U.S. patent application number 16/388225 was filed with the patent office on 2019-09-05 for compositions and methods using same for deposition of silicon-containing films.
This patent application is currently assigned to Versum Materials US, LLC. The applicant listed for this patent is Versum Materials US, LLC. Invention is credited to Moo-Sung Kim, Xinjian Lei, Matthew R. MacDonald, Manchao Xiao.
Application Number | 20190271075 16/388225 |
Document ID | / |
Family ID | 54477308 |
Filed Date | 2019-09-05 |
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United States Patent
Application |
20190271075 |
Kind Code |
A1 |
Lei; Xinjian ; et
al. |
September 5, 2019 |
Compositions and Methods Using Same for Deposition of
Silicon-Containing Films
Abstract
Described herein are methods and compositions for forming a
silicon-containing film or material such as without limitation a
silicon oxide, silicon nitride, silicon oxynitride, a carbon-doped
silicon nitride, or a carbon-doped silicon oxide film in a
semiconductor deposition process, such as without limitation, a
plasma enhanced atomic layer deposition of silicon-containing
film.
Inventors: |
Lei; Xinjian; (Tempe,
AZ) ; Kim; Moo-Sung; (Tempe, AZ) ; MacDonald;
Matthew R.; (Tempe, AZ) ; Xiao; Manchao;
(Tempe, AZ) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Versum Materials US, LLC |
Tempe |
AZ |
US |
|
|
Assignee: |
Versum Materials US, LLC
Tempe
AZ
|
Family ID: |
54477308 |
Appl. No.: |
16/388225 |
Filed: |
April 18, 2019 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
15520330 |
Apr 19, 2017 |
10316407 |
|
|
PCT/US2015/057045 |
Oct 23, 2015 |
|
|
|
16388225 |
|
|
|
|
62068248 |
Oct 24, 2014 |
|
|
|
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
C23C 16/36 20130101;
H01L 21/02222 20130101; C23C 16/48 20130101; H01L 21/02126
20130101; H01L 21/0234 20130101; H01L 21/02274 20130101; H01L
21/02326 20130101; H01L 21/02337 20130101; H01L 21/02216 20130101;
H01L 21/02219 20130101; H01L 21/0228 20130101; C23C 16/345
20130101; H01L 21/02211 20130101; H01L 21/02271 20130101; H01L
21/02348 20130101; H01L 21/02164 20130101; C23C 16/401 20130101;
C23C 16/50 20130101 |
International
Class: |
C23C 16/40 20060101
C23C016/40; C23C 16/50 20060101 C23C016/50; C23C 16/36 20060101
C23C016/36; H01L 21/02 20060101 H01L021/02; C23C 16/34 20060101
C23C016/34; C23C 16/48 20060101 C23C016/48 |
Claims
1. A method for depositing a silicon nitride film on at least a
portion of a surface of a substrate, the method comprising: placing
the substrate into a reactor; introducing into the reactor an at
least one silicon precursor compound having the following Formulae
IIA through IID: ##STR00006## wherein R is selected from the group
consisting of hydrogen, a halide atom, a linear C.sub.1 to C.sub.10
alkyl group, a branched C.sub.3 to C.sub.10 alkyl group, a linear
or branched C.sub.3 to C.sub.12 alkenyl group, a linear or branched
C.sub.3 to C.sub.12 alkenyl group, a linear or branched C.sub.3 to
C.sub.12 alkynyl group, a C.sub.4 to C.sub.10 cyclic alkyl group,
and a C.sub.6 to C.sub.10 aryl group under conditions sufficient to
provide a chemisorbed layer, wherein the silicon precursor contains
less than about 100 ppm of halide ions; c. purging the reactor with
a purge gas; d. introducing a plasma source comprising nitrogen
into the reactor to react with at least a portion of the
chemisorbed layer; and e. optionally purge the reactor with an
inert gas; and wherein the steps b through e are repeated until a
desired thickness of the silicon nitride film is obtained.
2. The method of claim 1 wherein the plasma source is selected from
the group consisting of nitrogen plasma, nitrogen/helium plasma,
nitrogen/argon plasma, ammonia plasma, ammonia/helium plasma,
ammonia/argon/plasma, helium plasma, argon plasma, hydrogen plasma,
hydrogen/helium plasma, hydrogen/argon plasma, organic amine
plasma, and mixtures thereof.
3. The method of claim 1 wherein the at least one silicon precursor
compound comprises bis(disilylamino)silane.
4. The method of claim 3, wherein the halide ions comprise chloride
ions.
5. The method of claim 3, wherein the chloride ions, if present,
are present at a concentration of 50 ppm or less.
6. The method of claim 3, wherein the chloride ions, if present,
are present at a concentration of 10 ppm or less.
7. The method of claim 3, wherein the chloride ions, if present,
are present at a concentration of 5 ppm or less.
8. The method of claim 3, wherein the composition is free of
chloride ions.
9. The method of claim 1 wherein the plasma in step d is generated
at a power density ranging from about 0.01 to about 1.5
W/cm.sup.2.
10. The method of claim 1 wherein the silicon nitride has a
reflective index of 2.0.
11. A composition for depositing a silicon nitride or silicon oxide
film, the composition comprising: at least one silicon precursor
compound having the following Formulae IIA and/or IIB: ##STR00007##
wherein R is selected from the group consisting of hydrogen, a
halide atom, a linear C.sub.1 to C.sub.10 alkyl group, a branched
C.sub.3 to C.sub.10 alkyl group, a linear or branched C.sub.3 to
C.sub.12 alkenyl group, a linear or branched C.sub.3 to C.sub.12
alkenyl group, a linear or branched C.sub.3 to C.sub.12 alkynyl
group, a C.sub.4 to C.sub.10 cyclic alkyl group, and a C.sub.6 to
C.sub.10 aryl group, wherein the silicon precursor comprises less
than about 100 ppm of halides.
12. The composition of claim 11, wherein the halides comprise
chloride ions.
13. The composition of claim 11, wherein the chloride ions, if
present, are present at a concentration of 50 ppm or less.
14. The composition of claim 11, wherein the chloride ions, if
present, are present at a concentration of 10 ppm or less.
15. The composition of claim 11, wherein the chloride ions, if
present, are present at a concentration of 5 ppm or less.
16. The composition of claim 11, wherein the composition is free of
chloride ions.
17. The composition of claim 11 wherein the at least one silicon
precursor compound comprises bis(disilylamino)silane.
18. The composition of claim 17, wherein the chloride ions, if
present, are present at a concentration of 50 ppm or less.
19. The composition of claim 17, wherein the chloride ions, if
present, are present at a concentration of 10 ppm or less.
20. The composition of claim 17, wherein the chloride ions, if
present, are present at a concentration of 5 ppm or less.
21. The composition of claim 17, wherein the composition is free of
chloride ions.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This application is a divisional of U.S. patent application
Ser. No. 15/520,330, filed on Apr. 19, 2017, which is a U.S.
national stage application of International Application No.
PCT/US2015/057045, filed on Oct. 23, 2015, which, claims the
benefit of priority under 35 U.S.C. .sctn. 119(e) to U.S.
application Ser. No. 62/068,248, filed on Oct. 24, 2014, the
disclosures of which are hereby incorporated by reference in their
entirety.
BACKGROUND OF THE INVENTION
[0002] Described herein is a process and a composition for the
fabrication of an electronic device. More specifically, described
herein are compositions for forming a silicon-containing film in a
plasma enhanced atomic layer deposition (PEALD) process. Exemplary
silicon-containing films that can be deposited using the
compositions and methods described herein include, without
limitation, stoichiometric or non-stoichiometric, silicon nitride,
silicon carbonitride, silicon oxynitride, silicon aluminum nitride,
silicon oxide, and silicon carboxide films.
