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Publication numberUS20050270516 A1
Publication typeApplication
Application numberUS 10/999,898
Publication dateDec 8, 2005
Filing dateNov 30, 2004
Priority dateJun 3, 2004
Also published asCN1981236A, CN1981236B, DE602005023153D1, EP1754108A2, EP1754108A4, EP1754108B1, EP2207061A2, EP2207061A3, EP2207061B1, EP2267531A2, EP2267531A3, US7298456, US7420654, US20050269745, US20060001194, WO2005121892A2, WO2005121892A3
Publication number10999898, 999898, US 2005/0270516 A1, US 2005/270516 A1, US 20050270516 A1, US 20050270516A1, US 2005270516 A1, US 2005270516A1, US-A1-20050270516, US-A1-2005270516, US2005/0270516A1, US2005/270516A1, US20050270516 A1, US20050270516A1, US2005270516 A1, US2005270516A1
InventorsAnshuman Cherala, Byung-Jin Choi, Pawan Nimmakayala, Mario Meissl, Sidlgata Sreenivasan
Original AssigneeMolecular Imprints, Inc.
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
System for magnification and distortion correction during nano-scale manufacturing
US 20050270516 A1
Abstract
The present invention is directed toward a system to vary dimensions of a substrate, such as a template having a patterned mold. To that end, the system includes a substrate chuck adapted to position the substrate in a region; a pliant member; and an actuator sub-assembly elastically coupled to the substrate chuck through the pliant member. The actuator assembly includes a plurality of lever sub-assemblies, one of which includes a body lying in the region and spaced-apart from an opposing body associated with one of the remaining lever sub-assemblies of the plurality of lever sub-assemblies. One of the plurality of lever assemblies is adapted to vary a distance between the body and the opposing body. In this manner, compressive forces may be applied to the template to remove unwanted magnification or other distortions in the pattern on the mold. The pliant member is configured to attenuate a magnitude of resulting forces sensed by the substrate chuck generated in response to the compressive forces.
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Claims(42)
1. An apparatus to vary dimensions of a substrate, said apparatus comprising:
a substrate chuck adapted to position said substrate in a region;
a pliant member; and
an actuator sub-assembly elastically coupled to said substrate chuck through said pliant member, with said actuator assembly including a plurality of lever sub-assemblies one of which includes a body lying in said region and spaced-apart from an opposing body associated with one of the remaining lever sub-assemblies of said plurality of lever sub-assemblies, with one of said plurality of lever sub-assemblies being adapted to vary a distance between said body and said opposing body.
2. The apparatus as recited in claim 1 wherein said body and said opposing body are positioned to receive said substrate therebetween and apply compressive forces thereto, with said pliant member configured to attenuate a magnitude resulting forces sensed by said substrate chuck generated in response to said compressive forces.
3. The apparatus as recited in claim 1 further including a flexure, with said substrate chuck being fixedly attached to said flexure and a first end of said pliant member being fixedly attached to said actuator assembly and a second end of said pliant member being fixedly attached to said flexure.
4. The apparatus as recited in claim 1 further including a flexure, with said substrate chuck being fixedly attached to said flexure and said pliant member being coupled between said flexure and said actuator sub-assembly to facilitate translational movement therebetween along two orthogonal axes lying in a common plane, while restricting translation movement along an additional axis extending normal to said plane.
5. The apparatus as recited in claim 4 wherein said pliant member facilitates rotational movement about said additional axis.
6. The apparatus as recited in claim 1 wherein said actuator assembly includes additional bodies, with said additional bodies and said body and said opposing body defining a plurality of bodies, with said plurality of bodies defining an area therebetween lying within said region, said plurality of bodies being adapted to vary said area.
7. The apparatus as recited in claim 1 wherein a subset of said plurality of lever sub-assemblies further includes a lever arm having first and second opposed termini; a linkage, coupled between said body and said lever arm, to translate angular motion of said lever arm about an axis into motion of said body along a direction extending transversely to said axis, with said direction being substantially constant over a range of motion of said body about said axis; and an actuation system to impart said angular motion.
8. The apparatus as recited in claim 7 wherein said body further includes a contact surface and said linkage further includes a linkage system coupled between said lever arm and said body to allow said contact surface to compress against a side of said substrate.
9. The apparatus as recited in claim 7 wherein said linkage further includes a linkage system coupled between said lever arm and said body to facilitate angular movement of said lever arm with respect to said body about two additional axes, one of which extends orthogonally to the remaining axis of said two axes.
10. The apparatus as recited in claim 7 wherein said body further includes a contact surface formed from a compliant material to contact a side of said substrate and conform to a shape of said side.
11. The apparatus as recited in claim 7 further including an amplifier coupled to said body, with said actuation system imparting a first force upon an additional contact surface of said opposing body, with said amplifier imparting a second force upon said contact surface in response to said first force with a magnitude of said second force being greater than a magnitude of said first force.
12. The apparatus as recited in claim 7 further including an amplifier coupled to said body, with said actuation system imparting a first force upon an additional contact surface of said opposing body, with said amplifier imparting a second force upon said contact surface, with a magnitude of said second force being a multiple of a magnitude of said first force.
13. The apparatus as recited in claim 7 further including an amplifier coupled to said opposing body, with said actuation system imparting a first force upon an additional contact surface of said opposing body, with said amplifier imparting a second force upon said contact surface in response to said first force, with said amplifier including a pivot disposed from said first end a first length and disposed from said second end a second length with said magnitude of said second force being a function of a ratio of said first length and said second length.
14. The apparatus as recited in claim 7 wherein said actuation system comprises an actuator selected from a set of actuators consisting essentially of a pneumatic acutator, a piezo-electric actuator, a magnetostrictive actuator and a voice coil actuator.
15. An apparatus to vary dimensions of a substrate, said apparatus comprising:
a substrate chuck adapted to position said substrate in a region;
a plurality of pliant members;
a flexure, with said substrate chuck being fixedly attached to said flexure; and
an actuator sub-assembly elastically coupled to flexure through said plurality of pliant members, with said actuator assembly including a plurality of lever sub-assemblies a subset of which includes a body lying in said region and spaced-apart from an opposing body associated with one of the remaining lever sub-assemblies of said plurality of lever sub-assemblies, with each of the lever sub-assemblies of said subset being adapted to vary a distance between said body and opposing body.
16. The apparatus as recited in claim 15 wherein said body and said opposing body are positioned to receive said substrate therebetween and apply compressive forces thereto, with said pliant member configured to attenuate a magnitude of resulting forces sensed by said substrate chuck generated in response to said compressive forces.
17. The apparatus as recited in claim 15 wherein a first end of a subset of said plurality of pliant members are fixedly attached to said actuator assembly and a second end of the pliant members of said subset are fixedly attached to said flexure.
18. The apparatus as recited in claim 15 wherein said plurality of pliant members are configured to facilitate translational movement between said flexure and said actuator sub-assembly along two orthogonal axes lying in a common plane, while restricting translation movement along an additional axis extending normal to said plane.
19. The apparatus as recited in claim 15 wherein said actuator assembly includes additional bodies, with said additional bodies and said body and said opposing body defining a plurality of bodies, with said plurality of bodies defining an area therebetween lying within said region, said plurality of bodies being adapted to vary said area.
20. The apparatus as recited in claim 15 wherein a subset of said plurality of lever sub-assemblies further includes a lever arm having first and second opposed termini; a linkage, coupled between said body and said lever arm, to translate angular motion of said lever arm about an axis into motion of said body along a direction extending transversely to said axis, with said direction being substantially constant over a range of motion of said body about said axis; and an actuation system to impart said angular motion.
21. The apparatus as recited in claim 20 wherein said body further includes a contact surface and said linkage further includes a linkage system coupled between said lever arm and said body to allow said contact surface to compress against a side of said substrate.
22. The apparatus as recited in claim 20 wherein said linkage further includes a linkage system coupled between said lever arm and said body to facilitate angular movement of said lever arm with respect to said body about two additional axes, one of which extends orthogonally to the remaining axis of said two axes.
23. The apparatus as recited in claim 20 wherein said body further includes a contact surface formed from a compliant material to contact a side of said substrate and conform to a shape of said side.
24. The apparatus as recited in claim 20 wherein said actuation system comprises an actuator selected from a set of actuators consisting essentially of a pneumatic acutator, a piezo-electric actuator, a magnetostrictive actuator and a voice coil actuator.
25. An apparatus to vary dimensions of a substrate, said apparatus comprising:
a first body having a first end;
a second body having a contact surface spaced-apart from said first end a distance;
a lever arm having first and second opposed termini;
a linkage, coupled between said second body and said lever arm, to translate angular motion of said lever arm about an axis into movement of said second body in a direction to vary said distance, while allowing angular movement between said second body and said lever arm; and
an actuation system to impart said angular movement.
26. The apparatus as recited in claim 25 wherein said linkage further includes a linkage system coupled between said lever arm and said second body to facilitate angular movement of said lever arm with respect to said second body about an additional axis extending parallel to said axis.
27. The apparatus as recited in claim 25 wherein said linkage further includes a linkage system coupled between said lever arm and said second body to facilitate angular movement of said lever arm with respect to said second body about an additional axis extending orthogonally to said axis.
28. The apparatus as recited in claim 25 wherein said linkage further includes a linkage system coupled between said lever arm and said second body to facilitate angular movement of said lever arm with respect to said second body about two additional axes one of which extends orthogonally to said axis, with the remaining axis of said two additional axes extending parallel to said axis.
29. The apparatus as recited in claim 25 wherein said contact surface is formed from a compliant material.
30. The apparatus as recited in claim 25 further including an amplifier coupled to said second body, with said actuation system imparting a first force upon an additional contact surface of said second body, with said amplifier imparting a second force upon said contact surface in response to said first force with a magnitude of said second force being greater than a magnitude of said first force.
31. The apparatus as recited in claim 25 further including an amplifier coupled to said second body, with said actuation system imparting a first force upon an additional contact surface of said second body, with said amplifier imparting a second force upon said first terminus, with a magnitude of said second force being a multiple of a magnitude of said first force.
32. The apparatus as recited in claim 25 further including an amplifier coupled to said second body, with said actuation system imparting a first force upon an additional contact surface of said second body, with said amplifier imparting a second force upon said first terminus in response to said first force, with said amplifier including a pivot disposed from said first end a first length and disposed from said second end a second length with said magnitude of said second force being a function of a ratio of said first length and said second length
33. The apparatus as recited in claim 25 wherein said actuation system comprises a piezo-electric actuator.
34. An apparatus to vary dimensions of a substrate, said apparatus comprising:
a plurality of bodies disposed about a perimeter defining an area, with a subset of said plurality of bodies being coupled to a lever arm through a linkage to translate angular motion of said lever arm about an axis to vary said area by imparting motion onto one of said plurality of bodies along a direction extending transversely to said axis, with said direction being substantially constant over a range of motion of said lever arm about said axis; and
an actuation system to impart said angular movement.
35. The apparatus as recited in claim 34 wherein said linkage further includes a linkage system coupled between one of said plurality of bodies and said lever arm to facilitate angular movement of said body with respect to said lever arm about an additional axis extending parallel to said axis.
36. The apparatus as recited in claim 34 wherein said linkage further includes a linkage system coupled between one of said plurality of bodies and said lever arm to facilitate angular movement of said body with respect to said lever arm about an additional axis extending orthogonally to said axis.
37. The apparatus as recited in claim 34 wherein said linkage further includes a linkage system coupled between one of said plurality of bodies and said lever arm to facilitate angular movement of said body with respect to said lever arm about two additional axes one of which extends orthogonally to said axis, with the remaining axis of said two additional axes extending parallel to said axis.
38. The apparatus as recited in claim 34 wherein one end of said body is formed from a compliant material.
39. The apparatus as recited in claim 34 further including an amplifier coupled to said lever arm, with said actuation system imparting a first force upon a said lever arm, with said amplifier imparting a second force upon said one of the bodies of said subset in response to said first force, with a magnitude of said second force being greater than a magnitude of said first force.
40. The apparatus as recited in claim 34 further including an amplifier coupled to said second body, with said actuation system imparting a first force upon said lever arm, with said amplifier imparting a second force upon said body, with a magnitude of said second force being a multiple of a magnitude of said first force.
41. The apparatus as recited in claim 34 further including an amplifier coupled to said second body, with said actuation system imparting a first force upon said lever arm, with said amplifier imparting a second force upon said body in response to said first force, with said amplifier including a pivot positioned between opposed ends of said lever arm, with said pivot being positioned, with respect to one of said opposed ends, a first length and positioned from the remaining of said opposed ends, a second length with a magnitude of said second force being a function of a ratio of said first length and said second length
42. The apparatus as recited in claim 34 wherein said actuation system comprises of a piezo-electric actuator.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS

The present application claims priority to U.S. provisional patent application No. 60/576,879 filed on Jun. 3, 2004, entitled “System and Method for Magnification and Distortion Correction during Nano-Scale Manufacturing,” which is incorporated by reference herein.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

The government of these United States has a paid-up license in this invention and the right in limited circumstance to require the patent owner to license other on reasonable terms as provided by the terms of N66001-01-1-8964 and N66001-02-C-8011 awarded by the Defense Advanced Research Projects Agency (DARPA).

BACKGROUND OF THE INVENTION

The field of invention relates generally to imprint lithography. More particularly, the present invention is directed to reducing pattern distortions during imprint lithography processes.

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.

An exemplary micro-fabrication technique is commonly referred to as imprint lithography and is described in detail in numerous publications, such as U.S. published patent applications 2004/0065976, entitled METHOD AND A MOLD TO ARRANGE FEATURES ON A SUBSTRATE TO REPLICATE FEATURES HAVING MINIMAL DIMENSIONAL VARIABILITY; 2004/0065252, entitled METHOD OF FORMING A LAYER ON A SUBSTRATE TO FACILITATE FABRICATION OF METROLOGY STANDARDS; and 2004/0046271, entitled METHOD AND A MOLD TO ARRANGE FEATURES ON A SUBSTRATE TO REPLICATE FEATURES HAVING MINIMAL DIMENSIONAL VARIABILITY, all of which are assigned to the assignee of the present invention. The fundamental imprint lithography technique as shown in each of the aforementioned published patent applications includes formation of a relief pattern in a polymerizable layer and transferring a pattern corresponding to the relief pattern into an underlying substrate. To that end, a template is employed spaced-apart from the substrate with a formable liquid present between the template and the substrate. The liquid is solidified to form a solidified layer that has a pattern recorded therein that is conforming to a shape of the surface of the template in contact with the liquid. The substrate and the solidified layer are then subjected to processes to transfer, into the substrate, a relief image that corresponds to the pattern in the solidified layer.

