U.S. patent application number 14/927833 was filed with the patent office on 2017-02-09 for template, imprint apparatus, imprint method and imprint apparatus management method.
This patent application is currently assigned to Kabushiki Kaisha Toshiba. The applicant listed for this patent is Kabushiki Kaisha Toshiba. Invention is credited to Manabu TAKAKUWA.
Application Number | 20170040196 14/927833 |
Document ID | / |
Family ID | 57988724 |
Filed Date | 2017-02-09 |
United States Patent
Application |
20170040196 |
Kind Code |
A1 |
TAKAKUWA; Manabu |
February 9, 2017 |
TEMPLATE, IMPRINT APPARATUS, IMPRINT METHOD AND IMPRINT APPARATUS
MANAGEMENT METHOD
Abstract
According to the embodiments, a template in which a main pattern
is placed on a pattern-formed surface of a template substrate, the
main pattern being formed by a concave and convex pattern, the
template substrate being transparent to an electromagnetic wave
with a predetermined wavelength is provided. The template includes
a first mark in which line-shaped first concave patterns and first
convex patterns are alternately placed in a width direction on the
pattern-formed surface. The first convex pattern includes a first
light-blocking portion and a first translucent portion. The first
light-blocking portion is a region including a first side surface
in the width direction and being covered with a metal film. The
first translucent portion is a region including a second side
surface in the width direction and being not covered with the metal
film.
Inventors: |
TAKAKUWA; Manabu; (Tsu,
JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Kabushiki Kaisha Toshiba |
Minato-ku |
|
JP |
|
|
Assignee: |
Kabushiki Kaisha Toshiba
Minato-ku
JP
|
Family ID: |
57988724 |
Appl. No.: |
14/927833 |
Filed: |
October 30, 2015 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
G03F 9/7038 20130101;
H01L 21/3105 20130101; G03F 7/0002 20130101 |
International
Class: |
H01L 21/67 20060101
H01L021/67; H01L 21/683 20060101 H01L021/683; H01L 21/3105 20060101
H01L021/3105; H01L 21/68 20060101 H01L021/68 |
Foreign Application Data
Date |
Code |
Application Number |
Aug 3, 2015 |
JP |
2015-153512 |
Claims
1. A template in which a main pattern is placed on a pattern-formed
surface of a template substrate, the main pattern being formed by a
concave and convex pattern, the template substrate being
transparent to an electromagnetic wave with a predetermined
wavelength, the template comprising: a first mark in which
line-shaped first concave patterns and first convex patterns are
alternately placed in a width direction on the pattern-formed
surface, wherein the first convex pattern including a first
light-blocking portion that is a region including a first side
surface in the width direction and being covered with a metal film,
and a first translucent portion that is a region including a second
side surface in the width direction and being not covered with the
metal film.
2. The template according to claim 1, wherein a ratio of the first
light-blocking portion, the first translucent portion, and the
first concave pattern in the width direction is 2:1:1.
3. The template according to claim 2, wherein a difference in
height between the first concave pattern and the first convex
pattern is set such that a phase difference between the
electromagnetic wave passing through the first translucent portion
and the electromagnetic wave passing through the first concave
pattern is 90 degrees.
4. The template according to claim 1, further comprising: a second
mark in which line-shaped second concave patterns and second convex
patterns are alternately placed in a width direction on the
pattern-formed surface, wherein the second convex pattern including
a second light-blocking portion that is a region including a first
side surface in the width direction and being covered with a metal
film, and a second translucent portion that includes a second side
surface in the width direction and is not covered with the metal
film, and pitches in the first mark are different from pitches in
the second mark in the width direction.
5. The template according to claim 4, wherein an order of
arrangement of the second concave pattern, the second
light-blocking portion, and the second translucent portion is
different from an order of arrangement of the first concave
pattern, the first light-blocking portion, and the first
translucent portion in the first mark.
6. The template according to claim 4, wherein a ratio of the second
light-blocking portion, the second translucent portion, and the
second concave pattern in the width direction is 2:1:1.
7. The template according to claim 6, wherein a difference in
height between the second concave pattern and the second convex
pattern is set such that a phase difference between the
electromagnetic wave passing through the second translucent portion
and the electromagnetic wave passing through the second concave
pattern is 90 degrees.
8. The template according to claim 4, wherein the first mark is
adjacent to the second mark.
9. The template according to claim 1, wherein the first mark is
placed at an outer periphery of a region in which the main pattern
is placed.
10. The template according to claim 1, wherein the first mark is
placed in a region in which the main pattern is not placed.
11. The template according to claim 1, wherein the first mark is
used also as a misalignment-correcting alignment mark.
12. An imprint apparatus comprising: a substrate stage that holds a
substrate to be processed, the substrate including a first mark; a
template stage that faces the substrate stage and holds a template
including a second mark; a moving mechanism that relatively moves
the substrate stage and the template stage in an in-plane direction
and in a height direction; and an alignment scope that puts the
first mark and the second mark in a field of view and receives a
diffracted light, the diffracted light being obtained by
irradiating the first mark and the second mark with an
electromagnetic wave with a predetermined wavelength, wherein the
alignment scope including a light source that emits the
electromagnetic wave, a projection optical system that includes a
first light input and output unit and a second light input and
output unit, and forms light paths being through the first and
second marks between the first light input and output unit and the
second light input and output unit, a light reception sensor that
receives the diffracted light, and a switching unit that switches a
state between a first state and a second state, the first state
being a state in which the light source is placed on a light path
formed by the first light input and output unit and the light
reception sensor is placed on a light path formed by the second
light input and output unit, and the second state being a state in
which the light reception sensor is placed on the light path formed
by the first light input and output unit, and the light source is
placed on the light path formed by the second light input and
output unit.
13. An imprint method comprising: aligning a first mark of a
substrate to be processed with a second mark of a template; placing
a first light source on a first light path and placing a first
light reception sensor on a second light path in an alignment
scope, the alignment scope forming the first light path and the
second light path, the first light path through which an
electromagnetic wave with a predetermined wavelength is led to the
aligned first and second marks from a direction of a first-order
diffraction angle, the first-order diffraction angle being an angle
of a first-order diffracted light when the first and second marks
are irradiated with the electromagnetic wave from a direction
perpendicular to the first and second marks, the second light path
through which a first diffracted light is led, the first diffracted
light vertically being diffracted at the aligned first and second
marks; receiving the first diffracted light from the first and
second marks with the first light reception sensor, the first
diffracted light being obtained by emitting the electromagnetic
wave from the first light source; correcting misalignment between
the template and the substrate to be processed using the first
diffracted light; aligning the first mark with a third mark of the
template; placing a second light source on the second light path
and placing a second light reception sensor on the first light path
in the alignment scope; receiving a second diffracted light from
the first and third marks with the second light reception sensor,
the second diffracted light being obtained by emitting the
electromagnetic wave from the second light source; calculating a
template height at the third mark from an intensity of the received
second diffracted light; and adjusting a pressure at which a
reverse surface of the template is pressurized based on the
template height.
