U.S. patent application number 09/943478 was filed with the patent office on 2002-02-07 for metal complexes with chelating c-, n-donor ligands for forming metal-containing films.
This patent application is currently assigned to Micron Technology, Inc.. Invention is credited to Uhlenbrock, Stefan, Vaartstra, Brian A..
Application Number | 20020016065 09/943478 |
Document ID | / |
Family ID | 22510714 |
Filed Date | 2002-02-07 |
United States Patent
Application |
20020016065 |
Kind Code |
A1 |
Uhlenbrock, Stefan ; et
al. |
February 7, 2002 |
Metal complexes with chelating C-, N-donor ligands for forming
metal-containing films
Abstract
A method of forming a film on a substrate using transition metal
or lanthanide complexes. The complexes and methods are particularly
suitable for the preparation of semiconductor structures using
chemical vapor deposition techniques and systems.
Inventors: |
Uhlenbrock, Stefan; (Boise,
ID) ; Vaartstra, Brian A.; (Nampa, ID) |
Correspondence
Address: |
MUETING, RAASCH & GEBHARDT, P.A.
P.O. BOX 581415
MINNEAPOLIS
MN
55401
US
|
Assignee: |
Micron Technology, Inc.
|
Family ID: |
22510714 |
Appl. No.: |
09/943478 |
Filed: |
August 30, 2001 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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09943478 |
Aug 30, 2001 |
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09650601 |
Aug 30, 2000 |
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6306217 |
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09650601 |
Aug 30, 2000 |
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09144912 |
Sep 1, 1998 |
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6214729 |
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Current U.S.
Class: |
438/682 ;
118/715; 438/681 |
Current CPC
Class: |
C23C 16/18 20130101 |
Class at
Publication: |
438/682 ;
118/715; 438/681 |
International
Class: |
H01L 021/44 |
Claims
What is claimed is:
1. A method of manufacturing a semiconductor structure, the method
comprising: providing a semiconductor substrate or substrate
assembly; providing a precursor composition comprising one or more
complexes of the formula: 5 wherein: M is a transition metal; each
R group is independently H, a hydrocarbyl group, a halogenated
hydrocarbyl group, a halide, or a silylated hydrocarbyl group, with
the proviso that R.sup.3 and R.sup.4 are not both H and optionally
the R groups are replaced by multiple bonds between atoms; each L
group is independently H, a hydrocarbyl group, a halogenated
hydrocarbyl group, a silylated hydrocarbyl group, or a halide; x=1
to 3; n=0 to 4; y=0 to 4; and forming a metal-containing film from
the precursor composition on a surface of the semiconductor
substrate or substrate assembly.
2. The method of claim 1 wherein the step of forming a
metal-containing film comprises vaporizing the precursor
composition and directing it toward the semiconductor substrate or
substrate assembly using a chemical vapor deposition technique.
3. The method of claim 2 wherein the chemical vapor deposition
technique comprises flash vaporization, bubbling, microdroplet
formation, or combinations thereof.
4. The method of claim 1 wherein the semiconductor substrate is a
silicon wafer.
5. The method of claim 1 wherein M is selected from the group
consisting of Co, Rh, Ir, Fe, Ru, Os, Ni, Pd, and Pt.
6. The method of claim 1 wherein each R.sup.3 and R.sup.4 is a
methyl group.
7. The method of claim 6 wherein each R.sup.1, R.sup.2, R.sup.5,
and R.sup.6 is hydrogen and each R.sup.7 and R.sup.8 is a methyl
group.
8. The method of claim 6 wherein each R.sup.1 and R.sup.2 is
SiMe.sub.3, each R.sup.5 and R.sup.6 is hydrogen, and each R.sup.7
and R.sup.8 is a methyl group.
9. The method of claim 1 wherein the precursor composition
comprises one or more complexes of the formula: 6
10. The method of claim 1 wherein the precursor composition is a
liquid.
11. The method of claim 1 wherein the precursor composition is
vaporized in the presence of a reaction gas, an inert carrier gas,
or a combination thereof.
12. The method of claim 11 wherein the reaction gas is SiH.sub.4,
Si.sub.2H.sub.6, NH.sub.3, N.sub.2H.sub.4, PH.sub.3, AsH.sub.3,
GeH.sub.4, t-BuSbMe.sub.2, H.sub.2S, H.sub.2Se, CO, and CH.sub.4,
and Te(allyl).sub.2.
13. The method of claim 1 wherein the metal containing film is a
single transition metal or a transition metal alloy film.
14. A method of manufacturing a semiconductor structure, the method
comprising: providing a semiconductor substrate or substrate
assembly; providing a precursor composition comprising one or more
organic solvents and one or more complexes of the formula: 7
wherein: M is a transition metal; each R group is independently H,
a hydrocarbyl group, a halogenated hydrocarbyl group, a halide, or
a silylated hydrocarbyl group, with the proviso that R.sup.3 and
R.sup.4 are not both H and optionally the R groups are replaced by
multiple bonds between atoms; each L group is independently H, a
hydrocarbyl group, a halogenated hydrocarbyl group, a silylated
hydrocarbyl group, or a halide; x=1 to 3; n=0 to 4; y=0 to 4; and
vaporizing the precursor composition to form vaporized precursor
composition; and directing the vaporized precursor composition
toward the semiconductor substrate or substrate assembly to form a
metal-containing film on a surface of the semiconductor substrate
or substrate assembly.
