Photoelectric detection device and optical inspection device

Abstract

One embodiment of this application provides a photoelectric detection device and an optical detection device. The photoelectric detection device includes a beam splitting component and a sensor component. The beam splitting component is used to split a continuous first optical signal into multiple second optical signals at different spatial locations. The sensor component is used to receive the multiple second optical signals. The sensor component includes multiple sensors, including single-pixel sensors. By splitting the continuous first optical signal into multiple smaller discrete second optical signals by the beam splitting component, the photosensitive area corresponding to each sensor on the sample is further reduced. The smaller photosensitive area helps to further reduce the haze noise on a single sensor, thereby reducing the noise on a single sensor while keeping the original first optical signal unchanged, and improving the signal-to-noise ratio of the photoelectric detection device.

Description

Technical Field

[0001] This disclosure relates to the field of photoelectric detection technology, and in particular, to a photoelectric detection device and an optical detection device. Background Technology

[0002] The advent of photodetectors has revolutionized human perception of light, laying the foundational sensory foundation for modern information technology and scientific observation. Photodetectors utilize the photoelectric effect to convert light signals (photon energy) into electrical signals (current or voltage), enabling light to be quantified, stored, and visualized. This transforms fleeting moments of light and shadow into calculable and transmittable digital information.

[0003] In particular, the advent of photomultiplier tubes (PMTs) and avalanche photodiodes (APDs) has greatly advanced the field of science and technology for detecting extremely weak light signals. First, their extremely high sensitivity and gain to light signals allow for the detection of very weak light signals (e.g., distant starlight, biological autofluorescence in fluorescence microscopy, lidar echoes, and extremely weak detection signals), even down to the single-photon level. Second, their extremely fast response speed to light signals (especially PMTs, reaching nanosecond or even picosecond levels) makes the measurement and detection of ultrafast optical phenomena (such as fluorescence lifetime and laser pulses) possible.

[0004] However, due to their extremely high sensitivity and response speed, PMTs and APDs are very complex in terms of structure and manufacturing process. The complex structure integrated into each pixel occupies a large area, which reduces the effective sensitivity. Therefore, even if current photodetectors arrange multiple PMT or APD units in an array, the total number of pixels (i.e., the number of detection units in space) is still very small. This low number of pixels reduces the spatial positioning accuracy and imaging quality during the detection process. Summary of the Invention

[0005] In view of this, the present disclosure provides a photoelectric detection device, which aims to solve the problem that current photoelectric detection devices are unable to simultaneously achieve high sensitivity, fast response speed and high spatial resolution.

[0006] In a first aspect, one embodiment of this disclosure provides a photoelectric detection device for an optical detection apparatus, comprising a beam splitting component and a sensor component. The beam splitting component is used to split a continuous first optical signal into multiple second optical signals, the multiple second optical signals being located at different spatial positions. The sensor component is used to receive the multiple second optical signals. The sensor component includes multiple sensors, including single-pixel sensors.

[0007] Secondly, one embodiment of this disclosure provides an optical inspection apparatus for inspecting wafers, comprising the aforementioned photoelectric detection device, light source, and beam collecting assembly. The light source is used to illuminate the wafer surface to generate a first light signal, and the beam collecting assembly is used to receive the first light signal and guide it to converge to the photoelectric detection device. The photoelectric detection device is located at the focal point of the telescope in the beam collecting assembly to receive the first light signal.

[0008] Since each sensor receives a portion of the continuous first optical signal, it is equivalent to further reducing the size of the first optical signal (i.e., the laser spot) on the wafer surface, which helps reduce wafer noise. For the sensors, since the first optical signal is divided into multiple smaller second optical signals, the photosensitive area of ​​each sensor on the sample is further reduced. The smaller photosensitive area helps to further reduce the haze noise on individual sensors, thereby greatly reducing the sensor noise while keeping the original first optical signal unchanged. This increases the ratio of the first optical signal to the wafer surface noise, thus improving the signal-to-noise ratio of the photoelectric detection device.

[0009] Furthermore, the multiple smaller second optical signals, after being segmented, are received by multiple sensors with fewer pixels and smaller photosensitive areas. This effectively reduces the pixel size of the sensors on the wafer, thereby improving spatial resolution. Moreover, this implementation method is simple to manufacture, reducing processing costs. Thus, it ensures both high detection sensitivity and fast response speed, while also improving the signal-to-noise ratio and spatial resolution of the photoelectric detection device, ultimately enhancing spatial positioning accuracy and imaging quality. Attached Figure Description

[0010] It should be understood that the following figures only illustrate certain embodiments of this disclosure and should not be construed as limiting the scope.

[0011] It should be understood that the same or similar reference numerals are used in the accompanying drawings to denote the same or similar elements.

[0012] It should be understood that the accompanying drawings are only schematic, and the dimensions and scales of the elements in the drawings are not necessarily precise.

[0013] Figure 1 This is one of the structural schematic diagrams of a photoelectric detection device provided in an embodiment of this disclosure.

[0014] Figure 2 A schematic diagram of the structure of a photoelectric detection device provided for current technology.

[0015] Figure 3 This is a second schematic diagram of the structure of a photoelectric detection device provided in an embodiment of this disclosure.

[0016] Figure 4 This is the third schematic diagram of the structure of a photoelectric detection device provided in an embodiment of this disclosure.

[0017] Figure 5 This is the fourth schematic diagram of the structure of a photoelectric detection device provided in an embodiment of this disclosure.

[0018] Figure 6 The fifth schematic diagram of the structure of the photoelectric detection device provided in one embodiment of this disclosure.

[0019] Figure 7 This is the sixth schematic diagram of the structure of a photoelectric detection device provided in an embodiment of this disclosure.

