Wafer defect detection device and method

Abstract

The invention discloses a wafer defect detection device and method. The wafer defect detection device comprises a detection module, a processing module and an image reconstruction module, the detection module comprises a laser emitting unit, a transmitting mirror group, a photo-acoustic conversion unit and an acoustic-electric conversion unit; the laser emission unit emits pulse detection laser to the surface of a to-be-detected wafer, the pulse detection laser generates an optical signal with defect feature information after passing through the to-be-detected wafer, and the photoacoustic conversion unit converts the optical signal into an acoustic signal; the acoustical-electrical conversion unit converts the acoustical signal into an electrical signal; the processing module extracts defect feature information of the wafer to be detected according to the electric signal; and the image reconstruction module determines the defect of the wafer to be detected according to the defect feature information. According to the defect detection device provided by the invention, through mutual cooperation of the photoacoustic conversion unit and the acoustic-electric conversion unit, the scattered optical signal of the wafer to be detected is converted into the electric signal, so that the defect of the wafer to be detected is analyzed and processed, and the defect on the surface of the wafer to be detected can be efficiently and accurately detected.

Description

Technical Field

[0001] The present invention relates to the technical field of wafer measurement, and particularly to a device and method for detecting defects of a wafer. Background Art

[0002] Defect detection refers to the technology of detecting whether there are removable defects such as particles and non-removable defects such as grooves and scratches on the surface of a wafer, as well as the positions and quantities of the defects. The application of wafer defect detection is very extensive: on the one hand, as the chip substrate, the defects existing on the wafer may cause the failure of expensive manufacturing processes. Therefore, wafer manufacturers often perform defect detection to ensure the qualification rate of products, and wafer users also need to determine the cleanliness of the wafer before use to ensure the qualification rate of products; on the other hand, due to the very strict control of additional contamination during semiconductor processing, and it is difficult to directly monitor the additional contamination during the processing, so people often judge the degree of additional contamination of the process by comparing the defect conditions of the wafer bare chip before and after processing.

[0003] With the improvement of the manufacturing process, the size of the transistors constituting the chip is getting smaller and smaller. Wafer defect detection equipment needs to detect smaller defect sizes of the wafer, thus posing higher requirements for the accuracy and detection rate of wafer defect detection equipment. Therefore, people have explored various wafer defect detection means.

[0004] In the prior art, defects of wafers are mainly detected by electron beam detection and optical detection. However, electron beam detection takes a long time and requires a high-vacuum environment, and can only be used for sampling inspection of a few key circuit links; optical detection has many limitations, such as high requirements for light, etc. Summary of the Invention

[0005] The present invention provides a device and method for detecting defects of a wafer. Through the mutual cooperation of a photoacoustic conversion unit and an acoustic-electric conversion unit, the optical signal scattered by the wafer to be detected is converted into an electric signal, so as to analyze and process the defects of the wafer to be detected, thereby being able to efficiently and accurately detect the defects on the surface of the wafer to be detected.

[0006] According to a first aspect of the present invention, there is provided a device for detecting defects of a wafer, including: a detection module, a processing module, and an image reconstruction module;

[0007] The detection module includes: a laser emission unit, a transmissive lens group, a photoacoustic conversion unit, and an acoustic-electric conversion unit;

[0008] The laser emission unit emits pulsed detection laser to the transmissive lens group. The pulsed detection laser is converged by the transmissive lens group and then emitted to the surface of the wafer to be detected. After passing through the wafer to be detected, the pulsed detection laser generates an optical signal with defect characteristic information and is incident on the photoacoustic conversion unit;

[0009] The photoacoustic conversion unit is electrically connected to the acoustic-electric conversion unit. The photoacoustic conversion unit converts the optical signal into an acoustic signal and then transmits it to the acoustic-electric conversion unit;

[0010] The acoustic-electric conversion unit is electrically connected to the processing module. The acoustic-electric conversion unit converts the acoustic signal into an electrical signal and transmits it to the processing module;

[0011] The processing module is electrically connected to the image reconstruction module. The processing module extracts defect feature information of the wafer to be measured according to the electrical signal and transmits it to the image reconstruction module;

[0012] The image reconstruction module determines the surface topography image, defect position and size of the wafer to be measured according to the defect feature information.

