Method, planarization system, and method for manufacturing an article

Abstract

To provide a planarization method in semiconductor manufacturing.SOLUTION: The method includes generating at least one crack at a point on an edge of a stack of at least a substrate and a super straight, propagating the cracks along the perimeter, and moving the super straight against the substrate so as to complete the separation of the super straight from the substrate.SELECTED DRAWING: Figure 9

Description

Technical Field

[0001] The present disclosure relates to substrate processes, and more particularly, to surface planarization in semiconductor manufacturing.

Background Art

[0002] Planarization techniques are useful in manufacturing semiconductor devices. For example, the process for creating a semiconductor device typically involves repeatedly adding material to and removing material from a substrate. This process can produce a layered substrate with irregular height variations (i.e., topography), and as more layers are added, the substrate height variations can increase. Height variations can negatively impact the ability to add additional layers to the layered substrate. Separately, a semiconductor substrate (e.g., a silicon wafer) itself is not always perfectly flat and can include initial surface height variations (i.e., topography). One way to address this problem is to planarize the substrate during the deposition steps. Various lithographic patterning methods benefit from patterning on a planar surface. In ArFi laser-based lithography, planarization improves the depth of focus (DOF), critical dimension (CD), and CD uniformity. In extreme ultraviolet lithography (EUV), planarization improves feature placement and DOF. In nanoimprint lithography (NIL), planarization improves feature filling and CD control after pattern transfer.

[0003] A planarization technique, sometimes referred to as inkjet-based adaptive planarization (IAP), involves dispensing a variable droplet pattern of a polymeric material between a substrate and a superstrate, where the droplet pattern varies depending on the substrate topography. The superstrate is then contacted with the polymeric material, after which the material is polymerized on the substrate and the superstrate is removed. Improvements to planarization techniques, including the IAP technique, are desired, for example, to improve overall wafer processing and semiconductor device manufacturing.

Summary of the Invention

[0004] A method is provided. The method includes generating at least one crack at a point on an edge of a stack of at least a substrate and a superstrate, propagating the crack along an outer periphery, and moving the superstrate relative to the substrate to complete separation of the superstrate from the substrate. The method may further include introducing a positive fluid pressure between the substrate and the superstrate at the point on the edge to generate the crack. The positive fluid pressure includes a flow of clean dry air, helium, or nitrogen. The method may further include holding the superstrate on a superstrate chuck with a negative fluid pressure and applying a high flow of negative fluid pressure to a peripheral zone on the superstrate to propagate the crack along the edge of the stack.

[0005] While the high flow of negative fluid pressure is applied to the peripheral zone on the superstrate, the positive fluid pressure is continuously introduced into the separated portion. The superstrate may be moved in a direction away from the substrate by the superstrate chuck. The method may further include applying a negative fluid pressure to a central zone on the superstrate to complete separation of the superstrate from the substrate by the superstrate chuck. The method may further include applying a force to the point on the edge of the superstrate to generate the crack. Other cracks may be generated by applying a positive fluid pressure between the substrate and the superstrate at other points on the edge of the stack. The force may be applied by introducing a positive fluid pressure or mechanical contact.

[0006] The method may further include laminating the substrate and the superstrate such that the superstrate includes an overhanging edge portion, and applying a force to the overhanging edge portion to generate a crack. Other edge portions of the superstrate may be aligned with notches of the edge portion of the substrate, and a force is applied to the other edge portions to generate other cracks between the substrate and the superstrate.

[0007] A chucking system is also provided. The system includes a superstrate chuck configured to hold the superstrate with a negative fluid pressure, and a force source configured to apply a force to a point on an edge of the superstrate laminated with the substrate to generate a crack between the substrate and the superstrate at the point of the edge. The superstrate chuck includes a land pattern, and one of the lands located near an edge of the superstrate chuck is recessed below another land located inside the superstrate chuck so as to allow the superstrate to bend toward the superstrate chuck while generating the crack. The chucking system may further include a substrate chuck configured to hold the substrate with a negative fluid pressure. The substrate chuck includes a land pattern, and one of the lands located at an edge of the substrate chuck is recessed below another land located inside the substrate chuck so as to allow the substrate to bend toward the substrate while generating the crack.

[0008] The force supply source includes a mechanism for generating a lateral mechanical pressing force or a source for supplying a positive fluid pressure towards the edge of the super straight. The substrate includes a notch disposed at its edge, and the force supply source includes a source for supplying a negative fluid pressure applied to the super straight through the notch. The chucking system may further include a source for supplying a negative fluid pressure for applying the negative fluid pressure to the super straight through the super straight chuck. The super straight chuck is configured to hold the super straight such that the super straight includes an overhanging portion. The force supply source is configured to apply a force to the overhanging portion of the super straight to generate the crack.

[0009] A method of manufacturing an article is provided. The method includes forming a cured material laminated between a substrate and a super straight, generating at least one crack at a point at an edge between the substrate and the super straight, propagating the crack along the outer periphery, and separating the super straight from the cured material.

