U.S. patent application number 14/319540 was filed with the patent office on 2015-01-08 for pattern formation method, lithography apparatus, lithography system, and article manufacturing method.
The applicant listed for this patent is CANON KABUSHIKI KAISHA. Invention is credited to Hiroshi SATO.
Application Number | 20150008605 14/319540 |
Document ID | / |
Family ID | 52132253 |
Filed Date | 2015-01-08 |
United States Patent
Application |
20150008605 |
Kind Code |
A1 |
SATO; Hiroshi |
January 8, 2015 |
PATTERN FORMATION METHOD, LITHOGRAPHY APPARATUS, LITHOGRAPHY
SYSTEM, AND ARTICLE MANUFACTURING METHOD
Abstract
A pattern forming method includes: a first step of forming a
first pattern to define a first shot arrangement; and a second step
of performing an imprint process, thereby forming a second pattern
on the imprint material on the first pattern and defining a second
shot arrangement. In the second step, the second shot arrangement
is defined so as to reduce an overlay error between the first and
second shot arrangements by deforming the mold. In the first step,
based on information of the estimated second shot arrangement
definable on the substrate when the second step is performed after
the second pattern formed on the mold is amended by deforming the
mold, the first pattern is formed to make an overlay error between
the first and second shot arrangements fall within an allowable
range.
Inventors: |
SATO; Hiroshi;
(Utsunomiya-shi, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
CANON KABUSHIKI KAISHA |
Tokyo |
|
JP |
|
|
Family ID: |
52132253 |
Appl. No.: |
14/319540 |
Filed: |
June 30, 2014 |
Current U.S.
Class: |
264/40.1 ;
425/150 |
Current CPC
Class: |
B05D 3/06 20130101; B05D
3/12 20130101; H01L 21/0274 20130101; G03F 9/7007 20130101; G03F
7/70633 20130101; G03F 9/7042 20130101; G03F 7/0035 20130101; G03F
7/0002 20130101 |
Class at
Publication: |
264/40.1 ;
425/150 |
International
Class: |
B29C 59/02 20060101
B29C059/02 |
Foreign Application Data
Date |
Code |
Application Number |
Jul 2, 2013 |
JP |
2013-139260 |
May 29, 2014 |
JP |
2014-111668 |
Claims
1. A method of forming a pattern on a substrate, the method
comprising: a first step of forming a first pattern in each shot
region on the substrate to define a first shot arrangement; and a
second step of performing, in every at least one shot region in the
first shot arrangement defined in the first step, an imprint
process of curing an imprint material while bringing the imprint
material on the substrate and a mold into contact with each other,
thereby forming a second pattern on the imprint material on the
first pattern and defining a second shot arrangement, wherein in
the second step, the second shot arrangement is defined so as to
reduce an overlay error between the first shot arrangement and the
second shot arrangement by deforming the mold, and wherein in the
first step, based on information of the estimated second shot
arrangement definable on the substrate when the second step is
performed after the second pattern formed on the mold is amended by
deforming the mold, the first pattern is formed to make an overlay
error between the first shot arrangement and the second shot
arrangement fall within an allowable range.
2. The method according to claim 1, wherein in the second step, the
imprint process is performed simultaneously in a plurality of shot
regions in the first shot arrangement defined in the first
step.
3. The method according to claim 1, wherein the first step is
performed using a projection exposure apparatus configured to
project a pattern of a mask to the substrate via a projection
optical system and expose the substrate.
4. The method according to claim 3, wherein in the first step, the
first pattern is formed to make the overlay error between the first
shot arrangement and the second shot arrangement fall within an
allowable range by adjusting a position or orientation of the mask
or an optical element constituting the projection optical
system.
5. The method according to claim 1, wherein information of the
second shot arrangement further includes identification data of the
mold and an imprint apparatus used in the imprint process.
6. The method according to claim 1, wherein information of the
second shot arrangement further includes data of a position of a
shot region to undergo the imprint process.
7. The method according to claim 1, wherein the second shot
arrangement is based on a measurement result of a shape of the mold
used in the imprint process.
8. The method according to claim 1, wherein the second shot
arrangement is based on a measurement result of a shape of the mold
mounted in the imprint apparatus used in the imprint process.
9. The method according to claim 1, wherein the second shot
arrangement is based on a measurement result of the second shot
arrangement defined by forming the second pattern by the imprint
process.
10. The method according to claim 8, wherein the second shot
arrangement is based on a measurement result by a detector arranged
in the imprint apparatus used in the imprint process.
11. The method according to claim 9, wherein the second shot
arrangement is based on a measurement result by a detector arranged
in the imprint apparatus used in the imprint process.
12. The method according to claim 1, wherein information of the
second shot arrangement includes a measurement result of a
difference between the first shot arrangement and the second shot
arrangement on a substrate on which a pattern has been formed
previously.
13. A lithography apparatus of forming a first pattern in each shot
region on a substrate, comprising: an obtaining unit configured to
perform, in every at least one shot region on the first pattern, an
imprint process of curing an imprint material while bringing the
imprint material on the substrate and a mold into contact with each
other, thereby forming a second pattern, and obtaining information
of an estimated second shot arrangement formable by performing an
imprint process of forming the second pattern; and a controller
configured to, based on the information of the second shot
arrangement obtained by said obtaining unit, form the first
pattern, define a first shot arrangement, and form the first
pattern to become the defined shot arrangement, wherein the
information of the second shot arrangement is information of an
estimated shot arrangement definable on the substrate by performing
an imprint process of forming a second pattern after a second
pattern formed on the mold is amended by deforming the mold.
14. The apparatus according to claim 13, wherein the information of
the second shot arrangement includes a pattern shape formed in the
mold.
15. A lithography system of forming a pattern on a substrate,
comprising: a lithography apparatus configured to form a first
pattern in each shot region on the substrate and define a first
shot arrangement; and an imprint apparatus configured to perform,
in every at least one shot region in the defined first shot
arrangement, an imprint process of curing a resin while bringing a
mold into contact with the resin, thereby forming a second pattern
on the resin on the first pattern and defining a second shot
arrangement, wherein based on information of the estimated second
shot arrangement definable on the substrate when the imprint
process is performed, said lithography apparatus forms the first
pattern to make an overlay error between the first shot arrangement
and the second shot arrangement fall within an allowable range, and
wherein the information of the second shot arrangement is
information of an estimated shot arrangement definable on the
substrate by performing an imprint process of forming a second
pattern after a second pattern formed on the mold is amended by
deforming the mold.
