U.S. patent application number 11/000567 was filed with the patent office on 2005-12-22 for composition for low dielectric material, low dielectric material and method for production thereof.
Invention is credited to Kamiyama, Takuya, Kumada, Teruhiko, Nobutoki, Hideharu, Yamamoto, Tetsuya.
Application Number | 20050282015 11/000567 |
Document ID | / |
Family ID | 35480945 |
Filed Date | 2005-12-22 |
United States Patent
Application |
20050282015 |
Kind Code |
A1 |
Kumada, Teruhiko ; et
al. |
December 22, 2005 |
Composition for low dielectric material, low dielectric material
and method for production thereof
Abstract
A low dielectric material is produced by using a composition
including a borazine ring-containing compound and a compound
represented by the following formula as a solvent, and/or by
annealing a composition comprising a borazine ring-containing
compound under atmosphere of oxygen concentration not higher than
0.1 vol % at 200 to 600.degree. C. In the following formula,
R.sup.a and R.sup.c independently represent alkyl group or acyl
group; R.sup.b represents hydrogen atom or alkyl group; and n
represents an integer of 1 to 5. 1
Inventors: |
Kumada, Teruhiko; (Sandashi,
JP) ; Nobutoki, Hideharu; (Osaka, JP) ;
Yamamoto, Tetsuya; (Nishinomiya-shi, JP) ; Kamiyama,
Takuya; (Osaka, JP) |
Correspondence
Address: |
Diane Dunn McKay, Esq.
Mathews, Collins, Shepherd & McKay, P.A.
Suite 306
100 Thanet Circle
Princeton
NJ
08540
US
|
Family ID: |
35480945 |
Appl. No.: |
11/000567 |
Filed: |
December 1, 2004 |
Current U.S.
Class: |
428/411.1 ;
106/287.3; 257/E21.259; 257/E21.292; 427/240 |
Current CPC
Class: |
H01L 21/02255 20130101;
H01L 21/318 20130101; H01L 21/02282 20130101; H01L 21/02118
20130101; H01L 21/02112 20130101; Y10T 428/31504 20150401; H01L
21/312 20130101 |
Class at
Publication: |
428/411.1 ;
106/287.3; 427/240 |
International
Class: |
B05D 003/12; C09K
003/00; B32B 009/00 |
Foreign Application Data
Date |
Code |
Application Number |
Dec 1, 2003 |
JP |
2003-401199 |
Dec 1, 2003 |
JP |
2003-401200 |
Claims
What is claimed is:
1. A composition for low dielectric material, comprising: a
borazine ring-containing compound; and a solvent represented by the
following formula: 9wherein R.sup.a and R.sup.c independently
represents alkyl group or acyl group; R.sup.b represents hydrogen
atom or alkyl group; and n represents an integer of 1 to 5.
2. A composition for low dielectric material according to claim 1,
wherein the borazine ring-containing compound is a compound
represented by the following formula (1) or a polymer thereof:
10wherein R.sup.1, R.sup.3 and R.sup.5 independently represents
hydrogen atom, substituted or unsubstituted alkyl group, or a group
represented by the following formula (2): 11wherein R.sup.7 is
alkyl group; R.sup.2, R.sup.4 and R.sup.6 independently represents
hydrogen atom, or alkyl group; and at least one of R.sup.1 to
R.sup.6 is hydrogen atom.
3. A low dielectric material obtainable by coating the composition
of claim 1 on a substrate.
4. An interlayer dielectric film for semiconductor device
obtainable by coating the composition of claim 1 on a
substrate.
5. A semiconductor device having the interlayer dielectric film of
claim 4.
6. A method for production of low dielectric material, comprising a
process of forming a coated membrane on a substrate by spin-coating
a composition comprising a borazine ring-containing compound and a
solvent represented by the following formula: 12wherein R.sup.a and
R.sup.c independently represents alkyl group or acyl group; R.sup.b
represents hydrogen atom or alkyl group; and n represents an
integer of 1 to 5.
7. A low dielectric material obtainable by annealing a composition
comprising a borazine ring-containing compound under atmosphere of
oxygen concentration not higher than 0.1 vol % at 200 to
600.degree. C.
8. A low dielectric material according to claim 7, wherein the
borazine ring-containing compound is a compound represented by the
following formula (1) or a polymer thereof: 13wherein R.sup.1,
R.sup.3 and R.sup.5 independently represents hydrogen atom,
substituted or unsubstituted alkyl group, or a group represented by
the following formula (2): 14wherein R.sup.7 is alkyl group;
R.sup.2, R.sup.4 and R.sup.6 independently represents hydrogen
atom, or alkyl group; and at least one of R.sup.1 to R.sup.6 is
hydrogen atom.
9. An interlayer dielectric film for semiconductor device,
comprising the low dielectric material of claim 8.
10. A semiconductor device having the interlayer dielectric film of
claim 9.
11. A method for production of a low dielectric material,
comprising a process of annealing a composition comprising a
borazine ring-containing compound under atmosphere of oxygen
concentration not higher than 0.1 vol % at 200 to 600.degree. C.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention:
[0002] The present invention relates to a composition for low
dielectric material, a low dielectric material and a method for
production thereof, in particular, relates to a composition for low
dielectric material containing a borazine ring-containing compound
and a low dielectric material prepared by using a borazine
ring-containing compound. A composition for low dielectric material
and a low dielectric material of the present invention is used to
produce an interlayer dielectric film for semiconductor device.
