Template, method of forming template, apparatus and method of manufacturing article

Abstract

To provide a method for forming an imprint template.SOLUTION: A hard mask layer is formed on a first surface of a template plate. An imprint lithography is performed to form a hard mask covering a first region, the patterned hard mask has: a pattern portion; and an edge portion defined in the same imprint lithography. The template plate is dry etched with the first region of the template plate converted with the patterned hard mask. An additional mask layer is formed on the patterned hard mask. Since a mesa is formed under the pattern portion while the edge portion of the hard mask is overhung onto a second region for the template plate, a wet edge process is performed in both of the patterned hard mask and the additional mask layer formed on the template plate.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to nanoimprint lithography templates, methods of forming nanoimprint lithography templates, and methods of manufacturing articles using nanoimprint lithography templates, and more particularly to nanoimprint lithography processes in semiconductor manufacturing. [Background technology]

[0002] Nanomanufacturing involves the fabrication of extremely small structures, with features on the order of 100 nanometers or less. One application in which nanomanufacturing has had a major impact is the fabrication of integrated circuits. Nanomanufacturing is becoming increasingly important as the semiconductor processing industry continues to pursue greater production yields while increasing the circuits formed per unit area on a substrate. Nanomanufacturing provides greater process control while enabling a continued reduction in the minimum feature dimensions of the structures being formed.

[0003] An exemplary nanofabrication technique in use today is commonly referred to as nanoimprint lithography. Nanoimprint lithography is useful in a variety of applications, including fabricating one or more layers of integrated devices such as CMOS logic, microprocessors, NAND flash memory, NOR flash memory, DRAM memory, MRAM, 3D cross-point memory, Re-RAM, Fe-RAM, STT-RAM, etc. Exemplary nanoimprint lithography processes are described in detail in numerous publications, such as U.S. Pat. No. 8,349,241, U.S. Pat. No. 8,066,930, and U.S. Pat. No. 6,936,194, all of which are incorporated herein by reference.

[0004] The nanoimprint lithography techniques disclosed in each of the above-mentioned U.S. patents involve forming a relief pattern in a formable (polymerizable) layer and transferring a pattern corresponding to the relief pattern into and / or onto an underlying substrate. The substrate may be coupled to a motion stage to obtain the desired positioning to facilitate the patterning process. The patterning process uses a template spaced apart from the substrate and a formable liquid applied between the template and the substrate. The formable liquid is solidified to form a solid layer having a pattern that matches the shape of the surface of the template in contact with the formable material. After solidification, the template is separated from the rigid layer to separate the template and the substrate. The substrate and solidified layer are then subjected to additional processes, such as an etching process, to transfer a relief image corresponding to the pattern in the solidified layer into the substrate. The patterned substrate is then subjected to further known steps and processes for device fabrication, including, for example, oxidation, film formation, deposition, doping, planarization, etching, formable material removal, dicing, bonding, packaging, etc. Summary of the Invention [Means for solving the problem]

[0005] A method for forming an imprint template is provided. A template plate is provided having a first surface and a second surface opposite the first surface. The first surface has a first region and a second region surrounding the first region. A hard mask layer is formed on the first surface of the template plate. Imprint lithography is performed on the hard mask layer to form a first mask used to form a patterned hard mask covering the first region of the template plate. The patterned hard mask may include a pattern portion and an edge portion defined by the same imprint lithography. The template is dry etched in the first region of the template plate covered by the patterned hard mask. An additional mask layer is formed on the patterned hard mask. The template plate is wet etched with both the patterned hard mask and the additional mask layer formed thereon to form a mesa below the pattern portion, with the edge portion of the hard mask overhanging the second region of the template plate.

[0006] The template plate may be a glass plate, and the hard mask layer may be a Cr layer. A core-out portion may be formed on the second surface and aligned with the first region. The imprint lithography may include providing an imprint resist layer on the hard mask layer over the first region of the template plate, contacting a master template with the imprint resist layer to transfer a pattern to the imprint resist layer, curing the imprint resist layer, and removing the master template from the cured imprint resist layer.

[0007] Prior to dry etching the template plate, the method may further include forming a positive photoresist layer to cover the first surface of the template, exposing the photoresist layer formed on the first region to light incident from the second surface while blocking the photoresist layer formed on the second region from being exposed by the light, and developing the positive photoresist layer to form the additional mask covering the patterned hard mask, the additional mask including a central portion and a periphery that is thinner than the central portion. The additional mask layer may be removed after wet etching the template plate and before dry etching the template plate.

[0008] The additional mask layer may include another hard mask layer, and the method may further include the following steps: a negative photoresist layer is formed to cover the first surface of the template plate; the photoresist layer formed on the first region is exposed to light incident from the second surface while blocking the photoresist layer formed on the second region from being exposed by the light; the negative photoresist layer is developed to form a photoresist mask having an outer portion covering the second region of the template plate and an inner portion covering the periphery of the edge portion of the patterned hard mask; during dry etching of the template plate, a portion of the outer portion of the photoresist mask that is thicker than the inner portion is removed; an additional hard mask layer is formed to cover the remaining photoresist mask and the patterned hard mask, and an additional photoresist layer is formed on the additional hard mask layer; the additional hard mask covering the remaining photoresist mask is removed, and the additional photoresist layer is planarized until the additional mask is formed. After wet-etching the template plate to form the mesa under the pattern portion with the edge portion overhanging the second region of the template plate, the patterned hard mask and the additional hard mask are removed. Prior to forming the patterned hard mask, a marking is formed in the second region of the template plate.