16. A method of manufacturing an article, the method comprising:
forming a pattern on a substrate by using a lithography system; and
processing the substrate, on which the pattern has been formed, to
manufacture the article, the lithography system including: a
lithography apparatus configured to form a first pattern in each
shot region on the substrate and define a first shot arrangement;
and an imprint apparatus configured to perform, in every at least
one shot region in the defined first shot arrangement, an imprint
process of curing a resin while bringing a mold into contact with
the resin, thereby forming a second pattern on the resin on the
first pattern and defining a second shot arrangement, wherein based
on information of the estimated second shot arrangement definable
on the substrate when the imprint process is performed, the
lithography apparatus forms the first pattern to make an overlay
error between the first shot arrangement and the second shot
arrangement fall within an allowable range, and wherein the
information of the second shot arrangement is information of an
estimated shot arrangement definable on the substrate by performing
an imprint process of forming a second pattern after a second
pattern formed on the mold is amended by deforming the mold.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to a pattern formation method,
a lithography apparatus, a lithography system, and an article
manufacturing method.
[0003] 2. Description of the Related Art
[0004] An imprint technique is a technique capable of transferring
a nanoscale micropattern, and is coming into practical use as one
lithography technique for mass production of magnetic storage media
and semiconductor devices. In the imprint technique, a micropattern
is formed on a substrate such as a silicon substrate or glass plate
by using, as an original, a mold on which a micropattern is formed
using an electron beam drawing apparatus or the like. This
micropattern is formed as follows. A resin is applied onto a
substrate. While the mold pattern is pressed against the substrate
via the resin, the substrate is irradiated with ultraviolet rays,
thereby curing the resin. Then, the mold is released from the cured
resin. Such an imprint technique is disclosed in, for example,
Japanese Patent Laid-Open No. 2010-098310.
[0005] To get the performance of a completed device, a mold pattern
needs to be transferred to a predetermined position of a pattern on
a substrate at high accuracy. At this time, a pattern shape formed
on the mold is generally adjusted to a pattern shape on the
substrate. For example, Japanese Patent Laid-Open No. 2008-504141
has proposed an imprint apparatus including a correction mechanism
of correcting the pattern shape of a mold by pressing or pulling
the mold from the periphery.
[0006] International Publication No. 99/36949 has proposed a method
of correcting aberrations generated in each projection optical
system between exposure apparatuses of different transfer methods.
The method disclosed in International Publication No. 99/36949
adjusts the projection optical system to a shape easily correctable
by the projection optical system of each exposure apparatus, and
adjusts and corrects the shape.
[0007] However, it is difficult for the imprint apparatus to
greatly correct the pattern shape of a mold by the mold correction
mechanism. Correction methods executable by the imprint apparatus
are limited. In addition, the mold may be deformed in a series of
imprint steps such as contact of the resin and mold, filling of the
resin, light irradiation, curing of the resin, and release.
Especially when the imprint process is performed at once in a
plurality of shot regions or shot regions on the entire surface of
a substrate, correction is difficult for the methods disclosed in
Japanese Patent Laid-Open No. 2008-504141 and International
Publication No. 99/36949 because the shapes of patterns formed in
respective shot regions are different. As a result, the overlay
accuracy may drop.
SUMMARY OF THE INVENTION
[0008] The present invention provides a pattern formation method
including an imprint process for improving the accuracy of overlay
with an underlayer.
[0009] The present invention in its first aspect provide a method
of forming a pattern on a substrate, the method comprising: a first
step of forming a first pattern in each shot region on the
substrate to define a first shot arrangement; and a second step of
performing, in every at least one shot region in the first shot
arrangement defined in the first step, an imprint process of curing
an imprint material while bringing the imprint material on the
substrate and a mold into contact with each other, thereby forming
a second pattern on the imprint material on the first pattern and
defining a second shot arrangement, wherein in the second step, the
second shot arrangement is defined so as to reduce an overlay error
between the first shot arrangement and the second shot arrangement
by deforming the mold, and wherein in the first step, based on
information of the estimated second shot arrangement definable on
the substrate when the second step is performed after the second
pattern formed on the mold is amended by deforming the mold, the
first pattern is formed to make an overlay error between the first
shot arrangement and the second shot arrangement fall within an
allowable range.
[0010] The present invention in its second aspect provide a
lithography apparatus of forming a first pattern in each shot
region on a substrate, comprising: an obtaining unit configured to
perform, in every at least one shot region on the first pattern, an
imprint process of curing an imprint material while bringing the
imprint material on the substrate and a mold into contact with each
other, thereby forming a second pattern, and obtaining information
of an estimated second shot arrangement formable by performing an
imprint process of forming the second pattern; and a controller
configured to, based on the information of the second shot
arrangement obtained by the obtaining unit, form the first pattern,
define a first shot arrangement, and form the first pattern to
become the defined shot arrangement, wherein the information of the
second shot arrangement is information of an estimated shot
arrangement definable on the substrate by performing an imprint
process of forming a second pattern after a second pattern formed
on the mold is amended by deforming the mold.
[0011] The present invention in its third aspect provide a
lithography system of forming a pattern on a substrate, comprising:
a lithography apparatus configured to form a first pattern in each
shot region on the substrate and define a first shot arrangement;
and an imprint apparatus configured to perform, in every at least
one shot region in the defined first shot arrangement, an imprint
process of curing a resin while bringing a mold into contact with
the resin, thereby forming a second pattern on the resin on the
first pattern and defining a second shot arrangement, wherein based
on information of the estimated second shot arrangement definable
on the substrate when the imprint process is performed, the
lithography apparatus forms the first pattern to make an overlay
error between the first shot arrangement and the second shot
arrangement fall within an allowable range, and wherein the
information of the second shot arrangement is information of an
estimated shot arrangement definable on the substrate by performing
an imprint process of forming a second pattern after a second
pattern.
