U.S. patent application number 12/111921 was filed with the patent office on 2009-10-29 for selective cobalt deposition on copper surfaces.
Invention is credited to Hua Chung, Seshadri Ganguli, Kevin Moraes, See-Eng Phan, Sang-Ho Yu.
Application Number | 20090269507 12/111921 |
Document ID | / |
Family ID | 41215285 |
Filed Date | 2009-10-29 |
United States Patent
Application |
20090269507 |
Kind Code |
A1 |
Yu; Sang-Ho ; et
al. |
October 29, 2009 |
SELECTIVE COBALT DEPOSITION ON COPPER SURFACES
Abstract
Embodiments of the invention provide processes to selectively
form a cobalt layer on a copper surface over exposed dielectric
surfaces. In one embodiment, a method for capping a copper surface
on a substrate is provided which includes positioning a substrate
within a processing chamber, wherein the substrate contains a
contaminated copper surface and a dielectric surface, exposing the
contaminated copper surface to a reducing agent while forming a
copper surface during a pre-treatment process, exposing the
substrate to a cobalt precursor gas to selectively form a cobalt
capping layer over the copper surface while leaving exposed the
dielectric surface during a vapor deposition process, and
depositing a dielectric barrier layer over the cobalt capping layer
and the dielectric surface. In another embodiment, a
deposition-treatment cycle includes performing the vapor deposition
process and subsequently a post-treatment process, which
deposition-treatment cycle may be repeated to form multiple cobalt
capping layers.
Inventors: |
Yu; Sang-Ho; (Sunnyvale,
CA) ; Moraes; Kevin; (Fremont, CA) ; Ganguli;
Seshadri; (Sunnyvale, CA) ; Chung; Hua; (San
Jose, CA) ; Phan; See-Eng; (San Jose, CA) |
Correspondence
Address: |
PATTERSON & SHERIDAN, LLP - - APPM/TX
3040 POST OAK BOULEVARD, SUITE 1500
HOUSTON
TX
77056
US
|
Family ID: |
41215285 |
Appl. No.: |
12/111921 |
Filed: |
April 29, 2008 |
Current U.S.
Class: |
427/535 ;
427/124; 427/576 |
Current CPC
Class: |
H01L 21/2855 20130101;
C23C 16/4554 20130101; H01L 21/76849 20130101; C23C 16/16 20130101;
C23C 16/45542 20130101; H01L 21/28556 20130101; C23C 16/50
20130101; C23C 16/0245 20130101; H01L 21/02068 20130101; H01L
21/7685 20130101; C23C 16/18 20130101; H01L 21/02074 20130101; H01L
21/76862 20130101; H01L 21/324 20130101; H01L 21/28562 20130101;
C23C 16/0218 20130101; H01L 21/76883 20130101 |
Class at
Publication: |
427/535 ;
427/124; 427/576 |
International
Class: |
B05D 3/04 20060101
B05D003/04; B05D 5/12 20060101 B05D005/12; C23C 16/44 20060101
C23C016/44 |
Claims
1. A method for capping a copper surface on a substrate,
comprising: positioning a substrate within a processing chamber,
wherein the substrate comprises a contaminated copper surface and a
dielectric surface; exposing the contaminated copper surface to a
reducing agent while forming a metallic copper surface during a
pre-treatment process; exposing the substrate to a cobalt precursor
gas to selectively form a cobalt capping layer over the metallic
copper surface while leaving exposed the dielectric surface during
a vapor deposition process; and depositing a dielectric barrier
layer over the cobalt capping layer and the dielectric surface.
2. The method of claim 1, further comprising chemically reducing
copper oxides on the contaminated copper surface to form the
metallic copper surface during the pre-treatment process.
3. The method of claim 1, wherein the contaminated copper surface
is exposed to the reducing agent and a plasma is ignited during the
pre-treatment process, the reducing agent comprises a reagent
selected from the group consisting of nitrogen (N.sub.2), ammonia
(NH.sub.3), hydrogen (H.sub.2), ammonia/nitrogen mixture, and
combinations thereof.
4. The method of claim 3, wherein the contaminated copper surface
is exposed to the plasma for a time period within a range from
about 5 seconds to about 15 seconds.
5. The method of claim 1, wherein the reducing agent comprises
hydrogen gas, the pre-treatment process is a thermal process, and
the substrate is heated to a temperature within a range from about
200.degree. C. to about 400.degree. C. during the thermal
process.
6. The method of claim 1, further comprising exposing the cobalt
capping layer to a reagent and a plasma during a post-treatment
process prior to depositing the dielectric barrier layer, the
reagent is selected from the group consisting of nitrogen
(N.sub.2), ammonia (NH.sub.3), hydrogen (H.sub.2), ammonia/nitrogen
mixture, and combinations thereof.
7. The method of claim 6, wherein a deposition-treatment cycle
comprises performing the vapor deposition process and subsequently
the post-treatment process, and the deposition-treatment cycle is
performed 2, 3, or more times to deposit multiple cobalt capping
layers.
8. The method of claim 7, wherein each of the cobalt capping layers
is deposited to a thickness within a range from about 3 .ANG. to
about 5 .ANG. during each of the deposition-treatment cycles.
9. The method of claim 1, wherein the cobalt capping layer has a
thickness within a range from about 4 .ANG. to about 20 .ANG..
10. The method of claim 1, wherein the cobalt capping layer has a
thickness of less than about 10 .ANG..
11. The method of claim 10, wherein the substrate is exposed to a
deposition gas comprising the cobalt precursor gas and hydrogen gas
during the vapor deposition process, the vapor deposition process
is a thermal chemical vapor deposition process or an atomic layer
deposition process.
12. The method of claim 1, wherein the cobalt precursor gas
comprises a cobalt precursor which has the general chemical formula
(CO).sub.xCo.sub.yL.sub.z, wherein: X is 1, 2, 3, 4, 5, 6, 7, 8, 9,
10, 11, or 12; Y is 1, 2, 3, 4, or 5; Z is 1, 2, 3, 4, 5, 6, 7, or
8; and L is a ligand independently selected from the group
consisting of cyclopentadienyl, alkylcyclopentadienyl,
methylcyclopentadienyl, pentamethylcyclopentadienyl, pentadienyl,
alkylpentadienyl, cyclobutadienyl, butadienyl, allyl, ethylene,
propylene, alkenes, dialkenes, alkynes, nitrosyl, ammonia,
derivatives thereof, and combinations thereof.
