Alignment method for imprint method

Abstract

1. A method of detecting a detection angle in a lithographic apparatus, comprising: a calibration substrate having a refractive index n and having a first pair of markers, the markers having a predetermined lateral displacement relative to one another, a first marker in the pair being at a first predetermined vertical position within the calibration substrate and a second marker in the pair being at a second predetermined vertical position within the calibration substrate, the calibration substrate being mounted on a first surface thereof; illuminating the marker pair with a light source and detecting light redirected from the first and second markers with a detector having an optical axis that is oriented at a detection angle of less than 90° with respect to a normal to the substrate; α1 and determining a first detected angle based on a first detected lateral displacement between the first marker and the second marker.

Description

[Technical Field]

[0001] The present invention relates to the field of alignment in imprint lithography, and in particular flexible stamp imprint lithography. [Background technology]

[0002] Imprint lithography of the type disclosed in EP 3126909A is gaining interest as a viable alternative to more traditional mask-based optical lithography techniques because it promises to provide smaller feature sizes over large areas in patterns transferred onto substrates, such as semiconductor device substrates. In imprint lithography techniques, such as substrate conformal imprint lithography (SCIL), a flexible stamp containing a feature relief pattern on its surface is contacted with a resist material. The resist material is imprinted with the feature pattern and then developed, e.g., cured, while imprinted. The feature pattern is then released from the resist material, leaving a patterned resist layer on the substrate.

[0003] In this process, a curable, fluid resist layer is applied to a substrate (e.g., a wafer) supported by a chuck. A flexible stamp, e.g., rubber, is used, and the resist layer can be cured (solidified) during imprinting to leave a hardened relief complementary to the relief layer of the stamp after the stamp is peeled from the resist. The imprinting process requires a thin, flexible stamp formed from a polydimethylsiloxane (PDMS) rubber layer bonded to a thin, flexible plate, e.g., a metal or glass plate, to be placed on a stamp manipulator with the relief side of the PDMS layer facing away from the glass plate. This positions the glass plate facing the stamp manipulator, and the relief side of the stamp facing the resist layer.

[0004] During the imprint process, the surfaces of the stamp and the resist layer of the substrate are held approximately parallel to each other in the XY plane and at a small mutual distance along the Z axis direction (sometimes called the vertical direction).

[0005] The stamp can be locally manipulated using a stamp manipulator, e.g., locally and sequentially released from and attached to the stamp manipulator by the stamp manipulator. In one example, the stamp manipulator has openings extending along its surface (XY plane), which can be individually manipulated with a set pressure, such as overpressure or underpressure, to hold the stamp (underpressure) or release the stamp (overpressure). During the imprinting process, releasing the stamp at one XY position (e.g., at an edge) creates initial contact between the relief surface and the resist at that position. The stamp is then gradually released from the stamp manipulator and contacts the resist layer, thereby expanding contact from the initial contact position along the X and / or Y axes, depending on the release scheme.

[0006] Alignment of the stamp and substrate uses markers on the stamp and substrate, respectively. The markers on the stamp and substrate are illuminated and the redirected light is detected to determine the position of the markers (absolute position or relative and to each other). The position of the stamp can then be compared to the position of the substrate to ensure the stamps are correctly aligned. If they are not correctly aligned, the stamp and / or substrate must be moved accordingly.

[0007] The inventors recognized that imprint lithography relies on contact between the stamp and the substrate, making it difficult to correct misalignment after initial contact is established, and therefore alignment must be performed before imprinting begins. However, this complicates alignment because alignment must be performed when a relatively large gap (i.e., Z-axis distance) exists between the stamp and the substrate. For example, if the light used for illumination is not perpendicular, a relatively large gap can cause parallax errors, resulting in inaccurate marker position measurements. Alternatively, if the camera is not perpendicular to the stamp / wafer surface, this can also introduce parallax errors.

[0008] Another challenge is to avoid problems caused by non-normal illumination of the substrate.

[0009] Some implementations may use illumination that is not perpendicular to the substrate, and in these situations it is important to know the exact detection angle and to avoid problems caused by the substrate being illuminated at an incorrect angle. Summary of the Invention [Problem to be solved by the invention]

[0010] Therefore, the imprinting procedure requires improved alignment to reduce or eliminate this misalignment problem, even in the presence of relatively large gaps. [Means for solving the problem]

[0011] The present invention is directed to addressing one or more of these problems.

[0012] According to the present disclosure, there is provided a method for determining a detection angle (e.g. in a lithographic apparatus and / or imprint system), the method comprising: using a calibration substrate having a refractive index n and having a first pair of markers, the markers having a predetermined lateral displacement from each other, a first marker of the pair being at a first predetermined vertical position within the calibration substrate and a second marker of the pair being at a second predetermined vertical position within the calibration substrate that is different from the first predetermined vertical position, the calibration substrate being mounted on a first surface thereof; illuminating the marker pairs with a light source; detecting light redirected from the first marker and the second marker with a detector having an optical axis at a detection angle α1 less than 90° (or greater than 0°, or less than 90° and greater than 0°) with respect to a normal to the substrate to determine a first detected lateral displacement between the first marker and the second marker; determining a first detected angle based on the refractive index n of the substrate and a first detected lateral displacement between the first marker and the second marker.

