U.S. patent application number 17/225667 was filed with the patent office on 2021-12-09 for fluorine-free tungsten ald and tungsten selective cvd for dielectrics.
This patent application is currently assigned to Applied Materials, Inc.. The applicant listed for this patent is Applied Materials, Inc.. Invention is credited to Shih Chung Chen, Wen Ting Chen, Ilanit Fisher, Srinivas Gandikota, Yu Lei, Ashley Lin, Chi-Chou Lin, He Ren, Chenfei Shen, Mandyam Sriram, Kedi Wu, Yi Xu, Naomi Yoshida.
Application Number | 20210384035 17/225667 |
Document ID | / |
Family ID | 1000005610834 |
Filed Date | 2021-12-09 |
United States Patent
Application |
20210384035 |
Kind Code |
A1 |
Fisher; Ilanit ; et
al. |
December 9, 2021 |
Fluorine-Free Tungsten ALD And Tungsten Selective CVD For
Dielectrics
Abstract
Methods of forming metallic tungsten films selectively on a
conductive surface relative to a dielectric surface are described.
A substrate is exposed to a first process condition to deposit a
fluorine-free metallic tungsten film. The fluorine-free metallic
tungsten film is exposed to a second process condition to deposit a
tungsten film on the fluorine-free metallic tungsten film.
Inventors: |
Fisher; Ilanit; (San Jose,
CA) ; Chen; Shih Chung; (Cupertino, CA) ; Wu;
Kedi; (Fremont, CA) ; Lin; Ashley; (New
Taipei, TW) ; Lin; Chi-Chou; (San Jose, CA) ;
Xu; Yi; (San Jose, CA) ; Lei; Yu; (Belmont,
CA) ; Sriram; Mandyam; (San Jose, CA) ; Chen;
Wen Ting; (San Jose, CA) ; Gandikota; Srinivas;
(Santa Clara, CA) ; Shen; Chenfei; (San Jose,
CA) ; Yoshida; Naomi; (Sunnyvale, CA) ; Ren;
He; (San Jose, CA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Applied Materials, Inc. |
Santa Clara |
CA |
US |
|
|
Assignee: |
Applied Materials, Inc.
Santa Clara
CA
|
Family ID: |
1000005610834 |
Appl. No.: |
17/225667 |
Filed: |
April 8, 2021 |
Related U.S. Patent Documents
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
|
|
63034721 |
Jun 4, 2020 |
|
|
|
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
C23C 16/0227 20130101;
H01L 21/02068 20130101; H01L 21/28568 20130101; C23C 16/14
20130101 |
International
Class: |
H01L 21/285 20060101
H01L021/285; H01L 21/02 20060101 H01L021/02; C23C 16/14 20060101
C23C016/14; C23C 16/02 20060101 C23C016/02 |
Claims
1. A method comprising: exposing a substrate surface to a first
process condition comprising a flow of a fluorine-free tungsten
precursor and a flow of a first reducing agent to form a
fluorine-free metallic tungsten film on the substrate surface to a
first thickness; and exposing the fluorine-free metallic tungsten
film to a second process condition comprising a flow of a second
tungsten precursor to deposit a tungsten film.
2. The method of claim 1, wherein the fluorine-free tungsten
precursor comprises tungsten halides, tungsten hydrohalides,
tungsten oxyhalides or combinations thereof.
3. The method of claim 1, wherein the first reducing agent and the
second reducing agent independently comprises one or more of
hydrogen (H.sub.2), silane (SiH.sub.4), disilane (Si.sub.2H.sub.6),
trisilane (Si.sub.3H.sub.8), tetrasilane (Si.sub.4H.sub.10) or
ammonia (NH.sub.3).
4. The method of claim 1, wherein the fluorine-free tungsten
precursor has a flow rate in a range of from 100 sccm to 700
sccm.
5. The method of claim 1, wherein the fluorine-free tungsten
precursor further comprises a co-flown reducing agent, the co-flown
reducing agent has a flow rate in the range of 500 to 7000
sccm.
6. The method of claim 1, wherein the first process condition
comprises flowing the fluorine-free tungsten precursor and flowing
the first reducing agent at a pressure in a range of from 15 psi to
30 psi.
7. The method of claim 1, wherein the first thickness is in the
range of 20 .ANG. to 60 .ANG.
8. The method of claim 1 further comprising treating the
fluorine-free metallic tungsten film with a plasma.
9. The method of claim 8, wherein the plasma treatment causes
thermal reduction of the fluorine-free metallic tungsten film.
10. The method of claim 8, wherein the plasma is generated in a
range of from 100 W to 1500 W.
11. The method of claim 8, wherein the plasma treatment comprises
Hydrogen (H.sub.2) plasma treatment, Oxygen (O.sub.2) plasma
treatment, Argon (Ar) plasma treatment or combinations thereof.
12. The method of claim 1, wherein the second tungsten precursor
comprises a tungsten fluoride or derivative thereof.
13. The method of claim 1, wherein the second process condition
further comprises co-flowing a second reducing with the second
tungsten precursor, the second reducing agent comprises one or more
of hydrogen (H.sub.2), silane (SiH.sub.4), disilane
(Si.sub.2H.sub.6), trisilane (Si.sub.3H.sub.8), tetrasilane
(Si.sub.4H.sub.10) or ammonia (NH.sub.3).
14. The method of claim 1 further comprising pre-cleaning the
substrate surface before exposing to the first process condition,
the pre-cleaning comprises treating the substrate surface with a
plasma.
15. The method of claim 1, wherein one or more of the first process
condition, plasma treatment or the second process condition are
performed at a temperature in a range of from 15.degree. C. to
450.degree. C.
16. The method of claim 1, wherein the substrate surface has a
structure formed thereon having a bottom and sidewall, the bottom
of the structure comprising a conductive surface and the sidewall
of the structure comprising a dielectric surface.
17. The method of claim 16, wherein the fluorine-free metallic
tungsten film is deposited selectively on the bottom of the
structure relative to the sidewall of the structure, the structure
has an aspect ratio in a range of from 2:1 to 4:1.
18. The method of claim 16, wherein the dielectric surface
comprises one or more of a SiN.sub.x, SiO.sub.x, SiO.sub.xN.sub.y,
or combination thereof.
