:
1. A method of manufacturing a semiconductor structure, the method
comprising: providing a semiconductor substrate or substrate
assembly; providing a precursor comprising one or more complexes of
the
formula:M{[(C(R.sup.1).sub.2).sub.n].sub.xN(R.sup.2).sub.3-x}(R.sup.3).su-
b.y(R.sup.4).sub.z (Formula I) wherein: M is a Group III metal;
each R.sup.1, R.sup.2, R.sup.3, and R.sup.4 group is independently
H or an organic group; x=1 to 3; n=1 to 6; y=1 when x=1 and y=3-x
when x=2 or 3; and z=3-x-y; and forming a metal-containing film
from said precursor on a surface of the semiconductor substrate or
substrate assembly; wherein the metal-containing film is a Group
III metal film or a Group III metal alloy film.
2. The method of claim 1 wherein the step of forming a
metal-containing film comprises vaporizing the precursor and
directing it toward the semiconductor substrate or substrate
assembly using a chemical vapor deposition technique.
3. The method of claim 2 wherein the chemical vapor deposition
technique comprises flash vaporization, bubbling, microdroplet
formation, or combinations thereof.
4. The method of claim 1 wherein the semiconductor substrate is a
silicon wafer.
5. The method of claim 1 wherein M is selected from the group
consisting of Al, Ga, and In.
6. The method of claim 1 wherein at least one of R.sup.3 and
R.sup.4 is H.
7. The method of claim 1 wherein each R.sup.1, R.sup.2, R.sup.3,
and R.sup.4 group is independently H or a (C.sub.1-C.sub.30)organic
group.
8. The method of claim 1 wherein each R.sup.1, R.sup.2, R.sup.3,
and R.sup.4 group is independently H or a (C.sub.1-C.sub.20)organic
group.
9. The method of claim 1 wherein each R.sup.1, R.sup.2, R.sup.3,
and R.sup.4 group is independently H or a (C.sub.1-C.sub.4)alkyl
moiety.
10. The method of claim 1 wherein the precursor is a liquid.
11. A method of manufacturing a semiconductor structure, the method
comprising: providing a semiconductor substrate or substrate
assembly; providing a precursor comprising one or more hydride
complexes of the
formula:M{[(C(R.sup.1).sub.2).sub.n].sub.xN(R.sup.2).sub.3-x}(R.sup.3).su-
b.y(R.sup.4).sub.z (Formula I) wherein: M is a Group III metal;
each R.sup.1, R.sup.2, R.sup.3, and R.sup.4 group is independently
H or an organic group, with the proviso that at least one of
R.sup.3 and R.sup.4 is H; x=1 to 3; n=1 to 6; y=1 when x=1 and
y=3-x when x=2 or 3; and z=3-x-y; and forming a metal-containing
film from said precursor on a surface of the semiconductor
substrate or substrate assembly.
12. The method of claim 11 wherein the step of forming a
metal-containing film comprises vaporizing the precursor and
directing it toward the semiconductor substrate or substrate
assembly using a chemical vapor deposition technique.
13. The method of claim 12 wherein the precursor is vaporized in
the presence of a carrier gas.
14. The method of claim 12 wherein the precursor is vaporized in
the presence of a reaction gas.
15. The method of claim 11 wherein the precursor further comprises
one or more compounds containing a Group V element.
16. The method of claim 11 wherein the precursor is a liquid.
17. The method of claim 11 wherein the metal containing film is a
Group III metal film.
18. The method of claim 11 wherein the metal containing film is a
Group III metal alloy film.
19. A method of manufacturing a semiconductor structure, the method
comprising: providing a semiconductor substrate or substrate
assembly; providing a liquid precursor comprising one or more
hydride complexes of the
formula:M{[(C(R.sup.1).sub.2).sub.n].sub.xN(R.sup.2).sub.3-x}(R.sup.3-
).sub.y(R.sup.4).sub.z (Formula I) wherein: M is a Group III metal;
each R.sup.1, R.sup.2, R.sup.3, and R.sup.4 group is independently
H or a (C.sub.1-C.sub.30)organic group, with the proviso that at
least one of R.sup.3 and R.sup.4 is H; x=1 to 3; n=1 to 6; y=1 when
x=1 and y=3-x when x=2 or 3; and z=3-x-y; and vaporizing said
liquid precursor to form vaporized precursor; and directing the
vaporized precursor toward the semiconductor substrate or substrate
assembly to form a metal-containing film on a surface of the
semiconductor substrate or substrate assembly.
20. A method of forming a film on a substrate, the method
comprising: providing a substrate; providing a precursor comprising
one or more complexes of the
formula:M{[(C(R.sup.1).sub.2).sub.n].sub.xN(R.sup.2).sub-
.3-x}(R.sup.3).sub.y(R.sup.4).sub.z (Formula I) wherein: M is a
Group III metal; each R.sup.1, R.sup.2, R.sup.3, and R.sup.4 group
is independently H or an organic group; x=1 to 3; n=1 to 6; y=1
when x=1 and y=3-x when x=2 or 3; and z=3-x-y; and forming a
metal-containing film from said precursor on a surface of the
substrate; wherein the metal-containing film is a Group III metal
film or a Group III metal alloy film.
21. The method of claim 20 wherein the step of forming a
metal-containing film comprises vaporizing the precursor and
directing it toward the substrate using a chemical vapor deposition
technique.
22. The method of claim 20 wherein the precursor is a liquid.
23. A method of forming a film on a substrate, the method
comprising: providing a substrate; providing a precursor comprising
one or more hydride complexes of the
formula:M{[(C(R.sup.1).sub.2).sub.n].sub.xN(R.su-
p.2).sub.3-x}(R.sup.3).sub.y(R.sup.4).sub.z (Formula I) wherein: M
is a Group III metal; each R.sup.1, R.sup.2, R.sup.3, and R.sup.4
group is independently H or a (C.sub.1-C.sub.30)organic group, with
the proviso that at least one of R.sup.3 and R.sup.4 is H; x=1 to
3; n=1 to 6; y=1 when x=1 and y=3-x when x=2 or 3; and z=3-x-y; and
forming a metal-containing film from said precursor on a surface of
the substrate.
