U.S. patent application number 11/169082 was filed with the patent office on 2008-09-04 for unsymmetrical ligand sources, reduced symmetry metal-containing compounds, and systems and methods including same.
This patent application is currently assigned to MICRON TECHNOLOGY, INC.. Invention is credited to Dan Millward, Timothy A. Quick, Stefan Uhlenbrock.
Application Number | 20080214001 11/169082 |
Document ID | / |
Family ID | 37450910 |
Filed Date | 2008-09-04 |
United States Patent
Application |
20080214001 |
Kind Code |
A9 |
Millward; Dan ; et
al. |
September 4, 2008 |
Unsymmetrical ligand sources, reduced symmetry metal-containing
compounds, and systems and methods including same
Abstract
The present invention provides metal-containing compounds that
include at least one .beta.-diketiminate ligand, and methods of
making and using the same. In some embodiments, the
metal-containing compounds are homoleptic complexes that include
unsymmetrical .beta.-diketiminate ligands. In other embodiments,
the metal-containing compounds are heteroleptic complexes including
at least one .beta.-diketiminate ligand. The compounds can be used
to deposit metal-containing layers using vapor deposition methods.
Vapor deposition systems including the compounds are also provided.
Sources for .beta.-diketiminate ligands are also provided.
Inventors: |
Millward; Dan; (Boise,
ID) ; Uhlenbrock; Stefan; (Boise, ID) ; Quick;
Timothy A.; (Boise, ID) |
Correspondence
Address: |
MUETING, RAASCH & GEBHARDT, P.A.
P.O. BOX 581336
MINNEAPOLIS
MN
55458-1336
US
|
Assignee: |
MICRON TECHNOLOGY, INC.
Boise
ID
|
Prior
Publication: |
|
Document Identifier |
Publication Date |
|
US 20060292873 A1 |
December 28, 2006 |
|
|
Family ID: |
37450910 |
Appl. No.: |
11/169082 |
Filed: |
June 28, 2005 |
Current U.S.
Class: |
438/681;
257/E21.17; 257/E21.271; 438/785 |
Current CPC
Class: |
C07F 5/003 20130101;
C23C 16/40 20130101; C23C 16/18 20130101; H01L 21/02197 20130101;
H01L 21/02175 20130101; H01L 21/0228 20130101; H01L 21/28556
20130101; H01L 21/3141 20130101; H01L 21/316 20130101; C07C 251/12
20130101 |
Class at
Publication: |
438/681;
438/785 |
International
Class: |
H01L 21/44 20060101
H01L021/44; H01L 21/31 20060101 H01L021/31 |
Claims
1. A method of forming a metal-containing layer on a substrate, the
method comprising: providing a substrate; providing a vapor
comprising at least one compound of the formula (Formula I):
##STR24## wherein: M is selected from the group consisting of a
Group 2 metal, a Group 3 metal, a Lanthanide, and combinations
thereof; each L is independently an anionic ligand; each Y is
independently a neutral ligand; n represents the valence state of
the metal; z is from 0 to 10; x is from 1 to n; and each R.sup.1,
R.sup.2, R.sup.3, R.sup.4, and R.sup.5 is independently hydrogen or
an organic group; with the proviso that one or more of the
following apply: R.sup.1 is different than R.sup.5, or R.sup.2 is
different than R.sup.4; and contacting the vapor comprising the at
least one compound of Formula I with the substrate to form a
metal-containing layer on at least one surface of the substrate
using a vapor deposition process.
2. The method of claim 1 wherein each R.sup.1, R.sup.2, R.sup.3,
R.sup.4, and R.sup.5 is independently hydrogen or an organic group
having 1 to 10 carbon atoms.
3. The method of claim 2 wherein R.sup.1=isopropyl; and
R.sup.5=tert-butyl.
4. The method of claim 2 wherein R.sup.2.dbd.R.sup.4=methyl; and
R.sup.3.dbd.H.
5. The method of claim 4 wherein R.sup.1=isopropyl; and
R.sup.5=tert-butyl.
6. The method of claim 1 wherein at least one L is selected from
the group consisting of a halide, an alkoxide group, an amide
group, a mercaptide group, cyanide, an alkyl group, an amidinate
group, a guanidinate group, an isoureate group, a .beta.-diketonate
group, a .beta.-iminoketonate group, a .beta.-diketiminate group,
and combinations thereof.
7. The method of claim 6 wherein the at least one L is a
.beta.-diketiminate group having a structure that is the same as
that of the .beta.-diketiminate ligand shown in Formula I.
8. The method of claim 6 wherein the at least one L is a
.beta.-diketiminate group having a structure that is different than
that of the .beta.-diketiminate ligand shown in Formula I.
9. The method of claim 8 wherein the at least one L is a symmetric
.beta.-diketiminate group.
10. The method of claim 8 wherein the at least one L is an
unsymmetric .beta.-diketiminate group.
11. The method of claim 1 wherein at least one Y is selected from
the group consisting of a carbonyl, a nitrosyl, ammonia, an amine,
nitrogen, a phosphine, an alcohol, water, tetrahydrofuran, and
combinations thereof.
12. A method of manufacturing a semiconductor structure, the method
comprising: providing a semiconductor substrate or substrate
assembly; providing a vapor comprising at least one compound of the
formula (Formula I): ##STR25## wherein: M is selected from the
group consisting of a Group 2 metal, a Group 3 metal, a Lanthanide,
and combinations thereof; each L is independently an anionic
ligand; each Y is independently a neutral ligand; n represents the
valence state of the metal; z is from 0 to 10; x is from 1 to n;
and each R.sup.1, R.sup.2, R.sup.3, R.sup.4, and R.sup.5 is
independently hydrogen or an organic group; with the proviso that
one or more of the following apply: R.sup.1 is different than
R.sup.5, or R.sup.2 is different than R.sup.4; and directing the
vapor comprising the at least one compound of Formula I to the
semiconductor substrate or substrate assembly to form a
metal-containing layer on at least one surface of the semiconductor
substrate or substrate assembly using a vapor deposition
process.
13. The method of claim 12 further comprising providing a vapor
comprising at least one metal-containing compound different than
Formula I, and directing the vapor comprising the at least one
metal-containing compound different than Formula I to the
semiconductor substrate or substrate assembly.
14. The method of claim 13 wherein the metal of the at least one
metal-containing compound different than Formula I is selected from
the group consisting of Ti, Ta, Bi, Hf, Zr, Pb, Nb, Mg, Al, and
combinations thereof.
15. The method of claim 12 further comprising providing at least
one reaction gas.
16. The method of claim 12 wherein the vapor deposition process is
a chemical vapor deposition process.
17. The method of claim 12 wherein the vapor deposition process is
an atomic layer deposition process comprising a plurality of
deposition cycles.
18. A method of forming a metal-containing layer on a substrate,
the method comprising: providing a substrate; providing a vapor
comprising at least one compound of the formula (Formula II):
##STR26## wherein: M is selected from the group consisting of a
Group 2 metal, a Group 3 metal, a.Lanthanide, and combinations
thereof; each L is independently an anionic ligand; each Y is
independently a neutral ligand; n represents the valence state of
the metal; z is from 0 to 10; each R.sup.1, R.sup.2, R.sup.3,
R.sup.4, R.sup.5, R.sup.6, R.sup.7, R.sup.8, R.sup.9, and R.sup.10
is independently hydrogen or an organic group; R.sup.1.dbd.R.sup.5,
R.sup.2.dbd.R.sup.4, R.sup.6.dbd.R.sup.10, and R.sup.7.dbd.R.sup.9;
and the two .beta.-diketiminate ligands shown in Formula II have
different structures; and contacting the vapor comprising the at
least one compound of Formula II with the substrate to form a
metal-containing layer on at least one surface of the substrate
using a vapor deposition process.
19. The method of claim 18 wherein each R.sup.1, R.sup.2, R.sup.3,
R.sup.4, R.sup.5, R.sup.6, R.sup.7, R.sup.8, R.sup.9, and R.sup.10
is independently hydrogen or an organic group having 1 to 10 carbon
atoms.
20. The method of claim 19 wherein R.sup.1.dbd.R.sup.5=tert-butyl;
and R.sup.6.dbd.R.sup.10=isopropyl.
21. The method of claim 19 wherein
R.sup.2.dbd.R.sup.4.dbd.R.sup.7.dbd.R.sup.9=methyl; and
R.sup.3.dbd.R.sup.8.dbd.H.
22. The method of claim 21 wherein R.sup.1.dbd.R.sup.5=tert-butyl;
and R.sup.6.dbd.R.sup.10=isopropyl.
23. A method of manufacturing a semiconductor structure, the method
comprising: providing a semiconductor substrate or substrate
assembly; providing a vapor comprising at least one compound of the
formula (Formula II): ##STR27## wherein: M is selected from the
group consisting of a Group 2 metal, a Group 3 metal, a Lanthanide,
and combinations thereof; each L is independently an anionic
ligand; each Y is independently a neutral ligand; n represents the
valence state of the metal; z is from 0to 10; each R.sup.1,
R.sup.2, R.sup.3, R.sup.4, R.sup.5, R.sup.6, R.sup.7, R.sup.8,
R.sup.9, and R.sup.10 is independently hydrogen or an organic
group; R.sup.1.dbd.R.sup.5, R.sup.2.dbd.R.sup.4,
R.sup.6.dbd.R.sup.10, and R.sup.7.dbd.R.sup.9; and the two
.beta.-diketiminate ligands shown in Formula II have different
structures; and directing the vapor comprising the at least one
compound of Formula II to the semiconductor substrate or substrate
assembly to form a metal-containing layer on at least one surface
of the semiconductor substrate or substrate assembly using a vapor
deposition process.
24. The method of claim 23 further comprising providing a vapor
comprising at least one metal-containing compound different than
Formula II, and directing the vapor comprising the at least one
metal-containing compound different than Formula II to the
semiconductor substrate or substrate assembly.
25. The method of claim 24 wherein the metal of the at least one
metal-containing compound different than Formula II is selected
from the group consisting of Ti, Ta, Bi, Hf, Zr, Pb, Nb, Mg, Al,
and combinations thereof.
26. The method of claim 23 further comprising providing at least
one reaction gas.
27. The method of claim 23 wherein the vapor deposition process is
a chemical vapor deposition process.
28. The method of claim 23 wherein the vapor deposition process is
an atomic layer deposition process comprising a plurality of
deposition cycles.
29. A compound of the formula (Formula I): ##STR28## wherein: M is
selected from the group consisting of a Group 2 metal, a Group 3
metal, a Lanthanide, and combinations thereof; each L is
independently an anionic ligand; each Y is independently a neutral
ligand; n represents the valence state of the metal; z is from 0 to
10; x is from 1 to n; and each R.sup.1, R.sup.2, R.sup.3, R.sup.4,
and R.sup.5 is independently hydrogen or an organic group; with the
proviso that one or more of the following apply: R.sup.1 is
different than R.sup.5, or R.sup.2 is different than R.sup.4.
30. The compound of claim 29 wherein each R.sup.1, R.sup.2,
R.sup.3, R.sup.4, and R.sup.5 is independently hydrogen or an
organic group having 1 to 10 carbon atoms.
31. The compound of claim 30 wherein R.sup.1=isopropyl; and
R.sup.5=tert-butyl.
32. The compound of claim 30 wherein R.sup.2.dbd.R.sup.4=methyl;
and R.sup.3.dbd.H.
33. The compound of claim 32 wherein R.sup.1=isopropyl; and
R.sup.5=tert-butyl.
34. The compound of claim 29 wherein M is selected from the group
consisting of Ca, Sr, Ba, and combinations thereof.
35. The compound of claim 29 wherein at least one L is selected
from the group consisting of a halide, an alkoxide group, an amide
group, a mercaptide group, cyanide, an alkyl group, an amidinate
group, a guanidinate group, an isoureate group, a .beta.-diketonate
group, a .beta.-iminoketonate group, a .beta.-diketiminate group,
and combinations thereof.