19. The method of claim 16, wherein the conductive surface
comprises TiN, TiAl, WC.sub.xN.sub.y, W or combination thereof.
20. A method comprising: exposing a substrate surface to a first
process condition comprising a flow of a fluorine-free tungsten
precursor and a flow of a first reducing agent to form a
fluorine-free metallic tungsten film on the substrate surface to a
first thickness; treating the fluorine free metallic tungsten film
with a plasma; and exposing the plasma treated fluorine-free
metallic tungsten film to a second process condition comprising a
flow of a second tungsten precursor to deposit a tungsten film.
Description
[0001] The present application claims the benefit of priorities to
U.S. Provisional Appl. No. 63/034,721, filed Jun. 4, 2020, which is
hereby incorporated by reference in its entirety.
TECHNICAL FIELD
[0002] Embodiments of the disclosure pertain to the field of
electronic device manufacturing, and in particular, to an
integrated circuit (IC) manufacturing. In particular, embodiments
of the disclosure pertain to methods for filling surface structures
with a metal containing film.
BACKGROUND
[0003] Integrated circuits are made possible by processes that
produce intricately patterned material layers on substrate
surfaces. Producing patterned material on a substrate requires
controlled methods for deposition of desired materials. Selectively
depositing a film on one surface relative to a different surface is
useful for patterning and other applications.
[0004] Conventional methods for metal deposition frequently suffer
from poor selectivity to dielectric surfaces. Additionally, single
wafer process environments can suffer from low throughput for
atomic layer deposition (ALD) processes.
[0005] In high-k metal gates with FINFET schemes, the features that
need to be filled are getting extremely small as the technology
node goes to 14 nm and below. Tungsten hexafluoride (WF.sub.6)
based chemical vapor deposition (CVD)/ALD tungsten films introduce
fluorine and cannot be directly deposited on the gate without a
barrier layer and a nucleation layer. As the dimensions of the
electronic devices shrinks, the barrier layer and nucleation layers
occupy most of volume in narrow feature. The high resistivities of
these films impact the performance of the resultant device.
[0006] Therefore, a need exists for improved methods for selective
metal deposition.
SUMMARY
[0007] One or more embodiments of the disclosure are directed to
methods for depositing a tungsten film. In some embodiments, the
method comprises exposing a substrate surface to a first process
condition comprising a flow of a fluorine-free tungsten precursor
and a flow of a first reducing agent to form a fluorine-free
metallic tungsten film on the substrate surface to a first
thickness, and exposing the fluorine-free metallic tungsten film to
a second process condition comprising a flow of a second tungsten
precursor to deposit a tungsten film.
[0008] In some embodiments, the method comprises exposing a
substrate surface to a first process condition comprising a flow of
a fluorine-free tungsten precursor and a flow of a first reducing
agent to form a fluorine-free metallic tungsten film on the
substrate surface to a first thickness, treating the fluorine free
metallic tungsten film with a plasma, and exposing the plasma
treated fluorine-free metallic tungsten film to a second process
condition comprising a flow of a second tungsten precursor to
deposit a tungsten film.
BRIEF DESCRIPTION OF THE DRAWINGS
[0009] So that the manner in which the above recited features of
the present disclosure can be understood in detail, a more
particular description of the disclosure, briefly summarized above,
may be had by reference to embodiments, some of which are
illustrated in the appended drawings. It is to be noted, however,
that the appended drawings illustrate only typical embodiments of
this disclosure and are therefore not to be considered limiting of
its scope, for the disclosure may admit to other equally effective
embodiments. The embodiments as described herein are illustrated by
way of example and not limitation in the figures of the
accompanying drawings in which like references indicate similar
elements.
[0010] FIG. 1 shows a cross-sectional schematic view of a
semiconductor device during a process method in accordance with one
or more embodiment of the disclosure;
[0011] FIG. 2 shows an exemplary process method according to one or
more embodiment of the disclosure; and
[0012] FIG. 3 shows a cross-sectional schematic view of a
semiconductor device during a process method in accordance with one
or more embodiment of the disclosure.
[0013] In the appended figures, similar components and/or features
may have the same reference label. Further, various components of
the same type may be distinguished by following the reference label
by a dash and a second label that distinguishes among the similar
components. If only the first reference label is used in the
specification, the description is applicable to any one of the
similar components having the same first reference label
irrespective of the second reference label.
DETAILED DESCRIPTION
[0014] Before describing several exemplary embodiments of the
disclosure, it is to be understood that the disclosure is not
limited to the details of construction or process steps set forth
in the following description. The disclosure is capable of other
embodiments and of being practiced or being carried out in various
ways.
[0015] A "substrate" as used herein, refers to any substrate or
material surface formed on a substrate upon which film processing
is performed during a fabrication process. For example, a substrate
surface on which processing can be performed include materials such
as silicon, silicon oxide, strained silicon, silicon on insulator
(SOI), carbon doped silicon oxides, amorphous silicon, doped
silicon, germanium, gallium arsenide, glass, sapphire, and any
other materials such as metals, metal nitrides, metal alloys, and
other conductive materials, depending on the application. In some
embodiments, the substrate comprises titanium nitride (TiN),
titanium aluminide (TiAl), tantalum nitride (TaN), silicon (Si),
tungsten (W), tungsten carbo nitride (WC.sub.xN.sub.y), cobalt (Co)
or combinations thereof. Substrates include, without limitation,
semiconductor wafers. Substrates may be exposed to a pretreatment
process to polish, etch, reduce, oxidize, hydroxylate, anneal
and/or bake the substrate surface. In addition to film processing
directly on the surface of the substrate itself, in the present
disclosure, any of the film processing steps disclosed may also be
performed on an under-layer formed on the substrate as disclosed in
more detail below, and the term "substrate surface" is intended to
include such under-layer as the context indicates. Thus, for
example, where a film/layer or partial film/layer has been
deposited onto a substrate surface, the exposed surface of the
newly deposited film/layer becomes the substrate surface.
[0016] As used in this specification and the appended claims, the
terms "precursor", "reactant", "reactive gas" and the like are used
interchangeably to refer to any gaseous species that can react with
the substrate surface.
[0017] As used herein, the term "liner" refers to a layer
conformably formed along at least a portion of the sidewalls and/or
lower surface of an opening such that a substantial portion of the
opening prior to the deposition of the layer remains unfilled after
deposition of the layer. In some embodiments, the liner may be
formed along the entirety of the sidewalls and lower surface of the
opening.
