Digital lithography apparatus with autofocus position control and methods of use thereof

Abstract

To provide a digital lithography system and related methods.SOLUTION: A system includes: at least one light source configured to emit a light beam 204 onto a substrate 206 via a lens 210; at least one image sensor 214 configured to detect a reflected light beam 211 from the substrate via the lens; at least one motor configured to move the lens to focus the light beam onto the substrate; and a controller in communication with the at least one light source, the at least one image sensor and the at least one motor, wherein the controller is to actuate the at least one motor to move the lens in response to at least one signal from the at least one image sensor.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] SUMMARY OF THE DISCLOSURE Embodiments of the present disclosure relate to a digital lithography apparatus having an automatic focus position control, and a method of using such a digital lithography apparatus. [Background technology]

[0002] Photolithography is widely used in manufacturing semiconductor and display devices such as liquid crystal displays (LCDs) and organic light-emitting diode displays (OLEDs). Large-area substrates are often utilized in the manufacture of LCDs. LCDs, or flat panels, are commonly used in active matrix displays such as computers, touchscreen devices, personal digital assistants (PDAs), mobile phones, and television monitors. Generally, a flat panel may include a layer of liquid crystal material that forms pixels sandwiched between two plates. When power from a power source is applied across the liquid crystal material, the amount of light passing through the liquid crystal material can be controlled at the pixel locations, allowing an image to be generated.

[0003] Digital lithography techniques are commonly used to create electrical features that are incorporated as part of the liquid crystal material layer that forms the pixels. According to this technique, a light-sensitive photoresist is typically applied to at least one surface of a substrate. A pattern generator then exposes selected areas of the light-sensitive photoresist to light as part of a pattern, causing chemical changes in the photoresist in the selected areas and preparing them for subsequent material removal and / or material addition processes to create the electrical features.

[0004] New devices, approaches, and systems are needed to accurately and cost-effectively create patterns on substrates. Summary of the Invention

[0005] According to various embodiments, a digital lithography system is disclosed herein, comprising at least one light source configured to emit a light beam onto a substrate through a lens, at least one image sensor configured to detect reflected light beams from the substrate through the lens, at least one motor configured to move the lens to focus the light beam on the substrate, and a controller in communication with the at least one light source, the at least one image sensor, and the at least one motor, wherein the controller is configured to actuate the at least one motor to move the lens in response to at least one signal from the at least one image sensor.

[0006] In a further embodiment, a digital lithography system is disclosed herein comprising: a plurality of light sources, each configured to emit light rays onto a substrate through a lens; a plurality of image sensors, each configured to detect reflected light rays from the substrate through the lens, each light source paired with a respective image sensor; at least one motor configured to move the lens to focus the light rays on the substrate; a plurality of autofocus channels, each associated with at least one light source of the plurality of light sources and at least one image sensor of the plurality of image sensors; and a controller in communication with the plurality of light sources, the plurality of image sensors, and the at least one motor, wherein the controller operates the at least one motor to move the lens in response to one or more signals from the plurality of image sensors.

[0007] Further, an embodiment of a method for automatically focusing a light beam in a digital lithography system disclosed herein comprises directing at least one light beam from at least one light source onto a substrate through a lens; reflecting at least one light beam from the substrate through the lens to at least one image sensor; receiving by a controller at least one signal from the at least one image sensor, the at least one signal indicative of a position of the light beam on the substrate; and controlling by the controller a position of the lens to focus the light beam onto a surface of the substrate.

[0008] The present disclosure is illustrated by way of example, and not by way of limitation, in the figures of the accompanying drawings in which like reference numerals indicate similar elements. It should be noted that different references to "an" or "one" embodiment in the present disclosure are not necessarily to the same embodiment, and such references mean at least one. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is a schematic diagram of a digital lithography system in accordance with one or more embodiments of the present disclosure. [Figure 2] 1 is a schematic diagram of the change in position of a lens relative to the surface of a substrate. [Figure 3A] FIG. 10 shows a substrate height map illustrating the defocus of an optical lens during image scanning. [Figure 3B] FIG. 10 shows a substrate height map illustrating low contrast, non-uniform brightness areas (i.e., mura) within an image scan. [Figure 4] FIG. 10 illustrates how the position of the lens can be controlled to maintain the focus of the light beam on the surface of the substrate. [Figure 5A] FIG. 10 shows a substrate height map representing the substrate height measured during a scan when the position is determined using proportional-integral-derivative control in conjunction with the autofocus center of gravity of one or more channels. [Figure 5B] FIG. 10 shows a substrate height map representing the substrate height measured during a scan as the position is determined by dynamic channel selection control together with the autofocus centroid of one or more channels. [Figure 6A] FIG. 10 shows a substrate height map representing the substrate height measured during a scan when the position is determined using proportional-integral-derivative control in conjunction with the autofocus center of gravity of one or more channels. [Figure 6B] FIG. 10 illustrates a substrate height map representing the substrate height measured during a scan as the position is determined by a Kalman filter control method in conjunction with the autofocus centroid of one or more channels. [Figure 7A] FIG. 10 shows a substrate height map representing the substrate height measured during a scan when the position is determined using proportional-integral-derivative control in conjunction with the autofocus center of gravity of one or more channels. [Figure 7B] FIG. 10 shows a substrate height map representing the substrate height measured during a scan when the position is determined by a reference position together with feedback control of a real-time autofocus signal. [Figure 8] FIG. 1 is an illustration of an example computing device that implements the systems and methods described herein. DETAILED DESCRIPTION OF THE INVENTION