24. The method of claim 23 wherein the metal containing film is a
Group III metal film.
25. The method of claim 23 wherein the metal containing film is a
Group III metal alloy film.
26. The method of claim 23 wherein the step of forming a
metal-containing film comprises vaporizing the precursor and
directing it toward the substrate using a chemical vapor deposition
technique.
27. The method of claim 26 wherein the precursor is vaporized in
the presence of a carrier gas.
28. The method of claim 26 wherein the precursor is vaporized in
the presence of a reaction gas.
29. The method of claim 23 wherein the precursor further comprises
one or more compounds containing a Group V element.
30. The method of claim 23 wherein the precursor is a liquid.
31. A method of forming a film on a substrate, the method
comprising: providing a substrate; providing a liquid precursor
comprising one or more hydride complexes of the
formula:M{[(C(R.sup.1).sub.2).sub.n].sub.xN-
(R.sup.2).sub.3-x}(R.sup.3).sub.y(R.sup.4).sub.z (Formula I)
wherein: M is a Group III metal; each R.sup.1, R.sup.2, R.sup.3,
and R.sup.4 group is independently H or a (C.sub.1-C.sub.30)organic
group, with the proviso that at least one of R.sup.3 and R.sup.4 is
H; x=1 to 3; n=1 to 6; y=1 when x=1 and y=3-x when x=2 or 3; and
z=3-x-y; and vaporizing said liquid precursor to form vaporized
precursor; and directing the vaporized precursor toward the
substrate to form a metal-containing film on a surface of the
substrate.
32. A hydride complex of the
formula:M{[(C(R.sup.1).sub.2).sub.n].sub.xN(R-
.sup.2).sub.3-x}(R.sup.3).sub.y(R.sup.4).sub.z (Formula I) wherein:
(a) M is a Group III metal; (b) each R.sup.1, R.sup.2, R.sup.3, and
R.sup.4 group is independently H or an organic group, with the
proviso that at least one of R.sup.3 and R.sup.4 is H; (c) x=1 to
3; (d) n=1 to 6; (e) y=1 when x=1 and y=3-x when x=2 or 3; and (f)
z=3-x-y.
33. The complex of claim 32 wherein M is selected from the group
consisting of Al, Ga, and In.
34. The complex of claim 32 wherein each R.sup.1, R.sup.2, R.sup.3,
and R.sup.4 group is independently H or a (C.sub.1-C.sub.30)organic
group.
35. The complex of claim 32 wherein each R.sup.1, R.sup.2, R.sup.3,
and R.sup.4 group is independently H or a (C.sub.1-C.sub.20)organic
group.
36. The complex of claim 32 wherein each R.sup.1, R.sup.2, R.sup.3,
and R.sup.4 group is independently H or a (C.sub.1-C.sub.4)alkyl
moiety.
37. A chemical vapor deposition system comprising: a deposition
chamber having a substrate positioned therein; a vessel containing
a precursor comprising one or more complexes of the
formula:M{[(C(R.sup.1).sub.2).sub-
.n].sub.xN(R.sup.2).sub.3-x}(R.sup.3).sub.y(R.sup.4).sub.z (Formula
I) wherein: M is a Group III metal; each R.sup.1, R.sup.2, R.sup.3,
and R.sup.4 group is independently H or an organic group; x=1 to 3;
n=1 to 6; y=1 when x=1 and y=3-x when x=2 or 3; and z=3-x-y; and a
source of an inert carrier gas for transferring the precursor to
the chemical vapor deposition chamber.
38. The system of claim 37 wherein the substrate is a silicon
wafer.
39. The system of claim 37 wherein M is selected from the group
consisting of Al, Ga, and In.
40. The system of claim 37 wherein at least one of R.sup.3 and
R.sup.4 is H.
41. The system of claim 37 wherein each R.sup.1, R.sup.2, R.sup.3,
and R.sup.4 group is independently H or a
(C.sub.1-C.sub.8)hydrocarbon group.
42. The system of claim 37 wherein each R.sup.1, R.sup.2, R.sup.3,
and R.sup.4 group is independently H or a
(C.sub.1-C.sub.20)hydrocarbon group.
43. The system of claim 37 wherein each R.sup.1, R.sup.2, R.sup.3,
and R.sup.4 group is independently H or a (C.sub.1-C.sub.4)alkyl
moiety.
44. The system of claim 37 wherein the precursor is a liquid.
45. The system of claim 37 further comprising a source of a
reaction gas.
46. The system of claim 37 wherein the precursor further comprises
one or more compounds containing a Group V element.
47. A chemical vapor deposition system comprising: a deposition
chamber having a substrate positioned therein; a vessel containing
a precursor comprising one or more complexes of the
formula:M{[(C(R.sup.1).sub.2).sub-
.n]N(R.sup.2).sub.2}(R.sup.3)(R.sup.4) wherein: M is a Group III
metal; each R.sup.1, R.sup.2, R.sup.3, and R.sup.4 group is
independently H or a (C.sub.1-C.sub.30)hydrocarbon group wherein
optionally R.sup.3 and R.sup.4 are joined to form a ring or rings
with the metal and none of the other R groups are joined together
to form ring systems; and n=1 to 6.
48. The system of claim 47 wherein the substrate is a silicon
wafer.
49. The system of claim 47 wherein M is selected from the group
consisting of Al, Ga, and In.
50. The system of claim 47 wherein at least one of R.sup.3 and
R.sup.4 is H.
