U.S. patent application number 10/135190 was filed with the patent office on 2003-01-16 for compounds for forming alumina films using chemical vapor deposition method and process for preparing the compound.
This patent application is currently assigned to Shipley Company, L.L.C.. Invention is credited to Shin, Hyun-Koock.
Application Number | 20030010256 10/135190 |
Document ID | / |
Family ID | 24320504 |
Filed Date | 2003-01-16 |
United States Patent
Application |
20030010256 |
Kind Code |
A1 |
Shin, Hyun-Koock |
January 16, 2003 |
Compounds for forming alumina films using chemical vapor deposition
method and process for preparing the compound
Abstract
Organometallic compounds useful for forming aluminum films by
chemical vapor deposition are disclosed. Also disclosed are methods
of preparing the organometallic compounds and methods of forming
aluminum films.
Inventors: |
Shin, Hyun-Koock; (Suwon,
KR) |
Correspondence
Address: |
EDWARDS & ANGELL, LLP
Dike, Bronstein, Roberts & Cushman, IP Group
P.O. Box 9169
Boston
MA
02209
US
|
Assignee: |
Shipley Company, L.L.C.
Marlborough
MA
|
Family ID: |
24320504 |
Appl. No.: |
10/135190 |
Filed: |
April 29, 2002 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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10135190 |
Apr 29, 2002 |
|
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|
09580293 |
May 26, 2000 |
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Current U.S.
Class: |
106/287.17 ;
544/225; 544/64; 546/2; 548/402; 548/950; 548/955 |
Current CPC
Class: |
C07F 5/062 20130101;
C07F 5/066 20130101; C23C 16/403 20130101; C07D 295/033
20130101 |
Class at
Publication: |
106/287.17 ;
544/64; 544/225; 546/2; 548/402; 548/950; 548/955 |
International
Class: |
C23C 016/12; C23C
016/18; C07F 005/06 |
Claims
What is claimed is:
1. An organometallic complex useful for depositing a highly pure
alumina film on a substrate by chemical vapor deposition, having
the Formula I: R'R"R'"Al:L.sub.n (I) wherein R', R" and R'" are
independently selected from alkyl, perfluoroalkyl or alkoxy each of
which has 1 to 5 carbon atoms, or borate (BH.sub.4); L is one or
more organic Lewis bases capable of providing an unshared electron
pair to the aluminum metal center selected from thiophene,
thiopyran and organic amines of the Formulae II or III 24wherein R
is an alkyl having 1 to 4 carbon atoms; R.sup.1, R.sup.2, R.sup.21,
R.sup.22, R.sup.23 and R.sup.24 are independently selected from
hydrogen or alkyl having 1 to 2 carbon atoms; X is oxygen or
nitrogen having alkyl group; k and l are integers of 1 to 3; m is
an integer of 2 to 8; and n is an integer of 1 or 2.
2. The organometallic complex of claim 1 wherein R', R" and R'" are
independently selected from methyl, ethyl, iso-propoxy or
sec-butoxy.
3. The organometallic complex of claim 1 wherein the organic amine
is selected from alkylaziridine, alkylazetidine, alkylpyrrolidine,
alkylpiperidine, alkylhexamethyleneimine, alkylheptamethyleneimine,
alkylmorpholine, and 1,4-dialkylpiperazine.
4. The organometallic complex of claim 3 wherein the organic amine
is selected from 1,2-dimethylpyrrolidine, 1-methylpyrrolidine,
1-butylpyrrolidine, 1,2,2,6,6-pentamethylpiperidine,
1-methylpiperidine, 1-ethylpiperidine, 4-methylmorpholine,
4-ethylmorpholine or 1,4-dimethylpiperazine.
5. The organometallic complex of claim 4 wherein the organic amine
is selected from 1-butylpyrrolidine, 1-methylpyrrolidine or
1-ethylpiperidine.
6. A vapor deposition precursor composition comprising the
organometallic complex of claim 1 and one or more heterocyclic
amine solvents.
7. The composition of claim 5 wherein the one or more heterocyclic
amine solvents are selected from 1-methylpyrrolidine,
1-butylpyrrolidine, 1-methylpiperidine, 1-ethylpiperidine,
4-methylmorpholine, 4-ethylmorpholine or
1,4-dimethylpiperazine.
8. A process for alumina film formation including the step of vapor
depositing an alumina film on a substrate, wherein the source of
aluminum in the alumina film is a vapor deposition precursor
comprising an organometallic compound of the Formula:
R'R"R'"Al:L.sub.n (I) wherein R', R" and R'" are independently
selected from alkyl, perfluoroalkyl or alkoxy each of which has 1
to 5 carbon atoms, or borate (BH.sub.4); L is one or more organic
Lewis bases capable of providing an unshared electron pair to the
aluminum metal center selected from thiophene, thiopyran and
compounds having the structure of Formulae II or III 25wherein R is
an alkyl having 1 to 4 carbon atoms; R.sup.1, R.sup.2, R.sup.21,
R.sup.22, R.sup.23 and R.sup.24 are independently selected from
hydrogen or alkyl having 1 to 2 carbon atoms; X is oxygen or
nitrogen having alkyl group; k and l are integers of 1 to 3; m is
an integer of 2 to 8; and n is an integer of 1 or 2.
9. The process of claim 8 wherein the organometallic compound is
vaporized by thermal energy, plasma or a bias applied on the
substrate.