15. A method of forming a film on a substrate, the method
comprising: providing a substrate; providing a precursor
composition comprising one or more complexes of the formula: 8
wherein: M is a transition metal; each R group is independently H,
a hydrocarbyl group, a halogenated hydrocarbyl group, a halide, or
a silylated hydrocarbyl group, with the proviso that R.sup.3 and
R.sup.4 are not both H and optionally the R groups are replaced by
multiple bonds between atoms; each L group is independently H, a
hydrocarbyl group, a halogenated hydrocarbyl group, a silylated
hydrocarbyl group, or a halide; x=1 to 3; n=0 to 4; y=0 to 4; and
forming a metal-containing film from the precursor composition on a
surface of the substrate.
16. The method of claim 15 wherein the step of forming a
metal-containing film comprises vaporizing the precursor
composition and directing it toward the substrate using a chemical
vapor deposition technique.
17. The method of claim 16 wherein the precursor composition is a
liquid.
18. A method of forming a film on a substrate, the method
comprising: providing a substrate; providing a precursor
composition comprising one or more organic solvents and one or more
complexes of the formula: 9 wherein: M is a transition metal; each
R group is independently H, a hydrocarbyl group, a halogenated
hydrocarbyl group, a halide, or a silylated hydrocarbyl group, with
the proviso that R.sup.3 and R.sup.4 are not both H and optionally
the R groups are replaced by multiple bonds between atoms; each L
group is independently H, a hydrocarbyl group, a halogenated
hydrocarbyl group, a silylated hydrocarbyl group, or a halide; x=1
to 3; n=0 to 4; y=0 to 4; and vaporizing the precursor composition
to form vaporized precursor composition; and directing the
vaporized precursor composition toward the substrate to form a
metal-containing film on a surface of the substrate.
19. A chemical vapor deposition system comprising: a deposition
chamber having a substrate positioned therein; a vessel containing
a precursor composition comprising one or more complexes of the
formula: 10 wherein: M is a transition metal; each R group is
independently H, a hydrocarbyl group, a halogenated hydrocarbyl
group, a halide, or a silylated hydrocarbyl group, with the proviso
that R.sup.3 and R.sup.4 are not both H and optionally the R groups
are replaced by multiple bonds between atoms; each L group is
independently H, a hydrocarbyl group, a halogenated hydrocarbyl
group, a silylated hydrocarbyl group, or a halide; x=1 to 3; n=0 to
4; y=0 to 4; and a source of an inert carrier gas for transferring
the precursor composition to the chemical vapor deposition
chamber.
20. A precursor composition comprising one or more complexes of the
formula: 11wherein: M is a transition metal; each R group is
independently H, a hydrocarbyl group, a halogenated hydrocarbyl
group, a halide, or a silylated hydrocarbyl group, with the proviso
that R.sup.3 and R.sup.4 are not both H and optionally the R groups
are replaced by multiple bonds between atoms; each L group is
independently H, a hydrocarbyl group, a halogenated hydrocarbyl
group, a silylated hydrocarbyl group, or a halide; x=1 to 3; n=0 to
4; y=0 to 4; and further wherein the precursor composition includes
at least two complexes containing different metals.
21. The precursor composition of claim 20 wherein M is selected
from the group consisting of Co, Rh, Ir, Fe, Ru, Os, Ni, Pd, and
Pt.
22. The precursor composition of claim 20 wherein each R.sup.3 and
R.sup.4 is a methyl group.
23. The precursor composition of claim 22 wherein each R.sup.1,
R.sup.2, R.sup.5, and R.sup.6 is hydrogen and each R.sup.7 and
R.sup.8 is a methyl group.
24. The precursor composition of claim 22 wherein each R.sup.1 and
R.sup.2 is SiMe.sub.3, each R.sup.5 and R.sup.6 is hydrogen, and
each R.sup.7 and R.sup.8 is a methyl group.
25. The precursor composition of claim 20 which is a liquid.
26. The precursor composition of claim 20 comprising one or more
complexes of the formula: 12
27. The precursor composition of claim 26 wherein M is selected
from the group consisting of Co, Rh, Ir, Fe, Ru, Os, Ni, Pd, and
Pt.
28. The precursor composition of claim 26 wherein each R.sup.1 and
R.sup.2 is SiMe.sub.3.
Description
FIELD OF THE INVENTION
[0001] This invention relates to methods and complexes for forming
metal-containing films, such as metal or metal alloy films,
particularly during the manufacture of semiconductor device
structures. The complexes include a transition metal, particularly
a Group VIIIB metal, and are particularly suitable for use in a
chemical vapor deposition system.