[0013] Optionally, the detection module further includes a condenser unit;

[0014] The condenser unit is located between the wafer to be measured and the photoacoustic conversion unit. The condenser unit is used to converge the optical signal and transmit it to the photoacoustic conversion unit.

[0015] Optionally, the detection module further includes a mirror group; the mirror group includes a first mirror group and a second mirror group; the mirror group includes a first mirror and a second mirror;

[0016] The pulsed detection laser emitted by the laser emitting unit is transmitted through the first mirror group, reflected by the first mirror, transmitted through the second mirror group, and reflected by the second mirror in sequence, and then incident on the surface of the wafer to be measured.

[0017] Optionally, the mirror group further includes a third mirror group;

[0018] The third mirror group is located between the condenser unit and the photoacoustic conversion unit. The third mirror group is used to transmit the optical signal converged by the condenser unit to the photoacoustic conversion unit.

[0019] Optionally, it further includes a rotating platform, and the rotating platform is used to carry and rotate the wafer to be measured to realize defect detection of different regions of the wafer to be measured.

[0020] Optionally, it further includes a bracket, and the bracket is fixedly connected to the rotating platform. The bracket is used to move the rotating platform.

[0021] Optionally, the image reconstruction module includes a charge-coupled device camera or a complementary metal oxide semiconductor camera.

[0022] Optionally, the photoacoustic conversion unit includes a photoacoustic cell; the acoustic-electric conversion unit includes a microphone.

[0023] Optionally, the detection module further includes a filtering unit;

[0024] The first end of the filtering unit is connected to the photoacoustic conversion unit, and the second end of the filtering unit is connected to the acoustic-electric conversion unit.

[0025] According to a second aspect of the present invention, there is provided a method for detecting defects of a wafer, which is detected by using the wafer defect detection device according to any one of the first aspects of the present invention. The detection method includes:

[0026] The laser emission unit emits pulsed detection laser to the surface of the wafer to be measured;

[0027] The pulsed detection laser generates an optical signal with defect characteristic information after being scattered by the wafer to be measured;

[0028] The photoacoustic conversion unit converts the optical signal into an acoustic signal and then transmits it to the acoustic-electric conversion unit;

[0029] The acoustic-electric conversion unit converts the acoustic signal into an electric signal and transmits it to the processing module;

[0030] The processing module extracts the defect characteristic information of the wafer to be measured and transmits it to the image reconstruction module;

[0031] The image reconstruction module determines the surface topography image, defect position and size of the wafer to be measured according to the defect characteristic information.

[0032] The present invention discloses a defect detection device for a wafer, comprising: a detection module, a processing module, and an image reconstruction module; the detection module includes: a laser emission unit, a transmissive lens group, a photoacoustic conversion unit, and an acoustic-electric conversion unit; the laser emission unit emits pulsed detection laser to the transmissive lens group, and the pulsed detection laser is converged by the transmissive lens group and then emitted to the surface of the wafer to be detected. After passing through the wafer to be detected, the pulsed detection laser generates an optical signal with defect characteristic information and is incident on the photoacoustic conversion unit; the photoacoustic conversion unit is electrically connected to the acoustic-electric conversion unit, and the photoacoustic conversion unit converts the optical signal into an acoustic signal and then transmits it to the acoustic-electric conversion unit; the acoustic-electric conversion unit is electrically connected to the processing module, and the acoustic-electric conversion unit converts the acoustic signal into an electrical signal and transmits it to the processing module; the processing module is electrically connected to the image reconstruction module, and the processing module extracts the defect characteristic information of the wafer to be detected according to the electrical signal and transmits it to the image reconstruction module; the image reconstruction module determines the surface topography image, defect position, and size of the wafer to be detected according to the defect characteristic information. The defect detection device provided by the present invention enables the optical signal scattered by the wafer to be detected to be converted into an electrical signal through the mutual cooperation of the photoacoustic conversion unit and the acoustic-electric conversion unit, so as to analyze and process the defects of the wafer to be detected, and thus can efficiently and accurately detect the defects on the surface of the wafer to be detected.

