Note: Descriptions are shown in the official language in which they were submitted.
-
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The present invention relates to a sensitizer for a ;f
cinnamic acid type photosensitive resin, and a photosensitive
composition thereof.
Various polymers having a cinnamic acid radical prepared ~ -
` by polymer reactions of cinnamic acid or a derivative thereo~ `~with polymers have been prpposed for use as photosensitive resins
in various fields. In general, these photosensitive polymers have
low photosensitivity. Accordingly, it is necessary to improve
the photosensitivity by adding of lower molecular weight compound
as a sensitizerO
Recently, various requirements of sensitivity improvement ~`
have been requested from the viewpoint of severe precesion require- ~ `
ments and high grade in the applications of the cinnamic acid
type photosensitive resins. It is thus not enough to provide
spectral sensitization ie.to expand sensitive wavelength, but it
~` has become desirable to improve sensitivity at specific wavelength. `~
For example, photoresists used for preparation of IC, LSI and a
ma~k in the semlconductor field, has been exposed by a projection
printing system. In the system, it is general to employ g-line
20 (4358 A) because of optical aberration. Accordingly, in the ;~
system, increas~ sensitiv~ty to g-line is required. It has been
difficult to provide -~ sùfficient increase of sensitivity using
known sensitizers. It has now been found that a halogen sub~
: ? ~
stituted benzanthrone in which the hydrogen atom of benzanthrone
is substituted for haloge~ atom imparts excellent sensitization
`~ of the cinnamic acid type photosensitive resins especially under
~ .
the exposure of g-line.
The present invention thus provides a sensi~izer for a ;~
` cinnamic acid type photosensitive resin especially under the `~
exposure of g-line.
, ~
The pres-ent invention also provides photosensitive compo-
sition which has high sensitivity to g-line and com~rises a
~S;~ ;4
cinnamic acid type photosensitive resin and sensitizer of a
halogen-substituted benzanthrone.
The sensitizers of the invention are benzanthrone deriv-
atives substituted for one or more halogen a~om such as chlorine,
bromine or iodine atom.
l ~ benzanthrone
The typical benzanthrone derivatives include monohaloben~
~anthrones such as 3-chlorobenzanthrone, ~-bromobenzanthrone, 5-
iodobenzanthrone, 9-chlorobenzanthrone and lO~bromobenzanthrone;
~nd dihalobenzanthrones such as 3,4-dichlorobenzanthrone, 6,11-
dichlorobenzanthrone~ 6,10-dibromobenzanthrone, 5,9-dibromoben-
; zanthrone and 8,11-diiodobenzanthrone. Benzanthrones having more
halogen atoms substituted therefor are also useful as sensitizers~
The cinnamic acid type photosensitive polymers which is
combined with the sensitizer of the invention are polymers con-
taining cinnamic acid group or a derivative thereof.
The typical photosensitive polymers have the following
units in the molecule ~
R' ` `
~ CH2 f -
R ICl - (XC = CY)n-Ar ~
';
or -~
-2- `
: !
- CH2 - CH - 0 -
R - C - (XC = CY)n - Ar
O ~:
wherein R represents oxygen atom or hydrocarbon moiety which may
contain oxygen or sulfur atom; R' represents hydrogen atom or a
lower alkyl group, X and Y are same or different and represent
hydrogen atoma a halogen atom, cyano group or nitro group; Ar
represents an aryl group which may be substituted; and n is 1 or
: 10 2~
Suitable photosensitive polymers can be vinyl polymers
prepared by reacting cinnamic acid or a derivative thereof with
: polymers containing hydroxy, chloromethyl or acetyl group, such .
clS polyvinyl cinnamate, poly(vinyl m-nitro-cinnamate), poly(vinyl
a-cyanocinnamate), poly(vinyl.~-nitro-cinnamate), poly(vinyl~
; nitroecinnamate), poly(vinyl~-chloro-cinnamate), poly(vinyl~
chloro-cinnamate), poly(vinyl cinnamylidene acetate), polyvinyl- :~
. oxyethyl cinnamate, polyvinylthioethyl cinnamate, poly(2-cinna~
: moyloxyethyl acrylate), poly(2-cinnamoyloxyethyl methacrylate),
20 poly(vinyl ~innamoyloxyacetate), poly(p-cinnamoyloxyvinylbenzene), ;~
::~ poly(p-cinnamoylstyrene), and the like or copolymers of the monomer
and another comm~omer and oxirane ring opening polymers such as - j.
polyglycidyl cinnamate, poly(glycidyl p-nitrocinnamate), poly(gly- ; .
cidyl~-cyanocinnamate), poly(glycidyl cinnamylidene acetate3 and -~
the like. Suitable polymers containing photosensitive groups whole
. or in pa~-t which are produced by reacting a polymer containing
. haloalkyl groups as side chains with a salt of a carboxylic acid `.