[0003] 2. Description of Related Art:
[0004] With higher functionalization of information devices, design
rule of LSI has been required to be finer year by year. In
production of LSI with finer design rule, materials composing LSI
should also have higher performance and fulfill function even on
fine LSI.
[0005] For example, as for materials used for an interlayer
dielectric film in LSI, high dielectric constant causes signal
delay. In fine LSI, effects of the signal delay is particularly
significant. Therefore, development of a new low dielectric
material which can be used for an interlayer dielectric film has
been needed. Also to be used as an interlayer dielectric film, it
is necessary not only to have low dielectric constant but also
superior characteristics such as humidity resistance, heat
resistance, mechanical strength, etc.
[0006] As a material to respond to these requirements, a compound
having borazine ring backbone has been proposed (for example, see
U.S. patent publication No. 2002-58142). A compound having borazine
ring backbone has small molecular polarizability and thus a coated
membrane formed provides low dielectric constant. Moreover, the
coated membrane formed is superior in heat resistance. The coated
membrane can be formed by spin-coating of a compound having
borazine ring backbone. As a solvent used in the spin-coating,
alcohols such as methanol, ethanol, propanol, butanol, etc.,
acetone, benzene, toluene and xylene are cited.
[0007] Further, a polymer composition containing a compound having
borazine ring backbone and an organosilicon compound has been
proposed (for example, see JP-2002-317049A). A coated membrane
formed by using a polymer composition containing a compound having
borazine ring backbone and an organosilicon compound has superior
humidity resistance. The coated membrane can be formed by
spin-coating of a polymer composition. As a solvent used here,
ethylene glycol, ethylene glycol monomethyl ether, toluene,
benzene, xylene, hexane, heptane, octane, tetrahydrofuran and
tetraglyme are cited.
BRIEF SUMMARY OF THE INVENTION
[0008] As described above, a compound having borazine ring backbone
is very useful as a raw material for a low dielectric material used
as an interlayer dielectric film, and the like. However, further
improvement is required to enhance value as a low dielectric
material.
[0009] It is an object of the present invention to further enhance
characteristics of a low dielectric material formed by using a
compound having borazine ring backbone.
[0010] Further, there are various means to form a coated membrane
(a low dielectric material) composed of a compound having borazine
ring backbone, however, in view of productivity, it is preferable
to use a coating method represented by a spin-coating. However,
when a composition for low dielectric material containing a
compound having borazine ring backbone is coated, such problems
occur as white turbidity of the coated membrane and reduced
membrane formability. For example, when an interlayer dielectric
film for semiconductor device is inhomogeneous, it leads to defect
or reduced performance of semiconductor device. That is, reduced
production yield may be induced by a coated membrane thus produced,
which in turn causes lowering of reliability of semiconductor
device produced or competitiveness of a company.
[0011] Therefore, it is also an object of the present invention to
provide means to form superior coated membrane using a coating
method.
[0012] In an aspect of the invention, as a solvent included in a
composition for low dielectric material containing a borazine
ring-containing compound, a solvent represented by the following
formula is preferably used: 2
[0013] wherein R.sup.a and R.sup.c may independently represents
alkyl group or acyl group; R.sup.b represents hydrogen atom or
alkyl group; and n represents an integer of 1 to 5. And a low
dielectric material is produced by forming a coated membrane on a
substrate by spin-coating the composition containing the solvent
represented by the above-described formula.
[0014] By containing a solvent represented by the above-described
formula, a homogeneous coated membrane can be formed. For example,
when an interlayer dielectric film for semiconductor device is
formed by using a composition of the present invention, reliability
of semiconductor device produced is improved. Also by using a
composition for low dielectric material of the present invention,
improvement of production yield of semiconductor device is expected
and thus can greatly contribute in industrial mass production
steps.
[0015] In another aspect of the invention, a low dielectric
material is produced by annealing a composition containing a
borazine ring-containing compound, preferably under atmosphere of
oxygen concentration not higher than 0.1 vol % at 200 to
600.degree. C.
[0016] By using a composition containing a compound having borazine
ring, a low dielectric material having low dielectric constant is
obtained. Also by controlling oxygen concentration in annealing,
dielectric constant of a low dielectric material formed is further
lowered. Furthermore, by controlling temperature in annealing,
humidity resistance and membrane formability of a low dielectric
material formed are improved.
[0017] A low dielectric material having such characteristics is
particularly useful as an interlayer dielectric film in
semiconductor device and a low dielectric material of the present
invention greatly contributes to realization of high speed
ULSI.
DETAILED DESCRIPTION OF THE INVENTION
[0018] As described above, a compound having borazine ring backbone
is superior as a raw material of low dielectric material. The
present inventors have studied comprehensively to further improve
characteristics of a low dielectric material formed by using a
compound having borazine ring backbone and have found, as the
results, that annealing conditions in producing a low dielectric
material have strong effects on characteristics of a low dielectric
material formed and thus completed the present invention. We have
also found out a preferable borazine ring-containing compound as a
low dielectric material.
[0019] The present inventors have also studied comprehensively to
further improve uniformity of a coated membrane composed of a
borazine ring-containing compound, formed by using a coating method
and have found, as the results, that by using a specified solvent
as a solvent of a borazine ring-containing compound to be coated by
using a coating method, uniformity of a coated membrane produced
can be improved and thus completed the present invention. We have
also found out a borazine ring-containing compound suitably used
here.
