U.S. patent application number 13/101328 was filed with the patent office on 2011-08-25 for organometallic compounds, processes for the preparation thereof and methods of use thereof.
Invention is credited to David Walter Peters, David M. Thompson.
Application Number | 20110206864 13/101328 |
Document ID | / |
Family ID | 40669957 |
Filed Date | 2011-08-25 |
United States Patent
Application |
20110206864 |
Kind Code |
A1 |
Peters; David Walter ; et
al. |
August 25, 2011 |
ORGANOMETALLIC COMPOUNDS, PROCESSES FOR THE PREPARATION THEREOF AND
METHODS OF USE THEREOF
Abstract
This invention relates to organometallic precursor compounds
represented by the formula (Cp(R').sub.x).sub.yM(H).sub.z-y, a
process for producing the organometallic precursor compounds, and a
method for depositing a metal and/or metal carbide layer, e.g., Ta
metal and/or TaC layer, on a substrate by the thermal or plasma
enhanced disassociation of the organometallic precursor compounds,
e.g., by CVD or ALD techniques. The metal and/or metal carbide
layer is useful as a liner or barrier layer for conducting metals
and high dielectric constant materials in integrated circuit
manufacturing.
Inventors: |
Peters; David Walter;
(Kingsland, TX) ; Thompson; David M.; (East
Amherst, NY) |
Family ID: |
40669957 |
Appl. No.: |
13/101328 |
Filed: |
May 5, 2011 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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11501075 |
Aug 9, 2006 |
7547796 |
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13101328 |
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12364197 |
Feb 2, 2009 |
7959986 |
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11501075 |
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Current U.S.
Class: |
427/576 ;
427/252; 556/43; 75/362 |
Current CPC
Class: |
C07F 17/00 20130101 |
Class at
Publication: |
427/576 ; 556/43;
75/362; 427/252 |
International
Class: |
C07F 17/00 20060101
C07F017/00; B22F 9/20 20060101 B22F009/20; H05H 1/24 20060101
H05H001/24; C23C 16/18 20060101 C23C016/18 |
Claims
1. A process for producing a compound having the formula
(Cp(R').sub.x).sub.yM(H).sub.z-y wherein M is a metal selected from
tantalum (Ta), tungsten (W), molybdenum (Mo), niobium (Nb),
vanadium (V) or chromium (Cr), each R' is the same or different and
represents a halogen atom, an acyl group having from 1 to about 12
carbon atoms, an alkoxy group having from 1 to about 12 carbon
atoms, an alkoxycarbonyl group having from 1 to about 12 carbon
atoms, an alkyl group having from 1 to about 12 carbon atoms, an
amine group having from 1 to about 12 carbon atoms or a silyl group
having from 0 to about 12 carbon atoms, Cp is a substituted or
unsubstituted cyclopentadienyl group or a substituted or
unsubstituted cyclopentadienyl-like group, x is an integer from 0
to 5, y is an integer from 1 to 5, and z is the valence of M, which
process comprises reacting a metal halide, a cyclopentadienyl salt
and a reducing agent in the presence of a first solvent and under
reaction conditions sufficient to produce an intermediate reaction
material, and reacting said intermediate reaction material with a
base material in the presence of a second solvent and under
reaction conditions sufficient to produce said compound.
2. The process of claim 1 wherein said metal halide comprises
tantalum pentachloride, niobium pentachloride, vanadium
pentachloride, tungsten hexachloride, molybdenum hexachloride or
chromium hexachloride; said cyclopentadienyl salt comprises sodium
cyclopentadiene, potassium cyclopentadiene, lithium cyclopentadiene
or magnesocene; said reducing agent comprises sodium
bis(2-methoxyethoxy)aluminum dihydride, sodium borohydride or
lithium aluminum hydride; said first solvent comprises
dimethoxyethane (DME), toluene or mixtures thereof; said
intermediate reaction material comprises
bis(cyclopentadienyl)(dihydrido)tantalum(bis-(2-methoxyethoxy)aluminate;
said base material comprises sodium hydroxide, potassium hydroxide
or ethyl acetate; and said second solvent comprises toluene, hexane
or mixtures thereof.
3. A method for producing a film, coating or powder by decomposing
an organometallic precursor, said organometallic precursor having
the formula (Cp(R').sub.x).sub.yM(H).sub.z-y wherein M is a metal
selected from tantalum (Ta), tungsten (W), molybdenum (Mo), niobium
(Nb), vanadium (V) or chromium (Cr), each R' is the same or
different and represents a halogen atom, an acyl group having from
1 to about 12 carbon atoms, an alkoxy group having from 1 to about
12 carbon atoms, an alkoxycarbonyl group having from 1 to about 12
carbon atoms, an alkyl group having from 1 to about 12 carbon
atoms, an amine group having from 1 to about 12 carbon atoms or a
silyl group having from 0 to about 12 carbon atoms, Cp is a
substituted or unsubstituted cyclopentadienyl group or a
substituted or unsubstituted cyclopentadienyl-like group, x is an
integer from 0 to 5, y is an integer from 1 to 5, and z is the
valence of M, thereby producing said film, coating or powder, a
method wherein the organometallic precursor is selected from
bis(cyclopentadienyl)(allyl)tantalum,
bis(cyclopentadienyl)(alkene)(hydrido)tantalum,
bis(cyclopentadienyl)(trihydrido)tantalum or
bis(cyclopentadienyl)(trialkyl)tantalum.
4. A method for processing a substrate in a processing chamber,
said method comprising (i) introducing an organometallic precursor
into said processing chamber, said organometallic precursor having
the formula (Cp(R').sub.x).sub.yM(H).sub.z-y wherein M is a metal
selected from tantalum (Ta), tungsten (W), molybdenum (Mo), niobium
(Nb), vanadium (V) or chromium (Cr), each R' is the same or
different and represents a halogen atom, an acyl group having from
1 to about 12 carbon atoms, an alkoxy group having from 1 to about
12 carbon atoms, an alkoxycarbonyl group having from 1 to about 12
carbon atoms, an alkyl group having from 1 to about 12 carbon
atoms, an amine group having from 1 to about 12 carbon atoms or a
silyl group having from 0 to about 12 carbon atoms, Cp is a
substituted or unsubstituted cyclopentadienyl group or a
substituted or unsubstituted cyclopentadienyl-like group, x is an
integer from 0 to 5, y is an integer from 1 to 5, and z is the
valence of M, (ii) heating said substrate to a temperature of about
100.degree. C. to about 400.degree. C., and (iii) disassociating
said organometallic precursor in the presence of a processing gas
to deposit a metal layer on said substrate.
5. The method of claim 4 wherein the organometallic precursor is
selected from bis(cyclopentadienyl)(allyl)tantalum,
bis(cyclopentadienyl)(alkene)(hydrido)tantalum,
bis(cyclopentadienyl)(trihydrido)tantalum or
bis(cyclopentadienyl)(trialkyl)tantalum.
6. The method of claim 4 wherein Ta or TaC is deposited on said
substrate.
7. The method of claim 4 wherein said metal layer is deposited on
said substrate by chemical vapor deposition, atomic layer
deposition, plasma assisted chemical vapor deposition or plasma
assisted atomic layer deposition.
8. The method of claim 4 wherein said processing gas is selected
from hydrogen, argon, helium, or combinations thereof.
9. The method of claim 4 wherein disassociating the precursor
further comprises generating a plasma at a power density between
about 0.6 Watts/cm.sup.2 and about 3.2 Watts/cm.sup.2.
10. The method of claim 4 further comprising exposing the deposited
metal layer to a plasma generated at a power density between about
0.6 Watts/cm.sup.2 and about 3.2 Watts/cm.sup.2.
11. The method of claim 4 furthering comprising depositing a second
metal layer on the metal layer, said second metal layer comprising
copper that is deposited by an electroplating technique.
