U.S. patent application number 15/649248 was filed with the patent office on 2018-01-18 for cvd mo deposition by using moocl4.
The applicant listed for this patent is Entegris, Inc.. Invention is credited to Richard Assion, Thomas H. Baum, Philip S.H. Chen, Bryan Hendrix, Shuang Meng, Robert Wright.
Application Number | 20180019165 15/649248 |
Document ID | / |
Family ID | 59579905 |
Filed Date | 2018-01-18 |
United States Patent
Application |
20180019165 |
Kind Code |
A1 |
Baum; Thomas H. ; et
al. |
January 18, 2018 |
CVD Mo DEPOSITION BY USING MoOCl4
Abstract
A method of forming a molybdenum-containing material on a
substrate is described, in which the substrate is contacted with
molybdenum oxytetrachloride (MoOCl.sub.4) vapor under vapor
deposition conditions, to deposit the molybdenum-containing
material on the substrate. In various implementations, a diborane
contact of the substrate may be employed to establish favorable
nucleation conditions for the subsequent bulk deposition of
molybdenum, e.g., by chemical vapor deposition (CVD) techniques
such as pulsed CVD.
Inventors: |
Baum; Thomas H.; (Billerica,
MA) ; Chen; Philip S.H.; (Billerica, MA) ;
Wright; Robert; (Billerica, MA) ; Hendrix; Bryan;
(Billerica, MA) ; Meng; Shuang; (Billerica,
MA) ; Assion; Richard; (Billerica, MA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Entegris, Inc. |
Billerica |
MA |
US |
|
|
Family ID: |
59579905 |
Appl. No.: |
15/649248 |
Filed: |
July 13, 2017 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
62362582 |
Jul 14, 2016 |
|
|
|
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
H01L 21/28568 20130101;
C23C 16/06 20130101; H01L 21/76843 20130101; H01L 21/76876
20130101; C23C 16/45553 20130101; C23C 16/0272 20130101; C23C
16/045 20130101; H01L 21/28556 20130101; H01L 2221/1089 20130101;
H01L 21/7685 20130101; C23C 16/14 20130101; H01L 21/76877 20130101;
H01L 21/32051 20130101 |
International
Class: |
H01L 21/768 20060101
H01L021/768; H01L 21/285 20060101 H01L021/285; C23C 16/06 20060101
C23C016/06 |
Claims
1. A method of forming a molybdenum-containing material on a
substrate, comprising contacting the substrate with molybdenum
oxytetrachloride (MoOCl.sub.4) vapor under vapor deposition
conditions, to deposit the molybdenum-containing material on the
substrate.
2. The method of claim 1, comprising establishing a nucleation
surface on the substrate and wherein said contacting of the
substrate with molybdenum oxytetrachloride (MoOCl.sub.4) vapor
comprises contacting the nucleation surface of the substrate with
molybdenum oxytetrachloride (MoOCl.sub.4) vapor to deposit the
molybdenum-containing material on the substrate.
3. The method of claim 2, wherein establishing the nucleation
surface on the substrate comprises contacting the substrate with
diborane vapor and optionally separately with molybdenum
oxytetrachloride (MoOCl.sub.4) vapor.
4. The method of claim 3, wherein establishing the nucleation
surface comprises a plurality of cycles of contacting the substrate
with diborane vapor and separately with molybdenum oxytetrachloride
(MoOCl.sub.4) vapor.
5. The method of claim 3, wherein the contact of the titanium
nitride layer with diborane vapor is conducted at temperature in a
range of from 300.degree. C. to 450.degree. C.
6. The method of claim 1, wherein the vapor deposition conditions
are pulsed vapor deposition conditions.
7. The method of claim 1, wherein the vapor conditions are selected
such that the deposited molybdenum-containing material has a
resistivity of at most 20 .mu..OMEGA.cm.
8. The method of claim 1, wherein the molybdenum-containing
material is deposited at a temperature in the range of from
400.degree. C. to 600.degree. C.
9. The method of claim 1, comprising volatilizing molybdenum
oxytetrachloride (MoOCl.sub.4) to form said molybdenum
oxytetrachloride (MoOCl.sub.4) vapor.
10. The method of claim 1, wherein said vapor deposition conditions
comprise a reducing ambient so that the molybdenum-containing
material comprises elemental molybdenum material.
11. The method of claim 1, wherein the molybdenum-containing
material comprises molybdenum oxide.
12. The method of claim 1, wherein the substrate comprises one or
more of TiN, Mo, MoC, B, SiO.sub.2, W, and WCN.
13. The method of claim 1, wherein: the substrate comprises a
semiconductor device substrate comprising silicon dioxide having a
titanium nitride layer thereon; the method comprises forming a
nucleation surface on the titanium nitride layer; and the
molybdenum-containing material is deposited on the nucleation
layer.
14. The method of claim 13, wherein the nucleation surface is
formed by pulsed CVD or ALD deposition comprising contact of the
titanium nitride layer with diborane vapor and separately with
molybdenum oxytetrachloride (MoOCl.sub.4) vapor.
15. The method of claim 1 carried out in a process for making a
semiconductor device on the substrate.
16. The method of claim 15, wherein the semiconductor device
comprises at least one of a DRAM device and a 3-D NAND device.
17. The method of claim 1, wherein the substrate comprises a via in
which the molybdenum-containing material is deposited.
18. The method of claim 1, wherein the molybdenum-containing
material is deposited on the substrate at step coverage of from 90%
to 110%.
19. A method of forming a molybdenum-containing material on a
semiconductor device substrate comprising silicon dioxide having a
titanium nitride layer thereon, the method comprising: forming a
nucleation surface on the titanium nitride layer by contacting the
titanium nitride layer with diborane vapor, contacting the
nucleation surface with molybdenum oxytetrachloride (MoOCl.sub.4)
vapor under vapor deposition conditions, to deposit the
molybdenum-containing material on the substrate, wherein the vapor
conditions are selected such that the deposited
molybdenum-containing material has a resistivity of at most 20
.mu..OMEGA.cm.
20. A method of forming a molybdenum-containing material on a
substrate, comprising contacting the substrate with diborane under
contacting conditions establishing nucleation surface on the
substrate, and depositing molybdenum on the nucleation surface by a
chemical vapor deposition process utilizing molybdenum
oxytetrachloride (MoOCl.sub.4) precursor in the presence of
hydrogen, to produce the molybdenum-containing material on the
substrate.
Description
FIELD
[0001] The present disclosure relates to vapor deposition of
molybdenum-containing material. In particular, though not
exclusively, the present disclosure relates to the use of
molybdenum oxytetrachloride (MoOCl.sub.4) as a precursor for such
deposition.
DESCRIPTION OF RELATED ART
[0002] In consequence of its characteristics of extremely high
melting point, low coefficient of thermal expansion, low
resistivity, and high thermal conductivity, molybdenum is
increasingly utilized in the manufacture of semiconductor devices,
including use in diffusion barriers, electrodes, photomasks, power
electronics substrates, low-resistivity gates, and
interconnects.
