KR20050026088A - Scatterometry alignment for imprint lithography - Google Patents

Abstract

Described are methods for patterning a substrate by imprint lithography. Imprint lithography is a process in which a liquid is dispensed onto a substrate. A template is brought into contact with the liquid and the liquid is cured. The cured liquid includes an imprint of any patterns formed in the template. Alignment of the template with a previously formed layer on a substrate, in one embodiment, is accomplished by using scatterometry.

Description

Scatterometer alignment for imprint lithography {SCATTEROMETRY ALIGNMENT FOR IMPRINT LITHOGRAPHY}

Embodiments described herein relate to methods and systems for imprint lithograhpy. In particular, these embodiments relate to methods and systems for micro- and nano-imprint lithography processes.

Currently, optical lithography techniques are used to manufacture most microelectronic devices. However, these methods are considered to have reached their limits in terms of resolution. Sub-micron scale lithography is an important process in the microelectronics industry. The use of submicron size lithography can meet the needs of manufacturers who want to place smaller, higher density packed electronic circuits on chips. The microelectronics industry is expected to pursue structures smaller than or smaller than about 50 nm. In addition, nanometer-sized lithography has begun to be applied in the fields of opto-electronic and magnetic storage. For example, terabytes per square inch of high density patterned magnetic memory and photonic crystals may require lithography of sub-100 nanometers in size.

To produce sub-50 nm structures, optical lithography techniques may need to use very short wavelengths of light (eg, about 13.2 nm). At these short wavelengths, many conventional materials are optically impermeable, so imaging systems are generally constructed using complex reflected light. In addition, it is difficult to obtain a light source having sufficient output intensity at these wavelengths. Such systems involve overly expensive processes and extremely complex equipment. In addition, high-resolution e-beam lithography techniques are very precise but are considered too slow for commercial use for high volume manufacturing.

As an alternative to conventional photolithography for high resolution patterning, a variety of imprint lithography techniques have been studied for mass production at low cost. Imprint lithography techniques are similar in that they replicate a surface relief in a film on a substrate using a template that includes topograhpy. One form of imprint lithography is known as hot embossing.

Hot embossing technology faces a number of problems: i) A pressure greater than 10 MPa is required to imprint the relief structure, ii) the temperature must be greater than the T _g of the polymer film, and iii) the isolation (in the substrate film) pattern isolating isolation similar to repeated lines and spacing. It should be limited to trenches or dense features. Hot embossing is unsuitable for printing isolated raised structures such as lines and dots. This is because the very high viscosity liquid generated due to the increase in temperature of the substrate film needs to be kept at very high pressure and for a long time to carry the large amount of liquid needed to create the isolation structure. This pattern dependency did not attract hot embossing. In addition, high pressure and high temperature, thermal expansion and material deformation create serious technical problems in interlayer alignment with the accuracy required to manufacture the device. Such pattern placement distortions cause problems, for example, when using patterned magnetic media for storage purposes. If the pattern placement distortion is not kept to a minimum, handling the patterned medium bits by the read-write head faces a very serious problem.

BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 shows an example of a system for imprint lithography.

2 shows an imprint lithography system enclosure.

3 illustrates one embodiment of an imprint lithography head coupled to an imprint lithography system.

4 is a perspective view of an imprint head;

5 is an enlarged view of an imprint head.

6 is a perspective view of a first flexure member.

7 is a perspective view of a second bending member.

8 is a perspective view of the combined first and second flexure members.

9 is a perspective view of a fine orientation system coupled to a pre-calibration system of the imprint head.

10 is a cross-sectional view of a pre-calibration system.

11 is a schematic diagram of a bending system.

12 is a perspective view of a motion stage and an imprint head of an imprint lithography system.

Figure 13 is a schematic diagram of a liquid dispense system.

Figure 14 is a perspective view of an imprint head with a camera and a light source optically coupled to the imprint head.

15 and 16 are side views of the interface between liquid droplets and portions of the template.

Figure 17 is a cross sectional view of a first embodiment of a template configured for confining liquid at the periphery of the template;

Figure 18 is a cross sectional view of a second embodiment of a template configured for confining liquid at the periphery of the template;

19A-19D are cross-sectional views of a series of steps of a template in contact with a liquid disposed on a substrate.

20A and 20B are top and cross-sectional views, respectively, illustrating a template having a plurality of patterning areas and borders.

Figure 21 is a perspective view of a rigid template support system coupled to the pre-calibration system of the imprint head.

Figure 22 shows an imprint head coupled to the X-Y motion system.

23A-23F are cross-sectional views of a negative imprint lithography process.

24A-24D are cross-sectional views of a negative imprint lithography process with a transfer layer.

25A-25D are cross-sectional views of a positive imprint lithography process.

26A-26C are cross-sectional views of a positive imprint lithography process with a carrier layer.

27A-27D are cross-sectional views of a combined positive and negative imprint lithography process.

Figure 28 is a schematic diagram of an optical alignment measuring device positioned on a template and a substrate.

FIG. 29 illustrates a method of determining alignment of a template with respect to a substrate using alignment marks by sequentially viewing and refocusing. FIG.

30 illustrates a manner of determining alignment of a template with respect to a substrate using alignment marks and polarized filters.

Fig. 31 is a top view of an alignment mark formed from polarization lines.

32A-32C are top views of patterns of curable liquids applied to a substrate.

33A-33C illustrate a manner of removing a template from a substrate after curing.

Figure 34 illustrates one embodiment of a template located on a substrate for field-based lithography.

35A-35D illustrate a first embodiment of a process for forming nanoscale structures using contact with a template.

36A-36C illustrate a first embodiment of a process for forming a nanosize structure without contacting a template.

37A-37B illustrate a template including a continuous patterned conductive layer disposed on a nonconductive base.

FIG. 38 illustrates a motion station with a substrate tilt module. FIG.

FIG. 39 illustrates a motion station including a fine orientation system. FIG.

40 is a schematic diagram of a substrate support;

Figure 41 is a schematic diagram of an imprint lithography system including an imprint head disposed below the substrate support.

42 is a diagram schematically showing the degree of motion of a template and a substrate.

Fig. 43 is a schematic diagram of a position detector based on an interferometer.

Fig. 44 is a perspective view of a position detector based on an interferometer.

45 is a cross sectional view of a patterned template including alignment marks surrounded by boundaries;

46A-46D are schematic diagrams of an off axis alignment method.

47A-47E are top views of theta alignment process.

48A is a top view of an alignment target including a diffraction grating.

48B is a sectional view of a diffraction grating;

48C is a top view of the alignment target including diffraction gratings with different spacing.

49 is a schematic diagram of a scatterometry system for analyzing multiple wavelengths on N-th scattered light.

50 is a schematic diagram of a scatterometry system for analyzing a plurality of wavelengths for N-scattered light through an optical element;

FIG. 51 is a schematic diagram of a scatterometry system for analyzing zero order scattered light at a non-vertical angle. FIG.

Fig. 52 is a schematic diagram of a scatterometry system for analyzing zero-order scattered light at non-vertical angles through optical elements.

Fig. 53 is a schematic diagram of a scatterometry system for analyzing zero-order scattered light at non-vertical angles through an optical fiber system.

54 is a schematic diagram of a scatterometry system for analyzing N-scattered light at non-vertical angles through an optical fiber system;

In one embodiment, the patterned layer is formed by curing an activating light curable liquid disposed on the substrate in the presence of the patterned template. The patterned template is placed over a portion of the substrate. Typically, certain portions of the substrate include preformed patterning areas. Aligning the template with the substrate is accomplished by alignment marks on both the template and the substrate.

In one embodiment, the patterned templates are placed in spaced relation to the substrate. The patterned template includes alignment marks. The template alignment mark includes a diffraction grating that matches the corresponding substrate alignment mark. A scatterometry alignment system is coupled to the body to analyze the alignment of the template diffraction grating with the substrate diffraction grating. Alignment is achieved by illuminating the template alignment mark and the substrate alignment mark with light at an angle substantially perpendicular to the plane defined by the substrate. Reflected light is measured along a non-zero order from the template and substrate alignment mark. Light measurements include analyzing light intensity at multiple wavelengths. Means outside the light intensity at multiple wavelengths are used to determine the mean alignment error. The average alignment error can be used to change the position of the template relative to the substrate before forming the patterned layer.

In another embodiment, the patterned template is placed in a spaced relationship relative to the substrate. The patterned template includes alignment marks. The template alignment mark includes a diffraction grating that matches the corresponding substrate alignment mark. Alignment is achieved by illuminating the template alignment mark and the substrate alignment mark with two incident light beams at an angle substantially non-perpendicular to the plane defined by the substrate. Light reflected along the zero order from the template and substrate alignment marks is measured. Optical measurements include analyzing light intensities at multiple wavelengths. Averages outside the light intensity reading at multiple wavelengths are used to determine the average alignment error. The average alignment error can be used to change the position of the template relative to the substrate before forming the patterned layer.

In yet another embodiment, the patterned template is placed in a spaced relationship relative to the substrate. The patterned template includes alignment marks. The template alignment mark includes a diffraction grating that matches the corresponding substrate alignment mark. Alignment is achieved by illuminating the template alignment mark and the substrate alignment mark with two incident light beams at an angle substantially non-perpendicular to the plane defined by the substrate. Light reflected along the non-zero difference from the template and substrate alignment marks is measured. Optical measurements include analyzing light intensities at multiple wavelengths. Averages outside the light intensity reading at multiple wavelengths are used to determine the average alignment error. The average alignment error can be used to change the position of the template relative to the substrate before forming the patterned layer.

Other objects and advantages of the present invention will become apparent from the following description taken in conjunction with the accompanying drawings.

While the invention may be in various modifications and alternative forms, specific embodiments of the invention are shown by way of example in the drawings and will be described in detail herein. However, the drawings and detailed description of the invention are not intended to limit the invention to the particular forms described, but rather all such modifications, equivalents, and alternatives falling within the spirit and scope of the invention as defined in the appended claims. Include them.

Embodiments described herein generally relate to systems, apparatuses, and related processes for manufacturing small apparatus. In particular, the embodiments described herein relate to systems, apparatuses and processes associated therewith in imprint lithography. For example, these embodiments can be used to imprint sub 100 nm features on a substrate such as a semiconductor wafer. These embodiments also include, but are not limited to, patterned magnetic media for data storage, micro-optical devices, micro-electro-mechanical systems, biological test devices, chemical test and reaction devices, and X-ray optics devices. It should be understood that it can be used to manufacture other kinds of devices.

Imprint lithography processes have been demonstrated to replicate high-resolution (sub-50 nm) images on a substrate using templates that include images such as topography on the substrate surface. Imprint lithography can be used to pattern substrates in the manufacture of microelectronic devices, optical devices, MEMS, opto-electronics, patterned magnetic media for storage applications, and the like. Imprint lithography techniques can be superior to optical lithography to fabricate three-dimensional structures such as microlenses and T-gate structures. Including templates, substrate liquids, and any other materials that may affect physical properties including, but not limited to, surface energy, interfacial energy, Hamacker constant, Van der Waals' forces, viscosity, density, impermeability, etc. Elements of an imprint lithography system are designed to suitably accommodate a repeatable process.

A method and system for imprint lithography is disclosed in US Pat. No. 6,334,960, entitled "Step and Flash Imprint Lithography," to Willson et al., Which is incorporated herein by reference. Additional methods and systems for imprint lithography are also described in US patent application Ser. No. 09 / 908,455, filed July 17, 2001, entitled "Method and System of Automatic Fluid Dispensing for Imprint Lithography Processes"; US Patent Application No. 09 / 907,512, entitled "High-Resoultion Overlay Alignment Methods and System for Imprint Lithography," filed July 16, 2001; US Patent Application No. 09 / 920,341 filed August 1, 2001, entitled "Methods for High-Precision Gap Orientation Sensing Between a Transparent Template and Substrate for Imprint Lithography"; US Patent Application No. 09 / 934,248, entitled "Flexure Based Macro Motion Translation Stage," filed August 21, 2001; US Patent Application No. 09 / 698,317, entitled "High-Precision Orientation Alignment and Gap Control Stages for Imprint Lithography Processes," filed October 27, 2000; US Patent Application No. 09 / 976,681, entitled "Template Design for Room Temperature, Low Pressure Micro-and Nano-Imprint Lithography," filed October 12, 2001; US patent application Ser. No. 10 / 136,188, entitled "Methods of Manufacturing a Lithography Template," filed May 1, 2002; And US patent application entitled "Method and System for Fabrication Nanoscale Patterns in Light Curable Compositions Using an Electric Field" filed May 16, 2001, all of which are incorporated herein by reference. It is. Additional methods and systems are described in the following publication, To appear in J. of Precision Engineering, B.J. Choi, S. Johnson, M. Colburn, S.V. Sreenivasan, C.G. Willson's "Design of Orientation Stages for Step and Flash Imprint Lithography"; "Large area high density quantized" published by W. Wu, B. Cui, XY Sun, W. Zhang, L. Zhunag, and SY Chou., In J. Vac Sci Technol B 16 (6) 3825-3829 Nov-Dec 1998. magnetic disks fabricated using nanoimprint lithography "; J. Vac Sci Technol B 17 (6) 3197-3202 published by SYChou, L.Zhuang in "Lithographically-induced Self-assembly of Periodic Polymer Micropillar Arrays" and Macromolecules 13, 4399 (1998), P. Mansky, Disclosed in "Large Area Domain Alignment in Block Copolymer Thin Films Using Electric Fields" published by J. DeRouchey, J. Mays, M. Pitsikalis, T. Morkved, H. Jaeger and T. Russell, all of which are incorporated herein by reference. It is.

1 illustrates one embodiment of a system for imprint lithography 3900. This system 3900 includes an imprint head 3100. The imprint head 3100 is provided on the imprint head support 3910. Imprint head 3100 is configured to support patterned template 3700. Patterned template 3700 includes a plurality of recesses that define a pattern of shapes to be imprinted into the substrate. Imprint head 3100 or motion stage 3600 is also configured to move patterned template 3700 toward and away from the substrate to be imprinted in use. System 3900 also includes a motion stage. The motion stage 3600 is installed on the motion stage support 3920. The motion stage 3600 is configured to support the substrate and move the substrate in generally planar motion relative to the motion stage support 3920. System 3900 further includes a curing light system 3500 coupled to imprint head 3100. The active light system 3500 is configured to generate cured light and direct the generated cured light through a patterned template 3700 coupled to the imprint head 3100. Cured light includes light of the appropriate wavelength to cure the polymerizable liquid. Cured light includes ultraviolet light, visible light, infrared light, x-ray radiation and electron beam radiation.

Imprint head support 3910 is coupled to motion stage support 3920 by bridging support 3930. In this way, imprint head 3100 is positioned above motion stage 3600. Imprint head support 3910, motion stage support 3920, and bridging support 3930 are all referred to herein as a system “body”. The components of the system body may be formed of a thermally stable material. Thermally stable materials have a coefficient of thermal expansion of less than about 10 ppm / ° C. at nearly room temperature (eg, 25 ° C.). In some embodiments, the constituent material may have a coefficient of thermal expansion less than about 10 ppm / ° C. or less than 1 ppm / ° C. Examples of such materials include silicon carbide; Alloys of steel and nickel (e.g., commercially available alloys with the trade name INVAR ^?? ) and alloys of certain steel, nickel and cobalt (e.g., commercially available alloys with the trademark super INVAR ^?? ) Any iron alloy is not limited to this. Motion stage support 3920 and bridging support 3930 are coupled to support table 3940. The support table 3940 supports the components of the system 3900 so that the components of the system 3900 hardly vibrate. The support table 3940 isolates the system 3900 from ambient vibrations (eg, due to work, other machinery, etc.). Motion stages and vibration isolation support tables are commercially available from Newport Corpoation, Irvine, California.

As used herein, the “X-axis” is referred to as the axis extending between the bridging supports 3930. As used herein, a “Y-axis” is referred to as an axis orthogonal to the X-axis. As used herein, an "X-Y plane" is a plane defined on the X-axis and the Y-axis. As used herein, the "Z-axis" is referred to as the axis extending from the motion stage support 3920 to the imprint head support 3910 orthogonal to the X-Y plane. In general, the imprint process includes moving the substrate or imprint head along the X-Y plane until an appropriate position of the substrate is achieved with respect to the patterned template. Moving the template or motion stage along the Z-axis will move the patterned template to a position where it contacts between the patterned template and the liquid disposed on the surface of the substrate.

System 3900 may be disposed in an enclosure as shown in FIG. Enclosure 3960 surrounds imprint lithography system 3900 and provides a thermal and air barrier to the lithographic component. Enclosure 3960 includes a movable access panel 3962 that accesses the imprint head and the motion stage when moved to the "open" position as shown in FIG. When in the "closed" position, the components of the system 3900 are at least partially isolated from the room atmosphere. The access panel 3962 also acts as a thermal barrier, reducing the change in temperature in the room affecting the temperature of the components in the enclosure 3960. Enclosure 3960 includes a temperature control system. The temperature control system is used to control the temperature of the components in the enclosure 3960. In one embodiment, the temperature control system is configured to prevent a temperature change greater than about 1 ° C. in the enclosure 3960. In some embodiments, the temperature control system prevents changes greater than about 0.1 ° C. In one embodiment, thermostats or other temperature measuring devices that cooperate with one or more fans may be used to keep enclosure 3960 maintain a substantially constant temperature.

Various user interfaces may also be provided on the enclosure 3960. The user interface 3936 can represent operating parameters, diagnostic information, task progression, and other information related to the functionality of the enclosed imprint system 3900. User interface 3936 may also be configured to receive operator commands to change operating parameters of system 3900. Staging support 3946 may also be coupled to enclosure 3960. The staging support 3946 is used to allow the operator to support the substrate, template, and other equipment during the imprint lithography process. In some embodiments, staging support 3966 may include one or more indentations 3767 (eg, a circular indentation of a semiconductor wafer) configured to support a substrate. The staging support 3946 may also include one or more indentations 3976 to support the template.

