Method of forming a resist pattern

A negative type resist in which an alkali-soluble base resin, a crosslinking agent and an acid generating agent are dissolved in a solvent, wherein 10 through 50 wt % of the crosslinking agent and 0.5 through 20 wt % of the acid generating agent on the basis of 100 wt % of the alkali-soluble base resin are dissolved in the solvent.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
The present invention relates to a negative type resist for a resist layer 
which is formed on the surface of a layer for etching that is formed on a 
substrate and a method of forming a resist pattern for forming a resist 
pattern on the surface of the layer for etching by using the negative type 
resist. 
2. Discussion of Background 
At present, in manufacturing methods of large scale integrated circuits 
(LSI) represented by a 4M or 16M dynamic random access memory (DRAM), it 
is very important for performing a miniaturization, to form a resist 
pattern which is formed on the surface of a layer for etching, for 
instance, of an insulating layer or a wiring layer. 
It is a general practice in forming a resist pattern that after coating a 
positive type photoresist comprising a novolak resin and 
naphthoquinonediazide on the surface of a layer for etching, g line beam 
(wavelength 436 nm) from a mercury lamp is selectively irradiated on the 
positive type photoresist layer and the layer is successively developed. 
In recent times, in the dynamic random access memory, the integration 
degree thereof has been increased further to 16M or 64M. 
When the integration degree is enhanced and the miniaturization process is 
promoted, i line beam (wavelength 365 nm) has been employed as a beam from 
a beam source for selectively irradiating to a resist layer. 
When the integration degree of the large scale integrated circuit is 
enhanced and a resist pattern of a half .mu.m or less is required from now 
on, it is difficult to manufacture stably the circuit when the resist 
pattern is formed by using the i line beam. Therefore, researches are 
beginning to carry out wherein a KrF excimer laser beam (wavelength 248 
nm) is employed as a beam source having a shorter wavelength. 
However, when a resist pattern is formed by selectively irradiating the KrF 
excimer laser beam to a positive type photoresist layer and by developing 
the layer, after coating the positive type photoresist comprising a 
novolak resin and naphthoquinonediazide on the surface of a layer for 
etching which has been employed for the g line beam or the i line beam 
from a mercury lamp, side walls of the pattern having faces orthogonal to 
the surface of the layer for etching can not be provided and a resist 
pattern having a high resolution can not be provided, since beam 
absorption is considerable in the positive type resist. 
Accordingly, the following two resists have been proposed as the resist for 
the KrF excimer laser beam. 
The first one is a chemically amplified positive type resist having two 
components comprising a base resin and an acid generating agent which 
generates an acid by receiving a light beam or three components comprising 
the above two components added with a dissolution restraining agent, which 
is easy to dissolve in an alkaline developer when an acid from the acid 
generating agent accelerates a polarity change reaction in a dissolution 
restraining protection group of the base resin or the dissolution 
restraining agent by performing a baking operation. 
The second one is a chemically amplified negative type resist comprising a 
base resin, a crosslinking agent and an acid generating agent which 
generates an acid by receiving a light beam, which is hardened when the 
acid from the acid generating agent accelerates a crosslinking reaction 
between the base resin and the crosslinking agent by performing a baking 
operation. 
However, in the above chemically amplified positive type resist, the acid 
from the acid generating agent which has generated by receiving a light 
beam is neutralized by a deactivating substance in environment (the acid 
is evaporated from the surface layer of the resist layer into the 
environment), by which the ratio of the polarity change reaction through 
the baking operation before developing is decreased, the surface layer of 
the resist layer is difficult to dissolve in the developer. Thereby, a 
phenomenon (T-Top) is caused wherein eaves are formed on the head portion 
of the resist pattern or a phenomenon (Skin) is caused wherein the head 
portions of the contiguous portions of the resist pattern are in 
connection with each other. Further, the acid from the acid generating 
agent which has been generated by receiving a light beam is neutralized by 
a deactivating substance on the surface of a layer for etching (the acid 
is diffused from portions of the resist layer contacting the layer for 
etching to the layer for etching), by which the ratio of the polarity 
change reaction is decreased through the baking operation before 
developing, the portions of the resist layer contacting the layer for 
etching are difficult to dissolve into the developer, and as a result, 
trails or residues are caused in the resist pattern. Such phenomena of the 
resist pattern are problematic in the etching operation for the layer for 
etching, and therefore, a resist pattern having a high resolution is 
difficult to obtain. 
Further, also in the chemically amplified negative type resist, the acid 
from the acid generating agent which has generated by receiving a light 
beam is neutralized by a deactivating substance in environment (the 
deactivating substance is diffused from the environment to the surface 
layer of the resist layer) by which the ratio of the crosslinking reaction 
is decreased through the baking operation before developing, the surface 
layer of the resist layer is difficult to harden, and the head portions of 
the resist pattern are provided with a rounded shape. Further, the acid 
from the acid generating agent which has been generated by receiving a 
light beam is neutralized by a deactivating substance on the surface of a 
layer for etching (the deactivating substance is diffused from the layer 
for etching to the portions of the resist layer contacting the layer for 
etching) by which the ratio of the crosslinking reaction is decreased 
through the baking operation before developing, the portions of the resist 
layer contacting the layer for etching are difficult to harden and the 
resist pattern is provided with an undercut shape. 
The rounding shape of the head portions and the undercut of the resist 
pattern which are observed in the chemically sensitizing negative type 
resist are not so problematic in etching the layer for etching. Further, 
in principle, the chemically amplified negative type resist utilizes the 
crosslinking reaction of a resin. Therefore, the thermal resistance 
thereof is considerable, the mechanical strength thereof is provided with 
a large value and the deformation of the resist pattern is extremely 
limited. Accordingly, the chemically amplified negative type resist is 
superior to the chemically amplified positive type resist in regard with a 
resist pattern that is employed in hard etching, highly-dosed ion 
implantation or high energy ion implantation wherein the temperature of 
the resin is substantially elevated. 
However, the following problems have been caused when the chemically 
amplified negative type resist was coated on the surface of the layer for 
etching, the resist was prebaked, the KrF excimer laser beam was 
selectively irradiated on a resist layer comprising the chemically 
amplified negative type resist, the resist was baked and the resist was 
developed, to provide a resist pattern of a half .mu.m or less. 
Firstly, in the exposure region of the resist layer irradiated with the KrF 
excimer laser beam, a portion of the film was reduced at the surface of 
the resist layer, and an encroachment was caused in the portions of the 
resist layer contacting the layer for etching. 
This is because, in the exposure region of the resist layer, the amount of 
acid from the acid generating agent is reduced by a neutralization 
reaction caused by a basic substance on the surface of the resist and in 
the portions of the resist proximate to the surface, and in the portions 
of the resist contacting the layer for etching, by which the crosslinking 
density is lowered. As a result, the dissolution rate with respect to the 
developer immediately before the developing operation on the surface and 
in the portions proximate to the surface of the resin, and the portions of 
the resin contacting the layer for etching, becomes faster in comparison 
with those in the other portions. 
Secondly, waviness of the side walls of the developed resist pattern, that 
is, a ruggedness thereof became conspicuous. 
This is due to a fact wherein the dissolution rate in the exposure region 
of the resist layer is periodically distributed in the depth direction by 
a standing wave caused by an interference between an incident beam of the 
KrF excimer laser beam that is incident on the exposure region of the 
resist layer and a reflecting beam from the surface of the layer for 
etching. 
Thirdly, there caused a variation in the resist film thickness of the 
resist pattern or a variation in dimensions of the resist. 
These are caused by a variation in the reflectance of the surface of the 
layer for etching. 
Fourthly, the difference between the dissolution rates with respect to the 
developer in the exposure region and the non-exposure region of the resist 
layer, at the portions of the resist layer contacting the layer for 
etching, was not made large, and therefore, the resolution was poor. 
This is due to a fact wherein, in the exposure region of the resist layer, 
the dissolution rate with respect to the developer in the portions of the 
resist layer contacting the layer for etching, is faster than the 
dissolution rate of the portions of the resist layer on the surface 
thereof. 
As a result, a sufficient resolution and a wide range of depth of focus 
were not provided, and an excellent shape of the resist pattern was not 
achieved. 
SUMMARY OF THE INVENTION 
This invention was carried out in view of these situations, and it is an 
object of the present invention to provide a negative type resist and a 
method of forming a resist pattern whereby a high resolution is achieved, 
a wide range of depth of focus is provided and an excellent shape of a 
resist pattern is provided. 
According to a first aspect of the present invention, there is provided a 
negative type resist in which an alkali-soluble base resin, a crosslinking 
agent and an acid generating agent are dissolved in a solvent, wherein 10 
through 50 wt % of the crosslinking agent and 0.5 through 20 wt % of the 
acid generating agent on the basis of 100 wt % of the alkali-soluble base 
resin are dissolved in the solvent. 
According to a second aspect of the present invention, there is provided a 
negative type resist in which an alkali-soluble base resin, a crosslinking 
agent and an acid generating agent are dissolved in a solvent, wherein 20 
through 40 wt % of the crosslinking agent and 3 through 15 wt % of the 
acid generating agent on the basis of 100 wt % of the alkali-soluble base 
resin are dissolved in the solvent. 
According to a third aspect of the present invention, there is provided a 
method of forming a resist pattern comprising: 
a step of forming a resist layer comprising a negative type resist of which 
dissolution rate with respect to a developer is 3,000 .ANG./sec or more at 
a surface layer of the resist layer, on a surface of a substrate by 
coating the negative type resist on the surface of the substrate and by 
prebaking the negative type resist, said negative type resist becoming 
slightly soluble or insoluble to the developer when a chemical change is 
caused to a substance generated by receiving a radiation such as a light 
beam or an electron beam by baking, or when a chemical change is caused in 
a substance by receiving the radiation; 
a total face irradiation step for irradiating the radiation on a total of 
the surface of the resist layer through an opaque reticle; 
a selective irradiation step for irradiating the radiation on the surface 
of the resist layer through a reticle formed with a desired pattern; and 
a step of providing a resist pattern by developing the resist layer 
irradiated with the radiation in the total face irradiation step and the 
selective irradiation step by the developer. 
According to a fourth aspect of the present invention, there is provided a 
method of forming a resist pattern comprising: 
a step of forming a resist layer on a surface of a substrate comprising a 
negative type resist by coating the negative type resist on the surface of 
the substrate and by prebaking the negative type resist, said negative 
type resist becoming slightly soluble or insoluble to a developer when a 
chemical change is caused in a substance generated by receiving a 
radiation such as a light beam or an electron beam by baking; 
a total face irradiation and baking step for irradiating the radiation on a 
total of a surface of the resist layer through an opaque reticle and 
baking the resist layer thereafter; 
a selective irradiation and baking step for irradiating the radiation on 
the surface of the resist layer through a reticle formed with a desired 
pattern and baking the resist layer thereafter; and 
a step of providing a resist pattern by developing the resist layer 
irradiated with the radiation in the total face irradiation and baking 
step and the selective irradiation and baking step. 
