Pattern forming contrast enhanced material utilizing water soluble photosensitive diazo compound and pattern forming method

Disclosed is a pattern forming contrast enhanced material comprising (a) a water soluble photosensitive compound selected from the group consisting of a water soluble aliphatic photosensitive compound (excluding ring compounds) having one or more of the group expressed by the formula (I), an aliphatic photosensitive quaternary ammonium salt having one or more of the group expressed by the formula (I), an aromatic photosensitive quaternary ammonium salt having one or more of the group expressed by the formula (I), and a photosensitive pyridinium salt having one or more of the group expressed by the formula (I), (b) a water soluble resin and (c) water and a pattern forming method using the same. ##STR1## According to the present invention, this material is used as a contrast enhanced layer in the exposure effected by deep ultraviolet ray such as an excimer laser beam to form a good fine pattern of a submicron order.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
The present invention relates to a pattern forming contrast enhanced 
material. The present invention also relates to a pattern forming method. 
More specifically, the present invention relates to a pattern forming 
method using a contrast enhanced material having such properties that the 
material has a low primary transmittance to deep ultraviolet ray such as 
KrF excimer laser and the like, a bleaching action to these rays and an 
increased transmittance after the perfect bleaching. 
2. Description of Related Art 
The progress of the high density integration of a semiconductor integrated 
circuit has been carried out together with a conventional lithography 
technology and the smallest line width thereof is dashing in a region of 
submicron. The resolution R of lithography by a reduction projection 
method is expressed by the following Rayleigh's equation: 
EQU R=k.sub.1 x .lambda./NA (1) 
where 
k.sub.1 : process coefficient 
.lambda.: wavelength 
NA: numerical aperture of lens 
From the above equation, a critical resolution is 0.68 .mu.m and 
insufficient for submicron lithography, when using g-line (0.436 .mu.m) 
and a stepper of NA of 0.45 and k.sub.1 being 0.7. 
Griffing et al. reported that by laminating a contrast enhanced layer for 
improving the contrast of the optical strength profile on the resist for 
pattern forming, a process coefficient k.sub.1 can be decreased and a 
resolution and pattern profile can be improved (B. F. Griffing et al., 
IEEE ELECTRON DEVICE LETTERS, Vol. EDL-4, No. 1, Jan., pages 14-16 (1983). 
According to their report, a resolution of 0.4 .mu.m is possible in the 
ordinary reduction projecting method (.lambda.: 0.436 .mu.m, NA: 0.32). 
Sasago et al. have found that the contrast enhanced material of Griffing et 
al. requires the formation of a water soluble interlayer thin film on a 
resist and hence not suitable for practical processes, since it contains 
an organic solvent, and reported a water soluble contrast enhanced 
material consisting of a water soluble resin and water soluble 
photosensitive compound (a diazonium salt) (M. Sasago et al., 1985 
SYMPOSIUM ON VLST TECHNOLOGY, Digest of Technical Papers, pages 76-77 
(1985). 
This water soluble contrast enhanced material is bleached in a wavelength 
range of 365-406 nm by exposure. Also, since it is water soluble, it can 
be directly applied on a resist film without being mixed with the resist. 
On the other hand, in order to reduce a wavelength of light source, a 
pattern forming method using KrF excimer laser beam of a wavelength of 248 
nm is proposed. The wavelength can be reduced about by 40% by using KrF 
excimer laser instead of g-line. Therefore considering the above equation 
(1), it is expected that the resolution can be improved thereby. 
Endo et al. reported the use of a compound having 
##STR2## 
group in its molecule as a photosensitive compound in a pattern forming 
material for deep ultraviolet ray (M. Endo et al., Technical Papers in 
Regional Technical Conference on Photopolymers Principles Processes and 
Materials, Oct. 30-Nov. 2, pages 39-50 (1988). Since transmittance 
relatively greatly changes due to exposure to KrF excimer laser beam in 
this pattern forming material, it is expected to decrease a process 
coefficient. However, the change of transmittance is still insufficient 
for improving contrast and hence not always provide a good result. Also, 
since the pattern forming material is not water soluble, it is difficult 
to apply it to practical processes in the same way as the contrast 
enhanced material of Griffing et al. which requires the formation of a 
water soluble interlayer thin film. 
Endo et al. also reported an excimer laser lithography using a water 
soluble contrast enhanced material (U.S. patent application Ser. No. 
372,227). The contrast enhanced material in this report consists of a 
photosensitive compound having 
##STR3## 
group in its molecule and a water soluble polymer. A --SO.sub.3 H group 
attached to an aromatic ring is selected as a water soluble group of the 
photosensitive compound. However, the --SO.sub.3 H group alone cannot 
provide an aromatic photosensitive compound having 
##STR4## 
group in its molecule with enough water solubility. Therefore, it is 
difficult to dissolve the compound in pure water so that the primary 
transmittance may become sufficiently low and hence a good pattern 
formation is not expected. 
Thus, there has been expected the lithography technology using a water 
soluble contrast enhanced material capable of decreasing a process 
coefficient and utilizing deep ultraviolet ray such as KrF excimer laser 
beam and the like. 
SUMMARY OF THE INVENTION 
The present inventors have found that the above problems can be solved by 
using a pattern forming contrast enhanced material comprising (a) a water 
soluble photosensitive compound selected from the group consisting of a 
water soluble aliphatic photosensitive compound (excluding ring compounds) 
having one or more of the group expressed by the following formula (I), an 
aliphatic photosensitive quaternary ammonium salt having one or more of 
the group expressed by the formula (I), an aromatic photosensitive 
quaternary ammonium salt having one or more of the group expressed by the 
formula (I), and a photosensitive pyridinium salt having one or more of 
the group expressed by the formula (I), (b) a water soluble resin and (c) 
water: 
##STR5## 
The present invention relates to a pattern forming contrast enhanced 
material comprising (a) a water soluble photosensitive compound selected 
from the group consisting of a water soluble aliphatic photosensitive 
compound (excluding ring compounds) having one or more of the group 
expressed by the formula (I), an aliphatic photosensitive quaternary 
ammonium salt having one or more of the group expressed by the formula 
(I), an aromatic photosensitive quaternary ammonium salt having one or 
more of the group expressed by the formula (I), and a photosensitive 
pyridinium salt having one or more of the group expressed by the formula 
(I), (b) a water soluble resin and (c) water. 