14. The imprint method according to claim 13, wherein, in a case
that a plurality of third marks exists, the receiving a second
diffracted light and the calculating a template height are
performed for all of the third mark
15. The imprint method according to claim 13, wherein the third
mark includes a pattern, the pattern giving a priority to one
first-order diffracted light over the other first-order diffracted
light of .+-.first-order diffracted lights diffracted at the third
mark, and the calculating of the template height includes measuring
a signal intensity of the second diffracted light diffracted at the
aligned first and third marks while a predetermined distance is
placed between the template and the substrate to be processed, and
finding the template height corresponding to the measured signal
intensity with reference to information indicating a relationship
between a height of a pattern-formed surface of the template from a
template stage and the signal intensity of the second diffracted
light.
16. The imprint method according to claim 13, wherein the third
mark includes a first pattern giving a priority to one first-order
diffracted light over the other first-order diffracted light of
.+-.first-order diffracted lights diffracted at the third mark, and
a second pattern giving a priority to the other first-order
diffracted light over the one first-order diffracted light, in the
receiving of the second diffracted light, a first process and a
second process are conducted while the distance between the
template and the substrate to be processed is changed, the first
process being a process receiving the second diffracted light when
the first mark and the first pattern are irradiated with the
electromagnetic wave, the second process being a process receiving
the second diffracted light when the first mark and the second
pattern are irradiated with the electromagnetic wave, and the
calculating of the template height includes calculating first
signal intensity and second signal intensity of the second
diffracted light corresponding to the distance, the first signal
intensity being obtained in the first process, the second signal
intensity being obtained in the second process, calculating the
distance at which the first signal intensity is identical to the
second signal intensity, and finding the template height
corresponding to the distance at which the first signal intensity
is identical to the second signal intensity.
17. The imprint method according to claim 13, wherein the third
mark includes line-shaped first concave patterns and first convex
patterns that are alternately placed in a width direction, the
first convex pattern includes: a first light-blocking portion that
is a region including a first side surface in the width direction
and being covered with a metal film; and a first translucent
portion that includes a second side surface in the width direction
and is not covered with the metal film, a ratio of the first
light-blocking portion, the first translucent portion, and the
first concave pattern in the width direction is 2:1:1, and a
difference in height between the first concave pattern and the
first convex pattern is set such that a phase difference between
the electromagnetic wave passing through the first translucent
portion and the electromagnetic wave passing through the first
concave pattern is 90 degrees.
18. The imprint method according to claim 13, wherein, in the
placing of the second light source and the second light reception
sensor, the first light source placed on the first light path is
placed on the second light path and is used as the second light
source, the first light reception sensor placed on the second light
path is placed on the first light path and is used as the second
light reception sensor.
19. The imprint method according to claim 10, wherein, in the
placing of the second light source and the second light reception
sensor, the first light source and the first light reception sensor
are switched while a substrate stage that holds the substrate to be
processed is stationary.
20. An imprint apparatus management method, the method comprising:
holding a template on a template stage in an imprint apparatus;
aligning a first mark of a substrate to be processed with a second
mark of the template; placing a light source on a first light path
and placing a light reception sensor on a second light path in an
alignment scope, the alignment scope forming the first light path
and the second light path, the first light path through which an
electromagnetic wave with a predetermined wavelength is led to the
first and second marks from a direction perpendicular to the
aligned first and second marks, the second light path through which
a diffracted light is led, the diffracted light being obtained by
diffracting the electromagnetic wave in a direction of a
first-order diffraction angle at the aligned first and second
marks, the electromagnetic wave being emitted from the
perpendicular direction; emitting the electromagnetic wave from the
light source, receiving the diffracted light from the aligned first
and second marks with the light reception sensor; calculating a
template height at the second mark from an intensity of the
diffracted light; and outputting expected maintenance time
information in accordance with temporal change of the template
height, the expected maintenance time information indicating a time
for maintenance of the template stage.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is based upon and claims the benefit of
priority from Japanese Patent Application No. 2015-153512, filed on
Aug. 3, 2015; the entire contents of which are incorporated herein
by reference.
FIELD
[0002] Embodiments described herein relate generally to an
template, an imprint apparatus, an imprint method and an imprint
apparatus management method.
BACKGROUND
[0003] In an imprint apparatus, a wafer to be processed is hold
with a vacuum chuck provided on a substrate stage. A template on
which a pattern is formed is pressed against the wafer through a
resist. The resist is cured and then the template is removed from
the resist.
[0004] The template is created normally by transferring the pattern
of a master template to a template substrate. However, the
magnification of the pattern transferred from the master template
varies depending on the degree of flatness of the reverse surface
of the template substrate. The variations in magnification of the
pattern become more pronounced as the pattern is shrunk. A
technique to measure the mi-alignment between the template and the
wafer has been proposed. However, a technique to measure the degree
of flatness of the surface of the template has not been
proposed.
BRIEF DESCRIPTION OF THE DRAWINGS
[0005] FIG. 1 is a schematic cross-sectional view of an exemplary
configuration of an imprint apparatus according to a first
embodiment;
[0006] FIGS. 1A and 1B are schematic cross-sectional views of other
exemplary configurations of the alignment scope according to the
first embodiment;
[0007] FIGS. 3A and 3B are schematic enlarged views of the vicinity
of the lenses on the lower surface of the alignment scope according
to the embodiments;
[0008] FIG. 4 is a schematic perspective view of an exemplary
configuration of a light source/light reception sensor switching
unit;
[0009] FIGS. 5A and 5B are schematic views of an exemplary
configuration of a template;
[0010] FIGS. 6A to 6C are views of an exemplary
misalignment-detecting alignment mark provided on the template;
[0011] FIG. 7 is a plan view of exemplary alignment marks provided
on a pattern-transferred substrate;
[0012] FIGS. 8A to 8C are schematic views of a method for detecting
the misalignment between the template and a to-be-processed
layer;
[0013] FIGS. 9A to 9C are views of an exemplary height-measuring
alignment mark provided on the template;
[0014] FIGS. 10A to 10C are schematic views of a method for
measuring the distance between the template and the to-be-processed
layer;
[0015] FIG. 11 is a schematic view of the relationship between the
signal intensity of a diffracted light and the driving amount of a
substrate stage in a Z direction;
[0016] FIG. 12 is a schematic view of an exemplary arrangement of
the height-measuring alignment marks on the template;
[0017] FIG. 13 is a flowchart of exemplary procedures of a method
for measuring the height of the template according to the first
embodiment;
[0018] FIG. 14 is a flowchart of exemplary procedures of a method
for measuring the height according to a second embodiment; and
[0019] FIG. 15 is a view of exemplary information about the height
of the template and signal intensity.
DETAILED DESCRIPTION
[0020] According to the embodiments, a template in which a main
pattern is placed on a pattern-formed surface of a template
substrate, the main pattern being formed by a concave and convex
pattern, the template substrate being transparent to an
electromagnetic wave with a predetermined wavelength is provided.
The template includes a first mark in which line-shaped first
concave patterns and first convex patterns are alternately placed
in a width direction on the pattern-formed surface. The first
convex pattern includes a first light-blocking portion and a first
translucent portion. The first light-blocking portion is a region
including a first side surface in the width direction and being
covered with a metal film. The first translucent portion is a
region including a second side surface in the width direction and
being not covered with the metal film.