[0020] Figure 8 This is the seventh schematic diagram of the structure of a photoelectric detection device provided in an embodiment of this disclosure.

[0021] Figure 9 This is a schematic diagram of the structure of a cylindrical mirror array provided in an embodiment of the present disclosure.

[0022] Figure 10 This is the eighth schematic diagram of the structure of a photoelectric detection device provided in an embodiment of this disclosure.

[0023] Figure 11 This is a schematic diagram of the structure of an optical detection device provided in an embodiment of the present disclosure.

[0024] Figure 12 This is a schematic diagram of the structure of a photoelectric detection device provided in another embodiment of the present disclosure.

[0025] Figure 13 This is a schematic diagram of the structure of a photoelectric detection device provided in another embodiment of the present disclosure.

[0026] Figure 14 This is a schematic diagram of the structure of a photoelectric detection device provided in another embodiment of the present disclosure.

[0027] Figure label: Optical inspection device 200; Light source 110; beam collecting assembly 120; photoelectric detection device 100; objective lens 121; tube lens 122; Beam splitter 10; microlens array 11; microlens 113; plano-convex lens 111; cylindrical lens 1111; cylindrical lens array 1110; Sensor assembly 20; original sensor assembly 20'; sensor 21; pixel unit 201; Optical path adjustment assembly 30; reflector assembly 31; reflector 311; steering mirror 313; Converging lens assembly 40; Converging lens 41; First optical signal S1; second optical signal S2. Detailed Implementation

[0028] The embodiments of this disclosure are described below with reference to the accompanying drawings. It should be understood that there are many ways to implement this disclosure, and it should not be construed as being limited to the embodiments set forth herein. The embodiments set forth herein are only for a more thorough and clear understanding of this disclosure.

[0029] Inspection technologies, especially optical inspection technologies, are integrated into every step of the semiconductor manufacturing process. Optical inspection technologies can capture nanometer- and micrometer-level defects on the surface of products under test (such as wafers) in a timely manner, providing guidance for process iteration and yield improvement. As the process node shrinks by a few nanometers, the size of the particles to be inspected also shrinks, which makes the weak light signals drowned out by noise and difficult to detect accurately. This is the core challenge that currently determines the sensitivity of photoelectric detection devices.

[0030] Among the many optical inspection methods, laser scanning is relatively mature. It uses an illumination system to focus one or more laser beams into a micron-sized spot and scans the wafer point by point. Then, the collection system simultaneously captures the scattered, reflected, or interference light signals caused by defects and focuses them onto a highly sensitive photoelectric sensor. Finally, the algorithm separates the weak defect signals from the noise and obtains relevant parameters such as defects on the surface of the product under test, thereby completing the inspection.

[0031] However, in dark-field laser scanning scenarios, the biggest noise source is stray light generated on the wafer surface itself—the so-called "wafer noise." However, wafer noise cannot be compensated for simply by increasing laser power. Reducing wafer noise is tantamount to making defects appear brighter in the dark. Common methods for reducing wafer noise include: 1. A single photoelectric sensor (such as a photomultiplier tube (PMT) or an avalanche photodiode (APD)) can be used for detection to reduce wafer noise by shrinking the size of the laser spot on the wafer surface. Although this method is low-cost and less technically complex, its effect on suppressing wafer noise is limited, and it cannot significantly improve the detection sensitivity and the signal-to-noise ratio of the detector.

[0032] 2. Linear array or area sensors (such as charge-coupled device (CCD) cameras or complementary metal-oxide-semiconductor (CMOS) cameras) can be used instead of traditional single sensors to evenly distribute wafer noise across each pixel of the array sensor, thus suppressing wafer noise. Although this method is more effective at suppressing "wafer noise" than the first method, CCD / CMOS array sensors introduce additional electrical noise, and the readout speed is usually limited (typically on the order of 100kHz-1M per line). Other technical designs are needed to compensate for these shortcomings, resulting in higher technical complexity and cost.

[0033] Therefore, current photoelectric detection devices struggle to simultaneously achieve extremely high response speed, gain, and high resolution when detecting extremely weak light signals, in order to meet the increasingly stringent detection requirements of advanced manufacturing processes.

[0034] To overcome the above problems, refer to Figures 1 to 14 This application provides a photoelectric detection device 100 and an optical detection device 200 having the same, for detecting extremely weak light signals to be detected (such as scattered light signals, reflected light signals, transmitted light signals, interference light signals, etc.), thereby detecting defects and other related parameters of the product under test (such as a wafer).

[0035] refer to Figure 1 The photoelectric detection device 100 may include a beam splitting component 10 and a sensor component 20. The beam splitting component 10 can be used to split a continuous first optical signal S1 (i.e., the optical signal to be detected, such as a scattered light signal, a reflected light signal, or an interference light signal) into multiple second optical signals S2. The first optical signal S1 is split into multiple discrete second optical signals S2 after passing through the beam splitting component 10. The second optical signals S2 and the first optical signal S1 have the same frequency and other properties, but the second optical signal S2 has fewer photons (i.e., less light energy) compared to the first optical signal S1. For example, the second optical signal S2 can be 1 / 2, 1 / 3, 1 / 4, 1 / 5, or 1 / 6 of the first optical signal S1. It does not have to be uniformly divided; the second optical signal S2 only needs to be a part of the first optical signal S1, and no specific limitation is made here. Furthermore, the multiple second optical signals are located at different spatial positions, so that the second optical signals at different spatial positions can be received by sensors at corresponding positions. For example, different spatial positions can include different directions, or different positions within the same direction, and no specific limitation is made here.

