U.S. patent application number 14/975945 was filed with the patent office on 2016-04-14 for surface treatment to improve cctba based cvd co nucleation on dielectric substrate.
The applicant listed for this patent is Applied Materials, Inc.. Invention is credited to Avgerinos V. Gelatos, Bhushan N. Zope.
Application Number | 20160104639 14/975945 |
Document ID | / |
Family ID | 52666142 |
Filed Date | 2016-04-14 |
United States Patent
Application |
20160104639 |
Kind Code |
A1 |
Zope; Bhushan N. ; et
al. |
April 14, 2016 |
SURFACE TREATMENT TO IMPROVE CCTBA BASED CVD CO NUCLEATION ON
DIELECTRIC SUBSTRATE
Abstract
Embodiments of the present invention generally relate to a
method of forming a cobalt layer on a dielectric material without
incubation delay. Prior to depositing the cobalt layer using CVD,
the surface of the dielectric material is pretreated at a
temperature between 100.degree. C. and 250.degree. C. Since the
subsequent CVD cobalt process is also performed at between
100.degree. C. and 250.degree. C., one processing chamber is used
for pretreating the dielectric material and forming of the cobalt
layer. The combination of processing steps enables use of two
processing chambers to deposit cobalt.
Inventors: |
Zope; Bhushan N.; (Santa
Clara, CA) ; Gelatos; Avgerinos V.; (Redwood City,
CA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Applied Materials, Inc. |
Santa Clara |
CA |
US |
|
|
Family ID: |
52666142 |
Appl. No.: |
14/975945 |
Filed: |
December 21, 2015 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
14026147 |
Sep 13, 2013 |
9218980 |
|
|
14975945 |
|
|
|
|
Current U.S.
Class: |
257/751 |
Current CPC
Class: |
H01L 2924/00 20130101;
C23C 16/50 20130101; H01L 21/76879 20130101; H01L 21/76843
20130101; H01L 21/28556 20130101; H01L 21/28562 20130101; H01L
2924/0002 20130101; C23C 14/22 20130101; C23C 16/18 20130101; H01L
21/76841 20130101; H01L 21/76877 20130101; H01L 23/53257 20130101;
H01L 21/76814 20130101; H01L 21/76826 20130101; C23C 16/0281
20130101; H01L 2924/0002 20130101; C23C 16/0245 20130101 |
International
Class: |
H01L 21/768 20060101
H01L021/768 |
Claims
1. A method for forming a metal interconnect, comprising: placing a
substrate into a processing chamber; pretreating a surface of the
substrate at a temperature between 100.degree. C. and 250.degree.
C., wherein the pretreating the surface of the substrate comprises
exposing the surface to an ammonia or nitrogen plasma; and
depositing a cobalt layer on the pretreated surface.
2. The method of claim 1, wherein the monolayer of molecules
further comprises nitrogen.
3. The method of claim 1, wherein the pretreating the surface of
the substrate further comprises exposing the surface to a titanium
containing precursor gas prior to exposing the surface to the
ammonia or nitrogen plasma.
4. The method of claim 3, wherein the titanium containing precursor
gas comprises tetrakis(dimethylamino)titanium or titanium
tetrachloride.
5. The method of claim 1, wherein the pretreating the surface of
the substrate further comprises exposing the surface to a titanium
containing precursor gas after exposing the surface to the ammonia
or nitrogen plasma.
6. The method of claim 5, wherein the titanium containing precursor
gas comprises tetrakis(dimethylamino)titanium or titanium
tetrachloride.
7. The method of claim 1, wherein the cobalt layer is deposited by
a chemical vapor deposition process.
8. The method of claim 7, wherein an organometallic precursor gas
is used in the chemical vapor deposition process.
9. The method of claim 8, wherein the organometallic precursor gas
comprises dicobalt hexacarbonyl tertbutyl acetylene.
10. The method of claim 9, wherein the chemical vapor deposition is
performed at a temperature between 100.degree. C. and 250.degree.
C.
11. The method of claim 10, wherein the surface of the substrate
comprises silicon dioxide or a low-k dielectric.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a divisional of co-pending U.S. patent
application Ser. No. 14/026,147, filed on Sep. 13, 2013, which
herein is incorporated by reference.