[0010] These and other objects, features, and advantages of the present disclosure will become apparent by reading the following detailed description of the exemplary embodiments of the present disclosure in conjunction with the accompanying drawings and the provided claims.

Brief Description of the Drawings

[0011] To enable a more detailed understanding of the features and advantages of the present invention, a more specific description of the embodiments of the present invention may be made with reference to the embodiments shown in the accompanying drawings. However, it should be noted that the accompanying drawings only show typical embodiments of the present invention, and thus the present invention should not be considered as limiting the scope of the present invention as other equally effective embodiments are acceptable.

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[0025] Throughout the drawings, unless otherwise specified, the same reference numerals and characters are used to denote similar features, elements, components, or parts of the illustrated embodiments. Further, while this disclosure is described in detail with reference to the drawings, it is done so in relation to exemplary embodiments that are illustrative. It is intended that changes and modifications can be made to the described exemplary embodiments without departing from the true scope and spirit of the disclosure as defined by the appended claims.

DETAILED DESCRIPTION OF THE INVENTION

[0026] Planarization system FIG. 1 shows a system for planarization. The planarization system 100 is used to planarize a film on a substrate 102. The substrate 102 can be coupled to a substrate chuck 104. The substrate chuck 104 may be a vacuum chuck, a pin-type chuck, a groove-type chuck, an electrostatic chuck, an electromagnetic chuck, etc., but is not limited thereto.

[0027] The substrate 102 and the substrate chuck 104 can be further supported by a substrate positioning stage 106. The substrate positioning stage 106 can provide translational and / or rotational movement along one or more of the x-, y-, z-, θ-, ψ, and φ-axes. Also, the substrate positioning stage 106, the substrate 102, and the substrate chuck 104 may be positioned on a base (not shown). The substrate positioning stage may be part of a positioning system.

[0028] Spaced apart from the substrate 102 is a superstrate 108 having a working surface 112 facing the substrate 102. The superstrate 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 one embodiment, the superstrate is readily transparent to UV light. The surface 112 is generally the same area size as, or slightly smaller than, the surface of the substrate 108.

[0029] The superstrate 108 may be coupled to or held by a superstrate chuck 118. The superstrate chuck 118 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 superstrate chuck 118 can be configured to apply stress, pressure, and / or strain varying across the superstrate 108 to the superstrate 108. In one embodiment, the superstrate chuck is also readily transmissive to UV light. The superstrate chuck 118 may include a system such as a zone-based vacuum chuck, an actuator array, a pressure bladder, etc., which can apply a pressure differential to the back surface of the superstrate 108 to curve and deform the template. In one embodiment, the superstrate chuck 118 includes a zone-based vacuum chuck that can apply a pressure differential to the back surface of the superstrate and curves and deforms the superstrate as described in more detail herein.

[0030] The super straight chuck 118 can be coupled to a planarization head 120 that is part of a positioning system. The planarization head 120 can be movably coupled to a bridge. The planarization head 120 can include one or more actuators such as voice coil motors, piezoelectric motors, linear motors, nut and screw motors, configured to move the super straight chuck 118 relative to the substrate 102 in at least the z-axis direction and potentially other directions (e.g., x, y-, θ-, ψ-, φ-axes).

[0031] The planarization system 100 can further include a fluid dispenser 122. Also, the fluid dispenser 122 can be movably coupled to the bridge. In one embodiment, the fluid dispenser 122 and the planarization head 120 share one or more of all the positioning components. In an alternative embodiment, the fluid dispenser 122 and the planarization head move independently of each other. 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, and the volume of the deposited material varies across regions of the substrate 102 based at least in part on its topographic profile. Different fluid dispensers 122 can use different techniques to dispense (dispense, supply) the formable material 124. If the formable material 124 is jetable, an inkjet type dispenser can be used to dispense the formable material. For example, thermal inkjetting, microelectromechanical system (MEMS)-based inkjetting, valve jet, and piezoelectric inkjetting are common techniques for dispensing jetable liquids.

[0032] The planarization system 100 may further include a curing system that directs actinic energy, such as UV radiation, along an exposure path 128. The planarization head 120 and the substrate positioning state 106 may be configured to position the superstrate 108 and the substrate 102 in alignment with the exposure path 128. The radiation source 126 sends actinic energy along the exposure path 128 after the superstrate 108 contacts the formable material 128. FIG. 1 shows the exposure path 128 when the superstrate 108 is not in contact with the formable material 124. This is done for illustrative purposes so that the relative positions of the individual components can be easily identified. One skilled in the art will understand that the exposure path 128 does not substantially change when the upper plate 108 contacts the formable material 124.

