Fuzzy reduction techniques for semiconductor inspection

Abstract

Techniques for reducing blur in images taken during semiconductor inspection are disclosed herein. A stage holding a substrate for inspection may be moved at a substantially constant speed during inspection to increase throughput. In some techniques, a mirror system may be added to a camera system to reduce blur in an image. The mirror system may include a rotating mirror or a dithering mirror to convert linear motion of the stage into counter-rotating motion in the form of a deflected beam angle to reduce motion blur caused by movement of the stage.

Description

Cross-reference to related applications

[0001] This PCT application claims the benefit of U.S. Patent Application Serial No. 18 / 475,684, filed September 27, 2023, entitled “Blur Reduction Techniques For Semiconductor Inspection,” the entire contents of which are incorporated herein by reference. Technical Field

[0002] This disclosure relates generally to imaging systems, and in particular to optical systems for reducing blur when capturing images of moving objects. Background Technology

[0003] Sometimes, it's desirable to capture images of moving objects. This happens during manufacturing. The faster you move something while manufacturing an object, the greater the throughput. In semiconductor manufacturing, the ability to process substrates that house integrated circuits or other components more quickly allows for higher productivity. The ability to process more substrates per unit time is valuable. Some equipment in semiconductor or similar manufacturing facilities needs to capture images of substrates for measurement, characterization, or inspection.

[0004] A problem that arises when attempting to capture images of moving objects at a specific speed is motion blur. Motion blur makes images less sharp and makes it harder to capture small features within them. Some techniques for addressing motion blur limit processing power. For example, some techniques use a strobe lamp to selectively illuminate a substrate that moves during exposure by a camera system. However, the pulse rate of the strobe lamp is limited by the physical specifications of the bulb and the time required for the bulb to cool between pulses. Summary of the Invention

[0005] This document discloses techniques for reducing motion blur (“blur”) in captured images of moving objects. In semiconductor inspection systems, a substrate is typically inspected by moving it below a camera. At some point, the substrate moves so quickly that the image capture system produces blur. In some techniques, the camera can also be configured to move such that the mismatch between the camera’s speed and the stage is reduced during image capture, thereby reducing motion blur. The camera can be accelerated and decelerated to position it above different portions of the substrate to capture images of different portions of the substrate. This can be performed in predefined patterns.

[0006] In some techniques, a mirror system can be added to a camera system to reduce blur in the image. The mirror system may include a rotating mirror or a dithering mirror. The mirror system can convert the linear motion of the stage into a reverse rotational motion, which allows the imaging system to capture an image of the substrate with reduced blur. This is because the motion of the mirror system reduces the relative motion between the moving object being imaged and the imaging system.

[0007] This disclosure describes an image capture system for reducing motion blur during semiconductor inspection. The image capture system includes: a stage for holding a substrate to be inspected, wherein the stage is configured to move at a substantially constant speed during inspection; a microscope objective positioned opposite the stage; a mirror system for receiving a light beam representing the substrate from the microscope objective and reflecting the light beam to a microscope lens, the mirror system including a mirror configured to move according to a preset angular velocity curve based on the speed of the stage, wherein the mirror system moves at a specified angular velocity for a defined time interval; and an image sensor for generating an image of a portion of the substrate based on the light beam received from the microscope lens during the defined time interval.

[0008] This disclosure also describes a method for inspecting a substrate. The method includes: loading a substrate onto a stage of an inspection system; moving the stage at a substantially constant speed; positioning the stage opposite a microscope objective; moving a mirror to reflect a light beam representing the substrate from the microscope objective to a microscope lens, the mirror moving according to a preset angular velocity curve based on the speed of the stage, wherein the mirror moves at a specified angular velocity for a defined time interval; and generating an image of a portion of the substrate based on the light beam received from the microscope lens during the defined time interval.

[0009] This disclosure further describes a system including a microscope objective positioned opposite a stage holding a substrate for examination, wherein the stage is configured to move at a substantially constant speed during examination. The system includes a tube lens and a mirror system positioned between the microscope objective and the tube lens for receiving a light beam representing the substrate from the microscope objective and reflecting the light beam back to the tube lens. The mirror system includes a first mirror for moving according to a preset angular velocity profile based on the speed of the stage, wherein the first mirror moves at a specified angular velocity for a defined time interval; and a second mirror positioned in a fixed orientation opposite to the first mirror. The system also includes a camera for generating an image of a portion of the substrate based on the light beam received from the tube lens during the defined time interval. Attached Figure Description

[0010] The accompanying drawings illustrate only exemplary embodiments of this disclosure and should not be construed as limiting its scope.