[0021] The template, imprint apparatus, imprint method and imprint
apparatus management method according to the embodiments will be
described in detail hereinafter with reference to the appended
drawings. Note that the present invention is not limited to the
embodiments.
First Embodiment
[0022] FIG. 1 is a schematic cross-sectional view of an exemplary
configuration of an imprint apparatus according to the first
embodiment. An imprint apparatus 10 includes a substrate stage 11.
The substrate stage 11 is provided with a chuck 12. The chuck 12
holds a pattern-transferred substrate 100 on which a pattern is to
be formed. The chuck 102 holds the pattern-transferred substrate
100, for example, by vacuum contact.
[0023] The pattern-transferred substrate 100 includes a substrate
such as a semiconductor substrate, a underlaying pattern formed on
the substrate, and a to-be-processed layer formed on the
underlaying pattern. When a pattern is transferred, the
pattern-transferred substrate 100 further includes a resist (an
imprint agent) formed on the to-be-processed layer. The
to-be-processed layer can be, for example, an insulating film, a
metal film (conductive film), or a semiconductor film.
[0024] The substrate stage 11 is movably provided on a stage
surface plate 13. The substrate stage 11 is provided movably along
each of two axes along an upper surface 13a of the stage surface
plate 13. In this embodiment, the two axes along the upper surface
13a of the stage surface plate 13 are an X axis and a Y axis. The
substrate stage 11 is movable also along a Z axis in a direction of
height perpendicular to the X axis and the Y axis. The substrate
stage 11 is preferably rotatable around each of the X axis, the Y
axis, and the Z axis.
[0025] The substrate stage 11 is provided with a reference mark
stand 14. The reference mark (not illustrated) that the reference
position for the imprint apparatus 10 is placed on the reference
mark stand 14. The reference mark is formed, for example, by
diffraction gratings in a checker pattern. The reference mark is
used to calibrate alignment scopes 3, and determine the position of
a template 110 (posture control and adjustment). The reference mark
is the origin on the substrate stage 11. The coordinates X and Y of
the pattern-transferred substrate 100 set on the substrate stage 11
are coordinates with respect to the reference mark stand 14 as the
origin.
[0026] The imprint apparatus 10 includes a template stage 21. The
template stage 21 fixes the template (original plate or mold) 110.
The template stage 21 holds, for example, the edges of the template
110 by vacuum contact. The template stage 21 operates so as to
position the template 110 at the apparatus basis. The template
stage 21 is attached to the base portion 22.
[0027] Correction mechanisms 23 and pressurization portions 24 are
attached to the base portion 22. The correction mechanisms 23
include, for example, adjustment mechanisms that receive an
instruction from the control arithmetic unit 51, and finely adjust
the position (posture) of the template 110. This adjustment
corrects the positions of the template 110 and the
pattern-transferred substrate 100 in relation to each other.
[0028] The pressurization portions 24 correct the distortion of the
template 110 by giving a stress to the side surface of the template
110. The pressurization portions 24 pressurize the template 110 in
the direction from the four side surfaces to the center of the
template 110. This pressurization corrects the size of the pattern
to be transferred (magnification correction). The pressurization
portions 24, for example, receive an instruction from the control
arithmetic unit 51, and pressurize the template 110 at a
predetermined stress.
[0029] The base portion 22 is attached to an alignment stage 25.
The alignment stage 25 moves the base portion 22 in the X axis and
Y axis directions in order to align the template 110 and the
pattern-transferred substrate 100. The alignment stage 25 has also
a function to rotate the base portion 22 along the XY plane. The
rotational direction along the XY plane is a .theta. direction.
[0030] The alignment scopes 30 detect an alignment mark provided on
the template 110 and an alignment mark provided on the
pattern-transferred substrate 100. The alignment mark of the
template 110 and the alignment mark of the pattern-transferred
substrate 100 are used to measure the relative misalignment between
the template 110 and the pattern-transferred substrate 100. The
alignment mark of the template 110 and the alignment mark of the
pattern-transferred substrate 100 will be described below. Note
that, although FIG. 1 illustrates only two right and left alignment
scopes 30, the number of alignment scopes 30 is preferably four or
more.
[0031] FIGS. 2A and 2B are schematic cross-sectional views of other
exemplary configurations of the alignment scope according to the
first embodiment. FIG. 2A illustrates an exemplary configuration to
correct the misalignment, and FIG. 2B illustrates an exemplary
configuration to measure the height.
[0032] The alignment scope 30 includes a projection optical system
31. The projection optical system 31 includes lenses 315-1, 315-2,
and 317 at the upper part, the lower part placed on the template
110 side, and a side surface in a direction perpendicular to a
vertical direction, respectively. The projection optical system 31
includes a half mirror 316 among the lenses 315-1, 315-2, and
317.
[0033] The alignment scope 30 further includes a light source 321
and a light reception sensor 322. To correct the misalignment, the
light source 321 is placed on the side surface side of the
projection optical system 31, and the light reception sensor 322 is
placed on the upper surface side as illustrated in FIG. 2A. In the
correction, the half mirror 316 reflects the light from the light
source 321 to the lens 317 at the lower part side, and transmits
the diffracted light entering from the lens 317 at the lower part
side to the upper surface side.
[0034] To measure the height, the light source 321 is placed at the
upper part side of the projection optical system 31 and the light
reception sensor 322 is placed on the side surface side as
illustrated in FIG. 2A. In the measurement, the half mirror 316
transmits the light from the light source 321 to the lens 317 at
the lower part side, and reflects the diffracted light entering
from the lens 317 at the lower part side to the lens 315-2.
[0035] Note that, although not illustrated, a lens or mirror can be
placed between the lens 315-1 at the upper part side and the half
mirror 316, or between the lens 317 at the lower part side and the
half mirror 316. For example, a lens or mirror is placed between
the lens 317 at the lower part side and the half mirror 316 such
that the incident light from the lens 315-2 on the side surface
side enters the template 110 at a first-order diffraction angle, or
such that the .+-.first-order diffracted light diffracted at the
aligned alignment marks is led to the lens 315-2 on the side
surface side.
[0036] FIGS. 3A and 3B are schematic enlarged views of the vicinity
of the lenses on the lower surface of the alignment scope according
to the embodiments. FIG. 3A illustrates an exemplary configuration
when correcting the misalignment, and FIG. 3B illustrates an
exemplary configuration when measuring the height.
[0037] The alignment scope 30 includes a housing 311 including a
projection optical system 31. The alignment scope 30 is placed such
that the lower surface of the housing 311 faces the template 110.
Although not illustrated, the projection optical system 31 includes
a lens or mirror that leads the incident light and the diffracted
light. The first to third light input and output units 312-1 to
312-3 working as lenses are provided at the lower part side of the
housing 311. The enlarged lens 317 in FIGS. 2A and 2B is the first
to third light input and output units 312-1 to 312-3. A
predetermined distance is placed between the first light input and
output unit 312-1 and the second light input and output unit 312-2
in a non-metric direction. The third light input and output unit
312-3 is placed at the midpoint between the first light input and
output unit 312-1 and the second light input and output unit 312-2.
