Wafer defect inspection equipment

Abstract

A wafer defect detection device includes: a wafer stage for fixing a wafer to be detected; an immersion liquid providing module for providing an immersion liquid to immerse the wafer to be detected on the wafer stage in the immersion liquid, wherein the refractive index of the immersion liquid is greater than the refractive index of air; an image acquisition module, wherein the image acquisition module includes a camera array, wherein the image acquisition module obtains a detection image corresponding to the entire surface of the wafer to be detected by shooting with the camera array at one time, and when shooting, at least part of the camera array is immersed in the immersion liquid; and a defect judgment module, wherein the defect judgment module judges whether there is a defect on the surface of the wafer to be detected based on the detection image obtained by the image acquisition module. The wafer defect detection device of the present invention improves the defect detection accuracy.

Description

Technical Field

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

[0002] With the rapid development of semiconductor manufacturing technology, semiconductor devices are developing towards higher integration in order to achieve faster computing speeds, larger storage capacities and more functions. The higher the integration of semiconductor chips, the smaller the critical dimension (CD) of the semiconductor device.

[0003] Photolithography is the most important process in semiconductor integrated manufacturing. When manufacturing integrated circuits, multi-layer processes are required, and each layer must be accurately aligned. Therefore, in order to ensure that the patterns between the layers of photolithography are accurately stacked, the chip must be inspected after the development process is completed. After-development inspection can detect errors in the photolithography process and correct them in time. This is one of the few steps in the chip manufacturing process that can be corrected. Once a wafer with defective photoresist is sent to the next step of pattern formation (etching), it is very easy to cause the wafer to be scrapped. Specifically, the after-development inspection generally includes checking the coverage, alignment, exposure, and development of the photoresist one by one, and judging whether the photoresist performance meets the process requirements.

[0004] In addition, after the thin film deposition, etching, and chemical mechanical polishing processes in the semiconductor manufacturing process are completed, defect detection needs to be carried out through detection equipment. Although the existing detection equipment uses an imaging sensor to obtain a detection image through a single shot, the detection method can improve the detection efficiency, the detection accuracy still needs to be improved. Summary of the invention

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

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

[0007] Wafer stage, used to fix the wafer to be inspected;

[0008] An immersion liquid providing module, used for providing an immersion liquid to immerse the wafer to be inspected on the wafer stage in the immersion liquid, wherein the refractive index of the immersion liquid is greater than the refractive index of air;

[0009] An image acquisition module, wherein the image acquisition module comprises a camera array, and the image acquisition module obtains a detection image corresponding to the entire surface of the wafer to be inspected by shooting with the camera array at one time, and when shooting, at least part of the camera array is immersed in the immersion liquid;

[0010] A defect judgment module is used to judge whether there are defects on the surface of the wafer to be inspected according to the inspection image obtained by the image acquisition module.

[0011] Optionally, the immersion liquid providing module includes an immersion liquid supply unit and a receiving tank, wherein the immersion liquid supply unit is used to supply the immersion liquid to the receiving tank, the receiving tank is used to receive the immersion liquid, and the wafer carrier is located in the receiving tank.

[0012] Optionally, the refractive index of the immersion liquid is greater than 1.1.

[0013] Optionally, the wetting liquid includes any one of deionized water, perfluoropolyether or cyclooctane, or a mixture of at least two of them.

[0014] Optionally, the camera array includes a lens assembly, and when the image acquisition module obtains the detection image corresponding to the entire surface of the wafer to be inspected by shooting with the camera array at one time, the lens assembly of the camera array is immersed in the immersion liquid.

[0015] Optionally, the image acquisition module further includes a planar substrate, and a plurality of cameras are arranged in an array on the planar substrate to form the camera array, and the number of the cameras is greater than or equal to 5.

[0016] Optionally, the wafer defect detection equipment includes a lighting device, which includes a light source and an optical fiber transmission unit. The light source is used to emit illumination light of a specific wavelength, and the optical fiber transmission unit is used to transmit the illumination light of the specific wavelength emitted by the light source to the surface of the wafer to be inspected for illumination.

[0017] Optionally, the wavelength range of the illumination light of the specific wavelength emitted by the light source is 50nm-500nm.