[0033] It should be understood that the content described in this part is not intended to identify the key or important features of the embodiments of the present invention, nor is it used to limit the scope of the present invention. Other features of the present invention will become easily understood through the following description. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following will briefly introduce the drawings required for the description of the embodiments. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0035] Figure 1 is a schematic structural diagram of a defect detection device for a wafer provided by an embodiment of the present invention;

[0036] Figure 2 is a partial structural diagram of another defect detection device for a wafer provided by an embodiment of the present invention;

[0037] Figure 3 is a partial structural diagram of another defect detection device for a wafer provided by an embodiment of the present invention;

[0038] Figure 4 is a flowchart of another defect detection method for a wafer provided by an embodiment of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0039] To enable those skilled in the art to better understand the solution of the present invention, the following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the scope of protection of the present invention.

[0040] It should be noted that the terms "first", "second", etc. in the specification and claims of the present invention and the above-mentioned drawings are used to distinguish similar objects, and do not necessarily need to describe a specific order or sequence. It should be understood that such data can be interchanged under appropriate circumstances, so that the embodiments of the present invention described here can be implemented in an order other than those illustrated or described here. In addition, the terms "comprising" and "having" and any variations thereof are intended to cover non-exclusive inclusion. For example, a process, method, system, product or device comprising a series of steps or units does not necessarily have to be limited to those steps or units clearly listed, but may include other steps or units not clearly listed or inherent to these processes, methods, products or devices.

[0041] It should be understood that various forms of the flow shown above can be used, reordering, adding or deleting steps. For example, the steps described in the present invention can be executed in parallel, sequentially or in different orders, as long as the desired results of the technical solutions of the present invention can be achieved, and no limitations are imposed herein.

[0042] In the process of semiconductor manufacturing, various irregularities or abnormalities will appear on the surface or inside of the wafer, which will affect the performance and yield of the chip. The defects include but are not limited to: particle contamination, scratches, crystal defects, etc.

[0043] Therefore, it is necessary to detect the defects of the wafer. Currently, the common wafer defect detection methods mainly include two categories: electron beam detection and optical detection. Electron beam detection is a technology that uses an electron beam to perform high-resolution imaging and defect detection on the surface or inside of the wafer. Thanks to the extremely short wavelength of the electron wave, electron beam detection can directly image and the resolution can reach 1nm - 2nm. However, the detection time required is relatively long and a high-vacuum environment is needed, so it can only be used for sampling inspection of a few key circuit links; Optical detection uses optical principles to image and detect defects on the surface or inside of the wafer. Among them, the light scattering method is one of the most important optical detection methods. Its basic principle is to judge the presence and size of defects by scanning whether there is scattered light from the incident light and the detected defects and their intensities, and it has a wide range of applications in many fields, but optical detection has many limitations.