36. The compound of claim 35 wherein the at least one L is a
.beta.-diketiminate group having a structure that is the same as
that of the .beta.-diketiminate ligand shown in Formula 1.
37. The compound of claim 35 wherein the at least one L is a
.beta.-diketiminate group having a structure that is different than
that of the .beta.-diketiminate ligand shown in Formula I.
38. The compound of claim 37 wherein the at least one L is a
symmetric .beta.-diketiminate group.
39. The compound of claim 37 wherein the at least one L is an
unsymmetric .beta.-diketiminate group.
40. The compound of claim 29 wherein at least one Y is selected
from the group consisting of a carbonyl, a nitrosyl, ammonia, an
amine, nitrogen, a phosphine, an alcohol, water, tetrahydrofuran,
and combinations thereof.
41. A method of making a metal-containing compound, the method
comprising combining components comprising: a ligand source of the
formula (Formula III): ##STR29## or a tautomer thereof; optionally
a source for an anionic ligand L; optionally a source for a neutral
ligand Y; and a metal (M) source; wherein each R.sup.1, R.sup.2,
R.sup.3, R.sup.4, and R.sup.5 is independently hydrogen or an
organic group, with the proviso that one or more of the following
apply: R.sup.1 is different than R.sup.5, or R.sup.2 is different
than R.sup.4; and wherein the metal (M) source is selected from the
group consisting of a Group 2 metal source, a Group 3 metal source,
a Lanthanide metal source, and combinations thereof, under
conditions sufficient to provide a metal-containing compound of the
formula (Formula I): ##STR30## wherein M, L, Y, R.sup.1, R.sup.2,
R.sup.3, R.sup.4, and R.sup.5 are as defined above, n represents
the valence state of the metal, z is from 0 to 10, and x is from 1
to n.
42. The method of claim 41 wherein the metal (M) source comprises a
M(II) bis(hexamethyldisilazane), a M(II)
bis(hexamethyldisilazane)bis(tetrahydrofuran), or combinations
thereof.
43. The method of claim 41 wherein M is selected from the group
consisting of Ca, Sr, Ba, and combinations thereof.
44. A method of making a metal-containing compound, the method
comprising combining components comprising: a compound of the
formula (Formula I): ##STR31## a compound of the formula (Formula
VI): ##STR32## wherein: each M is selected from the group
consisting of a Group 2 metal, a Group 3 metal, a Lanthanide, and
combinations thereof; each L is independently an anionic ligand;
each Y is independently a neutral ligand; each n represents the
valence state of the metal; each z is from 0 to 10; each x is from
1 to n; each R.sup.1, R.sup.2, R.sup.3, R.sup.4, R.sup.5, R.sup.6,
R.sup.7, R.sup.8, R.sup.9, and R.sup.10 is independently hydrogen
or an organic group; and the .beta.-diketiminate ligands shown in
Formula I and Formula VI have different structures; with the
proviso that one or more of the following apply: R.sup.1 is
different than R.sup.5, R.sup.2 is different than R.sup.4, R.sup.6
is different than R.sup.10, or R.sup.7 is different than R.sup.9;
under conditions sufficient to provide a metal-containing compound
of the formula (Formula II): ##STR33## wherein M, Y, L, R.sup.1,
R.sup.2, R.sup.3, R.sup.4, R.sup.5, R.sup.6, R.sup.7, R.sup.8,
R.sup.9, R.sup.10, n, and z are as defined above.
45. A precursor composition for a vapor deposition process, the
composition comprising at least one compound of the formula
(Formula I): ##STR34## wherein: M is selected from the group
consisting of a Group 2 metal, a Group 3 metal, a Lanthanide, and
combinations thereof; each L is independently an anionic ligand;
each Y is independently a neutral ligand; n represents the valence
state of the metal; z is from 0 to 10; x is from 1 to n; and each
R.sup.1, R.sup.2, R.sup.3, R.sup.4, and R.sup.5 is independently
hydrogen or an organic group; with the proviso that one or more of
the following apply: R.sup.1 is different than R.sup.5, or R.sup.2
is different than R.sup.4
46. A compound of the formula (Formula II): ##STR35## wherein: M is
selected from the group consisting of a Group 2 metal, a Group 3
metal, a Lanthanide, and combinations thereof; each L is
independently an anionic ligand; each Y is independently a neutral
ligand; n represents the valence state of the metal; z is from 0 to
10; each R.sup.1, R.sup.2, R.sup.3, R.sup.4, R.sup.5, R.sup.6,
R.sup.7, R.sup.8, R.sup.9, and R.sup.10 is independently hydrogen
or an organic group; R.sup.1.dbd.R.sup.5, R.sup.2.dbd.R.sup.4,
R.sup.6.dbd.R.sup.10, and R.sup.7.dbd.R.sup.9; and the two
.beta.-diketiminate ligands shown in Formula II have different
structures.
47. The compound of claim 46 wherein each R.sup.1, R.sup.2,
R.sup.3, R.sup.4, R.sup.5, R.sup.6, R.sup.7, R.sup.8, R.sup.9, and
R.sup.10 is independently hydrogen or an organic group having 1 to
10 carbon atoms.
48. The compound of claim 47 wherein
R.sup.1.dbd.R.sup.5=tert-butyl; and R.sup.6.dbd.R.sup.10
=isopropyl.
49. The compound of claim 47 wherein
R.sup.2.dbd.R.sup.4.dbd.R.sup.7.dbd.R.sup.9=methyl; and
R.sup.3.dbd.R.sup.8.dbd.H.
50. The compound of claim 49 wherein
R.sup.1.dbd.R.sup.5=tert-butyl; and
R.sup.6.dbd.R.sup.10=isopropyl.
51. The compound of claim 46 wherein M is selected from the group
consisting of Ca, Sr, Ba, and combinations thereof.
52. A method of making a metal-containing compound, the method
comprising combining components comprising: a ligand source of the
formula (Formula III): ##STR36## or a tautomer thereof; a ligand
source of the formula (Formula IV): ##STR37## or a tautomer
thereof; optionally a source for an anionic ligand L; optionally a
source for a neutral ligand Y; and a metal (M) source; wherein each
R.sup.1, R.sup.2, R.sup.3, R.sup.4, R.sup.5, R.sup.6, R.sup.7,
R.sup.8, R.sup.9, and R.sup.10 is independently hydrogen or an
organic group; R.sup.1.dbd.R.sup.5, R.sup.2.dbd.R.sup.4,
R.sup.6.dbd.R.sup.10, and R.sup.7.dbd.R.sup.9; and the ligand
sources shown in Formula III and Formula IV have different
structures; and wherein the metal (M) source is selected from the
group consisting of a Group 2 metal source, a Group 3 metal source,
a Lanthanide metal source, and combinations thereof, under
conditions sufficient to provide a metal-containing compound of the
formula (Formula II): ##STR38## wherein M, Y, L, R.sup.1, R.sup.2,
R.sup.3, R.sup.4, R.sup.5, R.sup.6, R.sup.7, R.sup.8, R.sup.9, and
R.sup.10 are as defined above, n represents the valence state of
the metal, and z is from 0 to 10.
53. A method of making a metal-containing compound, the method
comprising combining components comprising: a compound of the
formula (Formula I): ##STR39## a compound of the formula (Formula
VI): ##STR40## wherein: each M is selected from the group
consisting of a Group 2 metal, a Group 3 metal, a Lanthanide, and
combinations thereof; each L is independently an anionic ligand;
each Y is independently a neutral ligand; each n represents the
valence state of the metal; each z is from 0 to 10; each R.sup.1,
R.sup.2, R.sup.3, R.sup.4, R.sup.5, R.sup.6, R.sup.7, R.sup.8,
R.sup.9, and R.sup.10 is independently hydrogen or an organic
group; R.sup.1.dbd.R.sup.5, R.sup.2.dbd.R.sup.4,
R.sup.6.dbd.R.sup.10, and R.sup.7.dbd.R.sup.9; and the
.beta.-diketiminate ligands shown in Formula I and Formula VI have
different structures; under conditions sufficient to provide a
metal-containing compound of the formula (Formula II): ##STR41##
wherein M, Y, L, R.sup.1, R.sup.2, R.sup.3, R.sup.4, R.sup.5,
R.sup.6, R.sup.7, R.sup.8, R.sup.9, R.sup.10, n, and z are as
defined above, and the two .beta.-diketiminate ligands shown in
Formula II have different structures.
54. A precursor composition for a vapor deposition process, the
composition comprising at least one compound of the formula
(Formula II): ##STR42## wherein: M is selected from the group
consisting of a Group 2 metal, a Group 3 metal, a Lanthanide, and
combinations thereof; each L is independently an anionic ligand;
each Y is independently a neutral ligand; n represents the valence
state of the metal; z is from 0 to 10; each R.sup.1, R.sup.2,
R.sup.3, R.sup.4, R.sup.5, R.sup.6, R.sup.7, R.sup.8, R.sup.9, and
R.sup.10 is independently hydrogen or an organic group;
R.sup.1.dbd.R.sup.5, R.sup.2.dbd.R.sup.4, R.sup.6.dbd.R.sup.10 and
R.sup.7.dbd.R.sup.9; and the two .beta.-diketiminate ligands shown
in Formula II have different structures.
55. A ligand source of the Formula (III): ##STR43## or a tautomer
thereof, wherein each R.sup.1, R.sup.2, R.sup.3, R.sup.4, and
R.sup.5 is independently hydrogen or an alkyl moiety having 1 to 10
carbon atoms, with the proviso that one of more of the following
apply: R.sup.1 is different than R.sup.5, or R.sup.2 is different
than R.sup.4.
56. The ligand source of claim 55 wherein R.sup.1=tert-butyl and
R.sup.5=isopropyl.
57. The ligand source of claim 55 wherein
R.sup.2.dbd.R.sup.4=methyl, and R.sup.3.dbd.H.
58. The ligand source of claim 55 wherein R.sup.1=tert-butyl and
R.sup.5=isopropyl.
59. A method of making a .beta.-diketiminate ligand source, the
method comprising combining components comprising: an amine of the
formula R.sup.1NH.sub.2; a compound of the formula (Formula V):
##STR44## or a tautomer thereof; and an alkylating agent, under
conditions sufficient to provide a ligand source of the formula
(Formula III): ##STR45## or a tautomer thereof, wherein each
R.sup.1, R.sup.2, R.sup.3, R.sup.4, and R.sup.5 is independently
hydrogen or an alkyl moiety having 1 to 10 carbon atoms, with the
proviso that one of more of the following apply: R.sup.1 is
different than R.sup.5, or R.sup.2 is different than R.sup.4.
60. A vapor deposition system comprising: a deposition chamber
having a substrate positioned therein; and at least one vessel
comprising at least one compound of the formula (Formula I):
##STR46## wherein: M is selected from the group consisting of a
Group 2 metal, a Group 3 metal, a Lanthanide, and combinations
thereof; each L is independently an anionic ligand; each Y is
independently a neutral ligand; n represents the valence state of
the metal; z is from 0 to 10; x is from 1 to n; and each R.sup.1,
R.sup.2, R.sup.3, R.sup.4, and R.sup.5 is independently hydrogen or
an organic group; with the proviso that one or more of the
following apply: R.sup.1 is different than R.sup.5, or R.sup.2 is
different than R.sup.4.
61. A vapor deposition system comprising: a deposition chamber
having a substrate positioned therein; and at least one vessel
comprising at least one compound of the formula (Formula II):
##STR47## wherein: M is selected from the group consisting of a
Group 2 metal, a Group 3 metal, a Lanthanide, and combinations
thereof; each L is independently an anionic ligand; each Y is
independently a neutral ligand; n represents the valence state of
the metal; z is from 0 to 10; each R.sup.1, R.sup.2, R.sup.3,
R.sup.4, R.sup.5, R.sup.6, R.sup.7, R.sup.8, R.sup.9, and R.sup.10
is independently hydrogen or an organic group; R.sup.1.dbd.R.sup.5,
R.sup.2.dbd.R.sup.4, R.sup.6.dbd.R.sup.10 and R.sup.7.dbd.R.sup.9;
and the two .beta.-diketiminate ligands shown in Formula II have
different structures.
