Apparatus for detecting defects on a wafer

Abstract

The application discloses a device for detecting wafer defects, comprising: a distributed multi-wavelength light source module, including at least two groups of independent wavelength light source units, each group of independent wavelength light source units respectively providing light of one wavelength; a light path direction changing module, changing the direction of light emitted from each group of independent wavelength light source units; a light spot shaping module, shaping the light via the light path direction changing module and guiding the light to a wafer to be detected; and an image acquisition module, including multiple groups of image acquisition channels arranged side by side, each group of image acquisition channels respectively acquiring light of different wavebands reflected and photo-excited via the wafer to be detected, so as to realize defect detection of the wafer to be detected. Through the structural design of the multiple light path channels in parallel, the application can realize synchronous acquisition of multi-light path data and simultaneous detection of wafer defects by the multiple light path channels, thereby improving the detection efficiency of wafer defects and the integration of the detection equipment, and reducing the detection time consumption and the placement cost of the detection equipment.

Description

Technical Field

[0001] This application relates to the field of semiconductor inspection technology, and more specifically, to an apparatus for detecting wafer defects. Background Technology

[0002] Semiconductor automation equipment is particularly known for its high precision and efficiency. However, traditional single-path semiconductor inspection equipment is limited by the number of optical paths, resulting in low inspection efficiency and failing to meet the capacity requirements of Industry 4.0 production lines (≥10 wafers / hour). While combining multiple semiconductor inspection equipment can improve inspection efficiency, it also increases the equipment's footprint and installation costs. Utility Model Content

[0003] In response to at least one defect or improvement requirement in the prior art, this application provides an apparatus for detecting wafer defects, aiming to improve semiconductor detection efficiency and the integration of detection equipment.

[0004] To achieve the above objectives, in a first aspect, this application provides an apparatus for detecting wafer defects, comprising:

[0005] The distributed multi-wavelength light source module includes at least two sets of independent wavelength light source units, each set of independent wavelength light source units providing a wavelength of light;

[0006] The optical path direction changing module changes the direction of light emitted from each group of independent wavelength light source units;

[0007] The light spot shaping module shapes the light that has passed through the light path direction changing module and guides it to the wafer to be inspected;

[0008] The image acquisition module includes multiple sets of image acquisition channels arranged side by side. Each set of image acquisition channels acquires light of different wavelengths reflected and photoexcited by the wafer under test, so as to realize the defect detection of the wafer under test.

[0009] Furthermore, each image acquisition channel includes a corresponding objective lens, lens barrel, and camera arranged sequentially.

[0010] Furthermore, at least two sets of image acquisition channels share a set of objective lenses and beam splitters, and behind the beam splitter, each set of shared image acquisition channels is equipped with a corresponding lens barrel and camera.

[0011] Furthermore, the light provided by each group of independent wavelength light source units is laser light.

[0012] Furthermore, the spot shaping module includes a spot shaping module reflector, a first aperture mechanism, a second aperture mechanism, a Powell prism group, and a window lens arranged sequentially.

[0013] The beam shaping module's reflector is used to reflect and guide the beam to the target path;

[0014] The first and second aperture mechanisms are used to define the effective spot size;

[0015] Powell prisms are used to convert a beam of light into a uniformly distributed linear spot.

[0016] A window lens is used to adjust the position of the light spot projection.

[0017] Furthermore, the light spot shaping module also includes a polarizing prism disposed between the first aperture mechanism and the second aperture mechanism for adjusting the light spot intensity.

[0018] Furthermore, the optical path direction changing module includes a high-reflectivity mirror;

[0019] The reflective surface of the high-reflectivity mirror is coated with a film with a reflectivity of not less than 98%.

[0020] Furthermore, the optical path direction changing module also includes an adjustment mechanism containing a micro-motion platform, through which the orientation of the high-reflectivity mirror can be adjusted.

[0021] Secondly, this application provides an apparatus for detecting wafer defects, comprising:

[0022] The light source module provides a light of a specific wavelength.