[0018] Optionally, the wafer defect detection device further includes: a laser module and a curvature acquisition module, wherein the laser module is used to emit a detection laser to the surface of the wafer to be detected when the wafer to be detected moves; the camera array is also used to obtain the displacement of the light spot reflected when the detection laser irradiates the surface of the wafer to be detected; the curvature acquisition module is used to obtain the curvature of the wafer to be detected according to the displacement of the light spot.

[0019] Optionally, the laser module includes an emitting end, and when measuring the curvature, the emitting end of the laser module, the wafer to be inspected, and the lens assembly of the camera array are immersed in the immersion liquid.

[0020] Optionally, the wafer stage can enable the wafer to be inspected to rotate, move vertically, move horizontally, or deflect in the immersion liquid.

[0021] Compared with the prior art, the technical solution of the present invention has the following advantages:

[0022] The wafer defect detection device of the present invention comprises: a wafer stage for fixing a wafer to be detected;

[0023] An immersion liquid providing module is used to provide an immersion liquid to immerse the wafer to be inspected on the wafer carrier in the immersion liquid, wherein the refractive index of the immersion liquid is greater than the refractive index of air; an image acquisition module, wherein the image acquisition module includes a camera array, wherein the image acquisition module obtains a detection image corresponding to the entire surface of the wafer to be inspected by shooting with the camera array at one time, and when shooting, at least part of the camera array is immersed in the immersion liquid; a defect judgment module, wherein the defect judgment module judges whether there is a defect on the surface of the wafer to be inspected based on the detection image obtained by the image acquisition module. An immersion liquid having a refractive index greater than that of air is provided by an immersion liquid providing module, so that the wafer to be inspected on the wafer stage is immersed in the immersion liquid. During defect detection, when the illumination light source illuminates the entire surface of the wafer to be inspected through the immersion liquid (compared to illuminating the surface of the wafer to be inspected through the air), the energy loss of the illumination light source will be smaller, the energy distribution when irradiating the entire surface of the wafer to be inspected will be more uniform, and the irradiation position will be more precise, so that the energy of the light reflected from the wafer surface will be stronger, the accuracy will be better, and the resolution will be improved. Therefore, when the image acquisition module shoots once through the camera array, the resolution and accuracy of the detection image corresponding to the entire surface of the wafer to be inspected obtained by receiving the reflected light will be higher, thereby improving the accuracy of defect detection. Moreover, since the camera array is at least partially immersed in the immersion liquid when the camera array is shooting, the light reflected from the surface of the wafer to be inspected will only be transmitted to the camera array through the immersion liquid, so that the energy and signal loss of the reflected light are small, and the noise will be reduced, further improving the resolution and accuracy of the detection image, thereby further improving the accuracy of defect detection. In the present application, the detection image corresponding to the entire surface of the wafer to be inspected is obtained by a single shot of the image acquisition module through the camera array. 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 image acquisition module. 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, when the image acquisition module obtains the detection image corresponding to the entire surface of the wafer to be inspected through the camera array at one time, the lens assembly of the camera array is immersed in the immersion liquid, so that the light reflected from the surface of the wafer to be inspected can be directly transmitted through the immersion liquid to enter the camera array for sensing, thereby reducing the loss and noise of the reflected light.

[0025] Furthermore, the wafer defect detection equipment includes a lighting device, and the optical fiber transmission unit is used to transmit the illumination light of a specific wavelength emitted by the light source to illuminate the entire surface of the wafer to be inspected through the perforation, so that the illumination light has less energy loss during transmission, which is conducive to improving resolution.

[0026] Furthermore, the wafer defect detection equipment also includes: a laser module and a curvature acquisition module, wherein the laser module is used to emit a detection laser to the surface of the wafer to be detected when the wafer to be detected moves; the camera array is also used to obtain the displacement of the light spot reflected when the detection laser irradiates the surface of the wafer to be detected; the curvature acquisition module is used to obtain the curvature of the wafer to be detected according to the displacement of the light spot. The laser module includes a transmitting end. When measuring the curvature, the transmitting end of the laser module, the wafer to be detected and the lens assembly of the camera array are immersed in the immersion liquid. Since the transmission of the detection laser and the transmission of the light spot reflected when the wafer surface to be detected are both in the immersion liquid, the energy, accuracy and resolution are high, and the loss is small, thereby improving the accuracy of the curvature measurement. In addition to the defect detection function, the wafer defect detection equipment of the present application also has the function of curvature detection. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 A schematic diagram of the structure of a wafer defect detection device according to an embodiment of the present invention;