[0013] By detecting the detection angle, the parallax error due to the detection angle and the gap between the stamp and the substrate can be determined and accounted for. For example, from a known gap with a known parallax error, the displacement in the x and y directions can be calculated. The first and second markers may overlap when viewed along the perpendicular axis.

[0014] Determining the detection angle allows for the calculation and compensation of parallax errors during imprinting in several ways. Thus, rather than having to correct the detection angle to be perpendicular to the substrate, knowing the detection angle allows for the parallax errors to be calculated and compensated for in subsequent calculations and alignment steps. Furthermore, determining the detection angle allows for the calculation and compensation of parallax errors resulting from substrates being made from materials with different refractive indices.

[0015] Thus, rather than attempting to reduce or eliminate parallax as in previous systems and methods, the present invention has non-perpendicular detection that allows for the parallax to be calculated. In summary, the detection in the present invention is non-perpendicular and the resulting parallax is used to determine the detection angle.

[0016] In some implementations, a desired, non-perpendicular detection angle may be required, and in these implementations, the detection angle may be calculated and changed or modified to the desired angle.

[0017] The methods and systems presented herein can be used to initially determine the camera tilt or detection angle, but can also be used later to ensure that the camera angle remains stable over time by repeating the measurement.

[0018] The methods and systems presented herein can be used in imprint systems such as imprint lithography apparatus, or in particular substrate conformal imprint lithography apparatus that use deformable stamps, all of which require alignment between the substrate and stamp to be completed prior to imprinting, as described below.

[0019] The method further comprises: rotating the calibration substrate to place it on a second, different surface; illuminating the marker pairs with a light source; detecting light redirected from the first marker and the second marker and determining a second detected lateral displacement between the first marker and the second marker; and determining a second detected angle α2 based on a second lateral displacement detected between the first marker and the second marker.

[0020] By rotating the calibration substrate toward its second surface, the same marker pair can be detected and measured again. The first and second detection angles can be averaged. Turning the calibration substrate upside down reverses the error for a given lateral displacement.

[0021] The markers can be contrast markers configured to reflect light or diffractive markers configured to diffract light.

[0022] The lateral displacement between the first and second markers (i.e., in the XY plane) can be zero, or there can be a minimal amount of lateral displacement so that the first and second markers can be illuminated simultaneously without one marker blocking light from reaching the other marker.

[0023] The first detection angle α1 is given by the following equation:

number

[0024] The detection angle α2 is given by the following formula:

number

[0025] The method further comprises: providing a stamp including a stamp marker; illuminating the stamp marker with a light source; detecting light from the light source redirected by the stamp marker; and determining a lateral position of the stamp marker using at least the first detected angle.

[0026] Similar to detecting the stamp marker, the substrate marker can be detected, and the method further comprises: providing a second substrate including substrate markers; illuminating the substrate marker with a light source; detecting light from the light source redirected by the substrate marker; and determining a lateral position of the substrate marker using at least the first detected angle.

[0027] Once the positions of the stamp marker and the substrate marker are determined, the degree of alignment can be determined. As an advantage, this method improves the accuracy of alignment detection.

[0028] Another implementation assumes that the light source maintains a fixed detection angle relative to the substrate or substrate surface. The present invention can be used to determine the detection angle and, if it is not within a predetermined range, move the light source to a different detection angle.

[0029] According to the present invention, there is provided an alignment system for determining alignment between a stamp and a substrate in a substrate conformal imprint lithography process, the system comprising an alignment system and a substrate comprising first and second markers having a refractive index n and a predetermined lateral displacement relative to each other, the first marker of the marker pair being at a first predetermined vertical position within the substrate and the second marker of the marker pair being at a second predetermined vertical position within the substrate that is different from the first predetermined vertical position. A light source and an optical sensor having an optical axis and configured to detect light from the light source redirected by the substrate, the optical axis of the optical sensor at a detection angle α1 that is less than 90° with respect to a normal to the substrate (preferably the angle is not 0°); a processing system communicatively connected to the light source and the light sensor.

[0030] The alignment system is configured to receive a calibration substrate, and the processing system is configured to determine a first detection angle α1 based on a first detected lateral displacement between a first marker and a second marker on the calibration substrate when the calibration substrate is received in the alignment system.

[0031] The processing system may be further configured to control the alignment system to perform the following steps: illuminating the marker pair with a light source; Detecting light redirected from the first marker and the second marker and determining a first detected lateral displacement between the first marker and the second marker.

[0032] There is also provided an imprint system for performing an imprint process, the imprint system having an alignment system as defined herein.

[0033] The imprint system is configured to include a stamp holder for holding and manipulating an imprint stamp, and a substrate holder for holding a substrate to be imprinted, the lateral X-Y positions of which can be controlled and varied, and the imprint system may further include a calibration substrate holder for holding a calibration substrate.

[0034] Any imprint system as defined herein may be configured to carry out any one of the methods as defined herein.

[0035] The computer program product includes computer program code means which, when executed by an alignment system or imprint system (e.g., a processing system thereof) as described herein, causes the alignment system to perform all of the steps of any one of the methods described herein.