12. A method for forming a metal material on a substrate from an
organometallic precursor, said method comprising vaporizing said
organometallic precursor to form a vapor, and contacting the vapor
with the substrate to form said metal material thereon, wherein the
precursor is represented by the formula
(Cp(R').sub.x).sub.yM(H).sub.z-y wherein M is a metal selected from
tantalum (Ta), tungsten (W), molybdenum (Mo), niobium (Nb),
vanadium (V) or chromium (Cr), each R' is the same or different and
represents a halogen atom, an acyl group having from 1 to about 12
carbon atoms, an alkoxy group having from 1 to about 12 carbon
atoms, an alkoxycarbonyl group having from 1 to about 12 carbon
atoms, an alkyl group having from 1 to about 12 carbon atoms, an
amine group having from 1 to about 12 carbon atoms or a silyl group
having from 0 to about 12 carbon atoms, Cp is a substituted or
unsubstituted cyclopentadienyl group or a substituted or
unsubstituted cyclopentadienyl-like group, x is an integer from 0
to 5, y is an integer from 1 to 5, and z is the valence of M, and a
method wherein the organometallic precursor is represented by the
formula ##STR00005## wherein R.sub.1, R.sub.2 and each R are the
same or different and each represent a halogen atom, an acyl group
having from 1 to about 12 carbon atoms, an alkoxy group having from
1 to about 12 carbon atoms, an alkoxycarbonyl group having from 1
to about 12 carbon atoms, an alkyl group having from 1 to about 12
carbon atoms, an amine group having from 1 to about 12 carbon atoms
or a silyl group having from 0 to about 12 carbon atoms, a method
wherein the substrate comprises a microelectronic device
structure.
13. A method for forming a metal material on a substrate from an
organometallic precursor, said method comprising vaporizing said
organometallic precursor to form a vapor, and contacting the vapor
with the substrate to form said metal material thereon, wherein the
substrate comprises a microelectronic device structure, and wherein
the precursor is represented by the formula
(Cp(R').sub.x).sub.yM(H).sub.z-y wherein M is a metal selected from
tantalum (Ta), tungsten (W), molybdenum (Mo), niobium (Nb),
vanadium (V) or chromium (Cr), each R' is the same or different and
represents a halogen atom, an acyl group having from 1 to about 12
carbon atoms, an alkoxy group having from 1 to about 12 carbon
atoms, an alkoxycarbonyl group having from 1 to about 12 carbon
atoms, an alkyl group having from 1 to about 12 carbon atoms, an
amine group having from 1 to about 12 carbon atoms or a silyl group
having from 0 to about 12 carbon atoms, Cp is a substituted or
unsubstituted cyclopentadienyl group or a substituted or
unsubstituted cyclopentadienyl-like group, x is an interger from 0
to 5, y is an interger from 1 to 5, and z in the valence of M.
14. A method for processing a substrate in a processing chamber,
said method comprising (i) introducing an organometallic precursor
into said processing chamber, said organometallic precursor having
the formula (Cp(R').sub.x).sub.yM(H).sub.z-y wherein M is a metal
selected from tantalum (Ta), tungsten (W), molybdenum (Mo), niobium
(Nb), vanadium (V) or chromium (Cr), each R' is the same or
different and represents a halogen atom, an acyl group having from
1 to about 12 carbon atoms, an alkoxy group having from 1 to about
12 carbon atoms, an alkoxycarbonyl group having from 1 to about 12
carbon atoms, an alkyl group having from 1 to about 12 carbon
atoms, an amine group having from 1 to about 12 carbon atoms or a
silyl group having from 0 to about 12 carbon atoms, Cp is a
substituted or unsubstituted cyclopentadienyl group or a
substituted or unsubstituted cyclopentadienyl-like group, x is an
integer from 0 to 5, y is an integer from 1 to 5, and z is the
valence of M, (ii) heating said substrate to a temperature of about
100.degree. C. to about 400.degree. C., and (iii) disassociating
said organometallic precursor in the presence of a processing gas
to deposit a metal layer on said substrate, wherein disassociating
the precursor further comprises generating a plasma at a power
density between about 0.6 Watts/cm.sup.2 and about 3.2
Watts/cm.sup.2.
15. A method for processing a substrate in a processing chamber,
said method comprising (i) introducing an organometallic precursor
into said processing chamber, said organometallic precursor having
the formula (Cp(R').sub.x).sub.yM(H).sub.z-y wherein M is a metal
selected from tantalum (Ta), tungsten (W), molybdenum (Mo), niobium
(Nb), vanadium (V) or chromium (Cr), each R' is the same or
different and represents a halogen atom, an acyl group having from
1 to about 12 carbon atoms, an alkoxy group having from 1 to about
12 carbon atoms, an alkoxycarbonyl group having from 1 to about 12
carbon atoms, an alkyl group having from 1 to about 12 carbon
atoms, an amine group having from 1 to about12 carbon atoms or a
silyl group having from 0 to about 12 carbon atoms, Cp is a
substituted, or unsubstituted cyclopentadienyl group or a
substituted or unsubstituted syclopentadienyl-like group, x is an
integer from 0 to 5, y is an interger from 1 to 5, and z is the
valence of M, (ii) heading said substrate to a temperature of about
100.degree. C. to about 400.degree. C., and (iii) disassociating
said organometallic precursor in the presence of a processing gas
to deposit a metal layer on said substrate, and further comprising
exposing the deposited metal layer to a plasma generated at a power
density between about 0.6 Watts/cm.sup.2 and about 3.2
Watts/cm.sup.2.
Description
CROSS-REFERENCE TO RELATED APPLICATION
[0001] This application is a divisional and claims priority to U.S.
patent application Ser. No. 11/501,075 filed Aug. 9, 2006, and U.S.
patent application Ser. No. 12/364,197 filed Feb. 2, 2009, the
contents of which are incorporated herein by reference in its
entirety.
FIELD OF THE INVENTION
[0002] This invention relates to organometallic compounds, a
process for producing organometallic compounds, and a method for
producing a film or coating from organometallic precursor
compounds.
BACKGROUND OF THE INVENTION
[0003] The semiconductor industry is currently considering the use
of thin films of various metals for a variety of applications. Many
organometallic complexes have been evaluated as potential
precursors for the formation of these thin films. A need exists in
the industry for developing new compounds and for exploring their
potential as precursors for film depositions. The industry movement
from physical vapor deposition (PVD) to chemical vapor deposition
(CVD) and atomic layer deposition (ALD) processes, due to the
increased demand for higher uniformity and conformality in thin
films, has lead to a demand for suitable precursors for future
semiconductor materials.
[0004] In the industry, conducting metals such as copper are being
used to fill sub-micron features on substrates during the
manufacture of integrated circuits. However, copper can diffuse
into the structure of adjacent dielectric layers, thereby
compromising the integrity of the devices being formed. Diffusion,
as well as interlayer defects, such as layer delamination, may be
prevented by depositing a barrier layer, a liner layer, or a
combination of both, on the underlying material before depositing
the conducting metal. The barrier layer is deposited on the
underlying material and is often a nitride of a metal that prevents
interlayer diffusion and minimizes chemical reactions between
underlying materials and subsequently deposited materials. The
liner layer is conventionally composed of a metal that provides
adhesion for the conducting metal layer.
[0005] Metals such as tantalum, niobium, tungsten, and the
respective metal nitrides are being considered for liner and
barrier materials in copper applications. See, for example, U.S.
Pat. Nos. 6,491,978 B1 and 6,379,748 B1. Depending on the
application, a liner adhesion layer and/or a diffusion barrier
layer may comprise a metal, such as tantalum, niobium, or tungsten,
a metal nitride layer, such as tantalum nitride, niobium nitride
layer, or tungsten nitride, a metal and metal nitride stack, or
other combinations of diffusion barrier materials. Metal and metal
nitride layers have been traditionally deposited by PVD techniques.
However, traditional PVD techniques are not well suited for
providing conformal coverage on the wall and bottom surfaces of
high aspect ratio vias and other features. Therefore, as aspect
ratios increase and device features shrink, new precursors and
deposition techniques are being investigated to provide conformal
coverage in these device features.
[0006] As referred to above, one proposed alternative to PVD
techniques of metal and metal nitride layers is depositing the
layers by CVD techniques to provide good conformal coverage of
substrate features. The ability to deposit conformal metal and
metal nitride layers in high aspect ratio features by the
disassociation of organometallic precursors has gained interest in
recent years due to the development of CVD techniques. In such
techniques, an organometallic precursor comprising a metal
component and organic component is introduced into a processing
chamber and disassociates to deposit the metal component on a
substrate while the organic portion of the precursor is exhausted
from the chamber.