Description
BACKGROUND
[0001] The scaling down of integrated circuit devices has created a
need to incorporate high dielectric constant materials into
capacitors and gates. The search for new high dielectric constant
materials and processes is becoming more important as the minimum
size for current technology is practically constrained by the use
of standard dielectric materials. Dielectric materials containing
alkaline earth metals can provide a significant advantage in
capacitance compared to conventional dielectric materials. For
example, the perovskite material SrTiO.sub.3 has a disclosed bulk
dielectric constant of up to 500.
[0002] Unfortunately, the successful integration of alkaline earth
metals into vapor deposition processes has proven to be difficult.
For example, although atomic layer deposition (ALD) of alkaline
earth metal diketonates has been disclosed, these metal diketonates
have low volatility, which typically requires that they be
dissolved in organic solvent for use in a liquid injection system.
In addition to low volatility, these metal diketonates generally
have poor reactivity, often requiring high substrate temperatures
and strong oxidizers to grow a film, which is often contaminated
with carbon. Other alkaline earth metal sources, such as those
including substituted or unsubstituted cyclopentadienyl ligands,
typically have poor volatility as well as low thermal stability,
leading to undesirable pyrolysis on the substrate surface.
[0003] New sources and methods of incorporating high dielectric
materials are being sought for new generations of integrated
circuit devices.
SUMMARY OF THE INVENTION
[0004] The present invention provides metal-containing compounds
(i.e., metal-containing complexes) that include at least one
.beta.-diketiminate ligand, and methods of making and using, and
vapor deposition systems including the same. The presently
disclosed metal-containing compounds have reduced symmetry compared
to known homoleptic complexes with symmetrical ligands. The reduced
symmetry may result from the unsymmetric ligands themselves, the
coordination of different types of ligands, or both. Reduced
symmetry may lead to desirable properties (e.g., one or more of
higher vapor pressure, lower melting point, and lower sublimation
point) for use in vapor deposition methods.
[0005] In one aspect, the present invention provides a method of
forming a metal-containing layer on a substrate (e.g., a
semiconductor substrate or substrate assembly) using a vapor
deposition process. The method can be useful in the manufacture of
semiconductor structures. The method includes: providing a
substrate; providing a vapor including at least one compound of the
formula (Formula I): ##STR1## and contacting the vapor including
the at least one compound of Formula I with the substrate (and
typically directing the vapor to the substrate) to form a
metal-containing layer on at least one surface of the substrate.
The reduced symmetry compound of the formula (Formula I) includes
at least one unsymmetrical .beta.-diketiminate ligand, wherein M is
selected from the group consisting of a Group 2 metal, a Group 3
metal, a Lanthanide, and combinations thereof; each L is
independently an anionic ligand; each Y is independently a neutral
ligand; n represents the valence state of the metal; z is from 0 to
10; x is from 1 to n; and each R.sup.1, R.sup.2, R.sup.3, R.sup.4,
and R.sup.5 is independently hydrogen or an organic group; with the
proviso that one or more of the following apply: R.sup.1 is
different than R.sup.5, or R.sup.2 is different than R.sup.4.
[0006] In another aspect, the present invention provides a method
of forming a metal-containing layer on a substrate (e.g., a
semiconductor substrate or substrate assembly) using a vapor
deposition process. The method can be useful in the manufacture of
semiconductor structures. The method includes: providing a
substrate; providing a vapor including at least one compound of the
formula (Formula II): ##STR2## and contacting the vapor including
the at least one compound of Formula TI with the substrate (and
typically directing the vapor to the substrate) to form a
metal-containing layer on at least one surface of the substrate.
The reduced symmetry compound of the formula (Formula 11) includes
two different symmetrical .beta.-diketiminate ligands, wherein: M
is selected from the group consisting of a Group 2 metal, a Group 3
metal, a Lanthanide, and combinations thereof; each L is
independently an anionic ligand; each Y is independently a neutral
ligand; n represents the valence state of the metal; z is from 0 to
10; each R.sup.1, R.sup.2, R.sup.3, R.sup.4, R.sup.5, R.sup.6,
R.sup.7, R.sup.8, R.sup.9, and R.sup.10 is independently hydrogen
or an organic group; and R.sup.1.dbd.R.sup.5, R.sup.2.dbd.R.sup.4,
R.sup.6.dbd.R.sup.10 and R.sup.7.dbd.R.sup.9.
[0007] In another aspect, the present invention provides
metal-containing compounds having at least one unsymmetrical
.beta.-diketiminate ligand, precursor compositions including such
compounds, vapor deposition systems including such compounds, and
methods of making such compounds. Such metal-containing compounds
include those of the formula (Formula I): ##STR3## wherein: M is
selected from the group consisting of a Group 2 metal, a Group 3
metal, a Lanthanide, and combinations thereof; each L is
independently an anionic ligand; each Y is independently a neutral
ligand; n represents the valence state of the metal; z is from 0 to
10; and x is from 1 to n; and each R.sup.1, R.sup.2, R.sup.3,
R.sup.4, and R.sup.5 is independently hydrogen or an organic group;
with the proviso that one or more of the following apply: R.sup.1
is different than R.sup.5, or R.sup.2 is different than R.sup.4.
The present invention also provides sources for unsymmetrical
.beta.-diketiminate ligands, and methods of making same, which are
useful for making metal-containing compounds having at least one
unsymmetrical .beta.-diketiminate ligand.
[0008] In another aspect, the present invention provides
metal-containing compounds having two different symmetrical
.beta.-diketiminate ligands, precursor compositions including such
compounds, vapor deposition systems including such compounds, and
methods of making such compounds. Such metal-containing compounds
include those of the formula (Formula II): ##STR4## wherein: M is
selected from the group consisting of a Group 2 metal, a Group 3
metal, a Lanthanide, and combinations thereof; each L is
independently an anionic ligand; each Y is independently a neutral
ligand; n represents the valence state of the metal; z is from 0 to
10; each R.sup.1, R.sup.2, R.sup.3, R.sup.4, R.sup.5, R.sup.6,
R.sup.7, R.sup.8, R.sup.9, and R.sup.10 is independently hydrogen
or an organic group; and R.sup.1.dbd.R.sup.5, R.sup.2.dbd.R.sup.4,
R.sup.6.dbd.R.sup.10, and R.sup.7.dbd.R.sup.9.
[0009] Advantageously, the reduced symmetry metal-containing
compounds of the present invention include elements of asymmetry
that may lead to desirable properties (e.g., one or more of higher
vapor pressure, lower melting point, and lower sublimation point)
for use in vapor deposition methods.
Definitions
[0010] As used herein, formulas of the type: ##STR5## are used to
represent pentadienyl-group type ligands (e.g., .beta.-diketiminate
ligands) having delocalized electron density that are coordinated
to a metal. The ligands may be coordinated to the metal through
one, two, three, four, and/or five atoms (i.e.,
.eta..sup.1-.eta..sup.2, .eta..sup.3-, .eta..sup.4-, and/or
.eta..sup.5-coordination modes).
[0011] As used herein, the term "organic group" is used for the
purpose of this invention to mean 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, suitable organic groups for
metal-containing compounds of this invention are those that do not
interfere with the formation of a metal oxide layer using vapor
deposition techniques. 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 monovalent hydrocarbon group
including, for example, methyl, ethyl, n-propyl, isopropyl,
tert-butyl, amyl, heptyl, and the like. The term "alkenyl group"
means an unsaturated, linear or branched monovalent hydrocarbon
group with one or more olefinically unsaturated groups (i.e.,
carbon-carbon double bonds), such as a vinyl group. The term
"alkynyl group" means an unsaturated, linear or branched monovalent
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.).
[0012] 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 for substitution 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, S, Si,
or F atoms, for example, in the chain as well as carbonyl groups or
other conventional substituents. 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, tert-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, tert-butyl, and the
like.
[0013] As used herein, "metal-containing" is used to refer to a
material, typically a compound or a layer, that may consist
entirely of a metal, or may include other elements in addition to a
metal. Typical metal-containing compounds include, but are not
limited to, metals, metal-ligand complexes, metal salts,
organometallic compounds, and combinations thereof. Typical
metal-containing layers include, but are not limited to, metals,
metal oxides, metal silicates, and combinations thereof.
[0014] As used herein, "a," "an," "the," and "at least one" are
used interchangeably and mean one or more than one.
[0015] As used herein, the term "comprising," which is synonymous
with "including" or "containing," is inclusive, open-ended, and
does not exclude additional unrecited elements or method steps.
[0016] The terms "deposition process" and "vapor deposition
process" as used herein refer to a process in which a
metal-containing layer is formed on one or more surfaces of a
substrate (e.g., a doped polysilicon wafer) from vaporized
precursor composition(s) including one or more metal-containing
compounds. Specifically, one or more metal-containing compounds are
vaporized and directed to and/or contacted with one or more
surfaces of a substrate (e.g., semiconductor substrate or substrate
assembly) placed in a deposition chamber. Typically, the substrate
is heated. These metal-containing compounds form (e.g., by reacting
or decomposing) a non-volatile, thin, uniform, metal-containing
layer on the surface(s) of the substrate. For the purposes of this
invention, the term "vapor deposition process" is meant to include
both chemical vapor deposition processes (including pulsed chemical
vapor deposition processes) and atomic layer deposition processes.
"Chemical vapor deposition" (CVD) as used herein refers to a vapor
deposition process wherein the desired layer is deposited on the
substrate from vaporized metal-containing compounds (and any
reaction gases used) within a deposition chamber with no effort
made to separate the reaction components. In contrast to a "simple"
CVD process that involves the substantial simultaneous use of the
precursor compositions and any reaction gases, "pulsed" CVD
alternately pulses these materials into the deposition chamber, but
does not rigorously avoid intermixing of the precursor and reaction
gas streams, as is typically done in atomic layer deposition or ALD
(discussed in greater detail below).
[0017] The term "atomic layer deposition" (ALD) as used herein
refers to a vapor deposition process in which deposition cycles,
preferably a plurality of consecutive deposition cycles, are
conducted in a process chamber (i.e., a deposition chamber).
Typically, during each cycle the precursor is chemisorbed to a
deposition surface (e.g., a substrate assembly surface or a
previously deposited underlying surface such as material from a
previous ALD cycle), forming a monolayer or sub-monolayer that does
not readily react with additional precursor (i.e., a self-limiting
reaction). Thereafter, if necessary, a reactant (e.g., another
precursor or reaction gas) may subsequently be introduced into the
process chamber for use in converting the chemisorbed precursor to
the desired material on the deposition surface. Typically, this
reactant is capable of further reaction with the precursor.
Further, purging steps may also be utilized during each cycle to
remove excess precursor from the process chamber and/or remove
excess reactant and/or reaction byproducts from the process chamber
after conversion of the chemisorbed precursor. Further, the term
"atomic layer deposition," as used herein, is also meant to include
processes designated by related terms such as, "chemical vapor
atomic layer deposition", "atomic layer epitaxy" (ALE) (see U.S.
Pat. No. 5,256,244 to Ackerman), molecular beam epitaxy (MBE), gas
source MBE, or organometallic MBE, and chemical beam epitaxy when
performed with alternating pulses of precursor composition(s),
reactive gas, and purge (e.g., inert carrier) gas.