[0010] Embodiments of the present disclosure relate to controlling the position of a lens in a digital lithography tool in a robust and precise manner to provide precise focus with little or no unevenness. Digital lithography systems and methods use a light source to print device structures on a substrate (e.g., a glass substrate). The digital lithography systems and methods described herein are used, among other things, to manufacture displays. For example, a customer may order 5,000 phones and provide a semiconductor manufacturer with patterns for these 5,000 components. The manufacturer may create hundreds of these patterns per substrate. The same manufacturing process may be repeated, for example, 100 or 200 times. Semiconductor manufacturers typically scan a first substrate as an initial reference scan. However, each substrate (e.g., glass) may be slightly different, and the position may be slightly distorted in one direction or another with some misalignment between machines. By tracking the height change of the substrate, a controller can move the lens to properly focus the light source during the scan.

[0011] Autofocus systems according to embodiments herein utilize one or more light beams that pass through precision lenses and then project onto a substrate. The light source is then reflected back and measured using an image sensor to determine its position. In some embodiments, the substrate effectively forms a mirror with a line projected onto a transparent surface with a reflective material (e.g., chrome) underneath. This reflectivity can make it difficult to determine the location of the substrate's surface. In some embodiments, when a layer of material is printed on another, different types of reflectivity are created on those layers. The light beam can become out of focus due to these varying reflectivities. For example, the lens may drift to one side or another from the target position. In some embodiments, the substrate includes multiple layers, each of which is transparent. The substrate may be formed from, for example, 5, 6, 7, 8, or 9 transparent layers. When the light beam is directed at the substrate, the signal becomes very noisy, making it difficult for the system to determine the surface height.

[0012] In some cases, the substrate may heat and / or cool, changing its height, which may, for example, cause the light source to bend over the edge. The systems and methods described herein are configured to focus the light source during such conditions. When the system is not scanning the substrate, the height of the lens relative to the substrate may change. For example, when a new substrate is placed on the stage, each individual substrate will be slightly different in height from other substrates because substrate materials have varying thicknesses (e.g., on the order of microns). Sensors within the system are configured to determine this height change. Such information can be used as feedback to control the focus of the light source. In the case of systems and methods that perform printing operations using a light source, maintaining the focus of the light source is beneficial. The autofocus subsystem described by the embodiments herein functions with improved software control of the autofocus subsystem.

[0013] To obtain accurate focus in real time, various parameters are considered, including substrate conditions (e.g., topography, reflectivity, pattern structure, etc.), chuck flatness, stage movement, measurement noise, and thermal effects. Methods and systems according to embodiments herein collect such parameter data in real time and utilize the real-time data to control the position of the light source. In some embodiments, historical parameter data (e.g., from previous scanning and lithography steps) may also be used to control the position of the light source.

[0014] The systems and methods described herein improve the focus accuracy of an optical lens in real time by precisely controlling its position using a controller and motor unit. Systems and methods according to embodiments herein utilize a real-time autofocus signal and an empirical reference position to determine actual movement during printing. Such systems and methods also utilize some or all of the autofocus signal to drive one or more motors for different use cases. Systems and methods according to various embodiments can minimize mura and produce improved print fidelity, optionally ignoring underlying layers on the substrate, underlying pattern orientation / density, and / or scan speed.

[0015] In the systems and methods described herein, it is beneficial to focus the light source "on the fly" to maintain focus, especially during high scanning speeds. To maintain precise focus, various parameters are considered, including substrate conditions (e.g., topography, reflectivity, and pattern structure), chuck flatness, stage motion, measurement noise, and thermal effects during scanning.