[0011] Figure 1 An example section of an inspection system that performs stop-and-go inspections is shown.

[0012] Figure 2 An example section of an inspection system is shown, illustrating the use of a mobile camera system to perform inspections.

[0013] Figure 3 This is a flowchart of method 300 for semiconductor inspection, which uses a moving camera to reduce blur.

[0014] Figures 4A to 4C The beam deflection in an image capture system with stage movement is shown.

[0015] Figure 5 An example section of an image capture system with an optical system for reducing motion blur is illustrated.

[0016] Figure 6 An example of the angular velocity curve of a rotating mirror is shown.

[0017] Figure 7 An example of the angular velocity curve of a jittery mirror is shown.

[0018] Figure 8 An example of the motion curve of a jittery mirror is shown.

[0019] Figure 9A An example of a mirror system is shown.

[0020] Figure 9B An example section of the reflector system is shown.

[0021] Figure 10 A block diagram illustrating an example of a machine that includes one or more of the techniques (e.g., methods) discussed herein that can be executed thereon. Detailed Implementation

[0022] Techniques for reducing motion blur (“blur”) in captured images of moving objects are disclosed. In semiconductor inspection systems, a substrate (e.g., a semiconductor product) is typically inspected by moving it below a camera. In other manufacturing apparatuses, other moving systems, such as conveyors, moving systems, or robotic systems, may be used. At some point, the object or substrate moves so fast that the image capture system produces blur. In some techniques, the camera may also be configured to move such that the mismatch between the camera’s speed and the stage is reduced during image capture, thereby reducing motion blur. The camera can be accelerated and decelerated to position it above different portions of the substrate to capture images of different portions of the substrate. This can be performed in a predefined pattern.

[0023] In some techniques, a mirror system can be added to a camera system to reduce blur in the image. The mirror system may include a rotating mirror or a dithering mirror. The mirror system can convert the linear motion of the moving system or stage into a reverse rotational motion, which allows the imaging system to capture an image of the object or substrate with reduced blur. This is because the motion of the mirror system reduces the relative motion between the moving object being imaged and the image capture system.

[0024] Figure 1 An example portion of an image capture system performing stop-and-go image capture is illustrated. The image capture system may be within an inspection system 100, which may include a stage 102 and an image capture system 104. The stage 102 may be positioned opposite the image capture system 104 and may carry one or more substrates for inspection. The stage 102 may include a granite structure and a chuck for holding the substrates. The stage 102 may be movable in the x, y, z, and θ directions.

[0025] The image capture system 104 may include a microscope objective, a microscope tube lens, and a camera. The camera may be configured as an image sensor, such as a CMOS or CCD sensor. In some examples, the camera may be configured as an infrared sensor, such as an InGaAs sensor. The camera may be coupled to a processor that includes an image analysis module. The processor may process the images generated by the camera and analyze the images to detect defects. The processor may do this by running at least one algorithm that compares a reference image with the captured image. The processor may execute machine learning algorithms to detect defects in images captured by the camera of different portions of the substrate.

[0026] exist Figure 1In the example, as the stage moves, the image capture system 104 remains stationary, allowing different portions of the substrate to be positioned below the image capture system 104 at different times, and the image capture system 104 can capture images of different portions of the substrate to be inspected. These images can be compared with stored template images to detect defects in the substrate.

[0027] The stage 102 can move in a serpentine pattern, allowing the image capture system 104 to capture images of different portions of the substrate. As described above, the movement of the stage 102 (i.e., exposure time) while the image capture system 104 is capturing an image can cause motion blur in the image. To reduce motion blur, the stage 102 can move in a stop-and-go manner. That is, the stage 102 can stop moving when a portion of the substrate to be imaged is positioned below the image capture system. After capturing an image, the stage 102 can move such that the next portion of the substrate to be imaged is positioned below the image capture system, and the image of the next portion is captured. The amount of time the stage 102 stops for each image capture can be equal to or greater than the exposure time of the image capture system 104.

[0028] Stage 102 can continue this walk-stop operation in a serpentine pattern or other specified pattern until different portions of the substrate have been imaged. However, stage 102 can be heavy (e.g., about 150 pounds). Accelerating and decelerating heavy structures such as stage 102 in a walk-stop manner can have disadvantages such as causing vibration and reducing throughput.