[0018] One or more embodiments of the disclosure are directed to
high selectivity deposition processes. Some embodiments have high
deposition rates for metal fill applications. Some embodiments use
fluorine-free metal precursors to increase selectivity and
deposition rate. Some embodiments provide high selectivity
fluorine-free tungsten deposition with high throughput ALD
processes. Some embodiments incorporate a reducing agent in the
first ALD process to increase the selectivity relative to
dielectrics and increase the deposition rate with comparable film
performance (e.g., step coverage, gap filling). In some
embodiments, the fluorine-free tungsten film throughput is
increased due to increased deposition rate of the fluorine-free
tungsten precursor.
[0019] Some embodiments of the disclosure provide atomic layer
deposition methods incorporating a reducing agent in the first ALD
step. Without being bound by any particular theory of operation, it
is believed that the inclusion of the reducing agent enables the
precursor to thermally decompose into different derivatives of the
precursor with significantly greater precursor reduction in the
main reducing ALD step.
[0020] One or more embodiments of the disclosure incorporate
different gases (e.g., H.sub.2, SiH.sub.4, Si.sub.2H.sub.6,
Si.sub.4H.sub.10, NH.sub.3) into the metal (e.g., tungsten (W))
precursor dose. In some embodiments, the incorporation of a
reducing agent improves the selectivity of the metal deposition
relative to dielectrics and accelerates the rate of metal
reduction.
[0021] ALD Fluorine-Free Tungsten (FFW) in some embodiments
replaces and/or reduces traditional high resistivity nucleation
layers (e.g., SiH.sub.4 or B.sub.2H.sub.6 ALD W 20-30 .ANG.) and
thick fluorine barrier (e.g., TiN 30-50 .ANG.). In some
embodiments, FFW has low resistivity, excellent step coverage,
superior fluorine barrier property, and can integrate with
conventional WF.sub.6 based bulk W fill. Some embodiments improve
throughput while maintaining acceptable film performance or other
metrics (e.g., non-uniformity, step coverage, particles).
[0022] One or more embodiments of the disclosure are directed to
methods with high deposition rate Fluorine-Free Tungsten. A small
co-flow of a reducing agent, like H.sub.2, SiH.sub.4,
Si.sub.2H.sub.6, Si.sub.4H.sub.12, NH.sub.3, is added to the
Fluorine-Free Tungsten precursor ALD dose step. In some
embodiments, the growth of Fluorine-Free Tungsten film with a
hydrogen (H.sub.2) co-flow by ALD occurs at a suitable temperature
(e.g., ranging from 400.degree. C. to 550.degree. C., or form
460.degree. C. to 475.degree. C.).
[0023] The Fluorine-Free Tungsten precursor for growing
Fluorine-Free Tungsten film includes, but is not limited to,
tungsten chloride and hydrogen as reducing agent. In some
embodiments, Fluorine-Free Tungsten film is grown on a conductive
layer (e.g., TiN or TiAl films). In one or more embodiments, the
ALD process includes: exposure to a Fluorine-Free Tungsten dose
with 50-500 sccm of H.sub.2 co-flow, purge, H.sub.2 dose, purge.
Argon (Ar) or other suitable inert gas is used for precursor
carrier and purging in some embodiments.
[0024] In some embodiments, the deposition rate of the
Fluorine-Free Tungsten film is increased 2.times. or more on TiN
and TiAl films. In some embodiments, the film throughput is
increased due to increased deposition rate of the Fluorine-Free
Tungsten precursors. In some embodiments, a Fluorine-Free Tungsten
nucleation layer is deposited followed by high deposition rate
Fluorine-Free Tungsten film in same chamber without air break.
[0025] In one or more embodiments, the small amount of reducing
agent (H.sub.2) with Fluorine-Free Tungsten precursor does not show
any CVD W film growth. Without being bound by any particular theory
of operation, it is believed that without enough reducing agent,
the W precursor is not reduced completely to metallic W. It is
further believed that with small amount of reductant, some of W
precursor reduces to different W precursor derivatives that are
less reactive and are not readily reduced to metallic W with low
H.sub.2 flow. The tungsten precursor derivatives deposited on the
substrate surface is reduced to metallic tungsten.
[0026] Referring to FIGS. 1 through 3, one or more embodiments of
the disclosure are directed to methods 200 for depositing metal
films 140 on a substrate 100.
[0027] FIG. 3 illustrates the method 200 depositing the metal film
140 on the substrate 100; for example, a blanket deposition
process.
[0028] FIG. 1 shows the substrate 100 having at least one feature
112 formed therein. Those skilled in the art will understand that
the single feature 112 shown in FIG. 1 is for illustrative purposes
and there can be more than one feature. The shape of the feature
112 can be any suitable shape including, but not limited to, peaks,
trenches and cylindrical vias. In specific embodiments, the feature
112 is a trench. In other specific embodiments, the feature 112 is
a via. As used in this regard, the term "feature" means any
intentional surface irregularity. Suitable examples of features
include, but are not limited to trenches which have a top, two
sidewalls and a bottom, peaks which have a top and two sidewalls
extending upward from a surface, and vias which have sidewalls
extending down from a surface with an open bottom. Features can
have any suitable aspect ratio (ratio of the depth of the feature
to the width of the feature). In some embodiments, the aspect ratio
is greater than or equal to 2:1, 4:1, 5:1, 10:1, 15:1, 20:1, 25:1,
30:1, 35:1 or 40:1. In one or more embodiments the aspect ratio is
in a range of from 2:1 to 40:1, from 2:1 to 35:1, from 2:1 to 30:1,
from 2:1 to 25:1, from 2:1 to 20:1, from 2:1 to 15:1, from 2:1 to
10:1, from 2:1 to 4:1, from 4:1 to 40:1, from 4:1 to 35:1, from 4:1
to 30:1, from 4:1 to 25:1, from 4:1 to 20:1, from 4:1 to 15:1, from
4:1 to 10:1, from 5:1 to 40:1, from 5:1 to 35:1, from 5:1 to 30:1,
from 5:1 to 25:1, from 5:1 to 20:1, from 5:1 to 15:1, from 5:1 to
10:1, from 10:1 to 40:1, from 10:1 to 35:1, from 10:1 to 30:1, from
10:1 to 25:1, from 10:1 to 20:1, from 10:1 to 15:1, from 15:1 to
40:1, from 15:1 to 35:1, from 15:1 to 30:1, from 15:1 to 25:1, from
15:1 to 20:1, from 20:1 to 40:1, from 20:1 to 35:1, from 20:1 to
30:1, from 20:1 to 25:1, from 25:1 to 40:1, from 25:1 to 35:1, from
25:1 to 30:1, from 30:1 to 40:1, from 30:1 to 35:1 or from 35:1 to
40:1. In one or more embodiments the aspect ratio is greater than
10:1.
