U.S. patent application number 10/788700 was filed with the patent office on 2005-09-01 for full-wafer or large area imprinting with multiple separated sub-fields for high throughput lithography.
This patent application is currently assigned to MOLECULAR IMPRINTS, INC.. Invention is credited to Sreenivasan, Sidlgata V..
Application Number | 20050189676 10/788700 |
Document ID | / |
Family ID | 34887055 |
Filed Date | 2005-09-01 |
United States Patent
Application |
20050189676 |
Kind Code |
A1 |
Sreenivasan, Sidlgata V. |
September 1, 2005 |
Full-wafer or large area imprinting with multiple separated
sub-fields for high throughput lithography
Abstract
The present invention is directed to a method of forming a layer
on a substrate comprising forming a plurality of flowable regions
on the substrate and contacting the flowable regions with a
plurality of molds disposed on a template. Thereafter, the
plurality of flowable regions is solidified. In a further
embodiment, the method further includes spreading each of the
plurality of flowable regions to an area.
Inventors: |
Sreenivasan, Sidlgata V.;
(Austin, TX) |
Correspondence
Address: |
MOLECULAR IMPRINTS, INC.
KENNETH C. BROOKS
PO BOX 81536
AUSTIN
TX
78708-1536
US
|
Assignee: |
MOLECULAR IMPRINTS, INC.
1807-c west braker lane
Austin
TX
|
Family ID: |
34887055 |
Appl. No.: |
10/788700 |
Filed: |
February 27, 2004 |
Current U.S.
Class: |
264/225 |
Current CPC
Class: |
H01L 21/76817 20130101;
G03F 7/0002 20130101; B82Y 10/00 20130101; B82Y 40/00 20130101 |
Class at
Publication: |
264/225 |
International
Class: |
B29C 067/00; B29C
033/40 |
Claims
What is claimed is:
1. A method of forming a layer on a substrate, said method
comprising: forming a plurality of flowable regions on said
substrate; contacting said flowable regions with a plurality of
molds disposed on a template; and solidifying said plurality of
flowable regions.
2. The method as recited in claim 1, wherein forming further
includes forming said plurality of flowable regions as an integer
multiple of said plurality of molds.
3. The method as recited in claim 1 further including spreading a
material in said plurality of flowable regions over said substrate
while confining said material associated with each of said
plurality of flowable regions to an area.
4. The method as recited in claim 1, wherein contacting further
includes flexing said template to conform to a topography of said
substrate.
5. The method as recited in claim 1, wherein solidifying further
includes applying electromagnetic activation energy to said
plurality of flowable regions.
6. The method as recited in claim 1, wherein contacting further
includes flexing said template at a region between adjacent molds
of said plurality of molds.
7. The method as recited in claim 1, wherein forming further
includes forming said plurality of flowable regions
concurrently.
8. The method as recited in claim 1, wherein forming further
includes forming each of said plurality of flowable regions to be
spaced-apart from adjacent flowable regions of said plurality of
flowable regions.
9. A method of forming a layer on a substrate, said method
comprising: forming a plurality of flowable regions on a surface of
said substrate; providing each of said plurality of flowable
regions with a surface having a desired shape; and solidifying said
plurality of flowable regions.
10. The method as recited in claim 9, wherein providing further
includes contacting said plurality of flowable regions with a
plurality of molds disposed on a template.
11. The method as recited in claim 10, wherein forming further
includes forming said plurality of flowable regions as an integer
multiple of said plurality of molds.
12. The method as recited in claim 10, wherein contacting further
includes flexing said template to conform to a topography of said
substrate.
13. The method as recited in claim 9, wherein solidifying further
includes applying electromagnetic activation energy to said
plurality of flowable regions.
14. The method as recited in claim 10, wherein contacting further
includes flexing said template at a region between adjacent molds
of said plurality of molds.
15. The method as recited in claim 9 further including spreading a
material in said plurality of flowable regions over said substrate
while confining said material associated with each of said
plurality of flowable regions to an area.
16. A method of forming a layer on a substrate, said method
comprising: forming a plurality of flowable regions on said
substrate; spreading a material in said plurality of flowable
regions over said substrate while confining said material
associated with each of said plurality of flowable regions to an
area; contacting said flowable regions with a plurality of molds
disposed on a template; and solidifying said plurality of flowable
regions.
