Imprinting device

Abstract

The imprint apparatus comprises a first carrier carrying a flexible stamp and a second carrier movable relative to the first carrier, the second carrier configured to carry a substrate having a resist layer. The second carrier includes a chuck, a set of chuck actuators for translating a portion of the chuck in a Z-axis direction, a stamp landing device (e.g., a ring) around the outside of the chuck, and a set of landing ring actuators for translating a portion of the stamp landing ring in a Z-axis direction. The movement of the chuck as well as the movement of the stamp landing ring allows the apparatus to take into account different stamp thicknesses.

Description

[Technical Field]

[0001] The present invention relates to an apparatus for imprinting an imprint pattern of a flexible stamp into a resist layer, and to a stamp landing device for such an apparatus. [Background technology]

[0002] Imprint lithography of the type disclosed in EP 3126909(A) is gaining interest as a viable alternative to more traditional mask-based optical lithography techniques because imprint lithography promises to provide small (smaller) feature sizes in patterns transferred to substrates, such as semiconductor device substrates, over a wide range. In imprint lithography techniques, such as substrate conformal imprint lithography ("SCIL"), a flexible stamp containing a relief feature pattern on its surface is brought into contact with a substrate, which typically carries a resist material. The resist material is imprinted with the feature pattern. The resist material is subsequently developed, e.g., hardened, after which the feature pattern is released from the resist material, leaving a patterned resist layer on the substrate.

[0003] In this process, a curable but fluid resist layer is applied to a substrate (e.g., a wafer) supported by a chuck. A flexible stamp, e.g., rubber, is used to imprint the resist layer, which is cured (solidified) while being imprinted, leaving a solidified relief in the resist layer that is complementary to the relief in the stamp relief layer after the stamp is removed from the resist. The imprinting process involves placing a thin flexible stamp, formed, for example, from a PDMS rubber layer bonded to a thin flexible plate, e.g., a metal or glass plate, with the relief surface of the PDMS layer on the side opposite the glass plate, in a stamp manipulator, also known as a groove plate. This positions the glass plate against the stamp manipulator, with the relief surface of the stamp facing the resist layer of the wafer in the chuck.

[0004] The stamp is typically, but not necessarily, held upside down above the wafer by two parts parallel to each other in the XY plane at a small distance along the Z axis from the surface of the fluid resist layer, which small distance defines a so-called imprint gap along the Z axis between the relief surface of the stamp and the resist layer.

[0005] The stamp can be manipulated locally, for example, by a stamp manipulator, allowing it to be locally and sequentially released and attached to the stamp manipulator. The stamp manipulator often has grooves extending along its surface (XY plane), also known as groove plate openings, which can be individually manipulated with a set pressure, such as overpressure or negative pressure, to hold the stamp (negative pressure) or release the stamp (overpressure). Thus, during the imprinting process, releasing the stamp at one XY location (e.g., edge) creates a first contact between the relief surface and the resist at that location. The stamp is then gradually released from the stamp manipulator and is attracted to the resist layer primarily by capillary forces. Contact then grows from the first contact location along the X-axis and / or Y-axis, depending on the release strategy.

[0006] To be able to attach the stamp to the manipulator, the stamp needs to be positioned upside down under the manipulator. To do this, the stamp is placed under the stamp holder (upside down with the relief surface facing downwards). The stamp manipulator is moved over the underlying stamp, facing the back side of the stamp's glass plate, after which the stamp's glass plate surface is attached to the manipulator by manipulating the manipulator opening.

[0007] The substrate is then loaded onto the chuck and positioned as desired relative to the relief layer surface.

[0008] To set the imprint gap at the beginning of the process, the distance (in the Z-axis direction) needs to be set to a desired value (e.g., in the range of 50 μm to 150 μm) and kept within a tight tolerance during the imprint process (e.g., a gap variation of 5 μm to 10 μm). The imprint gap is the gap between the wafer and the stamp.

[0009] During the imprinting step, the manipulator openings are switched from negative pressure to a slight overpressure to gradually release the stamp from the stamp manipulator, thereby attracting the feature pattern to the resist layer by capillary forces because the spacing between adjacent protrusions of such patterns generally acts as a capillary, thereby speeding up the wetting of the stamp by the resist. During and after development (e.g., solidification) of the resist layer while still in contact with the stamp, the feature pattern of the flexible stamp is released from the resist layer by a reverse process in which individual manipulator openings are switched to negative pressure, thereby gradually releasing the feature pattern from the developed resist layer. The release process is generally hindered by interactions between the stamp material and the developed (solidified) resist, which slows the release process. This is due to the increased surface area between the stamp and the hardened resist, which increases the van der Waals forces per unit area. Therefore, for imprinting apparatuses such as those disclosed in WO 2008 / 068701(A2), the speed of the imprinting or release step can be set.

[0010] Current SCIL imprint machines use wafers with diameters of 100 to 200 mm. A single linear Z stage is used for vertical movement of the chuck to load and unload the wafer and to adjust the imprint gap. Adjustment of the tilt (RX and RY) between the chuck and the groove plate is performed manually, for example, using three micrometer adjustment screws.

[0011] The height of the stamp landing ring in existing machines is fixed and can only be adapted by replacing the stamp landing ring with one of a different height.

[0012] There is a desire to scale up the design to enable printing of larger wafers, such as 300 mm wafers. This results in an increased required process force (e.g., twice as high) and a larger span width (e.g., 300 mm diameter instead of 200 mm). It is not possible to simply scale up the existing design to maintain the required imprint gap variation, such as 5-10 μm, under process load. In particular, the support for the wafer is not sufficiently rigid.

[0013] The support for the wafer includes, for example, a support frame, such as a support and chuck of a C-frame design. The support frame can bend due to process loads or distortion during heating. The bending or distortion results in larger variations in the imprint gap, which significantly reduces the quality of the imprint process. A larger chuck also has a larger thermal mass, which results in longer heating and cooling times.

[0014] WO 2004 / 013693 A2 describes a method for patterning a substrate by imprint lithography. One embodiment of a system for imprint lithography has an imprint head mounted to an imprint head support and configured to hold a patterned template.

[0015] WO 03 / 099463 A2 describes a method for transferring a pattern from the stamping surface of a stamp to the receiving surface of a substrate: The pattern is transferred to the receiving surface by successively bringing portions of the pattern within the receiving surface. Summary of the Invention [Problem to be solved by the invention]

[0016] One challenge, therefore, is the need to control the imprint gap fairly accurately for larger area wafer supports, such as chucks and groove plates (e.g., 300 mm diameter), while still allowing for easy loading of the stamp and wafer. This loading requires, for example, longer distance manipulation of the chuck relative to the groove plate. For larger chucks, existing designs have been found difficult to manufacture with tolerances that allow sufficient rigidity to ensure imprint gap control over the entire chuck area.

[0017] Another challenge is to enable accurate and stable control of the position of the wafer support (known as a chuck).

[0018] Another challenge is ensuring a uniform process gap between the stamp and the substrate, such as at the stamp landing ring location around the outer region of the stamp.

[0019] The present invention aims to address one or more of these problems. [Means for solving the problem]

[0020] According to the present disclosure, there is provided an imprinting apparatus comprising a first carrier carrying a flexible stamp having an imprint pattern and a second carrier movable relative to the first carrier. The second carrier is arranged to receive (or may include) a chuck, the chuck being configured to carry a substrate having a resist layer. The second carrier includes a stamp landing device (502), which, when the second carrier includes a chuck (500), is arranged so that the stamp landing device (502) is positioned outside the chuck along at least a portion of the chuck, and the stamp landing device is intended to face the first carrier outside the area of ​​the flexible stamp. Thus, when the chuck is received by the second carrier, the stamp landing device is positioned around the outside of a portion of the chuck. The second carrier further includes a set of landing device actuators that translate a portion of the stamp landing device in a direction perpendicular to the plane of the second carrier. The second carrier further includes a set of chuck actuators that translate a portion of the chuck in a direction perpendicular to the plane of the second carrier.

[0021] The imprint apparatus is or includes a substrate conformal imprint lithography apparatus. The flexible stamp has an imprint pattern, and the first carrier includes, for example, an array of actuators (e.g., manipulator openings or apertures) that are used to attract the flexible stamp to the first carrier and push the flexible stamp away from the first carrier. The array of actuators may be or include pressure-operated manipulator openings or apertures, although other types, such as electric or electromagnetic actuators, may also be used, for example, in combination with a flexible stamp having a metal support layer.

[0022] The chuck actuator allows for controlled rotation of the chuck about the X and Y axes (in the plane of the chuck / substrate) as well as control in the Z axis. Tilt and wedge compensation is therefore enabled, which can be manual and / or automatic based on local position sensing. Tight control of the imprint gap is enabled.

[0023] The stamp landing device (e.g., a ring) provides support for the substrate of the flexible stamp. The flexible stamp, for example, includes a glass substrate and a rubber stamp area above the center area of ​​the glass substrate. The stamp landing device allows the same process gap to exist on the flexible stamp even if it has two areas of different heights.

[0024] An actuator for moving the stamp landing device is integrated into the second carrier. The movement of the stamp landing device allows the apparatus to take into account different stamp thicknesses.

[0025] The chuck includes a set of position sensors that measure the distance from the surface of the chuck to the first carrier, which allow for manual and / or automatic control of the chuck actuator.

[0026] The set of position sensors may, for example, include three position sensors each measuring a distance from the chuck to the first carrier, each position sensor being proximate to a respective first actuator, and together the set of three position sensors allows for six degrees of freedom ("DOF") control.

[0027] The second carrier includes a set of position sensors that measure the distance from the stamp landing device to the first carrier, allowing the position of the stamp landing device to be controlled, for example, to take into account different stamp thicknesses and therefore different height profiles of the flexible stamp.

[0028] The device is The mainframe and and a mainframe actuator that translates the mainframe in a direction perpendicular to the plane of the second carrier, the chuck actuator being for translating a portion of the chuck relative to the mainframe, the mainframe actuator having a larger stroke than the chuck actuator.

[0029] The Z-axis movement of the chuck (perpendicular to the plane of the chuck / substrate) is split into two stages by separate long-stroke and short-stroke drivers. This provides very rigid support. The chuck actuator allows control of the chuck's rotation about the X- and Y-axes (in the plane of the chuck / substrate) as well as control in the Z-axis. Thus, tilt and wedge compensation is enabled, which can be manual and / or automatic based on local position sensing. Tight control of the imprint gap is enabled.

[0030] The mainframe actuator has a large stroke (e.g., 50 mm or more) to facilitate loading of the stamp and substrate, and the chuck actuator has a small stroke for fine adjustment, e.g., down to +-1 μm for a 5 mm stroke.

[0031] The second carrier further includes a subframe, the subframe connected to the mainframe, the chuck attached to the subframe, and the subframe attached to the mainframe by a spring arrangement that biases the subframe against the first carrier via a kinematic coupling during imprinting.

[0032] The chuck is then carried by a rigid subframe, which can then be separated from the mainframe and mainframe actuator.

[0033] The sub-frame is attached to the main frame by, for example, a spring arrangement. The spring arrangement provides a separation between the sub-frame and the main frame. The sub-frame behaves as a rigid body, and deformations of the main frame and / or the main actuator do not affect the imprint gap. In particular, a separation of force and position paths is implemented.

