U.S. patent application number 10/437476 was filed with the patent office on 2005-09-29 for assembly and method for transferring imprint lithography templates.
This patent application is currently assigned to MOLECULAR IMPRINTS, INC. Invention is credited to Choi, Byung J., Meissl, Mario J..
Application Number | 20050214398 10/437476 |
Document ID | / |
Family ID | 34990201 |
Filed Date | 2005-09-29 |
United States Patent
Application |
20050214398 |
Kind Code |
A1 |
Meissl, Mario J. ; et
al. |
September 29, 2005 |
ASSEMBLY AND METHOD FOR TRANSFERRING IMPRINT LITHOGRAPHY
TEMPLATES
Abstract
Disclosed is a template transfer assembly and method that
features a template transfer substrate, and a template having first
and second sides, with the first side facing away from the template
transfer substrate and the second side facing the template transfer
substrate and having mold pattern formed thereon. Polymerized
imprint material is disposed between the second side and the
template transfer substrate to fixedly attach the template to the
template transfer substrate. The method of transferring an imprint
lithography template includes dispensing a selected volume of
imprinting fluid onto the template transfer substrate, placing the
template upon the selected volume; and converting the imprinting
fluid to solid imprint material. The selected volume of imprint
material is of sufficient quantity to fixedly attach the template
to the template transfer substrate while maintaining a space
between the mold and the template transfer substrate.
Inventors: |
Meissl, Mario J.; (Austin,
TX) ; Choi, Byung J.; (Round Rock, TX) |
Correspondence
Address: |
MOLECULAR IMPRINTS, INC.
KENNETH C. BROOKS
PO BOX 81536
AUSTIN
TX
78708-1536
US
|
Assignee: |
MOLECULAR IMPRINTS, INC
Austin
TX
|
Family ID: |
34990201 |
Appl. No.: |
10/437476 |
Filed: |
May 14, 2003 |
Current U.S.
Class: |
425/186 |
Current CPC
Class: |
B82Y 40/00 20130101;
B29C 2043/025 20130101; G03F 7/0002 20130101; B82Y 10/00 20130101;
B29C 43/003 20130101 |
Class at
Publication: |
425/186 |
International
Class: |
B29C 059/02; B29C
033/30 |
Claims
1. A template transfer assembly comprising: a template transfer
substrate; a template having first and second sides, with said
first side facing away from said template transfer substrate and
said second side facing said template transfer substrate and having
a mold pattern formed thereon; and polymerized imprint material
disposed between said second side and said template transfer
substrate to fixedly attach said template to said template transfer
substrate.
2. The template transfer assembly as recited in claim 1 wherein
said polymerized imprint material surrounds a sub-section of said
mold.
3. The template transfer assembly as recited in claim 1 wherein
said polymerized imprint material hermetically seals a sub-portion
of said mold.
4. The template transfer assembly as recited in claim 1 wherein
said polymerized imprint material surrounds said entire mold.
5. The template transfer assembly as recited in claim 1 wherein
said polymerized imprint material encapsulates said entire mold
hermetically sealing said mold from an ambient.
6. The template transfer assembly as recited in claim 1 wherein
said template further includes a perimeter groove surrounding said
mold with said polymerized imprint material disposed between said
template transfer substrate and a region of said second side that
is in superimposition with said perimeter groove.
7. The template transfer assembly as recited in claim 1 wherein
said template transfer substrate comprises a semiconductor
wafer.
8. The template transfer assembly as recited in claim 1 wherein
said template transfer substrate includes a semiconductor wafer
having an additional template coupled thereto.
9. A template transfer assembly comprising: a template transfer
substrate; a template having first and second sides, with said
first side facing away from said template transfer substrate and
said second side facing said template transfer substrate and having
a mold formed thereon; and polymerized imprint material disposed
between said second side and said template transfer substrate to
fixedly polymerized imprint material disposed between said second
side and said template transfer substrate to fixedly attach said
template to said template transfer substrate while maintaining a
space between said mold and said template transfer substrate.
10. The template transfer assembly as recited in claim 9 wherein
said space is filled with imprint material.
11. The template transfer assembly as recited in claim 9 wherein a
sub-portion of said space defines a void between said substrate and
a sub-section of said mold.
12. The template transfer assembly as recited in claim 11 wherein
said polymerized imprint material surrounds said void.
13. The template transfer assembly as recited in claim 9 wherein
said polymerized imprint material hermetically seals a sub-portion
of said mold.
14. The template transfer assembly as recited in claim 11 wherein
said void is coextensive with said mold.
15. The template transfer assembly as recited in claim 9 wherein
said polymerized imprint material encapsulates said entire mold
hermetically sealing said mold from an ambient.
16. A method of transferring an imprint lithography template, said
method comprising: providing a template transfer substrate; forming
a selected volume of imprinting fluid onto said template transfer
substrate; placing said template upon said selected volume; and
converting said imprinting fluid to solid imprint material, with
said selected volume being a quantity sufficient to fixedly attach
said template to said template transfer substrate while maintaining
a space between a mold and said template transfer substrate.