[0044] In view of the technical problems existing in the above-mentioned prior art, an embodiment of the present invention provides a wafer defect detection device. Figure 1 FIG. Figure 1 is a schematic structural diagram of a wafer defect detection device provided by an embodiment of the present invention. Referring to Figure 1 , the wafer defect detection device provided by an embodiment of the present invention includes: a detection module 1, a processing module 2, and an image reconstruction module 3; the detection module 1 includes: a laser emission unit 11, a transmissive lens group 12, a photoacoustic conversion unit 13, and an acoustic-electric conversion unit 14; the laser emission unit 11 emits pulsed detection laser to the transmissive lens group 12, and the pulsed detection laser is converged by the transmissive lens group 12 and then emitted to the surface of the wafer 4 to be detected. After passing through the wafer 4 to be detected, the pulsed detection laser generates an optical signal with defect characteristic information and is incident on the photoacoustic conversion unit 13; the photoacoustic conversion unit 13 is electrically connected to the acoustic-electric conversion unit 14, and the photoacoustic conversion unit 13 converts the optical signal into an acoustic signal and then transmits it to the acoustic-electric conversion unit 14; the acoustic-electric conversion unit 14 is electrically connected to the processing module 2, and the acoustic-electric conversion unit 14 converts the acoustic signal into an electrical signal and transmits it to the processing module 2; the processing module 2 is electrically connected to the image reconstruction module 3, and the processing module 2 extracts the defect characteristic information of the wafer 4 to be detected according to the electrical signal and transmits it to the image reconstruction module 3; the image reconstruction module 3 determines the surface topography image, defect position, and size of the wafer 4 to be detected according to the defect characteristic information.

[0045] Specifically, the defect detection device provided by the embodiments of the present invention includes a detection module 1, a processing module 2, and an image reconstruction module 3. The detection module 1 includes a laser emission unit 11, a transmissive lens group 12, a photoacoustic conversion unit 13, and an acoustic-electric conversion unit 14. The laser emission unit 11 is used to emit pulsed detection laser to detect the defects of the wafer 4 to be measured. The laser emission unit 11 provides a laser beam with high brightness, high directivity, and good monochromaticity. Exemplarily, the laser emission unit 11 can be a semiconductor pulsed laser. After the pulsed detection laser is emitted by the laser emission unit 11, it is incident on the transmissive lens group 12. The transmissive lens group 12 focuses the pulsed detection laser and then irradiates it onto the surface of the wafer 4 to be measured, thereby improving the transmission efficiency of the pulsed detection laser. The pulsed detection laser can be scattered at the defects on the surface of the wafer 4 to be measured to form scattered light. After the pulsed detection laser is scattered by the wafer 4 to be measured, an optical signal carrying the defect characteristic information of the wafer 4 to be measured is incident on the photoacoustic conversion unit 13. The concentrated optical signals carrying defect characteristic information are gathered in the photoacoustic conversion unit 13 in large quantities, resulting in the gas thermal expansion of the photoacoustic conversion unit 13 and an increase in the air pressure inside the photoacoustic conversion unit 13. Since the light intensity is periodically modulated, the air pressure in the closed photoacoustic conversion unit 13 also changes at the same frequency. Thus, the photoacoustic conversion unit 13 converts the optical signal carrying defect characteristic information into an acoustic signal, obtaining a photoacoustic signal proportional to the light intensity of the focused scattered optical signal. The acoustic signal is transmitted to the acoustic-electric conversion unit 14. The acoustic-electric conversion unit 14 is electrically connected to the processing module 2. The acoustic-electric conversion unit 14 is used to detect weak acoustic wave signals and is usually used in combination with photoacoustic spectroscopy technology. The acoustic-electric conversion unit 14 converts the acoustic signal transmitted by the photoacoustic conversion unit 13 into an electrical signal and transmits it to the processing module 2. The processing module 2 extracts the defect characteristic information of the wafer 4 to be measured from the optical signal carrying the defect characteristic signal and transmits it to the image reconstruction module 3. The image reconstruction module 3 analyzes and processes the defect characteristic information of the wafer 4 to be measured transmitted by the processing module 2. The analysis and processing techniques include but are not limited to: multi-channel data fusion, noise reduction and feature enhancement, three-dimensional topography reconstruction, etc., so as to determine the surface topography image, defect position, and size of the wafer 4 to be measured. Exemplarily, the image reconstruction module 3 can be a multi-channel scanning system, etc.

[0046] The defect detection device for wafers provided by the embodiments of the present invention enables the optical signal scattered by the wafer to be measured to be converted into an electrical signal through the mutual cooperation of the photoacoustic conversion unit and the acoustic-electric conversion unit, thereby analyzing and processing the defects of the wafer to be measured, and thus being able to efficiently and accurately detect the defects on the surface of the wafer to be measured.

