Method for determining X and Y location of surface particles

Abstract

The system includes a modulator, a laser source, a mirror, a laser sensor, and a processor. The modulator is movable along a first direction. The laser source is configured to emit laser light along a direction parallel to the modulator surface. The mirror is configured to redirect the laser light. The laser sensor is configured to detect a first intensity change when a particle on the modulator surface passes through the laser light emitted by the laser source. The laser sensor is further configured to detect a second intensity change when a particle on the modulator surface passes through the laser light redirected by the at least one mirror. The processor is configured to determine an XY location of the particle based on the first intensity change and the second intensity change.

Description

[Technical field]

[0001] FIELD OF THE DISCLOSURE This disclosure relates to inspection processes, and more particularly to surface particle detection processes on inspection tools. [Background technology]

[0002] An example of an inspection process is to use a modulator to detect defects in electrical circuits on a glass panel. For example, the modulator can be moved over a portion of the glass panel and lowered to within a few tens of micrometers of the surface of the glass panel. When a drive signal is applied to the electrodes of the glass panel, the electric field from the glass panel produces a temporary visible indication on the modulator that can be captured by a camera and inspected for defects. However, because the glass panel and modulator are positioned close to each other during inspection, foreign objects (e.g., particles) that are often present between the glass panel and the modulator can cause damage during the inspection operation. The particles can also reduce the accuracy of the inspection process.

[0003] Current methods for cleaning modulators are open-type, i.e., the modulator surface may be periodically cleaned during an inspection process, but there is no assurance that foreign matter has been removed from the modulator. Furthermore, detection of foreign matter on the modulator surface by existing methods does not allow for the location of those particles to verify their removal or diagnose problems within the system. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Korean Patent Publication No. 2022-0120342 Summary of the Invention [Problem to be solved by the invention]

[0005] Therefore, a method is needed to determine the X and Y location of surface particles. [Means for solving the problem]

[0006] An embodiment of the present disclosure provides a system that includes a modulator, a laser light source, at least one mirror, a laser sensor, and a processor. The modulator may be configured to detect defects in the electrical circuit. The modulator may be movable in a first direction. The modulator may be movable at a constant speed. The laser light source may be located proximate to a first side of the modulator. The laser light source may be configured to emit laser light along a direction parallel to the modulator surface and at a first angle to the first direction toward a second side of the modulator. The laser light may overlap with the modulator surface. At least one mirror may be located proximate to a second side of the modulator opposite the first side. The at least one mirror may be configured to redirect the laser light toward the first side of the modulator at a second angle to the first direction. The laser sensor may be located proximate to the first side of the modulator. The laser sensor may be configured to detect a first change in intensity of laser light received from the laser light source as a particle on the modulator surface passes through the laser light emitted by the laser light source and to detect a second change in intensity of laser light received from the laser light source redirected by the at least one mirror as a particle on the modulator surface passes through the laser light redirected by the at least one mirror. The processor may be configured to determine an XY location of the particle based on the first and second intensity changes.

[0007] According to certain embodiments of the present disclosure, the system may further include an air knife configured to remove the particle from the modulator surface after the XY location of the particle has been determined, the air knife may be located between the laser source and the laser sensor or may be located downstream from the laser source and the laser sensor.

[0008] According to some embodiments of the present disclosure, the at least one mirror can include a pair of mirrors positioned at a symmetric angle relative to the first direction.

[0009] According to some embodiments of the present disclosure, the at least one mirror can include a mirror oriented parallel to the first direction.

[0010] According to certain embodiments of the present disclosure, the XY location of a particle can be determined relative to an origin defined by the first corner of the modulator that passes through the laser light emitted by the laser source.

[0011] According to one embodiment of the present disclosure, the XY location of the particle can be determined based on a first distance between the laser source and the origin determined at a time corresponding to a first intensity change and a second distance between the laser sensor and the origin determined at a time corresponding to a second intensity change.

[0012] According to certain embodiments of the present disclosure, the XY location of the particle can be determined based on the difference between the time corresponding to the first intensity change and the time corresponding to the second intensity change.

[0013] According to certain embodiments of the present disclosure, the XY location of the particle can be determined based on the first angle and / or the second angle. The first angle and the second angle can be between 0 degrees and 90 degrees.

[0014] Another embodiment of the present disclosure provides a method for moving a modulator configured to detect defects in an electrical circuit in a first direction, emitting laser light from a laser source disposed adjacent to a first side of the modulator along a direction parallel to a surface of the modulator and at a first angle to the first direction toward a second side of the modulator, and overlapping the laser light with the surface of the modulator, and redirecting the laser light toward the first side of the modulator at a second angle to the first direction by at least one mirror disposed adjacent to a second side of the modulator opposite the first side. a laser sensor disposed adjacent to a first side of the modulator detects a first intensity change in the laser light received from the laser light source when a particle on the modulator surface passes through the laser light emitted by the laser light source, and a laser sensor detects a second intensity change in the laser light received from the laser light source after being redirected by the at least one mirror when a particle on the modulator surface passes through the laser light redirected by the at least one mirror, and a processor determines an XY location of the particle based on the first intensity change and the second intensity change.