[0018] As compared to the one cycle chemical vapor deposition (CVD)
process, the longer duration multi-cycle ALD process allows for
improved control of layer thickness and composition by
self-limiting layer growth, and minimizing detrimental gas phase
reactions by separation of the reaction components. The
self-limiting nature of ALD provides a method of depositing a film
on a wide variety of reactive surfaces, including surfaces with
irregular topographies, with better step coverage than is available
with CVD or other "line of sight" deposition methods such as
evaporation or physical vapor deposition (PVD or sputtering).
BRIEF DESCRIPTION OF THE FIGURES
[0019] FIG. 1 is a perspective view of a vapor deposition system
suitable for use in methods of the present invention.
DETAILED DESCRIPTION OF CERTAIN EMBODIMENTS
[0020] The present invention provides metal-containing compounds
(i.e., metal-containing complexes) that include at least one
.beta.-diketiminate ligand, and methods of making and using, and
vapor deposition systems including the same. In some embodiments,
the at least one .beta.-diketiminate ligand can be in the
.eta..sup.5-coordination mode. In some embodiments, the
metal-containing compounds are homoleptic complexes (i.e.,
complexes in which the metal is bound to only one type of ligand)
that include unsymmetrical .beta.-diketiminate ligands. In other
embodiments, the metal-containing compounds are heteroleptic
complexes (i.e., complexes in which the metal is bound to more than
one type of ligand) including at least one .beta.-diketiminate
ligand, which can be symmetric or unsymmetric. Thus, the presently
disclosed metal-containing compounds have reduced symmetry compared
to known homoleptic complexes with symmetrical ligands. The reduced
symmetry may result from the unsymmetric ligands themselves, the
coordination of different types of ligands, or both. Reduced
symmetry may lead to desirable properties (e.g., one or more of
higher vapor pressure, lower melting point, and lower sublimation
point) for use in vapor deposition methods.
Compounds with at Least One Unsymmetrical Ligand
[0021] In one embodiment, metal-containing compounds including at
least one unsymmetrical .beta.-diketiminate ligand, and precursor
compositions including such compounds, are disclosed. Such
compounds include a compound of the formula (Formula I): ##STR6## M
is a Group 2 metal (e.g., Ca, Sr, Ba), a Group 3 metal (e.g., Sc,
Y, La), a Lanthanide (e.g., Pr, Nd), or a combination thereof.
Preferably M is Ca, Sr, or Ba. Each L is independently an anionic
ligand; each Y is independently a neutral ligand; n represents the
valence state of the metal; z is from 0 to 10; and x is from 1 to
n.
[0022] Each R.sup.1, R.sup.2, R.sup.3, R.sup.4, and R.sup.5 is
independently hydrogen or an organic group (e.g., an alkyl group,
and preferably, for example, an alkyl moiety); with the proviso
that one or more of the following apply: R.sup.1 is different than
R.sup.5, or R.sup.2 is different than R.sup.4. In certain
embodiments, R.sup.1, R.sup.2, R.sup.3, R.sup.4, and R.sup.5 are
each independently hydrogen or an organic group having 1 to 10
carbon atoms (e.g., methyl, ethyl, propyl, isopropyl, butyl,
sec-butyl, tert-butyl). In certain embodiments, R.sup.1= isopropyl
and R.sup.5=tert-butyl. In certain embodiments, R.sup.2 and/or
R.sup.4 are methyl. In certain embodiments, R.sup.3 is H. Such an
exemplary compound of Formula I is the compound in which
R.sup.2.dbd.R.sup.4=methyl, R.sup.3.dbd.H, R.sup.1=isopropyl, and
R.sup.5=tert-butyl.
[0023] L can represent a wide variety of anionic ligands. Exemplary
anionic ligands (L) include halides, alkoxide groups, amide groups,
mercaptide groups, cyanide, alkyl groups, amidinate groups,
guanidinate groups, isoureate groups, .beta.-diketonate groups,
.beta.-iminoketonate groups, .beta.-diketiminate groups, and
combinations thereof. In certain embodiments, L is a
.beta.-diketiminate group having a structure that is the same as
that of the .beta.-diketiminate ligand shown in Formula I. In other
certain embodiments, L is a .beta.-diketiminate group (e.g.,
symmetric or unsymmetric) having a structure that is different than
that of the .beta.-diketiminate ligand shown in Formula I.
[0024] Y represents an optional neutral ligand. Exemplary neutral
ligands (Y) include carbonyl (CO), nitrosyl (NO), ammonia
(NH.sub.3), amines (NR.sub.3), nitrogen (N.sub.2), phosphines
(PR.sub.3), alcohols (ROH), water (H.sub.2O), tetrahydrofuran, and
combinations thereof, wherein each R independently represents
hydrogen or an organic group. The number of optional neutral
ligands (Y) is represented by z, which is from 0 to 10, and
preferably from 0 to 3. More preferably, Y is not present (i.e.,
z=0).
[0025] In one embodiment, a metal-containing compound including at
least one unsymmetrical .beta.-diketiminate ligand can be made, for
example, by a method that includes combining components including
an unsymmetrical .beta.-diketiminate ligand source, a metal source,
optionally a source for a neutral ligand Y, and a source for an
anionic ligand L, which can be the same or different than the
unsymmetrical .beta.-diketiminate ligand source. Typically, a
ligand source can be deprotonated to become a ligand.
[0026] An exemplary method includes combining components including:
a ligand source of the formula (Formula III): ##STR7## or a
tautomer thereof; a source for an anionic ligand L (e.g., as
described herein); optionally a source for a neutral ligand Y
(e.g., as described herein); and a metal (M) source under
conditions sufficient to form the metal-containing compound.
Preferably, the components are combined in an organic solvent
(e.g., heptane, toluene, or diethyl ether), typically under mixing
or stirring conditions, and allowed to react at a convenient
temperature (e.g., room temperature or below, refluxing or above,
or an intermediate temperature) for a length of time to form a
sufficient amount of the desired product. Preferably, the
components are combined under an inert atmosphere (e.g., argon),
typically in the substantial absence of water.
[0027] The metal (M) source can be selected from the group
consisting of a Group II metal source, a Group III metal source, a
Lanthanide metal source, and combinations thereof. Exemplary metal
sources include, for example, a M(II) bis(hexamethyldisilazane), a
M(II) bis(hexamethyldisilazane)bis(tetrahydrofuran), or
combinations thereof.
[0028] Each R.sup.1, R.sup.2, R.sup.3, R.sup.4, and R.sup.5 is
independently hydrogen or an organic group (e.g., an alkyl group,
and preferably, for example, an alkyl moiety), with the proviso
that one or more of the following apply: R.sup.1 is different than
R.sup.5, or R.sup.2 is different than R.sup.4.
[0029] The method provides a metal-containing compound of the
formula (Formula I): ##STR8## wherein M, L, Y, R.sup.1, R.sup.2,
R.sup.3, R.sup.4, and R.sup.5 are as defined above, n represents
the valence state of the metal, z is from 0 to 10, and x is from 1
to n.
[0030] Unsymmetrical .beta.-diketiminate ligand sources can be
made, for example, using condensation reactions. For example,
exemplary unsymmetrical .beta.-diketiminate ligand sources can be
made by a method including combining components including an amine
of the formula R.sup.1NH.sub.2; a compound of the formula (Formula
V): ##STR9## or a tautomer thereof; and an agent capable of
activating the carbonyl group for reaction with the amine, under
conditions sufficient to provide a ligand source of the formula
(Formula III): ##STR10## or a tautomer thereof.
[0031] Preferably, the components are combined in an organic
solvent (e.g., heptane, toluene, or diethyl ether), typically under
mixing or stirring conditions, and allowed to react at a convenient
temperature (e.g., room temperature or below, refluxing or above,
or an intermediate temperature) for a length of time to form a
sufficient amount of the desired product. Preferably, the
components are combined under an inert atmosphere (e.g., argon),
typically in the substantial absence of water.
[0032] Each R.sup.1, R.sup.2, R.sup.3, R.sup.4, and R.sup.5 is
independently hydrogen or an alkyl moiety having I to 10 carbon
atoms (e.g., methyl, ethyl, propyl, isopropyl, butyl, sec-butyl,
tert-butyl), with the proviso that one of more of the following
apply: R.sup.1 is different than R.sup.5, or R.sup.2 is different
than R.sup.4. Accordingly, the present invention also provides
ligand sources of Formula III. In certain embodiments,
R.sup.1=isopropyl and R.sup.5=tert-butyl. In certain embodiments,
R.sup.2 and/or R.sup.4 are methyl. In certain embodiments, R.sup.3
is H. Such an exemplary compound of Formula III is the compound in
which R.sup.2.dbd.R.sup.4=methyl, R.sup.3.dbd.H, R.sup.1=isopropyl,
and R.sup.5=tert-butyl.
[0033] Tautomers of compounds of Formula III and Formula V include
isomers in which a hydrogen atom is bonded to another atom.
Typically, tautomers can be in equilibrium with one another.
[0034] Specifically, the present invention contemplates tautomers
of Formula III including, for example, ##STR11##
[0035] Similarly, the present invention contemplates tautomers of
Formula V including, for example, ##STR12##
[0036] Suitable agents capable of activating a carbonyl group for
reaction with an amine are well known to those of skill in the art
and include, for example, alkylating agents. Exemplary alkylating
agents include triethyloxonium tetrafluoroborate, dimethyl sulfate,
nitrosoureas, mustard gases (e.g., 1,1-thiobis(2-chloroethane)),
and combinations thereof.
[0037] Additional metal-containing compounds including at least one
unsymmetrical .beta.-diketiminate ligand can be made, for example,
by ligand exchange reactions between a metal-containing compound
including at least one unsymmetrical .beta.-diketiminate ligand and
a metal-containing compound including at least one different
.beta.-diketiminate ligand. Such an exemplary method includes
combining components including a compound of the formula (Formula
I): ##STR13## and a compound of the formula (Formula VI): ##STR14##
under conditions sufficient to form the metal-containing compound.
Preferably, the components are combined in an organic solvent
(e.g., heptane, toluene, or diethyl ether), typically under mixing
or stirring conditions, and allowed to react at a convenient
temperature (e.g., room temperature or below, refluxing or above,
or an intermediate temperature) for a length of time to form a
sufficient amount of the desired product. Preferably, the
components are combined under an inert atmosphere (e.g., argon),
typically in the substantial absence of water.
[0038] Each M is a Group 2 metal, a Group 3 metal, a Lanthanide, or
a combination thereof; each L is independently an anionic ligand;
each Y is independently a neutral ligand; n represents the valence
state of the metal; z is from 0 to 10; and x is from 1 to n.
[0039] Each R.sup.1, R.sup.2, R.sup.3, R.sup.4, R.sup.5, R.sup.6,
R.sup.7, R.sup.8, R.sup.9, and R.sup.10 is independently hydrogen
or an organic group; and the .beta.-diketiminate ligands shown in
Formula I and Formula VI have different structures, with the
proviso that one or more of the following apply: R.sup.1 is
different than R.sup.5, R.sup.2 is different than R.sup.4, R.sup.6
is different than R.sup.10, or R.sup.7 is different than
R.sup.9.
[0040] The method can provide a metal-containing compound of the
formula (Formula II): ##STR15## wherein M, L, Y, R.sup.1, R.sup.2,
R.sup.3, R.sup.4, R.sup.5, R.sup.6, R.sup.7, R.sup.8, R.sup.9,
R.sup.10, n, and z are as defined above, and the two
.beta.-diketiminate ligands shown in Formula II have different
structures. Heteroleptic Compounds with Different Symmetrical
Ligands
[0041] In another embodiment, compounds that are heteroleptic
metal-containing compounds including different symmetrical
.beta.-diketiminate ligands, and precursor compositions including
such compounds, are disclosed. Such compounds include a compound of
the formula (Formula II): ##STR16## M is a Group 2 metal (e.g., Ca,
Sr, Ba), a Group 3 metal (e.g., Sc, Y, La), a Lanthanide (e.g., Pr,
Nd), or combinations thereof. Preferably M is Ca, Sr, or Ba. Each L
is independently an anionic ligand; each Y is independently a
neutral ligand; n represents the valence state of the metal; and z
is from 0 to 10.
