U.S. patent application number 12/030186 was filed with the patent office on 2008-08-28 for plasma enhanced cyclic chemical vapor deposition of silicon-containing films.
This patent application is currently assigned to AIR PRODUCTS AND CHEMICALS, INC.. Invention is credited to Thomas Richard Gaffney, Eugene Joseph Karwacki, Xinjian Lei, Hareesh Thridandam, Manchao Xiao.
Application Number | 20080207007 12/030186 |
Document ID | / |
Family ID | 39716395 |
Filed Date | 2008-08-28 |
United States Patent
Application |
20080207007 |
Kind Code |
A1 |
Thridandam; Hareesh ; et
al. |
August 28, 2008 |
Plasma Enhanced Cyclic Chemical Vapor Deposition of
Silicon-Containing Films
Abstract
The present invention is a process of plasma enhanced cyclic
chemical vapor deposition of silicon nitride, silicon carbonitride,
silicon oxynitride, silicon carboxynitride, and carbon doped
silicon oxide from alkylaminosilanes having Si--H.sub.3, preferably
of the formula (R.sup.1R.sup.2N)SiH.sub.3 wherein R.sup.1 and
R.sup.2 are selected independently from C.sub.2 to C.sub.10 and a
nitrogen or oxygen source, preferably ammonia or oxygen has been
developed to provide films with improved properties such as etching
rate, hydrogen concentrations, and stess as compared to films from
thermal chemical vapor deposition.
Inventors: |
Thridandam; Hareesh; (Vista,
CA) ; Xiao; Manchao; (San Diego, CA) ; Lei;
Xinjian; (Vista, CA) ; Gaffney; Thomas Richard;
(Carlsbad, CA) ; Karwacki; Eugene Joseph;
(Orefield, PA) |
Correspondence
Address: |
AIR PRODUCTS AND CHEMICALS, INC.;PATENT DEPARTMENT
7201 HAMILTON BOULEVARD
ALLENTOWN
PA
181951501
US
|
Assignee: |
AIR PRODUCTS AND CHEMICALS,
INC.
Allentown
PA
|
Family ID: |
39716395 |
Appl. No.: |
12/030186 |
Filed: |
February 12, 2008 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
60903734 |
Feb 27, 2007 |
|
|
|
Current U.S.
Class: |
438/778 ;
257/E21.24 |
Current CPC
Class: |
H01L 21/3141 20130101;
C23C 16/30 20130101; C23C 16/345 20130101; H01L 21/3144 20130101;
C23C 16/45553 20130101; H01L 21/0214 20130101; C23C 16/401
20130101; H01L 21/3145 20130101; H01L 21/02274 20130101; C23C
16/45542 20130101; H01L 21/0228 20130101; C23C 16/452 20130101;
H01L 21/02167 20130101; H01L 21/0217 20130101; H01L 21/3185
20130101; C23C 16/308 20130101 |
Class at
Publication: |
438/778 ;
257/E21.24 |
International
Class: |
H01L 21/31 20060101
H01L021/31 |
Claims
1. A process to deposit silicon nitride, silicon carbonitride,
silicon oxynitride, and silicon carboxynitride on a semi-conductor
substrate comprising: a. contacting a nitrogen-containing source
with a heated substrate under remote plasma conditions to absorb at
least a portion of the nitrogen-containing source on the heated
substrate, b. purging away any unabsorbed nitrogen-containing
source, c. contacting the heated substrate with a
silicon-containing source having one or more Si--H.sub.3 fragments
to react with the absorbed nitrogen-containing source, wherein the
silicon-containing source has one or more H.sub.3Si--NR.sup.0.sub.2
(R.sup.0.dbd.SiH.sub.3, R, R.sup.1 or R.sup.2, defined below)
groups selected from the group consisting of one or more of:
##STR00003## wherein R and R.sup.1 in the formulas represent
aliphatic groups having from 2 to 10 carbon atoms, wherein R and
R.sup.1 in formula A may also be a cyclic group, and R.sup.2
selected from the group consisting of a single bond,
(CH.sub.2).sub.n, a ring, or SiH.sub.2, and d. purging away the
unreacted silicon-containing source.
2. The process of claim 1 wherein the process is repeated until a
desired thickness of film is established.
3. The process of claim 1 is an atomic layer deposition.
4. The process of claim 1 is a plasma enhanced cyclic chemical
vapor deposition.
5. The process of claim 1 wherein the substrate temperature is in
the range of 200 to 600.degree. C.