17. The method as recited in claim 16, wherein forming further
includes forming said plurality of flowable regions as an integer
multiple of said plurality of molds.
18. The method as recited in claim 16, wherein contacting further
includes flexing said template to conform to a topography of said
substrate.
19. The method as recited in claim 16, wherein solidifying further
includes applying electromagnetic activation energy to said
plurality of flowable regions.
20. The method as recited in claim 16, wherein contacting further
includes flexing said template at a region between adjacent molds
of said plurality of molds.
Description
BACKGROUND OF THE INVENTION
[0001] The field of invention relates generally to imprint
lithography. More particularly, the present invention is directed
to a method of depositing and patterning materials on a substrate
during imprint lithography processes.
[0002] Micro-fabrication involves the fabrication of very small
structures, e.g., having features on the order of micro-meters or
smaller. One area in which micro-fabrication has had a sizeable
impact is in the processing of integrated circuits. As the
semiconductor processing industry continues to strive for larger
production yields while increasing the circuits per unit area
formed on a substrate, micro-fabrication becomes increasingly
important. Micro-fabrication provides greater process control while
allowing increased reduction of the minimum feature dimension of
the structures formed. Other areas of development in which
micro-fabrication has been employed include biotechnology, optical
technology, mechanical systems and the like.
[0003] An exemplary micro-fabrication includes forming a relief
image in a structure by depositing a polymerizable fluid
composition onto a transfer layer. The transfer layer may be a
sacrificial layer providing a mask for patterning the substrate or
the substrate itself. A mold makes mechanical contact with the
polymerizable fluid. The mold includes a relief structure, and the
polymerizable fluid composition fills the relief structure. The
polymerizable fluid composition is then subjected to conditions to
solidify and to polymerize the same, forming a solidified polymeric
material on a transfer layer that contains a relief structure
complimentary to that of the mold. The mold is then separated from
the solid polymeric material such that a replica of the relief
structure in the mold is formed in the solidified polymeric
material. The solidified polymeric material is subjected to an
environment to selectively etch the transfer layer relative to the
solidified polymeric material such that a relief image is formed in
the transfer layer. With this process, patterns with features on
the scale of a few nanometers may be formed. As a result,
substrates may demonstrate extreme topologies when compared to the
dimensions of features formed thereon, wherein such extreme
topologies may potentially prevent accurate reproduction of the
pattern in the solidified polymeric layer.
[0004] In order to maximize the throughput and to minimize the cost
of micro-fabrication, an increase in the size of the wafer being
subjected to patterning is desired. However, increasing the wafer
size not only exacerbates the non-planarity of the substrate being
patterned, but also increases the filling time needed to dispense
the polymerizable fluid composition upon the substrate, both of
which are undesirable.
[0005] It is desired, therefore, to provide an improved method of
dispensing and patterning a material upon a full-wafer or large
area wafer.
SUMMARY OF THE INVENTION
[0006] The present invention is directed to a method of forming a
layer on a substrate comprising forming a plurality of flowable
regions on the substrate and contacting the flowable regions with a
plurality of molds disposed on a template. Thereafter, the
plurality of flowable regions is solidified. In a further
embodiment, the method further includes spreading each of the
plurality of flowable regions to an area. These and other
embodiments are discussed below.
BRIEF DESCRIPTION OF THE DRAWINGS
[0007] FIG. 1 is a perspective view of a lithographic system in
accordance with the present invention;
[0008] FIG. 2 is a simplified elevation view of a lithographic
system shown in FIG. 1;
[0009] FIG. 3 is a simplified representation of material from which
an imprinting layer shown in FIG. 2 is comprised before being
polymerized and cross-linked;
[0010] FIG. 4 is a simplified representation of cross-linked
polymer material into which the material shown in FIG. 3 is
transformed after being subjected to radiation;
[0011] FIG. 5 is a simplified elevation cross-sectional view of a
mold spaced-apart from the imprinting layer, shown in FIG. 1, after
patterning of the imprinting layer;
[0012] FIG. 6 is a simplified elevational view of the template,
shown in FIGS. 1 and 2, in accordance with the present
invention;
[0013] FIG. 7 is a simplified elevational view of a dispensing
system, shown in FIG. 1, in accordance with the present
invention;
[0014] FIG. 8 is a detailed view demonstrating the non-planarity of
the substrate in accordance with the prior art;
[0015] FIGS. 9A-9B are simplified plan views of a template employed
to pattern the substrate, shown in Fig. 5, in accordance with the
present invention;
[0016] FIG. 10 is a simplified plan view showing the template,
shown in FIG. 9A, in contact with the imprinting material disposed
on the substrate, shown in FIG. 8;
[0017] FIG. 11 is simplified plan view showing the various patterns
that may be included with the template, shown in FIGS. 2 and 9A, in
accordance with the present invention; and
[0018] FIG. 12 is a simplified plan view showing the template
coupled to a device to apply pressure to one side of the template
in accordance with an alternate embodiment of the present
invention.
