Note: Descriptions are shown in the official language in which they were submitted.
Radiation-sensitive cornposition and pattern-formation
method usin~ the same
The present invention relates to a radiation~sensitive
composition and pattern-formation method using the same.
In conventional pattern-ormation methods, a coating
film of a radiation-sensitive composition is exposed to
radiation of a given pattern and then the coating film is
immersed in a liquid developer (usually an organic
solvent), or the liquid developer is sprayed over the
surface of the coating film, to form a pattern by the wet
development technique~ However, this wet development
technique has a disadvantage in that the negative-working
composition used in a system employing a crosslinking
reaction becomes swollen by the developer. This
constitutes a serious obstacle to the formation of an
accurate developed image of the pattern.
A dry development technique has been proposed to
overcome this disadvantage wherein plasma is used for
~evelopment. If dry development is effectea until a
region of a negative working composition, i.e. an
unexposed region, has been completely removed, the surface
of the e~posed region that must remain is also etched to a
considerable extent, and the normalized film remaining
(the ratio of the thickness of the remaining film to the
initial film thickness) is considerably reduced. Thus, if
this method is to be employed in practice, many problems
remain to be overcome.
Summary of the Invention
-
An object of the present invention is to provide a
radiation sensitive composition suitable for dry
development, and a pattern-forma~ion method using the same.
According to one aspect of the invention there is
provided a radiation-sensitive composition comprising.
an azide compound selected from the group consisting of
a compound of the general formula:
N3
~A
Z Z
wherein A represents an element or a substituent selected
from the group consisting of O, S, CH~, CH2CH2, SO2,
S2, CO, COO, SO3, CH=CH and CH=CRCO, and X, Y and Z each
represent an element or a substituent selected from the
group consisting of an azido group, hydrogen, alkyl group,
nitro group, halogen, amino group, monoalkylamino group,
alkoxy group, hydroxyl group, sulfonic acid group, sulfonic
acid ester group, carboxylic acid group and carboxylic
acid ester group; and a compound of the general formula:
~3 ~
y
wherein X, Y and Z each represent an element or substit-
uent selected from the group consisting of an azide group,
hydrogen, alkyl group, nitro group, halogen, amino group,
monoalkylamino group, alkoxyl group, hydroxyl group, sul-
fonic acid group, sulfonic acid ester group, carboxylic
acid group and car~oxylic acid ester group; an iodine
.
: :,
compound at least a part of which can be fixecl substan
tially in a polymer layer by exposure to a radiation;
and a polymer substantially having compatibility with
the azide compound and the iodine compound.
According to ano~her aspect of the invention there
is provided a method of forming a pattern character-
ized by comprising the step,s of forming a coating
film of a radiation-sensitive composition comprising
an azide compound, an iodine compound at least a
part of which can be fixed substantially in a poly-
mer layer by exposure to a radiation and a polymer
substantially having compatibility with the azide
compound and the iodine compound, exposing the
coating film to a radiation having a desired pat-
tern, heating the coating film to remove the iodine
compound from an unexposed region of the coating film
and exposing the coating film to an oxygen-containing
plasma to remove the unexposed part.
Other apsect~ of this invention are claimed in
our copending Canadian patent application Serial No.
407,336 filed on July 15, 1982, of which the present
application is a division.
Preferred embodiments of the present invention
are described in the following with reference to the
accompanying drawings, in which:
Fig. 1 is a graph showing the change in film
thickness of certain compositions with exposure to
plasma;
Fig. 2 and Fig. 3 are similar graphs for specific
0 compositions described in the examples.
- 2a -
In the radiation-sensitive composition of the
present invention an iodine-containing azide com-
pound may be replaced with an azide compound and
an organic iodine compound, at least a part of
which can be fixed substantially in the polymer
by exposure to radiation. Thus, the composition
may comprise an azide compound, an organic iodine
compound at least a part of which can be fixed
substantially in a polymer layer by exposure to a
- 2b -
radiation and a polymer substantially having compatibility
with the azide compound and the iodine compound.
The pattern-formation method involves the steps of
forming a coating film of the radiation-sensitive
composition, e~posing the coating film to radiation having
a desired pattern, heating the coating film to remove the
iodine-containing azide compound or iodine compound in the
unexposed regions and exposing the coating film to an
oxygen-containing plasma to remove the unexposed part~
The term "radiation" herein re~ers to visible light,
ultraviolet light, X-rays, electron beams and ion beams in
a broad sense.