One manner in which to locate the polymerizable liquid between the template and the substrate is by depositing a plurality of droplets of the liquid on the substrate. Thereafter, the polymerizable liquid is concurrently contacted by both the template and the substrate to spread the polymerizable liquid over the surface of the substrate. It is desirable to properly align the template with the substrate so that the proper orientation between the substrate and template may be obtained. To that end, both the template and substrate include alignment marks. A concern with these processes involves distortions in the pattern resulting from, inter alia, extenuative variations in the imprinting layer and/or the substrate, as well as misalignment of the template with respect to the substrate.

It is desired, therefore, to provide a system to reduce distortions in patterns due to magnification and alignment variations patterns formed using imprint lithographic techniques.

SUMMARY OF THE INVENTION

The present invention is directed toward a system to vary dimensions of a substrate, such as a template having a patterned mold. To that end, the system includes a substrate chuck adapted to position the substrate in a region; a pliant member; and an actuator sub-assembly elastically coupled to the substrate chuck through the pliant member. The actuator assembly includes a plurality of lever sub-assemblies, one of which includes a body lying in the region and spaced-apart from an opposing body associated with one of the remaining lever sub-assemblies of the plurality of lever sub-assemblies. One of the plurality of lever assemblies is adapted to vary a distance between the body and the opposing body. In this manner, compressive forces may be applied to the template to remove unwanted magnification or other distortions in the pattern on the mold. The pliant member is configured to attenuate a magnitude of resulting forces sensed by the substrate chuck generated in response to the compressive forces. These and other embodiments are discussed more fully below.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a lithographic system in accordance with the present invention;

FIG. 2 is a simplified elevation view of a lithographic system shown in FIG. 1;

FIG. 3 is a simplified elevation view of a mold spaced-apart from the imprinting layer, shown in FIG. 1, after patterning of the imprinting layer;

FIG. 4 is a simplified elevation view of an additional imprinting layer positioned atop of the substrate shown in FIG. 3 after the pattern in the first imprinting layer is transferred therein;

FIG. 5 is an exploded view of an imprint head, actuator sub-assembly and template in accordance with the present invention;

FIG. 6 is a cross-sectional view of a chucking system in accordance with the present invention;

FIG. 7 is a bottom-up plan view of a chuck body shown in FIG. 6;

FIG. 8 is a bottom-up perspective view of an apparatus shown in FIG. 5 used to vary dimensions of a template;

FIG. 9 is top-down perspective view of the apparatus shown in 8;

FIG. 10 is detailed side view of a lever sub-assembly shown in FIGS. 8 and 9 in accordance with the present invention;

FIG. 11 is an exploded perspective view of the actuator sub-assembly, flexure device, shown in FIG. 5, with pivots in accordance with the present invention;

FIG. 12 is a detailed perspective view of one of the pivots shown in FIG. 11;

FIG. 13 is a top down view of a wafer, shown in FIGS. 2, 3 and 4 upon which imprinting layers are disposed;

FIG. 14 is a detailed view of FIG. 13 showing the position of the mold in one of the imprint regions;

FIG. 15 is a bottom-up plan view of the chuck body shown in FIG. 7 in accordance with an alternate embodiment;

FIG. 16 is a cross-sectional view of a chuck body shown in FIG. 8 in accordance with a second alternate embodiment;

FIG. 17 is a flow diagram showing a method of reducing distortions in patterns formed using imprint lithography techniques in accordance with the present invention; and

FIG. 18 is a flow diagram showing a method of reducing distortions in patterns formed using imprint lithography techniques in accordance with an alternate embodiment of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

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. 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, but may move along the Z-axis as well. 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 system 10 to impinge actinic radiation upon motion stage 20. Operation of system 10 is under control of a processor 31 in data communication with a memory 33 containing computer readable code that defines instructions to regulate the operation of the various components of system 10.

Referring to both FIGS. 1 and 2, connected to imprint head 18 is a template 26 having a mold 28 thereon. Mold 28 includes a plurality of features defined by a plurality of spaced-apart recessions 28 a and protrusions 28 b. The plurality of features defines an original pattern that forms the basis of a pattern to be transferred into a wafer 30 positioned on motion stage 20. To that end, imprint head 18 is adapted to move along the Z axis and vary a distance “d” between mold 28 and wafer 30, but may move along the X and Y axes as well. In this manner, the features on mold 28 may be imprinted into a flowable region of wafer 30, discussed more fully below. Radiation source 22 is located so that mold 28 is positioned between radiation source 22 and wafer 30. As a result, mold 28 is fabricated from material that allows it to be substantially transparent to the radiation produced by radiation source 22.

Referring to FIG. 2, a flowable region, such as an imprinting layer 34, is formed on a portion of surface 32 that presents a substantially planar profile. The flowable region may be formed using any known technique such as a hot embossing process disclosed in U.S. Pat. No. 5,772,905, which is incorporated by reference in its entirety herein, or a laser assisted direct imprinting (LADI) process of the type described by Chou et al. in Ultrafast and Direct Imprint of Nanostructures in Silicon, Nature, Col. 417, pp. 835-837, June 2002. In the present embodiment, however, flowable region consists of imprinting layer 34 being deposited as a plurality of spaced-apart discrete droplets 36 of the imprinting material on wafer 30, discussed more fully below. An exemplary system for depositing droplets 36 is disclosed in U.S. patent application Ser. No. 10/191,749, filed Jul. 9, 2002, entitled “System and Method for Dispensing Liquids”, and which is assigned to the assignee of the present invention and incorporated by reference herein. Imprinting layer 34 is formed from the imprinting material that may be selectively polymerized and cross-linked to record the original pattern therein, defining a recorded pattern. An exemplary composition for the imprinting material 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.

Referring to FIGS. 2 and 3, the pattern recorded in imprinting layer 34 is produced, in part, by interaction with mold 28, e.g., mechanical contact, electrical contact and the like. In the present example, the distance “d” is reduced to allow imprinting layer 34 to come into mechanical contact with mold 28, to spread droplets 36 and form imprinting layer 34 with a contiguous formation of the imprinting material over surface 32. In one embodiment, distance “d” is reduced to allow sub-portions 34 a of imprinting layer 34 to ingress into and fill recessions 28 a.

To facilitate filling of recessions 28 a, the imprinting material is provided with the requisite properties to completely fill recessions 28 a while covering surface 32 with a contiguous formation of the imprinting material. In the present embodiment, sub-portions 34 b of imprinting layer 34 in superimposition with protrusions 28 b remain after the desired, usually minimum distance “d”, has been reached, leaving sub-portions 34 a with a thickness t1, and sub-portions 34 b with a thickness, t2. Thicknesses “t1” and “t2” may be any thickness desired, dependent upon the application.