[0033] The planarization system 100 may further include a camera 136 arranged to view the spread of the formable material 124 when the superstrate 108 contacts the formable material 124 during the planarization process. FIG. 1 shows the optical axis 138 of the image field of the field camera. As shown in FIG. 1, the planarization system 100 may include one or more optical elements (such as dichroic mirrors, beam combiners, prisms, lenses, mirrors, etc.) that combine the actinic rays and the light detected by the camera 136. The camera 136 may include one or more of a CCD, a sensor array, a line camera, and a photodetector configured to collect light at a wavelength that shows the contrast between the area under the superstrate 108 in contact with the formable material 124 and the area under the superstrate 108 not in contact with the formable material 124. The camera 136 may be configured to provide an image of the spread of the formable material 124 under the superstrate 108 and / or the separation of the superstrate 108 from the cured formable material 124. Also, the camera 136 may be configured to measure the interference fringes that change as the formable material 124 spreads into the gap between the surface 112 and the substrate surface.

[0034] The planarization system 100 can be adjusted, controlled, and / or directed by one or more processors 140 (controllers) that communicate with one or more components and / or subsystems such as a substrate chuck 104, a substrate positioning stage 106, a super straight chuck 118, a planarization head 120, a fluid dispenser 122, a radiation source 126, and / or a camera 136. The processor 140 can operate based on instructions in a computer-readable program stored in a non-transitory computer memory 142. The processor 140 can be or can include one or more of a CPU, an MPU, a GPU, an ASIC, an FPGA, a DSP, and a general-purpose computer. The processor 140 can be a general-purpose controller or a general-purpose computing device configured to be a controller. Examples of non-transitory computer-readable memories include, but are not limited to, RAM, ROM, CD, DVD, Blu-Ray, hard drives, network-connected attached storage (NAS), intranet-connected non-transitory computer-readable storage devices, and internet-connected non-transitory computer-readable storage devices.

[0035] During operation, the planarization head 120, the substrate position stage 106, or both change the distance between the super straight 118 and the substrate 102 to define a desired space (a bounded physical spread in three dimensions) filled with the formable material 124. For example, the planarization head 120 is moved toward the substrate so that the super straight contacts and spreads the droplets of the formable material 124, applying a force to the super straight 108, as described in more detail herein.

[0036] Planarization process The planarization process includes the steps (processes) schematically shown in FIGS. 2a - 2c. As shown in FIG. 2a, the formable material 124 is dispensed in the form of droplets onto the substrate 102. As previously described, the substrate surface may be known based on previous process operations or may be measured using a profilometer, AFM, SEM, or an optical surface profiler based on optical interference effects such as the Zygo NewView 8200 and has some topography. The local volume density of the deposited formable material 124 varies according to the substrate topography. Next, the superstrate 108 is positioned to contact the formable material 124.

[0037] Figure 2b shows a post-contact step after the superstrate 108 is in complete contact with the formable material 124 but before the polymerization process begins. When the superstrate 108 contacts the formable material 124, the droplets merge to form a film 144 of the formable material that fills the space between the superstrate 108 and the substrate 102. Preferably, the filling process is performed uniformly such that no air or gas bubbles are trapped between the superstrate 108 and the substrate 102 in order to minimize unfilled defects. The polymerization process or curing of the formable material 124 can be initiated by actinic radiation (e.g., UV radiation). For example, the radiation source 126 of FIG. 1 can provide actinic radiation that cures, solidifies, and / or crosslinks the film 144 of the formable material to define a cured planarization layer 146 on the substrate 102. Alternatively, the curing of the film 144 of the formable material may be initiated by using heat, pressure, chemical reactions, other types of radiation, or any combination thereof. Once cured, the planarization layer 146 is formed and the superstrate 108 can be separated therefrom. FIG. 2c shows the cured planarization layer 146 on the substrate 102 after separation of the superstrate 108. The substrate and the cured layer can then undergo additional known steps and processes for device (article) manufacturing, including, for example, patterning, curing, oxidation, layer formation, deposition, doping, planarization, etching, removal of the formable material, dicing, bonding, and packaging. The substrate may be processed to manufacture a plurality of articles (devices).

[0038] Spread, filling, and curing of planarization material between superstrate and substrate When the formable material droplets spread, merge, and fill the gap between the superstrate and the substrate, one scheme for minimizing the trapping of air or gas bubbles between the superstrate 108 and the substrate is to initially contact the formable material at the center of the substrate and then position the superstrate so that it progresses radially from the center towards the periphery after further contact. This requires deflection or bowing of the superstrate or the substrate or both to create a curvature profile within the superstrate. However, assuming that the superstrate 108 typically has the same or similar area dimensions as the substrate 102, a useful curvature profile across the entire superstrate requires both a large vertical deflection of the superstrate and the accompanying vertical movement by the superstrate chuck and flattening assembly. Such large vertical deflections and movements may not be desirable in terms of control, accuracy, and system design considerations. Such a superstrate profile can be obtained, for example, by applying backpressure to the internal region of the superstrate. However, by doing so, an outer peripheral holding region is still required to keep the superstrate held on the superstrate chuck. If both the superstrate and the peripheral edges of the substrate are flat chucked while the formable material droplets are spreading and merging, there will be no available superstrate curvature profile in this flat chuck region. This can impair the spreading and merging of the droplets, which can also result in non-fill defects in that region. Additionally, once the spreading and filling of the formable material are complete, the resulting stack of the superstrate chuck, the chucked superstrate, the formable material, the substrate, and the substrate chuck can be an overconstrained system. This can cause a non-uniform flattening profile of the resulting layer of the flattened film.That is, in such an overconstrained system, all flatness errors or variations from the super straight chuck, including the flatness of the front and back surfaces, can be transmitted to the super straight and may affect the uniformity of the layers of the planarization film.