,;, ~ :
: containing photosensitive groups in a dipolar aprotic solvent can ~`. .` ~
; also be used. s. ;~:.
.~ -
For example, the polymers can be produced by reacting .
polychloroethylvinyl ether, polyvinyl chloroacetate, poly(~
. chloroethyl acrylate), polyepichlorohydrin, or polyepibromohydrin
:~ _3~
i , - -:. . .:
~ . ... . . . . . . . ... ..... . . . . .. .. . . ... . . .
~ 05 ~6 ~
with cinnamic acid or a derivative thereoE. Suitable polymers
can also be prepared by catiomic pol~nerization of vinylethers
~ such as poly(vinyloxy ethyl cinnamate) and the like. The
- quantity of the sensitizer in the photosensitive co~position of
the invention is not limited and is preferably ~.01 - 10% by
weight to the cinnamic acid type photosensitive polymer.
The photosensitive resin and the sensitizer are used by
dissolving them in a solvent. The solvents can be conventional
solvents e.g. acetone, toluene, xylene, and methylcellosolve ace-
tate. The solvents also include chlorobenzene, bromobenæene and
4-methoxy-4-methylpentanone-2. It is possible to add to the
photosensitive composition conventional sensitizers such as
aromatic nitro compounds, ketones. Stabilizers such as hydro-
quinone and tert-butyl catechol plasticizers such as triacetin
and triethyleneglycol dipropionate. ~yestuffs or pigments can
also be effectively added to the compositions. The sensitizer
of the invention improves the sensitivity of the cinnamic acid
type photosensitive polymers especially their sensi~ivity under
exposure of g-line which can be remarkably improved.
The present invention will be further illustrated by way
of the following Examples and Preparations.
Preparation 1 Cinnamic acid type photosensitive pol~mer
., :.
10 g of polyepichlorohydrin having a reduced specific
~iscosity ~ SP/C = 0O97 (0.2 g/dl benzene sol. at 30C) was dis-
solved in 342 ml of dimethylformamide and 20.8 ~ of cinnamic ~
acid and 21.4 g of 1,8-diazabicyclo[5,4,0]undecene-7 w2re added. ~ -
homogenuous solution was formed. The reaction was conducted at
85C for 9 hours with stirring in an argon atmosphere. The
reaction mixture was then poured into about 1.5 1 of methanol to
precipitate the white rubber-like polymer.
The resulting polymer has the units of the following
-4- !''' ~
.~
~ 5~ 6
formula
CH2 - CH - 0~ CH ~ CH - 0-~------
0.552 0.~5 ~;
CH2 Cl . . ,
H2 ~ ~ C - CH = CH
Preparation 2 Sensitizer
9.7 g of 1,5-dichloroanthraquinone was dissolved in 75.5
ml of conc. sulfuric acid. 5.5 ml of water was added dropwise
to the solution. 4.8 g of copper powder was added to it during -
1 hour and the mixture was stirred at ~0C for 2.5 hours. A
- mixture of 9.6 g of glycerine and 9.6 ml of water was added to ~ ~
` the mixture to raise the temperature to 75C. The mixture was `~ ~ ;; urther heated to 110C at a rate of 1C per 3 minutes and the ` -~; reaction was conducted at 110C for 1.5 hours. 400 ml of the `;~
reaction mixture was poured into water to obtain yellowish green
powder. The product was recrystalliæed from o-dichlorobenzene ~ ~
and chlorobenzene to obtain yellow needle crystal (mp l~tOC). ~-
~,
According to the analysis, it was 6,11-dichlorobenzanthrone.
Preparation 3 Sensitizer ;~
Monochlorobenzanthrone was prepared from 2-chloroanthra~
quinone in accordance with Preparation 2.