[0007] There are few commercially available organometallic
precursors for the deposition of metal layers, such as tantalum,
niobium, and tungsten precursors by CVD techniques. The precursors
that are available produce layers which may have unacceptable
levels of contaminants such as carbon and oxygen, and have less
than desirable diffusion resistance, low thermal stability, and
undesirable layer characteristics. Further, in some cases, the
available precursors used to deposit metal nitride layers produce
layers with high resistivity, and in some cases, produce layers
that are insulative.
[0008] Another proposed alternative to PVD processes is ALD
processes. ALD technology is considered superior to PVD technology
in depositing thin films. However, the challenge for ALD technology
is availability of suitable precursors. ALD deposition process
involves a sequence of steps. The steps include 1) adsorption of
precursors on the surface of substrate; 2) purging off excess
precursor molecules in gas phase; 3) introducing reactants to react
with precursor on the substrate surface; and 4) purging off excess
reactant.
[0009] For ALD processes, the precursor should meet stringent
requirements. First, the ALD precursors should be able to form a
monolayer on the substrate surface either through physisorption or
chemisorption under the deposition conditions. Second, the adsorbed
precursor should be stable enough to prevent premature
decomposition on the surface to result in high impurity levels.
Third, the adsorbed molecule should be reactive enough to interact
with reactants to leave a pure phase of the desirable material on
the surface at relatively low temperature.
[0010] As with CVD, there are few commercially available
organometallic precursors for the deposition of metal layers, such
as tantalum, niobium, and tungsten precursors by ALD techniques.
ALD precursors that are available may have one or more of following
disadvantages: 1) low vapor pressure, 2) wrong phase of the
deposited material, and 3) high carbon incorporation in the
film.
[0011] Therefore, there remains a need for developing new compounds
and for exploring their potential as CVD and ALD precursors for
film depositions. There also remains a need for a process for
forming liner and/or barrier layers of metal or metal derivative
materials from organometallic precursors using CVD and ALD
techniques. Ideally, the liner and/or barrier layers deposited are
substantially free of contaminants, have reduced layer
resistivities, improved interlayer adhesion, improved diffusion
resistance, and improved thermal stability over those produced with
PVD processes.
SUMMARY OF THE INVENTION
[0012] This invention relates to compounds having the formula
(Cp(R').sub.x).sub.yM(H).sub.z-y wherein M is a metal selected from
tantalum (Ta), tungsten (W), molybdenum (Mo), niobium (Nb),
vanadium (V) or chromium (Cr), each R' is the same or different and
represents a halogen atom, an acyl group having from 1 to about 12
carbon atoms, an alkoxy group having from 1 to about 12 carbon
atoms, an alkoxycarbonyl group having from 1 to about 12 carbon
atoms, an alkyl group having from 1 to about 12 carbon atoms, an
amine group having from 1 to about 12 carbon atoms or a silyl group
having from 0 to about 12 carbon atoms, Cp is a substituted or
unsubstituted cyclopentadienyl group or a substituted or
unsubstituted cyclopentadienyl-like group, x is an integer from 0
to 5, y is an integer from 1 to 5, and z is the valence of M.
[0013] This invention relates to organometallic precursors having
the formula (Cp(R').sub.x).sub.yM(H).sub.z-y wherein M is a metal
selected from tantalum (Ta), tungsten (W), molybdenum (Mo), niobium
(Nb), vanadium (V) or chromium (Cr), each R' is the same or
different and represents a halogen atom, an acyl group having from
1 to about 12 carbon atoms, an alkoxy group having from 1 to about
12 carbon atoms, an alkoxycarbonyl group having from 1 to about 12
carbon atoms, an alkyl group having from 1 to about 12 carbon
atoms, an amine group having from 1 to about 12 carbon atoms or a
silyl group having from 0 to about 12 carbon atoms, Cp is a
substituted or unsubstituted cyclopentadienyl group or a
substituted or unsubstituted cyclopentadienyl-like group, x is an
integer from 0 to 5, y is an integer from 1 to 5, and z is the
valence of M.
[0014] This invention relates to a process for producing a compound
having the formula (Cp(R').sub.x).sub.yM(H).sub.z-y wherein M is a
metal selected from tantalum (Ta), tungsten (W), molybdenum (Mo),
niobium (Nb), vanadium (V) or chromium (Cr), each R' is the same or
different and represents a halogen atom, an acyl group having from
1 to about 12 carbon atoms, an alkoxy group having from 1 to about
12 carbon atoms, an alkoxycarbonyl group having from 1 to about 12
carbon atoms, an alkyl group having from 1 to about 12 carbon
atoms, an amine group having from 1 to about 12 carbon atoms or a
silyl group having from 0 to about 12 carbon atoms, Cp is a
substituted or unsubstituted cyclopentadienyl group or a
substituted or unsubstituted cyclopentadienyl-like group, x is an
integer from 0 to 5, y is an integer from 1 to 5, and z is the
valence of M, which process comprises reacting a metal halide, a
cyclopentadienyl salt and a reducing agent in the presence of a
first solvent and under reaction conditions sufficient to produce
an intermediate reaction material, and reacting said intermediate
reaction material with a base material in the presence of a second
solvent and under reaction conditions sufficient to produce said
compound.
[0015] This invention relates to a method for producing a film,
coating or powder by decomposing an organometallic precursor, said
organometallic precursor having the formula
(Cp(R').sub.x).sub.yM(H).sub.z-y wherein M is a metal selected from
tantalum (Ta), tungsten (W), molybdenum (Mo), niobium (Nb),
vanadium (V) or chromium (Cr), each R' is the same or different and
represents a halogen atom, an acyl group having from 1 to about 12
carbon atoms, an alkoxy group having from 1 to about 12 carbon
atoms, an alkoxycarbonyl group having from 1 to about 12 carbon
atoms, an alkyl group having from 1 to about 12 carbon atoms, an
amine group having from 1 to about 12 carbon atoms or a silyl group
having from 0 to about 12 carbon atoms, Cp is a substituted or
unsubstituted cyclopentadienyl group or a substituted or
unsubstituted cyclopentadienyl like group, x is an integer from 0
to 5, y is an integer from 1 to 5, and z is the valence of M,
thereby producing said film, coating or powder.
[0016] This invention relates to a method for processing a
substrate in a processing chamber, said method comprising (i)
introducing an organometallic precursor into said processing
chamber, said organometallic precursor having the formula
(Cp(R').sub.x).sub.yM(H).sub.z-y wherein M is a metal selected from
tantalum (Ta), tungsten (W), molybdenum (Mo), niobium (Nb),
vanadium (V) or chromium (Cr), each R' is the same or different and
represents a halogen atom, an acyl group having from 1 to about 12
carbon atoms, an alkoxy group having from 1 to about 12 carbon
atoms, an alkoxycarbonyl group having from 1 to about 12 carbon
atoms, an alkyl group having from 1 to about 12 carbon atoms, an
amine group having from 1 to about 12 carbon atoms or a silyl group
having from 0 to about 12 carbon atoms, Cp is a substituted or
unsubstituted cyclopentadienyl group or a substituted or
unsubstituted cyclopentadienyl-like group, x is an integer from 0
to 5, y is an integer from 1 to 5, and z is the valence of M, (ii)
heating said substrate to a temperature of about 100.degree. C. to
about 400.degree. C., and (iii) disassociating said organometallic
precursor in the presence of a processing gas to deposit a metal
layer on said substrate.
DETAILED DESCRIPTION OF THE INVENTION
[0017] As indicated above, this invention relates to organometallic
precursor compounds capable of forming metal-based materials, e.g.,
a metal and metal carbide such as Ta metal and TaC, W metal and WC,
and Nb metal and NbC, on a substrate by techniques such as CVD and
ALD. The substrate can preferably be microelectronic device
structures for applications such as copper metallization of
semiconductor device structures.
[0018] The organometallic precursor compounds of this invention
useful for the formation of metal-based material layers, e.g., Ta
metal and TaC barrier layers, include those compounds having the
formula (Cp(R').sub.x).sub.yM(H).sub.z-y wherein M is a metal
selected from tantalum (Ta), tungsten (W), molybdenum (Mo), niobium
(Nb), vanadium (V) or chromium (Cr), each R' is the same or
different and represents a halogen atom, an acyl group having from
1 to about 12 carbon atoms, an alkoxy group having from 1 to about
12 carbon atoms, an alkoxycarbonyl group having from 1 to about 12
carbon atoms, an alkyl group having from 1 to about 12 carbon
atoms, an amine group having from 1 to about 12 carbon atoms or a
silyl group having from 0 to about 12 carbon atoms, Cp is a
substituted or unsubstituted cyclopentadienyl group or a
substituted or unsubstituted cyclopentadienyl-like group, x is an
integer from 0 to 5, y is an integer from 1 to 5, and z is the
valence of M.