[0009] The additional mask layer may include another hard mask layer, and the method may further include the following steps: A marking may be formed in the second region of the template plate before forming the patterned hard mask; A first photoresist layer may be formed after dry etching the template plate using the patterned hard mask formed on the template plate; The photoresist layer may be exposed to light from the first side of the template plate; A second photoresist layer may be formed on the first photoresist layer; The first photoresist layer and the second photoresist layer may be exposed to light incident from the second side of the template plate; The second photoresist layer is developed to form a photoresist mask, the photoresist mask including a thick outer portion covering a portion of the first photoresist layer on the second region of the template plate and a thin portion covering a portion of the first photoresist layer around the edge of the patterned hard mask; The developed second photoresist layer; Another hard mask layer is formed; and a third photoresist layer is formed. The third photoresist layer is planarized until the additional hard mask layer on the second region of the template plate is removed, the first photoresist layer is removed, and the patterned hard mask and the additional hard mask are removed after wet etching the template plate to form the mesa under the pattern portion with the edge portion overhanging the second region of the template plate.

[0010] In one embodiment, the edge portion of the patterned hard mask has a width of about 30 μm. The edge of the mesa formed by wet etching is defined by an edge feature in the patterned hard mask formed in an imprint lithography template that is also used to define pattern features using dry etching in the first region of the template plate. Prior to performing imprint lithography on top of the hard mask, a core-out portion is formed on the second surface, the core-out portion being aligned with the first region.

[0011] An imprint template is provided having a first surface and a second surface on two opposite sides, the imprint template including a core-out portion recessed from a second surface in a first region of the imprint template, the first region being surrounded by a second region of the imprint template and including a mesa formed on the first surface in the first region, the mesa including a top having a pattern formed thereon and a bottom that is larger than the top, the difference between the top and the bottom being determined in the same imprint lithography process that defines the pattern.

[0012] These and other objects, features and advantages of the present disclosure will become apparent from a reading of the following detailed description of exemplary embodiments of the present disclosure in conjunction with the accompanying drawings and the appended claims. [Brief explanation of the drawings]

[0013] So that the features and advantages of the present invention may be understood in detail, a more particular description of the embodiments of the present invention can be had by reference to the embodiments illustrated in the accompanying drawings. It should be noted, however, that the accompanying drawings only illustrate typical embodiments of the present invention and therefore should not be considered as limiting the scope of the present invention, which may admit of other equally effective embodiments. [Figure 1]FIG. 1 is a diagram illustrating a nanoimprint lithography system. [Figure 2A] FIG. 2A illustrates the nanoimprint lithography process. [Figure 2B] FIG. 2B illustrates the nanoimprint lithography process. [Figure 2C] FIG. 2C illustrates the nanoimprint lithography process. [Figure 3A] FIG. 3A is a cross-sectional view illustrating a process for forming a template. [Figure 3B] FIG. 3B is a cross-sectional view illustrating a process for forming a template. [Figure 3C] FIG. 3C is a cross-sectional view illustrating a process for forming a template. [Figure 3D] FIG. 3D is a cross-sectional view illustrating a process for forming a template. [Figure 3E] FIG. 3E is a cross-sectional view illustrating a process for forming a template. [Figure 3F] FIG. 3F is a cross-sectional view illustrating a process for forming a template. [Figure 3G] FIG. 3G is a cross-sectional view illustrating a process for forming a template. [Figure 3H] FIG. 3H is a cross-sectional view illustrating a process for forming a template. [Figure 4A] FIG. 4A is a cross-sectional view showing a process for forming a template with submicron precision. [Figure 4B] FIG. 4B is a cross-sectional view showing a process for forming a template with submicron precision. [Figure 4C] FIG. 4C is a cross-sectional view showing a process for forming a template with submicron precision. [Figure 4D] FIG. 4D is a cross-sectional view showing a process for forming a template with submicron precision. [Figure 4E] FIG. 4E is a cross-sectional view illustrating a process for forming a template with submicron precision. [Figure 4F]FIG. 4F is a cross-sectional view illustrating a process for forming a template with submicron precision. [Figure 4G] FIG. 4G is a cross-sectional view showing a process for forming a template with submicron precision. [Figure 4H] FIG. 4H is a cross-sectional view showing a process for forming a template with submicron precision. [Figure 4I] FIG. 4I is a cross-sectional view showing a process for forming a template with submicron precision. [Figure 4J] FIG. 4J is a cross-sectional view illustrating a process for forming a template with submicron precision. [Figure 5A] FIG. 5A is a cross-sectional view showing a process for forming a template with submicron precision. [Figure 5B] FIG. 5B is a cross-sectional view showing a process for forming a template with submicron precision. [Figure 5C] FIG. 5C is a cross-sectional view showing a process for forming a template with submicron precision. [Figure 5D] FIG. 5D is a cross-sectional view showing a process for forming a template with submicron precision. [Figure 5E] FIG. 5E is a cross-sectional view illustrating a process for forming a template with submicron precision. [Figure 5F] FIG. 5F is a cross-sectional view showing a process for forming a template with submicron precision. [Figure 5G] FIG. 5G is a cross-sectional view showing a process for forming a template with submicron precision. [Figure 5H] FIG. 5H is a cross-sectional view showing a process for forming a template with submicron precision. [Figure 5I] FIG. 5I is a cross-sectional view showing a process for forming a template with submicron precision. [Figure 5J] FIG. 5J is a cross-sectional view showing a process for forming a template with submicron precision. [Figure 5K]FIG. 5K is a cross-sectional view illustrating a process for forming a template with submicron precision. [Figure 5L] FIG. 5L is a cross-sectional view showing a process for forming a template with submicron precision. [Figure 5M] FIG. 5M is a cross-sectional view showing a process for forming a template with submicron precision. [Figure 6A] FIG. 6A is a cross-sectional view showing a process for forming a template with submicron precision. [Figure 6B] FIG. 6B is a cross-sectional view showing a process for forming a template with submicron precision. [Figure 6C] FIG. 6C is a cross-sectional view showing a process for forming a template with submicron precision. [Figure 6D] FIG. 6D is a cross-sectional view showing a process for forming a template with submicron precision. [Figure 6E] FIG. 6E is a cross-sectional view showing a process for forming a template with submicron precision. [Figure 6F] FIG. 6F is a cross-sectional view showing a process for forming a template with submicron precision. [Figure 6G] FIG. 6G is a cross-sectional view showing a process for forming a template with submicron precision. [Figure 6H] FIG. 6H is a cross-sectional view showing a process for forming a template with submicron precision. [Figure 6I] FIG. 6I is a cross-sectional view showing a process for forming a template with submicron precision. [Figure 6J] FIG. 6J is a cross-sectional view showing a process for forming a template with submicron precision. [Figure 6K] FIG. 6K is a cross-sectional view showing a process for forming a template with submicron precision. [Figure 6L] FIG. 6L is a cross-sectional view showing a process for forming a template with submicron precision. [Figure 6M]FIG. 6M is a cross-sectional view showing a process for forming a template with submicron precision. [Figure 6N] FIG. 6N is a cross-sectional view illustrating a process for forming a template with submicron precision. [Figure 6O] FIG. 6O is a cross-sectional view showing a process for forming a template with sub-micron precision. [Figure 6P] FIG. 6P is a cross-sectional view showing a process for forming a template with submicron precision. [Figure 6Q] FIG. 6Q is a cross-sectional view showing a process for forming a template with submicron precision. [Figure 6R] FIG. 6R is a cross-sectional view illustrating a process for forming a template with submicron precision. [Figure 7] 7 illustrates a method of forming a template according to one embodiment. Throughout the drawings, the same reference numerals and characters, unless otherwise stated, are used to denote like features, elements, components, or portions of the illustrated embodiments. Also, while the subject disclosure will be described in detail with reference to the drawings, it is done so in connection with exemplary embodiments. It is intended that changes and modifications can be made to the exemplary embodiments described without departing from the true scope and spirit of the subject disclosure, as defined by the appended claims. DETAILED DESCRIPTION OF THE INVENTION