[0029] The following describes other techniques for reducing motion blur. For example, an image capture system can move at essentially the same speed as the stage during camera exposure to reduce motion blur.

[0030] Figure 2 An example portion of an inspection system performing an inspection using a moving camera system 200 is illustrated. The inspection system 200 may include a stage 202 and an image capture system 204. The stage 202 may be positioned opposite the image capture system 205 and may hold one or more substrates for inspection. The stage 202 may include a granite structure and a chuck for holding the substrates. The stage 202 may be movable in the x, y, z, and θ directions. For example, the stage 202 may move at a speed greater than 20 mm / sec. In some examples, the stage 202 may move at approximately 200 mm / sec.

[0031] In this example, the image capture system 204 can be coupled to an actuator to move the image capture system in the x and y directions. When capturing an image of a portion of the substrate, the image capture system 204 can travel at substantially the same speed as the stage 202, such that from the camera's perspective, the stage appears substantially stationary, and thus image blur is reduced. The image capture system 204 can then be moved so that it is positioned over the next portion of the substrate to be imaged, and the speed of the image capture system 204 can then be controlled so that it again substantially matches the speed of the stage 202 to capture an image of the corresponding portion with reduced blur. During the inspection process, the stage 202 can move at a substantially constant speed, thereby reducing vibration and increasing throughput.

[0032] Figure 3 This is a flowchart of method 300 for semiconductor inspection, which uses a moving camera to reduce blur. For example, the method described in the reference above can be used... Figure 2 The described inspection system 200 is used to perform this method.

[0033] At operation 302, the stage carrying the substrate to be inspected can move at a substantially constant speed. For example, the stage can move at a speed greater than 20 mm / sec. In some examples, the stage can move at approximately 200 mm / sec. At operation 304, the image acquisition system can be positioned above a first portion of the substrate to be imaged, and the image acquisition system can move at substantially the same speed as the stage. At operation 306, an image of the first portion of the substrate can be captured. Because the stage and the image acquisition system travel at substantially the same speed, motion blur in the image is reduced.

[0034] At operation 308, the image capture system is moved to position itself above the second portion of the substrate to be imaged, while the stage maintains its substantially constant speed. For example, the image capture system can be accelerated to move forward, positioning it above the second portion, and then decelerated to match the stage speed. In another example, the image capture system can be decelerated to move backward relative to the stage, positioning it above the second portion, and then accelerated to match the stage speed. At operation 310, an image of the second portion of the substrate is captured. Because the stage and image capture system travel at substantially the same speed, motion blur in the image is reduced.

[0035] These steps can be repeated until the last portion of the substrate (the nth portion) is imaged. In some examples, the stage and / or image capture system can move in a serpentine pattern or other specified pattern to image different portions of the substrate. At operation 312, the image capture system is moved such that it is positioned above the nth portion of the substrate to be imaged, while the stage maintains its substantially constant speed of movement. At operation 314, an image of the nth portion of the substrate is captured. Because the stage and the image capture system travel at substantially the same speed, motion blur in the image is reduced. The image capture system can weigh from about 5 pounds to 20 pounds, and is therefore significantly smaller than the stage (e.g., about 150 pounds); therefore, the vibration caused by the acceleration and deceleration of the image capture system is significantly less than the vibration caused by the stage moving in a stop-and-go manner as described above.

[0036] The optical system within the image capture system can also be used to compensate for stage movement, thus resolving blurring. Considering the magnification of the image capture system, linear motion in stage space can be converted to linear motion in camera space. For example, if the stage moves at velocity v and the magnification of the image capture system is 10x, the target in camera space can be considered to move at 10v (magnification multiplied by the stage velocity). The movement of the stage relative to the image capture system can also be defined by rotational motion in the form of deflection beam angles between components within the image capture system.

[0037] Figures 4A to 4C A beam deflection is illustrated in an image capture system with stage movement. The image capture system may include an objective lens 402, a barrel lens 404, and a camera 406 (e.g., an image sensor). Figures 4A to 4C The diagram illustrates beam deflection between objective lens 402 and barrel lens 404. As shown, the stage moves linearly (from right to left), causing beam deflection between objective lens 402 and barrel lens 404. The linear offset between beams A and B can be defined by the rotation angle α. Therefore, beam angle deflection α can reduce or eliminate motion blur caused by stage movement. Thus, for a stage with a moving velocity v, the corresponding angular velocity ω of the deflection can compensate for motion blur, which can be expressed as: ω = v / f Where f is the focal length of objective lens 402.