51. The system of claim 47 wherein each R.sup.1, R.sup.2, R.sup.3,
and R.sup.4 group is independently H or a
(C.sub.1-C.sub.8)hydrocarbon group.
52. The system of claim 47 wherein each R.sup.1, R.sup.2, R.sup.3,
and R.sup.4 group is independently H or a
(C.sub.1-C.sub.20)hydrocarbon group.
53. The system of claim 47 wherein each R.sup.1, R.sup.2, R.sup.3,
and R.sup.4 group is independently H or a (C.sub.1-C.sub.4)alkyl
moiety.
54. The system of claim 47 wherein the precursor is a liquid.
55. The system of claim 47 further comprising a source of a
reaction gas.
56. The system of claim 47 wherein the precursor further comprises
one or more compounds containing a Group V element.
57. A chemical vapor deposition system comprising: a deposition
chamber having a substrate positioned therein; a vessel containing
a precursor comprising one or more hydride complexes of the
formula:M{[(C(R.sup.1).su-
b.2).sub.n]N(R.sup.2).sub.2}(R.sup.3)(R.sup.4) wherein: M is a
Group III metal; each R.sup.1, R.sup.2, R.sup.3, and R.sup.4 group
is independently H or a (C.sub.1-C.sub.30) hydrocarbon group, with
the proviso that at least one of R.sup.3 and R.sup.4 is H and none
of the R groups are joined together to form ring systems; and n=1
to 6.
Description
FIELD OF THE INVENTION
[0001] This invention relates to methods and complexes for forming
metal-containing films, such as metal or metal alloy films,
particularly during the manufacture of semiconductor structures.
The complexes include a Group III metal, and are particularly
suitable for use in a chemical vapor deposition system.
BACKGROUND OF THE INVENTION
[0002] Aluminum is one of the three primary materials used today in
semiconductor structures, the other two being silicon and silicon
dioxide. It is primarily used in thin films as an interconnect
between the specific structures formed on semiconductor substrates
or substrate assemblies. Aluminum has been an important material in
the fabrication of semiconductor structures because of its high
conductivity, low resistivity (2.7 .mu..OMEGA.-cm), high adherence
to silicon and silicon dioxide, and low stress. And its use is
expanding into other metallization applications. For example, it is
being examined to replace tungsten in contacts or vias (i.e., very
small openings located, for example, between surface conductive
paths and or "wiring" and active devices on underlying layers),
which are getting narrower and deeper, and harder to fill with
metal.
[0003] Aluminum alloys are also used in semiconductor structures,
including alloys of aluminum with copper, titanium, etc., and
combinations thereof. The addition of small quantities (typically,
about 0.1-4%) of other metals to aluminum improves the
electromigration resistance and reduces the propensity of aluminum
thin-films to form hillocks (i.e., protrusions on the aluminum film
surface). Such films, however, have increased resistivity over that
of pure aluminum films.
[0004] In some applications, aluminum films are deposited using
sputtering techniques; however, sputtered aluminum is not effective
at filling contacts or vias because of shoulders or overhangs that
form at the contact openings. These overhangs can lead to the
formation of keyhole-shaped voids. Various collimation techniques
help reduce this problem, but typically not enough to enable
complete filling of very small geometries (e.g., less than about
0.5 .mu.m). Therefore, it is desirable to use chemical vapor
deposition (CVD) to form aluminum and aluminum alloy films.
[0005] Dimethylaluminum hydride has emerged as one of the preferred
materials for aluminum metallization by CVD. A serious problem with
this material, however, is its pyrophoricity. This problem has been
addressed to some degree by the addition of amines to the compound
to act as stabilizing Lewis base donors to the aluminum center.
However, such precursor compounds are still pyrophoric, albeit to a
lesser extent, and an additional complicating factor is introduced
into the vapor pressure behavior of the precursor as a result of
dissociation of the amine. Thus, there is a continuing need for
methods and precursors for the deposition of aluminum and aluminum
alloy films, as well as other Group III metal or metal alloy films,
on semiconductor structures, particularly using vapor deposition
processes.
SUMMARY OF THE INVENTION
[0006] The present invention provides complexes and methods for
forming metal-containing films, particularly Group III
metal-containing films on substrates, such as semiconductor
substrates or substrate assemblies during the manufacture of
semiconductor structures. The method involves forming a
metal-containing film using a Group III metal complex, preferably a
Group III metal hydride complex. The metal-containing film can be
used in various metallization layers, particularly in multilevel
interconnects, in an integrated circuit structure.
[0007] The metal-containing film can be a single Group III metal,
or a metal alloy containing a mixture of Group III metals or a
Group III metal and one or more metals or metalloids from other
groups in the Periodic Chart, such as copper, silicon, titanium,
vanadium, niobium, molybdenum, tungsten, scandium, etc.
Furthermore, for certain preferred embodiments, the
metal-containing film can be a nitride, phosphide, arsenide,
stibnide, or combination thereof. That is, the metal-containing
film can be a Group III-V (e.g., GaAs) semiconductor layer.
[0008] Thus, in the context of the present invention, the term
"Group III metal-containing film" or simply "metal-containing film"
includes, for example, relatively pure films of aluminum, gallium,
or indium, alloys of aluminum, gallium, and/or indium with or
without other non-pnicogen metals or metalloids, as well as
complexes of these metals and alloys with Group V elements (N, P,
As, Sb) or mixtures thereof. The terms "single Group III metal
film" or "Group III metal film" refer to films of aluminum,
gallium, or indium, for example. The terms "Group III metal alloy
film" or "metal alloy film" refers to films of aluminum, gallium,
and/or indium alloys with or without other metals or metalloids,
for example. That is, if there are no metals or metalloids from
groups in the Periodic Chart other than Group III, the alloy films
contain combinations of aluminum, gallium, and indium. Preferably,
the metal alloy films do not contain Group V metals or metalloids
(i.e., pnicogens).