According to a fifth aspect of the present invention, there is provided a 
method of forming a resist pattern comprising: 
a step of forming a resist layer comprising a negative type resist on a 
surface of a substrate by coating the negative type resist on the surface 
of the substrate and prebaking the negative type resist, said negative 
type resist becoming slightly soluble or insoluble to a developer when a 
chemical change is caused in a substance generated by receiving a 
radiation such as a light beam or an electron beam by baking or when a 
chemical change is caused in a substance by receiving the irradiation; 
a total face irradiation step for irradiating the radiation on a total of a 
surface of the resist layer; 
a selective irradiation step for irradiating the radiation on the surface 
of the resist layer through a reticle formed with a desired pattern; 
step of providing a resist pattern by developing the resist layer 
irradiated with the radiation in the total face irradiation step and the 
selective irradiation step by the developer; and 
wherein a first effective exposure amount applied on the resist layer 
irradiated with the radiation in the total face irradiation step is 5 
through 15% of a second effective exposure amount applied on an exposure 
region of the resist layer irradiated with the radiation in the selective 
irradiation step. 
According to a sixth aspect of the present invention, there is provided a 
method of forming a resist pattern comprising: 
a step of forming a resist layer comprising a negative type resist on a 
surface of a substrate by coating the negative type resist on the surface 
of the substrate and by prebaking the negative type resist, said negative 
type resist becoming slightly soluble or insoluble to a developer when a 
chemical change is caused in a substance generated by receiving a 
radiation such as a light beam or an electron beam by baking or when a 
chemical change is caused in a substance by receiving the radiation; 
an irradiation step for irradiating the radiation on a surface of the 
resist layer through a reticle formed with a desired pattern comprising a 
light transmitting region and a light shielding layer having a light 
transmittance of 1 through 20%; and 
a step of providing a resist pattern by developing the resist layer 
irradiated with the radiation in the irradiation step by the developer. 
According to a seventh aspect of the present invention, there is provided a 
method of forming a resist pattern comprising: 
a resist layer forming step for forming a resist layer comprising a 
negative type resist on a surface of a substrate by coating the negative 
type resist on the surface of the substrate and by prebaking the negative 
type resist, said negative type resist becoming slightly soluble or 
insoluble to a developer when a chemical change is caused in a substance 
generated by receiving a radiation such as a light beam or an electron 
beam by baking or when a chemical change is caused in a substance by 
receiving the radiation; 
an irradiation step for irradiating the radiation on a surface of the 
resist layer through a reticle formed with a desired pattern comprising a 
light transmitting region and a light shielding layer having a light 
transmittance of 3 through 15%; and 
a step for providing a resist pattern by developing the resist layer 
irradiated with the radiation in the irradiation step by the developer. 
According to the first aspect of the present invention, after coating 10 
through 50 wt % of the crosslinking agent on the basis of 100 wt % of the 
alkali-soluble base resin, on the surface of the substrate, the 
crosslinking agent promotes the dissolution rate of the resist layer with 
respect to the developer before the irradiation of the radiation, whereby, 
in the developing operation, the contrast of the dissolution rate with 
respect to the developer in the exposure region of the resist layer as 
compared with that in the non-exposure region is promoted. 
According to the second aspect of the present invention, after coating 20 
through 40 wt % of the crosslinking agent on the basis of 100 wt % of the 
alkali-soluble base resin, on the surface of the substrate, the 
crosslinking agent promotes the dissolution rate of the resist layer with 
respect to the developer before the irradiation of the radiation, whereby, 
in the developing operation, the contrast of the dissolution rate with 
respect to the developer in the exposure region of the resist layer as 
compared with that in the non-exposure region is promoted. 
According to the third aspect of the present invention, the resist layer 
comprising the negative type resist wherein the dissolution rate with 
respect to the developer is 3,000 .ANG./sec or more at the surface layer 
thereof, is formed. In the developing operation, the contrast of the 
dissolution rate with respect to the developer in the exposure region of 
the resist layer as compared with that in the non-exposure region, is 
promoted particularly on the side of the portions of the resist layer 
contacting the substrate, the total face irradiation step lowers the 
dissolution rate of the resist layer on the surface portion and the 
portions contacting the substrate in the exposure region, and the 
difference between the dissolution rates in the exposure region and the 
non-exposure region of the resist layer on the side of the portions 
contacting the substrate, is rendered to be larger than the difference 
between the dissolution rates in the exposure region and the non-exposure 
region of the resist layer at the surface portion. 
According to the fourth aspect of the present invention, the total face 
irradiation operation in the total face irradiation and baking step, 
lowers the dissolution rates at the surface portion of the resist layer 
and the portions thereof contacting the substrate in the exposure region, 
the difference between the dissolution rates of the resist layer between 
the exposure region and the non-exposure region on the side of the 
portions contacting the substrate, is rendered to be larger than the 
difference between the dissociation rates of the resist layer between the 
exposure region and the non-exposure region at the surface portion, and 
the baking operation of the resist layer that is carried out between the 
total face irradiation of the resist layer and the selective irradiation 
thereof, reduces the influence of a standing wave of the radiation in the 
exposure region of the resist layer. 
According to the fifth aspect of the present invention, the total face 
irradiation step lowers the dissolution rates at the surface portion of 
the resist layer and the portions thereof contacting the substrate in the 
exposure region, and renders the difference between the dissolution rates 
of the resist layer of the exposure region and the non-exposure region on 
the side of the portions thereof contacting the substrate to be larger 
than the difference between the dissolution rates of the resist layer of 
the exposure region and the non-exposure region at the surface portion. 
According to the sixth aspect of the present invention, the irradiation 
step lowers the dissolution rates of the resist layer at the surface 
portion and at the portions thereof contacting the substrate in the 
exposure region, and renders the difference between the dissolution rates 
of the resist layer of the exposure region and the non-exposure region on 
the side of the portions thereof contacting the substrate to be larger 
than the difference of the dissolution rates of the resist layer between 
the exposure region and the non-exposure region at the surface portion. 
According to the seventh aspect of the present invention, the irradiation 
step lowers the dissolution rates of the resist layer at the surface 
portions and the portions thereof contacting the substrate in the exposure 
region, and renders the difference of the dissolution rates of the resist 
layer between the exposure region and the non-exposure region on the side 
of the portions thereof contacting the substrate to be larger than the 
difference of the dissolution rates of the resist layer between the 
exposure region and the non-exposure region at the surface portion.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
EXAMPLE 1 
An explanation will be given of Example 1 of this invention as follows in 
reference to FIGS. 1 through 8. 
Firstly, an explanation will be given of a resist A which was employed in 
Example 1. The resist A comprises the following composition, which is "a 
negative type resist that is difficult to dissolve in a developer when a 
chemical change is caused in a substance generated by receiving a 
radiation, by baking". 
(Resist A) 
Alkali-soluble base resin 
Poly-P-hydroxystyrene: 20 parts by weight 
Crosslinking agent 
Hexamethoxymethylmelamine: 7 parts by weight 
Acid generating agent 
1,2,3,4-tetrabromobutane: 0.6 part by weight 
Solvent 
Methyl 3-methoxypropionate 
Next, an explanation will be given of a method of forming a resist pattern 
using the resist A. 
First, the resist A is spincoated on the surface of a substrate 1 such as a 
semiconductor wafer which is formed with a layer for etching (for 
instance, insulating layer), as shown in FIG. 1. A resist layer 2 is 
formed on the surface of the substrate 1 by prebaking the substrate 1 in 
which the resist A has been spincoated on a hot plate 3 that is a heating 
means, at 100.degree. C. for 70 seconds. 
As a condition of spincoating, the spincoating was performed such that the 
film thickness of the resist layer 2 became 1 .mu.m when the prebaking had 
been performed. 
At this instance, the dissolution rate of the resist layer 2 which had been 
formed on the surface of the substrate 1 with respect to a developer, for 
instance, an aqueous solution of 1.23 wt % of tetramethylammonium 
hydroxide (for instance, NMD-3 made by Tokyo Ohka Kogyo Co., LTD), was 
3,500 .ANG./sec at the surface layer of the formed resist 2. The 
dissolution rate of the resist layer 2 with respect to the developer is 
fast, since it contains much crosslinking agent. That is, although the 
dissolution rate of the base resin that is a high-molecular compound (in 
case of poly-P-hydroxystyrene, the weight-average molecular weight Mw is 
5,000 or less) is retarded (approximately 500 .ANG./sec.sup.2 or less) 
since it is hard, it becomes softer in accordance with addition of the 
crosslinking agent that is a low-molecular compound to the base resin, and 
the dissolution rate is enhanced. 
Further, the developer of the resist layer 2 is not restricted to the above 
Example and any developer can be employed so far as it is an alkaline 
aqueous solution. 
Next, as shown in FIG. 2, an exposure device, for instance, a KrF excimer 
stepper, (for instance, NSR2005EX8A, made by Nippon Kogaku K.K.) is 
employed, an opaque reticle 4 having the light transmittance of 10% is 
disposed on the surface of the formed resist layer 2, a KrF excimer laser 
beam 5 having the wavelength of 248 nm is irradiated from above the opaque 
reticle in a range of 10 through 50 mJ/cm.sup.2, and the excimer laser 
beam 5 is irradiated on the total face of the resist layer 2 through the 
opaque reticle 4. 
The opaque reticle 4 at this instance is formed with an opaque layer 
composed of chromium (Cr), molybdenum silicide (MoSi) or oxinitrides of 
these, on the total surface of a transparent substrate such as glass, and 
the light transmittance thereof is rendered to be 10%, which serves to 
irradiate the excimer laser beam 5 on the resist layer 2 after reducing 
the energy of the original excimer laser beam 5 from the exposure device. 
Further, although the opaque reticle 4 was provided with 10% of the light 
transmittance, the transmittance may be in a range of 1 through 50%, 
preferably in a range of 5 through 15%. 
As shown in FIG. 3, a baking operation is performed with respect to the 
substrate 1 which has been irradiated with the excimer laser beam on the 
total surface of the resist layer 2 thereof on the hot plate 3 that is the 
heating means, at 100.degree. C. for 90 seconds. 
By the baking operation, the thickness of the resist layer 2 which has been 
formed on the substrate 1 is more or less reduced in comparison with that 
before baking. 
Next, as shown in FIG. 4, the same exposure device which has been used in 
the total irradiation step shown in FIG. 2 is employed, a reticle 7 that 
is formed with a desired pattern is disposed on the surface of the resist 
layer 2, the KrF excimer laser beam 5 having the wavelength of 248 nm is 
irradiated from above the reticle 7 in a range of 5 through 100 
mJ/cm.sup.2, preferably 10 through 50 mJ/cm.sup.2, and the excimer laser 
beam 5 is selectively irradiated on the surface of the resist layer 2 
through the reticle 7, thereby forming an image on the resist layer 2. 