[0038] Figure 5 An example portion of an image capture system 500 having an optical system for reducing motion blur is illustrated. The image capture system 500 may include an objective lens 502, a first mirror 504, a second mirror 506, a barrel lens 508, and a camera 510. The objective lens 502 may include optical lenses and other optical components for providing a fixed magnification. The objective lens 502 may be selected from multiple objectives to achieve different magnifications.

[0039] The barrel lens 508 may include optical lenses and other optical components for focusing a light beam onto the camera 510. In some examples, the barrel lens 508 may include a fluid focusing device for providing variable focus shift based on the variable refractive index of a fluid encapsulated therein. A charge may be applied to the fluid focusing device by a controller (not shown) to change the refractive index of the fluid within the fluid focusing device, which in turn adjusts the focus of the image capture system 500. The controller may adjust the charge applied to the fluid focusing device in the barrel lens 508 to rapidly change the focus of the final image, thereby compensating for different contour variations of the substrate being examined. For example, the fluid focusing device may be configured as a tunable acoustic gradient lens. The fluid focusing device can compensate for focus blur in the image caused by variations in substrate height. In some examples, the barrel lens 508 may be configured as a digital micromirror device. The digital micromirror device may be controlled by a controller to change the focus, thereby compensating for focus blur caused by variations in substrate height.

[0040] Camera 510 may be configured as an image sensor, such as a CMOS or CCD sensor. In some examples, the camera may be configured as an infrared sensor, such as an InGaAs sensor. Camera 510 may be coupled to a processor including an image analysis module. The processor may process the images generated by the camera and analyze the images to detect defects. The processor may execute machine learning algorithms to detect defects in the images captured by the camera of different parts of the substrate. In some examples, camera 510 may include other optical components, such as a focusing lens.

[0041] First reflector 504 and second reflector 506 can be configured in a periscope manner between objective lens 502 and barrel lens 508 to reduce motion blur. First reflector 504 can be coupled to a motor, such as a DC motor or piezoelectric motor, to rotate or jiggle the reflector based on the stage speed, thereby reducing motion blur by adjusting the beam deflection between objective lens 502 and barrel lens 508. The first reflector can be configured as a small reflector, such as having dimensions of 6mm × 35mm × 25mm and a weight of approximately 14 grams. In some examples, second reflector 506 can be positioned in a fixed orientation to reflect the beam from first reflector 504 to barrel lens 508. In some examples, second reflector 506 can also be configured to rotate or jiggle, such that a combination of movements of first reflector 504 and second reflector 506 produces the desired beam deflection. As described further below, first reflector 504 (and second reflector 506 in some examples) can be configured as a digital micromirror device.

[0042] In some examples, the first reflector 504 can rotate continuously in one direction based on the stage's velocity according to a predetermined angular velocity curve. For example, the stage can move at a speed greater than 20 mm / sec. In some examples, the stage can move at approximately 200 mm / sec.

[0043] The first reflector 504 can be coupled to a motor (such as a DC motor) and an encoder to monitor the speed of the first reflector 504. The motor can drive the first reflector 504 to rotate based on a predetermined angular velocity curve. Figure 6 An example of a preset angular velocity curve for a rotating mirror is illustrated. The first mirror 504 can be accelerated to its maximum angular velocity (e.g., approximately 950 Rad. / sec in this example), and then decelerated to a low and constant speed, and then accelerated again to its maximum angular velocity, and so on. During interval 602, the first mirror 504 rotates at a low and constant speed, which matches the movement speed of the stage. The rotational speed of the first mirror 504 during interval 602 is substantially lower than the rotational speed of the first mirror 504 during other time periods. When the speed of the first mirror 504 reaches a low and constant speed at interval 602, the camera 510 can then capture an image of the portion of the substrate positioned below the image capture system. The duration of interval 602 is sufficient to cover the exposure time of the camera 510.

[0044] In some examples, the first reflector 504 can jitter back and forth within a specified angular range at its equilibrium position based on the stage's velocity according to a predetermined angular velocity curve. For example, the stage can move at a speed greater than 20 mm / sec. In some examples, the stage can move at approximately 200 mm / sec.