[0014] Flattening System 1 shows a system for nanoimprint lithography. The nanoimprint lithography system 100 is used to form a relief pattern film on a substrate 102. The substrate 102 may be coupled to a substrate chuck 104. The substrate chuck 104 may be, but is not limited to, a vacuum chuck, a pin-type chuck, a groove-type chuck, an electrostatic chuck, an electromagnetic chuck, or the like.

[0015] The substrate 102 and substrate chuck 104 may be further supported by a substrate positioning stage 106. The substrate positioning stage 106 may provide translational and / or rotational motion along one or more of the x, y, z, θ, ψ, and φ axes. The substrate positioning stage 106, substrate 102, and substrate chuck 104 may be positioned on a base (not shown). The substrate positioning stage may be part of a positioning system.

[0016] Spaced apart from the substrate 102 is a template 108 having a working surface 112 facing the substrate 102. The template 108 includes a body having a first side and a second side, one side of which has a mesa 110 (also referred to as a mold 110) extending toward the substrate 102. The mesa 110 may have the working surface 112 thereon. Alternatively, the template 108 may be formed without the mesa 110. The template 108 may be formed from materials including, but not limited to, fused silica, quartz, silicon, organic polymers, siloxane polymers, borosilicate glass, fluorocarbon polymers, metals, hardened sapphire, and the like. In an embodiment, the substrate is readily transparent to UV light. The surface 112 may be the same area size as the surface of the substrate 108. The surface 112 may be smaller than the surface of the substrate and may be used in repeated steps to pattern the surface of the substrate. Working surface 112 includes features defined by a plurality of spaced apart recesses 114 and protrusions 116, although embodiments of the present invention are not limited to such a configuration. Working surface 112 may also be a featureless surface used to form a planarizing surface.

[0017] The template 108 may be coupled to or held by the template chuck 118. The template chuck 108 may be, but is not limited to, a vacuum chuck, a pin-type chuck, a groove-type chuck, an electrostatic chuck, an electromagnetic chuck, and / or other similar chuck types. The template chuck 118 may be configured to apply a varying stress, pressure, and / or strain to the template 108 across the template 108. The template chuck 118 may include a system, such as a zone-based vacuum chuck, an actuator array, or a pressure bladder, that applies a pressure differential to the backside of the template 108 to bend and deform the template. In one embodiment, the template chuck 118 includes a zone-based vacuum chuck that can apply a pressure differential to the backside of the template to bend and deform the template, as described in further detail herein.

[0018] The template chuck 118 may be coupled to an imprint head 120 that is part of the positioning system. The imprint head 120 may be movably coupled to the bridge. The imprint head 120 may include one or more actuators, such as a voice coil motor, a piezoelectric motor, a linear motor, a nut and screw motor, etc., configured to move the template chuck 118 relative to the substrate 102 in at least the z-axis direction and potentially other directions (e.g., the x-, y-, θ-, ψ-, and φ-axes).