[0023] The optical path direction changing module changes the direction of light emitted from the light source module;

[0024] The light spot shaping module shapes the light that has passed through the light path direction changing module and guides it to the wafer to be inspected;

[0025] The image acquisition module includes multiple sets of image acquisition channels arranged side by side. Each set of image acquisition channels acquires light of different wavelengths reflected and photoexcited by the wafer under test, so as to realize the defect detection of the wafer under test.

[0026] Furthermore, at least two sets of image acquisition channels share a set of objective lenses and beam splitters, and behind the beam splitter, each set of shared image acquisition channels is equipped with a corresponding lens barrel and camera.

[0027] In summary, compared with the prior art, the above-described technical solutions conceived in this application can achieve the following beneficial effects:

[0028] This application, through a multi-optical-path parallel structural design, enables synchronous acquisition of multi-optical-path data and simultaneous detection of wafer defects by multiple optical-path channels, thereby improving the detection efficiency of wafer defects and the integration of the detection equipment, and reducing the detection time and the installation cost of the detection equipment. Attached Figure Description

[0029] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0030] Figure 1 A front view of a device for parallel detection of wafer defects via multiple optical paths, provided in an embodiment of this application;

[0031] Figure 2 This is a structural diagram of the distributed multi-wavelength light source module and the optical path direction changing module provided in the embodiments of this application;

[0032] Figure 3 This is a structural diagram of the spot shaping module provided in an embodiment of this application;

[0033] Figure 4 This is a structural diagram of the image acquisition module provided in an embodiment of this application; Attached image description:

[0035] 1-Distributed multi-wavelength light source module; 2-Optical path direction changing module;

[0036] 3-Spot shaping module; 4-Image acquisition module; 5-Wafer to be inspected;

[0037] 11 - First independent wavelength light source unit; 12 - Second independent wavelength light source unit;

[0038] 211-First two-dimensional adjustment mechanism; 212-First high-reflectivity mirror;

[0039] 221 - Second two-dimensional adjustment mechanism; 222 - Second high-reflectivity mirror;

[0040] 231 - Third two-dimensional adjustment mechanism; 232 - Third high-reflectivity mirror;

[0041] 241 - Fourth two-dimensional adjustment mechanism; 242 - Fourth high-reflectivity mirror;

[0042] 311 - First aperture mechanism; 312 - Second aperture mechanism; 32 - Powell prism assembly;

[0043] 33-Window lens; 34-Spot shaping module reflector; 35-Polarizing prism;

[0044] 411 - First objective lens; 412 - Second objective lens;

[0045] 421 - First beam splitter; 422 - Second beam splitter;

[0046] 431 - First telescope tube; 432 - Second telescope tube; 433 - Third telescope tube; 434 - Fourth telescope tube;

[0047] 441 - First camera; 442 - Second camera; 443 - Third camera; 444 - Fourth camera. Detailed Implementation

[0048] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application. Furthermore, the technical features involved in the various embodiments described below can be combined with each other as long as they do not conflict with each other.

[0049] The terms "first," "second," or "nth," etc., used in the specification, claims, or accompanying drawings of this application are used to distinguish different objects, not to describe a particular order. Furthermore, the terms "comprising" or "having," and any variations thereof, are intended to cover non-exclusive inclusion. For example, a process, method, system, product, or apparatus that includes a series of steps or units is not limited to the listed steps or units, but may optionally include steps or units not listed, or may optionally include other steps or units inherent to such processes, methods, products, or apparatus.

[0050] As described in the background section of this specification, traditional single-path semiconductor inspection equipment suffers from low inspection efficiency due to the limited number of optical paths. While combining multiple semiconductor inspection devices can improve inspection efficiency, it also increases the equipment's footprint and installation costs. Therefore, this application proposes a device for detecting wafer defects, aiming to improve both semiconductor inspection efficiency and the integration of inspection equipment.

[0051] refer to Figures 1-4 One embodiment of this application provides a device for parallel detection of wafer defects using multiple optical channels. The device may specifically include a distributed multi-wavelength light source module 1, an optical path direction changing module 2, a spot shaping module 3, and an image acquisition module 4.

[0052] The distributed multi-wavelength light source module 1 includes at least two sets of independent wavelength light source units, each set of independent wavelength light source units providing a wavelength of light.