[0029] The substrate 100 illustrated in FIG. 1 includes a first
material (conductive material 104) with a first surface (conductive
surface 105) and a second material (dielectric material 106) with a
second surface (dielectric surface 107). In the embodiment shown,
the feature 112 is a via. The via has a bottom formed by the
conductive surface 105 and sidewalls formed by the dielectric
surface 107.
[0030] The dielectric material 106 and the dielectric surface 107
of the dielectric material 106 comprises any suitable dielectric
material. In some embodiments, the dielectric material 106 and the
dielectric surface 107 comprises one or more of silicon nitride
(SiN.sub.x), silicon oxide (SiO.sub.x), silicon oxynitride
(SiO.sub.xN.sub.y), hafnium oxide (HfO.sub.x) or combination
thereof.
[0031] The conductive material 104 and the conductive surface 105
of the conductive material 104, comprises any suitable conductive
material. In some embodiments, the conductive material 104 and the
conductive surface 105 of the conductive material 104 comprises one
or more of titanium (Ti), aluminum (Al), titanium nitride (TiN),
titanium aluminide (TiAl), tantalum nitride (TaN), silicon (Si),
tungsten (W), tungsten carbo nitride (WC.sub.xN.sub.y), cobalt (Co)
or combinations thereof.
[0032] Referring to FIG. 2, the method 200 is performed in a
process chamber or in a region (or station) of a batch process
chamber. In some embodiments, the method 200 includes an optional
pretreatment process 205. In some embodiments, the pretreatment
process 205 comprises polishing, etching, reducing, oxidizing,
hydroxylating, annealing and/or baking the substrate 100.
[0033] In some embodiments, as shown in method 100 and in FIG. 3,
an optional nucleation layer 130 is formed on the substrate surface
102 prior to exposure to the first process condition 112. In some
embodiments, the substrate surface 102 is not exposed to air
between formation of the nucleation layer 130 and the first process
condition 112.
[0034] In other embodiments, metal precursor may form another
suitable metal film. Suitable metal films include, but are not
limited to, films including one or more of cobalt (Co), molybdenum
(Mo), tungsten (W), tantalum (Ta), titanium (Ti), ruthenium (Ru),
rhodium (Rh), copper (Cu), iron (Fe), manganese (Mn), vanadium (V),
niobium (Nb), hafnium (Hf), zirconium (Zr), yttrium (Y), aluminum
(Al), tin (Sn), chromium (Cr), lanthanum (La), iridium (Ir), or any
combination thereof. The metal precursor selected for the other
metal films of some embodiments comprises or consists essentially
of a fluorine-free metal halide.
[0035] Referring to FIG. 2, at process 210, the method 200
comprises three sub-processes. The skilled artisan will recognize
that more or less than three sub-processes can be included in the
process 210 and the disclosure is not limited to the process
illustrated. The process 210 comprises sequentially exposing the
substrate 100 having the dielectric surface 107 and the conductive
surface 105 to a first process condition 212 to deposit a
fluorine-free metallic tungsten film 120, an optional plasma
treatment 214 and a second process condition 216 to deposit a
tungsten film 140.
[0036] At process 212, the substrate 100 is exposed to the first
process condition. As used in this manner, a "process condition" is
any parameters used to deposit a predetermined film (e.g.,
precursor, flow rate, pressure, temperature). In some embodiments,
the first process condition selectively deposits the fluorine-free
tungsten-containing film on one surface preferentially relative to
a second surface. FIG. 1 illustrates a selective deposition process
in which the fluorine-free tungsten-containing film 120 is
deposited selectively on the conductive surface 105 relative to the
dielectric surface 107. As used in this manner, "selectivity",
"selectively" and the like, refer to a process that deposits at a
faster rate on the stated surface relative to the adjacent
surfaces. In some embodiments, the selective deposition conformally
deposits in a structure having an aspect ratio greater than or
equal to 2:1 or 4:1. In some embodiments, the first process
condition comprises an Atomic Layer Deposition (ALD) process. In
some embodiments, the ALD process deposits the fluorine-free
metallic tungsten film 120 selectively on the conductive surface
105 relative to the dielectric surface 107.
[0037] One or more embodiments of the disclosure are directed to
methods with high deposition rate for fluorine-free metallic
tungsten films 120. Some embodiments use fluorine-free tungsten
precursors to increase selectivity and/or deposition rate. Some
embodiments provide high selectivity fluorine-free tungsten
deposition with high throughput ALD processes. In some embodiments,
the ALD process comprises sequentially exposing the substrate 100
to a fluorine-free tungsten precursor to deposit the fluorine-free
tungsten-containing film, optionally purging the fluorine-free
tungsten precursor and exposing the fluorine-free
tungsten-containing film to a first reducing agent to form the
fluorine-free metallic tungsten film 120.
[0038] In some embodiments, the fluorine-free tungsten precursor
comprises a tungsten halide, a tungsten oxyhalide, a tungsten
hydrohalide or combinations thereof. In some embodiments, the
fluorine-free tungsten precursor consists essentially a tungsten
halide or a tungsten oxy-halide. As used in this specification and
the appended claims, the term "consists essentially of" means that
the active (or reactive) species comprises greater than or equal to
95%, 98%, 99% or 99.5% of the stated species on a molar basis. In
some embodiments, the tungsten halide comprises tungsten
pentachloride (WCl.sub.5), tungsten hexachloride (WCl.sub.6),
tungsten pentabromide (WBr.sub.5), tungsten hexabromide (WBr.sub.6)
or combinations thereof. In some embodiments, the tungsten
oxyhalide precursor comprises tungsten oxytetrachloride
(WOCl.sub.4), tungsten dichloride dioxide (WO.sub.2Cl.sub.2) or
combinations thereof. In some embodiments, the fluorine-free
tungsten precursor comprises tungsten pentachloride (WCl.sub.5),
tungsten hexachloride (WCl.sub.6), tungsten oxytetrachloride
(WOCl.sub.4), tungsten dichloride dioxide (WO.sub.2Cl.sub.2),
tungsten pentabromide (WBr.sub.5), tungsten hexabromide (WBr.sub.6)
or combinations thereof. In other embodiments, the first process
condition comprises a tungsten precursor selected from the group
consisting of fluorine free tungsten halide precursors or
chlorine-free tungsten halide precursors, such as tungsten
pentabromide (WBr.sub.5) or tungsten hexabromide (WBr.sub.6).