[0003] Such utility has motivated efforts to achieve deposition of
molybdenum films for such applications that is characterized by
high conformality of the deposited film and high deposition rate to
accommodate efficient high-volume manufacturing operations. This in
turn has informed efforts to develop improved molybdenum source
reagents useful in vapor deposition operations, as well as improved
process flows utilizing such reagents.
[0004] Molybdenum pentachloride is most commonly used as a
molybdenum source for chemical vapour deposition of
molybdenum-containing material. However, there remains a need to
achieve deposition of molybdenum-containing material with higher
deposition rates to accommodate efficient high-volume manufacturing
operations.
SUMMARY
[0005] The present disclosure relates to vapor deposition of
molybdenum-containing material, and more specifically to the use of
molybdenum oxytetrachloride (MoOCl.sub.4) as a source reagent for
such vapor deposition, as well as to processes and devices
employing molybdenum oxytetrachloride (MoOCl.sub.4) as a source
reagent.
[0006] In one aspect, the disclosure relates to a method of forming
a molybdenum-containing material on a substrate, comprising
contacting the substrate with molybdenum oxytetrachloride
(MoOCl.sub.4) vapor under vapor deposition conditions, to deposit
the molybdenum-containing material on the substrate.
[0007] In various embodiments, the disclosure relates to a method
of forming a molybdenum-containing material on a substrate,
comprising contacting the substrate with diborane under contacting
conditions establishing nucleation surface on the substrate, and
depositing molybdenum on the nucleation surface by a vapor
deposition process utilizing molybdenum oxytetrachloride
(MoOCl.sub.4) precursor, to produce the molybdenum-containing
material on the substrate.
[0008] Other aspects, features and embodiments of the disclosure
will be more fully apparent from the ensuing description and
appended claims.
BRIEF DESCRIPTION OF THE DRAWINGS
[0009] FIG. 1 is a graph of the thermogravimetric analysis (TGA) of
molybdenum oxytetrachloride.
[0010] FIG. 2 is a schematic cross-sectional elevation view of a
semiconductor device structure comprising molybdenum-containing
material deposited in accordance with an embodiment of the present
disclosure.
[0011] FIG. 3 shows a molybdenum oxytetrachloride
(MoOCl.sub.4)/hydrogen (H.sub.2) deposition curve illustrating
results from Example 1.
[0012] FIG. 4 is a graph of resistivity, as a function of
thickness, for deposition of molybdenum by a MoOCl.sub.4/H.sub.2
process in accordance with Example 1.
[0013] FIG. 5 and FIG. 6 are scanning electron micrograph (SEM)
images of a deposited molybdenum film formed in accordance with
Example 2.
[0014] FIG. 7 is a graph of molybdenum thickness as a function of
deposition time for deposition of molybdenum by a
MoOCl.sub.4/H.sub.2 process in accordance with Example 3.
[0015] FIG. 8 is a graph of film resistivity as a function of
molybdenum thickness for molybdenum deposition conducted by a
MoOCl.sub.4/H.sub.2 process in accordance with Example 4.
[0016] FIG. 9 is a graph comparing deposition rate as a function of
run number, for molybdenum deposition in accordance with Example
5.
[0017] FIG. 10 is a graph comparing film resistivity of deposited
molybdenum films as a function of molybdenum film thickness in
accordance with Example 6.
[0018] FIG. 11 is a graph of molybdenum film thickness, as a
function of diborane soak time illustrating results from Example
7.
[0019] FIGS. 12 and 13 are SEM micrographs of film depositions
formed in Example 8.
[0020] FIGS. 14 and 15 are SEM images of deposited films in vias
formed in Example 9.
[0021] FIG. 16 is a graph of molybdenum thickness and resistivity
as a function of diborane soak time for a deposition process in
accordance with Example 10.
[0022] FIG. 17 is a graph of molybdenum thickness and resistivity
as a function of MoOCl.sub.4/H.sub.2 exposure time, for a
deposition process in accordance with Example 11.
[0023] FIG. 18 is an SEM image of a molybdenum film deposited in
accordance with Example 12.
[0024] FIG. 19 is an SEM cross-section image of a molybdenum film
deposited in accordance with Example 12.
[0025] FIG. 20 is a graph of molybdenum thickness and resistivity
as a function of stage temperature, showing a reaction rate limited
regime for the MoOCl.sub.4/H.sub.2 process without diborane
nucleation, according to Example 13.
[0026] FIG. 21 is a graph of molybdenum thickness and resistivity
as a function of stage temperature, showing a reaction rate limited
regime for the MoOCl.sub.4/H.sub.2 process with diborane
nucleation, according to Example 13.
[0027] FIG. 22 is an Arrhenius plot (K=A.sup.e-Ea/RT) of activation
energy for the MoOCl.sub.4/H.sub.2 reaction, as conducted without
nucleation (.DELTA.), and as conducted with nucleation
(.smallcircle.).
[0028] FIGS. 23 and 24 show step coverage on a via structure by a
nucleation and CVD bulk molybdenum deposition MoOCl.sub.4/H.sub.2
process, as conducted in Example 15.
[0029] FIGS. 25, 26, and 27 show respective via structures
deposited with molybdenum in accordance with Example 16.
[0030] FIGS. 28, 29, and 30 show respective via structures
deposited with molybdenum in accordance with Example 17.
[0031] FIGS. 31, 32, and 33 show respective via structures
deposited with molybdenum in accordance with Example 18.
[0032] FIGS. 34, 35, and 36 are SEM images of a via structure
deposited with molybdenum in accordance with Example 19.
[0033] FIGS. 37 and 38 are SEM images of a via structure deposited
with molybdenum in accordance with Example 20.
[0034] FIGS. 39 and 40 are SEM images of a via structure deposited
with molybdenum in accordance with Example 21.
DETAILED DESCRIPTION
[0035] The present disclosure relates to vapor deposition of
molybdenum, and to use of molybdenum oxytetrachloride (MoOCl.sub.4)
for such deposition, e.g., in the manufacture of semiconductor
devices in which molybdenum films of superior conformality and
performance properties are desired.
[0036] In accordance with the present disclosure, molybdenum
oxytetrachloride (MoOCl.sub.4) has been found in vapor deposition
processes such as chemical vapor deposition to provide low
resistivity, high deposition rate films of a highly conformal
character.
[0037] The disclosure relates in one aspect to a method of forming
a molybdenum-containing material on a substrate, comprising
contacting the substrate with molybdenum oxytetrachloride
(MoOCl.sub.4) vapor under vapor deposition conditions, to deposit
the molybdenum-containing material on the substrate.
[0038] It has been found that, in various embodiments of the
disclosure, the use of molybdenum oxytetrachloride (MoOCl.sub.4) as
a precursor for vapor deposition of molybdenum-containing material
on substrates can provide a surprisingly high extent of
conformality, approaching 100% conformality, as determined by
cross-sectional scanning electron microscopy imaging techniques.