[0045] The first reflector 504 can be coupled to a motor, such as a DC motor or a piezoelectric motor, to move the first reflector 504 back and forth based on a predetermined angular velocity curve. Figure 7 An example of a preset angular velocity profile for a dithering mirror is illustrated. The first mirror 504 can be accelerated to its maximum angular velocity (e.g., 12 Rad. / sec in this example). The first mirror 504 can be maintained at this velocity at least at a interval 702. During the interval 702, the camera 510 can capture an image of the portion of the substrate positioned below the image capture system. The duration of the interval 702 can be sufficient to cover the exposure time of the camera 510. For example, the interval 702 can be at least 1 millisecond, during which the speed of the dithering mirror is controlled at a specified speed (e.g., 12 Rad. / sec in this example).

[0046] The piezoelectric motor can control the jitter of the first reflector 504 based on an angular velocity curve. In a steady state, the jittering motion can be repeated at a frequency period (e.g., 100 Hz). The frequency period can be adjustable.

[0047] Figure 8 An example of the motion curve of a jittery mirror is illustrated. In step (a), the mirror may come to rest at its equilibrium position. In this step, the angular velocity ω is zero. In step (b), after an initial start time (T0), the mirror may pass through the equilibrium position with a non-zero angular velocity ω. In step (c), the mirror may enter an interval (e.g., interval 702) for image capture at time TD1 with a specified angular velocity (e.g., 12 Rad. / sec), where TD1 represents the start of the interval in the frequency period. In step (d), the mirror maintains the specified angular velocity for a specified interval duration (e.g., 1 ms), which ends at time TD2, where TD2 represents the end of the interval, such that the interval duration is TD2 - TD1.

[0048] In steps (e1), (e2), and (e3), the mirror can swing in opposite directions and return. In step (f), the mirror can pass the equilibrium position with the same non-zero angular velocity as in step (b). The wobbling motion can then be repeated.

[0049] As described above, the jitter mirror (e.g., the first mirror 504) can be configured as a digital micromirror device to provide the jitter motion described herein. Figure 9A An example portion of a digital micromirror device 900 with dithering capability is illustrated. The digital micromirror device 900 may include an array of micromirrors 902a to 902n. The top surface of the micromirror array 902a to 902n includes a mirror surface. For example, the top surface of the micromirror array 902a to 902n may be coated with a mirror material. The array of micromirrors 902a to 902n may be formed on a silicon substrate, wherein each micromirror in the micromirrors 902a to 902n corresponds to a mirror pixel of the digital micromirror device 900. The micromirrors 902a to 902n may be individually addressable to change the tilt angle of the respective micromirror 902a to 902n. The micromirrors 902a to 902n may be closely spaced, such that the micromirrors effectively provide an image of an object or substrate to an image sensor.

[0050] Figure 9BA schematic diagram illustrating an example portion of a micromirror 902a is shown. The micromirror 902a may include a top surface 904 fabricated using a mirror material. The top surface 904 may be coupled to a first electrode 906, a second electrode 908, and a power connector 910. The first electrode 906 and the second electrode 908 may be controlled to change the tilt angle of the top surface 904. For example, the first electrode 906 may be coupled to a positive voltage source, and the second electrode 908 may be coupled to a negative voltage source. A controller (not shown) may supply power to the first and second electrodes 908 to change the tilt angle (α) of the top surface 904 of the micromirror 902a, thereby providing a specified jitter angle. The power connector 910 may be used to supply power to the micromirror 902a.

[0051] Micromirrors 902a to 902n can be individually controlled to change their respective tilt angles, thereby providing a jitter profile for the micromirror device 900 to reduce motion blur as described above (e.g., Figure 7 and Figure 8 (and its description). The time to change the tilt angle is relatively short because digital micromirror devices are microelectromechanical systems (MEMS), and the micromirrors 902a to 902n are relatively small in size. Compared to conventional mirrors in which the entire mirror (or at least the entire mirror surface) is moved to provide a jitter profile, the base of a digital micromirror device can remain stationary, while the top surface of the micromirror moves based on an electrically controlled signal to provide a jitter profile.

[0052] The techniques shown and described herein can be used in the inspection system machine shown in the above figure, either as part or in whole, or otherwise used as described in the following text. Figure 10 The machine in question is 1000 to execute this. Figure 10 A block diagram illustrating an example of a machine 1000 including any or more of the techniques (e.g., methods) discussed herein that can be performed thereon. In various examples, machine 1000 may operate as a standalone device or may be connected (e.g., networked) to other machines.