[0047] Optionally, Figure 2 is a partial structural schematic diagram of another defect detection device for wafers provided by the embodiments of the present invention. Refer to Figure 2, the detection module 1 further includes a condenser unit 15; the condenser unit 15 is located between the wafer 4 to be measured and the photoacoustic conversion unit 13, and the condenser unit 15 is used to converge the optical signal and transmit it to the photoacoustic conversion unit 13.

[0048] Specifically, the detection module 1 further includes a condenser unit 15. The condenser unit 15 is located between the wafer 4 to be measured and the photoacoustic conversion unit 13. The condenser unit 15 can be a concave mirror, and the concave mirror is used to converge the pulsed detection laser scattered by the wafer 4 to be measured and incident it into the photoacoustic conversion unit 13, so that the photoacoustic conversion unit 13 receives the converged optical signal with defect feature information, and then converts the optical signal into an acoustic signal to detect the defects of the wafer 4 to be measured.

[0049] Optionally, continue to refer to Figure 2 , in the wafer defect detection device provided by the embodiment of the present invention, the detection module 1 further includes a mirror group 16; the transmissive lens group 12 includes a first transmissive lens group 121 and a second transmissive lens group 122; the mirror group 16 includes a first mirror 161 and a second mirror 162; the pulsed detection laser emitted by the laser emission unit 11 passes through the first transmissive lens group 121, is reflected by the first mirror 161, passes through the second transmissive lens group 122, and is reflected by the second mirror 162 and then is incident on the surface of the wafer 4 to be measured.

[0050] Specifically, the detection module 1 in the wafer defect detection device provided by the embodiment of the present invention further includes a mirror group 16. The transmissive lens group 12 includes a first transmissive lens group 121 and a second transmissive lens group 122. The mirror group 16 includes a first mirror 161 and a second mirror 162. The pulsed detection laser emitted by the laser emission unit 11 is incident on the first transmissive lens group 121. The first transmissive lens group 121 and the second transmissive lens group 122 can realize the control, focusing and adjustment of the pulsed detection laser, and are all composed of a combination of multiple transmissive lenses. The transmissive lens group can include a combination formed by multiple convex lenses, concave lenses and plano-convex lenses, etc. The pulsed detection laser passes through the first transmissive lens group 121 and then is incident on the first mirror 161. The first mirror 161 changes the optical path of the pulsed detection laser and incident the pulsed detection laser on the second transmissive lens group 122. The pulsed detection laser passes through the second transmissive lens group 122 and then is incident on the second mirror 162. The second mirror 162 changes the transmission optical path of the pulsed detection laser again and is incident on the surface of the wafer 4 to be measured at a first preset angle. Among them, the first preset angle can be 30°, specifically, the size of the first preset angle can be set according to needs. Through the mutual cooperation between the first transmissive lens group 121, the second transmissive lens group 122, the first mirror 161 and the second mirror 162, not only can the pulsed detection laser be incident on the surface of the wafer 4 to be measured at a first preset angle, but also the volume of the wafer defect detection device can be reduced and the detection cost can be reduced.

[0051] Optionally, continue to refer to Figure 2 , the transmissive lens group 12 further includes a third transmissive lens group 123; the third transmissive lens group 123 is located between the condenser unit 15 and the photoacoustic conversion unit 13, and the third transmissive lens group 123 is configured to transmit the light signal converged by the condenser unit 15 to the photoacoustic conversion unit 13.

[0052] Specifically, the transmissive lens group 12 further includes a third transmissive lens group 123. The third transmissive lens group 123 is located between the condenser unit 15 and the photoacoustic conversion unit 13. The third transmissive lens group 123 receives the light signal with defect feature information converged by the condenser unit 15, and a large number of converged light signals are incident into the photoacoustic conversion unit 13, so that the photoacoustic conversion unit 13 converts the light signal with defect feature information into an acoustic signal to analyze and process the defects of the wafer 4 to be measured.