Advantageously, (MoOCl.sub.4), deposition of molybdenum
oxytetrachloride (MoOCl.sub.4) can proceed at higher rates than
deposition of molybdenum pentachloride (MoCl.sub.5). Furthermore,
surprisingly despite the presence of oxygen in the structure of
molybdenum oxytetrachloride (MoOCl.sub.4), the
molybdenum-containing material can have low resistivity and oxygen
content.
[0039] In various embodiments, the method comprises establishing a
nucleation surface on the substrate and said contacting of the
substrate with molybdenum oxytetrachloride (MoOCl.sub.4) vapor
comprises contacting the nucleation surface of the substrate with
molybdenum oxytetrachloride (MoOCl.sub.4) vapor to deposit the
molybdenum-containing material on the substrate.
[0040] A nucleation surface may advantageously facilitate
deposition of low resistivity molybdenum-containing material on the
substrate at lower temperatures.
[0041] Establishing the nucleation surface on the substrate may
suitably comprise contacting the substrate with diborane vapor and
optionally separately with molybdenum oxytetrachloride
(MoOCl.sub.4) vapor. Advantageously, establishing the nucleation
surface may comprise a plurality of cycles of contacting the
substrate with diborane vapor and separately with molybdenum
oxytetrachloride (MoOCl.sub.4) vapor. In various embodiments,
contact of the titanium nitride layer with diborane vapor is
conducted at temperature in a range of from 300.degree. C. to
450.degree. C.
[0042] Advantageously, the vapor deposition conditions may be
pulsed. It has been found that this can improve step coverage of
the deposition. Suitably the "pulse" and "purge" time of pulsed
deposition may each independently be in the range of from 1 to 20
seconds.
[0043] In various embodiments, the vapor conditions are selected
such that the deposited molybdenum-containing material has a
resistivity of at most 20 .mu..OMEGA.cm, optionally at most 15
.mu..OMEGA.cm.
[0044] Suitably, the molybdenum-containing material may be
deposited at a (stage) temperature in the range of from 400.degree.
C. to 750.degree. C., or in the range of from 400.degree. C. to
600.degree. C., or in the range of from 400.degree. C. to
575.degree. C. Suitably, the molybdenum-containing material may be
deposited at a (stage) temperature in the range of from 450.degree.
C. to 750.degree. C., or in the range of from 450.degree. C. to
600.degree. C., or in the range of from 450.degree. C. to
575.degree. C. Suitably, the molybdenum-containing material may be
deposited at a (stage) temperature in the range of from 500.degree.
C. to 750.degree. C., or in the range of from 500.degree. C. to
600.degree. C., or in the range of from 500.degree. C. to
575.degree. C.
[0045] In various embodiments, the vapor deposition conditions
comprise an inert atmosphere, save for the optional presence of a
reducing agent such as hydrogen. Suitably, the molybdenum
oxytetrachloride (MoOCl.sub.4) vapor may be deposited in the
substantial absence of other metal vapors.
[0046] The method may comprise volatilizing molybdenum
oxytetrachloride (MoOCl.sub.4) to form the molybdenum
oxytetrachloride (MoOCl.sub.4) vapor for the vapor deposition
operation. The vapor deposition conditions may be of any suitable
type, and may for example comprise a reducing ambient so that the
molybdenum-containing material comprises elemental molybdenum
material. The molybdenum-containing material may comprise, or
alternatively consist, or consist essentially of, elemental
molybdenum, or molybdenum oxide, or other molybdenum-containing
material.
[0047] The substrate utilized in the method of the disclosure may
be of any suitable type, and may for example comprise a
semiconductor device substrate, e.g., a silicon substrate, a
silicon dioxide substrate, or other silicon-based substrate. In
various embodiments, the substrate may comprise one or more of TiN,
Mo, MoC, B, SiO.sub.2, W, and WCN.
[0048] Advantageously, for example in the case of an oxide
substrate such as silicon dioxide, or alternatively a silicon or
polysilicon substrate, the substrate may be processed or fabricated
to include a barrier layer thereon, e.g. titanium nitride, for
subsequently deposited material. By way of illustration, the
substrate may comprise a nucleation layer on a titanium nitride
layer, with the molybdenum-containing material being deposited on
the nucleation layer in the appertaining process flow sequence.
[0049] Such a nucleation layer or surface may for example be formed
by pulsed CVD or ALD or other vapor deposition technique, and the
formation of such a nucleation layer may be carried out by
contacting of the titanium nitride layer with diborane vapor and
separately with molybdenum oxytetrachloride (MoOCl.sub.4) vapor.
The respective diborane vapor and molybdenum oxytetrachloride
(MoOCl.sub.4) vapor contacting steps may be carried out
alternatingly and repetitively for as many cycles as are desired to
form the nucleation layer of desired thickness. The process
conditions for such nucleation layer formation may comprise any
suitable desired temperature, pressure, flow rate, and other
process conditions. In various embodiments, the contact of the
titanium nitride layer with diborane vapor is conducted at
temperature in a range of from 300.degree. C. to 450.degree. C. In
various embodiments, the contact of the titanium nitride layer with
molybdenum oxytetrachloride (MoOCl.sub.4) vapor is conducted at
temperature in a range of from 400.degree. C. to 575.degree. C., or
another range as defined hereinabove for (MoOCl.sub.4) vapor
deposition.
[0050] Subsequent to formation of a nucleation layer by contact of
a substrate with diborane vapor and separately with molybdenum
oxytetrachloride (MoOCl.sub.4) vapor, the molybdenum-containing
material can be deposited on the nucleation layer, to form a bulk
deposit of elemental molybdenum or molybdenum oxide or other
molybdenum-containing compound or composition.
[0051] In various embodiments, the molybdenum-containing material
is deposited on the nucleation layer or surface at temperature in a
range of from 400.degree. C. to 575.degree. C. or another range as
defined hereinabove for (MoOCl.sub.4) vapor deposition. The process
may be carried out, so that the vapor deposition conditions produce
deposition of elemental molybdenum as the molybdenum-containing
material on the nucleation layer of the substrate. The vapor
deposition conditions may be of any suitable character, and may for
example comprise presence of hydrogen or other reducing gas, to
form a bulk layer of elemental molybdenum on the nucleation
layer.
[0052] More generally, the broad method of forming a
molybdenum-containing material on a substrate in accordance with
the present disclosure may comprise vapor deposition conditions
comprising presence of hydrogen or other reducing gas. The
molybdenum-containing material may be deposited on the barrier
layer or nucleation layer or surface in the presence or absence of
hydrogen. For example, the barrier layer may be constituted by
titanium nitride, and the titanium nitride layer may be contacted
with molybdenum oxytetrachloride (MoOCl.sub.4) vapor in the
presence of hydrogen.
[0053] It will be appreciated that the method of the present
disclosure may be carried out in numerous alternative ways, and
under a wide variety of process conditions. The method of the
disclosure may for example be carried out in a process for making a
semiconductor device on the substrate. The semiconductor device may
be of any suitable type, and may for example comprise a DRAM
device, 3-D NAND device, or other device or device precursor
structure. In various embodiments, the substrate may comprise a via
in which the molybdenum-containing material is deposited. The via
may for example have an aspect ratio of depth to lateral dimension
that is in a range of from 20:1 to 30:1.