BACKGROUND OF THE INVENTION
[0002] The future of microelectronic devices will depend on new
designs and new materials having superior properties. Metals like
cobalt, and compounds like cobalt silicide, are useful candidates
for use in memory devices. Cobalt silicide (CoSi.sub.2) shows
advantages over the currently used tungsten silicide (WSi.sub.2)
due to its lower polycrystalline film resistivity (about 15
.mu..OMEGA.-cm for CoSi.sub.2 compared to about 70 .mu..OMEGA.-cm
for WSi.sub.2). Furthermore, CoSi.sub.2 shows good thermal and
chemical stability.
[0003] In some applications, metal films are deposited using
sputtering techniques; however, sputtered metal is not typically
effective at filling contacts or vias because of shoulders or
overhangs that form at the contact openings. These overhangs can
lead to the formation of keyhole-shaped voids. Various collimation
techniques help reduce this problem, but typically not enough to
enable complete filling of very small geometries (e.g., less than
about 0.5 .mu.m). Therefore, it is desirable to use chemical vapor
deposition (CVD) to form metal and metal alloy films.
[0004] The desirability of CVD processes depend on the availability
of suitable precursor complexes. Many precursor complexes are
unsuitable because of their toxicity, pyrophoricity, poor
volatility, and thermal instability. Thus, there is a continuing
need for methods and precursor complexes for the deposition of
metal films (including metal alloy films), on semiconductor
structures, particularly using vapor deposition processes.
SUMMARY OF THE INVENTION
[0005] The present invention provides complexes and methods for
forming metal-containing films, particularly transition metals
(i.e., Groups IB through VIIIB, also referred to as Groups 3-12),
on substrates, such as semiconductor substrates or substrate
assemblies during the manufacture of semiconductor structures. The
methods involve forming a metal-containing film using a transition
metal complex. The metal-containing film can be used in various
metallization layers, particularly in multilevel interconnects, in
integrated circuit structures.
[0006] The metal-containing film can include a single transition
metal, or a metal alloy containing a mixture of transition metals,
or a transition metal and one or more metals or metalloids from
other groups in the Periodic Chart, such as Si, Ge, Sn, Pb, Bi,
etc. Furthermore, for certain preferred embodiments, the
metal-containing film can be a carbide, nitride, phosphide,
arsenide, stibnide, sulfide, selenide, telluride, or combinations
thereof.
[0007] Thus, in the context of the present invention, the term
"metal-containing film" includes, for example, relatively pure
films of cobalt, rhodium, iridium, nickel, palladium, platinum,
iron, ruthenium, and osmium, for example, alloys of these metals
(or other transition metals) with or without other metals or
metalloids (e.g., Si), or mixtures thereof. The term also includes
complexes of metals or metal alloys with other elements (e.g., C,
N, P, As, Sb, S, Se, and Te). The terms "single transition metal
film" or "single metal film" refer to relatively pure films of
single transition metals, for example. The terms "transition metal
alloy film" or "metal alloy film" refer to films of the transition
metals in alloys with or without other metals or metalloids, for
example. That is, if there are no metals or metalloids from groups
in the Periodic Chart other than transition metals, the alloy films
contain combinations of the transition metals.
[0008] One preferred method of the present invention involves
forming a film on a substrate, such as a semiconductor substrate or
substrate assembly during the manufacture of a semiconductor
structure, by: providing a substrate (preferably, a semiconductor
substrate or substrate assembly); providing a precursor composition
comprising one or more complexes of the formula: 1
[0009] wherein: M is a transition metal (also referred to as metals
of Groups IB through VIIIB or 3-12); each R group is independently
H, a hydrocarbyl group, a halogenated hydrocarbyl group, a halide,
or a silylated hydrocarbyl group, with the proviso that R.sup.3 and
R.sup.4 are not both H (preferably, neither is H); each L group is
independently H, a hydrocarbyl group, a halogenated hydrocarbyl
group, a silylated hydrocarbyl group, or a halide; x=1 to 3; n=0 to
4; y=0 to 4; and forming a metal-containing film from the precursor
composition on a surface of the substrate (preferably, the
semiconductor substrate or substrate assembly). The
metal-containing film can be a single transition metal film or a
transition metal alloy film. Using such methods, the complexes of
Formula I are converted in some manner (e.g., decomposed thermally)
and deposited on a surface to form a metal-containing film. Thus,
the film is not simply a film of the complex of Formula I.
[0010] Complexes of Formula I are neutral complexes and may be
liquids or solids at room temperature. If they are solids, they are
preferably sufficiently soluble in an organic solvent or have
melting points below their decomposition temperatures such that
they can be used in flash vaporization, bubbling, microdroplet
formation techniques, etc., or combinations thereof. However, they
may also be sufficiently volatile that they can be vaporized or
sublimed from the solid state using known chemical vapor deposition
techniques. Thus, the precursor compositions of the present
invention can be in solid or liquid form. 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, a "solution" does not require
complete solubility of the solid; rather, the solution may have
some undissolved material, preferably, however, there is a
sufficient amount of the material that can be carried by the
organic solvent into the vapor phase for chemical vapor deposition
processing.