Further, the present invention relates to a method of forming a pattern 
comprising (i) applying a pattern forming material on a substrate, (ii) 
forming a film of a pattern forming contrast enhanced material comprising 
(a) a water soluble photosensitive compound selected from the group 
consisting of a water soluble aliphatic photosensitive compound (excluding 
ring compounds) having one or more of the group expressed by the formula 
(I), an aliphatic photosensitive quaternary ammonium salt having one or 
more of the group expressed by the formula (I), an aromatic photosensitive 
quaternary ammonium salt having one or more of the group expressed by the 
formula (I), and a pyridinium salt having one or more of the group 
expressed by the formula (I), (b) a water soluble resin and (c) water, 
(iii) effecting exposure using a KrF excimer laser beam and (iv) effecting 
development. 
##STR6## 
An object of the present invention is to provide a pattern forming contrast 
enhanced material having a contrast effect to deep ultraviolet ray, in 
particular, to an excimer laser beam of 248 nm and a pattern forming 
method using this material. 
Other objects and advantages of the present invention will be apparent from 
the following description when considered in connection with the 
accompanying drawings.

PREFERRED EMBODIMENTS OF THE INVENTION 
A contrast enhanced material according to the present invention must be 
provided with the conditions that a resin to be used has less absorption 
around 248 nm, a photosensitive compound to be used has a transmittance 
around 248 nm which greatly increases after exposure, the material can be 
solved in aqueous solvent (e.g., an alkaline solution or the like as a 
developer for a resist) regardless of an optical reaction, and a solvent 
to be used has no absorption around 248 nm. 
The inventors selected water soluble resins as the resins satisfying these 
requirements. The water soluble resins used in the present invention 
include pullulan, polyvinyl alcohol, polyvinyl pyrrolidone, polyethylene 
glycol, polyethylene oxide, water soluble cellulose derivatives such as 
sodium carboxymethyl cellulose, methyl cellulose, hydroxyethyl cellulose, 
hydroxypropyl cellulose, hydroxypropyl methyl cellulose and the like. They 
may be used independently or in the combination composed of two or more 
kinds thereof. 
Note that although the above water soluble resins generally exhibit a 
transmittance of about ten percent at 248 nm when they are a thick film of 
1.0 .mu.m or more, they have a transmittance of several tens percent at 
248 nm when they are a thin film of 0.5 .mu.m or less. Therefore, when the 
contrast enhanced material according to the present invention is applied 
to a thickness of 0.5 .mu.m on a resist for forming a pattern, a contrast 
enhanced effect can be obtained without causing any problem. In addition, 
these water soluble resins have an advantage to enable an N.sub.2 gas to 
easily pass from an underlayer therethrough. 
A compound having 
##STR7## 
group is selected as a photosensitive compound in order to increase a 
ratio of a transmittance at around 248 nm before exposure to that after 
exposure. 
More specifically, the compound having 
##STR8## 
group has large absorption around 248 nm before exposure and almost no 
absorption around 248 nm due to the reaction of: 
##STR9## 
Water soluble aliphatic photosensitive compounds having one or more of 
##STR10## 
group used in this invention include the compounds having a hydrophilic 
group such as --OH group, --SO.sub.3 H group (which may be in the form of 
such as Na salt, K salt, NH.sub.4 salt, etc.), --COOH group (which may be 
in the form of Na salt, K salt, NH.sub.4 salt, etc.), an amino group, a 
substituted amino group, etc. or compounds which are in the form of 
quaternary ammonium salt or pyridinium salt by themselves. Substituted 
groups of the above substituted amino group includes methyl group, ethyl 
group, hydroxyethyl group or sulfopropyl group. Note that the two 
hydrogens of the amino group can be independently substituted by any of 
the above substituted groups, respectively. 
Further, the following compounds, etc., for example, can be sufficiently 
used as the water soluble photosensitive compound in this invention since 
they are water soluble, although they do not particularly have the 
hydrophilic group or the hydrophilic bond. 
##STR11## 
Incidentally, when the water soluble aliphatic photosensitive compound is 
in the form of quaternary ammonium salt or pyridinium salt, the aliphatic 
photosensitive compound itself may be water-insoluble. 
Note that if a benzene ring exists in the molecule, the absorption effected 
by the benzene ring around 250 nm lowers a transmittance after exposure 
and a sufficient bleaching action is difficult to be obtained. 
Consequently, it is preferable that the pattern forming contrast enhanced 
material according to the present invention does not contain the benzene 
ring. 0n the other hand, a substituted phenyl group, a naphthyl group, a 
substituted naphthyl group or a pyridyl group has an absorption peak in a 
range of about 280 nm to 350 nm and thus has a less effect for the 
improvement of transmittance after exposure. Therefore, an aromatic 
Photosensitive compound having both a group mentioned above and one or 
more of the group expressed by the formula (I) can be used in the present 
invention if it has high solubility to water. 
Then the inventors have selected the quaternary ammonium salt of the 
aromatic photosensitive compound and the pyridinium salt of the aromatic 
photosensitive compound as a compound having high solubility. 
Substituted groups of the phenyl group and the naphthyl group include alkyl 
group having 1-10 carbon atoms such as methyl group, ethyl group, propyl 
group, a butyl group, etc., alkoxy group having 1-5 carbon atoms such as 
methoxy group, ethoxy group, propoxy group, butoxy group, etc., OH group, 
carboxyl group, sulfonic acid group, amino group, substituted amino 
groups, etc. Substituents of the substituted amino groups are the same as 
mentioned above. 
The photosensitive compound used in the contrast enhanced material 
according to the present invention is generally produced by the following 
method. 
##STR12## 
More specifically, when a compound having a group expressed by 
##STR13## 
hereinafter, referred to as compound A) is diazotized, a compound having 
the 
##STR14## 
group can be easily obtained. In addition, when the obtained compound has 
a terminal amino or pyridyl group, it is treated by acid such as, for 
example, p-toluenesulfonic acid, methane sulfonic acid, etc. according to 
a common method to quantitatively obtain the quaternary ammonium salt or 
the pyridinium salt having the 
##STR15## 
group. 