[0034] These allow for automatic control of the chuck actuator.

[0035] The spring arrangement is preferably for biasing the sub-frame against the first carrier via a kinematic coupling during imprinting. The spring arrangement not only provides a biasing force but also compensates for alignment errors. The biasing kinematic coupling means that the sub-frame and the first holder (i.e., groove plate) act as a single rigid part.

[0036] The apparatus further comprises a stamp landing ring (or more generally a stamp landing device) for adapting the stamp landing device according to the thickness or size of the substrate.

[0037] Stamp landing device adaptors allow the fixed (modular) design of the stamp landing device to be tailored to take into account the particular substrate to be processed, or indeed the particular stamp to be used.

[0038] In one example, the stamp landing device is for fitting around a substrate of a first size and the stamp landing device adapter is for expanding the size of the stamp landing device to fit around a substrate of a second, smaller size.

[0039] Thus, the stamp landing device adapter increases the size of the stamp landing device (towards the center) to fit around the smaller substrate.

[0040] In another example, the stamp landing device is for fitting around a flexible stamp of a first size and the stamp landing device adapter is for expanding the size of the stamp landing device to fit around a smaller flexible stamp of a second size.

[0041] Thus, the stamp landing device adaptor increases the size of the stamp landing device (towards the center) to fit around the smaller flexible stamp.

[0042] In another example, the chuck is for supporting a substrate of a first size, and the apparatus further includes a second stamp landing device that fits over the chuck around a smaller substrate of a second size.

[0043] In this case, the second (fixed) stamp landing device effectively increases the size of the substrate to match the size of the stamp, which is for example larger than the substrate.

[0044] Each chuck actuator includes an actuator output and a lever arrangement between the actuator output and the chuck drive member that allows for improved positioning accuracy and increased stiffness compared to direct control of position using the actuator output.

[0045] The chuck includes a hollow cylindrical body having an upper surface and a lower surface.

[0046] A grating structure is provided between the upper and lower surfaces. The chuck has a reduced thermal mass while maintaining the required stiffness to maintain a uniform imprint gap.

[0047] The upper and lower surfaces each include an internal water channel configuration that provides a flow path between a set of water inlets and a water outlet. Heating and cooling occurs at the upper and lower surfaces of the chuck rather than throughout the entire structure, providing effective thermal control. Heating and cooling at the upper and lower surfaces prevents buckling.

[0048] The present invention also provides a stamp landing system for an imprinting apparatus as defined above, the stamp landing system comprising a stamp landing device for arranging around the outside of the chuck, the stamp landing ring for facing the first carrier outside the area of ​​the flexible stamp, the stamp landing ring enabling the same process gap to be present above the flexible stamp even if it has two areas of different heights.

[0049] The second carrier includes a set of position sensors that measure the distance from the stamp landing ring to the first carrier, allowing the position of the stamp landing ring to be controlled, for example, to account for different stamp thicknesses and therefore different height profiles of the flexible stamp.

[0050] The apparatus further includes a set of landing device actuators, each having a third stroke less than the first stroke, that translate a portion of the stamp landing ring relative to the main frame in a direction perpendicular to the plane of the second carrier.

[0051] The present invention further provides a method for controlling a stamp landing device, comprising the steps of: A method is provided that includes driving one or more actuators of a set of landing device actuators.

[0052] The present invention further provides a computer program comprising code which, when executed on a processor, causes a drive system to perform the steps of the method.

[0053] Actuating one or more actuators of the set of landing device actuators includes actuating the device parallel to the surface of the substrate to be imprinted.

[0054] Actuating one or more actuators of the set of landing device actuators includes actuating the one or more actuators after the imprint gap is set to a desired value.

[0055] The computer program may be downloadable from a network or may be stored on a computer-readable medium such as a non-transitory medium.

[0056] Embodiments of the invention will now be described in more detail, and by way of non-limiting example, with reference to the accompanying schematic drawings in which: [Brief explanation of the drawings]

[0057] [Figure 1] 1 shows an imprinting apparatus; [Figure 2] 2 illustrates an example of a portion of the imprint apparatus of FIG. 1; [Figure 3] 2 shows an imprint cycle using the imprint apparatus of FIG. 1. [Figure 4] A release cycle using the imprint apparatus of FIG. 1 is shown. [Figure 5] The design of the chuck manipulator is shown. [Figure 6] 1 illustrates an imprinting apparatus incorporating various design features. [Figure 7] The subframe (attached to the mainframe) is shown in plan view. [Figure 8] An example of a chuck is shown. [Figure 9] 1 shows two cross sections of a portion of the chuck showing the top and bottom surfaces of the chuck and the heating or cooling channel configurations on the top and bottom surfaces. [Figure 10] 1 shows a cross section of the entire chuck. [Figure 11] 10 shows a set of ridges in the upper or lower surface that define a channel configuration. [Figure 12] The underside of the lower surface of the chuck is shown. [Figure 13]1 shows an interface plate for use with the chuck. [Figure 14] 1 shows a drive arrangement for a groove plate. [Figure 15] The design of a short stroke actuator for use as a chuck actuator is shown. [Figure 16] 16A and 16B show different views of the drive element used in the actuator of FIG. 15; [Figure 17] 1 shows how to use a stamp landing ring. [Figure 18] 1 shows a first use of the stamp landing ring adapter. [Figure 19] 10 shows a second use of the stamped landing ring adapter. [Figure 20] An example using a second stamping landing ring is shown. [Figure 21] An example is given using a stamping landing ring with two thicknesses, suitable for imprinting a relatively thick 200 mm wafer. [Figure 22] 1 shows a diagram used to explain the semi-automatic stamp loading process. DETAILED DESCRIPTION OF THE INVENTION

[0058] The figures are not drawn to scale. The same reference numerals are used throughout the figures to denote the same or similar parts.

[0059] The present invention provides an imprinting apparatus comprising a first carrier carrying a flexible stamp and a second carrier movable relative to the first carrier and configured to carry a substrate having a resist layer. The second carrier includes a chuck, a set of chuck actuators for translating a portion of the chuck in the Z-axis direction, a stamp landing ring around the outside of the chuck, and a set of landing ring actuators for translating a portion of the stamp landing ring in the Z-axis direction. The movement of the chuck as well as the movement of the stamp landing ring allows the apparatus to account for various stamp thicknesses.

[0060] Before describing the present invention, the apparatus and method disclosed in EP 3126909(A) and WO 2020 / 0099265 will first be described with reference to Figures 1 to 4, followed by a description of modifications of this apparatus that embody the present invention.

[0061] Figure 1 shows an imprint apparatus 100. The imprint apparatus 100 may be a SCIL imprint apparatus or any other suitable imprint apparatus that can be used to transfer an imprint pattern from a (flexible) stamp to a substrate.

[0062] The imprinting apparatus 100 typically comprises a first holder 102 (a groove plate, as will become clear below) that holds a flexible stamp 104 that includes an imprint pattern 106 defined by recesses between protrusions. The first holder is mounted in a frame (not shown), and both are contained within a first carrier 102. The flexible stamp 104 and the imprint pattern 106 are realized in any suitable material, for example, a suitable (synthetic) rubber material, such as a polysiloxane-based material, e.g., polydimethylsiloxane (PDMS). A rubber layer is applied to a flexible stamp plate (not shown separately, made of, for example, glass, plastic, or metal). The feature size of the imprint pattern can be any suitable size, preferably a micrometer- or nanometer-scale pattern, i.e., a pattern having a feature size of around 10 nm to more than 1 mm, and the aspect ratio of the features (vertical dimension divided by lateral dimension) can be 8 or greater. However, it should be understood that other feature sizes are contemplated and the present invention is equally applicable to transferring patterns having smaller aspect ratios. For example, at least some embodiments of the present invention are suitable for transferring imprint patterns having aspect ratios in the range of 0.001 to 10.

[0063] To this end, the first carrier 102 typically comprises a plurality of stamp-engaging elements 112 arranged in an array or grid (see, e.g., FIG. 2 ). Such stamp-engaging elements 112 are typically configured to attract a portion of the flexible stamp 106 toward the first carrier 102 in a first configuration and to push a portion of the flexible stamp away from the first carrier 102 in a second configuration. Such elements may be referred to as stamp actuators. In the detailed description below, the stamp-engaging elements 112 are embodied by apertures that can be switched between negative pressure (vacuum) and overpressure to provide the first and second configurations, respectively. Other actuators may also be used, such as, for example, electromagnetic actuators.

[0064] The apertures 112 may have any suitable shape. For example, the apertures 112 may be groove-shaped, with the grooves extending substantially the entire length of the first carrier 102, or as shown in FIG. 2, the apertures 112 may be circular, with the apertures 112 forming a two-dimensional grid. Other suitable shapes will be apparent to those skilled in the art. Groove-shaped apertures 112 may be appropriate, for example, when the imprint and release directions of the flexible stamp are the same or opposite to one another. For example, a two-dimensional grid of circular apertures 112, as shown in FIG. 2, may be particularly appropriate when the imprint and release directions of the flexible stamp 104 are different from one another, as will be described in more detail below.

[0065] Each aperture 112 includes a valve 114 that can switch the aperture 112 between an overpressure source provided via a first channel 140 (referred to as the "overpressure channel") and a negative pressure source, e.g., a vacuum pump or a reservoir of air at low pressure, provided via a second channel 150 (referred to as the "negative pressure channel"). The connection between each valve 114 and the negative pressure channel 150 is shown by a solid line, and the connection between each valve 114 and the overpressure channel 140 is shown by a dashed line. The negative pressure can be provided at approximately 500 mBar to 900 mBar below atmospheric pressure, more preferably approximately 0.7 to 0.8 Bar below atmospheric pressure, i.e., approximately 200 to 300 mBar in absolute value.

[0066] Each valve 114 is typically controlled by a processing element (e.g., a processor) 160, which may take any suitable shape or form. The processing element 160 typically executes computer program code that instructs the processing element 160 on how to control the valves 114 and first carrier 102 during the imprint process, as described in more detail below.

[0067] By switching the aperture 112 to negative pressure, the flexible stamp 104 is attached to the first carrier 102. Additional attachment means may be provided, for example, around an edge portion of the flexible stamp 104. Such attachment means may comprise, for example, a clamp that secures the edge of the flexible stamp 104 to the first carrier 102, although in at least some examples, no additional attachment means is used.

[0068] The imprint apparatus 100 further comprises a second holder 170 (or carrier) that carries a substrate 180 to be imprinted.

[0069] The second holder 170 includes, for example, an aluminum or stainless steel chuck. The chuck is actuated for coarse alignment using a micrometer spindle. The chuck is surrounded by a plate that functions as a stamp landing device or stamp landing ring, which functions as described herein below. The device can be made of aluminum, stainless steel, or other solid material.

[0070] Water channels inside the chuck are used to heat and cool the chuck to control the heat-based curing of the resist layer.