[0015] According to certain embodiments of the method disclosed herein, particles may be removed from the surface of the modulator by passing the modulator through an air knife. The air knife may be disposed between the laser source and the laser sensor, and may be configured to be off when the modulator is moved in a first direction. The method may further include moving the modulator in a second direction opposite the first direction. The air knife may be configured to be on when the modulator is moved in the second direction.

[0016] According to certain embodiments of the present disclosure, an air knife can be positioned downstream from the laser source and the laser sensor and configured to be on when the modulator is moved in a first direction.

[0017] According to an embodiment of the method of the present disclosure, the corner of the modulator that first passes through the laser light emitted from the laser light source can be defined as an origin, and the XY location of the particle can be determined relative to the origin.

[0018] According to one embodiment of the present disclosure, when the processor determines the XY location of the particle based on the first intensity change and the second intensity change, a first distance between the laser light source and the origin is determined at a time corresponding to the first intensity change, a second distance between the laser sensor and the origin is determined at a time corresponding to the second intensity change, and the XY location of the particle is determined based on the first and second distances.

[0019] According to one embodiment of the present disclosure, when the processor determines the XY location of the particle based on the first intensity change and the second intensity change, the distance traveled by the modulator along the first direction between the time corresponding to the first intensity change and the time corresponding to the second intensity change is determined, and the XY location of the particle is determined based on the distance traveled by the modulator along the first direction between the time corresponding to the first intensity change and the time corresponding to the second intensity change.

[0020] For a complete understanding of the nature and scope of the present disclosure, reference should be made to the following detailed description taken in conjunction with the accompanying drawings, in which: [Brief description of the drawings]

[0021] [Figure 1A] FIG. 2 illustrates a modulator passing through a system in a first configuration of the present disclosure along a first direction. [Figure 1B] FIG. 2 illustrates a modulator passing through a system in a first configuration of the present disclosure along a first direction. [Figure 1C] FIG. 2 illustrates a modulator passing through a system in a first configuration of the present disclosure along a first direction. [Figure 1D] FIG. 2 illustrates a modulator passing through a system in a first configuration of the present disclosure along a first direction. [Figure 1E] FIG. 2 illustrates a modulator passing through a system in a first configuration of the present disclosure along a first direction. [Figure 1F] FIG. 2 illustrates a modulator passing through a system in a first configuration of the present disclosure along a first direction. [Figure 1G] A diagram illustrating a modulator passing through the system in a first configuration along a second direction. [Figure 1H] A diagram illustrating a modulator passing through the system in a first configuration along a second direction. [Figure 2A] FIG. 2 is a diagram illustrating a modulator passing through a system in a second configuration of the present disclosure along a first direction. [Figure 2B] 4 is a corresponding output signal graph. [Figure 2C] FIG. 2 is a diagram illustrating a modulator passing through a system in a second configuration of the present disclosure along a first direction. [Figure 2D] 4 is a corresponding output signal graph. [Figure 2E] FIG. 2 is a diagram illustrating a modulator passing through a system in a second configuration of the present disclosure along a first direction. [Figure 2F] 4 is a corresponding output signal graph. [Figure 2G] FIG. 2 is a diagram illustrating a modulator passing through a system in a second configuration of the present disclosure along a first direction. [Figure 2H] 4 is a corresponding output signal graph. [Figure 3A] A diagram illustrating the modulator passing through the system in a second configuration along a second direction. [Figure 3B] A diagram illustrating the modulator passing through the system in a second configuration along a second direction. [Figure 4] 1 is a flowchart of a method according to an embodiment of the present disclosure. [Diagram 5] 4 is a flowchart of a method according to another embodiment of the present disclosure. [Figure 6] 4 is a flowchart of a method according to another embodiment of the present disclosure. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0022] Although the claimed subject matter is described in terms of certain embodiments, other embodiments are within the scope of this disclosure, including embodiments that do not provide all of the benefits and features described herein. Various structural, logical, process step, and electronic changes may be made without departing from the scope of the disclosure. That is, the scope of the disclosure is defined solely by reference to the appended claims.

[0023] In one embodiment of the present disclosure, a system 100 is provided. A first configuration of the system 100 is shown in Figures 1A-1H, and a second configuration of the system 100 is shown in Figures 2A-2H and 3A-3B. Reference will be made interchangeably to the system 100 in the first and second configurations throughout this application. The system 100 may be part of a system used to test electrical circuits, such as those in glass display panels. Liquid crystal display (LCD) panels incorporate liquid crystals that exhibit electric field-dependent light modulation properties. They are frequently used to display images and other information in a variety of devices ranging from fax machine and laptop computer screens to large-screen high definition TVs. An active matrix LCD panel is a complex multi-layer structure consisting of several functional layers, including a TFT glass substrate incorporating polarizers, thin film transistors, storage capacitors, pixel electrodes and interconnect lines, a color filter glass substrate incorporating a black matrix, a color filter array and a transparent common electrode, and an actual liquid crystal material incorporating a polyimide alignment layer and plastic / glass spacers to maintain the proper LCD cell thickness. The system 100 can also be used to test other types of glass display panels (e.g., OLED, micro LED, etc.) and other types of electrical circuits disposed on the substrate.