DETAILED DESCRIPTION OF THE INVENTION
[0019] FIG. 1 depicts a lithographic system 10 in accordance with
one embodiment of the present invention that includes 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, which
extends from bridge 14 toward stage support 16 and provides
movement along the Z-axis. Disposed upon stage support 16 to face
imprint head 18 is a motion stage 20. Motion stage 20 is configured
to move with respect to stage support 16 along X- and Y-axes. It
should be understood that imprint head 18 may provide movement
along the X- and Y-axes, as well as the Z-axis, and motion stage 20
may provide movement in the Z-axis, as well as the X- and Y-axes.
An exemplary motion stage device is disclosed in U.S. patent
application Ser. No. 10/194,414, filed Jul. 11, 2002, entitled
"Step and Repeat Imprint Lithography Systems," assigned to the
assignee of the present invention, and which is incorporated by
reference herein in its entirety. A radiation source 22 is coupled
to lithographic system 10 to impinge actinic radiation upon motion
stage 20. As shown, radiation source 22 is coupled to bridge 14 and
includes a power generator 23 connected to radiation source 22.
Operation of lithographic system 10 is typically controlled by a
processor 25 that is in data communication therewith. An exemplary
system 10 is available under the trade name IMPRIO 100.TM. from
Molecular Imprints, Inc. having a place of business at 1807-C
Braker Lane, Suite 100, Austin, Tex. 78758. The system description
for the IMPRIO 100.TM. is available at www.molecularimprints.com
and is incorporated herein by reference.
[0020] Referring to both FIGS. 1 and 2, connected to imprint head
18, via a chuck 27, is a template 26 having a mold 28 thereon. An
exemplary chuck is disclosed in U.S. patent application Ser. No.
10/293,224, filed Nov. 13, 2003, entitled "A Chucking System for
Modulating Shapes of Substrates," which is assigned to the assignee
of the present invention and is incorporated by reference in its
entirety herein. Mold 28 includes a plurality of features defined
by a plurality of spaced-apart recessions 28a and protrusions 28b.
The plurality of features defines an original pattern that forms
the basis of a pattern to be transferred into a substrate 30
positioned on motion stage 20. To that end, imprint head 18 and/or
motion stage 20 may vary a distance "d" between mold 28 and
substrate 30. In this manner, the features on mold 28 may be
imprinted into a flowable region of substrate 30, discussed more
fully below. Radiation source 22 is located so that mold 28 is
positioned between radiation source 22 and substrate 30. As a
result, mold 28 is fabricated from a material that allows it to be
substantially transparent to the radiation produced by radiation
source 22.
[0021] Referring to both FIGS. 2 and 3, a flowable region, such as
an imprinting layer 34, is disposed on a portion of a surface 32
that presents a substantially planar profile. In the present
embodiment, a flowable region consists of imprinting layer 34 being
deposited as a plurality of spaced-apart discrete droplets 36 of a
material 36a on substrate 30, discussed more fully below. An
exemplary system for depositing droplets 36 is shown as a
dispensing system 70, in FIG. 1, and is discussed more fully below
with reference to FIG. 7.
[0022] Referring again to FIGS. 2 and 3, imprinting layer 34 is
formed from material 36a that may be selectively polymerized and
cross-linked to record the original pattern therein, defining a
recorded pattern. An exemplary composition for material 36a is
disclosed in U.S. patent application Ser. No. 10/463,396, filed
Jun. 16, 2003, and entitled "Method to Reduce Adhesion Between a
Conformable Region and a Pattern of a Mold," which is incorporated
by reference in its entirety herein. Material 36a is shown in FIG.