[0053] Optionally, the wafer defect detection device provided by an embodiment of the present invention further includes a rotating platform 5. The rotating platform 5 is configured to carry and rotate the wafer 4 to be measured to implement defect detection on different regions of the wafer 4 to be measured.

[0054] Specifically, the defect detection device provided by an embodiment of the present invention further includes a rotating platform 5. The rotating platform 5 is mainly used to support the wafer 4 to be measured and precisely rotate the wafer 4 to be measured according to actual needs, so as to implement defect detection on different regions of the wafer 4 to be measured. Exemplarily, the rotating platform 5 can be a wafer chuck, an electrostatic chuck rotary stage, a precision rotary stage, etc.

[0055] Optionally, the wafer defect detection device provided by an embodiment of the present invention further includes a bracket 6. The bracket 6 is fixedly connected to the rotating platform 4, and the bracket 6 is used to move the rotating platform 4.

[0056] Specifically, the wafer defect detection device further includes a bracket 6. The bracket 6 is fixedly connected to the rotating platform 4, so that during the detection process of the wafer 4 to be measured, the detection stability of the wafer 4 to be measured can be improved. The bracket 6 is also used to move the rotating platform 4 to ensure the stability of the defect detection of the wafer 4 to be measured.

[0057] Optionally, the image reconstruction module 3 includes a charge-coupled device camera or a complementary metal oxide semiconductor camera.

[0058] Specifically, the image reconstruction module 3 includes a Charge-Coupled Device (CCD) camera or a Complementary Metal-Oxide-Semiconductor (CMOS) camera. The charge-coupled device camera is a semiconductor device used to capture and convert optical signals into electrical signals, and the complementary metal-oxide-semiconductor camera is used to analyze and process the electrical signals with defect feature information, so as to determine the defect morphology image, defect position and size of the wafer 4 to be measured.

[0059] Optionally, the photoacoustic conversion unit 13 includes a photoacoustic cell; the acoustic-electric conversion unit 14 includes a microphone.

[0060] Specifically, the photoacoustic conversion unit 13 includes a photoacoustic cell. The photoacoustic cell is a core component in photoacoustic spectroscopy technology and is used to convert optical signals with defect feature information into acoustic signals. The wafer 4 to be measured scatters to the photoacoustic conversion unit 13 after absorbing the pulsed detection laser, causing a local temperature rise in the photoacoustic cell and generating a pressure wave. The acoustic wave signal is detected through a piezoelectric sensor, and then the defects on the surface of the wafer 4 to be measured are analyzed and processed; the acoustic-electric conversion unit 14 can be a microphone. The acoustic signal in the photoacoustic conversion unit 13 acts on the diaphragm of the microphone, causing the diaphragm to vibrate. The vibration of the diaphragm is converted into an electrical signal (such as capacitance change, piezoelectric effect), and the electrical signal is amplified and processed and output as a data electrical signal that can be processed by the processing module 2.

[0061] Figure 3 It is a schematic diagram of a partial structure of another wafer defect detection device provided by an embodiment of the present invention. Refer to Figure 3 Optionally, the detection module 1 further includes a filtering unit 17; the first end of the filtering unit 17 is connected to the photoacoustic conversion unit 13, and the second end of the filtering unit 17 is connected to the acoustic-electric conversion unit 14.

[0062] Specifically, the detection module 1 further includes a filtering unit 17. The first end of the filtering unit 17 is connected to the photoacoustic conversion unit 13, and the second end of the filtering unit 17 is connected to the acoustic-electric conversion unit 14. The filtering unit 17 is mainly used to filter out the clutter signals in the acoustic signals transmitted in the photoacoustic conversion unit 13, so as to make the defect detection of the wafer 4 to be measured more accurate and fast.

[0063] According to the same inventive concept, Figure 4 It is a flowchart of a wafer defect detection method provided by an embodiment of the present invention. Refer to Figure 4 An embodiment of the present invention provides a wafer defect detection method. A wafer defect detection method uses the wafer defect detection device in any of the above-mentioned inventive embodiments for detection. The detection method includes:

[0064] S101. The laser emission unit emits pulsed detection laser to the surface of the wafer to be measured.