[0036] It should be noted that the beam splitter assembly can be a continuous structure, allowing for complete reception of the first optical signal without any undetected signals, thus ensuring the complete detection of the first optical signal. For example, in wafer defect detection, the first optical signal comprises reflected light from different regions of the wafer, and each of the multiple split second optical signals corresponds to a defect in a different region of the wafer surface. Thus, a continuous beam splitter assembly facilitates complete reception and separation of the first optical signal, leading to more accurate acquisition of wafer surface defect results.

[0037] refer to Figure 1 The sensor assembly 20 may include multiple sensors 21, each of which includes a single-pixel sensor. Each sensor 21 can receive a second light signal S2. Thus, the sum of the second light signals S2 received by the pixel units 201 of all sensors 21 is equivalent to receiving the first light signal S1. It can be understood that the total photosensitive area of ​​the pixel units of the sensor 21 can be the same as the photosensitive area of ​​the pixel units of the original sensor assembly 20' that was originally used to directly receive the first light signal (e.g., ...). Figure 2 (As shown), of course, the pixel unit of a single-pixel sensor can also be larger than a single beam-splitting unit in the fractional-splitting assembly. In this way, the photosensitive area of ​​a single pixel unit in a single sensor 21 is reduced by a factor of two. A smaller photosensitive area helps to further reduce haze noise on a single sensor and improve the sensor's signal-to-noise ratio. Moreover, a sensor with a smaller photosensitive area also helps to further reduce manufacturing costs.

[0038] It can be understood that a beam splitter is used to spatially divide a continuous first optical signal into multiple discrete second optical signals, so that subsequent sensors can receive each beam of second optical signal accordingly. Beam splitters can be implemented in various ways, such as using multiple mirrors, multiple lenses, or gratings. Each mirror or lens can correspond to a beam splitting unit in the beam splitter, so that the continuous first optical signal is divided into multiple discrete second optical signals.

[0039] In this way, since each sensor receives a portion of the first optical signal, it is equivalent to further reducing the size of the first optical signal (i.e., the laser spot) on the wafer surface, which helps to reduce wafer noise. For the sensor, since the first optical signal is divided into multiple smaller second optical signals, the photosensitive area of ​​the sensor can be further reduced. The smaller photosensitive area helps to further reduce the haze noise on a single sensor, so that the noise of the sensor is greatly reduced while the original first optical signal remains unchanged. This increases the ratio of the first optical signal to the wafer surface noise, thereby improving the signal-to-noise ratio of the photoelectric detection device.

[0040] Furthermore, because the first optical signal is segmented, the resulting multiple smaller second optical signals are received by multiple sensors with fewer pixels and smaller photosensitive areas. This effectively reduces the equivalent pixel size of the sensor on the wafer, thereby improving spatial resolution. Moreover, this implementation method is simple to manufacture, reducing processing costs. Thus, it ensures both high detection sensitivity and fast response speed, while also improving the signal-to-noise ratio and spatial resolution of the photoelectric detection device, ultimately enhancing spatial positioning accuracy and imaging quality.

[0041] It should be noted that sensors with fewer pixels and smaller photosensitive areas can be single-pixel sensors, such as single-pixel PMTs or single-pixel APDs. Alternatively, they can be PMTs or APDs with fewer pixels. In this case, different pixel units correspond to different second light signals to obtain different detection results (e.g., detecting defects at different locations on a wafer). Furthermore, since a single-pixel sensor has only one pixel unit, the position of the second light signal simply corresponds to the position of each single-pixel sensor. Of course, sensor assemblies can also include multi-pixel sensors, such as 16-pixel sensors or 32-pixel sensors. Different pixel units are used to receive different second light signals to obtain different detection results on the wafer surface. It is important to note that because the pixel units in a multi-pixel sensor have a fixed periodic arrangement, the second light signal must correspond to the pixel unit at the corresponding position (see reference). Figures 12 to 14 ).

[0042] In one example, reference Figure 3 and Figure 10 The sensor assembly 20 provided in this application may include a single-pixel sensor, and the single-pixel sensor corresponds to a beam splitting unit (such as microlens 113) in the beam splitting assembly of the microlens array 11.

[0043] It's also important to note that the equivalent pixel size can be understood as the actual physical size of one physical pixel on the sensor corresponding to the surface of the wafer. It effectively reflects the resolution and measurement accuracy of the photoelectric detection device (or sensor). A smaller equivalent pixel size means stronger resolution and higher measurement accuracy, meaning it can "see" even smaller details. (Reference) Figure 3 and Figure 4 The beam separation component 10 may include a microlens array 11, which may include a plurality of microlenses 113, each microlens 113 corresponding to a pixel unit of the sensor 21.

[0044] Preferably, the beam splitting component may include a microlens array 11, which may include multiple microlenses 113. The microlens period refers to the distance from the center of one unit to the center of an adjacent identical unit in a periodically arranged array of microlenses. The microlens arrangement period can be flexibly designed according to requirements. The physical size of a pixel unit of the sensor refers to the physical outline size of a single pixel unit itself, such as its diameter, side length, or the diagonal length of its photosensitive area; here, only the physical concept of physical size is described. Thus, the sensor can include either a single-pixel sensor or a multi-pixel sensor, as long as the physical size of the pixel unit is equal to the arrangement period of the microlens array.

[0045] It is understandable that since the microlens 113 is essentially a two-dimensional planar optical element composed of a large number of micron-sized lenses arranged in a certain manner, when the first light signal S1 passes through the microlens array 11, different parts of the light signal in the first light signal S1 will illuminate different microlenses. Each part of the light signal will illuminate an independent microlens and be refracted to form a second light signal S2. Moreover, multiple second light signals S2 can also be arranged in a certain manner and separated from each other.