[0071] Any suitable substrate 180 may be used, such as a silicon substrate, a silicon-on-insulator substrate, a silicon germanium substrate, or the like. To this end, the substrate 180 may carry a resist layer 182, which may be of any suitable material. For example, the resist layer 182 may comprise a curable material that may be solidified (cured) to fix the imprint pattern 106 in the resist layer 182. In one example, the resist layer 182 comprises a sol-gel material. Suitable examples of such materials are disclosed in WO 2009 / 141774 A1, although any suitable resist material may be used. For example, further examples of suitable resist materials can be found in U.S. Patent Application Publication No. 2004 / 0261981(A1), WO 2005 / 101466(A2), U.S. Patent Application Publication No. 2005 / 0230882, U.S. Patent Application Publication No. 2004 / 0264019, and the non-patent literature Advanced Materials (1998, Vol. 10(8), p. 571).

[0072] The first carrier 102 is controlled by the processing element 160. To this end, the imprint apparatus 100 further comprises means for positioning and repositioning the first carrier 102 relative to the second carrier 170 in three dimensions, represented by the three Cartesian coordinates X, Y, and Z, under the control of the processing element 160. Furthermore, means are provided for adjusting the relative position in the lateral direction (parallel to the second carrier 170) and the longitudinal direction (perpendicular to the second carrier 170), both by translation and orientation. In this example, the apparatus comprises automatic displacement means under the control of the processing element 160. The automatic displacement means comprise, for example, mechanical or electrical units providing mechanical or electrical feedback mechanisms for precisely controlling the relative X, Y, and Z position and orientation of the first carrier 102 with respect to the second carrier 170. Such displacement means are known per se and therefore, merely for the sake of brevity, will not be described in further detail.

[0073] The second carrier 170 may optionally be controlled by the processing element 160 in a manner similar to the control means described above for the first carrier 102, in order to increase the degrees of freedom of the imprinting apparatus 100. However, it is equally feasible to provide the imprinting apparatus 100 with a stationary or fixed second carrier 170.

[0074] The first carrier 102 is separated from the second carrier 170 by a gap 190, the size of which is controlled by the processing element 160, for example, by engaging means for positioning and repositioning the first carrier 102 relative to the second carrier 170. In a particular example, the processing element 160 is programmed to change the gap size between the imprint step and the release step. In particular, the processing element 160 may be programmed to increase the gap size upon completion of the imprint step (and after developing the resist layer 182), as increasing the gap size can aid in the release of the imprint pattern 106 from the developed resist layer 182.

[0075] The overpressure channel 140 includes a pressure controller 192 under the control of the processing element 160. This facilitates varying the overpressure, for example, during the imprint step or the release step.

[0076] The imprinting apparatus 100 has a user interface, such as a user terminal including at least one command input device, such as a keyboard, mouse, trackball, etc., that allows a user to configure the imprinting apparatus 100 in accordance with a desired imprinting process. It should be understood that any suitable user interface may be used.

[0077] As mentioned above, processing element 160 is arranged to control first carrier 102, valve 114 and / or pressure regulator 192. To this end, imprinting apparatus 100 further comprises a computer-readable data storage medium (not shown), such as a memory device, e.g., flash memory, RAM or ROM, solid-state disk, magnetic disk, etc. The data storage medium includes computer program code for execution by processing element 160, which causes processing element 160 to perform the various steps of the imprinting method. The data storage medium may be located in any suitable location in imprinting apparatus 100. The data storage medium may be integral to processing element 160 or may be a separate component accessible by processing element 160 in any suitable manner, for example via a data communications bus or a point-to-point connection between processing element 160 and the data storage medium.

[0078] A typical imprint process using the imprint apparatus 100 is as follows: A flexible stamp 104 containing an imprint pattern 106 is attached to a first carrier 102, for example, by switching a valve 114 so that the aperture 112 is connected to a negative pressure channel 150, which is connected to a negative pressure source such as a vacuum pump. The first carrier 102 is then positioned above a second carrier 170 carrying a substrate 180 coated with a resist layer 182, with the imprint pattern 106 facing the resist layer 182. The first carrier 102 is typically positioned relative to the second carrier 170 such that a gap 190 exists between the first carrier 102 and the second carrier 170, defined by a user of the imprint apparatus 100 to ensure good conformal contact between the flexible stamp 104 and the substrate 180 during imprinting. The gap 190 is selected in any suitable range, for example, in a typical SCIL in which the imprint pattern 106 is a nanoscale pattern, the gap 190 is selected in the range of 10 to 500 μm, preferably in the range of 20 to 200 μm, and more preferably in the range of 10 to 100 μm.

[0079] Once the first carrier 102 is positioned relative to the second carrier 170, the imprint process proceeds with an imprint step in which a contact area is formed between the flexible stamp 104 and the substrate 180, and the contact area is gradually expanded until the entire imprint pattern 106 intended to contact the substrate 180 is in contact with this substrate.

[0080] The imprint process is shown in Figure 3, in which the imprint pattern 106 has been omitted for clarity only.

[0081] As can be seen in the top row of Figure 3, an initial contact area 194 is formed between the flexible stamp 104 and the substrate 180 by individually switching selected apertures 112 from negative pressure to overpressure in the direction of horizontal arrows 200 above the overpressure channels 140. For clarity, only selected connections between the valves 114 and the respective channels 140 and 150 are shown in Figure 3. This causes a portion of the flexible stamp 104 to rise away from the first carrier 102 and toward the second carrier 170 to establish contact area 194 between the flexible stamp 104 and the second carrier 170, which includes the substrate 180 carrying the resist layer 182. A space 196 is formed between the first carrier 102 and the flexible stamp 104.

[0082] The contact area 194 is typically enlarged by periodically switching the next aperture 112 from negative pressure to overpressure by controlling the valve 114, thereby moving the contact front of the contact area 194 in the direction of the aforementioned arrow, as shown in the bottom part of Figure 3. This process is repeated until the contact area 194 is established over the entire desired area of ​​the substrate 180, i.e., until the desired portion of the imprint pattern 106 is in contact with the resist layer 182. The rate at which the contact area 194 enlarges is typically determined by the rate at which the next aperture 112 is switched to overpressure and the gap 190. The associated bridge width W, where the stamp does not contact either the first carrier 102 or the substrate 180, is selected, for example, between 10 mm and 50 mm.

[0083] Once the desired contact areas 194 between the imprint pattern 106 and the substrate 180 have been established, the resist layer 182 is then developed, e.g., hardened, in any suitable manner, e.g., by exposure to an external stimulus such as UV or visible light, heat, etc. This solidifies the resist layer 182 and fixes the imprint pattern 106 in the developed resist layer 182.

[0084] At this stage, the gap 190 is adjusted, i.e., increased, to shorten the duration of the release step, during which the imprint pattern 106 is released from the developed resist layer 182. Not all gap settings facilitate automatic release of the stamp. Depending on the type of imprint pattern 106 and resist layer 182, the stamp 104 can adhere to the imprinted, developed resist layer 182 with a relatively high contact area 194, and therefore force. The release force that can be generated is higher when the gap 190 is larger. For example, the stamp 104 may not be able to release from the developed resist layer 182 if the gap 190 is set to 50 microns, but may be able to release if the gap is 100 microns.

[0085] FIG. 4 is used to illustrate how the stamp is released. During the release step, individual apertures 112 are switched from overpressure channels 140 to negative pressure (vacuum) channels 150 by the processing elements 160 controlling their respective valves 114, causing the flexible stamp 104 to lift, i.e., the flexible stamp 104 is peeled away from the developed resist layer 182, thereby sealing the vacuum and shortening the bridge length W by one aperture pitch. This increases the force on the contact surface 194, further shortening the bridge as more apertures 112 are switched to negative pressure, displacing the contact fronts of the contact areas 194 in the direction of the horizontal arrows 210, as shown in the bottom row of FIG. 4. The bridge shortens until the force is equal to the release force of the imprint pattern 106 of the flexible stamp 104 from the developed resist layer 182 on the substrate 180 carried by the second carrier 170. It then relaxes upon release of the stamp. A larger gap 190 facilitates stamp release by providing a higher force normal to the substrate wafer, and the longer bridge length provided by this larger gap 190 allows more force to be applied before the vacuum seal is lost between the portion of the stamp 104 and the aperture 112 of the first carrier 102 that holds the flexible stamp 104 in place, e.g., the aperture 112 that contacts the outer edge of the flexible stamp 104.

[0086] It should be noted that during stamp release from the solidified resist layer, the flexible stamp 104 is in equilibrium with the force required to release the stamp. The next aperture 112 can be switched to negative pressure, e.g., vacuum, only after a portion (on average) of the flexible stamp 104, having a size corresponding to the distance from one aperture to the next, has been released. Therefore, the release speed of the flexible stamp 104 from the substrate 180 is also determined by the gap setting. For example, if the flexible stamp 104 can be released using gaps of 50 and 100 microns, the release speed for the 100-micron gap is higher than that for the 50-micron gap. Therefore, a higher release speed, i.e., the speed at which each individual aperture 112 is switched to negative pressure along the direction indicated by the horizontal line, can be applied by the processing element 160, i.e., by periodically switching the corresponding valve 114 to the negative pressure channel 150. For maximum throughput of the overall imprint process, the setting of the gap 190 for each imprint step differs from the gap 190 required for optimal stamp release during the release step shown in FIG. 4 .

[0087] Further details of the known printing process are disclosed in EP 3126909(A) and WO 2020 / 0099265.

[0088] As mentioned above, there is a desire to scale up the design to enable printing of larger wafers, such as 300 mm wafers. This results in increased required process forces (e.g., twice as high) and larger span widths (e.g., 300 mm diameter instead of 200 mm). Simply scaling up the existing design to maintain the required imprint gap variation, such as 5-10 μm, under process load is not possible. In particular, the second carrier 170 (including the chuck and supporting chuck frame) does not have sufficient rigidity.

[0089] In particular, the conventional C-frame design, which is implemented by connecting the chuck frame and the groove plate, bends under process loads, resulting in larger variations in the imprint gap, which significantly reduces the quality of the imprint process.

[0090] The chuck frame may also warp during heating, and although some warping is acceptable to a certain extent, no warping is permitted after cooling to room temperature.

[0091] The chuck frame also has a large thermal mass, resulting in long heating and cooling times. Thermal gradients across the chuck can also become excessively high as the size is scaled up.

[0092] There is a need to control the imprint gap for larger area chucks and groove plates (e.g., 300 mm diameter) while still allowing for easy loading of the stamp and wafer. This requires, for example, longer distance manipulation of the chuck relative to the groove plate (i.e., as part of the first carrier 102). For larger chucks, existing designs are difficult to manufacture with tolerances that allow sufficient rigidity to ensure gap control over the entire chuck area.

[0093] A first aspect of the present invention relates to a chuck manipulator.

[0094] Figure 5 shows the design of the chuck manipulator.

[0095] This view shows a chuck 500 surrounded by a stamping landing ring 502. The chuck 500 comprises a chuck frame 504. The position of the chuck frame is adjustable by a micrometer adjustment screw 506.

[0096] A single Z-stage actuator 510 controls the Z-axis position control of the chuck.

[0097] This first aspect of the present invention provides a two-part frame chuck manipulator.

[0098] 6 shows the entire system, including a subframe 600 on which the chuck 500 and stamping landing ring 502 are mounted. The chuck 500 is held by the subframe 600 and manipulated relative to the subframe 600 using a set of three short-stroke manipulators 620, which are discussed further below. The three short-stroke manipulators 620 (i.e., sometimes referred to as "chuck actuators") are angularly spaced around the chuck 500.