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

[0029] Figure 3 It is a structural schematic diagram of a wafer defect detection device according to another embodiment of the present invention. DETAILED DESCRIPTION

[0030] The present invention provides a wafer defect detection device, comprising: a wafer carrier, used to fix a wafer to be detected; an immersion liquid providing module, used to provide an immersion liquid to immerse the wafer to be detected on the wafer carrier in the immersion liquid, wherein the refractive index of the immersion liquid is greater than the refractive index of air; an image acquisition module, wherein the image acquisition module comprises a camera array, wherein the image acquisition module obtains a detection image corresponding to the entire surface of the wafer to be detected by shooting with the camera array at one time, and when shooting, at least a part of the camera array is immersed in the immersion liquid; and a defect judgment module, wherein 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 image acquisition module. An immersion liquid having a refractive index greater than that of air is provided by an immersion liquid providing module, so that the wafer to be inspected on the wafer stage is immersed in the immersion liquid. During defect detection, when the illumination light source illuminates the entire surface of the wafer to be inspected through the immersion liquid (compared to illuminating the surface of the wafer to be inspected through the air), the energy loss of the illumination light source will be smaller, the energy distribution when irradiating the entire surface of the wafer to be inspected will be more uniform, and the irradiation position will be more precise, so that the energy of the light reflected from the wafer surface will be stronger, the accuracy will be better, and the resolution will be improved. Therefore, when the image acquisition module shoots once through the camera array, the resolution and accuracy of the detection image corresponding to the entire surface of the wafer to be inspected obtained by receiving the reflected light will be higher, thereby improving the accuracy of defect detection. Moreover, since the camera array is at least partially immersed in the immersion liquid when the camera array is shooting, the light reflected from the surface of the wafer to be inspected will only be transmitted to the camera array through the immersion liquid, so that the energy and signal loss of the reflected light are small, and the noise will be reduced, further improving the resolution and accuracy of the detection image, thereby further improving the accuracy of defect detection.

[0031] 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.

[0032] refer to Figure 1 , an embodiment of the present invention provides a wafer defect detection device, comprising:

[0033] Wafer stage 101, used for fixing wafer 102 to be inspected;

[0034] An immersion liquid providing module 111 is used to provide an immersion liquid 112 to immerse the wafer 102 to be inspected on the wafer stage 101 in the immersion liquid 112, wherein the refractive index of the immersion liquid 112 is greater than the refractive index of air;

[0035] An image acquisition module 103, wherein the image acquisition module 103 includes a camera array 104, and the image acquisition module 103 obtains a detection image corresponding to the entire surface of the wafer to be inspected by shooting with the camera array 104 at one time, and when shooting, the camera array 104 is at least partially immersed in the immersion liquid 112;

[0036] The defect judgment module 108 judges whether there are defects on the surface of the wafer 102 to be inspected according to the inspection image obtained by the image acquisition module 103 .

[0037] In one embodiment, the immersion liquid providing module 111 includes an immersion liquid supply unit 109 and a receiving tank 111, wherein the immersion liquid supply unit 109 is used to supply the immersion liquid 112 to the receiving tank 110, and the receiving tank 110 is used to receive the immersion liquid 112. The immersion liquid providing module 111 provides the immersion liquid 112 whose refractive index is greater than that of air, so that the wafer 102 to be inspected on the wafer carrier 101 is immersed in the immersion liquid 112. During the defect detection process, when the illumination light source illuminates the entire surface of the wafer to be inspected through the immersion liquid (compared to illuminating the surface of the wafer to be inspected through the air), the energy loss of the illumination light source will be smaller, the energy distribution when irradiating the entire surface of the wafer to be inspected will be more uniform, and the irradiation position will be more precise, so that the energy of the light reflected from the wafer surface will be stronger, the accuracy will be better, and the resolution will be improved. When the image acquisition module 103 takes a picture through the camera array 104 at one time, the detection image resolution and accuracy corresponding to the entire surface of the wafer to be inspected obtained by receiving the reflected light will be higher, thereby improving the accuracy of defect detection, and because the camera array is at least partially immersed in the immersion liquid when the camera array is taking pictures, the light reflected from the surface of the wafer to be inspected will only be transmitted to the camera array through the immersion liquid, so that the energy and signal loss of the reflected light are small, and the noise will be reduced, thereby further improving the detection image resolution and accuracy, thereby further improving the accuracy of defect detection.