As though the mechanisms of the reaction or
decomposition of the azide compound caused by exposure to
the radiation have not been elucidated yet, it is believed
that at least an iodine-containing moiety of the compound
is substantially fixed in the polymer layer. It is
believed that by the presence of iodine, a non-volatile,
oxygen-containing, plasma-resi~tant substance is formed on
the surface layer in the oxygen-conta;ning plasma. This
i5 a property peculiar to iodine compounds. Chlorine- or
bromine~containing compounds do not have such a property.
The reason why an iodine-containing azide compound is
substantially ixed in the polymer layer in the
composition containing said compound is that said compound
or a part thereof is directly linked with the polymer or,
otherwise~ converted into its dimer or polymer and,
there.ore, it is not dissipated even when heated.
When the composition containing the iodine compound
and azide compound is used, there are two cases, i.e. (1)
the azide compound is directly linked with both the iodine
--3--
compound and the polymer (particularly when the azide
compound is a d;azide compound) and (2~ a part of the
azide compound is linked with the iocline compound, whereby
the iodine compound is not dissipated even when heated and
the other part of the azide compound is linked with the
polymer to alter its solubility. The term "azide
compound" includes also compounds formed by the photolysis
and converted compounds. The mechanism described above is
only an estimation and it does not exert any limitation on
the scope of the invention~
The heating temperature of th~ coating film should be
such that the iodine-containing azide compound, or the
iod$ne compound, in the unexposed region is dissipated.
In other words, it should be higher than the sublimation
temperature or boiling point of said compound. The
heating temperature is, therefore, variable depending on
the particular iodine-containing azide compound or iodine
compound used If the coating film is placed under
reduced pressure, the heating temperature can be reduced
to some extent. The upper limit of the heating
temperature should be below the decompositlon point of the
polymer.
The term "polymer substantially compatible with the
azide compound or iodine compound" refers to a polymer
capable of forming a coating film including said compound
and having a substantially homogeneous composition. Even
if polymer Pl is incompatible with the compound, a
mixture of polymer Pl with another polymer P2
compatible with polymer Pl may be used, if this mixture
(Pl ~ P2) is compatible with said compound.
The polymer should preferably have very good
film-forming characteristics~
As for the proportion of the polymer to the iodine-
containing azide compound in the radiation-sensitive
composition, ;t is preferred that the amount of the
iodine-containing azide compound be 10-80 wt.%,
particularly 30-60 wt.%, based on the weight of
composition.
Fig~ l shows changes in film thickness observed when
films having various proportions of the polymer and the
azide compound were exposed to oxygen plasma. It should
be taken into consideration that the initial thicknesses
were different from one another and about 50~ of the
coating film containing 20 wt.% of the azide compound (2
,4 ,6 -triiodophenyl-4~-azido-benzoate) remained even
after exposure to oxygen plasma for about 8 min, while a
coating film containing only the polymer (polyvinylphenol~
disappeared after exposure to oxygen plasma for about 8
min. About 60% and 75% of coating Eilms containing 33
wt.% and 50 wt.%, respectively, of the same azide compound
remained after exposure to oxygen plasma for 8 min. This
fact indicates that the amount of film remaining (normal-
ized film) is increased as the amount of the iodine-
containing azide compound is increased. However, it will
be apparent from the above description that a certain
amount of the polymer is necessary for ixing the azide
compound. Therefore, an amount in the above-mentioned
range is preferred. The plasma irradiation conditions are
shown in Example l given below.
The proportion of the polymer, organic iodine compound
3G and azide compound in the radiation-sensitive composition
comprising these three compounds is preferably
l:G.1-3:0.05-2, particularly 1:0.4-2:0.1-1, by weight.
Experimental data of the resis~ance of the composltion
to oxygen plasma will be shown in Ta~le 1, which shows
relative removal rates of films by oxygen pla~sma measured
after hardenin~ of coating films comprising polystyrene,
3,3'-diaziododiphenyl sulfone and iodoform by light. It
is apparent from Table 1 that oxygen plasma resistance is
increased remarkably as the amount of iodoform (iodine
compound) is increased. I~ can be seen, therefore, that
the coating film can be used as an oxygen plasma-resisting
mas~. The experimental conditions were the same as in
Fig. 1.
Table 1
.