That is, the resist layer 2 is divided into an exposure region 6a and a 
non-exposure region 6b based on the pattern formed on the reticle 7. 
As shown in FIG. 7(b), in the exposure region 6a of the resist layer 2, an 
acid is generated from the acid generating agent. The non-exposure region 
6b of the resist layer 2 is in a state as shown in FIG. 7(a). 
The reticle 7 is formed with a beam shielding layer (the light 
transmittance is 0%) composed of a desired pattern on the surface of a 
transparent substrate such as glass, that is, formed with a beam shielding 
layer at a portion thereof corresponding to a portion of the resist to be 
removed and formed with a beam transmitting region corresponding to a 
portion of the resist to be preserved. The beam shielding layer is formed 
by chromium (Cr), molybdenum silicide (MoSi) or oxinitrides of these. 
Thereafter, as shown in FIG. 5, the baking was performed with respect to 
the substrate 2 having the resist layer 2 composed of the exposure region 
6a and the non-exposure region 6b above the hot plate 3 that is the 
heating means, at 100.degree. C for 90 seconds. As shown in FIG. 7(c), in 
the exposure region 6a of the resist layer 2, the acid generated from the 
acid generating agent operates as a catalyst, and a crosslinking reaction 
is caused between the crosslinking agent and the base resin, whereby the 
exposure region 6a of the resist layer 2 is hardened. This baking 
operation is called the post-exposure baking (PEB). Further, in the 
non-exposure region 6b of the resist layer 2, no crosslinking reaction is 
caused between the crosslinking agent and the base resin since no acid is 
generated from the acid generating agent. 
A result as shown in FIG. 8 was provided by measuring the dissolution rate 
of the resist layer 2 comprising the exposure region 6a and the 
non-exposure region 6b formed as above, with respect to the developer 
immediately before developing. In FIG. 8, line A designates the 
distribution of the dissolution rate of the resist layer 2 with respect to 
the developer from the surface of the resist layer 2 to the surface of the 
substrate 1 in the exposure region 6a, whereas line B designates the 
distribution of the dissolution rate of the resist layer 2 with respect to 
the developer from the surface of the resist layer 2 to the surface of the 
substrate 1 in the non-exposure region 6b. 
Further, a developing operation was performed by using the developer, or 
"NMD-3 made by Tokyo Ohka Kogyo Co., LTD" which is an aqueous solution of 
1.23 wt % of tetramethylammonium hydroxide, for 100 seconds by the 
spray-paddle method, thereby obtaining a resist pattern as shown in FIG. 
6. 
A result as shown in FIG. 9 was provided when with respect to the resist 
pattern 8 obtained as above, measurements were performed on a sectional 
shape of 0.3 .mu.m line and space pattern, a sensitivity of 0.3 .mu.m line 
and space pattern (exposure beam amount in finishing the resist pattern as 
specified by mask dimension), a limit resolution of line and space 
pattern, and a resolution depth of focus of 0.3 .mu.m line and space 
pattern. 
There are almost no rounding of the surface portions of the resist and no 
encroachment in the portions thereof contacting the substrate 1, in the 
sectional shape of the resist pattern 8 and the sectional shape is in an 
approximately rectangular shape in which side walls thereof have faces 
orthogonal to the approximately flat substrate 1. The sensitivity of 0.3 
.mu.m line and space pattern is 60 mJ/cm.sup.2, and the limit resolution 
of line and space pattern is 0.175 .mu.m which is a resolution 
sufficiently smaller than those in Comparative Examples, mentioned later 
whereby the function of the resist pattern is improved. The resolution 
depth of focus of 0.3 .mu.m line and space pattern is 1.8 .mu.m which is 
larger than those in Comparative Examples, mentioned later. Therefore, a 
wide range of depth of focus and therefore, the resist pattern having an 
improve function were provided. 
The reason for obtaining the resist pattern 8 having the high resolution, 
the broad focus allowance and the improved shape, is considered to be as 
follows. 
As is apparent in FIG. 8, showing the dissolution rate of the resist layer 
with respect to the developer immediately before developing, the 
dissolution rate of the resist layer 2 with respect to the developer 
distributing from the surface of the resist layer 2 to the surface of the 
substrate 1 in the exposure region 6(a), is within a range of 
approximately 0.1 through 0.5 .ANG./sec which stays approximately the 
same. Further, the dissolution rate of the resist layer 2 with respect to 
the developer distributing from the surface of the resist layer 2 to the 
surface of the substrate 1 in the non-exposure region 6b, is within a 
range of approximately 800 through 2,000 .ANG./sec, having an 
inconsiderable variation. 
Accordingly, in the exposure region 6a of the resist layer 2, the 
effectively absorbed exposure amount is increased, the hardening reaction 
is accelerated and the dissolution rate with respect to the developer is 
lowered by the twice irradiation steps of the total irradiation step shown 
in FIG. 2 and the selective irradiation step shown in FIG. 4. The total 
face irradiation step shown in FIG. 2 is carried out prior to the 
selective irradiation step shown in FIG. 4, and therefore, the acid from 
the acid generating agent in the vicinity of the surface of the resist 
layer 2 which has been generated in the total face irradiation step shown 
in FIG. 2, is reduced whereby the degree of hardening in the vicinity of 
the surface can be more or less reduced. The dissolution rate with respect 
to the developer distributing from the surface of the resist layer 2 to 
the surface of the substrate 1 stays approximately the same. Accordingly, 
the rounding of the surface portions of the resist pattern 8 which has 
been preserved after it is developed by the developer (corresponding to 
the exposure region 6a of the resist layer 2), and the encroachment of the 
portions of the resist contacting the substrate 1 are restrained, and the 
side walls are provided with approximately flat vertical faces. 
In the exposure region 6a of the resist layer 2, the dissolution rate with 
respect to the developer stays the same from the surface of the resist 
layer 2 to the surface of the substrate 1 due to the following reason. 
That is, the thicknesses of the resist layers 2 are different between the 
total face irradiation step shown in FIG. 2 and the selective irradiation 
step shown in FIG. 4, since the baking step of the resist layer 2 shown in 
FIG. 3 is performed between the total irradiation step of the excimer 
laser beam 5 shown in FIG. 2 and the selective irradiation step of the 
excimer laser beam 5 shown in FIG. 4. Therefore, a standing wave of the 
excimer laser beam 5 (a wave caused by an interference between the 
incident beam that is incident on the resist layer 2 and the reflecting 
beam reflected from the surface of the substrate 1) in the total face 
irradiation step shown in FIG. 2 at the exposure region 6a of the resist 
layer 2, and a standing wave of the excimer laser beam 5 in the selective 
irradiation step shown in FIG. 4, function to cancel each other, by which 
the dissolution rate of the resist layer 2 with respect to the developer 
distributing from the surface of the resist layer 2 to the surface of the 
substrate 1, is rendered to maintain constant. 
Further, in the non-exposure region 6b of the resist layer 2, the beam 
absorption amount of the excimer laser beam 5 in the total face 
irradiation step shown in FIG. 2 is increased in the portions thereof 
proximate to the surface, and the portions are easy to harden. Therefore, 
the dissolution rate with respect to the developer is lowered to 
approximately 800 .ANG./sec in comparison with 3,500 .ANG./sec of the 
dissolution rate with respect to the developer before irradiating the 
excimer laser beam 5. Although the hardening reaction is caused on the 
topmost surface thereof by the excimer laser beam 5 in the total face 
irradiation step shown in FIG. 2, the degree of lowering of the 
dissolution rate is smaller than the lowering of the dissolution rate at 
the portions of the resist proximate to the surface due to evaporation of 
the acid which has been generated by the excimer laser beam 5 and a 
reaction between the resist and basic substances in the atmosphere. The 
dissolution rate with respect to the developer is the most enhanced at the 
portions of the resist contacting the substrate 1. The dissolution rate of 
the resist layer 2 with respect to the developer distributing from the 
surface of the resist layer 2 to the surface of the substrate 1 is 
provided with little variation and is within a range of approximately 800 
through 2,000 .ANG./sec. Further, the difference between the dissolution 
rates of the resist layer 2 of the exposure region 6a and the non-exposure 
region 6b on the side of the portions of the resist layer contacting the 
substrate 1 is larger than the difference between the dissolution rates of 
the resist layer 2 of the exposure region 6a and the non-exposure region 
6b at the surface portion of the resist layer 2. 
Accordingly, there is a difference by four digits or more between the 
dissolution rate in the non-exposure region 6b in the resist layer 2 and 
the dissolution rate in the exposure region 6a of the resist layer 2 
throughout the resist from the surface of the resist layer 2 to the 
surface of the substrate 1, the pattern can be formed in a good shape even 
when it is of 0.3 .mu.m or less, and the difference between the 
dissolution rates in the portions of the resist contacting the substrate 1 
is larger than the difference between the dissolution rates on the surface 
of the resist layer 2. Therefore, the high resolution can be provided. 
EXAMPLE 2 
In Example 2, only the composition of the resist is different from that in 
Example 1, the following resist B is employed in place of the resist A 
shown in Example 1 , and the resist pattern 8 is provided in accordance 
with the order of steps shown in FIGS. 1 through 6 similar to Example 1. 
(Resist B) 
Alkali-soluble base resin 
Poly-P-hydroxystyrene: 20 parts by weight 
Crosslinking agent 
Hexamethoxymethylmelamine: 4 parts by weight 
Acid generating agent 
1,2,3,4-tetrabromobutane: 0.6 part by weight 
Solvent 
Methyl 3-methoxypropionate 
The resist B is "a negative type resist which is difficult to dissolve into 
a developer when a chemical change is caused in a substance generated by 
receiving a radiation by baking", similar to the resist A. 
In Example 2 wherein the resist pattern 8 is formed in accordance with the 
order of steps shown in FIGS. 1 through 6 similar to Example 1, after the 
step shown in FIG. 1, the dissolution rate of the resist layer 2 which has 
been formed on the surface of the substrate 1, with respect to a 
developer, for instance, an aqueous solution of 1.23 wt % of 
tetramethylammonium hydroxide, (for instance, NMD-3 made by Tokyo Ohka 
Kogyo Co., LTD) is 15,000 .ANG./sec at the surface layer of the formed 
resist layer 2. A result shown in FIG. 10 was provided by measuring the 
dissolution rate of the resist layer 2 comprising the exposure region 6a 
and the non-exposure region 6b with respect to the developer immediately 
before developing, after the step shown in FIG. 5. In FIG. 10, line A 
designates the distribution of the dissolution rate of the resist layer 2 
with respect to the developer from the surface of the resist layer 2 to 
the surface of the substrate 1 in the exposure region 6a, whereas line b 
designates the dissolution rate of the resist layer 2 from the surface of 
the resist layer 2 to the surface of the substrate 1 in the non-exposure 
region 6b. 
