Wafer inspection equipment

Abstract

A wafer detection device includes: a wafer stage for fixing a wafer to be detected and enabling the fixed wafer to be detected to move; a laser module for emitting a detection laser to the surface of the wafer to be detected when the wafer to be detected moves; a camera array, the camera array including a plurality of cameras, for obtaining the displacement of a light spot reflected when the detection laser irradiates the surface of the wafer to be detected; and a curvature acquisition module for obtaining the curvature of the wafer to be detected according to the displacement of the light spot. The wafer detection device of the present invention improves the efficiency and accuracy of curvature detection.

Description

Technical Field

[0001] The present invention relates to the field of wafer defect detection, and in particular to a high-speed wafer detection device. Background Art

[0002] Semiconductor wafers will warp during the manufacturing process and when electronic components and circuits are subsequently made on the wafers. Warping, also known as bending, refers to the phenomenon that the wafer is deformed and uneven in the semiconductor field. In the semiconductor process, warping will affect the quality of the wafer and the progress of the semiconductor process. For example, the nitride-oxygen stack film will fall off, the wafer will crack, the layout alignment performance will be unstable, and even in the worst case, the photolithography process will be restricted by the process tools and cannot be carried out; for example, in some process steps, an adsorption tool is required to adsorb and fix the wafer. If the wafer is greatly warped, it will be difficult to adsorb and fix it, which will make the process unable to proceed.

[0003] At present, in order to avoid the above situation, the industry usually tests the degree of wafer warpage after certain processes to determine whether it is within the allowable range. If it exceeds the allowable range, it means that the warpage of the wafer will affect the subsequent processes and compensation correction is required.

[0004] Currently, wafer warpage is generally measured through optical means, but the detection efficiency and accuracy of existing detection methods still need to be improved. Summary of the invention

[0005] The technical problem to be solved by the present invention is how to improve the efficiency and accuracy of curvature detection.

[0006] The present invention provides a wafer inspection device, comprising:

[0007] A wafer stage, used for fixing the wafer to be inspected and enabling the fixed wafer to be inspected to move;

[0008] A laser module, used for emitting a detection laser toward the surface of the wafer to be detected when the wafer to be detected moves;

[0009] A camera array, the camera array comprising a plurality of cameras, for obtaining the displacement of a light spot reflected when the detection laser irradiates the surface of the wafer to be detected;

[0010] The curvature acquisition module is used to obtain the curvature of the wafer to be inspected according to the displacement of the light spot.

[0011] Optionally, the laser module is used to emit one or more beams of detection laser.

[0012] Optionally, when the laser module emits multiple beams of detection laser, the camera array obtains multiple displacements corresponding to multiple light spots, and the curvature acquisition module obtains multiple curvatures of the wafer to be inspected according to the multiple displacements.

[0013] Optionally, the camera array acquires the displacement of the light spot through a camera.

[0014] Optionally, the camera array acquires the displacement of the light spot through multiple cameras.

[0015] Optionally, the camera array is also used to obtain a detection image corresponding to the entire surface of the wafer to be inspected through a single shot, and the wafer inspection equipment also includes a defect judgment module, which determines whether there are defects on the surface of the wafer to be inspected based on the detection image obtained by the camera array.

[0016] Optionally, all cameras in the camera array have the same size and the same magnification, and the magnification is 10 to 250 times.

[0017] Optionally, the camera array further includes an image stitching unit, which is used to stitch a number of images obtained by all cameras in the camera array at the same magnification to obtain a detection image corresponding to the entire surface of the wafer to be inspected.

[0018] Optionally, the camera array includes a plurality of first cameras having a first magnification and a plurality of second cameras having a second magnification, the first magnification is smaller than the second magnification, and the number of the first cameras is greater than the number of the second cameras.

[0019] Optionally, when the camera array shoots the surface of the wafer to be inspected, the first camera and the second camera initially shoot with the same magnification to obtain several first detection images; then, the second camera increases the magnification to shoot to obtain several second detection images. The camera array also includes an image stitching unit, which is used to stitch the several first detection images to obtain a detection image corresponding to the entire surface of the wafer to be inspected.