[0020] A "borazine ring-containing compound" in the present
invention means a compound having a borazine ring represented by
the following formula in the structure. 3
[0021] As is understood by the above formula, nitrogen (N) and
boron (B) in a borazine ring each has one bond which does not form
a borazine ring. An element and a functional group bonding to
nitrogen and boron which form a borazine ring are not especially
limited. An element and a functional group bonding to nitrogen and
boron which form a borazine ring include hydrogen atom, halogen
atom, alkyl group, amino group and borazinyl group.
[0022] A borazine ring-containing compound may be a compound having
one borazine ring or a compound having two or more borazine rings.
A borazine ring-containing compound may by a polymer. In the
present application, irrespective of morphlogy or molecular weight
of a compound, a compound as long as having a borazine ring is
included in a "borazine ring-containing compound" concept. When a
production step of a low dielectric material includes a coating
step by spin-coating of a composition containing a compound having
a borazine ring, it is preferable that a borazine ring-containing
compound is a polymer. Because viscosity of a solution containing a
polymer is high, it is suitable to coating using spin-coating.
[0023] A polymer as a borazine ring-containing compound can be
formed by using a compound having borazine ring backbone as a
monomer. A polymerization method or polymerization form is not
especially limited. A polymerization method is selected by a
functional group bonding to a borazine ring. For example, when
amino group is bonded, a polymer can be synthesized by a
polycondensation as shown in Examples. When vinyl group or a
functional group containing vinyl group is bonded to a borazine
ring, a polymer can be formed, for examples, by a radical
polymerization using a polymerization initiator. A polymer may be a
homopolymer or a copolymer containing two or more monomer units.
Morphology of a copolymer may be any of a random copolymer, a bock
copolymer, a graft copolymer, etc. By using a monomer having three
or more functional groups formable bonds with other monomers, a
polymer with monomers bonded in network structure can also be
obtained.
[0024] A borazine ring-containing compound of the present invention
is preferably a compound represented by the following formula (1)
or a polymer thereof. 4
[0025] R.sup.1, R.sup.3 and R.sup.5 bonding to boron (B) composing
a borazine ring are hydrogen atom, alkyl group which may be
substituted or a functional group represented by the following
formula (2): 5
[0026] R.sup.1, R.sup.3 and R.sup.5 may be the same or different
and R.sup.7 in the formula (2) is alkyl group.
[0027] Alkyl group included as R.sup.1, R.sup.3, R.sup.5 and
R.sup.7may be a straight, branched or cyclic alkyl group. As an
example of alkyl group, methyl group, ethyl group, propyl group,
butyl group, pentyl group, hexyl group, heptyl group, octyl group,
nonyl group, decyl group, 1-methylethyl group, sec-butyl group,
tert-butyl group, neopentyl group and cyclohexyl group are
included. However, alkyl group included as R.sup.1, R.sup.3,
R.sup.5 and R.sup.7 is not necessarily limited to these.
[0028] Alkyl group included as R.sup.1, R.sup.3, R.sup.5 and
R.sup.7 may be substituted with other functional groups at their
hydrogen atom as long as they do not impair the effects of the
present invention. As a functional group, amino group, isocyanate
group, vinyl group and ethynyl group are included.
[0029] When a functional group represented by the formula (2) is
included, a borazine ring-containing compound represented by the
formula (1) is suitable to be subjected to polycondensation. In
this case, it is preferable that two or more functional groups
represented by the formula (2) are included in a borazine
ring-containing compound used as a monomer. To obtain a polymer
with network structure, a borazine ring-containing compound is
suitably used, wherein all of R.sup.1, R.sup.3 and R.sup.5are
functional groups represented by the formula (2). However, even
when a network-like polymer is to be synthesized, R.sup.1, R.sup.3
and R.sup.5 are not necessarily functional groups represented by
the formula (2) for all borazine ring-containing compounds used as
monomers. When a membrane is formed by using spin-coating and the
like, homogeneous dissolution in a suitable solvent is necessary.
When a network-like polymer is three-dimensionally crosslinked to
high dense structure, it may cause lower solvent homogeneity or
solubility of a polymer in a solvent. Therefore, it is preferable
to control network degree in response to a solvent used or a
borazine ring-containing compound used.
[0030] When a composition containing a borazine ring-containing
compound is polymerized in network structure, workability is
improved in membrane formation by using spin-coating, compared with
the case using a composition containing only a borazine
ring-containing compound that is not polymerized. In industrial
mass production of the present invention, such effect is very
useful in view of cost and productivity.
[0031] R.sup.2, R.sup.4 and R.sup.6 bonding to nitrogen (N)
composing a borazine ring, each is hydrogen atom or alkyl group.
R.sup.2, R.sup.4 and R.sup.6 may be the same or different. Alkyl
group included as R.sup.2, R.sup.4 and R.sup.6 is not explained
here because it is the same as explained above as alkyl group
included as R.sup.1, R.sup.3, R.sup.5 and R.sup.7.
[0032] At least one of R.sup.1 to R.sup.6 in the formula (1)
includes hydrogen atom. When no hydrogen atom is present in R.sup.1
to R.sup.6, polycondensation does not proceed and a low dielectric
material having sufficient mechanical strength or humidity
resistance may not be formed.
[0033] By annealing a composition containing a borazine
ring-containing compound represented by the formula (1) or a
polymer thereof under oxygen concentration and temperature
conditions specified by the present invention, dielectric constant
or humidity resistance of a low dielectric material obtained can be
improved largely.
[0034] A specific example of a borazine ring-containing compound
represented by the formula (1) includes unsubstituted borazines;
alkylamino borazines such as B,B',B"-tris(propylamino)borazine,
B,B',B"-tris(hexylamino)borazine,
B,B',B"-tris(methylamino)borazine,
B,B',B"-tris(propylamino)-N,N',N"-trimethylborazine, etc.;
alkylborazines such as mono-B-methylborazine, di-B-methylborazine,
mono-N-ethylborazine, di-N-methylborazine, tri-N-propylborazine,
mono-N-di-B-methylborazine, etc.