[0038] In one embodiment, the immersion liquid supply unit 109 includes a filtering component, so that when supplying the immersion liquid 112, the immersion liquid 112 is filtered through the filtering component to remove impurities and bubbles. The immersion liquid supply unit 109 also includes a flow control component, through which the flow of the immersion liquid can be controlled.

[0039] In one embodiment, a drain port may be provided on the bottom or side wall of the receiving tank 111 to discharge the immersion liquid 112 in the receiving tank 110 when the detection is completed or when the immersion liquid 112 in the receiving tank 110 is contaminated.

[0040] The refractive index of the immersion liquid 112 is greater than 1.1, and it is ensured that there are no particles or contaminants in the immersion liquid 112 to contaminate the wafer to be inspected. In one embodiment, the immersion liquid 112 includes any one of deionized water, perfluoropolyether or cyclooctane, or a mixture of at least two of them.

[0041] The wafer stage 101 is used to fix the wafer 102 to be inspected. Specifically, the wafer stage 101 can fix the wafer 102 to be inspected by vacuum adsorption, electrostatic adsorption or mechanical support.

[0042] In one embodiment, the wafer stage 101 can move. Specifically, before the detection image is taken, the wafer stage 101 can rotate in the immersion liquid 112, and can 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 on the image acquisition module 103. In a specific embodiment, the wafer stage 101 can be connected to a corresponding driving unit or driving device, and the driving unit or driving device can drive the wafer stage to perform corresponding actions in the immersion liquid 112 (including rotation, small range movement in the vertical direction, small range movement in the horizontal direction, and deflection). The specific driving unit or driving device can be a combination of a micromotor and a micromachine. In one embodiment, the wafer stage 101 and the corresponding driving unit are located in the receiving groove 110. In another embodiment, the wafer stage 101 and the movable parts of the driving unit are located in the receiving groove 110 , and the immovable part of the driving unit may be located outside the receiving groove 110 .

[0043] The wafer 102 to be inspected is a wafer that needs to be inspected for defects after undergoing a certain semiconductor process. Specifically, the wafer 102 to be inspected can be a wafer after undergoing a photolithography coating process, a wafer after undergoing a photolithography development process, a wafer after undergoing an etching process (including wet etching or dry etching), a wafer after undergoing a chemical mechanical polishing process, a wafer after undergoing a chemical vapor deposition process, or a wafer after undergoing 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.

[0044] 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.

[0045] In one embodiment, the image acquisition module 103 further includes a planar substrate 105, and a plurality of cameras 107 are arranged in an array on the planar substrate 105 to form a camera array 104. The planar substrate 105 is used to install a plurality of cameras 107. Specifically, 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 external incident light on the image sensor array and to adjust the magnification and focal length of the camera. The corresponding plurality of lens assemblies in the camera array constitute the lens assembly of the camera array. In one embodiment, when the image acquisition module 103 obtains the detection image corresponding to the entire surface of the wafer to be inspected by shooting with the camera array 104 at one time, the lens assembly of the camera array is immersed in the immersion liquid, so that the light reflected from the surface of the wafer to be inspected can be directly transmitted through the immersion liquid to enter the camera array for sensing, thereby reducing the loss and noise of the reflected light.

[0046] 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.

[0047] 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.