[0024] 1A and 2A, the system 100 may include a modulator 110. The modulator 110 may be configured to detect defects in electrical circuits, such as those in a glass panel. For example, the modulator 110 may be movable over a portion of the glass panel and may be lowered to within a few tens of micrometers of the surface of the glass panel. When a drive signal is applied to the electrodes of the glass panel, an electric field from the glass panel may generate a temporary visible indication on the surface 113 of the modulator 110, which may be captured by a camera to inspect for defects. The modulator 110 may be moved in the X, Y, and Z directions by a gantry (not shown). The gantry may be configured to move the modulator at a constant speed v. For example, the modulator 110 may be moved at a speed v of 1 m / s. Other speeds (higher or lower) may be adopted depending on the system requirements. The modulator 110 may be moved to perform detection and cleaning processes on the modulator 110, as described in detail herein. During the detection and cleaning process, the modulator 110 can be moved in a first direction. The first direction can correspond to a -Y direction. The modulator 110 can be of various sizes and shapes. For example, the modulator 110 can be a square with sides less than 200 mm. In one embodiment, the modulator 110 can be 131 mm by 131 mm. Larger sizes of the modulator 110 (e.g., 500 mm) can also be used. Other sizes and shapes of the modulator 110 can also be used.

[0025] Although the present disclosure is described in the context of modulator 110, the present system 100 can also be used for particle detection on wafers that are, for example, circular and have a diameter of 100 mm to 300 mm, and on mother glass that is, for example, 3 m x 3 m or larger.

[0026] The system 100 may further include a laser light source 120. The laser light source 120 may be located proximate to the first side 111 of the modulator 110. For example, the laser light source 120 may be disposed on the first support structure 101 of the system 100. When the modulator 110 is moved in a first direction during the detection and cleaning process, the first side 111 of the modulator 110 is proximate to and parallel to the first support structure 101. The laser light source 120 may be configured to emit a laser light 122 toward the second side 112 of the modulator 110 along a direction parallel to the surface 113 of the modulator 110 and at a first angle α with respect to the first direction. For example, the laser light 122 may be a circular spot laser having a diameter of at least 100 μm, although other laser diameters are possible. According to a specific embodiment, the laser diameter may be about 1 mm. The laser light 122 can be directed parallel to the surface of the modulator 110 and can at least partially overlap the surface 113 of the modulator 110. The laser light 122 can be directed at a converging or diverging angle to the surface of the modulator 110, so long as the laser light 122 at least partially overlaps the surface 113 of the modulator 110 over its entire path.

[0027] The first angle α may be 0 to 90 degrees. For example, the first angle α may be greater than 0 degrees and less than 90 degrees and / or may be 10 to 70 degrees. According to a specific embodiment, the first angle α may be 20 degrees.

[0028] The system 100 may further include at least one mirror 130. The at least one mirror 130 may be disposed adjacent to a second side 112 of the modulator 110, opposite the first side 111. For example, the at least one mirror 130 may be disposed on the second support structure 102 of the system 100. When the modulator 110 is moved in the first direction during the detection and cleaning process, the second side 112 of the modulator 110 is adjacent to and parallel to the second support structure 102. Thus, the modulator 110 may be moved in the first direction between the first support structure 101 and the second support structure 102 during the detection and cleaning process. The at least one mirror 130 may be configured to redirect the laser light 122 toward the first side 111 of the modulator 110 at a second angle β with respect to the first direction. As used herein, the laser light 122 that has been redirected by at least one mirror may be described as redirected laser light 124.

[0029] The second angle β can be between 0 and 90 degrees. For example, the second angle β can be greater than 0 degrees and less than 90 degrees and / or between 10 and 70 degrees. According to a specific embodiment, the second angle β can be 20 degrees. The first angle α and the second angle β can be the same angle or different angles. Although the first angle α and the second angle β are shown in the figure based on the vertical direction (i.e., X direction), it should be understood that depending on the method of calculation, the complementary angle (i.e., 90-α or 90-β) of the first angle α and the second angle β may be used, and even the angle based on the horizontal direction (i.e., Y direction) may be used. Thus, the values ​​of the first angle α and the second angle β may depend on the definition of the coordinate system in the system 100.

[0030] In this embodiment, the at least one mirror 130 may be a pair of mirrors. For example, as shown in FIG. 1A-1H, the at least one mirror 130 may include a first mirror 131 and a second mirror 132. The laser light 122 from the laser source 120 may be redirected from the first mirror 131 to the second mirror 132. The portion of the laser light that is redirected by the first mirror 131 and enters the second mirror 132 may be referred to as the intermediate laser light 123. The first mirror 131 and the second mirror 132 may be separated by a distance equal to or greater than the length of the modulator 110. In this way, the modulator 110 may pass completely through the laser light 122 before passing through the redirected laser light 124. Other distances (e.g., smaller or larger) may be used based on system requirements.

[0031] The first mirror 131 and the second mirror 132 can be positioned at symmetric angles with respect to the first direction, so that the first angle α of the laser beam 122 incident on the first mirror 131 is equal to the second angle β of the redirected laser beam 124 from the second mirror 132. For example, the first mirror 131 and the second mirror 132 can be positioned so that the intermediate laser beam 123 is parallel to the first direction, so that the width between the first support structure 101 and the second support structure 102 can be minimized and / or the intermediate laser beam 123 does not cross over the surface 113 of the modulator 110. According to other designs, the first mirror 131 and the second mirror 132 can be positioned at different angles with respect to the first direction. In this way, the first angle α of the laser beam 122 incident on the first mirror 131 can be made different from the second angle β of the direction-redirected laser beam 124 from the second mirror 132, and the intermediate laser beam 123 can be angled with respect to the first direction. The separate angles, the first angle α and the second angle β, can be determined based on the system conditions.