[0016] The embodiments described herein utilize positioning control during fast scanning. Position can be determined by the following approaches: 1) using the autofocus signal centroid with proportional-integral-derivative (PID) control, i.e., using a PID control loop of all channels and the autofocus signal centroid as feedback to determine motion; 2) using the autofocus signal centroid with a Kalman filter, i.e., using a Kalman filter of all channels and the autofocus signal centroid as feedback to determine motion; 3) using the autofocus signal centroid with dynamic channel selection (similar to 1), dynamically using some but not all channels to determine motion; and / or 4) using an empirical reference position with feedback of the real-time autofocus signal, which differs from approach 3) in that position is not always determined by the real-time autofocus signal. Rather, approach 4) uses both a predetermined reference position and a real-time autofocus signal, where the reference position can be obtained from a plain substrate (i.e., no underlayer pattern), from printing the first layer, or from post-processed positions generated from other methods. Different approaches can be used depending on whether there is an underlayer / underlayer pattern and / or the orientation / density of the underlayer pattern.

[0017] FIG. 1 shows a schematic diagram of a digital lithography system 100 in accordance with one or more embodiments of the present disclosure. In the system 100, a light source 102 is configured to project a light beam 104 onto a substrate 106 via a reflector 108 and a lens 110. The substrate may be formed of a suitable material, including, but not limited to, glass, a reflective material, a metal, chrome, a polymer, a crystal, or an oxide. The lens may be an optical lens, a spherical lens, or an aspherical lens. The light source 102 may be mounted to the system 100 via a mounting substrate 112 configured to stabilize the light source 102 during operation. Suitable light sources include, but are not limited to, lasers, continuous wave (CW) lasers, quality (Q) switched lasers, mode-locked lasers, etc. The reflector 108 may be formed of any suitable material, including, but not limited to, a mirror, glass, metal, etc. The lens 110 may be an optical lens formed of any suitable material, including, but not limited to, glass, silica, a crystalline material, a nanocrystalline material, etc.

[0018] System 100 may further include at least one image sensor 114, which may be mounted on a stripboard 115. In some embodiments, multiple image sensors 114 may be mounted in a row on the stripboard. Image sensor 114 may be a linear image sensor, a complementary metal oxide semiconductor (CMOS) or active pixel image sensor, a charge-coupled device (CCD) image sensor, or a solid-state device that converts an optical image into an analog signal in a line-by-line manner. 1, the light beam 104 reflects from the substrate 106 at the light source spot 116 and directs the reflected light beam 118 to a reflector 120. The reflected light beam 118 reflects from the reflector 120 to a reflector 122, where it is directed to the image sensor 114 as an autofocus signal.

[0019] 1, system 100 has a single autofocus channel 124, but it should be understood that in some embodiments, system 100 may include multiple autofocus channels. For example, system 100 may include multiple autofocus channels, with each channel associated with a light source and a linear image sensor pair. In some embodiments, the systems described herein include at least three autofocus channels.

[0020] The system 100 may further include a unit consisting of a controller 126 and one or more motors 128. Suitable controllers 126 include, but are not limited to, a proportional controller, an integral controller, a proportional-integral controller, a proportional-derivative controller, or a proportional-integral-derivative (PID) controller.

[0021] Suitable motors include, but are not limited to, linear motors, such as piezoelectric motors, ultrasonic motors, ultrasonic resonant motors, piezoelectric stepper motors, piezoelectric walk motors, piezoelectric stick-slip motors, flexure-type motors, and inertial motors. The controller 126 is configured to operate the one or more linear motors 128. According to an embodiment, the one or more linear motors 128 move the lens 110 relative to the substrate 106 to improve and / or optimize the focus of the light source 104 on the substrate 106. The data processing unit 130 sends signals to and receives signals from the at least one image sensor 114, the light source 102, and the controller 126.

[0022] 2 shows a schematic diagram of the changing position of lens 210 relative to surface 207 of substrate 206. As the substrate undergoes processing, layers of circuitry and device features build up, making it difficult for lens 210 to focus the light beam onto the surface of the substrate. The systems and methods described herein are configured to detect the position of the surface of the substrate and optimize the focus of the light beam onto the surface of the substrate.

[0023] 2, when light beam 204 passes through lens 210 onto substrate 206 at spot 215, light beam 204 reflects off of substrate 206 and returns to lens 210 at 211. During a subsequent scan of substrate 206 with a light source (not shown), the height of the substrate's surface may change, e.g., from 207 to 209, as represented by ΔZ, and the distance between the substrate's surface and lens 210 may decrease.

[0024] As shown in FIG. 2, when the height of the surface of substrate 206 shifts toward lens 210, as represented by 209, light ray 213 reflects from surface 209 at spot 217 and returns to lens 210 at 216. According to an embodiment, the change in substrate height (ΔZ) can be captured and measured by a change in the autofocus signal centroid. After reflecting at spot 215, light ray 204 generates beam spot 218 on linear image sensor 214. The centroid of beam spot 218 is calculated and represents the relative distance between 207 and 210. Similarly, light ray 213 generates beam spot 219 (which needs to be added) on linear image sensor 214. In this way, a shift (ΔL) on linear image sensor 214 can capture the change in substrate height (ΔZ).