In this example, the non-metric direction is a direction in which
the line patterns forming the alignment mark of the template 110
extend.
[0038] Note that fourth and fifth light input and output units (not
illustrated) can be provided in a metric direction such that the
third light input and output unit 312-3 is placed at the midpoint.
In this example, the metric direction is a direction perpendicular
to the non-metric direction. The distance placed between the fourth
and fifth light input and output units is identical to the distance
between the first light input and output unit 312-1 and the second
light input and output unit 312-2. The configuration described
above enables the correction of the misalignment or the measurement
of the height without rotating the alignment scope 30 when the
metric direction is either of the X direction and the Y
direction.
[0039] In the alignment scope 30, first to third light source/light
reception sensor switching units 314-1 to 314-3 are provided on the
light paths formed by the first to third light input and output
units 312-1 to 312-3, respectively. FIG. 4 is a schematic
perspective view of an exemplary configuration of the light
source/light reception sensor switching unit. The light
source/light reception sensor switching unit 314 includes a light
source 321, a light reception sensor 322, and a switching unit 323.
The light source 321 emits a light with a predetermined wavelength.
For example, a laser diode or a Light Emitting Diode (LED) can be
used as the light source 321.
[0040] The light reception sensor 322 measures the intensity of the
diffracted light from the alignment mark. For example, a diode can
be used as the light reception sensor 322. The switching unit 323
switches the object to be placed near the lens of the projection
optical system 31 between the light source 321 and the light
reception sensor 322 in accordance with the instruction from the
control arithmetic unit 51. In the example of FIG. 4, the switching
unit 323 is formed by a disk-shaped holding member 3231 and a
supporting member 3232 that rotatably supports the vicinity of the
center of the holding member 3231. The holding member 3231 holds
the light source 321 and the light reception sensor 322. When the
switching unit 323 receives an instruction for a switch, the
holding member 3231 rotates such that the light source 321 or the
light reception sensor 322 is placed adjacent to the lens. Note
that the switch between the light source 321 and the light
reception sensor 322 is preferably performed while the substrate
stage 11 is stationary.
[0041] For example, in a case when correcting the misalignment, the
light sources 321 are placed on the light paths formed by the first
and second light input and output units 312-1 and 312-2, and the
light reception sensor 322 is placed on the light path formed by
the third light input and output unit 312-3 as illustrated in FIG.
3A. Alternatively, in a case when measuring the height, the light
reception sensors 322 are placed on the light path formed by the
first and second light input and output units 312-1 and 312-2, and
the light source 321 is placed on the light path formed by the
third light input and output unit 312-3 as illustrated in FIG.
3B.
[0042] The first to third light input and output units 312-1 to
312-3 are placed such that the first-order diffracted light
diffracted at the aligned alignment marks enters the third light
input and output unit 312-3 in the configuration illustrated in
FIG. 3A, and such that the first-order diffracted light diffracted
at the aligned alignment marks enters the first and second light
input and output units 312-1 and 312-2 in the configuration
illustrated in FIG. 3B. The third to fifth input and output units
are placed in the same manners. As described above, a reflective
mirror and optical system (not illustrated) are arranged in the
alignment scope 30 such that the directions in which incident light
and the diffracted light travel when the misalignment is corrected
are opposite to the directions when the height is measured. In the
examples of FIGS. 3A and 3B, the projection optical system 31 is
used both to correct the misalignment and to measure the
height.
[0043] The alignment scopes 30 detect the misalignment of the
template 110 from the reference mark on the reference mark stand
14, and the misalignment of the pattern-transferred substrate 100
from the template 110 as described above. The positions (for
example, the X and Y coordinates) of the alignment marks detected
with the alignment scopes 30 are transmitted to the control
arithmetic unit 51.
[0044] The alignment scope 30 according to the present embodiment
further detects the degree of flatness of the pattern-formed
surface of the template 110 held on the template stage 21 with a
chuck. The degree of flatness of the template 110 is the
information obtained, for example, by measuring the position of the
pattern-formed surface in the Z direction (the height direction)
from the principal surface facing the template stage 21 side
(hereinafter, referred to also as a template height) at a plurality
of places in the pattern-formed surface of the template 110. The
template heights (for example, a Z coordinate), which are detected
at the alignment marks of the template 110 by the alignment scope
30, are transmitted to the control arithmetic unit 51.
[0045] The imprint apparatus 10 includes a light source 41 and an
application unit 42. The light source 41 emits, for example, an
electromagnetic wave in the ultraviolet band. The light source 41
is placed, for example, immediately above the template 110. In
another case, the light source 41 is not placed immediately above
the template 110. In such a case, the light path is set with an
optical member such as a mirror such that the template 110 is
irradiated with the light, which is emitted from the light source
41, from immediately above the template 110.
[0046] The application unit 42 is a member that applies a resist on
the pattern-transferred substrate 100. For example, the application
unit 42 includes a nozzle to drop the resist on the
pattern-transferred substrate 100 from the nozzle.
[0047] The imprint apparatus 10 includes a control arithmetic unit
51. The control arithmetic unit 51 entirely controls the imprint
apparatus 10. The control arithmetic unit 51 performs, for example,
a process for controlling the substrate stage 11, a process for
controlling the light source 41, a process for correcting the
misalignment, a process for calculating the template height, and a
process for correcting the magnification in accordance with the
program in which the contents of the respective processes are
described.
[0048] The process for controlling the substrate stage 11 is a
process for generating signals to control the substrate stage 11 in
the X axis direction, the Y axis direction, the Z axis direction,
and the .theta. direction. This control positions of the template
110 and the substrate stage 11 in relation to each other. The
process for controlling the light source 41 is a process for
controlling the time to irradiate the resist with the light by the
light source 41 or the amount of the light with which the resist is
irradiated when the resist is cured.
[0049] The process for correcting the misalignment is a process in
which the misalignment of the template 110 from the reference mark
is calculated with the alignment mark of the template 110 and the
reference mark of the reference mark stand 14, and the misalignment
of the pattern-transferred substrate 100 from the template 110 is
calculated with the alignment mark of the template 110 and the
alignment mark of the pattern-transferred substrate 100.
Subsequently, the calculation to align the template stage 21 with
the substrate stage 11 is performed based on the misalignments in
order to correct the misalignments.
[0050] The process for calculating the template height is a process
in which the template height at the position at which the alignment
mark is formed on the template 110 is calculated with the alignment
mark of the template 110 and the alignment mark of the
pattern-transferred substrate 100, or with the alignment mark of
the template 110 and the reference mark of the reference mark stand
14.
[0051] The process for correcting the magnification is a process in
which a predetermined calculation is performed based on the
template height in order to calculate the stress for correcting the
magnification of the template 110. Subsequently, a signal for
generating the calculated stress is given to the pressurization
portions 24.
[0052] A method for correcting the misalignment with the alignment
scope 30, and a method for measuring the height with the alignment
scope 30 will be described next. A method for correcting the
misalignment with the alignment scope 30 will be described
first.
[0053] FIGS. 5A and 5B are schematic views of an exemplary
configuration of the template. FIG. 5A is a cross-sectional view of
the template. FIG. 5B is a plan view of the pattern-formed surface
of the template. FIGS. 6A to 6C are views of exemplary
misalignment-detecting alignment marks provided on the template.