A result shown in FIG. 9 was provided in the resist pattern 8 obtained as 
above, by measuring the sectional shape of 0.3 .mu.m line and space 
pattern, the sensitivity of 0.3 .mu.m line and space pattern (exposure 
beam amount in finishing the resist pattern as specified by mask 
dimensions), the limit resolution of line and space pattern and the 
resolution depth of focus of 0.3 .mu.m line and space pattern. 
Although the sectional shape of the resist pattern 8 is provided with more 
or less roundings on the surface portion and encroachments of the resist 2 
contacting the substrate 1 in comparison with that in Example 1, the side 
walls are provided with faces approximately orthogonal to the 
approximately flat substrate 1. The sensitivity of the 0.3 .mu.m line and 
space pattern is 45 mJ/cm.sup.2, and the limit resolution of lien and 
space pattern is 0.225 .mu.m which are a little larger than those in 
Example 1, however, sufficiently smaller than those in Comparative 
Examples, mentioned later. Therefore, the function is improved since a 
sufficient resolution is provided. The resolution depth of focus of 0.3 
.mu.m line and space pattern is 1.2 .mu.m which is a little smaller than 
that in Example, 1 however, larger than those in Comparative Examples, 
mentioned later. Therefore, the function is improved since a broad range 
of depth of focus is provided. 
The reason for obtaining the resist pattern 8 having such a high 
resolution, the broad range of the focus allowance and the excellent shape 
is considered to be as follows. 
As is apparent from FIG. 10 showing the dissolution rate of the resist 
layer 2 with respect to the developer immediately before developing, the 
dissolution rate of the resist layer 2 distributing from the surface of 
the resist layer 2 to the surface of the substrate 2 with respect to the 
developer in the exposure range 6a, is within a range of approximately 0.2 
through 0.5 .ANG./sec and stays almost the same. Further, the dissolution 
rate of the resist layer 2 with respect to the developer distributing from 
the surface of the resist layer 2 to the surface of the substrate 1 in the 
non-exposure region 6b is within a range of approximately 900 through 
1,500 .ANG./sec which shows little variation. 
Accordingly, in the exposure region 6a, the dissolution rate of the resist 
layer 2 with respect to the developer is lowered and the dissolution rate 
of the resist layer 2 with respect to the developer distributing from the 
surface of the resist layer 2 to the surface of the substrate 1 stays 
approximately the same as in Example 1. Therefore, roundings of the 
surface portion of the resist pattern 8 (corresponding to the exposure 
region 6a of the resist layer 2) that has been preserved after being 
developed by the developer, are restrained, encroachments of the portions 
of the resist 2 contacting the substrate 1 are restrained, and further, 
the side walls are provided with approximately flat faces. 
Further, there is a difference by four digits or more between the 
dissolution rate of the resist layer 2 in the non-exposure region 6b and 
the dissolution rate of the resist layer 2 in the exposure region 6a. 
Especially, the difference between the dissolution rates of the resist 
layer 2 of the exposure region 6a and the non-exposure region 6b on the 
side of the resist layer 2 contacting the substrate, is larger than the 
difference between the dissolution rates of the resist layer 2 of the 
exposure region 6a and the non-exposure region 6b on the surface portion 
of the resist layer 2. Therefore, the pattern can be formed in a good 
shape even if it is of 0.3 .mu.m or less. 
Further, in above Examples 1 and 2, the same exposure device, for instance, 
a KrF excimer stepper, (for instance, NSR2005EX8A made by Nippon Kogaku 
K.K.) is employed both in the total irradiation step shown in FIG. 2 and 
the selective irradiation step shown in FIG. 4. The KrF excimer laser beam 
5 is irradiated on the resist layer 2 preferably in a range of 10 through 
50 mJ/cm.sup.2. The opaque reticle 4 is used in the total face irradiation 
step shown in FIG. 2, and the effective exposure beam amount applied on 
the resist layer 2 is in a range of 1 through 50%, preferably 5 through 
15% of the effective exposure beam amount applied on the exposure region 
6a of the resist layer 2 in the selective irradiation step shown in FIG. 
4. However, the exposure device is not restricted to the KrF excimer 
stepper and may be an exposure device for irradiating an ArF excimer laser 
beam, or an exposure device using a mercury lamp for irradiating an 
ultraviolet ray such as g line beam or i line beam. In short, the same 
effect is achieved by rendering the effective exposure beam amount applied 
on the resist layer 2 in the total face irradiation step shown in FIG. 2 
is in the range of 1 through 50%, preferably 5 through 15% of the 
effective exposure beam amount applied on the exposure region 6a of the 
resist layer 2 in the selective irradiation step shown in FIG. 4, by using 
the same exposure device. 
When an exposure device irradiating the ArF excimer laser beam is employed, 
the KrF excimer laser beam may be irradiated under the same condition as 
in the KrF excimer stepper. When an exposure device using a mercury lamp 
irradiating an ultraviolet ray such as g line beam or i line beam, in the 
total face irradiation step shown in FIG. 2, the irradiation may be 
performed by irradiating an ultraviolet ray such as g line beam or i line 
beam by a mercury lamp for an irradiation time period of 50 through 200 
msec by using the opaque reticle 4 having the light transmittance of 1 
through 50%, preferably 5 through 15%, whereas in the selective 
irradiation step shown in FIG. 4, the irradiation may be performed by 
irradiating an ultraviolet ray such as g line beam or i line beam by a 
mercury lamp for an irradiation time period of 50 through 1,000 msec, 
preferably 50 through 200 msec. 
Further, with respect to the resist in the above Examples 1 and 2, the 
resist A and the resist B having different contents of the crosslinking 
agent are shown, however, the invention is not restricted to these 
resists. The resist may include hexamethoxymethylmelamine as the 
crosslinking agent by 10 through 50 wt %, preferably 20 through 40 wt % 
and 1,2,3,4-tetrabromobutane as the acid generating agent by 0.5 through 
20 wt %, preferably 3 through 15 wt %, on the basis of 100 wt % of 
poly-P-hydroxystyrene as the alkali-soluble base resin. 
The resist having such a content is provided with the dissolution rate of 
the resist layer 2 which has been formed on the surface of the substrate 1 
after the step shown in FIG. 1, with respect to the developer, of 1,000 
.ANG./sec or more, preferably 3,000 .ANG./sec or more at the surface layer 
of the formed resist layer 2, the dissolution rate of the resist layer 2 
at the exposure region 6a immediately before developing is in the range of 
approximately 0.1 through 0.5 .ANG./sec with little variation from the 
surface of the resist layer 2 to the surface of the substrate 1, and the 
dissolution rate with respect to the developer in the non-exposure region 
6b is in the range of approximately 800 through 2,000 .ANG./sec with 
little variation from the surface of the resist layer 2 to the surface of 
the substrate 1, which achieves an effect similar to those in Example 1 or 
Example 2. 
Further, although in Example 1 and Example 2, poly-P-hydroxystyrene was 
employed as the alkali-soluble base resin of the resist, the invention is 
not restricted to this resin and it may be a phenolic resin or a novolak 
resin. Although hexamethoxymethylmelamine was employed as the crosslinking 
agent, this invention is not restricted thereto, and it may be 
tetramethoxymethylol urea or dimethylol urea. Although 
1,2,3,4-tetrabromobutane was employed as the acid generating agent, this 
invention is not restricted thereto and it may be 
tris(2,3-dibromopropyl)isocyanurate, 2,3-dibromosulfolane, 
triphenylsulfonium triflate or the like. Although methyl 
3-methoxypropionate is employed as the solvent, this invention is not 
restricted thereto, and may be propylene glycol monomethyl ether acetate, 
diethylene glycol dimethyl ether or the like. In short, the same effect is 
achieved by "a negative type resist which is slightly soluble or insoluble 
to a developer when a chemical change is caused in a substance that has 
been generated by receiving a radiation such as a light beam, an electron 
beam or the like, by baking". 
Moreover, although in Example 1 and Example 2, the resist is "a negative 
type resist which is slightly soluble to a developer when a chemical 
change is caused in a substance that has been generated by receiving a 
radiation, by baking", the resist may be "a negative type resist which is 
slightly soluble or insoluble to a developer when a chemical change is 
caused to a substance by receiving a radiation such as a light beam, an 
electron beam or the like", using polyhydroxystyrene or a novolak resin or 
the like as an alkali-soluble base resin of the resist, 
4,4'-diazide-3,3'-dimethoxybiphenyl or the like as a crosslinking agent. 
EXAMPLE 3 
FIG. 11 through FIG. 17 show Example 3 of this invention, and an 
explanation will be given of a method of forming a resist pattern 
concerning Example 3 in reference to FIG. 11 through FIG. 17 as follows. 
Firstly, the resist A which is the same as the resist A employed in Example 
1, is spincoated on the surface of the substrate 1 as shown in FIG. 11. 
The substrate 1 spincoated with the resist A is prebaked on the hot plate 
3 at 100.degree. C. for 70 seconds, thereby forming the resist layer 2 on 
the surface of the substrate 1. 
As the condition of spincoating, the spincoating was carried out such that 
the film thickness of the resist layer 2 became 1 .mu.m. 
At this instance, the dissolution rate of the resist layer 2 which had been 
formed on the surface of the substrate 1, with respect to a developer, for 
instance, an aqueous solution of 1.23 wt % of tetramethylammonium 
hydroxide (for instance, NMD-3 made by Tokyo Chemicals Co.) was 3,500 
.ANG./sec at the surface layer of the formed resist layer 2. 
The developer of the resist layer 2 is not restricted to this Example and 
may be another developer so far as it is an alkaline aqueous solution. 
Next, as shown in FIG. 12, an exposure device, for instance, a KrF excimer 
stepper (for instance, NSR2005EX8A made by Nippon Kogaku K.K.) is 
employed, the reticle 7 which has been formed with a desired pattern 
similar to that in Example 1, is disposed on the surface of the resist 
layer 2, the KrF excimer laser beam 5 having a wavelength of 248 nm is 
irradiated from above the reticle 7 in a range of 5 through 100 
mJ/cm.sup.2, preferably 10 through 50 mJ/cm.sup.2, wherein the excimer 
laser beam 5 is selectively irradiated on the surface of the resist layer 
through the reticle 7, thereby forming an image on the resist layer 2. 
Accordingly, the resist layer 2 is divided into the exposure region 6a and 
the non-exposure region 6b based on the pattern which has been formed on 
the reticle 7. 