[0011] Yet another method of forming a metal-containing film on a
substrate, such as a semiconductor substrate or substrate assembly
during the manufacture of a semiconductor structure, involves:
providing a substrate (preferably, a semiconductor substrate or
substrate assembly); providing a precursor composition comprising
one or more organic solvents and one or more precursor complexes of
Formula I as defined above; vaporizing the precursor composition to
form vaporized precursor composition; and directing the vaporized
precursor composition toward the substrate to form a
metal-containing film on a surface of the substrate. Herein,
vaporized precursor composition includes vaporized molecules of
precursor complexes of Formula I either alone or optionally with
vaporized molecules of other compounds in the precursor
composition, including solvent molecules, if used.
[0012] Preferred embodiments of the methods of the present
invention involve the use of one or more chemical vapor deposition
techniques, although this is not necessarily required. That is, for
certain embodiments, sputtering, spin-on coating, etc., can be
used.
[0013] Methods of the present invention are particularly well
suited for forming films on a surface of a semiconductor substrate
or substrate assembly, such as a silicon wafer, with or without
layers or structures formed thereon, used in forming integrated
circuits. It is to be understood that methods of the present
invention are not limited to deposition on silicon wafers; rather,
other types of wafers (e.g., gallium arsenide wafer, etc.) can be
used as well. Also, methods of the present invention can be used in
silicon-on-insulator technology. Furthermore, substrates other than
semiconductor substrates or substrate assemblies can be used in
methods of the present invention. These include, for example,
fibers, wires, etc. If the substrate is a semiconductor substrate
or substrate assembly, the films can be formed directly on the
lowest semiconductor surface of the substrate, or they can be
formed on any of a variety of the layers (i.e., surfaces) as in a
patterned wafer, for example. Thus, the term "semiconductor
substrate" refers to the base semiconductor layer, e.g., the lowest
layer of silicon material in a wafer or a silicon layer deposited
on another material such as silicon on sapphire. The term
"semiconductor substrate assembly" refers to the semiconductor
substrate having one or more layers or structures formed
thereon.
[0014] A chemical vapor deposition system is also provided. The
system includes a deposition chamber having a substrate positioned
therein; a vessel containing a precursor composition comprising one
or more complexes of Formula I as described above; and a source of
an inert carrier gas for transferring the precursor composition to
the chemical vapor deposition chamber.
[0015] The present invention further provides precursor
compositions containing one or more complexes of Formula I wherein
the compositions include at least two complexes containing
different metals.
BRIEF DESCRIPTION OF THE DRAWINGS
[0016] FIG. 1 is a schematic of a chemical vapor deposition system
suitable for use in a method of the present invention.
[0017] FIG. 2 is a schematic of an alternative chemical vapor
deposition system suitable for use in a method of the present
invention.
[0018] FIG. 3 is a schematic of a gate structure with a
metal-containing film deposited in accordance with the method of
the present invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0019] The present invention provides a method of forming a
metal-containing film using one or more transition metal complexes.
These complexes are typically mononuclear (i.e., monomers in that
they contain one metal per molecule), although they can be in the
form of weakly bound dimers (i.e., dimers containing two monomers
weakly bonded together through hydrogen or dative bonds). Herein,
such monomers and weakly bound dimers are shown as mononuclear
complexes.
[0020] The complexes of Formula I are neutral complexes and may be
liquids or solids at room temperature. If they are solids, they are
sufficiently soluble in an organic solvent to allow for
vaporization, they can be vaporized or sublimed from the solid
state, or they have melting temperatures below their decomposition
temperatures. Thus, many of the complexes described herein are
suitable for use in chemical vapor deposition (CVD) techniques,
such as flash vaporization techniques, bubbler techniques, and/or
microdroplet techniques. Preferred embodiments of the complexes
described herein are particularly suitable for low temperature CVD,
e.g., deposition techniques involving vaporization temperatures of
about 50.degree. C. to about 300.degree. C.
[0021] The solvents that are suitable for this application can be
one or more of the following: aliphatic hydrocarbons or unsaturated
hydrocarbons (C.sub.3-C.sub.20, and preferably C.sub.5-C.sub.10,
cyclic, branched, or linear), aromatic hydrocarbons
(C.sub.5-C.sub.20, and preferably C.sub.5-C.sub.10) halogenated
hydrocarbons, silylated hydrocarbons such as alkylsilanes,
alkylsilicates, ethers, polyethers, thioethers, esters, lactones,
ammonia, amides, amines (aliphatic or aromatic, primary, secondary,
or tertiary), polyamines, nitrites, cyanates, isocyanates,
thiocyanates, silicone oils, aldehydes, ketones, diketones,
carboxylic acids, water, alcohols, thiols, or compounds containing
combinations of any of the above or mixtures of one or more of the
above. It should be noted that some precursor compositions are
sensitive to reactions with protic solvents, and examples of these
noted above may not be ideal, depending on the nature of the
precursor complexes. The complexes are also generally compatible
with each other, so that mixtures of variable quantities of the
complexes will not interact to significantly change their physical
properties.
[0022] One preferred method of the present invention involves
vaporizing a precursor composition that includes one or more
transition metal complexes. Also, the precursor composition can
include complexes containing other metals or metalloids.
Furthermore, the precursor composition can include one or more
organic solvents.