Additional components may be provided depending on the process of designing to implement the imprint lithography system. For example, semiconductor processing equipment, including but not limited to interfaces with automatic wafer loaders, automatic template loaders, and cassette loaders, all of which are not shown, may be coupled to the imprint lithography system 3900.

3 illustrates one embodiment of a portion of an imprint head. Imprint head 3100 includes a pre-calibration system 3109 and a fine orientation system 3111 coupled to the pre-calibration system. The template support 3130 is coupled to the micro orientation system 3111. The template support 3130 is designed to support the template 3700 and to couple to the micro orientation system 3111.

Referring to FIG. 4, a disk-shaped flex ring 3124 that forms part of the pre-calibration system 3109 is coupled to the imprint head housing 3120. The imprint head housing 3120 is coupled to the intermediate frame 3114 by guide shafts 3112a and 3112b. In one embodiment, three guide shafts (back guide shafts are not shown in FIG. 4) may be used to support the housing 3120. Sliders 3116a and 3112b, which are coupled to the corresponding guide axes 3112a and 3112b with respect to the intermediate frame 3114, are used to facilitate the up and down movement of the housing 3120. The disc-shaped base plate 3122 is coupled to the bottom portion of the housing 3120. Base plate 3122 may be coupled to bend ring 3124. The bend ring 3124 supports the micro-orientation system component that includes the first bent member 3126 and the second bent member 3128. The operation and configuration of flexure members 3126 and 3128 are described in detail below.

5 is an enlarged view of the imprint head 3700. Actuators 3134a, 3134b, 3134c are secured in housing 3120 and coupled to base plate 3122 and flex ring 3124 as shown in FIG. 5. In operation, the motion of the actuators 3134a, 3134b, 3134c controls the movement of the bend ring 3124. The motion of the actuators 3134a, 3134b, 3134c may allow coarse pre-calibration. In some embodiments, the actuators 3134a, 3134b, 3134c may be evenly spaced around the housing 3120. Actuators 3134a, 3134b, 3134c and bend ring 3124 both form a pre-calibration system. Actuators 3134a, 3134b, 3134c move flexure ring 3124 along the Z-axis to precisely control the gap.

The imprint head 3100 may also include a mechanism for finely directional control of the template 3700 so that proper orientation alignment is achieved and a uniform gap is maintained by the template relative to the substrate surface. In one embodiment, alignment and gap control are achieved by using each of the first and second flexure members 3126 and 3128.

6 and 7 illustrate embodiments of each of the first and second flexure members 3126 and 3128 in more detail. First flex member 3126 includes a plurality of flex joints 3160 coupled to corresponding rigid bodies 3164 and 3166 as shown in FIG. The flex joint 3160 is notched shaped to move the rigid bodies 3164 and 3166 relative to the pivot axis located along the thinnest cross section of the flex joint. Both the flex joint 3160 and the rigid body 3164 form an arm 3172, while the additional flex joint 3160 and the rigid body 3166 both form an arm 3174. Arms 3172 and 3174 are coupled to and extend from the first bend frame 3170. The first bend frame 3170 has an opening 3142, which passes cured light (eg, ultraviolet light) to the first bent member 3126. In the illustrated embodiment, the four bend joints 3160 move the first bend frame 3170 about the first direction axis 3180. However, it should be understood that some flexion joints can be used to achieve the desired control. As shown in FIG. 8, the first bending member 3126 is coupled to the second bending member 3128 through the first bending frame 3170. The first flex member 3126 also includes two engagement members 3184 and 3186. Engagement members 3184 and 3186 include openings that attach the engagement member to flexure ring 3124 using any suitable fastening means. Coupling members 3184 and 3186 are coupled to first bend frame 3170 through arms 3172 and 3174 as shown.

Second flexure member 3128 includes a pair of arms 3202 and 3204 extending from second flexure frame 3206 as shown in FIG. Both the flex joint 3316 and the rigid body 3208 form an arm 3202, while the additional flex member 3322 and the rigid body 3210 both form an arm 3204. The flex joint 3316 is notched, and can move the rigid bodies 3210 and 3204 relative to the pivot axis located along the thinnest cross section of the flex joint. Arms 3202 and 3204 are coupled to and extend from the template support 3130. Template support 3130 is configured to support and maintain at least a portion of the patterned template. The template support 3130 also has an opening 3212 that passes cured light (eg, ultraviolet light) to the second flex member 3128. In the illustrated embodiment, the four bent joints 3322 move the template support 3130 about the second direction axis 3200. However, it should be understood that some flexion joints can be used to achieve the desired control. Second flexure member 3128 also includes braces 3220 and 3222. The braces 3220 and 3222 include openings that attach the braces to portions of the first bent member 3126.

In one embodiment, as shown in FIG. 8, the first bent member 3126 and the second bent member 3128 are combined to form the fine direction measuring unit 3111. The braces 3220 and 3222 are coupled to the first bend frame 3170 such that the direction axis 3180 of the first bend member 3126 and the second direction axis 3200 of the second bend member are substantially orthogonal to each other. do. In such a configuration, the first direction axis 3180 and the second direction axis 3200 intersect at pivot point 3252 in a substantially central region of the patterned template disposed on the template support 3130. The combination of the first and second flexure members allows for fine alignment and gap control of the patterned template 3700 during use. Although the first and second flex members are shown as discrete elements, it should be understood that the first and second flex members may be formed from a single machined portion in which both flex members are integrated. Flexure members 3126 and 3128 are joined by mating surfaces to cause motion of patterned template 3700 to occur relative to pivot point 3252, thereby shearing imprinted features following imprint lithography. It substantially reduces "swinging" and other motion that can be sheared. The micro-orientation section provides a non-negligible lateral motion at the template surface and an almost non-negligible twisting motion relative to the template surface due to the optionally limited high structural stiffness bending joints. Another advantage of using the bending members described herein is that these members do not generate large amounts of particles, especially when compared to friction joints. Since the particles can disrupt such an imprint lithography process, this provides an advantage for the imprint lithography process.

9 shows an assembled fine orientation system coupled to a pre-calibration system. Patterned template 3700 is located within template support 3130, which is part of second flexure member 3128. The second bent member 3128 is coupled to the first bent member 3126 in a substantially orthogonal direction. The first bent member 3124 is coupled to the bent ring 3124 through coupling members 3186 and 3184. Flex ring 3124 is coupled to base plate 3122 as described above.

10 is a cross-sectional view of the pre-calibration system seen through cross section 3260. Flex ring 3124 is coupled to base plate 3122 with actuator 3134 as shown in FIG. Actuator 3134 includes an end 3270 coupled to a force detector 3135 that contacts flexure ring 3124. In use, the end 3270 moves toward or out of the bend ring 3124 due to the operation of the actuator 3134. Movement of the end 3270 toward the bend ring 3124 deforms the bend ring and moves the microorientation system toward the substrate along the Z-axis. Moving the base 3270 out of the bend ring causes the bend ring to move to its original shape, and in this process, the microdirectional stage is moved off the substrate.

In a typical imprint process, as shown in the preceding figures, the template is placed in a template holder coupled to the micro orientation system. The template is moved to contact the liquid on the surface of the substrate. When the template comes closer to the substrate, the compression of the liquid on the substrate causes the resistive force to be applied onto the template by the liquid. This resistive force is transferred to the bend ring 3124 through the micro orientation system as shown in FIGS. 9 and 10. This force exerted against the bend ring 3124 will also be transferred as resistance to the actuator 3134. The resistance applied to the actuator 3134 can be determined using the force sensor 3135. The force sensor 3135 may be coupled to the actuator 3134 such that the resistive force applied to the actuator 3135 may be determined and controlled during use.

FIG. 11 shows a curvature model designated generally 3300, useful for understanding the principle of operation of a fine decoupled orientation stage, such as the micro orientation described herein. Flexure model 3300 may include four parallel joints, joints 1, 2, 3, and 4, which are four-bar linkage systems in nominal and rotated configurations. (four-bar-linkage system). Line 3310 represents the alignment axis of joints 1 and 2. Line 3312 represents the alignment axis of joints 3 and 4. The angle α ₁ represents the angle between the rule axis and the line 3310 passing through the center of the template 3700. Angle α ₂ represents the angle between the vertical axis passing through the center of template 3700 and line 3310. In some embodiments, angles α ₁ and α ₂ are selected such that a compliant alignment axis (or direction axis) substantially lies on the template 3700 surface. With respect to the micro-direction change, the rigid body 3314 between the joints 2 and 3 can rotate about the axis shown by the point C. The rigid body 3314 may represent the template support 3130 of the second flexure member 3128.

Generates tilting motions with virtually no lateral motion at the surface of the template coupled to the micro-orientation system. The use of flex arms can provide a fine directional system having high stiffness in directions where lateral motion or rotation is undesirable and low stiffness in directions where the required directional motion is desired. Therefore, the micro-orientation system rotates the template support and the template with respect to the pivot point at the surface of the template while providing sufficient resistance in the direction perpendicular to and parallel to the template to maintain a proper position relative to the substrate. In this way, a manual orientation system is used for orientation of the template in a direction parallel to the template. The term "manual" refers to motion that occurs without any user or programmable controller intervention, ie the system self-calibrates in the proper direction by contacting the template with the liquid. Alternative embodiments may also be implemented that control the flex arms with a motor to generate active flex.

The motion of the microdirectional stage can be activated by direct or indirect contact with the liquid. If the microdirectional stage is passive, in one embodiment, the stage is designed to have dominant compliance for the two direction axes. The two direction axes lie perpendicular to each other and on the imprinting surface of the imprinting member disposed on the microdirectional stage. The two orthogonal torsional compliance values are set to be the same for the symmetrical imprint member. The passive micro-orientation stage is designed to change the orientation of the template when the template is not parallel to the substrate. When the template is in contact with the liquid on the substrate, the flexure member compensates for the uneven liquid pressure generated on the template. Such compensation can be done minimally or not excessively. In addition, the microdirectional stage as described above can maintain a substantially parallel orientation between the template and the substrate for a sufficiently long period of time to cure the liquid.

The imprint head 3100 is installed in the imprint head support 3910 as shown in FIG. 1. In this embodiment, this imprint head 3910 is installed so that the imprint head 3910 is always kept in a fixed position. In use, all movements along the X-Y plane are performed with respect to the substrate by the motion stage 3600.

Motion stage 3600 is used to support the substrate to be imprinted and to move the substrate along the X-Y plane during use. In some embodiments, the motion stage may move the substrate over a distance of up to several hundred millimeters with an accuracy of at least ± 30 nm, preferably with an accuracy of about ± 10 nm. In one embodiment, the motion stage includes a substrate chuck 3610 coupled to a carriage 3620 as shown in FIG. The carriage 3620 is moved relative to the base 3630 on the friction bearing system or the frictionless bearing system. In one embodiment, a non-friction bearing system is used that includes an air bearing. In one embodiment, the carriage 3620 is suspended over the base 3630 of the motion stage using an air layer (ie, "air bearing"). Magnetic or vacuum systems can be used to provide counter bearing forces for air bearing levels. Magnetic and vacuum based systems are commercially available from various suppliers, and any such system can be used in an imprint lithography process. One example of a motion stage that can be applied to an imprint lithography process is the Dynam YX motion stage, commercially available from Newport Corporation, Irvine, California. This motion stage can also include a tip tilt stage similar to the calibration stage, allowing the substrate to be approximately flush with the X Y motion plane. It also includes one or more theta stages to direct the pattern on the substrate to the X Y motion axis.

System 3900 also includes a liquid dispense system that is used to dispense curable liquid onto a substrate. The liquid dispense system is coupled to the system body. In one embodiment, the liquid dispense system is coupled to the imprint head 3100. 3 shows a liquid dispenser head 2507 of the liquid dispense system extending out from the cover 3127 of the imprint head 3100. Various components of the liquid dispense system 3125 may be disposed within the cover 3127 of the imprint head 3100.

A liquid dispense system is shown schematically in FIG. In one embodiment, the liquid dispense system includes a liquid container 2501. Liquid container 2501 is configured to store an active photocurable liquid. Liquid container 2501 is coupled to pump 2504 through inlet pipe 2502. An inlet valve 2503 is located between the liquid container 2501 and the pump 2504 to control the flow through the inlet tube 2502. Pump 2504 is coupled to liquid dispenser head 2507 through outlet tube 2506.

The liquid dispense system is configured to precisely control the volume of liquid volume dispensed onto the underlying substrate. In one embodiment, liquid control is accomplished using a piezoelectric valve as the pump 2504. Piezoelectric valves are commercially available from Lee Company, Westbrook, Connecticut. In use, the curable liquid is drawn to pump 2504 through inlet tube 2502. When the substrate is properly positioned below, the pump 2504 is operated to pass a volume of liquid through the outlet tube 2506. Thereafter, the liquid is dispensed onto the substrate through the liquid dispenser head 2507. In this embodiment, liquid volume control is achieved by the control of the pump 2504. Rapid switching of the pump from an open state to a closed state allows a controlled amount of liquid to be delivered to the dispenser head 2507. Pump 2504 is configured to dispense a volume of liquid less than about 1 μL. Operation of the pump 2504 dispenses either a droplet of liquid or a pattern of continuous liquid onto the substrate. This droplet is applied by rapidly circulating the pump from an open state to a closed state. The liquid stream exits the pump in the open state and is generated on the substrate by moving the substrate under the liquid dispenser head.

In yet another embodiment, liquid volume control may be accomplished by the use of a liquid dispenser head 2507. In such a system, pump 2504 is used to supply the curable liquid to the liquid dispenser head 2507. Small drops of liquid whose volume is precisely specified are dispensed by liquid dispensing actuators. Examples of liquid dispensing actuators include micro-solenoid valves or piezo-operated dispensers. Piezo-operated dispensers are commercially available from MicroFab Technologies, Inc., Plano, Texas. The liquid dispensing actuator is integrated in the liquid dispenser head to control the liquid dispense. The liquid dispensing actuator is configured to dispense between about 50 pL and about 1000 pL of liquid per drop of liquid dispensed. Advantages of systems with liquid dispensing actuators include more accurate volume control than faster dispensing times. Liquid dispensing systems are also disclosed in US patent application Ser. No. 09 / 908,455, entitled "Method and System of Automatic Fluid Dispensing for Imprint Lithography Processes," filed July 17, 2001. Reference is made herein.

Rough determination of template and substrate position is determined by using a linear encoder (eg an exposed linear encoder). The encoder provides rough measurements on the order of 0.01 μm. The linear encoder includes a scale coupled to the moving object and a reader coupled to the body. This scale can be formed from a variety of materials including glass, glass ceramics, and steel. This scale includes a number of markings read by the reader to determine the relative or absolute position of the moving object. This scale is coupled to the motion stage by means known in the art. The reader is coupled to the body and optically coupled to the scale. In one embodiment, an exposed linear encoder can be used. The encoder can be configured to determine the position of the motion stage along either a single axis or a two-axis plane. An example of an exposed two-axis linear encoder is a PP model encoder commercially available from Heidenhain Corporation, Schaumburg, IL. In general, encoders are built with many commercially available X-Y motion stages. For example, the Dynam YX motion stage, commercially available from Newport Corp, has a two-axis encoder built into the system.

The rough position of the template along the Z-axis is also determined by the linear encoder. In one embodiment, the exposed linear encoder can be used to measure the position of the template. In one embodiment, the scale of the linear encoder is coupled to the pre-calibration ring of the imprint head. Alternatively, this scale can be coupled directly to the template support 3130. The reader is coupled to the body and optically coupled to the scale. The position of the template is determined along the Z-axis by using an encoder.

In some embodiments, the detection of the position of the template and substrate during the imprint lithography process needs to be known with an accuracy of less than 100 nm. Since many shapes for patterned templates in high resolution semiconductor processes are smaller than 100 nm, such control is important for proper alignment of these shapes. In one embodiment, fine position detection can be determined using interferometers (eg, laser interferometers).

Figure 42 illustrates a rotation and movement axis that can be determined during an imprint lithography process. The substrate position is determined along the X _W axis, the Y _W axis, and the Z _W axis. The rotation of the substrate can also be determined about the X-axis (α _W ), the Y-axis (β _W ) and the Z-axis (θ _W ). Similarly, the position of the template is determined along the X, Y and Z axes. The rotation of the template can also be determined about the X-axis (α _T ), the Y-axis (β _T ) and the Z-axis (θ _T ). In order to align the template with the substrate, the angles α, β and θ must be matched as well as the X, Y and Z coordinates.

Linear encoders can be used to determine the X-axis, Y-axis and Z-axis positions of the template and substrate. However, such encoders typically do not provide rotational information about these axes. In one embodiment, an interferometer may be used to determine the X-axis and Y-axis positions and rotation angles α, β, and θ of the template and substrate. An interferometer based position detection system is schematically shown in FIG. Interferometer system 4300 includes a first three axis laser interferometer 4310 and a second three axis laser interferometer 4320. Mirror 4330 and mirror 4335 are coupled to the substrate and / or template. Mirror 4330 and mirror 4335 are optically coupled to the first and second laser interferometers, respectively. Mirror 4330 is positioned on a portion of the template and / or substrate that is perpendicular to the side where mirror 4335 is disposed on the template and / or substrate. This determines approximately five motions at the same time as shown in FIG. The first laser interferometer 4310 will sense the position of the substrate and / or template along the X-axis and rotation angles β and θ. The second laser interferometer 4320 will sense the position of the substrate and / or template along the Y-axis and rotation angles α and β.

An embodiment of an interferometer based position detector 4400 for use in the imprint lithography system 3900 is shown in FIG. 44. Position detector 4400 is installed in a portion of the body of system 3900. For example, the position detector may be installed on the support 3930 of the body. In one embodiment, the interferometer is based on a laser. Either differential or absolute interferometers can be used. Two interferometers 4410 and 4415 are used to position the template. The other two interferometers 4420 and 4425 are used to position the substrate. In one embodiment, all interferometers are triaxial interferometers. With this interferometer arrangement, both the template and the substrate are moved by about five (eg, X and Y positions and α, β and θ rotations). Laser 4430 provides light for the interferometer. Light from the laser is directed through the optical component 4440 to the interferometers 4410, 4415, 4420, and 4425 (note: not all optical components are referenced). Optical components include beam splitters and mirror systems to direct light from the laser to the interferometer. Interferometer systems and suitable optical systems are commercially available from several sources.