BACKGROUND
[0002] 1. Field
[0003] Embodiments of the invention generally relate to the field
of semiconductor manufacturing processes, more particularly, to
methods for forming a contact metal layer on dielectric
substrate.
[0004] 2. Description of the Related Art
[0005] Semiconductor processing involves a number of different
chemical and physical processes whereby minute integrated circuits
are created on a substrate. Layers of materials which make up the
integrated circuit are created by chemical vapor deposition (CVD),
physical vapor deposition (PVD), epitaxial growth, and the like.
Some of the layers of material are patterned using photoresist
masks and wet or dry etching techniques. The substrate utilized to
form integrated circuits may be silicon, gallium arsenide, indium
phosphide, glass, or other appropriate material.
[0006] As feature sizes have become smaller, the cross section
dimensions of logic metal contacts and subsequent metal
interconnect layers are decreasing rapidly. CVD cobalt may be used
as metal deposition technique for application as metal
interconnects. Conventionally, a cobalt thin film is grown on
dielectric material such as silicon dioxide or low-k dielectric.
Use of organometallic precursors negates the need of a barrier
layer, which is used in alternate metal CVD processes utilizing
halide based chemistry. However, incubation (growth) of the cobalt
layer on the dielectric material is poor and results in
non-continuous growth. A titanium nitride (TiN) nucleation layer
may be formed on the dielectric material prior to CVD deposition of
cobalt layer. However, titanium nitride will not deposit on the
dielectric material at less than 300.degree. C. The cobalt layer is
deposited at a temperature between 100.degree. C. and 250.degree.
C. Thus, two processing chambers may be utilized for the
depositions of the nucleation layer and the cobalt layer.
[0007] Therefore, an improved method of forming a cobalt layer is
needed.
SUMMARY
[0008] Embodiments of the present invention generally relate to a
method of forming a cobalt layer on a dielectric material without
incubation delay. Prior to depositing the cobalt layer using CVD,
the surface of the dielectric material is pretreated at a
temperature between 100.degree. C. and 250.degree. C. Since the
subsequent CVD cobalt process is also performed at between
100.degree. C. and 250.degree. C., only one processing chamber is
used for the forming of the cobalt layer.
[0009] In one embodiment, a method for forming a metal interconnect
is disclosed. The method includes placing a substrate into a
processing chamber, pretreating a surface of the substrate at a
temperature between 100.degree. C. and 250.degree. C., wherein a
monolayer of molecules is formed on the surface of the substrate,
and depositing a metal layer on the pretreated surface.
[0010] In another embodiment, a transfer chamber connecting a
plurality of processing chambers is disclosed. The transfer chamber
connecting a plurality of processing chambers has a transfer
chamber, at least two cobalt chemical vapor deposition chambers, at
least one physical vapor deposition chamber, and at least one
plasma enhanced chemical vapor deposition chamber.
BRIEF DESCRIPTION OF THE DRAWINGS
[0011] So that the manner in which the above recited features of
the present 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.
[0012] FIG. 1 illustrates a cross sectional view of a substrate
having a metal interconnect formed thereon according to one
embodiment of the invention.
[0013] FIG. 2 illustrates a method for depositing a cobalt layer
according to one embodiment of the invention.
[0014] FIG. 3 is a chart showing a relationship between CVD cobalt
thickness and deposition time.
[0015] FIG. 4 is a schematic cross sectional view of a processing
chamber which may be adapted to perform the processes disclosed
herein.
[0016] FIG. 5 is a schematic top view of a multi-chamber processing
system which may be adapted to perform the processes disclosed
herein.
[0017] To facilitate understanding, identical reference numerals
have been used, where possible, to designate identical elements
that are common to the figures. It is contemplated that elements
disclosed in one embodiment may be beneficially utilized on other
embodiments without specific recitation.
DETAILED DESCRIPTION
[0018] Embodiments of the present invention generally relate to a
method of forming a cobalt layer on a dielectric material without
incubation delay. Prior to depositing the cobalt layer using CVD,
the surface of the dielectric material is pretreated at a
temperature between 100.degree. C. and 250.degree. C. Since the
subsequent CVD cobalt process is also performed at between
100.degree. C. and 250.degree. C., only one processing chamber is
used for the forming of the cobalt layer.
