Dark field illumination system for front and back wafer detection and wafer detection system
By adopting an upper and lower symmetric front and back systems in the wafer detection system, combining blowing and suction structures, the wafer is kept flat, and using an annular light source and waveguide cone to provide dark field lighting, the image blur problem caused by wafer deformation is solved, and high-precision front and back detection is achieved.
Patent Information
- Application Number
- CN202422461587.8
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-10-11
- Publication Date
- 2025-08-22
- Estimated Expiration
- 2034-10-11
AI Technical Summary
During the wafer production process, the wafer is prone to deformation due to the lack of support structure during the detection process, resulting in blurred image and affecting the detection effect. At the same time, it is difficult for the prior art to conduct high-precision detection of the front and back of the wafer at the same time.
The front and back systems with up and down symmetrical arrangements are equipped with support devices and lighting devices respectively. The blowing and suction structures are used to keep the wafer flat, and dark field lighting is provided through an annular light source, annular light concentrating rod and a waveguide cone to ensure clear image acquisition.
The wafer is leveled during the detection process, avoiding image blur, improving detection accuracy, and saving space, cost and energy consumption through compact system design.
Smart Images
Figure CN223259550U_ABST
Abstract
Description
Technical Field
[0001] The utility model relates to the technical field of optical testing, in particular to a dark field illumination system for front and back wafer detection and a wafer detection system. Background Art
[0002] During the wafer production process, qualified wafers must be screened to ensure product yield. To ensure electrical performance, electrical testing is typically performed using probes. After electrical testing, defects such as probe marks are inevitable on the wafers. To avoid secondary damage to the wafers, non-contact measurement is typically used. Because probe marks are small and shallow, darkfield illumination is required for inspection.
[0003] In addition to the conventional inspection of the front side of the wafer, in order to ensure the yield of the subsequent process flow, it is necessary to ensure that there are no back defects between the wafer chip and the blue film, so the back side of the wafer is also required to be inspected.
[0004] Due to the small size of the grains on the wafer and the small size of the defects that need to be detected, a high-magnification imaging system is required. This imaging system usually has a small depth of field, which requires ensuring that the inspection surface cannot bend or deform. However, after cutting, the wafer is mounted on the blue film. The blue film itself is relatively soft and easily deformed without a supporting structure. If the degree of deformation exceeds the depth of field of the lens, the image will not be clear, affecting the inspection effect.
[0005] The above content is only used to assist in understanding the technical solution of the present invention and does not constitute an admission that the above content is prior art. Utility Model Content
[0006] The utility model provides a dark field illumination system for front and back side wafer inspection and a wafer inspection system, aiming to provide dark field illumination for front and back side wafer inspection while keeping the wafer flat during the inspection process.
[0007] To achieve the above-mentioned object, the present invention proposes a dark field illumination system for front-side and back-side wafer inspection, comprising: a front-side system and a back-side system symmetrically arranged in an upper and lower direction; wherein both the front-side system and the back-side system are provided with a support device, and an illumination device nested in the support device;
[0008] The lighting device comprises an annular light source, an annular focusing rod and a waveguide cone; and the annular focusing rod and the waveguide cone are sequentially arranged between the annular light source and the light outlet of the supporting device;
[0009] The support device of the front system is provided with several ventilation holes around the light outlet, which are connected to the blowing and suction mechanism; the support device of the back system is provided with a microporous device around the light outlet, which is connected to the blowing and suction mechanism, and the light outlet of the support device of the back system is provided with a window glass for placing the wafer.
[0010] Optionally, the upper surface of the microporous device is flush with the upper surface of the window glass.
[0011] Optionally, the annular light source is an LED light source.
[0012] Optionally, the refractive index of light in the annular focusing rod ranges from 1.4 to 1.9;
[0013] And / or, the refractive index of light in the waveguide cone ranges from 1.4 to 1.9.
[0014] Optionally, the angle between the inclined surface of the waveguide cone and the working surface ranges from 45° to 65°.