[0009] One preferred method of the present invention involves
forming a film on a substrate, such as a semiconductor substrate or
substrate assembly during the manufacture of a semiconductor
structure, by: providing a substrate (preferably, a semiconductor
substrate or substrate assembly); providing a precursor comprising
one or more complexes of the formula:
M{[(C(R.sup.1).sub.2).sub.n].sub.xN(R.sup.2).sub.3-x}(R.sup.3).sub.y(R.sup-
.4).sub.z (Formula I)
[0010] wherein: M is a Group III metal; each R.sup.1, R.sup.2,
R.sup.3, and R.sup.4 is independently H or an organic group; x=1 to
3; n=1 to 6; y=1 when x=1 and y=3-x when x=2 or 3; and z=3-x-y; and
forming a metal-containing film from said precursor on a surface of
the substrate (preferably, the semiconductor substrate or substrate
assembly). The metal-containing film is a Group III metal film or a
Group III metal alloy film. Using such methods the complexes of
Formula I are converted in some manner (e.g., decomposed thermally)
and deposited on a surface to form a Group III metal-containing
film. Thus, the film is not simply a film of the complex of Formula
I.
[0011] The complexes of Formula I are neutral complexes and may be
liquids or solids at room temperature. If they are solids, they are
preferably sufficiently soluble in an organic solvent to allow for
vaporization by flash vaporization, bubbling, microdroplet
formation, etc. However, these complexes can also be vaporized or
sublimed from the solid state using known chemical vapor deposition
techniques.
[0012] Another method of the present invention involves forming a
film on a substrate, such as a semiconductor substrate or substrate
assembly during the manufacture of a semiconductor structure, by:
providing a substrate (preferably, a semiconductor substrate or
substrate assembly); providing a precursor comprising one or more
hydride complexes of the formula:
M{[(C(R.sup.1).sub.2).sub.n].sub.xN(R.sup.2).sub.3-x}(R.sup.3).sub.y(R.sup-
.4).sub.z (Formula I)
[0013] wherein: M is a Group III metal; each R.sup.1, R.sup.2,
R.sup.3, and R.sup.4 is independently H or an organic group with
the proviso that at least one of R.sup.3 and R.sup.4 is H; x=1 to
3; n=1 to 6; y=1 when x=1 and y=3-x when x=2 or 3; and z =3-x-y;
and forming a metal-containing film from said precursor on a
surface of the substrate.
[0014] Yet another method of forming a metal-containing film on a
substrate, such as a semiconductor substrate or substrate assembly
during the manufacture of a semiconductor structure, by: providing
a substrate (preferably, a semiconductor substrate or substrate
assembly); providing a liquid precursor comprising one or more
hydride complexes of the formula:
M{[(C(R.sup.1).sub.2).sub.n].sub.xN(R.sup.2).sub.3-x}(R.sup.3).sub.y(R.sup-
.4).sub.z (Formula I)
[0015] wherein: M is a Group III metal; each R.sup.1, R.sup.2,
R.sup.3, and R.sup.4 group is independently H or a
(C.sub.1-C.sub.30)organic group, with the proviso that at least one
of R.sup.3 and R.sup.4 is H; x=1 to 3; n=1 to 6; y=1 when x=1 and
y=3-x when x=2 or 3; and z=3-x-y vaporizing said liquid precursor
to form vaporized precursor; and directing the vaporized precursor
toward the substrate to form a metal-containing film on a surface
of the substrate.
[0016] Thus, preferred embodiments of the methods of the present
invention involve the use of one or more chemical vapor deposition
techniques, although this is not necessarily required. That is, for
certain embodiments, sputtering, spin-on coating, etc., can be
used.
[0017] The methods of the present invention are particularly well
suited for forming films on a surface of a semiconductor substrate
or substrate assembly, such as a silicon wafer, with or without
layers or structures formed thereon, used in forming integrated
circuits. It is to be understood that the method of the present
invention is not limited to deposition on silicon wafers; rather,
other types of wafers (e.g., gallium arsenide wafer, etc.) can be
used as well. Also, the methods of the present invention can be
used in silicon-on-insulator technology. Furthermore, substrates
other than semiconductor substrates or substrate assemblies can be
used in the method of the present invention. These include, for
example, fibers, wires, etc. If the substrate is a semiconductor
substrate or substrate assembly, the films can be formed directly
on the lowest semiconductor surface of the substrate, or they can
be formed on any of a variety of the layers (i.e., surfaces) as in
a patterned wafer, for example. Thus, the term "semiconductor
substrate" refers to the base semiconductor layer, e.g., the lowest
layer of silicon material in a wafer or a silicon layer deposited
on another material such as silicon on sapphire. The term
"semiconductor substrate assembly" refers to the semiconductor
substrate having one or more layers or structures formed thereon.
The compounds of Formula I incorporate features that make them
selective for silicon over silicon dioxide.
[0018] Also, the present invention provides a hydride complex of
Formula I wherein: M is a Group III metal (preferably Al, Ga, In);
each R.sup.1, R.sup.2, R.sup.3, and R.sup.4 group is independently
H or an organic group, with the proviso that at least one of
R.sup.3 and R.sup.4 is H; x=1 to 3; n=1 to 6; y=1 when x=1 and
y=3-x when x=2 or 3; and z=3-x-y.
[0019] A chemical vapor deposition system is also provided. The
system includes a deposition chamber having a substrate positioned
therein; a vessel containing a precursor comprising one or more
complexes of Formula I wherein M is a Group III metal, each
R.sup.1, R.sup.2, R.sup.3, and R.sup.4 group is independently H or
an organic group, x=1 to 3, n=1 to 6, y=1 when x=1 and y=3-x when
x=2 or 3, and z=3-x-y; and a source of an inert carrier gas for
transferring the precursor to the chemical vapor deposition
chamber.