10. A process for preparing an organometallic compound of the
Formula: R'R"R'"Al:L.sub.n (I) wherein R', R" and R'" are
independently selected from alkyl, perfluoroalkyl or alkoxy each of
which has 1 to 5 carbon atoms, or borate (BH.sub.4); L is one or
more organic Lewis bases capable of providing an unshared electron
pair to the aluminum metal center selected from thiophene,
thiopyran and compounds having the structure of Formulae II or III
26wherein R is an alkyl having 1 to 4 carbon atoms; R.sup.1,
R.sup.2, R.sup.21, R.sup.22, R.sup.23 and R.sup.24 are
independently selected from hydrogen or alkyl having 1 to 2 carbon
atoms; X is oxygen or nitrogen having alkyl group; k and l are
integers of 1 to 3; m is an integer of 2 to 8; and n is an integer
of 1 or 2; including the step of combining in the absence of a
solvent the organic Lewis base and a tri-substituted aluminum
compound of the formula R'R"R'"Al, wherein R', R" and R'" are as
defined above.
Description
BACKGROUND OF THE INVENTION
[0001] The present invention relates to precursor compounds useful
for depositing alumina films used as a dielectric material in
semiconductor devices, processes for preparing the compounds, and
methods for vapor deposition of metallic films on silicon
substrates using the compounds. More specifically, the present
invention relates to compounds for forming alumina films upon
adhesive layers or diffusion-preventive layers formed on substrates
such as silicon substrates, processes for preparing the compounds,
and methods for vapor deposition of metal oxide films.
[0002] According to the trend of large scale integration and
miniaturization of semiconductor devices, the area occupied by
memory cells, such as DRAM ("dynamic random access memory"), is
rapidly decreasing. Therefore, it is important in the area of DRAM
capacitors to guarantee sufficient capacitance within a small
area.
[0003] Capacitance increases in proportion to the dielectric
constant of a dielectric material and the area of dielectric film
used in capacitor and is in inverse proportion to the thickness of
film, and therefore, three possible approaches may be considered in
order to obtain sufficient capacitance with the limited cell area
of DRAM.
[0004] First, the cell structure of the capacitor may be converted
into a 3-dimensional one in order to maximize the effective area of
dielectric film within the restricted small area. Actually in the 4
mega-DRAM, the capacitor having a plane structure has been replaced
with that having a stack or trench structure, each of which is a
3-dimensional one, for the purpose of enlarging the effective area.
Also in the 16 mega- or 64 mega-DRAM, the effective area has been
secured using the more complicated 3-dimensional capacitor such as
a fin cylinder or crown.
[0005] However, this approach has the problem that very complex
capacitor structures need to be formed in a cell having a small
area. Therefore, adoption of such 3-dimensional structures in the
manufacture of more than 256 mega-DRAM, such as 1 giga-DRAM, is
restricted due to their increasing complexity and high cost.
[0006] Second, the thickness of the dielectric film may be
decreased to guarantee the capacitance. However, even though the
3-dimensional capacitor structure is used for maximizing the
effective area, if the existing NO (Si.sub.3N.sub.4/SiO.sub.x)
composite dielectric material is used, the thickness of dielectric
film should be lowered to 40 to 45 .ANG. in order for guaranteeing
the minimum capacitance per cell, i.e. 25 to 30 fF (femptoFarad).
Further, the reduction of thickness may result in the increase of
current leakage due to the tunneling phenomenon or the increase of
soft error by .alpha.-particles, and consequently, the reliability
of device may be threatened seriously.
[0007] Third, another dielectric material having a higher
dielectric constant may be used instead of the currently used one
for capacitors, such as for example, ONO structure such as
SiO.sub.2/Si.sub.3N.sub.4/SiO.- sub.x or NO structure such as
Si.sub.3N.sub.4/SiO.sub.x, having a lower dielectric constant.
Under the situation as explained above, extensive studies have been
carried out for forming dielectric films of a capacitor using
materials having higher dielectric constants than the earlier
developed ones, whereby the capacitance can be stably secured in
the manufacture of the next generation memory of more than 256
mega-DRAM. Use of such films having high dielectric constants may
settle the problems such as difficulties in manufacturing
processes, complexity of capacitor structures, reduction of
reliability of devices, etc. One of the dielectric films currently
studied for that purpose is alumina film.
[0008] Since 1970s, the study of alumina CVD using commercially
available alkyl aluminum and aluminum alkoxide was performed in the
USA and Japan. The typical aluminum compounds used have been
trimethylaluminum having the formula Al(CH.sub.3).sub.3 and
aluminum isopropoxide having the formula
Al(O--iC.sub.3H.sub.7).sub.3.
[0009] The compounds as recommended above, however, show some
problems when they are used as precursors. The alkylaluminum
compound, trimethylaluminum, has been used for various purposes in
different technical areas, and thus, it can be commercially
purchased from the market with a low cost. Also, it has the
advantage of being effectively used as the CVD precursor because it
exists as a liquid having a high vapor pressure at room
temperature. However, since the vapor deposition of film is
achieved at a high temperature of 300 to 400.degree. C., the
undesirable impurity carbon may remain in the alumina film and a
very careful handling may be required due to the explosive
inflammation caused by the trifling contact of alkylaluminum
compound with the ambient air, which commonly occurs when the alkyl
aluminum compound is used.
[0010] The aluminum alkoxide compound, i.e., aluminum isopropoxide,
is cheap and commercially available. Also, it does not inflame upon
contact with moisture. However, it has the disadvantage that since
it exists as a solid at room temperature or its vapor pressure is
low, high temperature heating may be required at the stage of vapor
deposition which results in the decomposition of the compound, or
the deposition process may not be reproducible due to the
condensation of the compound.
[0011] In the case of vapor-deposition of aluminum films using such
compounds, several problems may occur, such as for example, the
introduction of undesirable carbon impurities into the aluminum
film; the difficult to achieve process reproducibility which is
caused by the decomposition of precursor compound in the reactor
due to the high temperature heating; and explosive inflammation
caused by the reaction of the compound with moisture, etc.
SUMMARY OF THE INVENTION
[0012] In order to solve the problems mentioned above, the present
inventor has complemented the earlier invention relating to a
precursor compound for forming aluminum film via chemical vapor
deposition method and process for preparing the same, which was
filed by the present inventor as Korean Patent App. No. 98-38572,
and as a result, completed the present invention.