[0054] The process chemistry for depositing molybdenum-containing
material in accordance with the present disclosure may include
deposition of elemental molybdenum, Mo(0), by the reaction
MoOCl4+3H2.fwdarw.Mo+4 HCl+H2O. A nucleation layer or surface
formed as described hereinabove by successive contacting of the
substrate with diborane and MoOCl.sub.4 to form the nucleation
layer may involve the formation reaction of
2MoOCl.sub.4+B.sub.2H.sub.6.fwdarw.2Mo+2BOCl+6HCl.
[0055] The molybdenum-containing material deposited in accordance
with the method of the present disclosure may be characterized by
any appropriate evaluation metrics and parameters, such as
deposition rate of the molybdenum-containing material, film
resistivity of the deposited molybdenum-containing material, film
morphology of the deposited molybdenum-containing material, film
stress of the deposited molybdenum-containing material, step
coverage of the material, and the process window or process
envelope of appropriate process conditions. Any appropriate
evaluation metrics and parameters may be employed, to characterize
the deposited material and correlate same to specific process
conditions, to enable mass production of corresponding
semiconductor products.
[0056] In various embodiments, the disclosure relates to a method
of forming a molybdenum-containing material on a substrate,
comprising contacting the substrate with diborane under contacting
conditions establishing nucleation surface on the substrate, and
depositing molybdenum on the nucleation surface by a vapor
deposition process utilizing molybdenum oxytetrachloride
(MoOCl.sub.4) precursor, to produce the molybdenum-containing
material on the substrate.
[0057] Such method may be carried out in any suitable manner as
variously described herein. In specific embodiments, such method
may be conducted with a vapor deposition process comprising
chemical vapor deposition, e.g., pulsed chemical vapor deposition.
The method may be carried out so that the resulting
molybdenum-containing material is composed essentially of elemental
molybdenum, and in various embodiments the molybdenum may be
deposited on the nucleation surface in the presence of hydrogen or
other suitable reducing gas. The method may be carried out in the
manufacture of a semiconductor product, such as a DRAM device, or a
3-D NAND device.
[0058] Generally, the methods of the present disclosure for forming
molybdenum-containing
[0059] material on a substrate may be carried out to achieve
deposition of the molybdenum-containing material at high levels of
step coverage, e.g., step coverage of from 90 to 110%.
[0060] The features and advantages of the methodology of the
present disclosure will be more fully apparent from the ensuing
description of illustrative embodiments and illustrative examples
hereinafter set forth.
[0061] Referring firstly to FIG. 1, there is shown a graph of the
thermogravimetric analysis (TGA) of molybdenum oxytetrachloride,
plotted as weight percent as a function of temperature, in degrees
Centigrade, showing the characteristics of the thermal behavior of
molybdenum oxytetrachloride. Notably, the T50 of molybdenum
oxytetrachloride (MoOCl.sub.4) is approximately 20.degree. C. lower
than that of molybdenum pentachloride (MoCl.sub.5).
[0062] With reference to FIG. 2 a semiconductor device structure
comprising molybdenum-containing material deposited in accordance
with an embodiment of the present disclosure includes a base layer
of silicon dioxide (SiO.sub.2), overlying which is a barrier layer
of titanium nitride (TiN), over which a nucleation layer has been
formed by contact of the substrate with molybdenum oxytetrachloride
(MoOCl.sub.4) and diborane, with a layer of elemental molybdenum
(Mo) as an upper layer deposited on the nucleation layer from
molybdenum oxytetrachloride (MoOCl.sub.4) in the presence of
hydrogen (H.sub.2).
[0063] The FIG. 2 semiconductor device may be fabricated by the
following sequence of process steps on the substrate comprising the
titanium nitride barrier layer on the silicon dioxide base
layer.
[0064] Step 1: contacting the barrier layer (TiN layer) of the
substrate with a pulse of diborane (B.sub.2H.sub.6), for example at
temperature in a range of from 300 to 450.degree. C.;
[0065] Step 2; pumping/purging the deposition chamber;
[0066] Step 3: contacting the barrier layer (TiN layer) of the
substrate with a pulse of molybdenum pentachloride (MoCl.sub.5) or
molybdenum oxytetrachloride (MoOCl.sub.4) vapor, in the presence of
hydrogen (H2) or argon (Ar), for example at temperature on the
order of 500.degree. C.;
[0067] Step 4; pumping/purging the deposition chamber;
[0068] Step 5: repeating Steps 1-4 (optional) to form a nucleation
layer of desired characteristics; and
[0069] Step 6: depositing bulk molybdenum on the nucleation layer,
by contact of the substrate with molybdenum oxytetrachloride
(MoOCl.sub.4) vapor, in the presence of hydrogen (H.sub.2), for
example at temperature on the order of 500.degree. C.
[0070] Steps 1 to 5 are optional and may be left out if no
nucleation layer is required.
Example 1--Deposition Rate Study
[0071] A chemical vapor deposition (CVD) molybdenum deposition with
molybdenum oxytetrachloride (MoOCl.sub.4)/hydrogen (H.sub.2) was
carried out utilizing the following process conditions: a
700.degree. C. stage on which substrate was maintained; a
70.degree. C. ampoule from which the molybdenum oxytetrachloride
(MoOCl.sub.4) precursor was dispensed for the vapor deposition
operation; 60 torr pressure in the vapor deposition operation; 50
standard cubic centimeter per minute (sccm) argon carrier gas flow,
and 2000 standard cubic feet per minute (sccm) of hydrogen
(H.sub.2).
[0072] Results of the deposition are shown in FIG. 3 and FIG. 4.
The data showed that the chemical vapor deposition (CVD) molybdenum
oxytetrachloride (MoOCl.sub.4)/hydrogen (H.sub.2) deposition
process at 700.degree. C. exhibited high deposition rate on the
order of about 110 .ANG./minute with the ampoule set at temperature
of 70.degree. C.
Example 2--SEM Study
[0073] FIG. 5 and FIG. 6 are scanning electron micrograph (SEM)
images of a deposited molybdenum film formed by CVD molybdenum
oxytetrachloride (MoOCl.sub.4)/hydrogen (H.sub.2) deposition
process involving the following process conditions: substrate=50
.ANG. TiN; ampoule temperature=70.degree. C.; stage
temperature=700.degree. C.; pressure=60 torr; argon carrier gas
flow rate=50 sccm; argon purge gas flow rate=0 sccm; hydrogen gas
flow rate=2000 sccm; deposition time=300 seconds; TiN thickness
prior to deposition=70.9 .ANG.; TiN thickness subsequent to
deposition=61.8 .ANG.; molybdenum thickness=600.1 .ANG.; and
resistivity of the deposited molybdenum=15.1 .mu..OMEGA.cm. FIG. 5
and FIG. 6 show a uniformly deposited molybdenum film with
relatively large grain size.