17. The method as recited in claim 16 wherein converting further
includes urging said template upon said selected volume so that,
upon converting said imprint material, said solid imprint material
surrounds a portion of said mold.
18. The method as recited in claim 10 wherein converting further
includes urging said template upon said selected volume so that,
upon converting said imprint material, said solid imprint material
hermetically seals a sub-portion of said mold.
19. The method as recited in claim 10 wherein converting further
includes urging said template upon said selected volume so that,
upon converting said imprint material, said solid imprint material
surrounds said mold, entirely.
20. The method as recited in claim 10 wherein converting further
includes urging said template upon said selected volume so that,
upon converting said imprint material, said solid imprint material
encapsulates said mold, hermetically sealing said mold from an
ambient.
Description
BACKGROUND OF THE INVENTION
[0001] The present invention relates generally to imprint
lithography. More particularly, the present invention is directed
to an assembly and method to transfer templates during imprint
lithography processes.
[0002] Micro-fabrication techniques can produce structures having
features on the order of nanometers. Micro-fabrication is used in a
wide variety of applications, such as the manufacturing of
integrated circuits (i.e. semiconductor processing), biotechnology,
optical technology, mechanical systems, and
micro-electro-mechanical systems ("MEMS").
[0003] Imprint lithography is a type of micro-fabrication technique
that is becoming increasingly important in semiconductor processing
and other applications. Imprint lithography provides greater
process control and reduction of the minimum feature dimension of
the structures formed. This in turn provides higher production
yields and more integrated circuits per wafer, for example.
[0004] Micro-fabrication can be used to form a relief image on a
substrate, such as a semiconductor wafer. The substrate typically
has a transfer layer that is coated with a thin layer of
polymerizable fluid, thermoplastic, or other imprint material
capable of being formed (i.e. molded or imprinted) into a desired
structure. A mold with a relief structure makes mechanical contact
with the substrate and the polymerizable fluid or other imprint
material fills the relief structure of the mold. The polymerizable
fluid is then polymerized to form the desired structure on the
transfer layer, which is complimentary to the relief structure of
the mold. The transfer layer and the solidified polymeric material
can then be etched to form a relief image in the transfer layer, or
coated with a thin-film layer of other material, for example.
[0005] Imprint lithography systems often use an imprint head with a
mold, also called a template, which can be installed and removed
from the imprint head. This allows the imprint lithography system
to be used to imprint different patterns. In this manner, the
imprint lithography system can be used to fabricate various types
of circuits or other devices, or imprint various structures on a
substrate.
[0006] To ensure high resolution imprinting it is generally
desirable to minimize handling of the template in order to avoid
damage to the template and contamination to the template and
imprint lithography system with dust or other particulates. To that
end, there is a need to store, load, and unload templates in a
manner that avoids physical damage to the relief pattern of the
mold and contamination to the template and imprint lithography
system.
SUMMARY OF THE INVENTION
[0007] A template transfer assembly and method features a template
transfer substrate and a template having first and second sides,
with the first side facing away from the template transfer
substrate and the second side facing the template transfer
substrate and having mold pattern formed thereon. Polymerized
imprint material is disposed between the second side and the
template transfer substrate to fixedly attach the template to the
template transfer substrate. The method of transferring an imprint
lithography template includes dispensing a selected volume of
imprinting fluid onto the template transfer substrate, placing the
template upon the selected volume and converting the imprinting
fluid to solid imprint material. The selected volume of imprint
material is of sufficient quantity to fixedly attach the template
to the template transfer substrate while maintaining a space
between the mold and the template transfer substrate. These and
other embodiments are described more fully below.
BRIEF DESCRIPTION OF THE DRAWINGS
[0008] FIG. 1 is a perspective view of an imprint lithography
system for practicing embodiments of the present invention;
[0009] FIG. 2 is a simplified side view of the imprint lithography
system, shown in FIG. 1, demonstrating the spatial relationship
between the mold and the wafer having imprinting material disposed
thereon;
[0010] FIG. 3 is a simplified side view of the mold of FIG. 2 in
contact with the imprinting layer;
[0011] FIG. 4 is a simplified side view of an imprinting layer,
shown in FIG. 2, patterned according to the template;
[0012] FIG. 5 is a simplified side view of the lithographic system,
shown in FIG. 1, with a template transfer holder in a motion stage
according to an embodiment of the present invention;
[0013] FIG. 6 is a simplified side view of the template transfer
holder of FIG. 5 in position to load the template in an imprint
head;
[0014] FIG. 7 is a perspective view showing a template transfer
holder of the template transfer system, shown in FIGS. 1, 5 and 6,
in accordance with one embodiment of the present invention;
[0015] FIG. 8 is a cross-sectional view of the template transfer
holder, shown in FIG. 7, taken along lines 8-8;
[0016] FIG. 9 is a cross-sectional view of the template transfer
holder, shown in FIG. 7, taken along lines 9-9, and having a
template disposed therein;
[0017] FIG. 10 is a simplified side view of the template transfer
holder, shown in FIG. 7, taken along lines 10-10;
[0018] FIG. 11 is a simplified side view of the template transfer
holder on a transfer substrate, shown in FIG. 5, according to
another embodiment of the present invention;
[0019] FIG. 12 is a simplified side view of a template transfer
holder on a transfer substrate above the wafer chuck, shown in FIG.