[0003] Silicon nitride is often used as an insulator and chemical
barrier in manufacturing integrated circuits, to electrically
isolate different structures or as an etch mask in bulk
micromachining. As a passivation layer for microchips, it is
superior to silicon dioxide, as it is a significantly better
diffusion barrier against water molecules and sodium ions, two
major sources of corrosion and instability in microelectronics. It
is also used as a dielectric between polysilicon layers in
capacitors in analog chips.
[0004] One of the commercial methods for forming silicon nitride or
films employs dichlorosilane and ammonia as the precursor
reactants. Low pressure chemical vapor deposition (LPCVD) using
precursors such as dichlorosilane and ammonia require high
deposition temperatures to get the best film properties. For
example, temperatures greater than 750.degree. C. may be required
to obtain reasonable growth rates and uniformities. Other
processing issues involve the hazardous aspects of chlorine and
chlorine byproducts.
[0005] Many of the newer semiconductor devices require silicon
nitride films that have low etch rates, high film stresses, or
both. It is also preferred, and sometimes necessary, that the films
be formed at temperatures below 600.degree. C. while maintaining
good electrical characteristics. Film hardness is yet another
factor to consider in the design of the electrical components and
the silicon nitride films do offer extremely hard films.
[0006] The deposition of conformal, stoichiometric and
non-stoichiometric silicon nitride films at low temperature, e.g.,
temperatures of about 500.degree. C. or less or about 400.degree.
C. or less, which meet one or more criteria to be considered a high
quality film, has been a long-standing industry challenge. There
are several applications in semiconductor field such as advanced
patterning or spacer which require high quality films. A silicon
nitride film is considered a "high quality" film if it has one or
more of the following characteristics: a density of 2.0 grams per
cubic centimeter (g/cc) or greater, a low wet etch rate (as
measured in dilute hydrofluoric acid (HF)), and combinations
thereof compared to other silicon nitride films. In these or other
embodiments, the refractive index for the silicon nitride film
should be 1.8 or greater.
[0007] Accordingly, there is a need in the art to provide a low
temperature (e.g., processing temperature of about 500.degree. C.
or less) method for depositing a conformal, high quality, silicon
nitride film wherein the film has one or more of the following
characteristics: a reflective index of 1.8 or higher, a density of
2.0 grams per cubic centimeter (g/cc) or greater, a low wet etch
rate (as measured in dilute hydrofluoric acid (HF)), and
combinations thereof compared to other silicon nitride films using
other deposition methods or precursors.
BRIEF SUMMARY OF THE INVENTION
[0008] Described herein are methods and compositions for forming
stoichiometric or non-stoichiometric silicon nitride films, which
may further comprise carbon, oxygen, or combinations thereof, onto
at least a portion of a substrate. In one aspect, the composition
for depositing a silicon nitride film comprises: at least one
silicon precursor compound selected from the group consisting
of:
##STR00001##
wherein substituent R is independently selected from a hydrogen, a
halide atom, a linear C.sub.1 to C.sub.10 alkyl group; a branched
C.sub.3 to C.sub.10 alkyl group; a linear or branched C.sub.3 to
C.sub.12 alkenyl group; a linear or branched C.sub.3 to C.sub.12
alkenyl group; a linear or branched C.sub.3 to C.sub.12 alkynyl
group; a C.sub.4 to C.sub.10 cyclic alkyl group; and a C.sub.6 to
C.sub.10 aryl group. In an alternative embodiment, the silicon
precursor compound described herein having Formulae IIA through IID
can be used to deposit other silicon-containing films or materials
such as, without limitation, silicon oxide films.
[0009] In another aspect, there is provided a composition for
forming a silicon-containing material comprising: (a) at least one
silicon precursor compound selected from the group consisting
of:
##STR00002##
wherein substituent R is independently selected from a hydrogen, a
halide atom, a linear C.sub.1 to C.sub.10 alkyl group; a branched
C.sub.3 to C.sub.10 alkyl group; a linear or branched C.sub.3 to
C.sub.12 alkenyl group; a linear or branched C.sub.3 to C.sub.12
alkenyl group; a linear or branched C.sub.3 to C.sub.12 alkynyl
group; a C.sub.4 to C.sub.10 cyclic alkyl group; and a C.sub.6 to
C.sub.10 aryl group; and (b) a solvent, wherein the solvent has a
boiling point and wherein the difference between the boiling point
of the solvent and that of the at least one precursor compound is
40.degree. C. or less, and wherein the composition is substantially
free of halide ions. In certain embodiments of the composition
described herein, exemplary solvent(s) can include, without
limitation, ether, tertiary amine, alkyl hydrocarbon, aromatic
hydrocarbon, tertiary aminoether, and combinations thereof.
[0010] In another aspect, there is provided a method for depositing
a silicon nitride film, the method comprising: [0011] a. placing
one or more substrates into a reactor; [0012] b. introducing at
least one silicon precursor compound selected from the group
consisting of:
##STR00003##
[0012] wherein substituent R is independently selected from a
hydrogen, a halide atom, a linear C.sub.1 to C.sub.10 alkyl group;
a branched C.sub.3 to C.sub.10 alkyl group; a linear or branched
C.sub.3 to C.sub.12 alkenyl group; a linear or branched C.sub.3 to
C.sub.12 alkenyl group; a linear or branched C.sub.3 to C.sub.12
alkynyl group; a C.sub.4 to C.sub.10 cyclic alkyl group; and a
C.sub.6 to C.sub.10 aryl group wherein at least a portion of the
compound reacts under processing conditions sufficient to provide a
chemisorbed layer; [0013] c. purging the reactor with a purge gas;
[0014] d. introducing a plasma source comprising nitrogen into the
reactor to react with at least a portion of the chemisorbed layer
wherein the plasma is generated at a power density ranging from
about 0.01 to about 1.5 W/cm.sup.2; and [0015] e. optionally purge
the reactor with an inert gas; and wherein the steps b through e
are repeated until a desired thickness of the silicon nitride film
is obtained.
BRIEF DESCRIPTION OF SEVERAL VIEWS OF THE DRAWINGS
[0016] FIG. 1 provides the relationship between silicon nitride
film thickness measured in Angstroms (.ANG.) and temperature of the
plasma enhanced atomic layer deposition of silicon nitride using
the Formula IIB precursor compound and method described in Example
2.
[0017] FIG. 2 provides the relationship between the growth of
deposited film thickness measured in .ANG./cycle and silicon
precursor pulse time (measured in seconds) for the precursor
compound and method described in Example 2.
[0018] FIG. 3 provides the silicon nitride film thickness measured
in .ANG. versus the number of cycles using Formula IIB precursor
and nitrogen plasma at 300.degree. C. described in Example 2.