Example 3--Temperature and Thickness Study
[0074] FIG. 7 is a graph of molybdenum thickness, in .ANG.ngstroms,
as a function of deposition time, in seconds, for deposition of
molybdenum by MoOCl.sub.4/H.sub.2 process, ampoule temperature of
70.degree. C., pressure of 60 torr, argon carrier gas flow rate of
50 sccm, and hydrogen gas flow rate of 2000 sccm, as carried out in
respective runs at temperature of 550.degree. C. (bottom curve),
600.degree. C. (second curve from bottom at 600.degree. C.),
650.degree. C. (third curve from bottom at 600.degree. C.), and
700.degree. C. (top curve at 600.degree. C.). The chemical vapor
deposition of molybdenum by MoOCl.sub.4/H.sub.2 process, without a
nucleation layer, showed temperature cut off at 550.degree. C.
Deposition rates are similar from 600.degree. C. to 700.degree. C.
(stage temperatures).
Example 4--Temperature and Resistivity Study
[0075] FIG. 8 is a graph of film resistivity, in .mu..OMEGA.cm, as
a function of molybdenum thickness, in .ANG.ngstroms, for
molybdenum deposition conducted by MoOCl.sub.4/H.sub.2 process at
conditions of 70.degree. C. ampoule temperature, 60 torr pressure,
50 sccm argon carrier gas flow rate, and 2000 sccm hydrogen gas
flow rate, in which the process was conducted in separate runs at
temperature of 600.degree. C. (top curve), 650.degree. C. (middle
curve) and 700.degree. C. (bottom curve). The data show that the
processes conducted at 600.degree. C. and 650.degree. C. showed
slightly higher resistivity compared to the 700.degree. C. process.
At 700.degree. C. stage temperature, the film resistivity drops to
approximately 11 .mu..OMEGA.cm for a molybdenum film thickness in
the order of 500 .ANG..
Example 5--Comparison with MoCl.sub.5--Long-Term Deposition
Study
[0076] FIG. 9 is a graph of deposition rate, in
.ANG.ngstroms/minute, as a function of run number, for molybdenum
deposition using molybdenum oxytetrachloride (MoOCl.sub.4) as the
molybdenum precursor (.smallcircle.), and for molybdenum deposition
using sublimed molybdenum pentachloride (MoCl5) as the molybdenum
precursor (.DELTA.). The process conditions in both cases were as
follows: ampoule temperature=70.degree. C.; pressure=60 torr; argon
carrier gas flow rate=50 sccm; hydrogen gas flow rate=2000
sccm.
[0077] The results in FIG. 9 show that the molybdenum deposition
using molybdenum oxytetrachloride (MoOCl.sub.4) as the molybdenum
precursor exhibited stable and high deposition rates, whereas
sublimed molybdenum pentachloride (MoCl5) showed stable and low
deposition rates.
[0078] Secondary ion mass spectrometry (SIMS) analysis of
molybdenum films formed from MoOCl.sub.4 verified that oxygen
concentration in the bulk molybdenum is well below 1%, using a
number density of approximately 6.4.times.10.sup.22 cm.sup.-3 for
bulk molybdenum.
Example 6--Comparison with MoCl.sub.5--Resistivity Study
[0079] FIG. 10 is a graph of film resistivity of deposited
molybdenum films, in .mu..OMEGA.cm, as a function of molybdenum
film thickness, in .ANG.ngstroms, for a CVD deposition process
conducted at 700.degree. C., for molybdenum film deposited using
unpurified MoCl.sub.5 precursor (.DELTA.), molybdenum film
deposited using sublimed MoCl.sub.5 precursor (.quadrature.), and
molybdenum film deposited using molybdenum oxytetrachloride
(MoOCl.sub.4) precursor (.diamond.). The process conditions were as
follows: ampoule temperature=70.degree. C.; pressure=60 torr; argon
carrier gas flow rate=50 sccm; hydrogen gas flow rate=2000 sccm.
The results show that MoOCl.sub.4 precursor produced molybdenum
films with higher resistivity values compared to films formed using
unpurified MoCl.sub.5 precursor and sublimed MoCl.sub.5
precursor.
Example 7--Diborane Soak Study
[0080] The effect of pre-soaking the substrate with diborane was
investigated. FIG. 11 is a graph of molybdenum film thickness, in
.ANG.ngstroms, as a function of diborane soak time, in seconds, for
diborane exposure at 400.degree. C., and 500.degree. C. bulk
molybdenum deposition using molybdenum oxytetrachloride
(MoOCl.sub.4) precursor (.smallcircle.), and for diborane exposure
at 300.degree. C., and 500.degree. C. bulk molybdenum deposition
using molybdenum oxytetrachloride (MoOCl.sub.4) precursor
(.DELTA.).
[0081] The results in FIG. 11 showed that the diborane exposure
condition of 300.degree. C. for 30 seconds and molybdenum
oxytetrachloride (MoOCl.sub.4) precursor exposure at 500.degree. C.
did not result in molybdenum deposition, and it was necessary to
increase either the diborane exposure temperature or diborane soak
time in order to obtain substantial molybdenum growth.
Example 8--SEM Study--with Diborane Nucleation
[0082] FIGS. 12 and 13 are SEM micrographs of film depositions
formed using 500.degree. C. diborane nucleation, and 500.degree. C.
bulk molybdenum deposition using molybdenum oxytetrachloride
(MoOCl.sub.4) precursor in the presence of hydrogen. The process
conditions for the diborane soak were as follows: substrate=50
.ANG. TiN; ampoule temperature=70.degree. C.; pressure=40 torr;
diborane flow rate=35 sccm; argon carrier gas flow rate=500 sccm;
hydrogen flow rate=0 sccm, duration=30 seconds. The process
conditions for the MoOCl.sub.4/H.sub.2 bulk molybdenum deposition
were as follows: stage temperature=500.degree. C.; pressure=60
torr; argon carrier gas flow rate=50 sccm; hydrogen flow rate=2000
sccm; duration=300 seconds. The results showed that 500.degree. C.
diborane nucleation resulted in molybdenum deposition, but an
excessive boron layer was formed under the molybdenum.
Example 9--Step Coverage--3 Cycle Diborane Nucleation Process
[0083] FIGS. 14 and 15 are SEM images of deposited films in vias,
showing step coverage for a 3 cycle nucleation and molybdenum bulk
deposition with MoOCl.sub.4/H.sub.2. The process conditions in the
diborane soak were as follows: substrate=via TEG; ampoule
temperature=70.degree. C.; stage temperature=300.degree. C.;
pressure=40 torr; diborane flow rate=35 sccm; argon carrier gas
flow rate=250 sccm; hydrogen flow rate=0 sccm, duration=60 seconds.
The process conditions for the MoOCl.sub.4/H.sub.2 molybdenum
deposition were as follows: stage temperature=550.degree. C.;
pressure=60 torr; argon carrier gas flow rate=50 sccm; hydrogen
flow rate=2000 sccm; duration=60 seconds. The SEM images show that
the MoOCl.sub.4/B2H.sub.6 nucleation process (3 cycles) exhibited
good step coverage on the via structure.