[0019] The nanoimprint lithography system 100 may further include a fluid dispenser 122. The fluid dispenser 122 may be movably coupled to the bridge. In an embodiment, the fluid dispenser 122 and the imprint head 120 share one or more of the overall positioning components. In an alternative embodiment, the fluid dispenser 122 and the imprint head 120 move independently of one another. The fluid dispenser 122 may be used to deposit droplets of a liquid formable material 124 (e.g., a photocurable polymerizable material) onto the substrate 102, with the volume of the deposited material varying across an area of ​​the substrate 102 based at least in part on the topographical profiles of both the substrate 102 and the template 108. Different fluid dispensers 122 may use different techniques to dispense the formable material 124. If the formable material 124 is jettable, an inkjet-type dispenser may be used to dispense the formable material. For example, thermal inkjet, microelectromechanical system (MEMS)-based inkjet, valve jet, and piezoelectric inkjet are common technologies for dispensing jettable liquids.

[0020] Nanoimprint lithography system 100 may further include a curing system including at least a radiation source 126 that directs actinic energy, such as UV radiation, along an exposure path 128. Imprint head 120 and substrate positioning stage 106 may be configured to position template 108 and substrate 102 in overlapping relationship with exposure path 128. Radiation source 126 directs actinic energy along exposure path 128 after template 108 contacts formable material 124. FIG. 1 illustrates exposure path 128 when template 108 is not in contact with formable material 124. This is done for illustrative purposes so that the relative positions of the individual components can be easily identified. Those skilled in the art will understand that exposure path 128 does not substantially change when template 108 contacts formable material 124.

[0021] Nanoimprint lithography system 100 may further include a camera 136 positioned to observe the spread of formable material 124 as template 108 contacts formable material 124 during the imprint process. FIG. 1 illustrates an optical axis 138 of the imaging field of the field camera as a dashed line. As shown in FIG. 1, nanoimprint lithography system 100 may include one or more optical components (such as a dichroic mirror, a beam combiner, a prism, a lens, a mirror, etc.) that combine actinic radiation with light to be detected by camera 136. Camera 136 may include one or more of a CCD, a sensor array, a line camera, and a photodetector configured to collect light at wavelengths indicative of contrast between areas under template 108 in contact with formable material 124 and areas under template 108 that are not in contact with formable material 124. Camera 136 may be configured to provide an image of the spread of moldable material 124 under template 108 and / or the separation of template 108 from hardened moldable material 124. Camera 136 may be configured to measure interference patterns that change as moldable material 124 spreads across the gap between surface 112 and the substrate surface.

[0022] The nanoimprint system 100 may be coordinated, controlled, and / or directed by one or more processors 140 (controllers) in communication with one or more components and / or subsystems, such as the substrate chuck 104, the substrate positioning stage 106, the template chuck 118, the imprint head 120, the fluid dispenser 122, the radiation source 126, and / or the camera 136. The processor 140 may operate based on computer-readable program instructions stored in non-transitory computer memory 142. The processor 140 may be or include one or more of a CPU, MPU, GPU, ASIC, FPGA, DSP, and a general-purpose computer. The processor 140 may be a dedicated controller or a general-purpose computing device configured to be a controller. Examples of non-transitory computer-readable memory include, but are not limited to, RAM, ROM, CD, DVD, Blu-Ray, hard drives, network-enabled storage (NAS), intranet-connected non-transitory computer-readable storage devices, and internet-connected non-transitory computer-readable storage devices.

[0023] Either or both of imprint head 120 and substrate positioning stage 106 vary the distance between template 118 and substrate 102 to define a desired volume (a bounded physical area in three dimensions) to be filled with moldable material 124. For example, imprint head 120 may apply a force to template 108 to bring template 108 into contact with moldable material 124.

[0024] Imprint process The imprint process includes the steps shown generally in Figures 2A through 2C. As shown in Figure 2A, formable material 124 in the form of droplets is dispensed onto substrate 102. As previously explained, the substrate and template surfaces have some topography that is known based on previous process operations or that is measured using a surface profilometer, AFM, SEM, or an optical surface profiler based on optical interference effects, such as the Zygo NewView 8200. The local volume density of the deposited formable material 124 varies depending on the substrate and template topography. Template 108 is then positioned in contact with formable material 124.

[0025] 2B illustrates a post-contact step after the template 108 has fully contacted the moldable material 124, but before the polymerization process begins. As the template 108 contacts the moldable material 124, the droplets combine to form a moldable material film 144 that fills the space between the template 108 and the substrate 102. Preferably, the filling process occurs in a uniform manner without air or bubbles being trapped between the template 108 and the substrate 102 to minimize unfilled defects. The polymerization process, or curing, of the moldable material 124 may be initiated with actinic radiation (e.g., UV radiation). For example, the radiation source 126 of FIG. 1 provides actinic radiation that cures, solidifies, and / or crosslinks the moldable material film 144, thereby defining a cured pattern layer 146 on the substrate 102. Curing of the moldable material film 144 may also be initiated using heat, pressure, a chemical reaction, other types of radiation, or any combination thereof. Once cured, patterned layer 146 is formed, from which template 108 is separated. Figure 2C shows cured patterned layer 146 on substrate 102 after separation of template 108.