[0015] Optionally, the upper portion of the support device is a frustum, and the lower portion is a cylinder, and the light outlet is provided on the surface of the frustum.
[0016] The present invention further proposes a wafer inspection system, which includes a front-side image acquisition device, a back-side image acquisition device, a dark-field lighting system and a control device; wherein the front-side image acquisition device, the back-side image acquisition device and the dark-field lighting system all establish a communication connection with the control device; the dark-field lighting system is the dark-field lighting system for front-side and back-side wafer inspection as described above.
[0017] The beneficial effects of the technical solution of the present utility model are: providing a dark field lighting system for front and back side wafer inspection, while providing dark field lighting for front and back side wafer inspection, the blowing structure of the front side system and the suction structure of the back side system can effectively keep the wafer flat during the inspection process, avoiding the situation where the degree of wafer deformation exceeds the depth of field of the lens, resulting in the inability to subsequently collect a clear image and affecting the wafer inspection results; at the same time, the structure of the entire dark field lighting system is compact, which can greatly reduce the volume of the light source, thereby bringing many advantages, such as saving space, improving integration, reducing costs, optimizing light source efficiency and reducing energy consumption. BRIEF DESCRIPTION OF THE DRAWINGS
[0018] Figure 1 This is a schematic cross-sectional view of an embodiment of a dark field illumination system for front-side and back-side wafer inspection according to the present invention;
[0019] Figure 2 A structural perspective diagram of a support device of a front-side system of an embodiment of a dark-field illumination system for front-side and back-side wafer inspection according to the present invention;
[0020] Figure 3 A structural perspective diagram of a backside system support device of an embodiment of a dark field illumination system for front-side and backside wafer inspection according to the present invention;
[0021] Figure 4This is a schematic diagram of dark field illumination light according to an embodiment of a dark field illumination system for front-side and back-side wafer inspection according to the present invention.
[0022] Description of reference numerals:
[0023] 1. Support device of the front system; 2. Support device of the back system; 3. Ring light source; 4. Ring focusing rod; 5. Waveguide cone; 6. Light outlet; 7. Vent; 8. Micropore device.
[0024] The realization of the purpose, functional features and advantages of the present invention will be further explained in conjunction with embodiments and with reference to the accompanying drawings. DETAILED DESCRIPTION
[0025] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the schemes in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.
[0026] It should be noted that all directional indications (such as up, down, left, right, front, back, etc.) in the embodiments of the present invention are only used to explain the relative position relationship, movement status, etc. between the various components under a certain specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indication will also change accordingly.
[0027] It should also be noted that when an element is referred to as being "fixed on" or "disposed on" another element, it may be directly on the other element or there may be an intermediate element. When an element is referred to as being "connected to" another element, it may be directly connected to the other element or there may be an intermediate element.
[0028] In addition, if the description of "first", "second", etc. in the present invention is only used for descriptive purposes (such as to distinguish the same or similar elements), it should not be understood as indicating or implying their relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of such features. In addition, the technical solutions between the various embodiments can be combined with each other, but they must be based on the fact that they can be implemented by ordinary technicians in this field. When the combination of technical solutions is contradictory or cannot be implemented, it should be deemed that such a combination of technical solutions does not exist and is not within the scope of protection required by the present invention.
[0029] The utility model proposes a dark field illumination system for front and back wafer inspection, referring to Figures 1 to 3The dark field illumination system for front- and back-side wafer inspection includes a front system and a back system symmetrically arranged in an upper and lower direction; wherein both the front system and the back system are provided with a support device and an illumination device nested in the support device;
[0030] The lighting device includes an annular light source 3, an annular focusing rod 4 and a waveguide cone 5; and the annular focusing rod 4 and the waveguide cone 5 are sequentially arranged between the annular light source 3 and the light outlet 6 of the supporting device;
[0031] The support device 1 of the front system is provided with a plurality of ventilation holes 7 connected to the blowing and suction mechanism around the light outlet 6; the support device 2 of the back system is provided with a microporous device 8 connected to the blowing and suction mechanism around the light outlet 6, and the support device 2 of the back system is provided with a window glass for placing the wafer at the light outlet 6.