[0032] The at least one mirror 130 may include more than two mirrors, interleaved on the first support structure 101 and the second support structure 102, such that the laser light 122 is redirected several more times.

[0033] According to another embodiment, as shown in FIGS. 2A-2H and 3A-3B, the at least one mirror 130 can be a single mirror. The mirror 130 can be disposed on the second support structure 102. The mirror 130 can be disposed parallel to the first direction. In this manner, the first angle α of the laser light 122 incident on the mirror 130 and the second angle β of the redirected laser light 124 can be equal. This design allows the mirror 130 to be easily set up and aligned with other components of the system 100. According to another design, the mirror 130 can be disposed at an angle with respect to the first direction such that the first angle α and the second angle β are different angles with respect to the first direction. The different angles, the first angle α and the second angle β, can be determined based on the system requirements. In any case, the use of a single mirror 130 can reduce space requirements compared to using more than one mirror 130.

[0034] The system 100 may further include a laser sensor 140. The laser sensor 140 may be located proximate to the first side 111 of the modulator 110. For example, the laser sensor 140 may be disposed on the first support structure 101 of the system 110. The laser sensor 140 may be located downstream of the laser light source 120 along the first direction. The laser sensor 140 may generate an output signal 145 based on the laser light 122 received from the laser light source 120. Graphs illustrating the output signal 145 are shown in Figures 2B, 2D, 2F, and 2H. A constant intensity in the output signal 145 generated by the laser sensor 140 may indicate that the surface 113 of the modulator is flat (e.g., free of defects or foreign objects). Any changes in intensity (i.e., spikes) in the output signal 145 generated by the laser sensor 140 may indicate defects or foreign objects (e.g., particles 115) on the surface 113 of the modulator 110. If greater than a predetermined threshold, the intensity change may be indicative of a defect or foreign object. The output signal 145 may be inverted relative to the power measurement, i.e., a short interruption along the laser path at that instant is represented by a leading edge spike. Alternatively, the laser sensor 140 may be configured to generate a positively varying output signal 145, with appropriate modifications to the system logic.

[0035] Particles 115 on the modulator 110 can cause damage when the modulator 110 is near a panel. Such particles may be 20 μm to 30 μm or larger in diameter.

[0036] The laser sensor 140 can be configured to detect a first intensity change 141 in the laser light 124 received from the laser light source 120 when a particle 115 on the surface 113 of the modulator 110 passes through the laser light 122 emitted by the laser light source 120 (as shown in FIGS. 1C, 2C, and 2D). In other words, the modulator 110 can be passed through the laser light 122 emitted by the laser light source 120 as the modulator 110 moves in a first direction. The presence of the particle 115 on the surface 113 of the modulator 110 will result in a first intensity change 141 in the output signal 145.

[0037] The laser sensor 140 may further be configured to detect a second intensity change 142 in the laser light 124 received from the laser source 120 after redirection by the at least one mirror 130 when a particle 115 on the surface 113 of the modulator 110 passes through the redirected laser light 124 by the at least one mirror 130 (as shown in FIGS. 1F, 2E and 2F). In other words, the modulator 110 may be further passed through the redirected laser light 124 as it is moved in the first direction. The presence of the particle 115 on the surface 113 of the modulator 110 will result in a second intensity change 142 in the output signal 145.

[0038] The system 100 may further include a processor 150. The processor 150 may include a microprocessor, a microcontroller, or other device.

[0039] Processor 150 may be coupled to components of system 100 in any suitable manner (e.g., via one or more transmission media, including, for example, wired and / or wireless transmission media) to receive the output from processor 150. Processor 150 may be configured to perform a variety of functions using the output. An inspection tool may receive instructions or other information from processor 150. Optionally, processor 150 may receive additional information or send instructions via electronic communication with another inspection tool, metrology tool, or review tool (not depicted).

[0040] The processor 150 may be part of a variety of systems, including a personal computer system, an image computer, a mainframe computer system, a workstation, a network appliance, an Internet appliance, or other device. The or those subsystems or systems may include any suitable processor known in the art, such as a parallel processor. In addition, the or those subsystems and systems may include platforms with high speed processing and software, whether stand-alone or networked tools.

[0041] The processor 150 may be a part of, e.g., disposed within, the system 100 or other device. According to one example, the processor 150 may be part of a stand-alone control unit or may be provided within a centralized quality control unit. Multiple processors 150 may be used to form multiple subsystems of the system 100.

[0042] Processor 150 may be implemented as any combination of hardware, software, and firmware, and its functions described herein may be performed in a single unit or distributed among separate components, each of which may also be implemented as any combination of hardware, software, and firmware. Program codes or instructions for causing processor 150 to perform and implement various methods and functions may be stored in a readable storage medium, such as a memory.

[0043] The processor 150 may be configured according to any of the embodiments described herein. The processor 150 may also be configured to perform other functions or additional steps using the output of the system 100 or using images or data from other sources.