13. The method of claim 1, wherein the cobalt precursor gas
comprises a cobalt precursor selected from the group consisting of
tricarbonyl allyl cobalt, cyclopentadienyl cobalt bis(carbonyl),
methylcyclopentadienyl cobalt bis(carbonyl), ethylcyclopentadienyl
cobalt bis(carbonyl), pentamethylcyclopentadienyl cobalt
bis(carbonyl), dicobalt octa(carbonyl), nitrosyl cobalt
tris(carbonyl), bis(cyclopentadienyl) cobalt, (cyclopentadienyl)
cobalt (cyclohexadienyl), cyclopentadienyl cobalt (1,3-hexadienyl),
(cyclobutadienyl) cobalt (cyclopentadienyl),
bis(methylcyclopentadienyl) cobalt, (cyclopentadienyl) cobalt
(5-methylcyclopentadienyl), bis(ethylene) cobalt
(pentamethylcyclopentadienyl), derivatives thereof, complexes
thereof, plasmas thereof, and combinations thereof.
14. The method of claim 13, wherein the cobalt precursor comprises
cyclopentadienyl cobalt bis(carbonyl).
15. A method for capping a copper surface on a substrate,
comprising: positioning a substrate within a processing chamber,
wherein the substrate comprises a copper oxide surface and a
dielectric surface; exposing the copper oxide surface to an ammonia
plasma or a hydrogen plasma while forming a metallic copper surface
during a pre-treatment process; exposing the substrate to a cobalt
precursor gas to selectively form a cobalt capping layer over the
metallic copper surface while leaving exposed the dielectric
surface during a vapor deposition process; exposing the cobalt
capping layer to a plasma during a post-treatment process; and
depositing a dielectric barrier layer over the cobalt capping layer
and the dielectric surface.
16. The method of claim 15, wherein a deposition-treatment cycle
comprises performing the vapor deposition process and subsequently
the post-treatment process, and the deposition-treatment cycle is
performed 2, 3, or more times to deposit multiple cobalt capping
layers.
17. The method of claim 16, wherein each of the cobalt capping
layers is deposited to a thickness within a range from about 3
.ANG. to about 5 .ANG. during each of the deposition-treatment
cycles.
18. The method of claim 15, wherein the copper oxide surface is
exposed to the ammonia plasma or the hydrogen plasma for a time
period within a range from about 5 seconds to about 15 seconds
during a pre-treatment process.
19. The method of claim 15, wherein a reagent and the plasma are
exposed to the cobalt capping layer during the post-treatment
process, and the reagent is selected from the group consisting of
nitrogen (N.sub.2), ammonia (NH.sub.3), hydrogen (H.sub.2),
ammonia/nitrogen mixture, and combinations thereof.
20. A method for capping a copper surface on a substrate,
comprising: positioning a substrate within a processing chamber,
wherein the substrate comprises a copper oxide surface and a
dielectric surface; exposing the copper oxide surface to an ammonia
plasma or a hydrogen plasma while forming a metallic copper surface
during a pre-treatment process; exposing the substrate to a cobalt
precursor gas and hydrogen gas to selectively form a cobalt capping
layer over the metallic copper surface while leaving exposed the
dielectric surface during a vapor deposition process; and exposing
the cobalt capping layer to a plasma and a reagent selected from
the group consisting of nitrogen (N.sub.2), ammonia (NH.sub.3),
hydrogen (H.sub.2), ammonia/nitrogen mixture, and combinations
thereof during a post-treatment process.
21. The method of claim 20, wherein a deposition-treatment cycle
comprises performing the vapor deposition process and subsequently
the post-treatment process, and the deposition-treatment cycle is
performed 2, 3, or more times to deposit multiple cobalt capping
layers.
22. The method of claim 21, wherein each of the cobalt capping
layers is deposited to a thickness within a range from about 3
.ANG. to about 5 .ANG. during each of the deposition-treatment
cycles.
23. The method of claim 20, further comprising depositing a
dielectric barrier layer over the cobalt capping layer and the
dielectric surface.
24. A method for capping a copper surface on a substrate,
comprising: positioning a substrate within a processing chamber,
wherein the substrate comprises a contaminated copper surface and a
dielectric surface; exposing the contaminated copper surface to a
reducing agent while forming a metallic copper surface during a
pre-treatment process; depositing a cobalt capping material over
the metallic copper surface while leaving exposed the dielectric
surface during a deposition-treatment cycle, comprising: exposing
the substrate to a cobalt precursor gas to selectively form a first
cobalt layer over the metallic copper surface while leaving exposed
the dielectric surface during a vapor deposition process; exposing
the first cobalt layer to a plasma comprising nitrogen, ammonia, an
ammonia/nitrogen mixture, or hydrogen during a treatment process;
exposing the substrate to the cobalt precursor gas to selectively
form a second cobalt layer over the first cobalt layer while
leaving exposed the dielectric surface during the vapor deposition
process; exposing the second cobalt layer to the plasma during the
treatment process; and depositing a dielectric barrier layer over
the cobalt capping material and the dielectric surface.
25. The method of claim 24, further comprising: exposing the
substrate to the cobalt precursor gas to selectively form a third
cobalt layer over the second cobalt layer while leaving exposed the
dielectric surface during the vapor deposition process; and
exposing the third cobalt layer to the plasma during the treatment
process.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] Embodiments of the invention generally relate to a
metallization process for manufacturing semiconductor devices, more
particularly, embodiments relate to preventing copper dewetting by
depositing cobalt materials on a substrate.
[0003] 2. Description of the Related Art
[0004] Copper is the current metal of choice for use in multilevel
metallization processes that are crucial to semiconductor device
manufacturing. The multilevel interconnects that drive the
manufacturing processes require planarization of high aspect ratio
apertures including contacts, vias, lines, and other features.