As shown in FIG. 7(b), an acid is generated from an acid generating agent 
in the exposure region 6a of the resist layer 2. The non-exposure region 
6b of the resist layer 2 is in a state as shown by FIG. 7(a). Thereafter, 
as shown in FIG. 13, the baking operation is performed with respect to the 
substrate 1 having the resist layer 2 comprising the exposure region 6a 
and the non-exposure region 6b on the hot plate 3 that is the heating 
means, at 100.degree. C. for 90 seconds. Through this baking operation, in 
the exposure region 6a of the resist layer 2, the acid generated from the 
acid generating agent operates as a catalyst, a crosslinking reaction is 
caused between the crosslinking agent and the base resin, and the exposure 
region 6a of the resist layer 2 is hardened, as shown in FIG. 7(c). This 
baking is called the post exposure baking (PEB). Further, in the 
non-exposure region 6b of the resist layer 2, no crosslinking reaction is 
caused between the crosslinking agent and the base resin since no acid has 
been generated from the acid generating agent. 
Further, by this baking operation, the thickness of the resist layer 2 
which has been formed on the substrate 1, is more or less reduced in 
comparison with the thickness before baking. 
Next, as shown in FIG. 14, the exposure device the same as that employed in 
the selective irradiation step shown in FIG. 12, is employed, the opaque 
reticle 4 having the light transmittance of 10% similar to that used in 
Example 1, is disposed above the surface of the resist layer 2 that has 
been selectively exposed, and the KrF excimer laser beam 5 having the 
wavelength of 248 nm is irradiated from above the opaque reticle 4 in a 
range of 10 through 50 mJ/cm.sup.2, wherein the excimer laser beam 5 is 
irradiated on the total face of the resist layer 2 through the opaque 
reticle 4. Further, although this Example employs the opaque reticle 4 
having the light transmittance of 10%, the light transmittance may be in a 
range of 1 through 50%, preferably 5 through 15%. 
Further, as shown in FIG. 15, the baking is performed by disposing the 
substrate 1 of which total surface of the resist layer 2 has been 
irradiated with the excimer laser beam, on the hot plate 3 that is the 
heating means, at 100.degree. C. for 90 seconds. 
A result as shown in FIG. 17 was obtained by measuring the dissolution rate 
of the resist layer 2 comprising the exposure region 6a and the 
non-exposure region 6b formed as above with respect to the developer 
immediately before developing. In FIG. 17, line A designates the 
dissolution rate of the resist layer 2 distributing from the surface of 
the resist layer 2 to the surface of the substrate 1 in the exposure 
region 6a, whereas line B designates the dissolution rate of the resist 
layer 2 with respect to the developer distributing from the surface of the 
resist layer 2 to the surface of the substrate 1 in the non-exposure 
region 6b. 
The developing is performed by the spray-paddle system for 100 seconds 
using the above developer, or "NMD-3 made by Tokyo Ohka Kogyo Co., LTD", 
or an aqueous solution of 1.23 wt % of tetramethylammonium hydroxide, 
thereby obtaining the resist pattern 8 as shown in FIG. 16. 
Measurement was performed on the resist pattern 8 obtained as above with 
respect to the sectional shape of 0.3 .mu.m line and space pattern, the 
sensitivity of 0.3 .mu.m line and space pattern (exposure beam amount in 
finishing the resist pattern as specified by mask dimensions), the limit 
resolution of line and space pattern, and the resolution depth of focus of 
0.3 .mu.m line and space pattern, whereby a result as shown in FIG. 9 is 
obtained. 
With respect to the sectional shape of the resist pattern 8, although there 
are more or less roundings of the surface portion, there are almost no 
encroachments in the portions of the resist contacting the substrate 1, 
and moreover, the side walls are in an approximately rectangular shape 
having faces orthogonal to the approximately flat substrate 1. The 
sensitivity of 0.3 .mu.m line and space pattern is 55 mJ/cm.sup.2, and the 
limit resolution of line and space pattern is 0.200 .mu.m which is smaller 
than those of Comparative Examples, mentioned later. Therefore, a 
sufficient resolution is provided and the function is improved. The 
resolution depth of focus of 0.3 .mu.m line and space pattern is 1.5 .mu.m 
which is larger than those in Comparative Examples, mentioned later. 
Therefore, a broad range of depth of focus is provided and the function is 
improved. 
The reason of obtaining the resist pattern 8 having the high resolution, 
the broad focus allowance and the good shape is considered to be as 
follows. 
As is apparent from FIG. 17 showing the dissolution rate of the resist 
layer 2 with respect to the developer immediately before developing, the 
dissolution rate of the resist layer 2 with respect to the developer 
distributing from the surface of the resist layer 2 to the surface of the 
substrate 1 in the exposure region 6a, is within the range of 
approximately 0.1 through 0.5 .ANG./sec which stays approximately the 
same, whereas the dissolution rate of the resist layer 2 with respect to 
the developer distributing from the surface of the resist layer 2 to the 
surface of the substrate 1 in the non-exposure exposure region 6b, is 
provided with little variation and within the range of approximately 800 
through 2,000 .ANG./sec. 
Accordingly, in the exposure region 6a of the resist layer 2, the 
effectively absorbed exposure beam amount is increased by the twice 
irradiation steps of the selective irradiation step shown in FIG. 12 and 
the total face irradiation step shown in FIG. 14, the hardening reaction 
is accelerated, the dissolution rate with respect to the developer is 
lowered, and the dissolution rate of the resist layer 2 with respect to 
the developer stays approximately the same from the surface of the resist 
layer 2 to the surface of the substrate 1. The encroachment of the 
portions of the resist pattern 8 which has been preserved after 
development by the developer (corresponding to the exposure region 6a of 
the resist layer 2) contacting the substrate 1, is restrained, and the 
side walls are provided with approximately flat vertical faces. 
Further, the dissolution rate of the resist with respect to the developer 
distributing from the surface of the resist to the surface of the 
substrate 1 in the exposure region 6a of the resist layer 2 because of the 
following reason. The baking step of the resist layer 2 shown in FIG. 13 
is performed between the selective irradiation step of the excimer laser 
beam 5 shown in FIG. 12 and the total irradiation step of the excimer 
laser beam 5 shown in FIG. 14, and therefore, the thickness of the resist 
layer 2 after the selective irradiation step shown in FIG. 12 is different 
from that after the total face irradiation step shown in FIG. 14. 
Accordingly, a standing wave of the excimer laser beam 5 in the selective 
irradiation step shown in FIG. 12 at the exposure region 6a of the resist 
layer 2, functions to cancel with a standing wave of the excimer laser 
beam in the total face irradiation step shown in FIG. 14, whereby the 
dissolution rate of the resist layer 2 stays the same in the resist from 
the surface of the resist layer 2 to the surface of the substrate 1. 
Further, in the non-exposure region 6b of the resist layer 2, the light 
absorption amount of the excimer laser beam 5 in the total face 
irradiation step shown in FIG. 14 is increased in the portions of the 
resist proximate to the surface and the portions of the resist are easy to 
harden. Therefore, the dissolution rate of the resist with respect to the 
developer is lowered to approximately 800 .ANG./sec from the dissolution 
rate of 3,500 .ANG./sec with respect to the developer before the 
irradiation of the excimer laser 5. Although the hardening reaction is 
caused on the topmost surface through the excimer laser beam 5 in the 
total face irradiation step shown in FIG. 14, the lowering of the 
dissolution rate at the topmost surface is smaller than the lowering of 
the dissolution rate at the portions of the resist proximate to the 
surface, due to the evaporation of the acid that has been generated by the 
excimer laser beam 5 or the reaction thereof with basic substances in the 
atmosphere. Further, the dissolution rate of the portions of the resist 
contacting the substrate 1 is mostly enhanced. The dissolution rate of the 
resist layer 2 with respect to the developer distributing from the surface 
of the resist layer 2 to the surface of the substrate 1 is provided with 
little variation and within the range of approximately 800 through 2,000 
.ANG./sec. Further, the difference between the dissolution rates of the 
resist layer 2 of the exposure region 6a and the non-exposure region 6b on 
the side of the portions of the resist contacting the substrate 1, is 
larger than the difference between the dissolution rates of the resist 
layer 2 of the exposure region 6a and the non-exposure region 6b at the 
surface portion of the resist layer 2. 
Accordingly, there is a difference by four digits or more between the 
dissolution rate of the resist layer 2 at the non-exposure region 6b and 
the dissolution rate of the resist layer 2 at the exposure region 6a 
throughout the resist from the surface of the resist layer 2 to the 
surface of the substrate 1, the resist pattern can be formed in a good 
shape even if it is of 0.3 .mu.m or less, and the difference of the 
dissolution rates therebetween at the portions of the resist contacting 
the substrate 1 is larger than the difference of the dissolution rates 
therebetween on the surface portion of the resist layer 2. Therefore, the 
high resolution can be achieved. 
Further, although in Example 3, for instance, the KrF excimer stepper is 
employed both in the selective irradiation step shown in FIG. 12 and the 
total face irradiation step shown in FIG. 14, it may be an exposure device 
irradiating an ArF excimer laser beam, or may be an exposure device using 
a mercury lamp irradiating an ultraviolet ray such as g line beam or i 
line beam. In short, the same effect is achieved when the effective 
exposure beam amount applied on the resist layer 2 in the total face 
irradiation step shown in FIG. 14, is in a range of 1 through 50%, 
preferably 5 through 15% of the effective exposure beam amount applied on 
the exposure region 6a of the resist layer 2 in the selective irradiation 
step shown in FIG. 12. 
When an exposure device irradiating the ArF excimer laser beam is employed, 
the ArF excimer laser beam may be irradiated under the same condition as 
in the KrF excimer stepper. When an exposure device using a mercury lamp 
irradiating an ultraviolet ray such as g line beam or i line beam, the 
ultraviolet ray such as g line beam or i line beam may be irradiated by a 
mercury lamp in the irradiation time period of 50 through 200 msec by 
using the opaque reticle 4, the light transmittance of which is in a range 
of 1 through 50%, preferably 5 through 15%, in the total face irradiation 
step shown in FIG. 14, and the ultraviolet ray such as g line beam or i 
line beam may be irradiated by a mercury lamp in the irradiation time 
period of 50 through 1,000 msec, preferably 50 through 200 msec in the 
selective irradiation step shown by FIG. 12. 
Further, although the resist A is employed in Example 3, the resist B in 
Example 2 may be used. Further, the resist may include 10 through 50 wt %, 
preferably 20 through 40 wt % of hexamethoxymethylmelamine as the 
crosslinking agent and 0.5 through 20 wt %, preferably 3 through 15 wt % 
of 1,2,3,4-tetrabromobutane as the acid generating agent, on the basis of 
100 wt % of poly-P-hydroxystyrene as the alkali-soluble base resin. 