6. The process of claim 1 wherein the silicon-containing source
having one or more Si--H.sub.3 fragments is selected from the group
consisting of diethylaminosilane (DEAS),
di-iso-propylaminosilane(DIPAS), di-tert-butylaminosilane (DTBAS),
di-sec-butylaminosilane, di-tert-pentylamino silane and mixtures
thereof.
7. The process of claim 1 wherein the nitrogen-containing source is
selected from the group consisting of nitrogen, ammonia, hydrazine,
monoalkylhydrozine, dialkylhydrozine, and mixture thereof.
8. A process to deposit silicon oxynitride, silicon carboxynitride,
and carbon doped silicon oxide on a semi-conductor substrate
comprising: a. contacting a oxygen-containing source with a heated
substrate under remote plasma conditions to absorb at least a
portion of the oxygen-containing source on the heated substrate, b.
purging away any unabsorbed oxygen-containing source, c. contacting
the heated substrate with a silicon-containing source having one or
more Si--H.sub.3 fragments to react with the absorbed
oxygen-containing source, wherein the silicon-containing source has
one or more H.sub.3Si--NR.sup.0.sub.2 (R.sup.0.dbd.SiH.sub.3, R,
R.sup.1 or R.sup.2, defined below) groups selected from the group
consisting of one or more of: ##STR00004## wherein R and R.sup.1 in
the formulas represent aliphatic groups having from 2 to 10 carbon
atoms, wherein R and R.sup.1 in formula A may also be a cyclic
group, and R.sup.2 selected from the group consisting of a single
bond, (CH.sub.2).sub.n, a ring, or SiH.sub.2, and d. purging away
the unreacted silicon-containing source.
9. The process of claim 8 wherein the process is repeated until a
desired thickness of film is established.
10. The process of claim 8 is an atomic layer deposition.
11. The process of claim 8 is a plasma enhanced cyclic chemical
vapor deposition.
12. The process of claim 8 wherein the substrate temperature is in
the range of 200 to 600.degree. C.
13. The process of claim 8 wherein the silicon-containing source
having one or more Si--H.sub.3 fragments is selected from the group
consisting of diethylaminosilane (DEAS),
di-iso-propylaminosilane(DIPAS), di-tert-butylaminosilane (DTBAS),
di-sec-butylaminosilane, di-tert-pentylamino silane and mixtures
thereof.
14. The process of claim 8 wherein the oxygen-containing source is
selected from the group consisting of oxygen, nitrous oxide, ozone,
and mixture thereof.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] The present patent application claims the benefits of U.S.
Provisional Patent Application No. 60/903,734 filed 27 Feb.
2007.
BACKGROUND OF THE INVENTION
[0002] The electronic device manufacturing industry has used
chemical vapor deposition (CVD), cyclic chemical vapor deposition
(CCVD), or atomic layer deposition (ALD) of silicon nitride,
silicon carbonitride, and silicon oxynitride in making integrated
circuits. Examples of this industry use include: US 2003/0020111;
US 2005/0048204 A1; U.S. Pat. No. 4,720,395; U.S. Pat. No.
7,166,516; Gumpher, J., W. Bather, N. Mehta and D. Wedel.
"Characterization of Low-Temperature Silicon Nitride LPCVD from
Bis(tertiary-butylamino)silane and Ammonia." Journal of The
Electrochemical Society 151(5): (2004) G353-G359; US 2006/045986;
US 2005/152501; US 2005/255714; U.S. Pat. No. 7,129,187; U.S.
2005/159017; U.S. Pat. No. 6,391,803; U.S. Pat. No. 5,976,991; US
2003/0059535; U.S. Pat. No. 5,234,869; JP2006-301338; US
2006/087893; US 2003/26083; US 2004/017383; U.S. 2006/0019032; US
2003/36097; US 2004/044958; U.S. Pat. No. 6,881,636; U.S. Pat. No.
6,963,101; US 2001/0000476; and US2005/129862. The present
invention offers an improvement over this prior industry practice
for CVD or ALD of silicon-containing films such as silicon nitride,
silicon carbonitride, silicon oxynitride, and carbon doped silicon
oxide on a substrate, as set forth below.
BRIEF SUMMARY OF THE INVENTION
[0003] The present invention is a process to deposit
silicon-containing films such as silicon nitride, silicon
carbonitride, silicon oxynitride, and carbon doped silicon oxide on
a substrate.