FIG. 6A is a plan view. FIG. 6B is a cross-sectional view taken
along line A-A in FIG. 6A. FIG. 6C is a cross-sectional view taken
along line B-B in FIG. 6A. FIG. 7 is a plan view of exemplary
alignment marks provided on a pattern-transferred substrate.
[0054] The template 110 is a template substrate 111 on which a
convex and concave transfer pattern is formed. The template
substrate 111 is made of a material such as quartz or fluorite that
transmits ultraviolet. The template substrate 111 has a mesa
structure in which the surface of a center region that is to be
imprinted on the pattern-transferred substrate 100 to be processed
protrudes from the peripheral region. The protruding region in the
template substrate 111 is referred to as a mesa surface 1111, and
the surface other than the mesa surface 1111 is referred to as an
off-mesa surface 1112. The mesa surface 1111 protrudes from the
off-mesa surface 1112, for example, by tens of micrometers (.mu.m).
The template 110 is provided such that the mesa surface 1111 faces
the pattern-transferred substrate 100.
[0055] The mesa surface 1111 is provided with a main pattern
placement region R.sub.M on which the main pattern 121 for forming
a device is placed, and an auxiliary pattern placement region
R.sub.S on which auxiliary patterns such as alignment marks 122 are
placed. In a planar view, the main pattern placement region R.sub.M
is, for example, a rectangular region, and the auxiliary pattern
placement region R.sub.S is a rectangular-ring-shaped region
provided on the outer periphery of the main pattern placement
region R.sub.M. Note that the main pattern placement region R.sub.M
and the auxiliary pattern placement region R.sub.S form a shot
region or an imprint region).
[0056] The main pattern 121 is a pattern for forming, for example,
a semiconductor device. A memory forming pattern for forming a NAND
flash memory, or a peripheral circuit forming pattern for forming a
peripheral circuit that drives the NAND flash memory is cited as an
example of the pattern for forming a semiconductor device. A
line-and-space pattern can be cited as an example of the memory
forming pattern. The line-and-space pattern is a pattern in which
line-shaped concave patterns are placed at predetermined intervals
in a direction perpendicular to the direction in which the concave
patterns extend. The line-shaped pattern is less than or equal to
tens of nanometers (nm) in width, for example, in which a word line
is formed. The concave portion of the main pattern 121 is, for
example, tens of nanometers (nm) in depth.
[0057] The alignment mark 122 is a mark that is provided in
correspondence with the alignment mark that is formed on the
to-be-processed layer in the pattern-transferred substrate 100, and
that is used to for the alignment of the template 110. In this
example, a position-adjusting alignment mark 123 and a
height-measuring alignment mark 124 are provided as the alignment
mark 122.
[0058] When correcting the misalignment, line-and-space diffraction
gratings are used as the alignment mark 123 as illustrated in FIGS.
6A to 6C. In this example, two types of alignment marks 123, the
alignment mark 123A with pitches A and the alignment mark 123B with
pitches B, are adjacent to each other. The pitch B has a value
different from the value of the pitch A.
[0059] The alignment mark 123A with the pitches A is a pattern in
which a plurality of line-shaped convex patterns 1231A is arranged
with the pitches A in a direction perpendicular to the direction in
which the line-shaped convex patterns 1231A extend. In the example,
the convex patterns 1231A extend in the X direction. A metal film
131 is formed on the surface and side surface of each of the convex
patterns 1231A. When the template 110 is made of quartz, an optical
coefficient of the template 110 corresponds to an optical
coefficient of the resist. This hinders the alignment while the
resist is filled in the concave patterns 1232A of the template 110
(the patterns each formed between the adjacent convex patterns
1231A). In light of the foregoing, each of the convex patterns
1231A is applied with the metal film 131. This application changes
the optical coefficient for the incident light. This enables
In-situ alignment.
[0060] The alignment mark 123B with the pitches B is a pattern in
which a plurality of line-shaped convex patterns 1231B is arranged
with the pitches B in a direction perpendicular to the direction in
which the line-shaped convex patterns 1231B extend. Similarly to
the alignment mark 123A, the convex patterns 1231B extend in the
direction in this example. The width of the convex pattern 1231B
differs from the width of the convex pattern 1231A of the alignment
mark 123A with pitches A. The metal film 131 is formed on the
bottom of each concave pattern 1232B.
[0061] Note that, when the alignment mark 123 formed on the
template 110 is formed by line-and-space diffraction gratings as
illustrated in FIGS. 6A to 6C, the Y direction that is the
direction in which the convex patterns 1231A, and 1231B or the
concave patterns 1232A, and 1232B) are arranged is the metric
direction, and the X direction is the non-metric direction.
[0062] On the other hand, an alignment mark 501 provided on the
to-be-processed layer is formed by the diffraction gratings in a
checker pattern as illustrated in FIG. 7. In this example, two
types of alignment marks 501, i.e., the alignment mark 501A with
pitches C and the alignment mark 501B with pitches U, are adjacent
to each other. The pitch D has a value different from the value of
the pitch C.
[0063] The alignment mark 501A with the pitches C is a pattern in
which rectangular convex patterns 502A are arranged with the
pitches C in the X direction and the Y direction. Portions
surrounded by the convex patterns 502A are rectangular concave
patterns 503A.
[0064] The alignment mark 501B with the pitches D is a pattern in
which rectangular convex patterns are arranged with the pitches D
in the X direction and the Y direction. Portions surrounded by
convex patterns 502B are rectangular concave patterns 503B.
[0065] FIGS. 8A to 8C are schematic views of a method for detecting
the misalignment between the template and the to-be-processed
layer. FIG. 8A is a schematic view of a method for detecting the
misalignment with the alignment cope. FIG. 8B is a view of a light
entering the alignment marks of the template and the
to-be-processed layer while the non-metric direction is viewed.
FIG. 8C is a view of the light entering the alignment marks of the
template and the to-he-processed layer while the metric direction
is viewed. Note that the line patterns forming the alignment mark
123 of the template 110 extend in the X direction in this
example.
[0066] When correcting the misalignment, the alignment mark 501 of
the to-be-processed layer is aligned with the alignment mark 123 of
the template 110, and the alignment scope 30 is placed at a
position at which the aligned alignment marks 123 and 501 can
simultaneously be detected. In accordance with the instruction from
the control arithmetic unit 51, the light sources 321 are placed on
the light paths formed by the first and second light input and
output units 312-1 and 312-2, and the light reception sensor 322 is
placed on the light path formed by the third light input and output
unit 312-3 in the alignment scope 30.
[0067] After that, the light source 321 emits an incident light I
with a predetermined wavelength. The incident light I is emitted
through the first and second light input and output units 312-1 and
312-2 to the aligned alignment marks 123 and 501 at .+-.first-order
diffraction angles in the non-metric direction. As illustrated in
FIG. 8B, the incident light I passes through a part on which the
metal film 131 is not formed on the template 110 (in this example,
the concave pattern 1232A) and is vertically diffracted by the
alignment mark 501 in a checker pattern in the non-metric direction
(the X direction in the drawing) of the pattern-transferred
substrate 100. As illustrated in FIG. 8C, the diffracted light D
generates moire interference fringes in the metric direction (the Y
direction in the drawing) between the pattern-transferred substrate
100 and the template 110. Then, the misalignment between the
pattern-transferred substrate 100 and the template 110 is corrected
while the moire interference fringes are observed with the light
reception sensor 322.