In one embodiment, an air gauge 3135 may be coupled to the imprint head 3100 as shown in FIG. The air gauge 3135 is used to determine whether the substrate disposed on the motion stage is substantially parallel to the reference plane. As used herein, an "air gauge" is referred to as a device for measuring the pressure of an air stream directed towards the surface. When the substrate is placed below the outlet of the air gauge 3135, the distance the substrate is away from the outlet of the air gauge 3135 affects the pressure that the air gauge senses. In general, the further the substrate is from the air gauge, the smaller the pressure.

In such a configuration, the air gauge 3135 can be used to determine the difference in pressure resulting from the change in distance between the substrate surface and the air gauge. By moving the air gauge 3135 along the surface of the substrate, the air gauge determines the distance between the air gauge and the substrate surface at various measurement points. The planarity of the substrate relative to the air gauge is determined by comparing the distance between the air gauge and the substrate at various measurement points. The distance between the air gauge and at least three points on the substrate is used to determine if the substrate is smooth. If the distances are substantially the same, the substrate is considered smooth. The significant difference in measured distance between the substrate and the air gauge indicates a non-smooth relationship between the substrate and the air gauge. This non-smooth relationship can be caused by either the non-smoothness of the substrate or the inclination of the substrate. Prior to use, the inclination of the substrate is corrected to establish a smooth relationship between the substrate and the template. The template using the tip tilt stage is attached to the X Y stage. Suitable air gauges can be obtained from Senex Inc.

During use of the air gauge, the substrate or template is placed within the measurement range of the air gauge. Movement of the substrate toward the air gauge may be accomplished by either movement of the Z-axis movement of the imprint head or Z-axis movement of the motion stage.

In an imprint lithography process, the photocurable liquid is disposed on the surface of the substrate. The patterned template is in contact with the photocurable liquid and active light is applied to the photocurable liquid. "Active light" as used herein means light that can affect chemical change. Actinic light may include ultraviolet light (eg, light having a wavelength between about 200 nm and about 400 nm), actinic light, visible light, or infrared light. In general, any light wavelength that may affect chemical change can be classified as active. Chemical changes can take many forms. Chemical changes may include, but are not limited to, any chemical reaction that results in a polymerization or crosslinking reaction. In one embodiment, the activating light passes through the template before reaching the composition. In this way, the photocurable liquid is cured to form a structure complementary to the structure formed on the template.

In some embodiments, active light source 3500 is an ultraviolet light source capable of generating light having a wavelength between about 200 nm and about 400 nm. The active light source 3500 is optically coupled to the template as shown in FIG. In one embodiment, the active light source 3100 is located in proximity to the imprint head 3100. Imprint head 3100 includes a mirror 3121 shown in FIG. 4, which reflects light from an active light source into a patterned template. Light passes through an opening in the body of the imprint head 3100 and is reflected by the mirror 3121 and directed to 3700. In this way, the active light source emits a patterned template without being disposed within the imprint head 3100.

Most active light sources generate significant amounts of heat during use. If the active light source 3500 is too close to the imprint stream 3500, heat from the light source may radiate towards the body of the imprint system to increase the temperature of the body portion. Because many metals expand when heated, an increase in temperature of a portion of the body of the imprint system can inflate the body. This expansion can affect the accuracy of the imprint system when manufacturing sub-100nm shapes.

In one embodiment, the active light source is positioned at a sufficient distance from the body such that the system body is generated by the active light source 3500 by intervening air interposed between the active light source 3500 and the imprint head 3100. Keep away from heat. 14 shows an active light source 3500 optically coupled to the imprint head 3100. The active light source 3500 includes an optical system 3510 that projects light generated by the light source toward the imprint head 3100. Light passes from the optical system 3510 through the opening 3123 to the imprint head 3100. Thereafter, the light is reflected toward the template coupled to the imprint head 3110 by a mirror 3121 disposed in the imprint head (see FIG. 4). In this way, the light source is thermally insulated from the body. Suitable light sources can be obtained from OAI Inc. of Santa Clara, California.

One or more optical measurement devices may be coupled to the imprint head 3910 and / or the motion stage 3920. In general, an optical measuring device is any device that determines the position and / or orientation of a template with respect to a substrate.

Referring to Figure 14, an optical imaging system 3800 through a template is optically coupled to the imprint head. Optical imaging system 3800 includes an optical imaging device 3810 and an optical system 3820. In one embodiment, the optical imaging device 3810 is a CCD microscope. Optical imaging system 300 is optically coupled to the template through an imprint head. When the substrate is disposed under the patterned template, the optical imaging system 3800 is also optically coupled to the substrate. Optical imaging system 3800 is used to determine placement errors between the patterned template and the underlying substrate as described herein. In one embodiment, the mirror 3121 (shown in FIG. 4) may be moved within the imprint head. During the alignment or optical inspection process, the mirror 3121 is moved out of the optical path of the optical imaging system.

During use of the optical alignment device, the substrate or template is placed within the measurement range (eg, field of view) of the optical imaging system. The motion of the substrate towards the optical imaging system can be achieved by either the Z-axis motion of the imprint head or the Z-axis motion of the motion stage.

An additional optical imaging device is coupled to the imprint head to view the substrate within the off-axis position. Off-axis position is defined herein as a position that is not in the light path of the active light source. Off-axis optical imaging system 3830 is coupled to imprint head 3100 as shown in FIG. Off-axis optical imaging system 3830 includes an optical imaging device 3832 and an optical system 3834. In one embodiment, the optical imaging device 3810 is a CCD microscope. Off-axis imaging system 3830 is used to scan the substrate without having a template in the optical path. Off-axis optical imaging system 3830 can be used for off-axis alignment processes as described herein. In addition, off-axis optical imaging system 3830 is used to perform rough alignment of the template with the substrate, while optical imaging system 3800 through the template is used to fine align the template with the substrate. An additional off-axis optical system may be coupled to the imprint head 3100. 12 illustrates an additional off-axis optical system 3840 coupled to imprint head 3100.

The additional optical imaging device may be coupled to the motion stage to observe the template. Template optical imaging system 3850 is coupled to motion stage 3600 as shown in FIG. Template optical imaging system 3850 includes an optical imaging device 3852 and an optical system 3854. In one embodiment, the optical imaging device 3852 is a CCD microscope. Template optical imaging system 3850 is used to scan the surface of the template without scanning through the bulk of the template. Template optical imaging system 3830 can be used for off-axis alignment processes as described herein.

It is to be understood that the optical imaging system may be deployed in alternative system embodiments described herein. For example, in an alternative system embodiment, the optical imaging system can be coupled to a motion stage configured to move the imprint head. In such an embodiment, the substrate is mounted to a substrate support that also includes an optical imaging device.

As described above, the photocurable liquid is disposed on the substrate and the template is brought into contact with the liquid during the imprint lithography process. The curable liquid is a low viscosity liquid monomer solution. Suitable solutions may have a viscosity ranging from about 0.01 cps to about 100 cps (measured at 25 ° C.). Low viscosity is particularly desirable for high resolution (eg, sub-100 nm) structures. Low viscosity also closes the gap more quickly. In addition, the low viscosity fills the liquid faster in the gap area at low pressure. In particular, at a sub-50 nm regime, the viscosity of the solution should be about 30 cps or lower, or more preferably less than about 5 cps (measured at 25 ° C.).

Many problems with other lithography techniques can be solved by using low viscosity photocurable liquids in imprint lithography processes. Patterning of low viscosity photocurable liquids solves all the problems encountered in hot embossing technology by using low viscosity photo-sensitive liquids. In addition, the use of thick, robust, and transparent templates makes interlayer alignment easier. The rigid template is generally transparent to both liquid actinic light and alignment mark measurement light.

The curable liquid may be made of various polymerizable materials. In general, any photopolymerizable material may be used. The photopolymerizable material may comprise a mixture of monomers and photoinitiators. In some embodiments, the curable liquid may include one or more commercially available negative photoresist materials. The viscosity of the photoresist material can be reduced by diluting the liquid photoresist with a suitable solvent.

In one embodiment, suitable curable materials include monomers, silylated monomers, and initiators. Crosslinking agents and dimethyl siloxane derivatives may also be included. Monomers include, but are not limited to, acrylate and methacrylate monomers. Examples of monomers include, but are not limited to, butyl acrylate, methyl acrylate, methyl methacrylate, or mixtures thereof. The monomers consist of 25-50% by weight of the curable liquid. The monomers are believed to ensure proper solubility of the photoinitiator in the curable liquid. It is also believed that the monomer provides adhesion to the underlying organic transport layer when used.

Curable liquids may also include silylated monomers. The silylated monomers are generally polymeric compounds comprising silicon groups. Classification of silylated monomers includes, but is not limited to, silane acrylyl and silane methacrylyl derivatives. Specific examples include methacryloxypropyl tris (tri-methylsiloxy) silane and (3-acryloxypropyl) tris (tri-methoxyoxyoxy) -silane. The silylated monomers may be provided in amounts of 25 to 50 weight percent. Curable liquids may also include dimethyl siloxane derivatives. Examples of dimethyl siloxane derivatives include, but are not limited to, methylsiloxane dimethylsiloxane copolymers, acryloxypropyl methylsiloxane homopolymers, and acryloxy terminated polydimethylsiloxanes. Dimethyl siloxane derivative is provided in an amount of about 0 to 50% by weight. The silylated monomers and dimethyl siloxane derivatives can impart high oxygen etch resistance to the cured liquid. In addition, the silylated monomers and dimethyl siloxane derivatives are believed to increase the ability to reduce the surface energy of the cured liquid to allow the template to be released from the surface. Both the silylated monomers and dimethyl siloxane derivatives listed herein are commercially available from Gelest Inc.

Any material capable of initiating a free radical reaction can be used as the initiator. For active light curing of the curable material, the initiator is preferably a photoinitiator. Examples of initiators include alpha-hydroxyketones (eg 1-hydroxycyclohexyl phenyl ketone, sold as Ciba-Geigy Specialty Chemical Division as Irgacure 184) and acrylphosphine oxide initiators (eg Ciba- Phenylbis (2,4,6-trimethyl benzol) phosphine oxide, sold as Geigy Specialty Chemical Division as Irgacure 819), but is not limited thereto.

The curable liquid may also include a crosslinking agent. Crosslinkers are monomers comprising two or more polymerizable groups. In one embodiment, multifunctional siloxane derivatives can be used as crosslinking agents. As an example of a multifunctional siloxane derivative, 1, 3-bis (3-methacryloxypropyl)-tetramethyl disiloxane is mentioned.

In one embodiment, the curable liquid may comprise a mixture of 50% by weight of n-butyl acrylate and 50% of (3-acryloxypropyl) tris-trimethylsiloxane-silane. To this mixture can be added 3% by weight of a mixture of 1: 1 Irgacure 819 and Irgacure 184 and 5% of the crosslinker 1,3-bis (3-methacryloxypropyl) -tetramethyl disiloxane. The viscosity of this mixture is less than 30 cps measured at about 25 ° C.

In alternative embodiments, the curable liquid may be formed of monomers, acid-generating photo-agents and base-generating photo-agents. Examples of monomers include, but are not limited to, phenolic polymers and epoxy resins. Acid-generating photo-agents are compounds that emit an acid when treated with actinic light. This generated acid accelerates the polymerization of the monomers. Such acid-generating additives are known to those skilled in the art, and the particular acid-generating additive used depends on the monomer and the desired curing conditions. In general, the acid-neutral additive is selected in some embodiments to be sensitive to radiation of one wavelength (λ ₁ ) in the visible or near ultraviolet (near UV) range. For example, in some implementations, the first wavelength λ ₁ is selected to be nearly 400 nm or longer. Base-generating photoagents are also added to the monomers. The base-generating photoagent prevents the monomer from curing near the interface of the template. The base-generating photo-agent is inactive or substantially inactive with respect to radiation of the first wavelength λ ₁ , but may be sensitive to radiation of the second wavelength λ ₂ . In addition, the second wavelength λ ₂ should be chosen so that the radiation of the second wavelength is mainly absorbed near the monomer surface at the interface with the template and does not penetrate very far into the curable liquid. For example, in some embodiments, base generating additives may be used that are sensitive to radiation having a wavelength λ ₂ in the deep UV range, ie, radiation having a wavelength in the range of about 190-280 nm.

According to one embodiment, a curable liquid comprising monomers, acid-generating photo-agents and base-generating photo-agents is deposited onto a substrate. The template is in contact with the curable liquid. Thereafter, the curable liquid is exposed to the radiation at the first wavelength λ ₁ and the second wavelength λ _{2 of} light almost simultaneously. Alternatively, the curable liquid may be exposed to radiation of the second wavelength λ ₂ , followed by radiation of the first wavelength λ ₁ . Exposure of the curable liquid to radiation of the second wavelength [lambda] ₂ generates excessive base near the interface with the template. This excess base acts to neutralize the acid generated by exposure of the curable liquid to radiation of the first wavelength λ ₁ , thereby preventing the acid from curing the curable liquid. If the radiation of the second wavelength λ ₂ has a depth that penetrates shallowly into the curable liquid, only the base generated by this radiation prevents the curable liquid from curing at or near the interface with the template. The remainder of the curable liquid is cured by exposure to longer wavelength radiation λ _{1 that} penetrates throughout the curable liquid. This process is described in further detail in US Pat. No. 6,218,316, entitled "Planarization of Non-Planar Surfaces in Device Fabrication".

In another embodiment, the curable liquid includes a photosensitizer, which is decomposed when exposed to deep UV radiation, for example, hydrogen (H ₂ ), nitrogen (N ₂ ), nitrous oxide (N ₂ O). One or more gases such as sulfur trioxide (SO ₃ ), acetylene (C ₂ H ₂ ), carbon dioxide (CO ₂ ), ammonia (NH ₃ ) or methane (CH ₄ ). Radiation of the first wavelength λ ₁ , such as visible or near UV, may be used to cure the curable liquid, and deep UV radiation λ ₂ may be used to generate one or more of the gases described above. Generation of gas generates local pressure near the interface between the cured liquid and the template, facilitating separation of the template from the cured liquid. This process is described in additional detail in US Pat. No. 6,218,316, referenced herein.

In another embodiment, the curable liquid may be comprised of monomers that are cured to form a polymer that can be degraded by exposure to light. In one embodiment, a polymer with a double substituted carbon backbone is deposited on the substrate. After the template is in contact with the curable liquid, the curable liquid is exposed to a second wavelength λ ₂ in the radiation and deep UV range of the first wavelength λ ₁ (eg, greater than 400 nm). The radiation of the first wavelength acts to cure the curable liquid. When the curable liquid is exposed to the second wavelength λ ₂ , cleavage occurs at the substituted carbon atoms. Since deep UV radiation does not penetrate deep into the curable liquid, the polymer decomposes only near the interface with the template. Promote the separation of the degraded surface of the cured liquid from the template. Other functional groups that promote the photo-degradability of the polymer can also be used. US Pat. No. 6,218,316, referenced herein, discloses this process in additional detail.

In various embodiments, the imprint lithography template may include optical lithography, electron beam lithography, ion beam lithography, x-ray lithography, ultraviolet lithography, scanning probe lithography, focused ion beam milling, interferometric lithography, epitaxial growth And thin film deposition, chemical etch, plasma etch, ion milling, reactive ion etch or combinations thereof. A method of manufacturing a patterned template is described herein and disclosed in US Patent Application No. 10 / 136,138, entitled "Methods of Manufacturing a Lithography Template," filed on May 1, 2002 by Voison.

In one embodiment, the imprint lithography template is substantially transparent to actinic light. The template includes a body with a lower surface. The template also includes a plurality of recesses on the bottom surface extending towards the top surface of the body. At least a portion of this recess has a shape size smaller than about 250 nm, but this recess may be of any suitable size.

For an imprint lithography process, the durability of the template and the release characteristics of the template can be important. In one embodiment, the template is formed of quartz. To form the template, other materials can be used, including but not limited to silicon germanium carbon, gallium nitride, silicon germanium, sapphire, gallium arsenide, epitaxial silicon, polysilicon, gate oxide, silicon dioxide, or combinations thereof. have. The template can also be used to form a detectable shape, such as alignment markings. For example, the detectable shape may be formed of SiO _X , where X is less than two. In some embodiments, X is about 1.5. In yet another embodiment, the detectable form may be formed of molybdenum silicide. SiO _X and molybdenum silicide are optically transmissive to the light used to cure the polymerizable liquid. However, the two materials are substantially impermeable to visible light. Using these materials, alignment marks are created on the template that do not prevent the underlying substrate from curing.

As mentioned above, the template is treated with a surface treatment material to form a thin layer on the template surface. The surface treatment process is optimized to produce a low surface energy coating. Such a coating is used to prepare an imprint template for imprint lithography. Treated templates have desirable release properties for untreated templates. The treated template surface has a surface free energy of at least about 65 dynes / cm. The treatment procedures described herein create a surface treatment layer that exhibits a high level of durability. The durability of the surface treatment layer allows the template to be used for numerous imprints without replacing the surface treatment layer. In some embodiments, the surface treatment layer reduces the surface free energy of the lower surface measured at 25 ° C. to less than about 40 dynes / cm or in some cases to less than about 20 dynes / cm.

