U.S. patent application number 14/105768 was filed with the patent office on 2015-01-29 for resist material and pattern forming method using same.
This patent application is currently assigned to KABUSHIKI KAISHA TOSHIBA. The applicant listed for this patent is KABUSHIKI KAISHA TOSHIBA. Invention is credited to Kei Kobayashi, Seiji Morita.
Application Number | 20150028524 14/105768 |
Document ID | / |
Family ID | 52389827 |
Filed Date | 2015-01-29 |
United States Patent
Application |
20150028524 |
Kind Code |
A1 |
Kobayashi; Kei ; et
al. |
January 29, 2015 |
RESIST MATERIAL AND PATTERN FORMING METHOD USING SAME
Abstract
In one embodiment, a resist material to be used in an imprint
process includes a diluent monomer having a hydroxyl group and at
least one functional group selected from a vinyl ether group, an
epoxy group and an oxetanyl group. The material further includes a
dendrimer having at least two reactive groups for photo-cationic
polymerization. The material further includes a photo-acid
generator as a polymerization initiator.
Inventors: |
Kobayashi; Kei;
(Yokohama-Shi, JP) ; Morita; Seiji; (Tokyo,
JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
KABUSHIKI KAISHA TOSHIBA |
Tokyo |
|
JP |
|
|
Assignee: |
KABUSHIKI KAISHA TOSHIBA
Tokyo
JP
|
Family ID: |
52389827 |
Appl. No.: |
14/105768 |
Filed: |
December 13, 2013 |
Current U.S.
Class: |
264/447 ;
264/293; 522/168; 522/170; 522/182 |
Current CPC
Class: |
C08F 2/48 20130101; C08F
216/36 20130101; C08F 216/1416 20130101; C08G 65/22 20130101; C08G
59/02 20130101; C08G 65/18 20130101; C08G 65/2609 20130101; C08L
71/02 20130101; C08L 71/02 20130101; C08F 20/02 20130101; B29K
2101/10 20130101; G03F 7/0002 20130101; C08G 65/105 20130101; C08L
101/005 20130101 |
Class at
Publication: |
264/447 ;
522/168; 522/170; 522/182; 264/293 |
International
Class: |
B29C 59/16 20060101
B29C059/16; B29C 59/00 20060101 B29C059/00; C08F 20/02 20060101
C08F020/02; C08G 65/26 20060101 C08G065/26; C08G 59/02 20060101
C08G059/02 |
Foreign Application Data
Date |
Code |
Application Number |
Jul 26, 2013 |
JP |
2013-156007 |
Claims
1. A resist material to be used in an imprint process, comprising:
a diluent monomer having a hydroxyl group and at least one
functional group selected from a vinyl ether group, an epoxy group
and an oxetanyl group; a dendrimer having at least two reactive
groups for photo-cationic polymerization; and a photo-acid
generator as a polymerization initiator.
2. The material of claim 1, wherein the material comprises: 50% or
more and 90% or less by weight of the diluent monomer; 5% or more
and 50% or less by weight of the dendrimer; and 0.3% or more and
10% or less by weight of the polymerization initiator.
3. The material of claim 1, wherein the dendrimer has a vinyl ether
group, an epoxy group or an oxetanyl group as the reactive groups
for photo-cationic polymerization.
4. The material of claim 1, wherein the diluent monomer having the
hydroxyl group and the vinyl ether group is represented by general
formula Ia: ##STR00004## wherein R is a hydrocarbon chain.
5. The material of claim 1, wherein the diluent monomer having the
hydroxyl group and the epoxy group is represented by general
formula Ib: ##STR00005## wherein R.sub.1 is a hydrocarbon
chain.
6. The material of claim 1, wherein the diluent monomer having the
hydroxyl group and the oxetanyl group is represented by general
formula Ic: ##STR00006## wherein each of R.sub.2 and R.sub.3 is a
hydrocarbon chain.
7. A resist material to be used in an imprint process, comprising:
a diluent monomer having a vinyl ether group and a hydroxyl group;
a dendrimer having at least two reactive groups for photo-radical
polymerization; and an acid-and-radical generator as a
polymerization initiator.
8. The material of claim 7, wherein the acid-and-radical generator
is an onium salt.