Filling the features without creating voids or deforming the
feature geometry is more difficult when the features have higher
aspect ratios. Reliable formation of interconnects is also more
difficult as manufacturers strive to increase circuit density and
quality.
[0005] As the use of copper has permeated the marketplace because
of its relative low cost and processing properties, semiconductor
manufacturers continue to look for ways to improve the boundary
regions between copper and dielectric material by reducing copper
diffusion and dewetting. Several processing methods have been
developed to manufacture copper interconnects as feature sizes have
decreased. Each processing method may increase the likelihood of
errors such as copper diffusion across boundary regions, copper
crystalline structure deformation, and dewetting. Physical vapor
deposition (PVD), chemical vapor deposition (CVD), atomic layer
deposition (ALD), chemical mechanical polishing (CMP),
electrochemical plating (ECP), electrochemical mechanical polishing
(ECMP), and other methods of depositing and removing copper layers
utilize mechanical, electrical, or chemical methods to manipulate
the copper that forms the interconnects. Barrier and capping layers
may be deposited to contain the copper.
[0006] In the past, a layer of tantalum, tantalum nitride, or
copper alloy with tin, aluminum, or magnesium was used to provide a
barrier layer or an adhesion promoter between copper and other
materials. These options are costly or only partially effective or
both. As the copper atoms along the boundary regions experience
changes in temperature, pressure, atmospheric conditions, or other
process variables common during multiple step semiconductor
processing, the copper may migrate along the boundary regions and
become agglomerated copper. The copper may also be less uniformly
dispersed along the boundary regions and become dewetted copper.
These changes in the boundary region include stress migration and
electromigration of the copper atoms. The stress migration and
electromigration of copper across the dielectric layers or other
structures increases the resistivity of the resulting structures
and reduces the reliability of the resulting devices.
[0007] Barrier layers containing cobalt have been deposited by PVD,
CVD, and ALD processes. PVD processes to deposit cobalt are often
hard to control precise deposition thicknesses. CVD processes
usually suffer from poor conformality and contaminants in the
deposited cobalt layer. During a typical ALD process, a cobalt
precursor and a reducing agent are sequentially exposed to a
substrate to form the desired cobalt layer. ALD processes have
several advantages over other vapor deposition processes, such as
very conformal films and the ability to deposit into high aspect
ratio vias. However, the deposition rates of an ALD process are
often too slow, so that ALD processes are not often used in
commercial applications.
[0008] Therefore, a need exists to enhance the stability and
adhesion of copper-containing layers, especially for copper seed
layers. Also, a need exists to improve the electromigration (EM)
reliability of copper-containing layer, especially for copper line
formations, while preventing the diffusion of copper into
neighboring materials, such as dielectric materials. A further need
exists for an improved vapor deposition process to deposit cobalt
materials.
SUMMARY OF THE INVENTION
[0009] Embodiments of the invention provide processes to
selectively form a cobalt layer on a copper surface over exposed
dielectric surfaces. In one embodiment, a method for capping a
copper surface on a substrate is provided which includes
positioning a substrate within a processing chamber, wherein the
substrate contains a contaminated copper surface and a dielectric
surface, exposing the contaminated copper surface to a reducing
agent while forming a metallic copper surface during a
pre-treatment process, exposing the substrate to a cobalt precursor
gas to selectively form a cobalt capping layer over the metallic
copper surface while leaving exposed the dielectric surface during
a vapor deposition process, and depositing a dielectric barrier
layer over the cobalt capping layer and the dielectric surface.
[0010] In some examples, the method further includes chemically
reducing copper oxides on the contaminated copper surface to form
the metallic copper surface during the pre-treatment process. The
contaminated copper surface may be exposed to the reducing agent
and a plasma is ignited during the pre-treatment process, the
reducing agent may contain a reagent such as nitrogen (N.sub.2),
ammonia (NH.sub.3), hydrogen (H.sub.2), an ammonia/nitrogen
mixture, or combinations thereof. In some examples, the
contaminated copper surface may be exposed to the plasma for a time
period within a range from about 5 seconds to about 15 seconds. In
another example, the reducing agent contains hydrogen gas, the
pre-treatment process is a thermal process, and the substrate is
heated to a temperature within a range from about 200.degree. C. to
about 400.degree. C. during the thermal process.
[0011] In other examples, the method further includes exposing the
cobalt capping layer to a reagent and a plasma during a
post-treatment process prior to depositing the dielectric barrier
layer. The reagent may contain nitrogen, ammonia, hydrogen, an
ammonia/nitrogen mixture, or combinations thereof.
[0012] In another embodiment, a deposition-treatment cycle includes
performing the vapor deposition process and subsequently the
post-treatment process, and the deposition-treatment cycle is
performed 2, 3, or more times to deposit multiple cobalt capping
layers. Each of the cobalt capping layers may be deposited to a
thickness within a range from about 3 .ANG. to about 5 .ANG. during
each of the deposition-treatment cycles. The overall cobalt capping
material or cobalt capping layer may have a thickness within a
range from about 4 .ANG. to about 20 .ANG.. In some examples, the
cobalt capping layer has a thickness of less than about 10
.ANG..