[0099] The subframe 600 is considered to be the main structural component of the second carrier and is thus considered to be equivalent to the support 170 in FIG.

[0100] The chuck is designed in this example to hold either a 200 mm wafer or a 300 mm wafer, and has, for example, an outflow channel around the outside of the 200 mm diameter and another outflow channel around the outside of the 300 mm diameter.

[0101] The subframe 600 can be a bolted assembly, but can also be a welded or 3D printed structure. The subframe 600, including the chuck, is treated as a subassembly attached to the mainframe 610. The mainframe 610 is manipulated relative to a fixed world, or reference frame 630, using a long-stroke driver 640 (i.e., sometimes referred to as a main actuator), which is sometimes referred to as the main actuator herein. Manipulation using the main actuator 640 allows for long-distance chuck manipulation (e.g., 50 mm or more, e.g., between 50 mm and 250 mm) for loading stamps and / or wafers or servicing chuck components. Furthermore, the main actuator 640 rigidly fastens (i.e., presses) the subframe 600 to the groove plate (i.e., as part of the first carrier 102), particularly to the groove plate holder 612 that holds the groove plate 102 and frame 103, so that the chuck can be short-stroke manipulated relative to the groove plate 102 to control the imprint gap. The short stroke may be about 5 mm or less, such as 50 μm or less.

[0102] At the same time, the sub-frame 600 and chuck 500 sub-assembly is biased toward the groove plate by a buffer spring arrangement 662, discussed below. This allows for design imperfections in the components that cause errors in the relative orientation of the sub-frame 600 to the groove plate. Errors resulting from movement can also be compensated for.

[0103] 6 shows that the sub-frame 600 has a set of contact buffers 670 through which the sub-frame 600 presses against the groove plate holder 612, as discussed further below. Also discussed in more detail below are three chuck actuators 620. The chuck actuators are positioned at the corners of a triangle (preferably an equilateral triangle), with the triangular frame defining the sub-frame 600, which in turn supports the chuck 500. Each chuck actuator includes a lever arrangement 621, as discussed below.

[0104] Three independent actuators and associated lever arrangements inside the subframe 600 support the chuck. In this way, the imprint gap is automatically adjustable (e.g., to + / - 1 μm) in the Z direction as well as for rotation about the X (R-Y) and Y (R-Y) directions. As will be shown below, support for the chuck is provided using a play-free, friction-free flexure mechanism.

[0105] Inside the subframe there are also three independent actuators (i.e., landing ring actuators) and levers that support the stamping landing ring, for translating a portion of the stamping landing ring in the Z-axis direction.

[0106] Therefore, the position of the stamp landing ring relative to the chuck is also automatically adjustable (up to + / - 1 μm) in the Z direction as well as for rotation about the X and Y directions. This allows adjustment for the thickness of the stamp and / or any taper of the stamp thickness since the stamp landing ring is contacted by the glass carrier plate of the stamp.

[0107] The setup illustrated above in the figures allows for tight control of the imprint gap and the orientation of the associated wedge of the stamping surface relative to the chuck surface, while still being able to apply long stroke operation of the chuck.

[0108] It should be noted that (XY) in-plane alignment of the stamp surface relative to the chuck surface, i.e., translation in the X and / or Y axes and / or rotation in the Z axis (RZ) of the stamp surface relative to the chuck surface, is achieved by manipulation of the groove plate 102 relative to its holder 612. The groove plate 102 has a groove plate frame 103 driven by three linear actuators (described further below), and the groove plate frame is supported by the groove plate holder 612 by air bearings 884, as will be further described below. Groove plate alignment is separate from gap (Z axis) alignment.

[0109] The use of separate long-stroke (main) and short-stroke (chuck) actuators provides very rigid support for the chuck in the Z-axis direction.

[0110] Three distance sensors are used to measure (and calibrate) the distance between the top of the chuck and the glass plate of the stamp, i.e., the groove plate. Three distance (and therefore position) sensors are also used to measure (and calibrate) the distance between the top of the stamp landing ring and the glass plate of the stamp. These sensors allow for automatic control of the chuck actuator and landing ring actuator without the need for manual adjustment.

[0111] FIG. 7 shows a plan view of the subframe 600.

[0112] The sub-frame 600 acts as a rigid body and internally accommodates process forces. The sub-frame 600 is a structure that extends around the chuck, such as a ring 602, which may be polygonal.

[0113] The sub-frame 600 is rigid and holds the chuck 500 and stamp landing ring 502. A landing ring actuator 620a is between the stamp landing ring 502 and the sub-frame 600, and a chuck actuator 620b is between the chuck and the sub-frame 600. The actuators can independently translate the three edges of the chuck / stamp landing ring in the Z-axis direction (e.g., perpendicular to the top surface of the chuck) relative to the sub-frame 600. These allow for maximum gap control for the entire chuck area and the stamp landing ring 502.

[0114] Fixtures are also used to ensure the thermal center of the chuck so that the subframe 600 remains in place during homogeneous expansion. The fixations define the connection between the chuck and the subframe 600. These fixations have enough play to allow for differential thermal expansion between the two parts, but once the kinematic coupling described above is formed, this play does not allow for any relative movement.

[0115] Returning to Figure 6, the sub-frame 600 is attached to (or rests upon in this case on) a main frame 610. The main frame 610 is slidably supported on a reference frame 630 (the outside world). A main actuator 640 is between the main frame 610 and the reference frame 630 to manipulate the main frame 630 (and also the sub-frame 600 and chuck) relative to the reference frame 630.

[0116] The groove plate holder 612 and the groove plate 102 are also attached to the reference frame 630 .

[0117] The attachment of the subframe 600 to the mainframe 610 is spring-damped in three locations. Two spring elements 662 are shown in FIG. 6. Although not shown, the spring elements 662 may include an outer, larger diameter damping spring and an inner, smaller diameter damping spring (not visible). The damping springs provide a compressive force while also serving to compensate for alignment errors. They provide a rigid connection between the subframe 600 and the channel plate 102.

[0118] As mentioned above, the sub-frame 600 has three (half-spherical with circular base) contact bumpers 670 on its top surface (opposite the side that rests on the main frame 610). The contact bumpers are spherical with circular bases. These contact bumpers are used to press the sub-frame 600 against the groove plate holder (at the kinematic coupling) when the imprinting machine is in the imprinting stage.

[0119] The buffer 670 is separated when the sub-frame 600 is lowered from the groove plate by manipulating the main frame 610 using the main actuator 640 to load a wafer or stamp. The compression is so strong that the groove plate holder and sub-frame 600 effectively become one rigid part. A spring-loaded connector 662 between the sub-frame 600 and the main frame 610 ensures that their connection compensates for any alignment error (from any cause) between the groove plate and the sub-frame 600. The spring arrangement 662 presses the sub-frame 600 against the groove plate holder.

[0120] In this way, gap control is independent of instabilities in the main frame 610 and reference frame 630, as it depends solely on the entire groove plate and sub-frame 600 acting as a single component.

[0121] The kinematic coupling between the subframe 600 and the groove plate holder may be based on balls and grooves rather than flat surfaced protrusions.

[0122] Subframe 600 is attached to mainframe 610 by three pins and three slots in area 666 .

[0123] The slots are oriented at angles of 0°, 120°, and 240°. The pins and slots have a few micrometers of play. However, this play does not cause any movement during the imprint process due to the high friction forces in the kinematic coupling provided by the buffer 670. The forces that the alignment motors can generate are much lower than the friction in the kinematic coupling.

[0124] As mentioned above, each spring arrangement 662 has a smaller diameter inner spring 664 within each larger diameter spring 662 for automatic mechanical overload protection. The two-spring design is optional. During normal processing, the main actuator (long stroke driver) operates at high speeds. The impact of a collision can cause serious damage to the groove plate. A collision can occur if there is material on the chuck that does not belong there, or if, for example, an excessively thick wafer is used.

[0125] The spring arrangement means that the subframe 600 is pressed up to the kinematic coupling by two springs in series at each corner of the subframe 600. The two springs have different force characteristics. Initially, only the weaker spring is used to raise the subframe 600. After contact with the kinematic mount, the stronger spring presses the subframe 600 against the kinematic mount. This two-stage approach provides the time needed to slow down the main actuator spindle drive motor.

[0126] As explained above, the chuck actuator 620 provides Z-axis positioning (i.e., perpendicular to the plane of the substrate and stamp). Z-axis positioning at three locations provides three degrees of freedom ("DOF") in that Z-axis translation and rotation about the X and Y axes can be controlled.

[0127] The groove plate has in-plane positioning control, provides X- and Y-axis translation, and can provide Z-axis rotation, thus enabling 6DOF positioning with a simple structure that maintains the desired carrier stiffness. Position control is split between the groove plate and the chuck.

[0128] In the above-described design, deflections of the reference frame 630 and / or the main (long stroke) actuator have no effect on the imprint gap. In particular, the sub-frame 600 is separated from the main actuator by contact buffers 670. In this way, separation of the force and position paths is established.

[0129] The above example utilizes a separate chuck actuator to move the chuck relative to the subframe 600 and actuators to move the groove plate. Alternatively, the chuck can be supported by a hexapod inside the subframe 600. The hexapod replaces the chuck's three chuck actuators 620. The hexapod can move in six axes. So-called overlay alignment for X- and Y-axis translation and Z-axis rotation (for alignment of the stamp relative to the wafer) is performed in the design shown above by moving the groove plates 102 and 103 inside the groove plate holder 612 or groove plate holder 888 in FIG. 14, which functions as an alignment station (see FIG. 14). In the case of a hexapod, this can also be done by moving the chuck with 6 DOF. However, this may pose additional challenges in enabling sufficiently accurate overlay alignment and sufficient Z-axis stiffness of the chuck support. Hexapods also offer less stiffness and less precise alignment, but allow for simpler modules that are less expensive to manufacture and develop, as they do not require linear actuators for grooves, air bearings, short-stroke manipulators, or flexible hoses.

[0130] As an alternative to the pins and slots 666 used to attach the subframe 600, bends, such as bends in a folded sheet, may also be used.

[0131] The illustrated configuration allows for automatic tilt adjustment of the chuck for rotation about the X and Y axes. In some designs, the position of the stamp landing ring relative to the chuck can also be automatically adjusted using position sensing. Wedge compensation is also possible (i.e., stamp parallelism errors).

[0132] A second aspect of the invention relates to a chuck design that again allows for the above-mentioned dimensional increases.

[0133] FIG. 8 shows chuck 500. The top image shows a perspective view of the top, and the bottom image shows a partial cutaway perspective view to reveal the internal structure. Chuck 500 has a flat top surface for receiving a wafer. Chuck 500 is designed to receive a 200 mm or 300 mm diameter wafer. Vacuum openings 800 are located approximately at the periphery of the wafer. These vacuum openings are for clamping the wafer. Radially outward of vacuum openings 800 are annular outflow grooves 801 that capture excess resist that may occur during the imprint step. Outflow grooves 801 prevent the chuck from being contaminated by wet resist on top of the wafer. Resist that does not come into contact with chuck 500 will not stick to chuck 500.