[0046] refer to Figure 4 Each microlens 113 may include a plano-convex lens 111. Since one side of the plano-convex lens 111 is a plane and the other side is a sphere, the first light signal S1 incident with parallel light is converged and split into multiple second light signals S2 (i.e. discrete, regularly arranged dot matrix). The second light signals S2 can be independent small blocks to achieve two-dimensional beam splitting.

[0047] For example, if the first optical signal S1 is a circular laser (i.e., circularly polarized light), and the microlenses 113 are arranged perpendicular to the incident direction of the first optical signal S1, then the light spot of the second optical signal S2 received by the sensor may be a circular spot, an elliptical spot, or a straight line. Different types of microlenses allow the sensor to receive light spots of different shapes. As another example, if the first optical signal S1 is an adjusted strip laser, and the microlenses 113 are arranged perpendicular to the incident direction of the first optical signal S1, then the light spot of the second optical signal S2 received by the sensor may be multiple thin lines or still be strip-shaped.

[0048] refer to Figure 5Each plano-convex lens 111 may include a cylindrical mirror 1111. Thus, a microlens array (hereinafter referred to as cylindrical mirror array 1110) composed of multiple cylindrical mirrors 1111 splits the incident first light signal S1 and outputs a striped second light signal S2 to achieve one-dimensional beam splitting. The size of this cylindrical mirror array can be very small, and the resulting striped multiple light signals are received by different sensors after being separated, so that different sensors receive different light signals, which is beneficial to further simplify the structure of the photoelectric detection device.

[0049] In another example, the first light signal S1 may include multiple elongated light signals. After the first light signal S1 is perpendicularly incident on multiple (e.g., two) cylindrical mirror arrays 1110, different sensors 21 receive second light signals S2 at different spatial positions. It can be understood that the elongated light signals may include a long side and a short side, with the short side pointing in the direction of the light signal's movement. Typically, the short side contains one pixel, while the long side is stitched together to form a multi-pixel structure for spatial downsampling. Thus, only a corresponding number of single-pixel sensors (e.g., single-pixel PMTs) need to be set according to the number of pixels, and the cylindrical mirror array 1110 only needs to focus in the long side direction, without needing to converge into a dot matrix in two directions, to acquire the first light signal S1. Moreover, since each light signal illuminates a corresponding cylindrical mirror 1111 and is received by a corresponding sensor 21, this not only simplifies manufacturing but also reduces costs.

[0050] It should be noted that both sides of the cylindrical mirror 1111 can be coated with an anti-reflection film (such as an AR film) to ensure that the reflectivity is no greater than 0.4%, thereby further reducing the loss of the first optical signal S1. Furthermore, the material of the cylindrical mirror 1111 can be selected according to different detection needs, transmitting different wavelength ranges and processing methods. For example, when the cylindrical mirror array 1110 is used for semiconductor detection, it needs to transmit light signals in the ultraviolet band (such as 193nm, 245nm, 266nm, 355nm), and the material of the cylindrical mirror 1111 can be fused silica, with photolithography being the preferred processing method. If the cylindrical mirror array 1110 needs to transmit light signals in the band above 400nm, the material of the cylindrical mirror 1111 can also be other glass materials or transparent plastic materials, and the processing method can also be injection molding or nanoimprinting.

[0051] refer to Figure 4Since the spacing d between the microlenses 113 affects the pixel size of the beam separation component 10, the spacing d between the microlenses (such as plano-convex lenses 111) must satisfy: 0.5mm ≤ d ≤ 10mm. This not only facilitates the integration and miniaturization of the photoelectric detection device 100, but also helps to further reduce the manufacturing difficulty, allowing the corresponding sensors 21 to be fixed in adjacent positions. For example, each microlens is a cylindrical mirror, and the spacing d between each cylindrical mirror 1111 in the cylindrical mirror array 1110 can be: 0.5mm, 1mm, 2mm, 2.5mm, 3mm, 4mm, 5mm, 6mm, 6.5mm, 8mm, 9mm, 10mm, etc. The size of the spacing d between the cylindrical mirrors can also be flexibly designed according to the size of the photoelectric detection device. It is understandable that if the spacing between the microlenses is too small, the manufacturing difficulty and cost of the microlenses will increase significantly; if the spacing between the microlenses is too large, it is not conducive to integration and miniaturization. For example, a single-pixel sensor (PMT) has a size of 4mm and can receive incident light spots with a maximum length of 8mm.

[0052] It is important to understand that the focal length f of the microlens 113 can satisfy: 5mm ≤ f ≤ 100mm. By adjusting the focal length of each microlens 113 in the microlens array 11, the first light signal S1 incident at different angles can be received by the corresponding sensor pixel unit 201 after passing through the microlens 113, thereby avoiding crosstalk between light signals. In other words, the larger the angle of the first light signal, the smaller the required focal length. Different angles are adjusted according to different incident angles to ensure that the corresponding sensor 21 receives the corresponding second light signal. For example, when each microlens is a cylindrical mirror 1111, the focal length f of each cylindrical mirror 1111 can be 5mm, 10mm, 30mm, 45mm, 60mm, 75mm, 90mm, 100mm, etc. The focal length f can be flexibly designed according to different incident angles, and no specific limitation is made here.

[0053] refer to Figures 5 to 8 The photoelectric detection device 100 may further include an optical path adjustment component 30, which is used to adjust the transmission direction of each second optical signal S2 so that each second optical signal S2 is received by the corresponding sensor 21 after passing through the optical path adjustment component 30. That is, after the first optical signal S1 passes through the beam splitting component 10, it is divided into multiple second optical signals S2. Each second optical signal S2 then passes through the optical path adjustment component 30 to make the transmission direction of the multiple second optical signals S2 more divergent, thereby helping to further reduce crosstalk between optical signals.