[0004] One embodiment of the present invention is a process to
deposit silicon nitride, silicon carbonitride, silicon oxynitride,
and silicon carboxynitride on a semi-conductor substrate
comprising: [0005] a. contacting a nitrogen-containing source with
a heated substrate under remote plasma conditions to absorb at
least a portion of the nitrogen-containing source on the heated
substrate, [0006] b. purging away any unabsorbed
nitrogen-containing source, [0007] c. contacting the heated
substrate with a silicon-containing source having one or more
Si--H.sub.3 fragments to react with the absorbed oxygen-containing
source, wherein the silicon-containing source has one or more
H.sub.3Si--NR.sup.0.sub.2 (R.sup.0.dbd.SiH.sub.3, R, R.sup.1 or
R.sup.2, defined below) groups selected from the group consisting
of one or more of:
[0007] ##STR00001## [0008] wherein R and R.sup.1 in the formulas
represent aliphatic groups having from 2 to 10 carbon atoms,
wherein R and R.sup.1 in formula A may also be a cyclic group, and
R.sup.2 selected from the group consisting of a single bond,
(CH.sub.2).sub.n, a ring, or SiH.sub.2, and [0009] d. purging away
the unreacted silicon-containing source.
[0010] Another embodiment of the present invention is a process to
deposit silicon oxynitride, silicon carboxynitride, and carbon
doped silicon oxide on a substrate comprising: [0011] a. contacting
an oxygen-containing source with a heated substrate under remote
plasma conditions to absorb at least a portion of the
oxygen-containing source on the heated substrate, [0012] b. purging
away any unabsorbed oxygen-containing source, [0013] c. contacting
the heated substrate with a silicon-containing source having one or
more Si--H.sub.3 fragments to react with the absorbed
oxygen-containing source, wherein the silicon-containing source has
one or more H.sub.3Si--NR.sup.0.sub.2 (R.sup.0.dbd.SiH.sub.3, R,
R.sup.1 or R.sup.2, defined below) groups selected from the group
consisting of one or more of:
[0013] ##STR00002## [0014] wherein R and R.sup.1 in the formulas
represent aliphatic groups having from 2 to 10 carbon atoms,
wherein R and R.sup.1 in formula A may also be a cyclic group, and
R.sup.2 selected from the group consisting of a single bond,
(CH.sub.2).sub.n, a ring, or SiH.sub.2, and [0015] d. purging away
the unreacted silicon-containing source.
BRIEF DESCRIPTION OF THE DRAWINGS
[0016] FIG. 1 is a scheme of typical plasma enhanced cyclic
chemical vapor deposition for silicon nitride, silicon
carbonitride, silicon oxynitride, and silicon carboxynitride.
[0017] FIG. 2 is a Deposition Rate vs Pulse Time graph for DIPAS
with the following PEALD experimental conditions: 5 sccm NH.sub.3
with plasma power of 1.39 kW, 10 sccm N.sub.2 as sweeping gas,
substrate temperature of 400.degree. C., DIPAS at 40.degree. C. in
a stainless steel container.
[0018] FIG. 3 is a scheme of typical plasma enhanced cyclic
chemical vapor deposition for silicon oxynitride and carbon doped
silicon oxide.
[0019] FIG. 4 is the FTIR spectrum for the films of Example 1 and
discussed in Example 2.
DETAILED DESCRIPTION OF THE INVENTION
[0020] The present invention is a process of plasma enhanced cyclic
chemical vapor deposition of silicon nitride, silicon carbonitride,
silicon oxynitride, silicon carboxynitride, and carbon doped
silicon oxide from alkylaminosilanes having Si--H.sub.3, preferably
of the formula (R.sup.1R.sup.2N)SiH.sub.3 wherein R.sup.1 and
R.sup.2 are selected independently from C.sub.2 to C.sub.10 and a
nitrogen source, preferably ammonia has been developed to provide
films with improved properties such as etching rate, hydrogen
concentrations, and stress as compared to films from thermal
chemical vapor deposition. Alternately, the process can be
performed as atomic layer deposition (ALD), plasma assisted atomic
layer deposition (PAALD), chemical vapor deposition (CVD), low
pressure chemical vapor deposition (LPCVD), plasma enhanced
chemical vapor deposition (PECVD) or spin on deposition (SOD).
[0021] A typical cycle of plasma enhanced cyclic chemical vapor
deposition for silicon nitride, silicon carbonitride, silicon
oxynitride, and silicon carboxynitride is shown in FIG. 1.
[0022] The remote plasma chamber is a Litmas RPS manufactured by
Advanced Energy Industries, Inc. The Litmas RPS is a cylindrical
inductive plasma source (quartz chamber) integrated with a
solid-state RF power delivery system. Water cooled coils are
wrapped around the chamber to provide cooling for the chamber and
to form the RF antenna. The frequency operating range is between
1.9 MHz and 3.2 MHz. The DC output power range is 100 W to 1500
W.