[0013] The substrate may be exposed to a deposition gas containing
the cobalt precursor gas and hydrogen gas during the vapor
deposition process, the vapor deposition process is a thermal
chemical vapor deposition process or an atomic layer deposition
process. wherein the cobalt precursor gas contains a cobalt
precursor which has the general chemical formula
(CO).sub.xCo.sub.yL.sub.z, wherein X is 1, 2, 3, 4, 5, 6, 7, 8, 9,
10, 11, or 12; Y is 1, 2, 3, 4, or 5; Z is 1, 2, 3, 4, 5, 6, 7, or
8; and L is a ligand independently selected from cyclopentadienyl,
alkylcyclopentadienyl, methylcyclopentadienyl,
pentamethylcyclopentadienyl, pentadienyl, alkylpentadienyl,
cyclobutadienyl, butadienyl, allyl, ethylene, propylene, alkenes,
dialkenes, alkynes, nitrosyl, ammonia, derivatives thereof, or
combinations thereof. The cobalt precursor gas may contain a cobalt
precursor selected from the group consisting of tricarbonyl allyl
cobalt, cyclopentadienyl cobalt bis(carbonyl),
methylcyclopentadienyl cobalt bis(carbonyl), ethylcyclopentadienyl
cobalt bis(carbonyl), pentamethylcyclopentadienyl cobalt
bis(carbonyl), dicobalt octa(carbonyl), nitrosyl cobalt
tris(carbonyl), bis(cyclopentadienyl) cobalt, (cyclopentadienyl)
cobalt (cyclohexadienyl), cyclopentadienyl cobalt (1,3-hexadienyl),
(cyclobutadienyl) cobalt (cyclopentadienyl),
bis(methylcyclopentadienyl) cobalt, (cyclopentadienyl) cobalt
(5-methylcyclopentadienyl), bis(ethylene) cobalt
(pentamethylcyclopentadienyl), derivatives thereof, complexes
thereof, plasmas thereof, or combinations thereof. In one example,
the cobalt precursor contains cyclopentadienyl cobalt
bis(carbonyl).
[0014] In another embodiment, a method for capping a copper surface
on a substrate is provided which includes positioning a substrate
within a processing chamber, wherein the substrate contains a
copper oxide surface and a dielectric surface, exposing the copper
oxide surface to an ammonia plasma or a hydrogen plasma while
forming a metallic copper surface during a pre-treatment process,
exposing the substrate to a cobalt precursor gas to selectively
form a cobalt capping layer over the metallic copper surface while
leaving exposed the dielectric surface during a vapor deposition
process, exposing the cobalt capping layer to a plasma during a
post-treatment process, and depositing a dielectric barrier layer
over the cobalt capping layer and the dielectric surface.
[0015] In some examples, a deposition-treatment cycle is formed by
performing the vapor deposition process and subsequently the
post-treatment process. The deposition-treatment cycle may be
performed 2, 3, or more times to deposit multiple cobalt capping
layers. Each of the cobalt capping layers may be deposited to a
thickness within a range from about 3 .ANG. to about 5 .ANG. during
each of the deposition-treatment cycles.
[0016] In another example, the copper oxide surface may be exposed
to the ammonia plasma or the hydrogen plasma for a time period
within a range from about 5 seconds to about 15 seconds during a
pre-treatment process. The plasma may be exposed to the cobalt
capping layer during the post-treatment process contains nitrogen,
ammonia, an ammonia/nitrogen mixture, or hydrogen.
[0017] In another embodiment, a method for capping a copper surface
on a substrate is provided which includes positioning a substrate
within a processing chamber, wherein the substrate contains a
copper oxide surface and a dielectric surface, exposing the copper
oxide surface to an ammonia plasma or a hydrogen plasma while
forming a metallic copper surface during a pre-treatment process,
exposing the substrate to a cobalt precursor gas and hydrogen gas
to selectively form a cobalt capping layer over the metallic copper
surface while leaving exposed the dielectric surface during a vapor
deposition process, and exposing the cobalt capping layer to a
plasma and a reagent selected from the group consisting of
nitrogen, ammonia, hydrogen, an ammonia/nitrogen mixture, and
combinations thereof during a post-treatment process.
[0018] In another embodiment, a method for capping a copper surface
on a substrate is provided which includes positioning a substrate
within a processing chamber, wherein the substrate contains a
contaminated copper surface and a dielectric surface, exposing the
contaminated copper surface to a reducing agent while forming a
metallic copper surface during a pre-treatment process, and
depositing a cobalt capping material over the metallic copper
surface while leaving exposed the dielectric surface during a
deposition-treatment cycle. In one example, the
deposition-treatment cycle includes exposing the substrate to a
cobalt precursor gas to selectively form a first cobalt layer over
the metallic copper surface while leaving exposed the dielectric
surface during a vapor deposition process, exposing the first
cobalt layer to a plasma containing nitrogen, ammonia, an
ammonia/nitrogen mixture, or hydrogen during a treatment process,
exposing the substrate to the cobalt precursor gas to selectively
form a second cobalt layer over the first cobalt layer while
leaving exposed the dielectric surface during the vapor deposition
process, and exposing the second cobalt layer to the plasma during
the treatment process. The method further provides depositing a
dielectric barrier layer over the cobalt capping material and the
dielectric surface.
[0019] In some examples, the method provides exposing the substrate
to the cobalt precursor gas to selectively form a third cobalt
layer over the second cobalt layer while leaving exposed the
dielectric surface during the vapor deposition process, and
exposing the third cobalt layer to the plasma during the treatment
process.
BRIEF DESCRIPTION OF THE DRAWINGS
[0020] So that the manner in which the above recited features of
the invention can be understood in detail, a more particular
description of the invention, 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 invention and
are therefore not to be considered limiting of its scope, for the
invention may admit to other equally effective embodiments.
[0021] FIG. 1 depicts a flow chart illustrating a treatment and
deposition process according to an embodiment described herein;
[0022] FIGS. 2A-2E depict schematic views of a substrate at
different process steps according to an embodiment described
herein; and
[0023] FIG. 3 depicts a flow chart illustrating a deposition
process according to another embodiment described herein.
DETAILED DESCRIPTION
[0024] Embodiments of the invention provide a method that utilizes
a cobalt capping layer or material to prevent copper diffusion and
dewetting in interconnect boundary regions. The transition metal,
for example, cobalt, improves copper boundary region properties to
promote adhesion, decrease diffusion and agglomeration, and
encourage uniform roughness and wetting of the substrate surface
during processing. Embodiments provide that a cobalt capping layer
may be selectively deposited on a copper contact or surface on a
substrate while leaving exposed dielectric surfaces on the
substrate.
[0025] FIG. 1 depicts a flow chart illustrating process 100
according to an embodiment of the invention. Process 100 may be
used to clean and cap a copper contact surface on a substrate post
a polishing process. In one embodiment, steps 110-140 of process
100 may be used on substrate 200, depicted in FIGS. 2A-2E. Process
100 includes exposing a substrate to pre-treatment process (step
110), depositing a cobalt capping layer on exposed copper surfaces
of the substrate (step 120), exposing the substrate to
post-treatment process (step 130), and depositing a dielectric
barrier layer on the substrate (step 140).