[0023] The precursor composition can be vaporized in the presence
of an inert carrier gas to form a relatively pure metal or metal
alloy film. The inert carrier gas is typically selected from the
group consisting of nitrogen, helium, argon, and mixtures thereof.
In the context of the present invention, an inert carrier gas is
one that is generally unreactive with the complexes described
herein and does not interfere with the formation of a
metal-containing film. Whether done in the presence of a carrier
gas or not, the vaporization is preferably done in the absence of
oxygen to avoid oxygen contamination of the films.
[0024] Alternatively, however, the precursor composition can be
vaporized in the presence of a reaction gas to form a film. The
reaction gas can be selected from a wide variety of gases reactive
with the complexes described herein, at least at a surface under
the conditions of chemical vapor deposition. Examples of reaction
gases include SiH.sub.4, Si.sub.2H.sub.6, NH.sub.3, N.sub.2H.sub.4,
PH.sub.3, AsH.sub.3, GeH.sub.4, t-BuSbMe.sub.2, H.sub.2S,
H.sub.2Se, CO, CH.sub.4, and Te(allyl).sub.2. Various combinations
of carrier gases and/or reaction gases can be used in the methods
of the present invention to form metal-containing films. Thus, the
metal-containing film can include a carbide, nitride, phosphide,
arsenide, stibnide, sulfide, selenide, telluride, or combinations
thereof, for example. Such films can also be formed by initially
forming a generally pure metal or metal alloy film and subsequently
subjecting it to a process such as silicidation. A film can be
deposited in a wide variety of thicknesses, depending on the
desired use.
[0025] The transition metal complexes described herein are three to
six coordinate complexes having one to three multidentate ligands.
The ligand typically has one carbon atom that covalently bonds to
the metal and one nitrogen atom that forms a dative bond with the
metal. The multidentate ligand stabilizes the metal complex by
incorporating the nitrogen donor atom into the ligand (chelate
effect). This eliminates the problem of dissociation of simple
donor ligands prior to thermal decomposition.
[0026] The transition metal complex is of the following formula,
which is shown as a monomer, although weakly bound dimers are also
possible: 2
[0027] wherein: M is a transition metal (i.e., a metal of Groups IB
through VIIIB or 3-12, preferably, M is Co, Rh, Ir, Fe, Ru, Os, Ni,
Pd, or Pt); each R group is independently H, a hydrocarbyl group, a
halogenated hydrocarbyl group, a halide, or a silylated hydrocarbyl
group, with the proviso that R.sup.3 and R.sup.4 are not both H
(preferably, neither is H); each L group is independently H, a
hydrocarbyl group, a halogenated hydrocarbyl group, a silylated
hydrocarbyl group, or a halide; x=1 to 3 (preferably, 2 or 3); n=0
to 4 (preferably, 1 or 2); y=0 to 4 (preferably, 0); and forming a
metal-containing film from the precursor composition on a surface
of the substrate (preferably, the semiconductor substrate or
substrate assembly).
[0028] The ligand
(C(R.sup.1)(R.sup.2))(C(R.sup.3)(R.sup.4))(C(R.sup.5)(R.-
sup.6)).sub.nN(R.sup.7)(R.sup.8) is typically bound to the central
metal through the N(R.sup.7)(R.sup.8) unit and the
C(R.sup.1)(R.sup.2) unit. The R groups on the carbon and nitrogen
atoms can be joined together to form a ring or rings, including
aromatic and heterocyclic rings. Furthermore, any of the R groups
can be replaced by multiple bonds between atoms in the ligand
backbone. Thus, the core structure of Formula I is represented by:
3
[0029] As used herein, the term "hydrocarbyl group" means an
organic hydrocarbon group that is classified as an aliphatic group,
cyclic group, or combination of aliphatic and cyclic groups (e.g.,
alkaryl and aralkyl groups). In the context of the present
invention, the organic groups are those that do not interfere with
the formation of a metal-containing film. Preferably, they are of a
type and size that do not interfere with the formation of a
metal-containing film using chemical vapor deposition techniques.
The term "aliphatic group" means a saturated or unsaturated linear
or branched hydrocarbon group. This term is used to encompass
alkyl, alkenyl, and alkynyl groups, for example. The term "alkyl
group" means a saturated linear or branched hydrocarbon group
including, for example, methyl, ethyl, isopropyl, t-butyl, heptyl,
dodecyl, octadecyl, amyl, 2-ethylhexyl, and the like. The term
"alkenyl group" means an unsaturated, linear or branched
hydrocarbon group with one or more carbon-carbon double bonds, such
as a vinyl group. The term "alkynyl group" means an unsaturated,
linear or branched hydrocarbon group with one or more carbon-carbon
triple bonds. The term "cyclic group" means a closed ring
hydrocarbon group that is classified as an alicyclic group,
aromatic group, or heterocyclic group. The term "alicyclic group"
means a cyclic hydrocarbon group having properties resembling those
of aliphatic groups. The term "aromatic group" or "aryl group"
means a mono- or polynuclear aromatic hydrocarbon group. The term
"hydrocarbyl group" does not include substitution, however, the
hydrocarbyl groups may be substituted with halogen or silicon
atoms, thereby forming "halogenated hydrocarbyl groups" and
"silylated hydrocarbyl groups," respectively.