[0032] In this embodiment, the lighting device of the front system is nested in the supporting device 1 of the front system; the lighting device of the back system is nested in the supporting device 2 of the back system.
[0033] In the front system and the back system that are symmetrically arranged in the upper and lower parts, the light outlet 6 of the support device 1 of the front system faces the back system, and the light outlet 6 of the support device 2 of the back system faces the front system.
[0034] Both the front and rear lighting systems include a ring light source 3, a ring focusing rod 4, and a waveguide cone 5. The ring focusing rod 4 and waveguide cone 5 of each lighting device are sequentially positioned between the ring light source 3 and the light outlet 6 of the support device. The ring light source 3 emits light, while the ring focusing rod 4 collimates the light emitted by the ring light source 3 and transmits it to the waveguide cone 5. The waveguide cone 5 then directs the transmitted light at a specific angle (the light undergoes total internal reflection within the waveguide cone 5) and exits the light outlet 6 of the support device.
[0035] Around the light outlet 6 of the support device 1 of the front system, a plurality of air vents 7 connected to the blowing and suction mechanism are provided (each air vent 7 can be connected to a corresponding air pipe provided by the blowing and suction mechanism, and the blowing and suction mechanism can be provided with blowing by an air pump).
[0036] A microporous device 8 connected to a blowing and sucking mechanism is provided around the light outlet 6 of the support device 2 of the back system, and a window glass for placing wafers is provided at the light outlet 6 of the support device 2 of the back system.
[0037] Among them, the air vent 7 and the microporous device 8 can be connected to the same blowing and sucking mechanism, and the two can be blown or sucked at the same time through the blowing and sucking mechanism (which can be done in a vacuum environment); or, the air vent 7 and the microporous device 8 are respectively connected to different blowing and sucking mechanisms, and the two can be blown or sucked at the same time through different blowing and sucking mechanisms (which can be done in a vacuum environment), or when the air vent 7 is sucked, the microporous device 8 is also blown (which can be done in a vacuum environment), or when the air vent 7 is blown, the microporous device 8 is also sucked.
[0038] It is preferred that when blowing air into the vent holes 7 , air is also sucked into the microporous device 8 . This preferred embodiment will be described below as an example.
[0039] When inspecting wafers using a dark-field illumination system for both front- and back-side wafer inspection, the wafer is placed on the window glass. The front-side system's air blowing mechanism blows air into the wafer through vents 7, while the back-side system's air suction mechanism draws air from the wafer through microporous devices 8. This helps to flatten the wafer against the back-side system's window glass, preventing it from bending or deforming due to the blue film. Using microporous devices 8 for air suction ensures uniform airflow at all locations, preventing damage to the wafer due to uneven suction.
[0040] The microporous device 8 is provided with a plurality of ventilation micropores, the aperture of the ventilation micropores is smaller than the aperture of the ventilation hole 7 ; and the number of the ventilation micropores is greater than the number of the ventilation holes 7 .
[0041] Optionally, the microporous device 8 is preferably annular microporous ceramic.
[0042] The blowing structure of the front system and the suction structure of the back system can effectively keep the wafer flat, prevent image blurring due to deformation, and improve detection accuracy.
[0043] Then, refer to Figure 4 , the annular light source 3 emits light that passes through the annular focusing rod 4. Since the annular focusing rod 4 has a different refractive index from that of air and has a positive refractive power, the emitted light is converged. After the converged light enters the waveguide cone, if parallel light is formed, it is directly reflected to the outside by the angled inner wall at the bottom of the cone; while non-parallel light passes through the upper part of the waveguide cone and is reflected multiple times until it is emitted to the outside of the cone. In this way, the light emitted by the annular light source 3 is collected and shaped into a low-angle beam that is projected onto the wafer to form dark field illumination light. The design of the waveguide cone 5 ensures that the light evenly illuminates the wafer at a low angle, reducing the shadow and reflection problems that may be caused by traditional lighting methods, thereby more effectively highlighting tiny defects on the wafer surface.