[0019] Referring to FIG. 1, in some embodiments, a device 100 may
include a metal interconnect structure 101, which may generally
comprise a substrate 102, a dielectric layer 104 and a metal layer
106. In some embodiments, the metal interconnect structure 101 may
be disposed within or atop the substrate 102. In such embodiments,
the metal interconnect structure 101 may be formed within a feature
108 formed, for example, in the dielectric layer 104 disposed over
the substrate 102.
[0020] The substrate 102 may be any substrate capable of having
material deposited thereon, such as a silicon substrate, for
example crystalline silicon (e.g., Si<100>or Si<111>),
silicon oxide, strained silicon, doped or undoped polysilicon, or
the like, a III-V compound substrate, a silicon germanium (SiGe)
substrate, an epi-substrate, a silicon-on-insulator (SOI)
substrate, a display substrate such as a liquid crystal display
(LCD), a plasma display, an electro luminescence (EL) lamp display,
a solar array, solar panel, a light emitting diode (LED) substrate,
a semiconductor wafer, or the like.
[0021] In some embodiments, the substrate 102 may include a p-type
or n-type region defined therein (not shown). The substrate 102 may
include other structures or features 108 at least partially formed
therein. For example, in some embodiments, the feature 108 (e.g., a
via, a trench, a dual damascene feature, high aspect ratio feature,
or the like) may be formed within the dielectric layer 104 through
any suitable process or processes, such as an etch process.
[0022] The dielectric layer 104 may contain silicon dioxide or a
low-k dielectric material, such as a silicon carbide oxide
material, or a carbon doped silicon oxide material. The dielectric
layer 104 may be formed via any process suitable to provide the
dielectric layer 104 having a desired thickness. Suitable processes
may include CVD, PVD, atomic layer deposition (ALD), and plasma
enhanced CVD (PECVD).
[0023] The metal layer 106 is a cobalt layer and is deposited using
CVD. Organometallic precursors may be used for the CVD process, and
one example of the organometallic precursors is dicobalt
hexacarbonyl tertbutyl acetylene (CCTBA). The CCTBA based CVD
cobalt is deposited at a temperature from about 100.degree. C. to
about 250.degree. C. To minimize impurities in the cobalt layer
106, the processing temperature may be in the range of 125.degree.
C.-175.degree. C. Conventionally, a nucleation layer such as a TiN
layer may be first deposited on the dielectric layer 104 and the
cobalt layer 106 is deposited on the TiN layer. TiN does not
deposit on the dielectric layer 104 at a temperature that is less
than 300.degree. C. The processing temperature of TiN deposition is
much higher than the processing temperature of cobalt deposition,
thus two processing chambers are used for any process using cobalt
as a metal interconnect material, causing loss of productivity by
decreasing system throughput. Depositing the cobalt layer 106
without the TiN nucleation layer may cause incubation delay.
Incubation delay, or growth delay, means the growth rate of the
cobalt layer 106 is very slow at the beginning of the deposition
process. To eliminate any incubation delay, the surface of the
dielectric layer 104 is pre-treated before the cobalt layer 106 is
deposited on the dielectric layer 104.
[0024] FIG. 2 illustrates a method 200 for depositing a cobalt
layer without any incubation delay according to one embodiment of
the invention. At step 202, the surface of the dielectric layer 104
is pretreated prior to the deposition of the cobalt layer 106 into
the feature 108. In one embodiment, the pretreatment includes
exposing the dielectric layer 104 to a precursor gas containing
titanium at process temperature used during CVD cobalt deposition.
The precursor gas may be tetrakis(dimethylamino)titanium (TDMAT),
titanium tetrachloride (TiCl.sub.4) or the like. The surface of the
dielectric layer 104 is exposed to the precursor gas at the same
temperature as the CVD cobalt deposition temperature, such as from
about 100.degree. C. to about 250.degree. C. In one embodiment, the
pretreatment and the CVD cobalt deposition have the same process
temperature, ranging from about 125.degree. C. to about 175.degree.
C. At these temperature ranges, no TiN layer is deposited; instead
a monolayer of the precursor molecules is deposited on the surface
of the dielectric layer 104, including the surface of dielectric
layer 104 inside the feature 108.