Referring to FIGS. 2 and 3, after a desired distance “d” has been reached, radiation source 22 produces actinic radiation that polymerizes and cross-links the imprinting material, forming cross-linked polymer material. As a result, the composition of imprinting layer 34 transforms from the imprinting material to solidified material. Specifically, the imprinting material is solidified to providing solidified imprinting layer 134 having a side with a shape conforming to a shape of a surface 28 c of mold 28, shown more clearly in FIG. 3. After formation of solidified imprinting layer 134 distance “d” is increased so that mold 28 and solidified imprinting layer 134 are spaced-apart.

Referring to FIG. 3, additional processing may be employed to complete the patterning of wafer 30. For example, wafer 30 and solidified imprinting layer 134 may be etched to transfer a pattern of solidified imprinting layer 134 into wafer 30, providing a patterned surface 32 a, shown in FIG. 4. Referring again to FIG. 3, to facilitate etching, the material from which solidified imprinting layer 134 is formed may be varied to define a relative etch rate with respect to wafer 30, as desired. Alternatively, or in addition to, solidified imprinting layer 134 may be provided with an etch differential with respect to photo-resist material (not shown) selectively disposed thereon. The photo-resist material (not shown) may be provided to further pattern solidified imprinting layer 134, using known techniques. Any etch process may be employed, dependent upon the etch rate desired and the underlying constituents that form wafer 30 and solidified imprinting layer 134. Exemplary etch processes may include plasma etching, reactive ion etching, chemical wet etching and the like.

Referring to both FIGS. 1 and 2 an exemplary radiation source 22 may produce ultraviolet radiation. Other radiation sources may be employed, such as thermal, electromagnetic and the like. The selection of radiation employed to initiate the polymerization of the imprinting material is known to one skilled in the art and typically depends on the specific application which is desired. Furthermore, the plurality of features on mold 28 are shown as recessions 28 a extending along a direction parallel to protrusions 28 b that provide a cross-section of mold 28 with a shape of a battlement. However, recessions 28 a and protrusions 28 b may correspond to virtually any feature desired, including features to create an integrated circuit and may be as small as a few nanometers. As a result, it may be desired to manufacture components of system 10 from materials that are thermally stable, e.g., have a thermal expansion coefficient of less than about 10 ppm/degree Centigrade at about room temperature (e.g. 25 degrees Centigrade). In some embodiments, the material of construction may have a thermal expansion coefficient of less than about 10 ppm/degree Centigrade, or less than 1 ppm/degree Centigrade. To that end, bridge supports 12, bridge 14, and/or stage support 16 may be fabricated from one or more of the following materials: iron alloys available under the trade name INVAR®, or name SUPER INVAR™, ceramics, including but not limited to ZERODUR® ceramic and silicon carbide. Additionally table 24 may be constructed to isolate the remaining components of system 10 from vibrations in the surrounding environment. An exemplary table 24 is available from Newport Corporation of Irvine, Calif.

Referring to FIGS. 5 and 6, template 26, upon which mold 28 is present, is coupled to imprint head housing 18, shown in FIG. 1, via a chucking system 40 that includes chuck body 42. Body 42 is coupled to a flexure 41 that is disclosed and claimed in U.S. patent application Ser. No. 10/858,179, filed Jun. 1, 2004, entitled “A Compliant Device for Nano-Scale Manufacturing”, which is assigned to the assignee of the present invention and is incorporated herein by reference. Flexure 41 is coupled to a system 43 that controls movement of template 26, which is disclosed in U.S. patent application Ser. No. 10/858,100, filed Jun. 1, 2004, entitled “Method and System to Control Movement of a Body for Nano-Scale Manufacturing,” which is assigned to the assignee of the present invention and is incorporated by reference herein.

Referring to FIGS. 6 and 7 chuck body 42 is adapted to retain template 26, upon which mold 28 is attached, employing vacuum techniques. To that end, chuck body 42 includes first 46 and second 48 opposed sides. A side, or edge, surface 50 extends between first side 46 and second side 48. First side 46 includes a first recess 52 and a second recess 54, spaced-apart from first recess 52, defining first 58 and second 60 spaced-apart support regions. First support region 58 cinctures second support region 60 and the first 52 and second 54 recesses. Second support region 60 cinctures second recess 54. A portion 62 of chuck body 42 in superimposition with second recess 54 is transparent to radiation having a predetermined wavelength, such as the wavelength of the actinic radiation mentioned above. To that end, portion 62 is made from a thin layer of transparent material, such as glass. However, the material from which portion 62 is made may depend upon the wavelength of radiation produced by radiation source 22, shown in FIG. 2. Portion 62 extends from second side 48 and terminates proximate to second recess 54 and should define an area at least as large as an area of mold 28 so that mold 28 is in superimposition therewith. Formed in chuck body 42 are one or more throughways, shown as 64 and 66. One of the throughways, such as throughway 64 places first recess 52 in fluid communication with side surface 50. The remaining throughway, such as throughway 66, places second recess 54 in fluid communication with side surface 50.

It should be understood that throughway 64 may extend between second side 48 and first recess 52, as well. Similarly, throughway 66 may extend between second side 48 and second recess 54. What is desired is that throughways 64 and 66 facilitate placing recesses 52 and 54, respectively, in fluid communication with a pressure control system, such a pump system 70.

Pump system 70 may include one or more pumps to control the pressure proximate to recesses 52 and 54, independently of one another. Specifically, when mounted to chuck body 42, template 26 rests against first 58 and second 60 support regions, covering first 52 and second 54 recesses. First recess 52 and a portion 44 a of template 26 in superimposition therewith define a first chamber 52 a. Second recess 54 and a portion 44 b of template 26 in superimposition therewith define a second chamber 54 a. Pump system 70 operates to control a pressure in first 52 a and second 54 a chambers. Specifically, the pressure is established in first chamber 52 a to maintain the position of the template 26 with the chuck body 42 and reduce, if not avoid, separation of template 26 from chuck body 42 under force of gravity. The pressure in the second chamber 54 a may differ from the pressure in the first chamber 52 a to, inter alia, reduce distortions in the template 26 that occur during imprinting, by modulating a shape of template 26. For example, pump system 70 may apply a positive pressure in chamber 54 a to compensate for any upward force R that occurs as a result on imprinting layer 34, shown in FIG. 2, contacting mold 28. In this manner, produced is a pressure differential between differing regions of side 46 so that bowing of template 26 and, therefore, mold 28 under force R is attenuated, if not avoided. Coupled to template 26 is a means for varying dimensions of the same in X and Y directions, with the understanding that the Y-direction is into the plane of FIG. 6. The means for varying dimensions is shown schematically as an actuator sub-assembly 72, which is coupled to chuck body 42, shown in exploded view in FIG. 5. Pump system 70 and actuator sub-assembly 72 are operated under control of processor 31, shown in FIG. 1.

Referring to FIGS. 8-10, in the present example actuator sub-assembly 72 is configured to subject template 26 to purely compressive forces so that out-of-plane bending forces are substantially minimized, if not avoided entirely. Forces causing bending of template 26 are problematic in that the same results in pattern distortion. To that end, actuator sub-assembly 72 includes a plurality of lever sub-assemblies mounted to a frame 76 having a central aperture 77 to direct compressive forces along a neutral axis of template 26. Each of lever sub-assemblies 74 includes a body 78 coupled to a lever arm 80 and an actuation system 82. Lever arm 80 is coupled to body 78 through a linkage 84 system. Typically, lever arm 80, body 78 and linkage system 84 are integrally formed from a solid material, e.g., aluminum, stainless steel and the like. A piston 88 of actuation system 82 is coupled to a terminus region 86 of lever arm 80 through a flex joint 90 and may push or pull against terminus region 86. A second terminus region 87 of lever arm 80 is coupled to linkage system 87 to impart a force thereon.