In the resist having such contents, after the step shown in FIG. 11, the 
dissolution rate of the resist layer 2 that has been formed on the surface 
of the substrate 1, with respect to the developer, is 1,000 .ANG./sec or 
more, preferably 3,000 .ANG./sec or more at the surface layer of the 
formed resist layer 2, the dissolution rate of the resist layer 2 at the 
exposure region 6a immediately before developing is provided with little 
variation and within a range of approximately 0.1 through 0.5 .ANG./sec 
distributing from the surface of the resist layer 2 to the surface of the 
substrate 1, whereas the dissolution rate with respect to the developer in 
the non-exposure region 6b is provided with little variation and within a 
range of approximately 800 through 2,000 .ANG./sec distributing from the 
surface of the resist layer 2 to the surface of the substrate 1, whereby 
an effect similar to that in Example 3 is achieved. 
Further, although poly-P-hydroxystyrene is employed in Example 3 as an 
alkali-soluble base resin of the resist, this invention is not restricted 
to the resin, and it may be a phenolic resin, a novolak resin or the like. 
Although hexamethoxymethylmelamine is employed as the crosslinking agent, 
this invention is not restricted thereto, and it may be 
tetramethoxymethylol urea or dimethylol urea or the like. Although 
1,2,3,4-tetrabromobutane is employed as the acid generating agent, this 
invention is not restricted thereto, and it may be 
tris(2,3-dibromopropyl)isocyanurate, 2,3-dibromosulfolane, 
triphenylsulfonium triflate or the like. Although methyl 
3-methoxypropionate is employed as the solvent, this invention is not 
restricted thereto, and it may be propylene glycol monomethyl ether 
acetate, diethylene glycol dimethyl ether or the like. In short, the same 
effect is achieved by "a negative type resist which is slightly soluble or 
insoluble to a developer when a chemical change is caused in a substance 
that has been generated by receiving a radiation such as a light beam, an 
electron beam or the like, by baking". 
Further, although Example 3 employs "a negative type resist which is 
slightly soluble to a developer when a chemical change is caused in a 
substance that has been generated by receiving a radiation, by baking", as 
a resist, the resist may be "a negative type resist which is slightly 
soluble or insoluble to a developer by causing a chemical change by 
receiving a radiation such as a light beam, an electron beam or the like", 
using polyhydroxystyrene or a novolak resin or the like as the 
alkali-soluble base resin of the resist, and 
4,4'diazide-3,3'-dimethoxybiphenyl or the like as the crosslinking agent. 
EXAMPLE 4 
FIG. 18 through FIG. 22 show Example 4 of this invention, and an 
explanation will be given of a method of forming a resist pattern with 
respect to Example 4 in reference to FIG. 18 through FIG. 22 as follows. 
Firstly, as shown in FIG. 18, the resist A that is the same with the resist 
A employed in Example 1, is spincoated on the surface of the substrate 1, 
as shown in FIG. 18. The substrate 1 spincoated with the resist A is 
prebaked above the hot plate 3 that is the heating means, at 100.degree. 
C. for 70 seconds. 
As the condition of spincoating, the spincoating operation was performed 
such that the film thickness of the resist layer 2 after prebaking became 
1 .mu.m. 
At this instance, the dissolution rate of the resist layer 2 that had been 
formed on the surface of the substrate 1, with respect to a developer, for 
instance, an aqueous solution of 1.23 wt % of tetramethylammonium 
hydroxide (for instance, NMD-3 made by Tokyo Ohka Kogyo Co., LTD), was 
3,500 .ANG./sec at the surface layer of the formed resist layer 2. 
Further, the developer for the resist layer 2 is not restricted to the 
above Example, and it may be any developer so far as it is an alkaline 
aqueous solution. 
Next, as shown in FIG. 19, an exposure device, for instance, a KrF excimer 
stepper (for instance, NSR2005EX8A made by Nippon Kogaku K.K.) is used, 
the reticle 9 formed with a desired pattern wherein the light 
transmittance of the light transmitting region is 100% and the light 
transmittance of the light shielding layer is 10%, is disposed above the 
surface of the resist layer 2, the KrF excimer laser beam 5 having the 
wavelength of 248 nm is irradiated from above the reticle 9, in a range of 
5 through 100 mJ/cm.sup.2, preferably 10 through 50 mJ/cm.sup.2, whereby 
the excimer laser 5 is irradiated on the surface of the resist layer 2 
through the reticle 9, thereby forming an image on the resist layer 2. 
Accordingly, the resist layer 2 is divided into the exposure region 6a and 
the non-exposure region 6b based on a pattern formed on the reticle 7, and 
the non-exposure region 6b is irradiated with the exposure beam amount 
that is 10% of the exposure beam amount irradiated on the exposure region 
6a. At this instance, as shown in FIG. 7(b), an acid is generated from an 
acid generating agent in the exposure region 6a of the resist layer 2. 
The reticle 9 is formed with a light shielding layer (the light 
transmittance is 10%) comprising a desired pattern or a light shielding 
layer corresponding to the portion of the resist to be removed and a light 
transmitting region corresponding to the portion of the resist to be 
preserved, on its face of a transparent substrate such as glass. The light 
shielding layer is formed by a film of chromium (Cr), molybdenum silicide 
(MoSi) or oxinitrides of these. 
Although the light transmittance of the light shielding layer of the 
reticle 9 is 10%, it may be in a range of 1 through 20%, preferably 3 
through 15%. Further, the light shielding layer may be a half tone mask 
employed in the phase shift method which is applicable to a positive type 
resist. 
Thereafter, as shown in FIG. 20, a baking operation is performed with 
respect to the substrate 1 having the resist layer 2 comprising the 
exposure region 6a and the non-exposure region 6b on the hot plate 3 that 
is the heating means, at 100.degree. C. for 90 seconds. Through this 
baking operation, in the exposure region 6a of the resist layer 2, an acid 
generated from an acid generating agent operates as a catalyst as shown in 
FIG. 7(c), a crosslinking reaction is caused between the crosslinking 
agent and the base resin, whereby the exposure region 6a of the resist 
layer 2 is hardened. The baking is called the post exposure baking (PEB). 
A result as shown in FIG. 22 is obtained by measuring the dissolution rate 
of the resist layer 2 comprising the exposure region 6a and the 
non-exposure region 6b formed as above, with respect to the developer 
immediately before developing. In FIG. 22, line A designates the 
distribution of the dissolution rate of the resist layer 2 with respect to 
the developer from the surface of the resist layer 2 to the surface of the 
substrate 1 in the exposure region 6a, whereas line B designates the 
distribution of the dissolution rate of the resist layer 2 with respect to 
the developer from the surface of the resist layer 2 to the surface of the 
substrate 1 in the non-exposure region 6b. 
Further, the developing is performed by the spray-paddle system for 100 
seconds by using the developer, or "NMD-3 made by Tokyo Ohka Kogyo Co., 
LTD " or an aqueous solution of 1.23 wt % of tetramethylammonium 
hydroxide, by which the resist pattern 8 as shown in FIG. 21 is provided. 
A result as shown in FIG. 9 is provided with respect to the resist pattern 
8 obtained as above, by measuring the sectional shape of 0.3 .mu.m line 
and space pattern, the sensitivity of 0.3 .mu.m line and space pattern 
(exposure beam amount for finishing the resist pattern as specified by 
mask dimensions), the limit resolution of line and space pattern and the 
resolution depth of focus of 0.3 .mu.m line and space pattern. 
In the sectional shape of the resist pattern 8, there are almost no 
roundings at the surface portion and encroachments at the portions of the 
resist contacting the substrate 1, and it is almost in a rectangular shape 
although there is more or less waviness on the side walls. The sensitivity 
of 0.3 .mu.m line and space pattern is 45 mJ/cm.sup.2 and the limit 
resolution of line and space pattern is 0.150 which are smaller than those 
of Comparative Examples, mentioned later. Therefore, a sufficient 
resolution is provided and the function is improved. The resolution depth 
of focus of 0.3 .mu.m line and space pattern is 2.1 .mu.m which is larger 
than those in Comparative Examples, mentioned later. Therefore, a broad 
range of depth of focus is provided and the function is improved. 
The reason of obtaining the resist pattern 8 having the high resolution, 
the broad focus allowance and the good shape is considered to be as 
follows. 
As is apparent from FIG. 22 showing the dissolution rate of the resist 
layer 2 with respect to the developer immediately before developing, the 
dissolution rate of the resist layer 2 distributing from the surface of 
the resist layer 2 to the surface of the substrate 1 in the exposure 
region 6a is within a range of approximately 0.09 through 0.2 .ANG./sec, 
and the dissolution rate of the resist layer 2 distributing from the 
surface of the resist layer 2 to the surface of the substrate 1 in the 
non-exposure region 6b, is provided with little variation and within a 
range of approximately 900 through 2,000 .ANG./sec. 
Accordingly, the dissolution rate of the resist layer 2 with respect to the 
developer in the exposure region 6a is lowered, by which roundings of the 
surface portion of the resist pattern 8 that has been preserved after 
developing by the developer (corresponding to the exposure region 6a of 
the resist layer 2) and encroachments of the portions of the resist 
contacting the substrate 1, are restrained. 
Further, with respect to the non-exposure region 6b of the resist layer 2, 
the portions of the resist proximate to the surface are applied with a 
large amount of light absorption of the excimer laser beam 5 in the 
irradiation step as shown in FIG. 19, and the portions are easy to harden. 
The dissolution rate with respect to the developer is lowered from 3,500 
.ANG./sec before irradiating the excimer laser beam 5 to approximately 900 
.ANG./sec. Although the hardening reaction is caused on the topmost 
surface by the excimer laser beam 5 in the irradiation step shown in FIG. 
19, the lowering of the dissolution rate is smaller than the lowering the 
dissolution rate of the portions of the resin proximate to the surface due 
to evaporation of the acid that has been generated by the excimer laser 
beam 5 or a reaction thereof with basic substances in the atmosphere. 
Further, the dissolution rate with respect to the developer at the 
portions of the resist contacting the substrate 1 is mostly enhanced. The 
dissolution rate of the resist layer 2 with respect to the developer 
distributing from the surface of the resist layer 2 to the surface of the 
substrate 1 is provided with little variation and within the range of 
approximately 900 through 2,000 .ANG./sec. Further, the difference between 
the dissolution rates of the resist layer 2 of the exposure region 6a and 
the non-exposure region 6b on the side of the portions of the resist 
contacting the substrate 1, is larger than the difference of the 
dissolution rates of the resist layer 2 between the exposure region 6a and 
the non-exposure region 6b on the surface portion of the resist layer 2. 
Accordingly, there is a difference by four digits or more between the 
dissolution rate of the resist layer 2 in the non-exposure region 6b and 
the dissolution rate of the resist layer 2 in the exposure region 6a 
throughout the resin from the surface of the resist layer 2 to the surface 
of the substrate 1. The resist pattern can be formed in a good shape even 
if it is a pattern of 0.3 .mu.m or less. The difference of the dissolution 
rates at the portions of the resist contacting the substrate 1, is larger 
than the difference of the dissolution rates on the surface portion of the 
resist layer 2. Therefore, the high resolution can be achieved. 