[0035] A borazine ring-containing compound is one which can be
produced by known method under appropriate modification. Therefore,
in the present invention, a production method for a borazine
ring-containing compound is not especially limited. For example,
known method described in "Yosiharu Kimura, Fiber and Industry,
vol. 52, No. 8, p 341 (1996)", "Paine & Sneddon, Recent
Developments in Borazine-Based Polymers", "Inorganic and
Organometallic Polymers", p 359, American Chemical Society, 1994,
and the like can be referenced.
[0036] A composition containing a borazine ring-containing compound
may further contain other components, if necessary, within the
range not to impair the effects of the present invention. For
example, a polysiloxane based polymer described in JP-2002-317049A
may be included. An inorganic or organic type additive such as a
hardening catalyst, a wettability improver, a plasticizer, a
defoaming agent, a thickener, and the like may also be included in
suitable amount.
[0037] As solvents to dissolve or disperse a borazine
ring-containing compound, various solvents can be used as long as
they can dissolve a borazine ring-containing compound or other
components, which is optionally added. For example, alcohols such
as ethylene glycol, ethylene glycol monomethyl ether; aromatic
hydrocarbons such as toluene, benzene, xylene, etc.;
tetrahydrofuran, diglyme, tetraglyme, and the like can be used as
such solvents. They may be used as a single component or in
combination of two or more types.
[0038] Preferably, a solvent to dissolve or disperse a borazine
ring-containing compound is represented by the following formula:
6
[0039] By using a solvent represented by the above-described
formula as a solvent for a composition containing a borazine
ring-containing compound, uniformity of a membrane formed by using
a coating method is improved.
[0040] Each of R.sup.a and R.sup.c is alkyl group or acyl group.
R.sup.a and R.sup.c may be the same or different. Alkyl group which
can be included as R.sup.a and R.sup.c may be a straight, branched
or cyclic alkyl group.
[0041] A specific example of alkyl group which can be included as
R.sup.a and R.sup.c includes methyl group, ethyl group, propyl
group, isopropyl group, butyl group, isobutyl group, sec-butyl
group, tert-butyl group, pentyl group, neopentyl group, hexyl
group, heptyl group, octyl group, nonyl group, decyl group,
cyclopropyl group, cyclobutyl group, cyclopentyl group, cyclohexyl
group, etc. However, alkyl group which can be included as R.sup.a
and R.sup.c is not limited to these.
[0042] A specific example of acyl group which can be included as
R.sup.a and R.sup.c includes formyl group, acetyl group, propionyl
group, butyryl group, isobutyryl group, valeryl group, isovaleryl
group, pivaloyl group, hexanoyl group, etc. However, acyl group
which can be included as R.sup.a and R.sup.c is not limited to
these.
[0043] R.sup.b is hydrogen atom or alkyl group. A specific example
of alkyl group which can be included as R.sup.b includes methyl
group, ethyl group, propyl group, isopropyl group, butyl group,
isobutyl group, sec-butyl group, tert-butyl group, pentyl group,
neopentyl group, hexyl group, heptyl group, octyl group, nonyl
group, decyl group, cyclopropyl group, cyclobutyl group,
cyclopentyl group, cyclohexyl group, etc. However, alkyl group
which can be included as R.sup.b is not limited to these.
[0044] n is an integer of 1 to 5, preferably an integer of from 1
to 3, more preferably 1 or 2. When n is included in the preferable
range, membrane formability and appearance of a coated membrane
improve further.
[0045] When a borazine ring-containing compound is a compound
represented by the above-described formula (1) and when a solvent
represented by the above-described formula is used, they are
effective to improve membrane formability in spin-coating and
appearance of a coated membrane.
[0046] A specific example of the above-described compound
preferable as a solvent includes diglyme (also called as diethylene
glycol dimethyl ether), monoglyme (also called as ethylene glycol
dimethyl ether), ethylene glycol monomethyl ether, ethylene glycol
monoethyl ether, ethylene glycol diethyl ether, ethylene glycol
monopropyl ether, ethylene glycol dipropyl ether, ethylene glycol
butyl ether, ethylene glycol monoacetate, ethylene glycol
diacetate, ethylene glycol methyl ether acetate, ethylene glycol
ethyl ether acetate, ethylene glycol monobutyl ether acetate,
propylene glycol dimethyl ether, propylene glycol methyl ether
acetate, propylene glycol diacetate, diethylene glycol monomethyl
ether, diethylene glycol monoethyl ether, diethylene glycol diethyl
ether, diethylene glycol methyl ether acetate, diethylene glycol
ethyl ether acetate, diethylene glycol diacetate, triglyme (also
called as triethylene glycol dimethyl ether), triethylene glycol
monomethyl ether, tetraglyme (also called as tetraethylene glycol
dimethyl ether), etc. In view of membrane formability in coating
and appearance of a coated membrane, a compound, among exemplified
solvents, having n of integer from 1 to 3 is preferable and a
compound having n of integer of 1 or 2 is more preferable in the
general formula (1) representing a solvent used in the present
invention as described above.
[0047] The above-described compound included as a solvent is one
which can be produced by known methods under appropriate
modification. A commercial compound may be used. A composition for
low dielectric material of the present invention may contain two or
more types of solvents. In this case, all of these two or more
types of solvents may have structure represented by the
above-described chemical formula specified by the present
invention. Optionally, a different solvent may be used in addition
to a solvent represented by the above-described chemical formula.