[0030] The R groups can be joined to form a ring or rings, which
may or may not have unsaturation, including aromaticity. They may
also be replaced by multiple bonds between atoms in the core
structure. Preferred R groups (R.sup.1, R.sup.2, R.sup.3, R.sup.4,
R.sup.5, R.sup.6, R.sup.7, and R.sup.8) in the complexes of Formula
I include H, (C.sub.1-C.sub.30)hydrocarbyl groups, halogenated
(C.sub.1-C.sub.30)hydro- carbyl groups, halides (F, Cl, Br, and I),
and tri(C.sub.1-C.sub.5)alkysil- yl groups. More preferred R groups
include H, (C.sub.1-C.sub.20)hydrocarby- l groups, halogenated
(C.sub.1-C.sub.20)hydrocarbyl groups, halides, and
tri(C.sub.1-C.sub.5)alkysilyl groups. Most preferred R groups
include H, (C.sub.1-C.sub.8)hydrocarbyl groups, halogenated
(C.sub.1-C.sub.8)hydroca- rbyl groups, halides, and
tri(C.sub.1-C.sub.5)alkysilyl groups. Of the halides, F and Cl are
preferred. The R.sup.3 and R.sup.4 groups are not both hydrogen,
and preferably, neither is hydrogen, due to the instability of such
complexes. Preferably, the R.sup.1, R.sup.2, R.sup.5, R.sup.6,
R.sup.7, and R.sup.8 groups are independently H, hydrocarbyl groups
(nonhalogenated), halogenated hydrocarbyl groups, and silylated
hydrocarbyl groups, and the R.sup.3 and R.sup.4 groups are
independently hydrocarbyl groups (nonhalogenated), halogenated
hydrocarbyl groups, halides, and silylated hydrocarbyl groups. In
particularly preferred embodiments, the R.sup.3, R.sup.4, R.sup.7,
and R.sup.8 groups are methyl groups, the R.sup.5 and R.sup.6
groups are hydrogen, and the R.sup.1 and R.sup.2 groups are
hydrogen or SiMe.sub.3.
[0031] Preferred L groups in the complexes of Formula I include H,
(C.sub.1-C.sub.30) hydrocarbyl groups,
halogenated(C.sub.1-C.sub.30)hydro- carbyl groups,
silylated(C.sub.1-C.sub.30) hydrocarbyl groups, and halides (F, Cl,
Br, and I). More preferred L groups include H,
(C.sub.1-C.sub.20)hydrocarbyl groups,
halogenated(C.sub.1-C.sub.20)hydroc- arbyl groups,
silylated(C.sub.1-C.sub.20)hydrocarbyl groups, and halides. Most
preferred L groups include H, (C.sub.1-C.sub.8)hydrocarbyl groups,
halogenated(C.sub.1-C.sub.8)hydrocarbyl groups,
silylated(C.sub.1-C.sub.8- ) hydrocarbyl groups, and halides. Of
the halides for the L groups, F and Cl are preferred.
[0032] A preferred class of complexes of Formula I include
complexes containing 2 or 3 of the chelating ligands and no L
groups. This class of complexes of Formula I is particularly
advantageous because they are most likely to be mononuclear and
volatile.
[0033] The complexes of Formula I can take the following forms
(which are representative only): 4
[0034] In the first of these two formulas, n=0, y=0, x=2, and
R.sup.3 and R.sup.4 represent the same group as do R.sup.7 and
R.sup.8, which are bonded together to form a ring.
[0035] As stated above, the complexes of Formula I are neutral
complexes and may be liquids or solids at room temperature. If they
are solids, they are preferably sufficiently soluble in an organic
solvent to allow for vaporization by flash vaporization, bubbling,
microdroplet formation, etc. However, these complexes can also be
vaporized or sublimed from the solid state using known chemical
vapor deposition techniques.
[0036] Various combinations of the complexes described herein can
be used in a precursor composition. Thus, as used herein, a
"precursor composition" refers to a liquid or solid that includes
one or more complexes of the formulas described herein optionally
mixed with one or more complexes of formulas other than those of
Formula I. The precursor composition can also include one or more
organic solvents suitable for use in a chemical vapor deposition
system, as well as other additives, such as free ligands, that
assist in the vaporization of the desired compounds.
[0037] The complexes described herein can be used in precursor
compositions for chemical vapor deposition. Alternatively, certain
complexes described herein can be used in other deposition
techniques, such as sputtering, spin-on coating, and the like.
Typically, those complexes containing R groups with a low number of
carbon atoms (e.g., 1-4 carbon atoms per R group) are suitable for
use with vapor deposition techniques. Those complexes containing R
groups with a higher number of carbon atoms (e.g., 5-12 carbon
atoms per R group) are generally suitable for spin-on or dip
coating. Preferably, however, chemical vapor deposition techniques
are desired because they are more suitable for deposition on
semiconductor substrates or substrate assemblies, particularly in
contact openings which are extremely small and require conformally
filled layers of metal.