5, according to another embodiment of the present invention;
[0020] FIG. 13 is a simplified cross section of a template transfer
assembly that may be employed in the lithographic system, shown in
FIGS. 1 and 5, having a template coupled to a template transfer
substrate with imprint material according to an embodiment of the
present invention;
[0021] FIG. 14 is a simplified cross section of a template transfer
assembly, shown in FIG. 13, with a template coupled to a template
transfer substrate with a perimeter of imprint material according
to an alternate embodiment of the present invention;
[0022] FIG. 15 is a simplified cross section of a template transfer
assembly, shown in FIG. 13, with a template coupled to a template
transfer substrate with a perimeter of imprint material according
to a second embodiment of the present invention;
[0023] FIG. 16 is a simplified cross section of a template transfer
assembly, shown in FIG. 13, with a template coupled to a template
transfer substrate with a perimeter of imprint material according
to a third alternate embodiment of the present invention;
[0024] FIG. 17 is a simplified flow chart of a method of handling a
template in a lithographic system, shown in FIGS. 1, 2, 3, 4, 5,
11, 12, 13, 14, 15 and 16, according to an embodiment of the
present invention;
[0025] FIG. 18 is a simplified flow chart of a method of removing a
template from an imprint head of a lithographic imprinting system,
shown in FIG. 17, according to another embodiment of the present
invention; and
[0026] FIG. 19 is a simplified flow chart of a method of installing
a template from a template transfer substrate into an imprint head
of a lithographic imprinting system, shown in FIG. 17, according to
yet another embodiment of the present invention.
DETAILED DESCRIPTION OF THE INVENTION
[0027] FIG. 1 is a perspective view of an imprint lithography
system 10 for practicing embodiments of the present invention. A
pair of spaced-apart bridge supports 12 having a bridge 14 and a
stage support 16 extending therebetween. Bridge 14 and stage
support 16 are spaced-apart. Coupled to bridge 14 is an imprint
head 18 that extends from bridge 14 toward stage support 16 and may
move along and/or rotate about, X, Y and/or Z axes. Disposed upon
stage support 16 to face imprint head 18 is a motion stage 20 and a
template transfer system 40. Motion stage 20 is configured to move
with respect to stage support 16 along one or more degrees of
freedom. For example, motion stage 20 may move along and/or rotate
about, X, Y and/or Z axes. In the present example, motion stage 20
holds a wafer 30 on a wafer chuck 21, which is typically a vacuum
chuck, and moves wafer 30 along the X and Y axes. A radiation
source 22 is coupled to imprint lithography system 10 to impinge
actinic radiation upon motion stage 20. Radiation source 22 is
coupled to bridge 14 and includes a power generator 23 connected to
radiation source 22.
[0028] Referring to both FIGS. 1 and 2, a template 26 is removably
connected to imprint head 18. Template 26 has first and second
sides 26a and 26b. First side 26a faces imprint head 18, and second
side 26b has a mold 28 thereon facing away from imprint head 18
toward wafer chuck 21. Mold 28 generally includes a plurality of
features defined by a plurality of spaced-apart recessions 28a and
protrusions 28b, having a step height, h, on the order of
nanometers (e.g. 100 nanometers). The plurality of features defines
an original pattern that is to be transferred onto a wafer 30
positioned on motion stage 20. To that end, a distance, d, between
mold 28 and a surface 32 of wafer 30 may be varied. It should be
understood that surface 32 may comprise of material from which
wafer 30 is formed, including any native oxide formed thereon
and/or one or more layers of material deposited on wafer 30.
[0029] An imprinting layer 34 is disposed on wafer 30. Imprinting
layer 34 is generally a selected volume of imprint material, such
as polymerizable fluid, applied to wafer 30, either as a plurality
of spaced-apart beads 36, as shown, or in a continuous film.
Exemplary imprint material is described in U.S. patent application
Ser. No. 10/178,947, filed Jun. 24, 2002 and entitled "Low
Viscosity High Resolution Patterning Material", which is
incorporated by reference herein in its entirety. An exemplary
method and system for depositing the imprint material is disclosed
in U.S. patent application Ser. No. 10/191,749, filed Jul. 2, 2002
and entitled "System and Method for Dispensing Liquids", which is
incorporated by reference herein in its entirety.