[0025] The movement of lens 210 may be determined by one or more autofocus channels as described above, for example, a shift (ΔL) on linear image sensor 214 due to a change in substrate height (ΔZ). A shift ΔL of 211-216 (and spots 215-217) due to a change in height ΔZ of the substrate surface (i.e., 207-209) can cause the light source to become defocused and / or create unevenness.

[0026] Systems and methods according to embodiments herein are used to refocus the light source, taking into account height changes ΔZ of the substrate's surface. In some embodiments, there is a correspondence between the incidence of the light source on the substrate's surface (e.g., spots 215, 217) and the movement of the reflected light beam along the linear sensor 214. For example, a linear shift measurement indicates a change in the height of the substrate's surface relative to the lens. In this manner, the system 100 can be calibrated using the autofocus channel to maintain a target focus (e.g., pixel count) during processing. A plain (uncoated) substrate can be scanned and used for calibration. Height variations are based on variations in the thickness of the substrate material (e.g., glass). The substrate can be pre-scanned during printing, and then the print is scanned in real time as pixels are actually printed on the substrate. If the actual pixel count changes when scanning the substrate, the controller determines that the light beam is a certain number of pixels away from the target. Using a feedback loop, the controller 126 commands the linear motor 128 to move the lens 110 to return the focus of the light beam 104 to the target position.

[0027] Figure 3A shows a substrate height map illustrating the defocus of an optical lens during image scanning. A control device and motor unit were used to automatically focus the light source in a digital lithography system. This substrate height map illustrates the problems that can occur when focus is not controlled during processing. During this scan, 70 scans along the y-axis and 12,800 frames along the x-axis were performed. The substrate height map shows the topology of the substrate as it passes through the lens. The scanned substrate contained devices, circuit features, and multiple layers of film. The lens focused the light beam onto underlying features rather than onto the surface of the substrate, resulting in the horizontal and vertical lines shown. If the linear motor were unable to move the lens to track the surface of the substrate, the resulting error would be greater than the depth of focus, and the printed pattern would be out of focus.

[0028] In one or more embodiments, the substrate may contain chrome or other metallic and non-metallic materials, i.e., the substrate may be made of a combination of materials. Similarly, one region of the substrate may have a different material combination than other regions of the substrate. As a light source scans a substrate with such irregular materials, the lens may be moved to the wrong position, resulting in the line shown in FIG. 3A, causing the light source to become unfocused. Systems and methods according to one or more embodiments herein are configured to eliminate variations resulting from this defocusing. In other words, the light beam reflecting off the substrate may reflect off an underlying device or layer within the substrate rather than off the surface of the substrate. In this way, the lens attempts to focus the light beam on an underlying feature rather than on the surface currently being printed. This causes the motor to move the lens to an unwanted position, causing the light beam to become unfocused, resulting in the pattern shown in FIG. 3A. Systems and methods according to one or more embodiments herein correct these erroneous signals rather than promoting them. The systems and methods described herein are configured to maintain precise positioning control during high-speed scanning. Controlling the lens movement can minimize mura and improve printing fidelity.

[0029] FIG. 3B shows a substrate height map illustrating low-contrast, non-uniform brightness regions (i.e., mura) within the image scan. In some cases, mura can result from improper lens movement. As shown in the substrate height map of FIG. 3B, mura exists near the following (x, y) coordinates: (10 mm, -80 mm).

[0030] According to one or more embodiments, a method 400 is described herein for, among other things, controlling the position of a lens using a controller and a linear motor in conjunction with an image sensor. In one or more embodiments, the controller is calibrated to the position of a light beam along the image sensor and to the height of the surface of the substrate. The control method 400 shown in FIG. 4 utilizes an autofocus signal centroid in conjunction with proportional-integral-derivative (PID) control to direct the position of the lens. In block 402, a light source projects a light beam through a lens onto the substrate.

[0031] In block 404, the light beam reflects off the substrate and returns through a lens. The reflected light beam is illuminated onto an image sensor (e.g., a linear image sensor) configured to receive and detect the light beam at multiple positions along the length of the image sensor. As shown in FIG. 2, the reflected light beam can be used to determine a shift ΔL between the expected position 211 and the actual position 216 of the light beam.

[0032] In block 406, the controller receives a signal from the image sensor indicating the position of the reflected light beam that has reflected back through the lens onto the image sensor. The controller determines the difference between the actual position of the light beam and the target position of the light beam. As shown in Figure 2, a shift along the length of the reflected light beam (ΔL) corresponds to a change in height (ΔZ) of the surface of the substrate.