[0044] At this time, the dark field illumination provided by the front-side system is used to capture images of the front side of the wafer, while the dark field illumination provided by the back-side system is used to capture images of the back side of the wafer. Image processing technology can be used to analyze the captured front and back side images of the wafer to detect defects such as blemishes, pinholes, scratches, and contamination on the wafer surface.
[0045] In one embodiment, a dark field illumination system for front-side and back-side wafer inspection is provided. While providing dark field illumination for front-side and back-side wafer inspection, the blowing structure of the front-side system and the suction structure of the back-side system can effectively keep the wafer flat during the inspection process, thereby avoiding the situation where the degree of wafer deformation exceeds the depth of field of the lens, resulting in the inability to subsequently capture a clear image and affecting the wafer inspection results. At the same time, the structure of the entire dark field illumination system is compact, which can greatly reduce the size of the light source, thereby bringing many advantages, such as saving space, improving integration, reducing costs, optimizing light source efficiency and reducing energy consumption.
[0046] In one embodiment, based on the above embodiment, the upper surface of the micro-hole device 8 is flush with the upper surface of the window glass to prevent the wafer from sinking downward.
[0047] In one embodiment, based on the above embodiment, the annular light source 3 is an LED light source.
[0048] In this embodiment, the LED light source is a Lambertian light source with a large divergence angle. The light intensity distribution is approximately Gaussian, with most of the energy concentrated in the center of the irradiated area. To improve energy utilization, an annular focusing rod 4 is used to converge the emitted light source so that the entire light beam enters the waveguide cone 5.
[0049] Optionally, the refractive index of the light in the annular focusing rod 4 is in the range of 1.4 to 1.9, preferably 1.5 to 1.6;
[0050] And / or, the refractive index of light in the waveguide cone 5 is in the range of 1.4 to 1.9, preferably 1.5 to 1.6.
[0051] In one embodiment, optimizing the LED light source design using an annular focusing rod 4 and waveguide cone 5 can significantly improve light energy utilization and enhance lighting effects. Selecting an appropriate refractive index helps optimize light transmission and shaping, reducing light loss and improving beam quality. This design not only enhances the performance of the dark-field illumination system, but also improves image quality and detection accuracy.
[0052] In one embodiment, based on the above embodiment, the angle between the inclined surface and the working surface of the waveguide cone 5 is in the range of 45° to 65°.
[0053] In this embodiment, the light undergoes total internal reflection in the waveguide cone 5. The inclined surface of the waveguide cone 5 forms an angle of 45° to 65° with the working surface, so that the light enters the working surface at an angle of (0, 40°).
[0054] Optionally, the angle between the inclined surface and the working surface is preferably 55°.
[0055] This effectively achieves total internal reflection of light and optimizes the use of light energy. This design helps improve the performance of the lighting system, ensures uniform light distribution, reduces light loss, and improves beam quality, thereby enhancing overall detection results.
[0056] In one embodiment, based on the above embodiment, the upper portion of the support device is a frustum and the lower portion is a cylinder, and the light outlet 6 is provided on the surface of the frustum.
[0057] In this embodiment, the frustum portion of the support device is used to accommodate the waveguide cone 5 , and the cylindrical portion is used to accommodate the annular light source 3 and the annular focusing rod 4 .
[0058] This support device design combines a frustum with a cylinder and strategically arranges a ring light source 3, an annular focusing rod 4, and a waveguide cone 5 to achieve light collimation, optimized transmission, and specific angled emission. This not only improves light energy utilization and lighting effects, but also ensures the stability and efficiency of the optical system. This design effectively enhances overall system performance and is suitable for applications requiring precise light control and efficient lighting.
[0059] The present invention further proposes a wafer inspection system, which includes a front image acquisition device, a back image acquisition device, a dark field lighting system and a control device; wherein the front image acquisition device, the back image acquisition device and the dark field lighting system all establish communication connections with the control device and are controlled by the control device; the specific structure of the dark field lighting system refers to the dark field lighting system for front and back wafer inspection provided in the above-mentioned embodiment. Since the present wafer inspection system adopts all the technical solutions of all the above-mentioned embodiments, it has at least all the technical effects brought about by the technical solutions of the above-mentioned embodiments, which will not be repeated here one by one.