Polystyrene Diazide com- Iodoform Relative
(part by wt.) pound (part by wt.) removal
(part by w~.l rate of film
1 0.2 0 1.0
1 0.2 0.24 0.77
1 0.2 0 S~ Q.4~
l 002 1.53 0.33
,
The followinq compounds can be used as the polymer:
poly-N-vlnyl-carbazole, polyacenaphthylene, polyvinylidene
fluoride, poly-N-vinylpyrrolidone, polyglycidyl
methacrylate, polystyrene, polyalkyl methacrylates, cyclic
polyisoprene, poly-4-methylstyrene, poymethacrylonitrile,
poly-4~vinylpyridine, poly-4-bromostyrene, polyvinyl-
benzyl chloride, polybutadiene, poly-4-chlorostyrene,
epoxidized polybutadiene, polyvinyi acetate, polyvinyl
cinnamate, polyvinyl chloride, pvlychloroprene, poly-
vinyl bromide, polyepichlorohydrin, polyvinylphenol,
polyvinyl alcohol, polyvinylidene chloride, poly-
acrylonitrile, poly-~methylstyrene, polymethyl
isopropenyl ketone, polyacrylamide, polyvinyl meth~l
ketone, polybu~ene-l sulfone, polystyrene sulfone,
polyisobutylene, a phenolic resin such as novolak
resin, styrene/maleic anhydride copolymer, cellulose
acetate hydrogenphthala~e, polyvinyl hydroxybenzoate,
polyvinyl hydroxvbenzal or acrylic resin. These poly-
mers may also be used as components of copolymers.
Further, polymers other than those mentioned above having
film-forming properties and compatibility with said
compounds may also be used. These polymers may be used
~ither alone or in the form of a mixture of two or more of
them.
Polymers containing a benzene ring or rubbery polymers
are preferred from the viewpoint of their dry etching
resistance.
When the pattern formation method of the present
invention is carried out according to the dry development
technique, the iodine-containing polymer cannot
substantially be used as the polymer. The reason therefor
is that even if it is attempted to remove the
iodine-containing compound from the unexposed region of
the coating film by heating, the iodine~containing polymer
remains in the film, and it exhibits a resistance to
oxygen plasma. However, it will be understood from, for
examplel Table 1 given above that if the iodine content is
low, the difference in the relative removal rate of film
in this case from that of iodine-free film is
insignificant. Since the iodine compound or
iodine-containing azide compound is present in the exposed
region, the total of iodine contained therein and that
oontained in the polymer is relatively large and the
relative xemoval rate of the film is reduced. Thus, even
if the polymer contains only a small amount of iodine, a
pattern may be formed in the coating film according to the
dry development.
The following compounds of general formula (I) are
given as examples of azide compounds containing iodine:
N3 ~ I
x (I)
R y
wherein Rx and Ry each represent an element or atomic
group selected from the group consisting of hydrogen, an
alkyl group, a nitro group, halogen, an amino group, a
monoalkylamino group, an acyl group, a dialkylamino group,
an alkoxyl group, a hydroxyl group, a sulfonic acid gro~p,
a sulfonio acid ester group, a carboxylic acid gro~p and a
carboxylic acid ester group.
The Eollowing are examples of these compounds:
p-azidoiodobenzene, 2,6-diiodo-4-nitroazido-benzene, 2-
chloro-4-iodoazidobenzene, 2,6-dichloro-4-iodoazido-
benzene, 2-bromo-4-iodoazidobenzene, 2,6-dibromo-4-
iodoazidobenzene, 2-methyl-4-iodoazidobenzene and
2-methoxy-4-iodoazidobenzene.
Further, azide compounds of the following general
formula (II) may be mentioned as examples:
i~s ~ _ y - ~ i (II)
wherein Y represents an atomic group selected from the
group consisting of CH2~ COO, OOC, SO3 and O3S and
Ri represents an element or atomic group selected from
the group consisting of I, CH2I and CH2CH2I.
The following are examples of these comounds:
2-iodoethyl-4-azidobenzoate, iodomethyl-4 azidobenzoate,
4 azidophenyl iodoacetate ancl 4-iodomethylazidobenzene.
In addition, azide compounds of the following general
formula (III) may be mentioned:
3 ~ ~ ~ y ~III)
wherein X represents an element or atomic gro~p selected
from the group consisting of S~, CH2, O, S, SO2, CO,
COO, SO3, CH=CH and CH=CHCO and Rx and Ry have the
same meaning as described above.
The following are examples of these compounds: 2 ,4
,6 -triiodophenyl-4'-azidobenzoate, 3
-iodophenyl-4'-azidobenzoate, 4-azido-4'-iododiphenyl
s~lfide and 4-azido-4'-iodobenzophenone.
In the above-mentioned, iodine-containing azide
compoundsl those having one aromatic ring and those having
the iodine atoms directly bonded to the henzene ring are
preferred in view of their ease o~ dissipation by heat.
