U.S. patent application number 09/765196 was filed with the patent office on 2001-10-04 for electrically insulating crosslinked thin-film-forming organic resin composition and method for forming thin film therefrom.
Invention is credited to Kobayashi, Akihiko, Mine, Katsutoshi, Nakamura, Takashi, Sawa, Kiyotaka.
Application Number | 20010026847 09/765196 |
Document ID | / |
Family ID | 18579074 |
Filed Date | 2001-10-04 |
United States Patent
Application |
20010026847 |
Kind Code |
A1 |
Nakamura, Takashi ; et
al. |
October 4, 2001 |
Electrically insulating crosslinked thin-film-forming organic resin
composition and method for forming thin film therefrom
Abstract
An electrically insulating crosslinked thin-film-forming organic
resin composition comprising (A) an electrically insulating organic
resin having silicon atom-bonded hydrogen atoms or silicon
atom-bonded alkenyl groups and (B) a solvent, and a method for
forming a crosslinked thin film therefrom.
Inventors: |
Nakamura, Takashi; (Chiba
Prefecture, JP) ; Kobayashi, Akihiko; (Chiba
Prefecture, JP) ; Sawa, Kiyotaka; (Chiba Prefecture,
JP) ; Mine, Katsutoshi; (Chiba Prefecture,
JP) |
Correspondence
Address: |
Dow Corning Corporation
Intellectual Property Department
Mail C01232
P. O. Box 994
Midland
MI
48686-0994
US
|
Family ID: |
18579074 |
Appl. No.: |
09/765196 |
Filed: |
January 18, 2001 |
Current U.S.
Class: |
427/551 ;
257/E21.26; 257/E21.261; 528/28 |
Current CPC
Class: |
H01L 21/3122 20130101;
H01L 21/02351 20130101; H01L 21/3121 20130101; G03F 7/0758
20130101; H01L 21/02282 20130101; H01L 21/02126 20130101; H01L
21/02216 20130101; G03F 7/0757 20130101 |
Class at
Publication: |
427/551 ;
528/28 |
International
Class: |
C08G 077/04; C08J
007/18 |
Foreign Application Data
Date |
Code |
Application Number |
Mar 3, 2000 |
JP |
2000-058484 |
Claims
We claim:
1. An electrically insulating crosslinkable thin-film-forming
organic resin composition comprising (A) an electrically insulating
organic resin having silicon atom-bonded hydrogen atoms or silicon
atom-bonded alkenyl groups and (B) a solvent.
2. The electrically insulating crosslinkable thin-film-forming
organic resin composition of claim 1, where component (A) is a
silicone modified organic resin comprising organic resin blocks and
organopolysiloxane blocks, and the silicon atom-bonded hydrogen
atoms or silicon atom-bonded alkenyl groups are bonded to silicon
atoms in the organopolysiloxane blocks.
3. The electrically insulating crosslinkable thin-film-forming
organic resin composition of claim 2, where component (A) is a
silicone modified polyimide resin comprising polyimide resin blocks
and organopolysiloxane blocks.
4. The electrically insulating crosslinkable thin-film-forming
organic resin composition of claim 3, where component (A) is a
silicone modified polyimide resin described by general formula
11where R.sup.1 alkyl group or aryl group, R.sup.2 is an alkylene
group or arylene group, a is an integer of at least one, b is an
integer of zero or greater, c is an integer of at least one, and n
is an integer of at least one.
5. The electrically insulating crosslinkable thin-film-forming
organic resin composition of claim 3, where component (A) is a
silicone modified polyimide resin described by general formula
12where R.sup.1 is an alkyl group or aryl group, R.sup.2 is an
alkylene group or arylene group, R.sup.3 is an alkylene group,
R.sup.4 is an alkenyl group, a is an integer of at least one, b is
an integer of zero or greater, c is an integer of at least one, d
is an integer of at least one, and n is an integer of at least
one.