[0039] In some embodiments, the fluorine-free tungsten precursor
comprises a carrier gas. In some embodiments, an inert gas used as
the carrier gas for the fluorine-free tungsten precursor. In some
embodiments, the carrier gas comprises helium, neon, argon,
nitrogen, krypton, xenon or combinations thereof. In some
embodiments, argon is used as a carrier gas for the fluorine-free
tungsten precursor.
[0040] In some embodiments, the substrate 100 is exposed to the
fluorine-free tungsten precursor at a concentration in a range of
from 100 sccm to 700 sccm, from 100 sccm to 600 sccm, from 100 sccm
to 500 sccm, from 100 sccm to 400 sccm, from 100 sccm to 300 sccm,
from 100 sccm to 200 sccm, from 200 sccm to 700 sccm, from 200 sccm
to 600 sccm, from 200 sccm to 500 sccm, from 200 sccm to 400 sccm,
from 200 sccm to 300 sccm, from 300 sccm to 700 sccm, from 300 sccm
to 600 sccm, from 300 sccm to 500 sccm, from 300 sccm to 400 sccm,
from 400 sccm to 700 sccm, from 400 sccm to 600 sccm, from 400 sccm
to 500 sccm, from 500 sccm to 700 sccm, from 500 sccm to 600 sccm
or from 600 sccm to 700 sccm.
[0041] In some embodiments, the fluorine-free tungsten precursor is
solid or liquid. In some embodiments, the fluorine-free tungsten
precursor is held in an ampoule. In some embodiments, a flow of the
carrier gas passes through the ampoule and brings the fluorine-free
tungsten precursor along to the substrate surface 100. As used
herein, the flow rate of the fluorine-free tungsten precursor is
the flow rate of the carrier gas including the fluorine-free
tungsten precursor.
[0042] In some embodiments, the fluorine-free tungsten precursor
comprises a co-flown reactant. In some embodiments, the co-flown
reactant comprises a hydrogen containing gas. In some embodiments,
the co-flown reactant comprises a reducing agent. In some
embodiments, the co-flown reducing agent comprises H.sub.2,
SiH.sub.4, Si.sub.2H.sub.6, Si.sub.4H.sub.12, NH.sub.3,
N.sub.2H.sub.4 or combinations thereof. In one or more embodiments,
the fluorine-free tungsten precursor comprises the co-flown
reducing agent at a concentration in a range of from 500 sccm to
7000 sccm, from 500 sccm to 6000 sccm, from 500 sccm to 5000 sccm,
from 500 sccm to 4000 sccm, from 500 sccm to 3000 sccm, from 500
sccm to 2000 sccm, from 500 sccm to 1000 sccm, from 1000 sccm to
7000 sccm, from 1000 sccm to 6000 sccm, from 1000 sccm to 5000
sccm, from 1000 sccm to 4000 sccm, from 1000 sccm to 3000 sccm,
from 1000 sccm to 2000 sccm, from 2000 sccm to 7000 sccm, from 2000
sccm to 6000 sccm, from 2000 sccm to 5000 sccm, from 2000 sccm to
4000 sccm, from 2000 sccm to 3000 sccm, from 3000 sccm to 7000
sccm, from 3000 sccm to 6000 sccm, from 3000 sccm to 5000 sccm,
from 3000 sccm to 4000 sccm, from 4000 sccm to 7000 sccm, from 4000
sccm to 6000 sccm, from 4000 sccm to 5000 sccm, from 5000 sccm to
7000 sccm, from 5000 sccm to 6000 sccm or from 6000 sccm to 7000
sccm. In some embodiments, the fluorine-free tungsten precursor
comprises hydrogen (H.sub.2) at a concentration in a range of from
500 sccm to 7000 sccm,
[0043] In one or more embodiments, the co-flown reducing agent with
fluorine-free tungsten precursor has substantially no CVD tungsten
film growth. As used in this manner, the term "substantially no
CVD" means that less than or equal to 5%, 2%, 1% or 0.5% of the
fluorine-free tungsten film is formed through gas-phase reactions,
on a volume basis. In some embodiments, substantially no CVD means
no co-flown reactant during ALD deposition of the fluorine-free
tungsten containing film. Without being bound by any particular
theory of operation, it is believed that without enough reducing
agent, the fluorine-free tungsten precursor is not reduced
completely to metallic tungsten. It is believed that the co-flown
reducing agent enables the fluorine-free tungsten precursor to
thermally decompose into different derivatives of the fluorine-free
precursor that significantly reduces more when exposed to the first
reducing agent.
[0044] In some embodiments, the fluorine-free tungsten precursor
consists of, or consists essentially of, a metallic tungsten
precursor gas, a reactant gas, and a carrier gas. In some
embodiments, the fluorine-free tungsten precursor consists of, or
consists essentially of a chlorine-free, fluorine-free tungsten
halide precursor, a hydrogen containing gas, and an inert gas.
[0045] In some embodiments, the fluorine-free tungsten film is
deposited at a suitable temperature. In some embodiments, the
suitable temperate is a temperature in a range of from 15.degree.
C. to 450.degree. C., from 15.degree. C. to 300.degree. C., from
15.degree. C. to 150.degree. C., from 15.degree. C. to 50.degree.