[0012] The present invention in its fourth aspect provide a method
of manufacturing an article, the method comprising: forming a
pattern on a substrate by using a lithography system; and
processing the substrate, on which the pattern has been formed, to
manufacture the article, the lithography system including: a
lithography apparatus configured to form a first pattern in each
shot region on the substrate and define a first shot arrangement;
and an imprint apparatus configured to perform, in every at least
one shot region in the defined first shot arrangement, an imprint
process of curing a resin while bringing a mold into contact with
the resin, thereby forming a second pattern on the resin on the
first pattern and defining a second shot arrangement, wherein based
on information of the estimated second shot arrangement definable
on the substrate when the imprint process is performed, the
lithography apparatus forms the first pattern to make an overlay
error between the first shot arrangement and the second shot
arrangement fall within an allowable range, and wherein the
information of the second shot arrangement is information of an
estimated shot arrangement definable on the substrate by performing
an imprint process of forming a second pattern after a second
pattern formed on the mold is amended by deforming the mold.
[0013] Further features of the present invention will become
apparent from the following description of exemplary embodiments
with reference to the attached drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0014] FIG. 1 is a view showing an imprint apparatus;
[0015] FIG. 2 is a view showing the correction mechanism of the
mold of the imprint apparatus;
[0016] FIGS. 3A and 3B are views showing the arrangements of
mold-side marks and substrate-side marks, respectively;
[0017] FIGS. 4A to 4E are views showing the difference in pattern
shape between a mold and a substrate;
[0018] FIGS. 5A to 5C are views showing an imprint process;
[0019] FIG. 6 is a view showing the relationship between the
transfer region of the mold and the substrate end;
[0020] FIG. 7 is a view showing an exposure apparatus;
[0021] FIGS. 8A to 8E are views each showing the state of
correction of a transfer shape by the exposure apparatus;
[0022] FIGS. 9A to 9C are views showing a transfer pattern
information management method when simultaneously imprinting a
pattern in a plurality of shot regions; and
[0023] FIG. 10 is a view showing a lithography system and pattern
formation method.
DESCRIPTION OF THE EMBODIMENTS
[0024] An embodiment of a pattern formation method according to the
present invention will now be described in detail with reference to
the accompanying drawings. In the respective drawings, the same
reference numerals denote the same parts, and a repetitive
description thereof will be omitted. FIG. 1 is a view showing the
arrangement of an imprint apparatus 100 used in the embodiment. The
imprint apparatus 100 forms a pattern on a resin on a substrate by
performing an imprint process of curing a resin (imprint material)
while bringing a mold into contact with the resin. As a resin
curing method, the embodiment adopts a photo-curing method of
curing a resin by irradiation of ultraviolet rays.
[0025] The imprint apparatus 100 includes a mold holding unit 12
which holds a mold 11, a substrate holding unit 14 which holds a
substrate (wafer) 13, a detector (alignment scope) 15, a correction
mechanism 16 which corrects the shape of the mold 11, and a
controller. The imprint apparatus 100 also includes a resin supply
unit (dispenser) for supplying an ultraviolet curing resin onto a
substrate, a bridge plate for holding the mold holding unit 12, and
a base plate for holding the substrate holding unit 14.
[0026] The mold 11 has a pattern surface 11a on which a pattern to
be transferred to a resin on a substrate is formed into a
three-dimensional shape. The mold 11 is made of a material, such as
quartz, capable of transmitting ultraviolet rays for curing a resin
on a substrate. Mold-side marks 18 are formed on the pattern
surface 11a of the mold 11. The mold holding unit 12 is a holding
mechanism which holds the mold 11. The mold holding unit 12
includes a mold chuck which vacuum-chucks or electrostatically
chucks the mold 11, a mold stage on which the mold chuck is placed,
and a driving system which drives the mold stage. The driving
system of the mold stage drives the mold stage and thus the mold 11
in at least the Z-axis direction (imprint direction of the mold 11
with respect to the resin). The driving system of the mold stage
may have a function of driving the mold stage not only in the
Z-axis direction, but also in the X-axis direction, Y-axis
direction, and .theta. (rotation about the Z-axis) direction.
[0027] The substrate (wafer) 13 is a substrate to which the pattern
of the mold 11 is transferred. The substrate 13 includes, for
example, a single-crystal silicon substrate and SOI (Silicon On
Insulator) substrate. A resin is supplied (applied) to the
substrate 13. Substrate-side marks 19 are formed in respective shot
regions on the substrate. The substrate holding unit 14 is a
holding mechanism which holds the substrate 13. The substrate
holding unit 14 includes a substrate chuck which vacuum-chucks or
electrostatically chucks the substrate 13, a substrate stage on
which the substrate chuck is placed, and a driving system which
drives the substrate stage. The driving system of the substrate
stage drives the substrate stage and thus the substrate 13 in at
least the X-axis direction and Y-axis direction (directions
perpendicular to the imprint direction of the mold 11). The driving
system of the substrate stage may have a function of driving the
substrate stage not only in the X-axis direction and Y-axis
direction, but also in the Z-axis direction and .theta. (rotation
about the Z-axis) direction.
[0028] The detector 15 is constructed by a scope which optically
detects (observes) the mold-side marks 18 formed on the mold 11,
and the substrate-side marks 19 formed in respective shot regions
on the substrate 13. The detector 15 suffices to detect the
relative positional relationship between the mold-side mark 18 and
the substrate-side mark 19. Hence, the detector 15 may be
constructed by a scope including an optical system for
simultaneously capturing the two, mold-side mark 18 and
substrate-side mark 19, or a scope which detects a signal
reflecting a relative positional relationship, such as an
interference signal of the two marks or moire. The detector 15 may
not simultaneously detect the mold-side mark 18 and substrate-side
mark 19. For example, the detector 15 may detect the relative
positional relationship between the mold-side mark 18 and the
substrate-side mark 19 by obtaining the respective positions of the
mold-side mark 18 and substrate-side mark 19 with respect to a
reference position arranged inside.
[0029] The correction mechanism 16 deforms the shape of the pattern
surface 11a by applying force to the mold 11 in a direction
parallel to the pattern surface 11a. For example, as shown in FIG.
2, the correction mechanism 16 includes suction units 16a which
suck the side surfaces of the pattern surface 11a, and actuators
16b which drive the suction units 16a in directions toward and
apart from the side surfaces of the pattern surface 11a. Note that
the correction mechanism 16 may deform the pattern surface 11a by
applying heat to the mold 11 and controlling the temperature of the
mold 11.