[0036] The present disclosure relates to the alignment of markers, for example in SCIL processes, especially when the detector is positioned substantially perpendicular to the substrate, which has the drawback that the signals from the substrate marker and the stamp marker become mixed and indistinguishable.

[0037] The processing system of the alignment system may be configured to control the operation of the illumination system and / or the light sensor to control the alignment system in performing a defined function.

[0038] A computer program product is provided which includes computer program code means which, when executed by an alignment system as described above, causes the system to perform all the steps of the method as described above.

[0039] These and other aspects of the invention will be apparent from and elucidated with reference to the embodiments described hereinafter. [Brief explanation of the drawings]

[0040] For a better understanding of the disclosed method and system, and to show more clearly how it may be carried into effect, reference will now be made, by way of example only, to the accompanying drawings in which: [Figure 1A] 1A and 1B show cross-sectional views of an imprint process performed by an imprint system. [Figure 1B] 1A and 1B show cross-sectional views of an imprint process performed by an imprint system. [Figure 1C] 1A and 1B show cross-sectional views of an imprint process performed by an imprint system. [Figure 2A] FIG. [Figure 2B] FIG. 10 illustrates an alternative calibration substrate. [Figure 3] 1 illustrates the method of the present invention. [Figure 4] FIG. 10 is a diagram showing the illumination of a marker pair. [Figure 5]A close-up of the light incident on the first marker. [Figure 6] FIG. 1 is a simplified block diagram of a computer in which one or more portions of the embodiments may be used. DETAILED DESCRIPTION OF THE INVENTION

[0041] The present invention will now be described with reference to the drawings.

[0042] The detailed description and specific examples, while indicating exemplary embodiments of the apparatus, systems and methods, are intended for purposes of illustration only and are not intended to limit the scope of the invention. These and other features, aspects and advantages of the apparatus, systems and methods of the present invention will become better understood from the following description, the appended claims and the accompanying drawings. 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.

[0043] Variations to the disclosed embodiments can be understood and effected by those skilled in the art in practicing the claimed invention, from a study of the drawings, the disclosure, and the appended claims. In the claims, the word "comprising" does not exclude other elements or steps, and the indefinite article "a" or "an" does not exclude a plurality.

[0044] The figures are only schematic and are not drawn to scale. The same reference numbers are used throughout the figures to denote the same or similar parts.

[0045] Embodiments propose a mechanism for aligning a stamp and a substrate during an imprint process, such as a substrate conformal imprint lithography (SCIL) process. A stamp marker is disposed on the stamp, and a substrate marker is disposed on the substrate. The markers can include diffraction gratings, but can also include other types of markers. The two markers can be illuminated with the same light or two different lights. Each marker is configured to redirect one type of light (received by that marker) relatively more than the other marker toward a light sensor.

[0046] 1A, 1B and 1C illustrate the manufacturing process to enhance contextual understanding.

[0047] Known processes for the fabrication of microdevices involve the successive application of device layers to a substrate. A typical process cycle for applying such device layers involves the deposition of a layer of a desired material, e.g., an insulator or a (semi-)conductor, followed by structuring, or so-called patterning, of the applied layer.

[0048] In the present disclosure, the structuring of the material layer is carried out using an imprinting or embossing method. This process involves applying (in a cycle of steps) a material layer 102 to the surface 101 of the substrate 100, for example, as droplets using inkjet printing or uniformly distributed over the substrate surface 101 using spin-coating or doctor blade techniques. Any other application technique can be used as well. The applied material layer 102 can be shaped.

[0049] As shown in Figure 1A, a stamp 104 having a relief surface 106 representing a pattern 106' that needs to be replicated or imaged in material layer 102 is positioned above substrate 104 at a distance D between substrate marker 103 and stamp marker 105. Once stamp 104 and substrate 100 are properly aligned, material layer 102 of the stamp is brought into contact with the stamp, which imprints the shape of the relief surface onto material layer 102, as shown in Figure 1B.

[0050] While the stamp 104 is in contact with the material layer 102 (as shown in FIG. 1B ), the material layer first adopts (e.g., conforms to) the shape of the relief surface 106 of the pattern 106′ and is then hardened beyond (re)formability using some curing process. Examples of curing processes are using a chemical reaction to solidify the layer under the application of heat or radiation, or solidification by solvent removal from the layer, as described in Publication Nos. EP 2,087,403 A2 and EP 2,091,666 A2 and the references cited therein.

[0051] After stamp 104 is removed from material layer 102, a formed relief material layer remains having a relief surface 108 that represents the complementary pattern 108 of pattern 106' (FIG. 1C). This formed material layer can serve as a base for patterning a substrate layer using some etching process, or can serve directly as a patterned device layer, with or without further modification or processing.

[0052] In some printing processes, the stamp is a hard stamp that does not deform substantially. Such a stamp can be made of, for example, quartz.