[0023] The ALD system is a Savannah 100 manufactured by Cambridge
NanoTech, Inc. The ALD reactor is anodized aluminum and
accommodates a 100 mm silicon substrate. The ALD reactor has an
embedded disk-shaped heating element which heats the substrate from
the bottom. There is also a tubular heater embedded in the reactor
wall. The precursor valve manifold is enclosed within a heating
block, and heating jackets are used to heat the precursor vessels.
The ALD valves in the precursor valve manifold are three-way
valves, which continuously supply 10-100 sccm of inert gas to the
ALD reactor.
[0024] The deposition process for silicon nitride, silicon
carbonitride, silicon oxynitride, and silicon carboxynitride is
described in the following.
[0025] In the first step of the process, ammonia plasma is
generated in a remote plasma chamber installed approximately 12
inches upstream of the deposition chamber and is supplied to the
deposition chamber at a predetermined volume flow rate and for a
predetermined time. Typically, the ammonia plasma is supplied to
the ALD chamber by opening the gate valve between the remote plasma
head and the ALD reactor for a period of 0.1 to 80 seconds to allow
the ammonia radicals to be sufficiently adsorbed so as to saturate
a substrate surface. During deposition, the ammonia flow rate
supplied to the inlet of the remote plasma chamber is typically in
the range of 1 to 100 sccm. The RF power in the plasma chamber is
variable between 100 W and 1500 W. Deposition temperatures are
conventional and range from about 200 to 600.degree. C., preferably
from 200 to 400.degree. C. for atomic layer deposition and 400 to
600.degree. C. for cyclic chemical vapor deposition. Pressures of
from 50 mtorr to 100 torr are exemplary. In addition, to ammonia,
other nitrogen-containing source can be nitrogen, hydrazine,
monoalkylhydrozine, dialkylhydrozine, and mixture thereof.
[0026] In the second step of the process, an inert gas, such as Ar,
N.sub.2, or He, is used to sweep unreacted ammonia radicals from
the chamber. Typically in a cyclic deposition process, a gas, such
as Ar, N.sub.2, or He, is supplied into the chamber at a flow rate
of 10 to 100 sccm, thereby purging the ammonia radicals and any
byproducts that remain in the chamber.
[0027] In the third step of the process, an organoaminosilane, such
as diethylaminosilane (DEAS), di-iso-propylaminosilane (DIPAS),
di-tert-butylaminosilane (DTBAS), di-sec-butylaminosilane,
di-tert-pentylamino silane and mixtures thereof, is introduced into
the chamber at a predetermined molar volume. e.g., from 1 to 100
micromoles for a predetermined time period, preferably about 0.005
to 10 seconds. The silicon precursor reacts with the ammonia
radicals adsorbed on the surface of the substrate resulting in the
formation of silicon nitride. Conventional deposition temperatures
of from 200 to 500.degree. C. and pressures of from 50 mtorr to 100
torr are employed.
[0028] In the fourth step of the process, an inert gas, such as Ar,
N.sub.2, or He, is used to sweep unreacted organoaminosilane from
the chamber. Typically in a cyclic deposition process, a gas, such
as Ar, N.sub.2, or He, is supplied into the chamber at a flow rate
of 10 to 100 sccm, thereby purging the organoaminosilane and any
byproducts that remain in the chamber.
[0029] The four process steps described above comprise a typical
ALD process cycle. This ALD process cycle is repeated several times
until the desired film thickness is obtained.
[0030] FIG. 2. exhibits a typical ALD saturation curve at a
substrate temperature of 400.degree. C.
[0031] A typical cycle of plasma enhanced cyclic chemical vapor
deposition for silicon oxynitride and carbon doped silicon oxide is
shown in FIG. 3.
[0032] In the first step of the process, oxygen plasma is generated
in a remote plasma chamber installed approximately 12 inches
upstream of the deposition chamber and is supplied to the
deposition chamber at a predetermined volume flow rate and for a
predetermined time. Typically, the oxygen plasma is supplied to the
ALD chamber by opening the gate valve between the remote plasma
head and the ALD reactor for a period of 0.1 to 80 seconds to allow
the oxygen containing radicals to be sufficiently adsorbed so as to
saturate a substrate surface. During deposition, the oxygen flow
rate supplied to the inlet of the remote plasma chamber is
typically in the range of 1 to 100 sccm. The RF power in the plasma
chamber is variable between 100 W and 1500 W. Deposition
temperatures are conventional and range from about 200 to
600.degree. C., preferably from 200 to 400.degree. C. for atomic
layer deposition and 400 to 600.degree. C. for cyclic chemical
vapor deposition. Pressures of from 50 mtorr to 100 torr are
exemplary. In addition to oxygen, other oxygen-containing source
can be ozone, nitrous oxide, and mixture thereof.