4 as being cross-linked at points 36b, forming a cross-linked
polymer material 36c.
[0023] Referring to FIGS. 2, 3 and 5, the pattern recorded in
imprinting layer 34 is produced, in part, by mechanical contact
with mold 28. To that end, distance "d" is reduced to allow
imprinting droplets 36 to come into mechanical contact with mold
28, spreading droplets 36 so as to form imprinting layer 34 with a
contiguous formation of material 36a over surface 32. In one
embodiment, distance "d" is reduced to allow sub-portions 34a of
imprinting layer 34 to ingress into and to fill recessions 28a.
[0024] To facilitate filling of recessions 28a, material 36a is
provided with the requisite properties to completely fill
recessions 28a, while covering surface 32 with a contiguous
formation of material 36a. In the present embodiment, sub-portions
34b of imprinting layer 34 in superimposition with protrusions 28b
remain after the desired, usually minimum, distance "d", has been
reached, leaving sub-portions 34a with a thickness t.sub.1, and
sub-portions 34b with a thickness t.sub.2. Thicknesses "t.sub.1"
and "t.sub.2" may be any thickness desired, dependent upon the
application. Typically, t.sub.1 is selected so as to be no greater
than twice the width u of sub-portions 34a, i.e., t.sub.1.ltoreq.2
u, shown more clearly in FIG. 5.
[0025] Referring to FIGS. 2, 3 and 4, after a desired distance "d"
has been reached, radiation source 22 produces actinic radiation
that polymerizes and cross-links material 36a, forming cross-linked
polymer material 36c. As a result, the composition of imprinting
layer 34 transforms from material 36a to cross-linked polymer
material 36c, which is a solid. Specifically, cross-linked polymer
material 36c is solidified to form solidified imprinting layer 134
with a side having a shape that conforms to a shape of a surface
28c of mold 28, shown more clearly in FIG. 5. After formation of
solidified imprinting layer 134, distance "d" is increased so that
mold 28 and solidified imprinting layer 134 are spaced-apart.
[0026] Referring to FIG. 5, additional processing may be employed
to complete the patterning of substrate 30. For example, substrate
30 and imprinting layer 34 may be etched to transfer the pattern of
imprinting layer 34 into substrate 30. To facilitate etching, the
material from which imprinting layer 34 is formed may be varied to
define a relative etch rate with respect to substrate 30, as
desired. The relative etch rate of imprinting layer 34 to substrate
30 may be in a range of about 1.5:1 to about 100:1.
[0027] Referring to FIGS. 3 and 6, typically template 26 includes a
plurality of molds, shown as 40, 42, 44, and 46, each of which may
include a common pattern or differing patterns. Further, molds 40,
42, 46, and 48 may be arranged on template 26 as a matrix. Although
four molds are shown, any number may be present. Each of molds 40,
42, 44, and 46 may be described as mold 28 with respective
lithographic processes that apply to mold 28 apply with equal
measure to each of molds 40, 42, 44, and 46. Each of molds 40, 42,
44, and 46 are separated from an adjacent mold 40, 42, 44, and 46
by a recess. As shown, a recess 50 is defined between molds 40 and
42, a recess 52 is defined between molds 42 and 46, and a recess 54
is defined between molds 46 and 48. The height, h.sub.1, h.sub.2,
and h.sub.3, of each recess 50, 52, and 54, respectively, are
substantially greater than the depth of recession 28a, shown in
FIG. 2. As a result, upon application of the appropriate forces
between template 26 and material 36a, material 36a in
superimposition with each of molds 40, 42, 44, and 46 will not
extrude from a region of substrate 30 coextensive with molds 40,
42, 44, and 46. It is believed that this is due in part to
capillary attraction between molds 40, 42, 44, and 46 and material
36a in superimposition therewith. This allows spreading of material
36a to cover an area of substrate 30 that has a desired shape as
defined by the shape of molds 40, 42, 44, and 46. For example, the
area of substrate 30 over which material 36a may be spread may have
any geometric shape known, e.g., circular, polygonal, and the
like.