[0068] The correction of the misalignment between the template 110
and the pattern-transferred substrate 100 has been described in
this example. Note that, however, the misalignment between the
template 110 and the reference mark of the reference mark stand 14
is corrected in the same manner.
[0069] The method for correcting the misalignment with the
alignment scope 30 has been described above. A method for measuring
the height of the template 110 with the alignment scope 30 will be
described next.
[0070] FIGS. 9A to 9C are views of exemplary height-measuring
alignment marks provided on the template. FIG. 9A is a plan view.
FIG. 9B is a cross-sectional view taken along line C-C in FIG. 9A.
FIG. 9C is a cross-sectional view taken along line D-D in FIG. 9A.
Note that the alignment mark 501 provided on the
pattern-transferred substrate 100 is the same as the alignment mark
501 described with reference to FIG. 7. Thus, the description will
be omitted.
[0071] When measuring the template height, line-and-space
asymmetric diffraction gratings are used as an alignment mark 124
as illustrated in FIGS. 9A to 9C, differently from the
misalignment-correcting alignment mark 123 illustrated in FIGS. 6A
to 6C. In this example, alignment marks 124A and 124B with
different pitches are adjacent to each other.
[0072] On the cross-sectional surface of the pattern of the
asymmetric diffraction gratings with pitches E as illustrated in
FIG. 9B, a plurality of line-shaped convex patterns 1241A are
arranged on the template substrate 111 with the pitches E in a
direction perpendicular to the direction in which the line-shaped
convex patterns 1241A extend. A metal film 131 is formed on a
region extending from a first end on the side surface to a place on
the lower surface of the convex pattern 1241A. The length of the
region in which the metal film 131 is formed on the lower surface
of the convex pattern 1241A is shorter than the width of the convex
pattern 1241A. Hereinafter, a part covered with the metal film 131
in the convex pattern 1241A is referred to as a light-blocking
portion 1242A, and a part that is not covered with the metal film
131 is referred to as a transmission portion 1243A.
[0073] In the present embodiment, the transmission light passing
through the transmission portion 1243A of the convex pattern 1241A
has a phase .phi.1, and the transmission light passing through a
concave pattern 1244A (the transmission portion) has a phase
.phi.2. The height of the convex pattern 1241A (or the depth of the
concave pattern 1244A) is set such that the difference between the
phase .phi.1 and the phase .phi.2 (hereinafter, referred to as
phase difference) has an angle except for 180 degrees. This setting
can generate the difference of diffraction efficiency between the
+first-order diffracted light and the -first-order diffracted light
that are diffracted at the aligned alignment marks 124A and 501.
Note that it is more preferable to set the phase difference at 90
degrees because the difference of diffraction efficiency between
the +first-order diffracted light and the -first-order diffracted
light increase
[0074] Furthermore, on the surface perpendicular to a direction in
which the patterns of the asymmetric diffraction gratings extend,
the light-blocking portion 1242A has a width W1, the transmission
portion 1243A of the convex pattern 1241A has a width W2, and the
concave pattern 1244A has a width W3. When W1:W2:W3=2:1:1 holds,
one of the diffraction efficiency of the -first-order diffracted
light and the +first-order diffracted light (in this example, the
-first-order diffracted light) can be zero. In other words, the
patterns of the asymmetric diffraction gratings are arranged such
that the phase difference is set at 90 degrees and W1:W2:W3=2:1:1
holds. This arrangement can prevent the -first-order diffracted
light from being generated at the aligned alignment marks 124A and
501. In FIG. 9B, the concave pattern 1244A, the light-blocking
portion 1242A of the convex pattern 1241A, and the transmission
portion 1243A are arranged in this order in the positive direction
of the Y direction.
[0075] On the cross-sectional surface of the pattern of the
asymmetric diffraction gratings with the pitches F as illustrated
in FIG. 9C, a plurality of line-shaped convex patterns 1241B are
arranged with the pitches F on the template substrate 111 in a
direction perpendicular to the direction in which the line-shaped
convex patterns 1241B extend. The pitch F is wider than the pitch
E. In the pattern of the asymmetric diffraction gratings with the
pitches F, the metal film 131 is also provided on the lower and
side surfaces of the convex pattern 1241B such that W1:W2:W3=2:1:1
holds, and the height of the convex pattern 1241B (or the depth of
the concave pattern 1244B) is set such that the phase difference
has an angle except for 180 degrees, preferably has an angle of 90
degrees. In FIG. 9C, the concave pattern 1244B, the transmission
portion 1243B of the convex pattern 1241B, and the light-blocking
portion 1242B are arranged in this order In the positive direction
of the Y direction, differently from the arrangement in FIG.
9C.
[0076] FIGS. 10A to 10C are schematic views of a method for
measuring the distance between the template and the to-be-processed
layer. FIG. 10A is a schematic view of a method for measuring the
template height with the alignment scope. FIG. 10B is a view of a
light entering the alignment marks of the template and the
to-be-processed layer while the metric direction is viewed. FIG.
10C is a view of the light entering the alignment marks of the
template and the to-be-processed layer while the non-metric
direction is viewed.
[0077] When measuring the template height, the alignment mark 501
of the to-be-processed layer is aligned with the alignment mark 124
of the template 110, and the alignment scope 30 is placed at a
position at which the aligned alignment marks 124 and 501 can
simultaneously be detected. In accordance with the instruction from
the control arithmetic unit 51, the light reception sensors 322 are
placed on the light paths formed by the first and second light
input and output units 312-1 and 312-2, and the light source 321 is
placed on the light path formed by the third light input and output
unit 312-3 in the alignment scope 30.
[0078] After that, the light source 321 emits an incident light I
with a predetermined wavelength. The incident light I is emitted
through the third light input and output unit 312-3 to the aligned
alignment marks 124 and 501 in a vertical direction. As illustrated
in FIG. 10B, the incident light I passes through the transmission
portion 1243 and the concave pattern 1244 of the alignment mark 124
of the template 110 and is diffracted. At that time, the
-first-order diffracted light disappears from the asymmetric
diffraction gratings with the pitches E in the metric direction
(the Y direction in the drawing), and two-beam interference of a
zero-order diffracted light and the +first-order diffracted light
occurs. A standing wave W appears between the zero-order diffracted
light and the +first-order diffracted light. The standing wave W
appears in a direction of an angle of about 45 degrees between the
template 110 and the pattern-transferred substrate 100, and enters
the pattern-transferred substrate 100.
[0079] As illustrated in FIG. 10C, in the non-metric direction (the
X direction in the drawing), the standing wave W is diffracted at
the diffraction gratings in checker pattern in the
pattern-transferred substrate 100. Subsequently, the diffracted
light D enters the light reception sensors 322 placed on the light
paths formed by the first and second light input and output units
312-1 and 312-2 in the alignment scope 30.