BRIEF DESCRIPTION OF THE DRAWINGS
[0020] FIG. 1 is a cross-sectional schematic of a semiconductor
contact or via having an aluminum film deposited in accordance with
the method of the present invention.
[0021] FIG. 2 is a schematic of a chemical vapor deposition system
suitable for use in the method of the present invention.
DETAILED DESCRIPTION
[0022] The present invention provides a method of forming a Group
III metal-containing film using one or more Group III metal
complexes, preferably a Group III metal hydride complex. These
complexes are mononuclear (i.e., monomers in that they contain one
metal per molecule). Preferred embodiments display few
intermolecular forces of attraction. Such complexes are generally
volatile and transportable in the gas phase. They preferably have
vapor pressures sufficiently low such that they are liquids at room
temperature, although they can be solids. If they are solids, they
are preferably soluble in organic solvents, such as aromatic and
aliphatic hydrocarbons, nitriles, ethers, amines, etc., which
allows for vaporization as a homogeneous mixture by direct liquid
injection. They are also generally compatible with each other, so
that mixtures of variable quantities of the complexes will not
interact to significantly change their physical properties.
Preferred embodiments are also generally nonpyrophoric.
[0023] Thus, many of the complexes described herein are suitable
for use in chemical vapor deposition (CVD) techniques, such as
flash vaporization techniques, bubbler techniques, and the
microdroplet techniques. However, these complexes can also be
vaporized or sublimed from the solid state using other known CVD
techniques. Preferred embodiments of the complexes described herein
are particularly suitable for low temperature CVD, i.e., deposition
techniques involving temperatures of about 50-200.degree. C.
[0024] One preferred method of the present invention involves
vaporizing a precursor that includes one or more Group III metal
complexes. For certain embodiments, the precursor can also include
one or more Group V complexes (i.e., a compound containing N, P,
As, or Sb). Also, the precursor can include complexes containing
other metals or metalloids (preferably, non-pnicogen metals or
metalloids).
[0025] The precursor can be vaporized in the presence of an inert
carrier gas to form a relatively pure metal or metal alloy film.
The inert carrier gas is typically selected from the group
consisting of nitrogen, helium, and argon. In the context of the
present invention, an inert carrier gas is one that does not
interfere with the formation of the metal-containing film. Whether
done in the presence of a carrier gas or not, the vaporization is
preferably done in the absence of oxygen to avoid oxygen
contamination of the films.
[0026] Alternatively, however, the precursor can be vaporized in
the presence of a reaction gas to form a film. The reaction gas can
be selected from a wide variety of gases reactive with the
complexes described herein, at least at a surface under the
conditions of chemical vapor deposition. Examples of reaction gases
include oxygen, nitrous oxide, ammonia, silane, water vapor,
hydrogen sulfide, hydrogen selenide, hydrogen telluride. Various
combinations of carrier gases and/or reaction gases can be used in
the methods of the present invention to form metal containing
films.
[0027] The Group III metal complexes described herein are four
coordinate complexes having one multidentate ligand, which
typically has at least one carbon atom that covalently bonds to the
metal and one nitrogen atom that forms a dative bond with the
metal. The designation "hydride complex" refers to a Group III
metal complex containing at least one negatively charged hydride
ligand in addition to the multidentate ligand. The multidentate
ligand stabilizes the metal complex by incorporating the nitrogen
donor atom into the ligand in such a way as to negate dissociation
of the ligand prior to thermal decomposition.
[0028] The Group III metal complex is of the following formula:
M{[(C(R.sup.1).sub.2).sub.n].sub.xN(R.sup.2).sub.3-x}(R.sup.3).sub.y(R.sup-
.4).sub.z (Formula I)
[0029] wherein: M is a Group III metal (preferably, Al, Ga, In);
each R (i.e., R.sup.1, R.sup.2, R.sup.3, R.sup.4) is independently
H or an organic group (preferably, with the proviso that at least
one of R.sup.3and R.sup.4 is H); x=1 to 3; n=1 to 6; y=1 when x=1
and y=3-x when x=2 or 3; and z=3-x-y. More preferably, R.sup.2 is
an organic group and at least one of R.sup.3 and R.sup.4 is H. The
ligand [(C(R.sup.1).sub.2).sub.n].sub.xN(R.sup.2).sub.3-x can bond
to the central metal through the nitrogen and at least one of the
C(R.sup.1).sub.2 units. The R.sup.3 and R.sup.4 groups can be
joined to form a ring or rings with the metal.
[0030] A preferred class of complexes of Formula I include hydride
complexes wherein: M is a Group III metal (preferably, Al, Ga, In);
each R (i.e., R.sup.1, R.sup.2, R.sup.3, R.sup.4) is independently
H or an organic group, with the proviso that at least one of
R.sup.3 and R.sup.4 is H; x=1 to 3; n=1 to 6; y=1 when x=1 and
y=3-x when x=2 or 3; and z=3-x-y. For these hydride complexes, more
preferably, R.sup.2 is an organic group. This class of complexes of
Formula I (i.e., the hydrides) are particularly advantageous
because additional reducing equivalents are present in the complex
(as a result of the hydride ligand(s)), which leads to less carbon
contamination of the films formed upon decomposition of the
complexes.
[0031] As used herein, the term "organic group" means a hydrocarbon
group that is classified as an aliphatic group, cyclic group, or
combination of aliphatic and cyclic groups (e.g., alkaryl and
aralkyl groups). In the context of the present invention, the term
"aliphatic group" means a saturated or unsaturated linear or
branched hydrocarbon group. This term is used to encompass alkyl,
alkenyl, and alkynyl groups, for example. The term "alkyl group"
means a saturated linear or branched hydrocarbon group including,
for example, methyl, ethyl, isopropyl, t-butyl, heptyl, dodecyl,
octadecyl, amyl, 2-ethylhexyl, and the like. The term "alkenyl
group" means an unsaturated, linear or branched hydrocarbon group
with one or more carbon-carbon double bonds, such as a vinyl group.