[0053] In other printing processes, such as the SCIL process, the stamp is deformable. Such a stamp can be manipulated into contact with the substrate gradually during the imprinting process by temporarily deforming the stamp during the contact step of the process. In such cases, the illustrated stamp 104A would have a conformable relief portion comprising a rubber, elastomer, or other deformable polymer material. A particularly advantageous example of such a deformable polymer includes or consists of a polysiloxane-based polymer. Often, although not necessarily, the relief portion is supported (e.g., glued) by a relatively rigid yet deformable support portion in the form of, for example, a (thin) glass plate (not separately shown in FIGS. 1A, 1B, and 1C). This helps improve manipulation of the stamp 104A by the stamp holder (also called the stamp manipulator) 104B.

[0054] In some embodiments, the stamp holder can include a groove plate, for example, in the form of a glass plate with one or more grooves. The groove plate is rigid and includes at least one groove, but preferably includes multiple grooves 105, within which the pressure of gas can be controlled to manipulate the stamp. For example, a low pressure (compared to ambient pressure) can be applied, causing the stamp to be pulled into or firmly held by the groove plate (via support portions, if the stamp includes such support portions). Conversely, release of the stamp can be achieved by increasing the pressure to ambient pressure or above. For clarity, only a limited number of system components are shown, but detailed descriptions of how such systems are designed and used to carry out such imprint methods are provided in the following documents, each of which is incorporated herein by reference in its entirety: WO03099463A2 "METHOD AND DEVICE FOR TRANSFERRING A PATTERN FROM A STAMP TO A SUBSTRATE"; WO2008068701A2 "METHOD AND APPARATUS FOR APPLYING A SHEET TO A SUBSTRATE"; WO2008087573A2 "METHOD AND SYSTEM FOR CONTACTING OF A FLEXIBLE SHEET AND A SUBSTRATE"; WO2016045961A1 "TRANSFER METHOD AND APPARATUS AND COMPUTER PROGRAM PRODUCT" (and references cited therein).

[0055] Generally, in devices with multiple stacked device layers, the pattern in one device layer must be laterally aligned (laterally meaning in the XY plane) with the pattern in one or more other such layers or the base substrate. For example, successive layers of semiconductor substrate 100 must be properly aligned with each other for the resulting device to function. After all, if the layers are not properly aligned, signals will not be transmitted between the layers and the device will not function properly. Therefore, alignment steps are also performed between the application of new device layers.

[0056] In the exemplary process as described herein, this means that an alignment step must be performed before the stamp 104 contacts the material layer 102 (e.g., the situation depicted in FIG. 1A ), because lateral repositioning of the substrate 100 and stamp 104 when they are in contact would be difficult or impossible, or could result in dragging or undesired deformation of the material layer 102, or could result in damage to the stamp.

[0057] For alignment purposes, the substrate includes one or more substrate markers 103, and the stamp 104A also includes one or more stamp markers 105, e.g., as part of its conformal portion. To properly align the stamp with the substrate and the patterned layer underlying the stamp, the markers on the stamp must be properly aligned with the markers on the substrate. The stamp and substrate need to be aligned within a certain margin in the XY plane.

[0058] The present disclosure relates to improved approaches for aligning a stamp with a substrate. The following description provides a descriptive understanding of embodiments whose features can be interchanged and / or combined.

[0059] The method of the present invention uses a calibration substrate 100 as depicted in FIG. 2A. The calibration substrate 100 is formed from a material having a refractive index n that is substantially transparent to the light used to detect the markers. The calibration substrate has first markers 111 and 112 on a first surface 110 of the calibration substrate and second markers 121 and 122 on a second surface 120 of the substrate. Thus, there is a known, predetermined displacement (DW) in the z-direction between the first and second markers. Each of the first markers 111 and 112 has a corresponding second marker nearby (in the X-Y plane), thereby forming a marker pair. In the example of FIG. 2A, the first marker (e.g., 111) and the corresponding second marker (e.g., 121) are at the same lateral position in the X-Y plane.

[0060] However, in some examples, the first and second markers may have a predetermined lateral displacement in the XY plane relative to one another. An alternative calibration substrate is depicted in FIG. 2B, which has a small predetermined lateral (i.e., in the XY plane) displacement X . N The calibration substrate 100 has a first marker 111 and a second marker 121 having a Z-axis direction Dw. Furthermore, although this is not required, the first marker is not on the substrate surface but within the calibration substrate 100. However, again, the displacement Dw between the first and second markers in the Z-axis direction is known.

[0061] The calibration substrate may form an integral part of the lithographic apparatus or may be removable, and may have means for removably attaching it to the apparatus, such means may include clamps, clips and / or screws, etc.

[0062] Each of the first and second markers can be either a reflective marker, such as a chrome marker, or a diffractive marker, such as a grating structure.

[0063] Referring to FIG. 3, the method 200 disclosed herein includes a step of using or providing a calibration substrate 100 placed on its first surface 110 and a step 220 of illuminating the marker pair 111, 121 with light, for example from a light source.

[0064] Referring also to FIG. 4 , the light source 310 illuminates the calibration substrate 100 with a beam of light at a non-perpendicular angle γ. In this example, both the first marker 111 and the second marker 121 are illuminated simultaneously. This is not necessary per se; alternatively, or additionally, they can be illuminated at different times. In either case, the illumination is such that the markers can be distinguished from the light redirected by them. Thus, the first marker redirects light toward the detector 320, and in this shown example, the second marker redirects light toward the same detector. While different detectors may be used, a single detector may be advantageous due to space limitations and / or cost and / or accuracy considerations.