[0030] Referring to FIG. 3, a simplified side view of mold 28 is
shown in contact with imprinting layer 34. Imprinting layer 34 is
generally flowable when mold 28 is brought into contact with
imprinting layer 34 by creating relative movement between the
imprint head 18, shown in FIG. 1, and wafer 30 along the Z axis. In
the present example, the relative movement is achieved by moving
imprint head 18 along the Z axis. The imprint material flows to
form a contiguous layer that fills mold 28. The imprint material is
then converted to a non-flowable (i.e. solid) state, such as by
polymerization with actinic radiation, in the case of a
polymerizable fluid imprint material, or by cooling, in the case of
a thermoplastic imprint material.
[0031] FIG. 4 is a simplified side view of imprinting layer 34'
patterned according to mold 28. Mold 28 has been removed from
imprinting layer 34' by moving the imprint head 18, shown in FIG.
1, away from wafer 30. A structure 28' recorded in imprinting layer
34' is produced, in part, by mechanical contact with mold 28, and
is generally an image of mold 28. Wafer 30 with structure 28' may
then be further processed.
[0032] Mold 28 has features sized according to the structure 28'
desired to be imprinted to imprinting layer 34', which can be on
the order of nanometers. It is important to protect mold 28 from
physical damage and/or contamination so that the desired structure
28' is obtained when imprinting substrates. Template 26 is
removable from imprint head 18 of imprint lithography system 10,
shown in FIG. 1. Another template can then be installed in imprint
head 18. For example, if template 26 wears out or is damaged, a
replacement template may be installed, or a template with a
different mold (i.e. structure or pattern) may be installed to
imprint a different structure.
[0033] Template 26 is removably secured to imprint head 18 with
vacuum and/or mechanical means, such as pins or clips. Mechanical
means are desirable to ensure retention of template 26 in imprint
head 18 in the event of a vacuum failure or in the event that
vacuum is turned off during processing. Mechanical means of
securing template 26 in imprint head 18 may also be convenient when
installing or removing template 26.
[0034] To facilitate coupling template 26 to imprint head 18, the
template 26 is typically stored on template transfer system 40 so
that first side 26a faces imprint head 18. When coupling together
template 26 and imprint head 18, template 26 and imprint head 18
are placed in very close proximity (e.g. 10's of microns or less)
to one another so that the template 26 can be secured to imprint
head 18 by vacuum and/or mechanical contact. Manual insertion of
the template 26 into imprint head 18 is typically avoided due to
the increased probability of damage to the template 26 and/or
imprint head 18, as well as the increased probability of
contamination of the imprint lithography system 10, particularly
the motion stage 20.
[0035] Referring to FIG. 5, shown is a simplified side view of a
portion of imprint lithography system 10, shown in FIG. 1, with
template transfer system 40 on a motion stage 20, according to an
embodiment of the present invention. Template transfer system 40
may be permanently affixed to motion stage 20, or alternatively,
may be removably mounted to motion stage 20. An advantage of
template transfer system 40 being permanently affixed to motion
stage 20 is that the position of template transfer system 40 is
precisely repeatable. An advantage of template transfer system 40
being removably attached to motion stage 20 is that template
transfer system 40 may be removed after installing template 26 into
imprint head 18, which reduces the mass of motion stage 20 and
therefore does not affect stage performance during imprinting.
Similarly, sensors and vacuum conduits might be more easily
implemented if template transfer system 40 is permanently affixed
to motion stage 20, and would not require attachment or alignment
mechanisms to repeatedly install template transfer system 40 on
motion stage 20.
[0036] It is generally desirable that template transfer system 40
be located in a position on motion stage 20 that allows template
transfer system 40 to be brought to a convenient position for
loading template 26 into template transfer system 40, and then to
be brought underneath imprint head 18 without compromising wafer
imprinting. Many motion stages have a range of motion greater than
the range required to imprint the entire surface of a wafer 30,
shown in FIG. 1, mounted on wafer chuck 21, and allow mounting
template transfer system 40 on a portion of motion stage 20 that is
accessible by imprint head 18, but that does not interfere with
wafer imprinting.
[0037] Referring to FIG. 6, shown is a simplified side view of
template transfer system 40 of FIG. 5, in position to load template
26 in imprint head 18. To that end, motion stage 20 has been moved
so that template 26 in template transfer system 40 is beneath
imprint head 18. Imprint head 18 includes a pocket 42 or other
structure for receiving template 26. Vacuum and/or mechanical
retention means for holding template 26 in imprint head 18 are
omitted for simplicity of illustration. Imprint head 18 and
template 26 are placed in close proximity to one another, and
template 26 is securely retained in imprint head 18.
[0038] After loading template 26 into imprint head 18, the relative
positions of imprint head 18 and motion stage 20 are established to
imprint a wafer (not shown) loaded onto wafer chuck 21. Upon
completion of imprinting processes, template 26 may be removed from
imprint head 18 by reversing the sequence of loading steps, and
load another template into imprint head 18, if desired.