[0013] The present invention provides a novel aluminum compound and
process for preparing the same, by which can be solved some
problems found in the prior art for precursor compounds for alumina
and aluminum CVD, such as for example, difficult to achieve
reproducibility of film deposition processes, explosive
inflammation of the compounds upon contact with moisture, and the
residual impurities in the film. Further, according to the present
invention, the skilled person may enjoy the large range of
selection of the precursor compounds.
[0014] In one aspect, the present invention provides an
organometallic complex useful for depositing a highly pure alumina
film on a substrate by chemical vapor deposition, having the
Formula I:
R'R"R'"Al:L.sub.n (I)
[0015] wherein R', R" and R'" are independently selected from
alkyl, perfluoroalkyl or alkoxy each of which has 1 to 5 carbon
atoms, or borate (BH.sub.4); L is one or more organic Lewis bases
capable of providing an unshared electron pair to the aluminum
metal center selected from thiophene, thiopyran and organic amines
of the Formulae II or III 1
[0016] wherein R is an alkyl having 1 to 4 carbon atoms; R.sup.1,
R.sup.2, R.sup.21, R.sup.22, R.sup.23 and R.sup.24 are
independently selected from hydrogen (H) or alkyl having 1 to 2
carbon atoms; X is oxygen (O) or nitrogen having alkyl group; k and
l are integers of 1 to 3; m is an integer of 2 to 8; and n is an
integer of 1 or 2.
[0017] In a second aspect, the present invention provides a vapor
deposition precursor composition comprising an organometallic
compound as described above and one or more heterocyclic amine
solvents.
[0018] In a third aspect, the present invention provides a process
for alumina film formation including the step of vapor depositing
an alumina film on a substrate, wherein the source of aluminum in
the alumina film is a vapor deposition precursor including an
organometallic compound of the Formula:
R'R"R'"Al:L.sub.n (I)
[0019] wherein R', R" and R'" are independently selected from
alkyl, perfluoroalkyl or alkoxy each of which has 1 to 5 carbon
atoms, or borate (BH.sub.4); L is one or more organic Lewis bases
capable of providing an unshared electron pair to the aluminum
metal center selected from thiophene, thiopyran and organic amines
of the Formulae II or III 2
[0020] wherein R is an alkyl having 1 to 4 carbon atoms; R.sup.1,
R.sup.2, R.sup.21, R.sup.22, R.sup.23 and R.sup.24 are
independently selected from hydrogen (H) or alkyl having 1 to 2
carbon atoms; X is oxygen (O) or nitrogen having alkyl group; k and
l are integers of 1 to 3; m is an integer of 2 to 8; and n is an
integer of 1 or 2.
[0021] In a fourth aspect, the present invention provides a process
for preparing an organometallic compound of the Formula:
R'R"R'"Al:L.sub.n (I)
[0022] wherein R', R" and R'" are independently selected from
alkyl, perfluoroalkyl or alkoxy each of which has 1 to 5 carbon
atoms, or borate (BH.sub.4); L is one or more organic Lewis bases
capable of providing an unshared electron pair to the aluminum
metal center selected from thiophene, thiopyran and organic amines
of the Formulae II or III 3
[0023] wherein R is an alkyl having 1 to 4 carbon atoms; R.sup.1,
R.sup.2, R.sup.21, R.sup.22, R.sup.23 and R.sup.24 are
independently selected from hydrogen (H) or alkyl having 1 to 2
carbon atoms; X is oxygen (O) or nitrogen having alkyl group; k and
l are integers of 1 to 3; m is an integer of 2 to 8; and n is an
integer of 1 or 2; including the step of combining in the absence
of a solvent the organic Lewis base and a tri-substituted aluminum
compound of the formula R'R"R'"Al, wherein R', R" and R'" are as
defined above.
BRIEF DESCRIPTION OF DRAWINGS
[0024] FIG. 1 is ESCA spectrum showing the composition and
components of alumina film deposited on silicon substrate.
DETAILED DESCRIPTION OF INVENTION
[0025] The present invention relates to novel aluminum compounds
useful as precursor compounds for metallic film deposition, as
represented by the Formula 1, which are designed to retain the
merits of the existing precursors for depositing an alumina film
and as well to address the problems of such precursors.
[0026] Organic Lewis bases capable of providing an unshared
electron pair to the aluminum center are useful in the present
invention. Suitable organic Lewis bases include those of Formulae
II and III. In particular, suitable Lewis bases include, but are
not limited to, alkylaziridine, alkylazetidine, alkylpyrrolidine,
alkylpiperidine, alkylhexamethyleneimine, alkylheptamethyleneimine,
alkylmorpholine, and 1,4-dialkylpiperazine. 4
[0027] In the above Formula II, R is an alkyl having 1 to 4 carbon
atoms; R.sup.1 and R.sup.2 are independently selected from hydrogen
(H) or alkyl having 1 to 2 carbon atoms; and m is an integer of 2
to 8. 5
[0028] In the above Formula III, R is as defined in Formula II;
R.sup.21, R.sup.22, R.sup.23 and R.sup.24 are independently
selected from hydrogen (H) or alkyl having 1 to 2 carbon atoms; X
is selected from oxygen (O) or nitrogen having alkyl group; and k
and l are integers of 1 to 3.