[0042] Each R.sup.1, R.sup.3, R.sup.3, R.sup.4, R.sup.5, R.sup.6,
R.sup.7, R.sup.8, R.sup.9, and R.sup.10 is independently hydrogen
or an organic group (e.g., an alkyl group, and preferably, for
example, an alkyl moiety); R.sup.1.dbd.R.sup.5,
R.sup.2.dbd.R.sup.4, R.sup.6.dbd.R.sup.10, and R.sup.7.dbd.R.sup.9;
and the two .beta.-diketiminate ligands shown in Formula II have
different structures. In certain embodiment, each R.sup.1, R.sup.2,
R.sup.3, R.sup.4, R.sup.5, R.sup.6, R.sup.7, R.sup.8, R.sup.9 , and
R.sup.10 is independently hydrogen or an organic group having 1 to
10 carbon atoms (e.g., methyl, ethyl, propyl, isopropyl, butyl,
sec-butyl, tert-butyl). In certain embodiments,
R.sup.1.dbd.R.sup.5=tert-butyl, and R.sup.6.dbd.R.sup.10=isopropyl.
In certain embodiments, R.sup.2, R.sup.4, R.sup.7, and/or R.sup.9
are methyl. In certain embodiments, R.sup.3 and/or R.sup.8 are H.
Such an exemplary compound of Formula II is the compound in which
R.sup.2.dbd.R.sup.4.dbd.R.sup.7.dbd.R.sup.9=methyl,
R.sup.3.dbd.R.sup.8.dbd.H, R.sup.1.dbd.R.sup.5=tert-butyl, and
R.sup.6.dbd.R.sup.10=isopropyl.
[0043] L represents a wide variety of optional anionic ligands.
Exemplary anionic ligands (L) include halides, alkoxide groups,
amide groups, mercaptide groups, cyanide, alkyl groups, amidinate
groups, guanidinate groups, isoureate groups, .beta.-diketonate
groups, .beta.-iminoketonate groups, .beta.-diketiminate groups,
and combinations thereof. In certain embodiments, L is a
.beta.-diketiminate group having a structure that is the same as
that of one of the .beta.-diketiminate ligands shown in Formula II.
In other certain embodiments. L is a .beta.-diketiminate group
(e.g., symmetric or unsymmetric) having a structure that is
different than either of the .beta.-diketiminate ligands shown in
Formula II.
[0044] Y represents an optional neutral ligand. Exemplary neutral
ligands (Y) include carbonyl (CO), nitrosyl (NO), ammonia
(NH.sub.3), amines (NR.sub.3), nitrogen (N.sub.2), phosphines
(PR.sub.3), alcohols (ROH), water (H.sub.2O), tetrahydrofuran, and
combinations thereof, wherein each R independently represents
hydrogen or an organic group. The number of optional neutral
ligands (Y) is represented by z, which is from 0 to 10, and
preferably from 0 to 3. More preferably, Y is not present (i.e.,
z=0). 10 In one embodiment, a metal-containing compound including
different symmetrical .beta.-diketiminate ligands can be made, for
example, by a method that includes combining components including
at least two different symmetrical .beta.-diketiminate ligand
sources and a metal source. Symmetrical .beta.-diketiminate ligand
sources can be made as described, for example, in El-Kaderi et al.,
Organometallics, 23:4995-5002 (2004).
[0045] An exemplary method includes combining components including:
a ligand source of the formula (Formula III): ##STR17## or a
tautomer thereof; a ligand source of the formula (Formula IV):
##STR18## or a tautomer thereof; and optionally a source for an
anionic ligand L (e.g., as described herein); optionally a source
for a neutral ligand Y (e.g., as described herein); and a metal (M)
source under conditions sufficient to form the metal-containing
compound. Preferably, the components are combined in an organic
solvent (e.g., heptane, toluene, or diethyl ether), typically under
mixing or stirring conditions, and allowed to react at a convenient
temperature (e.g., room temperature or below, refluxing or above,
or an intermediate temperature) for a length of time to form a
sufficient amount of the desired product. Preferably, the
components are combined under an inert atmosphere (e.g., argon),
typically in the substantial absence of water.
[0046] The metal (M) source is a Group II metal source, a Group III
metal source, a Lanthanide metal source, or a combination thereof.
Exemplary metal sources include, for example, a M(II)
bis(hexamethyldisilazane), a M(II)
bis(hexamethyldisilazane)bis(tetrahydrofuran), or combinations
thereof.
[0047] Each R.sup.1, R.sup.2, R.sup.3, R.sup.4, R.sup.5, R.sup.6,
R.sup.7, R.sup.8, R.sup.9, and R.sup.10 is independently hydrogen
or an organic group (e.g., an alkyl group, and preferably, for
example, an alkyl moiety); R.sup.1.dbd.R.sup.5,
R.sup.2.dbd.R.sup.4, R.sup.6.dbd.R.sup.10, and R.sup.7.dbd.R.sup.9,
and the ligand sources shown in Formula III and Formula IV have
different structures.
[0048] The method can provide a metal-containing compound of the
formula (Formula II): ##STR19## wherein M, L, Y, R.sup.1, R.sup.2,
R.sup.3, R.sup.4, R.sup.5, R.sup.6, R.sup.7, R.sup.8, R.sup.9, and
R.sup.10 are as defined above, n represents the valence of the
metal, and z is from 0 to 10.
[0049] Specifically, the present invention contemplates tautomers
of Formula IV including, for example, ##STR20##
[0050] In another embodiment, a metal-containing compound including
different symmetrical 0-diketiminate ligands can be made, for
example, by ligand exchange reactions between metal-containing
compounds including different symmetrical .beta.-diketiminate
ligands. Such an exemplary method includes combining components
including a compound of the formula (Formula I): ##STR21## and a
compound of the formula (Formula VI): ##STR22## under conditions
sufficient to form the metal-containing compound. Preferably, the
components are combined in an organic solvent (e.g., heptane,
toluene, or diethyl ether), typically under mixing or stirring
conditions, and allowed to react at a convenient temperature (e.g.,
room temperature or below, refluxing or above, or an intermediate
temperature) for a length of time to form a sufficient amount of
the desired product. Preferably, the components are combined under
an inert atmosphere (e.g., argon), typically in the substantial
absence of water.
[0051] Each M is a Group 2 metal, a Group 3 metal, a Lanthanide, or
a combination thereof; each L is independently an anionic ligand;
each Y is independently a neutral ligand; n represents the valence
state of the metal; z is from 0 to 10; and x is from 1 to n.
[0052] Each R.sup.1, R.sup.2, R.sup.3, R.sup.4, R.sup.5, R.sup.6,
R.sup.7, R.sup.8, R.sup.9, and R.sup.10 is independently hydrogen
or an organic group; R.sup.1.dbd.R.sup.5, R.sup.2.dbd.R.sup.4,
R.sup.6.dbd.R.sup.10, and R.sup.7.dbd.R.sup.9; and the
.beta.-diketiminate ligands shown in Formula I and Formula VI have
different structures.
[0053] The method can provide a metal-containing compound of the
formula (Formula II): ##STR23## wherein M, L, Y, R.sup.1, R.sup.2,
R.sup.3, R.sup.4, R.sup.5, R.sup.6, R.sup.7, R.sup.8, R.sup.9,
R.sup.10, n, and z are as defined above. Other Metal-Containing
Compounds
[0054] Precursor compositions that include a metal-containing
compound that includes at least one .beta.-diketiminate ligand can
be useful for depositing metal-containing layers using vapor
deposition methods. In addition, such vapor deposition methods can
also include precursor compositions that include one or more
different metal-containing compounds. Such precursor compositions
can be deposited/chemisorbed, for example in an ALD process
discussed more fully below, substantially simultaneously with or
sequentially to, the precursor compositions including
metal-containing compounds with at least one .beta.-diketiminate
ligand. The metals of such different metal-containing compounds can
include, for example, Ti, Ta, Bi, Hf, Zr, Pb, Nb, Mg, Al, and
combinations thereof. Suitable different metal-containing compounds
include, for example, tetrakis titanium isopropoxide, titanium
tetrachloride, trichlorotitanium dialkylamides, tetrakis titanium
dialkylamides, tetrakis hafnium dialkylamides, trimethyl aluminum,
zirconium (IV) chloride, pentakis tantalum ethoxide, and
combinations thereof.
Vapor Deposition Methods
[0055] The metal-containing layer can be deposited, for example, on
a substrate (e.g., a semiconductor substrate or substrate
assembly). "Semiconductor substrate" or "substrate assembly" as
used herein refer to a semiconductor substrate such as a base
semiconductor layer or a semiconductor substrate having one or more
layers, structures, or regions formed thereon. A base semiconductor
layer is typically the lowest layer of silicon material on a wafer
or a silicon layer deposited on another material, such as silicon
on sapphire. When reference is made to a substrate assembly,
various process steps may have been previously used to form or
define regions, junctions, various structures or features, and
openings such as transistors, active areas, diffusions, implanted
regions, vias, contact openings, high aspect ratio openings,
capacitor plates, barriers for capacitors, etc.
[0056] "Layer," as used herein, refers to any layer that can be
formed on a substrate from one or more precursors and/or reactants
according to the deposition process described herein. The term
"layer" is meant to include layers specific to the semiconductor
industry, such as, but clearly not limited to, a barrier layer,
dielectric layer (i.e., a layer having a high dielectric constant),
and conductive layer. The term "layer" is synonymous with the term
"film" frequently used in the semiconductor industry. The term
"layer" is also meant to include layers found in technology outside
of semiconductor technology, such as coatings on glass. For
example, such layers can be formed directly on fibers, wires, etc.,
which are substrates other than semiconductor substrates. Further,
the layers can be formed directly on the lowest semiconductor
surface of the substrate, or they can be formed on any of a variety
of layers (e.g., surfaces) as in, for example, a patterned
wafer.
[0057] The layers or films formed may be in the form of
metal-containing films, such as reduced metals, metal silicates,
metal oxides, metal nitrides, etc, as well as combinations thereof.
For example, a metal oxide layer may include a single metal, the
metal oxide layer may include two or more different metals (i.e.,
it is a mixed metal oxide), or a metal oxide layer may optionally
be doped with other metals.
[0058] If the metal oxide layer includes two or more different
metals, the metal oxide layer can be in the form of alloys, solid
solutions, or nanolaminates. Preferably, these have dielectric
properties. The metal oxide layer (particularly if it is a
dielectric layer) preferably includes one or more of BaTiO.sub.3,
SrTiO.sub.3, CaTiO.sub.3, (Ba,Sr)TiO.sub.3, SrTa.sub.2O.sub.6,
SrBi.sub.2Ta.sub.2O.sub.9 (SBT), SrHfO.sub.3, SrZrO.sub.3,
BaHfO.sub.3, BaZrO.sub.3, (Pb,Ba)Nb.sub.2O.sub.6,
(Sr,Ba)Nb.sub.2O.sub.6, Pb[(Sc,Nb).sub.0.575Ti.sub.0.425]O.sub.3
(PSNT), La.sub.2O.sub.3, Y.sub.2O.sub.3, LaAlO.sub.3, YAlO.sub.3,
Pr.sub.2O.sub.3, Ba(Li,Nb).sub.1/4O.sub.3--PbTiO.sub.3, and
Ba(0.6)Sr(0.4)TiO.sub.3-MgO. Surprisingly, the metal oxide layer
formed according to the present invention is essentially free of
carbon. Preferably metal-oxide layers formed by the systems and
methods of the present invention are essentially free of carbon,
hydrogen, halides, phosphorus, sulfur, nitrogen or compounds
thereof. As used herein, "essentially free" is defined to mean that
the metal-containing layer may include a small amount of the above
impurities. For example, for metal-oxide layers, "essentially free"
means that the above impurities are present in an amount of less
than 1 atomic percent, such that they have a minor effect on the
chemical properties, mechanical properties, physical form (e.g.,
crystallinity), or electrical properties of the film.