[0134] The top surface also has openings 802 that allow lift pins to pass through to raise and lower the wafer relative to the chuck 500 .

[0135] The chuck 500 is formed as a hollow structure. This allows it to have a large thickness to provide the required rigidity, yet a low thermal mass. The chuck 500 is generally cylindrical. Attachment points 810 are formed on the periphery, which engage with the chuck actuator 620. At each of these attachment points, there is also a sensor 812 that measures the spacing to the groove plate.

[0136] A hollow lattice structure is defined between the upper and lower surfaces. The upper and lower surfaces include a water channel configuration for temperature control. The same temperature control is provided on the upper and lower surfaces to provide symmetry and prevent buckling, e.g., the structure and water channel layout are identical.

[0137] The water channel arrangement, for example, covers the entire area of ​​the chuck. The temperature control of the top surface is for heating and cooling the wafer and, therefore, the resist layer disposed on the wafer.

[0138] Within the hollow region between the top and bottom surfaces is a lattice structure 814 to provide stiffness and rigidity. Thus, there is a sandwich design with a lattice structure within to provide the desired stiffness. The lattice structure can be, for example, a cubic lattice (simple, centered body, or centered face) or a hexagonal lattice. The cell size and beam size are selected to provide the required stiffness.

[0139] The connections for the water passages (eg, a set of water inlet ports and a single water outlet port) and the vacuum connection are all located on the underside of the chuck.

[0140] The chuck 500 is designed to be manufactured by powder bed fusion, for example, for metal 3D printing. The chuck is made from stainless steel. After 3D printing and powder removal, finishing is done by a milling machine. A lapping process at the end achieves the required flatness of 5 μm on the top surface.

[0141] Figure 9 shows the internal structure in more detail. The top part of Figure 9 is a cross section showing the upper and lower surfaces 820 and 830, each enclosing a channel configuration. Each surface is e.g., 5 mm thick, with a 1.5 mm skin above and below the 2 mm water layer.

[0142] The total thickness of the chuck is, for example, in the range of 40 mm to 100 mm.

[0143] Two vacuum openings 800 are shown as well as an outflow channel 801. Two alignment pin slots 802 are also shown.

[0144] The bottom part of Figure 9 is another cross section to show how heated water (e.g., 60-70 degrees) or cooled water (e.g., 20 degrees) is supplied to the upper and lower channel configurations. One water supply duct 840 is shown. There are, for example, six such supply ducts around the periphery of the chuck.

[0145] The supply duct 840 opens at its bottom to a channel formation in the lower surface 830 and also has a conduit 842 between the lower surface 830 and the upper surface 820 , which conduit 842 terminates in a channel formation in the upper surface 820 .

[0146] An upper surface 820 and a lower surface 830 surround the respective channel configurations. The central grid region of the chuck is sealed from the water supply.

[0147] The conduit 842 has a bellows structure so that axial stresses in the conduit can be compensated for by deformation of the conduit rather than causing deformation of the surrounding parts of the chuck, which can result in loss of flatness. However, the conduit bellows is an integral part of the structure of the chuck.

[0148] The chuck may, for example, have a single water outlet duct in the center of the chuck that collects the water after it has passed through the channel arrangement.

[0149] 10 shows a cross section of the entire chuck, which shows that the central water outlet duct 844 also has the same bellows design as shown in FIG.

[0150] FIG. 11 shows a set of ridges 850 within the upper or lower surface that define a channel configuration. Thus, FIG. 11 shows the open area of ​​the upper or lower channel configuration. The upper depiction is a plan view, and the lower depiction is a perspective view showing the three-dimensional nature of the ridges and protrusions. Six fluid inlet ducts 840 are spaced around the periphery, two of which are shown in FIG. 11 , with a single fluid outlet duct 844 shown in the center. The ridges 850 mean that water must follow a serpentine path from the fluid inlet duct locations to the fluid outlet duct, involving circumferential and radial path segments. The ridges 850 form a set of discontinuous annular paths, with the gaps in one annular path offset relative to the gaps in adjacent paths to define the serpentine path. In addition to the ridges acting as dams, struts 852 are present around the annular paths, which serve to support the surface and keep it flat, and may additionally or alternatively increase turbulence.

[0151] This design provides a uniform water temperature distribution covering all areas of the chuck, caused by multiple water mixing points.

[0152] All connections for water supply and removal and vacuum connections are located on the underside of the chuck (below), leaving space for a movable stamp landing ring around the chuck.

[0153] A thermal sensor may additionally be attached to the lower surface, so there may be sensors on the upper and lower surfaces to measure temperature.

[0154] FIG. 12 shows the underside of the lower surface, showing the peripheral water inlet connection 860, the central water outlet connection 862, the vacuum connections VAC1 and VAC2, and the cavity connections CAV1 to CAV6.

[0155] These cavity connections provide openings at various points on the chuck face for connection to a pressure source that applies negative or overpressure.

[0156] The cavities are used to allow printing on both sides of the wafer: after the first side is printed, the pattern should not be touched, and especially not pressed onto a flat surface once flipped over.

[0157] To enable double-sided printing, an interface plate 870, as shown in Figure 13, may be provided on top of the chuck. The interface plate is a metal or aluminum plate that can be removably positioned on top of the chuck. Figure 13 shows an example of an interface plate in perspective view (top) and cross-sectional view (bottom) above the chuck 500.

[0158] The interface plate 870 has a grid of openings 872 so that when the wafer 180 to be printed is placed on the interface plate 870 (with the first, already printed side facing down), the areas of the wafer to be printed (which will be diced to form separate products) align with the openings, and the grid lines 874 of the interface plate 870 overlie (are aligned with) the unpatterned areas of the wafer.

[0159] The openings may be straight through the plate 870 (e.g., 872a), as can be seen in the cross section of Figure 13, or may have an offset shape. They need to be deep enough to accommodate the substrate layer to be printed so that the surfaces are not touched. The extension of openings 872 to the side of the plate facing the chuck is positioned so that when the plate is attached to the chuck, the openings align with pressure lines 873 in the chuck.

[0160] By providing pressure lines 873 through the chuck 500 to the openings 872, the pressure within the cavities (openings) can be controlled simultaneously with the printing process. Specifically, by providing positive pressure in the presence of the stamp's printing ridges, counter pressure is used via the pressure lines to support the wafer against the pressure of the printing ridges during the printing process, instead of using a solid chuck surface. As the printing ridges advance in the direction of arrow 876, support pressure is applied sequentially to the first through fourth rows C1 through C4 of the openings 872. Thus, for example, the interface plate of FIG. 13 uses four cavity (opening) connections. However, there may be more rows of independently operable cavities; FIG. 12 actually shows six independently operable cavity connections CAV1 through CAV6 at the bottom of the chuck. The cavity connections are routed via pressure lines 873 to openings in the chuck, which are positioned within the openings 872. If no positive pressure is applied, a negative pressure can or is applied to those openings (which are closed on the side of the interface plate by the wafer).

[0161] Interface plate 870 is, for example, a 1 mm thick stainless steel plate with a set of notches, preferably formed by chemical etching. To mount the interface plate onto the chuck, the interface plate has, for example, a set of three apertures through which the receiving pins of chuck 500 slide. The interface plate also has vacuum grooves 878 in the areas between the apertures 872. The vacuum grooves 878 between and around the cavities clamp the wafer to the cavity plate.

[0162] Note that the interface plate may alternatively be an integral part of the chuck, in which case the plate is not removable from the chuck.

[0163] The openings 872, as described above, prevent contact between already imprinted structures and the wafer support. The interface plate also allows the wafer to be supported or clamped in any desired position. The openings connect to overpressure air and / or vacuum through the chuck. Openings and channels in the bottom of the interface plate connect the chuck's supply to the cavity.

[0164] The interface plate 870 has low thermal mass and high thermal conductivity so as to slow down the printing process as little as possible. The plate is preferably made from aluminum, although other materials such as stainless steel can be used. Stainless steel has a lower thermal conductivity than aluminum (which is less preferred), but the thinness of the plate allows such a low thermal conductivity to be used. Those skilled in the art will know how to balance the thermal properties of the material with the geometric design to arrive at a useful plate.

[0165] The required flatness and parallelism of the cavity plate is approximately + / - 5 μm. For stainless steel plates, this required flatness and parallelism can be achieved by using an etching process to form the cavities. Milling creates stresses in the material that can cause inadvertent deformation.

[0166] The interface plate 870 provides a lot of flexibility for implementing additional designs. The chuck 500 itself cannot be modified to imprint different designs. However, for each stamp design, a separate interface plate 870 can be designed and manufactured.

[0167] The use of pin and slot connections (e.g., two or more, preferably three or more pin and slot combinations) between the interface plate and the chuck can prevent movement due to thermal expansion and can also prevent or reduce distortion.

[0168] Here we will discuss some design options.

[0169] Stainless steel plates are preferred. For stainless steel plates, the plates are preferably thinner than 2 mm. Thin plates have lower thermal mass and higher thermal conductivity than thicker plates. Thin plates also have lower stiffness so that they can bend easily. The plate aligns itself with the planarized top surface of the chuck under vacuum force. Thin plates also exhibit good thermal transfer from the chuck to the cavity plate. Flatness requirements, which may be important for the imprint gap, are also met. Thin plates are also preferred due to the range of the chuck's short-stroke manipulator, such as 2 mm.

[0170] However, the plate should also not be too thin. If it is too thin, the vacuum channels cannot be made deep enough, resulting in too much flow loss and an insufficient vacuum. In that case, the force holding the wafer to the cavity plate is too small. The cavities and grooves can be or are made by a chemical etching process.

[0171] Stainless steel has a much lower thermal conductivity than aluminum. Nevertheless, the stainless steel plate will add less than approximately 2 seconds of heat-up time and 2 seconds of cool-down time.

[0172] Aluminum plates are possible, but are a less preferred option. Regarding aluminum interface plates, aluminum has better thermal conductivity and lower thermal mass than stainless steel. Therefore, aluminum can be made thicker for better manufacturability. Stress-free cast aluminum is only available in thicknesses of 10 mm and above. Regular aluminum sheet material already has excessive internal stress due to the rolling process of the raw material.

[0173] In the case of thicker plates, the vacuum channels can be made deep enough to allow sufficient flow and create a vacuum strong enough to hold the wafer. The cavities and grooves cannot be made by chemical etching processes in this case, which is not possible with aluminum. Alternative milling processes induce stresses in the material, which can lead to inadvertent deformation. Tension-free annealing may also be used.

[0174] A thicker aluminum plate is stiffer than a thinner stainless steel plate. However, the thicker aluminum plate does not align itself with the planarized top of the chuck. This creates a gap between the chuck and the cavity plate, which can lead to a vacuum leak and, consequently, no vacuum holding the cavity plate to the chuck. Furthermore, such a gap reduces heat transfer between the plate and the chuck, thus reducing heating and cooling rates during use of the device.

[0175] However, with aluminum plates, it is difficult to achieve the desired thermal transition from the chuck to the cavity plate and to meet the flatness requirements, which are important for controlling the imprint gap. Thicker plates are also undesirable due to the short stroke manipulator of the chuck. However, thicker plates can be used on printers with only one Z stage.

[0176] As mentioned above, a short stroke manipulator (ie, chuck actuator 620) is another aspect of the present design.