[0048] 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 can be 5 (a specific arrangement method can be to set 1 camera in the middle of the planar substrate 105 and set a camera on each of the four edges), 9 (a specific arrangement method can be to arrange 9 cameras in a 3x3 array on the planar substrate 105), 13 (a specific arrangement method can be to arrange 9 cameras in a 3x3 array in the middle of the planar substrate 105). cameras, 1 camera is arranged on each of the four edges), 24 (the specific arrangement method can be 16 cameras arranged in a 4x4 array in the middle of the planar substrate 105, and 2 cameras are arranged on each of the four edges), 37 (the specific arrangement method can be 25 cameras arranged in a 5x5 array in the middle of the planar substrate 105, and 3 cameras are arranged on each of the four edges), 69 (the specific arrangement method can be 49 cameras arranged in a 7x7 array in the middle of the planar substrate 105, and 5 cameras are arranged on each of the four edges, such as Figure 1 It 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.

[0049] The wafer defect detection device includes an illumination device 115, and the illumination device 115 is used to illuminate the surface of the wafer 102 to be detected when the camera array 104 shoots the surface of the wafer 102 to be detected. The illumination device 115 includes a light source 114 and an optical fiber transmission unit 113, and the light source 114 is used to emit illumination light of a specific wavelength, and the optical fiber transmission unit 113 is used to transmit the illumination light of a specific wavelength emitted by the light source to the surface of the wafer 102 to be detected for illumination. Specifically, a plurality of perforations can be opened in the planar substrate 105, and the opening positions of the perforations do not overlap with the cameras. The illumination light of the optical fiber transmission unit 113 is incident on the surface of the wafer 102 to be detected through the perforations. The optical fiber transmission unit 113 makes the energy loss of the illumination light smaller during transmission, thereby ensuring the uniformity of the energy and brightness distribution of the illumination light when illuminating the surface of the wafer 102 to be detected, which is conducive to improving the resolution.

[0050] In one embodiment, the wavelength range of the illumination light of a specific wavelength emitted by the light source 114 is 50nm-500nm, which can be 50nm, 100nm, 150nm, 193nm, 248nm, 365nm, 400nm, 450nm, so as to further improve the resolution of the obtained detection image.

[0051] The optical fiber transmission unit 113 includes a plurality of optical fiber transmission channels, each of which corresponds to a perforation on the planar substrate. The illumination light output by each optical fiber transmission channel illuminates a portion of the surface of the wafer to be inspected. The entire surface of the wafer 102 to be inspected is illuminated through the plurality of optical fiber transmission channels, thereby improving the uniformity of the energy and brightness distribution of the illumination light when illuminating the surface of the wafer to be inspected. The specific number of optical fiber transmission channels only needs to satisfy the requirement that the illumination light output by all optical fiber transmission channels can illuminate the entire surface of the wafer 102 to be inspected.

[0052] In this embodiment, continue to refer to 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 image acquisition module 103 can quickly focus and shoot the wafer 102 to be inspected, and it is convenient to stitch the images obtained by several cameras 107.

[0053] Specifically, the magnification of each camera 107 in the camera array 104 is 10 to 250 times.

[0054] 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 image acquisition module 103 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).

[0055] 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 2 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, 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 image acquisition module 103 uses the 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 of 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 can also be used for 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.

[0056] In one embodiment, the first magnification is 10 to 250 times, and the second magnification is 20 to 300 times.

[0057] 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.

[0058] In a specific embodiment, please continue to refer to Figure 2 , 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.

[0059] 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).

[0060] 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.

[0061] 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.

[0062] The image acquisition module 103 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 2 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.

[0063] 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.

[0064] 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.).

[0065] 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.

[0066] 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.

[0067] 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.

[0068] 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.

[0069] 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.

[0070] 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 several circuits on the planar substrate 105, which can further reduce the volume occupied by the image acquisition module 103.

[0071] 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 image acquisition module 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.

[0072] 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.

[0073] 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.

[0074] 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.

[0075] In one embodiment, reference Figure 3 The wafer defect detection equipment also includes: a laser module 121 and a curvature acquisition module 116, wherein the laser module 121 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; the camera array 104 is also used to obtain the displacement of the light spot reflected when the detection laser 11 irradiates the surface 102 of the wafer to be detected; the curvature acquisition module 116 is used to obtain the curvature of the wafer to be detected according to the displacement of the light spot.

[0076] The laser module 121 includes a transmitting end. When measuring the curvature, the transmitting end of the laser module 121, the wafer to be detected 102 and the lens assembly of the camera array 104 are immersed in the immersion liquid 112. Since the transmission of the detection laser and the transmission of the light spot reflected when the wafer surface 102 to be detected are both in the immersion liquid 112, the energy, accuracy and resolution are high, and the loss is small, thereby improving the accuracy of the curvature measurement. In addition to the defect detection function, the wafer defect detection device of the present application also has the function of curvature detection.