[0033] In block 408, the controller determines the current height of the surface of the substrate. The controller then utilizes a control method, e.g., a PID control loop, along with the autofocus signal centroid of one or more channels as feedback to determine lens movement for proper focusing for the determined height of the substrate. For example, if the lens focuses a light beam on an underlying structure below the surface of the substrate, the controller moves the lens to focus the light beam on the surface of the substrate (i.e., focus at a height above the underlying structure). In some embodiments, the controller uses dynamic channel selection as feedback along with the autofocus signal centroid of one or more channels. For example, the controller dynamically uses some, but not all, channels to control lens movement. In other embodiments, the controller uses all channels to control lens movement. In one or more embodiments, autofocus signals are collected from an image sensor, and the centroid of these signals is then determined and used to confirm position.

[0034] In some embodiments, as an alternative to the PID control loop described above, method 400 combines a Kalman filter (i.e., linear quadratic estimation) with one or more channel autofocus signal centroids as feedback. In this embodiment, the controller utilizes historical data from one or more channel autofocus signal centroids combined with the current one or more channel measurements. In this embodiment, the Kalman filter also predicts how the surface height will change, and the controller activates a linear motor to move the lens and focus the light beam onto the surface of the substrate. In some embodiments, the Kalman filter is based on the following equation: The Kalman filter model assumes that the true state at time k evolves from the state at (k-1) according to the following equation: x k =F k x k-1 +B k u k +w k During the ceremony, F k is the previous state xk-1 This is a state transition model that applies to ·B k is the control vector u k is a control input model applied to ·w k is the process noise, which is the covariance (Q k ) are assumed to be drawn from a zero-mean multivariate normal distribution (N) with k ~N(0,Q k )). At time k, the true state x k Observation (or measurement) of z k is carried out according to the following formula: z k =H k x k +v k During the ceremony, H k is the observation model, which maps the true state space to the observation space. ·v k is the observation noise, which is the covariance (R k ) is assumed to be zero-mean Gaussian white noise with k ~N(0,R k )). The initial state and the noise vectors {x0, w1, ..., w k , v1, ..., v k} are all assumed to be mutually independent.

[0035] In some embodiments, as an alternative to the PID control loop described above, method 400 combines an empirical reference position for the substrate (e.g., a reference map of the substrate) with the real-time autofocus signal centroid of one or more channels as feedback. In some embodiments, each substrate has a reference map tracked with an identification code. In this embodiment, the position of the lens is not necessarily determined by the real-time autofocus signal from one or more channels. The controller utilizes both the real-time autofocus signal and a predefined reference position of the lens controlled by the controller. The reference position can be obtained from a plain substrate (i.e., no underlayer pattern or feature), the printing of the first layer, a post-processed position generated from another method, etc. In some embodiments, any of the above control approaches can be used depending on whether there is an underlayer or underlayer pattern, and the orientation or density of the underlayer pattern. For example, light passing through a lens may be defocused due to varying reflectivities of the substrate's surface. The systems and methods described herein are configured to measure the actual height of the substrate's surface. To do this, prior information about the height and / or filtering of the substrate surface is used to move the lens to maintain the focus of the light beam on the substrate's surface.

[0036] FIG. 5A shows a substrate height map representing the substrate height measured during a scan when the position is determined using proportional-integral-derivative control with one or more channels of autofocus centroid. During this scan, 35 scans along the y-axis were performed with 12,800 frames along the x-axis. The controller collected the autofocus signals and determined the centroid of these signals. This centroid was used by the PID controller to generate the lens position. In some embodiments, this method of scanning a substrate can be used on a "blank substrate" (e.g., a clean, uncoated surface).

[0037] Figure 5B shows a substrate height map representing the substrate height measured during a scan when the position is determined by dynamic channel selection control in conjunction with the autofocus center of gravity of one or more channels. This control method is used to dynamically select a specific autofocus channel, and some, but not all, channels can be used as feedback to the PID controller to determine movement. Three autofocus channels (i.e., three image sensor and light source pairs) were used during this scan, and data for each scan was stored in memory and accessible by the controller. Data from the channel with the best signal was used in the control loop. In some embodiments, the controller can dynamically select the number of channels. During a scan, the light beam may land at a specific pixel location. Some locations may be over complex device features, reflective materials, and / or multi-layer structures. Scans at such locations may have relatively more noise (i.e., the lens has difficulty focusing at that pixel location). The system can dynamically increase the number of channels at that location to improve the feedback signal. Controlling the lens position using this method eliminates and / or reduces lines such as those shown in Figure 3A.