[0026] FIG. 2A depicts substrate 200 containing dielectric layer
204 disposed over underlayer 202 after being exposed to a polishing
process. Copper contacts 208 are disposed within dielectric layer
204 and are separated from dielectric layer 204 by barrier layer
206. Dielectric layer 204 contains a dielectric material, such as a
low-k dielectric material. In one example, dielectric layer 204
contains a low-k dielectric material, such as a silicon carbide
oxide material or a carbon doped silicon oxide material, for
example, BLACK DIAMOND.RTM. II low-k dielectric material, available
from Applied Materials, Inc., located in Santa Clara, Calif.
[0027] Barrier layer 206 may be conformally deposited into the
aperture within dielectric layer 204. Barrier layer 206 may be
formed or deposited by a PVD process, an ALD, or a CVD process, and
may have a thickness within a range from about 5 .ANG. to about 50
.ANG., preferably, from about 10 .ANG. to about 30 .ANG.. Barrier
layer 206 may contain titanium, titanium nitride, tantalum,
tantalum nitride, tungsten, tungsten nitride, suicides thereof,
derivatives thereof, or combinations thereof. In some embodiments,
barrier layer 206 may contain a tantalum/tantalum nitride bilayer
or titanium/titanium nitride bilayer. In one example, barrier layer
206 contains tantalum nitride and metallic tantalum layers
deposited by PVD processes.
[0028] During the polishing process, such as a chemical mechanical
polishing (CMP) process, the upper surface of copper contacts 208
are exposed across substrate field 210 and contaminants 212 are
formed on copper contacts 212. Contaminants 212 usually contain
copper oxides formed during or after the polishing process. The
exposed surfaces of copper contacts 208 may be oxidized by
peroxides, water, or other reagents in the polishing solution or by
oxygen within the ambient air. Contaminants 212 may also include
moisture, polishing solution remnants including surfactants and
other additives, or particles of polished away materials.
[0029] At step 110 of process 100, contaminants 212 may be removed
from substrate field 210 by exposing substrate 200 to a
pre-treatment process. Copper surfaces 214 are exposed once
contaminants 212 are treated or removed from copper contacts 208,
as illustrated in FIG. 2B. Copper oxides may be chemically reduced
by exposing substrate 200 to a reducing agent. The pre-treatment
process exposes substrate 200 to the reducing agent during a
thermal process or a plasma process. The reducing agent may have a
liquid state, a gas state, a plasma state, or combinations thereof.
Reducing agent that are useful during the pre-treatment process
include hydrogen (e.g., H.sub.2 or atomic-H), ammonia (NH.sub.3), a
hydrogen and ammonia mixture (H.sub.2/NH.sub.3), atomic-N,
hydrazine (N.sub.2H.sub.4), alcohols (e.g., methanol, ethanol, or
propanol), derivatives thereof, plasmas thereof, or combinations
thereof. Substrate 200 may be exposed to a plasma formed in situ or
remotely during the pre-treatment process.
[0030] In one embodiment, substrate 200 is exposed to a thermal
pre-treatment process to remove contaminants 212 from copper
contacts 208 while forming copper surfaces 214. Substrate 200 may
be positioned within a processing chamber, exposed to a reducing
agent, and heated to a temperature within a range from about
200.degree. C. to about 800.degree. C., preferably, from about
250.degree. C. to about 600.degree. C., and more preferably, from
about 300.degree. C. to about 500.degree. C. Substrate 200 may be
heated for a time period within a range from about 2 minutes to
about 20 minutes, preferably, from about 5 minutes to about 15
minutes. For example, substrate 200 may be heated to about
500.degree. C. in a processing chamber containing a hydrogen
atmosphere for about 12 minutes.
[0031] In another embodiment, substrate 200 is exposed to a plasma
pre-treatment process to remove contaminants 212 from copper
contacts 208 while forming copper surfaces 214. Substrate 200 may
be positioned within a processing chamber, exposed to a reducing
agent, and heated to a temperature within a range from about
100.degree. C. to about 400.degree. C., preferably, from about
125.degree. C. to about 350.degree. C., and more preferably, from
about 150.degree. C. to about 300.degree. C., such as about
200.degree. C. or about 250.degree. C. The processing chamber may
produce an in situ plasma or be equipped with a remote plasma
source (RPS). In one embodiment, substrate 200 may be exposed to
the plasma (e.g., in situ or remotely) for a time period within a
range from about 2 seconds to about 60 seconds, preferably, from
about 3 seconds to about 30 seconds, preferably, from about 5
seconds to about 15 seconds, such as about 10 seconds. The plasma
may be produced at a power within the range from about 200 watts to
about 1,000 watts, preferably, from about 400 watts to about 800
watts. In one example, substrate 200 may be exposed to hydrogen gas
while a plasma is generated at 400 watts for about 10 seconds at
about 5 Torr. In another example, substrate 200 may be exposed to
ammonia gas while a plasma is generated at 800 watts for about 20
seconds at about 5 Torr. In another example, substrate 200 may be
exposed to a hydrogen and ammonia gaseous mixture while a plasma is
generated at 400 watts for about 15 seconds at about 5 Torr.
[0032] At step 120 of process 100, cobalt capping layer 216 may be
selectively deposited or formed on copper surfaces 214 while
leaving bare the exposed surfaces of dielectric layer 204 across
substrate field 210, as illustrated in FIG. 2C. Therefore, along
substrate field 210, cobalt capping layer 216 is selectively
deposited on copper surfaces 214 while leaving the surfaces of
dielectric layer 204 free or at least substantially free of cobalt
capping layer 216. Initially, cobalt capping layer 216 may be a
continuous layer or a discontinuous layer across copper surfaces
214, but is a continuous layer after multiple deposition
cycles.