[0059] Various metal-containing compounds can be used in various
combinations, optionally with one or more organic solvents
(particularly for CVD processes), to form a precursor composition.
Advantageously, some of the metal-containing compounds disclosed
herein can be used in ALD without adding solvents. "Precursor" and
"precursor composition" as used herein, refer to a composition
usable for forming, either alone or with other precursor
compositions (or reactants), a layer on a substrate assembly in a
deposition process. Further, one skilled in the art will recognize
that the type and amount of precursor used will depend on the
content of a layer which is ultimately to be formed using a vapor
deposition process. The preferred precursor compositions of the
present invention are preferably liquid at the vaporization
temperature and, more preferably, are preferably liquid at room
temperature.
[0060] The precursor compositions may be liquids or solids at room
temperature (preferably, they are liquids at the vaporization
temperature). Typically, they are liquids sufficiently volatile to
be employed using known vapor deposition techniques. However, as
solids they may also be sufficiently volatile that they can be
vaporized or sublimed from the solid state using known vapor
deposition techniques. If they are less volatile solids, they are
preferably sufficiently soluble in an organic solvent or have
melting points below their decomposition temperatures such that
they can be used in flash vaporization, bubbling, microdroplet
formation techniques, etc.
[0061] Herein, vaporized metal-containing compounds may be used
either alone or optionally with vaporized molecules of other
metal-containing compounds or optionally with vaporized solvent
molecules or inert gas molecules, if used. As used herein, "liquid"
refers to a solution or a neat liquid (a liquid at room temperature
or a solid at room temperature that melts at an elevated
temperature). As used herein, "solution" does not require complete
solubility of the solid but may allow for some undissolved solid,
as long as there is a sufficient amount of the solid delivered by
the organic solvent into the vapor phase for chemical vapor
deposition processing. If solvent dilution is used in deposition,
the total molar concentration of solvent vapor generated may also
be considered as a inert carrier gas.
[0062] "Inert gas" or "non-reactive gas," as used herein, is any
gas that is generally unreactive with the components it comes in
contact with. For example, inert gases are typically selected from
a group including nitrogen, argon, helium, neon, krypton, xenon,
any other non-reactive gas, and mixtures thereof. Such inert gases
are generally used in one or more purging processes described
according to the present invention, and in some embodiments may
also be used to assist in precursor vapor transport.
[0063] Solvents that are suitable for certain embodiments of the
present invention may be one or more of the following: aliphatic
hydrocarbons or unsaturated hydrocarbons (C3-C20, and preferably
C5-C10, cyclic, branched, or linear), aromatic hydrocarbons
(C5-C20, and preferably C5-C 10), halogenated hydrocarbons,
silylated hydrocarbons such as alkylsilanes, alkylsilicates,
ethers, polyethers, thioethers, esters, lactones, nitrites,
silicone oils, or compounds containing combinations of any of the
above or mixtures of one or more of the above. The compounds are
also generally compatible with each other, so that mixtures of
variable quantities of the metal-containing compounds will not
interact to significantly change their physical properties.
[0064] The precursor compositions of the present invention can,
optionally, be vaporized and deposited/chemisorbed substantially
simultaneously with, and in the presence of, one or more reaction
gases. Alternatively, the metal-containing layers may be formed by
alternately introducing the precursor composition and the reaction
gas(es) during each deposition cycle. Such reaction gases may
typically include oxygen, water vapor, ozone, nitrogen oxides,
sulfur oxides, hydrogen, hydrogen sulfide, hydrogen selenide,
hydrogen telluride, hydrogen peroxide, ammonia, organic amines,
hydrazines (e.g., hydrazine, methylhydrazine, symmetrical and
unsymmetrical dimethylhydrazines), silanes, disilanes and higher
silanes, diborane, plasma, air, borazene (nitrogen source), carbon
monoxide (reductant), alcohols, and any combination of these gases.
For example, oxygen-containing sources are typically used for the
deposition of metal-oxide layers. Preferable optional reaction
gases used in the formation of metal-oxide layers include oxidizing
gases (e.g., oxygen, ozone, and nitric oxide).
[0065] Suitable substrate materials of the present invention
include conductive materials, semiconductive materials, conductive
metal-nitrides, conductive metals, conductive metal oxides, etc.
The substrate on which the metal-containing layer is formed is
preferably a semiconductor substrate or substrate assembly. A wide
variety of semiconductor materials are contemplated, such as for
example, borophosphosilicate glass (BPSG), silicon such as, e.g.,
conductively doped polysilicon, monocrystalline silicon, etc. (for
this invention, appropriate forms of silicon are simply referred to
as "silicon"), for example in the form of a silicon wafer,
tetraethylorthosilicate (TEOS) oxide, spin on glass (i.e., a thin
layer of SiO.sub.2, optionally doped, deposited by a spin on
process), TiN, TaN, W, Ru, Al, Cu, noble metals, etc. A substrate
assembly may also contain a layer that includes platinum, iridium,
iridium oxide, rhodium, ruthenium, ruthenium oxide, strontium
ruthenate, lanthanum nickelate, titanium nitride, tantalum nitride,
tantalum-silicon-nitride, silicon dioxide, aluminum, gallium
arsenide, glass, etc., and other existing or to-be-developed
materials used in semiconductor constructions, such as dynamic
random access memory (DRAM) devices, static random access memory
(SRAM) devices, and ferroelectric memory (FERAM) devices, for
example.
[0066] For substrates including semiconductor substrates or
substrate assemblies, the layers 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.
[0067] Substrates other than semiconductor substrates or substrate
assemblies can also be used in methods of the present invention.
Any substrate that may advantageously form a metal-containing layer
thereon, such as a metal oxide layer, may be used, such substrates
including, for example, fibers, wires, etc.
[0068] A preferred deposition process for the present invention is
a vapor deposition process. Vapor deposition processes are
generally favored in the semiconductor industry due to the process
capability to quickly provide highly conformal layers even within
deep contacts and other openings.
[0069] The precursor compositions can be vaporized in the presence
of an inert carrier gas if desired. Additionally, an inert carrier
gas can be used in purging steps in an ALD process (discussed
below). The inert carrier gas is typically one or more of nitrogen,
helium, argon, etc. In the context of the present invention, an
inert carrier gas is one that does not interfere with the formation
of the metal-containing layer. Whether done in the presence of a
inert carrier gas or not, the vaporization is preferably done in
the absence of oxygen to avoid oxygen contamination of the layer
(e.g., oxidation of silicon to form silicon dioxide or oxidation of
precursor in the vapor phase prior to entry into the deposition
chamber).
[0070] Chemical vapor deposition (CVD) and atomic layer deposition
(ALD) are two vapor deposition processes often employed to form
thin, continuous, uniform, metal-containing layers onto
semiconductor substrates. Using either vapor deposition process,
typically one or more precursor compositions are vaporized in a
deposition chamber and optionally combined with one or more
reaction gases and directed to and/or contacted with the substrate
to form a metal-containing layer on the substrate. It will be
readily apparent to one skilled in the art that the vapor
deposition process may be enhanced by employing various related
techniques such as plasma assistance, photo assistance, laser
assistance, as well as other techniques.
[0071] Chemical vapor deposition (CVD) has been extensively used
for the preparation of metal-containing layers, such as dielectric
layers, in semiconductor processing because of its ability to
provide conformal and high quality dielectric layers at relatively
fast processing times. Typically, the desired precursor
compositions are vaporized and then introduced into a deposition
chamber containing a heated substrate with optional reaction gases
and/or inert carrier gases in a single deposition cycle. In a
typical CVD process, vaporized precursors are contacted with
reaction gas(es) at the substrate surface to form a layer (e.g.,
dielectric layer). The single deposition cycle is allowed to
continue until the desired thickness of the layer is achieved.
[0072] Typical CVD processes generally employ precursor
compositions in vaporization chambers that are separated from the
process chamber wherein the deposition surface or wafer is located.
For example, liquid precursor compositions are typically placed in
bubblers and heated to a temperature at which they vaporize, and
the vaporized liquid precursor composition is then transported by
an inert carrier gas passing over the bubbler or through the liquid
precursor composition. The vapors are then swept through a gas line
to the deposition chamber for depositing a layer on substrate
surface(s) therein. Many techniques have been developed to
precisely control this process. For example, the amount of
precursor composition transported to the deposition chamber can be
precisely controlled by the temperature of the reservoir containing
the precursor composition and by the flow of an inert carrier gas
bubbled through or passed over the reservoir.
[0073] A typical CVD process may be carried out in a chemical vapor
deposition reactor, such as a deposition chamber available under
the trade designation of 7000 from Genus, Inc. (Sunnyvale, Calif.),
a deposition chamber available under the trade designation of 5000
from Applied Materials, Inc. (Santa Clara, Calif.), or a deposition
chamber available under the trade designation of Prism from
Novelus, Inc. (San Jose, Calif.). However, any deposition chamber
suitable for performing CVD may be used.
[0074] Several modifications of the CVD process and chambers are
possible, for example, using atmospheric pressure chemical vapor
deposition, low pressure chemical vapor deposition (LPCVD), plasma
enhanced chemical vapor deposition (PECVD), hot wall or cold wall
reactors or any other chemical vapor deposition technique.
Furthermore, pulsed CVD can be used, which is similar to ALD
(discussed in greater detail below) but does not rigorously avoid
intermixing of precursor and reactant gas streams. Also, for pulsed
CVD, the deposition thickness is dependent on the exposure time, as
opposed to ALD, which is self-limiting (discussed in more detail
below).
[0075] Alternatively, and preferably, the vapor deposition process
employed in the methods of the present invention is a multi-cycle
atomic layer deposition (ALD) process. Such a process is
advantageous, in particular advantageous over a CVD process, in
that it provides for improved control of atomic-level thickness and
uniformity to the deposited layer (e.g., dielectric layer) by
providing a plurality of deposition cycles. The self-limiting
nature of ALD provides a method of depositing a film on a wide
variety of reactive surfaces including, for example, surfaces with
irregular topographies, with better step coverage than is available
with CVD or other "line of sight" deposition methods (e.g.,
evaporation and physical vapor deposition, i.e., PVD or
sputtering). Further, ALD processes typically expose the
metal-containing compounds to lower volatilization and reaction
temperatures, which tends to decrease degradation of the precursor
as compared to, for example, typical CVD processes. See, for
example, copending U.S. application Ser. No. ______ (entitled
"ATOMIC LAYER DEPOSITION SYSTEMS AND METHODS INCLUDING METAL
BETA-DIKETIMINATE COMPOUNDS," Attorney Docket No. 150.01470101),
filed on the same day herewith.
[0076] Generally, in an ALD process each reactant is pulsed
sequentially onto a suitable substrate, typically at deposition
temperatures of at least 25.degree. C., preferably at least
150.degree. C., and more preferably at least 200.degree. C. Typical
ALD deposition temperatures are no greater than 400.degree. C.,
preferably no greater than 350.degree. C., and even more preferably
no greater than 250.degree. C. These temperatures are generally
lower than those presently used in CVD processes, which typically
include deposition temperatures at the substrate surface of at
least 150.degree. C., preferably at least 200.degree. C., and more
preferably at least 250.degree. C. Typical CVD deposition
temperatures are no greater than 600.degree. C., preferably no
greater than 500.degree. C., and even more preferably no greater
than 400.degree. C.
[0077] Under such conditions the film growth by ALD is typically
self-limiting (i.e., when the reactive sites on a surface are used
up in an ALD process, the deposition generally stops), insuring not
only excellent conformality but also good large area uniformity
plus simple and accurate composition and thickness control. Due to
alternate dosing of the precursor compositions and/or reaction
gases, detrimental vapor-phase reactions are inherently eliminated,
in contrast to the CVD process that is carried out by continuous
co-reaction of the precursors and/or reaction gases. (See Vehkamaki
et al, "Growth of SrTiO.sub.3 and BaTiO.sub.3 Thin Films by Atomic
Layer Deposition," Electrochemical and Solid-State Letters,
2(10):504-506 (1999)).