DETAILED DESCRIPTION OF THE INVENTION
[0019] The deposition of conformal, stoichiometric and
non-stoichiometric silicon nitride films at low temperatures, e.g.,
temperatures of 500.degree. C. or less or 400.degree. C. or less,
which meet one or more criteria to be considered a high quality
film, has been a long-standing industry challenge. Throughout the
description, the term "silicon nitride" as used herein refers to a
film comprising silicon and nitrogen selected from the group
consisting of stoichiometric or non-stoichiometric silicon nitride,
silicon carbonitride, silicon carboxynitride, silicon aluminum
nitride and there mixture thereof. A silicon nitride film is
considered a "high quality" film if it has one or more of the
following characteristics: a density of 2.0 grams per cubic
centimeter (g/cc) or greater, a low wet etch rate (as measured in
dilute hydrofluoric acid (HF)), and combinations thereof compared
to other silicon nitride films. In these or other embodiments, the
refractive index for the silicon nitride film should be 1.8 or
higher. In one embodiment, described herein is composition for
forming a silicon-containing film or material using silicon
precursor compounds having Formulae IIA through IID. Also described
herein is an atomic layer deposition (ALD) or ALD-like method that
deposits a silicon nitride film at a low temperature, or one or
more deposition temperatures ranging from about 20.degree. C. to
about 500.degree. C., using the Formula IIA through IID described
herein in a plasma process which comprises nitrogen and optionally
a noble or inert gas.
[0020] Described herein are methods for forming a stoichiometric or
non-stoichiometric silicon nitride film comprising silicon and
nitrogen onto at least a portion of a substrate. In certain
embodiments, the silicon nitride film may further comprise carbon.
In certain embodiments, the silicon nitride film may further
comprise aluminum such as a silicon aluminum nitride film. In
certain embodiments, the silicon nitride film further comprises
oxygen such as a silicon oxynitride film. In this or other
embodiments, the silicon nitride film comprises oxygen and carbon
such as a silicon carboxynitride film.
[0021] In alternative embodiments, the composition comprising at
least one silicon precursor compound having Formulae IIA through
IID may be used to deposit a silicon oxide material or film.
Throughout the description, the term "silicon oxide" as used herein
refers to a film comprising silicon and nitrogen selected from the
group consisting of stoichiometric or non-stoichiometric silicon
oxide, carbon doped silicon oxide, silicon carboxynitride and
mixtures thereof.
[0022] The silicon nitride films described herein are deposited
using at least one silicon precursor compound represented by
Formulae IIA through IID below:
##STR00004##
wherein substituent R is independently selected from a hydrogen, a
halide atom, a linear C.sub.1 to C.sub.10 alkyl group; a branched
C.sub.3 to C.sub.10 alkyl group; a linear or branched C.sub.3 to
C.sub.12 alkenyl group; a linear or branched C.sub.3 to C.sub.12
alkenyl group; a linear or branched C.sub.3 to C.sub.12 alkynyl
group; a C.sub.4 to C.sub.10 cyclic alkyl group; and a C.sub.6 to
C.sub.10 aryl group.
[0023] While not being bound by theory, it is believed that the
silicon precursor compounds having three or more Si--N bonds, and
optionally three or more Si--H.sub.3 groups in Formula IIA, IIB and
IID, are more reactive towards at least a portion of the substrate
surface, thus anchoring more silicon fragments on the surface
during the deposition process. This in turn will increase the
growth rate of the film as well as provide better surface coverage
for substrate comprising surface features, such as without
limitation, pores, trenches, and/or vias, thereby allowing for the
deposition of a conformal silicon nitride or other
silicon-containing film on the surface. An example of a Formula IIB
compound is bis(disilylamino)silane (aka N,N'-disilyltrisilazane).
An example of a Formula IIC compound is tris (ethylsillyl) amine.
In embodiments wherein the silicon precursor compound is
tris(ethylsillyl)amine, it is believed that the ethylene acts as
leaving group in the deposition process thereby creating additional
Si reactive sites while at the same time lowering the Si--H content
in the precursor.
[0024] In Formulae IIA through IID above and throughout the
description, the term "linear alkyl" denotes a linear functional
group having from 1 to 10, 3 to 10, or 1 to 6 carbon atoms.
Exemplary linear alkyl groups include, but are not limited to,
methyl, ethyl, propyl, butyl, pentyl, and hexyl groups. In the
formula IIA through IID above and throughout the description, the
term "branched alkyl" denotes a branched functional group having
from 3 to 10, or 1 to 6 carbon atoms. Exemplary branched alkyl
groups include, but are not limited to, isopropyl, isobutyl,
sec-butyl, tert-butyl, iso-pentyl, tert-pentyl, isohexyl, and
neohexyl. In certain embodiments, the alkyl group may have one or
more functional groups such as, but not limited to, an alkoxy
group, a dialkylamino group or combinations thereof, attached
thereto. In other embodiments, the alkyl group does not have one or
more functional groups attached thereto. The alkyl group may be
saturated or, alternatively, unsaturated.
[0025] In Formulae IIA through IID above and throughout the
description, the term "halide" denotes a chloride, bromide, iodide,
or fluoride ion.
[0026] In Formulae IIA through IID above and throughout the
description, the term "cyclic alkyl" denotes a cyclic group having
from 3 to 10 or 5 to 10 atoms. Exemplary cyclic alkyl groups
include, but are not limited to, cyclobutyl, cyclopentyl,
cyclohexyl, and cyclooctyl groups. In certain embodiments, the
cyclic alkyl group may have one or more C.sub.1 to C.sub.10 linear,
branched substituents, or substituents containing oxygen or
nitrogen atoms. In this or other embodiments, the cyclic alkyl
group may have one or more linear or branched alkyls or alkoxy
groups as substituents, such as, for example, a methylcyclohexyl
group or a methoxycyclohexyl group.
[0027] In Formulae IIA through IID above and throughout the
description, the term "aryl" denotes an aromatic cyclic functional
group having from 3 to 10 carbon atoms, from 5 to 10 carbon atoms,
or from 6 to 10 carbon atoms. Exemplary aryl groups include, but
are not limited to, phenyl, benzyl, chlorobenzyl, tolyl, and
o-xylyl.
[0028] In Formulae IIA through IID above and throughout the
description, the term "alkenyl group" denotes a group which has one
or more carbon-carbon double bonds and has from 2 to 12, from 2 to
10, or from 2 to 6 carbon atoms. Exemplary alkenyl groups include,
but are not limited to, vinyl or allyl groups.
[0029] In Formulae IIA through IID above and throughout the
description, the term "alkynyl group" denotes a group which has one
or more carbon-carbon triple bonds and has from 2 to 12 or from 2
to 6 carbon atoms.
[0030] In Formulae IIA through IID above and throughout the
description, the term "unsaturated" as used herein means that the
functional group, substituent, ring or bridge has one or more
carbon double or triple bonds. An example of an unsaturated ring
can be, without limitation, an aromatic ring such as a phenyl ring.
The term "saturated" means that the functional group, substituent,
ring or bridge does not have one or more double or triple
bonds.
[0031] In certain embodiments, one or more of the alkyl group,
alkenyl group, alkynyl group, alkoxysilylalkyl group, alkoxy group,
aryloxy, aroyloxy, aryl group, and/or aromatic group in the
formulae may be "substituted" or have one or more atoms or group of
atoms substituted in place of, for example, a hydrogen atom.
Exemplary substituents include, but are not limited to, oxygen,
sulfur, halogen atoms (e.g., F, Cl, I, or Br), nitrogen, alkyl
groups, and phosphorous. In other embodiments, one or more of the
alkyl group, alkenyl group, alkynyl group, alkoxyalkyl group,
alkoxy group, alkylaminoalkyl group, aromatic and/or aryl group in
the formulae may be unsubstituted.