[0019] This invention in part provides organometallic precursors
and a method of processing a substrate to form a metal layer and/or
metal carbide layer on the substrate by CVD or ALD of the
organometallic precursor. The metal or metal carbide layer is
deposited on a heated substrate by thermal or plasma enhanced
disassociation of the organometallic precursor having the formula
(Cp(R').sub.x).sub.yM(H).sub.z-y in the presence of a processing
gas. The processing gas may be an inert gas, such as helium and
argon, and combinations thereof. The composition of the processing
gas is selected to deposit metal and metal carbide layers as
desired.
[0020] For the organometallic precursors of this invention
represented by the formula (Cp(R').sub.x).sub.yM(H).sub.z-y, M
represents the metal to be deposited. Examples of metals which can
be deposited according to this invention are the Group VIB metals
of tungsten, molybdenum and chromium, and the Group VB metals of
vanadium, tantalum, and niobium. Y is the valence of the metal, M,
of the precursor, with a valence of 6 for the Group VIB metals and
a valence of 5 for the Group VB metals.
[0021] Cp is a cyclopentadienyl ring having the general formula
(C.sub.5H.sub.5--) which forms a ligand with the metal, M. The
cyclopentadienyl ring may be substituted, thereby having the
formula (Cp(R').sub.x).sub.n, where n is the number of
cyclopentadienyl groups forming ligands with the metal, M. At least
one, but generally between 1 and 5 cyclopentadienyl groups faun a
ligand with the metal, M, in forming the precursor. The precursor
preferably contains two cyclopentadienyl groups.
[0022] Illustrative substituted cyclopentadienyl-like moieties
include cyclo-olefin e.g., cyclohexadienyl, cycloheptadienyl,
cyclooctadienyl rings, heterocyclic rings, aromatic rings, such as
substituted benzenyl, and others, as known in the art.
[0023] Permissible substituents of the substituted cyclopentadienyl
and cyclopentadienyl-like groups include halogen atoms, acyl groups
having from 1 to about 12 carbon atoms, alkoxy groups having from 1
to about 12 carbon atoms, alkoxycarbonyl groups having from 1 to
about 12 carbon atoms, alkyl groups having from 1 to about 12
carbon atoms, amine groups having from 1 to about 12 carbon atoms
or silyl groups having from 0 to about 12 carbon atoms.
[0024] Illustrative halogen atoms include, for example, fluorine,
chlorine, bromine and iodine. Preferred halogen atoms include
chlorine and fluorine.
[0025] Illustrative acyl groups include, for example, formyl,
acetyl, propionyl, butyryl, isobutyryl, valeryl,
1-methylpropylcarbonyl, isovaleryl, pentylcarbonyl,
1-methylbutylcarbonyl, 2-methylbutylcarbonyl,
3-methylbutylcarbonyl, 1-ethylpropylcarbonyl,
2-ethylpropylcarbonyl, and the like. Preferred acyl groups include
formyl, acetyl and propionyl.
[0026] Illustrative alkoxy groups include, for example, methoxy,
ethoxy, n-propoxy, isopropoxy, n-butoxy, isobutoxy, sec-butoxy,
tert-butoxy, pentyloxy, 1-methylbutyloxy, 2-methylbutyloxy,
3-methylbutyloxy, 1,2-dimethylpropyloxy, hexyloxy,
1-methylpentyloxy, 1-ethylpropyloxy, 2-methylpentyloxy,
3-methylpentyloxy, 4-methylpentyloxy, 1,2-dimethylbutyloxy,
1,3-dimethylbutyloxy, 2,3-dimethylbutyloxy, 1,1-dimethylbutyloxy,
2,2-dimethylbutyloxy, 3,3-dimethylbutyloxy, and the like. Preferred
alkoxy groups include methoxy, ethoxy and propoxy.
[0027] Illustrative alkoxycarbonyl groups include, for example,
methoxycarbonyl, ethoxycarbonyl, propoxycarbonyl,
isopropoxycarbonyl, cyclopropoxycarbonyl, butoxycarbonyl,
isobutoxycarbonyl, sec-butoxycarbonyl, tert-butoxycarbonyl, and the
like. Preferred alkoxycarbonyl groups include methoxycarbonyl,
ethoxycarbonyl, propoxycarbonyl, isopropoxycarbonyl and
cyclopropoxycarbonyl.
[0028] Illustrative alkyl groups include, for example, methyl,
ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl,
tert-butyl, pentyl, isopentyl, neopentyl, tert-pentyl,
1-methylbutyl, 2-methylbutyl, 1,2-dimethylpropyl, hexyl, isohexyl,
1-methylpentyl, 2-methylpentyl, 3-methylpentyl, 1,1-dimethylbutyl,
2,2-dimethylbutyl, 1,3-dimethylbutyl, 2,3-dimethylbutyl,
3,3-dimethylbutyl, 1-ethylbutyl, 2-ethylbutyl,
1,1,2-trimethylpropyl, 1,2,2-trimethylpropyl,
1-ethyl-1-methylpropyl, 1-ethyl-2-methylpropyl, cyclopropyl,
cyclobutyl, cyclopentyl, cyclohexyl, cyclopropylmethyl,
cyclopropylethyl, cyclobutylmethyl, and the like. Preferred alkyl
groups include methyl, ethyl, n-propyl, isopropyl and
cyclopropyl.
[0029] Illustrative amine groups include, for example, methylamine,
dimethylamine, ethylamine, diethylamine, propylamine,
dipropylamine, isopropylamine, diisopropylamine, butylamine,
dibutylamine, tert-butylamine, di(tert-butyl)amine,
ethylmethylamine, butylmethylamine, cyclohexylamine,
dicyclohexylamine, and the like. Preferred amine groups include
dimethylamine, diethylamine and diisopropylamine.
[0030] Illustrative silyl groups include, for example, silyl,
trimethylsilyl, triethylsilyl, tris(trimethylsilyl)methyl,
trisilylmethyl, methylsilyl and the like. Preferred silyl groups
include silyl, trimethylsilyl and triethylsilyl.
[0031] In a preferred embodiment, this invention relates in part to
organometallic tantalum compounds represented by the formula
##STR00001##
[0032] wherein R.sub.1, R.sub.2 and each R are the same or
different and each represent a halogen atom, an acyl group having
from 1 to about 12 carbon atoms, an alkoxy group having from 1 to
about 12 carbon atoms, an alkoxycarbonyl group having from 1 to
about 12 carbon atoms, an alkyl group having from 1 to about 12
carbon atoms, an amine group having from 1 to about 12 carbon atoms
or a silyl group having from 0 to about 12 carbon atoms.
[0033] Illustrative organometallic compounds of this invention
include, for example, bis(cyclopentadienyl)(allyl)tantalum,
bis(cyclopentadienyl)(alkene)(hydrido)tantalum or
bis(cyclopentadienyl)(trialkyl)tantalum,
bis(cyclopentadienyl)(trihydrido)tantalum, and the like.
[0034] It is believed that the presence of the substituent groups
on the cyclopentadienyl groups, particularly the silicon containing
substituent groups, enhance preferred physical properties. It is
believed that the substituent groups increase organometallic
precursor volatility, decrease the temperature required to
disassociate the precursor, and lower the boiling point of the
organometallic precursor. An increased volatility of the
organometallic precursor compounds ensures a sufficiently high
concentration of precursor entrained in vaporized fluid flow to the
processing chamber for effective deposition of a layer. The
improved volatility will also allow the use of vaporization of the
organometallic precursor by sublimation and delivery to a
processing chamber without risk of premature disassociation.
Additionally, the presence of substituent cyclopentadienyl groups
may also provide sufficient solubility of the organometallic
precursor for use in liquid delivery systems.
[0035] It is believed that the organometallic precursors described
herein have functional groups which allow the formation of heat
decomposable organometallic compounds that are thermally stable at
temperatures below about 150.degree. C. and are capable of
thermally disassociating at a temperature above about 150.degree.
C. The organometallic precursors are also capable of disassociation
in a plasma generated by supplying a power density at about 0.6
Watts/cm.sup.2 or greater, or at about 200 Watts or greater for a
200 mm substrate, to a processing chamber.