[0039] Referring to FIGS. 1, 2 and 7, important characteristics
demonstrated by template transfer system 40 is to prevent movement
of template 26 when housed therein, as well as to prevent mold
pattern 28 from being damaged and minimize particulate
contamination as a result of movement of the template 26 to and
from template transfer system 40. To that end, template transfer
system 40 includes a template transfer holder 40a and, optionally,
a template transfer gimbal 40b. Template transfer gimbal 40b allows
angular movement of template transfer holder 40a about three
orthogonal axes.
[0040] Template transfer holder 40a includes a body 50 having a
plurality of tines 52 extending from a common side 54 of body 50.
Also protruding from side 54 is a plurality of compliant members
56, each of which has a throughway 58. Throughway 58 is in fluid
communication with a channel 60, shown in FIG. 8, extending from
side 54 into body 50. A central channel 62 is in fluid
communication with one or more exit channels 64 that have couplings
66 connected to a side 68 of body 50 disposed opposite to side 54.
Couplings 66 facilitate connecting channels 60 to a pump system 70
via elastic tubing 67 coupled between channels 60 and couplings 66.
Pump system 70 may create vacuum or positive pressure, dependent
upon the application.
[0041] Referring to FIGS. 7 and 8, each of tines 52 includes an
oblique surface 52a that is substantially smooth. Oblique surface
52a extends from a first end 52b of tine 52, disposed opposite to
side 54 and extends toward a second end 52c of tine 52 positioned
between oblique surface 52a and end 52b. End 52c is coupled to, or
integrally formed with, a resilient member 53 coupled between body
50 and tine 52. Side 54 extends from end 52b and angles inwardly
toward the tine 52 disposed on an opposite edge of body 50. In this
manner, a length l.sub.1 between ends 52b of opposed tines 52 is
greater than a length l.sub.2 between ends 52c of opposed tines 52.
The dimensions of l.sub.2 are established to be slightly larger
than the template 26, shown more clearly in FIG. 9. Referring to
both FIGS. 8 and 9, resilient member 53 includes a body 53a having
a void 53b formed therein. A detent 53c is positioned proximate to
end 52c and extends therefrom to selectively contact a perimeter
region 26d of template 26. In superimposition with detent 53c is a
gap 53d extending through body 53a into void 53b to facilitate
bending of resilient member 53 about pivot point 53e. Pivot point
53e is positioned substantially opposite to gap 53d, and a moment
arm 53f extends between detent 53c and pivot point 53e. Tine 52
rests upon moment arm 53f.
[0042] Referring to both FIGS. 8 and 9, oblique surfaces 52a
function to guide template 26 onto template transfer holder 40a,
shown in FIG. 1, so as to minimize frictional contact with template
26. To that end, tines 52, shown in FIG. 7, are formed from a
compound having minimal friction, such as a Teflon.RTM.-containing
material, e.g., a PTFE-filled Acetal. An exemplary material is sold
under the tradename Delrin AF.RTM., available from DuPont.RTM..
Resilient members 53 are structured to allow tines 52 to bend
toward template 26 and clamp against template edge 26c to center
template 26 on transfer template holder 40a.
[0043] Referring to FIGS. 8, 9 and 10, to facilitate clamping of
template 26 by tines 52, shown in FIG. 7, compliant members 56 are
formed from Delrin AF.RTM. and include a suction cup 56a and a
detent 56b disposed opposite to suction cup 56a. Body 50 includes a
chamber 55 in which a boss 56c is disposed, with detent 56b being
disposed in chamber 55 resting on boss 56c. The volume of chamber
55 is greater than the volume of either detent 56b or boss 56c,
allowing the same to move freely within chamber 55 along three
orthogonal axes. Chamber 55 includes an opening 55a disposed in
side 54 through which a sub-portion of compliant member 56 passes
to allow suction cup 56a to extend from side 54. However, the cross
section of opening 55a is less than a cross section of boss 56c. As
a result, the region of body 50 surrounding opening 55a forms a
bearing surface 55b against which boss 56c bears when a vacuum is
applied to template 26. Boss 56c is coupled to a channel 60 that
extends through chamber 55. Detent 56b is resiliently biased
against a portion of boss 56c positioned proximate to opening 55a.
In this manner, compliant member 56, boss 56c and channel 60 move
as a unit within chamber 55. In the absence of a vacuum, boss 56c
rests against a bushing 56d disposed in chamber 55 to maintain boss
56c within chamber 55. An interface 56e of a surface of boss 56c
and a surface of bushing 56d has a frusto-conical shape that is
symmetrical about an axis 55c of chamber 55. The frusto-conical
shape of interface 56e centers suction cup 56a with respect to
chamber 55. To that end, tubing 67 functions as a dead weight under
force of gravity g, pulling channel 60 downwardly. Upon application
of a vacuum to template 26, pump system 70 operates to evacuate
central channel 62, thereby exerting a compression force between
compliant member 56 and template 26. The compression force urges
boss 56c against bearing surface 55b. Once boss 56c bears against
bearing surface 55b, movement along Z axis is minimized, if not
prevented. However, boss 56c may still move along the X and Y
axes.