[0038] For the preparation of alloy films, two or more complexes of
Formula I can be combined in a precursor composition (e.g.,
Co(CH.sub.2CMe.sub.2CH.sub.2NMe.sub.2).sub.2 wherein the nitrogen
atom is also bonded to the cobalt, and
RhCl(CH.sub.2CMe.sub.2CH.sub.2NMe.sub.2).s- ub.2 wherein the
nitrogen atom is also bonded to the rhodium for a Co/Rh alloy).
Alternatively, at least one complex of Formula I can be combined
with another complex in a precursor composition
(e.g.,Co(CH.sub.2CMe.sub.- 2CH.sub.2NMe.sub.2).sub.2 wherein the
nitrogen atom is also bonded to the cobalt, and Ir(allyl).sub.3 for
a Co/Ir alloy).
[0039] The complexes used in the present invention can be prepared
by a variety of methods known to one of skill in the art. For
example, Co{C(SiMe.sub.3).sub.2(C.sub.5H.sub.4N)}.sub.2 wherein the
nitrogen atom is also bonded to the cobalt, can be prepared by the
method outlined in Leung et al., J. C. S. Dalton, 779 (1997).
[0040] Methods of the present invention can be used to deposit a
metal-containing film, preferably a metal or metal alloy film, on a
variety of substrates, such as a semiconductor wafer (e.g., silicon
wafer, gallium arsenide wafer, etc.), glass plate, etc., and on a
variety of surfaces of the substrates, whether it be directly on
the substrate itself or on a layer of material deposited on the
substrate as in a semiconductor substrate assembly. The film is
deposited upon decomposition (typically, thermal decomposition) of
a complex of Formula I, preferably one that is either a volatile
liquid, a sublimable solid, or a solid that is soluble in a
suitable solvent that is not detrimental to the substrate, other
layers thereon, etc. Preferably, however, solvents are not used;
rather, the transition metal complexes are liquid and used neat.
Methods of the present invention preferably utilize vapor
deposition techniques, such as flash vaporization, bubbling,
etc.
[0041] A typical chemical vapor deposition (CVD) system that can be
used to perform the process of the present invention is shown in
FIG. 1. The system includes an enclosed chemical vapor deposition
chamber 10, which may be a cold wall-type CVD reactor. As is
conventional, the CVD process may be carried out at pressures of
from atmospheric pressure down to about 10.sup.-3 torr, and
preferably from about 10 torr to about 0.1 torr. A vacuum may be
created in chamber 10 using turbo pump 12 and backing pump 14.
[0042] One or more substrates 16 (e.g., semiconductor substrates or
substrate assemblies) are positioned in chamber 10. A constant
nominal temperature is established for the substrate, preferably at
a temperature of about 100.degree. C. to about 600.degree. C., and
more preferably at a temperature of about 100.degree. C. to about
300.degree. C. Substrate 16 may be heated, for example, by an
electrical resistance heater 18 on which substrate 16 is mounted.
Other known methods of heating the substrate may also be
utilized.
[0043] In this process, the precursor composition 40, which
contains one or more complexes of Formula I (and/or other metal or
metalloid complexes), is stored in liquid form (a neat liquid at
room temperature or at an elevated temperature if solid at room
temperature) in vessel 42. A source 44 of a suitable inert gas is
pumped into vessel 42 and bubbled through the neat liquid (i.e.,
without solvent) picking up the precursor composition and carrying
it into chamber 10 through line 45 and gas distributor 46.
Additional inert carrier gas or reaction gas may be supplied from
source 48 as needed to provide the desired concentration of
precursor composition and regulate the uniformity of the deposition
across the surface of substrate 16. As shown, a series of valves
50-54 are opened and closed as required.
[0044] Generally, the precursor composition is pumped into the CVD
chamber 10 at a flow rate of about 1 sccm (standard cubic
centimeters) to about 1000 sccm. The semiconductor substrate is
exposed to the precursor composition at a pressure of about 0.001
torr to about 100 torr for a time of about 0.01 minute to about 100
minutes. In chamber 10, the precursor composition will form an
adsorbed layer on the surface of the substrate 16. As the
deposition rate is temperature dependent, increasing the
temperature of the substrate will increase the rate of deposition.
Typical deposition rates are about 10 Angstroms/minute to about
1000 Angstroms/minute. The carrier gas containing the precursor
composition is terminated by closing valve 53.
[0045] An alternative CVD system that can be used to perform the
process of the present invention is shown in FIG. 2. The system
includes an enclosed chemical vapor deposition chamber 110, which
may be a cold wall-type CVD reactor, in which a vacuum may be
created using turbo pump 112 and backing pump 114. One or more
substrates 116 (e.g., semiconductor substrates or substrate
assemblies) are positioned in chamber 110. Substrate 116 may be
heated as described with reference to FIG. 1 (for example, by an
electrical resistance heater 118).