[0053] While traditional LED light sources can detect basic surface defects, their light intensity, monochromaticity, and directionality are limited, making it difficult to distinguish submicron-level defects. Preferably, this embodiment uses a high-brightness, narrow-linewidth laser light source, which can distinguish submicron-level defects.

[0054] In some embodiments, the distributed multi-wavelength light source module 1 may include a first independent wavelength light source unit 11, a second independent wavelength light source unit 12, and a light source controller.

[0055] The first independent wavelength light source unit 11 can provide 405nm laser light, and the second independent wavelength light source unit 12 can provide 355nm laser light. The dual-band light source can excite multiple wavelengths for different material defect characteristics. For example, the 405nm light source is suitable for silicon-based defect detection, and the 355nm light source is suitable for metal layer detection, thereby improving the defect identification sensitivity.

[0056] The light source controller can output laser light of different wavelengths according to a preset timing sequence. Specifically, the light source controller triggers the emission timing of each independent wavelength light source unit according to a preset protocol and synchronously controls the light source to shut down via the SPI bus.

[0057] Preferably, the distributed multi-wavelength light source module 1 may also include an independent optical power closed-loop monitoring device, which can provide real-time feedback of the light source intensity through a photodetector. Closed-loop monitoring can control the light source power fluctuation within ±1%, avoiding detection signal errors caused by power fluctuations, thereby improving the consistency of multi-channel data.

[0058] The optical path direction changing module 2 is used to change the direction of the light emitted from each group of independent wavelength light source units.

[0059] In some embodiments, the optical path direction changing module 2 may include several sets of reflector groups, each set of reflector groups may include a high reflector and a two-dimensional adjustment mechanism, and each set of reflector groups is fixed to the base by an adjustment bracket.

[0060] Preferably, the reflective surface of the high-reflectivity mirror is coated with a film layer with a reflectivity of not less than 98%.

[0061] To facilitate adjustment of the orientation of the high-reflectivity mirror, some embodiments incorporate a two-dimensional adjustment mechanism including a micro-motion platform. This mechanism allows for adjustment of the mirror's orientation. The micro-motion platform provides a positioning accuracy better than ±1 μm. Its high-precision adjustment capability (e.g., piezoelectric ceramic drive) ensures that the optical path alignment error does not exceed 0.5 μm, preventing optical path misalignment caused by mechanical vibration and improving detection stability. The micro-motion platform can be driven by piezoelectric ceramics and integrate a displacement feedback sensor. The piezoelectric ceramic drive ensures nanometer-level displacement resolution (e.g., 0.1 nm steps), and the displacement feedback sensor can correct positional deviations in real time, thus guaranteeing long-term stability of the optical path.

[0062] refer to Figure 2The optical path direction changing module 2 may specifically include 4 sets of reflectors. The first and second reflectors are on one side of the device and work with the first independent wavelength light source unit 11 to change the optical path direction. The third and fourth reflectors are on the other side of the device and work with the second independent wavelength light source unit 12 to change the optical path direction.

[0063] The first reflector group includes a first two-dimensional adjustment mechanism 211 and a first high reflectivity mirror 212.

[0064] The second reflector group includes a second two-dimensional adjustment mechanism 221 and a second high-reflectivity mirror 222.

[0065] The third reflector group includes a third two-dimensional adjustment mechanism 231 and a third high-reflectivity mirror 232.

[0066] The fourth reflector group includes a fourth two-dimensional adjustment mechanism 241 and a fourth high-reflectivity mirror 242.

[0067] The light spot shaping module 3 shapes the light that has passed through the light path direction changing module 2 and guides it to the wafer 5 to be inspected.

[0068] refer to Figure 1 In some embodiments, the component labeled 3 on the left is the first spot shaping unit, which is used to shape the laser light passing through the first and second reflector groups and guide it to the wafer 5 to be inspected. The component labeled 3 on the right is the second spot shaping unit, which is used to shape the laser light passing through the third and fourth reflector groups and guide it to the wafer 5 to be inspected. The spot shaping units on the left and right are symmetrically arranged. Here, we will discuss the first spot shaping unit on the left as an example. The second spot shaping unit on the right is similar and will not be described again.