[0065] The detector 320 has an optical axis and detects light along the optical axis. The optical axis along which light is detected forms a detection angle α with the normal to the substrate. Thus, light propagating at an angle α toward the detector is detected. Based on the redirected light from the first and second markers, the relative lateral positions (in the XY plane) of the first and second markers can be detected, and the lateral displacement between the first and second markers can be determined. The detection angle α can be determined (240) from the detected lateral displacement between the first and second markers. The detection angle is the angle of detection relative to the normal to the substrate.

[0066] FIG. 5 is a close-up view of light redirected from a first marker 111 of the calibration substrate 100. For simplicity, the corresponding second marker and its redirected light (reflected or diffracted) are not shown in FIG. 5. As can be seen, the light changes path at the boundary between air and the calibration substrate 100 due to the refractive index n. The detection angle is α, and the reflection angle β is less than α because the refractive index of the calibration substrate is greater than that of air. The lateral shift (in the X-Y plane) between the vertical position of the second marker 121 (second surface 120 in this example) and the vertical position of the first marker 111 (first surface 110 in this example) due to non-normal illumination of the markers is expressed as X w which can be calculated as follows:

number

number

number

[0067] To improve the accuracy of detection, the calibration substrate 100 can be rotated to rest on its second surface 120, and the process can be repeated. That is, the marker pair is illuminated by the light source 310 and detected by the detector 320. Based on the detected redirected light, the lateral displacement is detected, and a second detection angle α2 is determined. An average can be taken between the first detection angle and the second detection angle.

[0068] There may be several pairs of markers on the calibration substrate 100, and the same process may be repeated for each pair of markers. Each pair of markers has the same lateral displacement X N and vertical displacement D W Alternatively, each pair of markers may have a different lateral and / or vertical displacement from the others. If there are eight pairs of markers on the calibration substrate and the substrate is placed on the first and second surfaces and each pair of markers is detected, a total of 16 detections are made. An average detection angle can be determined.

[0069] Once the detection angle is determined, it can be used as part of the alignment process of the imprint method. Ultimately, the detection angle represents the orientation of the detector. For example, a stamp marker on a stamp can be detected using the same detector 320 (in an unaltered, or in other words, calibrated, position). Using the determined detection angle and knowing the vertical position of the stamp marker, the lateral position of the stamp marker can be accurately determined relative to any other marker at any other given vertical position.

[0070] The determined detection angle can be used in a similar manner to determine the lateral position of a substrate marker on a second substrate. As an example, there may be a distance of 20-300 microns between the top surface of the second substrate and the bottom surface of the stamp. The substrate marker is illuminated and the redirected light is detected. Using the determined detection angle and knowing the vertical position of the substrate marker, the lateral position of the substrate marker can be accurately determined.

[0071] The positions of the stamp marker and the substrate marker, both determined using the determined detection angle, can be compared to detect the alignment of the stamp and the second substrate before the stamp is imprinted onto the second substrate. If the substrate and stamp are aligned within a predetermined level of accuracy, imprinting can proceed. However, if they are not aligned with sufficient accuracy (e.g., within 5% of the feature size), the stamp and / or substrate can be moved to correct the misalignment.

[0072] In some examples, the camera or detector 320 is intended to detect at a predetermined detection angle. In these examples, the determined detection angle can be compared to the predetermined detection. If necessary, the angle or position of the camera (or detector) can be changed. The new detection angle can then be determined again and compared again to the predetermined detection.

[0073] An alternative application of the present invention is to ensure that the detected angle is stable over an extended period of time, for example, the detected angle can be verified after a predetermined period of time, thereby preventing the accuracy of the device from gradually deteriorating during use.

[0074] Determination of the detection angle can be completed once before imprinting a substrate, as described above. Additionally or alternatively, it can be completed after n substrates have been completed. For example, the detection angle can be determined or checked every 100 substrates printed.

[0075] The calibration process to determine the detection angle can be automated or performed manually. A marker at a first position on the z-axis can be detected using pattern recognition. The relative lateral position of a corresponding second marker can be known, allowing the second marker to be detected.

[0076] For each pair of markers, the following equation can be written: X n = Ax + Sx n ; Y n = Ay + Sy n

[0077] X n and Y n is the measured shift, n indicates the number of measurements (16 in this example), Ax and Ay represent the parallax error, and Sx n and Sy n is the known correct shift of the wafer. In total we have 16 equations for X with unknown variable Ax, and 16 equations for Y with unknown variable Ay. This is a system of linear equations that are solved with a linear least squares approximation. In this way we can calculate the parallax errors Ax and Ay.

[0078] The present invention may also include a processing system 350 communicatively coupled to the light source 310 and the light detector 320 and configured to determine a detected angle based on the detected lateral displacement between the first marker 111 and the second marker 121 on the calibration substrate 100.

[0079] The processing system 350 can additionally be configured to control the alignment system to illuminate the marker pair and detect, by the photodetector 320, the light redirected by the first and second markers.

[0080] The processing system 350 of the alignment system may be configured to control the operation of the illumination system 400 and / or the light sensor 300 to control the alignment system in performing defined functions.