[0026] Template structure and template manufacturing process During the imprinting process, the template 108 is brought into complete contact with the formable material 124 provided on the substrate 102. More specifically, the formable material 124 is in complete contact with a mold 110 formed on the template 108. The mold 110 may include a pattern to be transferred to the formable material 124. The mold 110 may also be referred to as a mesa 110 formed on the contact side of the template 108. FIGS. 3A-3G illustrate a process for forming a template. As shown in FIG. 3A, a template plate 300 is provided, e.g., a glass plate made of a glass-based material. Preferably, and optionally, the template plate 300 includes a core-out portion 301 recessed from the non-contact side of the template plate 300. A hard mask layer 302, e.g., a Cr layer, is formed on the contact side of the template plate 300. A photoresist 303 is formed on the hard mask layer 302 and patterned. The photoresist 303 may be formed by applying a photoresist layer on the hard mask layer 302 and patterning the photoresist layer using an etching process. The patterned resist layer 303 includes a central portion and a peripheral portion.

[0027] A wet etching process is performed on the template plate 300 to define a main portion 300a, a mesa 300m protruding from a central portion of the main portion 300a, and an off-mesa mark 300o protruding from a peripheral portion of the main portion 300a. As shown in FIG. 3B, the remaining hard mask 302 and the remaining photoresist 303 after the wet etching process include edge portions overhanging the main portion 300a. Then, as shown in FIG. 3C, the remaining hard mask 302 and the remaining photoresist 303 are removed to expose the mesa 300m. In FIG. 3D, another hard mask layer 304 is formed to cover the main portion 300a, the mesa 300m, and the off-mesa mark 300o. An imprint process is performed on the mesa 300m. For example, as shown in FIG. 3E, a moldable material 305 is provided on the hard mask layer 304 on the mesa 300m. As shown in FIG. 3E, patterned master template 306 is contacted with moldable material 305 to transfer the pattern of master template 306 to moldable material 305. For example, radiation source 126 of FIG. 1 provides actinic radiation that cures, solidifies, and / or crosslinks moldable material 305, defining a cured pattern layer 305 on template plate 300. Also shown in FIG. 3E, curing of moldable material 305 can be initiated using heat, pressure, a chemical reaction, other types of radiation, or any combination thereof. As shown in FIG. 3F, master template 306 is removed. In FIG. 3G, a dry etching process is performed using patterned material 305 as a mask to remove exposed portions of hard mask layer 304 and portions of mesas 300m beneath the exposed portions of hard mask layer 304. In an embodiment, an etching process is used to transfer the pattern of the hardened photoresist 305 to pattern the hard mask layer 304, and a dry etching process is used to transfer the patterned hard mask to the mesa 300m of the template plate 300. The dry etching process results in a pattern 300p on the top portion of the mesa 300m.Then, as shown in Figure 3H, the remaining moldable material 305 and remaining hard mask layer 304 are removed to form template 30 with pattern 300p on the top portion of mesa 300m.

[0028] As shown in FIGS. 3A-3C, mesa 300m is defined by a wet etching process using photoresist 303 as a mask, and as shown in FIGS. 3D-3G, pattern 300p is formed by a dry etching process similar to that described in the imprint lithography process. When the wet etching mask and the dry etching mask are created in separate processes, a certain degree of misalignment error inevitably exists. This misalignment error is on the order of ±1.5 μm. This error is caused by the features on the mesa defined using the dry etching process and the edges of the mesa defined using the wet etching process. The dry etching process is used to etch depths on the order of 100 nm, and the wet etching process is used to etch micron-scale depths.

[0029] 4A-4I are cross-sectional views illustrating a process for forming a template free of alignment errors caused by processes such as those illustrated in FIGS. 3A-3H. In FIG. 4A, a template plate 400 is provided, e.g., a plate made of a glass-based material (which may be fused silica, quartz, silicon, an organic polymer, a siloxane polymer, a borosilicate glass, a fluorocarbon polymer, a metal, a hardened sapphire, a 6025 photomask substrate, and / or the like that is transparent to actinic radiation). The template plate 400 may have a polygonal, square, rectangular, or circular disk shape, including a first surface on which a mold is formed and a second surface opposite the first surface. A core-out portion 401 recessed from the second surface is formed in a central portion of the template plate 400. In one embodiment, the central core-out portion 401 has a diameter of approximately 64 mm. In FIG. 4B, a hard mask layer 402 is disposed on the template plate 400. The hard mask layer 402 may be formed of chromium (Cr). The hard mask layer 402 may have a thickness of about 5-30 nm. The hard mask layer 402 may be applied using standard coating techniques such as sputtering, evaporation, chemical vapor deposition, electroplating, electroforming, dip coating, spin coating, slot die coating, inkjet printing, etc. The formable material 124 is then applied over the hard mask layer 402.

[0030] In FIG. 4C, an imprint lithography process is performed to form a photoresist or moldable material mask 403. The imprint lithography process includes providing moldable material 124 on hard mask layer 402 as shown in FIG. 4B, bringing master template 404 into full contact with moldable material 124 as shown in FIG. 4C, and transferring the pattern of master template 404 to the moldable material to form dry etch mask 403. Dry etch mask 403 may be defined by pattern portion 403p surrounded by edge portion 403e and rim portion 403r surrounding edge portion 403e. As shown in FIG. 4C, master template 404 may be used to define the edge of wet etch (EWE) and pattern feature 403p of mask 403 in a single patterning step. The EWE is the outer edge of edge portion 403e. The EWE is used to define the mesa edge during the wet etching process so that there is no alignment error between the feature and the mesa edge EM. In the example shown in FIG. 4C, the edge portion 403e, i.e., the distance between the edge of the wet etching (EWE) and the mesa edge (EM), is approximately 30 μm. The rim portion 403r is sufficiently thinner than the edge portion 403e. The master template 404 is removed from the dry etching mask 403, and a dry etching process is performed to define the hard mask layer 402. In the embodiment shown in FIG. 4C, the rim portion 403r is sufficiently thin so that the portion of the hard mask layer 403 below the rim portion 403r is removed by the dry etching process or a descumming process used prior to the dry etching process to remove a thin portion of the dry etching mask 403 before the dry etching. As shown in FIG. 4E, the hard mask 402 is defined by a pattern 402a surrounded by the edge portion 402e.