[0065] Specifically, the laser emission unit emits pulsed detection laser for detecting surface defects of the wafer to be measured, and after passing through the first transmissive lens group, the first reflector, the second transmissive lens group and the second reflector in sequence, it is incident on the surface of the wafer to be measured.

[0066] S102. The pulsed detection laser generates an optical signal with defect characteristic information after being scattered by the wafer to be measured.

[0067] Specifically, in the above step S101, after the pulsed detection laser is incident on the surface of the wafer to be measured, if there are no defects on the surface of the wafer to be measured, the pulsed detection laser will be reflected to the outside at a fixed angle; if there are defects on the surface of the wafer to be measured, the pulsed detection laser will be scattered and converted into an optical signal with defect characteristic information on the surface of the wafer to be measured and transmitted to the photoacoustic conversion unit. Among them, the defect characteristic information includes but is not limited to: particle contamination, scratches, crystal defects, etc.

[0068] S103. The photoacoustic conversion unit converts the optical signal into an acoustic signal and then transmits it to the acoustic-electric conversion unit.

[0069] Specifically, after the optical signal with defect characteristic information scattered by the wafer to be measured in the above step S102 is transmitted to the photoacoustic conversion unit, it causes the gas in the photoacoustic conversion unit to thermally expand, thereby causing the air pressure in the photoacoustic conversion unit to increase. Since the optical intensity of the optical signal with defect characteristic information is periodically modulated, the air pressure in the photoacoustic conversion unit also changes at the same frequency, thereby forming an acoustic signal.

[0070] S104. The acoustic-electric conversion unit converts the acoustic signal into an electric signal and transmits it to the processing module.

[0071] Specifically, after the photoacoustic conversion unit in the above step S103 converts the optical signal with defect characteristic information into an acoustic signal and transmits it to the acoustic-electric conversion unit, the acoustic-electric conversion unit performs conversion according to the acoustic signal, generates an electric signal and transmits it to the processing module.

[0072] Optionally, before the acoustic signal is transmitted to the acoustic-electric conversion unit, it further includes:

[0073] Filtering the acoustic signal through a filtering unit.

[0074] Specifically, the acoustic signal converted by the photoacoustic conversion unit in the above step S103 is first transmitted to the filtering unit, and after being filtered by the filtering unit, it is then transmitted to the acoustic-electric conversion unit, thereby improving the efficiency and accuracy of defect detection of the wafer 4 to be measured.

[0075] S105. The processing module extracts the defect feature information of the wafer to be measured and transmits it to the image reconstruction module.

[0076] Specifically, in the above step S104, after the acoustic-electric conversion unit converts the acoustic signal into an electric signal with defect feature information, it is transmitted to the processing module. The processing module analyzes and processes the electric signal with defect feature information, extracts the defect feature information of the wafer to be measured, and then transmits it to the image reconstruction module.

[0077] S106. The image reconstruction module determines the surface topography image, defect position and size of the wafer to be measured according to the defect feature information.

[0078] Specifically, after receiving the defect feature information of the wafer to be measured transmitted by the processing module, the image reconstruction module performs image reconstruction according to the defect feature information, so as to determine the surface topography image, defect position and size of the wafer to be measured. Among them, the analysis and processing techniques in the image reconstruction module include but are not limited to: multi-channel data fusion, noise reduction and feature enhancement, three-dimensional topography reconstruction, etc.

[0079] The wafer defect detection method provided by the embodiment of the present invention can achieve the same technical effect as the wafer defect detection device in any of the above-mentioned embodiments of the invention, which will not be elaborated here.