[0044] As a result of compression of template 26 against compliant
members 56, a perimeter region 26d of template 26 bears against
detent 53c and moves along the Z axis about pivot point 53e. Member
arm 53f cantilevers toward surface 52a causing end tines 52 to move
inwardly toward template 26 until template edge 26c is compressed
by ends 52c. Each of tines 52 is arranged to move approximately the
same extent as the remaining tines 52 on body 50. The free movement
of detent 56b and boss 56c along X and Y axes, as well as the
movement of tines 52, results in template 26 being placed at a
predefined location on body 50, each time template 26 is loaded
thereon. In the present example, template 26 is centered on body
50. This is referred to as the final seating position. In the final
seating position, mold 28 is spaced-apart from side 54. To that
end, gap 53d is provided with a height h.sub.1, and mold 28 extends
from side 26b having a height, h.sub.2. Heights h.sub.1 and h.sub.2
are established to ensure that upon reaching the final seating
position mold 28 does not contact surface 52a. Thus, the structural
integrity of mold 28 is preserved, while allowing template 26 to be
removed and inserted into template transfer holder 40a with imprint
head 18, shown in FIG. 1.
[0045] Referring to FIGS. 1 and 11, shown is a simplified side view
of a template transfer system 140 that is removably mounted to
motion stage 20. Template transfer system 140 includes a transfer
substrate 144, and template 126 may be affixed thereto using
imprint material, discussed more fully below. Transfer substrate
144 can be made from any of a variety of materials, such as
aluminum, stainless steel, glass, ceramic, silicon and the like.
Further, the transfer substrate 144 may be bigger or smaller than
the production wafers (substrates) that will be imprinted. A
transfer substrate 144 that is the same size as production wafers
enables using the alignment structure on wafer chuck 21, normally
used for production wafers. With this configuration, transfer
substrate 144 is compatible for use with existing wafer handling
systems, e.g., robots, cassettes and the like. This is beneficial
because template 126 and transfer substrate 144 may be manipulated
using a wafer handling system, instead of manually.
[0046] Template transfer system 140 can be located anywhere on
transfer substrate 144 accessible by the imprint head 18. Motion
stage 20 does not need additional motion range to position template
transfer system 140 under imprint head 18. Contamination of wafer
chuck 21 by the backside of transfer substrate 144 may be reduced
by proper handling of transfer substrate 144.
[0047] Referring to FIGS. 1 and 12, shown is a simplified side view
of a template transfer system 240 on a transfer substrate 244
spaced-apart from wafer chuck 21, according to another embodiment
of the present invention. The position of template 226 and template
transfer substrate 244 may be fixed employing imprint material,
discussed more fully below. Legs 246 support transfer substrate 244
above wafer chuck 21, thereby avoiding contamination of the surface
of wafer chuck 21 from contact with the backside of transfer
substrate 244 (i.e. the side opposite template transfer system
240). Alternatively, legs 246 that extend from transfer substrate
244 onto a perimeter region of wafer chuck 21, or a perimeter ledge
or other structure, are used to support transfer substrate 244
above wafer chuck 21.
[0048] Referring to FIGS. 1 and 13, shown is a simplified cross
section of a template transfer assembly 340 having template 326
coupled to a template transfer substrate 344 with solid imprint
material 334, according to an embodiment of the present invention.
Template transfer substrate 344 could be a process wafer, for
example. Template 326 is stored on template transfer substrate 344
when not in use, and template 326 can be loaded from template
transfer substrate 344 into imprint head 18.
[0049] When it is desired to unload and store template 326 from
imprint head 18 (e.g. after imprinting a run of process wafers),
template transfer substrate 344 is mounted on wafer chuck 21. A
selected volume of imprinting material is applied in a fluid state
to the region of template transfer substrate 344 that template 326
will be attached to. The volume of fluid may be less than, the same
as, or greater than the volume of imprinting material that would be
used to imprint a production wafer.
[0050] Template 326 is brought into contact with the imprinting
material, and the imprinting material is polymerized or otherwise
solidified fixedly affixing template 326 to template transfer
substrate 344. Rather than increasing a distance between the
imprint head 18 and the wafer chuck 21, vacuum and/or mechanical
retaining means may be deactivated to release template 326 from the
imprint head 18. Template 326 adheres to template transfer
substrate 344 with solid imprint material 334, and may be moved
therewith to a remote storage location.
[0051] Alternatively, template transfer substrate 344 may be left
on the wafer chuck 21 and template 326 is removed from or retained
in the imprint head 18. In each case, solid imprint material 334
protects the mold pattern 328 on template 326 when not in use.