A diazotizing reaction is usually carried out in such a manner that the 
compound A, 0.5 to 3 moles, preferably 0.8 to 1.5 moles per mole of the 
compound A of a diazotizing agent and 0.5 to 5 moles, preferably 0.8 to 
1.5 moles per mole of the compound A of a base are reacted in a suitable 
reaction solvent at a temperature of -10.degree. to 30.degree. C., 
preferably -5.degree. to 10.degree. C. for 15 min. to 5 hours, preferably 
1 to 2 hours. 
As a reaction solvent used in the diazotizing reaction there can be used an 
alcohol such as ethanol, isopropanol, etc.; ether such as ethyl ether, 
isopropyl ether, tetrahydrofuran, etc.; a halogenated hydrocarbon such as 
methylene chloride, chloroform, carbon tetrachloride, 1,2-dichloroethane, 
etc.; a hydrocarbon such as n-hexane, cyclohexane, toluene, etc. As a 
diazotizing agent, there can be used p-toluenesulfonylazide, 
benzenesulfonylazide, 2-azide-3-ethylbenzothiazolium fluoroborate, etc., 
and as a base, there can be used an organic base such as piperidine, 
triethylamine, N-methylpyrrolidine, N-methylmorpholine, pyridine, 
diethylamine, etc.; an alcoholate such as NaOCH.sub.3, NaOC.sub.2 H.sub.5, 
KOC(CH.sub.3).sub.3, KOC.sub.2 H.sub.5, etc.; and metal sodium, sodium 
hydride, potassium hydride, etc. 
Since the methods of synthesizing the compound A are different depending on 
the kind of R when it is expressed by the formula: 
##STR16## 
the compound A can be suitably synthesized by a synthesizing method 
corresponding to the kind of R. In addition, the compound A is 
commercially available depending on the kind of R and thus in this case it 
can be used as it is or after it is suitably refined. 
A synthesizing method of some of the concrete compounds will be briefly 
described below. 
##STR17## 
The pattern forming contrast enhanced material according to the present 
invention is produced in such a manner that 0.5 part by weight or more, 
preferably 1-3 parts by weight of a photosensitive material and 1 part of 
a water soluble resin are mixed with water and made to a solution having a 
concentration of 5-50% by weight. 
Next, a pattern forming method using the pattern forming contrast enhanced 
material according to the present invention will be described with 
reference to FIG. 1. 
More specifically, for example, a suitable positive resist material 2 
[e.g., MP2400 (made by Shipley Co., Inc.)] is spin-coated on a substrate 1 
such as a silicon wafer and prebaked in an oven at 70.degree. to 
110.degree. C. for 10 to 30 min. or on a hot plate at 
70.degree.-110.degree. C. for 1-2 min. to obtain a resist film having a 
thickness of 0.5 to 2 .mu.m [FIG. 1 (a)]. Note that the substrate 1 often 
has an oxide film, insulating film or conductive film formed thereon. 
Next, a contrast enhanced material 3 according to the present invention is 
spin-coated on the prebaked resist film 2 to a thickness of about 0.1-0.5 
.mu.m [FIG. 1 (b)]. Then, a mask 6 for obtaining a target pattern is held 
on the above resist film and a selective pattern exposure is effected by 
applying an excimer laser beam 4 of 248.4 nm having an exposure dose which 
is about 1.5 times that used when a pattern is formed using only an 
underlayer resist [FIG. 1 (c)]. Finally, it is developed for about 0.5-3 
min. using a developer such as a water solution containing 20% of a 2401 
developer (made by Shipley Co., Inc.) by a common method such as a dipping 
method, puddle method, spray method or the like with the result that the 
pattern forming contrast enhanced material layer 3 and the exposed portion 
of the pattern forming material 2 are solved and removed and thus the 
target pattern is formed on the substrate [FIG. 1 (d)]. 
FIG. 4 describes a method of forming a pattern by an excimer laser exposure 
using the conventional contrast enhanced material, wherein a resist 2 is 
spin-coated on a substrate 1 [FIG. 4 (a)]; a water soluble contrast 
enhanced layer 5 is formed by spin-coating on the resist 2 [FIG. 4 (b)]; 
and then an excimer laser beam 4 is selectively applied through a mask 6 
by a reduced projection method [FIG. 4 (c)]. At the time, not only the 
contrast enhanced layer 5 but also a portion of the resist 2 are 
selectively irradiated. Finally, a usual developing process is carried out 
to remove the water soluble contrast enhanced layer 5 as well as only the 
portion of the resist 2 where the laser beam is applied whereby a pattern 
2b is formed [FIG. 4 (d)]. 
Note that the positive resist materials include, for example, alkali 
soluble resins having good photo transmittance in the vicinity of 248.4 nm 
such as p-cresol novolac resins, m-cresol novolac resins, 
o-chloro-m-cresol novolac resins, maleimide resins, hydroxystyrene resins, 
poly(p-vinylphenol) resins, phenol resins, styrene resins, maleic acid 
resins, etc. 
Further, the above resist material is usually used by being dissolved in an 
organic solvent. The organic solvents used for this object include, for 
example, diethylene glycol dimethylether, diethylene glycol diethylether, 
ethylcellosolve acetate, methylcellosolve acetate, etc. Said organic 
solvents, however, are not limited to them, but any solvent capable of 
dissolving a photosensitive compound and resin may be used. 
In addition, it suffices to select as a developer used in the above pattern 
forming method an alkaline solution having a suitable concentration which 
does not almost dissolve an unexposed portion but dissolve an exposed 
portion in accordance with the solubility of the resin used as the resist 
material in the alkaline solution, and the concentration is usually 
selected from a range of 0.01 to 50%. The alkaline solutions used include 
solutions each containing an organic amine such as tetramethyl ammonium 
hydroxide (TMAH), etc. and inorganic alkali such as NaOH, KOH, etc. 
The present invention will be described below more specifically referring 
to the following Examples. However, the present invention should not be 
construed to be restricted to the Examples. 