[0078] A typical ALD process includes exposing a substrate (which
may optionally be pretreated with, for example, water and/or ozone)
to a first chemical to accomplish chemisorption of the species onto
the substrate. The term "chemisorption" as used herein refers to
the chemical adsorption of vaporized reactive metal-containing
compounds on the surface of a substrate. The adsorbed species are
typically irreversibly bound to the substrate surface as a result
of relatively strong binding forces characterized by high
adsorption energies (e.g., >30 kcal/mol), comparable in strength
to ordinary chemical bonds. The chemisorbed species typically form
a monolayer on the substrate surface. (See "The Condensed Chemical
Dictionary", 10th edition, revised by G. G. Hawley, published by
Van Nostrand Reinhold Co., New York, 225 (1981)). The technique of
ALD is based on the principle of the formation of a saturated
monolayer of reactive precursor molecules by chemisorption. In ALD
one or more appropriate precursor compositions or reaction gases
are alternately introduced (e.g., pulsed) into a deposition chamber
and chemisorbed onto the surfaces of a substrate. Each sequential
introduction of a reactive compound (e.g., one or more precursor
compositions and one or more reaction gases) is typically separated
by an inert carrier gas purge. Each precursor composition
co-reaction adds a new atomic layer to previously deposited layers
to form a cumulative solid layer. The cycle is repeated to
gradually form the desired layer thickness. It should be understood
that ALD can alternately utilize one precursor composition, which
is chemisorbed, and one reaction gas, which reacts with the
chemisorbed species.
[0079] Practically, chemisorption might not occur on all portions
of the deposition surface (e.g., previously deposited ALD
material). Nevertheless, such imperfect monolayer is still
considered a monolayer in the context of the present invention. In
many applications, merely a substantially saturated monolayer may
be suitable. A substantially saturated monolayer is one that will
still yield a deposited monolayer or less of material exhibiting
the desired quality and/or properties.
[0080] A typical ALD process includes exposing an initial substrate
to a first chemical species A (e.g., a metal-containing compound as
described herein) to accomplish chemisorption of the species onto
the substrate. Species A can react either with the substrate
surface or with Species B (described below) but not with itself.
Typically in chemisorption, one or more of the ligands of Species A
is displaced by reactive groups on the substrate surface.
Theoretically, the chemisorption forms a monolayer that is
uniformly one atom or molecule thick on the entire exposed initial
substrate, the monolayer being composed of Species A, less any
displaced ligands. In other words, a saturated monolayer is
substantially formed on the substrate surface. Practically,
chemisorption may not occur on all portions of the substrate.
Nevertheless, such a partial monolayer is still understood to be a
monolayer in the context of the present invention. In many
applications, merely a substantially saturated monolayer may be
suitable. In one aspect, a substantially saturated monolayer is one
that will still yield a deposited monolayer or less of material
exhibiting the desired quality and/or properties. In another
aspect, a substantially saturated monolayer is one that is
self-limited to further reaction with precursor.
[0081] The first species (e.g., substantially all non-chemilsorbed
molecules of Species A) as well as displaced ligands are purged
from over the substrate and a second chemical species, Species B
(e.g., a different metal-containing compound or reactant gas) is
provided to react with the monolayer of Species A. Species B
typically displaces the remaining ligands from the Species A
monolayer and thereby is chemisorbed and forms a second monolayer.
This second monolayer displays a surface which is reactive only to
Species A. Non-chemisorbed Species B, as well as displaced ligands
and other byproducts of the reaction are then purged and the steps
are repeated with exposure of the Species B monolayer to vaporized
Species A. Optionally, the second species can react with the first
species, but not chemisorb additional material thereto. That is,
the second species can cleave some portion of the chemisorbed first
species, altering such monolayer without forming another monolayer
thereon, but leaving reactive sites available for formation of
subsequent monolayers. In other ALD processes, a third species or
more may be successively chemisorbed (or reacted) and purged just
as described for the first and second species, with the
understanding that each introduced species reacts with the
monolayer produced immediately prior to its introduction.
Optionally, the second species (or third or subsequent) can include
at least one reaction gas if desired.
[0082] Thus, the use of ALD provides the ability to improve the
control of thickness, composition, and uniformity of
metal-containing layers on a substrate. For example, depositing
thin layers of metal-containing compound in a plurality of cycles
provides a more accurate control of ultimate film thickness. This
is particularly advantageous when the precursor composition is
directed to the substrate and allowed to chemisorb thereon,
preferably further including at least one reaction gas that reacts
with the chemisorbed species on the substrate, and even more
preferably wherein this cycle is repeated at least once.
[0083] Purging of excess vapor of each species following
deposition/chemisorption onto a substrate may involve a variety of
techniques including, but not limited to, contacting the substrate
and/or monolayer with an inert carrier gas and/or lowering pressure
to below the deposition pressure to reduce the concentration of a
species contacting the substrate and/or chemisorbed species.
Examples of carrier gases, as discussed above, may include N.sub.2,
Ar, He, etc. Additionally, purging may instead include contacting
the substrate and/or monolayer with any substance that allows
chemisorption by-products to desorb and reduces the concentration
of a contacting species preparatory to introducing another species.
The contacting species may be reduced to some suitable
concentration or partial pressure known to those skilled in the art
based on the specifications for the product of a particular
deposition process.
[0084] ALD is often described as a self-limiting process, in that a
finite number of sites exist on a substrate to which the first
species may form chemical bonds. The second species might only
react with the surface created from the chemisorption of the first
species and thus, may also be self-limiting. Once all of the finite
number of sites on a substrate are bonded with a first species, the
first species will not bond to other of the first species already
bonded with the substrate. However, process conditions can be
varied in ALD to promote such bonding and render ALD not
self-limiting, e.g., more like pulsed CVD. Accordingly, ALD may
also encompass a species forming other than one monolayer at a time
by stacking of a species, forming a layer more than one atom or
molecule thick.
[0085] The described method indicates the "substantial absence" of
the second precursor (i.e., second species) during chemisorption of
the first precursor since insignificant amounts of the second
precursor might be present. According to the knowledge and the
preferences of those with ordinary skill in the art, a
determination can be made as to the tolerable amount of second
precursor and process conditions selected to achieve the
substantial absence of the second precursor.
[0086] Thus, during the ALD process, numerous consecutive
deposition cycles are conducted in the deposition chamber, each
cycle depositing a very thin metal-containing layer (usually less
than one monolayer such that the growth rate on average is 0.2 to
3.0 Angstroms per cycle), until a layer of the desired thickness is
built up on the substrate of interest. The layer deposition is
accomplished by alternately introducing (i.e., by pulsing)
precursor composition(s) into the deposition chamber containing a
substrate, chemisorbing the precursor composition(s) as a monolayer
onto the substrate surfaces, purging the deposition chamber, then
introducing to the chemisorbed precursor composition(s) reaction
gases and/or other precursor composition(s) in a plurality of
deposition cycles until the desired thickness of the
metal-containing layer is achieved. Preferred thicknesses of the
metal-containing layers of the present invention are at least 1
angstrom (.ANG.), more preferably at least 5 .ANG., and more
preferably at least 10 .ANG.. Additionally, preferred film
thicknesses are typically no greater than 500 .ANG., more
preferably no greater than 400 .ANG., and more preferably no
greater than 300 .ANG..
[0087] The pulse duration of precursor composition(s) and inert
carrier gas(es) is generally of a duration sufficient to saturate
the substrate surface. Typically, the pulse duration is at least 0.
1, preferably at least 0.2 second, and more preferably at least 0.5
second. Preferred pulse durations are generally no greater than 5
seconds, and preferably no greater than 3 seconds.
[0088] In comparison to the predominantly thermally driven CVD, ALD
is predominantly chemically driven. Thus, ALD may advantageously be
conducted at much lower temperatures than CVD. During the ALD
process, the substrate temperature may be maintained at a
temperature sufficiently low to maintain intact bonds between the
chemisorbed precursor composition(s) and the underlying substrate
surface and to prevent decomposition of the precursor
composition(s). The temperature, on the other hand, must be
sufficiently high to avoid condensation of the precursor
composition(s). Typically the substrate is kept at a temperature of
at least 25.degree. C., preferably at least 1 50.degree. C., and
more preferably at least 200.degree. C. Typically the substrate is
kept at a temperature of no greater than 400.degree. C., preferably
no greater than 300.degree. C., and more preferably no greater than
250.degree. C., which, as discussed above, is generally lower than
temperatures presently used in typical CVD processes. Thus, the
first species or precursor composition is chemisorbed at this
temperature. Surface reaction of the second species or precursor
composition can occur at substantially the same temperature as
chemisorption of the first precursor or, optionally but less
preferably, at a substantially different temperature. Clearly, some
small variation in temperature, as judged by those of ordinary
skill, can occur but still be considered substantially the same
temperature by providing a reaction rate statistically the same as
would occur at the temperature of the first precursor
chemisorption. Alternatively, chemisorption and subsequent
reactions could instead occur at substantially exactly the same
temperature.
[0089] For a typical vapor deposition process, the pressure inside
the deposition chamber is at least 10.sup.-8 torr
(1.3.times.10.sup.-6 Pa), preferably at least 10.sup.-7 torr
(1.3.times.10.sup.-5 Pa), and more preferably at least 10.sup.-6
torr (1.3.times.10.sup.-4 Pa). Further, deposition pressures are
typically no greater than 10 torr (1.3.times.10.sup.3 Pa),
preferably no greater than 1 torr (1.3.times.10.sup.2 Pa), and more
preferably no greater than 10.sup.-1 torr (13 Pa). Typically, the
deposition chamber is purged with an inert carrier gas after the
vaporized precursor composition(s) have been introduced into the
chamber and/or reacted for each cycle. The inert carrier gas/gases
can also be introduced with the vaporized precursor composition(s)
during each cycle.
[0090] The reactivity of a precursor composition can significantly
influence the process parameters in ALD. Under typical CVD process
conditions, a highly reactive compound may react in the gas phase
generating particulates, depositing prematurely on undesired
surfaces, producing poor films, and/or yielding poor step coverage
or otherwise yielding non-uniform deposition. For at least such
reason, a highly reactive compound might be considered not suitable
for CVD. However, some compounds not suitable for CVD are superior
ALD precursors. For example, if the first precursor is gas phase
reactive with the second precursor, such a combination of compounds
might not be suitable for CVD, although they could be used in ALD.
In the CVD context, concern might also exist regarding sticking
coefficients and surface mobility, as known to those skilled in the
art, when using highly gas-phase reactive precursors, however,
little or no such concern would exist in the ALD context.
[0091] After layer formation on the substrate, an annealing process
may be optionally performed in situ in the deposition chamber in a
reducing, inert, plasma, or oxidizing atmosphere. Preferably, the
annealing temperature is at least 400.degree. C., more preferably
at least 600.degree. C. The annealing temperature is preferably no
greater than 1 000.degree. C., more preferably no greater than
750.degree. C., and even more preferably no greater than
700.degree. C.
[0092] The annealing operation is preferably performed for a time
period of at least 0.5 minute, more preferably for a time period of
at least I minute. Additionally, the annealing operation is
preferably performed for a time period of no greater than 60
minutes, and more preferably for a time period of no greater than
10 minutes.
[0093] One skilled in the art will recognize that such temperatures
and time periods may vary. For example, furnace anneals and rapid
thermal annealing may be used, and further, such anneals may be
performed in one or more annealing steps.