[0069] refer to Figure 3 The first spot shaping unit includes a spot shaping module reflector 34, a first aperture mechanism 311, a second aperture mechanism 312, a Powell prism group 32, and a window lens 33 arranged sequentially.

[0070] The reflector 34 of the spot shaping module reflects and guides the light beam (the light beam for the first spot shaping unit is the light beam reflected by the first reflector group and the second reflector group) to the target path to maintain the compactness of the optical path space.

[0071] The first aperture mechanism 311 and the second aperture mechanism 312 control the diameter of the beam cross-section by adjusting the aperture size, cut off stray light at the edge and limit the effective spot size, and the spot diameter adjustment range is 0.1mm to 5mm.

[0072] The Powell prism group 32 converts a Gaussian beam into a uniformly distributed linear spot, eliminating excessively high energy at the center. The Powell prism group 32 is configured to achieve light intensity uniformity within ±3%, suitable for continuous scanning of wafer surfaces and reducing false positive rates. The full sector angle of the Powell prism group 32 is 5°. The spot size can be adjusted via an aperture mechanism (e.g., 0.5mm for fine scanning of submicron defects, 3mm for rapid, large-area detection), combined with the uniform light field distribution of the Powell prism, allowing for flexible adaptation to different defect detection needs.

[0073] The window lens 33 fine-tunes the beam projection position by axial translation or angular deflection, thereby compensating for assembly errors. The fine-tuning mechanism of the window lens 33 adopts differential thread adjustment with an adjustment accuracy of ±10μm. The differential thread design (e.g., 0.5mm pitch) enables fine adjustment of the beam position, ensuring that the overlap error of multi-channel beams is less than 5μm, thus improving image fusion accuracy.

[0074] Preferably, the first spot shaping unit further includes a polarizing prism 35 disposed between the first aperture mechanism 311 and the second aperture mechanism 312 for adjusting the spot intensity. The polarizing prism 35 finely adjusts the transmitted light intensity by rotating the polarization direction to match the signal sensitivity requirements of wafers made of different materials.

[0075] The image acquisition module 4 includes multiple sets of image acquisition channels arranged side by side. Each set of image acquisition channels acquires light of different wavelengths reflected and photoexcited by the wafer 5 under test, so as to realize defect detection of the wafer 5 under test.

[0076] In some embodiments, the laser emitted by the first spot shaping unit is reflected and photoexcited by the wafer 5 under test and then acquired by a set of image acquisition channels. The laser emitted by the second spot shaping unit is reflected and photoexcited by the wafer 5 under test and then acquired by another set of image acquisition channels. Each set of image acquisition channels includes a set of objectives, a lens barrel, and a camera arranged sequentially. The objectives are large-field objectives with a numerical aperture of not less than 0.8; the lens barrel is a large-field lens barrel that supports a maximum image size of 40mm; the camera is an 8K line scan camera based on TDI mode. The large-field lens barrel covers a single scan area of ​​10mm × 40mm. Combined with a high-resolution camera (pixel size 5μm), submicron-level defect detection can be achieved with a synchronization error of less than 1ms. Photoluminescence is a type of cold light emission, which refers to the process by which a substance (here, the wafer 5 under test) absorbs photons (or electromagnetic waves) and then re-emits photons (or electromagnetic waves). This process emits light of different wavelengths. In this embodiment, there are only two sets of image acquisition channels, which can only receive light of two different wavelengths.

[0077] To receive light from a wider variety of wavelengths and distinguish more types of defects, thereby enabling more precise identification of wafer defects, reference Figure 4 Another embodiment of this application proposes a scenario where the image acquisition module 4 includes four sets of image acquisition channels arranged side by side. The first image acquisition channel sequentially includes a first objective lens 411, a first beam splitter 421, a first lens barrel 431, and a first camera 441.

[0078] The second image acquisition channel includes, in sequence, a first objective lens 411, a first beam splitter 421, a second lens tube 432, and a second camera 442.

[0079] The third image acquisition channel includes, in sequence, a second objective lens 412, a second beam splitter 422, a third lens tube 433, and a third camera 443.

[0080] The fourth image acquisition channel includes, in sequence, a second objective lens 412, a second beam splitter 422, a fourth lens tube 434, and a fourth camera 444.