[0020] Compared with the prior art, the technical solution of the present invention has the following advantages:

[0021] The wafer detection equipment of the present invention comprises: a wafer carrier, which is used to fix the wafer to be detected and enable the fixed wafer to be detected to move; a laser module, which is used to emit a detection laser to the surface of the wafer to be detected when the wafer to be detected moves; a camera array, which comprises a plurality of cameras and is used to obtain the displacement of a light spot reflected when the detection laser irradiates the surface of the wafer to be detected; and a curvature acquisition module, which is used to obtain the curvature of the wafer to be detected according to the displacement of the light spot. When performing curvature detection, when the laser module emits a detection laser to the surface of the wafer to be detected, due to the presence of the camera array (the size of the camera array will be relatively large), when the wafer stage drives the wafer to be detected to move a large distance, the camera array can still accurately and quickly obtain the position of the light spot reflected from the surface of the wafer to be detected, and the curvature acquisition module can also quickly obtain the curvature of the wafer to be detected according to the displacement of the light spot, thereby improving the accuracy of the curvature and the efficiency of detection (the greater the distance the wafer to be detected moves, the greater the distance that the detection laser irradiates the surface of the wafer to be detected, so that the reflected light spot can better reflect the degree of warping of the surface of the wafer to be detected, thereby improving the accuracy of detection).

[0022] Furthermore, the laser module can simultaneously emit multiple beams of detection lasers to the surface of the wafer to be inspected, so that the displacement of multiple light spots can be simultaneously obtained through different cameras in the camera array, and the corresponding curvature acquisition module can simultaneously obtain the curvature corresponding to different positions of the wafer to be inspected through the displacement of the multiple light spots, thereby further improving the accuracy and efficiency of curvature detection.

[0023] Further, the camera array is also used to obtain the detection image corresponding to the entire surface of the wafer to be detected by one shot, and the wafer detection equipment also includes a defect judgment module, and the defect judgment module judges whether there is a defect on the surface of the wafer to be detected according to the detection image obtained by the camera array. So that the wafer detection equipment of the present application can be used not only for curvature measurement, but also for defect detection. And when performing defect detection, the camera array obtains the detection image corresponding to the entire surface of the wafer to be detected by the camera array through one shot, so when acquiring the detection image, the wafer stage does not need to perform scanning movement (movement in the horizontal direction), and the wafer stage described in the present application only needs to move in a small range or a small distance in the vertical direction and / or in the horizontal direction when aligning with the camera array, so the wafer stage and the corresponding drive unit or drive device can be smaller in size, and the volume occupied by the camera array is also smaller, thereby reducing the volume occupied by the entire wafer detection equipment, and can reduce energy consumption (small drive volume reduces energy consumption). In the present application, the detection image corresponding to the entire surface of the wafer to be inspected is obtained by shooting the camera array once. The defect judgment module judges whether there are defects on the surface of the wafer to be inspected based on the detection image obtained by the camera array. When performing defect detection, the time for acquiring the detection image is greatly reduced (one-time transient imaging), thereby improving the efficiency of defect detection and reducing costs (the cost of the camera array is greatly reduced compared to the optical scanning magnifier).

[0024] Furthermore, all cameras in the camera array have the same size and the same magnification, and several cameras are arranged in an array on the planar substrate, and each camera in the camera array is set at a horizontal angle, so that when performing defect detection, the camera array can quickly focus and shoot the wafer to be inspected, and it is convenient to stitch the images obtained from several cameras.

[0025] Furthermore, the plurality of cameras in the camera array include a plurality of first cameras with a first magnification and a plurality of second cameras with a second magnification, the first magnification is smaller than the second magnification, and the number of the first cameras is greater than the number of the second cameras. When performing defect detection, the first camera with a smaller magnification can detect general defects, and the second camera with a larger magnification can obtain a larger magnification and clearer image for individual positions on the wafer to be detected, so as to meet different detection requirements (such as feature size (CD) measurement and overlay measurement).

[0026] Furthermore, when the camera array described above is used to photograph the surface of the wafer to be inspected, the first camera and the second camera are initially photographed at the same magnification to obtain a number of first inspection images, and the image stitching unit stitches the first inspection images to obtain an inspection image for general defect detection; then, the second camera increases the magnification to photograph to obtain a number of second inspection images, and the obtained number of second inspection images can be used for separate observation or measurement, such as for feature size (CD) measurement and overlay error measurement, so that general defect detection as well as feature size (CD) measurement and overlay error measurement are all performed on one device, thereby improving efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 It is a structural schematic diagram of a wafer inspection device according to an embodiment of the present invention;

[0028] Figure 2 It is a structural schematic diagram of a wafer inspection device according to another embodiment of the present invention;

[0029] Figure 3 This is a structural schematic diagram of a wafer inspection device according to another embodiment of the present invention;

[0030] Figure 4 This is a structural schematic diagram of a wafer inspection device according to another embodiment of the present invention;

[0031] Figure 5 This is a structural schematic diagram of a wafer inspection device according to another embodiment of the present invention;

[0032] Figure 6 It is a structural schematic diagram of a wafer inspection device according to another embodiment of the present invention. DETAILED DESCRIPTION