9. The material of claim 7, wherein the material comprises: 50% or
more and 90% or less by weight of the diluent monomer; 5% or more
and 50% or less by weight of the dendrimer; and 0.3% or more and
10% or less by weight of the polymerization initiator.
10. The material of claim 7, wherein the dendrimer has an acryloyl
group as the reactive groups for photo-radical polymerization.
11. The material of claim 7, wherein the diluent monomer having the
vinyl ether group and the hydroxyl group is represented by general
formula Ia: ##STR00007## wherein R is a hydrocarbon chain.
12. A pattern forming method comprising: providing, on a substrate,
a resist material which comprises a diluent monomer having a
hydroxyl group and at least one functional group selected from a
vinyl ether group, an epoxy group and an oxetanyl group, a
dendrimer having at least two reactive groups for photo-cationic
polymerization, and a photo-acid generator as a polymerization
initiator; imprinting a template having concave-convex shape
patterns against the resist material; curing the resist material;
and releasing the template from the cured resist material.
13. The method of claim 12, wherein the resist material comprises:
50% or more and 90% or less by weight of the diluent monomer; 5% or
more and 50% or less by weight of the dendrimer; and 0.3% or more
and 10% or less by weight of the polymerization initiator.
14. The method of claim 12, wherein the dendrimer has a vinyl ether
group, an epoxy group or an oxetanyl group as the reactive groups
for photo-cationic polymerization.
15. The method of claim 12, wherein the resist material is provided
on an adhesion film on the substrate.
16. The method of claim 12, wherein the resist material is cured by
irradiating the resist material with an ultraviolet ray.
17. A pattern forming method comprising: providing, on a substrate,
a resist material which comprises a diluent monomer having a vinyl
ether group and a hydroxyl group, a dendrimer having at least two
reactive groups for photo-radical polymerization, and an
acid-and-radical generator as a polymerization initiator;
imprinting a template having concave-convex shape patterns against
the resist material; curing the resist material; and releasing the
template from the cured resist material.
18. The method of claim 17, wherein the acid-and-radical generator
is an onium salt.
19. The method of claim 17, wherein the material comprises: 50% or
more and 90% or less by weight of the diluent monomer; 5% or more
and 50% or less by weight of the dendrimer; and 0.3 or more and 10%
or less by weight of the polymerization initiator.
20. The method of claim 17, wherein the dendrimer has an acryloyl
group as the reactive groups for photo-radical polymerization.
Description
CROSS REFERENCE TO RELATED APPLICATION
[0001] This application is based upon and claims the benefit of
priority from the prior Japanese Patent Application No.
2013-156007, filed on Jul. 26, 2013, the entire contents of which
are incorporated herein by reference.
FIELD
[0002] Embodiments described herein relate to a resist material and
a pattern forming method using the same.
BACKGROUND
[0003] A method of performing an imprint process in the atmosphere
of a condensable gas such as pentafluoropropane (PFP) is proposed
to improve the yield of the imprint process. The condensable gas
means a gas which is condensed and liquefied at a low pressure.
When a template is pressed against a resist material under the
condensable gas atmosphere, the condensable gas present between
concave portions of patterns of the template and the resist
material is compressed into a liquid. Therefore, bubbles of the
condensable gas disappear from the concave portions, so that the
concave portions are completely filled with the resist
material.
BRIEF DESCRIPTION OF THE DRAWINGS
[0004] FIGS. 1A to 1F are diagrams for illustrating a pattern
forming method of a first embodiment; and
[0005] FIGS. 2A and 2B are photomicrographs of patterns formed in
resist materials of the first embodiment, a second embodiment and a
comparative example.
DETAILED DESCRIPTION
[0006] Embodiments will now be explained with reference to the
accompanying drawings. It will be understood that these embodiments
are not intended to limit the present invention. The drawings are
schematic for the purpose of illustrating the present invention and
facilitating the understanding thereof. In the drawings, the shape,
size, ratio, or the like of some parts differ from those of actual
products. The design of these features, however, can be changed or
modified as needed taking into account the description below and
techniques known in the art.
[0007] In one embodiment, a resist material to be used in an
imprint process includes a diluent monomer having a hydroxyl group
and at least one functional group selected from a vinyl ether
group, an epoxy group and an oxetanyl group. The material further
includes a dendrimer having at least two reactive groups for
photo-cationic polymerization. The material further includes a
photo-acid generator as a polymerization initiator.