[0030] The controller includes a CPU and memory, and controls the
respective units of the imprint apparatus 100. The controller
controls an imprint process and processes associated with it. For
example, when performing the imprint process, the controller aligns
the mold 11 and substrate 13 based on the detection result of the
detector 15. Also, when performing the imprint process, the
controller controls the deformation amount of the pattern surface
11a of the mold 11 by the correction mechanism 16.
[0031] The mold-side mark 18 and substrate-side mark 19 used to
align the mold 11 and substrate 13 will be explained with reference
to FIGS. 3A and 3B. The embodiment assumes that six chip regions
are arranged in one shot region on the substrate 13. FIG. 3A shows
mold-side marks 18a to 18h formed at the four corners of the
pattern surface 11a of the mold 11. For example, the mold-side
marks 18a, 18b, 18e, and 18f having a longitudinal direction in the
horizontal direction are marks having a measurement direction in
the X-axis direction. The mold-side marks 18c, 18d, 18g, and 18h
having a longitudinal direction in the vertical direction are marks
having a measurement direction in the Y-axis direction. In FIG. 3A,
regions surrounded by dotted lines are pattern regions where
patterns to be transferred to six respective chip regions are
formed.
[0032] FIG. 3B shows substrate-side marks 19a to 19h formed at the
four corners of one shot region on the substrate. For example, the
substrate-side marks 19a, 19b, 19e, and 19f having a longitudinal
direction in the horizontal direction are marks having a
measurement direction in the X-axis direction. The substrate-side
marks 19c, 19d, 19g, and 19h having a longitudinal direction in the
vertical direction are marks having a measurement direction in the
Y-axis direction. In FIG. 3B, regions surrounded by solid lines
inside the shot region 13a are chip regions.
[0033] When performing the imprint process, that is, when bringing
the mold 11 and the resin on the substrate 13 into contact with
each other, the respective mold-side marks 18a to 18h and the
respective substrate-side marks 19a to 19h are positioned close to
each other. The detector 15 detects the mold-side marks 18 and
substrate-side marks 19. The shape and position of the pattern
surface 11a of the mold 11 can be compared with those of the shot
region 13a on the substrate 13. If a large difference (deviation)
is generated between the shape and position of the pattern surface
11a of the mold 11 and those of the shot region 13a on the
substrate 13, the overlay error exceeds an allowable range, causing
a pattern transfer error (product defect).
[0034] FIGS. 4A to 4E are views showing a deviation (second shot
arrangement) generated between the shape and position of the
pattern surface 11a of the mold 11 and those of the shot region 13a
on the substrate 13. The deviation between the mold 11 and the shot
region 13a contains a shift, magnification deviation, rotation, and
the like. By detecting the position deviation amount of the
mold-side mark 18 with respect to the substrate-side mark 19, it
can be estimated which of the shift, magnification deviation, and
rotation is the deviation.
[0035] FIG. 4A shows a case in which the deviation between the mold
11 and the shot region 13a is the shift. When it is detected that
the mold-side mark 18 deviates from the substrate-side mark 19 in
one direction, it can be estimated that the deviation between the
mold 11 and the shot region 13a is the shift. FIG. 4B shows a case
in which the deviation between the mold 11 and the shot region 13a
is the magnification deviation. When it is detected that the
mold-side mark 18 deviates outward or inward with respect to the
center of the shot region 13a, it can be estimated that the
deviation is the magnification deviation. FIG. 4C shows a case in
which the deviation between the mold 11 and the shot region 13a is
a trapezoidal deviation. When it is detected that the mold-side
mark 18 deviates outward or inward with respect to the center of
the shot region 13a and the direction differs between the upper and
lower sides or left and right sides of the shot region 13a, it can
be estimated that the deviation is the trapezoidal deviation. Also,
when it is detected that the mold-side mark 18 deviates outward or
inward with respect to the center of the shot region 13a and the
deviation amount differs between the upper and lower sides or left
and right sides of the shot region 13a, it can be estimated that
the deviation is the trapezoidal deviation.
[0036] FIG. 4D shows a case in which the deviation between the mold
11 and the shot region 13a is a twist. When it is detected that the
mold-side mark 18 deviates in different directions between the
upper and lower sides or left and right sides of the shot region
13a, it can be estimated that the deviation is the twist. FIG. 4E
shows a case in which the deviation between the mold 11 and the
shot region 13a is the rotation. When the mold-side mark 18
deviates in different directions between the upper and lower sides
or left and right sides of the shot region 13a in FIG. 4D, and
deviates to draw a circle using a given point in the shot region as
the center, it can be estimated that the deviation is the
rotation.
[0037] As shown in FIGS. 4B to 4E, when the deviation between the
mold 11 and the shot region 13a is the magnification deviation,
trapezoidal deviation, twist, rotation, or the like, the controller
controls the correction mechanism 16 to deform the shape of the
pattern surface 11a of the mold 11. More specifically, the
controller controls the deformation amount of the pattern surface
11a by the correction mechanism 16 so that the shape of the pattern
surface 11a becomes that of the shot region 13a. The controller
obtains in advance data representing the correspondence between the
driving amount (that is, force to be applied to the mold 11) of the
actuator 16b and the deformation amount of the pattern surface 11a,
and stores the data in a memory or the like. Based on the detection
result of the detector 15, the controller calculates the
deformation amount of the pattern surface 11a necessary for making
the shape of the pattern surface 11a coincide with that of the shot
region 13a. In other words, from the position deviation amount
between the mold-side mark 18 and the substrate-side mark 19 that
has been detected by the detector 15, the controller calculates the
degree at which the pattern surface 11a is deformed. Then, the
controller obtains, from the data stored in the memory, a driving
amount of the actuator 16b that corresponds to the calculated
deformation amount of the pattern surface 11a, and drives the
actuator 16b. The alignment and shape correction of the mold 11 and
shot region 13a are performed in the above-described manner, and
the mold pattern is transferred onto the substrate.