Referential Example 1 
Synthesis of 3,8-bis-diazo-2,4,7,9-decanetetraone 
(1) Synthesis of 2,4,7,9-decanetetraone 
To a suspension of sodium hydride (60% in oil, 15 g) in dry tetrahydrofuran 
(200 ml), a solution of 2,4-pentanedione (37.5 g, 0.375 mol) in dry 
tetrahydrofuran (100 ml) was added dropwise of -5.degree..about.0.degree. 
C. with stirring under nitrogen, and the resultant mixture was stirred for 
20 min. at the same temperature. To this suspension, n-butyllithium (1.6M 
in n-hexane solution, 250 ml) was added dropwise at the same temperature, 
followed by the addition of cuprous chloride (5.63 g) at -10.degree. C. or 
lower and the resultant mixture was stirred for 45 min. at 
-5.degree..about.0.degree. C. Then to this suspension, iodine (47.6 g, 
0.19 mol) in ethyl ether (250 ml) was added dropwise at 
0.degree..about.5.degree. C., stirring was continued for 7 hrs. at room 
temperature and the resultant mixture was allowed to stand for overnight. 
The reaction mixture was poured into dilute hydrochloric acid, subjected 
to extraction with ethyl acetate, the organic layer was washed with 
H.sub.2 O (200 ml.times.3), dried over anhydrous MgSO.sub.4 and evaporated 
in vacuo. The resultant residue (22.5 g) was chromatographed on silica gel 
(Wako Gel C-200, manufactured by Wako Pure Chemical Industries, Ltd.) 
with dichloromethane as eluent, followed by recrystallization from 
cyclohexane to give the title compound as yellow leaflets which was an ca 
1:1 mixture of Keto/Enol as seen by the methylene singlet at .delta.3.64 
ppm and the methine singlet at .delta.5.53 ppm in a .sup.1 HNMR spectrum; 
yield: 8.2 g; mp 62.7.degree..about.64.degree. C. 
##STR18## 
(2) Synthesis of 3,8-bis-diazo-2,4,7,9-decanetetraone 
To a solution of 2,4,7,9-decanetetraone (7.9 g, 40 mmol) obtained in the 
above process (1) and piperidine (6.9 g, 80 mmol) in chloroform (200 ml), 
p-toluenesulfonylazide (15.8 g, 80 mmol) in chloroform (50 ml) was added 
dropwise at 3020 .about.35.degree. C., and stirring was continued for 2 
hrs. at the same temperature. The reaction mixture was concentrated and 
the resultant residue was chromatographed on silica gel (Wako Gel C-200) 
with dichloromethane/ethyl acetate (10:1) as eluent to give the title 
compound as a yellow crystals; yield: 2.5 g; mp 
79.degree..about.82.5.degree. C. 
______________________________________ 
.sup.1 HNMR .delta.ppm(CDCl.sub.3): 
##STR19## 
##STR20## 
IR(KBr).nu.cm.sup.-1 : 
##STR21## 
UV(CH.sub.3 CN).lambda.maxnm(.epsilon.): 
229.9(35400). 
Anal. calcd. for C.sub.10 H.sub.10 N.sub.4 O.sub.4 : 
C %, 48.00; H %, 4.03; 
N %, 22.39. 
Found: C %, 48.30; H %, 3.97; 
N % 22.33. 
______________________________________ 
Referential Example 2 
Synthesis of 2-diazo-3-oxo-N,N-diethylbutyramide 
(1) Synthesis of 3-oxo-N,N-diethylbutyramide 
To a solution of diethylamine (35 g, 0.48 mol) in benzene (75 ml), diketene 
(40.2 g, 0.48 mol) in benzene (100 ml) was added dropwise at 
20.degree..about.30.degree. C., stirring was continued for 1 hr. under 
reflux, and evaporated. The residue (75 g) was chromatographed on silica 
gel (wako Gel C-200) with dichloromethane/ethyl acetate (10:1) as eluent 
to give the title compound as a yellow viscous oil; yield: 48.4 g. 
______________________________________ 
.sup.1 HNMR .delta.ppm (CDCl.sub.3): 
##STR22## 
##STR23## 
##STR24## 
IR(Neat) .nu.cm.sup.-1 : 
##STR25## 
______________________________________ 
(2) Synthesis of 2-diazo-3-oxo-N,N-diethylbutyramide 
To a solution of 3-oxo-N,N-diethylbutyramide (11.8 g, 75 mmol) obtained in 
the above process (1) and triethylamine (7.6 g, 75 mmol) in acetonitrile 
(120 ml), p-toluenesulfonylazide (14.8 g, 75 mmol) in acetonitrile (20 ml) 
was added dropwise at 20.degree..about.25.degree. C., and stirring was 
continued for 2.5 hrs. at the same temperature. The reaction mixture was 
concentrated under reduced pressure, diluted with ethyl ether (50 ml), 
washed with dilute aqueous potassium hydroxide and H.sub.2 O, dried over 
anhydrous MgSO.sub.4 and evaporated under reduced pressure. The resultant 
residue (6.8 g) was chromatographed on silica gel (Wako Gel C-200) with 
dichloromethane/ethyl acetate (5:1) as eluent to give the title compound 
as a yellow viscous oil; yield: 2.4 g. 
______________________________________ 
.sup.1 HNMR .delta.ppm (CDCl.sub.3): 
##STR26## 
##STR27## 
##STR28## 
IR(Neat).nu.cm.sup.-1 : 
##STR29## 
UV(MeOH) 227.8(12000). 
.lambda..sub.max nm(.epsilon.): 
Anal. calcd. for 
C %, 52.45; H %, 7.15; 
C.sub.8 H.sub.13 N.sub.3 O.sub.2 : 
N %, 22.94. 
Found: C %, 52.51; H %, 7.01; 
N %, 22.75. 