[0054] In one example, reference Figures 6 to 12The optical path adjustment component 30 may include a reflector component 31, which may include multiple reflectors 311. Each reflector 311 corresponds to a pixel unit of the sensor 21, so that the second optical signal S2 is received by the corresponding pixel unit of the sensor 21 after passing through the reflector 311. Different second optical signals S2 pass through different reflectors 311 and are received by different pixel units, further avoiding crosstalk between optical signals, thereby improving detection accuracy. For example, when the sensor 21 is a single-pixel sensor, each reflector corresponds to a single-pixel sensor and a microlens 113.

[0055] It should be noted that when the number of reflectors 311 is equal to the number of cylindrical mirrors 1111, each beam of second light signal S2 is received by the corresponding pixel unit 201 after passing through the cylindrical mirror 1111 and the reflector 311 (see reference). Figure 7 , Figure 12 and Figure 13 When the number of reflectors 311 is less than the number of cylindrical mirrors 1111, a portion of the second optical signal S2 is received by the corresponding portion of pixel units 201 after passing through the cylindrical mirrors 1111 and 311, while another portion of the second optical signal is directly received by the other portion of pixel units 201 after passing through the cylindrical mirrors 1111 (see reference). Figure 8 , Figure 10 and Figure 14 Furthermore, when the sensor is a single-pixel sensor, each single-pixel sensor corresponds to one reflector and one beam of second light signal; when the sensor is a multi-pixel sensor, each sensor can correspond to multiple reflectors and multiple beams of second light signals.

[0056] In one example, reference Figure 5 Some of the second light signals S2 are received by the pixel unit 201 of the corresponding sensor 21 after passing through the reflector 311, while the other second light signals S2 are directly received by the pixel unit 201 of the corresponding sensor 21. With this design, it is not necessary to set a reflector 311 for each pixel unit 201 of the sensor 21, which helps to further reduce manufacturing difficulty and manufacturing cost.

[0057] refer to Figures 5 to 8 The reflector 311 can be located at the focal point of the cylindrical mirror 1111, so that the second optical signal S2 passes through the cylindrical mirror 1111 and the reflector 311 successively before being received by the corresponding pixel unit of the sensor 21. It can be understood that since the light spot is smallest at the focal point, the reflector 311 located at the focal point can directly reflect the light spot to the pixel unit of the sensor 21, which helps to further improve the detection accuracy. Of course, the sensor can be placed directly at the focal point of the cylindrical mirror; specific details will not be elaborated further.

[0058] It should be noted that the reference Figure 9 The product of the incident angle α of the first optical signal S1 and the focal length f of each cylindrical mirror is less than the size L (i.e., the aperture) of each reflector, i.e., α x f < L. For example, the first optical signal S1 is perpendicularly incident on cylindrical mirror 1111, i.e., the incident angle α = Π / 2, the focal length of the cylindrical mirror f = 10 mm, and the size L of the reflector > 5Π, to ensure that the first optical signal S1 can be received by the corresponding sensor after passing through the cylindrical mirror array 1110. For example, for cylindrical mirror 1111 with a reflector size L = 3.8 mm and a focal length f = 10 mm, the first optical signal S1 can be perpendicularly incident on the photoelectric detection device, and the divergence angle β (the angle between the incident ray and the normal) needs to be less than 10.75°. If the divergence angle of the first optical signal S1 is greater than 10.75°, the second optical signal S2 may be received by adjacent sensors, thereby generating crosstalk and affecting the accuracy of detection. Preferably, the first optical signal S1 is perpendicularly incident on the cylindrical mirror array so that the second optical signal can be received by the smallest possible size of the reflector.

[0059] It should be noted that the size and spacing of the reflectors 311 can be adjusted according to the pixel size and the focal length requirements of the front cylindrical mirror array. The total size of the reflector assembly is the sum of the sizes of the multiple reflectors 311, which can also be understood as the product of the number of periods and the size L of a single reflector. (Reference) Figure 9 The microlens array 11 may include four cylindrical mirrors to form a microlens array. The size of the reflector 311 can be 3.8mm x 3.8mm, and there is a 0.2mm gap between each reflector 311. Thus, the size of the entire reflector assembly is 16mm, consistent with the gap of the cylindrical mirror array 1110. A reflective film is coated on the reflective surface, and the reflectivity can be greater than 90%. Preferably, the reflectivity can be greater than 98%, and the reflective film can be flexibly designed according to the selection of wavelength, which will not be described in detail here.

[0060] In another example, refer to Figure 12 The microlens array 11 may include 16 consecutively arranged cylindrical mirrors 1111 to split the first optical signal S1 into 16 beams of second optical signals S2. The reflector assembly 31 may include 16 reflectors 311, each reflector 311 corresponding to one cylindrical mirror 1111, so that each beam of second optical signal S2 passes through one reflector 311. The sensor assembly 20 may include two eight-pixel sensors, each multi-pixel sensor having eight pixel units, each pixel unit 201 corresponding to receiving one beam of second optical signal S2. In this way, a beam of first optical signal S1 is spatially split and received by pixel units at different spatial locations, thereby helping to improve the spatial resolution and signal-to-noise ratio of the photoelectric detection device.

[0061] In another example, the microlens array 11 may include 16 consecutively arranged cylindrical mirrors 1111 to split the first optical signal S1 into 16 beams of second optical signals S2. The mirror assembly 31 may include 8 spaced-apart mirrors 311 (i.e., there is no mirror between two mirrors, allowing the second optical signal to pass through directly, see reference). Figure 10 The reflector 311 is positioned corresponding to a cylindrical mirror 1111, and the size of the reflector is set to correspond to the size of the cylindrical mirror, so that eight beams of second light signals S2 pass through the reflector 311, while the other eight beams of second light signals S2 are directly transmitted. The sensor assembly 20 may include two eight-pixel sensors, each with eight pixel units to receive each beam of second light signal S2. Thus, it is not necessary to have a reflector 311 corresponding to each pixel unit of the sensor 21, which helps to further reduce manufacturing difficulty and cost.