[0081] That is to say Figure 4 The two image acquisition channels on the left share the first objective lens 411 and the first beam splitter 421, while the two image acquisition channels on the right share the second objective lens 412 and the second beam splitter 422. If more image acquisition channels are needed, simply replace the appropriate beam splitter to separate more wavelengths of laser light for acquisition by more image acquisition channels.

[0082] Figure 4 In fact, two sets of symmetrically distributed optical channels (Ch1-Ch4) were set up, and the complete optical path of each optical channel is as follows.

[0083] Ch1: First independent wavelength light source unit 11 → Reflection module M1 (including first reflector group and second reflector group) → First spot shaping unit → First objective lens 411 → First beam splitter 421 → First lens barrel 431 → First camera 441.

[0084] Ch2: First independent wavelength light source unit 11 → reflection module M1 → first spot shaping unit → first objective lens 411 → first beam splitter prism 421 → second lens barrel 432 → second camera 442.

[0085] Ch3: Second independent wavelength light source unit 12 → Reflection module M2 (including the third and fourth reflector groups) → Second spot shaping unit → Second objective lens 412 → Second beam splitter 422 → Third lens tube 433 → Third camera 443.

[0086] Ch4: Second independent wavelength light source unit 12 → reflection module M2 → second spot shaping unit → second objective lens 412 → second beam splitter 422 → fourth lens barrel 434 → fourth camera 444.

[0087] After image preprocessing, the image data from each camera in each band are fused at the sub-pixel level using a position registration algorithm to achieve four-channel image fusion. Parallel detection of four channels can increase throughput by 4 times. Combined with sub-pixel registration (accuracy up to 0.1 pixels), the defect location error is less than 50nm, which can meet the high-precision inspection requirements of 3D NAND and other applications.

[0088] In fact, the first and second image acquisition channels on the left can share a set of first objective lens 411 and first beam splitter 421, while the third and fourth image acquisition channels on the right do not share a set of objective lens and beam splitter, but each uses a separate set of objective lens, lens barrel and camera.

[0089] This application, through a multi-optical-path parallel structural design, enables synchronous acquisition of multi-optical-path data and simultaneous detection of wafer defects by multiple optical-path channels, thereby improving the detection efficiency of wafer defects and the integration of the detection equipment, and reducing the detection time and the installation cost of the detection equipment.

[0090] The foregoing embodiments are all designed for the distributed multi-wavelength light source module 1, that is, for a light source module that can provide multiple wavelengths. When the light source module can only provide one wavelength of light, the initial design goal of this application can also be achieved through the structural design of the optical path.

[0091] Another embodiment of this application provides an apparatus for detecting wafer defects, comprising:

[0092] The light source module can only provide one wavelength of light.

[0093] The light path direction changing module changes the direction of the light emitted from the light source module.

[0094] The light spot shaping module shapes the light that has passed through the light path direction changing module and guides it to the wafer to be tested.

[0095] The image acquisition module includes multiple sets of image acquisition channels arranged side by side. Each set of image acquisition channels acquires light of different wavelengths reflected and photoexcited by the wafer under test, thereby realizing defect detection of the wafer under test. At least two sets of image acquisition channels share a set of objective lenses and beam splitters. Behind the beam splitter, each set of image acquisition channels is provided with a corresponding lens barrel and camera.

[0096] This embodiment can actually be referred to Figure 1 Half of it, that is, based only on one of the first independent wavelength light source unit 11 and the second independent wavelength light source unit 12, rather than both. For example, based only on the light emitted by the first independent wavelength light source unit 11, the complete optical path of the possible optical channel includes:

[0097] Ch1: First independent wavelength light source unit 11 → Reflection module M1 (including first reflector group and second reflector group) → First spot shaping unit → First objective lens 411 → First beam splitter 421 → First lens barrel 431 → First camera 441.

[0098] Ch2: First independent wavelength light source unit 11 → reflection module M1 → first spot shaping unit → first objective lens 411 → first beam splitter prism 421 → second lens barrel 432 → second camera 442.