[0029] Among the compounds of Formula II, alkylaziridine (m=2 in
Formula II) of the following Formula IV, alkylpyrrolidine (m=4 in
Formula II) of the following Formula V and alkylpiperidine (m=5 in
Formula II) of the following Formula VI are preferred. Among the
compounds of Formula III, alkylmorpholine of the following Formula
VII and alkylpiperazine of the following Formula VIII are
preferred, and compounds of Formula VIII are more preferred. 6
[0030] In the above Formula IV, R is an alkyl having 1 to 4 carbon
atoms; and R.sup.2 is selected from hydrogen or alkyl having 1 to 2
carbon atoms. Suitable compounds of Formula IV include those
wherein R is methyl or ethyl and R.sup.2 is hydrogen or methyl. In
the compounds of Formula V, R is an alkyl having 1 to 4 carbon
atoms; R.sup.3, R.sup.4, R.sup.5, R.sup.6, R.sup.7, R.sup.8,
R.sup.9 and R.sup.10 are independently selected from hydrogen or
alkyl having 1 to 2 carbon atoms. In the compounds of Formula VI, R
is an alkyl having 1 to 4 carbon atoms; and R.sup.11, R.sup.12,
R.sup.13, R.sup.14, R.sup.15, R.sup.16, R.sup.17, R.sup.18,
R.sup.19 and R.sup.20 are independently selected from hydrogen or
alkyl having 1 to 2 carbon atoms. 7
[0031] In the above formula 7, R is an alkyl having 1 to 4 carbon
atoms; and R.sup.25, R.sup.26, R.sup.27, R.sup.28, R.sup.29,
R.sup.30, R.sup.31 and R.sup.32 are independently selected from
hydrogen or alkyl having 1 to 2 carbon atoms. In compounds having
the structure of formula VIII, R is an alkyl having 1 to 4 carbon
atoms; and R.sup.33, R.sup.34, R.sup.35, R.sup.36, R.sup.37,
R.sup.38, R.sup.39 and R.sup.40 are independently selected from
hydrogen or alkyl having 1 to 2 carbon atoms.
[0032] Alkylpyrrolidines having the structure of Formula IX wherein
R is an alkyl having 1 to 4 carbon atoms; and R.sup.3, R.sup.4,
R.sup.6, R.sup.7, R.sup.9 and R.sup.10 are independently selected
from hydrogen or methyl, are the preferred compounds of Formula II.
Preferred compounds of Formula IX, include the compounds of Formula
X wherein R and R.sup.3 are CH.sub.3, and each of R.sup.4, R.sup.6,
R.sup.7, R.sup.9 and R.sup.10 is hydrogen, that is
1,2-dimethylpyrrolidine, the compounds of Formula XI wherein R is
CH.sub.3, and each of R.sup.3 to R.sup.10 is hydrogen, that is
1-methylpyrrolidine, and the compounds of Formula XII wherein R is
C.sub.4H.sub.9, and each of R.sup.3 to R.sup.10 is hydrogen, that
is 1-butylpyrrolidine. When the Lewis base is an alkylpiperidine of
Formula VI, it is preferred that the alkylpiperidine has the
structure of Formula XIII wherein R is methyl or ethyl, and each of
R.sup.11, R.sup.12, R.sup.14, R.sup.16, R.sup.18, R.sup.19 and
R.sup.20 are hydrogen or methyl. Preferred alkylpiperidines of
Formula XIII, include 1,2,2,6,6-pentamethylpiperidine (Formula XIV
wherein each of R, R.sup.11, R.sup.12, R.sup.19 and R.sup.20 is
methyl, and each of R.sup.14, R.sup.16 and R.sup.18 is hydrogen),
and 1-methylpiperidine and 1-ethylpiperidine (Formulae XV and XVI,
respectively). 8
[0033] The preferred compounds among those of Formula III are the
alkylmorpholines 4-methylmorpholine having the Formula XVII and
4-ethylmorpholine having the Formula XVIII. Among the
alkylpiperazines of Formula VIII, 1,4-dimethylpiperazine having the
Formula XIX is preferably reacted to form a complex which is then
used as a precursor compound for alumina film deposition via
chemical vapor deposition method. 9
[0034] Thus, suitable organic amines of Formulae II and III include
1,2-dimethylpyrrolidine, 1-methylpyrrolidine, 1-butylpyrrolidine,
1,2,2,6,6-pentamethylpiperidine, 1-methylpiperidine,
1-ethylpiperidine, 4methylmorpholine, 4-ethylmorpholine and
1,4-dimethylpiperazine.
[0035] As depicted in the following Reaction Scheme 1, the aluminum
compound of Formula I, which is useful for alumina chemical vapor
deposition, can be prepared by reacting a trialkylaluminum
(Al(R'R"R'")) compound with a Lewis base such as an alkyl
pyrrolidine, alkylpiperidine, alkylmorpholine, alkylpiperazine and
the like, at room temperature. 10
[0036] In the tri-substituted aluminum compounds in the above
Reaction Scheme 1, R', R" and R'" are independently selected from
alkyl, perfluoroalkyl or alkoxy each of which has 1 to 5 carbon
atoms, or borate (BH.sub.4); L is an organic Lewis base, and n is
an integer of 1 or 2. It is preferred that R', R" and R'" are
independently selected from methyl, ethyl, iso-propoxy or
sec-butoxy. Preferably, the compounds of Formula I are prepared
using as the Lewis base alkylpyrrolidines such as
1-butylpyrrolidine or 1-methylpyrrolidine, or alkylpiperidines such
as 1-ethylpiperidine, which belongs to is preferable as the
precursor compound for film deposition.
[0037] Therefore, the present invention will be more specifically
explained centering around 1-butylpyrrolidine trimethylaluminum
having the Formula XX, 1-methylpyrrolidine triethylaluminum having
the Formula XXI, 1-ethylpiperidine trimethylaluminum and
1-ethylpiperidine triethylaluminum having the Formulae XXII and
XXIII, respectively. These compounds can be used as a CVD precursor
for alumina film deposition, which is used in the manufacture of
semiconductor devices. 11
[0038] The aluminum compounds of the Formulae XX to XXIII exhibit
the following effects when they are used as a precursor for alumina
film deposition. First, since the film deposition using known
aluminum compounds is carried out at a high temperature,
undesirable carbon contamination may occur in the deposited film.
In contrast, the compounds of the present invention, a monomer
prepared by combining the existing compound with a Lewis base
ligand, may reduce the degree of contamination in the deposited
film by somewhat decreasing the temperature during the
deposition.