First Embodiment
(1) Pattern Forming Method
[0008] FIGS. 1A to 1F are cross-sectional views showing the
respective steps of a pattern forming method of this embodiment.
The pattern forming method using an imprint process in a
condensable gas (such as PFP or trichlorofluoromethane) atmosphere
will be described with reference to FIGS. 1A to 1F.
[0009] As shown in FIG. 1A, a substrate 1 is first prepared.
Herein, a case where a semiconductor substrate is used as the
substrate 1 will be described. An adhesion film material for an
imprint process is applied onto the semiconductor substrate 1 by
spinning and heated. As shown in FIG. 1B, this process forms an
adhesion film 2 on the semiconductor substrate 1.
[0010] Next, as shown in FIG. 1C, drops of a resist material 8 of
this embodiment are deposited (provided) on the adhesion film 2 by
an inkjet method or the like. The resist material 8 has the
property of being insoluble in a liquefied condensable gas
(hereinafter, the liquefied condensable gas is referred to as the
liquefied gas).
[0011] Next, as shown in FIG. 1D, the atmosphere is filled with a
condensable gas, and a template 11 having concave-convex shape
patterns is imprinted against the resist material 8. In this step,
the condensable gas present between the concave portions of the
patterns of the template 11 and the resist material 8 is compressed
into a liquefied gas. Accordingly, bubbles of the condensable gas
disappear from the concave portions, and the concave portions are
completely filled with the resist material 8. The resist material
8, which has the property of being insoluble in the liquefied gas,
is not dissolved in the liquefied gas in this step.
[0012] Next, as shown in FIG. 1E, ultraviolet rays 12 are applied
to the resist material 8 while the template 11 is imprinted against
the resist material 8, so that the resist material 8 is cured. In
this step, the resist material 8 is not dissolved in the liquefied
gas while cured. Therefore, the surface and the sidewall of
patterns formed in the resist material 8 are prevented from being
rough (irregular).
[0013] Finally, as shown in FIG. 1F, the template 11 is separated
(released) from the cured resist material 8. In this way, the
patterns of the templates 11 are transferred to the resist material
8 so that the patterns are formed in the resist material 8. For
example, the adhesion film 2 and the semiconductor substrate 1 are
then etched by using the patterns of the resist material 8 as a
mask, so that a semiconductor device or the like are formed on the
semiconductor substrate 1.
(2) Resist Material
[0014] The resist material 8 used in the pattern forming method
will be described. The resist material 8 contains a crosslinking
polyfunctional monomer having two or more reactive groups for
photo-cationic polymerization, a diluent monomer for controlling
the viscosity of the resist material 8, and a photo-acid generator
as a polymerization initiator for polymerization reaction of these
monomers. The crosslinking polyfunctional monomer includes a
dendrimer having two or more reactive groups for photo-cationic
polymerization, and the diluent monomer includes a monomer having a
hydroxyl group and a reactive group for photo-cationic
polymerization.
[0015] The resist material 8 contains 50% or more and 90% or less
by weight of the diluent monomer, 5% or more and 50% or less by
weight of the dendrimer (crosslinking polyfunctional monomer), and
0.3% or more and 10% or less by weight of the photo-acid generator,
based on the total weight of the resist material 8. An optimum
value can be selected as the content of each component in the
resist material 8, depending on the imprint conditions or the
like.
[0016] Hereinafter, the diluent monomer, the dendrimer, and the
photo-acid generator in the resist material 8 will be
described.
(3) Diluent Monomer
[0017] The diluent monomer of this embodiment has a hydroxyl group
and is hydrophilic. In other words, the diluent monomer has the
property of being highly soluble in a polar solvent such as water
and being insoluble in a nonpolar solvent. Since the liquefied gas
(such as PFP or trichlorofluoromethane) functions as a nonpolar
solvent, the diluent monomer having a hydroxyl group can have the
property of being insoluble in the liquefied gas.
[0018] The diluent monomer of this embodiment also has at least one
of a vinyl ether group, an epoxy group, and an oxetanyl group as
the reactive group for photo-cationic polymerization, together with
the hydroxyl group.