Each of lever sub-assemblies 74 is mounted to frame 76 so that linkage system 84 is positioned on a first side 92 of frame 76. Actuation system 82 is positioned on a second side 94 of frame 76, disposed opposite to first side 92, with lever arm 80 extending therebetween. Each body 78 of lever sub-assemblies 74 extends from linkage system 84 away from lever arm 80 toward aperture 77 and terminates in superimposition therewith. Although it is not necessary, it is desirable to have the plurality of lever sub-assemblies 74 coupled to frame 76 so that the plurality of bodies 78 associated therewith are symmetrically disposed with respect to aperture 77. Furthermore, it may be desirable to have the plurality of lever sub-assemblies 74 coupled to frame 76 such that the same may impart the aforementioned force on a common frame, i.e. frame 76. Alternatively, sub-assemblies may be coupled to differing frames, but it is desirable that opposed sub-assemblies be coupled to a common frame. Although aperture 77 may have any shape desired, typically aperture 77 has a shape complementary to the shape of the template 26. To that end, and as shown, aperture 77 is square. Further it is desired that each of the plurality of bodies 78 be disposed opposite one of the remaining bodies 78 of the plurality of bodies 78. To that end, there are an equal number of bodies 78 on opposing sides of aperture 77. Although four lever sub-assemblies 74 are shown, providing four bodies 78 to a side of aperture 77, any number may be present. More specifically, each lever sub-assembly 74 may be made smaller such that a greater number of lever sub-assemblies 74 may be employed to provide a finer precision of the distortion control of template 26. In this manner, an area is defined between the plurality of bodies 78 in which template 26 may be centered. An advantage with the present design is that the entire actuator sub-assembly 72 is positioned to lie on one side of mold 28 so as to be spaced-apart from a plane in which mold surface 28 c, shown in FIG. 3, lies. This is beneficial in preventing contact between the components of actuator sub-assembly 72, shown in FIG. 5, and a wafer 30, shown in FIG. 3, during imprint processes.

Referring to FIGS. 8-10, during operation, actuator sub-assembly 72 applies a force to terminus region 86 to provide aperture 77 with appropriate dimensions to receive template 26. For example, in a neutral state, i.e., without the force being applied by actuator sub-assembly 72, aperture 77 may have dimensions that are smaller than the dimensions of template 26. As a result, actuator sub-assembly 72 may operate to pull against terminus region 86 and cause retraction of body 78 away from an opposing body 78 to increase the size of aperture 77 for loading of template 26. Template 26 is disposed within aperture 77 and held in place via chucking system 40, shown in FIG. 6.

Referring again to FIGS. 8-10, bodies 78 are arranged so that a contact surface 98 is included in body 78 to contact a side 96 of template 26. Specifically, a contact surface 98 is configured to extend parallel to side 96 and make contact therewith. To that end, actuation system 82 is coupled to pump system 70, shown in FIG. 6, to cause actuation system 82 to impart angular movement of lever arm 80. Specifically, piston 88 imparts a force FIN upon one end of lever arm 80 through flexure joint 90. This causes lever arm 80 to undergo rotational movement that causes body 78 to undergo translational movement toward template 26, thereby decreasing the area defined by the plurality of bodies 78. In this manner, a force FOUT is imparted upon side 96 of template 26. By appropriately imparting FOUT from one or more bodies 78 along differing portions of side 96 of template 26, dimensional variations of template 26 may be achieved. The dimensional variations of template 26 are imparted upon mold 28, which may be employed to compensate for magnification errors, discussed more fully below.

An important consideration when varying the dimensions of template 26 is to minimize, if not avoid, localized force concentrations upon template 26 and bending of template 26, both of which will result in distortions in the pattern of mold 28. To that end, linkage 84 is designed to control the direction of travel of body 78 and lever arm 80. Additionally the structural connect of sub-assemblies 74 to common frame 76 ensures that high forces are reacted in frame 76, which as opposed to other components such as template chuck body 42 and, therefore, template 26.

Linkage 84 includes a linkage member 99 and a plurality of flexure joints, shown as 100, 102, 104, 106, 108 and 110. Each of flexure joints 100, 102, 104, 106, 108 and 110 are regions of material of linkage member 99 has substantially reduced material. Flexure joint 100 defines a pivot axis 112 about which lever arm 80 undergoes rotational/angular movement in response to force FIN imparted upon lever arm 80 by piston 88 of actuation system 82 at terminus region 86. The rotational/angular movement of lever arm 80 about pivot axis 112 causes body 78 to move in a direction 114 that is transverse, if not orthogonal, to pivot axis 112. It is highly desired that direction 114 is precisely controlled so that deviation therefrom is minimized. This reduces, if not avoids, out-of-plane bending of template 26 upon being subjected to force FOUT by the plurality of bodies 78. Force FOUT is directed along terminus region 87 of lever arm 80 onto linkage system 84.

Flexure joints 102, 104, and 106 in addition to flexure joint 100 facilitate rotational/angular movement between lever arm 80 and body 78 while ensuring that deviation of body 78 from direction 114 is minimized. Specifically, each of flexure joints 102, 104, and 106 defines an axis of rotation, 116, 118, and 120, respectively, about which rotational/angular movement between lever arm 80 and body 78 may occur. Axes 112, 116, 118, and 120 extend parallel, with axes 112 and 116 being substantially in superimposition with one another and axes 118 and 120 being substantially in superimposition with one another. Axes 112 and 118 lie in a common plane and axes 116 and 120 lie in a common plane.

Additionally by properly positioning axis 112 between terminus regions 86 and 87, lever arm 80 and linkage 84 may function as an amplifier. Specifically, when contact between side 96 and contact surface 98 exists, the force FOUT applied to linkage system 84 is a function of force FIN and the position of axis 112 between terminus regions 86 and 87. The magnitude of FOUT may be defined as follows:
F OUT =F IN(l 1 /l 2)
where l1 is a distance axis 112 from terminus region 86, and l2 is a distance of axis 112 from terminus region 87.

Referring to FIGS. 10 and 12, in furtherance of maintaining pure compression on template 26, linkage system 84 includes joints 108 and 110. Joints 108 and 110 facilitate rotational/angular movement of body 78 with respect to lever member 99 along two transversely extending axes 124 and 126. By providing body 78 with rotational freedom about axes 124 and 126, body 78 may change position to compensate for obliqueness of side 96 with respect to contact surface 98. In this manner, contact surface 98 will maintain contact with side 96, so as to reduce, if not prevent, localized stresses resulting from, inter alia, having a corner of contact surface 98 contacting side 96. To further reduce localized stresses between contact surface 98 and template 26, contact surface 98 may be formed from a compliant material, so that localized stresses on side 96 resulting from non-conformity of contact surface 98 with side 96 is minimized. Further compliance with surface anomalies of side 96 may be achieved by allowing independent control over body 78 and, therefore, contact surface 98.