[0039] To solve the above problems, in one embodiment, as shown in FIGS. 3a and 3b, a multi-zone super straight chuck 118 is provided. The super straight chuck 118 includes a central zone 301 and a series of ring zones 303 around the central zone 301. The ring zones 303 can be defined as a peripheral ring zone 303b around the edge, outer periphery, or perimeter of the super straight chuck 118 and a plurality of inner ring zones 303a located between the central zone 301 and the peripheral ring zone 303b. The plurality of ring zones 303 can be defined by a series of lands 307 protruding from the surface of the super straight chuck 118. As shown in FIGS. 3a and 3b, the lands 307 can be formed around the central zone 301. In each of the ring zones 303, at least one port 305 is formed to enable a pressure source to apply a positive pressure (positive pressure) or a negative pressure (negative pressure), such as a vacuum, to the super straight connected and thereby held via the super straight chuck 118.

[0040] Figure 3b shows a side cross-sectional view of the super straight chuck 118. Each of the lands 307 projects from the surface of the super straight chuck 118 having a height. The lands 307 include a peripheral land 307b surrounding the peripheral ring zone 303b and a series of inner lands 307a between the central zone 301 and the peripheral ring zone 303b. As shown in Figure 3b, the inner lands 307a have substantially the same height, but the height of the peripheral land 307b is lower than the height of the inner lands 307a. The central zone 301 of the super straight chuck 118 can be in the shape of a circular cavity such that a pressure source (not shown) can apply the pressure of air or gas through the associated channels 308 and ports 305 to deflect the central portion of the held super straight. Similarly, a vacuum pressure may be applied to the central zone 301 through the same channels and ports. The central zone 301 of the super straight chuck 118 can be aligned with the central portion of the held super straight. Similarly, the peripheral ring zone 303a can be aligned with the outer periphery or edge of the held super straight. The peripheral ring zone 303 is also provided with respective channels 308 and ports 305 for applying pressure or vacuum.

[0041] Referring to FIGS. 4a - 4e, a process for contacting, spreading, and merging droplets of the deposited formable material 124 is shown. As shown in FIG. 4a, prior to contacting the superstrate 108 with the formable material 124, a positive pressure (indicated by arrow P) is applied through port 305 to the central zone 301 of the superstrate chuck 118, to the held superstrate 108, deflecting the central portion of the superstrate 108 towards the formable material 124. The pressure P is applied to the central zone 301 to control the initial deflection within a predetermined range and maintain a predetermined curvature of the superstrate 108, as shown in FIG. 4a. On the other hand, a negative pressure, preferably a vacuum (indicated by arrow V), is applied to the superstrate 108 through port 305 within the ring zone 303, holding the superstrate 108 together with the superstrate chuck 118. The superstrate 108 is then initially contacted with the droplets of the formable material 124, as shown in FIG. 4b.

[0042] Next, by sequentially releasing the vacuum (V) from the inner ring zone 303a proximal to the central zone 301, the deflection of the superstrate 108 is expanded in a radially outward direction from the central portion. In this way, the droplets of the formable material are contacted, spread, and merged to form a film layer having a fluid front end that progresses radially outward as the superstrate contacts and conforms to the substrate. As the vacuum is sequentially released from the inner ring zone 303a, the pressure P applied through the central zone 301 is maintained at a desired value. Also, the pressure P can be applied to the superstrate 108 through channels 308 and ports 305 within the inner ring zone 303a where the vacuum has been released. In the embodiment shown in FIG. 4c, the vacuum is sequentially released from the three inner rings 303a closest to the inner zone 301, and the pressure P is sequentially applied as the vacuum is sequentially released. The flattening head can be moved downward during this sequential vacuum release and pressurization.

[0043] Next, the deflection of the superstrate 108 is sequentially further radially expanded until the vacuum is released from all of the inner ring zones 303a while the vacuum V applied through the peripheral ring zone 303b is maintained. For each of the inner ring zones 303a, when the vacuum is released, pressure P is also applied. As shown in FIG. 4d, when the vacuum is released from all of the inner ring zones 303a, the superstrate 108 is deflected to conform to the substrate 102, except for the peripheral portion of the substrate 108 that remains held by the superstrate chuck 118 via the vacuum V applied through the surrounding zone 303b. Thus, the edges of the superstrate 108 remain in a deflected, curved state for the final spreading and merging of the droplets of formable material dispensed on the peripheral portion of the substrate 102. Also, the surrounding land 307b that is lower than the inner land 307a facilitates the maintenance of such curvature.