[0099] The above example only illustrates the scenario where two image acquisition channels share a single objective lens and beam splitter. In reality, multiple image acquisition channels can also share a single objective lens and beam splitter. For specific technical details regarding the structural design of devices based solely on single-wavelength light sources, please refer to the aforementioned structural design of devices based on multi-wavelength light sources; these details will not be repeated here.

[0100] Those skilled in the art will understand that the technical features described in the various embodiments and / or claims of this application can be combined and / or combined in various ways, even if such combinations or combinations are not explicitly described in this application. In particular, without departing from the spirit and teachings of this application, the technical features described in the various embodiments and / or claims of this application can be combined and / or combined in various ways, and all such combinations and / or combinations fall within the scope of this application.

[0101] Although this application has been shown and described with reference to specific exemplary embodiments thereof, those skilled in the art will understand that various changes in form and detail may be made to this application without departing from the spirit and scope of the application as defined by the appended claims and their equivalents. Therefore, the scope of this application should not be limited to the above embodiments, but should be determined not only by the appended claims, but also by their equivalents.

Claims

1. An apparatus for detecting wafer defects, characterized in that, include: The distributed multi-wavelength light source module includes at least two sets of independent wavelength light source units, each set of independent wavelength light source units providing a wavelength of light; The optical path direction changing module changes the direction of light emitted from each group of independent wavelength light source units; The light spot shaping module shapes the light that has passed through the light path direction changing module and guides it to the wafer to be inspected; The image acquisition module includes multiple sets of image acquisition channels arranged side by side. Each set of image acquisition channels acquires light of different wavelengths reflected and photoexcited by the wafer under test, so as to realize the defect detection of the wafer under test. At least two sets of image acquisition channels share a set of objective lens and beam splitter. After the beam splitter, a corresponding lens barrel and camera are set for each set of shared image acquisition channels. The spot shaping module includes a spot shaping module reflector, a first aperture mechanism, a second aperture mechanism, a Powell prism group, and a window lens arranged sequentially. The beam shaping module's reflector is used to reflect and guide the beam to the target path; The first and second aperture mechanisms are used to define the effective spot size; Powell prisms are used to convert a beam of light into a uniformly distributed linear spot. A window lens is used to adjust the position of the light spot projection. The light spot shaping module also includes a polarizing prism disposed between the first aperture mechanism and the second aperture mechanism for adjusting the light spot intensity.

2. The apparatus for detecting wafer defects as described in claim 1, characterized in that, Each image acquisition channel includes a corresponding objective lens, lens barrel, and camera arranged in sequence.

3. The apparatus for detecting wafer defects as described in claim 1, characterized in that, The light provided by each group of independent wavelength light source units is laser light.

4. The apparatus for detecting wafer defects as described in claim 1, characterized in that, The optical path direction changing module includes a high-reflectivity mirror; The reflective surface of the high-reflectivity mirror is coated with a film with a reflectivity of not less than 98%.

5. The apparatus for detecting wafer defects as described in claim 4, characterized in that, The optical path direction changing module also includes an adjustment mechanism containing a micro-motion platform, which can be used to adjust the orientation of the high-reflectivity mirror.

6. An apparatus for detecting wafer defects, characterized in that, include: The light source module provides a light of a specific wavelength. The optical path direction changing module changes the direction of light emitted from the light source module; The light spot shaping module shapes the light that has passed through the light path direction changing module and guides it to the wafer to be inspected; The image acquisition module includes multiple sets of image acquisition channels arranged side by side. Each set of image acquisition channels acquires light of different wavelengths reflected and photoexcited by the wafer under test, so as to realize the defect detection of the wafer under test. At least two sets of image acquisition channels share a set of objective lens and beam splitter. After the beam splitter, a corresponding lens barrel and camera are set for each set of shared image acquisition channels. The spot shaping module includes a spot shaping module reflector, a first aperture mechanism, a second aperture mechanism, a Powell prism group, and a window lens arranged sequentially. The beam shaping module's reflector is used to reflect and guide the beam to the target path; The first and second aperture mechanisms are used to define the effective spot size; Powell prisms are used to convert a beam of light into a uniformly distributed linear spot. A window lens is used to adjust the position of the light spot projection. The light spot shaping module also includes a polarizing prism disposed between the first aperture mechanism and the second aperture mechanism for adjusting the light spot intensity.

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