6. The electrically insulating crosslinkable thin-film-forming
organic resin composition of claim 1, where component (A) comprises
(i) an electrically insulating organic resin having silicon
atom-bonded hydrogen atoms and (ii) an electrically insulating
organic resin having silicon atom-bonded alkenyl groups, and
further comprises (C) a hydrosilylation catalyst.
7. The electrically insulating crosslinkable thin-film-forming
organic resin composition of claim 6, where component (i) is a
silicone modified organic resin comprising organic resin blocks and
organopolysiloxane blocks, and the silicon atom-bonded hydrogen
atoms are bonded to silicon atoms in the organopolysiloxane
blocks.
8. The electrically insulating crosslinkable thin-film-forming
organic resin composition of claim 6, where component (i) is a
silicone modified polyimide resin comprising polyimide resin blocks
and organopolysiloxane blocks.
9. The electrically insulating crosslinkable thin-film-forming
organic resin composition of claim 8, where component (i) is a
silicone modified polyimide resin described by general formula
13where R.sup.1 is an alkyl group or aryl group, R.sup.2 is an
alkylene group or arylene group, a is an integer of at least one, b
is an integer of zero or greater, c is an integer of at least one,
and n is an integer of at least one.
10. The electrically insulating crosslinkable thin-film-forming
organic resin composition of claim 6, where component (ii) is a
silicone modified organic resin comprising organic resin blocks and
organopolysiloxane blocks, and the alkenyl groups are bonded to
silicon atoms in the organopolysiloxane blocks.
11. The electrically insulating crosslinkable thin-film-forming
organic resin composition of claim 10, where component (i) is a
silicone modified polyimide resin comprising polyimide resin blocks
and organopolysiloxane blocks.
12. The electrically insulating crosslinkable thin-film-forming
organic resin composition of claim 11, where component (ii) is a
silicone modified polyimide resin described by general formula
14where R.sup.1 is an alkyl group or aryl group, R.sup.2 is an
alkylene group or arylene group, R.sup.3 is an alkylene group,
R.sup.4 is an alkenyl group, a is an integer of at least one, b is
an integer of zero or greater, c is an integer of at least one, d
is an integer of at least one, and n is an integer of at least
one.
13. A method for forming an electrically insulating crosslinked
thin film comprising coating a surface of an electronic device with
an electrically insulating crosslinkable thin-film-forming organic
resin composition comprising (A) an electrically insulating organic
resin having silicon atom-bonded hydrogen atoms or silicon
atom-bonded alkenyl groups and (B) a solvent, evaporating a part or
all of the solvent, and crosslinking the electrically insulating
organic resin by a method selected from the group consisting of
heating and irradiation with high-energy rays.
14. A method for forming an electrically insulating crosslinked
thin film according to claim 13, where component (A) is a silicone
modified organic resin comprising organic resin blocks and
organopolysiloxane blocks, and the silicon atom-bonded hydrogen
atoms or silicon atom-bonded alkenyl groups are bonded to silicon
atoms in the organopolysiloxane blocks.
15. A method for forming an electrically insulating crosslinked
thin film according to claim 14, where component (A) is a silicone
modified polyimide resin comprising polyimide resin blocks and
organopolysiloxane blocks.
16. A method for forming an electrically insulating crosslinked
thin film according to claim 15, where component (A) is a silicone
modified polyimide resin described by general formula 15where
R.sup.1 is an alkyl group or aryl group, R.sup.2 is an alkylene
group or arylene group, a is an integer of at least one, b is an
integer of zero or greater, c is an integer of at least one, and n
is an integer of at least one.
17. A method for forming an electrically insulating crosslinked
thin film according to claim 15, where component (A) is a silicone
modified polyimide resin described by general formula 16where
R.sup.1 is an alkyl group or aryl group, R.sup.2 is an alkylene
group or arylene group, R.sup.3 is an alkylene group, R.sup.4 is an
alkenyl group, a is an integer of at least one, b is an integer of
zero or greater, c is an integer of at least one, d is an integer
of at least one, and n is an integer of at least one.