[0039] Second, the alkylaluminum compound conventionally used as a
CVD precursor may cause explosive inflammation when it contacts
with water or air. To the contrary, the compounds of the present
invention have a highly reduced inflammability and may exclude the
hazardous factors for fire and personal accidents resulting from
handling such compounds.
[0040] Third, the compounds of the present invention have a vapor
pressure sufficiently high for chemical vapor deposition and an
excellent thermal stability. The compounds do not decompose upon
storage and exist as liquid phase-precursors. Therefore, during
film deposition by chemical vapor deposition methods using a
bubbler for delivering the precursor, the compounds of the present
invention make it easy to exactly control the delivery rate, which
is directly related to process reproducibility. The present
compounds also make it possible to use other manners of precursor
delivery, such as direct liquid injection or liquid delivery
systems in addition to the bubbler method. This is a further
advantage of the present compounds since they provide a wide
opportunity for developing various processes.
[0041] Additionally, the present inventor has developed precursor
solutions which can be used more conveniently for depositing an
alumina film in a liquid delivery system, such as for example,
direct liquid injection or other liquid delivery systems. As the
solvent for making the precursor solutions, heterocyclic amines may
be used, preferably 1-methylpyrrolidine, 1-butylpyrrolidine,
1-methylpiperidine, 1-ethylpiperidine, 4-methylmorpholine,
4-ethylmorpholine, 1,4-dimethylpiperazine, and the like. The
compounds of Formula I dissolved in said solvents can be used as
highly effective precursors for depositing alumina films.
[0042] In general, in the chemical vapor deposition methods, an
alumina film is deposited on a substrate, such as a silicon
substrate, heated to a deposition temperature of from 150 to
550.degree. C. using an organometallic compound of Formula I.
During such deposition process, vaporized water, in the form of
steam, is provided. The water steam, particularly from ultrapure
water, oxidizes the precursor aluminum to aluminum oxide through
oxidation-reduction reaction in a reactor, and simultaneously forms
a film on the substrate. In such chemical vapor deposition
processes, thermal energy or plasma is used as the excitation
source of the processing gas or a bias is applied on the
substrate.
[0043] The precursor solution of the present invention is more
advantageous than existing precursor solutions in view of the broad
selection range for developing new deposition process of alumina
film.
[0044] The novel precursor solutions may be prepared by dissolving
the compounds of Formula I in a purified solvent free from
moisture, wherein this solvent may be a Lewis base such as
heterocyclic amine, and the like. Since the compound should be
prevented from deterioration caused by the contact with air, the
whole reaction procedure must be proceeded under inert gas such as
nitrogen or argon.
[0045] The compound of the present invention and process for
preparing the precursor solution will be more specifically
explained in the following examples.
EXAMPLE 1
Synthesis of 1-Methylpyrrolidine Trimethylaluminum
[0046] Colorless 1-methylpyrrolidine, 212 g (2.5 mol), was added
dropwise to 144 g (2 mol) of trimethylaluminum at room temperature
under nitrogen gas flow with stirring. After the addition of
1-methylpyrrolidine was completed, the resulting mixture was
stirred for 6 hours at room temperature to complete the reaction.
1-Methylpyrrolidine trimethylaluminum was obtained after completion
of the reaction and was dried under vacuum at about 45.degree. C.
to give 300 g of a colorless liquid. The dried colorless liquid was
distilled under vacuum (10.sup.-2 torr) at 60.degree. C., during
which a colorless distillate was condensed inside a vessel cooled
with dry ice. This first colorless distillate was purified
according to the same procedure at 60.degree. C. to give 267 g of
the colorless and highly purified 1-methylpyrrolidine
trimethylaluminum.
[0047] The chemical reaction shown in Reaction Scheme 2 is the
preparation of 1-methylpyrrolidine trimethylaluminum, and the
product was analyzed by proton (".sup.1H") nuclear magnetic
resonance. The .sup.1H nuclear magnetic resonance ("NMR") data and
physicochemical properties of the highly purified
1-methylpyrrolidine trimethylaluminum are shown in the following
Table 1. 12
EXAMPLE 2
Synthesis of 1-Butylpyrrolidine Trimethylaluminum
[0048] The procedure of Example 1 was repeated, except that 292 g
(2.3 mol) of 1-butylpyrrolidine was added dropwise to 144 g (2 mol)
of trimethylaluminum under nitrogen gas flow with stirring. The
resulting mixture was stirred for 6 hours at room temperature and
then dried under vacuum at 50.degree. C. to give a colorless liquid
compound. Then, the dried colorless liquid compound was distilled
under vacuum at 80.degree. C. to give 330 g of the colorless liquid
1-butylpyrrolidine trimethylaluminum having high purity.
[0049] The chemical reaction shown in Reaction Scheme 3 is the
preparation of 1-butylpyrrolidine trimethylaluminum, and the
product was analyzed by .sup.1H NMR. The .sup.1H NMR data and
physicochemical properties of the highly purified
1-butylpyrrolidine trimethylaluminum are shown in the following
Table 1. 13
EXAMPLE 3
Synthesis of 1-Methylpiperidine Trimethylaluminum
[0050] The procedure of Example 1 was repeated, except that 218 g
(2.2 mol) of 1-methylpiperidine was added dropwise to 144 g (2 mol)
of trimethylaluminum under nitrogen gas flow with stirring. The
resulting mixture was stirred for 6 hours at room temperature,
dried under vacuum at 60.degree. C., and then distilled under
vacuum at 95.degree. C. to give 298 g of the colorless liquid
1-methylpiperidine trimethylaluminum having high purity.