______________________________________ 
Referential Example 3 
Synthesis of 4-(2-diazo-1,3-dioxobutyl)pyridinium p-toluenesulfonate 
(1) synthesis of 4-(1,3-dioxobutyl)pyridine 
To a suspension of methyl isonicotinate (96.0 g, 0.7 mol) and sodium 
methoxide (45.4 g, 0.84 mol) in ethyl ether (1 l), acetone (81.3 g, 1.4 
mol) was added dropwise at 25.degree..about.30.degree. C. and stirring was 
continued for 2 hrs. under reflux. After cooling, acetic acid (50.4 g, 
0.84 mol) was added to the reaction mixture, the organic layer was 
separated, washed twice with H.sub.2 O, dried over anhydrous MgSO.sub.4 
and evaporated. The residue (87.5 g) was distilled under reduced pressure 
to give the title compound as a pale yellow oil which solidified in the 
refrigerator; yield: 40.2 g; bp 135.degree..about.138.degree. C./10 mmHg; 
mp 62.degree..about.64.5.degree. C. (Lit. bp 118.degree..about.120.degree. 
C.; mp 66.5.degree..about.67.degree. C.; R. Levine, J. K. Sneed, J. Am. 
Chem. Soc., 73, 5614 (1951).). 
##STR30## 
(2) Synthesis of 4-(2-diazo-1,3-dioxobutyl)pyridine 
To a solution of 4-(1,3-dioxobutyl)pyridine (4.9 g, 30 mmol) obtained in 
the above process (1) and triethylamine (3.2 g, 31 mmol) in chloroform (75 
ml), p-toluenesulfonylazide (6.3 g, 32 mmol) in chloroform (20 ml) was 
added dropwise at 10.degree. C. or lower, and stirring was continued for 
1.5 hrs. at the same temperature. The resultant solid was filtered off, 
the filtrate was washed twice with H.sub.2 O, dried over anhydrous 
MgSO.sub.4 and evaporated in vacuo. The residue (7.1 g) was purified by 
silica gel column chromatography (Wako Gel C-200, manufactured by Wako 
Pure Chemical Industries, Ltd.) with dichloromethane/ethyl acetate (3:1) 
to give the title compound as a yellow crystals; yield: 3.5 g; mp 
75.5.degree..about.76.5.degree. C. 
.sup.1 HNMR .delta.ppm (CDCl.sub.3) 2.55 (3H, s, CH.sub.3 CO--), 7.50 (2H, 
dd, J=6Hz, Ar 3-H, 5-H), 8.80 (2H, dd, J=6Hz, Ar 2-H, 6-H). 
IR (KBr) .nu.cm.sup.-1 : 2120 (&gt;C.dbd.N.sub.2). 
(3) Synthesis of 4-(2-diazo-1,3-dioxobutyl)pyridinium p-toluenesulfonate 
To a solution of 4-(2-diazo-1,3-dioxobutyl)-pyridine (1.9 g, 10 mmol) 
obtained in the above process (2) in ethanol (30 ml), p-toluenesulfonic 
acid monohydrate (1.9 g, 10 mmol) in ethanol (20 ml) was added dropwise at 
10.degree..about.15.degree. C., the resultant mixture was continued for 1 
hr. with stirring at room temperature and concentrated under reduced 
pressure. The resultant residue was recrystallized from isopropylalcohol 
to give the title compound as a yellow powders which was very hydroscopic; 
yield: 2.7 g; mp 106.degree. C. (dec.). 
.sup.1 HNMR .delta.ppm (CDCl.sub.3 --DMSO--d.sub.6) 2.30 (3H, s, CH.sub.3 
--), 
2.40 (3H, s, CH.sub.3 CO--), 7.13 (2H, d, J=7Hz, 
phenyl 3-H, 5-H), 7.68 (2H, d, J=7Hz, phenyl 
2-H, 6-H), 8.08 (2H, d, J=6Hz, pyridine 3-H, 
5-H), 9.00 (2H, d, J=6Hz, pyridine 2-H, 6-H). 
IR (KBr) .nu.cm.sup.-1 : 2130 (&gt;C=N.sub.2). 
Anal. calcd. for C.sub.16 H.sub.15 N.sub.3 O.sub.5 S: C%, 53.18; H%, 4.18; 
N%, 11.63. 
Found: C%, 53.50; H%, 3.98; 
N%, 11.49. 
Referential Example 4 
Synthesis of 2-(2-diazo-1,3-dioxobutyl)pyridinium p-toluenesulfonate 
(1) Synthesis of 2-(1,3-dioxobutyl)pyridine 
Using ethyl picolinate (19.7 g, 0.13 mol) and sodium methoxide (8.6 g, 0.16 
mol), the reaction was carried out in the same manner as described in 
Example 3(1), and residual oil (17.8 g) was distilled under reduced 
pressure to give the title compound as a yellow oil which was solidified 
in the refrigerator and which was an ca 1:3 mixture of Keto/Enol as seen 
by the methylene singlet at 6 4.27 ppm and the methine singlet at 
.delta.6.80 ppm in a .sup.1 HNMR spectrum; yield: 12.1 g; bp 
143.degree..about.144.degree. C./18 mmHg; mp 46.degree..about.49.degree. 
C. (Lit. bp 114.degree..about.118.degree. C./4.6 mmHg; mp 
49.degree..about.50.degree. C.; R. Levine, J. K. Sneed, J. Am. Chem. Soc., 
73, 5614 (1951).). 
##STR31## 
(2) Synthesis of 2-(2-diazo-1,3-dioxobutyl)pyridine 
Using 2-(1,3-dioxobutyl)pyridine (4.9 g, 30 mmol) obtained in the above 
process (1) and piperidine (2.6 g, 31 mmol), the reaction was carried out 
in the same manner as described in Example 3(2), and residual solid (9.0 
g) was purified by silica gel column chromatography (Wako Gel C-200) with 
dichloromethane/ethyl acetate (5:1) as eluent and then by the 
recrystallization from ethanol to give the title compound as a yellow 
plates; yield: 2.1 g; mp 83.0.degree..about.84.5.degree. C. (Lit. mp 
83.degree..about.84.degree. C.; R. Levine, J. K. Sneed, J. Am. Chem. Soc., 
73, 5614 (1951).). 
.sup.1 HNMR .delta.ppm (CDCl.sub.3) 2.67 (3H, s, CH.sub.3 CO--), 
7.33.about.8.13 (3H, m, Ar 3-H, 4-H, 5-H), 8.60 (1H, d, J=7Hz, Ar 6-H). 
IR (KBr) .nu.cm.sup.-1 : 2140 (&gt;C=N.sub.2), 1630 (C=0). 