[0033] Contaminants 218 may collect throughout substrate field 210,
such as on cobalt capping layer 216 as well as the surfaces of
dielectric layer 204, as depicted in FIG. 2C. Contaminants 218 may
include by-products from the deposition process, such as carbon,
organic residue, precursor residue, and other undesirable materials
collected on substrate field 210.
[0034] Substrate 200 may be exposed to a plasma formed in situ or
remotely during the post-treatment process at step 130 of process
100. The post-treatment process removes or reduces the amount of
contaminants from substrate 200 while further densifying cobalt
capping layer 216. The post-treatment process may expose substrate
200 and cobalt capping layer 216 to a reducing agent during the
plasma process. Reducing agent that are useful during the
post-treatment process include hydrogen (e.g., H.sub.2 or
atomic-H), ammonia (NH.sub.3), a hydrogen and ammonia mixture
(H.sub.2/NH.sub.3), nitrogen (e.g., N.sub.2 or atomic-N), hydrazine
(N.sub.2H.sub.4), derivatives thereof, plasmas thereof, or
combinations thereof. Cobalt capping layer 216 may be exposed to
the plasma during the post-treatment process for a time period
within a range from about 2 seconds to about 60 seconds,
preferably, from about 3 seconds to about 30 seconds, and more
preferably, from about 5 seconds to about 15 seconds.
[0035] In one example, the cobalt capping layer is exposed to a
hydrogen plasma, formed by igniting hydrogen gas in situ or
remotely of the processing chamber. In another example, the cobalt
capping layer is exposed to an ammonia plasma, formed by igniting
ammonia gas in situ or remotely of the processing chamber. In
another example, the cobalt capping layer is exposed to a
hydrogen/ammonia plasma, formed by igniting a mixture of hydrogen
gas and ammonia gas in situ or remotely of the processing
chamber.
[0036] A plasma may be generated external from the processing
chamber, such as by a remote plasma source (RPS) system, or
preferably, the plasma may be generated in situ a plasma capable
deposition chamber, such as a PE-CVD chamber during a plasma
treatment process, such as in steps 130 or 330. The plasma may be
generated from a microwave (MW) frequency generator or a radio
frequency (RF) generator. In a preferred example, an in situ plasma
is generated by a RF generator. The processing chamber may be
pressurized during the plasma treatment process at a pressure
within a range from about 0.1 Torr to about 80 Torr, preferably
from about 0.5 Torr to about 10 Torr, and more preferably, from
about 1 Torr to about 5 Torr. Also, the chamber or the substrate
may be heated to a temperature of less than about 500.degree. C.,
preferably within a range from about 100.degree. C. to about
450.degree. C., and more preferably, from about 150.degree. C. to
about 400.degree. C., for example, about 300.degree. C.
[0037] During treatment processes, a plasma may be ignited within
the processing chamber for an in situ plasma process, or
alternative, may be formed by an external source, such as a RPS
system. The RF generator may be set at a frequency within a range
from about 100 kHz to about 60 MHz. In one example, a RF generator,
with a frequency of 13.56 MHz, may be set to have a power output
within a range from about 100 watts to about 1,000 watts,
preferably, from about 250 watts to about 600 watts, and more
preferably, from about 300 watts to about 500 watts. In one
example, a RF generator, with a frequency of 350 kHz, may be set to
have a power output within a range from about 200 watts to about
2,000 watts, preferably, from about 500 watts to about 1,500 watts,
and more preferably, from about 800 watts to about 1,200 watts, for
example, about 1,000 watts. A surface of substrate may be exposed
to a plasma having a power per surface area value within a range
from about 0.01 watts/cm.sup.2 to about 10.0 watts/cm.sup.2,
preferably, from about 0.05 watts/cm.sup.2 to about 6.0
watts/cm.sup.2.
[0038] In another embodiment, step 120 is repeated at least once,
two times, or more. Step 120 may be performed one time to form a
single layer of cobalt capping layer 216, or performed multiple
times to form multiple layers of cobalt capping layer 216, such as
2, 3, 4, 5, or more layers of cobalt capping layer 216. In another
embodiment, steps 120 and 130 are sequentially repeated at least
once, if not, 2, 3, 4 or more times. Cobalt capping layer 216 may
be deposited having a thickness within a range from about 2 .ANG.
to about 30 .ANG., preferably, from about 3 .ANG. to about 25
.ANG., more preferably, from about 4 .ANG. to about 20 .ANG., and
more preferably, from about 5 .ANG. to about 10 .ANG., such as
about 7 .ANG. or about 8 .ANG.. In one example, two cycles of steps
120 and 130 and performed to form cobalt capping layer 216 with a
thickness of about 7 .ANG.. In another example, three cycles of
steps 120 and 130 and performed to form cobalt capping layer 216
with a thickness of about 8 .ANG..
[0039] Cobalt capping layer 216 may be deposited by thermal
decomposition of a cobalt containing precursor carried by an inert
gas during step 120. A reducing gas may be co-flowed or alternately
pulsed into the processing chamber along with the cobalt precursor.
The substrate may be heated to a temperature within a range from
about 50.degree. C. to about 600.degree. C., preferably, from about
100.degree. C. to about 500.degree. C., and more preferably, from
about 200.degree. C. to about 400.degree. C. Alternatively, cobalt
capping layer 216 may be deposited by exposing the substrate to a
cobalt containing precursor gas in an ALD or CVD process.
[0040] FIG. 3 depicts a flow-chart of process 300 which may be used
to form cobalt-containing materials, such as cobalt capping layer
216. In one embodiment, process 300 includes exposing a substrate
to a deposition gas to form a cobalt capping material (step 310),
optionally purging the deposition chamber (step 320), exposing the
substrate to a plasma treatment process (step 330), purging the
deposition chamber (step 340), and determining if a predetermined
thickness of the cobalt capping material has been formed on the
substrate (step 350). In one embodiment, the cycle of steps 310-350
may be repeated if the cobalt capping material has not been formed
having the predetermined thickness. In another embodiment, the
cycle of steps 310 and 330 may be repeated if the cobalt capping
material has not been formed having the predetermined thickness.
Alternately, process 300 may be stopped once the cobalt capping
material has been formed having the predetermined thickness.