18. A method for forming an electrically insulating crosslinked
thin film according to claim 13, where component (A) comprises (i)
an electrically insulating organic resin having silicon atom-bonded
hydrogen atoms and (ii) an electrically insulating organic resin
having silicon atom-bonded alkenyl groups, and further comprises
(C) a hydrosilylation catalyst.
Description
FIELD OF THE INVENTION
[0001] The present invention relates to an electrically insulating
crosslinkable thin-film-forming organic resin composition and to a
method for forming an electrically insulating crosslinkable thin
film. More particularly, it relates to an electrically insulating
crosslinked thin-film-forming organic resin composition from which
it is possible to form a crosslinkable thin film having good heat
resistance and low dielectric constant and excellent adhesion to
the surface of electronic devices, and to a method for efficiently
forming on the surface of an electronic device a thin film having
good heat resistance and low dielectric constant and excellent
adhesion to the surface.
BACKGROUND OF THE INVENTION
[0002] Examples of a method for forming an electrically insulating
crosslinked thin film on the surface of an electronic device
include a method in which the surface of an electronic device is
coated with a hydrogen silsesquioxane resin solution, the solvent
is evaporated off, and the surface is then heated at 150 to
1000.degree. C. (see Japanese Laid-Open Patent Application
S63-144525), and a method in which the surface of an electronic
device is coated with a solution of a hydrogen silsesquioxane resin
and a platinum or rhodium catalyst, the solvent is evaporated off,
and the surface is then heated at 150 to 1000.degree. C. (see
Japanese Laid-Open Patent Application S63-144524).
[0003] As miniaturization and integration have increased in
electronic devices in recent years, there has been a need for a
method for forming an electrically insulating layer with a low
dielectric constant. More specifically, there is a need for a
method for forming an electrically insulating layer with a low
dielectric constant (a specific inductive capacity of less than
2.5) in a highly integrated circuit with a next-generation design
rule of 0.15 .mu.m or less. Accordingly, Japanese Laid-Open Patent
Application H10-279687 proposes a method in which the surface of an
electronic device is coated with a solution composed of a hydrogen
silsesquioxane resin and two types of solvent with different
boiling points or affinity to this resin, after which part of the
solvent is evaporated, and the surface is heated to evaporate the
solvent either during or after the crosslinking of the resin,
thereby forming a porous electrically insulating crosslinked thin
film.
[0004] However, a porous electrically insulating crosslinked thin
film generally has poor mechanical strength and is susceptible to
infiltration and attack by a variety of chemicals, and therefore
cannot sufficiently stand up to next-generation multilayer wiring
processes, and particularly a copper dual damascene process,
therefore making such films impractical. Also, to form an
electrically insulating crosslinked thin film with a low dielectric
constant, a relatively large amount of silicon atom-bonded hydrogen
atoms must be present in the hydrogen silsesquioxane resin, and
consequently the silicon atom-bonded hydrogen atoms in the thin
film react due to the heat, various chemicals, or plasma
encountered in the various steps following the formation of the
thin film, such as the multilayer wiring of an electronic device,
which further raises the density of the thin film and drives up the
dielectric constant.
[0005] There have also been numerous proposals for electrically
insulating crosslinkable thin-film-forming organic resin
compositions that form electrically insulating thin films with a
relatively low dielectric constant, but the problem with these
electrically insulating thin films is their poor heat resistance
and when they are heated to over 400.degree. C. in the course of
manufacturing an electronic device there is a decrease in the film
quality or quantity. Furthermore, such electrically insulating thin
films have inferior adhesion to electronic device surfaces and peel
off during the manufacturing of such an electronic device.
[0006] Specifically, it is an object of the present invention to
provide an electrically insulating crosslinkable thin-film-forming
organic resin composition from which it is possible to form a
crosslinked thin film having good heat resistance and low
dielectric constant and excellent adhesion to the surface of
electronic devices, and to a method for efficiently forming on an
electronic device surface an electrically insulating crosslinked
thin film having good heat resistance and low dielectric constant
and excellent adhesion to the surface of electronic devices.