(3) Synthesis of 2-(2-diazo-1,3-dioxobutyl)pyridinium p-toluenesulfonate 
Using 2-(2-diazo-1,3-dioxobutyl)pyridine (1.9 g, 10 mmol) obtained in the 
above process (2), the reaction was carried out in the same manner as 
described in Example 3(3), and residual solid was recrystallized from 
isopropylalcohol to give the title compound as a yellow powders which was 
very hydroscopic; yield: 2.2 g; mp 69.degree..about.74.degree. C. 
.sup.1 HNMR .delta.ppm (CDCl.sub.3) 2.37 (3H, s, CH.sub.3 --), 2.63 (3H, s, 
CH.sub.3 CO--), 7.23 (2H, d, J=7Hz, phenyl 3-H, 5-H), 7.70 (2H, d, J=7Hz, 
phenyl 2-H, 6-H), 7.50.about.8.03 (3H, m, pyridine 3-H, 4-H, 5-H), 8.57 
(1H, d, J=6Hz, pyridine 6-H). 
IR (KBr) .nu.cm.sup.-1 : 2180 (&gt;C=N.sub.2). 
Anal. calcd. for C.sub.16 H.sub.15 N.sub.3 O.sub.5 S: C%, 53.18; H%, 4.18; 
N%; 11.63. 
Found: C%, 53.29; H%, 3.89; 
N%, 11.54. 
Referential Example 5 
Synthesis of 2-Diazo-N-(2-hydroxyethyl)-3-oxobutanamide 
(1) Synthesis of N-(2-hydroxyethyl)-3-oxobutanamide 
To a solution of diketene (42.1 g, 0.5 mol) in dichloromethane (100 ml), 
ethanolamine (30.5 g, 0.5 mol) was added dropwise at 10.degree.-20.C with 
stirring, and the reaction was carried out at room temperature for 2 hrs. 
After pouring H.sub.2 O (200 ml) into the reaction solution, an aqueous 
layer was separated, washed thrice with dichloromethane and was obtained 
N-(2-hydroxyethyl)-3-oxobutanamide as an aqueous solution. 
(2) Synthesis of 2-Diazo-N-(2-hydroxyethyl)-3-oxobutanamide 
In an aqueous solution of N-(2-hydroxyethyl)-3-oxobutanamide obtained in 
the above process (1), triethylamine (50.0 g, 0.5 ml) was dissolved, then 
p-toluenesulfonylazide (98.5 g, 0.5 mol) was added dropwise at 
0.degree.-10.C and the reaction was carried out at room temperature for 3 
hrs. Then, the reaction mixture was extracted with dichloromethane (100 
ml.times.3), the organic layer was dried over anhydrous MgSO.sub.4 and 
evaporated in vacuo. The resultant residue (122 g) was chromatographed on 
silica gel (Wako Gel C-200 manufactured by Wako Pure Chemical Industries, 
Ltd.) with dichloromethane/methanol (20:1) as an eluent to give the title 
compound as pale yellow crystals; yield: 24.5 g; mp. 
69.0.degree.-70.0.degree. C. 
.sup.1 H--NMR .delta. ppm (CDCl.sub.3): 2.23 (1H, bs, --OH), 2.36 (3H, s, 
CH.sub.3 --), 3.54 (2H, m, --NHCH.sub.2 --), 3.76 (2H, t, J=5 Hz, 
--CH.sub.2 CH.sub.2 OH, 8.50 (1H, bd, NH). 
IR (KBr) .nu. cm.sup.-1 : 2140 (C=N.sub.2), 1640 (C=O). 
Anal. calcd. for C.sub.6 H.sub.9 N.sub.3 O.sub.3 : C%, 42.10; H%, 5.30; N%, 
24.55. 
Found: C%, 42.23; H%, 5.45; N%, 24.41 
Example 1 
A compound having the following composition was used as a pattern forming 
contrast enhanced material to form a pattern. 
______________________________________ 
##STR32## 4.0 g 
pullulan 2.0 g 
pure water 20.0 g 
______________________________________ 
More specifically, a positive resist [MP-2400 (made by Shipley Co., Inc.)] 
was spin-coated on a semiconductor substrate and the substrate was 
prebaked at 90.degree. C. on a hot plate for 2 min. to obtain a resist 
film having a thickness of 1.0 .mu.m. Next, the pattern forming contrast 
enhanced material having the above composition according to the present 
invention was spin-coated on the resist film to have a thickness of 0.20 
.mu.m. Successively, a selective pattern exposure was effected through a 
mask using an excimer laser beam of 248.4 nm and finally development was 
effected using an ordinary alkaline developer (an aqueous solution 
containing 2.38% of TMAH) with the result that a pattern forming contrast 
enhanced material layer was removed, only the exposed portion of the 
pattern forming material was dissolved and removed to obtain a resist 
pattern. Note that this resist pattern was a submicron pattern of a good 
configuration having a pattern angle of 90.degree.. 
As shown in FIG. 2 illustrating an ultraviolet spectroscopic curve of the 
pattern forming contrast enhanced material before and after the material 
was exposed, the transmittance of the material at 248 nm was greatly 
changed from 5% to 95% in the pre- and post-exposures. 
In contrast, a conventional contrast enhanced material was suitable to 
ultraviolet ray of 436 nm, 365 nm or 406 nm but did not absorb deep 
ultraviolet ray, in particular, an excimer laser beam of 248 nm at all. 
Therefore, this material did not exhibit a contrast enhanced action at all 
to the exposure using the above excimer laser beam. It was found that no 
absorption was carried out in the deep ultraviolet ray region as apparent 
from an ultraviolet spectroscopic curve of a conventional contrast 
enhanced film (0.36 .mu.m) shown in FIG. 3. 
Example 2 
A pattern forming contrast enhanced material having the following 
composition was produced and an experiment was carried out in the same 
manner as Example 1. 
______________________________________ 
##STR33## 4.0 g 
pullulan 2.0 g 
pure water 20.0 g 
______________________________________ 
As a result, a good result similar to Example 1 was obtained. 
Example 3 
A pattern forming contrast enhanced material having the following 
composition was produced and an experiment was carried out in the same 
manner as Example 1. 