In one embodiment, the surface treatment layer is formed from the reaction output of water with an alkylsilane, fluoroalkylsilane or fluoroalkyltrichlorosilane. This reaction forms a silicided coating layer on the surface of the patterned template. For example, the silinated surface treatment layer is formed from the reaction output of water and tridecafluoro-1,1,2,2-tetrahydrooctyl trichlorosilane. The surface treatment layer is formed through either a liquid phase process or a gas phase process. In the liquid phase process, the substrate is immersed in a solution or solvent of a precursor. In the gas phase process, the precursor is delivered through an inert carrier gas. It may be difficult to obtain a solvent of pure anhydride for use in liquid treatment. During the process, the bulk phase of the water may deposit into a clump, which adversely affects the final quality or coverage of the coating. In an embodiment of the gas phase process, the template is placed in a vacuum chamber, which is then cycle-purged to remove excess water. However, some absorbed water still remains on the surface of the template. However, small amounts of water are believed to be needed to initiate the surface reactions that form the coating. This reaction can be explained by the following equation.

R-SiCl ₃ + 3H ₂ O => R-Si (OH) ₃ + 3HCl

To facilitate the reaction, the template is brought to the desired reaction temperature via a temperature control chuck. Thereafter, the precursor is supplied to the reaction chamber for a predetermined time. Reaction parameters such as template temperature, precursor concentration, flow geometries and the like are tailored to the specific precursor and template substrate combination. By controlling these conditions, the thickness of the surface treatment layer is controlled. The thickness of the surface treatment layer is kept at a minimum value, minimizing interference of the surface treatment layer with the shape size. In one embodiment, a monolayer of the surface treatment layer is formed.

In one embodiment, there are at least two separate depths associated with the recesses on the bottom surface of the template. 20A and 20B show top and cross-section, respectively, of a patterned template with two depth recesses. 20A and 20B, the template includes one or more patterning areas 401. In such an embodiment, the first relatively shallow depth is associated with a recess in the patterning area of the template as shown in FIG. 20B. The patterning area includes an area that is duplicated during patterning of the template. The patterning area is located within the area defined by the edge 407 of the template. Outer region 409 is defined as the region extending from the outer edge of any of the patterning areas to the edge of the template. The outer region has a depth substantially greater than the depth of the recess in the patterning area. Here, the periphery of the template is defined by the patterning area defined by the outer area 409. As shown in Fig. 20A, four patterning areas are located within an area defined by a template. This patterning area is separated from the edge 407 of the template by the outer area 409. The "periphery" of the template is defined by the edges 403a, 403b, 403c, 403d, 403e, 403f, 403g, and 403h of the patterning area.

The patterning areas may be separated from each other by the boundary regions 405. The boundary area is a recess located between the patterning areas having a depth greater than that of the patterning area. As described below, the two boundary regions and the outer region prevent liquid from flowing between the patterning regions or beyond the perimeter of the patterning area.

The design of the template is chosen depending on the type of lithography process used. For example, templates for positive imprint lithography are designed to form discrete films on a substrate. In one embodiment, as shown in Figure 15, the template 12 is formed such that the depth of one or more structures is relatively large compared to the depth of the structure used to form the patterning area. In use, the template 12 is disposed spaced apart from the substrate 20 as desired. In such an embodiment, the gap h ₁ between the lower surface 536 of the template 12 and the substrate 20 is much smaller than the gap h ₂ between the recessed surface 534 and the substrate 20. For example, h ₁ may be less than about 200 nm, while h ₂ may be greater than about 10,000 nm. When the template is in contact with the liquid 40 on the substrate 20, the liquid 40 is released in the area below the recessed surface 534 (as shown in FIG. 16) and the lower surface 536 and the substrate. Fill the gap between the 20. It is believed that the combination of surface energy and capillary forces lead the liquid from the larger recess to the narrower region. When h ₁ is reduced, the force exerted by the template 12 on the liquid may exceed the capillary force that draws the liquid below the lower surface 536. These forces diffuse liquid into the area below the recessed surface 534. The minimum value of h ₁ that prevents the liquid from diffusing into the recess 532 is referred to herein as the "minimum film thickness." In addition, when h ₁ is increased, the capillary force decreases, eventually spreading the liquid into the deeper recessed area. The maximum value of h ₁ at which the capillary force is sufficient to prevent liquid from flowing into the deeper recessed area is known herein as the “maximum film thickness”.

As shown in FIGS. 17 and 18, in various embodiments, the template 12 is formed to prevent the curable liquid disposed on the substrate 20 from flowing beyond the perimeter 412 of the template 12. . In the embodiment shown in FIG. 17, the height h ₁ is measured from the substrate 20 to the shallow recessed surface. The shallow recessed surface 552 extends around the template 12. Thus, the edge of the template forms a height h ₂ and is virtually infinite compared to the height h ₁ . In the embodiment shown in Figure 18, a deep recess is formed in the outer edge of the template 12. The height h ₂ is measured between the substrate 20 and the deep recessed surface 554. The height h ₁ is measured again between the substrate 20 and the shallow recessed surface 552. In one embodiment, the height h ₂ is much greater than the height h ₁ . If h ₁ is sufficiently small, the active photocurable liquid is maintained in the gap between the template 12 and the substrate 20 while the curing agent is applied. Deeply recessed portions are particularly useful for confining liquids in the step and repeat processes described herein.

In one embodiment, template 12 and substrate 20 each have one or more alignment marks. The alignment mark can be used to align the template 12 and the substrate 20. For example, one or more optical imaging devices (eg, microscopes, cameras, imaging arrays, etc.) are used to determine the alignment of alignment marks.

In some embodiments, the alignment mark on the template may be substantially transmissive for actinic light. Alternatively, the alignment mark is substantially impermeable to the alignment mark detection light. As used herein, alignment mark detection light and light used for other measurement and analysis is referred to as "analysis light". In one embodiment, the analysis light includes, but is not limited to, visible light and / or infrared light. The alignment mark may be formed of a material different from that of the body. For example, the alignment mark can be formed from SiO _x , where x is about 1.5. In another example, the alignment mark may be formed of molybdenum silicide. Alternatively, the alignment mark may include a number of lines etched on the surface of the body. This line is substantially configured to diffuse actinic light, but generates an analytable mark under the analysis light.

In various embodiments, one or more deep recesses as described above completely protrude through the template body to form openings in the template. The advantage of such openings is that they substantially increase the height h ₂ compared to the height h ₁ at each opening. In addition, in some embodiments, pressurized gas or vacuum may be applied to the opening. Pressurized gas or vacuum may also be applied to one or more openings after curing the liquid. For example, pressurized gas is applied after curing according to part of the peel and pull process, to help separate the template from the cured liquid.

In one embodiment, one or more alignment marks may be formed in the patterned template. As described herein, alignment marks formed on the template can be used to align the template with the patterned area on the substrate. One embodiment of a template including alignment marks is shown in FIG. Patterned template 4500 includes patterned area 4510, alignment mark 4520, and alignment mark patterning area 4530. Alignment mark 4520 is separated from patterning areas 4510 and 4512 by boundaries 4540 and 4542. The boundaries 4540 and 4542 have a depth substantially greater than the depth of the alignment marks. When the template 4500 is in contact with the active photocurable liquid 4560, the liquid diffuses into the patterning areas 4510 and 4512, but is diffused into the alignment mark 4520 area by the boundary as shown in FIG. 45. Is prevented.

Preventing the active photocurable liquid from entering the alignment area can provide an advantage when making alignment measurements. During a typical alignment procedure, optical measurements are made through the template to underlying substrate alignment marks (eg, alignment marks 4550) to determine whether the alignment marks are aligned. The presence of liquid between the template and the substrate during the alignment measurement can interfere with the optical measurement. Typically, the refractive index of the liquid is substantially similar to the template material. By preventing liquid from entering the alignment area, the optical alignment technique can be simplified and the optical requirements of the alignment system can be reduced.

When a template is used to imprint one of a plurality of layers to be formed on a substrate, it is useful for the template to include an alignment patterning area as well as an alignment mark for alignment with the underlying substrate. As shown in FIG. 10, alignment mark patterning area 4530 is in contact with a portion of the applied active photocurable liquid. During curing, the alignment marks defined by alignment mark patterning area 4530 are imprinted into the cured layer. During the next process, alignment marks formed from alignment mark patterning area 4530 may be used to support alignment of the substrate with the template.

The imprint lithography system described above may be modified in accordance with alternative embodiments described below. It should be understood that any of the alternative embodiments described may be combined with any other system described herein, alone or in combination.

As mentioned above, the imprint head includes a micro-orientation system for "passive" orientation of the template with respect to the substrate. In yet another embodiment, the micro-orientation system can include an actuator coupled to the flex arm. The actuator "actively" controls the micro orientation system. In use, an operator or programmable controller monitors the orientation of the template with respect to the substrate. The operator or programmable controller then changes the orientation of the template relative to the substrate by operating the actuator. Movement of the actuator moves the flexing arm to change the orientation of the template. In this way, "active" control for fine positioning of the template with respect to the substrate can be achieved. Active micro-orientation systems are also disclosed in US Patent Application 09 / 920,341, entitled "Methods for High-Precision Gap Orientation Sensing Between a Transparent Template and Substrate for Imprint Lithography," filed August 1, 2001. This patent is incorporated herein by reference.

In alternative embodiments, the imprint head may include a pre-calibration system as described above. The pre-calibration system includes a bend ring 3124 as shown in FIG. Instead of the micro-orientation system as described above, template support system 3125 is coupled to the pre-calibration ring. In contrast to the microorientation system, the template support system 3125 is formed of substantially rigid and non-compliant members 3127. These members substantially firmly support the template 3700 disposed on the template support 3130. In this embodiment, fine orientation can be achieved using a motion stage instead of a template support.

In the above embodiments, the imprint head 3100 is coupled to the body in a fixed position. In alternative embodiments, the imprint head 3100 may be installed in a motion system that moves the imprint head 3100 along the X-Y plane as shown in FIG. Imprint head 3100 is configured to support a patterned template as described in any of the embodiments herein. Imprint head 3100 is coupled to a motion system that includes an imprint head chuck 3121 and an imprint motion stage 3123. The imprint head 3100 is installed in the imprint head chuck 3121. The imprint head chuck interacts with the imprint motion stage 3123 to move the imprint head along the X-Y plane. Mechanical or electromagnetic motion systems can be used. Electromagnetic systems use magnets to move the imprint chuck X-Y two-dimensionally. In general, electromagnetic systems integrate permanent and electromagnetic magnets into the imprint motion stage 3123 and the imprint head chuck 3121. The attractive forces of these magnets are overcome by an air cushion between the imprint head chuck 3121 and the imprint head motion stage 3123 to generate an "air bearing". The imprint head chuck and the imprint head are moved along the X-Y plane on the air cushion. The electromagnetic X-Y motion stage is disclosed in more detail in US Pat. No. 6,389,702, entitled "Method and Apparatus for Motion Control," referred to herein. In a mechanical motion system, an imprint head chuck is attached to the motion stage. The motion stage is then moved by the use of various mechanical means to change the position of the imprint head chuck to change the imprint head along the X-Y plane. In this embodiment, the imprint head may comprise a passive compliant microdirectional system, an activated microdirectional system or a rigid template support system as described herein.

Due to the imprint head 3100 coupled to the moving support, the substrate can be installed on a fixed support. Thus, in an alternative embodiment, the imprint head 3100 is coupled to the X-Y axis motion stage as described herein. The substrate is installed in a substantially stationary substrate support. The stationary substrate support is shown in FIG. The fixed substrate support 3640 includes a base 3642 and a substrate chuck 3644. Substrate chuck 3644 is configured to support the substrate during an imprint lithography process. The substrate chuck uses any suitable means to hold the substrate to the substrate chuck. In one embodiment, substrate chuck 3644 may include a vacuum system that applies a vacuum to the substrate to couple the substrate to the substrate chuck. The substrate chuck 3644 is coupled to the base 3638. The base is coupled to the support 3920 of the imprint lithography system (FIG. 1). In use, the stationary substrate support 3640 is held in a fixed position on the support 3920 while the imprint head position is varied to access other portions of the substrate.

Coupling the imprint head to the motion stage provides an advantage over the technique of placing the substrate on the motion stage. In general, the motion stage substantially frictionally moves the motion stage, depending on the air bearing. In general, the motion stage is not designed to accommodate the significant pressure exerted along the Z-axis. When pressure is applied to the motion stage chuck along the Z-axis, the motion stage chuck position will change somewhat in response to this pressure. During the step and repeat process, a template having an area smaller than the area of the substrate is used to form a number of imprinted areas. This substrate motion stage is relatively large compared to the template to accommodate larger substrates. When the template contacts the substrate motion stage at an off-center position, the motion stage is tilted to accommodate the increased pressure. This tilt is compensated for by tilting the imprint head to ensure proper alignment. However, once the imprint head is coupled to the motion stage, all forces along the Z-axis will be centered on the template, regardless of whether imprinting occurs on the substrate. This can increase the ease of alignment and also increase the throughput of the system.

In one embodiment, the substrate tilt module may be formed in a substrate support as shown in FIG. The substrate support 3650 includes a substrate chuck 3652 coupled to the substrate tilt module 3654. The substrate tilt module 3654 is coupled to the base 3656. In one embodiment, base 3656 is coupled to a motion stage that X-Y moves the substrate support. Alternatively, base 3656 may be coupled to a support (eg, 3920) such that the substrate support is installed in the imprint system in a fixed position.

The substrate chuck 3652 supports the substrate to the substrate chuck using any suitable means. In one embodiment, substrate chuck 3654 may include a vacuum system that applies a vacuum to the substrate to couple the substrate to the substrate chuck. The substrate tilt module 3654 includes a flex ring 3658 coupled to the flex ring support 3660. Multiple actuators 3662 are coupled to flex ring 3658 and flex ring support 3660. Actuator 3662 is operative to change the inclination of flexure ring 3658. In one embodiment, the actuator uses a differential gear mechanism that can be operated manually or automatically. In an alternative embodiment, the actuator uses an eccentric roller mechanism. Eccentric roller mechanisms generally provide greater vertical rigidity to the substrate support than differential gear systems. In one embodiment, the substrate tilt module has a template of about 1 lb. To about 10 lbs. It has rigidity that prevents the inclination of the substrate when applying the liver force to the liquid disposed on the substrate. In particular, the substrate tilt module is configured to tilt only 5 micro radians when a pressure of up to 10 lbs. Is applied to the substrate through the liquid on the template.

In use, a sensor coupled to the substrate chuck can be used to determine the inclination of the substrate. The inclination of the substrate is adjusted by the actuator 3662. In this way, tilt correction of the substrate can be achieved.

The substrate tilt module may also include a micro orientation system. A substrate support including a micro orientation system is shown in FIG. To achieve fine directional control, bend ring 3658 includes a central recess in which substrate chuck 3652 is disposed. The depth of the central recess is such that the upper surface of the substrate disposed on the substrate chuck 3652 is substantially flush with the upper surface of the bend ring 3658. Fine orientation can be accomplished using the actuator 3662. Fine orientation is achieved by using actuators that can control motion in the nanometer range. Alternatively, fine orientation can be accomplished in a manual manner. The actuator can be made substantially compliant. When the template is in contact with a liquid disposed on the substrate surface, the compliance of the actuator can cause the substrate to self-correct the gradient change. By placing the substrate at a position substantially at the same height as the bend ring, fine orientation can be achieved at the substrate-liquid interface in use. Thus, the compliance of the actuator is transferred to the upper surface of the substrate to make fine orientation measurements on the substrate.

The system described above generally consists of a system for dispensing an actinic curable liquid onto a substrate and bringing the substrate and template close to each other. However, it should be understood that the system described above can be modified such that the actinic curable liquid is applied to the template rather than the substrate. In such an embodiment, the template is disposed below the substrate. FIG. 41 is a schematic illustration of an embodiment of a system 4100 configured such that a template is positioned below a substrate. System 4100 includes an imprint head 4110 and a substrate support 4120 positioned over the imprint head 4110. The imprint head is configured to support the template 3700. The imprint head is similar in design to any of the imprint heads described herein. For example, the imprint head 4110 can include a micro orientation system as described herein. The imprint head is coupled to the imprint head support 4130. The imprint head may be engaged in a fixed position and may remain substantially unmoved during use. Alternatively, the imprint head may be placed on a motion stage that moves in X-Y two dimensions of the imprint head 4130 during use.

The substrate to be imprinted is installed onto the substrate support 4120. Substrate support 4120 is designed similar to any of the substrate supports described herein. For example, substrate support 4120 may comprise a micro orientation system as described herein. Substrate support 4120 may be coupled to support 4140 in a fixed position and may remain substantially unmoved during use. Alternatively, substrate support 4120 may be disposed on a motion stage that moves X-Y two-dimensionally of the substrate support during use.

In use, the active light curable liquid is disposed on a template 3700 disposed in the imprint head. The template can be patterned or smoothed depending on the type of operation to be performed. The patterned template can be configured for use in an imprint lithography system in combination with definitions, negatives, or definitions as described herein.

A typical imprint lithography process is shown in FIGS. 23A-23F. As shown in FIG. 23A, the template 12 is positioned spaced apart from the substrate 20, thereby forming a gap between the template 12 and the substrate 20. As shown in FIG. Template 12 includes a surface defining one or more desired shapes, which shapes can be transferred to substrate 20 during patterning. As used herein, "shape size" generally relates to the width, length and / or depth of one of the desired shapes. In various embodiments, the shapes described may be defined on the surface of the template 12 as recesses and / or conductive patterns formed on the surface of the template. The surface 14 of the template 12 may be treated with a thin layer 13 that lowers template surface energy and supports separation of the template 20 from the substrate 20. Surface treatment layers for templates are described herein.

In one embodiment, material 40 may be dispensed onto substrate 20 prior to moving template 12 into a desired position relative to substrate 20. Material 40 may be a curable liquid that matches the shape of the desired shape of template 12. In one embodiment, material 40 is a low viscosity liquid that at least partially fills the space in gap 31 without using high temperature. Low viscosity liquids can also close the gap between the template and the substrate without requiring high pressure. As used herein, the term "low viscosity liquid" refers to a liquid having a viscosity of less than about 30 cps measured at about 25 ° C. Additional details regarding the appropriate choice of materials are described below. The template 12 interacts with the curable liquid 40 to match the liquid to the desired shape. For example, the curable liquid 40 may match the shape of the template 12 as shown in FIG. 23B. The position of the template 12 can be adjusted to create the desired gap distance between the template and the substrate 20. The position of the template 12 can also be adjusted to properly align the template with the substrate.