[0038] A state in which the pattern of the mold 11 is transferred
to a resin on a substrate by the imprint process will be explained
with reference to FIGS. 5A to 5C. As shown in FIG. 5A, a resin 20
is applied to an imprint target region on the substrate till the
start of imprinting. An imprint resin generally used is applied
immediately before the imprint process because it is highly
volatile. If the volatility is low, the resin may be applied in
advance by using spin coating or the like. As described above, the
controller controls the detector 15 to measure the relative
positions of the mold-side mark 18 and substrate-side mark 19, and
performs alignment of the two marks 18 and 19 and shape correction
of the mold 11. The mold 11 has the pattern surface 11a on which an
element pattern is inscribed in addition to the mold-side mark 18
for alignment.
[0039] As shown in FIG. 5B, the controller brings the mold 11 into
contact with the resin 20 to fill the pattern portion
(three-dimensional structure) of the mold 11 with the resin 20. At
this time, since the resin 20 transmits visible light, the
substrate-side mark 19 can be measured. The mold 11 uses a
transparent substrate made of quartz or the like in order to cure
the resin 20 with ultraviolet rays. In some cases, therefore, the
difference in refractive index between the mold 11 and the resin 20
is small, and the mold-side mark 18 may not be measured by only the
three-dimensional structure. Thus, there have been proposed methods
each of coating the mold-side mark 18 with a substance different in
refractive index or transmittance from the mold 11, or changing the
refractive index of the mark portion by ion irradiation or the
like. By using these methods, the detector 15 can measure the
mold-side mark 18 even in the state of FIG. 5B.
[0040] FIG. 5C shows a state in which the resin 20 is cured by
irradiating it with ultraviolet rays, and then the mold 11 is
released from the substrate 13. By the irradiation of ultraviolet
rays, the pattern of the mold 11 is transferred to the substrate
13. At the same time, the mold-side marks 18 are also transferred
to the substrate 13, forming transfer marks 21 on the substrate 13.
The transfer mark 21 is a pattern transferred onto the substrate.
By measuring the relative positions of the transfer mark 21 and
substrate-side mark 19, overlay inspection between them can be
performed.
[0041] The mold 11 used in the imprint apparatus 100 needs to be
drawn at a magnification equal to the line width of a predetermined
mold. When the imprint process is repeated, the mold 11 contacts
the resin many times, damage caused by release is accumulated, and
breakage of the pattern or the like occurs. Direct drawing by an
electron beam drawing apparatus or the like costs high and greatly
increases the production cost. To prevent this, there has been
proposed a method of fabricating a master mold and transferring it
to fabricate a replica mold. In this case, a pattern distortion,
twist, or the like upon transfer occurs inevitably. There have also
been proposed a method of simultaneously imprinting a pattern in a
plurality of shot regions to increase the productivity, and a
method of transferring a pattern at once on the entire surface of a
substrate. However, if the area of the pattern surface increases,
deterioration of the pattern shape such as a larger pattern
distortion or twist occurs. Since a large-area mold is transferred,
a shape change by holding or transfer also occurs. A mold
correction mechanism deforms a mold and corrects a pattern shape of
the mold by applying a force to the mold consisting of a material
such as quarts from the periphery as mentioned above. Therefore,
even if the deviation is magnification deviation, trapezoidal
deviation, twist, rotation, or the like as mentioned above, an
amount of correction is limited. If a considerable great force is
applied for correcting a mold, the mold itself has a potential of
being damaged. It has been found that, if a mold has a greater
area, it is difficult to deform a portion near the center of the
mold by deforming the mold from its periphery. As explained below,
it is difficult to correct a chip and a shot arrangement in a mold
pattern as shown in FIGS. 9A to 9C by applying a force from the
periphery of the mold. Therefore, it is impossible to correct all
of them by only the correction mechanism 16 of the mold.
[0042] Hence, the present inventor proposes a method of, for
example, when forming an underlying pattern (first pattern) by a
projection exposure apparatus, correcting it to have a pattern
shape conforming to the shape of a pattern (second pattern) formed
by the imprint apparatus 100 used in a succeeding stage. A method
of measuring the shape of a pattern formed on the pattern surface
11a of the mold 11 will be described below. When the shape
performance of a pattern formed in the mold 11 greatly influences a
pattern transferred to the substrate 13 by the imprint process, the
pattern shape of the mold 11 is measured in advance at high
accuracy and used as a correction amount when using the mold
11.
[0043] When a shape change caused by holding of the mold 11 by the
mold holding unit 12 greatly influences the shape of the transfer
pattern of the mold 11, the pattern shape of the mold 11 needs to
be measured in a state in which the mold 11 is attached to the
imprint apparatus 100. As shown in FIG. 1, the mold holding unit 12
holds the mold 11 used. When the mold holding unit 12 holds the
mold 11, force is added to the mold 11, deforming it. Then, the
shape difference from a pattern reference formed on the mold 11 is
measured, measuring the pattern shape of the deformed mold 11. As
the reference, a reference substrate or a reference mark 22 formed
on the substrate stage is used. The reference substrate is a
substrate fabricated for inspection, and its constitutive pattern
is measured and managed in advance at high accuracy by a
measurement apparatus outside the imprint apparatus. The reference
mark 22 constitutes a pattern by using an electron beam drawing
apparatus or the like, and this pattern is also managed at high
accuracy.
[0044] The pattern shape of the mold 11 can be measured by
measuring the relative positional relationship between the
above-mentioned reference and the mark formed on the mold 11 by
using the method shown in FIGS. 4A to 4E. In FIGS. 4A to 4E, eight
marks formed on the mold 11 are measured. However, when the pattern
region is wide or measurement needs to be executed at higher
accuracy, the pattern shape can be measured at a larger number of
points.
[0045] When a shape change of the mold 11 in performing the imprint
process while holding the mold 11 in the apparatus greatly
influences the shape of the transfer pattern, the result of
actually performing the imprint process by the imprint apparatus
needs to be reflected.
[0046] As shown in FIGS. 5A to 5C, when the pattern of the mold 11
is transferred, the mold-side mark 18 and pattern are transferred
onto the substrate. By measuring the shape of this transferred
pattern, the shape of the transfer pattern upon a shape change of
the mold 11 in the imprint process can be obtained. Further, the
behavior in transfer may change depending on the location on the
substrate surface. For example, the holding state of the substrate
13 or the like differs between imprinting near the center of the
substrate 13 and imprinting at the periphery of the substrate 13,
so the shape of the transfer pattern may change. Particularly in a
case in which the pattern surface 11a of the mold 11 lies on the
edge of the substrate 13, as shown in FIG. 6, the behavior is
highly likely to differ from that in other cases. FIG. 6 shows a
state in which six chips are transferred as one shot region, but
only three of them can be transferred onto the substrate 13.