[0084] The associated process chemistry includes the following
reactions: MoOCl.sub.4+3 H.sub.2.fwdarw.Mo+4 HCl+H.sub.2O; and 2
MoOCl.sub.4+B.sub.2H.sub.6.fwdarw.2 Mo+2 BCl.sub.3+2
HCl+2H.sub.2O.
[0085] X-ray diffraction measurements were made on a representative
molybdenum film deposited from MoOCl.sub.4 in accordance with the
present disclosure, and the XRT measurement showed only Mo metal
peaks, with no MoO.sub.2 or MoO.sub.3 peaks present.
[0086] X-ray reflectivity (XRR) measurements on a representative
molybdenum film formed in accordance with the present disclosure
showed .about.13.4 nm molybdenum with a density of approximately
8.33 g/cm.sup.3 on a 147 .ANG. x-ray fluorescence (XRF)
spectrometry-measured film.
Example 10--Diborane Soak Time--Impact on Thickness and
Resistivity
[0087] FIG. 16 is a graph of molybdenum thickness (.DELTA.), in
.ANG.ngstroms, and resistivity (bar graph column markers), in
.mu..OMEGA.cm, as a function of diborane soak time, in seconds, for
a deposition process including nucleation at process conditions of:
stage temperature=300.degree. C.; pressure=44; diborane flow
rate=35 sccm; argon carrier gas flow rate=250 sccm, and bulk
molybdenum deposition for 600 seconds, at process conditions of:
stage temperature=550.degree. C., ampoule temperature=70.degree.
C.; pressure=60 torr; argon carrier gas flow rate=50 sccm; hydrogen
gas flow rate 2000 sccm, showing the diborane soak time effect. The
data show that with 60 seconds or longer diborane pre-soak,
molybdenum deposition is enabled at 550.degree. C. stage
temperature. As shown, film resistivity increases at longer
diborane soak time periods.
Example 11--Thickness and Resistivity Study--with Diborane
Nucleation
[0088] FIG. 17 is a graph of molybdenum thickness (.DELTA.), in
.ANG.ngstroms, as a function of MoOCl4/H.sub.2 exposure time, in
seconds, and resistivity (.smallcircle.), in .mu..OMEGA.cm, as a
function of the MoOCl.sub.4/H.sub.2 exposure time, for a deposition
process including nucleation at process conditions: stage
temperature=300.degree. C.; pressure=40 torr; diborane flow rate=35
sccm; argon carrier gas flow rate=250 sccm; duration=60 seconds,
and bulk molybdenum deposition at conditions: stage
temperature=550.degree. C., ampoule temperature=70.degree. C.;
pressure=60 torr; argon carrier gas flow rate=50 sccm; and hydrogen
gas flow rate=2000 sccm. As shown, with a 60 second diborane
pre-soak, molybdenum deposition thickness grows with
MoOCl.sub.4/H.sub.2 exposure time at 550.degree. C. Film
resistivity drops below 20 .mu..OMEGA.cm for thickness greater than
400 .ANG..
Example 12--SEM Study--with Diborane Nucleation
[0089] FIG. 18 is an SEM image of a molybdenum film deposited at
550.degree. C., and FIG. 19 is an SEM cross-section image of such
film, as deposited at the following diborane soak process
conditions: substrate=50 .ANG. TiN; ampoule temperature=70.degree.
C.; stage temperature=300.degree. C.; pressure=40 torr; diborane
flow rate=35 sccm; argon carrier gas flow rate=250 sccm; hydrogen
gas flow rate=0 sccm; and duration=90 seconds, followed by bulk
molybdenum deposition by MoOCl.sub.4/H.sub.2 process at the
following process conditions: stage temperature=550.degree. C.;
pressure=60 torr; argon carrier gas flow rate=50 sccm; hydrogen gas
flow rate=2000 sccm; and duration=600 seconds (one cycle). The X RF
thickness of the film was 1693.6 .ANG., and the resistivity was
determined as 21.6 .mu..OMEGA.cm. The SEM images showed
approximately 40-70 nm grain size for molybdenum deposited at
550.degree. C. with 90 seconds diborane pre-soak. The cross-section
SEM image shows approximately 7.7 nm boron layer underneath the
deposited molybdenum.
Example 13--Stage Temperature Study--with an without Diborane
Nucleation
[0090] FIG. 20 is a graph of molybdenum thickness (.DELTA.), in
.ANG.ngstroms, as a function of stage temperature, in degrees
Centigrade, and resistivity, (.smallcircle.), in .mu..OMEGA.cm, as
a function of the stage temperature, showing a reaction rate
limited regime for the MoOCl.sub.4/H.sub.2 process with diborane
nucleation, as conducted at diborane nucleation conditions of:
stage temperature=300.degree. C.; pressure=40 torr; diborane flow
rate=35 sccm; argon carrier gas flow rate=250 sccm; duration=60
seconds, and at bulk molybdenum deposition process conditions of:
ampoule temperature=70.degree. C., pressure=60 torr; argon carrier
gas flow rate=50 sccm; hydrogen gas flow rate=2000 sccm; duration=5
minutes. The data show that with diborane nucleation, molybdenum
deposition cutoff temperature is reduced to 500.degree. C. with
rapid deposition rate drop off between 500.degree. C. and
540.degree. C.
[0091] FIG. 21 is a graph of molybdenum thickness (.DELTA.), in
.ANG.ngstroms, as a function of stage temperature, in degrees
Centigrade, and resistivity, (.smallcircle.), in .mu..OMEGA.cm, as
a function of the stage temperature, showing a reaction rate
limited regime for the MoOCl.sub.4/H.sub.2 process without diborane
nucleation, as conducted at process conditions of: ampoule
temperature=70.degree. C., pressure=60 torr; argon carrier gas flow
rate=50 sccm; hydrogen gas flow rate=2000 sccm; duration=5 minutes.
The data show that deposition rates for the CVD process without
diborane nucleation drop-off rapidly below 600.degree. C. with
cutoff temperature at approximately 560.degree. C.
Example 14--Arrhenius Plot--with and without Diborane
Nucleation
[0092] FIG. 22 is an Arrhenius plot (K=A.sup.e-Ea/RT) of activation
energy for the MoOCl.sub.4/H.sub.2 reaction, as conducted without
nucleation (.DELTA.), and as conducted with nucleation
(.smallcircle.). The data show that the extracted activation energy
for the MoOCl.sub.4/H.sub.2 reaction is approximately 233 kJ/mole
for the bulk molybdenum process deposition without nucleation, and
approximately 251 kJ/mole for the bulk molybdenum deposition
process with diborane nucleation.