[0038] Figure 6A shows a substrate height map representing the substrate height measured during a scan when the position is determined using PID control in conjunction with the autofocus center of gravity. To generate this substrate height map, 57 scans along the y-axis and 6,545 frames along the x-axis were performed. Controlling the lens position using this method eliminates and / or reduces lines such as those shown in Figure 3A.

[0039] Figure 6B shows a substrate height map representing the substrate height measured during a scan when the position is determined by the autofocus center of gravity with Kalman filter control. This method is similar to lowering the treble control on a stereo so that only lower frequency signals pass. In this embodiment, this method is used to control the position of the lens to eliminate and / or reduce lines such as those shown in Figure 3A.

[0040] Figure 7A shows a substrate height map representing the substrate height measured during a scan when the position is determined by the center of gravity of the autofocus with proportional-integral-derivative control. During this scan, 6,400 frames were performed along the x-axis and 55 scans along the y-axis. The resulting substrate height map shows several line patterns.

[0041] FIG. 7B shows a substrate height map representing the substrate height measured during a scan when the position is determined by a reference position with feedback control of the real-time autofocus signal. An empirical reference position was used during these scans. For example, the systems and methods described herein can store each data scan in memory. Each previous layer or layers can be used by the control system as a reference. This reference data (or historical data) can be used and combined with the real-time image sensor signal as a feedback signal in the control loop. In some embodiments, the real-time signal can contain noise as a result of multiple layers in the substrate. In this manner, the real-time signal can be ignored due to excessive noise.

[0042] For example, the real-time signal may be utilized once the signal is determined to be reliable. In some embodiments, using the real-time signal for feedback, the controller knows the actual height of the substrate at a particular region (or pixel) of the substrate. This actual height can be compared to the first layer, as a reference map is stored in the system's memory, and the height difference can be determined. The controller will apply this difference at the corresponding pixel region. According to one or more embodiments described herein, utilizing this method by the controller to actuate the linear motor and control the position of the lens substantially reduces or eliminates the noise or line pattern shown in FIG. 7B compared to the scan presented in FIG. 3A.

[0043] 8 illustrates a diagrammatic representation of a machine in the exemplary form of a computer system 800 including a set of instructions executable by the system as described herein to perform any one or more of the methods discussed herein. In one implementation, the system may include instructions to enable execution of the processes and corresponding components shown and described in connection with FIGS. 1, 2, and 4.

[0044] In alternative implementations, the system may include a machine connected (e.g., networked) to other machines in a LAN, an intranet, an extranet, or the Internet. The machine may operate as a server machine in a client-server network environment. The machine may be a personal computer (PC), a neural network computer, a set-top box (STB), a personal digital assistant (PDA), a mobile phone, a server, a network router, switch, or bridge, or any machine capable of executing a set of instructions (sequential or otherwise) that specify actions to be taken by the machine. Furthermore, while only a single machine is illustrated, the term "machine" should be interpreted to include any collection of machines individually or collectively executing a set of instructions (or sets) to perform any one or more of the methods described herein.

[0045] The exemplary computer system 800 may include a processing device (processor) 802, a main memory 804 (e.g., Read-Only Memory (ROM)), flash memory, dynamic random access memory (DRAM) such as synchronous DRAM (SDRAM), static memory 806 (e.g., flash memory, static random access memory (SRAM)), and a data object storage device 818, which communicate with each other via a bus 830.

[0046] The processing device 802 represents one or more general-purpose processing devices, such as a microprocessor, a central processing unit, or the like. More specifically, the processing device 802 may be a Complex Instruction Set Computing (CISC) microprocessor, a Reduced Instruction Set Computing (RISC) microprocessor, a Very Long Instruction Word (VLIW) microprocessor, or a processor implementing other instruction sets or a combination of instruction sets. The processing device 802 may also be one or more special-purpose processing devices, such as an Application Specific Integrated Circuit (ASIC), a Field Programmable Gate Array (FPGA), a Digital Signal Processor (DSP), a network processor, or the like. In various implementations of the present disclosure, the processing device 802 is configured to execute instructions for the devices or systems described herein to perform the operations and processes described herein.

[0047] Computer system 800 may further include a network interface device 808. Computer system 800 may also include a video display unit 810 (e.g., a liquid crystal display (LCD) or a cathode ray tube (CRT)), an alphanumeric input device 812 (e.g., a keyboard), a cursor control device 814 (e.g., a mouse), and a signal generation device 816 (e.g., a speaker).

[0048] The data storage device 818 may include a computer-readable medium 828 on which are stored one or more sets of instructions for the devices and systems as described herein that implement any one or more of the methodologies or functions described herein. The instructions may also reside, completely or at least partially, within the main memory 804 and / or within the processing logic 826 of the processing device 802 during their execution, with the computer system 800, the main memory 804, and the processing device 802 also constituting computer-readable media.