[0177] The same design of the short stroke manipulator can be used as a rigid support and drive arrangement for the chuck as well as for the stamping landing ring. When combined with the groove plate positioning as explained above, the short stroke manipulator is used to position the chuck and stamping landing ring with six degrees of freedom (i.e., three translations and three rotations).

[0178] The chuck, groove plate and stamping landing ring each need to be supported and precisely aligned with 6 DOF.

[0179] The groove plate can move in 3 DOF (X-axis translation, Y-axis translation and rotation about the Z-axis), while the other three (Z-axis translation and rotation about the X- and Y-axes) are fixed.

[0180] The chuck and stamping landing ring can move in 3 DOF (Z-translation and rotation about X and Y axes), while the other three (X-translation, Y-translation and rotation about Z axis) are fixed. One short-stroke manipulator supports 2 DOF (Z-translation and fixed X-translation).

[0181] The manipulators are used for fine adjustment of the chuck and stamping ring in the Z axis direction and for rotation about the X and Y axes. As will be explained further below, the chuck actuators are also used for force measurement and shock absorption.

[0182] Therefore, 6DOF alignment and manipulation between the stamp and the wafer is achieved by two separate alignment systems: (i) Stamp-to-wafer overlay alignment, translation along the X and Y axes and rotation around the Z axis are performed by groove plate alignment (i.e., stamp alignment). (ii) Imprint gap adjustment, translation along the Z axis and rotation about the X and Y axes are performed by three short-stroke manipulators (which provide support for the chuck).

[0183] For double-sided imprinting of wafers (as mentioned above), in addition to controlling the imprint gap, overlay alignment is essential. The overlay alignment specifications require very high positional accuracy. Friction- and hysteresis-free overlay alignment is crucial. A large alignment range also needs to be covered in the horizontal plane, such as a linear movement of up to 5 mm or even 15 mm. The force capacity of piezo stepper drives is also limited, such as a maximum of 50 N.

[0184] Controlling the imprint gap is achieved by the two-stage chuck support described above. For overlay alignment, two markers are used on the stamp and two on the wafer. The coordinates of these four markers are measured by a camera system on top of the groove plate. For this reason, the groove plate is transparent. Both the wafer marker and the stamp marker need to be within the focus (i.e., at the correct height) of the camera system.

[0185] The system compares the coordinates of the four markers and the transformation matrix is ​​used to calculate the desired movement for the three short-stroke actuators. This control loop can be repeated several times to reach greater accuracy.

[0186] As mentioned above, one option for controlling all 6 DOF is to operate the chuck only. As mentioned above, a hexapod could be used for this purpose. However, no hexapods that meet the requirements are commercially available. Splitting the alignment function in the manner outlined above makes it possible to meet the requirements.

[0187] One aspect of the present invention utilizes an alignment stage that includes a movable grooved plate carrier 612. The grooved plate carrier can be positioned by translation in the X and Y axes and Z-axis rotation (Rz) without any friction or backlash. A large alignment range in the horizontal plane is possible with a desired 5 mm (or even 15 mm) of linear movement.

[0188] FIG. 14 shows a drive configuration for the groove plate 102 (i.e., as part of the first carrier). This drive configuration functions as an alignment stage. The groove plate 102 has a groove plate frame 103 driven by three linear actuators 880, each coupled to an associated pair of air bearings 884 via flexures 886, as also shown in FIG. 6. While this is the preferred configuration, coupling is not essential. The actuators can also be positioned at various positions or angles, for example, three times rotated 120 degrees relative to each other and 60 degrees relative to the air bearings. These actuators are sometimes referred to as "carrier actuators" to distinguish them from the chuck actuators and stamp landing ring actuators. Flexible air tubes connect the groove plate to air valve terminals 882 to provide the printing pressure described above.

[0189] The groove plate frame can be positioned in the X axis, Y axis and Z axis rotation (Rz) without any friction or backlash.

[0190] Translation in the X and Y directions and rotation about the Z axis are established by three actuators 880. The required force for the linear actuators is, for example, not more than 50 N. The actuators are mounted to a fixed world (i.e., base 888) and connected to the channel plate frame 103 via three flexures 886. The three flexures allow lateral movement orthogonal to the actuator movement. Lateral shifting prevents the channel plate frame 103 from being overly constrained.

[0191] Three pairs of air bearings 884 are used for Z, Rx, and Ry fixation of the groove plate frame 103 inside the alignment stage. The air bearings are attached to a fixed world 888. At each of the three corners, two pairs of air bearings 884 clamp the groove plate frame. One air bearing is above the groove plate frame and one air bearing is below (as can be seen in FIG. 6, but shown as a single unit in FIG. 14). The groove plate frame 103 is clamped between the air bearing above and the air bearing below, so that the air pressure (in the Z direction) is equalized. The three corners define a fixed horizontal frame, and movement within its plane is allowed by each pair of air bearings. The allowed movement is, for example, approximately 10 mm and is mainly required for Rz adjustment.

[0192] One air bearing of each pair can be preloaded using a spring mechanism, as can be seen in Figure 6. This preload allows the air gap to remain constant under all circumstances. The height of the air gap is the dominant factor for the stiffness of the groove plate support in the Z direction.

[0193] The displacement coordinates of the frame 103 are calculated using the transformation matrix.

[0194] In use, the wafer marker is positioned at the correct focal depth by manipulating the chuck support to provide Z axis positioning, after which horizontal alignment can be performed.

[0195] Note that an alternative to six air bearings is a set of (e.g., three or four) folded leaf springs for Z-axis, Rx, and Ry fixation. The disadvantage compared to air bearings is that folded leaf springs require additional force from the linear actuator to move the groove plate. The leaf springs (e.g., folded leaf springs) must be tall, long, and thick enough to provide the required translation in the X and Y axes, and rotation about the Z axis (Rz), as well as the stiffness of the groove plate frame 103, resulting in greater force requirements for the (e.g., groove plate) actuator.

[0196] 15 shows in more detail the design of the short stroke actuator 620 used as the chuck actuator. The same actuator can be used for the stamping landing ring, as well as sensors (described below) for machine damage protection.

[0197] The chuck actuator includes a drive element 900, such as a piston, that drives an actuator tip 902 up and down. The position of the actuator tip 902 is fixed relative to the sub-frame at connection 903, which is rigidly connected to the real world (i.e., reference frame 630) during printing as discussed below, so that movement of the actuator results in an actuator output 904, in the form of a drive connection, moving up and down. A tension spring 906 pulls the short-stroke actuator upward. The top of the tension spring connects to a pin 907, which is also connected to the sub-frame. The spring compression varies over the same distance as the stroke of the short-stroke manipulator.

[0198] The tension spring 906 is adjustable, ensuring a preloaded manipulator with no play. The adjustment is made by a threaded tube 908 that adjusts the position of one end of the spring (e.g., the end opposite the pin 907). The pretension of the tension spring 906 determines the allowable stamp release force. The higher the spring force, the higher the release force can be. The spring pretension can not be too high due to the limited allowable load on the integrated force sensor 920, discussed below.

[0199] The actuator 900 includes a lever assembly having an actuator output 904 at one end and a chuck driver 910 at the other end. Along the lever assembly is a pivot point 912, which is configured as a cross flexure pivot. A fixed part 914 of the lever assembly connects to a reference frame (e.g., subframe 600), and a main body 916 of the lever assembly is the movable part of the pivot point 912, swinging about the pivot point. The lever ratio is defined as the ratio of the distance (d2) between the pivot point 912 and the actuator output 904 to the distance (d1) between the pivot point and the chuck driver 910. An example lever ratio (d2:d1) is 4:1.

[0200] For example, a lever with a lever ratio of 4:1 ensures that the support provided in the chuck driver 910 is over four times more accurate and 16 times stiffer in the Z-axis direction than if the actuator 900 did not have a lever arrangement. Thus, the use of a lever provides better control of the imprint gap.

[0201] A force sensor 920 is integrated inside the lever to measure the process load, allowing for better monitoring of the imprint process. The force sensor 920 is part of a rigid loop, with the force sensor being placed in series with the actuator.

[0202] The main body 916 of the lever is divided by a groove 930, e.g., 0.2 mm. The moment created inside the lever by the actuator force is transferred through the sensor 920 and notched flexure 932 without any hysteresis. The sensor in this example measures a force of 0.443 times the load based on the ratio of d1:d3 (e.g., 30 mm to 67.71 mm), where d3 is the rotation arm length from the notched flexure to the force sensor.

[0203] Connection 903, pin 907, and fixed part 914 all connect to subframe 600. However, in use with a subframe that presses against a groove plate, the subframe becomes rigidly connected to the reference frame (via a kinematic coupling). Thus, subframe 600 presses against part 612 via kinematic coupling 670.

[0204] The force sensor 920 includes a force sensor element 940 that is biased by a compression spring 942 against a seat above the split 930 .

[0205] The seat provides overload protection for the sensor. The force sensor element 940 is pressed against the seat by a pre-compressed spring 942. The seat only moves against the bias of the spring if the force on the sensor exceeds, for example, 250N.

[0206] As long as the force sensor element is pressed against the seat in the absence of excessive force, the overload protection has no effect on the rigid loop.

[0207] The actuator tip 902 of the drive element 900 is limited by a stopper 950 that is fixed relative to the reference frame.

[0208] The stopper 950 includes a ring that is pressed against the tip by a spring 952. The ring is able to move against the bias of the spring when the force on the sensor exceeds, for example, 250 N. As long as the tip is not compressed by the spring against the stopper, the spring has no effect on the rigid loop. This prevents the actuator spindle from being damaged by impact forces.

[0209] The force sensor and actuator are thus protected from shock overloads; for example, the load on a force sensor should be limited to between -30 and +300 N, otherwise the sensor or actuator may be damaged.

[0210] Negative forces on the sensor are prevented by the split groove design. The split groove inside the lever becomes wider in the case of negative forces, so the sensor lifts from its contact point. Therefore, the force is zero. However, positive forces can be higher than 300 N due to impact, and therefore the force limiting configuration described above is used.

[0211] The force sensor can also detect stuck stamps and can be used to prevent machine damage.

[0212] Stamp sticking is a problem that is preferably detected. Stamp sticking occurs when the stamp release sequence after the imprint process does not work. This situation can occur if the stamp has been used too many times. The rubber relief part of the stamp no longer detaches from the wafer.

[0213] At the end of the imprint process, the stamp support (e.g., a glass or metal plate) is held against the groove plate by vacuum, and the wafer is held against the chuck by vacuum. The groove plate, stamp, wafer, and chuck now function as one monolithic body. Typically, after the imprint and stamp release sequence, the chuck is lowered, in this case by the chuck actuator and the main actuator. At this time, the chuck is raised and the actuators lose contact.

[0214] In such a case, the gap between the actuator tip 902 and the stopper 950 may have a dimension of, for example, 2 mm to 8 mm. If the chuck is suddenly dropped, it may fall downward by approximately 0.5 mm to 2 mm. This causes an impact with a collision force of approximately 5000 N on the actuator. This impact can result in failure of the force sensor and damage to the actuator spindle.