[0062] In another example, refer to Figure 14 The microlens array 11 may include 16 consecutively arranged cylindrical mirrors 1111 to split the first optical signal S1 into 16 beams of second optical signals S2. The reflector assembly 31 may include 10 reflectors 311, corresponding to the 10 cylindrical mirrors 1111 arranged on the outer side. The reflectors 311 on both sides may be hollowed out to allow the second optical signal S2 in the middle to be directly transmitted. Each reflector 311 corresponds to one cylindrical mirror 1111, so that the 10 beams of second optical signals S2 on the outer side pass through one reflector 311 respectively, and the 6 beams of second optical signals S2 in the middle are directly transmitted. The sensor assembly 20 may include three six-pixel sensors. Each multi-pixel sensor is provided with 6 pixel units 201. The sensors on both sides have only 5 pixel units 201 receiving the corresponding second optical signal S2, and the sensor in the middle receives the 6 transmitted beams of second optical signals S2. Of course, the number of pixel units 201 provided on the multi-pixel sensor can be selected according to actual needs; this is just an illustrative example. In addition, the first optical signal S1 can be divided without omission, the size of the cylindrical mirror can be flexibly selected according to the number of divisions required, and the number of multi-pixel sensors and the number of pixel units in each multi-pixel sensor can also be flexibly selected as needed.

[0063] Furthermore, the sensor assembly 20 can include sensors with different pixel units as needed. For example, the microlens array 11 may include 10 consecutively arranged cylindrical mirrors 1111, and the sensor assembly may include two single-pixel sensors and one eight-pixel sensor. Of course, the pixel units of the sensor need to be selected according to the actual situation, and no specific limitation is made here. Moreover, reflection and transmission can be designed separately and alternately to improve space utilization.

[0064] In one example, reference Figure 10The reflector 311 may include a 45-degree turning mirror 313. The addition of the turning mirror helps to reduce manufacturing difficulty and cost. In this way, the first optical signal S1 is split into two beams (three, four, five, six, seven or eight beams) of second optical signal S2 after passing through the microlens array 11 formed by two (or three, four, five, six, seven or eight) cylindrical mirrors. The transmission direction of part of the second optical signal S2 changes after passing through the turning mirror 313 so that it can be received by the pixel unit 201 of the corresponding sensor 21 (such as a single-pixel PMT). The other part of the second optical signal S2 is directly received by the pixel unit 201 of the corresponding sensor 21 (such as a single-pixel PMT).

[0065] It is understandable that the multiple steering mirrors 313 can be spaced about 0.2mm apart. In this way, the first optical signal S1 is focused after passing through the cylindrical mirror array 1110, which helps to prevent the second optical signal S2 from being incident on the 0.2mm interval, thereby avoiding the loss of optical signal.

[0066] refer to Figures 7 to 10 The photoelectric detection device 100 may further include a converging lens assembly 40, which may include multiple converging lenses 41. Each converging lens 41 may correspond to a pixel unit 201 of a sensor 21 to adjust the transmission direction of the second optical signal S2, so that the second optical signal S2 is received by the corresponding pixel unit 201 of the sensor 21 after passing through the reflector 311 and the converging lens 41. It can be understood that the first optical signal S1 is divided into multiple independent second optical signals S2 after passing through the cylindrical mirror array 1110. After passing through the reflector 311, the transmission direction of some of the second optical signals S2 changes. The second optical signals S2 with changed transmission direction can be received by the corresponding pixel unit 201 of the sensor 21 after passing through the converging lens 41 (such as a convex lens); the other part of the second optical signals S2 that do not pass through the reflector 311 and continue to transmit in the original transmission direction can be received by the corresponding pixel unit of the sensor 21 after passing through the converging lens 41 (such as a convex lens).

[0067] In this way, different converging lenses 41 and sensors 21 can be set for different second optical signals S2, so that each second optical signal S2 can be detected independently.

[0068] Furthermore, the second optical signal S2 can be collimated or focused after passing through the converging lens 41, thereby controlling the size of the light spot of the second optical signal S2 to further improve the detection accuracy.

[0069] In one example, sensor 21 can be a single-pixel photodetector (PMT). By setting a suitable converging lens 41, the spot size can reach the order of 1 mm to 10 mm. It should be noted that the number of pixels in a single-pixel sensor can be expanded from 2 to 5 or more. Preferably, the number of single-pixel photodetectors is 4-8. This is mainly due to the relatively large size of the single-pixel photodetector itself, thus limiting the number of sensors that can be integrated. Furthermore, signals from different pixels can be refracted by a mirror or directly received using transmission (i.e., without a mirror). By combining transmission and reflection, signals from different pixels can be introduced into single-pixel sensors at different locations, thereby achieving the function of extended beam splitting.

[0070] In another example, refer to Figure 13 The microlens array 11 may include 16 consecutively arranged cylindrical mirrors 1111 to split the first optical signal S1 into 16 beams of second optical signal S2. The reflector assembly 31 may include 16 reflectors 311, each reflector 311 corresponding to one cylindrical mirror 1111, so that each beam of second optical signal S2 passes through one reflector 311. The converging lens assembly 40 may include 16 converging lenses 41 (such as convex lenses), each converging lens 41 corresponding to one pixel unit 201 of the sensor 21, to adjust the transmission direction of the second optical signal S2 so that the second optical signal S2 passes through the reflector 311 and the converging lens 41 successively and is received by the corresponding pixel unit 201 of the sensor 21. The sensor assembly 20 may include two eight-pixel sensors, each multi-pixel sensor having eight pixel units, each pixel unit corresponding to receiving one beam of second optical signal S2. In this way, the first optical signal S1 is spatially split and collimated or converged by the converging lens 41. The addition of a converging lens helps control the size of the spot of the second optical signal S2, thereby helping to further improve the detection accuracy.