However, in such a case, a solvent represented by the
above-described chemical formula is contained preferably in the
amount of not less than 25 wt % of total solvent weight.
[0048] In a composition for low dielectric material of the present
invention, a solvent, a borazine ring-containing compound and
optional other additives may be included. Content of each component
in a composition for low dielectric material is not especially
limited and optimal conditions may be selected in response to
applications and practice embodiments. For example, when a
composition for low dielectric material is coated by spin-coating,
amount of the compounding is determined in view of uniformity of a
coated membrane and economical aspect. In general, in a composition
for low dielectric material, 50 to 99 wt % of a solvent and 1 to
50% of a borazine ring-containing compound is preferably contained
based on total weight of a composition for low dielectric material.
When they are contained within the above-described range, a low
dielectric material superior in water resistance, economical
aspect, humidity resistance, heat resistance, chemical resistance,
mechanical strength, durability, and the like is obtained.
[0049] A composition containing a borazine ring-containing compound
is fed to a place desired, dried and solidified. For example, to
form an interlayer dielectric film for semiconductor device, it is
coated on a substrate by spin-coating and dried. When a coated
membrane with desired thickness is not obtained by one
coating-and-drying step, coating-and-drying may be repeated until
desired thickness is attained. Membrane formation conditions such
as rotation number of a spin-coater, temperature for drying and
time for drying are not especially limited.
[0050] Coating on a substrate may be performed using a method other
than spin-coating. For example, spray coating, dip coating, and the
like may be used. Furthermore in producing a low dielectric
substrate as a bulk body, a composition containing a borazine
ring-containing compound may be flowed in a template to be molded
and then a molded part thus obtained is annealed. However, when the
above-described preferable solvent, such as diglyme as a
representative one, is used, it is preferable to use
spin-coating.
[0051] Then a dried membrane is annealed under atmosphere of oxygen
concentration preferably not higher than 0.1 vol %, more preferably
not higher than0.0000001vol % (not higher than 0.1 vol ppm). When
oxygen concentration in atmosphere is higher, dielectric constant
of a low dielectric material obtained tends to become higher. It is
preferable that oxygen concentration in atmosphere is as low as
possible and the lower limit is not especially limited.
[0052] Oxygen concentration in the present application means oxygen
concentration in atmosphere inside an annealing unit in which a
coated membrane is placed. Specifically, oxygen concentration can
be determined by measurement using a zirconia oxygen concentration
analyzer.
[0053] Annealing temperature of a dried membrane is preferably
controlled from 200 to 600.degree. C., more preferably from 300 to
500.degree. C. When annealing temperature is too low, humidity
resistance of a low dielectric material obtained tends to be
lowered. While, annealing temperature is too high, defect such as
crack may generate at the surface of a low dielectric material
obtained.
[0054] Annealing temperature in the present application means
maximum temperature in annealing treatment. For example, when
annealing temperature is gradually increased and held at
400.degree. C. for 30 minutes, followed by cooling, "annealing
temperature" is defined to be 400.degree. C. Annealing temperature
can be measured by a thermocouple. However, the means to measure
annealing temperature is not especially limited.
[0055] Annealing time for a dried membrane is not especially
limited. It is preferable to be determined under consideration of
characteristics such as a low dielectric material obtained, such as
dielectric constant, humidity resistance, and the like. It is
usually about 3 to 300 minutes as period from start of temperature
increase to completion of cooling.
[0056] A composition for low dielectric material of the present
invention can be used, as described above, in producing a low
dielectric material. And a low dielectric material of the present
invention is preferably used as an interlayer dielectric film for
semiconductor device. Because an interlayer dielectric film of the
present invention is superior in dielectric constant, humidity
resistance, and the like, it is useful to various semiconductor
devices such as a LSI element, an IC substrate, etc. In particular,
as an interlayer dielectric film of the present invention has low
dielectric constant, it can greatly contribute to realization of
high speed ULSI.
[0057] Compositions of various electronics parts such as LSI, IC,
and the like are not especially limited as long as they are
semiconductor device where an interlayer dielectric film of the
present invention is formed. Semiconductor device having an
interlayer dielectric film of the present invention is included
within technical scope of the present invention.
EXAMPLES
[0058] Then, the effects of the present invention are explained
using Examples. However, technical scope of the present invention
is not limited to the following Examples.
[0059] (Synthesis 1)
[0060] B,B',B"-trichloroborazine (15 g) was dissolved into
sufficiently dewatered toluene (100 mL) and a mixture solution of
n-propyl amine (22 g), triethyl amine (25 g) and toluene (100 mL)
was dropped over 1 hour at room temperature. After completion of
the drop-wise addition, the solution was stirred at 25.degree. C.
for 3 hours and further at 60.degree. C. for 3 hours. An amine-HCl
salt generated was removed by filtration, followed by removal of
the solvent and unreacting amine under reduced pressure to obtain
B,B',B"-tris(propylamino)borazine as yellow viscous liquid (22.5 g)
(see the following scheme). Thus obtained compound was further
stirred in xylene at 130.degree. C. for 3 hours to proceed
polycondensation reaction. After the reaction, the solvent is
removed under reduced pressure to obtain a borazine ring-containing
compound 1, as a polymer with network-like bonding of repeating
units (see the following scheme).