[0060] Optionally, after providing corresponding dark field lighting for the front and back sides of the wafer respectively based on the dark field lighting system, the front side image of the wafer is collected based on the front side image acquisition device, and the back side image of the wafer is collected based on the back side image acquisition device, and then the front and back side images of the wafer are transmitted to the control device, and the control device performs image processing and analysis on the front and back side images of the wafer (or the control device calls an external computing device to perform image processing and analysis on the front and back side images of the wafer) to identify and analyze features and defects in the image.
[0061] Optionally, image processing includes image denoising, contrast enhancement, feature extraction, etc., to better identify details in the image; image analysis uses various analysis techniques such as defect detection, dimension measurement, pattern recognition, etc. to analyze the processed image to evaluate the quality and status of the wafer.
[0062] Among them, dark field illumination enhances the contrast and details of the image, making the defects and features of the wafer more obvious, thereby improving the accuracy of detection.
[0063] Through automated image processing and analysis, defects and features can be quickly and accurately identified, improving inspection efficiency. Furthermore, by analyzing images of the front and back sides of wafers, production problems can be promptly identified, allowing adjustments and optimizations to be made, thereby improving production quality.
[0064] The wafer inspection system based on darkfield illumination provides an efficient quality inspection solution by performing darkfield illumination, image acquisition, transmission, processing, and analysis on the front and back sides of wafers. This inspection system is designed to enhance image contrast and detail, making wafer defect detection more accurate. It also improves inspection efficiency and quality control through automated image processing and analysis.
[0065] The above description is only part or preferred embodiments of the present invention. Neither the text nor the drawings can limit the scope of protection of the present invention. All equivalent structural transformations made by using the contents of the present invention specification and drawings under the overall concept of the present invention, or direct / indirect application in other related technical fields are included in the scope of protection of the present invention.
Claims
1. A dark field illumination system for front and back wafer inspection, characterized in that: include: A front system and a back system are symmetrically arranged in an upper and lower manner; wherein both the front system and the back system are provided with a support device and a lighting device nested in the support device; The lighting device comprises an annular light source, an annular focusing rod and a waveguide cone; and the annular focusing rod and the waveguide cone are sequentially arranged between the annular light source and the light outlet of the supporting device; The support device of the front system is provided with several ventilation holes around the light outlet, which are connected to the blowing and suction mechanism; the support device of the back system is provided with a microporous device around the light outlet, which is connected to the blowing and suction mechanism, and the light outlet of the support device of the back system is provided with a window glass for placing the wafer.
2. The dark field illumination system for front and back wafer inspection according to claim 1, wherein: The upper surface of the microporous device is flush with the upper surface of the window glass.
3. The dark field illumination system for front and back wafer inspection according to claim 1, wherein: The annular light source adopts an LED light source.
4. The dark field illumination system for front and back wafer inspection according to claim 1, wherein: The refractive index of light in the annular focusing rod ranges from 1.4 to 1.9; And / or, the refractive index of light in the waveguide cone ranges from 1.4 to 1.
9.
5. The dark field illumination system for front and back wafer inspection according to claim 1 or 4, characterized in that: The angle between the inclined surface of the waveguide cone and the working surface ranges from 45° to 65°.
6. The dark field illumination system for front-side and back-side wafer inspection according to claim 1, wherein: The upper part of the support device is a frustum, and the lower part is a cylinder. The light outlet is arranged on the surface of the frustum.
7. A wafer inspection system, characterized in that: It includes a front image acquisition device, a back image acquisition device, a dark field lighting system and a control device; wherein the front image acquisition device, the back image acquisition device and the dark field lighting system all establish a communication connection with the control device; the dark field lighting system is a dark field lighting system for front and back wafer inspection as described in any one of claims 1-6.