[0025] In another embodiment, the surface of the dielectric layer
104 is pretreated with an ammonia or nitrogen based plasma. The
plasma pretreatment is also performed at process temperature used
during CVD cobalt deposition. A monolayer of nitrogen molecules is
formed on the dielectric layer 104. In another embodiment, both
TDMAT exposure and ammonia or nitrogen plasma treatment are
utilized. The TDMAT exposure may be performed before the ammonia or
nitrogen plasma treatment, or performed after the ammonia or
nitrogen plasma treatment.
[0026] Next, at step 204, the cobalt layer 106 is deposited on the
dielectric layer 104, including on the dielectric layer 104 inside
the feature 108. The cobalt layer 106 is deposited using a CVD
process and the CVD process is performed in the chamber in which
the pretreatment process is performed. The precursor used in the
CVD process may be CCTBA and the cobalt layer 106 may have a
thickness of less than 10 nanometers. Pretreating the dielectric
surface 104 eliminated any incubation delay during CVD cobalt
deposition. In addition, the cobalt layer 106 deposited on the
pretreated dielectric surface has lower resistivity compared to
cobalt layers formed on untreated dielectric surface.
[0027] FIG. 3 is a chart 300 showing a relationship between CVD
cobalt layer thickness and deposition time for no pretreatment,
ammonia plasma treatment and TDMAT exposure treatment. As shown in
chart 300, both ammonia plasma and TDMAT exposure treatments result
in a thicker cobalt layer at early stage of the deposition
process.
[0028] FIG. 4 is a schematic cross sectional view of a processing
chamber 400 which may be adapted to perform the processes disclosed
herein. The processing chamber 400 may be a CVD chamber that is
adapted to perform the pretreatment step 202 and the CVD cobalt
deposition step 204, as described in FIG. 2. The chamber 400
comprises a chamber body 402 having sidewalls 404 and a bottom 406.
A liner, such as a quartz liner, may line the sidewalls 404 and the
bottom 406 of the chamber body 402 to provide thermal and/or
electrical insulation. An opening 408 in the chamber 400 provides
access for a robot (not shown) to deliver and retrieve substrates
410 to the chamber 100.
[0029] A substrate support 412 supports the substrate 410 in the
chamber 400 on a substrate receiving surface 411. The substrate
support 412 is mounted to a lift motor 414 to raise and lower the
substrate support 412 and a substrate 410 disposed thereon. A lift
plate 416 connected to a lift motor 418 is mounted in the chamber
and raises and lowers pins 420 movably disposed through the
substrate support 412. The pins 420 raise and lower the substrate
410 over the surface of the substrate support 412.
[0030] The substrate support 412 may be heated to heat the
substrate 410 disposed thereon. For example, the substrate support
412 may have an embedded heating element 422 to resistively heat
the substrate support 412 by applying an electric current from a
power supply (not shown). A temperature sensor 426, such as a
thermocouple, may be embedded in the substrate support 412 to
monitor the temperature of the substrate support 412. For example,
a measured temperature may be used in a feedback loop to control
electric current applied to the heating element 422 from a power
supply (not shown), such that the substrate temperature can be
maintained or controlled at a desired temperature or within a
desired temperature range. Alternatively, the substrate 410 may be
heated using radiant heat, such as by lamps.
[0031] A gas distribution system 430 is disposed at an upper
portion of the chamber body 402 to provide two gas flows
distributed in a substantially uniform manner over a substrate 410
disposed on the substrate receiving surface 411 in which the two
gas flows are delivered in separate discrete paths through the gas
distribution system 430. One gas flow path may be used for the
pretreatment step 202 while the other may be used for the CVD
cobalt deposition step 204. In the embodiment shown, the gas
distribution system 430 comprises a gas box 432, a blocker plate
460 positioned below the gas box 432, and a showerhead 470
positioned below the blocker plate 460. The gas distribution system
430 provides two gas flows through two discrete paths to a
processing region 428 defined between the showerhead 470 and the
substrate support 412.