[0061] (Synthesis of B,B',B"-tris(propylamino)borazine) 7
[0062] (polycondensation reaction) 8
[0063] (Synthesis 2)
[0064] B,B',B"-trichloroborazine (15 g) was dissolved into
sufficiently dewatered toluene (100 mL) and a mixture solution of
n-hexyl amine (37 g), triethyl amine (25 g) and toluene (100 mL)
was dropped over 1 hour at room temperature. After completion of
the drop-wise addition, the solution was stirred at 25.degree. C.
for 3 hours and further at 60.degree. C. for 3 hours. An amine-HCl
salt generated was removed by filtration, followed by removal of
the solvent and unreacting amine under reduced pressure to obtain
B,B',B"-tris (hexylamino)borazine as yellow viscous liquid (30 g).
Thus obtained compound was further stirred in xylene at 130.degree.
C. for 3 hours to proceed polycondensation reaction. After the
reaction, the solvent is removed under reduced pressure to obtain a
borazine ring-containing compound 2.
[0065] (Synthesis 3)
[0066] B,B',B"-trichloroborazine (15 g) was dissolved into
sufficiently dewatered toluene (100 mL) and dropped over 1 hour
into a flask containing methyl amine (16 g), held at about
-70.degree. C. After completion of the drop-wise addition, the
solution was stirred at 25.degree. C. for 3 hours and further at
60.degree. C. for 3 hours. An amine-HCl salt generated was removed
by filtration, followed by removal of the solvent and unreacting
amine under reduced pressure to obtain
B,B',B"-tris(methylamino)borazine as white viscous liquid (12 g).
Thus obtained compound was further stirred in xylene at 130.degree.
C. for 3 hours to proceed polycondensation reaction. After the
reaction, the solvent is removed under reduced pressure to obtain a
borazine ring-containing compound 3.
[0067] (Synthesis 4)
[0068] B,B',B"-trichloro-N,N',N"-trimethylborazine (15 g) was
dissolved into sufficiently dewatered toluene (100 mL) and a
mixture solution of n-propyl amine (14 g), triethylamine (23g) and
toluene (100 mL) was dropped over 1 hour at room temperature. After
completion of the drop-wise addition, the solution was stirred at
25.degree. C. for 3 hours and further at 60.degree. C. for 3 hours.
An amine-HCl salt generated was removed by filtration, followed by
removal of the solvent and unreacting amine under reduced pressure
to obtain B,B',B"-tris(propylamino)-N,N',N"-- trimethylborazine as
yellow viscous liquid (17 g). Thus obtained compound was further
stirred in xylene at 130.degree. C. for 3 hours to proceed
polycondensation reaction. After the reaction, the solvent is
removed under reduced pressure to obtain a borazine ring-containing
compound 4.
[0069] 1. Study on the Effects of Annealing Conditions
Example 1
[0070] The borazine ring-containing compound 1 obtained in
Synthesis 1 was dissolved in sufficiently dried xylene to obtain a
solution of 10 wt % of the borazine ring-containing compound. This
solution was coated on a silicon substrate using a spin-coater at
3000 rpm, followed by drying at 120.degree. C. for 3 minutes. By
repeating this operation 8 times, a coated membrane with thickness
of 1 .mu.m was obtained. This membrane was annealed at 350.degree.
C. for 30 minutes under argon atmosphere with oxygen concentration
not higher than 0.1 ppm to form a transparent coated membrane 1
without any crack. To the coated membrane 1, a gold electrode was
vapor deposited to measure dielectric constant of the membrane.
Humidity resistance of the membrane was also evaluated. Results are
shown in Table 1.
[0071] Humidity resistance was evaluated by observation of
appearance change at 20.degree. C. and 20% RH conditions based on
the following criteria:
[0072] .circleincircle.: no change for 2 days or more
[0073] .largecircle.: change in 1 to 2 days
[0074] .times.: change within 1 day.
Example 2
[0075] A coated membrane 2 was formed in accordance with procedure
in Example 1 except that a borazine ring-containing compound 2
obtained in Synthesis 2 was used. Measurement results of dielectric
constant and humidity resistance of the coated membrane 2 are shown
in Table 1.
Example 3
[0076] A coated membrane 3 was formed in accordance with procedure
in Example 1 except that the borazine ring-containing compound 3
obtained in Synthesis 3 was used. Measurement results of dielectric
constant and humidity resistance of the coated membrane 3 are shown
in Table 1.
Example 4
[0077] A coated membrane 4 was formed in accordance with procedure
in Example 1 except that the borazine ring-containing compound 4
obtained in Synthesis 4 was used. Measurement results of dielectric
constant and humidity resistance of the coated membrane 4 are shown
in Table 1.
Example 5
[0078] A coated membrane 5 was formed in accordance with procedure
in Example 1 except that annealing temperature was set at
550.degree. C. Measurement results of dielectric constant and
humidity resistance of the coated membrane 5 are shown in Table
1.
Example 6
[0079] A coated membrane 6 was formed in accordance with procedure
in Example 2 except that annealing temperature was set at
550.degree. C. Measurement results of dielectric constant and
humidity resistance of the coated membrane 6 are shown in Table
1.
Example 7
[0080] A coated membrane 7 was formed in accordance with procedure
in Example 3 except that annealing temperature was set at
550.degree. C. Measurement results of dielectric constant and
humidity resistance of the coated membrane 7 are shown in Table
1.
Example 8
[0081] A coated membrane 8 was formed in accordance with procedure
in Example 4 except that annealing temperature was set at
550.degree. C. Measurement results of dielectric constant and
humidity resistance of the coated membrane 8 are shown in Table
1.