The term "alkynyl group" means an unsaturated, linear or branched
hydrocarbon group with one or more carbon-carbon triple bonds. The
term "cyclic group" means a closed ring hydrocarbon group that is
classified as an alicyclic group, aromatic group, or heterocyclic
group. The term "alicyclic group" means a cyclic hydrocarbon group
having properties resembling those of aliphatic groups. The term
"aromatic group" or aryl group" means a mono- or polynuclear
aromatic hydrocarbon group. The term "heterocyclic group" means a
closed ring hydrocarbon in which one or more of the atoms in the
ring is an element other than carbon (e.g., nitrogen, oxygen,
sulfur, etc.).
[0032] In metal complexes such as this, substitution is not only
tolerated, but is often advisable. Thus, substitution is
anticipated in the complexes of the present invention. As a means
of simplifying the discussion and the recitation of certain
terminology used throughout this application, the terms "group" and
"moiety" are used to differentiate between chemical species that
allow for substitution or that may be substituted and those that do
not so allow or may not be so substituted. Thus, when the term
"group" is used to describe a chemical substituent, the described
chemical material includes the unsubstituted group and that group
with nonperoxidic O, N, or S atoms, for example, in the chain as
well as carbonyl groups or other conventional substitution. Where
the term "moiety" is used to describe a chemical compound or
substituent, only an unsubstituted chemical material is intended to
be included. For example, the phrase "alkyl group" is intended to
include not only pure open chain saturated hydrocarbon alkyl
substituents, such as methyl, ethyl, propyl, t-butyl, and the like,
but also alkyl substituents bearing further substituents known in
the art, such as hydroxy, alkoxy, alkylsulfonyl, halogen atoms,
cyano, nitro, amino, carboxyl, etc. Thus, "alkyl group" includes
ether groups, haloalkyls, nitroalkyls, carboxyalkyls,
hydroxyalkyls, sulfoalkyls, etc. On the other hand, the phrase
"alkyl moiety" is limited to the inclusion of only pure open chain
saturated hydrocarbon alkyl substituents, such as methyl, ethyl,
propyl, t-butyl, and the like.
[0033] For the R groups (R.sup.1, R.sup.2, R.sup.3, and R.sup.4) in
the complexes of Formula I, H or (C.sub.1-C.sub.30)organic groups
are preferred, H or (C.sub.1-C.sub.20)organic groups are more
preferred, and H or (C.sub.1-C.sub.8)organic groups are most
preferred. Of the organic groups, nonaromatic groups (e.g.,
aliphatic groups and alicyclic groups, which may or may not include
unsaturation, and which may or may not include heteroatoms such as
N, O, S, P, Si, etc.) are preferred. Of these, the aliphatic groups
are more preferred, and alkyl moieties (particularly "lower"
(C.sub.1-C.sub.4)alkyl moieties) are most preferred. The R.sup.3
and R.sup.4 groups can be joined to form a ring or rings.
[0034] Thus, the complexes of Formula I (wherein R.sup.1=H, n=3,
x=1, 2, or 3, R.sup.2 is a lower alkyl moiety, and R.sup.3 and
R.sup.4 are H or a lower alkyl moiety) can take the following forms
(which are representative only): 1
[0035] The complexes of Formula I are neutral complexes and may be
liquids or solids at room temperature. If they are solids, they are
preferably sufficiently soluble in an organic solvent to allow for
vaporization by flash vaporization, bubbling, microdroplet
formation, etc. However, these complexes can also be vaporized or
sublimed from the solid state using known chemical vapor deposition
techniques.
[0036] Various combinations of the complexes described herein can
be used in precursors for chemical vapor deposition. Alternatively,
certain complexes described herein can be used in other deposition
techniques, such as sputtering, spin-on coating, and the like.
Typically, those complexes containing R groups with a low number of
carbon atoms (e.g., 1-4 carbon atoms per R group) are suitable for
use with vapor deposition techniques. Those complexes containing R
groups with a higher number of carbon atoms (e.g., 5-12 carbon
atoms per R group) are generally suitable for spin-on or dip
coating. Preferably, however, chemical vapor deposition techniques
are desired because they are more suitable for deposition on
semiconductor substrates or substrate assemblies, particularly in
contact openings which are extremely small and require conformally
filled layers of metal.
[0037] For preparation of films containing Group III-V (e.g., GaAs)
semiconductor materials, the precursors described herein contain
one or more complexes of Formula I and an appropriate source of the
Group V element. Such sources of Group V elements include compounds
such as NH.sub.3, PH.sub.3, AsH.sub.3, Me.sub.3As, Me.sub.3Sb,
Me.sub.3P, EtAsH.sub.2, Me.sub.2.sup.tBuSb, etc.
[0038] For the preparation of alloy films, two or more complexes of
Formula I can be combined in a precursor mixture (e.g.,
AlH.sub.2(CH.sub.2CH.sub.2CH.sub.2NMe.sub.2) and
GaH.sub.2(CH.sub.2CH.sub- .2CH.sub.2NMe.sub.2) for an Al-Ga alloy).
Alternatively, at least one complex of Formula I can be combined
with another complex can be combined in a precursor mixture (e.g.,
AlH.sub.2(CH.sub.2CH.sub.2CH.sub.2NMe.sub.2- ) and
(Cu(PMe.sub.3)(hfac) for an Al-Cu alloy).