[0077] The curvature acquisition module 116 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 116 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 107 when the wafer 102 to be inspected moves dx.

[0078] 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 defect detection device, characterized in that: include: Wafer stage, used to fix the wafer to be inspected; An immersion liquid providing module, used for providing an immersion liquid to immerse the wafer to be inspected on the wafer stage in the immersion liquid, wherein the refractive index of the immersion liquid is greater than the refractive index of air; An image acquisition module, wherein the image acquisition module includes a camera array, and the image acquisition module obtains a detection image corresponding to the entire surface of the wafer to be detected by shooting with the camera array at one time, and when shooting, the camera array is at least partially immersed in an immersion liquid, so that the light reflected from the surface of the wafer to be detected is transmitted through the immersion liquid and directly enters the camera array for sensing, and the image acquisition module also includes a planar substrate, a plurality of cameras are arranged in an array on the planar substrate, a plurality of through holes are provided on the planar substrate, and the opening positions of the through holes do not overlap with the cameras, and 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; An illumination device, the illumination device comprising a light source and an optical fiber transmission unit, the light source being used to emit illumination light of a specific wavelength, the optical fiber transmission unit being used to transmit the illumination light of the specific wavelength emitted by the light source to the surface of a wafer to be inspected for illumination, the optical fiber transmission unit comprising a plurality of optical fiber transmission channels, each of the optical fiber transmission channels corresponding to a perforation on the planar substrate, the illumination light output by each optical fiber transmission channel illuminating a portion of the surface of the wafer to be inspected, the entire surface of the wafer to be inspected is illuminated through the plurality of optical fiber transmission channels, thereby improving the uniformity of energy and brightness distribution of the illumination light when illuminating the surface of the wafer to be inspected, and the lower end of the illumination device is immersed in the immersion liquid; A defect judgment module is used to judge whether there are defects on the surface of the wafer to be inspected according to the inspection image obtained by the image acquisition module.

2. The wafer defect detection device according to claim 1, characterized in that: The immersion liquid supply module comprises an immersion liquid supply unit and a receiving tank, wherein the immersion liquid supply unit is used to supply the immersion liquid to the receiving tank, the receiving tank is used to receive the immersion liquid, and the wafer stage is located in the receiving tank.

3. The wafer defect detection device according to claim 2, characterized in that: The refractive index of the immersion liquid is greater than 1.

1.

4. The wafer defect detection device according to claim 3, characterized in that: The wetting liquid includes any one of deionized water, perfluoropolyether or cyclooctane, or a mixture of at least two of them.

5. The wafer defect detection device according to any one of claims 1 to 4, characterized in that: The camera array includes a lens assembly. When the image acquisition module obtains a detection image corresponding to the entire surface of the wafer to be detected by shooting with the camera array at one time, the lens assembly of the camera array is immersed in the immersion liquid.

6. The wafer defect detection device according to claim 5, characterized in that: The number of the cameras is greater than or equal to 5.

7. The wafer defect detection device according to claim 6, characterized in that: The wavelength range of the irradiation light of specific wavelength emitted by the light source is 50nm-500nm.

8. The wafer defect detection device according to claim 1, characterized in that: The wafer defect detection equipment also includes: a laser module and a curvature acquisition module, wherein the laser module is used to emit a detection laser toward the surface of the wafer to be detected when the wafer to be detected moves; the camera array is also used to obtain the displacement of the light spot reflected when the detection laser irradiates the surface of the wafer to be detected; the curvature acquisition module is used to obtain the curvature of the wafer to be detected according to the displacement of the light spot.

9. The wafer defect detection device according to claim 8, characterized in that: The laser module comprises an emitting end. When measuring the curvature, the emitting end of the laser module, the wafer to be inspected and the lens assembly of the camera array are immersed in the immersion liquid.

10. The wafer defect detection device according to claim 1, characterized in that: The wafer stage can enable the wafer to be inspected to rotate, move vertically, move horizontally, or deflect in the immersion liquid.

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