Solid imprint material 334 seals template 326 from contamination
and the mold pattern 328 on the face of template 326 is protected
from damage. This may be achieved by covering the entire area of
mold pattern 328 with the imprint material 334, thereby
hermetically sealing mold pattern 328.
[0052] When template 326 is removed from the imprint head 18 for
storage again, a new or reworked template transfer substrate is
used. Alternatively, the same substrate may be employed to store
template 326, but the template 326 would be stored in a differing
region thereof. A template transfer substrate 344 is reworked by
removing solid imprint material 334 from template transfer
substrate 344. Process wafers rejected before imprinting are often
convenient for use as template transfer substrates 344.
[0053] Alternatively, as shown in FIG. 14, template transfer holder
440 may include having imprinting material 434 applied to a
sub-portion 428a of mold pattern 428. To that end, the imprint
material 434 is applied in sufficient quantity to allow sub-portion
428a to be spaced-apart from both the template transfer substrate
444 and the imprint material 434. Further, by circumscribing
sub-portion 428a with imprinting material 434, sub-portion 428a may
be encapsulated, e.g., hermetically sealed so that the only
atmosphere to which mold pattern 428 is exposed is present in
volume 434a to which sub-portion 428a is exposed. This prevents
ingress of contamination into sub-portion 428a of mold pattern 428
during storage.
[0054] When it is desired to store template 426, the same may be
attached to template transfer substrate 444 with solid imprint
material 434 to fixedly attach template transfer substrate 444 to
template 426. To that end, template transfer substrate 444, having
imprinting material 434, is loaded onto the wafer chuck 21 and
template 426 is moved to a position underneath the imprint head 18
(if not already loaded). Relative movement between the imprint head
18 and template 426 is achieved to reduce the spacing therebetween,
placing the imprint head 18 and the template 426 in close proximity
or contact. The template 426 is secured to the imprint head 18 by
means of a vacuum and/or mechanical coupling. The imprint head 18,
along with template 426 is placed in superimposition with template
transfer substrate 444. Thereafter, contact is made between
template 426 and imprint material 434 present on template transfer
substrate 444. The imprint material 434 is then solidified, as
discussed above, securely affixing template 426 to template
transfer substrate 444.
[0055] Referring to FIG. 15, shown is a simplified cross section of
a template transfer holder 540 having a template 526 coupled to the
template transfer substrate 544 with a perimeter of solid imprint
material 534 according to another embodiment of the present
invention to fixedly attach template transfer substrate 544 to
template 526. In this configuration, the entire mold pattern 528
may be encapsulated, e.g., hermetically sealed as discussed above
with respect to FIG. 14. Further, template 526 may, optionally,
include a perimeter mesa 536 that forms a perimeter recess 537
around the mold pattern 528. Imprint material 534 does not adhere
to a mold pattern 528 on template 526, thus facilitating mold
fidelity.
[0056] To store template 526 on template transfer substrate 544, a
selected volume of imprinting material 534 is applied in a fluid
state to a surface 531 of template transfer substrate 544. The
imprinting material 534 may be applied to a selected area (e.g. an
area corresponding to the perimeter of template 526), or the volume
of imprinting material 534 is selected to adhere to the perimeter
mesa 536 only, and to not fill in areas of mold pattern 528 on
template 526. Recess 537 prevents fluid imprinting material 534
from reaching mold pattern 528 when mechanical contact is made
between the imprinting material 534 and template 526.
[0057] FIG. 16 is a simplified cross section of a template transfer
assembly 640 having a template 626, a mesa 636 and a major surface
626a disposed opposite to the mesa 636. A mold pattern 628 is
included on the mesa 636 as having grooves 628a and protrusions
628b. The grooves 628a include a nadir surface 628c and the
protrusions 628b include an apex surface 628d. A surface 638
circumscribes, if not all, then a subset of the grooves 628a and
the protrusions 628b. One or more of nadir surfaces 628c are spaced
apart from major surface 626a a first distance d.sub.1, and one or
more apex surfaces 628d are spaced-apart from major surface 626a a
second distance, d.sub.2. Surface 638 is spaced apart from major
surface 626a a third distance, d.sub.3. Mesa 636 is defined by
ensuring third distance d.sub.3 differs from both first and second
distances, d.sub.1 and d.sub.2. In the specific example, distance
d.sub.3 is less than either of distances d.sub.1 and d.sub.2.
Imprinting material 634 is disposed in regions between surface 638
and surface 631 of template transfer substrate 644. In this
fashion, imprint material 634 may be employed to maintain a fixed
position between template 626 and template transfer substrate 644
without imprint material 634 contacting mold pattern 628 on
template 626. Additionally, imprinting material 634 may be disposed
so as to encapsulate mold pattern 628, e.g., hermetically seal the
same, as discussed above. In this manner, mold pattern 628 is
protected from physical damage and contamination.