[0081] The present invention may also be embodied as a computer program comprising computer program code means adapted to implement the method as described above when executed by the alignment system described above.

[0082] 7 illustrates an example of a computer 70 in which one or more portions of the embodiments may be employed. The various operations described above may utilize the functionality of the computer 70. For example, one or more portions of the system for providing a subject-specific user interface may be incorporated into any of the elements, modules, applications, and / or components described herein. In this regard, it should be understood that the system functional blocks may be executed on a single computer or distributed across multiple computers and locations (e.g., connected via the Internet), such as in a cloud-based computing infrastructure.

[0083] The computer 70 may include, but is not limited to, a PC, a workstation, a laptop, a PDA, a palm device, a server, storage, etc. Generally, from a hardware architecture perspective, the computer 70 may include one or more processors 71, memory 72, and one or more I / O devices 73 communicatively coupled via a local interface (not shown). The local interface may be, for example, but not limited to, one or more buses or other wired or wireless connections, as known in the art. The local interface may include additional elements, such as controllers, buffers (caches), drivers, repeaters, receivers, etc., to enable communication. Additionally, the local interface may include address, control, and / or data connections to enable appropriate communication between the aforementioned components.

[0084] Processor 71 is a hardware device for executing software that may be stored in memory 72. Processor 71 may be virtually any custom or commercially available processor, central processing unit (CPU), digital signal processor (DSP), or coprocessor among several processors associated with computer 70, and processor 71 may be a semiconductor-based microprocessor (in the form of a microchip) or microprocessor.

[0085] The memory 72 can be any one or combination of volatile memory elements (e.g., random access memory (RAM), e.g., dynamic random access memory (DRAM), static random access memory (SRAM), etc.) and non-volatile memory elements (e.g., ROM, erasable programmable read-only memory (EPROM), electronically erasable programmable read-only memory (EEPROM), programmable read-only memory (PROM), tape, compact disc read-only memory (CD-ROM), disk, diskette, cartridge, cassette, etc.). Furthermore, the memory 72 can incorporate electrical, magnetic, optical, and / or other types of storage media. The memory 72 can have a distributed architecture in which various components are located remotely from each other but are accessible by the processor 71.

[0086] The software in memory 72 may include one or more separate programs, each including an ordered list of executable instructions for implementing logical functions. According to an exemplary embodiment, the software in memory 72 includes a suitable operating system (O / S) 74, a compiler 76, source code 75, and one or more applications 77. As shown, application 77 comprises multiple functional components for implementing the features and operations of the exemplary embodiments. According to an exemplary embodiment, application 77 of computer 70 may represent various applications, computational units, logic, functional units, processes, operations, virtual entities, and / or modules, although application 77 is not intended to be limiting.

[0087] Operating system 74 controls the execution of other computer programs and provides scheduling, input / output control, file and data management, memory management, and communication control and related services. It is contemplated by the inventors that application 77 for implementing the exemplary embodiment may be applicable to all commercially available operating systems.

[0088] The application 77 can be a source program, an executable program (object code), a script, or any other entity comprising a set of instructions to be executed. In the case of a source program, the program is typically converted via a compiler (such as compiler 76), assembler, interpreter, etc., which may or may not be contained in memory 72 and operate appropriately in conjunction with the O / S 74. Additionally, the application 77 can be written in an object-oriented programming language, which has classes of data and methods, or a procedural programming language, including, but not limited to, C, C++, C#, Pascal, BASIC, API calls, HTML, XHTML, XML, ASP script, JavaScript, FORTRAN, COBOL, Perl, Java, ADA, .NET, etc.

[0089] The I / O devices 73 may include input devices such as, but not limited to, a mouse, keyboard, scanner, microphone, camera, etc. Additionally, the I / O devices 73 may include output devices such as, but not limited to, a printer, display, etc. Finally, the I / O devices 73 may further include devices that communicate both input and output, such as, but not limited to, a network interface card or modulator / demodulator (for accessing remote devices, other files, devices, systems, or networks), radio frequency (RF) or other transceivers, telephone interfaces, bridges, routers, etc. The I / O devices 73 also include components for communicating over various networks, such as the Internet or an intranet.

[0090] If computer 70 is a PC, workstation, intelligent device, etc., the software in memory 72 may further include a basic input / output system (BIOS) (omitted for simplicity). The BIOS is a set of essential software routines that initializes and tests hardware at startup, starts O / S 74, and supports data transfers between hardware devices. The BIOS is stored in some type of read-only memory, such as ROM, PROM, EPROM, EEPROM, etc., so that the BIOS can be executed when computer 70 is started.

[0091] When computer 70 is operating, processor 71 is configured to execute software stored in memory 72, to communicate data to and from memory 72, and to generally control the operation of computer 70 in accordance with the software. Applications 77 and O / S 74 are read, in whole or in part, by processor 71, possibly buffered within processor 71, and then executed.

[0092] It should be noted that if application 77 is implemented in software, application 77 may be stored on virtually any computer-readable medium for use by or in connection with any computer-related system or method. In the context of this specification, a computer-readable medium may be an electrical, magnetic, optical, or other physical device or means that can contain or store a computer program for use by or in connection with a computer-related system or method.