[0049] Instructions may further be transmitted or received over network 820 via network interface device 808. While computer-readable storage medium 828 is shown to be a single medium in the exemplary implementation, the term "computer-readable storage medium" should be interpreted to include a single medium or multiple media (e.g., centralized or distributed databases, and / or associated caches and servers) that store one or more sets of instructions. The term "computer-readable storage medium" should also be interpreted to include any medium that is capable of storing, encoding, or transmitting a set of instructions for execution by a machine, causing the machine to perform any one or more of the methodologies of the present disclosure. Accordingly, the term "computer-readable storage medium" should be interpreted to include, but is not limited to, solid-state memory, optical media, and magnetic media.

[0050] The foregoing description sets forth numerous specific details, such as examples of particular systems, components, methods, etc., to provide a thorough understanding of some embodiments of the present disclosure. However, it will be apparent to those skilled in the art that at least some embodiments of the present disclosure may be practiced without these specific details. In other instances, well-known components or methods have not been described in detail or have been presented in simple block diagram form to avoid unnecessarily obscuring the present disclosure. Thus, the specific details described are merely exemplary. Particular implementations may differ from these example details and still be intended to be within the scope of the present disclosure.

[0051] As used herein, the singular forms "a," "an," and "the" include plural references unless the context clearly dictates otherwise. Thus, for example, reference to a "precursor" includes a single precursor as well as mixtures of two or more precursors, reference to a "reactant" includes a single reactant as well as mixtures of two or more reactants, etc.

[0052] References throughout this specification to "one embodiment" or "an embodiment" mean that a particular feature, structure, or characteristic described in connection with an embodiment is included in at least one embodiment. Thus, appearances of the phrase "in one embodiment" or "in an embodiment" in various places throughout this specification do not necessarily all refer to the same embodiment. Additionally, the term "or" is intended to mean an inclusive "or" rather than an exclusive "or." When the term "about" or "approximately" is used herein, it is intended to mean that the nominal value presented is accurate to within ±10%, such that "about 10" would include 9 to 11.

[0053] The term "at least about" in reference to a measured quantity refers to normal variations in the measured quantity as would be expected by one of ordinary skill in the art in making the measurement and exercising a level of care commensurate with the subject of measurement and the precision of the measurement device, as well as any quantity greater than that. In certain embodiments, the term "at least about" includes the recited number minus 10% and any larger amount such that "at least about 10" would include 9 and greater. The term can also be expressed as "about 10 or greater." Similarly, the term "less than about" typically includes the recited number plus 10% and any smaller amount such that "less than about 10" would include 11 and less than 11. The term can also be expressed as "about 10 or less."

[0054] The description of numerical ranges herein, unless otherwise indicated herein, is merely intended to serve as a shorthand method for individually referring to each separate value falling within the range, and each separate value is incorporated into the specification as if it were individually recited herein. All methods described herein can be performed in any suitable order unless otherwise indicated herein or clearly contradicted by context. Any and all examples provided herein, or the use of exemplary language (e.g., "etc."), are intended merely to highlight particular materials and methods and are not limiting in scope. No language in the specification should be construed as indicating any non-claimed element as essential to the practice of the disclosed materials and methods.

[0055] Although the operations of the methods herein are shown and described in a particular order, the order of the operations of each method may be changed such that certain operations may be performed in the reverse order or such that certain operations may be performed, at least in part, concurrently with other operations. In alternative embodiments, the instructions of separate operations or sub-operations may be intermittent and / or alternating.

[0056] It is to be understood that the foregoing specification is intended to be illustrative, and not restrictive. Many other embodiments will become apparent to those skilled in the art upon reading and understanding the foregoing specification. The scope of the present disclosure should, therefore, be determined with reference to the appended claims, along with the full scope of equivalents to which such claims are entitled.

Claims

1. at least one light source configured to emit a light beam through a lens onto the substrate; at least one image sensor configured to detect light reflected from the substrate through the lens; at least one motor configured to move the lens to focus the light beam onto the substrate; a controller in communication with the at least one light source, the at least one image sensor, and the at least one motor; The digital lithography system, wherein the controller is configured to actuate the at least one motor to move the lens in response to at least one signal from the at least one image sensor.

2. The system of claim 1 , wherein the at least one light source comprises at least one of a laser, a continuous wave (CW) laser, a quality (Q) switched laser, or a mode-locked laser.

3. The system of claim 1 , wherein the substrate comprises at least one of the following materials: glass, a reflective material, a metal, chromium, a polymer, a crystal, or an oxide.

4. The system of claim 1 , wherein the lens comprises at least one of an optical lens, a spherical lens, or an aspherical lens.