[0071] In another example, the microlens array 11 may include 16 consecutively arranged cylindrical mirrors 1111 to split the first optical signal S1 into 16 beams of second optical signals S2. The mirror assembly 31 may include 8 spaced-apart mirrors 311 (i.e., there is no mirror between two mirrors, allowing the second optical signal to pass through directly, see reference). Figure 10The reflector 311 is positioned to correspond to a cylindrical mirror 1111. The size of the reflector corresponds to the size of the cylindrical mirror, so that eight beams of second light signals S2 pass through the reflector 311, while another eight beams of second light signals S2 are directly transmitted. The converging lens assembly 40 may include 16 converging lenses 41 (such as convex lenses), each converging lens 41 corresponding to a pixel unit 201 of the sensor 21, to adjust the transmission direction of the second light signals S2. This ensures that eight beams of second light signals S2 pass through the reflector 311 and the converging lens 41 sequentially before being received by the corresponding pixel unit 201 of the sensor 21, while the other eight beams of second light signals pass directly through the converging lens 41 at the corresponding position before being received by the corresponding pixel unit 201 of the sensor 21. The sensor assembly 20 may include two eight-pixel sensors, each with eight pixel units to receive each beam of second light signal S2. This eliminates the need for a separate reflector 311 for each pixel unit of the sensor 21, further reducing manufacturing difficulty and cost.

[0072] The following example uses a photoelectric detection device 100 that includes a cylindrical mirror array (including 5 cylindrical mirrors), a first light signal S1 that is a scattered light signal and a long strip of light, and a sensor component 20 in the photoelectric detection device 100 that includes multiple single-pixel PMTs (see reference). Figure 10 This section describes the structure of the photoelectric detection device 100 and the detection process of the first optical signal S1.

[0073] After the first optical signal S1 is perpendicularly incident on the cylindrical mirror array 1110, it is split into five second optical signals S2. The second optical signal S2 located in the middle of the five second optical signals S2 passes directly through the converging lens 41 and is received by the single pixel PMT at the corresponding position. The converging lens 41 can be located at the focal point of the cylindrical mirror 1111, and the single pixel PMT can be located at the focal point of the converging lens 41.

[0074] Of the remaining four second light signals, the two outermost second light signals S2 pass through two correspondingly arranged steering mirrors 313, and are then transmitted perpendicularly to their respective single-pixel PMTs (i.e., sensor 21). Similarly, the remaining two second light signals S2 pass through two correspondingly arranged steering mirrors 313 to transmit to their respective single-pixel PMTs. Furthermore, the converging lens 41 is located at the focal point of the corresponding cylindrical mirror 1111, and the single-pixel PMT is located at the focal point of the converging lens 41.

[0075] It is understandable that the cylindrical mirror array 1110, the steering mirror 313, the converging lens 41, and the sensor 21 (such as a single-pixel PMT) mentioned above can all be fixed on a three-dimensional structural component. In addition, each sensor (such as a single-pixel PMT) can also include a data acquisition circuit board, and the sensor (such as a single-pixel PMT) can be fixed to the data acquisition circuit board through pins, which is beneficial to further improve the integration.

[0076] It should also be noted that the photoelectric detection device provided in this application is not only suitable for dark field detection environments (such as dark field laser scanning wafer detection), but can also be used in bright field detection environments.

[0077] Of course, sensor components can also include both single-pixel sensors and multi-pixel sensors, for example, Figure 12 The multi-pixel sensor can be replaced with multiple single-pixel sensors; no specific restrictions are made here.

[0078] refer to Figure 11 This application also provides an optical detection device 200 for detecting a wafer W, which may include the photodetector 100, light source 110, and beam collecting assembly 120 mentioned above. The light source 110 illuminates the surface of the wafer W to generate a first optical signal S1. The beam collecting assembly 120 receives the first optical signal S1 and guides it to converge to the photodetector 100, which is located at the focal point of the beam collecting assembly to receive the first optical signal S1. A beam splitting assembly 10 is located at the focal point of the beam collecting assembly in the optical detection device to ensure that optical signals from different locations on the wafer W are received by different microlens arrays 11 in the beam splitting assembly 10. Of course, the light source 110 can illuminate the surface of the wafer W perpendicularly or at a certain angle; no limitation is made here. The light source 110 may include lasers or LEDs of different wavelengths and powers; no specific limitation is made here.

[0079] For example, the beam collecting assembly 120 may include an objective lens 121 and a telescope lens 122, so that the beam separating assembly in the photoelectric detection device 100 can be located at the focal point of the telescope lens 122 to collect the first optical signal. The wafer W can be positioned with a wafer displacement stage; no specific limitations are made. Furthermore, the second optical signal S2 received by the sensor 21 is converted into an electrical signal and can be acquired and analyzed by a host computer to obtain defect or related parameter information.

[0080] For example, in the case of an optical detection device used for dark field detection, the first optical signal S1 can be a scattered light signal.

[0081] It is understandable that for a defect signal on the wafer that is located exactly between two sensors, the beam splitting assembly will distribute the first optical signal evenly to the two adjacent sensors.

[0082] It should be noted that due to differences in processing batches and process errors, the responses of different sensors may vary. To improve the consistency between sensors, calibration can be performed using the following methods: 1. Using an integrating sphere light source, test the sensor response time by fixing the intensity of the light source and the position of the sensor.