[0044] The processor 150 may be communicatively coupled to any of the various components or subsystems of the system 100 in any manner known in the art. Additionally, the processor 150 may be configured to receive and / or acquire data or information from other systems via a transmission medium having, for example, wired and / or wireless sections. In this way, the transmission medium may act as a data link between the processor 150 and other subsystems of the system 100 or systems outside the system 100. The various steps, functions and / or operations of the system 100 and methods disclosed herein may be performed by one or more of electronic circuits, logic gates, multiplexers, programmable logic devices, ASICs, analog or digital controllers / switches, microcontrollers, or information processing systems. The above description should be taken as merely illustrative and not as a limitation on the present disclosure.

[0045] The processor 150 may be in communication with the laser sensor 140. For example, the processor 150 may be configured to receive the output signal 145 from the laser sensor 140. As a result, the processor 150 may receive the first intensity change 141 and the second intensity change 142 from the laser sensor 140. The processor 150 may be configured to determine an XY location of the particle 115 on the modulator 110 based on the first intensity change 141 and the second intensity change 142 according to any of the computational methods disclosed herein. The XY location of the particle 115 may be determined relative to an origin O. The origin O may be defined by the corner of the modulator 110 that first passes through the laser light 122 emitted from the laser light source 120 (as shown in FIGS. 1B and 2A). Using the output signal 145 and the velocity v, the distance of the laser light source 120 and the laser sensor 140 from the origin O may be determined. For example, if the velocity v is 1 m / s, the distance of the laser source 120 from the origin O may change by 1 mm every 1 ms. That is, the length (in mm) of the modulator 110 can be related to the duration (in ms) in the output signal 145, and the distance of the laser source 120 from the origin O can be determined at each instant of the output signal 145. Alternatively, a position encoder can be used to track the location of the modulator 110, and the processor 150 can query the position of the modulator 110 at times corresponding to the first intensity change 141 and the second intensity change to determine the relative distance from the origin O. In this way, the processor 150 can relate the time and position information from the position encoder to the time and laser power information in the output signal 145 from the laser sensor 140. Furthermore, the first angle α and / or the second angle β can be used to determine the XY location of the particle 115 using one of the methods described below.

[0046] According to an embodiment, the XY location of the particle 115 can be determined based on a first distance D1 between the laser source 120 and the origin O determined at a time T1 corresponding to a first intensity change 141, and a second distance D2 between the laser sensor 140 and the origin O determined at a time T2 corresponding to a second intensity change 142. For example, let T0 be the time when the laser beam 122 is at the origin O and the sensor output 145 begins. Let time T1 be a time point after time T0. Let time T2 be a time point after the redirected laser beam 124 is at the origin O. The first distance D1 and the second distance D2 can be determined by multiplying the velocity v by the time T1 and the time T2, respectively, or can be determined directly from the position encoder value. At time T1, particle 115 is known to be somewhere along line L1 defined by laser light 122 from laser source 120, and at time T2, particle 115 is known to be somewhere along line L2 defined by redirected laser light 124 received by laser sensor 140. The XY location of particle 115 can then be determined by the intersection of line L1 and line L2. This method is best seen in system 100 in the configuration shown in Figures 1A-1H, but can also be applied to system 100 in the configuration of Figures 2A-2H.

[0047] The intersection of lines L1 and L2 can be determined by defining lines L1 and L2 according to the slope intercept form y=mx+b, where m is the slope of the line and b is the y-intercept. Using a first angle α and a second angle β, the slopes of lines L1 and L2 can be equivalently expressed as -tan α and tan β, respectively. Depending on the definition of the X and Y directions, the slopes of lines L1 and L2 may be equivalently expressed as tan(90-α), -tan(90-β), or other values. Based on the location of origin O, the y-intercepts of lines L1 and L2 can be expressed as a first distance D1 and a second distance D2. Thus, lines L1 and L2 can be defined as y=-tan αx+D1 and y=tan βx+D2, respectively. Using these functions, the XY location of particle 115 can be determined algebraically.

[0048] As an example, the velocity v of the modulator 110 is 1 m / s, the first angle α is 20°, the second angle β is 20°, the time T1 is 77 ms, and the time T2 is 15 ms. The first distance D1 is calculated to be 77 mm, and the second distance D2 is calculated to be 15 mm. In this case, the lines L1 and L2 can be defined as y=-tan20x+77 and y=tan20x+15, respectively. The XY location of the particle 115 can be calculated as follows: -tan20x+77=tan20x+15 -0.36x+77=0.36x+15 0.72x=62 x=86mm y=tan20(86)+15 y=46mm This can be calculated as approximately (86mm, 46mm).

[0049] According to another embodiment, the XY location of the particle 115 can be determined based on the difference between time T1 corresponding to the first intensity change 141 and time T2 corresponding to the second intensity change 142. For example, let T0 be the time when the laser light 122 is at the origin O and the sensor output 145 begins, and let times T1 and T2 be times after time T0. Using the velocity v, the distance B traveled by the modulator 110 along the first direction between time T1 and time T2 can be determined. Distance B could also be determined directly from the position encoder values. Using distance B, the modulator width W, the distance A of the mirror 130 from the second side 112 of the modulator, and known values ​​for the first angle α and the second angle β, and B = (T2-T1)v C = B / (tan α + tan β) x=A+WC y=T1v-Xtanα The XY location of the particle 115 can be determined using the following equation:

[0050] It should be understood that the above equations may vary depending on the definition of the X and Y directions, and may require the use of complements of the first angle α and the second angle β. This method is best seen in the system 100 configuration shown in Figures 2A-2H, but may also be applied to the system 100 configuration shown in Figures 1A-1H.