[0051] The chemical reaction shown in Reaction Scheme 4 is the
preparation of 1-methylpiperidine trimethylaluminum, and the
product was analyzed by .sup.1H NMR. The .sup.1H NMR data and
physicochemical properties of the highly purified
1-methylpiperidine trimethylaluminum are shown in the following
Table 1. 14
EXAMPLE 4
Synthesis of 1-Ethylpiperidine Trimethylaluminum
[0052] The procedure of Example 1 was repeated, except that 249 g
(2.2 mol) of 1-ethylpiperidine was added dropwise to 144 g (2 mol)
of trimethylaluminum under nitrogen gas flow with stirring. The
resulting mixture was stirred for 6 hours at room temperature,
dried under vacuum at 70.degree. C., and then distilled under
vacuum at 120.degree. C. to give 315 g of the colorless liquid
1-ethylpiperidine trimethylaluminum having high purity.
[0053] The chemical reaction shown in Reaction Scheme 5 is the
preparation of 1-ethylpiperidine trimethylaluminum, and the product
was analyzed by .sup.1H NMR. The .sup.1H NMR data and
physicochemical properties of the highly purified 1-ethylpiperidine
trimethylaluminum are shown in the following Table 1. 15
EXAMPLE 5
Synthesis of 1,4-Dimethylpiperazine Trimethylaluminum
[0054] The procedure according to Example 1 was repeated, except
that 251 g (2.2 mol) of 1,4-dimethylpiperazine was added dropwise
to 144 g (2.2 mol) of trimethylaluminum under nitrogen gas flow
with stirring. The resulting mixture was stirred for 6 hours at
room temperature, the mixture was separated, and then dried under
vacuum to give 301 g of the solid 1,4-dimethylpiperazine
trimethylaluminum.
[0055] The chemical reaction shown in Reaction Scheme 6 is the
preparation of 1,4-dimethylpiperazine trimethylaluminum, and the
product was analyzed by .sup.1H NMR. The .sup.1H NMR data and
physicochemical properties of the highly purified
1,4-dimethylpiperazine trimethylaluminum are shown in the following
Table 1. 16
EXAMPLE 6
Synthesis of 4-Ethylmorpholine Trimethylaluminum
[0056] The procedure according to Example 1,253 g (2.2 mol) of
4-ethylmorpholine was added dropwise to 144 g (2 mol) of
trimethylaluminum under nitrogen gas flow with stirring. The
resulting mixture was stirred for 6 hours at room temperature for
reaction completion, and then the mixture was dried under vacuum at
65.degree. C. and distilled under vacuum at 90.degree. C. to give
329 g of the colorless 4-ethylmorpholine trimethylaluminum having
high purity.
[0057] The chemical reaction shown in Reaction Scheme 7 is the
preparation of 4-ethylmorpholine trimethylaluminum, and the product
was analyzed by .sup.1H NMR. The .sup.1H NMR data and
physicochemical properties of the highly purified 4-ethylmorpholine
trimethylaluminum are shown in the following Table 1. 17
EXAMPLE 7
Synthesis of 1-Methylpyrrolidine Triethylaluminum
[0058] Colorless 1-methylpyrrolidine, 195 g (2.3 mol), was added
dropwise to 228 g (2 mol) of triethylaluminum at room temperature
under nitrogen gas flow with stirring. After the addition of
1-methylpyrrolidine was completed, the resulting mixture was
stirred for about 6 hours at room temperature to complete the
reaction. 1-Methylpyrrolidine triethylaluminum was obtained after
completion of the reaction, and was dried under vacuum at about
45.degree. C. to give a colorless liquid. The dried colorless
liquid compound was distilled under vacuum (10.sup.-2 torr) at
70.degree. C., during which a colorless distillate was condensed
inside a vessel cooled with dry ice. This first colorless
distillate was purified according to the same procedure at
70.degree. C. to give 354 g of the colorless liquid
1-methylpyrrolidine triethylaluminum having high purity.
[0059] The chemical reaction shown in Reaction Scheme 8 is the
preparation of 1-methylpyrrolidine triethylaluminum, and the
product was analyzed by .sup.1H NMR. The .sup.1H NMR data and
physicochemical properties of the highly purified
1-methylpyrrolidine triethylaluminum are shown in the following
Table 1. 18
EXAMPLE 8
Synthesis of 1-Butylpyrrolidine Triethylaluminum
[0060] The procedure of Example 7 was repeated except that 280 g
(2.2 mol) of 1-butylpyrrolidine was added dropwise to 228 g (2 mol)
of triethylaluminum under nitrogen gas flow with stirring. The
resulting mixture was stirred for 6 hours at room temperature,
dried under vacuum at 60.degree. C. and then distilled under vacuum
at 85.degree. C. to give 420 g of the colorless liquid
1-butylpyrrolidine triethylaluminum having high purity.
[0061] The chemical reaction shown in Reaction Scheme 9 is the
preparation of 1-butylpyrrolidine triethylaluminum, and the product
was analyzed by .sup.1H NMR. The .sup.1H NMR data and
physicochemical properties of the highly purified
1-butylpyrrolidine triethylaluminum are shown in the following
Table 1. 19
EXAMPLE 9
Synthesis of 1-Methylpiperidine Triethylaluminum
[0062] The procedure of Example 7 was repeated, except that 218 g
(2.2 mol) of 1-methylpiperidine was added dropwise to 228 g (2 mol)
of triethylaluminum under nitrogen gas flow with stirring. The
resulting mixture was stirred for 6 hours at room temperature,
dried under vacuum at 60.degree. C. and then distilled under vacuum
at 75.degree. C. to give 345 g of the colorless liquid
1-methylpiperidine triethylaluminum having high purity.
[0063] The chemical reaction shown in Reaction Scheme 10 is the
preparation of 1-methylpiperidine triethylaluminum, and the product
was analyzed by .sup.1H NMR. The .sup.1H NMR data and
physicochemical properties of the highly purified
1-methylpiperidine triethylaluminum are shown in the following
Table 1. 20
EXAMPLE 10
Synthesis of 1-Ethylpiperidine Triethylaluminum
[0064] The procedure of Example 7 was repeated, except that 249 g
(2.2 mol) of 1-ethylpiperidine was added dropwise to 228 g (2 mol)
of triethylaluminum under nitrogen gas flow with stirring. The
resulting mixture was stirred for 6 hours at room temperature,
dried under vacuum at 65.degree. C. and then distilled under vacuum
at 80.degree. C. to give 400 g of the colorless liquid
1-ethylpiperidine triethylaluminum having high purity.