[0093] The application 77 may be embodied in any computer-readable medium for use by or associated with an instruction execution system, apparatus, or device, such as a computer-based system, a processor-containing system, or other system that can fetch instructions from and execute instructions from the instruction execution system, apparatus, or device. In the context of this document, a "computer-readable medium" may be any means that can store, communicate, propagate, or transfer a program for use by or in connection with an instruction execution system, apparatus, or device. The computer-readable medium may be, for example, but is not limited to, an electric, magnetic, optical, electromagnetic, infrared, or semiconductor system, apparatus, device, or propagation medium.

[0094] The proposed image capture and / or processing method can be implemented in hardware or software, or a combination of both (e.g., as firmware running on a hardware device). To the extent that an embodiment is implemented partially or entirely in software, the functional steps illustrated in the process flowcharts can be performed by appropriately programmed physical computing devices, such as one or more central processing units (CPUs) or graphics processing units (GPUs). Each process, and its individual component steps illustrated in the flowcharts, can be performed by the same or different computing devices. According to an embodiment, a computer-readable storage medium stores a computer program including computer program code configured to cause one or more physical computing devices to perform an encoding or decoding method as described above when the program is executed on the one or more physical computing devices.

[0095] The storage medium includes volatile and non-volatile computer memory such as RAM, PROM, EPROM, and EEPROM, optical disks (such as CDs, DVDs, and BDs), and magnetic storage media (such as hard disks and tapes). Various storage media may be installed in a mobile computing device or may be transportable such that one or more programs stored on the storage medium are read by a processor.

[0096] To the extent that embodiments are implemented partially or entirely in hardware, the blocks shown in the block diagrams of Figures 1 and 5 may be separate physical components, logical subdivisions of a single physical component, or all implemented in an integrated manner in one physical component. The functionality of a block shown in the figures may be split among multiple components in implementation, or the functionality of multiple blocks shown in the figures may be combined into a single component in implementation. Hardware components suitable for use in embodiments of the present invention include, but are not limited to, conventional microprocessors, application-specific integrated circuits (ASICs), and field-programmable gate arrays (FPGAs). One or more blocks may be implemented as a combination of dedicated hardware to perform some functions and one or more programmed microprocessors and associated circuitry to perform other functions.

[0097] The alignment methods, alignment systems, and calibration substrates can be used or implemented in corresponding imprint methods and imprint systems. Such systems are disclosed in detail in the references cited herein. Typically, such systems have a stamp holder and a substrate holder that can be controlled and manipulated to adjust the relative lateral X-Y positions of the stamp and / or substrate. Preferably, they are also configured to adjust the relative Z positions. Such imprint systems are typically configured to implement any of the imprint methods described herein. For example, the imprint system includes hardware and software that can control the application of the stamp to the substrate as well as the release of the stamp from the substrate after curing of the imprint layer. Preferably, the imprint system is configured for use with a deformable stamp (as previously described herein) and configured as described in the references cited herein. It is contemplated that certain parts of the systems described in the documents required for such use, such as chucks, stamp holders and manipulators, pressure, stamp release mechanisms, etc., are part of such imprint systems described herein and in the following documents: WO03099463A2 METHOD AND DEVICE FOR TRANSFERRING A PATTERN FROM A STAMP TO A SUBSTRATE; WO2008068701A2 METHOD AND APPARATUS FOR APPLYING A SHEET TO A SUBSTRATE; WO2008087573A2 METHOD AND SYSTEM FOR CONTACTING OF A FLEXIBLE SHEET AND A SUBSTRATE; and WO2016045961A1 TRANSFER METHOD AND APPARATUS AND COMPUTER PROGRAM PRODUCT. For example, the presently disclosed alignment system and method can be applied to an imprint system such as that described in WO2016045961 with reference to Figures 2 to 4 thereof.

[0098] Variations to the disclosed embodiments can be understood and implemented by those skilled in the art in practicing the claimed invention, from a study of the drawings, the disclosure, and the appended claims. In the claims, the word "comprising" does not exclude other elements or steps, and the indefinite article "a" or "an" does not exclude a plurality. A single processor or other unit may fulfill the functions of several items recited in the claims. The mere fact that certain means are recited in mutually different dependent claims does not indicate that a combination of these means cannot be used to advantage. Where a computer program is described above, the computer program can be stored or distributed on a suitable medium, such as an optical storage medium or a solid-state medium supplied together with or as part of other hardware, but can also be distributed in other forms, such as via the Internet or other wired or wireless telecommunications systems. It is noted that where the term "suitable for" is used in the claims or the description, it is intended to be equivalent to the term "comprised of." Any reference signs in the claims should not be construed as limiting the scope.

[0099] The flowcharts and block diagrams in the figures illustrate the architecture, functionality, and operation of possible implementations of systems, methods, and computer program products according to various embodiments of the present invention. In this regard, each block in the flowcharts or block diagrams may represent a module, segment, or portion of instructions, comprising one or more executable instructions for implementing the specified logical function(s). In some alternative implementations, the functions noted in the blocks may occur out of the order noted in the figures. For example, two blocks shown in succession may in fact be executed substantially concurrently, or the blocks may sometimes be executed in the reverse order, depending on the functionality involved. It should also be noted that each block of the block diagrams and / or flowchart diagrams, and combinations of blocks in the block diagrams and / or flowchart diagrams, may be implemented by a special-purpose hardware-based system that performs the specified functions or operations or executes a combination of special-purpose hardware and computer instructions.