Although the irradiation step shown in FIG. 19, uses, for instance, the KrF 
excimer stepper, in Example 4, it may be replaced by an exposure device 
irradiating an ArF excimer laser beam, or an exposure device using a 
mercury lamp irradiating an ultraviolet ray such as g line beam or i line 
beam. In short, the same effect is achieved when the effective exposure 
beam amount applied on the non-exposure region 6b of the resist layer 2 
which is irradiated by transmitting through the light shielding layer, is 
within a range of 1 through 20%, preferably 3 through 15% of the effective 
exposure beam amount to the exposure region 6a of the resist layer 2 which 
is irradiated by transmitting through the light transmitting region, by 
using the reticle 9. 
When the exposure device irradiating the ArF excimer laser beam is 
employed, the ArF excimer laser beam may be irradiated under the same 
condition as in the KrF excimer stepper. When the exposure device using 
the mercury lamp irradiating an ultraviolet ray such as g line beam or i 
line beam, is employed, an ultraviolet ray such as g line beam or i line 
beam may be irradiated by the mercury lamp in the irradiation time period 
of 100 through 300 msec by using the reticle 9 having the light 
transmittance of the light shielding layer in the range of 1 through 20%, 
preferably 3 through 15%, in the irradiation step shown in FIG. 19. 
Although in Example 4, the resist A is employed, the resist B in Example 2 
may be used. The resist may include 10 through 50 wt %, preferably 20 
through 40 wt % of hexamethoxymethylmelamine as the crosslinking agent and 
0.5 through 20 wt %, preferably 5 through 15 wt % of 
1,2,3,4-tetrabromobutane as the acid generating agent, on the basis of 100 
wt % of poly-P-hydroxymethylene as the alkali-soluble base resin. 
In the resist having such contents, the dissolution rate of the resist 2 
that has been formed on the surface of the substrate 1 after the step 
shown in FIG. 18, with respect to the developer, is 1,000 .ANG./sec or 
more, preferably 3,000 .ANG./sec or more at the surface layer of the 
formed resist layer 2. The dissolution rate of the resist layer 2 in the 
exposure region 6a immediately before developing is within a range of 
approximately 0.09 through 0.2 .ANG./sec distributing from the surface of 
the resist layer 2 to the surface of the substrate 1, whereas the 
dissolution rate with respect to the developer in the non-exposure region 
6b, is provided with little variation and within a range of approximately 
900 through 2,000 .ANG./sec distributing from the surface of the resist 
layer 2 to the surface of the substrate 1. Therefore, an effect the same 
as Example 4 is achieved. 
Although Example 4 employs poly-P-hydroxystyrene as the alkali-soluble base 
resin of the resist, this invention is not restricted thereto, and it may 
be a phenolic resin, a novolak resin or the like. Although 
hexamethoxymethylmelamine is employed as the crosslinking agent, the 
invention is not restricted thereto, and it may be tetramethoxymethylol 
urea, dimethylol urea or the like. Although 1,2,3,4-tetrabromobutane is 
employed as the acid generating agent, the invention is not restricted 
thereto, and it may be tris(2,3-dibromopropyl-isocyanurate, 
2,3-dibromosulfolane, triphenylsulfonium triflate or the like. Although 
methyl 3-methoxypropionate is employed as the solvent, the invention is 
not restricted thereto, and it may be propylene glycol monomethyl ether 
acetate, diethylene glycol dimethyl ether or the like. In short, the same 
effect is achieved when the resist is "a negative type resist which is 
slightly soluble or insoluble to a developer when a chemical change is 
caused in a substance which has been generated by receiving a radiation 
beam such as a light beam, an electron beam or the like, by baking". 
Furthermore, although Example 4 employs as a resist, "a negative type 
resist which is slightly soluble to a developer when a chemical change is 
caused in a substance which has been generated by receiving a radiation, 
by baking", the resist may be a negative type resist which is slightly 
soluble or insoluble to a developer by causing a chemical change by 
receiving a radiation such as a light beam, an electron beam or the like", 
using polyhydroxystyrene, a novolak resin or the like as the 
alkali-soluble base resin of the resist, and 
4,4'-diazide-3,3'-dimethoxybiphenyl or the like as the crosslinking agent. 
The resolution of the resist pattern is further enhanced in Example 4, when 
the reticle 9 uses a half tone mask wherein the light shielding layer is a 
phase shifter layer for transmitting a radiation having a first phase that 
is different from a second phase of a radiation for transmitting through 
the light transmitting region, wherein the first phase is different from 
the second phase, for instance, by 180.degree. C. 
Next, an explanation will be given of Comparative Examples having the 
resist A (Comparative Example 1 ) and the resist B (Comparative Example 2) 
wherein resist patterns are formed by a conventional method of forming a 
resist pattern as shown in FIG. 23 through FIG. 26, to compare these with 
the above Examples. 
COMATIVE EXAMPLE 1 
Firstly, as shown in FIG. 23, the resist A which has been employed in 
Example 1, is spincoated on the surface of the substrate 1. The substrate 
1 spincoated with the resist A is prebaked above the hot plate 3 that is 
the heating means, at 100.degree. C. for 70 seconds, by which the resist 
layer 2 is formed on the surface of the substrate 1. 
As the spincoating condition, the spincoating was performed such that the 
film thickness of the resist layer 2 became 1 .mu.m after prebaking. 
At this instance, the dissolution rate of the resist layer 2 which had been 
formed on the surface of the substrate 1, with respect to a developer for 
the resist layer 2, for instance, an aqueous solution of 1.23 wt % of 
tetramethylammonium hydroxide (for instance, NMD-3 made by Tokyo Ohka 
Kogyo Co., LTD) was 3,500 .ANG./sec at the surface layer of the formed 
resist layer 2. 
Next, as shown in FIG. 24, an exposure device, for instance, a KrF excimer 
stepper (for instance, NSR2005EX8A made by Nippon Kogaku K.K.) is 
employed, the reticle 7 formed with a desired pattern similar to that 
employed in the selective radiation step of Example 1 shown in FIG. 4, is 
disposed above the surface of the resist layer 2, and the KrF excimer 
laser beam 5 having the wavelength of 248 nm is irradiated from above the 
reticle 7 in a range of 5 through 100 mJ/cm.sup.2, wherein the excimer 
laser beam 5 is selectively irradiated on the surface of the resist layer 
2 through the reticle 7, by which an image is formed on the resist layer 
2. The resist layer 2 is divided into the exposure region 6a and the 
non-exposure region 6b based on the pattern formed on the reticle 7. 
Thereafter, as shown in FIG. 25, the baking operation is performed with 
respect to the substrate having the resist layer 2 comprising the exposure 
region 6a and the non-exposure region 6b on the hot plate 3 that is the 
heating means, at 100.degree. C. for 90 seconds. 
A result as shown in FIG. 27 is obtained by measuring the dissolution rate 
of the resist layer 2 comprising the exposure region 6a and the 
non-exposure region 6b formed as above with respect to the developer 
immediately before developing. In FIG. 27, line A designates the 
distribution of the dissolution rate of the resist layer 2 from the 
surface of the resist layer 2 to the surface of the substrate 1 in the 
exposure region 6a, whereas line B designates the distribution of the 
dissolution rate of the resist layer 2 with respect to the developer from 
the surface of the resist layer 2 to the surface of the substrate 1 in the 
non-exposure region 6b. 
As is apparent from FIG. 27, as the dissolution rate of the resist layer 2 
at this instance with respect to the developer immediately before 
developing, the dissolution rate with respect to the developer in the 
exposure region 6a, is wavily distributed within a range of approximately 
0.1 through 5 .ANG./sec from the surface of the resist layer 2 to the 
surface of the substrate 1, whereas the dissolution rate with respect to 
the developer in the non-exposure region 6b, stays approximately the same 
with the dissolution rate of 3,500 .ANG./sec at the surface layer of the 
resist layer 2 after the step shown in FIG. 23. The dissolution rate 
varies from the surface of the resist layer 2 to the surface of the 
substrate 1 within a range of approximately 1,500 through 3,500 .ANG./sec. 
Further, the developing operation is performed through the spray-paddle 
system for 100 seconds by using the developer, by which the resist pattern 
8 shown in FIG. 26 is provided. 
A result as shown in FIG. 9 is obtained in the resist pattern 8 provided as 
above, by measuring the sectional shape of 0.3 .mu.m line and space 
pattern, the sensitivity of 0.3 .mu.m line and space pattern (exposure 
beam amount in finishing resist pattern as specified by mask dimensions), 
the limit resolution of line and space pattern, and the resolution depth 
of focus of 0.3 .mu.m line and space pattern. 
The sectional shape of the resist pattern 8 is in an elliptic shape wherein 
roundings are caused on the surface portion and encroachments are caused 
at the portions of the resist contacting the substrate 1. The sensitivity 
of 0.3 .mu.m line and space pattern is 70 mJ/cm.sup.2 and the limit 
resolution of line and space pattern is 0.300 .mu.m which are large 
values. The resolution depth of focus of 0.3 .mu.m line and space pattern 
is 0 .mu.m which is the smallest value. 
COMATIVE EXAMPLE 2 
In Comparative Example 2, only the composition of the resist is different 
from that in Comparative Example 1, and the resist B in Example 2 is 
employed in place of the resist A. 
In Comparative Example 2 in which the resist pattern 8 is formed in 
accordance with the order of steps as shown by FIG. 23 through FIG. 26 
similar to Comparative Example 1, after the step shown by FIG. 23, the 
dissolution rate of the resist layer 2 with respect to the developer which 
has been formed on the surface of the substrate 1, is 1,500 .ANG./sec at 
the surface layer of the formed resist layer 2. A result as shown in FIG. 
28 is obtained by measuring the dissolution rate of the resist layer 2 
comprising the exposure region 6a and the non-exposure region 6b with 
respect to the developer immediately before developing, after the step 
shown in FIG. 25. In FIG. 28, line A designates the distribution of the 
dissolution rate of the resist layer 2 with respect to the developer from 
the surface of the resist layer 2 to the surface of the substrate 1 in the 
exposure region 6a, whereas line B designates the distribution of the 
dissolution rate of the resist layer 2 with respect to the developer from 
the surface of the resist layer 2 to the surface of the substrate 1 in the 
non-exposure region 6b of the resist layer 2. 
As is apparent from FIG. 28, as the dissolution rate of the resist layer 2 
at this instance with respect to the developer immediately before 
developing, the dissolution rate with respect to the developer in the 
exposure region 6a is wavily distributed within a range of approximately 
0.1 through 5 .ANG./sec, from the surface of the resist layer 2 to the 
surface of the substrate 1, whereas the dissolution rate with respect to 
the developer in the non-exposure region 6b on the surface of the resist 
layer 2, is approximately equal to the dissolution rate of 1,500 .ANG./sec 
at the surface layer of the resist layer 2 after the step shown in FIG. 23 
and the dissolution rate is provided with little variation and within a 
range of approximately 950 through 1,500 .ANG./sec distribution from the 
surface of the resist layer 2 to the surface of the substrate 1. 