However, if even one chip can be transferred, the imprint process
should be performed in terms of the productivity. In this case, the
behavior in the transfer step is highly likely to be changed in
comparison with the imprint process on the entire surface of the
shot region. Therefore, when the transfer pattern shape changes at
a transfer portion including the edge of the substrate 13, as shown
in FIG. 6, or on the substrate surface, the shape of the transfer
pattern of the mold 11 needs to be obtained for each case. For
example, a pattern transferred on the substrate by the method shown
in FIGS. 5A to 5C is extracted from the apparatus to measure the
shape of the pattern by a measurement apparatus. By these methods,
the shape of the transferred pattern can also be obtained at high
accuracy, and a more accurate shape can be obtained.
[0047] By transferring the pattern of the mold 11 to a reference
substrate as described above, the relative positions of the
transferred pattern (mark) and an underlying pattern formed on the
reference substrate are measured, and the shape of the transfer
pattern can be obtained. In this case, for example, the detector 15
arranged in the imprint apparatus can also be used. The shape can
be measured from the relative positions of these patterns by using
the method shown in FIGS. 4A to 4E. This method does not require
the measurement apparatus outside the imprint apparatus, can
efficiently measure the shape, and obviates the need to separately
prepare the measurement apparatus. The reference substrate having a
pattern measured and managed in advance at high accuracy by the
measurement apparatus or the like outside the apparatus has been
exemplified as the reference for measuring a pattern shape at high
accuracy. However, a substrate to be actually used may be used. An
example is a so-called pilot wafer used to set imprint conditions
before the start of the imprint process.
[0048] In an actual production step, the difference between an
underlying pattern and a transfer pattern in the imprint apparatus
is fed back to a fabrication step of forming an underlying pattern
by using a projection exposure apparatus. As the production
proceeds, the overlay accuracy can be further improved. In the
embodiment, a correction mechanism in the imprint apparatus such as
the correction mechanism 16 does not correct the pattern of the
mold 11. However, the correction mechanism in the imprint apparatus
may correct the pattern of the mold 11. For example, the correction
mechanism 16 may obtain the shape of a transfer pattern in a state
in which the correction mechanism 16 does not perform correction.
In this case, a difference obtained by subtracting the amount of
correction by the correction mechanism 16 from the difference
between the obtained transfer pattern shape and the underlying
pattern is set as the amount of correction by the projection
exposure apparatus. This will enable correct a manufacturing error,
which may occur in the underlayer, by the correction mechanism of
the imprint apparatus, and therefore, adjustment of a shot shape
will be much improved. Reversely, the item and amount of
correction, which can be performed as much as possible by the
correction mechanism 16 may be obtained in the above-described way,
and the difference between the obtained transfer pattern and the
underlying pattern may be set as the amount of correction by the
projection exposure apparatus. In other words, the item and amount
of correction, which can be performed by the correction mechanism
16, is performed by the imprint apparatus, and another item and
amount of correction is performed by the underlayer side, and
thereby the item and amount of correction is divided to that for
the mold and that for the underlayer. This will enable decrease
deformation amount of shot shape of the underlayer. Because a
number of transferring a pattern are performed in a series of
processes, an allowable amount of deformation of the shot shape
naturally exists. Therefore, the method of the present invention
solves a need of decreasing deformation amount of shot shape of the
underlayer.
[0049] In the measurement method described here, a combination of
the imprint apparatus and the mold 11, that is, whether there is a
difference between apparatuses or whether the shape deformation is
reproducible also needs to be taken into consideration. For
example, if the deformation of the mold 11 by holding is equal
between apparatuses, data of the same transfer pattern shape can be
used regardless of an apparatus which performs the imprint process
as long as the model is the same. In measurement, therefore, the
difference between apparatuses or the reproducibility is desirably
measured.
[0050] The deformation difference between apparatuses can be
obtained by performing the same measurement on the same mold 11 in
a plurality of imprint apparatuses. If there is a difference
between the apparatuses, a combination of the imprint apparatus and
the mold 11 is indispensable information, and pieces of
identification data for the apparatuses need to be managed. The
reproducibility can be obtained by repeating the steps from holding
of the mold 11 up to measurement a plurality of times by a single
imprint apparatus. If the measurement results vary, the average
shape of them is obtained, and the correction mechanism 16 arranged
in the imprint apparatus executes fine correction by the variation.
In this way, a pattern shape to be transferred by the imprint
apparatus can be obtained.
[0051] Based on a pattern shape to be transferred by the
above-described imprint apparatus, a projection exposure apparatus
200 forms an underlying pattern as a stage preceding pattern
formation by the imprint apparatus 100. Generation of an image
distortion in the projection exposure apparatus will be explained
in detail. First, generation of an image distortion in a relatively
simple step & repeat reduction projection exposure apparatus
(stepper) will be explained with reference to FIGS. 7 and 8A to 8E.
As shown in FIG. 7, the stepper uses a bi-telecentric projection
optical system PO. When a constituted lens element or a mask
(reticle) R is driven in a direction parallel to the optical axis
of the projection optical system PO, an image change (magnification
component) of a component symmetrical about the optical axis
occurs. Also, the lens element to be driven can generate, for
example, a symmetrical distortion (barrel distortion) in which the
image of a square pattern indicated by a dotted line in FIG. 8A is
changed into a shape as indicated by a solid line. When a
projection optical system in which the reticle side is
non-telecentric is used as the projection optical system PO, only
the magnification can be changed by driving the lens element in the
optical axis direction of the projection optical system PO.
[0052] When the reticle R or lens element is tilted with respect to
a plane perpendicular to the optical axis of the projection optical
system PO, the square pattern can be changed into a trapezoidal
shape indicated by a solid line, as shown in FIG. 8B. That is, a
trapezoidal distortion can be generated by changing the
magnification component using the rotation axis as the center. Not
only the lens element but also another constituted optical element
may be configured to be drivable. Alternatively, a lens group
including a plurality of lenses may be configured to be drivable. A
pattern shape obtained by moving the position or orientation of a
given lens element depends on the optical arrangement. Thus, a lens
element to be moved is selected, as needed.