[0019] The three types of reactive groups for photo-cationic
polymerization have the characteristics described below,
respectively. The vinyl ether group has a short time
(polymerization initiation time) to initiate the
cationic-polymerization reaction from exposure to light, and has a
low polymerization reaction rate. In contrast, the epoxy group has
a long polymerization initiation time and has a high reaction
rate.
[0020] The oxetanyl group has a polymerization initiation time near
the middle between those of the vinyl ether and epoxy groups and
has a low reaction rate. Since the polymerization initiation time
and the reaction rate vary with the type of the reactive group for
photo-cationic polymerization as shown above, a diluent monomer
having a most suitable reactive group for photo-cationic
polymerization should be selected depending on the imprint
conditions or the like.
[0021] For example, a diluent monomer having a hydroxyl group and a
vinyl ether group is represented by general formula Ia below. In
general formula Ia, R is a hydrocarbon chain optionally having a
cyclic hydrocarbon moiety, an aromatic ring, an ether bond, or the
like.
##STR00001##
[0022] Examples of the diluent monomer having a hydroxyl group and
a vinyl ether group include 2-hydroxyethyl vinyl ether, diethylene
glycol monovinyl ether, 4-hydroxybutyl vinyl ether,
cyclohexanedimethanol monovinyl ether, ONB-DVE (manufactured by
Daicel Corporation), and VEEA (manufactured by NIPPON SHOKUBAI CO.,
LTD.) or the like.
[0023] For example, the diluent monomer having a hydroxyl group and
an epoxy group is represented by general formula Ib below. In
general formula Ib, R.sub.1 is a hydrocarbon chain optionally
having a cyclic hydrocarbon moiety, an aromatic ring, an ether
bond, or the like.
##STR00002##
[0024] Examples of the diluent monomer having a hydroxyl group and
an epoxy group include resorcinol diglycidyl ether and
3,4-epoxycyclohexenylmethyl-3',4'-epoxycyclohexenecarboxylate or
the like.
[0025] For example, the diluent monomer having a hydroxyl group and
an oxetanyl group is represented by general formula Ic below. In
general formula Ic, R.sub.2 and R.sub.3 are each a hydrocarbon
chain optionally having an oxetane ring, an ether bond, or the
like.
##STR00003##
[0026] Examples of the diluent monomer having a hydroxyl group and
an oxetanyl group include 3-methyl-3-oxetanemethanol,
3-ethyl-3-hydroxymethyloxetane, 2-ethylhexyloxetane, and
3-ethyl-3{[(3-ethyloxetane-3-yl)methoxy]methyl}oxetane or the
like.
[0027] Another monomer having a hydroxyl group and a reactive group
for photo-radical polymerization instead of the reactive group for
photo-cationic polymerization could be a candidate for use as a
diluent monomer in this embodiment. As a result of studies based on
Globally Harmonized System of Classification and Labelling of
Chemicals (GHS) data, however, the inventors have found that some
monomers having a hydroxyl group and a reactive group for
photo-radical polymerization fall under the category of chemicals
with skin irritation (possessing the property of irritating human
skin) or the like and have a safety problem. In contrast, it is
found that the diluent monomer of this embodiment, specifically,
the monomer having a hydroxyl group and a reactive group for
photo-cationic polymerization does not fall under the category of
chemicals with skin irritation, toxicity to reproduction
(possessing the property of having an adverse effect on human
reproduction), or the like and is safe. Therefore, the diluent
monomer of this embodiment is safe for use in the imprint
process.
(4) Dendrimer
[0028] Dendrimers are molecules with a globular structure, having a
core (matrix) with a large volume and a number of branched polymer
moieties extending radially around the core. Dendrimers, which have
a globular structure, are more compact than linearly structured
molecules with the same molecular weight. Therefore, dendrimers
have low flow resistance, which means that they have low
viscosity.
[0029] Dendrimers also have the property of being less shrinkable
upon curing (less hardening-shrinkable) because there is only a
small difference between their van der Waals distance (distance
between non-bonded molecules) and bonding distance (distance
between bonded molecules). In general, the distances between bonded
organic material molecules (bonding distances) are shorter than
their van der Waals distances (distance between non-bonded
molecules).