Example 9
[0082] A coated membrane 9 was formed in accordance with procedure
in Example 1 except that annealing temperature was set at
200.degree. C. Measurement results of dielectric constant and
humidity resistance of the coated membrane 9 are shown in Table
1.
Example 10
[0083] A coated membrane 10 was formed in accordance with procedure
in Example 2 except that annealing temperature was set at
200.degree. C. Measurement results of dielectric constant and
humidity resistance of the coated membrane 10 are shown in Table
1
Example 11
[0084] A coated membrane 11 was formed in accordance with procedure
in Example 3 except that annealing temperature was set at
200.degree. C. Measurement results of dielectric constant and
humidity resistance of the coated membrane 11 are shown in Table
1
Example 12
[0085] A coated membrane 12 was formed in accordance with procedure
in Example 4 except that annealing temperature was set at
200.degree. C. Measurement results of dielectric constant and
humidity resistance of the coated membrane 12 are shown in Table
1
Comparative Example 1
[0086] A coated membrane 13 was formed in accordance with procedure
in Example 1 except that annealing was performed under oxygen
concentration of 20%. Measurement results of dielectric constant
and humidity resistance of the coated membrane 13 are shown in
Table 1.
Comparative Example 2
[0087] A coated membrane 14 was formed in accordance with procedure
in Example 2 except that annealing was performed under oxygen
concentration of 20%. Measurement results of dielectric constant
and humidity resistance of the coated membrane 14 are shown in
Table 1.
Comparative Example 3
[0088] A coated membrane 15 was formed in accordance with procedure
in Example 3 except that annealing was performed under oxygen
concentration of 20%. Measurement results of dielectric constant
and humidity resistance of the coated membrane 15 are shown in
Table 1.
Comparative Example 4
[0089] A coated membrane 16 was formed in accordance with procedure
in Example 4 except that annealing was performed under oxygen
concentration of 20%. Measurement results of dielectric constant
and humidity resistance of the coated membrane 16 are shown in
Table 1.
Comparative Example 5
[0090] A coated membrane 17 was formed in accordance with procedure
in Example 1 except that annealing temperature was set at
150.degree. C. Measurement results of dielectric constant and
humidity resistance of the coated membrane 17 are shown in Table
1.
Comparative Example 6
[0091] A coated membrane 18 was formed in accordance with procedure
in Example 2 except that annealing temperature was set at
150.degree. C. Measurement results of dielectric constant and
humidity resistance of the coated membrane 18 are shown in Table
1.
Comparative Example 7
[0092] A coated membrane 19 was formed in accordance with procedure
in Example 3 except that annealing temperature was set at
150.degree. C. Measurement results of dielectric constant and
humidity resistance of the coated membrane 19 are shown in Table
1.
Comparative Example 8
[0093] A coated membrane 20 was formed in accordance with procedure
in Example 4 except that annealing temperature was set at
150.degree. C. Measurement results of dielectric constant and
humidity resistance of the coated membrane 20 are shown in Table
1.
Comparative Example 9
[0094] A coated membrane 21 was formed in accordance with procedure
in Example 1 except that annealing temperature was set at
700.degree. C. Measurement results of dielectric constant and
humidity resistance of the coated membrane 21 are shown in Table
1.
Comparative Example 10
[0095] A coated membrane 22 was formed in accordance with procedure
in Example 2 except that annealing temperature was set at
700.degree. C. Measurement results of dielectric constant and
humidity resistance of the coated membrane 22 are shown in Table
1.
Comparative Example 11
[0096] A coated membrane 23 was formed in accordance with procedure
in Example 3 except that annealing temperature was set at
700.degree. C. Measurement results of dielectric constant and
humidity resistance of the coated membrane 23 are shown in Table
1.
Comparative Example 12
[0097] A coated membrane 24 was formed in accordance with procedure
in Example 4 except that annealing temperature was set at
700.degree. C. Measurement results of dielectric constant and
humidity resistance of the coated membrane 24 are shown in Table
1.
1 TABLE 1 Borazine Coated ring-containing Annealing Annealing
Dielectric Humidity membrane compound atmosphere temperature
constant resistance example 1 1 1 Argon 350.degree. C. 2.5
.circleincircle. example 2 2 2 Argon 350.degree. C. 2.4
.circleincircle. example 3 3 3 Argon 350.degree. C. 2.3
.circleincircle. example 4 4 4 Argon 350.degree. C. 2.3
.circleincircle. example 5 5 1 Argon 550.degree. C. 2.8
.circleincircle. example 6 6 2 Argon 550.degree. C. 2.7
.circleincircle. example 7 7 3 Argon 550.degree. C. 2.7
.circleincircle. example 8 8 4 Argon 550.degree. C. 2.8
.circleincircle. example 9 9 1 Argon 200.degree. C. 2.5
.largecircle. example 10 10 2 Argon 200.degree. C. 2.3
.largecircle. example 11 11 3 Argon 200.degree. C. 2.3
.largecircle. example 12 12 4 Argon 200.degree. C. 2.2
.largecircle. comparative 13 1 Air 350.degree. C. 3.3 .largecircle.
example 1 comparative 14 2 Air 350.degree. C. 3.2 .largecircle.
example 2 comparative 15 3 Air 350.degree. C. 3.5 .largecircle.
example 3 comparative 16 4 Air 350.degree. C. 5.6 .largecircle.
example 4 comparative 17 1 Argon 150.degree. C. -- X example 5
comparative 18 2 Argon 150.degree. C. -- X example 6 comparative 19
3 Argon 150.degree. C. -- X example 7 comparative 20 4 Argon
150.degree. C. -- X example 8 comparative 21 1 Argon 700.degree. C.