[0080] The above specific implementation manners do not constitute a limitation to the protection scope of the present invention. Those skilled in the art should understand that various modifications, combinations, sub-combinations and substitutions can be made according to design requirements and other factors. Any modifications, equivalent substitutions and improvements made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A wafer defect detection device, characterized in that: include: Detection module, processing module and image reconstruction module; The detection module includes: a laser emitting unit, a transmission lens group, a photoacoustic conversion unit and an acoustic-electric conversion unit; The laser emitting unit emits a pulse detection laser to the transmission mirror group, and the pulse detection laser is converged by the transmission mirror group and then emitted to the surface of the wafer to be tested. After passing through the wafer to be tested, the pulse detection laser generates an optical signal with defect feature information and is incident on the photoacoustic conversion unit; The photoacoustic conversion unit is electrically connected to the acoustic-electric conversion unit, and the photoacoustic conversion unit converts the optical signal into an acoustic signal and transmits the acoustic signal to the acoustic-electric conversion unit; The acoustic-to-electric conversion unit is electrically connected to the processing module, and the acoustic-to-electric conversion unit converts the acoustic signal into an electrical signal and transmits the electrical signal to the processing module; The processing module is electrically connected to the image reconstruction module, and the processing module extracts defect feature information of the wafer to be tested according to the electrical signal and transmits the information to the image reconstruction module; The image reconstruction module determines the surface topography image, defect position and size of the wafer to be tested according to the defect feature information.

2. The wafer defect detection device according to claim 1, characterized in that: The detection module also includes a light focusing unit; The light focusing unit is located between the wafer to be tested and the photoacoustic conversion unit, and is used for focusing the light signal and transmitting it to the photoacoustic conversion unit.

3. The wafer defect detection device according to claim 1, characterized in that: The detection module further comprises a reflector group; the transmission mirror group comprises a first transmission mirror group and a second transmission mirror group; the reflector group comprises a first reflector and a second reflector; The pulse detection laser emitted by the laser emitting unit is sequentially transmitted by the first transmission mirror group, reflected by the first reflection mirror, transmitted by the second transmission mirror group, and reflected by the second reflection mirror before being incident on the surface of the wafer to be tested.

4. The wafer defect detection device according to claim 2, characterized in that: The transmission lens group further includes a third transmission lens group; The third transmission mirror group is located between the light focusing unit and the photoacoustic conversion unit, and the third transmission mirror group is used to transmit the optical signal focused by the light focusing unit to the photoacoustic conversion unit.

5. The wafer defect detection device according to claim 1, characterized in that: It also includes a rotating platform, which is used to carry and rotate the wafer to be tested to achieve defect detection in different areas of the wafer to be tested.

6. The wafer defect detection device according to claim 5, characterized in that: It also includes a bracket, which is fixedly connected to the rotating platform and is used to move the rotating platform.

7. The wafer defect detection device according to claim 1, characterized in that: The image reconstruction module includes a charge coupled device camera or a complementary metal oxide semiconductor camera.

8. The wafer defect detection device according to claim 1, characterized in that: The photoacoustic conversion unit includes a photoacoustic cell; the acoustic-electric conversion unit includes a microphone.

9. The wafer defect detection device according to claim 1, characterized in that: The detection module also includes a filtering unit; The first end of the filter unit is connected to the photoacoustic conversion unit, and the second end of the filter unit is connected to the acoustic-electric conversion unit.

10. A wafer defect detection method, characterized in that: The wafer defect detection device according to any one of claims 1 to 9 is used for detection, and the detection method comprises: The laser emitting unit emits a pulse detection laser to the surface of the wafer to be tested; The pulse detection laser generates an optical signal with defect feature information after being scattered by the wafer to be tested; The photoacoustic conversion unit converts the optical signal into an acoustic signal and transmits the acoustic signal to the acoustic-electric conversion unit; The acoustic-to-electric conversion unit converts the acoustic signal into an electrical signal and transmits the electrical signal to the processing module; The processing module extracts the defect feature information of the wafer to be tested and transmits it to the image reconstruction module; The image reconstruction module determines the surface topography image, defect position and size of the wafer to be tested according to the defect feature information.

Images