Example 15--Step Coverage
[0093] FIGS. 23 and 24 show step coverage on a via structure by a
nucleation and CVD bulk molybdenum deposition MoOCl.sub.4/H.sub.2
process, as conducted at the following process conditions:
substrate=via TEG; ampoule temperature=70.degree. C., with the
diborane nucleation (soak) process conducted at the process
conditions of: stage temperature=300.degree. C.; pressure=40 torr;
diborane flow rate=35 sccm; argon carrier gas flow rate=250 sccm;
hydrogen gas flow rate=0 sccm; duration=60 seconds, and with the
bulk molybdenum deposition CVD process carried out at conditions
of: stage temperature=520.degree. C.; pressure=60 torr; argon
carrier gas flow rate=50 sccm; hydrogen gas flow rate=2000 sccm;
and duration=600 seconds. The images show that the 520.degree. C.
MoOCl.sub.4/H.sub.2 process with one cycle of diborane nucleation
showed approximately 50% step coverage (bottom/top) on the via
structure.
Example 16--Step Coverage--Impact of Deposition Time
[0094] FIGS. 25, 26, and 27 show respective via structures
deposited with molybdenum by diborane nucleation (soak) and
520.degree. C. CVD bulk molybdenum deposition MoOCl.sub.4/H.sub.2
process, at bulk deposition process times of 300 seconds, 450
seconds, and 600 seconds, respectively. The process conditions were
as follows: substrate=via TEG; ampoule temperature=70.degree. C.,
with the diborane nucleation (soak) process conducted at the
process conditions of: stage temperature=300.degree. C.;
pressure=40 torr; diborane flow rate=35 sccm; argon carrier gas
flow rate=250 sccm; hydrogen gas flow rate=0 sccm; duration=60
seconds, and with the bulk molybdenum deposition CVD process
carried out at conditions of: stage temperature=520.degree. C.;
pressure=60 torr; argon carrier gas flow rate=50 sccm; hydrogen gas
flow rate=2000 sccm; and duration=300 seconds (FIG. 25), 450
seconds (FIG. 26) and 600 seconds (FIG. 27). The images show that
the 520.degree. C. MoOCl.sub.4/H.sub.2 process with one cycle of
diborane nucleation exhibited gradually reduced step coverage on
the via structure with increased deposition, due to constraints at
the "neck" of the structure.
Example 17--Step Coverage--Impact of Temperature
[0095] FIGS. 28, 29, and 30 show respective via structures
deposited with molybdenum by diborane nucleation (soak) and CVD
bulk molybdenum deposition MoOCl.sub.4/H.sub.2 process, at bulk
deposition temperature of 510.degree. C., 520.degree. C., and
530.degree. C., respectively. The process conditions were as
follows: substrate=via TEG; ampoule temperature=70.degree. C., with
the diborane nucleation (soak) process conducted at the process
conditions of: stage temperature=300.degree. C.; pressure=40 torr;
diborane flow rate=35 sccm; argon carrier gas flow rate=250 sccm;
hydrogen gas flow rate=0 sccm; duration=60 seconds, and with the
bulk molybdenum deposition CVD process carried out at conditions
of: stage temperature=510.degree. C. (FIG. 28), 520.degree. C.
(FIG. 29), and 530.degree. C. (FIG. 30); pressure=60 torr; argon
carrier gas flow rate=50 sccm; hydrogen gas flow rate=2000 sccm;
and duration=600 seconds. The images show that the 510.degree. C.
MoOCl.sub.4/H.sub.2 process exhibited poor step coverage due to
rough film morphology, the 520.degree. C. process showed
approximately 50% step coverage on the via structure, and the step
coverage degraded to about 30% for the 530.degree. C. process.
Example 18--Step Coverage--Impact of Diborane Soak Time
[0096] FIGS. 31, 32, and 33 show respective via structures
deposited with molybdenum by diborane nucleation (soak) and CVD
bulk molybdenum deposition MoOCl.sub.4/H.sub.2 process, at diborane
dose (soak) times of 45 seconds (FIG. 31), 60 seconds (FIG. 32),
and 75 seconds (FIG. 33), respectively. The process conditions were
as follows: substrate=via TEG; ampoule temperature=70.degree. C.,
with the diborane nucleation (soak) process conducted at the
process conditions of: stage temperature=300.degree. C.;
pressure=40 torr; diborane flow rate=35 sccm; argon carrier gas
flow rate=250 sccm; hydrogen gas flow rate=0 sccm, and with the
bulk molybdenum deposition CVD process carried out at conditions
of: stage temperature=520.degree. C.; pressure=60 torr; argon
carrier gas flow rate=50 sccm; hydrogen gas flow rate=2000 sccm;
and duration=450 seconds. The images show a boron layer clearly
visible underneath the deposited molybdenum for the 60 second and
75 seconds diborane soak conditions.
Example 19--Step Coverage--Pulsing at 60 Torr
[0097] FIGS. 34, 35, and 36 are SEM images of a via structure
deposited with molybdenum by diborane nucleation (soak) and CVD
bulk molybdenum deposition MoOCl.sub.4/H.sub.2 process, involving a
pulsed CVD process conducted at 60 torr for 120 cycles, wherein
FIG. 34 shows the via having an upper portion with a molybdenum
film thickness of 510 .ANG. and a lower portion with a molybdenum
film thickness of 375 .ANG., FIG. 35 shows the via at an
intermediate portion thereof with a molybdenum film thickness of
480 .ANG., and FIG. 36 shows the lower portion of the via having a
molybdenum film thickness of 375 .ANG., at the following process
conditions: substrate=via TEG; ampoule temperature=70.degree. C.,
with the diborane nucleation (soak) process conducted at the
process conditions of: stage temperature=300.degree. C.;
pressure=40 torr; diborane flow rate=35 sccm; argon carrier gas
flow rate=250 sccm; hydrogen gas flow rate=0 sccm; and duration=45
seconds, and with the pulsed molybdenum deposition CVD process
carried out at conditions of: stage temperature=520.degree. C.;
pressure=60 torr; argon carrier gas flow rate=50 sccm; hydrogen gas
flow rate=2000 sccm; pulse duration=5 seconds; purge duration=10
seconds; and number of cycles=120. The pulsed CVD process with 10
second purge between each pulse exhibited a reduced build up near
the neck of the structure. Step coverage was on the order of 75%
for a bulk molybdenum deposition of approximately 500 .ANG.
thickness.
Example 20--Step Coverage--Pulsing at 40 Torr
[0098] FIGS. 37 and 38 are SEM images of a via structure deposited
with molybdenum by diborane nucleation (soak) and CVD bulk
molybdenum deposition MoOCl.sub.4/H.sub.2 process, involving a
pulsed CVD process conducted at 40 torr for 120 cycles, wherein
FIG. 37 shows the via having an upper portion having a molybdenum
film thickness of 320 .ANG., and intermediate portion with a
molybdenum film thickness of 520 .ANG., and a lower portion with a
molybdenum film thickness of 460 .ANG., and FIG. 38 shows the via
at the lower portion thereof, wherein the process was conducted at
the following process conditions: substrate=via TEG; ampoule
temperature=70.degree. C., with the diborane nucleation (soak)
process conducted at the process conditions of: stage
temperature=300.degree. C.; pressure=40 torr; diborane flow rate=35
sccm; argon carrier gas flow rate=250 sccm; hydrogen gas flow
rate=0 sccm; and duration=45 seconds, and with the pulsed
molybdenum deposition CVD process carried out at conditions of:
stage temperature=520.degree. C.; pressure=40 torr; argon carrier
gas flow rate=50 sccm; hydrogen gas flow rate=2000 sccm; pulse
duration=5 seconds; purge duration=10 seconds; and number of
cycles=120. The pulsed CVD process at 40 torr showed excellent step
coverage, with thinner deposition on top and thicker deposition
inside the via. Nominal step coverage on this via structure
exceeded 100%.