[0051] As an example, the width W of the modulator 110 is 131 mm, the velocity v is 1 m / s, the mirror 130 is disposed at a distance A of 10 mm from the second side 112 of the modulator 110, the first angle α is 20°, the second angle β is 20°, the time T1 is 77 ms, and the time T2 is 115 ms. The XY location of the particle 115 is as follows: B = (T2-T1)v = (117-77)(1) = 40 mm C=B / (tanα+tanβ)=40 / (tan20+tan20)=55mm x=A+WC=10+131-55=86mm y=T1v-Xtanα=(77)(1)-(86)tan20=46mm This can be calculated as approximately (86mm, 46mm).

[0052] 1A and 2A, the system 100 may further include an air knife 160. The air knife 160 may be configured to remove particles 115 from the surface 113 of the modulator 110. For example, the air knife 160 may blow air toward the surface 113 of the modulator 110 to remove foreign objects from the surface 113 of the modulator 110. The air knife 160 may be used to effectively remove foreign objects from the surface 113 of the modulator 110 while minimizing damage to the surface 113 of the modulator 110. Although the air knife 160 is used to clean the surface 113 of the modulator 110 in the description herein, other tools capable of removing liquids, solids, and / or liquid particles from the surface 113 of the modulator 110 may be used (e.g., wipers, hard brushes, soft brushes, cloths, etc.).

[0053] The air knife 160 can be configured to remove the particle 115 from the surface 113 of the modulator 110 after the XY location of the particle 115 has been determined (i.e., after FIGS. 1G and 2G). In this configuration, the system 100 can track the XY location of the particle so that a system level problem can be diagnosed and / or a second inspection process can be used to verify that the cleaning process has removed the particle 115 (i.e., inspect, then clean, inspect). Detection of the particle 115 in the second inspection process (i.e., after FIG. 3B) can indicate a defect on the surface 113 of the modulator 110 or a problem with the air knife 160.

[0054] The air knife 160 may be disposed on the first support structure 101 and the second support structure 102 of the system 100. For example, the air knife 160 may extend from the first support structure 101 to the second support structure 102. In this manner, the modulator 110 may pass under the air knife 160 as it is moved between the first support structure 101 and the second support structure 102 in the first direction.

[0055] According to the embodiment shown in FIG. 1A-FIG. 1H, an air knife 160 can be disposed between the laser source 120 and the laser sensor 140. For example, the air knife 160 can be disposed on the first support structure 101 and the second support structure 102 between the laser source 120 and the laser sensor 140. In this way, the modulator 110 can be passed under the air knife 160 after passing through the laser light 122 but before passing through the redirected laser light 124, as shown in FIG. 1E. This design can reduce the space required by the system 100 in the overall inspection system. However, it is better to set the air knife 160 to an OFF state to avoid removing the particle 115 from the surface 113 of the modulator 110 before the XY location of the particle 115 is determined. As shown in FIG. 1G and FIG. 1H, the air knife 160 can be set to an ON state to remove the particle 115 from the surface 113 of the modulator 110 after the XY location of the particle 115 is determined. After the XY location of the particle 115 has been determined, the modulator 110 may be moved in a second direction opposite the first direction to pass underneath the air knife 160 .

[0056] According to the embodiment shown in Figures 2A-2H and 3A-3B, the air knife 160 can be located downstream from the laser source 120 and the laser sensor 140. For example, the air knife 160 can be disposed on the first support structure 101 and the second support structure 102 downstream from the laser source 120 and the laser sensor 140. This allows the modulator 110 to pass under the air knife 160 after passing through the laser light 122 and the redirected laser light 124, as shown in Figures 3A-3B. Thus, the modulator 110 can be prevented from passing under the air knife 160 before the XY location of the particle 115 has been determined, as shown in Figure 2G. With such a design, it is not necessary to change the direction of movement of the modulator 110 during the cleaning process and / or toggling the air knife 160 on and off to prevent the particle 115 from being removed before the XY location of the particle 115 has been determined.

[0057] The air knife 160 may be located elsewhere in the system 100 depending on space requirements. The air knife 160 may also be positioned such that the modulator 110 can be moved in a direction other than the first and / or second direction to pass underneath the air knife 160.

[0058] In the disclosed system 100, the XY location of the particle 115 on the surface 113 of the modulator 110 can be determined using the output signal 145 of the laser light 122 reflected off of the mirror 130. By locating the particle 115, the cleaning process can be a closed loop that provides feedback to the disclosed system 100 to verify how well the modulator 110 is actually being cleaned and / or to diagnose system level problems.