A combination of ~n azide compound containing a polar
group, e.g. a carboxylic acid group, with a polymer having
a polar group, e.g~ a polyvinylphenol, is not preferred,
since dissipation of the azide compound by heat becomes
difficult.
Examples of the iodine compounds that may be used in
the present invention are diiodomethane,
iodoform, iodoethane, l-iodobutane, l-iodohept~ne,
l-iodopropane, 2-iodopropane, 1,2-diiodoetnane,
1,4-diiodobutane, iodotrimethylsilane, 2-iodo-1,1,1-
trifluoroethane, iodomethyltrimethylsilane, iodoacetamide,
iodoacetic acid, 3-iodopropionic acid, 2-iodoethanol,
2-iodoaniline, 3-iodoaniline, 4-iodoaniline, 4-iodo-
anisole, 5-iodoanthranilic acid, o-iodobenzoic acid,
m-iodobenzoic acid, p iodobenzoic acid, p iodobenzene-
sulfonyl chloride, o-iodobenzyl alcohol, m-iodobenzyl
alcohol, p~iodobenzyl alcohol, iodobenzene, o-diiodo-
benzene, m-diiodobenzene, p-diiodobenzene, o-iodobenzyl
chloride, l-iodo-2-nitrobenzene, 1-iodo-3-nitrobenzene,
l-iodo-4-nitrobenzene, 2-iodophenol, 3-iQdophenol,
4-iodophenol, 5-iodosalicylic acid, o-iodotoluene,
m-iodotoluene, p-iodotoluene, o-iodo-~ -trifluoro-
toluene, 2 iodo-6-methyl-3-pyridinol, 2-iodo-3-pyri.dinol,
4-iodopyrazole, 2-iodothiophene, 3-iodothiophene,
2,6-diiodo-4-nitroaniline, 2,6-diiodo-4-nitrophenol,
3,5-diiodo-4-pyridone-N-acetate, 4-hydroxy-3,5-diiodo-
benzoic acid, 2,4,$-triiodobenzoic acid, 3,4,5-triodo-
benzoic acid and 2,4,6-triiodophenol. They may be
used either alone or in the form of a m-xture of two
or more compounds~ These iodine compounds do not have an
azido group.
Examples of the azide compounds that may be used in
the invention are those of the general formula:
Y~ ~ ~ ~ (IV)
Z Z
--10--
wherein A represents an element or a substituent
selected from the group ~onsisting of O, S, CH2,
CH2CH2, SO2, S2, CO, COO, SO3, CH=CH and CH=CHCO,
and X, Y and Z each represent an element or a sub-
stituent selected from the group consisting of an
azido group, hydrogen, al~yl group, nitro group,
haLogen, amino group, monoalkylamino group, alkoxyl
group, hydroxyl group, sulfonic acid group, sulfonic
acid es~er group, carboxylic acid group and carboxylic
acid ester gro~p, and
those of the general formula:
~Z ~V)
Y
X
wherein X, Y and Z have the same meaning as above.
Organlc azide compounds other than those shown above
may also be used. The azide compounds may be used either
alone or in the form of a mixture of two or more of them.
Some of ~he compounds wherein at least one of
X, Y and Z represents iodine are the same as the
a~ove-mentioned iodine-containing azide compounds.
These lodine-containing azide compounds may also be
used in combination with the iodine compound, if they
are remo~able from the coating film in an unexposed
region by heating.
Particular examples of the azide compounds of
general formula (IV) are 4,4'-diazidodiphenyl ether,
4,4'-diazidodiphenyl sulfide, 4,4'-diazidodiphenyl
sulfone, 3,3'-dia2idodiphenyl sulfone,
4,4'-diazidodiphenylmethane, 3,31-dichloro-
'7
4,4'-diazidodiphenylmethane, 4,4'-diazidodiphenyl
disulfide t 4,4l-diazidobibenzyl, 2 ,4 ,6 -triiodo-
phenyl-4' azidobenzoate, 3 -iodophenyl-4'-azidobenzoate,
4-azido-4'-iododiphenyl sulfide and 4-azido-4'-iodobenzo-
phenone.
Particular examples of the azide compounds of general
formula ~V) are p-azidoiodobenzene, 2,6-diiodo-4-
nitroazidobenzene, 2-chloro-4-iodoazidobenzene, 2,6-
dichloro-4~iodoazidobenæene, 2~bromo-4-iodoazidobenzene,
2,6-dibro~o-4-iodoazidobenzene, 2-methyl-4-
iodoazidobenzene and 2-methoxyr4-iodoazidobenzene.