[0053] In general, when an image distortion is generated, the image
plane position (focus), coma, or the like secondarily changes along
with the generated image distortion, so the reticle R and lens
element need to be driven to cancel the change. This will be simply
explained by exemplifying three, image plane position (focus),
coma, and distortion. For example, to change only the distortion,
while independently driving the reticle R and lens element in the
stage of initial adjustment, the three imaging characteristics of
the focus, coma, and distortion are measured, obtaining the change
coefficients of the three imaging characteristics. Simultaneous
linear equations with two unknowns are set up by using the change
coefficients of the two imaging characteristics except for the
focus, and the driving amounts of the reticle R and lens element.
Then, a predetermined amount is substituted into the change
coefficient of the distortion in the equations, and 0 is
substituted into the change coefficient of the coma, thereby
setting up new simultaneous equations. The reticle R and lens
element are driven in accordance with driving amounts obtained by
solving these equations. The focus is excluded because, when the
lens or the like is driven to correct another imaging
characteristic such as the distortion, the focus fluctuates
accessorily and needs to be corrected by another detection unit.
The focus can be corrected by changing the target value of a focus
detection system (not shown) in consideration of the fluctuation
amount of the secondarily changed focus. As described above, the
static exposure stepper can relatively easily correct a component
which changes in proportion to an axially symmetrical component or
tilt axis.
[0054] In a scanning exposure apparatus (scanner) such as a step
& scan exposure apparatus, a pattern is formed after scanning
exposure. Thus, only a change of the image shape of the projection
optical system PO is insufficient. An image distortion in the
scanning direction is averaged during scanning, and this needs to
be taken into consideration. First, when the magnification is
changed, the magnification of the projection optical system PO is
changed by the same method as that for the stepper. In addition,
the relative scanning speeds (synchronous speed ratio) of the
reticle R and substrate need to be changed. The magnification in
the non-scanning direction can be changed by changing the
magnification of the projection optical system PO. The
magnification in the scanning direction can be changed by changing
the synchronous speed ratio of the reticle R and substrate. The
main controller of the scanner can generate an image distortion
(rectangular component) in which a square pattern indicated by a
dotted line in FIG. 8C is changed into a rectangular shape
indicated by a solid line. By giving an offset to the relative
angles of the reticle R and substrate in the scanning direction, an
image distortion (rhomboidal or parallelogram-shaped image
distortion) as indicated by a solid line in FIG. 8D can be
generated. By gradually changing the relative angles of the reticle
R and substrate in the scanning direction during scanning, an image
distortion as indicated by a solid line in FIG. 8E can be
generated. A change of the magnification in the scanning direction
by changing the synchronous speed ratio of the reticle and
substrate, and generation of an image distortion by giving an
offset to the relative angles the reticle and substrate in the
scanning direction are described in detail in Japanese Patent
Laid-Open Nos. 6-310399 and 7-57991.
[0055] In this fashion, the scanner can generate image distortions
independently in the scanning direction and non-scanning direction
in order to form the pattern image of the reticle R by relatively
scanning (synchronously moving) the reticle R and substrate. By
changing conditions such as the synchronous speed ratio and the
relative angle in the scanning direction during scanning, an image
distortion which changes depending on the scanning position can be
generated.
[0056] By the above-described method, the projection exposure
apparatus 200 is used to fabricate an underlayer of a shape (first
shot arrangement) conforming to the shape (second shot arrangement)
of the transfer pattern of the imprint apparatus 100 used in a
succeeding stage. The projection exposure apparatus generally
performs an exposure process for each shot region. In the imprint
process, however, time is taken to fill the three-dimensional
structure of a mold with a resin at the time of transfer. It is
therefore efficient to simultaneously transfer the pattern to one
or more shot regions, for example, a plurality of shot regions.
That is, the number of shot regions to undergo transfer at once may
be different between the projection exposure apparatus and the
imprint apparatus. A case in which the imprint apparatus forms a
pattern at once in four shot regions, as shown in FIG. 9A, will be
examined. In this case, a pin-cushion shape is generated in the
transfer region, so four shot regions A to D have different shapes.
To correct the shape of the underlayer in a preceding projection
exposure step (first step) when this imprint process step (second
step) exists in a succeeding stage, the shapes of patterns in the
four respective shot regions need to be grasped, managed, and
transferred.
[0057] Not only the distortion and deformation of the entire
imprint region, but also the relative positions of shot regions
(patterns) formed in the imprint region, as shown in FIG. 9B, need
to be considered.
[0058] The positions and shapes of shot regions (patterns) in the
imprint region, and the like will be generically called "mark
arrangements" hereinafter.
[0059] FIG. 9C shows an example in which the imprint apparatus is
used to perform the imprint process for four shot regions serving
as a unit. In this case, the shapes of the shot arrangements of the
four shot regions A to D are different. Thus, the projection
exposure apparatus needs to form an underlying pattern so that the
overlay error in each of the four shot regions falls within an
allowable range. At the substrate end, only some of the four shot
regions may be formed. Hence, the position of a shot region to
undergo imprinting and the correction amount need to be managed to
transfer a pattern by the projection exposure apparatus. When
imprinting a pattern at once on the entire surface of a substrate,
the shape may be different between all shot regions. It is
therefore necessary to manage the correction amount for each shot
region, and transfer a pattern by the projection exposure
apparatus.
[0060] Further, when forming an underlying pattern by using the
projection exposure apparatus, it is desirable to minimize the
difference between shot regions to simultaneously undergo
imprinting. For example, as for the scanner, the transfer
performance may change depending on the scanning direction in
exposure. It is thus desirable to perform scanning exposure in the
same direction in all shot regions to simultaneously undergo
imprinting.
[0061] A lithography system which forms a pattern on a substrate
according to the present invention will be described with reference
to FIG. 10. The lithography system includes a measurement apparatus
300, an information processing apparatus 400, the imprint apparatus
100, and the projection exposure apparatus 200. The lithography
system also includes a development apparatus which develops a
resist pattern formed by the imprint apparatus 100 or projection
exposure apparatus 200, and an etching apparatus. The projection
exposure apparatus 200 forms an underlying pattern (first pattern)
in each shot region on a substrate, and defines the first shot
arrangement.