[0044] Next, in FIG. 4e, the vacuum V applied through the peripheral ring zone 303b is released in order to completely release the superstrate 108 from the superstrate chuck 118. This provides several advantages. First, by releasing the peripheral edge of the superstrate 108 from the peripheral ring zone 303b that was held in a curved state, the spread and coalescence of the droplets of the remaining formable material can be completed in a radial pattern from the same center to the outer periphery, and thus, the trapping of air or gas and the resulting non-fill defects can continue to be minimized. Specifically, the peripheral land 307b that is recessed with respect to the inner land 307a allows the superstrate 108 to maintain the desired curvature before release. Second, by completely releasing the superstrate 108 from the superstrate chuck 118, any overconstraint of the superstrate 108 due to the chucking conditions is removed, thereby reducing the local non-uniform flattening that could occur due to such constraint conditions. Third, by releasing the superstrate 108 from the superstrate chuck 118, the transfer of any chuck non-flatness errors or variations to the superstrate 108 is removed, thereby also reducing the variations in local non-uniform flattening.

[0045] Once the superstrate 108 is released, curing energy is applied to cure the formable material to form the flattening layer. As described above, the curing source may be a light beam for curing the formable material 124. In one embodiment, the size of the light beam can be adjusted or controlled with reference to the diameter of the superstrate. The light beam can also be controlled to be incident on the substrate at a predetermined angle. During curing, the lateral position of the substrate 102 with respect to the curing source (i.e., within the X-Y plane) can be adjusted. After the curing process, the superstrate 108 is re-held by the superstrate chuck 118, and then the superstrate 108 is separated from the substrate as further described herein.

[0046] FIG. 5 shows a flowchart of the planarization process described as shown in FIGS. 3 and 4. In step 501, droplets 124 of formable material are dispensed onto substrate 102. The central zone of the superstrate 108 is deflected towards the droplets 124 of formable material in step S502. The deflected superstrate 108 is then advanced by the superstrate chuck 118 in step S503 to contact the formable material 124. The deflection of the superstrate 108 is expanded from the central zone towards the outer periphery of the superstrate 108 in step S504. Then, the application of the force for holding the superstrate 108 by the superstrate chuck 118, for example, by the vacuum applied to the outer periphery of the superstrate 108, is stopped, and the superstrate 108 is released (i.e., de-chucked) from the superstrate chuck 118 in step S506. The formable material 124 is cured in step S507. After curing, the superstrate 108 is re-held by the superstrate chuck 118 to separate the superstrate 108 from the cured formable material 146.

[0047] For example, when using a UV curable material as the formable material 124, the super straight chuck 118 desirably is highly transparent to UV light for UV curing (e.g., as highly transmissive for imaging by the camera 136 as shown in FIG. 1). As described above, the air supply channels 308 and ports 305, zones 303, and lands 307 are integrated into the super straight as shown in FIGS. 3 and 4. These structures can cause problems for UV curing. In particular, the UV transmittance in the regions under the channels 308 and lands 307 can be significantly reduced compared to regions without such features, resulting in insufficient or non-uniform curing of the formable material. This phenomenon is sometimes referred to as the "shadow effect". The shadow effect is particularly important at the edges of the lands 307. Further, when the super straight 100 is chucked to the land 307, a thin air gap exists because the two surfaces do not optically contact each other. This type of thin gap can completely block UV. This phenomenon is known as the "thin film effect" between the land and the super straight.

[0048] One solution to the above "shadow effect" involves moving the stack of the super straight and the substrate on the wafer stage in the x, y, and / or θ coordinates after de-chucking (i.e., releasing) the super straight from the super straight chuck. By moving the wafer stage in this manner during UV exposure, the regions of the super straight and the substrate that would have remained under the channels, ports, and lands can be periodically moved under the super straight chuck where there are no chuck features. The required relative motion can be estimated from Equation (1) below: JPEG0007713064000001.jpg17166Here, I m is the desired average intensity over the range of motion, and I h is the high intensity (i.e., maximum or "peak" intensity) over the region without chuck features, and I lis the intensity in the target feature (i.e., the minimum or "low" intensity), and w h is I m is the estimated range of motion to achieve, and w l is the target feature width (e.g., the width of a land, port, or channel). For example, assuming 100% UV transmission in an area without features and assuming the desired I m is 90% of that value, and further assuming w i = 1 mm, from Equation (1), the desired range of relative motion w h = 8.0 mm. Alternatively, the UV source can be moved by tilting or inclining the UV source relative to the super straight chuck so as to change the angle of the UV light incident on the super straight chuck, thereby also reducing the shadow effect near the target feature. The "thin film effect" can be avoided by moving relatively in the z-axis direction to create a sufficient gap between the super straight and the super straight chuck, for example, by de-chucking the super straight and moving the wafer stage in the z-direction away from the super straight chuck. The various solutions described above can be applied individually or in combination to improve the uniformity of the total UV dose in a specific area and minimize the shadow effect and the thin film effect. In various embodiments, the applied UV light beam may be smaller than, the same size as, or larger than the substrate or the super straight. In one embodiment, the applied UV light beam can be made larger than the substrate by an amount that adapts to the relative motion w h while continuously exposing the entire substrate to the UV light.