[0028] Referring to FIGS. 6 and 7, taking advantage of these
properties, imprinting layer 34 may be formed on substrate 30 as a
plurality of spaced-apart layer segments, shown as 60, 62, 64, and
66. To that end, dispensing system 70 may include a plurality of
jet nozzles 72, each of which is in fluid communication with one or
more of a plurality of material reservoirs 74. The number of jet
nozzles 72 may be equal to an integer multiple of the number of
molds present on template 26. Material reservoirs 74 contain
material to be deposited on substrate 30, such as material 36a,
shown in FIG. 3, or some other material.
[0029] Referring to FIGS. 1 and 7, an exemplary system implemented
as fluid dispensing system 70 is described by Steinerta et al. in
"An Improved 24 Channel Picoliter Dispenser Based on Direct Liquid
Displacement," published at The 12th International Conference on
Solid State Sensors, Actuators and Microsystems, Boston, Jun. 8-12,
2003. Specifically, by providing material reservoirs 74 with
material 36a, shown in FIG. 3, a plurality of flowable regions may
be formed on substrate 30 concurrently. As shown, the first
flowable region includes droplets 80; a second flowable region
includes droplets 82; a third flowable region includes droplets 84;
and a fourth flowable region includes droplets 86. Droplets 80, 82,
84, and 86 may be dispensed upon substrate 30 in identical
patterns.
[0030] Upon dispensing droplets 80, 82, 84, and 86 upon substrate
30, droplets 80, 82, 84, and 86 may be patterned according to molds
40, 42, 44, and 46. Specifically droplets 80 may be patterned by
mold 40 forming layer segment 60; droplets 82 may be patterned by
mold 42 forming layer segment 62; droplets 84 may be patterned by
mold 44 forming layer segment 64; and droplets 86 may be patterned
by mold 46 forming layer segment 66.
[0031] As a result of forming the plurality of flowable regions on
substrate 30 concurrently, any evaporative effects of material 36a,
shown in FIG. 3, will be substantially identical within droplets
80, 82, 84 and 86. This facilitates control of the thickness of
solidified imprinting layer so that all thicknesses t.sub.1 are
substantially uniform and all thicknesses t.sub.2 are substantially
uniform. As a result, the dimensions of the features transferred
into substrate 30 may be precisely controlled. This minimizes
undesirable etch rate differentials over the area of solidified
imprinting layer. Additionally the time required to form a
patterned layer is reduced, because the time in which multiple
droplets 80, 82, 84, and 86 are dispensed and fill the features of
mold 28, e.g., the fill time, is equivalent to the time required to
dispense a single droplet. The fill time is on the order of
seconds.
[0032] As mentioned above, each of molds 40, 42, 44, and 46 makes
mechanical contact with droplets 80, 82, 84, and 86, respectively.
However, the area of substrate 30 that is covered with droplets 80,
82, 84, and 86 may comprise an extreme topology when compared to
the dimensions of features formed thereon. An example of such an
extreme topology is depicted in FIG. 8, wherein substrate 30
appears to present a non-planar surface 90. This has been
traditionally found in substrates formed from gallium arsenide
(GAs) or indium phosphide (InP). However, as the feature dimensions
decrease, substrates that have historically been considered planar
may present a non-planar surface to features formed thereon. For
example, substrate 30 is shown with variations in surface
height.
[0033] The variations in surface height of substrate 30 frustrates
the patterning of droplets 80, 82, 84, and 86 because of the
resulting differences in distances between surface regions 92 and
94 as measured from a backside 96 of substrate 30, as h.sub.1 and
h.sub.2, respectively. The height differential, .DELTA.h, between
regions 92 and 94 is defined as follows:
.DELTA.h=.vertline.h.sub.1-h.sub.2.vertline. (1)
[0034] Height differential, .DELTA.h, may be problematic during the
imprinting process and/or one or more post imprinting process,
e.g., etching.
[0035] Referring to FIGS. 8 and 9A, to overcome the problems
resulting from height differential, .DELTA.h, template 26 may be
made to conform to non-planar surface 90 for patterning liquids,
such as material 36a, shown in FIG. 3, disposed on substrate 30.