[0031] In FIG. 4F, a photoresist mask layer 405 is formed on the first side of the template plate 400 to cover the hard mask layer 402 and the exposed template plate 400. Light (arrows shown in the drawing) is incident from the second side of the template plate 400. The template plate 400 is transparent to light. Therefore, the light is incident through the template plate 400 and onto the photoresist layer 405. A photomask 406 is disposed between the light source and the template plate 400. As shown in FIG. 4F, the photomask 406 blocks light from entering through the pattern portion 402p and blocks some of the light incident on the edge portion 402e, while allowing light to travel outside the edge portion 402e. In an embodiment, the photomask 406 allows some light to enter part of the edge portion 402e. The photoresist layer 405 is then developed to provide a photoresist mask 405 with a stepped-down rim, as shown in FIG. 4G. In other embodiments, the photoresist mask 405 may be formed without step-down features, provided that light is completely blocked from impinging on the edge portion 402e. The photomask 406 is aligned with the patterned hard mask layer 402 such that the edges of the masking portions of the photomask 406 are between the outer edges of the edge portion EWE and the outer edges of the pattern EM. This reduces the alignment requirement of the photomask 406 relative to the template plate 400; the edge of the blocking portion of the photomask 406 only needs to be within the distance between the EWE and the pattern portion 403p. The hard mask 402 is not etched away or substantially thinned while the photoresist mask layer 405 is being developed. If the photomask 406 is perfectly aligned with the edge portion 102e and / or the edge portion 402, there will be no step-down rim.

[0032] In FIG. 4H, a wet etching process is performed to remove the exposed portion of the template plate 400. The isotropic wet etching process also removes the portion of the template plate 400 below the hard mask layer 402. As shown in FIG. 4H, the sidewalls of the mesa 400m have a curved shape with a narrow top and a wide bottom. In the embodiment shown in FIG. 4H, the mesa 400m has a top surface that is substantially the same size as the patterned portion 402p of the hard mask layer 402p, and the edge of the hard mask layer 402e directly above the edge portion 402e and the photoresist mask 405 overhang the main portion 400a of the template plate 400. Then, as shown in FIG. 4H, the photoresist mask 405 is removed to expose the hard mask layer 402. In FIG. 4I, a dry etching process is performed using the hard mask layer 402 on the mesa 400m to pattern the mesa 400m. In Figure 4J, hard mask layer 402 is removed to form mesa 400m, i.e., mold-containing template 40, with the pattern from master template 404 used in Figure 4C. Hard mask layer 402 and photoresist mask 405 are made of a material that is substantially etch-resistant to the wet etching process used to form mesa 400m relative to the isotropic wet etch rate of template plate 400.

[0033] The template 40 fabricated by the process shown in Figures 4A-4J controls the position of the mesas and patterns in the same dry etching step in imprint lithography. Therefore, both the mesas and patterns are formed with submicron or nanoscale precision. The alignment errors that occur in the template 30 fabricated by the process shown in Figures 3A-3G no longer exist.

[0034] 5A-5M are cross-sectional views illustrating a process for fabricating a template according to another embodiment. The steps illustrated in FIGS. 5A-5D are the same as those illustrated in FIGS. 4A-4D. The steps in FIG. 5E are similar to those illustrated in FIG. 4E, except that the photoresist layer 505 is selective from a negative-tone photoresist material. That is, upon exposure, the exposed portions remain after development, while the unexposed portions of the photoresist layer 505 are removed by development. As illustrated in FIG. 5F, the exposed portions of the photoresist layer 505 remain on the template plate 500. The remaining photoresist layer 505 may have a stepped structure with a thin inner rim covering part of the edge portion of the hard mask layer 505 and a thicker portion directly adjacent to the template plate 500. As illustrated in FIG. 5G, a dry etching process is performed to transfer the pattern of the hard mask layer 502 to the top portion of the template plate 500. In embodiments, prior to using the dry etching process, the thin inner rim of the photoresist layer may be removed in a descumming process that removes the thin layer of photoresist while leaving the thick layer of photoresist intact.

[0035] In FIG. 5H, another hard mask layer 507 is formed to cover the photoresist layer 505, the exposed hard mask layer 502, and the exposed template plate 500. As shown in FIG. 5I, another photoresist layer 508 is formed on the hard mask layer 507 and planarized. An etching process is then performed to remove the portions of the hard mask layer 507 covering the photoresist layer 508 and the photoresist layer 506, resulting in the features shown in FIG. 5J. In FIG. 5K, the photoresist layer 506 is removed. As shown in FIG. 5L, a wet etching process is performed to form the mesa 500m. Then, the hard mask layers 502 and 507 are removed, forming the template 50 with the patterned mesa 500m, as shown in FIG. 5M. The process shown in FIGS. 5A-5M defines the mesa edge and pattern in the same dry etching step for imprint lithography, as shown in FIG. 5C. As a result, both the pattern and edge precision of the wet etching can be achieved on the submicron or nanoscale. In this embodiment, an additional hard mask layer 507 is formed. The increased thickness prevents the mesa pattern from being etched, damaged, or removed in the wet etching process, especially when the wet process is performed at a faster rate.