[0041] In one embodiment, a method for capping a copper surface on
a substrate is provided which includes exposing the substrate to a
cobalt precursor gas and hydrogen gas to selectively form a cobalt
capping layer over the metallic copper surface while leaving
exposed the dielectric surface during a vapor deposition process,
and exposing the cobalt capping layer to a plasma and a reagent,
such as nitrogen, ammonia, hydrogen, an ammonia/nitrogen mixture,
or combinations thereof during a post-treatment process.
[0042] In another embodiment, a method for capping a copper surface
on a substrate is provided which includes depositing a cobalt
capping material over the metallic copper surface while leaving
exposed the dielectric surface during a deposition-treatment cycle.
In one example, the deposition-treatment cycle includes exposing
the substrate to a cobalt precursor gas to selectively form a first
cobalt layer over the metallic copper surface while leaving exposed
the dielectric surface during a vapor deposition process, exposing
the first cobalt layer to a plasma containing nitrogen, ammonia, an
ammonia/nitrogen mixture, or hydrogen during a treatment process.
The method further provides exposing the substrate to the cobalt
precursor gas to selectively form a second cobalt layer over the
first cobalt layer while leaving exposed the dielectric surface
during the vapor deposition process, and exposing the second cobalt
layer to the plasma during the treatment process.
[0043] In some examples, the method provides exposing the substrate
to the cobalt precursor gas to selectively form a third cobalt
layer over the second cobalt layer while leaving exposed the
dielectric surface during the vapor deposition process, and
exposing the third cobalt layer to the plasma during the treatment
process.
[0044] Suitable cobalt precursors for forming cobalt-containing
materials (e.g., metallic cobalt or cobalt alloys) by CVD or ALD
processes described herein include cobalt carbonyl complexes,
cobalt amidinates compounds, cobaltocene compounds, cobalt dienyl
complexes, cobalt nitrosyl complexes, derivatives thereof,
complexes thereof, plasma thereof, or combinations thereof. In some
embodiments, cobalt materials may be deposited by CVD and ALD
processes further described in commonly assigned U.S. Pat. No.
7,264,846 and U.S. Ser. No. 10/443,648, filed May 22, 2003, and
published as US 2005-0220998, which are herein incorporated by
reference.
[0045] In some embodiments, cobalt carbonyl compounds or complexes
may be utilized as cobalt precursors. Cobalt carbonyl compounds or
complexes have the general chemical formula
(CO).sub.xCo.sub.yL.sub.z, where X may be 1, 2, 3, 4, 5, 6, 7, 8,
9, 10, 11, or 12, Y may be 1, 2, 3, 4, or 5, and Z may be 1, 2, 3,
4, 5, 6, 7, or 8. The group L is absent, one ligand or multiple
ligands, that may be the same ligand or different ligands, and
include cyclopentadienyl, alkylcyclopentadienyl (e.g.,
methylcyclopentadienyl or pentamethylcyclopentadienyl),
pentadienyl, alkylpentadienyl, cyclobutadienyl, butadienyl,
ethylene, allyl (or propylene), alkenes, dialkenes, alkynes,
acetylene, bytylacetylene, nitrosyl, ammonia, derivatives thereof,
complexes thereof, plasma thereof, or combinations thereof. Some
exemplary cobalt carbonyl complexes include cyclopentadienyl cobalt
bis(carbonyl) (CpCo(CO).sub.2), tricarbonyl allyl cobalt
((CO).sub.3Co(CH.sub.2CH.dbd.CH.sub.2)), dicobalt hexacarbonyl
bytylacetylene (CCTBA, (CO).sub.6Co.sub.2(HC.ident.C.sup.tBu)),
dicobalt hexacarbonyl methylbytylacetylene
((CO).sub.6Co.sub.2(MeC.ident.C.sup.tBu)), dicobalt hexacarbonyl
phenylacetylene ((CO).sub.6Co.sub.2(HC.ident.CPh)), hexacarbonyl
methylphenylacetylene ((CO).sub.6Co.sub.2(MeC.ident.CPh)), dicobalt
hexacarbonyl methylacetylene ((CO).sub.6Co.sub.2(HC.ident.CMe)),
dicobalt hexacarbonyl dimethylacetylene
((CO).sub.6Co.sub.2(MeC.ident.CMe)), derivatives thereof, complexes
thereof, plasma thereof, or combinations thereof.
[0046] In another embodiment, cobalt amidinates or cobalt amido
complexes may be utilized as cobalt precursors. Cobalt amido
complexes have the general chemical formula (RR'N).sub.xCo, where X
may be 1, 2, or 3, and R and R' are independently hydrogen, methyl,
ethyl, propyl, butyl, alkyl, silyl, alkylsilyl, derivatives
thereof, or combinations thereof. Some exemplary cobalt amido
complexes include bis(di(butyldimethylsilyl)amido) cobalt
(((BuMe.sub.2Si).sub.2N).sub.2Co), bis(di(ethyidimethylsilyl)amido)
cobalt (((EtMe.sub.2Si).sub.2N).sub.2Co),
bis(di(propyidimethylsilyl)amido) cobalt
(((PrMe.sub.2Si).sub.2N).sub.2Co), bis(di(trimethylsilyl)amido)
cobalt (((Me.sub.3Si).sub.2N).sub.2Co),
tris(di(trimethylsilyl)amido) cobalt
(((Me.sub.3Si).sub.2N).sub.3Co), derivatives thereof, complexes
thereof, plasma thereof, or combinations thereof.