[0049] Separation of superstrate from layer of cured planarization film Once the formable material is cured and a layer of planarization film is formed, it is necessary to remove or peel off the superstrate from the formed layer. However, when the superstrate and the substrate have the same or similar area dimensions, it is difficult to initiate and propagate a separation crack between the superstrate and the formed layer as needed to completely separate the superstrate from the formed layer. This problem can be solved by the structures and methods shown in FIGS. 6 - 8. As shown in FIGS. 6a and 6b, the substrate chuck 604 includes a retractable pin 606 located at the outer periphery of the chuck that can be aligned with a notch 608 on the substrate 102. Such notches (e.g., wafer notches) are common to semiconductor wafers for the purpose of orienting the wafer during processing and handling. During operation, the retractable pin 606 is aligned and positioned with the notch 608 located on the substrate 102. To initiate separation, the pin 606 moves upward through the notch 608 and contacts the point 610 at the edge of the superstrate 108, as shown in FIG. 6a. The force applied by the pin 606 is sufficient to initiate a separation crack 601 between the superstrate 108 and the cured layer 146 on the substrate 102. Once the crack 601 is generated, the edge of the superstrate 108 is deflected towards the superstrate chuck 118 by the application of a vacuum pressure through the port 305 of the superstrate chuck 118. This is facilitated by the fact that the land 307b of the superstrate chuck 118 is shorter than the adjacent land 307a, thereby providing a space for the edge of the superstrate 108 to deflect away from the substrate 102 and towards the superstrate chuck 118. The force applied to generate the crack 601 can depend on the geometric and physical conditions of the superstrate, the layer of planarization film, and the substrate. Alternatively, the crack 601 may be generated by introducing a positive pressure between the substrate 102 and the superstrate 108, as shown in FIG. 6c. Here, the substrate chuck 614 includes a nozzle 616 connected to a source of positive fluid pressure (not shown). Activation of the nozzle 616 causes a positive fluid pressure P Iis delivered with sufficient force to initiate the separation crack 601 to the point 610 at the edge of the supersheet 118 through the nozzle 616. The positive fluid pressure can include a flow of clean dry air, helium, or nitrogen. While the crack 601 is being generated, the supersheet 102 is held within the supersheet chuck 118 and the substrate 102 is held by the substrate chuck 104.

[0050] Figures 7-8 show the progress of the separation. Figure 7a shows a top and bottom view where the supersheet 118 is in full contact with the layer formed on the substrate (as indicated by the hatched area). In Figure 7b, the separation crack 601 is initiated as described above. Once the crack 601 is initiated, it engages the edge of the supersheet 108 and a high flow of negative pressure or vacuum is applied to the outer ring zone 303b of the supersheet chuck 118 to propagate the separation crack 601 around the outer zone ring 303b. This propagation proceeds circumferentially in both directions from the notch 608, as indicated by the arrow C. To assist the propagation of the crack 601 around the outer ring zone 303b, an additional lateral air flow (not shown) can be supplied between the substrate 102 and the supersheet 108 as the crack propagation progresses. Figure 7c shows the crack 601 that has fully propagated around the outer ring zone 303b.

[0051] Once the separation crack has completely propagated around the outer ring zone, an upward movement is applied along the Z-axis direction of the superstrate 108, and the separation of the superstrate 108 from the cured layer on the substrate can be completed. FIG. 8 shows the superstrate 108 completely separated from the substrate 102. When completing the separation, the significant upward movement of the superstrate 108 relative to the substrate 102 can induce shear stress in the remaining contact area between the superstrate 108 and the substrate 102. Alternatively, the movement in the Z direction can be stopped at a desired earlier position, and the separation can be advanced and concluded through the continuous application of a vacuum pressure to the inner and / or central ring zones. Such shear stress can be minimized by applying a vacuum to one or more of the inner ring zone 303a and / or the central zone 301 during the continuous separation.

[0052] FIG. 9 shows a flowchart of the separation process described and illustrated in FIGS. 7 and 8. In step S901, a separation crack is initiated between the superstrate 108 and the cured layer. Then, in step S902, the separation crack is propagated around the outer periphery of the superstrate 108. In step S903, the remainder of the superstrate is separated from the cured layer. In the above-described embodiment, the separation of the superstrate 108 from the substrate 102 includes the steps of generating a crack by a mechanical force such as a push pin or pneumatic pressure, applying a vacuum pressure to the outer zone to propagate the crack, firmly holding the superstrate 108, moving the superstrate 108 upward in the Z direction, and separating it from the substrate 102 with a safe force sufficient to avoid the superstrate from de-chucking upward, and applying a vacuum to the center of the superstrate 108 while moving upward in the Z direction to complete the separation. Alternatively, or in combination with the above-described Z-direction movement method, the propagation of the separation can also be affected by continuously applying a high-pressure in-plane (or lateral) direction flow from one or more sides of the substrate (not shown).