5. 10. The system of claim 1, wherein the at least one image sensor comprises at least one of a linear image sensor, a complementary metal-oxide semiconductor (CMOS) or active pixel image sensor, a charge-coupled device (CCD) image sensor, or a solid-state device.

6. 10. The system of claim 1, wherein the at least one motor comprises a linear motor comprising at least one of a piezoelectric motor, an ultrasonic motor, an ultrasonic resonant motor, a piezo stepper motor, a piezo walk motor, a piezo stick slip motor, a flexure type motor, or an inertia motor.

7. The system of claim 1 , further comprising one or more autofocus channels associated with the at least one light source and the at least one image sensor.

8. 2. The system of claim 1, wherein the controller is configured to operate the at least one motor using a proportional-integral-derivative control method using an autofocus signal centroid from the one or more autofocus channels as a feedback signal.

9. 10. The system of claim 1, wherein the controller is configured to operate the at least one motor using a Kalman filter control method that uses an autofocus signal centroid from the one or more autofocus channels as a feedback signal.

10. 10. The system of claim 1, wherein the controller is configured to operate the at least one motor using a proportional-integral-derivative control method with dynamic channel selection using an autofocus signal centroid from the one or more autofocus channels as a feedback signal.

11. 2. The system of claim 1, wherein the controller is configured to operate the at least one motor using an empirical reference position control method that uses a real-time autofocus signal centroid from the one or more autofocus channels as a feedback signal.

12. a plurality of light sources, each configured to emit a light beam through a lens onto the substrate; a plurality of image sensors, each configured to detect light reflected from the substrate through the lens, each light source paired with a respective image sensor; at least one motor configured to move the lens to focus the light beam onto the substrate; a plurality of autofocus channels, each associated with at least one light source of the plurality of light sources and at least one image sensor of the plurality of image sensors; a controller in communication with the plurality of light sources, the plurality of image sensors, and the at least one motor; The digital lithography system, wherein the controller operates the at least one motor to move the lens in response to one or more signals from the plurality of image sensors.

13. the controller operates the at least one motor using a proportional-integral-derivative control method using the autofocus signal centroid from the one or more autofocus channels as a feedback signal; or the controller operates the at least one motor using a Kalman filter control method using an autofocus signal centroid from the one or more autofocus channels as a feedback signal; or the controller operates the at least one motor using a proportional-integral-derivative control method with dynamic channel selection using an autofocus signal centroid from the one or more autofocus channels as a feedback signal; or 13. The system of claim 12, wherein the controller operates the at least one motor using an empirical reference position control method that uses a real-time autofocus signal centroid from the one or more autofocus channels as a feedback signal.

14. 1. A method for automatically focusing a light beam in a digital lithography system, comprising: directing at least one light beam from at least one light source through a lens onto a substrate; reflecting the at least one light ray from the substrate through the lens onto at least one image sensor; receiving by a controller at least one signal from the at least one image sensor, the at least one signal indicative of a position of the light beam on the substrate; and controlling, with the control device, a position of the lens to focus the light beam onto the surface of the substrate.

15. 15. The method of claim 14, further comprising calibrating the at least one image sensor to correlate changes in the length (ΔL) of the reflected light beam along the length of the at least one image sensor with changes in height (ΔZ) of the surface of the substrate.

16. The method of claim 14 , wherein controlling the position of the lens comprises operating at least one motor to move the lens.

17. controlling the position of the lens operating the at least one motor with the controller using a proportional-integral-derivative control method using an autofocus signal centroid from the one or more autofocus channels as a feedback signal; operating the at least one motor using a Kalman filter control method using an autofocus signal centroid from the one or more autofocus channels as a feedback signal; operating the at least one motor using a proportional-integral-derivative control method with dynamic channel selection using an autofocus signal centroid from the one or more autofocus channels as a feedback signal; and operating the at least one motor using an empirical reference position control method that uses a real-time autofocus signal centroid from the one or more autofocus channels as a feedback signal.

18. 17. The method of claim 16, wherein the at least one motor is a linear motor selected from the group consisting of a piezoelectric motor, an ultrasonic motor, an ultrasonic resonant motor, a piezo stepper motor, a piezo walk motor, a piezo stick slip motor, a flexure type motor, and an inertia motor.

19. 15. The method of claim 14, wherein the substrate comprises at least one material selected from the group consisting of glass, a reflective material, a metal, chromium, a polymer, a crystal, or an oxide.

20. 15. The method of claim 14, wherein the at least one image sensor is selected from the group consisting of a linear image sensor, a complementary metal-oxide semiconductor (CMOS) or active pixel image sensor, a charge-coupled device (CCD) image sensor, and a solid-state device.

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