[0062] The imprint apparatus 100 performs the imprint process for
every one or more shot regions in the first shot arrangement
defined using the projection exposure apparatus 200, thereby
forming the second pattern on the underlying pattern and defining
second shot regions. The measurement apparatus 300 performs
measurement to obtain an estimated second shot arrangement
definable on the substrate when the imprint process is performed.
The information processing apparatus (obtaining unit) 400 obtains
the measurement result of the measurement apparatus 300, and holds
it as information of the estimated second shot arrangement.
[0063] The operations of the measurement apparatus 300, information
processing apparatus 400, imprint apparatus 100, and projection
exposure apparatus 200, and exchange of pieces of information
between them when the lithography system forms a pattern on a
substrate will be explained below.
[0064] (Step S1) The measurement apparatus 300 measures the pattern
of the pattern surface 11a in order to measure the accuracy of a
pattern formed on the pattern surface 11a of the mold 11. As a
result, the shape of the pattern surface 11a itself can be
obtained.
[0065] (Step S2) The measurement apparatus 300 or a scope in the
imprint apparatus measures the shape of the pattern in a necessary
step installed in the imprint apparatus in a state in which the
imprint apparatus holds the mold 11, or when the influence of a
shape change of the pattern that is generated in the imprint step
is large.
[0066] (Step S3) The information processing apparatus 400 stores
the measurement results in steps S1 and S2. When a shape change of
the pattern depends on a combination of the mold 11 and the imprint
apparatus, the information processing apparatus 400 holds and
manages a set of combination information and measurement result
information. The information processing apparatus 400 similarly
manages the deformation of the pattern in a shot region on the
substrate surface or including a substrate edge.
[0067] (Step S4) Based on the held information, the information
processing apparatus 400 sends, to the projection exposure
apparatus 200, shape information of an underlying pattern to be
formed by an exposure process. The projection exposure apparatus
200 transfers the pattern by the exposure process based on the
underlying pattern shape information received from the information
processing apparatus 400.
[0068] (Step S5) The substrate 13 on which the projection exposure
apparatus 200 has transferred the underlying pattern undergoes
steps such as development and etching, forming an underlying
pattern.
[0069] (Step S6) The imprint apparatus 100 transfers the pattern to
the substrate 13 by performing the imprint process on the substrate
13 bearing the underlying pattern. The information processing
apparatus 400 manages a mold and imprint apparatus used to imprint
a coincident pattern shape on the substrate 13 to undergo the
imprint process. In accordance with an instruction from the
information processing apparatus 400, the substrate 13 is sent to a
mold/imprint apparatus providing the coincident shape, and the
process advances to a transfer step based on imprinting.
[0070] (Step S7) The substrate 13 on which the imprint apparatus
100 has transferred the pattern is sent to the next step such as
development or etching.
[0071] By performing steps S1 to S7 described above, the transfer
pattern shape of the mold 11 and the underlying shape can be made
to coincide with each other even when the imprint process is
performed simultaneously in a plurality of shot regions. The
embodiment has adopted the projection exposure apparatus as a
lithography apparatus which transfers a pattern to an underlayer.
However, a charged particle beam drawing apparatus or the like is
also usable as the lithography apparatus which transfers a pattern
to an underlayer.
[0072] In the above-mentioned embodiment, the imprint apparatus can
perform shape correction using a correction mechanism. For example,
a substrate manufactured by an exposure apparatus has a
manufacturing error. This manufacturing error remains as an error
in a shot shape when the substrate is imprinted by an imprint
apparatus. This error in a shot shape can be corrected by a
correction mechanism of the imprint apparatus.
[0073] Further, in another example, all of the manufacturing error
can be corrected in the underlayer side. However, a number of
transferring a pattern are performed in a series of processes.
Thus, an allowable amount of deformation of the shot shape
naturally exists. Therefore, there is a need of decreasing
deformation amount of shot shape. In this case, a method, wherein
correcting a part of correction is performed by the imprint
apparatus, and the rest of correction is performed in the
underlayer side, can be thinkable. In this case, a correction item
and a correction amount in the imprint apparatus 100 can be sent to
the information processing apparatus 400 in S3, or can be possessed
by the information processing apparatus 400 from the beginning as
information if the correction item and the correction amount is
inherent in the imprint apparatus 100. Then, a shape which is
obtained by deducting an item and amount of correction, which can
be performed by the imprint apparatus, from a pattern shape, to be
imprinted, sent in S3, is sent to the exposure apparatus 200 and
the underlayer is manufactured in S4. Imprint operation with much
adjusted shapes having less correction amounts will be possible by
sending the underlayer manufactured in S4 to the imprint apparatus
100 and performing a shape correction using the correction
mechanism of the imprint apparatus 100.
[0074] In this embodiment, the correction mechanism 16 is explained
as a shape correction mechanism of the imprint apparatus. However,
the shape correction mechanism of the imprint apparatus is not
limited to the correction mechanism 16. A shape correction
mechanism, which can correct a shape in the imprint apparatus, can
be used in the present invention.
[0075] [Method of Manufacturing Article]
[0076] A method of manufacturing an article according to the
embodiment of the present invention is suitable for manufacturing
an article such as a microdevice (for example, a semiconductor
device) or an element having a microstructure. The manufacturing
method includes a step of forming a pattern on a substrate by using
the lithography apparatus including the projection exposure
apparatus 200 and imprint apparatus 100. Further, the manufacturing
method includes other well-known steps (for example, oxidization,
deposition, vapor deposition, doping, planarization, etching,
resist removal, dicing, bonding, and packaging) of processing the
pattern-formed substrate. The method of manufacturing an article
according to the embodiment is superior to a conventional method in
at least one of the performance, quality, productivity, and
production cost of the article.
[0077] While the present invention has been described with
reference to exemplary embodiments, it is to be understood that the
invention is not limited to the disclosed exemplary embodiments.
The scope of the following claims is to be accorded the broadest
interpretation so as to encompass all such modifications and
equivalent structures and functions.
[0078] This application claims the benefit of Japanese Patent
Application Nos. 2013-139260, filed Jul. 2, 2013 and 2014-111668,
filed May 29, 2014, which are hereby incorporated by reference
herein in their entirety.
* * * * *