[0033] The present invention provides a wafer detection device, comprising: a wafer carrier, used for fixing a wafer to be detected and enabling the fixed wafer to be detected to move; a laser module, used for emitting a detection laser to the surface of the wafer to be detected when the wafer to be detected moves; a camera array, wherein the camera array comprises a plurality of cameras, and is used for obtaining the displacement of a light spot reflected when the detection laser irradiates the surface of the wafer to be detected; and a curvature acquisition module, used for obtaining the curvature of the wafer to be detected according to the displacement of the light spot. When performing curvature detection, when the laser module emits a detection laser to the surface of the wafer to be detected, due to the presence of the camera array (the size of the camera array will be relatively large), when the wafer stage drives the wafer to be detected to move a large distance, the camera array can still accurately and quickly obtain the position of the light spot reflected from the surface of the wafer to be detected, and the curvature acquisition module can also quickly obtain the curvature of the wafer to be detected according to the displacement of the light spot, thereby improving the accuracy of the curvature and the efficiency of detection (the greater the distance the wafer to be detected moves, the greater the distance that the detection laser irradiates the surface of the wafer to be detected, so that the reflected light spot can better reflect the degree of warping of the surface of the wafer to be detected, thereby improving the accuracy of detection).

[0034] In order to make the above-mentioned objects, features and advantages of the present invention more clearly understood, the specific embodiments of the present invention are described in detail below in conjunction with the accompanying drawings. When describing the embodiments of the present invention in detail, for the sake of convenience, the schematic diagrams will not be partially enlarged according to the general proportion, and the schematic diagrams are only examples, which should not limit the scope of protection of the present invention. In addition, in actual production, the three-dimensional dimensions of length, width and depth should be included.

[0035] refer to Figure 1 An embodiment of the present invention provides a wafer inspection device, characterized in that it includes:

[0036] The wafer stage 101 is used to fix the wafer 102 to be inspected and to move the fixed wafer 102 to be inspected;

[0037] The laser module 111 is used to emit a detection laser 11 to the surface of the wafer 102 to be detected when the wafer 102 to be detected moves;

[0038] A camera array 104, wherein the camera array 104 includes a plurality of cameras 107, which are used to obtain the displacement of the light spot reflected when the detection laser 11 irradiates the surface of the wafer 102 to be detected;

[0039] The curvature acquisition module 110 is used to obtain the curvature of the wafer 102 to be inspected according to the displacement of the light spot.

[0040] The wafer stage 101 can not only fix the wafer to be detected 102 but also move the fixed wafer to be detected 102. In some embodiments, the wafer stage 101 can fix the wafer to be detected by electrostatic adsorption, vacuum adsorption, or mechanical clamping. The wafer stage 101 can also control the fixed wafer to be detected to move linearly in a certain direction (such as the x-axis or y-axis direction) when performing curvature detection, so that the camera array 104 can obtain the displacement of the light spot reflected when the detection laser is irradiated on the surface of the wafer to be detected 102. The wafer stage 101 can be connected to a corresponding driving unit, and the driving unit is used to drive the movement of the wafer stage 101.

[0041] The wafer 102 to be inspected is a wafer that needs to be subjected to curvature measurement and / or defect detection after a certain semiconductor process. Specifically, the wafer 102 to be inspected can be a wafer after a photolithography coating process, a wafer after a photolithography development process, a wafer after an etching process (including wet etching or dry etching), a wafer after a chemical mechanical polishing process, a wafer after a chemical vapor deposition process, or a wafer after a physical vapor deposition process. The material of the wafer 102 to be inspected can be silicon (Si), germanium (Ge), or silicon germanium (GeSi), silicon carbide (SiC); it can also be silicon on insulator (SOI), germanium on insulator (GOI); or it can also be other materials, such as III-V compounds such as gallium arsenide. The size (diameter) of the wafer 102 to be inspected can be 6 inches, 8 inches, 12 inches or 18 inches.

[0042] The laser module 111 is used to emit one or more detection laser beams 11. In one embodiment, the laser module 111 includes at least one laser source for generating a detection laser beam. When the laser module 111 is used to generate multiple detection laser beams, the laser module 111 may include a beam splitter, which may split one detection laser beam into multiple detection laser beams. In other embodiments, when the laser module 111 is used to generate multiple detection laser beams, the laser module 111 may include multiple laser sources, and the multiple laser sources correspondingly generate multiple detection laser beams.

[0043] In one embodiment, when performing curvature detection, when the laser module 111 emits a beam of detection laser to the surface of the wafer 102 to be detected, due to the presence of the camera array 104 (the size of the camera array 104 will be relatively large), when the wafer stage 101 drives the wafer 104 to be detected to move a large distance, the camera array 104 can still accurately and quickly obtain the position of the light spot reflected from the surface of the wafer to be detected, and the curvature acquisition module 110 can also quickly obtain the curvature of the wafer 102 to be detected according to the displacement of the light spot, thereby improving the accuracy of the curvature and the efficiency of detection (the greater the distance that the wafer 104 to be detected moves, the corresponding distance that the detection laser irradiates the surface of the wafer to be detected will be greater, so that the reflected light spot can better reflect the degree of warping of the surface of the wafer to be detected, thereby improving the accuracy of detection).