[0046] In this process, one or more solutions 60 of one or more
precursor complexes of Formula I (and/or other metal or metalloid
complexes), are stored in vessels 62. The solutions are transferred
to a mixing manifold 64 using pumps 66. The resultant precursor
composition containing one or more precursor complexes and one or
more organic solvents is then transferred along line 68 to
vaporizer 70, to volatilize the precursor composition. A source 74
of a suitable inert gas is pumped into vaporizer 70 for carrying
volatilized precursor composition into chamber 110 through line 75
and gas distributor 76. Reaction gas may be supplied from source 78
as needed. As shown, a series of valves 80-85 are opened and closed
as required. Similar pressures and temperatures to those described
with reference to FIG. 1 can be used.
[0047] Alternatives to such methods include an approach wherein the
precursor composition is heated and vapors are drawn off and
controlled by a vapor mass flow controller, and a pulsed liquid
injection method as described in "Metalorganic Chemical Vapor
Deposition By Pulsed Liquid Injection Using An Ultrasonic Nozzle:
Titanium Dioxide on Sapphire from Titanium (IV) Isopropoxide," by
Versteeg, et al., Journal of the American Ceramic Society, 78,
2763-2768 (1995). The complexes of Formula I are also particularly
well suited for use with vapor deposition systems, as described in
copending application U.S. Ser. No. 08/720,710 entitled "Method and
Apparatus for Vaporizing Liquid Precursor compositions and System
for Using Same," filed on Oct. 2, 1996. Generally, one method
described therein involves the vaporization of a precursor
composition in liquid form (neat or solution). In a first stage,
the precursor composition is atomized or nebulized generating high
surface area microdroplets or mist. In a second stage, the
constituents of the microdroplets or mist are vaporized by intimate
mixture of the heated carrier gas. This two stage vaporization
approach provides a reproducible delivery for precursor
compositions (either in the form of a neat liquid or solid
dissolved in a liquid medium) and provides reasonable growth rates,
particularly in device applications with small dimensions.
[0048] Various combinations of carrier gases and/or reaction gases
can be used in certain methods of the present invention. They can
be introduced into the chemical vapor deposition chamber in a
variety of manners, such as directly into the vaporization chamber
or in combination with the precursor composition. Although specific
vapor deposition processes are described by reference to FIGS. 1-2,
methods of the present invention are not limited to being used with
the specific vapor deposition systems shown. Various CVD process
chambers or reaction chambers can be used, including hot wall or
cold wall reactors, atmospheric or reduced pressure reactors, as
well as plasma enhanced reactors. Furthermore, methods of the
present invention are not limited to any specific vapor deposition
techniques.
[0049] As stated above, the use of the complexes of Formula I and
methods of forming metal-containing films of the present invention
are beneficial for a wide variety of thin film applications in
semiconductor structures, particularly various metallization
layers. Such applications include multilevel interconnects in an
integrated circuit structure. Typically, thin films of Group VIII
metals, such as cobalt, and alloys thereof are deposited as
polycrystalline materials, usually in a range of about 20 Angstroms
to about 500 Angstroms thick.
[0050] As shown in FIG. 3, device structure 150 includes n-type
active areas 151 and 152, p-well 153 having field oxide regions 154
deposited thereon in accordance with conventional techniques, and
stacks 155 and 156, i.e., word lines. The stacks 155 and 156 may
include, for example, a gate oxide region 157, a polysilicon region
158, a metal silicide region 160 (such as, for example, cobalt
silicide formed in accordance with the present invention), and an
oxide region 162 (such as TEOS). Further, the stacks 155 and 156
include spacers 164 at the side walls thereof. The structure may
also include a cobalt silicide region 166 over the active n-type
region 152, other interconnect layers 167, 168, and 169 such as
titanium nitride, tungsten or any other interconnect material
typically deposited for interconnect functions. Thereafter, other
metallization layers 170, such as aluminum or any other metal
conventionally used may be deposited for connection to the bit line
contact as is known to one skilled in the art.
[0051] The following examples are offered to further illustrate the
various specific and preferred embodiments and techniques. It
should be understood, however, that many variations and
modifications may be made while remaining within the scope of the
present invention.
EXAMPLE
[0052] A 0.1 molar solution of
Co{C(SiMe.sub.3).sub.2(C.sub.5H.sub.4N)}.su- b.2 in THF (5.32 g in
100 mL) is delivered to a vaporizer (COVA Technologies, Inc.,
Colorado Spring, Colo.) using a syringe pump. From here the
vaporized precursor composition (vaporizer temperature 180.degree.
C.) is transferred via helium carrier gas (50 sccm) to the CVD
reactor containing the substrate. A cobalt film is deposited on
silicon substrate that is heated to 550.degree. C. Hydrogen is used
as a reactant gas (100 sccm) and the pressure inside the chamber is
1 Torr. Thicknesses of cobalt on the silicon substrate are
determined by the deposition time and the substrate
temperature.
[0053] The foregoing detailed description and examples have been
given for clarity of understanding only. No unnecessary limitations
are to be understood therefrom. The invention is not limited to the
exact details shown and described, for variations obvious to one
skilled in the art will be included within the invention defined by
the claims. The complete disclosures of all patents, patent
documents, and publications listed herein are incorporated by
reference, as if each were individually incorporated by
reference.
* * * * *