______________________________________ 
##STR34## 4.0 g 
pullulan 2.0 g 
pure water 20.0 g 
______________________________________ 
As a result, a good result similar to Example 1 was obtained. 
Example 4 
A pattern forming contrast enhanced material having the following 
composition was produced and an experiment was carried out in the same 
manner as Example 1. 
______________________________________ 
##STR35## 4.0 g 
pullulan 2.0 g 
pure water 20.0 g 
______________________________________ 
As a result, a good result similar to Example 1 was obtained. 
Example 5 
A pattern forming contrast enhanced material having the following 
composition was produced and an experiment was carried out in the same 
manner as Example 1. 
______________________________________ 
##STR36## 4.0 g 
pullulan 2.0 g 
pure water 20.0 g 
______________________________________ 
As a result, a good result similar to Example 1 was obtained. 
Example 6 
A pattern forming contrast enhanced material having the following 
composition was produced and an experiment was carried out in the same 
manner as Example 1. 
______________________________________ 
##STR37## 4.0 g 
pullulan 2.0 g 
pure water 20.0 g 
______________________________________ 
As a result, a good result similar to Example 1 was obtained. 
Example 7 
A pattern forming contrast enhanced material having the following 
composition was produced and an experiment was carried out in the same 
manner as Example 1. 
______________________________________ 
##STR38## 4.0 g 
pullulan 2.0 g 
pure water 20.0 g 
______________________________________ 
As a result, a good result similar to Example 1 was obtained. 
A pattern forming contrast enhanced material having the following 
composition was produced and an experiment was carried out in the same 
manner as Example 1. 
______________________________________ 
##STR39## 4.0 g 
pullulan 2.0 g 
pure water 20.0 g 
______________________________________ 
As a result, a good result similar to Example 1 was obtained. 
Example 9 
A pattern forming contrast enhanced material having the following 
composition was produced and an experiment was carried out in the same 
manner as Example 1. 
______________________________________ 
##STR40## 4.0 g 
pullulan 2.0 g 
pure water 20.0 g 
______________________________________ 
As a result, a good result similar to Example 1 was obtained. 
Example 10 
A pattern forming contrast enhanced material having the following 
composition was produced and an experiment was carried out in the same 
manner as Example 1. 
______________________________________ 
##STR41## 4.0 g 
pullulan 2.0 g 
pure water 20.0 g 
______________________________________ 
As a result, a good result similar to Example 1 was obtained. 
Example 11 
A pattern forming contrast enhanced material having the following 
composition was produced and an experiment was carried out in the same 
manner as Example 1. 
______________________________________ 
##STR42## 4.0 g 
pullulan 2.0 g 
pure water 20.0 g 
______________________________________ 
As a result, a good result similar to Example 1 was obtained. 
Example 12 
A pattern forming contrast enhanced material having the following 
composition was produced and an experiment was carried out in the same 
manner as Example 1. 
______________________________________ 
##STR43## 4.0 g 
pullulan 2.0 g 
pure water 20.0 g 
______________________________________ 
As a result, a good result similar to Example 1 was obtained. 
Example 13 
A pattern forming contrast enhanced material having the following 
composition was produced and an experiment was carried out in the same 
manner as Example 1. 
______________________________________ 
##STR44## 4.0 g 
pullulan 2.0 g 
pure water 20.0 g 
______________________________________ 
As a result, a good result similar to Example 1 was obtained. 
Example 14 
A pattern forming contrast enhanced material having the following 
composition was produced and an experiment was carried out in the same 
manner as Example 1. 
______________________________________ 
##STR45## 4.0 g 
pullulan 2.0 g 
pure water 20.0 g 
______________________________________ 
As a result, a good result similar to Example 1 was obtained. 
Example 15 
A pattern forming contrast enhanced material having the following 
composition was produced and an experiment was carried out in the same 
manner as Example 1. 
______________________________________ 
##STR46## 4.0 g 
pullulan 2.0 g 
pure water 20.0 g 
______________________________________ 
As a result, a good result similar to Example 1 was obtained. 
Example 16 
A pattern forming contrast enhanced material having the following 
composition was produced and an experiment was carried out in the same 
manner as Example 1. 
______________________________________ 
##STR47## 4.0 g 
pullulan 2.0 g 
pure water 20.0 g 
______________________________________ 
As a result, a good result similar to Example 1 was obtained. 
Example 17 
A pattern forming contrast enhanced material having the following 
composition was produced and an experiment was carried out in the same 
manner as Example 1. 
______________________________________ 
##STR48## 4.0 g 
pullulan 2.0 g 
pure water 20.0 g 
______________________________________ 
As a result, a good result similar to Example 1 was obtained. 
Example 18 
A pattern forming contrast enhanced material having the following 
composition was produced and an experiment was carried out in the same 
manner as Example 1. 
______________________________________ 
##STR49## 4.0 g 
pullulan 4.0 g 
pure water 2.0 g 
______________________________________ 
As a result, a good result similar to Example 1 was obtained. 
Example 19 
A pattern forming contrast enhanced material having the following 
composition was produced and an experiment was carried out in the same 
manner as Example 1. 
______________________________________ 
##STR50## 4.0 g 
pullulan 2.0 g 
pure water 20.0 g 
______________________________________ 
As a result, a good result similar to Example 1 was obtained. 
Example 20 
A pattern forming contrast enhanced material having the following 
composition was produced and an experiment was carried out in the same 
manner as Example 1. 
______________________________________ 
##STR51## 4.0 g 
pullulan 2.0 g 
pure water 20.0 g 
______________________________________ 
As a result, a good result similar to Example 1 was obtained. 
Example 21 
A pattern forming contrast enhanced material having the following 
composition was produced and an experiment was carried out in the same 
manner as Example 1. 
______________________________________ 
##STR52## 4.0 g 
pullulan 2.0 g 
pure water 20.0 g 
______________________________________ 
As a result, a good result similar to Example 1 was obtained. 
Example 22 
A pattern forming contrast enhanced material having the following 
composition was produced and an experiment was carried out in the same 
manner as Example 1. 
______________________________________ 
##STR53## 4.0 g 
pullulan 2.0 g 
pure water 20.0 g 
______________________________________ 
As a result, a good result similar to Example 1 was obtained. 