[0044] In another embodiment, when performing curvature detection, the laser module 111 can simultaneously emit multiple detection laser beams 11 to the surface of the wafer 102 to be detected. The multiple detection laser beams 11 are parallel to each other, so that the displacement of multiple light spots can be obtained simultaneously through different cameras in the camera array. The corresponding curvature acquisition module 110 can simultaneously obtain the curvature corresponding to different positions of the wafer 102 to be detected through the displacement of the multiple light spots, thereby further improving the accuracy and efficiency of curvature detection.

[0045] In this embodiment, the laser module 111 is disposed on one side of the wafer stage 101 or the camera array 104. In other embodiments, please refer to Figure 4 The laser module 111 can be arranged above the camera array 104, and the camera array 104 can also include a planar substrate 105, and a plurality of cameras 107 are arranged on the planar substrate 105. The planar substrate 105 between two adjacent cameras 107 has a through hole penetrating the upper and lower surfaces of the planar substrate 105 (the number of the through holes is consistent with the number of laser beams generated by the laser module 111). When performing curvature detection, the laser 11 generated by the laser module 111 passes through the through holes in the parallel substrate 105 to irradiate the surface of the wafer 102 to be detected.

[0046] Please continue to refer to Figure 1 or Figure 4, a plurality of cameras 107 are arranged in an array and mounted on the planar substrate 105. The planar substrate 105 may be a PCB substrate, and the PCB substrate has a plurality of connection circuits, and the corresponding circuits are connected to the corresponding cameras. Each of the cameras 107 includes a substrate, an image sensor array located in the substrate, the image sensor array is used to sense external incident light to generate an electrical signal, and a lens assembly located on the image sensor array, the lens assembly is used to converge the external incident light on the image sensor array and to adjust the magnification and focal length of the camera.

[0047] The image sensor arrays in the plurality of cameras 107 in the camera array 104 are CMOS image sensor arrays or CCD image sensor arrays.

[0048] In one embodiment, when detecting the curvature, the camera array 104 obtains the displacement of the light spot through a camera 107. Figure 1 and Figure 2 , Figure 1 The initial position for curvature detection is that the light spot reflected by the detection laser emitted by the laser module 111 on the wafer 102 to be detected is received by the camera 107-1. Figure 2 The wafer stage 101 makes the wafer 102 to be inspected move linearly in a certain direction, and the light spot reflected by the inspection light on the wafer 102 to be inspected is still received by the camera 107 - 1 , and the displacement of the light spot can be obtained through the camera 107 - 1 .

[0049] In another embodiment, the camera array 104 acquires the displacement of the light spot through a plurality of (≥2) cameras 107. Taking two cameras acquiring the displacement of the light spot as an example, specifically, referring to Figure 1 and Figure 3 , Figure 1 The initial position for curvature detection is that the light spot reflected by the detection laser emitted by the laser module 111 on the wafer 102 to be detected is received by the camera 107-1. Figure 3 The wafer stage 101 makes the wafer 102 to be inspected move linearly in a certain direction, and the light spot reflected by the inspection light on the wafer 102 to be inspected is received by the camera 107-2, and the displacement of the light spot can be obtained through the camera 107-1 and the camera 107-2 (the positions of adjacent cameras in the camera array 104 are fixed).

[0050] Please continue to refer to Figure 1The curvature acquisition module 110 obtains the curvature of the wafer 102 to be inspected according to the displacement of the light spot. In one embodiment, the curvature of the wafer to be inspected is measured by the curvature radius. Specifically, the curvature acquisition module 110 calculates the curvature radius by the following formula: R=2L(dz / dx) -1 , where R represents the radius of curvature, L represents the optical path between the surface of the wafer 102 to be inspected and the camera 107, dx represents the moving distance of the wafer 102 to be inspected in a certain direction (such as the x-axis direction) when performing curvature measurement, and dz represents the moving distance of the light spot on the corresponding camera when the wafer 102 to be inspected moves dx.

[0051] In one embodiment, please continue to refer to Figure 1 The camera array 104 is also used to obtain a detection image corresponding to the entire surface of the wafer 102 to be detected by shooting once, and the wafer detection device also includes a defect judgment module 108, which determines whether there is a defect on the surface of the wafer to be detected based on the detection image obtained by the camera array. The wafer detection device of the present application can be used not only for curvature measurement, but also for defect detection.