A result as shown in FIG. 9 is obtained for the resist pattern 8 provided 
as above, by measuring the sectional shape of 0.3 .mu.m line and space 
pattern, the sensitivity of 0.3 .mu.m line and space pattern (exposure 
beam amount in finishing resist pattern as specified by mask dimensions), 
the limit resolution of line and space pattern and the resolution depth of 
focus of 0.3 .mu.m line and space pattern. 
As the sectional shape of the resist pattern 8, there are roundings on the 
surface portion and encroachments at the portions of the resin contacting 
the substrate 1, and the side walls are provided with a wavy shape. The 
sensitivity of 0.3 .mu.m line and space pattern is 50 mJ/cm.sup.2, and the 
limit resolution of line and space pattern is 0.250 .mu.m which is a large 
value. The resolution depth of focus of 0.3 .mu.m line and space pattern 
is 0.9 .mu.m which is a small value. 
As is apparent from FIG. 9, in contrast to the resist patterns in 
Comparative Example 1 and Comparative Example 2, those shown in Examples 1 
through 4, are provided with high sensitivity, high resolution prevailing 
over a fine pattern and a broad range of depth of focus. The sectional 
shape of the resist pattern has advantages in which no roundings of the 
surface portion, and no encroachments of the portions of the resist 
contacting the substrate 1 are formed, and the side faces of which are 
flat. 
The first aspect of this invention is a negative type resist in which an 
alkali-soluble base resin, a crosslinking agent and an acid generating 
agent are dissolved in a solvent, wherein 10 through 50 wt % of the 
crosslinking agent and 0.5 through 20 wt % of the acid generating agent on 
the basis of 100 wt % of the alkali-soluble base resin are dissolved in 
the solvent. Accordingly, the dissolution rate of the resist layer of this 
negative type resist with respect to the developer is enhanced after 
coating it on the surface of the substrate and before irradiating the 
radiation. Therefore, in developing the resist layer, the contrast of the 
dissolution rate with respect to the exposure region of the resist layer 
as compared with that of the non-exposure region thereof, is promoted. The 
reduction of film and the undercut of the resist pattern are restrained. 
Thereby, an effect is achieved wherein the resist pattern having a high 
resolution is provided. 
The second aspect of this invention is a negative type resist in which an 
alkali-soluble base resin, a crosslinking agent and an acid generating 
agent are dissolved in a solvent, wherein 20 through 40 wt % of the 
crosslinking agent and 3 through 15 wt % of the acid generating agent on 
the basis of 100 wt % of the alkali-soluble base resin are dissolved in 
the solvent. Therefore, the dissolution rate of the resist layer of this 
negative type resist with respect to the developer is enhanced after 
coating it on the surface of the substrate and before irradiating the 
radiation. Therefore, in developing, the contrast of the dissolution rate 
with respect to the developer in the exposure region of the resist layer 
as compared with that in the non-exposure region thereof is promoted. The 
reduction of the film and the undercut of the resist pattern are 
restrained. Thereby, an effect is achieved wherein the resist pattern 
having a high resolution is provided. 
The third aspect of this invention a method of forming a resist pattern 
comprising: a step of forming a resist layer comprising a negative type 
resist of which dissolution rate with respect to a developer is 3,000 
.ANG./sec or more at a surface layer of the resist layer, on a surface of 
a substrate by coating the negative type resist on the surface of the 
substrate and by prebaking the negative type resist, said negative type 
resist becoming slightly soluble or insoluble to the developer when a 
chemical change is caused to a substance generated by receiving a 
radiation such as a light beam or an electron beam by baking, or when a 
chemical change is caused in a substance by receiving the radiation; a 
total face irradiation step for irradiating the radiation on a total of 
the surface of the resist layer through an opaque reticle; a selective 
irradiation step for irradiating the radiation on the surface of the 
resist layer through a reticle formed with a desired pattern; and a step 
of providing a resist pattern by developing the resist layer irradiated 
with the radiation in the total face irradiation step and the selective 
irradiation step by the developer. Therefore, in developing, the contrast 
of the dissolution rate with respect to the developer in the exposure 
region of the resist layer as compared with that in the non-exposure 
region thereof, is enhanced especially on the side of the portions of the 
resist contacting the substrate. The dissolution rates in the exposure 
region of the resist layer on the surface portion and at the portions 
thereof contacting the substrate are lowered. The difference between the 
dissolution rates in the exposure region and the non-exposure region of 
the resist layer on the side of the portions thereof contacting the 
substrate, is larger than the difference between the dissolution rates in 
the exposure region and the non-exposure region of the resist layer on the 
surface portion. The reduction of the film and the undercut of the resist 
pattern are restrained. Thereby, an effect is achieved wherein the resist 
pattern having a high resolution and an improved sectional shape is 
provided. 
The fourth aspect of this invention is a method of forming a resist pattern 
comprising: a step of forming a resist layer comprising a negative type 
resist on a surface of the resist by coating the negative type resist on 
the surface of the substrate and by prebaking the negative type resist, 
said negative type resist becoming slightly soluble or insoluble to a 
developer when a chemical change is caused in a substance generated by 
receiving a radiation such as a light beam or an electron beam by baking; 
a total face irradiation and baking step for irradiating the radiation on 
a total of a surface of the resist layer through an opaque reticle and 
baking the resist layer thereafter; a selective irradiation and baking 
step for irradiating the radiation on the surface of the resist layer 
through a reticle formed with a desired pattern and baking the resist 
layer thereafter; and a step of providing a resist pattern by developing 
the resist layer irradiated with the radiation in the total face 
irradiation and baking step and the selective irradiation and baking step. 
Therefore, in developing, the dissolution rates on the surface portion and 
at the portions contacting the substrate in the exposure region of the 
resist layer are lowered. The difference between the dissolution rates in 
the exposure region and the non-exposure region of the resist layer on the 
side of the portions of the resist contacting the substrate, is larger 
than the difference between the dissolution rates in the exposure region 
and the non-exposure region of the resist layer on the surface portion. 
Further, the influence of the standing wave of the radiation in the 
exposure region of the resist layer is reduced. The reduction of film and 
the undercut of the resist pattern are restrained. Thereby, an effect is 
achieved wherein the resist pattern having a high resolution approximately 
flat side walls and a good sectional shape are provided. 
The fifth aspect of this invention is a method of forming a resist pattern 
comprising a step of forming a resist layer comprising a negative type 
resist on a surface of a substrate by coating the negative type resist on 
the surface of the substrate and prebaking the negative type resist, said 
negative type resist becoming slightly soluble or insoluble to a developer 
when a chemical change is caused in a substance generated by receiving a 
radiation such as a light beam or an electron beam by baking or when a 
chemical change is caused in a substance by receiving the irradiation; a 
total face irradiation step for irradiating the radiation on a total of a 
surface of the resist layer; a selective irradiation step for irradiating 
the radiation on the surface of the resist layer through a reticle formed 
with a desired pattern; a step of providing a resist pattern by developing 
the resist layer irradiated with the radiation in the total face 
irradiation step and the selective irradiation step by the developer; and 
wherein a first effective exposure amount applied on the resist layer 
irradiated with the radiation in the total face irradiation step is 5 
through 15% of a second effective exposure amount applied on an exposure 
region of the resist layer irradiated with the radiation in the selective 
irradiation step. Therefore, in developing, the dissolution rates in the 
exposure region of the resist layer on the surface portion and at the 
portions thereof contacting the substrate are lowered. The difference 
between the dissolution rates in the exposure region and the non-exposure 
region of the resist layer on the side of the portions of the resist 
contacting the substrate, is larger than the difference between the 
dissolution rates in the exposure region and the non-exposure region of 
the resist layer on the surface portion. The reduction of the film and the 
undercut of the resist pattern are restrained. Thereby, an effect is 
achieved wherein the resist pattern having a high resolution and a good 
sectional shape are provided. 
The sixth aspect of this invention is a method of forming a resist pattern 
comprising: a step of forming a resist layer comprising a negative type 
resist on a surface of a substrate by coating the negative type resist on 
the surface of the substrate and by prebaking the negative type resist, 
said negative type resist becoming slightly soluble or insoluble to a 
developer when a chemical change is caused in a substance generated by 
receiving a radiation such as a light beam or an electron beam by baking 
or when a chemical change is caused in a substance by receiving the 
radiation; an irradiation step for irradiating the radiation on a surface 
of the resist layer through a reticle formed with a desired pattern 
comprising a light transmitting region and a light shielding layer having 
a light transmittance of 1 through 20%; and a step of providing a resist 
pattern by developing the resist layer irradiated with the radiation in 
the irradiation step by the developer. Therefore, the dissolution rates in 
the exposure region of the resist layer on the surface portion and the 
portions thereof contacting the substrate are lowered. The difference 
between the dissolution rates in the exposure region and the non-exposure 
region of the resist layer on the side of the portions of the resist 
contacting the substrate, is larger than the difference between the 
dissolution rates in the exposure region and the non-exposure region of 
the resist layer on the surface portion. The reduction of the film and the 
undercut of the resist pattern are restrained. Thereby, an effect is 
achieved wherein the resist pattern having a high resolution and a good 
sectional shape are provided. 
The seventh aspect of this invention is a method of forming a resist 
pattern comprising: a resist layer forming step for forming a resist layer 
comprising a negative type resist on a surface of a substrate by coating 
the negative type resist on the surface of the substrate and by prebaking 
the negative type resist, said negative type resist becoming slightly 
soluble or insoluble to a developer when a chemical change is caused in a 
substance generated by receiving a radiation such as a light beam or an 
electron beam by baking or when a chemical change is caused in a substance 
by receiving the radiation; an irradiation step for irradiating the 
radiation on a surface of the resist layer through a reticle formed with a 
desired pattern comprising a light transmitting region and a light 
shielding layer having a light transmittance of 3 through 15%; and a step 
for providing a resist pattern by developing the resist layer irradiated 
with the radiation in the irradiation step by the developer. Therefore, 
the dissolution rates in the exposure region of the resist layer on the 
surface portion and the portions of the resist contacting the substrate 
are lowered. The difference between the dissolution rates in the exposure 
region and the non-exposure region of the resist layer on the side of the 
portions of the resist layer contacting the substrate, is larger than the 
difference between the dissolution rates in the exposure region and the 
non-exposure region of the resist layer on the surface portion. The 
reduction of the film and the undercut of the resist pattern are 
restrained. Thereby, an effect is achieved wherein the resist pattern 
having a high resolution and a good sectional shape is provided.