After the template is properly positioned, material 40 is cured to form masking layer 42 on the substrate. In one embodiment, material 40 is cured using actinic light 32 to form masking layer 42. The application of actinic light through the template 12 to cure the liquid is shown in FIG. 23C. After the liquid has substantially cured, the template 12 is removed from the masking layer 42, leaving a cured masking layer on the surface of the substrate as shown in Figure 23D. Masking layer 42 has a pattern that is complementary to the pattern of template 12. Masking layer 42 may include a "base layer" (also referred to as a "residual layer") between one or more desired shapes. By separating the template 12 from the masking layer 42, the desired mold remains intact without shearing or tearing from the surface of the substrate 20. Additional details regarding the imprinting and then detachment of the template 12 from the substrate 20 are described below.

Masking layer 42 may be used in a variety of ways. For example, in some embodiments, masking layer 42 may be a functional layer. In such embodiments, the curable liquid 40 may be cured to form a conductive layer, a semiconducting layer, a dielectric layer and / or a layer having desired mechanical or optical properties. In another embodiment, masking layer 42 may be used to cover a portion of substrate 20 during further processing of substrate 20. For example, masking layer 42 is used during the material deposition process to prevent material from being deposited on any part of the substrate. Similarly, masking layer 42 may be used as a mask for etching substrate 20. In order to simplify the additional description of the masking layer 42, it will be described in the embodiments described below only for use as a mask for the etching process. However, it will be appreciated that the masking layer of the embodiments described herein can be used in a variety of processes as described above.

For use in the etch process, as shown in FIG. 23, the masking layer 42 may be etched using the etch process until the substrate portion is exposed through the masking layer 42. That is, portions of the base layer can be etched away. Portions of the masking layer 42 are retained on the substrate 20 and used to prevent portions of the substrate 20 from being etched. After etching of the masking layer 42 is completed, the substrate 20 may be etched using a known etching process. The portion of the substrate 20 disposed below the portion of the masking layer 42 may remain substantially unetched, while the exposed portion of the substrate 20 is etched. In this way, a pattern corresponding to the pattern of the template 12 can be transferred to the substrate 20. The remaining portion of masking layer 42 is removed, leaving the patterned substrate 20 as shown in FIG. 23F.

24A-24D illustrate one embodiment of an imprint lithography process using a transport layer. The transport layer 18 may be formed on the upper surface of the substrate 20. The transport layer 18 may be formed from a masking layer formed from a material and / or curable liquid 40 having an etch characteristic different from the underlying substrate 20. That is, the etching layer (eg, carrier layer 18, masking layer and / or substrate 20) may be selectively etched at least to some extent with respect to the other layers.

Masking layer 44 is formed on the surface of carrier layer 18 by depositing a curable liquid on the surface of carrier layer 18 and curing the masking layer, as described in connection with FIGS. 23A-23C. Masking layer 42 may be used as a mask to etch carrier layer 18. As shown in FIG. 24B, the masking layer 42 is exposed using an etch process until a portion of the transport layer 18 is exposed through the masking layer 42. Portion 44 of masking layer 42 may remain on carrier layer 18 and may be used to prevent portions of the carrier layer from being etched. After etching of the masking layer 42 is completed, the carrier layer 18 may be etched using a known etching process. The portion of the carrier layer 18 disposed below the portion 44 of the masking layer 42 may remain substantially unetched, while the exposed portion of the carrier layer 18 is etched. In this way, the pattern of masking layer 42 is replicated in the transport layer 18.

In Figure 24C, both the etched portion and portion 44 of the transport layer 18 form a masking stack 46, which may be used to prevent the portion of the underlying substrate 20 from being etched. . Etching of the substrate 20 may be performed using known etch processes (eg, plasma etching processes, reactive ion etching processes, etc.). As shown in Figure 24D, the masking stack can prevent etching of the underlying portion of the substrate 20. As shown in FIG. Etching of the exposed portion of the substrate 20 may continue until a predetermined depth is reached. The advantage of using a masking stack as a mask for etching the substrate 20 is that the combined stack of layers can produce a high aspect ratio mask (ie, a mask having a height greater than width). High aspect ratio masking layers are preferred during the etching process to prevent undercut of the mask portion.

The processes shown in Figures 23A-23F and 24A-24D are examples of negative imprint lithography processes. As used herein, a "partial imprint lithography process" is generally referred to as a process that substantially matches the shape of the template prior to curing the curable liquid. That is, the negative image of the template is formed in the cured liquid. As shown in these figures, the unrecessed portion of the template becomes the recessed portion of the mask layer. Therefore, the template is designed to have a pattern that displays a negative image of the pattern to be provided to the mask layer.

As used herein, a "definition imprint lithography" process is generally referred to as a process that causes a pattern formed in the mask layer to be a mirror image of the pattern of the template. As described further below, the unrecessed portion of the template becomes the unrecessed portion of the mask layer.

A typical positive imprint lithography process is shown in Figures 25A-25D. As shown in FIG. 25A, the template 12 is positioned spaced apart from the substrate 20, thereby forming a gap between the template 12 and the substrate 20. The surface of the template 12 may be treated with a thin surface treatment layer 1 that reduces the template surface energy and supports the separation of the template 12 from the hardened masking layer.

The curable liquid 40 is disposed on the surface of the substrate 20. The template 12 is in contact with the curable liquid 40. As shown in Figure 25B, the curable liquid fills the gap between the lower surface of the template and the substrate. In contrast to the negative imprint lithography process, the curable liquid 40 is substantially absent in the region of the substrate immediately below at least a portion of the recess of the template. Thus, the curable liquid 40 is retained as a discontinuous film on the substrate defined by the position of at least a portion of the recess of the template 12. After the template 12 is properly positioned, the curable liquid 40 is cured to form a masking layer 42 on the substrate. The template 12 is removed from the masking layer 42, leaving a cured masking layer on the surface of the substrate, as shown in Figure 25C. Masking layer 42 has a pattern that is complementary to the pattern of template 12.

Masking layer 42 may be used to prevent portions of substrate 20 from being etched. After formation of the masking layer 42 is complete, the substrate 20 may be etched using a known etching process. As shown in Figure 25D, the portion of the substrate 20 disposed under the masking layer 42 remains substantially unetched, while the exposed portion of the substrate 20 is etched. In this way, the pattern of the template 12 can be duplicated in the substrate 20. The remaining portion 44 of the masking layer 42 is removed to create a patterned substrate 20.

26A-26C illustrate one embodiment of a positive imprint lithography process using a transport layer. The transport layer 18 may be formed on the upper surface of the substrate 20. The transport layer 18 is formed from a material having an etch characteristic different from the underlying transport layer 18 and / or the substrate 20. As described with reference to FIGS. 25A-25C, a masking layer 42 is formed on the surface of the transport layer 18 by depositing a curable liquid on the surface of the transport layer 18 and curing the masking layer.

Masking layer 42 may be used as a mask for etching carrier layer 18. The masking layer 42 can prevent portions of the transport layer 18 from being etched. The transport layer 18 can be etched using known etching processes. The portion of the carrier layer 18 disposed below the masking layer 42 remains substantially unetched while the exposed portion of the carrier layer 18 is etched. In this way, the pattern of masking layer 42 can be replicated in the transport layer 18.

In FIG. 26B, both the etched portion and the masking layer 42 of the transport layer 18 form a masking stack 46, which may be used to prevent the portion of the underlying substrate 20 from being etched. have. Etching of the substrate 20 may be performed using known etch processes (eg, plasma etching processes, reactive ion etching processes, etc.). As shown in Figure 26C, the masking stack can prevent etching of the underlying portion of the substrate 20. As shown in FIG. Etching of the exposed portion of the substrate 20 may continue until a predetermined depth is reached.

In one embodiment, the process may combine positive and negative imprint lithography. The template for the combined positive and negative imprint lithography process may include a recess suitable for positive lithography and a recess suitable for negative lithography. For example, one embodiment of a template for combined positive and negative imprint lithography is shown in FIG. 27A. As shown in FIG. 27A, template 12 includes a bottom surface 566, one or more first recesses 562, and one or more second recesses 564. First recess 562 is configured to create a discontinuous portion of curable liquid 40 when the template contacts the curable liquid. The substantially greater than the height of the second recess (h ₁₎ the height of the first recesses (h _2).

A typical combined imprint lithography process is shown in Figures 27A-27D. As shown in FIG. 27A, the template 12 is positioned spaced apart from the substrate 20 to form a gap between the template 12 and the substrate 20. As shown in FIG. At least the bottom surface of the template 12 may be treated with a thin surface treatment layer (not shown) that lowers the template surface energy and supports the separation of the template 12 from the cured masking layer. In addition, the surfaces of the first recesses 562 and / or the second recesses 564 may be treated with a thin surface treatment layer.

Curable liquid 40 is disposed on the surface of the substrate. The template 12 is in contact with the curable liquid 40. As shown in FIG. 27B, the curable liquid fills the gap between the lower surface of the template 566 and the substrate 20. Curable liquid 40 also fills first recess 562. However, the curable liquid 40 is substantially absent in the region of the substrate immediately below the second recess 564. Thus, the curable liquid 40 is maintained as a discontinuous film on a substrate that includes a surface topology corresponding to the pattern formed by the first recess 562. After the template 12 is properly positioned, the curable liquid 40 is cured to form a masking layer 42 on the substrate. The template 12 is removed from the masking layer 42, leaving the cured masking layer on the surface of the substrate 20 as shown in FIG. 27C. Masking layer 42 may include an area 568 similar to a mask layer formed by negative imprint lithography. In addition, the mask layer 42 may include an area 569 that does not include any masking material.

In one embodiment, the mask layer 42 is made of a material having the same or similar etch rate as the underlying substrate. An etch process is applied to the masking layer 42 to remove the masking layer and the substrate with substantially the same etch rate. In this way, the multilayer pattern of the template can be transferred to the substrate as shown in FIG. 27D. This process can also be performed using a carrier layer as described in other embodiments.

Combinations of positive and negative lithography are also useful for patterning multiple regions of a template. For example, the substrate may include a number of areas that require patterning. As shown in Figure 27C, the template with multiple depth recesses includes two patterning regions 568 with intervening "boundary" regions 569. Boundary area 569 prevents liquid from flowing beyond the patterning area of the template.

As used herein, a "step and repeat" process involves forming a plurality of patterned regions on a substrate using a template smaller than the substrate. The step and repeat imprint process deposits a photocurable liquid on a portion of the substrate, aligns the pattern of the cured liquid with a prepattern on the substrate, impresses the template into the liquid, cures the liquid, and removes the template from the cured liquid. And separating. Separating the template to the substrate leaves an image of the topology of the template in the cured liquid. Since the template is smaller than the total surface area of the substrate, only a portion of the substrate contains the patterned cured liquid. The "repeating" part of this process involves depositing a photocurable liquid on another part of the substrate. The patterned template is then aligned with the substrate and in contact with the curable liquid. The curable liquid is cured using actinic light to form a second area of the cured liquid. This process can be repeated over and over until most of the substrate is patterned. Step and iterative processes can be used for definition, negative or positive / negative imprint processes. The step and repeat process may be performed by any embodiment of the equipment described herein.

Step and iterative imprint lithography processes provide many advantages over other techniques. The step and repeat processes described herein are based on imprint lithography using low viscosity photocurable liquids and rigidly transmissive templates. The template becomes transmissive to liquid actinic light and alignment mark detection light, thereby providing potential for interlayer alignment. For production-scale imprint lithography of multilevel devices, it is useful to include very high resolution interlayer alignments (eg, as low as 1/3 of the minimum mold size ("MFS")). Do.

There are various sources of distortion error in the manufacture of templates. Step and repeat processes are used so that only a portion of the substrate is processed during a given step. The size of the field processed during each step must be small enough to contain pattern distortions less than one third of the MFS. This is necessary for step repeat patterning in high resolution imprint lithography. This is also because most optical lithography tools are step and repeat systems. In addition, as described above, the requirement for low CD change and defect inspection / repair is also desirable for the processing of small fields.

In order to keep the process costs low, it is important to make the lithographic equipment have a sufficiently high throughput. Throughput requirements severely limit the patterning time required per field. Photocurable low viscosity liquids are of interest in terms of throughput. These liquids move much faster to properly fill the gaps of the template and the substrate and the lithographic performance is independent of the pattern. The resulting low pressure, room temperature treatment is suitable for high throughput while maintaining the benefits of interlayer alignment.

While the prior art deals with the patterning of low viscosity photocurable liquids, these techniques do not address step and repeat processes. In hot embossing as well as photolithography, the film is spin coated onto the substrate and hard baked before being patterned. When this method is used for low viscosity liquids, three major problems arise. Low-viscosity liquids tend to dehydrate and are difficult to spin coat because they cannot maintain the shape of the continuous film. Also, in the step and repeat process, the liquid is evaporated to vary the amount of liquid that will remain on the substrate when the template performs the step and repeat process on the substrate. Finally, blanket light exposure tends to be distributed over the particular field being patterned. This partially affects the fluid properties of the liquid before imprinting by partially curing the next field. Dispensing a liquid suitable for a single field onto a substrate, one field at a time, solves these three problems. However, in order to avoid loss of usable area on the substrate, it is important to limit the liquid precisely to a particular field.

In general, lithography is one of many unit processes used to manufacture devices. In particular, the cost of all these processes in a multilayer device is highly desirable to place the patterned regions as close to each other as possible without interfering with the next pattern. This effectively maximizes the available area to maximize the use of the substrate. Imprint lithography can also be used in "mix-and-match modes" with other types of lithography (e.g., optical lithography), where the same devices at different levels are made from different lithography techniques. It is useful to make the imprint lithography process compatible with other lithography techniques The boundary area is the area that separates two adjacent fields on the substrate In modern optical lithography tools, this boundary area can be as small as 50-100 microns. The size of the boundary is typically limited to the size of the blades used to separate the patterned area, which will be as small as the dicing blades that dice each chip. In order to achieve this stringent boundary size requirement, The location of any excess liquid exiting should be well limited and repeatable, including, but not limited to, surface energy, interfacial energy, Hamacker constants, van der Waal forces, viscosity, density, impermeability, etc. Each element, including templates, substrates, liquids, and any other material that affects the physical properties of the non-system, is designed as described herein to suitably accommodate a repeatable process.

As mentioned above, the discontinuous film is formed using a suitably patterned template. For example, a template with a high aspect ratio recess defining a boundary area can prevent liquid from flowing beyond the boundary area. The prevention of liquids within the boundary area is affected by various factors. As mentioned above, the template design serves to trap the liquid. In addition, the process of contacting the template with the liquid also affects the confinement of the liquid.

19A-C are cross-sectional views of a process of forming a discontinuous film on a surface. In one embodiment, as shown in FIG. 19A, the curable liquid 40 is dispensed onto the substrate 20 as a line or droplet pattern. Therefore, the curable liquid 40 does not cover the entire area of the substrate 20 to be imprinted. When the lower surface 536 of the template 12 contacts the liquid 40, the force of the template on the liquid diffuses the liquid over the surface 20 of the substrate as shown in FIG. 19B. In general, the greater the force exerted on the liquid by the template, the more diffuse the liquid will be across the substrate. Thus, when a sufficient amount of force is applied, the liquid is forced beyond the periphery of the template as shown in Fig. 19C. By adjusting the force exerted on the liquid by the template, the liquid is confined within certain boundaries of the template, as shown in FIG. 19D.

The amount of force applied to the liquid is related to the amount of liquid dispensed on the substrate and the distance the template is away from the substrate during curing. For negative imprint lithography processes, the amount of fluid dispensed onto the substrate is defined by the volume of liquid needed to substantially fill the recess of the patterned template, the area of the patterned substrate, and the desired thickness of the cured layer. It must be below the volume to which it is intended. If the amount of cured liquid exceeds this volume, the liquid will be displaced from the periphery of the template when the template is moved a suitable distance from the substrate. Definitions For a positive imprint lithography process, the amount of liquid dispensed onto the substrate must be less than the volume defined by the cured layer (ie, the distance of the unrecessed portion of the substrate and template and the surface area of the portion of the substrate to be patterned). do.

For an imprint lithography process using a template that includes one or more boundaries, the distance between the substrate and the unrecessed surface of the template is set between the minimum and maximum film thicknesses as described above. Setting the height between these values ensures that the appropriate capillary force is within the bounded area of the template to contain the liquid. In addition, the thickness of the layer should be about the same as the height of the patterned shape. If the cured layer is too thick, shapes formed in the cured layer may corrode before being transferred to the underlying substrate. Therefore, the volume is controlled as described above to use an appropriate film thickness.

The force exerted on the liquid by the template is also affected by the rate at which the template contacts the liquid. In general, the faster the template has a contact speed, the greater the force applied to the liquid. Thus, any measure of controlling liquid diffusion on the surface of the substrate can be accomplished by controlling the rate at which the template contacts the liquid.

All these shapes are taken into account when measuring the position of the template relative to the substrate during the imprint lithography process. By controlling these variables in a predetermined manner, the flow of liquid can be controlled to be confined and confined within a predetermined area.

Overlay alignment schemes include measuring alignment errors prior to compensating for these errors to achieve accurate alignment of the patterned template and the desired imprint position on the substrate. Accurate placement of the template relative to the substrate is important to achieve proper alignment of the patterned layer with any of the layers previously formed on the substrate. Placement errors as used herein are generally referred to as X-Y positioning errors (ie, movement along the X and / or Y-axis) between the template and the substrate. In one embodiment, the placement error is determined and corrected by using an optical device through the template as shown in FIG.