[0052] The wafer stage 101 can rotate before the detection image is taken, and can also move in the vertical direction and / or move in a small range or a small distance in the horizontal direction (the specific small range or small distance movement range is plus or minus 10-25 mm), so that the wafer 102 to be detected on the wafer stage 101 is aligned with the camera array 104, and the wafer stage 101 can also deflect when the detection image is taken so that the wafer to be detected is in a tilted state to obtain a dark field image. In a specific embodiment, the wafer stage 101 can be connected to a corresponding drive unit or drive device, and the drive unit or drive device can drive the wafer stage to perform corresponding actions (including rotation, small range movement in the vertical direction, small range movement in the horizontal direction, and deflection), and the specific drive unit or drive device can be a combination of a micromotor and a micromachine.

[0053] In the present application, the subsequent defect detection on the wafer 102 to be inspected includes: detecting whether the pattern formed on the surface of the wafer 102 to be inspected is good (such as whether the pattern is complete, whether the pattern has defects), detecting whether the film layer formed on the surface of the wafer 102 to be inspected is good (such as whether the surface morphology of the film layer is good), and detecting whether there are particle defects, scratch defects or other types of defects on the surface of the wafer 102 to be inspected. Specifically, for example, after the photolithography and development process, the post-development defect detection (ADI, After Development Inspection) of the wafer 102 to be inspected specifically includes: detecting whether the photoresist pattern after development is good, the photoresist pattern includes a photoresist pattern used as a subsequent etching mask, a photoresist pattern used to measure a feature size (CD), and a photoresist pattern used to measure an overlay error (overlay), and checking whether there are particle defects, scratch defects or other types of photoresist defects. For another example, the post-etch defect inspection (AEI, After Etch Inspection) performed on the wafer to be inspected after the etching process specifically includes: inspecting whether the etching pattern is good, inspecting whether there are particle defects, scratch defects or other types of etching defects.

[0054] In this embodiment, the size of the camera array 104 corresponds to the size of the wafer 102 to be inspected, that is, the size of the camera array 104 can be equal to, approximately equal to, slightly larger than, or slightly smaller than the size of the wafer 102 to be inspected, as long as the combined viewing angle of the cameras in the camera array 104 can cover the entire surface of the wafer 102 to be inspected.

[0055] The camera array 104 includes a plurality of cameras 107. In one embodiment, the number of cameras 107 in the camera array 104 is greater than or equal to 5, and may be 5 (a specific arrangement may be to set 1 camera in the middle of the planar substrate 105, and to set 1 camera on each of the four edges), 9 (a specific arrangement may be to arrange 9 cameras in a 3x3 array on the planar substrate 105), 13 (a specific arrangement may be to arrange 9 cameras in a 3x3 array in the middle of the planar substrate 105, and to arrange 1 camera on each of the four edges), 24 (a specific arrangement may be to arrange 16 cameras in a 4x4 array in the middle of the planar substrate 105, and to arrange 2 cameras on each of the four edges), 37 (a specific arrangement may be to arrange 25 cameras in a 5x5 array in the middle of the planar substrate 105, and to arrange 3 cameras on each of the four edges), 69 (a specific arrangement may be to arrange 7x4 array in the middle of the planar substrate 105, and to arrange 7x4 array in the middle of the planar substrate 105, and to arrange 7 cameras on each of the four edges). 7 arrays are arranged with 49 cameras, with 5 cameras arranged on each of the four edges. Figure 1It should be noted that the number of cameras 107 in the camera array 104 can also be other numbers, and the specific number can be set according to the size of the wafer 102 to be inspected, the clarity of the image, the accuracy of the inspection, etc., as long as the combined viewing angle of the cameras in the camera array 104 can cover the entire surface of the wafer 102 to be inspected.

[0056] In this embodiment, reference Figure 1 All cameras 107 in the camera array 104 have the same size (the size is the package size of the camera) and the same magnification. Several cameras 107 are arranged in an array on the planar substrate 105, and each camera 107 in the camera array 104 is set at a horizontal angle, so that when performing defect detection, the camera array 104 in the camera array 104 can quickly focus and shoot the wafer 102 to be inspected, and it is convenient to stitch the images obtained by several cameras 107.

[0057] Specifically, the magnification of each camera 107 in the camera array 104 is 10 to 250 times.

[0058] When the aforementioned camera array 104 is used for shooting, all cameras 107 in the camera array 104 use the same magnification for shooting. Each camera 107 also has its own control chip (not shown in the figure), and the control chip controls the corresponding camera 107 to perform focusing, magnification and shooting. The camera array 104 may also include a total shooting control unit, which is used to send control instructions to the control chips in each camera 107, such as focusing instructions, magnification instructions, shooting instructions, etc. In a specific embodiment, the focusing of the camera can use phase detection autofocus (Phase Detection AutoFocus).