[0053] In a networked deployment, Machine 1000 can operate as a server machine, a client machine, or both in a server-client network environment. In one example, Machine 1000 can act as a peer-to-peer (P2P) (or other distributed) network environment. Machine 1000 can be a personal computer (PC), tablet device, set-top box (STB), personal digital assistant (PDA), mobile phone, web appliance, network router, switch, or bridge, or any machine capable of (sequentially or otherwise) executing instructions specifying actions to be taken by that machine. Furthermore, although only a single machine is shown, the term "machine" should also be understood to include any collection of machines that individually or jointly execute one or more sets of instructions to perform any or more of the methods discussed herein, such as cloud computing, Software as a Service (SaaS), and other computer cluster configurations.

[0054] Examples as described herein may include logic or multiple components or mechanisms, or may be operated by logic or multiple components or mechanisms. A circuit system is a collection of circuits implemented in a tangible entity including hardware (e.g., simple circuits, gates, logic, etc.). The membership of a circuit system may change over time and with potential hardware variations. A circuit system includes members that can perform a specified operation individually or in combination during operation. In one example, the hardware of the circuit system may be immutably designed to perform a specific operation (e.g., hardwired). In one example, the hardware including the circuit system may include variable-connected physical components (e.g., execution units, transistors, simple circuits, etc.) including computer-readable media that are physically modified (e.g., magnetically, electrically, such as via a change in physical state or a transformation of another physical property) to encode instructions for a specific operation. When connecting physical components, the underlying electrical characteristics of the hardware composition may, for example, change from insulating to conductive or vice versa. Instructions enable embedded hardware (e.g., execution units or loading mechanisms) to form members of a circuit system in the hardware via variable connections to perform a specific operation during operation. Therefore, when the device is operational, the computer-readable medium is communicatively coupled to other components of the circuit system. In one example, any physical component may be used in more than one member of more than one circuit system. For instance, in operation, an execution unit may be used in a first circuit of a first circuit system at one point in time, and may be reused at different times by a second circuit of the first circuit system or by a third circuit of the second circuit system.

[0055] Machine 1000 (e.g., a computer system) may include a hardware-based processor 1001 (e.g., a central processing unit (CPU), a graphics processing unit (GPU), a hardware processor core, or any combination thereof), main memory 1003, and static memory 1005, some or all of which may communicate with each other via interconnect 1030 (e.g., a bus). Machine 1000 may also include a display device 1009, an input device 1011 (e.g., an alphanumeric keypad), and a user interface (UI) navigation device 1013 (e.g., a mouse). In one example, display device 1009, input device 1011, and UI navigation device 1013 may include at least a portion of a touchscreen display. Machine 1000 may additionally include a storage device 1020 (e.g., a drive unit), a signal generation device 1017 (e.g., a speaker), a network interface device 1050, and one or more sensors 1015 (such as a global positioning system (GPS) sensor, a compass, an accelerometer, or other sensors). Machine 1000 may include output controller 1019, such as a serial controller or interface (e.g., Universal Serial Bus (USB)), a parallel controller or interface, or other wired or wireless (e.g., infrared (IR) controller or interface, near field communication (NFC), etc.), which are coupled to communicate or control one or more peripheral devices (e.g., printers, card readers, etc.).

[0056] Storage device 1020 may include a machine-readable medium on which one or more sets of data structures or instructions 1024 (e.g., software or firmware) embodying or utilized by any or more of the techniques or functions described herein are stored. Instructions 1024 may also reside wholly or at least partially within main memory 1003, static memory 1005, mass storage device 1007, or hardware-based processor 1001 during execution by machine 1000. In one example, one or any combination of hardware-based processor 1001, main memory 1003, static memory 1005, or storage device 1020 may constitute a machine-readable medium.

[0057] Although machine-readable media is considered as a single medium, the term “machine-readable media” can include a single medium or multiple media (e.g., a centralized or distributed database, and / or associated caches and servers) configured to store one or more instructions 1024.

[0058] The term "machine-readable medium" can include any medium capable of storing, encoding, or carrying instructions for execution by machine 1000 and causing machine 1000 to perform any one or more of the technologies disclosed herein, or any medium capable of storing, encoding, or carrying data structures used by or associated with such instructions. Examples of non-limiting machine-readable media can include solid-state memory, as well as optical and magnetic media. Therefore, machine-readable media are not transiently propagating signals. Specific examples of large-scale machine-readable media can include: non-volatile memory, such as semiconductor memory devices (e.g., electrically programmable read-only memory (EPROM), electrically erasable programmable read-only memory (EEPROM)) and flash memory devices; magnetic or other phase-change or state-changing memory circuits; magnetic disks, such as internal hard disks and removable disks; magneto-optical disks; and CD-ROM and DVD-ROM disks.