SUMMARY OF THE INVENTION
[0007] The present invention is an electrically insulating
crosslinkable thin-film-forming organic resin composition
comprising (A) an electrically insulating organic resin having
silicon atom-bonded hydrogen atoms or silicon atom-bonded alkenyl
groups and (B) a solvent, and a method for forming a crosslinked
thin film therefrom.
DESCRIPTION OF THE INVENTION
[0008] The present invention is an electrically insulating
crosslinkable thin-film-forming organic resin composition
comprising (A) an electrically insulating organic resin having
silicon atom-bonded hydrogen atoms or silicon atom-bonded alkenyl
groups and (B) a solvent, and a method for forming a crosslinked
thin film therefrom.
[0009] First, the electrically insulating crosslinkable
thin-film-forming organic resin composition of the present
invention will be described in detail. Examples of the electrically
insulating organic resin of component (A) include polyimide resins;
polytetrafluoroethylene resins and other fluorocarbon resins;
benzocyclobutene resins; fluorinated polyallyl ether resins;
polyethylene resins and other polyolefin resins; and polyacrylate
resins, polycarbonate resins, polyamide resins, polysulfone resins,
polyether ether ketone resins, polyether nitrile resins,
polystyrene resins, and ABS resins. Preferably, this resin is a
silicone modified organic resin composed of organic resin blocks
and organopolysiloxane blocks. Most preferred is a silicone
modified polyimide resin composed of polyimide resin blocks and
organopolysiloxane blocks. Preferably, the silicon atom-bonded
hydrogen atoms or alkenyl groups are bonded to silicon atoms in the
organopolysiloxane blocks in the electrically insulating organic
resin of component (A). It is particularly favorable if they are
bonded to the silicon atoms in the organopolysiloxane blocks in a
silicone modified polyimide resin. A silicone modified polyimide
resin having silicon atom-bonded hydrogen atoms such as this is
described by the following general formula. 1
[0010] In the above formula, R.sup.1 is an alkyl group or aryl
group. Examples of the alkyl groups represented by R.sup.1 include
methyl, ethyl, and propyl, while examples of the aryl groups
represented by R.sup.1 include phenyl and tolyl. R.sup.2 in the
above formula is an alkylene group or arylene group. Examples of
the alkylene groups represented by R.sup.2 include methylene,
ethylene, and propylene, while examples of the arylene groups
represented by R.sup.2 include phenylene. Subscript a in the above
formula is an integer of at least one, b is an integer of zero or
greater, c is an integer of at least one, and n is an integer of at
least one. An example of a silicone modified polyimide resin such
as this is described by the following general formula. 2
[0011] In the formula, Me is a methyl group and n is an integer of
at least one.
[0012] An example of a silicone modified polyimide resin having
silicon atom-bonded alkenyl groups is expressed by the following
general formula. 3
[0013] R.sup.1 in the above formula is an alkyl group or aryl
group. Examples of the alkyl groups represented by R.sup.1 include
methyl, ethyl, and propyl, while examples of the aryl groups
represented by R.sup.1 include phenyl and tolyl. R.sup.2 in the
above formula is an alkylene group or arylene group. Examples of
the alkylene groups represented by R.sup.2 include ethylene and
propylene, while examples of the arylene groups represented by
R.sup.2 include phenylene. R.sup.3 in the above formula is an
alkylene group, examples of which include ethylene and propylene.
R.sup.4 in the above formula is an alkenyl group, example of which
includes vinyl, allyl, and butenyl. Subscript a in the above
formula is an integer of at least one, b is an integer of zero or
greater, c is an integer of at least one, d is an integer of at
least one, and n is an integer of at least one. An example of a
silicone modified polyimide resin such as this is described by the
following formula. 4
[0014] In the formula, Me is a methyl group and n is an integer of
at least one.