[0039] The complexes of the present invention can be prepared by a
variety of methods known to one of skill in the art. For example,
AlH.sub.2(CH.sub.2CH.sub.2CH.sub.2NMe.sub.2) can be prepared by
reacting AlCl.sub.3 with ClMg(CH.sub.2).sub.3NMe.sub.2 followed by
reduction.
[0040] As stated above, the use of the complexes of Formula I and
methods of forming metal-containing films of the present invention
are beneficial for a wide variety of thin film applications in
semiconductor structures, particularly various metallization
layers. For example, such applications include multilevel
interconnects in an integrated circuit structure. Typically, thin
films of Group III metals, such as aluminum, and alloys thereof are
deposited as polycrystalline materials, usually in the 0.5-1.5
.mu.m thickness range.
[0041] A specific example of where a film formed from the complexes
of the present invention would be useful is the structure shown in
FIG. 1. The substrate 16 may be in the form of an n-channel MOSFET
(n-channel metal-oxide semiconductor field-effect transistor),
which may be used in a DRAM memory device. As shown, substrate 16
is a p-type silicon having two n-type silicon islands 20 and 22,
representing the transistor source and drain. Such a construction
is well known. The gate for the transistor is formed by a
metal/polysilicon layer 24 deposited over a silicon dioxide layer
26. A relatively thick layer of an insulating silicon dioxide 28
overlies the active areas on substrate 16.
[0042] To connect the MOSFET with conductive paths on the surface
of the device, contacts 30 and 32 have been etched through oxide
layer 28 down to the surface of substrate 16. A metal or metal
silicide layer 34, such as titanium silicide, is deposited and
formed at the base of contacts 30 and 32. A thin, conformal barrier
layer of a refractory metal nitride 36 (e.g., titanium nitride,
titanium aluminum nitride, titanium nitride silicide) is deposited
over the walls of the contacts. Because of the presence of the
conductive barrier layer, the electrical contact path is excellent
and the aluminum metal 38 which is deposited over the refractory
metal nitride barrier layer is prevented from attacking the
substrate surfaces.
[0043] The method of the present invention can be used to deposit a
metal-containing film, preferably a metal or metal alloy film, on a
variety of substrates, such as a semiconductor wafer (e.g., silicon
wafer, gallium arsenide wafer, etc.), glass plate, etc., and on a
variety of surfaces of the substrates, whether it be directly on
the substrate itself or on a layer of material deposited on the
substrate as in a semiconductor substrate assembly. The film is
deposited upon thermal decomposition of a Group III metal complex
that is preferably either liquid at the temperature of deposition
or soluble in a suitable solvent that is not detrimental to the
substrate, other layers thereon, etc. Preferably, however, solvents
are not used; rather, the Group III metal complexes are liquid and
used neat. The method of the present invention preferably utilizes
vapor deposition techniques, such as flash vaporization, bubbling,
etc.
[0044] Conventional bubbler technology can be used to form films
from the complexes of Formula I described above. In conventional
bubbler technology, a carrier gas, typically nitrogen, is bubbled
through the precursor (which is either a liquid or is dissolved in
a liquid solvent) to sweep some of the precursor molecules into the
processing chamber.
[0045] Alternatives to conventional bubbler technology include an
approach wherein the precursor is heated and vapors are drawn off
and controlled by a vapor mass flow controller. Further, another
way is to pump the gas through the precursor using either a very
precise metering pump or a liquid mass flow controller up to the
point where it enters the reaction chamber. At that point, it can
either be flash vaporized or injected directly into a mixing
chamber and showerhead where it is vaporized. As described in the
article entitled, "Metalorganic Chemical Vapor Deposition By Pulsed
Liquid Injection Using An Ultrasonic Nozzle: Titanium Dioxide on
Sapphire from Titanium (IV) Isopropoxide," by Versteeg, et al.,
Journal of the American Ceramic Society, 78, 2763-2768 (1995) a
metalorganic CVD process utilizes pulsed on/off liquid injection in
conjunction with atomization by an ultrasonic, piezoelectrically
driven nozzle to deliver such metalorganic precursors. The pulse
injection is said to allow control of film deposition rates, as
fine as monolayers per pulse. The ultrasonic nozzle provides a mist
of droplets into the processing chamber of a reactor for
reproducible vaporization of the liquid precursor. Such a delivery
system performs the vaporization in the processing chamber.
[0046] The complexes of Formula I are particularly well suited for
use with vapor deposition systems, as described in copending
application U.S. Ser. No. ______ entitled "Method and Apparatus for
Vaporizing Liquid Precursors and System for Using Same," filed on
even date herewith. Generally, using the method described therein,
the vaporization of a liquid precursor or precursor dissolved in a
liquid medium is carried out in two stages. First, the precursor is
atomized or nebulized generating high surface area microdroplets or
mist. In the second stage, the constituents of the microdroplets or
mist are vaporized by intimate mixture of the heated carrier gas.
This two stage vaporization approach provides a reproducible
delivery for precursors (either liquid or dissolved in a liquid
medium) and provides reasonable growth rates, particularly in
device applications with small dimensions.
[0047] A typical chemical vapor deposition (CVD) system that can be
used to perform the process of the present invention is shown in
FIG. 2. The system includes an enclosed chemical vapor deposition
chamber 10, which may be a cold wall-type CVD reactor. As is
conventional, the CVD process may be carried out at pressures of
from atmospheric pressure down to about 10.sup.-3 torr, and
preferably from about 1.0-0.1 torr. A vacuum may be created in
chamber 10 using turbo pump 12 and backing pump 14.
[0048] One or more substrates 16 (e.g., semiconductor substrates or
substrate assemblies) are positioned in chamber 10. A constant
nominal temperature is established for the substrate, preferably at
a temperature of about 0-600.degree. C., and more preferably at a
temperature of about 50-300.degree. C. Substrate 16 may be heated,
for example, by an electrical resistance heater 18 on which
substrate 16 is mounted. Other known methods of heating the
substrate may also be utilized.