[0032] The gas box 432 as used herein is defined as a gas manifold
coupling gas sources to the chamber. The gas box 432 comprises a
first gas channel 437 and a second gas channel 443 providing two
separate paths for the flow of gases through the gas box 432. The
first gas channel 437 comprises a first gas input 434 and a first
gas outlet 438. The first gas input is adapted to receive a first
gas from a first gas source 435 through valve 436. The first gas
outlet 438 is adapted to deliver the first gas to the top of the
blocker plate 460. The second gas channel 443 of the gas box 432
comprises a second gas input 440 and a second gas outlet 444. The
second gas input 440 is adapted to receive a second gas from a
second gas source 441 through valve 442. The second gas outlet 444
is adapted to deliver the second gas to top of the showerhead 470.
The term "gas" as used herein is intended to mean a single gas or a
gas mixture. The valves 436, 442 control delivery of the first gas
and the second gas into the first gas input 434 and the second gas
input 440 respectively. Gas sources 435, 441 may be adapted to
store a gas or liquid precursor in a cooled, heated, or maintained
at ambient environment. The gas lines fluidly coupling the gas
sources 435, 441 to the gas inputs 434, 440 may also be heated,
cooled, or at ambient temperature.
[0033] FIG. 5 is a schematic top view of a multi-chamber processing
system 500 which may be adapted to perform the processes disclosed
herein. Examples of suitable multi-chamber processing systems
include the ENDURA.RTM. and PRODUCER.RTM. processing systems,
commercially available from Applied Materials, Inc. of Santa Clara,
Calif. The system 500 generally includes load lock chambers 502,
504, for the transfer of substrates (such as substrates 102
described above) into and out from the system 500. Since the system
500 is operated under vacuum, the load lock chambers 502, 504 may
be "pumped down" to maintain to facilitate entry and egress of
substrates to the system. A first robot 510 disposed in a first
transfer chamber 520 may transfer the substrate between the load
lock chambers 502, 504, processing chambers 512, 514, passthrough
chambers 522, 524, and other processing chambers 516, 518. Each
processing chamber 512, 514, 516, 518 may be outfitted to perform a
number of substrate processing operations such as ALD, CVD, PVD,
etch, preclean, degas, orientation and other substrate processes.
The passthrough chambers 522, 524 typically are used for cool down
of the substrates.
[0034] The passthrough chambers 522, 524 are connected to a second
transfer chamber 540. The second transfer chamber 540 is connected
to a plurality of processing chambers. In one embodiment,
processing chambers 532, 534, 536 and 538 are connected to the
second transfer chamber 540. An optional anneal chamber (not shown)
may be connected to the second transfer chamber 540. A second robot
530 disposed in the second transfer chamber 540 may transfer the
substrate between processing chambers 532, 534, 536, 538 and the
passthrough chambers 522, 524.
[0035] In one embodiment, the processing chambers 532, 534, 536,
538 include essentially at least two CVD cobalt deposition
chambers, at least one PVD chamber, and at least one plasma
enhanced CVD chamber. The at least two CVD cobalt deposition
chambers may be the processing chamber 400 described above. In one
embodiment, processing chambers 534, 536 are the processing
chambers that are adapted to perform both the pretreatment process
and the CVD cobalt deposition, such as the processing chamber 400.
The processing chamber 532 is a PVD chamber used for PVD cobalt
deposition. The processing chamber 538 is a plasma processing
chamber such as a plasma enhanced CVD chamber used for contact
applications. Conventional method of forming a TiN nucleation layer
prior to CVD cobalt deposition would utilize an additional
processing chamber, leaving only one CVD cobalt deposition chamber
connected to the transfer chamber 530. Since CVD cobalt deposition
is relatively slow, having two pretreatment/CVD cobalt deposition
processing chambers helps increasing throughput.
[0036] In summary, a single processing chamber is utilized to
perform both pretreatment of the dielectric layer and CVD cobalt
deposition. The pretreatment of the dielectric layer includes
exposing the dielectric layer to a TDMAT precursor gas or to an
ammonia plasma or a nitrogen plasma. The processing temperature for
the pretreatment and the CVD cobalt deposition may be the same.
Pretreating the dielectric layer prior to CVD cobalt deposition
eliminates incubation delay. In addition, throughput is increased
since two CVD cobalt deposition chambers may be included in a
processing system.
[0037] While the foregoing is directed to embodiments of the
present 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.
* * * * *