Pr~paration 4 Sensitiz~r
10 g of benzanthrone was dissolved in a solvent mixture
of 100 g of acetic acid and 100 g of water. 6 g of potassium ~ -
chlorate was added to the solution and the mixture was heated
i and stirred at 90 - 95C for 2 hours. 12 g of conc. hy,drochloric ` (~ ;
~` acid was added dropwise to the mixture during 1 hour 20 minutes.
i 30 Ater ~he addition, the mixture was stirred for 1 hour to cause
re~a~o`~ The ~e'actlon` mixtur~i-w~s cctoled ànd ~ tere-d~`an`d ~as~ed ~-
with water and dried. The product was then ~ecrystallized from
.:
; ~-
:
~ 6 4
chlorobenzene to obtain 3-chlorobenzanthrone having melting
point of 179 - 190C (orange needle crystal). ;~
'' ~e~ .. - .,
A 8.5 g of the photosensitive polymer prepared as des- ~
cribed in Preparation 1 was dissolved in 100 ml of 4-methoxy-4- ~ -
methylpentanone-2. ~-
A 0.8 g of 6,11-dichlorobenzanthrone prepared as des-
cribed in Preparation 2 was added to the solution to prepare a
photosensitive solution. The photosensitive solution was coated
with a spinner on a glass plate coated with vapor deposited chrom-
ium (50 x 50 mm). The coated plate was prebaked at 80C for 15
minutes. The coated plate was contacted with the Steps tablet
.. ..
No. 2(Kodak Co.) and was exposed for 10 seconds at a 30 cm dis~
i; itance from the source of a high pressure mercury lamp (manufac- ;
, ..................................................................... . . .
' tured by Ushio Denki K.K. under the trademark of Unipalse 3 KW),
by g-line passed through a colour glass filter (manufactured by
Toshiba K.K~ under the trademark of V-Y43 and VClA). A solvent
''! mixture of xylene and cyclohexanone (2 : 1 by volume) was sprayed
I on the exposed coated plàte as a developing solution. The rela~
;, ... .
ti~e sensitivity (S) was calculated by the following equation (1) `
from the insolubilized steps.
` k antilog D
S = ~ ......................... (1) j: ,;
I . t
., o
. .; ~
~ wherein the constant k was given so as to be 100 of the relative
;~' sensitivity S of benzanthrone, and D designates optical density ;~ ~
of step tablets for insoIubilized limit steps; and t designates r ,:~.
exposure time (seconds); Io designates optical intensity (relative ~ ~
. ~
value) on the surface of the sample. The relative sensitivity S
of the sample was 280.
. .
, ~; '
-
~s~
Example 2
In accordance with Example 1, 0.7 g of monochlorobenzan-
throne prepared as described in Preparation 3 was used as the
sensitizer, and ~he relative sensitivity S of the sample was
measured to give 140.
Example 3
In accordance with Example 1, 0.7 g of 3-chlorobenzan-
throne prepared as described in Preparation 4 was u~ed as the
sensitizer, and the relative sensitivity S of the sample was
measured to give 140. The relative sensitivities of the samples --
~.
using the known sensitizers of benzanthrone, 5-nitroacenaphthene
and 1,2-benzanthraquino~e and the sensitizers of the invention.
Table 1 -
: - -- -: ~ - ~
Sensitizer Relative sensitizer
6,11-dichlorobenzanthrone 280
monochlorobenzanthrone 140
3-chlorobenzanthrone 140
benzanthrone 100 ~ `~
5-nitroacenaphthene 40
1,2-benzanthraquinone 25
,~ :
Example 4
The photosensitive solution pre~ared as described in
Example 1 was coated with a spinner (3000 rpm) on a silicon wafer ;
covered with an oxidized membrane of 1~. The coated silicon
wafer was exposed for 3 minutes by g-line passed through a mask
for preparation of an integrated circuit by projection type ~
printer (Canon K.K. PPC 210). The exposed sample was developed
with a solvent mixture of xylene and cyclohexanone (2 : 1 by
volume), and then it was post-baked at 170C for 20 minutes.
~
!
.. . . . . .. , . ~ . . ~ ..
~L05~64
,
The resulting sample was treated with a fluoric acid type etching
solution at 25C for 6 minutes to obtain a sharp pattern.
Example 5
The photosensitive solution prepared as described in
Example 1 was coated with a spinner on a smooth glass plate coated -
with vapor deposited chromium (50 x 50 mm). The coated plate was
prebaked at 70C for 20 minutes. The coated plate was exposed
,
by the projection type printer to print fine pattern having lines ;
of 1 - 50~u~ A solvent mix~ure of xylene and cyclohexanone (2 ~
0 1 by volume) was applied on the exposed coated plate as a devel-
oping solution. Then, it was post-baked at 170C for 20 min~tes. -
. ,
The resulting plate was etched with an ammonium ceric nitrateper-
`~ chloric acid type etching solution at 21C for 60 seconds to
~ obtain a sharp pattern. ~he product can be used as a hard mask
.,, , . ~
l for preparation of semiconductor. ~ ~
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