[0047] Some exemplary cobalt precursors include
methylcyclopentadienyl cobalt bis(carbonyl) (MeCpCo(CO).sub.2),
ethylcyclopentadienyl cobalt bis(carbonyl) (EtCpCo(CO).sub.2),
pentamethylcyclopentadienyl cobalt bis(carbonyl)
(Me.sub.5CpCo(CO).sub.2), dicobalt octa(carbonyl)
(Co.sub.2(CO).sub.8), nitrosyl cobalt tris(carbonyl)
((ON)Co(CO).sub.3), bis(cyclopentadienyl) cobalt,
(cyclopentadienyl) cobalt (cyclohexadienyl), cyclopentadienyl
cobalt (1,3-hexadienyl), (cyclobutadienyl) cobalt
(cyclopentadienyl), bis(methylcyclopentadienyl) cobalt,
(cyclopentadienyl) cobalt (5-methylcyclopentadienyl), bis(ethylene)
cobalt (pentamethylcyclopentadienyl), cobalt tetracarbonyl iodide,
cobalt tetracarbonyl trichlorosilane, carbonyl chloride
tris(trimethylphosphine) cobalt, cobalt
tricarbonyl-hydrotributylphosphine, acetylene dicobalt
hexacarbonyl, acetylene dicobalt pentacarbonyl triethylphosphine,
derivatives thereof, complexes thereof, plasma thereof, or
combinations thereof.
[0048] Suitable reagents, including reducing agents, that are
useful to form cobalt-containing materials (e.g., metallic cobalt,
cobalt capping layers, or cobalt alloys) by processes described
herein include hydrogen (e.g., H.sub.2 or atomic-H), atomic-N,
ammonia (NH.sub.3), hydrazine (N.sub.2H.sub.4), a hydrogen and
ammonia mixture (H.sub.2/NH.sub.3), borane (BH.sub.3), diborane
(B.sub.2H.sub.6), triethylborane (Et.sub.3B), silane (SiH.sub.4),
disilane (Si.sub.2H.sub.6), trisilane (Si.sub.3H.sub.8),
tetrasilane (Si.sub.4H.sub.10), methyl silane (SiCH.sub.6),
dimethylsilane (SiC.sub.2H.sub.8), phosphine (PH.sub.3),
derivatives thereof, plasmas thereof, or combinations thereof.
[0049] During step 140 of process 100, dielectric barrier layer 220
may be deposited over cobalt capping layer 216 and on substrate
200, as depicted in FIG. 2E. Dielectric barrier layer 220 having a
low dielectric constant may be deposited on substrate 200, across
substrate field 210, and over cobalt capping layer 216. Dielectric
barrier layer 220 may contain a low-k dielectric material, such as
silicon carbide, silicon nitride, silicon oxide, silicon
oxynitride, silicon carbide oxide or carbon doped silicon oxide
material, derivatives thereof, or combinations thereof. In one
example, BLOK.RTM. low-k dielectric material, available from
Applied Materials, Inc., located in Santa Clara, Calif., may be
utilized as a low-k dielectric material for dielectric barrier
layer 220. An example of a suitable material for dielectric barrier
layer 220 is a silicon carbide based film formed using CVD or
plasma enhanced CVD (PE-CVD) processes such as the processes
described in commonly assigned U.S. Pat. Nos. 6,537,733, 6,790,788,
and 6,890,850, which are herein incorporated by reference.
[0050] An ALD processing chamber used during embodiments described
herein is available from Applied Materials, Inc., located in Santa
Clara, Calif. A detailed description of an ALD processing chamber
may be found in commonly assigned U.S. Pat. Nos. 6,916,398 and
6,878,206, commonly assigned U.S. Ser. No. 10/281,079, filed on
Oct. 25, 2002, and published as U.S. Pub. No. 2003-0121608, and
commonly assigned U.S. Ser. Nos. 11/556,745, 11/556,752,
11/556,756, 11/556,758, 11/556,763, each filed Nov. 6, 2006, and
published as U.S. Pub. Nos. 2007-0119379, 2007-0119371,
2007-0128862, 2007-0128863, and 2007-0128864, which are hereby
incorporated by reference in their entirety. In another embodiment,
a chamber configured to operate in both an ALD mode as well as a
conventional CVD mode may be used to deposit cobalt-containing
materials is described in commonly assigned U.S. Pat. No.
7,204,886, which is incorporated herein by reference in its
entirety. A detailed description of an ALD process for forming
cobalt-containing materials is further disclosed in commonly
assigned U.S. Ser. No. 10/443,648, filed on May 22, 2003, and
published as U.S. Pub. No. 2005-0220998, and commonly assigned U.S.
Pat. No. 7,264,846, which are hereby incorporated by reference in
their entirety. In other embodiments, a chamber configured to
operate in both an ALD mode as well as a conventional CVD mode that
may be used to deposit cobalt-containing materials is the TXZ.RTM.
showerhead and CVD chamber available from Applied Materials, Inc.,
located in Santa Clara, Calif.
[0051] "Substrate surface" or "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 may be
performed include materials such as monocrystalline,
polycrystalline or amorphous silicon, strained silicon, silicon on
insulator (SOI), doped silicon, silicon germanium, germanium,
gallium arsenide, glass, sapphire, silicon oxide, silicon nitride,
silicon oxynitride, and/or carbon doped silicon oxides, such as
SiO.sub.xC.sub.y, for example, BLACK DIAMOND.RTM. low-k dielectric,
available from Applied Materials, Inc., located in Santa Clara,
Calif. Substrates may have various dimensions, such as 200 mm or
300 mm diameter wafers, as well as, rectangular or square panes.
Unless otherwise noted, embodiments and examples described herein
are preferably conducted on substrates with a 200 mm diameter or a
300 mm diameter, more preferably, a 300 mm diameter. Embodiments of
the processes described herein deposit cobalt silicide materials,
metallic cobalt materials, and other cobalt-containing materials on
many substrates and surfaces, especially, silicon-containing
dielectric materials. Substrates on which embodiments of the
invention may be useful include, but are not limited to
semiconductor wafers, such as crystalline silicon (e.g.,
Si<100> or Si<111>), silicon oxide, strained silicon,
silicon germanium, doped or undoped polysilicon, doped or undoped
silicon wafers, and patterned or non-patterned wafers. Substrates
may be exposed to a pre-treatment process to polish, etch, reduce,
oxidize, hydroxylate, anneal, and/or bake the substrate
surface.
[0052] While the foregoing is directed to embodiments of the
invention, other and further embodiments of the invention may be
devised without departing from the basic scope thereof, and the
scope thereof is determined by the claims that follow.
* * * * *