[0080] In this example, the template 110 is attached to the
template stage 21. As a result, the pattern-formed surface of the
template 110 is not flat, in other words, the template is not even
in thickness. Thus, the distance from the pattern-transferred
substrate 100 to the template 110 in the vertical direction varies
depending on the position on the template 110. This means that the
light focuses at the standard distance (reference distance) between
the pattern-transferred substrate 100 and the template 110 while
the light defocuses at a distance that is not the reference
distance. When the defocus is generated, the length of the standing
wave W changes as described with reference to FIG. 10B. Thus, the
positions of the diffracted lights entering the light reception
sensors 322 of the alignment scope 30 change. In other words, a
variation in template height is measured as the difference of the
positions at which the diffracted light enters the light reception
sensors 322.
[0081] On the other hand, in the alignment mark 124B with the
pitches F, the order in which the light-blocking portion 1242B, the
transmission portion 1243B of the convex pattern 1241B, and the
concave pattern 1244B are arranged is different from the order in
the alignment mark 124A with the pitches E. Thus, the +first-order
diffracted light disappears in the metric direction, two-beam
interference of the zero-order diffracted light and the
-first-order diffracted light occurs, and a standing wave appears
between the zero-order diffracted light and the -first-order
diffracted light. The standing wave travels in a direction opposite
to the direction in the alignment mark 124A with the pitches E. As
a result, the position at which the diffracted light enters the
light reception sensor 322 moves due to a variation in height of
the template 110 in a direction opposite to the direction in the
alignment mark 124A with the pitches E.
[0082] Each of the light reception sensors 322 placed on the light
paths formed by the first and second light input and output units
312-1 and 312-2 has a predetermined size. Thus, if a part of the
diffracted light is not included in the light reception sensor 322,
the signal intensity of the diffracted light received by the light
reception sensor 322 decreases. In contrast, when a large amount of
diffracted light enters the light reception sensor 322, the signal
intensity of the diffracted light received by the light reception
sensor 322 increases. In other words, a variation in template
height changes the signal intensity of the diffracted light
entering the light reception sensor 322.
[0083] In light of the foregoing, the signal intensity in the light
reception sensor 322 when the height of the pattern-transferred
substrate 100, namely, the driving amount of the substrate stage 11
in the Z direction is changed is measured. The signal intensity is
measured at both of the alignment mark 124A with the pitches E and
the alignment mark 124B with the pitches F. FIG. 11 is a schematic
view of the relationship between the signal intensity of the
diffracted light and the driving amount of the substrate stage in
the Z direction. In the drawing, the driving amount of the
substrate stage 11 in the Z direction is shown on the horizontal
axis, and the signal intensity of the diffracted light received by
the light reception sensor 322 is shown on the vertical axis. When
the driving amount of the substrate stage 11 in the Z direction
increases, the diffracted light moves from the position at which a
part of the diffracted light is not included in the light reception
sensor 322 to the position at which the diffracted light is
included in the light reception sensor 322 in the alignment mark
124A with the pitches E. As the result, the area of the diffracted
light entering the light reception sensor 322 increases, and the
signal intensity increases. On the other hand, the diffracted light
moves from the position at which the diffracted light is included
in the light reception sensor 322 to the position at which a part
of the diffracted light is not included in the light reception
sensor 322 in the alignment mark 124B with the pitches F. As the
result, the area of the diffracted light entering the light
reception sensor 322 decreases, and the signal intensity
decreases.
[0084] Note that the driving amount of the substrate stage 11 in
the Z direction can be changed to the template height. The control
arithmetic unit 51 obtains the curves indicating the signal
intensities with the two pitches, and the template height at the
intersection of the two signal intensity curves is the template
height at the position at which the height is measured.
[0085] FIG. 12 is a schematic view of an exemplary arrangement of
the height-measuring alignment marks on the template. The
height-measuring alignment marks 124 are placed in the auxiliary
pattern placement region R.sub.S in FIG. 5B. However, the
height-measuring alignment marks 124 can be placed in a region
where the main pattern is not placed in the main pattern placement
region R.sub.M as illustrated in FIG. 12. Arranging the
height-measuring alignment marks 124 as illustrated in FIG. 12 can
measure the heights in the whole pattern-formed surface of the
template 110.
[0086] A method for measuring the template height with the imprint
apparatus and the template will be described next. FIG. 13 is a
flowchart of exemplary procedures of a method for measuring the
height of the template according to the first embodiment. First,
the template 110 is installed on the template stage 21 (step S11),
and the template 110 is fixed on the template stage 21.
Furthermore, the pattern-transferred substrate 100 is installed on
the substrate stage 11 (step S12), and the pattern-transferred
substrate 100 is fixed on the substrate stage 11 with the chuck
12.
[0087] Next, the position-adjusting alignment mark 123 of the
template 110 is aligned with the alignment mark of the
pattern-transferred substrate 100, and the alignment scope 30 is
moved on the two alignment marks (step S13).
[0088] After that, the position of the substrate stage 11 is
measured and aligned in an alignment mode (step S14). Specifically,
as illustrated in FIG. 3A, the light sources 321 are placed the
light paths formed by the first and second light input and output
units 312-1 and 312-2, and the light reception sensor 322 is placed
on the light path formed by the third light input and output unit
312-3 in the alignment scope 30. An alignment between the
pattern-transferred substrate 100 and the template 110 is performed
as described with reference to FIGS. 6A to 6C and FIGS. 8A to
8C.
[0089] Next, the light system and detection system in the alignment
scope 30 are exchanged (step S15). Specifically, the light sources
321 placed on the light paths formed by the first and second light
input and output units 312-1 and 312-2 are switched to the light
reception sensors 322, and the light reception sensor 322 placed on
the light path formed by the third light input and output unit
312-3 is switched to the light source 321 in the alignment scope
30. The light source 321 and the light reception sensors 322 are
arranged as illustrated in FIG. 3B.
[0090] After that, the height-measuring alignment mark 124 of the
template 110 is aligned with the alignment mark of the
pattern-transferred substrate 100, and the alignment scope 30 is
moved on the two alignment marks (step S16).
[0091] Next, the substrate stage 11 or the template stage 21 is
driven in the Z direction in a degree-of-flatness measuring mode.
The amount of misalignment of the diffracted light from the Z
position is obtained, and the result from the measurement of the
degree of flatness is obtained (step S17). In this example, the
template height at the position of the height-measuring alignment
mark 124 is obtained as described with reference to FIGS. 9A to 9C
and FIGS. 10A to 10C.
[0092] After that, it is determined whether another
height-measuring alignment mark 124 exists (step S18). When another
height-measuring alignment mark exists (Yes in step S18), the
process goes back to step S16. On the other hand, when another
height-measuring alignment mark 124 does not exist (No in step
S18), the process is terminated.
[0093] Note that, when an imprint process is performed, the control
arithmetic unit 51 calculates the amount of pressure at which the
pressurization portions 24 pressurize the template 110 such that
the pattern-formed surface of the template 110 is made fiat based
on the result of the measurement of the degree of flatness. Then,
the control arithmetic unit 51 transmits the signal to the
pressurization portions 24.