[0059] In another embodiment, the sizes of the cameras 107 in the camera array 104 are the same, but the magnifications of the cameras are different. For details, refer to Figure 5The several cameras 107 in the camera array 104 include several first cameras 107a with a first magnification and several second cameras 107b with a second magnification, the first magnification is smaller than the second magnification, the number of the first cameras 107a is greater than the number of the second cameras 107b, and the size values ​​of the first cameras 107a and the second cameras 107b are the same. When performing defect detection, the first camera 107 with a smaller magnification can detect general defects, and the second camera 107b with a larger magnification can obtain a larger magnification and clearer image for individual positions on the wafer to be detected to meet different detection requirements (such as characteristic size (CD) measurement and overlay error measurement). Specifically, the camera array 104 uses a second camera 107b with a larger magnification to detect the photoresist pattern used to measure the characteristic size (CD) and obtain a specific characteristic size value, and can also detect the photoresist pattern used to measure the overlay error and obtain a specific overlay error value, or can also be used to obtain a larger magnification and clearer image at a specific position for observation by process and equipment personnel. That is, the defect detection equipment of the present application can be used for rapid detection of general defects and rapid measurement of overlay errors and characteristic size values, thereby improving the defect detection efficiency and the measurement efficiency of related parameters in the integrated circuit manufacturing process and saving the time required for the entire integrated circuit process.

[0060] In one embodiment, the first magnification is 10 to 250 times, and the second magnification is 20 to 300 times.

[0061] In one embodiment, the plurality of second cameras 107 b are located at a plurality of specific positions in the camera array 104 , and the number of the second cameras 107 b is greater than or equal to two.

[0062] In a specific embodiment, please continue to refer to Figure 5 , the number of the second cameras 107b is 3, and the three second cameras 107b are respectively located at the center, the edge, and the position between the center and the edge of the camera array 104. In other embodiments, the number of the second cameras 107b can also be 5 (5 second cameras 107b are distributed in the middle of the camera array 104, and 4 are distributed at the edge) or 9 (9 second cameras 107b are distributed in a nine-square grid in the camera array 104). When performing defect detection, only the second camera 107b can be used to detect the corresponding positions on the wafer 102 to be detected, thereby improving the efficiency of detection.

[0063] In one embodiment, when the camera array 104 described above is used to photograph the surface of the wafer 102 to be inspected, the first camera 107a and the second camera 107b are initially photographed at the same magnification (first magnification) to obtain a number of first inspection images for general defect detection; then, the second camera 107b increases the magnification (second magnification, the second magnification is greater than the first magnification) to photograph to obtain a number of second inspection images, and the obtained number of second inspection images can be used for separate observation or measurement, such as for feature size (CD) measurement and overlay error measurement, so that general defect detection and feature size (CD) measurement and overlay error measurement are all performed on one device, improving measurement efficiency. In a specific embodiment, a pattern (CDbar) for feature size measurement and a pattern (overlay mark) for overlay error measurement are formed at a specific position of the wafer 102 to be inspected (the specific position is a position corresponding to a second camera 107b in the camera array 104).

[0064] In other embodiments, when the camera array 104 described above is used to photograph the surface of the wafer to be inspected, only the second camera 107 b may be used for photographing.

[0065] In a specific embodiment, before the camera array 104 is used to shoot and obtain the detection image corresponding to the entire surface of the wafer to be inspected, the camera array 104 and the wafer to be inspected 102 need to be aligned so that the position of the wafer to be inspected 102 can correspond to the position of the camera 107 on the camera array 104. Since the initial position of the wafer stage 101 is known, and the positions of the cameras 107 on the camera array 104 are fixed, the position of the notch on the wafer to be inspected 102 is fixed, and therefore before obtaining the detection image corresponding to the entire surface of the wafer to be inspected, the camera array 104 is used to obtain the image of the edge of the wafer to be inspected, and the position of the notch on the wafer to be inspected 102 relative to the wafer stage 101 can be obtained through the corresponding image processing process. By adjusting the position of the wafer stage 101, the wafer to be inspected 102 on the wafer stage 101 can establish a positional connection with the camera 107 on the camera array 104, so that the position of the wafer to be inspected 102 can correspond to the position of the camera 107 on the camera array 104.