Example 23 
A pattern forming contrast enhanced material having the following 
composition was produced and an experiment was carried out in the same 
manner as Example 1. 
______________________________________ 
##STR54## 4.0 g 
pullulan 2.0 g 
pure water 20.0 g 
______________________________________ 
As a result, a good result similar to Example 1 was obtained. 
Example 24 
A pattern forming contrast enhanced material having the following 
composition was produced and an experiment was carried out in the same 
manner as Example 1. 
______________________________________ 
##STR55## 4.0 g 
pullulan 2.0 g 
pure water 20.0 g 
______________________________________ 
As a result, a good result similar to Example 1 was obtained. 
Example 25 
A pattern forming contrast enhanced material having the following 
composition was produced and an experiment was carried out in the same 
manner as Example 1. 
______________________________________ 
##STR56## 4.0 g 
pullulan 2.0 g 
pure water 20.0 g 
______________________________________ 
As a result, a good result similar to Example 1 was obtained. 
Example 26 
A pattern forming contrast enhanced material having the following 
composition was produced and an experiment was carried out in the same 
manner as Example 1. 
______________________________________ 
##STR57## 4.0 g 
pullulan 2.0 g 
pure water 20.0 g 
______________________________________ 
As a result, a good result similar to Example 1 was obtained. 
Example 27 
A pattern forming contrast enhanced material having the following 
composition was produced and an experiment was carried out in the same 
manner as Example 1. 
______________________________________ 
##STR58## 4.0 g 
pullulan 2.0 g 
pure water 20.0 g 
______________________________________ 
As a result, a good result similar to Example 1 was obtained. 
Example 28 
A pattern forming contrast enhanced material having the following 
composition was produced and an experiment was carried out in the same 
manner as Example 1. 
______________________________________ 
##STR59## 4.0 g 
pullulan 2.0 g 
pure water 20.0 g 
______________________________________ 
As a result, a good result similar to Example 1 was obtained. 
Example 29 
A pattern forming contrast enhanced material having the following 
composition was produced and an experiment was carried out in the same 
manner as Example 1. 
______________________________________ 
##STR60## 4.0 g 
pullulan 2.0 g 
pure water 20.0 g 
______________________________________ 
As a result, a good result similar to Example 1 was obtained. 
Example 30 
A pattern forming contrast enhanced material having the following 
composition was produced and an experiment was carried out in the same 
manner as Example 1. 
______________________________________ 
##STR61## 4.0 g 
pullulan 2.0 g 
pure water 20.0 g 
______________________________________ 
As a result, a good result similar to Example 1 was obtained. 
Example 31 
A pattern forming contrast enhanced material having the following 
composition was produced and an experiment was carried out in the same 
manner as Example 1. 
______________________________________ 
##STR62## 4.0 g 
pullulan 2.0 g 
pure water 20.0 g 
______________________________________ 
As a result, a good result similar to Example 1 was obtained. 
Example 32 
A pattern forming contrast enhanced material having the following 
composition was produced and an experiment was carried out in the same 
manner as Example 1. 
______________________________________ 
##STR63## 4.0 g 
pullulan 2.0 g 
pure water 20.0 g 
______________________________________ 
As a result, a good result similar to Example 1 was obtained. 
Example 33 
A pattern forming contrast enhanced material having the following 
composition was produced and an experiment was carried out in the same 
manner as Example 1. 
______________________________________ 
##STR64## 4.0 g 
pullulan 2.0 g 
pure water 20.0 g 
______________________________________ 
As a result, a good result similar to Example 1 was obtained. 
Example 34 
A pattern forming contrast enhanced material having the following 
composition was produced and an experiment was carried out in the same 
manner as Example 1. 
______________________________________ 
##STR65## 4.0 g 
pullulan 2.0 g 
pure water 20.0 g 
______________________________________ 
As a result, a good result similar to Example 1 was obtained. 
Example 35 
A pattern forming contrast enhanced material having the following 
composition was produced and an experiment was carried out in the same 
manner as Example 1. 
______________________________________ 
##STR66## 4.0 g 
pullulan 2.0 g 
pure water 20.0 g 
______________________________________ 
As a result, a good result similar to Example 1 was obtained. 
Example 36 
A pattern forming contrast enhanced material having the following 
composition was produced and an experiment was carried out in the same 
manner as Example 1. 
______________________________________ 
##STR67## 4.0 g 
pullulan 2.0 g 
pure water 20.0 g 
______________________________________ 
As a result, a good result similar to Example 1 was obtained. 
Example 37 
A pattern forming contrast enhanced material having the following 
composition was produced and an experiment was carried out in the same 
manner as Example 1. 
______________________________________ 
##STR68## 4.0 g 
pullulan 2.0 g 
pure water 20.0 g 
______________________________________ 
As a result, a good result similar to Example 1 was obtained. 
Example 38 
A pattern forming contrast enhanced material having the following 
composition was produced and an experiment was carried out in the same 
manner as Example 1. 
______________________________________ 
##STR69## 4.0 g 
pullulan 2.0 g 
pure water 20.0 g 
______________________________________ 
As a result, a good result similar to Example 1 was obtained. 
Although the present invention is described using only the pluran as the 
water soluble resin, water soluble resin applicable to the pattern forming 
contrast enhanced material according to the present invention is not 
limited to the pullulan and the same good result was obtained when 
polyvinyl alcohol, polyvinyl pyrrolidone, polyethylene glycol, 
polyethylene oxide, water soluble cellulose derivatives, etc. were used. 
In addition, although the pure water was used as a solvent, it is not 
limited to the pure water. 
Example 39 
A pattern forming contrast enhanced material having the following 
composition was produced and an experiment was carried out in the same 
manner as Example 1. 
______________________________________ 
##STR70## 4.0 g 
pullulan 2.0 g 
pure water 20.0 g 
______________________________________ 
As a result, a good result similar to Example 1 was obtained. 
Example 40 
A pattern forming contrast enhanced material having the following 
composition was produced and an experiment was carried out in the same 
manner as Example 1. 
______________________________________ 
##STR71## 4.0 g 
pullulan 2.0 g 
pure water 20.0 g 
______________________________________ 
As a result, a good result similar to Example 1 was obtained.