[0059] The transmission medium can also be used to send or receive instructions 1024 on the communication network 1021 via the network interface device 1050 using any of a variety of transmission protocols (e.g., Frame Relay, Internet Protocol (IP), Transmission Control Protocol (TCP), User Datagram Protocol (UDP), Hypertext Transfer Protocol (HTTP), etc.). Example communication networks may include local area networks (LANs), wide area networks (WANs), packet data networks (e.g., the Internet), mobile phone networks (e.g., cellular networks), conventional telephone (POTS) networks, and wireless data networks (e.g., known as Wi-Fi). ® The Institute of Electrical and Electronics Engineers (IEEE) 802.22 standard series, known as WiMax ® The IEEE 802.26 series of standards, the IEEE 802.27.4 series of standards, peer-to-peer (P2P) networks, etc. In one example, network interface device 1050 may include one or more physical jacks (e.g., Ethernet, coaxial, or telephone jacks) or one or more antennas for connecting to communication network 1021. In one example, network interface device 1050 may include multiple antennas for wireless communication using at least one of single-input multiple-output (SIMO), multiple-input multiple-output (MIMO), or multiple-input single-output (MISO) technologies. The term "transmitting medium" should be understood to include any intangible medium capable of storing, encoding, or carrying instructions for execution by machine 1000, and includes digital or analog communication signals or other intangible media used to facilitate communication of such software.

[0060] Various precautions Each of the above non-limiting aspects may be independent or may be arranged or combined in various ways with one or more of the other aspects or other topics described in this document.

[0061] The above detailed description includes reference to the accompanying drawings, which form a part of this detailed description. The drawings illustrate, by way of example, specific embodiments in which the invention may be practiced. These specific embodiments are also generally referred to as "examples." Such examples may include elements other than those shown or described. However, the inventors also contemplate examples that provide only those elements shown or described. Furthermore, the inventors contemplate examples using any combination or arrangement of those elements (or one or more aspects thereof) shown or described relative to a particular example (or one or more aspects thereof) or relative to other examples (or one or more aspects thereof) shown or described in the text.

[0062] In the event of any inconsistency between the usage in this document and any other document incorporated herein by reference, the usage in this document shall prevail.

[0063] In this document, the terms “a” or “an” are used as commonly found in patent documents to include one or more, independent of any other instances or uses of “at least one” or “one or more.” In this document, unless otherwise specified, the term “or” is used to mean non-exclusive or such that “A or B” includes “A but not B,” “B but not A,” and “A and B.” In this document, the terms “comprising” and “in which” are used as their commonly understood English equivalents to the corresponding terms “including” and “wherein.” Furthermore, the terms “comprising” and “including” are open-ended, meaning that a system, apparatus, article, composition, formulation, or process that includes elements other than those listed after such terms in one aspect is still considered to fall within the scope of that aspect. Additionally, in other aspects, the terms “first,” “second,” and “third,” etc., are used merely as labels and are not intended to impose numerical requirements on their objects.

[0064] The examples of methods described herein may be implemented, at least in part, by a machine or computer. Some examples may include computer-readable or machine-readable media encoded with instructions for configuring an electronic device to perform the methods described in the examples above. Specific implementations of such methods may include code, such as microcode, assembly language code, high-level language code, etc. Such code may include computer-readable instructions for performing various methods. The code may form part of a computer program product. Furthermore, in one example, such as during execution or at other times, the code may be tangibly stored on one or more volatile, non-transitory, or non-volatile tangible computer-readable media. Examples of such tangible computer-readable media may include, but are not limited to, hard disks, removable disks, removable optical disks (e.g., high-density disks and digital video disks), magnetic tape cassettes, memory cards or sticks, random access memory (RAM), read-only memory (ROM), etc.

[0065] The above description is intended to be illustrative and not limiting. For example, the examples (or one or more aspects thereof) described above may be used in combination with each other. Other embodiments may be used, as will be apparent to those skilled in the art after reading the above description. A summary of the specification is provided to enable the reader to quickly determine the essence of the technical disclosure. It should be understood at the time of submission that it is not intended to interpret or limit the scope or meaning of any aspect. Furthermore, in the above embodiments, various features may be combined together to simplify the disclosure. This should not be construed as meaning that any unclaimed disclosed features are necessary for any claim. Rather, the subject matter of the invention may be present in all features of fewer than a particular disclosed embodiment. Therefore, the following aspects are thus incorporated into the embodiments as examples or embodiments, wherein each aspect is independently a separate embodiment, and it is contemplated that such embodiments may be combined or arranged in various ways.