[0030] This means that as organic material molecules are bonded
together, the distance between the molecules decreases so that
their volume decreases. The larger the number of intermolecular
bonds per unit volume, the shorter the bonding distance, which
means the smaller the organic material volume. In dendrimers, the
core occupies most of the volume, and the polymer moieties occupy a
relatively small volume. Therefore, a single dendrimer molecule has
a relatively small number of polymer moieties per unit volume
although the whole of it has a large number of polymer moieties.
Also in dendrimers, the number of intermolecular bonds per unit
volume is relatively small, because the intermolecular bonds are
formed by coupling between polymer moieties. Therefore, dendrimers
do not have significantly short bonding distances, and their
volumetric shrinkage is low.
[0031] Examples of the dendrimer of this embodiment include
dendrimers having two or more groups of one type selected from
vinyl ether, epoxy, and oxetanyl as reactive groups for
photo-cationic polymerization.
[0032] As a result of studies based on GHS data, the inventors
found that none of these dendrimers fall under the category of
chemicals with skin irritation, toxicity to reproduction, or the
like. Therefore, the dendrimer of this embodiment can be deemed to
be safe.
(5) Photo-Acid Generator
[0033] The resist material 8 contains a photo-acid generator
(cation generator) as a polymerization initiator. Examples of the
photo-acid generator include diphenyl-4-methylphenylsulfonium
trifluoromethanesulfonate and
diphenyl[4-(phenylsulfanyl)phenyl]sulfonium
hexafluoro-.chi.5-stibanuide or the like.
[0034] In this embodiment, the resist material 8, which contains
the diluent monomer insoluble in the liquefied gas, has the
property of being insoluble in the liquefied gas. According to this
embodiment, therefore, the resist material 8 is prevented from
being dissolved in the liquefied gas when the template 11 is
imprinted against the resist material 8 under the condensable gas
atmosphere. Therefore, when cured, the resist material 8 remains
not dissolved in the liquefied gas, so that the surface and the
sidewall of the patterns of the resist material 8 are prevented
from becoming rough (irregular).
[0035] According to this embodiment, the resist material 8, which
contains the dendrimer with low viscosity, also has the property of
being less viscous. Therefore, the resist material 8 can be quickly
charged into the concave portions of the patterns of the template
11. This means that the imprint process can be performed at a high
rate.
[0036] According to this embodiment, the resist material 8, which
contains the dendrimer less shrinkable upon curing, also has the
property of being less shrinkable upon curing. Therefore, the
patterns of the resist material 8 of this embodiment are less
deformable upon curing.
[0037] In addition, the resist material 8 of this embodiment, which
is composed of safe materials, is safe for use in the imprint
process.
Second Embodiment
[0038] This embodiment differs from the first embodiment in that
the resist material used can be cured not only by photo-cationic
polymerization reaction but also by photo-radical polymerization
reaction.
[0039] (1) Resist Material
[0040] The resist material of this embodiment is cured by
photo-cationic polymerization reaction and photo-radical
polymerization reaction. This resist material contains a dendrimer
having two or more reactive groups for photo-radical
polymerization, a diluent monomer having a hydroxyl group and a
vinyl ether group as a reactive group for photo-cationic
polymerization, and an acid-and-radical generator capable of
functioning as a photo-cationic polymerization initiator and a
photo-radical polymerization initiator.
[0041] The rate of photo-radical polymerization reaction is higher
than that of photo-cationic polymerization reaction. When the
resist material of this embodiment is used, both photo-cationic
polymerization reaction and photo-radical polymerization reaction
can be used, so that the high rate of photo-radical polymerization
reaction can compensate for the low rate of photo-cationic
polymerization reaction. According to this embodiment, therefore,
the resist material can have a higher reaction rate and can be
quickly cured.
[0042] Hereinafter, the diluent monomer, the dendrimer, and the
photo-acid generator contained in the resist material of this
embodiment will be described.
[0043] (2) Diluent Monomer
[0044] The diluent monomer of this embodiment also has a hydroxyl
group as in the first embodiment. Therefore, the diluent monomer of
this embodiment has the property of being insoluble in the
liquefied gas. The diluent monomer also has a vinyl ether group as
a reactive group for photo-cationic polymerization, together with
the hydroxyl group. The vinyl ether group is generally a functional
group to undergo photo-cationic polymerization reaction. However,
the vinyl ether group can also function as a reactive group for
photo-radical polymerization. Therefore, this diluent monomer can
undergo two types of polymerization reactions and can increase the
reaction rate.