FIG. 28 schematically illustrates an optical system 3820 of an optical imaging system 3800 via a template (see also FIG. 14). Optical system 3820 is configured to focus the two alignment marks from different planes onto a single focal plane. Optical system 3820 uses a change in focal length resulting from light with various wavelengths to determine the alignment of the underlying substrate with the template. Optical system 3820 may include an optical imaging device 3810, an illumination source (not shown), and a focusing device 3805. Light with various wavelengths can be generated by using either a light source or a single broadband light source and inserting an optical band pass filter between the imaging surface and the alignment mark. Depending on the gap between the template 3700 and the substrate 2500, several wavelengths are selected to adjust the focal length. Under each wavelength of light used, each superimposition mark can generate two images on the image pickup surface as shown in FIG. The first image 2601 using light of a particular wavelength is an image that is clearly focused. The second image 2602 using light of the same wavelength is an out of focus image. In order to remove all images out of focus, various methods can be used.

In a first method, the optical imaging device 3810 may receive two images under illumination of a first optical wavelength. The image is shown in FIG. 29 and generally designated by reference numeral 2604. While the images are shown as squares, it should be understood that any other shape can be used, including a cross. Image 2602 corresponds to the overlap alignment mark on the substrate. Image 2601 corresponds to the overlap alignment mark on the template. When image 2602 is in focus, image 2601 is out of focus. In one embodiment, image processing techniques may be used to erase geometric data corresponding to pixels associated with image 2602. Thus, the out of focus image of the substrate mark is removed, leaving only the image 2601. Using the same procedure and light of the second wavelength, images 2605 and 2606 may be formed on the optical imaging device 3810. Thereafter, out of focus image 2606 is removed, leaving only image 2605. Thereafter, the two remaining focused images 2601 and 2605 are combined on a single imaging surface 2603 to make overlapping error measurements.

The second method may use two coplanar polarization arrays and polarized illumination sources as shown in FIG. 30 shows overlap mark 2701 and orthogonally polarized array 2702. Polarization array 2702 is formed on or disposed on a template surface. Under two polarized illumination sources, only focused image 2703 (each of which corresponds to various wavelengths and polarizations) may appear on the imaging plane. Thus, the out of focus image is filtered out by the polarization array 2702. The advantage of this method is that it may not require image processing technology to remove the out of focus image.

Overlapping measurements based on moire patterns are used for the optical lithography process. In an imprint lithography process, it may be difficult to obtain two angularly focused images if the two layers of the Muware pattern are not on the same plane but still overlap in the imaging array. However, careful control of the gap between the template and the substrate without direct contact between the template and the substrate and within the depth of focus of the optical measurement tool allows simultaneous acquisition of two layers of the Moire pattern while minimizing the problem of focusing. It is believed that other standard superposition schemes based on the Muware pattern can be performed directly for the imprint lithography process.

Another important issue for overlapping alignment for an imprint lithography process using a UV curable liquid material may be the visibility of the alignment mark. For overlap placement error measurement, two overlap marks, one overlap mark on the template and the other overlap mark on the substrate, are used. However, since it is desirable for the template to be permeable to the curing agent, in some embodiments, the template overlap mark does not become an opaque line. Rather, template overlap marks are topographical features of the template surface. In some embodiments, this mark is made of the same material as the template. In addition, the UV curable liquid may have a refractive index similar to that of the template material (eg, quartz). Therefore, when the UV curable liquid fills the gap between the template and the substrate, the template overlap mark can be very difficult to recognize. If the template overlap mark is made of an impermeable material (eg chromium), the UV curable liquid below the overlap mark may not be properly exposed to UV light.

In one embodiment, the superimposition mark is used on the template seen by the optical imaging system 3800, but is impermeable to cured light (eg, UV light). An embodiment of this manner is shown in FIG. In Fig. 31, instead of the complete opaque line, the overlap mark 3102 on the template may be formed of the fine polarization lines 3101. For example, suitable fine polarization lines have a width of about 1/2 to 1/4 of the wavelength of actinic light used as the curing agent. The line width of the polarization line 3101 is sufficiently small so that the active light passing between the two lines is sufficiently diffracted to cure all liquid below this line. In such an embodiment, actinic light is polarized in accordance with the polarization of the overlap mark 3102. Polarizing actinic light provides uniform exposure to all template areas, including areas with relatively overlap marks 3102. The light used to navigate the overlap mark 3102 on the template may be a particular wavelength that cannot cure the broadband light or liquid material. This light does not need to be polarized. The polarized line 3101 is substantially opaque to the measurement light to visualize the overlap mark using a set overlap error measurement tool. Finely polarized overlap marks are fabricated on a template using conventional techniques such as electron beam lithography.

In another embodiment, the overlap mark is formed of a material different from the template. For example, the material selected to form the template overlap mark is substantially impermeable to visible light but transparent to active light (eg, UV light) used as a curing agent. For example, SiO _X can be used as such a material, where X is less than two. In particular, the structure formed of SiO _X is substantially impermeable to visible light but transmissive to UV cured light, where X is about 1.5.

In one embodiment, one or more template alignments may be accomplished using an off-axis alignment process. As described above, the system may include an off-axis optical imaging device coupled to the motion stage and the imprint head. Although the following description relates to a system having a substrate installed in a motion stage, it should be understood that this process can be easily modified for a system having an imprint head installed in a motion stage. In addition, it should be understood that the following description corrects for magnification errors before performing the alignment process. Magnification errors occur when the material expands or contracts due to temperature changes. Techniques for correcting magnification errors are disclosed in US Patent Application 09 / 907,512, entitled "High-Resolution Overlay Alignment Methods and Systems for Imprint Lithography," filed July 16, 2001, incorporated herein by reference. In addition, magnification correction that differs in two orthogonal directions in the plane of the patterning area of the template may also be needed before alignment.

46A-D schematically illustrate a system for off-axis alignment of a substrate and a template. The imprint head 3100 includes a template 3700 and an off-axis imaging device 3840. The substrate 4600 is installed on a substrate chuck 3610 coupled to the motion stage 3620. Motion stage 3620 is configured to control the motion of the substrate in a direction substantially parallel to the template. Template optical imaging system 3850 is coupled to motion stage 3620 to allow the optical imaging system to be moved by the motion stage. The system also includes a system alignment target 4630. System alignment target 4630 is coupled to a fixture of a system that is optically aligned with the optical imaging system. System alignment target 4630 can be coupled to a non-moving optical imaging system (eg, optical imaging system 3840) or an imprint lithography system body. The system alignment target is used as a fixed reference point for the alignment measurement.

Template 3700 and substrate 4600 include at least one, preferably two alignment marks, as shown in FIG. 46A. During the imprinting process, the alignment marks on the template are aligned with the corresponding alignment marks on the substrate before curing the liquid disposed on the substrate. In one embodiment, alignment can be performed by using off-axis optical imaging devices. 46A shows the system in an initialized state. In this initial state, the template alignment mark is not aligned with the substrate alignment mark. However, optical alignment systems 3840 and 3850 are aligned with system alignment target 4630. Thus, the starting position of each motion relative to a fixed point in the system is known.

In order to perform alignment of the template and substrate alignment marks, the position of the alignment marks relative to the system alignment target is determined. To determine the position of the template alignment mark relative to the system alignment target, the motion stage 3610 is moved until the template alignment target is within the field of view of the optical imaging device 3850, as shown in FIG. 46B. The movement of the motion stage needed to find the alignment mark (in the X-Y plane) is used to determine the position of the template alignment mark relative to the system alignment target. The position of the substrate alignment target can be determined by moving the substrate to the motion stage 3610 until the substrate alignment mark is within the field of view of the off-axis optical imaging system 3840 as shown in FIG. 46C. The movement of the motion stage needed to find the alignment mark (in the X-Y plane) is used to determine the position of the template alignment mark relative to the system alignment target. In one embodiment, the motion stage may be moved to an initial position (eg, as shown in Figure 46A) prior to determining the position of the substrate alignment mark.

Once the position of the substrate and template alignment mark is determined, alignment is achieved by moving the substrate to the appropriate position. 46D shows the final aligned state of the template and substrate.

In order to properly align the template with the fields on the substrate, the position of the substrate relative to the template is selected to align the template and alignment marks on the substrate. Typically, two or more alignment marks are formed on the template. Corresponding alignment marks are also formed on the substrate. When all of the alignment marks on the template are properly aligned with the alignment marks on the substrate, an imprinting process is performed.

In some embodiments, the template can be rotated about the Z-axis relative to the substrate. In such an embodiment, it is not possible to align a number of alignment marks on the template with the corresponding alignment marks on the substrate just because of the X-Y movement of the substrate. In order to properly align the template with the selected field on the substrate, the substrate (or template) is rotated about the Z-axis. This rotation correction is referred to herein as "theta alignment."

47A is a top view of template 4710 positioned over substrate 4720. Template 4710 includes at least two alignment marks and substrate 4720 includes at least two corresponding alignment marks. When properly aligned, all template alignment marks must be aligned with all corresponding substrate alignment marks.

Initial alignment is performed by moving the substrate (or template) to a position such that at least one mark of the alignment marks on the template is aligned with at least one mark of the alignment marks on the substrate, as shown in FIG. 47B. When there are no theta alignment errors (and magnification errors), the alignment marks must be registered without any additional movement of the substrate. However, as shown in Figure 47B, theta alignment error will misalign the template and other alignment marks on the substrate. Theta error correction is performed before additional imprinting is performed.

Theta error correction is achieved by rotating the substrate (template) about the Z-axis (ie, the axis extending out of the page perpendicular to the X and Y axes of the page). Rotation of the substrate will align all template and substrate alignment marks as shown in FIG. 47C.

Theta errors can be detected (corrected) using either off-axis or template alignment procedures. As described herein, off-axis alignment techniques allow the location of various alignment marks to be determined relative to a fixed reference point (eg, system alignment target). 47D is a top view of template 4710 positioned over substrate 4720. Template 4710 includes at least two alignment marks and substrate 4720 includes at least two corresponding alignment marks.

Initially, using the off-axis imaging device, the positions of the two template alignment marks and the two substrate alignment marks are determined relative to the system alignment target 4730. System alignment target 4730 defines the vertices of the X and Y reference axes. The directions of the X and Y reference axes relative to the system alignment target are determined by the directions of the X-motion and Y-motion, respectively, of the motion stage. The position of the template alignment mark is used to determine the angle of the line 4740 through the template alignment mark with respect to the X and Y reference axes. The position of the substrate alignment mark is used to determine the angle of the line 4750 through the substrate alignment mark with respect to the X and Y reference axes. The angles of lines 4740 and 4750 can be determined using standard geometric functions. The difference in the determined angles of 4740 and 4750 with respect to the X and Y reference axes indicates theta alignment error.

After determining the theta error, the motion stage is rotated to an appropriate amount to correct this error. Once calibrated, the angle of line 4740 drawn through the template alignment mark and the angle of line 4750 drawn through the substrate alignment mark with respect to the X and Y reference axes must be substantially the same. After the theta correction is completed, the template and substrate alignment marks are finally aligned by the X-Y movement of the motion stage. The imprinting process is subsequently performed with a properly aligned template and substrate.

In another embodiment, the alignment method through the template may be used to align the template with the substrate by correcting theta error. The alignment technique through the template is done by observing the alignment of the template alignment mark with respect to the corresponding substrate alignment mark by observing the two marks. As described herein, this can be accomplished using an optical system that observes the template and substrate alignment marks through the template.

47E is a view from above of template 4710 positioned over substrate 4720. Template 4710 includes at least two alignment marks and substrate 4720 includes at least two corresponding alignment marks.

Initially, using an optical imaging device through a template, the motion stage is moved so that the first template alignment mark is aligned with the first substrate alignment mark, as shown in FIG. 47E. The position of the second template alignment mark and the second substrate alignment mark is determined by moving the optical imaging device over the template until the alignment mark is found. Once the position of the template mark is found, the virtual line 4740 (between the template alignment marks) and the virtual line 4750 (between the substrate alignment marks) are calculated and used to determine theta angle between these two lines. This angle indicates theta error.

In one embodiment, the position of the second template and substrate alignment mark is determined by the movement of the motion stage. Initially, the first template and substrate alignment mark are aligned as shown in FIG. 47E. The optical imaging device is moved to find the second template alignment mark. After finding this mark, the motion stage is moved, while the optical imaging device remains in the same position until the first template alignment mark is moved back to the field of view of the optical imaging device. The movement of the motion stage is monitored and this movement is used to calculate the position of the second template alignment mark relative to the first template alignment mark. The position of the second template alignment mark relative to the first template alignment mark is determined based on the X-Y reference plane defined by the direction of the X-motion and Y-motion of the movement stage. In a similar manner, the position of the second substrate alignment mark is determined relative to the second substrate alignment mark.

After determining the theta error, the motion stage is rotated to an appropriate amount to correct this error. After the theta correction is completed, the template and substrate alignment marks are finally aligned by the X-Y movement of the motion stage. The imprinting process is subsequently performed with the template and the substrate properly aligned.

In another embodiment, both off-axis and alignment through the template are used together to align the template with the substrate. In this embodiment, the off-axis method can be used to perform the first alignment, while the alignment through the template can be used to refine the alignment of the substrate and the template. Theta calibration and X-Y calibration are performed using two techniques.

Theta correction alignment process described above can be used for step and repeat processes. Step and repeat sorting can be done by sorting globally or field by field. For global alignment, two or more fields of the substrate will include at least two alignment marks. Alignment via off-axis or template is done in two or more fields and theta alignment error and X-Y alignment error in each field are determined. Optionally, the alignment in each field may involve an imprinting step. Theta alignment error and X-Y alignment error in each field are then averaged to determine the "average alignment error". The average alignment error is used to determine the correction needed to apply any field on the substrate.

The average alignment error is then used in the step and repeat process. In step and repeat processes, the location of each field is predetermined and stored in a database of the lithography system. During imprinting, the motion stage is moved so that the template is directed over the desired position of the substrate based on the coordinates stored in the database. The template and the substrate then undergo an alignment correction based on the average alignment error. The actinic curable liquid may be disposed on the substrate before or after alignment correction. Active light is applied to cure the active light curable liquid and the template is separated from the cured liquid. The motion stage is moved to direct the template over another portion of the substrate and this process is repeated.

Alternatively, an alignment process may be used per field. During imprinting, the motion stage is moved so that the template is directed over the desired field of the substrate based on the coordinates stored in the database. Each field of the substrate includes two or more alignment marks corresponding to the alignment marks on the template. The template alignment mark is then aligned with the substrate alignment mark in a particular field that is imprinted using wither off-axis, via a template or a combination of these alignment techniques. The actinic curable liquid may be disposed on the substrate before or after alignment. Active light is applied to cure the active light curable liquid and the template is separated from the cured light. The motion stage is moved to direct the template over another field of substrate and template. Alignment is done by each individual field of the substrate.

In one embodiment, alignment may be performed using scatterometry. Scattering is a technique used to measure the properties of light scattered out of a surface. To align the substrate with the template, the scatterometry uses a diffraction grating on the substrate and the template. In the imprint technique, the alignment mark on the template and the alignment mark on the substrate can be separated from each other by less than 200 nm. Therefore, the alignment system can see two alignment marks at the same time. In general, incident light on the alignment mark will be scattered from the alignment mark in a predictable manner according to the orientation measurement of the alignment mark with respect to each other. In one embodiment, light scattering is calculated when the alignment marks are aligned, producing a scattering profile. In use, alignment is achieved by moving either the substrate or the template until the scattered light profile from the alignment mark substantially matches the desired scatter profile.

While patterning the substrate using imprint lithography, the patterned template is positioned over a portion of the substrate. Typically, the portion of the substrate to be imprinted will have a structure previously formed. Before imprinting the patterned template, it needs to be aligned with the preformed structure on the substrate. For sub 100mm imprint lithography, alignment of the template with the shapes on the substrate may be enabled with an accuracy of less than about 25 nm, and in some embodiments, less than about 10 nm. Alignment of the substrate with the template is typically accomplished by the use of alignment marks. Matching alignment marks are formed on the substrate and the template and located at a predetermined position. When the alignment marks are properly aligned, the template is properly aligned with the substrate and the imprint process is performed.

In general, the alignment can be performed using a high power microscope. Such a microscope collects images of alignment marks. The collected image is analyzed by the user, and the user changes the position of the template with respect to the substrate to align the image to align the template with the underlying substrate. High power microscopes that can achieve alignment accuracy less than 10 nm are very expensive and can be difficult to implement within an imprint lithography system.

Scattering provides a technique for collecting image data without imaging the shape. Generally, scatterometry tools include optical hardware, such as ellipsometers or reflectometers, and data processing devices loaded with scatterometry software applications for processing data collected by the optical hardware. Scattering tools generally include an analytical light source and a detector that can be positioned proximate the alignment marks on the substrate and template. The light source can illuminate at least a portion of the diffraction grating structure of the alignment mark. The detector takes optical measurements such as the intensity or phase of the reflected light. The data processing apparatus receives the optical measurement from the detector and processes this data to determine the scattering profile of the light out of the diffraction grating.

The scatterometry tool may use monochromatic light, white light, or any other wavelength or combination of wavelengths, depending on the particular implementation. The angle of incidence of light may also vary depending on the particular implementation. The light analyzed by the scatterometry tool typically includes reflected components (ie, angle of incidence equal to reflection angle) and scattered components (ie, angle of incidence not equal to reflection angle). To describe below, the term "reflected" light is meant to include two components.

When the alignment mark on the template is aligned with the alignment mark on the substrate, light is reflected off the surface in a way that can be characterized in the reflection profile. Misalignment of the substrate and template alignment marks changes the reflection profile (eg, intensity, phase, polarization, etc.) measured by the scatterometry tool compared to the light reflection profile present when the mark is aligned. In use, the scatterometry tool measures the reflection profile for the alignment mark. The difference in reflection profile measured for alignment marks during use indicates misalignment of the substrate and template.

The data processing device of the scatterometry tool compares the specified reflection profile with a reference reflection profile library. The difference between the measured reflection profile and the reference reflection profile is used to determine the alignment of the substrate alignment mark and the template alignment mark. Alternatively, when the two gratings are aligned, the scatterometry pattern from the vertical incident beam should be symmetric, i.e. the + and -1 differences should be the same, or from two opposite low angle incident beams (zero The orders must be the same. Symmetric signals from multiple wavelengths are subtracted, this difference is summed to measure alignment, and the wafer or template must be shifted to minimize the sum.