[0066] The camera array 104 further includes an image stitching unit 106. In one embodiment, please refer to Figure 1, when each camera 107 in the camera array 104 has the same size and the same magnification, and when photographing the surface of the wafer 102 to be inspected, all cameras 107 in the camera array 104 use the same magnification to photograph, the image stitching unit 106 is used to stitch together a number of images obtained by all cameras 107 in the camera array 104 at the same magnification to obtain a detection image corresponding to the entire surface of the wafer to be inspected. In another embodiment, please refer to Figure 5 When the several cameras 107 in the camera array 104 include several first cameras 107a with a first magnification and several second cameras 107b with a second magnification, when shooting the surface of the wafer 102 to be inspected, the first cameras 107a and the second cameras 107b start to shoot with the same magnification, and when several first detection images are obtained, the image stitching unit 106 is used to stitch the several first detection images to obtain a detection image corresponding to the entire surface of the wafer to be inspected.

[0067] In one embodiment, the image stitching unit 106 performs stitching including an image preprocessing step, an image registration step, a change model establishment step, a same coordinate change step, and a fusion reconstruction step.

[0068] Specifically, the image preprocessing step includes basic operations of digital image processing (such as denoising, edge extraction, histogram processing, etc.), establishing a matching template for the image, and performing some transformation on the image (such as Fourier transform, wavelet transform, etc.).

[0069] The image registration step is to use a certain matching strategy or algorithm to find the corresponding position of the template or feature point in the image to be spliced ​​in the reference image, and then determine the transformation relationship between the two images.

[0070] In one embodiment, the algorithm used for the image registration can adopt a frequency domain-based method (phase correlation method) and a time domain-based method. Among them, the time domain-based method can be specifically divided into a feature-based method and a region-based method. The feature-based method first finds the feature points (such as boundary points, inflection points, corner points) in the two images, and determines the correspondence between the feature points between the images, and then uses this correspondence to find the transformation relationship between the two images. This type of method does not directly use the grayscale information of the image, so it is not sensitive to light changes, but it relies heavily on the accuracy of the correspondence between the feature points. The region-based method uses a block in the overlapping area of ​​one image as a template, and searches for the matching block that is most similar to this template in the other image. This algorithm has high accuracy.

[0071] The step of establishing the transformation model calculates the parameter values ​​in the mathematical model according to the corresponding relationship between the templates or image features, thereby establishing a mathematical transformation model of the two images.

[0072] The unified coordinate transformation step transforms the image to be spliced ​​into the coordinate system of the reference image according to the established mathematical transformation model to complete the unified coordinate transformation.

[0073] The fusion and reconstruction step fuses the overlapping areas of the images to be stitched to obtain a smooth and seamless panoramic image that is stitched and reconstructed.

[0074] In one embodiment, the image stitching unit 106 includes an image processing chip. The image stitching unit 106 can be installed on the planar substrate 105 and connected to the corresponding camera 107 through a number of circuits on the planar substrate 105, which can further reduce the volume occupied by the camera array 104.

[0075] In one embodiment, the defect judgment module 108 includes a standard unit and a comparison unit. The standard unit stores a standard wafer image or a defect-free wafer image. The comparison unit is used to compare or match the detection image obtained by the camera array with the standard wafer image or the defect-free wafer image, and then determine whether there are defects on the detection image and the location of the defects, thereby determining whether there are defects on the surface of the wafer to be inspected.

[0076] In another embodiment, the defect judgment module 108 may include an area division unit and a comparison unit, wherein the area division unit divides the detection image into a number of areas to be compared of the same size (when there are no defects, the graphics and patterns on the areas to be compared are the same or repeated), and the comparison unit is used to compare several adjacent areas to be compared to find out the locations of different points in the adjacent areas to be compared, which are the locations where defects exist.

[0077] It should be noted that the defect judgment module 108 may use other methods or approaches to judge whether there are defects in the detection image.

[0078] The standard wafer image or the defect-free wafer image is an image obtained when there are no defects on the surface of the wafer to be inspected after a certain semiconductor process is performed.

[0079] In one embodiment, please refer to Figure 6, the wafer inspection device also includes an illumination light source 109, and the illumination light source 109 is used to emit white light to illuminate the surface of the wafer 102 to be inspected during inspection. In this embodiment, the illumination unit 109 is arranged on one side of the wafer stage 101 and the planar substrate 105. When performing defect detection, the wafer stage 101 can be deflected so that the wafer 102 to be inspected is in an inclined state. At the same time, the illumination unit 109 illuminates the surface of the wafer 102 to be inspected, and the camera array 104 obtains a detection image with a dark field corresponding to the entire surface of the wafer to be inspected by shooting once. In one embodiment, the illumination unit 109 can rotate around the wafer stage 101 and the planar substrate 105. In another embodiment, the number of the illumination units 109 can be multiple (greater than or equal to 2), and the multiple illumination units 109 are evenly (at equal angles) distributed around the wafer stage 101 and the planar substrate 105.