Claims

1. 1. A method for determining a detection angle, comprising: using a calibration substrate having a refractive index n and having a first pair of markers, the marker pair having a predetermined lateral displacement from each other, a first marker of the marker pair being at a first predetermined vertical position within the calibration substrate and a second marker of the marker pair being at a second predetermined vertical position within the calibration substrate that is different from the first predetermined vertical position, the calibration substrate being mounted on a first surface thereof; illuminating the marker pair with a light source; detecting light redirected from the first marker and the second marker with a detector having an optical axis that is angled at a detection angle α less than 90° and greater than 0° with respect to a normal to the substrate to determine a first detected lateral displacement between the first marker and the second marker; 1 Steps determining a first detected angle based on the refractive index n of the substrate and a first detected lateral displacement between the first marker and the second marker; A method having the following.

2. rotating the calibration substrate to rest on a second, different surface thereof; illuminating the marker pair with a light source; detecting light redirected from the first marker and the second marker to determine a second detected lateral displacement between the first marker and the second marker; a second detected angle α based on the second detected lateral displacement between the first marker and the second marker; 2 determining a 2. The method of claim 1, comprising:

3. The method of claim 2 , further comprising determining the detected angle by averaging the first detected angle and the second detected angle.

4. The method of claim 1 , wherein the first marker is a contrast marker configured to reflect a portion of the light to the light sensor.

5. 3. The method of claim 1, wherein the second marker is a contrast marker configured to reflect a portion of the light to the light sensor.

6. 6. The method of claim 1, wherein the predetermined lateral displacement between the first marker and the second marker is zero.

7. The method of claim 1 , wherein the first marker is on the first surface of the substrate and the second marker is on the second surface of the substrate.

8. The first detection angle α 1 is given by the following equation: [Equation 6] X 1 8. The method of claim 1, wherein ∇ is the measured displacement, LD is the lateral displacement, and Dw is the perpendicular distance between the first marker and the second marker.

9. The second detection angle α 2 is given by the following formula, [Equation 7] X 2 7. The method of claim 2, wherein L is the measured displacement, LD is the lateral displacement, and Dw is the perpendicular distance between the first marker and the second marker.

10. using a stamp including a stamp marker; illuminating the stamp marker using a light source; detecting light from the light source redirected by the stamp marker; determining a lateral position of the stamp marker using at least the detected first angle; 10. The method of claim 1, further comprising:

11. using a second substrate including substrate markers; illuminating the substrate marker using a light source; detecting light from the light source redirected by the substrate marker; determining a lateral position of the substrate marker using at least the detected first angle; 11. The method of claim 1, further comprising:

12. 1. An alignment system for determining alignment between a stamp and a substrate in a substrate conformal imprint lithography process, the alignment system comprising: A light source and a light sensor having an optical axis and configured to detect light from a light source redirected by the substrate, the optical axis of the light sensor being angled at a detection angle α greater than 0° with respect to a normal to the substrate; 1 and an optical sensor located at a processing system communicatively connected to the light source and the light sensor; and the alignment system is configured to receive a calibration substrate having a first marker and a second marker with a refractive index n and with a predetermined lateral displacement from each other, the first marker of the marker pair being at a first predetermined vertical position within the substrate and the second marker of the marker pair being at a second predetermined vertical position within the substrate that is different from the first predetermined vertical position; The processing system determines a first detected angle α based on a first detected lateral displacement between the first marker and the second marker on the calibration substrate when the calibration substrate is present in the alignment system. 1 and using the determined detection angle to determine alignment between the stamp and the substrate.

13. The processing system includes: illuminating the marker pair with a light source; detecting light redirected from the first marker and the second marker to determine a first detected lateral displacement between the first marker and the second marker; and further configured to control the alignment system to perform 13. The alignment system of claim 12.

14. 14. An alignment system according to claim 12 or claim 13, further comprising a calibration substrate having a refractive index n and a first pair of markers, the markers having a predetermined lateral displacement from each other, a first marker of the marker pair being at a first predetermined vertical position within the calibration substrate and a second marker of the marker pair being at a second predetermined vertical position within the calibration substrate carrying the first marker.

15. An imprint system for performing an imprint process, comprising an alignment system according to any one of claims 12 to 14.

16. 16. The imprint system of claim 15, further comprising a stamp holder for holding and manipulating the imprint stamp and a substrate holder for holding a substrate to be imprinted, wherein the lateral X-Y positions of the stamp and the substrate holder are configured to be controllable and variable, and further comprising a calibration substrate holder for holding a calibration substrate.

17. An imprint system according to claim 15 or 16, configured to carry out the method according to any one of claims 1 to 11.

18. A computer program which, when executed by an alignment system according to any one of claims 12 to 14, causes an imprint or alignment system to carry out the method according to any one of claims 1 to 11.

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