As representative of other azide compounds,
2-iodomethyl-4-azidobenzoate, for example, may be
mentioned.
It is preferred to use diazide compounds as the azide
compounds, since they fix the iodine compounds firmly.
Also in the radiation-s~nsitive ~omposition comprising
the iodine compound, azide compound and polymer wherein
the iodine compound contains a polar group, e.g. a
carboxylic acid group, or wherein the azide compound
contains iodine and a polar group, e.g. carbox~lic acid
group, it is not preferred to use a polar gro~p-containing
polymer such as polyvinylphenol, novolak resin,
styrne/maleic anhydride copolymer, cellulose acetate
hydrogenphthalate, polyvinyl hydroxybenæoate,
polyvinylhydroxybenzalJ polymethacry~ic acid or poly-
acrylic acid, because these compounds are difficult to
dissipate by heating during dry development.
The sensitive composition of the present invention can
also be used in an ordinary wet development technique~
In this case, it is preferred that the azide compound be a
-12-
dia7ide compound or that when the azide compound is a
monoazide compound, a polymer having a polar group e.y.
polyacrylic acid, particularly~ a polymer soluble in an
aqueous alkali solution be used.
When other compositions, wherein the azide compound is
a monoazide compound and the polymer contains no polar
group, are used, the wet development technique should
preferably not be employed.
Examples of the polymers soluble in an aqueous alkali
solution are, for example, polyvinylphenol, novolak resin,
styrene/maleic anhydride copolymer, cel].ulose acetate
hydrogenphthalate, polyvinyl hydroxybenzoatel polyvinyl-
hydroxybenzal/ polymethacrylic acid and polyacrylic acid.
When the wet development technique is employed, an
unexposed part is removed with a solvent by an ordinary
method after exposure to the radiation.
The radiation-sensitive composition of the present
invention has very good resistance to oxygen plasma as
described above and, therefore, it may be used for the
production of a printing plate. In this technique, for
example, a coating film of the composition of the pre~ent
invention is formed on a nylon base, a desired pattern is
formed thereon and the base is etched using oxygen
plasma. Accordingly, the reduction of resolution due to
the swelling of the base with a solvent can be prevented.
Any oxygen-containing plasma may be used, though it is
preferred to use oxygen plasma per se.
The following Examples will further illustrate the
present invention. First, processes for synthesizing the
iodine-containing azide compounds will be described.
-13-
p-Iodoaniline (6g) was dispersed in a solu~ion
comprising 25 cc of water and 7.5 GC of 36% hydro-
chloric acid and c0012d with ice. Sodium nitrite
(2.1g) was dissolved in 13 ml of water and the result-
ing solution was added dropwise slowly to the dispersion
to effect the diazotization reaction. A ~olution of
2.5g of sodlum azlde ln 18 ml of water was added drop-
wise thereto and, ater stirring for one hour, the
mixture was subjected to extraction with benzene.
After the dehydration with sodium sulfate, benzene
was e~aporated to yield p-azidoiodobenzene.
ax~ 260 ~m, m.p. 33C
2,6-Diiodo-4 nitroazidobenzene:
.
2,6-Diiodo-4-nitroaniline (Sg) was dissolved
in 20 ml of ~onc. sulfuric acid and cooled with iceO
Sodium nitrite previously ~acuum-dried was added to
the solution in portions to effect the diazotization
xeactio~ at 0-5C~ The reaction product was added
dxopwise to ice-wa~er to dil~te the sulfuric acid.
A solution of 104g of sodium azide in 10 cc of water
was added dropwise to the mix~ure, stirred for about
one hour, filtered and washed with water. Af~er t~e
rac~ystallization from ethanol followed by drying,
2,6-dilodo-4-nitroazidobenzene was obtained.
~max 302 nm, m.p. 82 C.
2_,4 ,6 -Triiodophenyl-4'-azidoben~oate:
p-~minobenzoic acid (13.7~) was dispersed in
a solution of 100 cc of water and 30 cc of 30% hydro-
chloric acid in an ordinary manner and the dispersion
was cooled wi~h ice. A solution of 8.3g of sodium
nitrite in S0 cc of water was added dropwise to the,
dispersion to efEect the diazo-tization reaction.