[0045] Examples of the diluent monomer having the hydroxyl group
and the vinyl ether group may be the same as those in the first
embodiment.
[0046] (3) Dendrimer
[0047] The dendrimer of this embodiment differs from that of the
first embodiment by having a reactive group for photo-radical
polymerization. As mentioned above, the rate of photo-radical
polymerization reaction is higher than that of photo-cationic
polymerization reaction. In the resist material of this embodiment,
therefore, the high rate of photo-radical polymerization reaction
of the dendrimer can compensate for the low rate of photo-cationic
polymerization reaction of the diluent monomer. As described in the
first embodiment, the dendrimer also has low viscosity and the
property of less shrinkable upon curing.
[0048] The dendrimer of this embodiment has an acryoyl group as the
reactive group for photo-radical polymerization. Examples of the
dendrimer of this embodiment include Viscoat 1000 (manufactured by
Osaka Organic Chemical Industry Ltd.) and STAR-501 (manufactured by
Osaka Organic Chemical Industry Ltd.) or the like.
[0049] As a result of studies based on GHS data, the inventors have
found that none of these dendrimers fall under the category of
chemicals with skin irritation, toxicity to reproduction, or the
like. Therefore, the dendrimer of this embodiment can be deemed to
be safe.
[0050] (4) Acid-and-Radical Generator
[0051] The resist material of this embodiment contains an
acid-and-radical generator so that it can be cured by
photo-cationic polymerization reaction and photo-radical
polymerization reaction. Such a polymerization initiator may be an
onium salt. Examples of such an onium salt include
diphenyl(4-methylphenyl)sulfonium and tris(4-methylphenyl)sulfonium
or the like.
[0052] In this embodiment, the resist material can be cured by
photo-cationic polymerization reaction and photo-radical
polymerization reaction, because it contains the diluent monomer
having the reactive group for photo-cationic polymerization, the
dendrimer having the reactive group for photo-radical
polymerization, and an onium salt capable of functioning as a
photo-cationic polymerization initiator and a photo-radical
polymerization initiator. In the resist material of this
embodiment, therefore, the high rate of photo-radical
polymerization reaction can compensate for the low rate of
photo-cationic polymerization reaction. Therefore, the resist
material of this embodiment can undergo a higher rate of reaction
and be more quickly cured than that of the first embodiment. This
means that the imprint process can be performed at a higher
rate.
[0053] The resist material of this embodiment contains a diluent
monomer insoluble in the liquefied gas and a dendrimer having low
viscosity and being less shrinkable upon curing as that of the
first embodiment does. Therefore, this embodiment can produce the
same advantageous effect as the first embodiment.
[0054] In addition, the resist material of this embodiment is
composed of safe materials as that of the first embodiment is.
Therefore, the resist material of this embodiment is safe for use
in the imprint process.
[0055] [Evaluation of Resist Materials]
[0056] The inventors have evaluated the properties of resist
materials of the respective embodiments (the viscosity, the curing
time of the resist material, the curing shrinkage ratio, and the
surface roughness of the patterns). Specifically, three types of
resist materials of the first and second embodiments were prepared
as samples A, B, and C. Table 1 shows the details of the
composition of the resist materials as samples A, B, and C. Another
resist material containing a diluent monomer having an acryloyl
group (a reactive group for photo-radical polymerization), a
dendrimer having an acryloyl group, and a photo-radical generator
as a polymerization initiator was also prepared as a comparative
example (sample D) (see Table 1).
[0057] Each prepared resist material was measured for viscosity at
room temperature (25.degree. C.) before curing (see Table 2 and
Table 3).
[0058] Next, an imprint process was performed using each resist
material, in which patterns of the resist material were formed.
More specifically, an adhesion film for an imprint process was
formed on a substrate, and drops of the resist material of each
sample were deposited on the adhesion film by an inkjet method.
Subsequently, a template was imprinted against the resist material
under a PEP atmosphere. The resist material was cured by being
irradiated with ultraviolet light while the template was imprinted
against the resist material. In this process, the ultraviolet light
intensity was 20 mJ/cm.sup.2. Finally, the template was separated
from the cured resist material, so that the patterns of the resist
material were formed.