Crack -- example 9 comparative 22 2 Argon 700.degree. C. Crack --
example 10 comparative 23 3 Argon 700.degree. C. Crack -- example
11 comparative 24 4 Argon 700.degree. C. Crack -- example 12
[0098] As shown by Comparative Examples 1 to 4 (coated membranes 13
to 16), when oxygen concentration in annealing atmosphere was high,
dielectric constant of low dielectric materials obtained increased.
As shown by Comparative Examples 5 to 8 (coated membranes 17 to
20), when annealing temperature was low, humidity resistance of low
dielectric materials obtained was insufficient. The low dielectric
materials obtained did not show function as low dielectric
materials due to hydrolysis of coated membranes by moisture in
atmosphere. As shown by Comparative Examples 9 to 12 (coated
membranes 21 to 24), when annealing temperature was high, crack
generated in low dielectric materials obtained. A part of low
dielectric materials was found to be peeled from a substrate.
While, low dielectric materials of the present invention had low
dielectric constant and were also superior in humidity
resistance.
[0099] Thus, by controlling annealing conditions, a low dielectric
material having low dielectric constant and also high humidity
resistance can be obtained.
[0100] 2. Study on the Effects of a Solvent
Example 13
[0101] The borazine ring-containing compound 1 obtained in
Synthesis 1 was dissolved in sufficiently dried diglyme to obtain a
composition for low dielectric material containing 10 wt % of the
borazine ring-containing compound. This composition for low
dielectric material obtained was coated on a silicon substrate
using a spin-coater at 3000 rpm, followed by drying at 120.degree.
C. for 3 minutes. By repeating this operation 8 times, a coated
membrane with thickness of 1 .mu.m was obtained. This membrane was
annealed at 350.degree. C. for 30 minutes under argon atmosphere
with oxygen concentration not higher than 0.1 ppm to form a
transparent coated membrane 25 without any crack. The coated
membrane 25 was uniform and appearance was also good. To the coated
membrane obtained, a gold electrode was vapor deposited to measure
dielectric constant of the membrane. Measurement results are shown
in Table 2.
Example 14
[0102] A coated membrane 26 was formed in accordance with procedure
in Example 13 except that a borazine ring-containing compound 2
obtained in Synthesis 2 was used. The coated membrane 26 was
uniform and appearance was good. Measurement results of appearance
and dielectric constant of the coated membrane 26 are shown in
Table 2.
Example 15
[0103] A coated membrane 27 was formed in accordance with procedure
in Example 13 except that a borazine ring-containing compound 3
obtained in Synthesis 3 was used. The coated membrane 27 was
uniform and appearance was good. Measurement results of appearance
and dielectric constant of the coated membrane 27 are shown in
Table 2.
Example 16
[0104] A coated membrane 28 was formed in accordance with procedure
in Example 13 except that a borazine ring-containing compound 4
obtained in Synthesis 4 was used. The coated membrane 28 was
uniform and appearance was good. Measurement results of appearance
and dielectric constant of the coated membrane 28 are shown in
Table 2.
Comparative Example 13
[0105] A coated membrane 29 was formed in accordance with procedure
in Example 13 except that toluene was used as a solvent instead of
diglyme. The coated membrane 29 showed white turbid state. The
coated membrane 29 was also an unsatisfactory membrane because
streak or convex points were formed at the surface.
Comparative Example 14
[0106] A coated membrane 30 was formed in accordance with procedure
in Example 14 except that tetrahydrofuran (THF) was used as a
solvent instead of diglyme. The coated membrane 30 showed white
turbid state. The coated membrane 30 was also an unsatisfactory
membrane because streak or convex points were formed at the
surface.
Comparative Example 15
[0107] A coated membrane 31 was formed in accordance with procedure
in Example 15 except that toluene was used as a solvent instead of
diglyme. The coated membrane 31 showed white turbid state. The
coated membrane 31 was also an unsatisfactory membrane because
streak or convex points were formed at the surface.
Comparative Example 16
[0108] A coated membrane 32 was formed in accordance with procedure
in Example 16 except that ethanol was used as a solvent instead of
diglyme. The coated membrane 32 showed white turbid state. The
coated membrane 32 was also an unsatisfactory membrane because
streak or convex points were formed at the surface.
2 TABLE 2 Borazine ring Coated containing Appearance of Dielectric
membrane compound Solvent coated membrane constant example 13 25 1
Diglyme Transparent, Good 2.5 example 14 26 2 Diglyme Transparent,
Good 2.6 example 15 27 3 Diglyme Transparent, Good 2.3 example 16
28 4 Diglyme Transparent, Good 2.5 comparative 29 1 Toluene Turbid,
poor -- example 13 comparative 30 2 THF Turbid, poor -- example 14
comparative 31 3 Toluene Turbid, poor -- example 15 comparative 32
4 Ethanol Turbid, poor -- example 16
[0109] As shown by Table 2, when a solvent specified by the present
invention was used as a solvent for a borazine ring-containing
compound, a superior coated membrane without any trouble such as
white turbidity was obtained.
[0110] Thus, by using a composition for low dielectric material
containing a solvent having structure represented by the
above-described formula, a uniform coated membrane is formed. For
example, when an interlayer dielectric film for semiconductor
device is produced by using a composition of the present invention,
reliability of semiconductor device produced is improved.
Furthermore, by using a composition of the present invention,
improvement of production yield for semiconductor device is
expected, which can greatly contribute in industrial mass
production step.
* * * * *