C., from 50.degree. C. to 450.degree. C., from 50.degree. C. to
300.degree. C., from 50.degree. C. to 150.degree. C., from
150.degree. C. to 450.degree. C., from 150.degree. C. to
300.degree. C. or from 300.degree. C. to 450.degree. C. In some
embodiments, the substrate 100 is exposed to the fluorine-free
tungsten precursor and the co-flown reducing agent at a temperature
in a range of from 15.degree. C. to 450.degree. C. In some
embodiments, substrate 100 is exposed to the fluorine-free tungsten
precursor and a hydrogen (H.sub.2) at a temperature in a range of
from 15.degree. C. to 450.degree. C.
[0046] In some embodiments, the fluorine-free tungsten precursor
and co-flown reducing agent increases the selectivity for
conductive material relative to dielectric material. In some
embodiments, the fluorine-free tungsten precursor and co-flown
reducing agent increase the deposition rate with comparable film
performance (e.g., step coverage, gap filling).
[0047] In some embodiments, the fluorine-free tungsten-containing
film is substantially free of tungsten metal. As used in this
manner, the term "tungsten metal" refers to zero valent tungsten
atoms in the tungsten-containing film. As used in this manner, the
term "substantially free of tungsten metal" means that less than or
equal to 5%, 2%, 1% or 0.5% of the tungsten atoms in the
tungsten-containing film are zero valent tungsten atoms. In some
embodiments, the flow rates of the fluorine-free tungsten precursor
and the co-flown reducing agent are configured to provide a
fluorine-free tungsten-containing film substantially free of
tungsten metal.
[0048] In some embodiments, the fluorine-free tungsten precursor is
purged before exposing the substrate to the first reducing agent.
The purging can be any suitable purge process that removes
unreacted fluorine-free metal precursor, reaction products and
by-products from the process region. The suitable purge process
includes moving the substrate 100 through a gas curtain to a
portion or sector of the processing region that contains none or
substantially none of the reactant. In one or more embodiments,
purging the processing region comprises applying a vacuum. In some
embodiments, purging the processing region comprises flowing a
purge gas over the substrate 100. In some embodiments, the purge
process comprises flowing the same inert gas that is used as the
carrier gas for the fluorine-free tungsten precursor. In one or
more embodiments, the purge gas is selected from one or more of
nitrogen (N.sub.2), helium (He), and argon (Ar).
[0049] In some embodiments, the fluorine-free tungsten-containing
film is reduced to a fluorine-free metallic tungsten film 120.
Stated differently, in some embodiments, the fluorine-free
tungsten-containing film is converted to the fluorine-free metallic
tungsten film 120 by treating the fluorine-free tungsten-containing
film that is substantially free of tungsten metal with the first
reducing agent.
[0050] In one or more embodiments, the first process condition
includes the first reducing agent that is reactive with the
tungsten precursor. The first reducing agent (also referred to as a
first reductant) comprises a reactive gas, such as a
hydrogen-containing gas, such as hydrogen (H.sub.2) or ammonia
(NH.sub.3) or hydrazine N.sub.2H.sub.4).
[0051] In one or more embodiments, the first reducing agent
comprises hydrogen (H.sub.2), silane (SiH.sub.4), disilane
(Si.sub.2H.sub.6), trisilane (Si.sub.3H.sub.8), tetrasilane
(Si.sub.4H.sub.10), ammonia (NH.sub.3), hydrazine (N.sub.2H.sub.4)
or combinations thereof. In some embodiments, the first reducing
agent comprises a carrier gas. In some embodiments, the carrier gas
is an inert gas. In some embodiments, the inert gas comprises argon
(Ar), helium (He), nitrogen (N.sub.2) or combinations thereof. In
some embodiments, the fluorine-free tungsten-containing film is
exposed to the first reducing agent at a concentration in a range
of from 500 sccm to 7000 sccm, from 500 sccm to 6000 sccm, from 500
sccm to 5000 sccm, from 500 sccm to 4000 sccm, from 500 sccm to
3000 sccm, from 500 sccm to 2000 sccm, from 500 sccm to 1000 sccm,
from 1000 sccm to 7000 sccm, from 1000 sccm to 6000 sccm, from 1000
sccm to 5000 sccm, from 1000 sccm to 4000 sccm, from 1000 sccm to
3000 sccm, from 1000 sccm to 2000 sccm, from 2000 sccm to 7000
sccm, from 2000 sccm to 6000 sccm, from 2000 sccm to 5000 sccm,
from 2000 sccm to 4000 sccm, from 2000 sccm to 3000 sccm, from 3000
sccm to 7000 sccm, from 3000 sccm to 6000 sccm, from 3000 sccm to
5000 sccm, from 3000 sccm to 4000 sccm, from 4000 sccm to 7000
sccm, from 4000 sccm to 6000 sccm, from 4000 sccm to 5000 sccm,
from 5000 sccm to 7000 sccm, from 5000 sccm to 6000 sccm or from
6000 sccm to 7000 sccm.
[0052] At 214, in some embodiments, the first reducing agent is
optionally purged from the processing region. Purging the
processing region removes unreacted reactant, reaction products and
by-products from the area adjacent the substrate surface 100. The
purge process can be any suitable purge process that removes
unreacted first reducing agent from the process region. In some
embodiments, the purge process can be the same or different process
as the fluorine-free tungsten precursor purge process.
[0053] In one or more embodiments, the ALD process cycle comprises
exposing a substrate surface to a fluorine-free tungsten precursor
comprising co-flowing hydrogen (H.sub.2) at a dose in a range of
from 500 sccm to 7000 sccm to deposit a fluorine-free film,
optionally purging fluorine-free tungsten precursor, exposing the
fluorine-free film to H.sub.2 at a dose in a range of from 0 sccm
to 7000 sccm, and optionally purging H.sub.2.
[0054] In some embodiments, the ALD process cycle is repeated until
the fluorine-free metallic tungsten film 120 has a thickness in a
range of from 20 .ANG. to 60 .ANG., from 30 .ANG. to 60 .ANG., from
40 .ANG. to 60 .ANG., from 50 .ANG. to 60 .ANG., from 20 .ANG. to
50 .ANG., from 30 .ANG. to 50 .ANG., from 40 .ANG. to 50 .ANG.,
from 20 .ANG. to 40 .ANG., from 30 .ANG. to 40 .ANG. or from 20
.ANG. to 30 .ANG..
[0055] The substrate 100 temperature of some embodiments is
maintained throughout the ALD process 110. In some embodiments, the
substrate 100 is maintained at a temperature in a range of from
15.degree. C. to 450.degree. C., from 50.degree. C. to 450.degree.