[0036] The organometallic precursors described herein may deposit
metal and metal carbide layers depending on the processing gas
composition and the plasma gas composition for the deposition
process. A metal or metal carbide layer is deposited in the
presence of inert processing gases such as argon, a reactant
processing gas, such as hydrogen, and combinations thereof.
[0037] It is believed that the use of a reactant processing gas,
such as hydrogen, facilitates reaction with the cyclopentadienyl
groups to form volatile gases, thereby removing the
cyclopentadienyl ring from the precursor and depositing a metal or
metal carbide layer on the substrate. The metal layer is preferably
deposited in the presence of argon.
[0038] An exemplary processing regime for depositing a layer from
the above described precursor is as follows. A precursor having the
composition described herein, such as
bis(cyclopentadienyl)(allyl)tantalum and a processing gas is
introduced into a processing chamber. The precursor is introduced
at a flow rate between about 5 and about 500 sccm and the
processing gas is introduced into the chamber at a flow rate of
between about 5 and about 500 sccm. In one embodiment of the
deposition process, the precursor and processing gas are introduced
at a molar ratio of about 1:1. The processing chamber is maintained
at a pressure between about 100 milliTorr and about 20 Torr. The
processing chamber is preferably maintained at a pressure between
about 100 milliTorr and about 250 milliTorr. Flow rates and
pressure conditions may vary for different makes, sizes, and models
of the processing chambers used.
[0039] Thermal disassociation of the precursor involves heating the
substrate to a temperature sufficiently high to cause the
hydrocarbon portion of the volatile metal compound adjacent the
substrate to disassociate to volatile hydrocarbons which desorb
from the substrate while leaving the metal on the substrate. The
exact temperature will depend upon the identity and chemical,
thermal, and stability characteristics of the organometallic
precursor and processing gases used under the deposition
conditions. However, a temperature from about room temperature to
about 400.degree. C. is contemplated for the thermal disassociation
of the precursor described herein.
[0040] The thermal disassociation is preferably performed by
heating the substrate to a temperature between about 100.degree. C.
and about 400.degree. C. In one embodiment of the thermal
disassociation process, the substrate temperature is maintained
between about 250.degree. C. and about 450.degree. C. to ensure a
complete reaction between the precursor and the reacting gas on the
substrate surface. In another embodiment, the substrate is
maintained at a temperature below about 400.degree. C. during the
thermal disassociation process.
[0041] For plasma-enhanced CVD processes, power to generate a
plasma is then either capacitively or inductively coupled into the
chamber to enhance disassociation of the precursor and increase
reaction with any reactant gases present to deposit a layer on the
substrate. A power density between about 0.6 Watts/cm.sup.2 and
about 3.2 Watts/cm.sup.2, or between about 200 and about 1000
Watts, with about 750 Watts most preferably used for a 200 mm
substrate, is supplied to the chamber to generate the plasma.
[0042] After disassociation of the precursor and deposition of the
material on the substrate, the deposited material may be exposed to
a plasma treatment. The plasma comprises a reactant processing gas,
such as hydrogen, an inert gas, such as argon, and combinations
thereof. In the plasma-treatment process, power to generate a
plasma is either capacitively or inductively coupled into the
chamber to excite the processing gas into a plasma state to produce
plasma specie, such as ions, which may react with the deposited
material. The plasma is generated by supplying a power density
between about 0.6 Watts/cm.sup.2 and about 3.2 Watts/cm.sup.2, or
between about 200 and about 1000 Watts for a 200 mm substrate, to
the processing chamber.
[0043] In one embodiment the plasma treatment comprises introducing
a gas at a rate between about 5 seem and about 300 seem into a
processing chamber and generating a plasma by providing power
density between about 0.6 Watts/cm.sup.2 and about 3.2
Watts/cm.sup.2, or a power at between about 200 Watts and about
1000 Watts for a 200 mm substrate, maintaining the chamber pressure
between about 50 milliTorr and about 20 Torr, and maintaining the
substrate at a temperature of between about 100.degree. C. and
about 400.degree. C. during the plasma process.
[0044] It is believed that the plasma treatment lowers the layer's
resistivity, removes contaminants, such as carbon or excess
hydrogen, and densities the layer to enhance barrier and liner
properties. It is believed that species from reactant gases, such
as hydrogen species in the plasma react with the carbon impurities
to produce volatile hydrocarbons that can easily desorb from the
substrate surface and can be purged from the processing zone and
processing chamber. Plasma species from inert gases, such as argon,
further bombard the layer to remove resistive constituents to lower
the layers resistivity and improve electrical conductivity.
[0045] Plasma treatments are preferably not performed for metal
carbide layers, since the plasma treatment may remove the desired
carbon content of the layer. If a plasma treatment for a metal
carbide layer is performed, the plasma gases preferably comprise
inert gases, such as argon and helium, to remove carbon.
[0046] It is believed that depositing layers from the above
identified precursors and exposing the layers to a post deposition
plasma process will produce a layer with improved material
properties. The deposition and/or treatment of the materials
described herein are believed to have improved diffusion
resistance, improved interlayer adhesion, improved thermal
stability, and improved interlayer bonding.
[0047] In an embodiment of this invention, a method for
metallization of a feature on a substrate is provided that
comprises depositing a dielectric layer on the substrate, etching a
pattern into the substrate, depositing a metal carbide layer on the
dielectric layer, and depositing a conductive metal layer on the
metal carbide layer. The substrate may be optionally exposed to
reactive pre-clean comprising a plasma of hydrogen and argon to
remove oxide formations on the substrate prior to deposition of the
metal carbide layer. The conductive metal is preferably copper and
may be deposited by physical vapor deposition, chemical vapor
deposition, or electrochemical deposition. The metal layer and the
metal carbide layer are deposited by the thermal or plasma enhanced
disassociation of an organometallic precursor of this invention in
the presence of a processing gas, preferably at a pressure less
than about 20 Torr. Once deposited, the metal layer and the metal
carbide layer can be exposed to a plasma prior to subsequent layer
deposition.
[0048] Current copper integration schemes involve a diffusion
barrier with a copper wetting layer on top followed by a copper
seed layer. A layer of TaC gradually becoming tantalum rich in
accordance with this invention would replace multiple steps in the
current integration schemes. The TaC layer is an excellent barrier
to copper diffusion due to its amorphous character. The tantalum
rich layer functions as a wetting layer and may allow for direct
plating onto the tantalum. This single layer could be deposited in
one step by manipulating the deposition parameters during the
deposition. A post deposition treatment may also be employed to
increase the ratio of tantalum in the film. Removal of one or more
steps in semiconductor manufacture will result in substantial
savings to the semiconductor manufacturer.
[0049] TaC films from Cp.sub.2TaH.sub.3 are deposited at
temperatures lower than 400.degree. C. and form no corrosive
byproducts. TaC films are amorphous and are superior barriers than
TaN to copper diffusion. By tuning the deposition parameters and
post deposition treatment, the TaC barrier can have a tantalum rich
film deposited on top of it. This tantalum rich film acts as a
wetting layer for copper and may allow for direct copper plating on
top of the Ta layer. In an embodiment, the deposition parameters
may be tuned to provide a layer in which the composition varies
across the thickness of the layer. For example, the layer may be
TaC rich at the silicon portion surface of the microchip, e.g.,
good barrier properties, and Ta rich at the copper layer surface,
e.g., good adhesive properties.
[0050] As also indicated above, this invention also relates in part
to a process for producing the organometallic compound represented
by the formula (Cp(R').sub.x).sub.yM(H).sub.z-y wherein M is a
metal selected from tantalum (Ta), tungsten (W), molybdenum (Mo),
niobium (Nb), vanadium (V) or chromium (Cr), each R' is the same or
different and represents a halogen atom, an acyl group having from
1 to about 12 carbon atoms, an alkoxy group having from 1 to about
12 carbon atoms, an alkoxycarbonyl group having from 1 to about 12
carbon atoms, an alkyl group having from 1 to about 12 carbon
atoms, an amine group having from 1 to about 12 carbon atoms or a
silyl group having from 0 to about 12 carbon atoms, Cp is a
substituted or unsubstituted cyclopentadienyl group or a
substituted or unsubstituted cyclopentadienyl-like group, x is an
integer from 0 to 5, y is an integer from 1 to 5, and z is the
valence of M, which process comprises reacting a metal halide, a
cyclopentadienyl salt and a reducing agent in the presence of a
first solvent and under reaction conditions sufficient to produce
an intermediate reaction material, and reacting said intermediate
reaction material with a base material in the presence of a second
solvent and under reaction conditions sufficient to produce said
organometallic precusrors. The organometallic compound yield
resulting from the process of this invention can be 40% or greater,
preferably 35% or greater, and more preferably 30% or greater.