A sollltion of lO.lg of sodium azide in J0 cc of water
was added dropwise to the mixture, stirred lor about
one hour, filtered and vacuum-dried to obtain p-
azidobenzoic acid. The thus obtained p-azidobenzoic
acid ~5~4g) was dissolved in 10 cc of dimethyl-
formamide and 25 g of thionyl chloride was added dropwise
to the solution. The mixture was stirred for about one
hour and the product was added dropwise to ice~water.
After filtration followed by washing with water and
~acuum drying, p-azidobenzoyl chloride was obtained.
p-Azidobenzoyl chloride (0.9g) a~ 2,4g o~
2,4,6-triiodophenol were dissolved in 60 cc of dioxane.
The resulting solution was mixed with a solution of
0.2g of sodium hydroxide in 20 ml of water and the
mixture was left to stand overnight and then poured
into water. A solid matter thus formed was filtered
out, washed with water and dried under vacuum to
yield 2 ,4 ,6 -triiodophenyl-4'-azidobenzoate.
~max 278 nm, m-p- llS C.
3 -Iodo hen 1-4'-azidobenzoate:
__ P
3 -Iodophenyl 4-azidobenzoate was obtained by
reacting azidobenzoyl chloride obtained as above with
m-iodophenol in the same manner as above.
~max 278 nm.
Example 1
Polystyrene having a weight-average molecular
weigh~ ~Mw) of about 270,000 was dissolved in chloro-
benzene to form a 7 wt.% solution. Then, p-a7ido-
iodobenzene was added to the solution to ob~ain a
resist solution~ The mixing ratio of polystyrene to
-15-
p-azidoiodobenzene was 1:0.6, by weight. The resist
solution was applied ~o the surface oE a silicon wafer
by ~eans of a spinner to form a film having a thickness
of 0.6 ~m. After exposing the film to light from a
Xe-Hg lamp via a test pattern mask for 20 sec, it was
post-baked at 100C for 30 min to form a sample for
the plasma development. The development was effected
as shown below by means of an experimental apparatus
con isting of a parallel-plate plasma reactor having
a maximum output of 600 W and an electrode diameter
of 60 mm. The sample was place~ on a lower elec-trode
and, after degassing, oxygen gas was introduced there-
in to control the pressure in the reactor to 0.5 Torr. A
high frequency power of 13.56 MHz was applied thereto and
oxygen plasma was formed in the plasma reactor at an
output of 55 W for 6 min. A~ter degassing in the reactor,
the pressure was returned to atmospheric. The sample was
taken out and subjected to microscopic examination to
reveal that, unlike the product of the wet development
method, the product thus obtained had a repetition pattern
of line~ having a width of 1 ~m that were not swollen
at all and were arranged at intervals of 1 ~m with high
accuracy.
p-Azidoiodobenzene was added to a 10 wt.% solution of
cyclic polyisoprene in xylene to obtain a resist solution.
The mixing ratio of cyclic polyisoprene to p-azidoiodo-
benzene was 1:1, by weight. The resist solution was
applied to the surface of a silicone wafer by means of
a spinner to form a film having a thickness of about
0.9 ~m~ After exposing the film to light from a Xe Hg
-16-
lamp, it wa.s post-baked at lOO~C for 30 min to form a
sample for the plasma development. After efecting the
development in ~he same manner as in Example 1, the product
was subjected to microscopic examination to reveal that,
unlike the product of the wet development method, the
product thus obtained had the same, minute pattern as in
Example 1.
The relationship between the exposure time and normal-
ized film remaining is shown in Eig. 2. After the exposure
for longer than about ~ sec, the normalized film remaining
was higher than 50~
p-Azidoiodobenzene was added to a 6 wt.% solution of
polymethyl methacrylate having a weight-average molecular
weight (Mw) of about 600,000 in ethyl cellosolve acetate
to form a resist solution. The mixing ratio of polymethyl
methacrylate to p-azidoiodobenzene was 1:1, by weight.
The resist solution was applied to the surEace of a
silicon wafer by means of a spinner to form a film having
a thickness of about 0.5 ~m. After exposing the film to
light from a Xe~Hg lamp via a test pattern mask for 20
sec, it was post-baked at 100C for 30 min to form a
sample for the plasma development. After effecting the
development with oxygen plasma ;n the same manner as
in Example 1, the product was subjected to microscopic
examination to reveal that, unlike the product of the
wet development method, the product thus obtained had a
repetition pattern of lines having a width of 1 ~m which
were not swollen at all and were arranged at intervals of
1 ~m with high accuracy.