[0015] When two or more types of electrically insulating organic
resin are used together as component A in the present composition,
a combination of (i) an electrically insulating organic resin
having silicon atom-bonded hydrogen atoms and (ii) an electrically
insulating organic resin having silicon atom-bonded alkenyl groups
is preferable. Examples of the electrically insulating organic
resin of component (i) are the same as those listed above, with a
silicone modified organic resin composed of organic resin blocks
and organopolysiloxane blocks being preferable, and a silicone
modified polyimide resin composed of polyimide resin blocks and
organopolysiloxane blocks being particularly favorable. Examples of
such silicone modified polyimide resins are the same as those
listed above. Examples of the electrically insulating organic resin
of component (ii) are the same as those listed above, with a
silicone modified organic resin composed of organic resin blocks
and organopolysiloxane blocks being preferable, and a silicone
modified polyimide resin composed of polyimide resin blocks and
organopolysiloxane blocks being particularly favorable. Examples of
such silicone modified polyimide resins are the same as those
listed above. When component (i) and component (ii) are used
together, it is preferable for the amount of component (ii) to be
such that the amount of alkenyl groups in component (ii) is 0.1 to
10 mol per mole of silicon atom-bonded hydrogen atoms in component
(i). This is because if the component (ii) content is outside the
above range, there is the danger that the obtained composition will
not be sufficiently crosslinked merely by being left at room
temperature or heated.
[0016] There are no particular restrictions on the solvent of
component (B)as long as it will dissolve the above-mentioned
component (A) without modifying component (A). Examples of useful
solvents include toluene, xylene, and other aromatic solvents;
hexane, heptane, octane, and other aliphatic solvents; methyl ethyl
ketone, methyl isobutyl ketone, and other ketone-based solvents;
butyl acetate, isoamyl acetate, and other aliphatic ester-based
solvents; N,N'-dimethylformamide, N,N'-dimethylacetamide,
N-methyl-2-pyrollidinone, dimethyl sulfoxide, diethylene glycol
dimethyl ether, dibutyl ether, butyrolactone; hexamethyldisiloxane,
1,1,3,3-tetramethyldisiloxane, and other linear methylsiloxanes,
1,1,3,3,5,5,7,7-octamethyltetracyclosiloxane,
1,3,5,7-tetramethyltetracyclosiloxane, and other cyclic siloxanes;
and silicon-based solvents of silane compounds such as
tetramethylsilane and dimethyldiethylsilane. There are no
restrictions on the amount in which component (B) is contained in
the present composition, but it is general preferable for this
amount to be at least 50 weight parts per 100 weight parts of
component (A). This is because if the content of component (B) is
below the above range, it will tend to be difficult for the
resulting electrically insulating organic resin to be applied in a
thin coating over the surface of a substrate such as an electronic
device.
[0017] A hydrosilylation catalyst (C) may also be contained as an
optional component in the present composition. In particular when
(i) an electrically insulating organic resin having silicon
atom-bonded hydrogen atoms and (ii) an electrically insulating
organic resin having silicon atom-bonded alkenyl groups are used
together as the electrically insulating organic resin of component
(A), this catalyst will promote the hydrosilylation reaction of the
silicon atom-bonded hydrogen atoms in component (i) with the
alkenyl groups in component (ii). Examples of this hydrosilylation
catalyst of component (C) include platinum catalysts, rhodium
catalysts, and palladium catalysts, with a platinum catalyst being
particularly favorable. Examples of platinum catalysts include
chloroplatinic acid, an alcohol solution of chloroplatinic acid, an
olefin complex of platinum, an alkenylsiloxane complex of platinum,
and a carbonyl complex of platinum. There are no restrictions on
the amount in which component (C) is contained in the present
composition, as long as the amount is sufficient to promote the
above-mentioned reaction, but an amount such that the catalyst
metal in component (C) is between 1 and 1000 weight parts per
million weight parts of component (A) is preferred. A sensitizer
may also be added if the present composition is to be crosslinked
solely by irradiation with high-energy rays.