[0083] 2. Record the ratio of response times of different sensors under the same light intensity conditions.

[0084] 3. Adjust the analog gain of the sensor proportionally according to the response intensity, and adjust the response of different sensors to an error of no more than 5%.

[0085] It should also be noted that the steering mirror and cylindrical mirror array need to be aligned during installation. An area array camera imaging unit can be placed at the sensor's imaging position. Collimated light is incident along the optical axis onto the cylindrical mirror using a collimator. The steering mirror is fixed, and the cylindrical mirror is moved horizontally along the direction parallel to the steering mirror using an adjustment mechanism. This continues until a clear, diffraction-free spot is seen on the camera, ensuring the cylindrical mirror and steering mirror are aligned.

[0086] It should also be noted that the steering mirror and sensor need to be aligned during installation. First, align the steering mirror with the cylindrical mirror array, then install the sensor under test. Use a collimator and move the sensor horizontally until the sensor's response is strongest to ensure alignment between the steering mirror and the sensor.

[0087] It is understood that in this disclosure, directional descriptions such as "up," "down," "inner," and "outer" are relative rather than absolute. These directional terms may be applicable when the photoelectric detection device provided in this disclosure is placed in the posture and position shown in the accompanying drawings.

[0088] It should be understood that although terms such as “first” or “second” may be used in this disclosure to describe various elements (such as the first optical signal and the second optical signal), these elements are not defined by these terms, which are only used to distinguish one element from another.

[0089] The basic principles of this disclosure have been described above with reference to specific embodiments. However, it should be noted that the advantages, benefits, and effects mentioned in this disclosure are merely examples and not limitations, and should not be considered as essential features of each embodiment of this disclosure. Furthermore, the specific details disclosed above are for illustrative and facilitative purposes only, and are not limitations. These details do not limit the scope of this disclosure to the necessity of employing the aforementioned specific details for implementation.

[0090] The above description has been given for purposes of illustration and description. Furthermore, this description is not intended to limit the embodiments of this disclosure to the forms disclosed herein. Although numerous exemplary aspects and embodiments have been discussed above, those skilled in the art will recognize certain variations, modifications, alterations, additions, and sub-combinations therein.

[0091] The components and devices described in this disclosure are merely illustrative examples and are not intended to require or imply that they must be connected, arranged, or configured in the manner shown in the accompanying drawings. As those skilled in the art will recognize, these components and devices can be connected, arranged, and configured in any manner.

[0092] The above are merely specific embodiments of this disclosure, but the scope of protection of this disclosure is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this disclosure should be included within the scope of protection of this disclosure. Therefore, the scope of protection of this disclosure should be determined by the scope of the claims.

Claims

1. A photoelectric detection device for use in an optical detection device, characterized in that, include: A beam splitting assembly includes multiple beam splitting units for splitting a continuous first optical signal into multiple second optical signals corresponding to the beam splitting units, with the multiple second optical signals located at different spatial positions. A reflector assembly includes multiple reflectors for receiving and guiding multiple beams of the second optical signal, wherein the reflectors are located at the focal point of the beam splitting unit; The sensor assembly includes multiple single-pixel sensors for receiving the multiple beams of second light signals. Each single-pixel sensor corresponds one-to-one with a beam-splitting unit, and the photosensitive area of ​​each pixel unit of the single-pixel sensor is not smaller than the size of the beam-splitting unit. Each of the reflectors corresponds to a pixel unit of the single-pixel sensor, so that the second light signal is received by the corresponding pixel unit after passing through the beam splitting unit and the corresponding reflector in the reflector assembly. When the number of reflectors in the reflector assembly is equal to the number of beam splitters, the second optical signal is received by the corresponding pixel unit after passing through the beam splitter and the corresponding reflector in the reflector assembly; When the number of reflectors in the reflector assembly is less than the number of beam splitting units, the first part of the second light signal in the multiple second light signals is received by the pixel unit of the corresponding first part sensor after passing through the multiple beam splitting units and the reflector assembly, and the second part of the second light signal in the multiple second light signals is directly received by the pixel unit of the second part sensor after passing through the beam splitting unit.

2. The photoelectric detection device according to claim 1, wherein the plurality of beam-splitting units include a microlens array.

3. The photoelectric detection device according to claim 2, wherein the microlenses in the microlens array include plano-convex lenses.

4. The photoelectric detection device according to claim 3, wherein the plano-convex lens comprises a cylindrical lens.

5. The photoelectric detection device according to claim 1, wherein the product of the incident angle of the first optical signal and the focal length of the beam splitting unit is less than the size of each reflector.

6. The photoelectric detection device according to claim 1, further comprising a converging component, the converging component comprising a plurality of converging lenses, each of the plurality of converging lenses corresponding to a pixel unit of the sensor, to adjust the transmission direction of the plurality of second light signals so that the plurality of second light signals pass through the reflector assembly and the converging lens in sequence and are received by the corresponding pixel unit of the sensor.

7. In the photoelectric detection device according to claim 2, the spacing d between each microlens satisfies: 0.5mm ≤ d ≤ 10mm.

8. In the photoelectric detection device according to claim 2, the focal length f of each microlens satisfies: 5mm ≤ f ≤ 100mm.

9. An optical inspection device for inspecting wafers, characterized in that, Includes the photoelectric detection device, light source, and beam collecting assembly as described in any one of claims 1 to 8. The light source is used to illuminate the surface of the wafer to generate a first light signal. The beam collecting component is used to receive the first optical signal and guide it to converge to the photodetector, wherein each pixel unit in the photodetector corresponds to a different region of the wafer.

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