A resist solution having the same composition as in
Example 1 having a mixing ratio of poly,tyrene to p-azido-
iodobenzene of 1:1, by weight, was used. The resist
solution was applied to the surface of a silicon wafer
in the same manner as in Example 1. After the exposure
followed by the post-baking, the development was efected
with oxygen plasma. The normalized film remaining was
superior to that obtained in Example 1. The sample was
su~ected to microscopic examination to reveal that, unlike
the product of the wet development method, the product thus
obtained had a repetition pattern of lines having a width
of 1~ m which were not swollen at all and were arranged at
intervals o~ 1~ m with high accuracy.
Example 5
2 ,4 ,6 Triiodophenyl-4'-aæidobenzoate was added to
a 20% solution of polyvinylphenol having a weight-average
molecular weight (Mw) of about 3000 in methyl cellosolve
acetate to form a resist solution. The mixing ratio o the
polyvinylphenol to the a~ide compound was 1:1, by weight.
The resist solution was applied to the surface of a sili-
con wafer by means of a spinner to form a film having a
thickness of about 0.9~ m. After exposing the film to
light from a Xe-Hg lamp via a test pattern mask for 20 sec,
it was post-baked at 140C for 60 min to form a sample for
the plasma development. After effecting the development
with oxygen plasma in the same manner as in Example 1, the
product was subjected to microscopic examination to reveal
that, unlike the product of the wet development method, the
product thus obtained had a repetition pattern of lines
-18-
having a width of 1 ~m that were not swollen at all and
were arranged at intervals of 1 ~m with high accuracy.
2,6-Diiodo-4-nitroazidobenzene was added to a 20 wt.%
solution of polyvinylphencl having a weight~average molec-
ular weight (~w) of about 3000 in methyl cellosolve acetate
to form a resist solution. The mixing ratio of polyvinyl-
phenol to the azide compound was 1:0.5, by weight. The
resist solution was applied to the surface of a silicon
wafer by means of a spinner to form a film having a thick-
ness of about 0.9~ m. After exposing the film to light
from a Xe-Hg lamp via a test pattern mask for 20 sec, it
was post-baked at 140C for 60 min ~o form a sample for
plasma development. After effecting the development with
oxygen plasma in the same manner as in Example 1, the
product was subjected to microscopic examination to reveal
that, unlike the product of the wet development method~
the product thus obtained had a repetition pattern oE lines
having a width of 1~ m that were not swollen at all and
were arranged at intervals of 1~ m with high accuracy.
Example 7
Polyvinylphenol having a weight-average molecular
weight ~Mw) of about 5800 was dissolved in methyl cello-
solve acetate to orrn a 20 wt.% solution. Then, 3,3'-
diazidodiphenyl sulfone and 2,4,6-triiodophenol were added
to the solution to form a resist solution. The mixing
ratio of polyvinylphenol : 3,3'-diazidodiphenyl sulfone
: 2,4,6-triiodophenol was 1:0.2:0~7, by weight. The
resist solution was appl.ied to the surface of a silicon
wafer by means of a spinner to form a film having a
thickness of about 0.85 ~m. After exposing the film to
-19-
light from a Xe-Hg lamp via a test pattern rnask for 20 ~ec,
it was post-baked at 140C for 60 min to obtain a sample
for plasma development. This sample was placed in the
same plasma~orming apparatus as in Example 1 and oxygen
plasma was formed for 8 min. After degassing in the
reactor, the pressure was returned to atmospheric. The
sample was taken out and subjected to microscopic examin-
ation to reveal that the product had a repetition pattern
of lines having a width of 1 ~m that were not swollen at
all and were arranged at intervals of 1 ~m with high
accuracy.
A resist solution was used having the same composition
as in Example 7 except that the mixing ratio of polyvinyl~
phenol : 3,3'-diazidodiphenyl sulfone : 2,4,6-triidodi
phenol was altered to 1:0.2:1, by weight. The resist
solution was applied to a silicon wafer in the same manner
as in Example 7. After the exposure followed by the post-
baking, it was subjected to the development with oxygen
plasma in the same manner as in Example 7. The exposure
time and normalized film remaining were as shown in Fig.
3. The film was superior to that of Example 7 with respect
to the remaining normalized filmO The product was subjec-
ted to microscopic examination to reveal that it had a
repetition pattern o~ lines having a width of 1~ m ~hat
were not swollen at all and were arranged at intervals of
1~ m with high accuracy.