[0051] The process is particularly well-suited for large scale
production since it can be conducted using the same equipment, some
of the same reagents and process parameters that can easily be
adapted to manufacture a wide range of products. The process
provides for the synthesis of organometallic precursor compounds
using a process where all manipulations can be carried out in a
single vessel, and which route to the organometallic precursor
compounds does not require the isolation of an intermediate
complex.
[0052] The metal halide compound starting material may be selected
from a wide variety of compounds known in the art. The invention
herein most prefers metals selected from tantalum (Ta), tungsten
(W), molybdenum (Mo), niobium (Nb), vanadium (V) or chromium (Cr).
Illustrative metal halide compounds include, for example, tantalum
pentachloride, niobium pentachloride, vanadium pentachloride,
tungsten hexachloride, molybdenum hexachloride, chromium
hexachloride, and the like.
[0053] The concentration of the metal source compound starting
material can vary over a wide range, and need only be that minimum
amount necessary to react with the cyclopentadienyl salt and
reducing agent to produce the intermediate reaction material and to
provide the given metal concentration desired to be employed and
which will furnish the basis for at least the amount of metal
necessary for the organometallic compounds of this invention. In
general, depending on the size of the reaction mixture, metal
source compound starting material concentrations in the range of
from about 1 millimole or less to about 10,000 millimoles or
greater, should be sufficient for most processes.
[0054] The cyclopentadienyl salt starting material may be selected
from a wide variety of compounds known in the art. Illustrative
cyclopentadienyl salts include sodium cyclopentadiene, potassium
cyclopentadiene, lithium cyclopentadiene, magnesocene, and the
like. The cyclopentadienyl salt starting material is preferably
sodium cyclopentadiene and the like.
[0055] The concentration of the cyclopentadienyl salt starting
material can vary over a wide range, and need only be that minimum
amount necessary to react with the metal source compound starting
material and reducing agent to produce an intermediate reaction
material. In general, depending on the size of the first reaction
mixture, cyclopentadienyl salt starting material concentrations in
the range of from about 1 millimole or less to about 10,000
millimoles or greater, should be sufficient for most processes.
[0056] The reducing agent starting material may be selected from a
wide variety of materials known in the art. Illustrative reducing
agents include sodium bis(2-methoxyethoxy)aluminum dihydride (e.g.,
Red-Al.RTM. and Vitride reducing agent materials), sodium
borohydride, lithium aluminum hydride, and the like. The reducing
agent material is preferably sodium bis(2-methoxyethoxy)aluminum
dihydride (e.g., Red-Al.RTM. reducing agent material), and the
like.
[0057] The concentration of the reducing agent starting material
can vary over a wide range, and need only be that minimum amount
necessary to react with the metal source compound starting material
and cyclopentadienyl salt starting material to produce an
intermediate reaction material. In general, depending on the size
of the first reaction mixture, reducing agent starting material
concentrations in the range of from about 1 millimole or less to
about 10,000 millimoles or greater, should be sufficient for most
processes.
[0058] The first solvent employed in the method of this invention
may be any saturated and unsaturated hydrocarbons, aromatic
hydrocarbons, aromatic heterocycles, alkyl halides, silylated
hydrocarbons, ethers, polyethers, thioethers, esters, thioesters,
lactones, amides, amines, polyamines, silicone oils, other aprotic
solvents, or mixtures of one or more of the above; more preferably,
diethylether, pentanes, or dimethoxyethanes; and most preferably
toluene or dimethoxyethane (DME) or mixtures thereof. Any suitable
solvent which does not unduly adversely interfere with the intended
reaction can be employed. Mixtures of one or more different
solvents may be employed if desired. The amount of solvent employed
is not critical to the subject invention and need only be that
amount sufficient to solubilize the reaction components in the
reaction mixture. In general, the amount of solvent may range from
about 5 percent by weight up to about 99 percent by weight or more
based on the total weight of the reaction mixture starting
materials.
[0059] Reaction conditions for the reaction of the cyclopentadienyl
salt compound and reducing agent with the metal source compound to
produce the intermediate reaction material, such as temperature,
pressure and contact time, may also vary greatly and any suitable
combination of such conditions may be employed herein. The reaction
temperature may be the reflux temperature of any of the
aforementioned solvents, and more preferably between about
-80.degree. C. to about 150.degree. C., and most preferably between
about 20.degree. C. to about 120.degree. C. Normally the reaction
is carried out under ambient pressure and the contact time may vary
from a matter of seconds or minutes to a few hours or greater. The
reactants can be added to the reaction mixture or combined in any
order. The stir time employed can range from about 0.1 to about 400
hours, preferably from about 1 to 75 hours, and more preferably
from about 4 to 16 hours, for all steps.
[0060] The intermediate reaction material may be selected from a
wide variety of materials known in the art. Illustrative
intermediate reaction materials include
bis(cyclopentadienyl)(dihydrido)tantalum(bis-(2-methoxyethoxy)aluminate.
The intermediate reaction material is preferably
bis(cyclopentadienyl)(dihydrido)tantalum(bis-(2-methoxyethoxy)aluminate,
and the like. The process of this invention does not require
isolation of the intermediate reaction material.
[0061] The concentration of the intermediate reaction material can
vary over a wide range, and need only be that minimum amount
necessary to react with the base material to produce the
organometallic compounds of this invention. In general, depending
on the size of the second reaction mixture, intermediate reaction
material concentrations in the range of from about 1 millimole or
less to about 10,000 millimoles or greater, should be sufficient
for most processes.
[0062] The base material may be selected from a wide variety of
materials known in the art. Illustrative base materials include
sodium hydroxide, potassium hydroxide, ethyl acetate, and the like.
The base material is preferably sodium hydroxide and the like.
[0063] The concentration of the base material can vary over a wide
range, and need only be that minimum amount necessary to react with
the intermediate reaction material to produce the organometallic
compounds of this invention. In general, depending on the size of
the second reaction mixture, base material concentrations in the
range of from about 1 millimole or less to about 10,000 millimoles
or greater, should be sufficient for most processes.
[0064] The second solvent employed in the method of this invention
may be any saturated and unsaturated hydrocarbons, aromatic
hydrocarbons, aromatic heterocycles, alkyl halides, silylated
hydrocarbons, ethers, polyethers, thioethers, esters, thioesters,
lactones, amides, amines, polyamines, silicone oils, other aprotic
solvents, or mixtures of one or more of the above; more preferably,
diethylether, pentanes, or dimethoxyethanes; and most preferably
toluene, hexane or mixtures thereof. Any suitable solvent which
does not unduly adversely interfere with the intended reaction can
be employed. Mixtures of one or more different solvents may be
employed if desired. The amount of solvent employed is not critical
to the subject invention and need only be that amount sufficient to
solubilize the reaction components in the reaction mixture. In
general, the amount of solvent may range from about 5 percent by
weight up to about 99 percent by weight or more based on the total
weight of the reaction mixture starting materials.
[0065] Reaction conditions for the reaction of the intermediate
reaction material with the base material to produce the
organometallic precursors of this invention, such as temperature,
pressure and contact time, may also vary greatly and any suitable
combination of such conditions may be employed herein. The reaction
temperature may be the reflux temperature of any of the
aforementioned solvents, and more preferably between about
-80.degree. C. to about 150.degree. C., and most preferably between
about 20.degree. C. to about 120.degree. C. Normally the reaction
is carried out under ambient pressure and the contact time may vary
from a matter of seconds or minutes to a few hours or greater. The
reactants can be added to the reaction mixture or combined in any
order. The stir time employed can range from about 0.1 to about 400
hours, preferably from about 1 to 75 hours, and more preferably
from about 4 to 16 hours, for all steps.
[0066] Other alternative processes that may be used in preparing
the organometallic compounds of this invention include those
disclosed in U.S. Pat. No. 6,605,735 B2 and U.S. Patent Application
Publication No. US 2004/0127732 A1, published Jul. 1, 2004, the
disclosure of which is incorporated herein by reference. The
organometallic compounds of this invention may also be prepared by
conventional processes such as described in Legzdins, P. et al.