[0032] The method used to form the silicon-containing materials and
films described herein are deposition processes. Examples of
suitable deposition processes for the method disclosed herein
include, but are not limited to, plasma enhanced ALD (PEALD) or
plasma enhanced cyclic CVD (PECCVD) process. As used herein, the
term "chemical vapor deposition processes" refers to any process
wherein a substrate is exposed to one or more volatile precursors,
which react and/or decompose on the substrate surface to produce
the desired deposition. As used herein, the term "atomic layer
deposition process" refers to a self-limiting (e.g., the amount of
film material deposited in each reaction cycle is constant),
sequential surface chemistry that deposits silicon containing films
of materials onto substrates of varying compositions. Although the
precursors, reagents and sources used herein may be sometimes
described as "gaseous", it is understood that the precursors can be
either liquid or solid which are transported with or without an
inert gas into the reactor via direct vaporization, bubbling or
sublimation. In some case, the vaporized precursors can pass
through a plasma generator. In one embodiment, the silicon nitride
film is deposited using a plasma enhanced ALD process. In another
embodiment, the silicon nitride film is deposited using a plasma
enhanced CCVD process. The term "reactor" as used herein, includes
without limitation, reaction chamber or deposition chamber. The
ALD-like process is defined herein as a cyclic CVD process that
provides a high conformal silicon nitride film such as, silicon
nitride or silicon carbonitride on a substrate as shown by having
at least one of the following: percentage of non-uniformity of
about 5% or less as measured by ellipsometer, a deposition rate of
1 .ANG. or greater per cycle, or a combination thereof.
[0033] The silicon precursor compounds having Formulae IIA through
IID may be delivered to the reaction chamber such as a CVD or ALD
reactor in a variety of ways. In one embodiment, a liquid delivery
system may be utilized. In an alternative embodiment, a combined
liquid delivery and flash vaporization process unit may be
employed, such as, for example, the turbo vaporizer manufactured by
MSP Corporation of Shoreview, Minn., to enable low volatility
materials to be volumetrically delivered, which leads to
reproducible transport and deposition without thermal decomposition
of the precursor. In liquid delivery formulations, the precursors
described herein may be delivered in neat liquid form, or
alternatively, may be employed in solvent formulations or
compositions comprising same. Thus, in certain embodiments the
precursor formulations may include solvent component(s) of suitable
character as may be desirable and advantageous in a given end use
application to form a film on a substrate.
[0034] In one embodiment of the method described herein, a
substrate having a surface to which at least a portion of
silicon-containing film or materials is deposited thereupon, is
placed into a reactor deposition chamber. The temperature of the
substrate may be controlled to be less than the walls of the
reactor. The substrate temperature is held at a temperature from
about room temperature (e.g., 20.degree. C.) to about 500.degree.
C. Alternative ranges for the substrate temperature have one or
more of the following end points: 20, 50, 75, 100, 125, 150, 175,
200, 225, 250, 275, 300, 325, 350, 375, 400, 425, 450, 475, and
500.degree. C. Exemplary temperature ranges include the following:
20 to 475.degree. C., 100 to 400.degree. C. or 175 to 350.degree.
C.
[0035] Depending upon the deposition method, in certain
embodiments, the one or more silicon-containing precursor compounds
may be introduced into the reactor at a predetermined molar volume,
or from about 0.1 to about 1000 micromoles. In this or other
embodiments, the silicon precursor or the silicon precursor
comprising Formula IIA to IID and a solvent may be introduced into
the reactor for a predetermined time period. In certain
embodiments, the time period ranges from about 0.001 to about 500
seconds.
[0036] In certain embodiments, the silicon-containing films
comprise silicon nitride. In these embodiments, the
silicon-containing films deposited using the methods described
herein are formed in the presence of nitrogen-containing source. A
nitrogen-containing source may be introduced into the reactor in
the form of at least one nitrogen-containing source and/or may be
present incidentally in the other precursors used in the deposition
process. Suitable nitrogen-containing source gases may include, for
example, ammonia, hydrazine, monoalkylhydrazine, dialkylhydrazine,
plasma comprising nitrogen, plasma comprising nitrogen and
hydrogen, plasma comprising nitrogen and helium, plasma comprising
nitrogen and argon, ammonia plasma, plasma comprising nitrogen and
ammonia, plasma comprising ammonia and helium, plasma comprising
ammonia and argon plasma, NF.sub.3 plasma, organoamine plasma, and
mixtures thereof. In other embodiments, the plasma is selected from
the group consisting of hydrogen plasma, helium plasma, neon
plasma, argon plasma, xenon plasma, hydrogen/helium plasma,
hydrogen/argon plasma and mixtures thereof. In one particle
embodiment, the nitrogen containing source is substantially free of
(e.g., has 2 weight percent (wt. %) or less) hydrogen to avoid
introducing additional hydrogen into the final silicon nitride film
and is selected from the group consisting of nitrogen plasma,
nitrogen/helium, nitrogen/argon plasma. In another embodiment, the
nitrogen containing source is selected from monoalkylhydrazine,
dialkylhydrazine. For deposition of silicon carbonitride, the
nitrogen containing source can be selected from the group
consisting of organic amine plasma such as methylamine plasma,
dimethylamine plasma, trimethylamine plasma, ethylamine plasma,
diethylamine plasma, trimethylamine plasma, ethylenediamine plasma.
Throughout the description, the term "organic amine" as used herein
describes organic compound has at least one nitrogen atom. Examples
of organic amine, but are not limited to, methylamine, ethylamine,
propylamine, iso-propylamine, tert-butylamine, sec-butylamine,
tert-amylamine, ethylenediamine, dimethylamine, trimethylamine,
diethylamine, pyrrole, 2,6-dimethylpiperidine, di-n-propylamine,
di-iso-propylamine, ethylmethylamine, N-methylaniline, pyridine,
triethylamine. Similarly, throughout the description, the term
"organoamino group" as used herein refers to an organic group
consisting of at least one nitrogen atom derived from secondary or
primary organoamines as described above. "Organoamino group" does
not include --NH.sub.2 group.
[0037] In certain embodiments, the nitrogen-containing source is
introduced into the reactor at a flow rate ranging from about 1 to
about 2000 square cubic centimeters (sccm) or from about 1 to about
1000 sccm. The nitrogen-containing source can be introduced for a
time that ranges from about 0.1 to about 100 seconds. In
embodiments wherein the film is deposited by an ALD or a cyclic CVD
process, the precursor pulse can have a pulse duration that is
greater than 0.01 seconds, and the nitrogen-containing source can
have a pulse duration that is less than 0.01 seconds. In yet
another embodiment, the purge duration between the pulses that can
be as low as 0 seconds or is continuously pulsed without a purge
in-between.
[0038] In certain embodiments, the silicon-containing films
deposited using the methods described herein are formed in the
presence of oxygen using an oxygen-containing source, reagent or
precursor comprising oxygen. An oxygen-containing source may be
introduced into the reactor in the form of at least one
oxygen-containing source. In this or other embodiments, the
oxygen-containing source may be present incidentally in the other
precursors used in the deposition process. Suitable
oxygen-containing source gases may include, for example, water
(H.sub.2O) (e.g., deionized water, purifier water, and/or distilled
water), oxygen (O.sub.2), oxygen plasma, ozone (O.sub.3), NO,
N.sub.2O, NO.sub.2, carbon monoxide (CO), carbon dioxide (CO.sub.2)
and combinations thereof. In certain embodiments, the
oxygen-containing source is introduced into the reactor at a flow
rate ranging from about 1 to about 2000 square cubic centimeters
(sccm) or from about 1 to about 1000 sccm. The oxygen-containing
source can be introduced for a time that ranges from about 0.1 to
about 100 seconds. In one particular embodiment, the
oxygen-containing source comprises water having a temperature of
10.degree. C. or greater. In embodiments wherein the film is
deposited by an ALD or a cyclic CVD process, the precursor pulse
can have a pulse duration that is greater than 0.01 seconds, and
the oxygen-containing source can have a pulse duration that is less
than 0.01 seconds, while the water pulse duration can have a pulse
duration that is less than 0.01 seconds. In yet another embodiment,
the purge duration between the pulses that can be as low as 0
seconds or is continuously pulsed without a purge in-between. The
oxygen-containing source or reagent is provided in a molecular
amount less than a 1:1 ratio to the silicon precursor, so that at
least some carbon is retained in the as deposited
silicon-containing film.