[0215] Lifting the chuck requires protecting the groove plate from excessive loads. The main actuator 640 can easily cause too much pulling force from the stamp on the groove plate. Therefore, by detecting a stuck stamp, the main actuator can be stopped. Thus, the groove plate is protected from damage.

[0216] 16 shows an end view of the chuck driver 910 mounted between the lever and the chuck. The chuck driver 910 has a cross flexure 960 in the middle of its width (e.g., perpendicular to the Z axis), which allows some rotational movement across the width of the chuck driver, e.g., about the Y axis for the example shown.

[0217] The purpose of this movement is to allow the chuck driver 910 to assume the proper position after the chuck tilt has been adjusted.

[0218] The chuck driver 910 includes a shortening compensation leaf spring.

[0219] As the lever rotates about pivot 912, the right (short) side of the lever shortens as viewed from the center of the chuck. This shortening is a parasitic action of the lever. Its projected length onto the plane of the chuck is shortened to a length L(l-cos(φ)), where φ is the angle of rotation of the lever. Thus, the lever arrangement is compensated so that the position of the chuck in the X and Y directions does not change in response to adjustments to the Z direction position.

[0220] This design allows the three chuck actuators to move independently through the full stroke of the lever, which allows for zeroing the output of each actuator and prevents over-constraining the chuck.

[0221] Forces applied to the chuck in the X and Y axis directions (parallel to the wafer) are routed through the cross flexures 912 of the three levers and the cross flexure 960 of the chuck driver 910. Each lever thereby provides two degrees of freedom, translation along the Z and X axes.

[0222] The short-stroke manipulator design is used as a chuck actuator for moving the chuck and as a landing ring actuator for moving the stamp landing ring. Thus, two short-stroke manipulators, one constituting a chuck actuator and the other constituting a landing ring actuator, can be placed at each corner of the triangular subframe 600. This provides a modular design.

[0223] Note that in this design, the tension spring 906 not only pulls the sensor tip onto the lever, but also the actuator tip onto the stop. However, two separate springs could be used. This means that the load on the sensor is not affected (or is less affected) by adjusting the pretension of the tension spring and / or by different positions of the lever.

[0224] As mentioned above, another aspect of the present invention is the ability to control the position of the stamp landing ring. Some further improvements regarding the stamp landing ring are discussed below.

[0225] As explained above, before starting the imprinting process, the substrate (wafer) is brought very close to the stamp, for example, 25 μm to 300 μm, creating a process gap. The grooves in the groove plate are continuously pressed, causing the stamp to rise from the groove plate toward the substrate and be supported by the process gap and the substrate until it makes contact with the substrate. During contact, the resist layer on the substrate solidifies, and after solidification, the stamp is detached by applying vacuum to the grooves again. Thus, the process of applying the stamp to the substrate relies on a pressure difference between the area of ​​the stamp held by the groove plate and the area of ​​the stamp pressed toward the substrate. This difference occurs at the edge of the stamp. This difference can cause pressure leakage, resulting in uncontrolled stamp application and / or detachment. Generally, the larger the process gap between the groove plate and the substrate (or chuck), the greater the leakage and the associated pressure loss under the stamp. Therefore, the process gap must be precisely controlled across the entire area of ​​the stamp.

[0226] Various stamps differ from one edge to the other. There are areas of the support (groove plate) that are not covered by the stamp material at the edge. This area is therefore unsupported during the stamping operation, since only the supported wafer and the stamp are in contact. This lack of support allows the stamp to rise beyond the set process gap in these areas, which can cause further leakage.

[0227] The stamp landing ring described above surrounds the chuck to provide stamp support at this edge region, thereby preventing the entire raised flexible stamp area from rising beyond the set process gap. However, different stamp and substrate (wafer) combinations require actively controlled different thicknesses and gaps, with different areas outside the stamp and different stamp thicknesses.

[0228] The stamp landing ring is an additional edge support structure that supports that part of the composite stamp, thereby preventing the stamp at the edge from rising beyond the set process gap.

[0229] FIG. 17 shows the process using a stamping landing ring.

[0230] The above depiction shows the substrate 180 elevated above the chuck 500 by supporting wafer lift pins 1000, and the chuck spaced apart from the groove plate 102 on which the stamp 106 is mounted. The chuck 500 is driven relative to a chuck assembly, such as the subframe 600, by a chuck actuator 620a.

[0231] The stamp landing ring 502 is driven relative to the sub-frame 600 by a landing ring actuator 620b.

[0232] The above configuration allows the substrate 180 and stamp 106 to be loaded and unloaded.

[0233] The imprint locations are shown below.

[0234] The process gap between the substrate 180 and the stamp 106 is the same as the process gap between the stamp landing ring 502 and the groove plate (or more specifically the glass support plate of the stamp) outside the area where the stamp material is present.

[0235] The use of separate chuck and landing ring actuators allows various combinations of substrate (wafer) thickness and stamp thickness to be accommodated.

[0236] As shown, the stamp landing ring can be driven to a height above the surface of the substrate being imprinted, so that the same process gap is below the imprint pattern and below the stamp around the outside of the imprint pattern.

[0237] Additionally, further improvements discussed below enable various imprint configurations for different combinations of stamp size (plan view) and wafer size (plan view), for example, a 200 mm or 300 mm substrate with a 200 mm or 300 mm stamp.

[0238] FIG. 18 shows a substrate 180 supported on a chuck 500. A stamp landing ring 502 supports an area outside the actual stamping area. FIG. 18 shows a stamp landing ring adapter 1002 on top of the stamp landing ring. The adapter design has the same shape and size as the stamp landing ring, thus providing thickness matching. For example, FIG. 18 shows a 300 mm wafer 180 with a 300 mm PDMS stamp 106. The process gap is defined by the distance between the wafer, the stamp, the adapter 1002, and the stamp's thin glass support.

[0239] However, the stamping landing ring adapter may also employ a stamping landing ring depending on the size of the substrate.

[0240] FIG. 19 shows an example where the stamp landing ring 502 is for fitting around a substrate of a first size (e.g., 300 mm) and the stamp landing ring adapter 1002 is for expanding the size of the stamp landing ring 502 to fit around a substrate 180 of a second, smaller size (e.g., 200 mm).

[0241] In FIG. 19, the stamp landing ring 502 is for fitting around a flexible stamp 106 of a first size (e.g., 300 mm), and the stamp landing ring adapter is for expanding the size of the stamp landing ring to fit around a flexible stamp 180 of a second, smaller size (e.g., 200 mm).

[0242] Thus, Figure 19 shows a 200 mm substrate (wafer) along with a 200 mm PDMS stamp. The process gap is defined by the distance between the wafer, stamp, adapter, and thin glass. The adapter extends above and beyond the 300 mm chuck to support the PDMS stamp outside the wafer area. Because the ring is relatively thin, it can bend downward due to pressure under the stamp. This can be compensated for by moving the stamp landing ring up relative to the chuck.

[0243] FIG. 20 shows an example in which the chuck 500 is for fitting around a flexible stamp 106 of a first size (e.g., 300 mm), and there is a second stamp landing ring 1004 on the chuck that fits around a smaller substrate 180 of a second size.

[0244] Figure 20 shows that a 300 mm PDMS stamp would be used for a relatively thin wafer (e.g., 200-300 µm). An overhanging stamp landing ring may not have a sufficiently high bending stiffness to compensate for the pressure exerted by the stamp. The maximum thickness for such a stamp landing ring is the thickness of the wafer.

[0245] The stamp bends the free-hanging parts down too much, causing the stamp to not transfer well onto the wafer, causing imprint defects at or around the wafer edge and stamp / pattern deformations that degrade overlay alignment.

[0246] By having a second stationary stamp landing ring as shown around the wafer that has the same thickness as the substrate (wafer), the movable stamp landing ring 502 can be used to compensate for variations in stamp thickness and wedge due to the chuck, and the entire stamp is still properly suspended over the entire area. The stationary ring 1004 does not need to be changed because wafer thickness is typically not an issue, within + / - 10 μm or even + / - 25 μm, and the stamp can smoothly transition from the stationary ring 1004 to the wafer.

[0247] Figure 21 shows an example suitable for imprinting a relatively thick 200 mm wafer (e.g., 0.5-2 mm) using a 300 mm stamp; therefore, the stamp must also be correspondingly thick. The stamp landing ring adapter 1002 can be rigid enough to counteract the pressure from the stamp on the overhanging part. Still, the outer rubber area of ​​the stamp must be supported so that the stamp does not rise further than the process gap. This can be achieved by using a stamp landing ring with two thicknesses. The additional outer thickness provided by the second adapter 1006 compensates for the stamp thickness.

[0248] The adjustable drive provided by the landing ring actuator reduces the need to exchange stamp landing rings to account for different stamp and substrate combinations, allowing (on-the-fly) adjustment for a wide variety of wafer and stamp thicknesses and wedge angles, resulting in an optimized imprint process for each case.

[0249] The optimized process gap results in reduced pressure loss and improved reproducibility of imprint quality with reduced pattern distortion and improved overlay alignment.

[0250] For example, the stamp and wafer thicknesses need to have known thicknesses within approximately 10 μm, since the process gap is desired to be defined within this range. The same tool and stamp hardware and sizes can be used to handle a wide variety of combinations of wafer and stamp sizes.

[0251] The chuck actuator and landing ring actuator allow dynamic changes to the gap between the stamp and substrate during different stages of the process (eg, alignment, imprint, release).

[0252] The printing process requires loading a stamp onto a groove plate. In existing machines, the stamp is loaded by pivoting open the top cover that carries the groove plate. The cover can be manually rotated 180° so that the groove plate is upside down. The stamp can then be placed glass-side up on the groove plate. The grooves now have a small overpressure, which creates an air bearing for the stamp. Therefore, the stamp can be easily moved and aligned manually.

[0253] The position is then fixed by switching on the vacuum in the groove. After this, the cover is closed again and the imprint process can begin. In the event of a power down or vacuum loss, the stamp will fall onto the chuck. To remove the stamp, the top cover can be easily opened manually in the same manner.

[0254] The designs described above, with groove plate alignment stages for overlay alignment and increasing wafer size, mean that it is undesirable to have a pivotable cover as it would be too large, too heavy and too fragile.

[0255] Therefore, another design aspect relates to a semi-automatic stamp loading function, where the stamp loads from below the groove plate. The design approach described below also means that if the hold on the stamp is lost (due to power or vacuum loss), the machine does not need to be opened. Integrated stamp drop protection prevents the stamp from falling, and the stamp can be unloaded via the normal unload sequence.

[0256] Figure 22 shows a design using a semi-automatic stamp load.

[0257] FIG. 22 shows the groove plate 102 above the stamp 104. The stamp is attached to a stamp carrier 1100, which is positioned in a frame, specifically a sliding telescopic drawer 1102. The stamp carrier 1100 and the drawer together are considered to comprise a stamp loader. The stamp carrier 1100 comprises a frame with a central opening to avoid contact with the rubber stamp material (PDMS). Thus, the stamp carrier 1100 supports the glass substrate of the stamp, and the stamp does not move or sink because the outer rim of the stamp is held by a vacuum. The telescopic drawer 1102 moves the stamp carrier 1100 horizontally from a load position (outside the module) to a park position and then to a transfer position.

[0258] The modular long stroke driver 640, described above, is used to vertically raise and lower the stamp carrier 1100.