[0053] In the embodiment of FIG. 6, crack initiation is initiated by an upward force applied through the wafer notch 608, either by a mechanical pin 606 (FIG. 6a) or a fluid nozzle 616 (FIG. 6b). FIG. 10 shows a further embodiment of a substrate chuck configured to initiate a separation crack. Here, the substrate chuck 624 includes a separate retractable pin 626 that can initiate a separation crack when the superstrate 108 and the substrate are non-concentrically arranged. This non-concentric arrangement results in a portion 628 of the superstrate 108 that overhangs the substrate 102. The crack 602 can be generated by applying a force to the overhang portion 110 via the movement of the pin 626. Alternatively, the overhang portion 608 can also be obtained by using a superstrate that is slightly larger than the substrate. In this way, the superstrate 108 can still be arranged concentrically with the substrate 102. In either case, the substrate chuck 624 can further include mechanical pins or nozzles spaced apart from the pin 626, such as in the embodiments of FIGS. 6a or 6b, or in other ways, to generate a plurality of points around the outer periphery of the superstrate for initiating the separation crack.

[0054] Superstrate chuck As described above, the superstrate 108 is preferably held or supported by a superstrate chuck 118 that applies pressure or vacuum (negative pressure) to the volume between the superstrate and the chucking surface within a ring zone 303 defined by lands 307 extending from the chucking surface. Separate from the outermost land 307a, the inner lands 307b preferably have the same height such that the depth of the gap between adjacent inner lands 307b remains constant. The height of the lands (i.e., the depth of the gap) is typically very small, on the order of, for example, about several tens of microns to several thousand microns, for reasons such as minimizing gas filling or evacuation response times, land rigidity characteristics, and thermal effects such as expansion or contraction. During operation, when a vacuum is applied to the ring zone to hold the superstrate against the lands of the zone, a vacuum seal is created at the superstrate-land boundary. However, if sufficient force or pressure is applied to the superstrate in the direction opposite the chucking vacuum, the substrate can be lifted off the lands of the chuck. At a particular gap between the superstrate and the lands, the vacuum seal can break or leak, causing the vacuum pressure within the zone to decrease or even go to zero. The superstrate then becomes unintentionally de-chucked from the chuck. Further, even if the superstrate does not become de-chucked, vacuum leaks can disrupt the required level of control, for example, when sequentially releasing the vacuum pressure in adjacent ring zones in the processes of FIGS. 4 and 5. Also, such leaks at the outer lands can negatively affect the controlled retention of the desired outer edge curvature of the superstrate in the processes of FIGS. 4 - 5. Similarly, leaks at the outer lands can prevent the initiation and propagation of separation cracks in the processes of FIGS. 7 - 9.

[0055] To counter such undesirable leakage, as shown in FIGS. 11a and 11b, a super straight chuck 1118 incorporating a trench structure 1109 is provided. Similar to the super straight chuck 118, the super straight chuck 1118 also includes a plurality of lands 307 that can be defined by a series of inner lands 307a and a peripheral land 307b protruding from the surface 1119 of the super straight chuck 1118. As shown in FIGS. 11b and 12, the surface 1119 is a holding or maintaining surface for holding or maintaining the super straight 108. A series of inner zones 303a are defined by the lands 307a. In at least one of the ring zones 303, a trench 1109 recessed from the surface of the chuck 1118 is formed. The trench may be concentric and may be disposed between corresponding lands of the ring zone. The trench 1109a formed in the inner ring zone 303a is positioned at a distal position from the center of the chuck 1118 with respect to the width of the associated inner ring zone. In contrast, the trench 1109b formed in the peripheral ring zone 303b is positioned in a region close to the center of the substrate chuck 1118 with respect to the width of the outer zone ring. That is, the trench 1109a formed in the inner ring zone 303a is formed at the outer diameter of the corresponding inner ring zone 303a, while the trench 1109b formed in the peripheral ring zone 303b is formed at the inner diameter of the peripheral zone 303b.

[0056] In operation, the trench 1109 serves as a buffer that provides a uniform source of high vacuum pressure that continues to act on the superstrate even if there is a gap between the superstrates on the distal side of the trench. In this way, the sequential outward radial release of the vacuum and the application of positive pressure to the ring zones adjacent to the central zone can proceed in a controlled manner. That is, the vacuum pressure applied within a given ring zone can be maintained even if positive pressure is applied to the adjacent inner zone in an amount sufficient to deflect the superstrate enough to create a gap in the distal land. In other words, by providing the trench 1109, some leakage can be tolerated without interrupting the intended process. Similarly, the trench 1109b located within the surrounding ring zone having a smaller outer land height operates to maintain an appropriate vacuum pressure within the outer ring zone even if there is a small gap in the outer land. This allows the outer perimeter of the superstrate to be maintained at the desired curvature for both the final spread and coalescence of the deposited droplets of formable material (see FIG. 4d) and the generation and propagation of separation cracks (see FIG. 6), even with some leakage.