[0039] In certain embodiments, the temperature of the reactor in
the introducing step is at one or more temperatures ranging from
about room temperature (e.g., 20.degree. C.) to about 500.degree.
C. Alternative ranges for the substrate temperature have one or
more of the following end points: 20, 50, 75, 100, 125, 150, 175,
200, 225, 250, 275, 300, 325, 350, 375, 400, 425, 450, 475, and
500.degree. C. Exemplary temperature ranges include the following:
20 to 475.degree. C., 100 to 400.degree. C. or 175 to 350.degree.
C.
[0040] Energy is applied to the at least one of the precursor
compound, nitrogen-containing source, oxygen-containing source,
other reagents, or a combination thereof to induce reaction and to
form the silicon-containing film or coating or a chemisorbed layer
on at least a portion of the substrate. Such energy can be provided
by, but not limited to, thermal, plasma, pulsed plasma, helicon
plasma, high density plasma, inductively coupled plasma, X-ray,
e-beam, photon, remote plasma methods, and combinations thereof. In
certain embodiments, a secondary RF frequency source can be used to
modify the plasma characteristics at the substrate surface. In
embodiments wherein the deposition involves plasma, the
plasma-generated process may comprise a direct plasma-generated
process in which plasma is directly generated in the reactor, or
alternatively a remote plasma-generated process in which plasma is
generated outside of the reactor and supplied into the reactor. In
certain embodiments of the method described herein, the plasma is
generated at a power density ranging from about 0.01 to about 1.5
W/cm.sup.2.
[0041] The deposition methods disclosed herein may involve one or
more purge gases. The purge gas, which is used to purge away
unconsumed reactants and/or reaction byproducts, is an inert gas
that does not react with the precursors. Exemplary purge gases
include, but are not limited to, argon (Ar), nitrogen (N.sub.2),
helium (He), neon, hydrogen (H.sub.2), and mixtures thereof. In
certain embodiments, a purge gas is supplied into the reactor at a
flow rate ranging from about 10 to about 2000 sccm for about 0.1 to
1000 seconds, thereby purging the unreacted material and any
byproduct that may remain in the reactor.
[0042] The respective step of supplying the precursors,
oxygen-containing source, the nitrogen-containing source, and/or
other precursors, source gases, and/or reagents may be performed by
changing the time for supplying them to change the stoichiometric
composition of the resultant film or material. A flow of argon
and/or other gas may be employed as a carrier gas to help deliver
the vapor of the at least one precursor compound to the reaction
chamber during the precursor pulsing. In certain embodiments, the
reaction chamber process pressure is about 10 Torr or less, 5 Torr
or less, 2 Torr or less, 1 torr or less.
[0043] In one embodiment of the ALD or CCVD method described
herein, a substrate is heated on a heater stage in a reaction
chamber that is exposed to the precursor compound initially to
allow the compound to chemically adsorb onto the surface of the
substrate. A purge gas such as nitrogen, argon, or other inert gas
purges away unabsorbed excess precursor compound from the process
chamber. After sufficient purging, a nitrogen-containing source may
be introduced into reaction chamber to react with the absorbed
surface followed by another gas purge to remove reaction
by-products from the chamber. The process cycle can be repeated to
achieve the desired film thickness. In other embodiments, pumping
under vacuum can be used to remove unabsorbed excess precursor
compound from the process chamber, after sufficient evacuation
under pumping, a nitrogen-containing source may be introduced into
reaction chamber to react with the absorbed surface followed by
another pumping down purge to remove reaction by-products from the
chamber. In yet another embodiment, the precursor compound and the
nitrogen-containing source can be co-flowed into reaction chamber
to react on the substrate surface to deposit silicon nitride. In a
certain embodiment of cyclic CVD, the purge step is not used.
[0044] In this or other embodiments, it is understood that the
steps of the methods described herein may be performed in a variety
of orders, may be performed sequentially or concurrently (e.g.,
during at least a portion of another step), and any combination
thereof. The respective step of supplying the precursors and the
nitrogen-containing source gases may be performed by varying the
duration of the time for supplying them to change the
stoichiometric composition of the resulting silicon-containing
film.
[0045] In one aspect, there is provided a method of forming a
silicon nitride film, the method comprising the steps of: [0046] a.
providing a substrate in a reactor; [0047] b. introducing into the
reactor an at least one silicon precursor compound selected from
the group consisting of:
##STR00005##
[0047] wherein substituent R is independently selected from a
hydrogen, a halide atom, a linear C.sub.1 to C.sub.10 alkyl group;
a branched C.sub.3 to C.sub.10 alkyl group; a linear or branched
C.sub.3 to C.sub.12 alkenyl group; a linear or branched C.sub.3 to
C.sub.12 alkenyl group; a linear or branched C.sub.3 to C.sub.12
alkynyl group; a C.sub.4 to C.sub.10 cyclic alkyl group; and a
C.sub.6 to C.sub.10 aryl group wherein at least a portion of the
compound reacts under processing conditions sufficient to provide a
chemisorbed layer; [0048] c. purging the reactor with a purge gas;
[0049] d. introducing a plasma comprising nitrogen into the reactor
to react with at least a portion of the chemisorbed layer and
provide at least one reactive site; and [0050] e. optionally purge
the reactor with an inert gas; and wherein the steps b through e
are repeated until a desired thickness of the silicon nitride film
is obtained.
[0051] The silicon precursors described herein and compositions
comprising the silicon precursors having three or more Si--N bonds,
and optionally three or more Si--H.sub.3 groups represented by
Formulae IIA through IID, according to the present invention are
preferably substantially free of halide ions such as chloride or
metal ions such as Al. As used herein, the term "substantially
free" as it relates to halide ions (or halides) such as, for
example, chlorides and fluorides, bromides, iodides, Al.sup.3+
ions, Fe.sup.2+, Fe.sup.3+, Ni.sup.2+, Cr.sup.3+ means less than 5
ppm (by weight), preferably less than 3 ppm, and more preferably
less than 1 ppm, and most preferably 0 ppm. Chlorides or metal ions
are known to act as decomposition catalysts for silicon precursors.
Significant levels of chloride in the final product can cause the
silicon precursors to degrade. The gradual degradation of the
silicon precursors may directly impact the film deposition process
making it difficult for the semiconductor manufacturer to meet film
specifications. In addition, the shelf-life or stability is
negatively impacted by the higher degradation rate of the silicon
precursors thereby making it difficult to guarantee a 1-2 year
shelf-life. Moreover, silicon precursors are known to form
flammable and/or pyrophoric gases upon decomposition such as
hydrogen and silane. Therefore, the accelerated decomposition of
the silicon precursors presents safety and performance concerns
related to the formation of these flammable and/or pyrophoric
gaseous byproducts.
