Wafer edge width detection systems, methods, and storage media

Abstract

The application provides a wafer edge width detection system, method and storage medium, the system comprises: an image acquisition component, the image acquisition component comprises a detection camera and an irradiation light source, the image acquisition component is located on the front side of the wafer, the field of view of the image acquisition component covers the edge region of the wafer and the background region outside the edge region, the irradiation light source is located on the back side of the wafer and is opposite to the image acquisition component, part of the light beam emitted by the irradiation light source is blocked by the edge of the wafer, and the other part is used for irradiating the background region outside the edge of the wafer. By introducing the irradiation light source, the application actively creates a very high optical contrast between the edge region and the background region of the wafer, completely overcomes the boundary blur problem caused by the rough surface of the inclined section and the light scattering in the traditional method, and realizes clear and stable imaging of the wafer profile.

Description

Technical Field

[0001] This invention relates to the field of semiconductor manufacturing inspection, and in particular to a wafer edge width inspection system, method and storage medium. Background Technology

[0002] In semiconductor manufacturing processes, wafer edge exposure (WEE) and edge bead removal (EBR) are key steps in the photolithography process. Both WEE and EBR processes target the outermost annular region of the wafer, and the width of this processed area (i.e., the WEE & EBR area) is a process parameter that must be strictly monitored. Currently, the industry primarily relies on machine vision-based measurement schemes for detecting this width, specifically the following two typical schemes:

[0003] like Figure 1 and Figure 2 As shown, a is the wafer pattern segment, b is the wafer frontside segment, and c is the wafer bevel segment. The right endpoint of segment a is the center of the wafer. The required width of the WEE&EBR region is the sum of the lateral widths of segments b and c.

[0004] Option 1: As Figure 1 As shown, this scheme detects the width R (i.e., the radius of the pattern segment) of segment a using a detection camera and an illumination light source. Taking a 12-inch wafer as an example, the width of the WEE&EBR area is 150-R, where 150 is the radius of the 12-inch wafer in millimeters. Since the pattern area is much larger than the field of view of a single camera during semiconductor manufacturing, it is necessary to move the wafer to take segmented pictures to detect the distance of each segment. Then, the distances of each detected segment are summed to obtain R. Segmented detection involves wafer movement, which inevitably causes mechanical errors due to movement, resulting in reduced accuracy and poor stability of the final measurement results.

[0005] Option 2: Figure 2As shown, this scheme uses two sets of detection cameras and illumination light sources. One set of cameras and illumination light sources is used to detect the width B of segment b, and the other set is used to detect the width d of the bevel segment c. The width C of segment c is then calculated as d * cosθ, and the width of the WEE&EBR region is B + C = B + d * cosθ, where θ is the bevel angle. However, the success of this scheme heavily depends on the optical characteristics of the bevel segment at the wafer edge. In actual production, the bevel segment at the wafer edge is often not an ideally smooth surface. When the surface is rough, the incident light undergoes severe diffuse scattering, resulting in extremely weak reflected light signals received by the camera observing the bevel. This makes the grayscale difference between the bevel segment and its external environment very small and the boundary blurred in the captured image. The computing system cannot effectively segment and identify it when processing the data, leading to inaccurate measurement of the length of segment c and rendering the entire measurement scheme ineffective. Figure 3 As shown, Figure 3 The left image is the overall image, and the right image is a partial image of the wafer edge. Figure 3 As can be seen in the right image, segment c and the background area are almost integrated, and the edge outline of the wafer is not visible at all. Summary of the Invention

[0006] The purpose of this invention is to provide a wafer edge width detection system, method, and storage medium. By introducing a through-beam light source, it actively creates extremely high optical contrast between the edge region of the wafer and the background region, completely overcoming the boundary blurring problem caused by the rough surface of the inclined section and light scattering in traditional methods, and realizing clear and stable imaging of the wafer outline.