[0059] In the imprint process, the time from the application of
ultraviolet light to the resist material to the completion of the
curing of the resist material (the curing time) was measured as an
index of reaction rate. The shorter curing time means the higher
reaction rate. The curing shrinkage ratio of the resist material
was also determined at room temperature (25.degree. C.) (which was
calculated from the measured volumes of the resist material before
and after the curing) (see Table 2 and Table 3).
[0060] The surface roughness (arithmetic mean roughness Ra) of the
patterns formed in each sample was measured using an atomic force
microscope (AFM) (see Table 2 and Table 3). The surface roughness
was measured for an area of 2.5 .mu.m square.
[0061] Table 1 below shows the composition of the resist materials
as samples A to D. Table 2 and Table 3 show the results of the
measurement of samples A to D. Table 2 shows the results of the
evaluation on a scale of 1, 2, 3, and 4 instead of showing the
actual values. Table 3 shows how the results of the evaluation are
rated on a scale of 1 to 4, in which a smaller number indicates a
better result.
TABLE-US-00001 TABLE 1 Polymerization Diluent monomer Dendrimer
initiator Sample A Monomer with Dendrimer with Photo-acid (First
hydroxyl and vinyl oxetanyl group generator Embodiment) ether
groups Sample B Monomer with Dendrimer with Photo-acid (First
hydroxyl and epoxy group generator Embodiment) oxetanyl groups
Sample C Monomer with Dendrimer with Onium salt (Second hydroxyl
and vinyl acryloyl group Embodiment) ether groups Sample D Monomer
with Dendrimer with Photo-radical (Comparative acryloyl group
acryloyl group generator Example)
TABLE-US-00002 TABLE 2 Viscosity Curing Surface roughness before
Curing shrinkage (Ra) of pattern curing time ratio obtained after
Sample A 2 1 3 0.3 nm or less Sample B 2 1 3 0.3 nm or less Sample
C 2 1 3 0.3 nm or less Sample D 3 1 3 4.5 nm or more
TABLE-US-00003 TABLE 3 1 2 3 4 Curing Less Equal to or more Equal
to or more 20 time than 5 than 5 seconds than 10 seconds seconds
seconds and less than 10 and less than 20 or more seconds seconds
Viscosity Less Equal to or more Equal to or more 20 cP or than 3
than 3 cP and than 10 cP and more cP less than 10 cP less than 20
cP Curing Less Equal to or more Equal to or more 10% or shrinkage
than 3% than 3% and less than 5% and less more ratio than 5% than
10%
[0062] Table 2 shows that the patterns of the resist materials
(samples A to D) of the embodiments have a surface roughness (Ra)
of 0.3 nm or less, whereas sample D (comparative example) has a
surface roughness of 4.5 nm or more. It is apparent that the
surface of the patterns formed in the resist materials (samples A
to C) of the embodiments is very flat as compared with that of the
comparative example. This shows that according to the embodiments,
the surface and sidewall of the patterns of the resist material can
be prevented from becoming rough (irregular). FIGS. 2A and 2B are
AFM photomicrographs showing the actual surfaces of samples A and
D. FIG. 2A is an AFM photomicrograph of the surface of sample D,
and FIG. 2B is an AFM photomicrograph of the surface of sample A.
Both are at the same magnification. These photomicrographs also
show that the surface of the patterns formed in sample A is flatter
and less rough than that of sample D.
[0063] Table 2 also shows that the pre-curing viscosity, curing
time (reaction rate), and curing shrinkage ratio of the resist
materials of the embodiments (samples A to C) are at similar levels
to those of the comparative example (sample D). This indicates that
the viscosity, reaction rate, and curing shrinkage ratio of the
resist materials of the embodiments reach the level required for
resist materials to be used in imprint processes.
[0064] While certain embodiments have been described, these
embodiments have been presented by way of example only, and are not
intended to limit the scope of the inventions. Indeed, the novel
materials and methods described herein may be embodied in a variety
of other forms; furthermore, various omissions, substitutions and
changes in the form of the materials and methods described herein
may be made without departing from the spirit of the inventions.
The accompanying claims and their equivalents are intended to cover
such forms or modifications as would fall within the scope and
spirit of the inventions.
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