Actuator sub-assembly 72 facilitates varying the dimension of template 26 in two dimensions. This is particularly useful in overcoming Poisson's effect. Poisson's effect may result in linear coupling of strain in orthogonal directions of template 26. Specifically, the Poisson ratio is the ratio between the tensile strain caused in the Y and Z directions in template 26 to the compressive strain imparted to template 26 in the X direction. Typical numbers are in the range of 0.1-0.4. Were template 26 formed from fused silica, the ratio is approximately 0.16. A dimensional change that is purely in the X direction, therefore, i.e., with no dimensional change in the Y direction being desired, may necessitate activation of actuator sub-assembly 72 to vary both distances D1 and D2, to compensate for Poisson's effect. With any of the above-described configurations of actuator sub-assembly 72, a force may be applied to template 26 to vary the dimensions of the same and reduce distortions in the pattern recorded into imprinting layer 34, shown in FIG. 2.

Referring to FIGS. 1, 5, 9, 11 and 12 another important consideration when varying template dimensions is to minimize the deleterious effects of the forces employed. For example, when varying template dimensions, forces on the order of hundreds of pounds may be exerted. It is desirable to minimize the amount of these forces felt on other units of system 10, such as system 43. In addition, it is desirable that template 26 neither rotate with respect to chuck body 42 about the Z-axis nor move along the X and Y directions with respect to body 42, such as in the presence of unequal compression forces exerted upon side 96 by bodies 78. To that end, actuator sub-assembly 72 is pivotally/elastically coupled to flexure 41 to move in a plane along X and Y directions in a plane and rotate about the Z direction. This is accomplished by coupling each corner, 72 a, 72 b, 72 c and 72 d, of actuator sub-assembly 72 to a corner, 41 a, 41 b, 41 c and 41 d, of flexure 41 through a pliant member 75.

As shown, each pliant member 75 includes opposed termini 79 and 81 with a dual fulcrum lever system 83 extending from terminus 79, toward terminus 81, terminating in a fulcrum 85. Fulcrum 85 is located between opposed termini 79 and 81. Fulcrum lever system 83 includes a lever 187, extending from fulcrum 85, along direction Z toward terminus 79, terminating in a base 89. Base 89 is coupled to lever 187 defining a fulcrum 91 thereat. Base 89 extends from fulcrum 91, transversely to direction Z. Extending from fulcrum 85 is a support 93 that terminates in a base 95. Support 93 extends from fulcrum 85 toward terminus 79 and is disposed opposite to and spaced apart from lever 187. Base 95 extends from support 93 away from lever and is positioned in superimposition with, and spaced apart from, base 89.

Base 89 is fixedly attached to actuator sub-assembly 72, and base 95 is fixedly attached to flexure 41. With this configuration, relative movement between actuator sub-assembly 72 and flexure 41 is facilitated. Having one pliant member 75 coupling together each pair of corners, i.e., one of the corners of flexure 41 with one of the corners of actuator sub-assembly 72, allows each lever 187 to function as a parallel four-bar linkage in space. This provides the actuator sub-assembly 72 with relative translational movement, with respect to flexure 41, along the X and Y directions, as well as rotational about the Z direction. Specifically, fulcrum 85 facilitates relative movement about axis 97, and fulcrum 91 facilitates relative movement about axis 199. In addition, relative rotational movement about axis Z is facilitated by lever 187. The rigidity of lever 187 minimizes, of not prevents, translational movement along the Z direction. Providing the aforementioned relative movement between actuator sub-assembly 72 and flexure 41 minimizes the amount of magnification forces that is sensed by others features of the system 10, e.g., flexure 41 and system 42 among others.

Additionally, actuators sub-assembly 72 is allowed to accommodate loading tolerances and unequal forces between the template and actuator sub-assembly 72. For example, were template 26 loaded on body 42 with theta error, e.g., not properly aligned, rotationally about the Z direction, with respect to chuck body 42 then the actuator sub-assembly 72 may rotate about the Z direction to accommodate for the misalignment. In addition, were the sum of the forces applied to template 26 by opposing bodies 78 not cancel, the actuator sub-assembly 72 accommodates for non-equilibrium of the forces applied by moving in the X and/or Y directions and/or rotates about the Z direction.

For example, it is desired that each of the plurality of levers systems 74 operate independently of the remaining lever sub-assemblies 74 so that the sum of the magnification forces applied to template 26 in each direction is zero. To that end the following is satisfied:
F xi +F x(i+1) + . . . F x(i+n)=0   (1)
F yi +F y(i+1) + . . . + F y(i+n)=0   (2)
Σ(M zi)=0   (3)
where i is an integer number, Fx is a force in the X direction, Fy is a force in the Y direction and Mz is the moment of the forces Fx and Fy about the Z-axis. A large number of combinations of forces can be applied on the template obeying the above constraints. These combinations can be used to correct for magnification and distortion errors.

In a further embodiment, to provide better distortion control over template 26, the area of template 26 may be increased such that a greater number of lever sub-assemblies 74 may be employed to apply compressive forces to template 26. The larger number of lever sub-assembly 74 allow a finer precision of the distortion control of template 26. To that end, a subset of, or each of lever sub-assemblies 74 may be constructed to have bodies 78 of smaller dimensions to increase the number thereof coupled to side 96. In this manner, improved distortion correction may be achieved due to the increased resolution of correction afforded by increasing a number of bodies 78 on side 96. Alternatively, the area of side 96 may be increased, requiring appropriate scaling of actuator sub-assembly 72 to accommodate a template of increased size 26. Another advantage of increasing the size of template 26 is that the area of template 26 outside of mold 28 filters, e.g., attenuates, deleterious effects of stress concentrations of bodies 78 on side 96. The stress concentration creates strain variations at mold 28, which results in pattern distortions in the pattern on mold 28. In short it may be realized that the number of bodies 78 per unit area of edge is proportional to the resolution of distortion correction. Furthermore, decreasing the area of mold 28 with respect to the remaining regions of template 26 reduces the pattern distortions caused by bodies 78 contacting side 96.

Referring to FIGS. 1 and 2, distortions in the pattern recorded into imprinting layer 34 may arise from, inter alia, dimensional variations of imprinting layer 34 and wafer 30. These dimensional variations, which may be due in part to thermal fluctuations, as well as, inaccuracies in previous processing steps that produce what is commonly referred to as magnification/run-out errors. The magnification/run-out errors occur when a region of wafer 30 in which the original pattern is to be recorded exceeds the area of the original pattern. Additionally, magnification/run-out errors may occur when the region of wafer 30, in which the original pattern is to be recorded, has an area smaller than the original pattern. The deleterious effects of magnification/run-out errors are exacerbated when forming multiple layers of imprinted patterns, shown as imprinting layer 124 in superimposition with patterned surface 32 a, shown in FIG. 4. Proper alignment between two superimposed patterns is difficult in the face of magnification/run-out errors in both single-step full wafer imprinting and step-and-repeat imprinting processes. To achieve proper alignment an interferometric analysis may be undertaken to generate control signals operated on by processor 31, shown in FIG. 1, as disclosed in U.S. co-pending patent application No. (unassigned) filed (herewith), entitled INTERFEROMETRIC ANALYSIS FOR THE MANUFACTURE OF NANO-SCALE DEVICES, having Pawan K. Nimmakayala, Tom H. Rafferty, Alireza Aghili, Byung-Jin Choi, Philip D. Schumaker, Daniel A. Babbs, and Sidlgata V. Sreenivasan listed as inventors and having attorney docket number P180-56-04, which in incorporated by reference herein.