C., from 100.degree. C. to 450.degree. C., from 200.degree. C. to
450.degree. C., from 300.degree. C. to 450.degree. C., from
400.degree. C. to 450.degree. C., from 15.degree. C. to 350.degree.
C., from 50.degree. C. to 350.degree. C., from 100.degree. C. to
350.degree. C., from 200.degree. C. to 350.degree. C., from
300.degree. C. to 350.degree. C., from 15.degree. C. to 250.degree.
C., from 50.degree. C. to 250.degree. C., from 100.degree. C. to
250.degree. C., from 200.degree. C. to 250.degree. C., from
15.degree. C. to 150.degree. C., from 50.degree. C. to 150.degree.
C. or from 100.degree. C. to 150.degree. C. during the ALD process
110.
[0056] ALD fluorine-free metallic tungsten film 120 in some
embodiments replaces and/or reduces traditional high resistivity
nucleation layers (e.g., SiH.sub.4 or B.sub.2H.sub.6 ALD W 20-30
.ANG.) and thick fluorine barrier (e.g., TiN 30-50 .ANG.). In some
embodiments, the fluorine-free metallic tungsten film 120 has low
resistivity, excellent step coverage, superior fluorine barrier
property, and can integrate with conventional tungsten fluoride
(WF.sub.x) based bulk tungsten fill. Some embodiments improve
throughput while maintaining acceptable film performance or other
metrics (e.g., non-uniformity, step coverage, particles).
[0057] The total flow into the process region according to some
embodiments is the combined flow rates of the fluorine-free metal
precursor and the first reducing agent. In some embodiments, a
make-up gas is flowed into the process region and the fluorine-free
metal precursor and the first reducing agent are added to the
make-up gas flow stream. In some embodiments, the make-up gas flow
stream is at a much larger flow rate than either the fluorine-free
metal precursor or the first reducing agent. In some embodiments,
the make-up gas flow stream has a flow rate greater than 10.times.
the higher of the precursor flow or the first reducing agent flow.
The skilled artisan would understand that the flow rate of a
make-up gas does not change the ratio of the fluorine-free tungsten
precursor to the first reducing agent. The make-up gas flow can
change the overall concentration of the fluorine-free tungsten
precursor and/or the first reducing agent. In some embodiments, the
first process condition has a flow rate of the first reducing agent
is in a range of from 5% to 70% of a flow rate of the fluorine-free
tungsten precursor. In some embodiments, the fluorine-free tungsten
precursor and the first reducing agent has a flow rate ratio in a
range of from 10:1 to 1:2.5.
[0058] At process 215, the fluorine-free metallic tungsten film 120
is optionally treated with a plasma. In some embodiments, the
plasma treatment causes thermal reduction of the fluorine-free
metallic tungsten film 120. In some embodiments, the plasma is
generated at a power in a range of from 100 W to 1500 W, from 100 W
to 1200 W, from 100 W to 900 W, from 100 W to 600 W, from 100 W to
300 W, from 300 W to 1500 W, from 300 W to 1200 W, from 300 W to
900 W, from 300 W to 600 W, from 600 W to 1500 W, from 600 W to
1200 W, from 600 W to 900 W, from 900 W to 1500 W, from 900 W to
1200 W or from 1200 W to 1500 W. In some embodiments, the plasma
treatment comprises hydrogen (H.sub.2) plasma treatment, oxygen
(O.sub.2) plasma treatment, argon (Ar) plasma treatment or
combinations thereof. In some embodiments, the hydrogen and oxygen
plasma is configured to thermally reduce the fluorine-free metallic
tungsten film 120 by radicals and ions.
[0059] At process 216, the fluorine-free metallic tungsten film 130
is exposed to a second process condition to deposit the tungsten
film 140. In some embodiments, the second process is a chemical
vapor deposition (CVD) process. The CVD process is configured to
deposit and grow the tungsten film 140 on the fluorine-free
metallic tungsten film 130. In some embodiments, the CVD process
comprises exposing the fluorine-free metallic tungsten film 130 to
a second tungsten precursor. In some embodiments, the feature 112
is filled in a bottom-up manner. As used in this manner, the term
"bottom-up" means that most of the deposition occurs on the
metallic tungsten film 130 initially, and then on the deposited
tungsten film as the thickness grows, with little to no deposition
on the sidewalls of the feature 112.
[0060] In some embodiments, the second tungsten precursor comprises
a tungsten halide, tungsten oxyhalide, tungsten hydrohalide or
combinations thereof. In some embodiments, the tungsten halide
comprises fluorine atoms. In some embodiments, the tungsten
fluoride comprises one or more of tungsten hexafluoride (WF.sub.6)
or tungsten pentafluoride (WF.sub.5).
[0061] In some embodiments, the fluorine-free metallic tungsten
film 130 is exposed to the second tungsten precursor at a
concentration in a range of from 50 sccm to 500 sccm, from 50 sccm
to 400 sccm, from 50 sccm to 300 sccm, from 50 sccm to 200 sccm,
from 50 sccm to 100 sccm, from 100 sccm, to 500 sccm, from 100 sccm
to 400 sccm, from 100 sccm to 300 sccm, from 100 sccm to 200 sccm,
from 200 sccm to 500 sccm, from 200 sccm to 400 sccm, from 200 sccm
to 300 sccm, from 300 sccm to 500 sccm, from 300 sccm to 400 sccm
or from 400 sccm to 500 sccm. In some embodiments, the second
tungsten precursor is flowed into the process region at a pressure
in a rage of from 1 mTorr to 20 Torr, from 1 mTorr to 10 Torr, from
1 mTorr to 5 Torr, from 1 mTorr to 1 Torr, from 1 mTorr to 500
mTorr, from 500 mTorr to 20 Torr, from 500 mTorr to 10 Torr, from
500 mTorr to 5 Torr, from 500 mTorr to 1 Torr, from 1 Torr to 20
Torr, from 1 Torr to 10 Torr, from 1 Torr to 5 Torr, from 5 Torr to
20 Torr, from 5 Torr to 10 Torr or from 10 Torr to 20 Torr.
[0062] In some embodiments, the second tungsten precursor comprises
a carrier gas. In some embodiments, an inert gas used as the
carrier gas for the second tungsten precursor. In some embodiments,
the carrier gas comprises helium, neon, argon, nitrogen, krypton,
xenon or combinations thereof.