[0018] The method of the present invention for forming an
electrically insulating crosslinked thin film will now be described
in detail. The method of the present invention for forming an
electrically insulating crosslinked thin film is characterized in
that the surface of an electronic device is coated with the
above-mentioned electrically insulating crosslinkable
thin-film-forming organic resin composition, and all or part of the
solvent is evaporated, after which the electrically insulating
organic resin contained in the composition is crosslinked by
heating and/or irradiation with high-energy rays. In the present
method the first step is to coat the surface of an electronic
device with the above-mentioned electrically insulating
crosslinkable thin-film-forming organic resin composition. Examples
of coating methods include spin coating, dip coating, spray
coating, and flow coating. After coating, all or part of the
solvent is evaporated, and the surface is then subjected to heating
and/or irradiation with high-energy rays. When the resulting
electrically insulating thin film needs to be smooth, it is
preferable to heat it at a temperature higher than the melting
point of component (A). Examples of heating methods include the use
of a heating furnace or a hot plate. When irradiation with
high-energy rays is employed, examples of high-energy rays that can
be used include ultraviolet rays, infrared rays, X-rays, and an
electron beam, and the use of an electron beam is particularly
favorable because component (A) can be thoroughly crosslinked.
EXAMPLES
[0019] The electrically insulating crosslinkable thin-film-forming
organic resin composition and the method for forming an
electrically insulating crosslinked thin film of the present
invention will now be described in detail through examples. Me in
the formulas represents a methyl group and n is a positive integer
indicating the repeating units. The specific inductive capacity of
the electrically insulating crosslinked thin film was measured at a
temperature of 25.degree. C. and 1 MHz using a sample formed on a
silicon wafer with a resistivity of 10.sup.-2 .OMEGA..cndot. cm.
The measurement was performed using an impedance analyzer.
Reference Example 1.
[0020] 6.4 g Of pyromellitic dianhydride and 31.5 g of a mixture of
N,N'-dimethylacetamide and xylene (95:5 weight ratio) were put into
a four-neck flask equipped with an agitator, a dropping funnel, and
a thermometer, and were agitated under a nitrogen gas flow. 9.4 g
Of a diamino functional siloxane compound described by formula
5
[0021] and 31.5 g of a mixture of N,N'-dimethylacetamide and xylene
(95:5 weight ratio) were added dropwise through the dropping funnel
over a period of about 15 minutes, with the reaction temperature
varying between 26 and 33.degree. C.
[0022] The resulting mixture was then agitated for 3 hours at a
temperature between 25 and 33.degree. C. A Dean-Stark tube was then
attached and azeotropic dehydration was performned for 13 minutes
at 140 to 144.degree. C. After this, the mixture was cooled to room
temperature and filtered, yielding 64.6 g of a solution of the
silicone modified polyimide resin described by the following
formula 6
Reference Example 2.
[0023] 3.6 g Of pyromellitic dianhydride and 34.8 g of a mixture of
N,N'-dimethylacetamide and xylene (95:5 weight ratio) were put into
a four-neck flask equipped with an agitator, a dropping funnel, and
a thermometer, and were agitated under a nitrogen gas flow. 11.1 g
Of a diamino functional siloxane compound described by 7
[0024] and 34.8 g of a mixture of N,N'-dimethylacetamide and xylene
(95:5 weight ratio) were added dropwise through the dropping funnel
over a period of about 30 minutes, with the reaction temperature
varying between 29 and 37.degree. C.
[0025] The resulting mixture was then agitated for 3.5 hours at a
temperature between 26 and 37.degree. C. A Dean-Stark tube was then
attached and azeotropic dehydration was performed for 8 minutes at
144 to 146.degree. C. After this, the mixture was cooled to room
temperature and filtered, yielding 77.3 g of a solution of a
silicone modified polyimide resin described by formula 8
Reference Example 3.
[0026] 3.6 g Of pyromellitic dianhydride and 35.0 g of a mixture of
N,N'-dimethylacetamide and xylene (95:5 weight ratio) were put into
a four-neck flask equipped with an agitator, a dropping funnel, and
a thermometer, and were agitated under a nitrogen gas flow. 16.5 g
Of a diamino functional siloxane compound described by 9
[0027] and 34.8 g of a mixture of N,N'-dimethylacetamide and xylene
(95:5 weight ratio) were added dropwise through the dropping funnel
over a period of about 30 minutes, with the reaction temperature
varying between 29 and 37.degree. C.