Inorg. Synth. 1990, 28, 196 and references therein.
[0067] For organometallic compounds prepared by the method of this
invention, purification can occur through recrystallization, more
preferably through extraction of reaction residue (e.g., hexane)
and chromatography, and most preferably through sublimation and
distillation.
[0068] Those skilled in the art will recognize that numerous
changes may be made to the method described in detail herein,
without departing in scope or spirit from the present invention as
more particularly defined in the claims below.
[0069] Examples of techniques that can be employed to characterize
the organometallic compounds formed by the synthetic methods
described above include, but are not limited to, analytical gas
chromatography, nuclear magnetic resonance, thermogravimetric
analysis, inductively coupled plasma mass spectrometry,
differential scanning calorimetry, vapor pressure and viscosity
measurements.
[0070] Relative vapor pressures, or relative volatility, of
organometallic compound precursors described above can be measured
by thermogravimetric analysis techniques known in the art.
Equilibrium vapor pressures also can be measured, for example by
evacuating all gases from a sealed vessel, after which vapors of
the compounds are introduced to the vessel and the pressure is
measured as known in the art.
[0071] The organometallic compound precursors described herein are
well suited for preparing in-situ powders and coatings. For
instance, an organometallic compound precursor can be applied to a
substrate and then heated to a temperature sufficient to decompose
the precursor, thereby forming a metal or metal carbide, e.g., Ta
metal or TaC, coating on the substrate. Applying the precursor to
the substrate can be by painting, spraying, dipping or by other
techniques known in the art. Heating can be conducted in an oven,
with a heat gun, by electrically heating the substrate, or by other
means, as known in the art. A layered coating can be obtained by
applying an organometallic compound precursor, and heating and
decomposing it, thereby forming a first layer, followed by at least
one other coating with the same or different precursors, and
heating.
[0072] Organometallic compound precursors such as described above
also can be atomized and sprayed onto a substrate. Atomization and
spraying means, such as nozzles, nebulizers and others, that can be
employed are known in the art.
[0073] This invention provides in part an organometallic precursor
and a method of forming a metal or metal carbide layer on a
substrate by CVD or ALD of the organometallic precursor. In one
aspect of the invention, an organometallic precursor of this
invention is used to deposit a metal or metal carbide layer at
subatmospheric pressures. The method for depositing the metal or
metal carbide layer comprises introducing the precursor into a
processing chamber, preferably maintained at a pressure of less
than about 20 Torr, and disassociating the precursor in the
presence of a processing gas to deposit a metal or metal carbide
layer. The precursor may be disassociated and deposited by a
thermal or plasma-enhanced process. The method may further comprise
a step of exposing the deposited layer to a plasma process to
remove contaminants, densify the layer, and reduce the layer's
resistivity.
[0074] In preferred embodiments of the invention, an organometallic
compound, such as described above, is employed in gas phase
deposition techniques for forming powders, films or coatings. The
compound can be employed as a single source precursor or can be
used together with one or more other precursors, for instance, with
vapor generated by heating at least one other organometallic
compound or metal complex. More than one organometallic compound
precursor, such as described above, also can be employed in a given
process.
[0075] As indicated above, this invention also relates in part to a
method for producing a film, coating or powder. The method includes
the step of decomposing at least one organometallic compound
precursor, thereby producing the film, coating or powder, as
further described below.
[0076] Deposition methods described herein can be conducted to form
a film, powder or coating that includes a single metal or a film,
powder or coating that includes a single metal or metal carbide,
e.g., Ta metal or TaC. Mixed films, powders or coatings also can be
deposited, for instance mixed metal/metal carbide films.
[0077] Gas phase film deposition can be conducted to form film
layers of a desired thickness, for example, in the range of from
about 1 nm to over 1 mm The precursors described herein are
particularly useful for producing thin films, e.g., films having a
thickness in the range of from about 10 nm to about 100 nm. Films
of this invention, for instance, can be considered for fabricating
metal electrodes, in particular as n-channel metal electrodes in
logic, as capacitor electrodes for DRAM applications, and as
dielectric materials.
[0078] The method also is suited for preparing layered films,
wherein at least two of the layers differ in phase or composition.
Examples of layered film include metal-insulator-semiconductor, and
metal-insulator-metal.
[0079] In an embodiment, the invention is directed to a method that
includes the step of decomposing vapor of an organometallic
compound precursor described above, thermally, chemically,
photochemically or by plasma activation, thereby forming a film on
a substrate. For instance, vapor generated by the compound is
contacted with a substrate having a temperature sufficient to cause
the organometallic compound to decompose and form a film on the
substrate.
[0080] The organometallic compound precursors can be employed in
chemical vapor deposition or, more specifically, in metal organic
chemical vapor deposition processes known in the art. For instance,
the organometallic compound precursors described above can be used
in atmospheric, as well as in low pressure, chemical vapor
deposition processes. The compounds can be employed in hot wall
chemical vapor deposition, a method in which the entire reaction
chamber is heated, as well as in cold or warm wall type chemical
vapor deposition, a technique in which only the substrate is being
heated.
[0081] The organometallic compound precursors described above also
can be used in plasma or photo-assisted chemical vapor deposition
processes, in which the energy from a plasma or electromagnetic
energy, respectively, is used to activate the chemical vapor
deposition precursor. The compounds also can be employed in
ion-beam, electron-beam assisted chemical vapor deposition
processes in which, respectively, an ion beam or electron beam is
directed to the substrate to supply energy for decomposing a
chemical vapor deposition precursor. Laser-assisted chemical vapor
deposition processes, in which laser light is directed to the
substrate to affect photolytic reactions of the chemical vapor
deposition precursor, also can be used.
[0082] The method of the invention can be conducted in various
chemical vapor deposition reactors, such as, for instance, hot or
cold-wall reactors, plasma-assisted, beam-assisted or
laser-assisted reactors, as known in the art.
[0083] Examples of substrates that can be coated employing the
method of the invention include solid substrates such as metal
substrates, e.g., Al, Ni, Ti, Co, Pt, metal silicides, e.g.,
TiSi.sub.2, CoSi.sub.2, NiSi.sub.2; semiconductor materials, e.g.,
Si, SiGe, GaAs, InP, diamond, GaN, SiC; insulators, e.g.,
SiO.sub.2, Si.sub.3N.sub.4, HfO.sub.2, Ta.sub.2O.sub.5,
Al.sub.2O.sub.3, barium strontium titanate (BST); or on substrates
that include combinations of materials. In addition, films or
coatings can be formed on glass, ceramics, plastics, thermoset
polymeric materials, and on other coatings or film layers. In
preferred embodiments, film deposition is on a substrate used in
the manufacture or processing of electronic components. In other
embodiments, a substrate is employed to support a low resistivity
conductor deposit that is stable in the presence of an oxidizer at
high temperature or an optically transmitting film.
[0084] The method of this invention can be conducted to deposit a
film on a substrate that has a smooth, flat surface. In an
embodiment, the method is conducted to deposit a film on a
substrate used in wafer manufacturing or processing. For instance,
the method can be conducted to deposit a film on patterned
substrates that include features such as trenches, holes or vias.
Furthermore, the method of the invention also can be integrated
with other steps in wafer manufacturing or processing, e.g.,
masking, etching and others.
[0085] In an embodiment of this invention, a plasma assisted ALD
(PEALD) method has been developed for using the organometallic
precursors to deposit TaC and tantalum rich films. The solid
precursor can be sublimed under the flow of an inert gas to
introduce it into a CVD chamber. TaC films are grown on a substrate
with the aid of a hydrogen plasma. The ratio of tantalum to carbon
can be controlled by controlling the pulse duration of the hydrogen
plasma.
[0086] Chemical vapor deposition films can be deposited to a
desired thickness. For example, films formed can be less than 1
micron thick, preferably less than 500 nanometers and more
preferably less than 200 nanometers thick. Films that are less than
50 nanometers thick, for instance, films that have a thickness
between about 0.1 and about 20 nanometers, also can be
produced.
[0087] Organometallic compound precursors described above also can
be employed in the method of the invention to form films by ALD
processes or atomic layer nucleation (ALN) techniques, during which
a substrate is exposed to alternate pulses of precursor, oxidizer
and inert gas streams. Sequential layer deposition techniques are
described, for example, in U.S. Pat. No. 6,287,965 and in U.S. Pat.