[0059] Although this disclosure has been described with respect to a single particle 115 on the surface 113 of the modulator 110, the system 100 can be used with multiple particles 115. For example, the XY location of the particle 115 on the surface 113 of the modulator 110 can be determined and the detection process can be repeated after the modulator 110 has been passed under the air knife 160. If additional particles 115 are detected, the modulator 110 can be passed under the air knife 160 again and the detection process repeated until no particles 115 are found on the surface 113 of the modulator 110. The system 100 can also include multiple modulators 110 that can be individually passed through the laser light 122 for surface particle detection and under the air knife 160 for surface particle removal. By determining the XY location of the particle on each of the multiple individual modulators 110, system level problems can be diagnosed if there is a correlation between the particle locations on each of the multiple modulators.

[0060] Another embodiment of the present disclosure provides a method 200. As shown in Figure 4, the method 200 may include the following steps.

[0061] In step 210, the modulator is moved in a first direction. The modulator may be configured to detect defects in an electrical circuit. A possible modulator is the modulator 110 described above. The modulator moving in the first direction can be seen in sequence in Figures 1A-1F and 2A, 2C, 2E, and 2G.

[0062] In step 220, a laser light source disposed adjacent to a first side of the modulator emits laser light along a direction parallel to a surface of the modulator and at a first angle to the first direction toward a second side of the modulator, the laser light being capable of overlapping the surface of the modulator.

[0063] In step 230, at least one mirror disposed adjacent a second side of the modulator opposite the first side redirects the laser light toward the first side of the modulator at a second angle relative to the first direction.

[0064] In step 240, a first intensity change of the laser light received from the laser light source is detected by a laser sensor disposed adjacent to a first side of the modulator when a particle on the modulator surface passes through the laser light emitted by the laser light source. The passage of a particle on the modulator surface through the laser light emitted by the laser light source can be seen in Figures 1C and 2C.

[0065] In step 250, a laser sensor detects a second change in intensity of the laser light received from the laser source as the particle on the modulator surface passes through the laser light redirected by the at least one mirror, as can be seen in Figures 1F and 2E.

[0066] In step 260, a processor determines an XY location of the particle based on the first intensity change and the second intensity change. For example, the processor may receive an output signal from a laser sensor and determine an XY location of the particle based on the time of the first intensity change and the second intensity change in the output signal.

[0067] According to an embodiment of the present disclosure, step 260 may include the following steps (as shown in FIG. 5):

[0068] In step 261, the origin is defined as the first corner of the modulator that passes through the laser light emitted by the laser source. The XY location of the particle can be determined relative to the origin.

[0069] In step 262, a first distance between the laser source and the origin is determined at a time corresponding to the first intensity change. The first distance can be seen in FIG. 1C.

[0070] In step 263, a second distance between the laser sensor and the origin is determined at a time corresponding to the second intensity change. The second distance can be seen in FIG. 1F.

[0071] In step 264, an XY location of the particle is determined based on the first distance and the second distance. For example, the first distance and the second distance can be used to identify two lines that intersect at the XY location of the particle. The intersection point can be seen in FIG. 1G. In particular, the first distance and the second distance can be equivalently expressed as the y-intercepts of the two lines. The slopes of the two lines can be determined by the first and second angles of the laser light and the redirected laser light. The intersection point can be determined algebraically using an equation for the two lines.

[0072] According to an embodiment of the present disclosure, step 260 may include the following steps (as shown in FIG. 6):

[0073] In step 261, the origin is defined as the first corner of the modulator that passes through the laser light emitted by the laser source. The XY location of the particle can be determined relative to the origin.

[0074] In step 265, the distance traveled by the modulator along the first direction between the time corresponding to the first intensity change and the time corresponding to the second intensity change is determined, for example, by multiplying the difference between the time corresponding to the first intensity change and the time corresponding to the second intensity change by the velocity of the modulator to determine the distance.

[0075] In step 266, the XY location of the particle is determined based on the distance traveled by the modulator along the first direction between the times corresponding to the first intensity change and the second intensity change. For example, the calculated distance can be used along with known values ​​for the width of the modulator, the distance of the mirror from the second side of the modulator, the first angle, and the second angle to calculate the XY location of the particle. These parameters can be seen in Figures 2A and 2E.

[0076] According to certain embodiments of the present disclosure, the method 200 may further include step 270 of removing particles from the modulator surface by passing the modulator through an air knife, which may be performed after the XY location of the particle has been determined in step 260.

[0077] In the configuration shown in Figures 1A-1H, an air knife is disposed between the laser source and the laser sensor. Thus, by configuring the air knife to be off when moving the modulator in a first direction, it is possible to avoid removing the particle before the XY location of the particle has been determined. Therefore, the method 200 may further include moving the modulator in a second direction opposite to the first direction. This can be seen in Figures 1G and 1H. By configuring the air knife to be on when moving the modulator in the second direction, it is possible to remove the particle from the modulator surface after the XY location of the particle has been determined.

[0078] In the configuration shown in Figures 2A-2H, the air knife is located downstream from the laser source and the laser sensor. Thus, as shown in Figure 3A, the air knife can be configured to turn on when the modulator is moved in a first direction, thereby removing particles from the modulator surface. After the XY location of the particle has been determined and the particle has been removed from the modulator surface, the method 200 can further include moving the modulator in a second direction, as can be seen in Figure 3B. Moving the modulator in the second direction can cause the modulator to be passed back through the laser light. This can be used to verify that the air knife has removed particles from the modulator surface, or to diagnose system level problems.