[0057] FIG. 12 is an enlarged cross-sectional view of an exemplary trench structure 1109b. The specific trench dimensions and associated positions within the ring zone necessary to achieve the desired vacuum buffering performance depend on the land height of the superstrate chuck and the ring zone width. In the example shown in FIG. 12, the trench 1109b is located within the ring zone 303b and is recessed from the chuck surface. In this example, the outer land 307b has a height h1 that is lower than the height h2 of the inner land 307a. In typical use, the difference in land height can range from about 5 microns to about 50 microns. The ring zone 303b has a width d. The trench 1109b is arranged such that it has a first edge at a distance d1 from the land 307b and a second edge at a distance d2 from the land 307a. The trench 1109b has a depth h3 and a width d3. In this embodiment, the relationship of these parameters satisfies the following conditions: h1 < h2 h3 > 10h2 d3 < 0.5d d1 > d2 + d3 The port 305 that connects the trench 1109b to a pressure source (not shown) intersects the trench or is otherwise disposed within the trench. If the port does not intersect the trench, the required high pressure cannot be maintained and the trench becomes ineffective. In the above embodiment, the outer land h1 is a location where leakage is expected. In the case of the inner ring trench 1109b, the land height can be the same, i.e., h1 = h2. In this case, the distance d1 is measured from the designated land where leakage is expected (i.e., h1 or h2). For example, in the embodiments of FIGS. 11a and 11b, the inner ring zone 303a includes a trench 1109a disposed closer to the outer land (measured radially from the chuck center) of each of those respective ring zones in order to mitigate leakage at the inner land during sequential vacuum release and subsequent pressurization of the ring zones, as described in the processes associated with FIGS. 4 - 5.

[0058] Further modifications and alternative embodiments of various aspects will be apparent to those skilled in the art in view of this description. Accordingly, this description should be construed as illustrative only. It is to be understood that the forms shown and described herein are to be construed as examples of embodiments. Elements and materials can be replaced with those illustrated and described herein, parts and processes can be reversed, and specific features can be utilized independently, all of which will become apparent to those skilled in the art after the benefit of this description.

Claims

1. For a stack having a cured layer sandwiched between a substrate and a superstrate, by applying a force to a partial region of the outer periphery of the superstrate from an opening provided in a substrate chuck holding the substrate, the superstrate and the cured layer are separated in a partial region of the outer periphery of the surface where the superstrate and the cured layer are in contact, and a step of starting the separation of the superstrate and the cured layer; A step of expanding a separation region where the superstrate and the cured layer are separated along the outer periphery of the surface where the superstrate and the cured layer are in contact from the partial region; A step of starting relative movement between the substrate and the superstrate in a direction in which the substrate and the superstrate are separated with the separation region expanded along the outer periphery, and completing the separation of the superstrate and the cured layer; A method comprising the above.

2. In the step of starting the separation, the separation is started by applying the force to a partial region of the outer periphery of the superstrate from below and outside the edge of the substrate toward the superstrate. The method according to claim 1.

3. The substrate includes a notch formed at an edge, and the substrate chuck applies the force to the superstrate through the notch. The method according to claim 1.

4. In the step of starting the separation, the force is applied to the partial region by introducing a positive fluid pressure into the partial region. The method according to claim 1.

5. The positive fluid pressure includes a pressure by clean dry air, helium or nitrogen. The method according to claim 4.

6. The opening is a nozzle located on the outer periphery of the substrate chuck, and the positive fluid pressure is introduced into the partial region through the nozzle. The method according to claim 4.

7. The force includes a mechanical force. The method according to claim 1.

8. The opening is located on the outer periphery of the substrate chuck, and the force is applied to the partial region through a pin disposed in the opening. The method according to claim 7.

9. The pin is storable in the substrate chuck. The method according to claim 8.

10. The method according to claim 1, wherein in the step of widening the separation region, a negative fluid pressure is applied to a peripheral zone of a superstrate chuck that holds the superstrate so as to bend an outer peripheral region of the superstrate.

11. The method according to claim 1, wherein the force is applied from below the superstrate.

12. A superstrate chuck for holding a superstrate, A substrate chuck for holding a substrate, A force supply source configured to apply a force from an opening provided in the substrate chuck to a stack in which a cured layer is sandwiched between the substrate and the superstrate, so as to start separation between the superstrate and the cured layer in a partial region of an outer periphery of a surface where the superstrate and the cured layer are in contact, A planarization system comprising the same.

13. The planarization system according to claim 12, wherein the force is a positive fluid pressure including pressure by clean dry air, helium or nitrogen.

14. The planarization system according to claim 13, wherein the opening is a nozzle located on an outer periphery of the substrate chuck, and the positive fluid pressure is introduced into the partial region through the nozzle.

15. The planarization system according to claim 12, wherein the force includes a mechanical force.

16. The planarization system according to claim 15, wherein the opening is located on an outer periphery of the substrate chuck, and the force is applied to the partial region through pins arranged in the opening.

17. The planarization system according to claim 16, wherein the pins can be stored in the substrate chuck.

18. A step of forming a cured layer between a substrate and a superstrate, A step of completing separation between the superstrate and the cured layer using the method according to any one of claims 1 to 11, A step of manufacturing an article by processing the cured layer, A method for manufacturing an article including the same.

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