[0028] The resulting mixture was then agitated for 3.5 hours at a
temperature between 26 and 37.degree. C. A Dean-Stark tube was then
attached and azeotropic dehydration was performed for 8 minutes at
144 to 146.degree. C. After this, the mixture was cooled to room
temperature and filtered, yielding 81 g of a solution of the
silicone modified polyimide resin described by formula 10
Example 1.
[0029] An electrically insulating crosslinkable thin-film-forming
resin composition was prepared from 50 g of a solution of the
silicone modified polyimide resin prepared in Reference Example 2,
50 g of the silicone modified polyimide resin prepared in Reference
Example 3, and a 1,3-divinyltetramethylsiloxane complex of
chloroplatinic acid (in an amount such that there was 5 ppm (by
weight) platinum metal with respect to the overall reaction
mixture). This composition was applied on a silicon wafer by spin
coating at a speed of 3000 rpm, the solvent was evaporated off, and
the wafer was heated for 1 minute on a 150.degree. C. hot plate.
The coated wafer was then heated for 3 hours in a quartz furnace
(360.degree. C.) under a nitrogen gas flow, forming an electrically
insulating crosslinked thin film with a thickness of 520 nm and a
specific inductive capacity of 2.4. The resulting electrically
insulating crosslinked thin film was subjected to an annealing test
for 1 hour in a quartz furnace (420.degree. C.) under a nitrogen
gas flow. Table 1 shows the film thickness before and after the
annealing.
Example 2.
[0030] A solution of the silicone modified polyimide resin prepared
in Reference Example 2 was applied on a silicon wafer by spin
coating at a speed of 3000 rpm and the solvent was evaporated off,
after which the coating was irradiated with an electron beam (300
Mrad) accelerated with 165 kV and then heated for 3 hours in a
quartz furnace (360.degree. C.) under a nitrogen gas flow, forming
an electrically insulating crosslinked thin film with a thickness
of 510 nm and a specific inductive capacity of 2.4. This thin film
adhered well to the silicon wafer. The resulting electrically
insulating crosslinked thin film was subjected to an annealing test
for 1 hour in a quartz furnace (420.degree. C.) under a nitrogen
gas flow. Table 1 shows the film thickness before and after the
annealing.
Example 3.
[0031] A solution of the silicone modified polyimide resin prepared
in Reference Example 3 was applied to a silicon wafer by spin
coating at a speed of 3000 rpm and the solvent was evaporated off,
after which the coating was irradiated with an electron beam (300
Mrad) accelerated with 165 kV and then heated for 3 hours in a
quartz furnace (360.degree. C.) under a nitrogen gas flow, forming
an electrically insulating crosslinked thin film with a thickness
of 510 nm and a specific inductive capacity of 2.4. This thin film
adhered well to the silicon wafer. The resulting electrically
insulating crosslinked thin film was subjected to an annealing test
for 1 hour in a quartz furnace (420.degree. C.) under a nitrogen
gas flow. Table 1 shows the film thickness before and after the
annealing.
Comparative Example 1.
[0032] A solution of the silicone modified polyimide resin prepared
in Reference Example 1 was applied to a silicon wafer by spin
coating at a speed of 3000 rpm and the solvent was evaporated off,
after which wafer was heated for 3 hours in a quartz furnace
(360.degree. C.) under a nitrogen gas flow, forming an electrically
insulating crosslinked thin film with a thickness of 500 nm and a
specific inductive capacity of 2.4. The resulting electrically
insulating crosslinked thin film was subjected to an annealing test
for 1 hour in a quartz furnace (420.degree. C.) under a nitrogen
gas flow. Table 1 shows the film thickness before and after the
annealing. A reduction in the film thickness after annealing was
observed.
1 TABLE 1 Comparative Example 1 Example 2 Example 3 Ex. 1 Film
thickness before 520 510 510 500 annealing (nm) Film thickness
after 520 510 510 330 annealing (nm)
* * * * *