Referring to FIGS. 13 and 14, a step-and-repeat process includes defining a plurality of regions, shown as, a-l, on wafer 30 in which the original pattern on mold 28 will be recorded. The original pattern on mold 28 may be coextensive with the entire surface of mold 28, or simply located on a sub-portion thereof. The present invention will be discussed with respect to the original pattern being coextensive with the surface of mold 28 that faces wafer 30. Step-and-repeat imprint lithography processes may be achieved in a variety of manners. For example, the entire surface of wafer 30 may be coated with droplets 36, shown in FIG. 2, of imprinting material so that mold 28 may be sequentially placed in contact therewith at each region a-l. To that end, each region a-l would include the requisite volume of imprinting material so that the same would not egress into adjacent regions a-l upon being patterned by mold 28 and subsequently solidified, as discussed above. In this technique all the imprinting material required to pattern regions a-l is deposited over the surface of wafer before solidification and imprinting material in any of regions a-l. Alternatively, a sub-portion of regions a-l, e.g., one of regions a-l, may be provided with imprinting material that is subsequently patterned and solidified before remaining regions of a-l are provided with any imprinting material. In yet another embodiment, the entire surface of wafer may be provided with imprinting material deposited employing spin-coating techniques followed by sequentially patterning and solidifying imprinting material in each of regions a-l.

Proper execution of a step-and-repeat process may include proper alignment of mold 28 with each of regions a-l. To that end, mold 28 includes alignment marks 114 a, shown as a “+” sign. One or more of regions a-l includes fiducial marks 110 a. By ensuring that alignment marks 114 a are properly aligned with fiducial marks 110 a, proper alignment of mold 28 with one of regions a-l in superimposition therewith is ensured. To that end, machine vision devices (not shown) may be employed to sense the relative alignment between alignment marks 114 a and fiducial marks 110 a. In the present example, proper alignment is indicated upon alignment marks 114 a being in superimposition with fiducial marks 110 a. With the introduction of magnification/run-out errors, proper alignment becomes very difficult.

However, in accordance with one embodiment of the present invention, magnification/run-out errors are reduced, if not avoided, by creating relative dimensional variations between mold 28 and wafer 30. Specifically, the relative dimensions of mold 28 and wafer 30 are established so that at least one of regions a-l defines an area that is slightly less than an area of the original pattern on mold 28. Thereafter, the final compensation for magnification/run-out errors is achieved by subjecting template 26, shown in FIG. 8, to mechanical compression forces using actuator sub-assembly 72, which are in turn transferred to mold 28 shown by arrows F1 and F2, orientated transversely to one another, shown in FIG. 14. In this manner, the area of the original pattern is made coextensive with the area of the region a-l in superimposition therewith. To ensure that magnification correction is achieved primarily through reduction of dimensions of mold 28, patterns defined by mold 28 may be generated to be slightly larger than nominal, e.g., slightly larger than desired. In this manner, it could be said that the original pattern defined by mold 28 has a fixed magnification associated therewith, compared to the nominal dimensions of the pattern desired to be recorded in one of regions a-l. Actuator sub-assembly 72 is then employed to compress template 26 to provide the original pattern with a zero magnification. It is possible, however, to create thermal changes to vary the dimension of wafer 30 so that one of regions a-l has dimensions that are slightly less than the dimensions of mold 86.

Referring again to FIG. 6, when compressing template 26 with actuator sub-assembly 72, relative movement between template 26 and support regions 58 and 60 occurs along the X and Y axes. As a result, in one embodiment support regions 58 and 60 have surface regions 58 a and 60 a, respectively, formed thereon from a material adapted to conform to a profile of said template 26 and resistant to deformation along the X and Y axes. In this manner, surface regions 58 a and 60 a resist relative movement of template 26 with respect to chuck body 42 in the X and Y directions.

Referring to both FIGS. 2 and 15, providing a chuck body 142 with walls/baffles 142 a, 142 b, 142 c and 142 d facilitates providing sub-regions 152 a, 152 b, 152 c and 152 d with differing pressure levels, concurrently. As a result, the amount of force exerted on template 26 when being pulled-apart from imprinting layer 34 may vary across the surface of template 26. This allows cantilevering, or peeling-off of template 26 from imprinting layer 34 that reduces distortions or defects from being formed in imprinting layer 34 during separation of mold 28 therefrom. For example, sub-chamber 152 b may have a pressure established therein that is greater than the pressure associated with the remaining sub-chambers 152 a, 152 c and 152 d. As a result, when increasing distance “d” the pulling force of the portion of template 26 in superimposition with sub-chambers 152 a, 152 c and 152 d is subjected to is greater than the pulling force to which the portion of template 26 in superimposition with sub-chamber 152 b is subjected. Thus, the rate that “d” increases for the portion of template 26 in superimposition with sub-chambers 152 a, 152 c and 152 d is accelerated compared to the rate at which “d” increases for the portion of template 26 in superimposition with sub-chamber 152 b, providing the aforementioned cantilevering effect.

In yet another embodiment, shown in FIG. 16, chuck body 242 may include a plurality of pins 242 a projecting from a nadir surface 252 a of out recess 252. Pins 242 a provide mechanical support for the template (not shown) retained on chuck body 242 via vacuum and resting against surfaces 258 a and 260 a of support regions 258 and 260, respectively. Surface regions 258 a and 260 a provide a fluid-tight seal with the template (not shown). To that end, surfaces 258 a and 260 a are polished to be optically flat and pins 242 a extend from recess 252 terminating in a common plane with surfaces 258 a and 260 a. Mechanical support of the template (not shown) in the Z direction is provided by support regions 258 and 260 and pins 242 a, with pins 242 a typically being rigid posts having a circular or square cross-section. Pins 242 a are arranged in a patter so that the mold (not shown) on template (not shown) is substantially flat when a nominal vacuum pressure is applied.

Referring to FIGS. 13, 14 and 17, in operation, an accurate measurement of wafer 30 in an X-Y plane is undertaken at step 200. This may be achieved by sensing gross alignment fiducials 110 b present on wafer 30 using machine vision devices (not shown) and known signal processing techniques. At step 202, the area of one of regions a-l is established to be slightly less than an area of the original pattern on mold 28. This may be achieved by fabricating mold 28 to have a pattern thereon that is slightly larger than the area of one of regions a-l, and/or expanding the mold by varying the temperature thereof. Alternatively, or in conjunction therewith, the temperature of wafer 30 may be varied, i.e., raised or lowered, so that the area of one of regions a-l is slightly less than an area of the original pattern on mold 28. The temperature variations may be achieved using a temperature controlled chuck or pedestal (not shown) against which wafer 30 rests. The area of each of regions a-l can be determined by measurement of a change in distance between two collinear gross alignment fiducials 110 b.