[0036] 6A-6R illustrate another exemplary process for forming a template. In FIG. 6A, a template plate 600 is provided. The template plate 600 is made of a glass-based material and is transparent to the light used in the imprint and lithography processes. For example, the template plate is transparent to at least ultraviolet (UV) light. The template plates 300, 400, and 500 described above are also transparent to the light used in the imprint lithography process. The template plate 600 includes a first surface on which a mesa, i.e., a mold having a pattern, is formed, and a second surface opposite the first surface. As shown in FIG. 6A, a core-out portion 601 may be recessed from the surface of the second surface. In FIG. 6B, a hard mask layer 602 is formed to cover the first surface of the template plate 600. The hard mask layer 602 may be made of, for example, Cr. In FIG. 6C, a photoresist mask 603 is formed and patterned on the hard mask layer 602. Photoresist mask 603 includes openings that expose hard mask layer 602 near the edges of template plate 600 to define off-mesa alignment marks. An etching process is performed to remove the exposed portions of the hard mask layer 602 and the portions of the template plate 600 covered by the exposed portions of the hard mask layer 602. As shown in Figure 6D, grooves are formed near the edges of the template plate 600 that are recessed from the surface of the first side. In Figure 6E, the photoresist mask 603 and the hard mask layer 602 are removed to result in off-mesa alignment marks 600o that are recessed from the surface of the second side of the template plate 600.

[0037] In FIG. 6F, another hard mask layer 604 is formed on the template plate 600, including the off-mesa alignment marks 600o. In FIG. 6G, an imprint lithography process is performed to form an imprint mask 605, including the pattern transferred from the master template 606 and wet etch edges surrounding the pattern. The imprint mask 605 may be aligned using the off-mesa alignment marks 600o. The master template 606 is removed, and a dry etching process is performed to remove portions of the hard mask layer 604 not covered by the imprint mask 605 and portions of the template plate 600 below the exposed hard mask layer 604. As a result, as shown in FIG. 6H, during the dry etching process, portions of the template plate 600 covered by the photoresist layer 605 protrude from the surrounding portions of the template plate 600.

[0038] In FIG. 6I, a photoresist layer 607 is formed to cover the exposed template plate 600 and the remaining hard mask layer 604. The photoresist layer 607 is planarized. Light, indicated by arrows, is incident on the photoresist layer 607 from the first side of the template plate 600. Another photoresist layer 608 is formed on the planarized photoresist layer 607. As shown in FIG. 6J, light is incident on the photoresist layers 607 and 608 from the second side of the template plate 600 using a photomask 609 positioned between the template plate 600 and a light source. The photomask 609 includes light-blocking portions aligned with the protruding portions of the template plate 600, leaving the photoresist layers 607 and 608 exposed at the edges of the protruding portions of the template plate 600. The exposed portions of the photoresist layers 607 and 608 are developed. The photoresist layer 607 is not removed because it was previously exposed. The development process removes a central portion of photoresist layer 608 but does not remove a substantial portion of photoresist layer 607. As shown in Figure 6K, after the development process, photoresist layer 608 has an opening and may have a stepped inner edge. The opening exposing the portion of photoresist layer 607 covers a major portion of hard mask layer 604 and the patterned features of the template plate, and covers the stepped inner edge of photoresist layer 608.

[0039] An etching process is performed to remove the remaining photoresist layer 608, the exposed portions of photoresist layer 607, and the portions of photoresist layer 607 covered by the inner edge of photoresist layer 608, resulting in the features shown in FIG. 6L. In FIG. 6L, hard mask layer 604 and the patterned features of template plate 600 are exposed, with the template plate 600 surrounding the patterned features still covered by the remaining photoresist layer 607. In FIG. 6M, an additional hard mask layer 610 is formed to cover photoresist layer 607, the exposed hard mask layer 604, and the patterned features of template plate 600. As a result, the fine-patterned features are covered with an increased thickness of hard mask material to further protect the fine-patterned features from damage during subsequent processes.

[0040] In FIG. 6N, another photoresist layer 611 is formed and planarized on the hard mask layer 610. An etching process is performed to remove portions of the hard mask layer 610 until the photoresist layer 607 is exposed, as shown in FIG. 6O. The photoresist layer 607 is removed, exposing portions of the template plate 600 surrounding the patterned feature, as shown in FIG. 6P. A wet etching process is performed to form mesa 600m. As shown in FIG. 6Q, the edges of the hard mask layers 610 and 604 overhang portion 600a of the template plate 600. Then, as shown in FIG. 6R, the hard mask layers 610 and 604 are removed to form a template 60 including a flat portion 600a, a mesa 600m with a desired pattern 600p, and an off-mesa alignment mark 600o recessed from the surface of the flat portion 600a.

[0041] FIG. 7 illustrates a method for forming a template through the process illustrated in FIGS. 4A-4I, 5A-5M, or 6A-6R. In step S701, a template plate is provided. The template has a first surface and a second surface opposite the first surface. In step S702, a hard mask layer is formed on the first surface of the template plate. In step S703, an imprint lithography process is performed on the hard mask layer to form a hard mask covering a predetermined area of ​​the template plate. The hard mask includes a pattern portion defined by the same imprint lithography process and an edge portion surrounding the pattern portion. In step S704, a dry etching process is performed on the first area covered by the patterned hard mask. In step S705, an additional mask layer is formed on the patterned hard mask. In step S706, a wet etching process is performed on the template plate with the patterned hard mask and the additional mask layer formed thereon to form a mesa under the patterned portion, with the edge portion of the hard mask overhanging the second region of the template plate. Then, in step S707, the patterned hard mask and the additional mask layer are removed to form a template with a mesa containing the patterned feature formed thereon. In the method shown in FIG. 7, the patterned feature and the edge portion of the mesa are defined in the same imprint lithography process with submicron or nanoscale accuracy. Therefore, alignment errors that occur in the process of defining the edge portion with wet etching no longer exist.