[0079] In the disclosed method 200, the output signal of the mirror reflected laser light can be used to determine the XY location of the particle on the modulator surface. Locating the particle allows the cleaning process to be a closed loop where feedback is provided to the system to verify how well the modulator is actually being cleaned and / or to diagnose system level problems.

[0080] Although the present disclosure has been described in connection with one or more specific embodiments, it will be understood that other embodiments of the present disclosure may be made without departing from the scope of the present disclosure, that is, the present disclosure is to be considered limited only by the appended claims and the reasonable interpretation thereof.

Claims

1. 1. A system comprising: a modulator configured to detect defects in an electrical circuit, the modulator being movable in a first direction; a laser light source disposed adjacent to a first side of the modulator, the laser light source configured to emit laser light along a direction parallel to a surface of the modulator and at a first angle to the first direction toward a second side of the modulator, the laser light overlapping the modulator surface; at least one mirror disposed adjacent to a second side of the modulator opposite the first side, the at least one mirror configured to redirect the laser light toward the first side of the modulator at a second angle relative to the first direction; a laser sensor disposed proximate to the first side of the modulator; detecting a first change in intensity of the laser light received from the laser light source when a particle on the modulator surface passes through the laser light emitted by the laser light source; and detecting a second change in intensity of the laser light redirected by the at least one mirror and received from the laser light source when the particle on the modulator surface passes through the laser light redirected by the at least one mirror; A laser sensor configured as: a processor configured to determine an XY location of the particle based on the first intensity variation and the second intensity variation; A system comprising:

2. 10. The system of claim 1, further comprising an air knife configured to remove the particle from the modulator surface after the XY location of the particle has been determined.

3. 3. The system of claim 2, wherein the air knife is disposed between the laser source and the laser sensor.

4. 3. The system of claim 2, wherein the air knife is disposed downstream from the laser source and the laser sensor.

5. 2. The system of claim 1, wherein the first angle and the second angle are between 0 degrees and 90 degrees.

6. 2. The system of claim 1, wherein the at least one mirror comprises a pair of mirrors disposed at a symmetric angle with respect to the first direction.

7. 2. The system of claim 1, wherein the at least one mirror comprises a mirror oriented parallel to the first direction.

8. 2. The system of claim 1, wherein the XY location of the particle is determined relative to an origin defined by a corner of the modulator that passes first through the laser light emitted from the laser light source.

9. 9. The system of claim 8, wherein the XY location of the particle is determined based on a first distance between the laser light source and the origin determined at a time corresponding to the first intensity change and a second distance between the laser sensor and the origin determined at a time corresponding to the second intensity change.

10. 9. The system of claim 8, wherein the XY location of the particle is determined based on a difference between a time corresponding to the first intensity change and a time corresponding to the second intensity change.

11. 2. The system of claim 1, wherein the XY location of the particle is determined based on the first angle and / or the second angle.

12. 10. The system of claim 1, wherein the modulator is moved at a constant speed.

13. 1. A method comprising: moving a modulator in a first direction, the modulator being configured to detect defects in the electrical circuit; a laser light source disposed adjacent to a first side of the modulator, emitting laser light along a direction parallel to a surface of the modulator and at a first angle to the first direction toward a second side of the modulator, the laser light overlapping the modulator surface; redirecting the laser light toward the first side of the modulator at a second angle relative to the first direction by at least one mirror disposed adjacent to a second side of the modulator opposite the first side; detecting a first intensity change of the laser light received from the laser light source by a laser sensor disposed adjacent to a first side of the modulator when a particle on a surface of the modulator passes through the laser light emitted by the laser light source; detecting, by the laser sensor, a second change in intensity of the laser light redirected by the at least one mirror and received from the laser light source as the particle on the modulator surface passes through the laser light redirected by the at least one mirror; determining, with a processor, an XY location of the particle based on the first intensity variation and the second intensity variation; method.

14. 14. The method of claim 13, further comprising removing the particles from the modulator surface by passing the modulator through an air knife.

15. 15. The method of claim 14, wherein the air knife is disposed between the laser sensors and configured to be off when the modulator is moved in the first direction.

16. 16. The method of claim 15, further comprising moving the modulator in a second direction opposite to the first direction, the air knife being configured to be on when moving the modulator in the second direction.

17. 15. The method of claim 14, wherein the air knife is positioned downstream from the laser source and the laser sensor, and the air knife is configured to be on when the modulator is moved in the first direction.

18. 14. The method of claim 13, further comprising: determining an origin at a corner of the modulator that passes first through the laser light emitted from the laser light source; and determining the XY location of the particle with reference to the origin.

19. 20. The method of claim 18, wherein determining, by the processor, the XY location of the particle based on the first intensity change and the second intensity change comprises: determining a first distance between the laser light source and the origin at a time corresponding to the first intensity change; determining a second distance between the laser sensor and the origin at a time corresponding to the second intensity change; and determining the XY location of the particle based on the first distance and the second distance; method.

20. 20. The method of claim 18, wherein determining, by the processor, the XY location of the particle based on the first intensity change and the second intensity change comprises: determining a distance traveled by the modulator along the first direction between a time corresponding to the first intensity change and a time corresponding to the second intensity change; and determining the XY location of the particle based on the distance traveled by the modulator along the first direction between the time corresponding to the first intensity change and the time corresponding to the second intensity change. method.

Images