[0058] To store template 626 a selected volume of imprinting
material 634 is applied in a fluid state to a surface 631 of
template transfer substrate 644. The imprinting material 634 is
applied to a region of surface 631 that will be in superimposition
with surface 638. The volume of imprinting material 634 typically
selected is sufficient to adhere template 626 to the template
transfer substrate 644 so that mold pattern 628 is spaced-apart
from surface 631. Although it is not necessary, imprinting material
634 may circumscribe mold pattern 628, thereby encapsulating the
same to prevent contamination by particulate matter.
[0059] Referring to FIGS. 1 and 17, during operation of imprint
lithography system 10, template 26 is loaded onto template transfer
system 40 at step 702. Template 26 is moved to a position beneath
an imprint head 18 at step 704 and the spacing between the imprint
head 18 and template 26 is reduced at step 706 to place the imprint
head 18 in close proximity, or in contact, with the template 26.
The template 26 is secured to the imprint head 18 at step 708, and
the distance between template transfer holder 40a and imprint head
18 is increased at step 710. The template transfer holder 40a is
moved to a second position that is not beneath the imprint head 18
at step 712. In a further embodiment, the template transfer holder
40a is removed from the motion stage 20 at step 714 and a process
wafer 30 is loaded on a wafer chuck 21 of the motion stage 20 for
imprinting with the template 26. Although the foregoing has been
discussed with respect to template transfer system 40, it should be
understood that the operation discussed with respect to FIG. 17
applies when using template transfer systems, 140, 240, 340, 440,
540 and 640, shown in FIGS. 11, 12, 13, 14, 15 and 16,
respectively.
[0060] FIG. 18 is a simplified flow chart of a method 720 of
removing a template 26, shown in FIG. 1, from an imprint head 18 in
an imprint lithography system 10, according to another embodiment
of the present invention. A template transfer substrate, such as
template transfer substrates 144, 244, 344, 444, 544 and 644, shown
in FIGS. 11, 12, 13, 14, 15 and 16, respectively, may be employed.
For simplicity of discussion, the present example is discussed with
respect to template transfer substrate 444, shown in FIG. 14, and
applies with equal weight to the aforementioned template transfer
substrates. At step 722, template transfer substrate 444 is loaded
onto a wafer chuck 21 in imprint lithography system 10. A selected
volume of imprinting fluid is dispensed onto the surface of the
template transfer substrate 444 at step 724. Relative movement
between the imprint head 18 holding a template 26 and the template
transfer substrate 444 is achieved so that the template 26 contacts
the imprinting fluid at step 726. The imprinting fluid is converted
to solid imprint material at step 728. The template 26 is released
from the imprint head 18 (e.g. by turning off the securing means
and raising the imprint head 18) and the template transfer
substrate 444 with the attached template 26 is removed from the
wafer chuck 21 and transferred to a storage location at step 730.
Alternatively, the template 26 remains attached to the template
transfer substrate 444 on the wafer chuck 21 and the imprint head
18 and the template 26 are arranged to be spaced-apart at step
730a. In yet another alternative, the template 26 is left in the
imprint head 18 attached to the template transfer substrate 444 for
storage on the wafer chuck 21 at step 730b.
[0061] FIG. 19 is a simplified flow chart of a method 740 of
installing a template 26, shown in FIG. 1, from a template transfer
substrate 444, shown in FIG. 14, into an imprint head 18 of an
imprint lithography system 10, according to yet another embodiment
of the present invention. A template transfer substrate 444 with a
template 26 adhered to the template transfer substrate 444 with
imprint material 434 is provided at step 742. The template transfer
substrate 444 is loaded onto a wafer chuck 21 of a wafer 30 in
imprint lithography system 10 at step 744. Alternatively, the
template transfer substrate 444 is already on the wafer chuck 21,
as when the template 26 is stored in this fashion between uses. The
wafer chuck 21 is moved to position the template 26 beneath an
imprint head 18 of the wafer 30 in imprint lithography system 10 at
step 746. Alternatively, a template 26 stored on a template
transfer substrate 444 is already beneath the imprint head 18.
Relative movement between the imprint head 18 and the template 26
is achieved to place the imprint head 18 and template 26 in close
proximity or contact at step 748. The template 26 is secured to the
imprint head 18 at step 750. The distance between imprint head 18
and template transfer substrate 444 is increased at step 752,
releasing the template 26 from the imprint material 434. The
template transfer substrate 444 is removed from the wafer chuck 21
and a process wafer 30 may then be loaded onto the wafer chuck 21
for imprinting with the template 26.
[0062] The embodiments of the present invention described above are
exemplary. Many changes and modifications may be made to the
disclosure recited above, while remaining within the scope of the
invention. Therefore, the scope of the invention should be
determined not with reference to the above description, but instead
should be determined with reference to the appended claims along
with their full scope of equivalents.
* * * * *