[0094] Based on the information obtained from the process described
above, the correction mechanisms 23 adjust the misalignment between
the template 110 and the pattern-transferred substrate 100, and the
pressurization portions 24 adjust the pressure such that the
pattern-formed surface of the template 110 is flat. Then, the
imprint process is conducted.
[0095] The height of the pattern-formed surface of the template 110
sometimes varies depending on the existence of a particle between
the template 110 and the template stage 21, or the chip of the
template stage 21. In light of the foregoing, the template height
is measured at predetermined intervals of time (for example, once a
day or once a week). This measurement can manage the time for
maintenance including the time to clean the template stage 21, or
the lifetime of the template stage 21.
[0096] An imprint method with the imprint apparatus 10 will briefly
be described hereinafter. First, the template 110 is aligned with
the pattern-transferred substrate 100 in the method described
above. Meanwhile, the pressurization portions 24 adjust the
pressure on the template 110. Subsequently, the application unit 42
applies a resist on the pattern-transferred substrate 100. After
that, the distance between the template 110 and the
pattern-transferred substrate 100 in the Z direction is reduced,
and the transfer pattern of the template 110 is made in contact
with the resist. In the conditions, the light source 41 irradiates
the resist with the light to cure the resist. After the resist is
cured, the template 110 is removed from the resist. As a result, a
resist pattern obtained by transferring the concave and convex
shape of the transfer pattern of the template 110 to the resist is
formed on the pattern-transferred substrate 100.
[0097] After that, by etching the to-be-processed layer using the
resist pattern as a mask, the pattern is transferred to the
to-be-processed layer.
[0098] The position-adjusting alignment mark 123 and the
height-measuring alignment mark 124 are separately provided in the
above-mentioned description. Note that, however, an alignment mark
can be used as both of the misalignment-correcting alignment mark
and the height-measuring alignment mark. In such a case, the
height-measuring alignment mark 124 illustrated in FIGS. 9A to 9C
is used not only for measuring the template height but also for
correcting the misalignment.
[0099] The template 110 is provided with the two types of
height-measuring alignment marks 124 formed by the asymmetric
diffraction gratings with different pitches in the first
embodiment. The position of the light sources 321 and light
reception sensor 322 that are used for the alignment are exchanged
in the alignment scope 30. Then, the aligned height-measuring
alignment mark 124 of the template 110 and the alignment mark of
the pattern-transferred substrate 100 are irradiated with the
light. After that, the signal intensity of the diffracted light is
measured with the light reception sensor 322. These are repeated
while the height of the pattern-transferred substrate 100 or
template 110 in the Z direction is changed. Using the
height-measuring alignment marks 124 with the two types of pitches
to find the signal intensity of the diffracted light, it is
possible to find the height of the template 110 at a position at
which the height-measuring alignment mark 124 is placed.
[0100] If a particle exists between the template stage 21 and the
template 110, the template height varies. Continuously conducting
the measurement of the template height, it is possible to predict
the time to clean the template stage 21. If a part of the template
stage 21 is chipped and the degree of flatness is deteriorated, the
template height also varies. Continuously conducting the
measurement of the template height, it is also to possible to
predict the time to replace the template stage 21. Note that, when
the time for maintenance including the time to clean the template
stage 21 and the time to replace the template stage 21 is detected,
the control arithmetic unit 51 outputs the information about the
predicted maintenance time, and thus can draw the attention of the
user of the imprint apparatus.
[0101] For example, the measurement of the template height at a
predetermined intervals of time detects a place in which the height
of the template 110 varies with time. In such a case, the recipe
for dropping the resist on the place can be updated such that the
amount of resist to be dropped near the place in which the height
varies is changed in accordance with the height. It is possible to
maintain the filling characteristics of the resist in an imprint
process without the deterioration of the filling characteristics
over the course of the time in which the template 110 is used.
[0102] The pressure on the template 110 in an imprint process is
changed such that a place with a low degree of flatness in the
template 110 becomes flat and the template 110 is optimized. It is
also possible to uniform the Residual Layer Thickness (RLT) of the
residue resist film.
Second Embodiment
[0103] In the first embodiment, the height-measuring alignment
marks with the two types of pitches are used to obtain the
intensity of the diffracted light when the position of the
pattern-transferred substrate or template in the Z direction is
changed. The template height is measured from the intensity of the
diffracted light. In the second embodiment, height-measuring
alignment marks with a type of pitches are used to measure the
template height.
[0104] An imprint apparatus according to the second embodiment has
the same configuration as the configuration described in the first
embodiment, and thus the description will be omitted. Differently
from the first embodiment, only the height-measuring alignment
marks with a type of pitches are placed in the configuration of the
template, for example, in FIG. 9A.
[0105] The measurement of the height will be described next. FIG.
14 is a flowchart of exemplary procedures of a method for measuring
the height according to the second embodiment. The flowchart shows
the process corresponding to the process in step S17 of FIG.
13.
[0106] First, the alignment scope 30 is moved to a position in
which the height-measuring alignment mark 124 of the template 110
and the alignment mark of the pattern-transferred substrate 100 can
simultaneously be detected (step S31). Subsequently, the substrate
stage 11 and the template stage 21 are placed at predetermined
positions in the Z direction. Then, the light source 41 irradiates
the aligned height-measuring alignment mark 124 with a light in the
degree-of-flatness measuring mode to obtain the signal intensity of
the diffracted light (step S32).
[0107] After that, the control arithmetic unit 51 obtains the
template height corresponding to the obtained signal intensity with
reference to the held information about the template height and the
signal intensity (step S33). After the process described above, the
process is completed.
[0108] FIG. 15 is a view of exemplary information about the
template height and the signal intensity. Basically, FIG. 15 is the
same as FIG. 11 illustrating the relationship between the driving
amount of the substrate stage in the Z direction and the signal
intensity in the light reception sensor. The information about the
template height and the signal intensity indicates the relationship
between the template height and the signal intensity of the
diffracted light in the light reception sensor 322 when the
distance between the template 110 and the pattern-transferred
substrate 100 is a predetermined distance. Note that the
illustrated relationship is an example, and the graph may show a
line falling from top left to bottom right depending on the order
of arrangement of the transmission portion 1243 and light-blocking
portion 1242 in a convex pattern, and the concave pattern 1244 in
the height-measuring alignment mark 124.
[0109] When the signal intensity in the light reception sensor 322
is I1, it can be found that the template height is Z1 from the
information about the template height and the signal intensity
illustrated in FIG. 15.
[0110] The second embodiment can bring about the same effect as the
effect by the first embodiment.
[0111] In the embodiments, the alignment mark on the
pattern-transferred substrate 100 is used to measure the degree of
flatness of the template 110. Note that, however, the alignment
mark provided on the reference mark stand 14 can be used in place
of the alignment mark on the pattern-transferred substrate 100.
[0112] In the embodiments, the alignment marks and
degree-of-flatness measuring marks are with the two or less types
of pitches. However, the alignment marks can be with three or more
types of pitches.
[0113] 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
embodiments described herein may be embodied in a variety of other
forms; furthermore, various omissions, substitutions and changes in
the form of the embodiments 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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