[0080] In other embodiments, the illumination light source can be directly set on one side of the camera 107 in the camera array 104. When shooting, the front side of the wafer 102 to be inspected is illuminated. The camera array 104 obtains a detection image with a bright field corresponding to the entire surface of the wafer to be inspected through one shooting.

[0081] When the aforementioned wafer inspection equipment is used for defect detection, the camera array 104 obtains the inspection image corresponding to the entire surface of the wafer 102 to be inspected through a single shot. Therefore, the wafer stage 101 does not need to perform scanning movement (move in the horizontal direction) when acquiring the inspection image, and the wafer stage 101 described in the present application only needs to move in a small range or distance in the vertical direction and / or in the horizontal direction when aligning with the camera array 104. Therefore, the wafer stage 101 and the corresponding driving unit or driving device can be smaller in size, and the volume occupied by the camera array 104 is also smaller, thereby reducing the volume occupied by the entire wafer inspection equipment and reducing energy consumption (small driving volume reduces energy consumption). In the present application, the detection image corresponding to the entire surface of the wafer 102 to be inspected is obtained by shooting once with the camera array 104. The defect judgment module 108 judges whether there are defects on the surface of the wafer 102 to be inspected based on the detection image obtained by the camera array 104. When performing defect detection, the time for acquiring the detection image is greatly reduced (one-time transient imaging), thereby improving the efficiency of defect detection and reducing costs (the cost of the camera array is greatly reduced compared to the optical scanning magnifier).

[0082] The above is only a preferred embodiment of the present invention. It should be pointed out that ordinary technicians in this technical field can make several improvements and modifications without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A wafer inspection device, characterized in that: include: A wafer stage, used for fixing the wafer to be inspected and enabling the fixed wafer to be inspected to move; A laser module, used for emitting multiple beams of detection laser to the surface of the wafer to be detected when the wafer to be detected moves; A camera array, wherein the camera array includes a plurality of cameras, and is used to obtain a plurality of displacements corresponding to a plurality of light spots reflected when a plurality of detection laser beams irradiate the surface of the wafer to be detected. The camera array also includes a planar substrate, and the plurality of cameras are arranged on the planar substrate. The planar substrate is a PCB substrate, and the PCB substrate has a plurality of connection circuits, and the corresponding circuits are connected to the corresponding cameras; The planar substrate between two adjacent cameras has a through hole penetrating the upper and lower surfaces of the planar substrate, the laser module is arranged above the camera array, and the detection laser emitted by the laser module passes through the through hole to illuminate the wafer to be detected; The curvature acquisition module is used to obtain multiple curvatures of the wafer to be detected according to the multiple displacements of the multiple light spots. The curvature acquisition module calculates the curvature radius through the following formula: R=2L(dz / dx) -1, where R represents the curvature radius, L represents the optical path between the surface of the wafer to be detected and the camera, dx represents the moving distance of the wafer to be detected in a certain direction when the curvature is measured, and dz represents the moving distance of the light spot on the corresponding camera when the wafer to be detected moves dx. At the initial position during curvature detection, the light spot reflected by the detection laser emitted by the laser module on the wafer to be detected is received by one camera in the camera array. When the wafer carrier makes the wafer to be detected move in a straight line in a certain direction, the light spot reflected by the detection laser on the wafer to be detected is received by another camera.

2. The wafer inspection device according to claim 1, characterized in that: The camera array acquires the displacement of the light spot through multiple cameras.

3. The wafer inspection device according to claim 1, characterized in that: The camera array is also used to obtain a detection image corresponding to the entire surface of the wafer to be inspected through a single shot. The wafer inspection equipment also includes a defect judgment module, which determines whether there are defects on the surface of the wafer to be inspected based on the detection image obtained by the camera array.

4. The wafer inspection device according to claim 3, characterized in that: All cameras in the camera array have the same size and the same magnification, and the magnification is 10 to 250 times.

5. The wafer inspection device according to claim 4, characterized in that: The camera array further includes an image stitching unit, which is used to stitch a number of images obtained by all cameras in the camera array at the same magnification to obtain a detection image corresponding to the entire surface of the wafer to be detected.

6. The wafer inspection device according to claim 3, characterized in that: The camera array includes a plurality of first cameras with a first magnification and a plurality of second cameras with a second magnification, the first magnification is smaller than the second magnification, and the number of the first cameras is greater than the number of the second cameras.

7. The wafer inspection device according to claim 6, characterized in that: When the camera array shoots the surface of the wafer to be inspected, the first camera and the second camera start to shoot with the same magnification to obtain a number of first detection images; then, the second camera increases the magnification to shoot to obtain a number of second detection images. The camera array also includes an image stitching unit, which is used to stitch the several first detection images to obtain a detection image corresponding to the entire surface of the wafer to be inspected.

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