[0094] As stated above, the use of the compounds and methods of
forming films of the present invention are beneficial for a wide
variety of thin film applications in semiconductor structures,
particularly those using high dielectric materials. For example,
such applications include gate dielectrics and capacitors such as
planar cells, trench cells-(e.g., double sidewall trench
capacitors), stacked cells (e.g., crown, V-cell, delta cell,
multi-fingered, or cylindrical container stacked capacitors), as
well as field effect transistor devices.
[0095] A system that can be used to perform vapor deposition
processes (chemical vapor deposition or atomic layer deposition) of
the present invention is shown in FIG. 1. The system includes an
enclosed vapor deposition chamber 10, in which a vacuum may be
created using turbo pump 12 and backing pump 14. One or more
substrates 16(e.g., semiconductor substrates or substrate
assemblies) are positioned in chamber 10. A constant nominal
temperature is established for substrate 16, which can vary
depending on the process used. Substrate 16may 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.
[0096] In this process, precursor compositions as described herein,
60 and/or 61, are stored in vessels 62. The precursor
composition(s) are vaporized and separately fed along lines 64 and
66 to the deposition chamber 10 using, for example, an inert
carrier gas 68. A reaction gas 70 may be supplied along line 72 as
needed. Also, a purge gas 74, which is often the same as the inert
carrier gas 68, may be supplied along line 76 as needed. As shown,
a series of valves 80-85 are opened and closed as required.
[0097] The following examples are offered to further illustrate
various specific embodiments and techniques of the present
invention. It should be understood, however, that many variations
and modifications understood by those of ordinary skill in the art
may be made while remaining within the scope of the present
invention. Therefore, the scope of the invention is not intended to
be limited by the following example. Unless specified otherwise,
all percentages shown in the examples are percentages by
weight.
EXAMPLES
Example 1
Synthesis and Characterization of a Ligand Source of Formula III,
with R.sup.1=tert-butyl; R.sup.5=isopropyl;
R.sup.2.dbd.R.sup.4=methyl; and R.sup.3.dbd.H:
N-isopropyl-(4-tert-butylimino)-2-penten-2-amine
[0098] An oven-dry 1-L Schlenk flask was charged with 38.0 g of
triethyloxonium tetrafluoroborate (0.2 mol) and 75 mL diethyl ether
under argon atmosphere, and fitted with an addition funnel. 250 mL
of dichloromethane and 28.2 grams of
N-isopropyl-4-amino-3-penten-2-one (0.2 mol) were charged into the
addition funnel and this solution was added dropwise, then stirred
for 30 minutes. A solution of 21 mL tert-butyl amine (0.2 mol) and
25 mL dichloromethane was charged into the addition funnel and
added to the reaction solution, which was then stirred overnight.
Volatiles were then removed in vacuo and the resulting
yellow-orange solid was washed with two 100 mL aliquots of cold
ethyl acetate while the flask was placed in an ice-bath. After
decanting off each ethyl acetate wash, the yellow solid residue was
added to a mixture of 500 mL benzene and 500 mL water containing
8.0 g sodium hydroxide (0.2 mol). The mixture was stirred for three
minutes, then the organic phase was separated. The aqueous phase
was extracted three times, each with 100 mL diethyl ether portions.
All the organic phases were combined, dried over sodium sulfate and
concentrated on a rotary evaporator. The crude product was then
distilled through a 20 cm glass-bead packed column and short path
still head. The desired product was collected in 96% pure form at
34-42 .degree. C., 40 mTorr (5.3 Pa) pressure. The only impurity
observed by gas chromatography-mass spectrometry (GCMS) was
N-isopropyl-(4-isopropylimino)-2-penten-2-amine. The amount of
N-isopropyl-(4-isopropylimino)-2-penten-2-amine formed may be
limited by limiting the reaction time (e.g., 30 minutes after
addition of the tert-butyl amine). Allowing the reaction to stir
overnight may result in the formation of more
N-isopropyl-(4-isopropylimino)-2-penten-2-amine.
Example 2
Synthesis and Characterization of a Metal-containing Compound of
Formula I, with M=Sr (n=2); R.sup.1=tert-butyl; R.sup.5=isopropyl;
R.sup.2.dbd.R.sup.4=methyl; R.sup.3.dbd.H; x=2; and z=0: Strontium
bis(N-isopropyl-(4-tert-butylimino)-2-penten-2-aminato)
[0099] In a dry box, a 500 mL Schlenk flask was charged with 13.819
g of strontium bis(hexamethyldisilazane)bis(tetrahydrofuran) (25
mmol) and 100 mL toluene. A second Schlenk flask was charged with
9.800 g of N-isopropyl-(4-tert-butylimino)-2-penten-2-amine (50
mmol) and 100 mL toluene. The ligand solution was added to the
strontium solution, immediately producing a bright yellow reaction
solution, which was stirred for 60 hours. Volatiles were then
removed in vacuo. The crude product, a bright yellow solid, was
charged into a sublimator in dry box. The sublimator was attached
to a vacuum manifold in a fume hood, evacuated to less than 100
mTorr (13 Pa) and heated to 115.degree. C. A total of 8.204 g of
off-white crystalline solid was sublimed in three batches (68.5%
yield). Elemental Analysis calculated for
C.sub.24H.sub.46N.sub.4Sr: Sr, 18.3%. Found 18.5%. .sup.1H nuclear
magnetic resonance (NMR) (C.sub.6D.sub.6, 25.degree. C., .delta.)
4.234 (s, 2H, .beta.-CH), 3.586 (septet, J=6.0 Hz, 2H,
CH(CH.sub.3).sub.2), 1.989 (s, 6H, .alpha.-C--CH.sub.3 (isopropyl
side)), 1.907 (s, 6H, .alpha.-C--CH.sub.3 (tert-butyl side)), 1.305
(s, 18H, C(CH.sub.3).sub.3), 1.200 (d, J=6.0 Hz, 12H,
CH(CH.sub.3).sub.2); .sup.13C{.sup.1H} (C.sub.6D.sub.6, 25.degree.
C., .delta.) 16 1.19 (s, .alpha.-C--CH.sub.3 (isopropyl side)), 16
0.44 (s, .alpha.-C--CH.sub.3 (tert-butyl side)), 88.33 (s,
.beta.-CH), 54.07 (s, C(CH.sub.3).sub.3), 49.86 (s,
CH(CH.sub.3).sub.2)), 32.44 (s, C(CH.sub.3).sub.3), 26.50 (s,
CH(CH.sub.3).sub.2), 24.84 (s, .alpha.-C--CH.sub.3 (tert-butyl
side)), 22.09 (s, .alpha.-C--CH.sub.3 (isopropyl side)).
Example 3
Synthesis and Characterization of a Metal-containing Compound of
Formula II, with M=Sr (n=2); R.sup.1.dbd.R.sup.5=tert-butyl;
R.sup.6.dbd.R.sup.10=isopropyl;
R.sup.2.dbd.R.sup.4.dbd.R.sup.7.dbd.R.sup.9=methyl;
R.sup.3.dbd.R.sup.8.dbd.H; and z=0: Strontium
(N-isopropyl-(4-isopropylimino)-2-penten
-2-aminato)(N-tert-butyl-(4-tert-butylimino)-2-penten-2-aminato)
[0100] In a dry box, a 500 mL Schlenk flask was charged with 5.526
g of strontium bis(hexamethyldisilazane) (10 mmol) and 100 mL
toluene. A solution of 2.104 g
N-tert-butyl-(4-tert-butylimino)-2-penten-2-amine (10 mmol,
prepared according to literature) in 20 mL toluene was added to the
reaction flask. The reaction solution was stirred for 18 hours. A
solution of 1.823 g N-isopropyl-(4-isopropylimino)-2-penten-2-amine
(10 mmol, prepared according to literature) in 20 mL toluene was
added to the reaction flask. The reaction solution was then stirred
an additional 24 hours. Volatiles were removed in vacuo to afford a
red-brown solid, which was charged into a sublimator in a dry box
(4.70 g, 9.98 mmol). The sublimator was evacuated on a vacuum
manifold in a hood and heated. At around 80.degree. C., the pot
residue appeared to begin to melt and bump. A yellow-brown
condensate was collected on the cold finger while heating the pot
at 112.degree. C. at 115 mTorr (15.3 Pa). 2.856 g of a yellow
semi-crystalline but somewhat oily solid was recovered from the
cold-finger (59.7% yield). Analysis by proton NMR indicates that
the sublimed material consists of a 1:1:1 mixture of the title
compound with Strontium bis(N-isopropyl-4-isopropyl
imino)-2-penten-2-aminato) and Strontium
bis(N-tert-butyl-(4-tert-butylimino)-2-penten-2-aminato). The
material also contains a 0.3 relative ratio of
N-tert-butyl-(4-tert-butylimino)-2-penten-2-amine. The chemical
shifts for the title compound are as follows: .sup.1H NMR
(C.sub.6D.sub.6, 25.degree. C., .delta.) 4.218 (s, 2H, .beta.-CH),
3.586 (septet, J=6.0 Hz, 2H, CH(CH.sub.3).sub.2), 1.990 (s, 6H,
.alpha.-C--CH.sub.3 (tert-butyl)), 1.865 (s, 6H,
.alpha.-C--CH.sub.3 (isopropyl)), 1.325 (s, 18H,
C(CH.sub.3).sub.3), 1.172 (d, J=6.0 Hz, 12H, CH(CH.sub.3).sub.2);
.sup.13C{.sup.1H} (C.sub.6D.sub.6, 25.degree. C., .delta.) 160.95
(s, .alpha.-C--CH.sub.3 (isopropyl)), 160.79 (s,
.alpha.-C--CH.sub.3 (tert-butyl)), 90.05 (s, .beta.-CH
(tert-butyl)), 86.51 (s, .beta.-CH (isopropyl)), 53.99 (s,
C(CH.sub.3).sub.3), 49.93 (s, CH(CH.sub.3).sub.2)), 32.81 (s,
C(CH.sub.3).sub.3), 25.06 (s, CH(CH.sub.3).sub.2), 24.83 (s,
.alpha.-C--CH.sub.3 (tert-butyl)), 22.05 (s, .alpha.-C--CH.sub.3
(isopropyl)). Elemental Analysis calculated for
C.sub.24H.sub.46N.sub.4Sr: Sr, 18.3%. Found 17.5%.
Example 4
Alternate Synthesis of the Metal-containing Compound Prepared and
Characterized in Example 3 by Ligand Exchange Reactions Between
Metal-Containing Compounds Including Different Symmetrical
.beta.-Diketiminate Ligands
[0101] A 50 mL schlenk flask was charged with 0.50 g of
bis(N-tert-butyl-(4-tert-butylimino)-2-penten-2-aminato)strontium
(1 mmol), 0.45 g of
bis(N-isopropyl-(4-isopropylimino)-2-penten-2-aminato)strontium (1
mmol), and 20 mL toluene. The resulting solution was refluxed for
24 hours, then volatiles were removed in vacuo. A sample of the
resulting yellow solid was submitted for proton NMR analysis, and
the results indicated approximately a 1:1:1 mixture of
bis(N-tert-butyl-(4-tert-butylimino)-2-aminato)strontium:bis(N-isopropyl--
(4-isopropylimino)-2-penten-2-aminato)strontium:
(N-isopropyl-(4-isopropylimino)-2-penten-2-aminato)(N-tert-butyl-(4-tert--
butylimino)-2-penten-2-aminato)strontium, with approximately a 0.3
ratio of free
N-tert-butyl-(4-tert-butylimino)-2-penten-2-amine.
[0102] The complete disclosures of the patents, patent documents,
and publications cited herein are incorporated by reference in
their entirety as if each were individually incorporated. Various
modifications and alterations to this invention will become
apparent to those skilled in the art without departing from the
scope and spirit of this invention. It should be understood that
this invention is not intended to be unduly limited by the
illustrative embodiments and examples set forth herein and that
such examples and embodiments are presented by way of example only
with the scope of the invention intended to be limited only by the
claims set forth herein as follows.
* * * * *