[0259] Stamp 104 is shown above chuck 500 and stamp landing ring 502. The stamp landing ring is positioned by stamp landing actuator 620a and the chuck is positioned by chuck actuator 620b.

[0260] This stamp loading mechanism automatically loads and unloads the stamp 104 from below without opening the top cover. The groove plate 102 is positioned by the downward groove. A stamp drop protection part 1104 is also integrated inside the frame of the groove plate 102.

[0261] The stamp 104 is held by vacuum to the outer rim of the stamp carrier 1100 by vacuum channel 1101. The stamp carrier 1100, for example, has two separate vacuum channels: one channel is used when the carrier is placed in the telescoping drawer 1102, and the other channel is used when the stamp carrier is placed in the stamp landing ring 502. The presence of the stamp is detected by measuring the vacuum pressure.

[0262] Here, the stamp load sequence will be described. (i) The operator opens the module door. (ii) The operator pulls out the telescoping drawer 1102 to the load position outside the module. (iii) Place the stamp carrier 1100 in the drawer mechanism. (iv) An operator manually places the stamp on the stamp carrier 1100. Thus, steps (i) to (iv) involve loading the stamp into a stamp carrier in a drawer (stamp loader) if the stamp is located outside the imprint position. (v) A first vacuum channel of vacuum channels 1101 provided by drawer 1102 keeps the stamp in place. Thus, the suction channel of the stamp carrier is used to hold the stamp to the stamp carrier. (vi) The operator manually pushes the drawer into the park position and closes the machine door. (vii) A pneumatic cylinder or other actuator pulls the drawer into the transfer position, which is above the stamp landing ring 502 and chuck 500 and below the groove plate 102, as shown in Figure 22. This therefore involves moving the stamp loader (drawer and stamp carrier) into the space between the first carrier and the second carrier. (viii) The long stroke driver 640 supporting the chuck 500 and stamp landing ring 502 is raised until the stamp landing ring 502 touches the stamp carrier 1100. The three support pins of the stamp carrier 1100 are centered in the three holes or slots in the stamp landing ring (these can be seen in FIG. 22). This involves moving the second carrier towards the first carrier, thereby moving the stamp carrier and held stamp towards the first carrier. (ix) A second vacuum channel of the vacuum channels 1101 provided by the stamp landing ring takes over clamping of the stamp and the first vacuum channel can be switched off. (x) The long stroke driver 640 raises the stamp carrier 1100 just a few mm above the drawer mechanism, which moves the stamp carrier 1100 from the telescoping drawer 1102 to the stamp landing ring 502. (xi) The drawer mechanism is returned from the transfer position to the park position by a pneumatic cylinder or other actuator to prevent collision with the long stroke driver 640. (xii) The long stroke driver 640 raises the stamp carrier directly below the groove plate 102. At this point, the stamp drop guard 1104 is active (open), thus transferring the held stamp to the first carrier (groove plate). (xiii) The grooves of the groove plate 102 are switched to vacuum so that the stamp 104 is held by the groove plate 102. There is then a transfer of the held stamp to the groove plate (first carrier). (xiv) Switch off the second vacuum channel of the stamp carrier. (xv) The long stroke driver 640 then lowers the stamp carrier 1100 to the transfer height, thereby separating the second carrier (chuck) from the first carrier (groove plate). (xvi) The stamp drop protection unit 1104 is then either kept in an enabled state or disabled (closed). The stamp drop protection unit 1104 can be kept in an enabled state because it does not interfere with the stamp carrier 1100 being lowered at that time. (xvii) The drawer 1102 is moved by a pneumatic cylinder or other actuator back under the stamp carrier 1100, ie, to the transfer position. (xviii) Lower the long stroke driver 640 until the carrier 1100 is supported by the drawer. A few mm of clearance is required. (xix) The drawer is retracted by the pneumatic cylinder to its park position, thus moving the stamp loader back to a position outside the imprint position, which may be the parking position.

[0263] The loaded stamp is then ready to be used. The stamp is unloaded by the reverse procedure.

[0264] An integrated stamp drop protector prevents the stamp from falling uncontrollably into the chuck.

[0265] Typically, three or four clamps support the stamp at the corners or outer rim of the stamp. The stamp drop protection includes, for example, a spring-loaded mechanism to keep the stamp clamped in the event of a loss of power, vacuum, or air pressure. As outlined above, the stamp drop protection must be opened to load and unload the stamp. In the closed (clamped) position, the stamp drop protection interferes with the stamp carrier.

[0266] During the normal manufacturing cycle (i.e., no stamp loading), the stamp drop guard remains closed (i.e., clamped). The stamp drop guard is designed so that it does not interfere with the stamp landing device during the normal cycle. An opening in or around the stamp landing ring can be used to allow for all motions (linear and rotational) of the clamp.

[0267] If the stamp is not fixed to the groove plate (e.g. due to an accident) and is only clamped by the stamp drop protection, the stamp can be removed by performing the normal stamp unload sequence with the stamp carrier - no manual intervention by the operator (opening the module as before) is required.

[0268] The stamp loading process is described as semi-automatic in that the stamps are manually loaded into the drawer. However, the drawer design may be used as a step toward fully automating stamp loading and unloading in the future. Currently, an operator manually places the stamps in the carrier, and the telescoping drawer moves the carrier in and out. In the future, this may be done by a robot in the cluster tool. This may be the robot currently used to load and unload wafers or an additional robot. The robot's end effector must be adapted to handle the stamp carrier and provide vacuum to hold the stamp. The robot can then take on the role of the drawer. Inside the cluster tool, a stacking system may be installed to accommodate stamp carriers loaded with new stamps and empty stamp carriers.

[0269] There are various design aspects described above, which may be used alone or in combination. In particular, these design aspects are: Drive of the Z axis movement of the chuck to the two stages by separate long stroke and short stroke drivers. This allows a very rigid support to be formed. Use of a lever arrangement for the chuck actuator and / or stamping landing ring actuator. The lever arrangement allows for improved positioning accuracy and increased stiffness compared to direct control of position using the actuator output. A chuck including a hollow cylindrical body having upper and lower surfaces and a lattice structure between the upper and lower surfaces, the chuck having reduced thermal mass while maintaining the required stiffness to maintain a uniform imprint gap. Use of a landing ring actuator to translate a portion of the stamp landing ring in the Z-axis. The movement of the stamp landing ring in addition to the movement of the chuck allows the apparatus to account for various stamp thicknesses. An interface plate that mounts on top of the chuck with a pressurized cavity to allow double-sided printing. Stamp support system to allow semi-automatic (or even fully automatic) stamp loading. Splitting of position control between the stamp carrier and groove plate carrier to allow for full 6DOF control while allowing sufficient stiffness between the two.

[0270] In the above example, the first carrier includes an array of apertures that are used to attract the flexible stamp to the first carrier and push the flexible stamp away from the first carrier. A pressure source in combination with the apertures provides the actuator function. However, other actuators may be used, for example, electromagnetic actuators or other actuators may be used to provide the push / pull function.

[0271] It should be noted that the above-described embodiments are illustrative rather than limiting of the present invention, and that those skilled in the art can design many alternative embodiments without departing from the scope of the appended claims. In the claims, any reference signs placed between parentheses shall not be construed as limiting the claim. The word "comprises" does not exclude the presence of elements or steps other than those listed in a claim. The word "a" or "an" preceding an element does not exclude the presence of a plurality of such elements. The invention can be implemented by means of hardware comprising several distinct elements. In a device claim enumerating several means, several of these means may be embodied by one and the same item of hardware. The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measures cannot be used to advantage.

Claims

1. a first carrier carrying a flexible stamp having an imprint pattern, the first carrier including an array of actuators adapted to attract the flexible stamp to the first carrier and to push the flexible stamp away from the first carrier; a second carrier movable relative to the first carrier, the second carrier being positioned to receive a chuck carrying a substrate having a resist layer thereon; An imprinting apparatus comprising: The second carrier comprises: Chuck and a stamp landing device arranged outside the chuck along at least a portion of the chuck, the stamp landing device facing the first carrier carrying the flexible stamp outside the area of ​​the imprint pattern; a set of landing device actuators that translate a portion of the stamp landing device in a direction perpendicular to a plane of the second carrier.

2. The imprinting apparatus of claim 1 , wherein the chuck includes a set of position sensors that measure a distance from a surface of the chuck to the first carrier.

3. 3. The imprint apparatus of claim 2, wherein the set of position sensors includes three position sensors each measuring a distance from the chuck to the first carrier, each position sensor being proximate to a respective first actuator.

4. An imprinting apparatus according to claim 1 , wherein the second carrier comprises a set of position sensors that measure a distance from the stamp landing device to the first carrier.

5. the imprint apparatus, The mainframe and a mainframe actuator that translates the mainframe in a direction perpendicular to the plane of the second carrier; Furthermore, the second carrier further includes a set of chuck actuators that translate a portion of the chuck in a direction perpendicular to the plane of the second carrier; The imprinting apparatus of claim 1 , wherein the chuck actuators each have a stroke that is smaller than a stroke of one or more chuck actuators that translate a portion of the chuck relative to the mainframe.

6. The imprinting apparatus of claim 5 , wherein the second carrier further includes a sub-frame, the sub-frame connected to the main frame, and the chuck attached to the sub-frame.

7. The imprinting apparatus of claim 6 , wherein the sub-frame is attached to the main frame by a spring arrangement.

8. The imprinting apparatus of claim 7 , wherein the spring arrangement is for biasing the sub-frame against the first carrier via a kinematic coupling during imprinting.

9. The imprinting apparatus of claim 1 , further comprising a stamp landing device adaptor that is positioned on the stamp landing device to adapt the stamp landing device according to a thickness or size of the substrate.

10. 10. The imprint apparatus of claim 9, wherein the stamp landing device is for fitting around a substrate of a first size, and the stamp landing device adapter is for expanding the size of the stamp landing device to fit around a substrate of a second, smaller size.

11. 10. The imprinting apparatus of claim 9, wherein the stamp landing device is for fitting around a flexible stamp of a first size, and the stamp landing device adapter is for expanding the size of the stamp landing device to fit around a flexible stamp of a second, smaller size.

12. 10. The imprinting apparatus of claim 9, wherein the chuck is for supporting a substrate of a first size, the imprinting apparatus further comprising a second stamp landing device that fits over the chuck around a substrate of a second, smaller size.

13. The imprinting apparatus of claim 1 , wherein each chuck actuator includes an actuator output portion and a lever arrangement between the actuator output portion and the chuck drive member.

14. 4. The imprinting apparatus of claim 1, wherein the chuck comprises a hollow cylindrical body having an upper surface and a lower surface, a grid arrangement between the upper surface and the lower surface, and an internal water channel arrangement providing a flow path between a set of water inlets and a water outlet.

15. a stamp landing device for placing around the outside of a chuck of an imprinting apparatus, the stamp landing device facing a first carrier carrying a flexible stamp having an imprint pattern thereon, the first carrier and the stamp landing device facing each other outside the area of ​​the imprint pattern; a set of landing device actuators for translating a portion of the stamp landing device in a direction perpendicular to a plane of a second carrier carrying the chuck; A stamp landing system for an imprint apparatus, comprising:

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