Example 21--Step Coverage--Pulsing at 40 Torr--Increased Number of
Cycles
[0099] FIGS. 39 and 40 are SEM images of a via structure deposited
with molybdenum by diborane nucleation (soak) and CVD bulk
molybdenum deposition MoOCl.sub.4/H.sub.2 process, involving a
pulsed CVD process conducted at 40 torr for 240 cycles, wherein
FIG. 39 shows the via having an intermediate portion with a
molybdenum film thickness of 720 .ANG., and a lower portion with a
molybdenum film thickness of 460 .ANG., and FIG. 40 shows the via
at the lower portion thereof, wherein the process was conducted at
the following process conditions: substrate=via TEG; ampoule
temperature=70.degree. C., with the diborane nucleation (soak)
process conducted at the process conditions of: stage
temperature=300.degree. C.; pressure=40 torr; diborane flow rate=35
sccm; argon carrier gas flow rate=250 sccm; hydrogen gas flow
rate=0 sccm; and duration=45 seconds, and with the pulsed
molybdenum deposition CVD process carried out at conditions of:
stage temperature=520.degree. C.; pressure=40 torr; argon carrier
gas flow rate=50 sccm; hydrogen gas flow rate=2000 sccm; pulse
duration=5 seconds; purge duration=10 seconds; and number of
cycles=240. Increasing the number of cycles that 40 torr pressure,
from 120 to 240 did not result in a void-free fill due to pinch-off
at the via neck.
Example 22--Etch Rates
[0100] The etch rate of a MoOCl.sub.4/H.sub.2 process on boron
nucleation surfaces (CVD B) was explored. The process was carried
out at conditions of: stage temperature=500.degree. C.; pressure=20
torr; argon carrier gas flow rate=50 sccm; hydrogen gas flow
rate=2000 sccm. Further conditions and the resulting etch rate are
shown in Table 1:
TABLE-US-00001 TABLE 1 Ex- Air Etch Start End Etch am- Sub- Under
expo- time thickness thickness rate ple strate layer sure (s)
(.ANG.) (.ANG.) (.ANG./min) 22C CVD B 1k.ANG. Mo >50 hr 600 2835
2630 20 22H CVD B 1k.ANG. Mo >50 hr 1200 2715 2525 10 22M CVD B
30.ANG. TiN 0 300 280 (avg) 274 1 22N CVD B 30.ANG. TiN 2 hr 300
278 272 1 22O CVD B 30.ANG. TiN 50 hr 300 287 283 1
[0101] The etch rate was not impacted by exposure to air. The etch
rate of thick boron film on a Mo substrate was much higher than on
boron film on TiN substrate. This may be due to surface roughness
of the thick boron films.
Example 23--Other Substrates
[0102] The MoOCl.sub.4/H.sub.2 process was carried out on a range
of substrates. The process was carried out at conditions of: stage
temperature=500.degree. C.; pressure=60 torr; argon carrier gas
flow rate=50 sccm; hydrogen gas flow rate=2000 sccm. Further
conditions and the substrates are shown in Table 2:
TABLE-US-00002 TABLE 2 Stage Mo Mo temperature thickness
resistivity Example Substrate (.degree. C.) (.ANG.) (.mu..OMEGA.
cm) 23A 1000 .ANG. PVD Mo 500 148 6.5 23B 1000 .ANG. PVD Mo 560 902
6.3 23C ~50 .ANG. CVD B 510 470 8.9 23D ~50 .ANG. CVD B 550 656 7
23E 150 .ANG. MoC 500 940 25.3 23F 136 .ANG. MoC 550 953 17.1 23G
178 .ANG. TiN 560 165 256.3 23H 175 .ANG. TiN 600 877 30 23I 177
.ANG. TiN 650 1750 9.3 23J 1000 .ANG. SiO.sub.2 540 300 30.5 23K
1000 .ANG. CVD W 500 126 5.2 23L 1000 .ANG. CVD W 650 1989 7.5 23M
25 .ANG. WCN 500 273 46 23N 25 .ANG. WCN 600 1801 16
[0103] The deposited molybdenum exhibited a wide range of
resistivity. Resistivity did not vary with thickness where the
substrate was PVD Mo. As noted from previous results, resistivity
was very dependent on stage temperature of TiN substrates without a
boron nucleation layer.
Discussion
[0104] The foregoing shows that CVD molybdenum films deposited
using MoOCl.sub.4 precursor showed good film resistivity of less
than 15 .mu..OMEGA.cm at thickness of 400 .ANG., and SIMS analyses
showed oxygen concentration in the bulk molybdenum film to be well
below 1 atomic percent for films deposited using MoOCl.sub.4
precursor. On a TiN substrate the CVD MoOCl.sub.4/H.sub.2 process
exhibited deposition temperature cut off at approximate 560.degree.
C. without diborane nucleation, and cut off at approximately
500.degree. C. with diborane nucleation. Activation energy
extracted from Arrhenius plot is approximately 223 kJ/mole for the
process without nucleation, and approximately 251 kJ/mole for the
process with diborane nucleation. The CVD MoOCl.sub.4/H.sub.2
process with diborane nucleation exhibited excellent step coverage
on via structures, and the pulsed CVD process was demonstrated to
achieve and even exceed 100% step coverage at film thickness of 500
.ANG..
[0105] While the disclosure has been set forth herein in reference
to specific aspects, features and illustrative embodiments, it will
be appreciated that the utility of the disclosure is not thus
limited, but rather extends to and encompasses numerous other
variations, modifications and alternative embodiments, as will
suggest themselves to those of ordinary skill in the field of the
present disclosure, based on the description herein.
Correspondingly, the disclosure as hereinafter claimed is intended
to be broadly construed and interpreted, as including all such
variations, modifications and alternative embodiments, within its
spirit and scope.
[0106] Throughout the description and claims of this specification,
the words "comprise" and "contain" and variations of the words, for
example "comprising" and "comprises", mean "including but not
limited to", and do not exclude other components, integers or
steps. Moreover the singular encompasses the plural unless the
context otherwise requires: in particular, where the indefinite
article is used, the specification is to be understood as
contemplating plurality as well as singularity, unless the context
requires otherwise.
[0107] Optional features of each aspect of the invention may be as
described in connection with any of the other aspects. Within the
scope of this application it is expressly intended that the various
aspects, embodiments, examples and alternatives set out in the
preceding paragraphs and in the claims and drawings, and in
particular the individual features thereof, may be taken
independently or in any combination. That is, all embodiments
and/or features of any embodiment can be combined in any way and/or
combination, unless such features are incompatible.
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