[0052] Compositions according to the present invention that are
substantially free of halides can be achieved by (1) reducing or
eliminating chloride sources during chemical synthesis, and/or (2)
implementing an effective purification process to remove chloride
from the crude product such that the final purified product is
substantially free of chlorides. Chloride sources may be reduced
during synthesis by using reagents that do not contain halides such
as chlorodislanes, bromodisilanes, or iododislanes thereby avoiding
the production of by-products that contain halide ions. In
addition, the aforementioned reagents should be substantially free
of chloride impurities such that the resulting crude product is
substantially free of chloride impurities. In a similar manner, the
synthesis should not use halide based solvents, catalysts, or
solvents which contain unacceptably high levels of halide
contamination. The crude product may also be treated by various
purification methods to render the final product substantially free
of halides such as chlorides. Such methods are well described in
the prior art and, may include, but are not limited to purification
processes such as distillation, or adsorption. Distillation is
commonly used to separate impurities from the desire product by
exploiting differences in boiling point. Adsorption may also be
used to take advantage of the differential adsorptive properties of
the components to effect separation such that the final product is
substantially free of halide. Adsorbents such as, for example,
commercially available MgO--Al.sub.2O.sub.3 blends can be used to
remove halides such as chloride.
[0053] For those embodiments relating to a composition comprising a
solvent(s) and a silicon precursor having Formulae IIA through IID
described herein, the solvent or mixture thereof selected does not
react with the silicon precursors. The amount of solvent by weight
percentage in the composition ranges from 0.5% by weight to 99.5%
or from 10% by weight to 75%. In this or other embodiments, the
solvent has a boiling point (b.p.) similar to the b.p. of the
silicon precursor precursors of Formula II or the difference
between the b.p. of the solvent and the b.p. of the silicon
precursor precursors of Formula II is 40.degree. C. or less,
30.degree. C. or less, or 20.degree. C. or less, 10.degree. C. or
less, or 5.degree. C. or less. Alternatively, the difference
between the boiling points ranges from any one or more of the
following end-points: 0, 10, 20, 30, or 40.degree. C. Examples of
suitable ranges of b.p. difference include without limitation, 0 to
40.degree. C., 20.degree. to 30.degree. C., or 10.degree. to
30.degree. C. Examples of suitable solvents in the compositions
include, but are not limited to, an ether (such as 1,4-dioxane,
dibutyl ether), a tertiary amine (such as pyridine,
1-methylpiperidine, 1-ethylpiperidine, N,N'-Dimethylpiperazine,
N,N,N',N'-Tetramethylethylenediamine), a nitrile (such as
benzonitrile), an alkyl hydrocarbon (such as octane, nonane,
dodecane, ethylcyclohexane), an aromatic hydrocarbon (such as
toluene, mesitylene), a tertiary aminoether (such as
bis(2-dimethylaminoethyl) ether), or mixtures thereof. Some
non-limiting exemplary compositions include, but not limited to, a
composition comprising bis(disilylamino)silane (b.p. about
135.degree. C.) and octane (b.p. 125 to 126.degree. C.); a
composition comprising bis(disilylamino)silane (b.p. about
135.degree. C.) and ethylcyclohexane (b.p. 130-132.degree. C.); a
composition comprising bis(disilylamino)silane (b.p. about
135.degree. C.) and cyclooctane (b.p. 149.degree. C.); a
composition comprising bis(disilylamino)silane (b.p. about
135.degree. C.), and toluene (b.p. 115.degree. C.).
[0054] In another embodiment, a vessel for depositing a
silicon-containing film comprising one or more silicon precursor
compound having Formulae IIA through IID is described herein. In
one particular embodiment, the vessel comprises at least one
pressurizable vessel (preferably of stainless steel) fitted with
the proper valves and fittings to allow the delivery of one or more
precursors to the reactor for a CVD or an ALD process. In this or
other embodiments, the silicon precursor compound is provided in a
pressurizable vessel comprised of stainless steel and the purity of
the silicon precursor is 98% by weight or greater or 99.5% or
greater which is suitable for the majority of semiconductor
applications. In certain embodiments, such vessels can also have
means for mixing the precursors with one or more additional
precursor if desired. In these or other embodiments, the contents
of the vessel(s) can be premixed with an additional precursor.
Alternatively, the silicon precursor compounds described herein
and/or other precursor can be maintained in separate vessels or in
a single vessel having separation means for maintaining the silicon
precursor having Formulae IIA through IID and other precursor
separate during storage.
[0055] In certain embodiments, the method described herein further
comprises one or more additional silicon-containing precursors
other than the silicon precursors having the above Formulae IIA
through IID. Examples of additional silicon-containing precursors
include, but are not limited to, monoaminosilane (e.g.,
di-iso-propylaminosilane, di-sec-butylaminosilane,
phenylmethylaminosilane; organo-silicon compounds such as
trisilylamine (TSA); monoaminosilane (di-iso-propylaminosilane,
di-sec-butylaminosilane, phenylmethylaminosilane); siloxanes (e.g.,
hexamethyl disiloxane (HMDSO) and dimethyl siloxane (DMSO));
organosilanes (e.g., methylsilane, dimethylsilane, diethylsilane,
vinyl trimethylsilane, trimethylsilane, tetramethylsilane,
ethylsilane, disilylmethane, 2,4-disilapentane, 1,4-disilabutane,
2,5-disilahexane, 2,2-disilylpropane, 1,3,5-trisilacyclohexane and
fluorinated derivatives of these compounds); phenyl-containing
organo-silicon compounds (e.g., dimethylphenylsilane and
diphenylmethylsilane); oxygen-containing organo-silicon compounds,
e.g., dimethyldimethoxysilane;
1,3,5,7-tetramethylcyclotetrasiloxane;
1,1,3,3-tetramethyldisiloxane; 1,3,5,7-tetrasila-4-oxo-heptane;
2,4,6,8-tetrasila-3,7-dioxo-nonane;
2,2-dimethyl-2,4,6,8-tetrasila-3,7-dioxo-nonane;
octamethylcyclotetrasiloxane;
[1,3,5,7,9]-pentamethylcyclopentasiloxane;
1,3,5,7-tetrasila-2,6-dioxo-cyclooctane;
hexamethylcyclotrisiloxane; 1,3-dimethyldisiloxane;
1,3,5,7,9-pentamethylcyclopentasiloxane; hexamethoxydisiloxane, and
fluorinated derivatives of these compounds.
[0056] In certain embodiments, the silicon precursors having
Formulae IIA through IID described herein can also be used as a
dopant for metal containing films, such as but not limited to,
metal oxide films or metal nitride films. In these embodiments, the
metal containing film is deposited using an ALD or CVD process such
as those processes described herein using metal alkoxide, metal
amide, or volatile organometallic precursors. Examples of suitable
metal alkoxide precursors that may be used with the method
disclosed herein include, but are not limited to, group 3 to 6
metal alkoxide, group 3 to 6 metal complexes having both alkoxy and
alkyl substituted cyclopentadienyl ligands, group 3 to 6 metal
complexes having both alkoxy and alkyl substituted pyrrolyl
ligands, group 3 to 6 metal complexes having both alkoxy and
diketonate ligands; group 3 to 6 metal complexes having both alkoxy
and ketoester ligands; Examples of suitable metal amide precursors
that may be used with the method disclosed herein include, but are
not limited to, AlCl.sub.3, trimethylaluminum (TMA),
triethylaluminum, methylaluminum chloride,
tris(dimethylamino)aluminum (TDMAA), tris(dimethylamino)aluminum
(TDMAA), and tris(diethylamino)aluminum (TDEAA), and other volatile
aluminum precursors, tetrakis(dimethylamino)zirconium (TDMAZ),
tetrakis(diethylamino)zirconium (TDEAZ),
tetrakis(ethylmethylamino)zirconium (TEMAZ),
tetrakis(dimethylamino)hafnium (TDMAH),
tetrakis(diethylamino)hafnium (TDEAH), and
tetrakis(ethylmethylamino)hafnium (TEMAH),
tetrakis(dimethylamino)titanium (TDMAT),
tetrakis(diethylamino)titanium (TDEAT),
tetrakis(ethylmethylamino)titanium (TEMAT), tert-butylimino
tri(diethylamino)tantalum (TBTDET), tert-butylimino
tri(dimethylamino)tantalum (TBTDMT), tert-butylimino
tri(ethylmethylamino)tantalum (TBTEMT), ethylimino
tri(diethylamino)tantalum (EITDET), ethylimino
tri(dimethylamino)tantalum (EITDMT), ethylimino
tri(ethylmethylamino)tantalum (EITEMT), tert-amylimino
tri(dimethylamino)tantalum (TAIMAT), tert-amylimino
tri(diethylamino)tantalum, pentakis(dimethylamino)tantalum,
tert-amylimino tri(ethylmethylamino)tantalum,
bis(tert-butylimino)bis(dimethylamino)tungsten (BTBMW),
bis(tert-butylimino)bis(diethylamino)tungsten,
bis(tert-butylimino)bis(ethylmethylamino)tungsten, and combinations
thereof. Examples of suitable organometallic precursors that may be
used with the method disclosed herein include, but are not limited
to, group 3 metal cyclopentadienyls or alkyl cyclopentadienyls.