[0065] The chemical reaction shown in Reaction Scheme 11 is the
preparation of 1-ethylpiperidine triethylaluminum, and the product
was analyzed by .sup.1H NMR. The .sup.1H NMR data and
physicochemical properties of the highly purified 1-ethylpiperidine
triethylaluminum are shown in the following Table 1. 21
EXAMPLE 11
Synthesis of 1,4-Dimethylpiperazine Triethylaluminum
[0066] The procedure of Example 7 was repeated, except that 251 g
(2.2 mol) of 1,4-dimethylpiperazine was added dropwise to 228 g (2
mol) of triethylaluminum under nitrogen gas flow with stirring. The
resulting mixture was stirred for 6 hours at room temperature,
dried under vacuum at 65.degree. C. and then distilled under vacuum
at 115.degree. C. to give 365 g of the colorless liquid
1,4-dimethylpiperazine triethylaluminum having high purity.
[0067] The chemical reaction shown in Reaction Scheme 12 is the
preparation of 1,4-dimethylpiperazine triethylaluminum, and the
product was analyzed by .sup.1H NMR. The .sup.1H NMR data and
physicochemical properties of the highly purified
1,4-dimethylpiperazine triethylaluminum are shown in the following
Table 1. 22
EXAMPLE 12
Synthesis of 4-Ethylmorpholine Triethylaluminum
[0068] The procedure of Example 7 was repeated, except that 253 g
(2.2 mol) of 4-ethylmorpholine was added dropwise to 228 g (2 mol)
of triethylaluminum under nitrogen gas flow with stirring. The
resulting mixture was stirred for 6 hours at room temperature,
dried under vacuum at 65.degree. C. and then distilled under vacuum
at 115.degree. C. to give 412 g of the colorless liquid
4-ethylmorpholine triethylaluminum having high purity.
[0069] The chemical reaction shown in Reaction Scheme 13 is the
preparation of 4-ethylmorpholine triethylaluminum, and the product
was analyzed by .sup.1H NMR. The .sup.1H NMR data and
physicochemical properties of the highly purified 4-ethylmorpholine
triethylaluminum are shown in the following Table 1. 23
1TABLE 1 Ex- Phase at 'H NMR in ample Compound 20.degree. C. Color
ppm (C.sub.6D.sub.6) 1 1-Methylpyrrolidine Solid Colorless -0.50(s,
9H), trimethylaluminum Liquid 1.28(t, 4H), at 1.91(s, 3H),
30.degree. C. 2.30(s, br, 4H) 2 1-Butylpyrrolidine Liquid Colorless
-0.50(s, 9H), trimethylaluminum 0.69(t, 3H), 0.89(m, 2H), 1.28(m,
6H), 2.07(br, 4H), 2.30(m, 2H), 2.91(br, 2H) 3 1-Methylpiperidine
Liquid Colorless -0.45(s, 9H), trimethylaluminum 0.80(m, 4H),
1.08(m, 2H), 2.41(m, 4H), 2.69(t, 3H) 4 1-Ethylpiperidine Liquid
Colorless -0.43(s, 9H), trimethylaluminum 0.84(m, 6H), 1.01(t, 3H),
2.38(m, 4H), 2.68(m, 2H) 5 1,4-Dimethylpiperazine Solid Colorless
-0.50(s, 9H), trimethylaluminum 1.71(s, 6H), 2.4(br, 2H) 6
4-Ethylmorpholine Solid Colorless -0.5(s, 9H), trimethylaluminum
Liquid 0.67(t, 3H), at 1.96(q, 2H), 40.degree. C. 2.08(m, 4H),
3.45(m, 4H) 7 1-Methylpyrrolidine Liquid Colorless 0.08(q, 6H),
triethylaluminum 1.17(br, 4H), 1.38(t, 9H), 1.81(s, 3H), 1.94(m,
2H), 2.72(m, 2H) 8 1-Butylpyrrolidine Liquid Colorless 0.11(q, 6H),
triethylaluminum 0.69(t, 3H), 0.88(m, 2H), 1.08(m, 2H), 1.30(m,
4H), 1.52(t, 9H), 2.07(m, 4H), 2.31(m, 2H), 2.87(m, 2H) 9
1-Methylpiperidine Liquid Colorless 0.14(q, 6H), triethylaluminum
0.83(t, 4H), 1.43(t, 9H), 1.75(s, 3H), 2.30(m, 4H), 2.71(m, 2H) 10
1-Ethylpiperidine Liquid Colorless 0.15(q, 6H), triethylaluminum
0.81(t, 6H), 1.0(m, 3H), 1.48(t, 9H), 2.3(m, 4H), 2.65(m, 2H) 11
1,4-Dimethylpiperazine Liquid Colorless 0.05(m, 6H),
triethylaluminum 1.40(t, 9H), 1.85(s, 6H), 2.60(m, 8H) 12
4-Ethylmorpholine Liquid Colorless 0.11(q, 6H), triethylaluminum
0.69(t, 3H), 1.35(t, 9H), 1.96(m, 6H), 3.42(br, 4H)
[0070] In order to confirm the solubility of the compounds obtained
in Examples 1 to 12, the solutions of the following Examples 13 and
14 were prepared.
EXAMPLE 13
1-Ethylpiperidine Trimethylaluminum in 1-Ethylpiperidine
[0071] A colorless solution was obtained by adding 10 g of purified
1-ethylpiperidine to 90 g of the liquid compound 1-ethylpiperidine
trimethylaluminum prepared according to Example 4.