[0063] In some embodiments, the second tungsten precursor is solid,
gas or liquid. In some embodiments, the second tungsten precursor
is held in an ampoule. In some embodiments, a flow of the carrier
gas passes through the ampoule and brings the second tungsten
precursor along to the process region. As used herein, the flow
rate of the second tungsten precursor is the flow rate of the
carrier gas including the second tungsten precursor.
[0064] In some embodiments, the second tungsten precursor comprises
a second reducing agent. In some embodiments, the second reducing
agent is the same species as the first reducing agent. In some
embodiments, the second reducing agent is a different species as
the first reducing agent. The concentration of the second reducing
agent can be the same or different from the first reducing agent
concentration. In some embodiments, the second reducing agent
comprises one or more of hydrogen (H.sub.2), silane (SiH.sub.4),
disilane (Si.sub.2H.sub.6), trisilane (Si.sub.3H.sub.8),
tetrasilane (Si.sub.4H.sub.10), hydrazine (N.sub.2H.sub.4) or
ammonia (NH.sub.3).
[0065] In some embodiments, the second tungsten precursor comprises
the carrier gas and/or make-up gas. In some embodiments, the
carrier gas and/or make-up gas is an inert gas. In some
embodiments, the inert gas comprises argon (Ar), helium (He),
nitrogen (N.sub.2) or combinations thereof.
[0066] At process 218, in some embodiments, the second tungsten
precursor is optionally purged from the processing region. Purging
the processing region removes unreacted reactant, reaction products
and by-products from the area adjacent the substrate surface 100.
The purge process can be any suitable purge process that removes
unreacted second tungsten precursor from the process region. In
some embodiments, the purge process can be the same or different
process as the fluorine-free tungsten precursor purge process.
[0067] In some embodiments, the fluorine-free metallic tungsten
film 130 is exposed to the second tungsten precursor until the
tungsten film 140 has a thickness in a range of from 0 .ANG. to
1000 .ANG., from 50 .ANG. to 1000 .ANG., from 100 .ANG. to 1000
.ANG., from 200 .ANG. to 1000 .ANG., from 500 .ANG. to 1000 .ANG.,
from 800 .ANG. to 1000 .ANG., from 0 .ANG. to 800 .ANG., from 50
.ANG. to 800 .ANG., from 100 .ANG. to 800 .ANG., from 200 .ANG. to
800 .ANG., from 500 .ANG. to 800 .ANG., from 0 .ANG. to 500 .ANG.,
from 50 .ANG. to 500 .ANG., from 100 .ANG. to 500 .ANG., from 200
.ANG. to 500 .ANG., from 0 .ANG. to 200 .ANG., from 50 .ANG. to 200
.ANG., from 100 .ANG. to 200 .ANG., from 0 .ANG. to 100 .ANG., from
50 .ANG. to 100 .ANG. or from 50 .ANG. to 100 .ANG..
[0068] In some embodiments, as illustrated in FIG. 1, the metallic
tungsten film 140 is formed selectively on the conductive surface
105 over the dielectric surface 107. In some embodiments, the
metallic tungsten film 140 fills the structure 112 in a gap fill
process. The metallic tungsten film 240 of some embodiments
deposits at a rate greater than or equal to twice a deposition rate
of a substantially similar process without the first reducing agent
in the first process condition.
[0069] In some embodiments, the substrate 100 is maintained at a
temperature in a range of from 15.degree. C. to 450.degree. C.,
from 50.degree. C. to 450.degree. C., from 100.degree. C. to
450.degree. C., from 200.degree. C. to 450.degree. C., from
300.degree. C. to 450.degree. C., from 400.degree. C. to
450.degree. C., from 15.degree. C. to 350.degree. C., from
50.degree. C. to 350.degree. C., from 100.degree. C. to 350.degree.
C., from 200.degree. C. to 350.degree. C., from 300.degree. C. to
350.degree. C., from 15.degree. C. to 250.degree. C., from
50.degree. C. to 250.degree. C., from 100.degree. C. to 250.degree.
C., from 200.degree. C. to 250.degree. C., from 15.degree. C. to
150.degree. C., from 50.degree. C. to 150.degree. C. or from
100.degree. C. to 150.degree. C. during the ALD process condition
212 and the second process condition 216.
[0070] At decision point 220, a thickness of the tungsten film 140
is examined as part of method 100 of some embodiments. If the
tungsten film 140 has reached a predetermined thickness, the method
100 ends or moves to an optional post-deposition process 230. If
the predetermined condition(s) have not been met, the method 200
repeats the process 216.
[0071] The optional post-processing operation 230 can be, for
example, a process to modify film properties (e.g., annealing) or a
further film deposition process (e.g., additional ALD or CVD
processes) to grow additional films. In some embodiments, the
optional post-processing operation 230 can be a process that
modifies a property of the deposited film. In some embodiments, the
optional post-processing operation 230 comprises annealing the
as-deposited film. In some embodiments, annealing is done at
temperatures in the range of about 300.degree. C., 400.degree. C.,
500.degree. C., 600.degree. C., 700.degree. C., 800.degree. C.,
900.degree. C. or 1000.degree. C. The annealing environment of some
embodiments comprises one or more of an inert gas (e.g., molecular
nitrogen (N.sub.2), argon (Ar)) or a reducing gas (e.g., molecular
hydrogen (H.sub.2) or ammonia (NH.sub.3)) or an oxidant, such as,
but not limited to, oxygen (O.sub.2), ozone (O.sub.3), or
peroxides. Annealing can be performed for any suitable length of
time. In some embodiments, the film is annealed for a predetermined
time in the range of about 15 seconds to about 90 minutes, or in
the range of about 1 minute to about 60 minutes. In some
embodiments, annealing the as-deposited film increases the density,
decreases the resistivity and/or increases the purity of the
film.
[0072] In the foregoing specification, embodiments of the
disclosure have been described with reference to specific exemplary
embodiments thereof. It will be evident that various modifications
may be made thereto without departing from the broader spirit and
scope of the embodiments of the disclosure as set forth in the
following claims. The specification and drawings are, accordingly,
to be regarded in an illustrative sense rather than a restrictive
sense.
* * * * *