Exemplary Group 3 to 6 metal herein include, but not limited to, Y,
La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Er, Yb, Lu, Ti, Hf, Zr, V, Nb,
Ta, Cr, Mo, and W.
[0057] As mentioned previously, the method described herein may be
used to deposit a silicon nitride film on at least a portion of a
substrate. Examples of suitable substrates include but are not
limited to, silicon, SiO.sub.2, Si.sub.3N.sub.4, OSG, FSG, silicon
carbide, hydrogenated silicon carbide, silicon nitride,
hydrogenated silicon nitride, silicon carbonitride, hydrogenated
silicon carbonitride, boronitride, antireflective coatings,
photoresists, a flexible substrate such as IGZO, organic polymers,
porous organic and inorganic materials, metals such as copper and
aluminum, and diffusion barrier layers such as but not limited to
TiN, Ti(C)N, TaN, Ta(C)N, Ta, W, or WN. The films are compatible
with a variety of subsequent processing steps such as, for example,
chemical mechanical planarization (CMP) and anisotropic etching
processes.
[0058] The deposited films have applications, which include, but
are not limited to, computer chips, optical devices, magnetic
information storages, coatings on a supporting material or
substrate, microelectromechanical systems (MEMS),
nanoelectromechanical systems, thin film transistor (TFT), light
emitting diodes (LED), organic light emitting diodes (OLED), IGZO,
and liquid crystal displays (LCD).
[0059] In certain embodiments, the substrate has a surface feature.
In one particular embodiment, the substrate optionally has features
on it of a small size less than 100 .mu.m in width preferably less
than 1 .mu.m in width and most preferably less than 0.5 .mu.m in
width. The aspect ratio (the depth to width ratio) of the features,
if present, is greater than 1:1 and preferably greater than 4:1 and
most preferably greater than 8:1.
[0060] The substrate may be a single crystal silicon wafer, a wafer
of silicon carbide, a wafer of aluminum oxide (sapphire), a sheet
of glass, a metallic foil, an organic polymer film or may be a
polymeric, glass, silicon or metallic 3-dimensional article. The
substrate may be coated with a variety of materials well known in
the art including films of silicon oxide, silicon nitride,
amorphous carbon, silicon oxycarbide, silicon oxynitride, silicon
carbide, gallium arsenide, gallium nitride and the like. These
coatings may completely coat the substrate, may be in multiple
layers of various materials and may be partially etched to expose
underlying layers of material. The surface may also have on it a
photoresist material that has been exposed with a pattern and
developed to partially coat the substrate.
[0061] The following examples illustrate the method for depositing
silicon-containing materials or films described herein and are not
intended to limit it in any way.
WORKING EXAMPLES
[0062] In the following examples, unless stated otherwise,
properties were obtained from sample films that were deposited onto
medium resistivity (14-17 .OMEGA.-cm) single crystal silicon wafer
substrates. All film depositions were performed using the CN-1
reactor which has a showerhead design and uses 13.56 MHz direct
plasma or the cross flow type CN-1 reactor without plasma (for
comparative examples). In typical process conditions, unless stated
otherwise, the chamber pressure was fixed at a pressure ranging
from about 1 to about 5 torr. Additional inert gas such as argon or
nitrogen was used to maintain chamber pressure. Typical RF power
used was 125 W over electrode area of 150 mm wafer susceptor to
provide a power density of 0.7 W/cm.sup.2.
Example 1. Synthesis of Bis(Disilylamino)Silane (aka
N,N'-Disilyltrisilazane Formula IIB)
[0063] Under the protection of nitrogen, 2.5 grams of a solution of
B(C.sub.6F.sub.5).sub.3 in dodecane (0.2 weight (wt. %),
9.8.times.10.sup.-6 moles (mol)) was added to a 1 liter (L) round
bottomed flask containing trisilylamine (500 g, 4.66 moles (mol)).
Silane gas immediately began to evolve as gas bubbles. The reaction
solution was stirred for approximately 1 hour while maintaining an
internal temperature of 20.degree. C. Once the mass of the reaction
solution had decreased by 30%, 4,4-bipyridine was added (1.25 g,
8.00.times.10.sup.-3 moles) as a catalyst poison, and the bubbling
quickly stopped. After stirring the quenched reaction mixture for 2
h, the volatiles were vacuum transferred (25-35.degree. C./1 Torr)
into a second 1 L flask chilled to -78.degree. C. The collected
crude liquid was determined by gas chromatography (GC) and gas
chromatography-mass spectroscopy (GC-MS) to be a.about.1:1 mixture
of trisilylamine and N,N'-disilyltrisilazane. Purification by
fractional vacuum-distillation (58.degree. C./50 Torr) yielded 164
g of N,N'-disilyltrisilazane as a colorless liquid with a purity of
>99%. boiling point (b.p.)=135.degree. C. GC-MS showed the
following mass peaks: 181 (M-1), 149, 119, 104, 91, 72.
Example 2. PEALD Silicon Nitride Film Using Bis(Disilylamino)Silane
(aka N,N'-Disilyltrisilazane, Formula IIB) and Nitrogen Plasma
[0064] The silicon wafer was loaded into the CN-1 reactor equipped
with showerhead design with 13.56 MHz direct plasma and heated to
300.degree. C. with chamber pressure of 2 torr.
Bis(disilylamino)silane was used as silicon precursor and nitrogen
plasma as plasma source. The ALD cycle was conducted using the
following process parameters.
[0065] a. Prepare the reactor and load wafer [0066] Chamber
pressure: 2 torr
[0067] b. Introduce a silicon precursor to the reactor [0068] Total
flow of nitrogen: 1000 standard cubic centimeters (sccm) [0069]
silicon precursor pulse: 1 second
[0070] c. Purge [0071] Total flow of nitrogen: 1000 sccm [0072]
Purge time: 10 seconds
[0073] d. Introduce plasma [0074] Total flow of nitrogen: 1000 sccm
[0075] Plasma power: 125 W [0076] Plasma pulse: 10 second
[0077] e. Purge [0078] Total flow of nitrogen: 1000 sccm [0079]
Purge time: 10 seconds
[0080] Steps b to e were repeated for 300 cycles. The refractive
index of the resulting silicon nitride film was 2.0 whereas the
growth per cycle (GPC) was about 0.90 .ANG./cycle, demonstrating
high quality silicon nitride can be achieved using the
bis(disilylamino)silane precursor compound.