[0033] In the second step of the process, an inert gas, such as Ar,
N.sub.2, or He, is used to sweep unreacted oxygen containing
radicals from the chamber. Typically in a cyclic deposition
process, a gas, such as Ar, N.sub.2, or He, is supplied into the
chamber at a flow rate of 10 to 100 sccm, thereby purging the
oxygen containing radicals and any byproducts that remain in the
chamber.
[0034] In the third step of the process, an organoaminosilane, such
as diethylaminosilane (DEAS), di-iso-propylaminosilane (DIPAS),
di-tert-butylaminosilane (DTBAS), di-sec-butylaminosilane,
di-tert-pentylamino silane and mixtures thereof, is introduced into
the chamber at a predetermined molar volume. e.g., from 1 to 100
micromoles for a predetermined time period, preferably about 0.005
to 10 seconds. The silicon precursor reacts with the oxygen
containing radicals adsorbed on the surface of the substrate
resulting in the formation of silicon oxide. Conventional
deposition temperatures of from 200 to 500.degree. C. and pressures
of from 50 mtorr to 100 torr are employed.
[0035] In the fourth step of the process, an inert gas, such as Ar,
N.sub.2, or He, is used to sweep unreacted organoaminosilane from
the chamber. Typically in a cyclic deposition process, a gas, such
as Ar, N.sub.2, or He, is supplied into the chamber at a flow rate
of 10 to 100 sccm, thereby purging the organoaminosilane and any
byproducts that remain in the chamber.
[0036] The four process steps described above comprise an ALD
process cycle. This ALD process cycle is repeated several times
until the desired film thickness is obtained.
EXAMPLE 1
[0037] In an ALD reactor, the said silicon precursor was introduced
along with NH.sub.3 after the reactor was pumped down to a vacuum
level of .about.40 mT and purged with 10 sccm N.sub.2. The
deposition was performed at a temperature of 400.degree. C. Remote
plasma was also used to reduce the required deposition temperature.
The said silicon precursor was pre-heated to 40.degree. C. in a
bubbler wrapped with a heat jacket before being introduced into the
reactor. The results are summarized in Table 1.
[0038] Since only very small amount of chemical was used during one
deposition, the flow rate (amount per unit time) of the said
silicon precursor out of the bubbler can then be considered to be
constant at a given temperature. Therefore, the amount of the said
silicon precursor added into the ALD reactor is linearly
proportional to the pulse time used to introduce the said silicon
precursor.
[0039] As can be seen from Table 1, the rate of forming silicon
nitride films changes as the amount of the said silicon precursor
added into the reactor changes even when the deposition temperature
and the amount of nitrogen precursor are kept the same.
[0040] It can also be seen from Table 1, when other processing
conditions are kept the same, the rate of forming silicon nitride
films increases initially from 0.156 A/cycle as the pulse time (or
amount) of the said silicon precursor increases from 0.01 seconds
to 0.05 seconds. Then, however, the rate remains almost unchanged
after even more silicon precursor is added. This suggests that the
films formed using the Si precursor are indeed ALD films.
TABLE-US-00001 TABLE 1 Temperature NH.sub.3 pulse Silicon precursor
Deposition Rate (.degree. C.) (second) pulse time (second)
(A/cycle) 400 3 0.01 0.156 400 3 0.025 0.272 400 3 0.05 0.318 400 3
0.1 0.307 400 3 0.2 0.3
EXAMPLE 2
[0041] The deposited ALD films were analyzed using FTIR. The FTIR
spectrum for the films is shown in FIG. 4. As can be seen from FIG.
4 there is an absorbance peak at 1046 cm.sup.-1, suggesting oxide
presence in the film. The peak at 3371 is an N--H stretch (with
some O--H) and has the corresponding rock at the shoulder near 1130
cm-1. The 2218 peak is from Si--H and its broad shape indicates a
low stress film. The 813 peak is near Si--N. An EDX analysis of the
deposited films also confirmed the presence of Si and N in the
films.
[0042] The embodiments of the present invention listed above,
including the working examples, are exemplary of numerous
embodiments that may be made of the present invention. It is
contemplated that numerous other configurations of the process may
be used, and the materials used in the process may be selected from
numerous materials other than those specifically disclosed. In
short, the present invention has been set forth with regard to
particular embodiments, but the full scope of the present invention
should be ascertained from the claims as follow.
* * * * *