No. 6,342,277. The disclosures of both patents are incorporated
herein by reference in their entirety.
[0088] For example, in one ALD cycle, a substrate is exposed, in
step-wise manner, to: a) an inert gas; b) inert gas carrying
precursor vapor; c) inert gas; and d) oxidizer, alone or together
with inert gas. In general, each step can be as short as the
equipment will permit (e g milliseconds) and as long as the process
requires (e.g. several seconds or minutes). The duration of one
cycle can be as short as milliseconds and as long as minutes. The
cycle is repeated over a period that can range from a few minutes
to hours. Film produced can be a few nanometers thin or thicker,
e.g., 1 millimeter (mm)
[0089] This invention includes a method for forming a metal
material, e.g., Ta metal or TaC, on a substrate, e.g., a
microelectronic device structure, from an organometallic precursor
of this invention, said method comprising vaporizing said
organometallic precursor to form a vapor, and contacting the vapor
with the substrate to form said metal material thereon. After Ta
metal or TaC is deposited on the substrate, the substrate may
thereafter be metallized with copper or integrated with a
ferroelectric thin film.
[0090] The method of the invention also can be conducted using
supercritical fluids. Examples of film deposition methods that use
supercritical fluid that are currently known in the art include
chemical fluid deposition; supercritical fluid transport-chemical
deposition; supercritical fluid chemical deposition; and
supercritical immersion deposition.
[0091] Chemical fluid deposition processes, for example, are well
suited for producing high purity films and for covering complex
surfaces and filling of high-aspect-ratio features. Chemical fluid
deposition is described, for instance, in U.S. Pat. No. 5,789,027.
The use of supercritical fluids to form films also is described in
U.S. Pat. No. 6,541,278 B2. The disclosures of these two patents
are incorporated herein by reference in their entirety.
[0092] In an embodiment of the invention, a heated patterned
substrate is exposed to one or more organometallic compound
precursors, in the presence of a solvent, such as a near critical
or supercritical fluid, e.g., near critical or supercritical
CO.sub.2. In the case of CO.sub.2, the solvent fluid is provided at
a pressure above about 1000 psig and a temperature of at least
about 30.degree. C.
[0093] The precursor is decomposed to form a metal film on the
substrate. The reaction also generates organic material from the
precursor. The organic material is solubilized by the solvent fluid
and easily removed away from the substrate.
[0094] In an example, the deposition process is conducted in a
reaction chamber that houses one or more substrates. The substrates
are heated to the desired temperature by heating the entire
chamber, for instance, by means of a furnace. Vapor of the
organometallic compound can be produced, for example, by applying a
vacuum to the chamber. For low boiling compounds, the chamber can
be hot enough to cause vaporization of the compound. As the vapor
contacts the heated substrate surface, it decomposes and forms a
metal or metal carbide film As described above, an organometallic
compound precursor can be used alone or in combination with one or
more components, such as, for example, other organometallic
precursors, inert carrier gases or reactive gases.
[0095] In a system that can be used in producing films by the
method of the invention, raw materials can be directed to a
gas-blending manifold to produce process gas that is supplied to a
deposition reactor, where film growth is conducted. Raw materials
include, but are not limited to, carrier gases, reactive gases,
purge gases, precursor, etch/clean gases, and others. Precise
control of the process gas composition is accomplished using
mass-flow controllers, valves, pressure transducers, and other
means, as known in the art. An exhaust manifold can convey gas
exiting the deposition reactor, as well as a bypass stream, to a
vacuum pump. An abatement system, downstream of the vacuum pump,
can be used to remove any hazardous materials from the exhaust gas.
The deposition system can be equipped with in-situ analysis system,
including a residual gas analyzer, which permits measurement of the
process gas composition. A control and data acquisition system can
monitor the various process parameters (e.g., temperature,
pressure, flow rate, etc.).
[0096] The organometallic compound precursors described above can
be employed to produce films that include a single metal or a film
that includes a single metal carbide. Mixed films also can be
deposited, for instance mixed metal carbide films. Such films are
produced, for example, by employing several organometallic
precursors. Metal films also can be formed, for example, by using
no carrier gas, vapor or other sources of oxygen.
[0097] Films formed by the methods described herein can be
characterized by techniques known in the art, for instance, by
X-ray diffraction, Auger spectroscopy, X-ray photoelectron emission
spectroscopy, atomic force microscopy, scanning electron
microscopy, and other techniques known in the art. Resistivity and
thermal stability of the films also can be measured, by methods
known in the art.
[0098] In addition to their use in semiconductor applications as
chemical vapor or atomic layer deposition precursors for film
depositions, the organometallic compounds of this invention may
also be useful, for example, as catalysts, fuel additives and in
organic syntheses.
[0099] Various modifications and variations of this invention will
be obvious to a worker skilled in the art and it is to be
understood that such modifications and variations are to be
included within the purview of this application and the spirit and
scope of the claims.
EXAMPLE 1
[0100] The thin film deposition system used in this example is
described in detail in J. Atwood, D. C. Hoth, D. A. Moreno, C. A.
Hoover, S. H. Meiere, D. M. Thompson, G. B. Piotrowski, M. M.
Litwin, J. Peck, Electrochemical Society Proceedings 2003-08,
(2003) 847. Cp.sub.2TaH.sub.3 was sublimed at 90.degree. C. using
100 sccm of argon in a flow cell vaporizer at 50 Torr. The
precursor/argon mixture was combined with additional argon to form
the process gas mixture. Thin films were generated using a pulsed
process, consisting of 4 steps. The substrate (typically 3 inch
SiO.sub.2 wafer) was exposed to the process gas mixture at 5 Torr
and from 350 to 450.degree. C. In step 1, the process gas mixture
contained the precursor (Cp.sub.2TaH.sub.3). After exposing the
substrate to the mixture of precursor and argon for a specified
period of time (typically 10 seconds), the flow of precursor was
interrupted and the reactor was purged using argon. The purge step
(step 2) was typically conducted for 20 seconds. During step 3
(typically 10 seconds), the substrate was exposed to a mixture of
hydrogen and argon, in the presence of a plasma discharge. The
plasma was generated using a capacitively coupled RF configuration.
Between 20 and 160 Watts of forward power was applied to generate
the plasma. In step 4 (typically 20 seconds), the reactor was again
purged with argon. This pulsed process was repeated until the
desired thickness of Ta containing film was deposited.
[0101] A silicon dioxide wafer was used as the substrate at
362.degree. C. A plasma enhanced ALD (PEALD) process with timing of
10/20/10/20 seconds was repeated for 50 cycles to grow a tantalum
containing film that measured four nanometers by elipsometry.
Thicker films can be grown by increasing the number of cycles.
EXAMPLE 2
[0102] In order to prevent THF from reacting with the tantalum
complex, sodium cyclopentadiene (NaCp) was first synthesized via a
THF free route. A slight excess of freshly cracked cyclopentadiene
dimer was reacted with sodium bistrimethylsilylamide in ether.
##STR00002##
[0103] The solid product was purified by filtration and rinsing
with ether. 1 equivalent of tantalum pentachloride (TaCl.sub.5) was
added to a solution of three equivalents of NaCp and three
equivalents of the reducing agent Vitride.RTM. (commercially
available from Sigma Aldrich) in dimethoxy ethane (DME). The
solution was heated to reflux for four hours and then the solvent
was replaced with toluene.
##STR00003##
[0104] The reaction was cooled to 0.degree. C. and one equivalent
of distilled, degassed water was added. This is followed by one
equivalent of 15% sodium hydroxide solution and three equivalents
of water.
##STR00004##
[0105] The reaction was then heated to reflux for an hour and
allowed to cool. The reaction mixture was filtered through a pad of
magnesium sulfate to remove excess water and the solvent was
removed under reduced pressure. The solid was washed two to three
times with pentane to yield a slightly off white solid. The solid
was characterized by NMR in C.sub.6D.sub.6. We observed a single
peak at 4.8 for the Cp resonance and a triplet and a doublet at 1.6
and 2.9 for the hydride resonances. At this point, sublimation can
be performed at 100.degree. C. and 10.sup.-2 torr for further
purification. Further purification is not necessary for the
deposition method described above as the chemical delivery is a
sublimation.
* * * * *