[0049] In this process, the precursor 40, which contains one or
more complexes of Formula I, is stored in liquid form in vessel 42.
A source 44 of a suitable inert gas is pumped into vessel 42 and
bubbled through the liquid, picking up the precursor and carrying
it into chamber 10 through line 45 and gas distributor 46.
Additional inert carrier gas may be supplied from source 48 as
needed to provide the desired concentration of precursor and
regulate the uniformity of the deposition across the surface of
substrate 16. As shown, a series of valves 50-54 are opened and
closed as required.
[0050] Generally, the precursor is pumped into the CVD chamber 10
at a flow rate of about 1-1000 sccm. The semiconductor substrate is
exposed to the precursor at a pressure of about 0.001-100 torr for
a time of about 0.01-100 minutes. In chamber 10, the precursor will
form an adsorbed layer on the surface of the refractory metal
nitride 36. As the deposition rate is temperature dependent,
increasing the temperature of the substrate will increase the rate
of deposition. Typical deposition rates are about 1000-10,000
.ANG./minute. The carrier gas containing the precursor is
terminated by closing valve 53.
[0051] Various combinations of carrier gases and/or reaction gases
can be used in certain methods of the present invention. They can
be introduced into the chemical vapor deposition chamber in a
variety of manners, such as directly into the vaporization chamber,
in combination with the precursor, in combination (or in place of)
the carrier gas.
[0052] The following examples are offered to further illustrate the
various specific and preferred embodiments and techniques. It
should be understood, however, that many variations and
modifications may be made while remaining within the scope of the
present invention.
EXAMPLES
Example 1
Preparation of AlH.sub.2(CH.sub.2CH.sub.2CH.sub.2NMe.sub.2)
[0053] AlCl.sub.3 (2.0 g, 15 mmol) is added to a dry flask under an
inert atmosphere (e.g., argon). To this is added 30 mL of hexanes,
and the resulting slurry is cooled to -40.degree. C. A solution of
ClMgCH.sub.2CH.sub.2CH.sub.2NMe.sub.2 (30 mL of 0.5 M in
tetrahydrofuran) is added to the AlCl.sub.3 over 10 minutes. The
resulting mixture is stirred for 18 hours. The solvent is then
removed in vacuo, resulting in a white solid, which is dried in
vacuo and then transferred into a sublimator. A white sublimate of
AlCl.sub.2(CH.sub.2CH.sub.2CH.sub.2NMe.s- ub.2) is obtained at
100.degree. C. and a pressure of 0.5 torr. This product (2.0 g,
10.9 mmol) is dissolved in 30 mL of tetraethyleneglycol
dimethylether (i.e., tetraglyme) and added to a suspension of
LiAlH.sub.4 (0.82 g, 21.8 mmol) in 20 mL of tetraglyme. After
stirring for several hours, the product
AlH.sub.2(CH.sub.2CH.sub.2CH.sub.2NMe.sub.2) is removed from the
solvent by vacuum transfer into a liquid nitrogen-cooled receiver.
The resulting colorless product is used for deposition of
Al-containing films.
Example 2
Preparation of
In(CH.sub.3).sub.2(CH.sub.2CH.sub.2CH.sub.2NMe.sub.2)
[0054] This compound is prepared as described in Hostalek et al.,
Thin Solid Films, 174, 1 (1989).
Example 3
Preparation of GaH(CH.sub.3)(CH.sub.2CH.sub.2CH.sub.2NMe.sub.2)
[0055] GaCl.sub.3 (2.0 g, 11.4 mmol) is added to a dry flask under
an inert atmosphere (e.g., argon) and suspended in 25 mL of
tetrahydrofuran. To this suspension is added 22.8 mL (11.4 mmol) of
a 0.5 M solution of ClMgCH.sub.2CH.sub.2CH.sub.2NMe.sub.2 in
tetrahydrofuran. The mixture is stirred for 18 hours. The resulting
solution is cooled to -60.degree. C. and then 3.8 mL (11.4 mmol) of
a 3.0 M solution of MeMgBr in diethyl ether is slowly added. The
mixture is allowed to warm to room temperature, and after 2 hours
the solvent is removed in vacuo. The intermediate,
GaCl(CH.sub.3)(CH.sub.2CH.sub.2CH.sub.2NMe.sub.2), is then taken up
in 30 mL of tetraglyme and added dropwise to a suspension of
LiAlH.sub.4 (0.43 g, 11.4 mmol) in 20 mL of tetraglyme. After
several hours, the product
GaH(CH.sub.3)(CH.sub.2CH.sub.2CH.sub.2NMe.sub.2) is removed from
the solvent by vacuum transfer into a liquid nitrogen-cooled
receiver. The resulting colorless product is used for deposition of
Ga-containing films.
Example 4
Preparation of Aluminum Thin Films
[0056] A patterned semiconductor wafer is loaded into a CVD
chamber, and the wafer heated to approximately 250.degree. C. The
precursor, AlH.sub.2(CH.sub.2CH.sub.2CH.sub.2NMe.sub.2), is loaded
into a conventional stainless steel bubbler inside a glove box, and
the bubbler transferred to the CVD system. A helium carrier gas
flow of 50 sccm is established through the bubbler, and a chamber
pressure of 0.25 torr is established. The deposition is carried out
until a desired thickness of aluminum is obtained on the wafer.
[0057] The foregoing detailed description and examples have been
given for clarity of understanding only. No unnecessary limitations
are to be understood therefrom. The invention is not limited to the
exact details shown and described, for variations obvious to one
skilled in the art will be included within the invention defined by
the claims. The complete disclosures of all patents, patent
documents, and publications listed herein are incorporated by
reference, as if each were individually incorporated by
reference.
* * * * *