Specifically, a change in the distance between two gross alignment fiducials lob collinear along one of the X or Y axes is determined. Thereafter, this change in distance is divided by a number of adjacent regions a-l on the wafer 30 along the X-axis. This provides the dimensional change of the areas of regions a-l attributable to dimensional changes in wafer 30 along the X-axis. If necessary the same measurement may be made to determine the change in area of regions a-l due to dimensional changes of wafer 30 along the Y-axis. However, it may also be assumed that the dimensional changes in wafer 30 may be uniform in the two orthogonal axes, X and Y.

At step 204, compressive forces, F1-10, are applied to mold 28 to establish the area of the original pattern to be coextensive with the area of one of the regions a-l in superimposition with the pattern and proper alignment between the pattern on mold 28 and one of the regions a-l. This may be achieved in real-time employing machine vision devices (not shown) and known signal processing techniques, to determine when two or more of alignment marks 114 a are aligned with two or more of fiducial marks 110 a. At step 206, after proper alignment is achieved and magnification/run-out errors are reduced, if not vitiated, the original pattern is recorded in the region a-l that is in superimposition with mold 28, forming the recorded pattern. It is not necessary that compression forces F1-10 have the same magnitude, as the dimensional variations in either wafer 30 or mold 28 may not be uniform in all directions. Further, the magnification/run-out errors may not be identical in both X-Y directions. As a result, compression forces, F1-10 may differ to compensate for these anomalies. Specifically, as mentioned above, each lever sub-assembly 74 of actuator sub-assembly 72 may operate independently. This affords application of differing force combinations F1-10 to mold 28 to compensate for magnification distortion, as well as distortions that may be present in pattern on mold, e.g., orthogonally distortions, such as skew distortions and keystone distortions. Furthermore, to ensure greater reduction in magnification/run-out errors, the dimensional variation in mold 28 may be undertaken after mold 28 contacts imprinting layer 124, shown in FIG. 6. However, this is not necessary.

Referring again to FIGS. 6, 13 and 14, the alignment of mold 28 with regions a-l in superimposition therewith may occur with mold 28 being spaced-apart from imprinting layer 124. Were it found that the magnification/run-out errors were constant over the entire wafer 30, then the magnitude of forces F1-10 could be maintained for each region a-l in which the original pattern is recorded. However, were it determined that the magnification/run-out errors differed for one or more regions a-l, steps 202 and 204, shown in FIG. 17, would then be undertaken for each region a-l in which the original pattern is recorded. It should be noted that there are limits to the relative dimensional changes that may occur between wafer 30 and mold 28. For example, the area of the regions a-l should be of appropriate dimensions to enable pattern on mold 28 to define an area coextensive therewith when mold 28 is subject to compression forces F1-10 without compromising the structural integrity of mold 28.

Referring to FIGS. 13, 14 and 18, in accordance with another embodiment of the present invention, accurate measurement of wafer 30 in an X-Y plane is undertaken at step 300. At step 302, it is determined whether the original pattern on mold 28 has any distortions, e.g., skew distortions, keystone distortions and the like. If there are original pattern distortions, a force differential is established to create the requisite differences in magnitude among forces F1-10 to remove the original pattern distortions, defining a force differential, at step 303. In this manner, skew distortions, keystone distortions and the like may be attenuated if not abrogated entirely to provide mold 28 with the original pattern desired. If there are no distortions in the original pattern, it is determined whether the area of one of regions a-l in superimposition with mold 28 is larger than the area of the pattern on mold 28, at step 304. If this is the case, the process proceeds to step 306, otherwise the process proceeds to step 308. At step 308, mold 28 is placed in contact with the region a-l in superimposition therewith, and the requisite magnitude of compressive forces F1-10 is determined to apply to mold 28 to ensure that the area of pattern is coextensive with the area of this region a-l, with the compressive forces including the force differential. At step 310, compressive forces F1-10 are applied to mold 28 and the pattern is recorded in wafer 30. At step 311, the pattern is recorded on wafer. Thereafter, mold 28 is spaced-apart from the region a-l in superimposition with mold 28 and the process proceeds to step 312 where it is determined whether there remain any regions a-l on wafer 30 in which to record the original pattern. If there are, the process proceeds to step 314 wherein mold is placed in superimposition with the next region and the process proceeds to step 304. Otherwise, the process ends at step 316.

Were it determined at step 304 that the region a-l in superimposition with mold 28 had an area greater than the area of the pattern, then the process proceeds to step 306 wherein the temperature of mold 28 and/or wafer 30 is varied to cause expansion of the same. In the present embodiment, mold 28 is heated at step 306 so that the pattern is slightly larger than the area of region a-l in superimposition therewith. Then the process continues at step 310.

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. For example, by pressurizing all chambers formed by the chuck body-substrate combination with positive fluid pressure, the substrate may be quickly released from the chuck body. Further, many of the embodiments discussed above may be implemented in existing imprint lithography processes that do not employ formation of an imprinting layer by deposition of droplets of polymerizable material. 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.

Referenced by
Citing PatentFiling datePublication dateApplicantTitle
US7360851Feb 15, 2006Apr 22, 2008Kla-Tencor Technologies CorporationAutomated pattern recognition of imprint technology
US7708926Feb 5, 2008May 4, 2010Molecular Imprints, Inc.Capillary imprinting technique
US7837907Jul 17, 2008Nov 23, 2010Molecular Imprints, Inc.Alignment system and method for a substrate in a nano-imprint process
US8231821Nov 2, 2009Jul 31, 2012Molecular Imprints, Inc.Substrate alignment
US8345242Oct 16, 2009Jan 1, 2013Molecular Imprints, Inc.Optical system for use in stage control
US8361371Feb 6, 2009Jan 29, 2013Molecular Imprints, Inc.Extrusion reduction in imprint lithography
US8432548Oct 27, 2009Apr 30, 2013Molecular Imprints, Inc.Alignment for edge field nano-imprinting
US8553207 *Apr 7, 2009Oct 8, 2013Asml Holdings N.V.Optically compensated unidirectional reticle bender
US20100167189 *Apr 7, 2009Jul 1, 2010Asml Holding N.V.Optically Compensated Unidirectional Reticle Bender
US20120193832 *Jan 30, 2012Aug 2, 2012Canon Kabushiki KaishaHolding apparatus, imprint apparatus and article manufacturing method using same
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Classifications
U.S. Classification355/72
International ClassificationG03B27/58, B29C43/02, G03F7/00, B81C99/00
Cooperative ClassificationB82Y40/00, B82Y10/00, G03B27/58, G03F7/0002
European ClassificationB82Y10/00, B82Y40/00, G03F7/00A, G03B27/58
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Apr 4, 2012ASAssignment
Owner name: NAVY, UNITED STATES OF AMERICA AS REPRESENTED BY T
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Effective date: 20111202
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Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNORS:CHERALA, ANSHUMAN;CHOL, BYUNG-JIN;NIMMAKAYALA, PAWAN K.;AND OTHERS;REEL/FRAME:016184/0252
Effective date: 20050324
Mar 24, 2005ASAssignment
Owner name: MOLECULAR IMPRINTS, INC., TEXAS
Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNORS:CHERALA, ANSHUMAN;CHOI, BYUNG-JIN;NIMMAKAYALA, PAWAN K.;AND OTHERS;REEL/FRAME:015959/0662
Effective date: 20050324