Claims

1. An image capture system for reducing motion blur during semiconductor inspection, the image capture system comprising: a stage for holding a substrate for inspection, wherein the stage is configured to move at a substantially constant velocity during inspection; a microscope objective positioned opposite the stage; a mirror system for receiving a light beam representing the substrate from the microscope objective and reflecting the light beam to a tube lens, the mirror system comprising a mirror configured to move according to a pre-set angular velocity profile based on the velocity of the stage, wherein the mirror system moves at a specified angular velocity for a defined time interval; and an image sensor for generating an image of a portion of the substrate based on the light beam received from the tube lens during the defined time interval.

2. The image capture system of claim 1, further comprising: a piezoelectric motor coupled to the mirror to dither the mirror in a specified angular range about an equilibrium position of the mirror based on the pre-set angular velocity profile.

3. The image capture system of claim 2, wherein the mirror dithers at a maximum angular velocity during the defined time interval.

4. The image capture system of claim 1, wherein the angular velocity of the mirror reaches a substantially constant velocity during the defined time interval that is lower than other time intervals in the angular velocity profile.

5. The image capture system of claim 1, wherein the mirror is a digital micro-mirror device.

6. The image capture system of claim 1, wherein the substantially constant velocity is greater than 20 mm / sec.

7. The image capture system of claim 1, further comprising: a processor for receiving images from the image sensor to detect whether a defect is present in the substrate.

8. The image capture system of claim 1, wherein the tube lens comprises a fluid focusing device comprising a variable focus shift based on a variable refractive index.

9. The image capture system of claim 8, wherein the fluid focusing device comprises a tunable acoustic gradient lens.

10. The image capture system of claim 1, wherein the tube lens comprises a digital micro-mirror device.

11. A method for inspecting a substrate, the method comprising: loading the substrate on a stage of an inspection system; moving the stage at a substantially constant velocity; positioning the stage opposite a microscope objective; moving a mirror to reflect a light beam representing the substrate from the microscope objective to a tube lens, the mirror moving according to a pre-set angular velocity profile based on the velocity of the stage, wherein mirror moves at a specified angular velocity for a defined time interval; and ​ ​ generating an image of a portion of the substrate based on the light beam received from the tube lens during the defined time interval.

12. The method of claim 11, further comprising: dithering the mirror in a specified angular range about an equilibrium position of the mirror based on the preset angular velocity profile using a piezoelectric motor.

13. The method of claim 12, wherein the mirror is dithered at a maximum angular velocity during the defined time interval.

14. The method of claim 11, wherein the angular velocity of the mirror reaches a substantially constant velocity during the defined time interval, the substantially constant velocity being lower than other time intervals in the angular velocity profile.

15. The method of claim 11, wherein the mirror comprises a digital micromirror device.

16. The method of claim 11, wherein the substantially constant velocity is greater than 20 mm / sec.

17. The method of claim 11, wherein the tube lens comprises a fluid focusing device having a variable focus shift based on a variable refractive index, wherein the fluid focusing device comprises a tunable acoustic gradient lens.

18. The method of claim 17, wherein the tube lens comprises a digital micromirror device.

19. A system, comprising: a microscope objective positioned opposite a stage holding a substrate for inspection, wherein the stage is configured to move at a substantially constant velocity during inspection; a tube lens; a mirror system positioned between the microscope objective and the tube lens, the mirror system for receiving a light beam from the microscope objective representing the substrate and reflecting the light beam to tube lens, the mirror system comprising: a first mirror for moving according to a preset angular velocity profile based on the velocity of the stage, wherein the first mirror moves at a specified angular velocity for a defined time interval, and a second mirror positioned opposite the first mirror in a fixed orientation; and a camera for generating an image of a portion of the substrate based on the light beam received from the tube lens during the defined time interval.

20. The system of claim 19, further comprising: a piezoelectric motor coupled to the mirror to dither the mirror in a specified angular range about an equilibrium position of the mirror based on the preset angular velocity profile, wherein the mirror is dithered at a maximum angular velocity during the defined time interval.

21. The system of claim 19, wherein the mirror comprises a digital micromirror device.

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