EXAMPLE 14
1-Ethylpiperidine Triethylaluminum in 1-Ethylpiperidine
[0072] A colorless solution was obtained by adding 10 g of purified
1-ethylpiperidine to 90 g of the liquid compound 1-ethylpiperidine
triethylaluminum prepared according to Example 10.
EXAMPLE 15
[0073] Another aspect of the present invention resides in the
formation of aluminum oxide film using the compounds exemplified
above while ultrapure water steam is provided. The ultrapure water
steam oxidized the precursor aluminum to aluminum oxide through
oxidation-reduction reaction in a reactor, and simultaneously makes
a film on the substrate. The experiments are carried out as below,
and the results are represented in the following Tables 2 to 4.
[0074] The following experiments for vapor deposition of alumina
film were carried out using solutions containing 1-butylpyrrolidine
trimethylaluminum of Example 2,1-ethylpiperidine triethylaluminum
of Example 10, and 1-ethylpiperidine triethylaluminum of Example 14
which were each dissolved in 1-ethylpiperidine.
[0075] Experiment A
[0076] 1-Butylpyrrolidine trimethylaluminum prepared according to
Example 2 was introduced into a stainless steel bubbler, and was
then melted by heating at 65.degree. C. The precursor compound was
bubbled using argon or nitrogen gas having a flow rate of 100 sccm
(standard cubic centimeters per minute or cm.sup.3/minute) as a
delivery gas.
[0077] The precursor compound and ultrapure distilled water were
contained in separate bubblers and were bubbled and vaporized. The
vaporized precursor and water were introduced into a reactor in
which a substrate to be film-deposited was located, while the
stainless steel delivery conduit for the precursor was heated to
80.degree. C. and that for water steam was heated to 100.degree.
C.
[0078] The reactor wall was heated to 80.degree. C. to prevent the
introduced precursor compound from condensing thereon. The high
functional alumina film was vapor deposited on a silicon substrate
at 350.degree. C. on which SiO.sub.2 of 2000 .ANG. was already
deposited. Components of the deposited film were analyzed by ESCA
(Electron Spectroscopy for Chemical Analysis) to confirm that
alumina film was actually deposited (see, FIG. 1). Conditions for
vapor deposition and analysis data are represented in the following
Table 2.
2TABLE 2 Conditions for Precursor vapor deposition Film
1-Butylpyrrolidine Delivery gas Nitrogen Deposition 100.about.500
trimethylaluminum or Argon rate .ANG./min Reaction gas Water
Dielectric About 9.5 steam constant (.epsilon.) Bubbler 65.degree.
C. Adhesive Good for temperature strength SiO.sub.2 Reactor/
80.degree. C. Degree of Good Delivery Reflection conduit Substrate
350.degree. C. temperature Flow rate 100 sccm Reactor 100 Pressure
mtorr.about.6 torr
[0079] Experiment B
[0080] Alumina film deposition was carried out using
1-ethylpiperidine triethylaluminum compound prepared in Example 10.
The conditions for vapor deposition and reactors were identical
with those of Experiment A. The alumina film was deposited on a
silicon substrate heated to 400.degree. C. Composition and
components of the deposited film were analyzed by ESCA, and the
results are represented in the following Table 3.
3TABLE 3 Conditions for Precursor vapor deposition Film
1-Ethylpiperidine Delivery gas Nitrogen Deposition 150.about.500
triethylaluminum or Argon rate .ANG./min Reaction gas Water
Dielectric About 9.5 steam constant (.epsilon.) Bubbler 65.degree.
C. Adhesive Good for temperature strength SiO.sub.2 Reactor/
80.degree. C. Degree of Good Delivery Reflection conduit Substrate
400.degree. C. temperature Flow rate 100 sccm Reactor 100 Pressure
mtorr.about.6 torr
[0081] Experiment C
[0082] Alumina film deposition was carried out using the precursor
solution prepared in Example 14. Here, the same silicon substrate
as Experiment A was used as the substrate; a tube having an inner
diameter of 5 cm and a length of 30 cm, one side of which was
closed and the other side was connected with a vacuum pump
(10.sup.-2 torr), was used; the precursor solution and ultrapure
distilled water were introduced into each of 5 ml volume glass
vessels, which were then located at the closed end of the reactor;
several thin silicone plates were introduced into the center of
glass tube; the precursor solution was heated to 85.degree. C. and
the substrate was heated to 300.degree. C. using separate heat
waves, during which the alumina film was deposited under
controlling the exhaust pressure to 10.sup.-2 torr by vacuum pump.
Deposition of alumina film was confirmed by ESCA (see, Table 4). As
a result, it was identified that the solution according to the
present invention can be suitably used for delivery system of
liquid precursor such as direct liquid injection or liquid delivery
system.
4TABLE 4 Conditions for Precursor vapor deposition Film Solution of
Reaction gas Water Dielectric About 9.5 1-ethylpiperidine steam
constant (.epsilon.) triethylaluminum Vapor 85.degree. C. Adhesive
Good for dissolved in 1- temperature strength SiO.sub.2
ethylpiperidine Substrate 300.degree. C. Rate of 200.about.600
temperature vapor .ANG./min deposition Reactor 1 mtorr.about.
Pressure 10.sup.-1 torr
[0083] As can be seen from Experiments A to C, the present
invention provides some outstanding advantages, for example, the
compound of the present invention may vaporize at 85.degree. C. or
less; the substrate may be film-deposited at a broad temperature
range from 250 to 450.degree. C.; deposition rate, dielectric
constant, adhesive strength, and degree of reflection of the
alumina film on silicon substrate are comparatively excellent to
the known compounds; and direct liquid injection or liquid delivery
system can be used for the deposition.
[0084] Further, although the alumina film was deposited through the
reaction of precursor compound with the vaporized water steam in
the above Experiments A to C, the precursor compound alone, without
the water steam, can also be used for depositing an alumina
film.
* * * * *