[0042] Further modifications and alternative embodiments of various aspects will be apparent to those skilled in the art upon consideration of this description. Accordingly, this description should be construed as illustrative only. It should be understood that the forms shown and described herein should be construed as example embodiments. Elements and materials may be substituted for those illustrated and described herein, components and processes may be reversed, and certain features may be utilized independently, all of which will be apparent to those skilled in the art after having the benefit of this description.

Claims

1. A method for forming an imprint template, comprising: providing a template plate having a first surface and a second surface opposite to the first surface, wherein the first surface has a first region and a second region surrounding the first region; forming a hard mask layer on the first surface of the template plate; performing imprint lithography on the hard mask layer to form a first mask used to form a patterned hard mask covering the first region of the template plate, wherein the patterned hard mask has a pattern portion and an edge portion defined by the same imprint lithography; dry etching the template plate in the first region of the template plate covered by the patterned hard mask; forming an additional mask layer on the patterned hard mask; wet etching both the patterned hard mask and the additional mask layer formed thereon to form a mesa under the pattern portion while the edge portion of the hard mask overhangs on the second region of the template plate; A method characterized by comprising the above steps.

2. The method according to claim 1, wherein the template plate includes a glass plate.

3. The method according to claim 1, wherein the hard mask layer includes a Cr layer.

4. The method according to claim 1, further comprising forming a core-out portion on the second surface, wherein the core-out portion is aligned with the first region.

5. Performing imprint lithography further comprises: providing an imprint resist layer on the hard mask layer on the first region of the template plate; bringing a master template into contact with the imprint resist layer to transfer a pattern to the imprint resist layer; curing the imprint resist layer; removing the master template from the cured imprint resist layer. The method according to claim 1, characterized by further comprising the above steps.

6. Before dry etching the template plate, To cover the first surface of the template plate, forming a positive photoresist layer; Exposing the positive photoresist layer formed on the first region with light incident from the second surface while blocking the positive photoresist layer formed on the second region from being exposed by the light; Developing the positive photoresist layer to form the additional mask that covers the patterned hard mask, the additional mask including a central portion and a peripheral portion thinner than the central portion; The method according to claim 1, further comprising.

7. The method according to claim 5, further comprising removing the additional mask layer after wet etching the template plate and before dry etching the template plate.

8. The method according to claim 1, wherein the additional mask layer includes another hard mask layer.

9. To cover the first surface of the template plate, forming a negative photoresist layer; Exposing the negative photoresist layer formed on the first region with light incident from the second surface while blocking the negative photoresist layer formed on the second region from being exposed by the light; Developing the negative photoresist layer to form a photoresist mask having an outer portion covering the second region of the template plate and an inner portion covering the periphery of the edge portion of the patterned hard mask; Removing a part of the outer portion thicker than the inner portion of the photoresist mask while dry etching the template plate; Forming an additional hard mask layer to cover the remaining photoresist mask and the patterned hard mask; Forming an additional negative photoresist layer on the additional hard mask layer; Planarizing the additional negative photoresist layer until the additional hard mask covering the remaining photoresist mask is removed and the additional mask is formed. After wet-etching the template plate to form the mesa under the pattern portion in a state where the edge portion overhangs on the second region of the template plate, removing the patterned hard mask and the additional hard mask; The method according to claim 8, further comprising.

10. The method according to claim 9, further comprising forming a marking on the second region of the template plate before forming the patterned hard mask.

11. Forming a marking on the second region of the template plate before forming the patterned hard mask; After dry-etching the template plate using the patterned hard mask formed on the template plate, forming a first photoresist layer; Exposing the first photoresist layer with light from the first surface of the template plate; Forming a second photoresist layer on the first photoresist layer; Exposing the first photoresist layer and the second photoresist layer with light incident from the second surface of the template plate; Developing the second photoresist layer to form a photoresist mask, the photoresist mask including a thick outer portion covering a part of the first photoresist layer on the second region of the template plate and a thin portion covering a part of the first photoresist layer around the edge portion of the patterned hard mask; Removing the developed second photoresist layer; Forming another hard mask layer; Forming a third photoresist layer; Flattening the third photoresist layer until the other hard mask layer on the second region of the template plate is removed; Removing the first photoresist layer; After wet-etching the template plate to form the mesa under the pattern portion in a state where the edge portion overhangs on the second region of the template plate, removing the patterned hard mask and the additional hard mask; The method according to claim 8, further comprising

12. The method according to claim 1, wherein the edge portion of the patterned hard mask has a width of about 30 μm.

13. The method according to claim 1, wherein the edge of the mesa formed by wet etching is defined by an edge feature in the patterned hard mask formed by an imprint lithography template that is also used to define a pattern feature by dry etching in the first region of the template plate.

14. The method according to claim 1, further comprising forming a core-out portion on the second surface before performing imprint lithography on the top of the hard mask, wherein the core-out portion is aligned with the first region.

15. An imprint template having a first surface and a second surface on two opposite surfaces, A core-out portion recessed from the second surface in a first region of the imprint template, wherein the first region is surrounded by a second region of the imprint template, and A mesa formed on the first surface in the first region, Comprising The mesa Has a top with a pattern formed thereon, A bottom larger than the top, Including An imprint template, wherein the difference between the top and the bottom is determined in the same imprint lithography process that defines the pattern.

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