Example 9
Polystyrene having a weight-average molecular weight
(Mw) of about 270,000 was dissolved in chlorobenzene to
form a 7 wt.~ solution. Then, 3,3'-diazidodiphenyl
-20-
sulfone and m-iodophenol were added to the solution to
form a resist solution. The mixing ratio of polystyrene :
3,3'-diazidodiphenyl sulfone : ~-iodophenol was 1:0.2:0.5,
by weight. The resist solution was applied to the surface
of a silicon wafer by means of a spinner to form a film
having a thickness of about 0.76 ~m. After exposing the
film to light from a Xe-Hg lampl it was post~baked at 110C
for 85 min to obtain a sample for the plasma development.
After effecting the development with oxygen plasma in the
same manner as in Example 7, the product was subjected to
mlcroscopic examination to reveal that, unlike the product
of the wet development method, the product thus obtained
had the same, fine pattern as in Example 7.
Exam~e_10
Polystyrene having a weight-average molecular weight
(Mw) of about 270/000 was dissolved in chlorobenzene to
Porm a 7 wt.% solution. Then, 3,3'-diazidodiphenyl sulfone
and m-diiodobenzene were added to the solution to form a
resist solution. The mixing ratio of polystyrene : 3,3'-
diazidodiphenyl sulfone : m-diiodobenzene was 1:0.2:0.5,
by weight. The resist solution was applied to the surface
of a silicon wafer by means of a spinner to form a film
having a thickness of 0.86 ~m. After exposing the film to
light from a Xe-H~ lamp, it was post-baked at 110C for 60
min to form a sample for the plasma developmentO After
effecting the development with oxygen plasma in the same
manner as in Example 7, the product was subjected to micro-
scopic examination to reveal that, unlike the product of
the wet development method, the product thus obtained had
the same, fine pattern as in Example 7.
-21-
3~'7
Example 11
Polystyrene having a weight-average molecular weight
~Mw) of about 270,000 was dissolved in chlorobenzene to
form a 7 wt D % solution. Then, 3,3'-diazidodiphenyl sulfone
and iodoform were added to the solution to form a resist
solution. The mixing ratio of polystyrene : 3,3'-diazido-
diphenyl sulfone : iodoform was 1:0.2:0.5, by weight. The
resist solution was applied to the surface of a silicon
wafer by means of a spinner to form a film having a thick-
ness of 0.86~ mO After exposing the film to light from aXe-Hg lamp, it was post-baked at 110C or 90 min to form
a sample for the plasma development. After effecting the
development with oxygen plasma in the same manner as in
Example 1, the product was subjected to microscopic examin-
ation to reveal that, unlike the product of the wet devel-
opment method, the product thus obtained had the same,
fine pattern as in Example 7 and was free of swelling.
When the iodine compounds or azido compounds used in
above Examples 7-11 were replaced with other iodine com~
pounds or azido compounds, a fine pattern could also be
obtained by dry development.
2,4,6-Triiodophenol (13 parts by weight) was added to
100 parts by weight of a solution comprising 20 parts by
weight of poly-p~vinylphenol, 4 parts by weight of 3,3'-
diazidodiphenyl sulfone and 80 parts by weight of cyclo-
hexanone to form a resist solution. The resist solution
was applied to the surface of a silicon wafer by means of
a spinner and baked at 80C for 20 min in air to form a
resist film having a thickness of 1.1~ m which was
-22-
'7
used as an expo.sure sample~ After exposing the sample to
light from a 600 W Xe-Hg lamp via a ~est pattern mask for
5 sec, it was immersed in a 0~95 wt.% aqueous solution of
tetramethylammonium hydroxide used as a developer for 30
sec to effect the development of the resist film. The
product was subjected to microscopic examination to reveal
that the product thus obtained had a repetition pattern of
lines having a width of 1 ~m which were not swollen at all
and were arranged at intervals of 1 ~m with high accuracy.
Example 13
m,p-Cresol novolak resin (20 parts by weight), 6 parts
by weight of 4 azido-4' methoxychalcone and 10 parts by
weight of 2,4,6-triiodophenol were dissolved in 80 parts
by weight of methyl cellosolve acetate to form a resist
solution. The resist solution was applied to the surface
of a silicon wafer and baked at 80C for 20 min to form a
resist film having a thickness of 0.9 ~m. After exposiny
the film to light from a 500 W ultra-high pressure Hg lamp
via a test pattern mask for 2 sec, it was developed with
an aqueous solution of tetramethylammonium hydroxide to
form a repetit;on pattern of lines having a width of 1 ~m
arranged at intervals of 1 ~m with high accuracy.
The films were exposed to light in the above examples.
Substantially the same effects were also obtained when
visible light, X-rays, electron beams or ion beams were
used,
-23-