Scattering measurements offer advantages over optical imaging processes. The optical requirements of the scatterometry tool are much lower than for optical imaging systems. In addition, scatterometry makes it possible to collect additional optical information (eg, optical phase and polarization) that cannot be collected using an optical imaging device such as a microscope.

An alignment mark is shown in Figure 48A. Alignment mark 4800 includes a plurality of trenches formed in substrate 4820 (eg, a template or substrate on which an imprinted layer is formed), all of which may include diffraction gratings (eg, 4825 and 4827). It is limited. Alignment mark 4800 is shown in cross section in FIG. 48B. Typically, the diffraction grating can be formed by etching a plurality of grooves in the substrate. These grooves have substantially the same width and depth and are evenly spaced. At least two sets of diffraction gratings are used to align along the X and Y axes. As shown in Figure 48A, the first group of trenches 4525 define a diffraction grating for aligning along a first axis (e.g., X-axis). The second group of trenches 4827 define a diffraction grating for aligning along a second axis (eg, Y-axis).

An alternative embodiment of the alignment mark is shown in Figure 48C. At least four sets of diffraction gratings are used to align the template with the substrate. The diffraction grating is formed from a number of trenches that are etched into the substrate as described above. Two of the diffraction gratings 4830 and 4840 are used for coarse alignment of the substrate and the template. Roughly aligned gratings are formed from multiple trenches having substantially the same width and depth and are evenly spaced. Roughly aligned diffraction grating trenches may be spaced at a distance between about 1 μm and about 3 μm. Diffraction gratings with this range of spacing can be used to align the substrate and template with an accuracy of up to about 100 nm. Diffraction grating 4830 is used to align along a first axis (e.g., X-axis). Diffraction grating 4840 is used to align along a second axis (eg, Y-axis).

When imprinting onto a surface a structure with a shape size smaller than about 100 nm, this accuracy is not sufficient to properly orient different patterning layers. Additional grating structures 4850 and 4860 can be used for fine alignment. The fine diffraction grating is formed from a plurality of trenches having substantially the same width and depth and evenly spaced apart. The fine aligned diffraction grating trenches may be spaced at a distance between about 100 nm and about 1000 nm. Diffraction gratings with gaps in this range can be used to align the substrate and template with an accuracy of up to about 5 nm. Diffraction grating 4850 is used to align along a first axis (eg, X-axis). Diffraction grating 4860 is used to align along a second axis (eg, Y-axis).

Figure 49 illustrates a configuration of the scatterometry tool used to determine the alignment between the template alignment mark 4910 and the substrate alignment mark 4920. The scatterometry tool generates an incident light beam 4930 that is directed to the alignment mark as shown. The incident light beam 4930 is directed in a direction substantially perpendicular to the plane of the template (or substrate). The incident light beam 4930 may be generated from a white light source or any other light source capable of generating light of multiple wavelengths. The light source used to generate the light may be disposed in the imprint head of the imprint system as described herein. Alternatively, the light source can be coupled to the outer body of the imprint head and the optical system can be used to direct light to the template.

When light from the light source is in contact with the alignment mark, this light is scattered as shown in FIG. As is known in the art, scattering of light produces maximum light intensity at different angles. The angles that generate different maximum light correspond to different diffraction orders. Typically, when light is reflected off the diffraction grating, a number of orders occur. Zero order as used herein refers to light that is reflected back to the light source along the same optical path as incident light. As shown in Fig. 49, the light reflected back to the light source along the incident light beam 4930 becomes zero order. The primary light is reflected off the diffraction defects along an angle different from the incident angle. As shown in Figure 49, light rays 4942 and 4944 represent light generated along a positive first order (i.e., +1 order) and light rays 4952 and 4954 are negative first order (i.e., -1st order). ) Indicates the light generated. Although +1 and -1 orders are shown, other orders of light (eg, N orders, where n is greater than zero) can be used.

In use, light reflected from the substrate (and through the template) is collected by the detector 4960. In one embodiment, detector 4960 is an array detector capable of simultaneously measuring optical properties at multiple locations. When light is scattered from the diffraction grating, light of each wavelength is scattered differently from each other. In general, all wavelengths will be scattered along one of the diffraction orders, but light of different wavelengths will be scattered at somewhat different angles. Figure 49 shows how two different light wavelengths are reflected along the +1 and -1 orders. Note that the difference in scattering angle is magnified for this explanation. Referring to the + 1st order, the light beam 4942 displays red light, while the light beam 4944 displays blue light. For -primary, light beam 4952 displays red light, while light beam 4954 displays blue light. As shown, the red and blue light beams are in contact with the diffractive portion of the detector. Detector 4960 includes an array of photodetecting elements. The size and position of the photodetector allows for analyzing different wavelengths of light. As shown in Fig. 49, red light 4942 impinges on blue light 4944 and other light detecting elements. Thus, the scatterometry tool can measure optical properties simultaneously at multiple wavelengths.

The advantage of measuring scattering at multiple light wavelengths is that the phase error can be averaged out. Phase error is caused by non-uniformity in the etching of the trenches forming the diffraction grating. For example, if the walls are non-parallel or the bottom of the trench is angled, light scattering may not follow the predicted model. Such errors tend to vary depending on the light wavelength used for analysis. For example, processing errors in forming trenches can cause greater deviations for red light than blue light. By reading multiple wavelengths, one wavelengths can be averaged to induce alignment more accurately.

In the alternative embodiment shown in FIG. 50, the light reflected from the alignment mark can be scattered as described above with respect to FIG. Instead of capturing different light wavelengths depending on the resolution of the detector, the optical element 5070 can be used to separate the reflected light. As described above, the template alignment mark 5010 and the substrate alignment mark 5020 are illuminated with incident light 5030. Incident light 5030 is directed in a direction perpendicular to the plane defined by the template. Light reflected from the diffraction grating of the alignment mark is analyzed along the +1 order 5040 and the -order 5050. In this embodiment, the optical element 5070 is disposed in the optical path between the substrate and the detector 5060. The optical element 5070 is configured to diffract light at different angles based on the light wavelength. Optical element 5070 may be, for example, a diffraction grating (eg, part of a spectrophotometer) or prism. As shown in FIG. 50, red light is diffracted at an angle different from blue light. Although shown as a single element in FIG. 50, it should be understood that the optical element 5070 may be comprised of two separate elements. In addition, although optical element 5070 and detector 5060 are shown as separate elements, it should be understood that this element may be integrated into a single device (eg, a spectrophotometer).

Alternatively, optical element 5070 can be a lens. When the optical element 5070 is a lens, diffraction occurs when light passes through the lens. The degree of diffraction is based, in part, on the refractive index of the lens material. The degree of diffraction is also based on the light wavelength. Different light wavelengths will be diffracted at different angles. This is known as "chromatic aberration." Using chromatic aberration can improve the separation of light at different wavelengths. In some embodiments, two lenses may be used, one lens for each order of light.

Scattering measurements as described above can be used for an imprint lithography process. In one embodiment, the amount of active photocurable liquid is disposed on a portion of the substrate to be imprinted. The patterned template is located proximate to the substrate. Generally, the template is separated from the substrate by a distance less than about 200 nm. In order to properly align the patterned template with the preformed structure on the substrate, the template alignment target is aligned with the substrate alignment target. The template alignment target includes a diffraction grating, allowing scattering techniques to be used for alignment. Initial alignment of the substrate alignment mark and the template alignment mark is accomplished using a mask optical imaging. This mark is aligned using pattern recognition software. Such alignment can be used to achieve alignment accuracy within about 1 micron.

Scattering measurements are used for the next iteration of the alignment. In one embodiment, the alignment mark includes a coarse alignment diffraction grating and a fine alignment diffraction grating, such as the alignment mark shown in FIG. 48C. Rough alignment of the alignment marks can be performed using a roughly aligned diffraction grating. Fine alignment of the alignment marks can be performed using a fine alignment diffraction grating. All alignment measurements can be performed with an active photocurable liquid disposed between the template and the substrate. As described herein, the optical imaging device may be required to perform initial alignment. Before performing scattering measurement, the optical imaging device may be moved off the optical path between the light source and the template. Alternatively, light from the light source can be directed in a manner such that the optical imaging device does not lie in the optical path between the light source and the template.

In one embodiment, light may be directed to a template and substrate alignment mark perpendicular to the plane defined by the template. Light scattering measurements along the +1 and -1 orders can be analyzed at multiple wavelengths. The intensity level of light scattered in the +1 order is compared with the light intensity level of light scattered in the -1 order. Once the template alignment mark and the substrate alignment mark are aligned, the intensity is substantially the same at any given wavelength. The difference in light intensity between the +1 and -1 order indicates that the alignment marks may be misaligned. The degree of misalignment at multiple wavelengths is compared, resulting in an "average" misalignment of the alignment marks.

The average misalignment of the template and the substrate alignment mark can be used to determine the correction needed for the position of the template relative to the substrate to properly align the alignment mark. In one embodiment, the substrate is disposed on a substrate motion stage. Alignment can be achieved by moving the substrate in an appropriate manner as determined by the mean misalignment calculated using scattering measurements. After the template and substrate are properly aligned, curing of the liquid may be performed prior to separating the template from the cured liquid.

FIG. 51 illustrates an alternative configuration of a scatterometry tool used to determine alignment between template alignment mark 5110 and substrate alignment mark 5120. Scattering tool 5100 measures the two zero order reflections off the substrate to determine the alignment of the alignment marks. The two light sources generate two incident light beams 5130 and 5135 directed to the alignment mark as shown. The incident light beams 5130 and 5135 are directed in a direction that is not substantially perpendicular to the plane of the template (or substrate). Incident light beams 5130 and 5135 may be generated from a white light source or any other light source capable of generating light of multiple wavelengths. Incident light beams 5130 and 5135 pass through beam splitters 5152 and 5194 respectively.

When light from the light source contacts the alignment mark, the light is scattered as described above. Zero order light is light that is reflected back to a light source along the same optical path as incident light. Light reflected back toward the light is reflected by the beam splitters 5152 and 5194 toward the detectors 5160 and 5162. In one embodiment, detectors 5160 and 5162 are array detectors capable of simultaneously measuring optical properties at multiple locations. When light is scattered from the diffraction grating, the individual light wavelengths are scattered differently. In general, as described above, all wavelengths will be scattered along one of the diffraction orders, but different light wavelengths will be scattered at somewhat different angles. Note that the difference in scattering angles is enlarged for this explanation. For incident light beam 5130, light beam 5152 shows red light, while light beam 5144 shows blue light. For incident light beam 5135, light beam 5152 displays red light, while white light 5504 displays blue light. As shown, the red and blue light beams are in contact with different detector portions. Detector 5160 includes an array of photodetecting elements. The size and position of the photodetector allows for analyzing different wavelengths of light. As shown in Fig. 51, red light 5152 collides with blue light 5144 and other light detecting elements. Thus, the scatterometry tool can measure optical properties of multiple wavelengths simultaneously. Using an array detector has the additional advantage of being able to detect any small change in the direction of the wafer or template or any other mechanical change that changes the position of the order peak and can accurately measure the intensity.

The scatterometry system shown in FIG. 51 uses the strongest reflected signal (ie, zero order signal) for alignment. In general, when the incident light is perpendicular to the grating, the alignment difference of the grating does not become very large along the zero difference. By using a non-perpendicular angle of incidence, it is believed that the zero difference is more sensitive to misalignment of the grating. In addition, the optical path for the scatterometry system places the optical imaging device 5180 in the center of the system. As described herein, optical imaging device 5180 may be used for coarse alignment of template and substrate alignment marks. During alignment of the template and substrate using a scatterometry system, movement of the optical imaging device may not be necessary.

In the alternative embodiment shown in FIG. 52, the light reflected from the alignment mark can be scattered as described above with respect to FIG. Instead of capturing light of different wavelengths depending on the resolution of the detector, the reflected light can be separated using optical elements 5272 and 5274. As described above, template alignment mark 5210 and substrate alignment mark 5220 are illuminated with two incident light beams 5230 and 5235. Incident light beams 5230 and 5235 are directed in a direction that is not perpendicular to the plane defined by the template. Light reflected from the diffraction grating of the alignment mark is analyzed along the zero difference by reflecting light into the beam splitters 5292 and 5294. In this embodiment, optical elements 5272 and 5274 are disposed in the optical path between the substrate and the detector 5260. Optical elements 5272 and 5274 are configured to diffract light at different angles based on the light wavelength. Optical elements 5272 and 5274 can be, for example, diffraction gratings (eg, portions of spectrophotometers) or prisms. Alternatively, optical elements 5272 and 5274 can be lenses that exhibit chromatic aberration.

In the alternative embodiment shown in FIG. 53, the light reflected from the alignment mark can be scattered as described above in FIG. Instead of capturing light of different wavelengths depending on the resolution of the detector, the reflected light can be separated using optical elements 5172 and 5374. Light reflected outside the alignment mark is directed to the optical fiber cables 5376 and 5378 by beam splitters 5392 and 5394 respectively. The first optical cable carries light from the imprint system to the optical elements 5372 and 5374. Optical elements 5372 and 5374 are configured to diffract light at different angles based on the light wavelength. Optical elements 5372 and 5374 can be, for example, diffraction gratings (eg, portions of spectrophotometers) or prisms. Alternatively, optical elements 5372 and 5374 may be lenses that exhibit chromatic aberration. An advantage of this embodiment is that a portion of the optical system can be isolated from the imprint system. This allows the imprint system size to be kept to a minimum.

An alternative embodiment of the configuration of the scatterometry tool used to determine the alignment between the template alignment mark 5410 and the substrate alignment mark 5520 is shown in FIG. The two light sources generate two incident light beams 5430 and 5435 which are directed to the alignment mark as shown. Incident light beams 5430 and 5435 are directed in a direction that is not substantially perpendicular to the plane of the template (or substrate). Incident light beams 5430 and 5435 can be generated from a white light source or any other light source capable of generating light of multiple wavelengths. Incident light beams 5430 and 5435 pass through beam splitters 5552 and 5494 respectively.

When light from the light source contacts the alignment mark, the light is scattered as shown in FIG. As shown in Fig. 54, the light reflected back to the light source along the incident light beam 5430 and the incident light beam 5535 becomes zero order. The primary light is reflected off the diffraction grating along an angle different from the incident angle. As shown in FIG. 54, light beam 5440 indicates light generated along the +1 order of the incident light beam 5430. As shown in FIG. Ray 5450 represents an incident light beam 5440 of the + 1st order. The primary beam is not shown. Although the +1 order is shown, it should be understood that other orders of light (eg, N orders, where n is greater than zero) may be used.

Light reflected outside the alignment mark is directed to the first optical cable 5476 and 5478 by beam splitters 5542 and 5494. Fiber optic cables carry light from the imprint system to optical elements 5542 and 5474. Optical elements 5542 and 5474 are configured to diffract light at different angles based on the light wavelength. Optical elements 5542 and 5474 may be, for example, diffraction gratings (eg, portions of spectrophotometers) or prisms. Alternatively, optical elements 5542 and 5474 can be lenses that exhibit chromatic aberration.

Beam splitters 5552 and 5494 pass some of the reflected light through the beam splitter. The portion of light that passes through the beam splitter is analyzed using photo detectors 5542 and 5464. The photo detector is used to determine the overall intensity of all light passing through the beam splitters 5552 and 5494. Data regarding the overall intensity of the light can be used to determine the alignment of the template and substrate alignment marks. In one embodiment, this alignment is determined according to the average of the error measurements and the light intensity measurements determined by spectrophotometric analysis of the nth order (eg, + 1st order) reflected light.

It should be understood that any of the embodiments described above can be combined for different configurations. In addition, it should be understood that the optical properties used to determine the alignment of the template and substrate marks include light intensity and polarization of light.

In all embodiments of the imprint lithography process, liquid is dispensed onto the substrate. While the following description relates to dispensing liquid onto a substrate, it should be understood that the same liquid dispensing technique is also used when dispensing liquid onto a template. The liquid dispensing process is carefully controlled. In general, liquid dispense is controlled so that a predetermined amount of liquid is dispensed at an appropriate location on the substrate. In addition, the liquid volume is also controlled. The combination of an appropriate volume of liquid and an appropriately positioned liquid is controlled by using the liquid dispensing system described herein. In particular, step and repeat processes use a combination of liquid volume control and liquid batch to limit patterning to specific fields.

Various liquid dispensing patterns are used. The pattern can be used in the form of continuous lines or patterns of droplets. In some embodiments, the relative motion between the placement and imprinting member based on the liquid dispenser tip is used to form a pattern with substantially continuous lines on a portion of the imprinting member. The balancing rate of dispensing and relative motion is used to control the cross-sectional size of the line and the shape of the line. During the dispensing process, the dispenser tip is secured near the substrate (e.g., on the order of tens of microns). Two examples of the continuous pattern are shown in Figs. 32A and 32B. The patterns shown in Figs. 32A and 32B are sine patterns, but other patterns are possible. As shown in Figures 32A and 32B, the continuous line pattern can be derived using either a single dispenser tip 2401 or multiple dispenser tips 2402. Alternatively, a pattern of droplets may be used as shown in FIG. 32C. In one embodiment, a small droplet pattern with a central small droplet having a volume larger than the surrounding droplet is used. When the template is in contact with droplets, the liquid diffuses to fill the patterning area of the template as shown in FIG. 32C.