Specifically, template 26 includes a body 100 having opposed first
surface 102 and second surface 104. First surface 102 includes a
plurality of recessed regions 106 with molds 40, 42, 44, and 46
being disposed between adjacent recessed regions 106. Specifically,
recessed regions 106 define flexure regions 108 about which each of
molds 40, 42, 44, and 46 may move independent of one another. As
shown, molds 40, 42, 44, and 46 are areas of second surface 104
positioned between adjacent flexure regions 108.
[0036] Referring to FIG. 9B, in a further embodiment, body 100
comprises a third surface 105. Third surface 105 includes a
plurality of recessed regions 107, wherein recessed regions 107
define flexure regions 109 and may be described analogously to
recessed regions 106, shown in FIG. 9A.
[0037] Referring to both FIGS. 3 and 10, during imprinting of
material 36a, template 26 compresses material 36a between second
surface 104 and non-planar surface 90 forming imprinting layer 34,
and more specifically mold 40 compresses material 36a forming layer
segment 60 of imprinting layer 34; mold 42 compresses material 36a
forming layer segment 62 of imprinting layer 34; mold 44 compresses
material 36a forming layer segment 64 of imprinting layer 34; and
mold 46 compresses material 36a forming layer segment 66 of
imprinting layer 34. Recessed regions 106 allow flexing of body 100
about the plurality of flexure regions 108. In this manner,
template 26 conforms to the profile of non-planar surface 90
defined, in part, by the height differential .DELTA.h. Material 36a
may be disposed on non-planar surface 90 and solidified, as
described above with respect to FIGS. 1-5. As mentioned above,
molds 40, 42, 44, and 46 may comprise any type of pattern, such as
uniform periodic features having common shapes, as well as features
having differing shapes. Exemplary patterns include a series of
linear grooves/projections 110, a series of L-Shaped
grooves/projections 112, a series of intersecting
grooves/projections defining a matrix 114, a series of arcuate
grooves/projections 116, and pillars 118 that have any
cross-sectional shape desired, e.g., circular, polygonal, etc.,
shown in FIG. 11.
[0038] Referring to FIG. 12, to facilitate conforming template 26
to a surface, a fluid source, such as a pump 120, may be placed in
fluid communication with first surface 102 to vary a pressure
present. To that end, a fluid chamber 122 includes an inlet 124 and
a throughway 126. Template 26 is mounted in throughway 126 to
substantially restrict fluid flow there through. As a result
template 26 and sides 128, 130, and 132 define a volume 136. Sides
128, 130, and 132 may be more rigid than template 26. In this
fashion, template 26 may be more sensitive to variations in
pressure changes occurring in volume 136 than sides 128, 130, and
132. As a result, pump 120 may pressurize or evacuate volume 136 as
desired to vary a shape of template 26 to facilitate conformation
of template 26 with a surface adjacent to second side 104.
[0039] Referring to FIGS. 1, 3 and 6, the characteristics of
material 36a are important to efficiently pattern substrate 30 in
light of the unique deposition process employed. As mentioned
above, material 36a is deposited on substrate 30 as a plurality of
discrete and spaced-apart droplets 36. The combined volume of
droplets 36 is such that the material 36a is distributed
appropriately over an area of surface 32 where imprinting layer 34
is to be formed. As a result, imprinting layer 34 is spread and
patterned concurrently with the pattern being subsequently set by
exposure to radiation, such as electromagnetic activation
radiation. As a result of the deposition process, it is desired
that material 36a have certain characteristics to facilitate rapid
and even spreading of material 36a in droplets 36 over surface 32
so that the all thicknesses t.sub.1 are substantially uniform and
all thickness t.sub.2 are substantially uniform. Exemplary
materials are disclosed in U.S. patent application Ser. No.
10/463,396, filed Jun. 17, 2003, entitled "Method to Reduce
Adhesion between a Conformable Region and a Pattern of a Mold," and
which is incorporated by reference herein in its entirety.
[0040] The embodiments of the present invention described above are
exemplary. For example, anomalies in processing regions other than
film thickness may be determined. For example, distortions in the
pattern may formed in imprinting layer may be sensed and the cause
of the same determined employing the present invention. As a
result, 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 not be
limited by the above description, but instead should be determined
with reference to the appended claims along with their full scope
of equivalents.
* * * * *
References