[0081] Additional experiments were designed to further confirm the
PEALD behavior of bis(disilylamino)silane as silicon precursor.
FIG. 1 shows the temperature dependence of the plasma enhanced
atomic layer deposition of silicon nitride using Formula IIB
precursor and nitrogen plasma, indicating that ALD window for this
precursor is at least up to .about.400.degree. C. FIG. 2 shows the
film thickness of as-deposited silicon nitride vs pulse time of
Formula IIB precursor using nitrogen plasma at 300.degree. C.,
demonstrating the self-limiting behavior even at 0.1 s and
suggesting high reactivity of Formula IIB precursor. FIG. 3 shows
the film thickness of as-deposited silicon nitride vs the number of
cycles using Formula IIB precursor and nitrogen plasma at
300.degree. C., demonstrating the growth per cycle is about 0.9
.ANG./cycle.
[0082] In a further experiment, steps b to e were repeated for 300
cycles except that the plasma power in step d was set to 250 Watts.
The resultant film thickness of silicon nitride was 230 .ANG.,
corresponding to a growth per cycle (GPC) of 0.77 .ANG./cycle. The
refractive index of the silicon nitride film was 2.0.
Example 3. PEALD Silicon Nitride Film Using Bis(Disilylamino)Silane
(aka N,N'-Disilyltrisilazane, Formula IIB) and Ammonia Plasma
[0083] The silicon wafer was loaded into the CN-1 reactor equipped
with showerhead design with 13.56 MHz direct plasma and heated to
300.degree. C. with chamber pressure of 2 torr.
Bis(disilylamino)silane was used as silicon precursor and ammonia
plasma as plasma source. The ALD cycle was conducted using the
following process parameters.
[0084] a. Prepare the reactor and load wafer [0085] Chamber
pressure: 2 torr
[0086] b. Introduce a silicon precursor to the reactor [0087] Total
flow of argon: 1000 sccm [0088] silicon precursor pulse: 0.2
second
[0089] c. Purge [0090] Total flow of argon: 1000 sccm [0091] Purge
time: 10 seconds
[0092] d. Introduce plasma [0093] Total flow of argon: 1000 sccm
[0094] Total flow of ammonia: 500 sccm [0095] Plasma power: 125 W
[0096] Plasma pulse: 10 second
[0097] e. Purge [0098] Total flow of nitrogen: 1000 sccm [0099]
Purge time: 10 seconds
[0100] Steps b to e were repeated for 300 cycles. The thickness of
the as deposited silicon nitride was about 29 .ANG., suggesting
that the ammonia plasma is not as good of a nitrogen source
compared to nitrogen plasma under similar conditions such as those
in Example 2.
Comparable Example 3. Thermal ALD Silicon Nitride Film Using
Bis(Disilylamino)Silane (aka N,N'-Disilyltrisilazane, Formula IIB)
and Ammonia
[0101] The silicon wafer was loaded into the CN-1 reactor equipped
with showerhead design with 13.56 MHz direct plasma and heated to
350.degree. C. with chamber pressure of 2 torr.
Bis(disilylamino)silane was used as the silicon precursor. The ALD
cycle was conducted using the following process parameters.
[0102] a. Prepare the reactor and load wafer [0103] Chamber
pressure: 2 torr
[0104] b. Introduce a silicon precursor to the reactor [0105] Total
flow of argon: 1000 sccm [0106] silicon precursor pulse: 0.2
second
[0107] c. Purge [0108] Total flow of argon: 1000 sccm [0109] Purge
time: 10 seconds
[0110] d. Introduce ammonia [0111] Total flow of argon: 1000 sccm
[0112] Total flow of ammonia: 500 sccm [0113] Pulse: 10 second
[0114] e. Purge [0115] Total flow of argon: 1000 sccm [0116] Purge
time: 10 seconds
[0117] Steps b to e were repeated for 200 cycles. No deposition was
observed on the substrate when a plasma was not used compared to
Example 3.
Example 4. PEALD Silicon Nitride Film Using Bis(Disilylamino)Silane
(aka N,N'-Disilyltrisilazane, Formula IIB) and Hydrogen/Nitrogen
Plasma
[0118] The silicon wafer was loaded into the CN-1 reactor equipped
with showerhead design with 13.56 MHz direct plasma and heated to
300.degree. C. with chamber pressure of 2 torr.
Bis(disilylamino)silane was used as silicon precursor and nitrogen
plasma as plasma source. The ALD cycle was conducted using the
following process parameters.
[0119] a. Prepare the reactor and load wafer [0120] Chamber
pressure: 2 torr
[0121] b. Introduce a silicon precursor to the reactor [0122] Total
flow of nitrogen: 1000 sccm [0123] silicon precursor pulse: 0.2
second
[0124] c. Purge [0125] Total flow of nitrogen: 1000 sccm [0126]
Purge time: 10 seconds
[0127] d. Introduce plasma [0128] Total flow of nitrogen: 1000 sccm
[0129] Total flow of hydrogen: 500 sccm [0130] Plasma power: 125 W
[0131] Plasma pulse: 10 second
[0132] e. Purge [0133] Total flow of nitrogen: 1000 sccm [0134]
Purge time: 10 seconds
[0135] Steps b to e were repeated for 300 cycles. The thickness of
as deposited silicon nitride was about 45 .ANG., corresponding a
GPC of 0.15 .ANG./cycle. This experiment suggests hydrogen/nitrogen
plasma is not a good nitrogen source compared to nitrogen plasma
under the similar conditions such as Example 2.
Example 5. PEALD Silicon Nitride Film Using Bis(Disilylamino)Silane
(aka N,N'-Disilyltrisilazane) Formula IIB and Hydrogen/Nitrogen
Plasma
[0136] The silicon wafer was loaded into the CN-1 reactor equipped
with showerhead design with 13.56 MHz direct plasma and heated to
300.degree. C. with chamber pressure of 2 torr.
Bis(disilylamino)silane was employed as silicon precursor and
nitrogen plasma as plasma source. The ALD cycle was conducted using
the following process parameters.
[0137] a. Prepare the reactor and load wafer [0138] Chamber
pressure: 2 torr
[0139] b. Introduce a silicon precursor to the reactor [0140] Total
flow of nitrogen: 500 sccm [0141] Total flow of hydrogen: 500 sccm
[0142] silicon precursor pulse: 0.2 second
[0143] c. Purge [0144] Total flow of nitrogen: 500 sccm [0145]
Total flow of hydrogen: 500 sccm [0146] Purge time: 10 seconds
[0147] d. Introduce plasma [0148] Total flow of nitrogen: 500 sccm
[0149] Total flow of hydrogen: 500 sccm [0150] Plasma power: 125 W
[0151] Plasma pulse: 10 second
[0152] e. Purge [0153] Total flow of nitrogen: 1000 sccm [0154]
Purge time: 10 seconds
[0155] Steps b to e were repeated for 300 cycles. The thickness of
as deposited silicon nitride was about 57 .ANG., corresponding a
GPC of 0.19 .ANG./cycle. This experiment suggests changing the
ratio of hydrogen vs nitrogen can improve the deposition rate of
silicon nitride, however growth per cycle is still much lower than
nitrogen plasma shown in Example 2. Another experiment was
conducted using 1 sec pulse for the silicon precursor in step b,
the thickness of as deposited silicon nitride was about 72 .ANG.,
corresponding a GPC of 0.24 .ANG./cycle.
* * * * *