The dispensing speed v _d and the relative lateral speed v _s of the imprinting member can be related as follows.

v _d = V _d / t _d (dispensing volume / dispensing period), (1)

v _s = L / t _d (line length / dispensing period), (2)

v _d = a L (where 'a' is the cross-sectional area of the line pattern), (3)

therefore,

v _d = av _s (4)

The width of the initial line pattern typically depends on the tip size of the dispenser. The dispenser tip may be fixed. In one embodiment, the liquid dispensing controller is used to control the time taken to dispense the dispensed liquid volume (V _d ) and the liquid (t _d ). When V _d and t _d are fixed, the length of the line is increased to approximate the cross-sectional height of the patterned line. Increasing the pattern length can be accomplished by increasing the spatial frequency of the periodic pattern. Lower heights of the pattern may increase the amount of liquid to be displaced during the imprint process. By using multiple tips connected to the same dispensing line, long length line patterns can be formed faster than in the case of a single dispenser tip. Alternatively, a number of closely spaced drops are used to form a line with the correct volume.

After curing of the liquid is complete, the template is separated from the cured liquid. Because the template and the substrate are almost perfectly parallel, the assembly of the template, the imprint layer, and the substrate brings the substantially uniform contact between the template and the cured liquid. Such a system may require a large separation force to separate the template from the cured liquid. In one embodiment, in the case of a flexible template or substrate, separation is performed using a "peeling process". However, the use of flexible templates or substrates may be undesirable for high resolution overlapping alignments. In the case of quartz templates and silicon substrates, it may be difficult to perform the peeling process. In one embodiment, the "peel" and "pull" processes are performed to separate the template from the imprint layer. One embodiment of the peel and pull process is shown in FIGS. 33A, 33B, and 33C.

33A shows template 12 embedded in the cured layer after curing. After curing the material 40, either the template 12 or the substrate 20 is tilted to intentionally angle 3604 between the template 12 and the substrate 20 as shown in Figure 35B. do. A pre-calibration stage coupled to either the template or the substrate can be used to tilt between the template and the cured layer 40. If the tilt axis is positioned proximate the template-substrate interface, the relative lateral motion between the template 12 and the substrate 20 may not be large during the tilt motion. If the angle 3604 between the template 12 and the substrate 20 is large enough, the template 12 can be separated from the substrate 20 using only Z-axis motion (ie, vertical motion). This peeling and pulling method allows the desired mold 40 to remain intact on the transport layer 18 and the substrate 20 without performing undesirable shear.

In addition to the embodiments described above, the embodiments described herein include forming a patterned structure by using an electric field. The cured layer formed using an electric field to generate a pattern in the cured layer can be used for single imprinting or for step and repeat processes.

34 illustrates an embodiment of template 1200 and substrate 1202. In one embodiment, template 1200 is formed from a material that is transparent to actinic light to cure the actinic curable liquid by exposure to actinic light. Forming the template 1200 from the transmissive material measures the gap between the template 1200 and the substrate 1202 using established optical techniques and measures the overlap marks to perform overlap alignment and magnification correction during formation of the structure. Template 1200 is also thermally and mechanically stable to provide nano-resolution patterning performance. Template 1200 includes a conductive material and / or layer 1204 to generate an electric field at the template-substrate interface.

In one embodiment, a blank of dissolved silica (eg, quartz) is used as the material for the base 1206 of the template 1200. Indium tin oxide (ITO) is deposited onto the base 1206. ITO is transparent to visible and UV light and is a conductive material. ITO can be patterned using high resolution electron beam lithography. As described above, the low surface energy coating is coated onto the template, improving the release properties between the template and the polymerized composition. Substrate 1202 may include standard wafer materials such as Si, GaAs, SiGeC, and InP. UV curable liquids and / or thermally curable liquids may be used as the active photocurable liquid 1208. In one embodiment, active photocurable liquid 1208 may be spin coated onto wafer 1210. In another embodiment, a volume of active photocurable liquid 1208 may be dispensed onto a substrate in a predetermined pattern as described herein. In some embodiments, the transport layer 1212 may be disposed between the wafer 1210 and the active photocurable liquid 1208. The transport layer 1212 material properties and thickness may be selected to produce a high aspect ratio structure from the low aspect ratio structure produced in the cured liquid material. Connecting ITO to voltage source 1214 may generate an electric field between template 1200 and substrate 1202.

Two embodiments of the process described above in FIGS. 35A-D and 36A-C are shown. In each embodiment, a desired uniform gap can be maintained between the template and the substrate. An electric field of a desired size is applied to direct the active photocurable liquid 1208 to the protruding portion 1216 of the template 1200. 35A-D, the gap and field size are such that the active photocurable liquid 1208 is in contact and adhered to the template 1200. Curing agents (eg, actinic light 1218 and / or heat) may be used to cure the liquid. Once the desired structure is formed, the template 1200 can be separated from the substrate by the method described herein.

36A-C, the gap and field size may be selected to achieve a topography in which the active photocurable liquid 1208 becomes essentially the same as the topography of the template 1200. This topography can be accomplished without direct contact with the template. Curing agent (eg, actinic light 1218) may be used to cure the liquid. In the embodiments of FIGS. 35A-D and 36A-C, the next etch process may be used to remove the cured material 1220. Additional etch may also be used if the carrier layer 1212 is provided between the cured material 1220 and the wafer 1210 as shown in FIGS. 35A-D and 36A-C.

In yet another embodiment, FIG. 37A illustrates a conductive template including a continuous layer of conductive portion 1504 coupled to non-conductive base 1502. As shown in Figure 37B, the non-conductive portions of the template 1502 are separated from each other by conductive portions 1504. The template can be used in a "definition" imprint process as described above.

Using an electric field, in some cases, forms lithographic patterned structures in less than about 1 second. This structure is generally tens of nanometers in size. In one embodiment, curing the active photocurable liquid in the presence of an electric field produces a patterned layer on the substrate. This pattern is created by placing the template in a particular nanometer-sized topography at a controlled distance (eg, within nanometers) from the surface of a thin layer of curable liquid on the substrate. If all or part of the desired structure is a regularly repeating pattern (eg, an array of dots), the pattern on the template may be significantly larger than the size of the desired repeating structure.

Duplication of the pattern on the template can be accomplished by applying an electric field between the template and the substrate. Since the liquid and air (or vacuum) have different permittivity and the electric field is locally variable due to the presence of the topography of the template, electrostatic forces are generated to direct the area of the liquid to the template. Surface tension or capillary pressure tends to stabilize the membrane. At high field strength, the active light curable liquid may be made to adhere to the template and may be made to dewet from the substrate at some point. However, if the ratio of electrostatic force, measured in dimensionless number Λ, is comparable to the capillary force, a liquid film will attach. The magnitude of the electrostatic force is approximately εE ² d ² , where ε is the dielectric constant of the vacuum, E is the size of the electric field, and d is the shape size. The magnitude of the capillary force is approximately γ d, where γ is the liquid-gas surface tension. The ratio of these two forces is Λ = εE ² d / γ. In order to deform the interface and attach it to the top surface, the electric field must be such that L is approximately 1 (unity). The exact value for this depends on the detail of the topography of the plate and the ratio of liquid-gas permittivity and height, but this number will be 0 (1). Thus, the electric field is provided at approximately E to (γ / ε d) ^1/2 . This active photocurable liquid can be cured suitably by the polymerization reaction of a composition. The template may be treated with a low energy self-assembled monolayer membrane (eg, fluorinated surfactant) to support the desorption of the template in the polymerized composition.

Examples of such approximations are provided below. For d = 100nm, γ = 30mJ / m and ε = 8.85 × 10-12 C ² / Jm, E = 1.8 × 10 ⁸ V / m, which is appropriate 18V if the plate spacing is 100nm and 180V if the plate spacing is 1000nm. Corresponds to the potential difference between the plates. Note that the shape size d ~ γ / εE ² , which means that the shape size is reduced by the square of the electric field. Thus, 50 nm shapes require voltages on the order of 25 or 250 volts for 100 and 1000 plate spacing.

By controlling the electric field, the topography of the template and the proximity of the liquid surface to the template, a pattern can be created in an active photocurable liquid that is not in contact with the surface of the template. This technique can also eliminate the need to mechanically separate the template from the polymerized composition. However, when not in contact, the liquid cannot form a sharp, high resolution structure as well defined as in the case of contact. This may first be processed by creating a structure of active photocurable liquid that is partially defined at a given electric field. Next, while increasing the gap between the template and the substrate, at the same time increasing the size of the electric field to form a clearly defined structure without "draw-out" the liquid to contact.

The active photocurable liquid may be deposited on top of the carrier layer as described above. This bi-layer process uses an electric field to form a low aspect ratio high resolution structure prior to the etch process yielding a high aspect ratio high resolution structure. This bilayer process is also used to perform a "metal lift-off process" to deposit metal on a substrate, which is then lifted off into the trench area of the originally created structure. Leave it behind.

With the use of low viscosity active photocurable liquids, pattern formation using an electric field can be at high speeds (eg, less than about 1 second), and this structure can be cured rapidly. Avoiding temperature variations in substrates and active light liquid curable liquids can also avoid unwanted pattern distortions that prevent nano-resolution interlayer alignment from being performed. In addition, as described above, the pattern can be quickly formed without contacting the template, thereby eliminating defects associated with an imprint method requiring direct contact.

Certain US patents and U.S. patents are incorporated into this patent. See patent application. However, such U.S. Patents and U.S. The contents of the patent applications are referenced to the extent that they do not conflict with the contents described herein and others. If there is a conflict, U.S. Patent and U.S. The conflicting content of the patent application is not referred to herein.

Although the present invention has been described in connection with various exemplary embodiments, this description should not be construed as limiting. The skilled artisan can make various modifications and combinations to the exemplary embodiments of the present invention as well as other embodiments with reference to the description. Therefore, it is intended that the appended claims cover such modifications or embodiments.

Claims (29)

A method of determining alignment between a template having a template alignment mark and a substrate having a substrate alignment mark, the method comprising: Overlaying the template and the substrate; Obtaining a plurality of alignment measurements; Identifying the deviation from the desired spatial direction of the template alignment mark and the substrate alignment mark from the plurality of alignment measurements to define an alignment deviation; And, Determining an average deviation based on the alignment deviation; and determining an alignment between the template having the template alignment mark and the substrate having the substrate alignment mark. The method of claim 1, further comprising: changing the position according to information obtained from the average deviation to obtain the desired spatial orientation measurement. Determine alignment between the substrate having the template alignment mark and the substrate having the substrate alignment mark. How to. The method of claim 1, wherein obtaining a plurality of alignment measurements includes colliding light having first and second wavelengths on both the template alignment mark and the substrate alignment mark, wherein the identifying step comprises: Determining a first alignment error of the template alignment mark with respect to the substrate alignment mark based on the alignment measurement collected at light of wavelength and the substrate based on the alignment measurement collected at light of the second wavelength with a photo detector And determining a second alignment error of the template alignment mark with respect to the alignment mark. 4. The method of claim 3, wherein determining the average deviation further comprises averaging the first and second alignment errors to determine the average deviation between the substrate having the template alignment mark and the substrate having the substrate alignment mark. How to determine the alignment. 4. The method of claim 3, wherein determining the first alignment error comprises detecting non-zeroing of the first wavelength and determining the second alignment error comprises detecting non-zeroing of the second wavelength. And determining the alignment between the template having the template alignment mark and the substrate having the substrate alignment mark. The method of claim 1, further comprising providing a first grating having a plurality of shapes to the template and providing a second grating having a plurality of markings to the substrate, wherein each of the plurality of shapes is about from an adjacent shape. Spaced apart by a first distance in the range of 1 μm to about 3 μm to define the template alignment mark, each of the plurality of markings spaced apart from an adjacent marking by a second distance in the range of about 1 μm to about 3 μm A method for determining alignment between a template having a template alignment mark and a substrate having a substrate alignment mark defining a mark. The method of claim 1, further comprising providing a first grating having a plurality of shapes to the template and providing a second grating having a plurality of markings to the substrate, wherein each of the plurality of shapes is about from an adjacent shape. A substrate having a template alignment mark and a template having a template alignment mark spaced less than 1 μm apart to define the template alignment mark, each of the plurality of markings spaced less than about 1 μm from an adjacent marking to define the substrate alignment mark How to determine the alignment of the liver. The method of claim 1, further comprising providing a first grating having a plurality of shapes to the template and providing a second grating having a plurality of markings to the substrate, wherein each of the plurality of shapes is 100 from an adjacent shape. A substrate having a template alignment mark and a template having a template alignment mark spaced apart in a range from to 1000 nm to define the template alignment mark, and each of the plurality of markings spaced from an adjacent marking in a range of 100 to 1000 nm to define the substrate alignment mark. How to determine the alignment of the liver. The method of claim 1, further comprising providing the first and second gratings to the template to define the template alignment mark and providing the third and fourth gratings to the substrate to define the substrate alignment mark. Further comprising: each of the first and second gratings comprises a plurality of shapes, each of the shapes of the first grating being spaced in the range of 1 μm to 3 μm from an adjacent shape and associated with the second grating. The shape is spaced apart from the adjacent shape in the range of 100 to 1000 nm, each of the third and fourth gratings comprises a plurality of markings, each of the markings of the third grating being spaced from the adjacent markings in the range of 1 μm to 3 μm. Each of the markings associated with the fourth grating has a template having a template alignment mark and a substrate alignment mark spaced apart in a range of 100 to 1000 nm from an adjacent marking. The method for determining the alignment. 2. The method of claim 1, wherein determining the first alignment error further comprises sensing the first wavelength of +1 and -1 order, and determining the second alignment error comprises +1 and-. Sensing an alignment of the primary second wavelength further comprising a template having a template alignment mark and a substrate having a substrate alignment mark. 4. The method of claim 3, wherein determining the first alignment further comprises comparing a positive nth order alignment measurement at the first wavelength to a negative nth order alignment measurement at the first wavelength, and wherein the second alignment error Determining an alignment between the substrate having the template alignment mark and the substrate having the substrate alignment mark further comprising comparing a positive nth order alignment measurement at the second wavelength with a negative nth order alignment measurement at the second wavelength. How to decide. 3. The method of claim 2, further comprising applying an active photocurable liquid to the substrate and contacting the active photocurable liquid with the template, wherein the repositioning is performed between the template and the active photocurable liquid. And setting the template and the substrate to be in a desired spatial direction while maintaining contact. 13. The template and substrate alignment marks of claim 12 further comprising the step of solidifying the actinic curable liquid, forming a cured liquid, and separating the template from the cured liquid. A method of determining alignment between substrates having. 13. The method of claim 12, wherein changing the position further comprises changing the position from the region overlapping both the substrate alignment mark and the template alignment mark to the active photocurable liquid that is substantially free. A method of determining alignment between a template having a template alignment mark and a substrate having a substrate alignment mark. The template of claim 1, wherein the template has a template alignment mark including first and second opposing surfaces formed with a plurality of recesses extending at a first distance from the first surface towards the second surface; A method of determining alignment between substrates having substrate alignment marks. 16. The method of claim 15, further comprising providing the template with a boundary formed around the plurality of recesses, the boundary having a second distance greater than the first distance from the first surface toward the second surface. And determining the alignment between the template having the template alignment mark and the substrate having the substrate alignment mark. The method of claim 13, wherein separating the template from the cured liquid comprises moving the template and the substrate in a direction substantially non-parallel to one another and moving the template and the substrate spaced apart from each other. And determining an alignment between the template having the template alignment mark and the substrate having the substrate alignment mark. 14. The method of claim 13, further comprising applying separation light prior to separating the cured liquid from the template, wherein the separation light alters the chemical composition of a portion of the cured liquid to the cured liquid. A method of determining alignment between a substrate having a template alignment mark and a substrate having a substrate alignment mark that reduces the adhesion of the template to the template. Imprint lithography system, body; A stage coupled to the body; A substrate coupled to the stage, the substrate having a substrate alignment mark; An imprint head coupled to the body; A template coupled to the imprint head, the template including a template alignment mark; A light source for generating light having first, second, and third wavelengths, the first and second wavelengths impinging on the substrate and template alignment marks; And, A second deviation from said desired alignment direction of said template alignment mark and said substrate alignment mark from said plurality of alignment measurements to reflect and obtain a plurality of alignment measurements therefrom from said substrate and template alignment mark to define an alignment deviation; And a detection system for sensing light having a first and second wavelength and determining an average deviation based on the alignment deviation. 20. The apparatus of claim 19, further comprising a liquid dispenser coupled to the body for depositing a plurality of droplets of active photocurable liquid on the substrate, the active photocurable liquid reacting to and impinging upon the third wavelength. And imprinted in response to said third wavelength. 20. An imprint lithography according to claim 19, wherein the template has a first and a second opposing surface and has a patterning area comprising a plurality of recesses extending a first distance from the first surface towards the second surface. system. 20. The system of claim 19, wherein each of the substrate and template alignment marks comprises a grating having a plurality of shapes, each of which is spaced apart from an adjacent shape by a distance in the range of about 1 μm to about 3 μm. 20. The system of claim 19, wherein each of the substrate and template alignment marks comprises a grating having a plurality of shapes, each of which is spaced apart from an adjacent shape by a distance of less than about 1 micrometer. 20. The system of claim 19, wherein each of the substrate and template alignment marks comprises a grating having a plurality of shapes, each of which is spaced apart from an adjacent shape by a distance in the range of about 100 to 1000 nm. 20. The substrate of claim 19, wherein each of the substrate and template alignment marks comprises first and second gratings, each of the first and second gratings having a plurality of shapes, each of the shapes of the first grating from an adjacent shape. An imprint lithography system spaced in the range of 1 μm to 3 μm and the shape associated with the second grating is spaced in the range of 100 to 1000 nm from an adjacent shape. 20. An imprint lithography system according to claim 19, wherein the detection system comprises a detector selected from a set of detectors consisting essentially of an array camera, a spectrophotometer, a CCD array, a two-axis interferometer, and a five-axis interferometer. 21. The imprint lithography system of claim 20, further comprising a force detector coupled to the imprint head to determine the force exerted on the template by contacting the droplets. 20. The imprint lithography system of claim 19, further comprising a precalibration stage, wherein the imprint head is coupled to the precalibration stage. The imprint of claim 21, wherein the template further comprises a boundary formed around the plurality of recesses, the boundary extending from the first surface toward the second surface to a second distance greater than the first distance. Lithography system.