[0007] To achieve the above objectives, the present invention provides a wafer edge width detection system, comprising:

[0008] An image acquisition component includes a detection camera and an illumination light source. The image acquisition component is located on the front side of a wafer. The field of view of the image acquisition component covers the edge region of the wafer and the background region outside the edge region. The edge region of the wafer includes a flat section and a beveled section on the front side. The illumination light source is configured to emit a light beam of a first preset wavelength.

[0009] A through-beam light source is located on the back side of the wafer and is positioned opposite the image acquisition component. The through-beam light source is configured to emit a light beam of a second preset wavelength. The light emission direction of the through-beam light source is perpendicular to the mirror surface of the detection camera. Part of the light beam emitted by the through-beam light source is blocked by the edge of the wafer, and the other part is used to illuminate the background area outside the edge of the wafer.

[0010] The image acquisition component is used to acquire images of the edge region of the wafer and the background region outside the edge region. Due to the illumination of the through light source, there is a grayscale difference between the image of the edge region and the image of the background region.

[0011] Optionally, the first preset wavelength and the second preset wavelength are outside the photosensitive wavelength range of the photoresist on the wafer.

[0012] Optionally, both the illumination light source and the through light source are white light sources using light-emitting diodes.

[0013] Optionally, the through-beam light source is a reflective light source, which includes a reflector disposed on one side of the back surface of the wafer for reflecting the light from the illumination source.

[0014] Optionally, an auxiliary light source is provided on one side of the front of the wafer to enhance the light reflected by the reflector.

[0015] Optionally, the through-beam light source is a ring light source or multiple light sources arranged in a ring to illuminate the edge of the wafer and the background area outside the wafer edge.

[0016] Optionally, the detection system further includes a controller, which is electrically connected to the through-beam light source and is used to control the opening and closing of the through-beam light source.

[0017] Optionally, the detection system further includes an image data processing module for processing the images collected by the detection camera and measuring the width of the edge region of the wafer.

[0018] According to another aspect of the present invention, the present invention also provides a wafer edge width detection method, which employs the wafer edge width detection system described above, and the detection method includes:

[0019] The through-beam light source is activated to illuminate the background area outside the wafer edge;

[0020] The image acquisition component acquires an image containing the edge region of the wafer and the background region outside the edge region;

[0021] The width of the edge region of the wafer is measured based on the image acquired by the image acquisition component.

[0022] In another aspect, the present invention also provides a storage medium storing a program that can be read and written, wherein the program, when executed, implements the wafer edge width detection method as described above.

[0023] With the above configuration, the present invention achieves the following significant technical effects:

[0024] Fundamentally solves the imaging problem: By introducing a through-beam light source, an extremely high optical contrast is actively created between the edge region of the wafer and the background region (the background region is bright, and the beveled section of the wafer edge is dark), which completely overcomes the boundary blurring problem caused by the rough surface of the beveled section and light scattering in traditional methods, and achieves clear and stable imaging of the wafer outline.

[0025] Improved detection accuracy and stability: By eliminating the need to move the wafer for segmented imaging to measure the distance of each segment and then summing the results, direct, one-time measurement of the WEE&EBR area width (edge ​​width) is achieved. This eliminates the cumulative error introduced by mechanical movement, significantly improving measurement accuracy, repeatability, and stability.

[0026] In summary, this invention transforms the width detection of the WEE & EBR region from an auxiliary means that is susceptible to interference and has limited accuracy into a highly reliable, high-precision, and online-integratable basic process monitoring capability, providing key technical support for improving semiconductor manufacturing yield and process control. Attached Figure Description

[0027] Those skilled in the art will understand that the accompanying drawings are provided to better understand the invention and do not constitute any limitation on the scope of the invention. Wherein:

[0028] Figure 1 This is a schematic diagram of the first solution in the prior art;

[0029] Figure 2 This is a schematic diagram of the second solution in the prior art;

[0030] Figure 3 This is a schematic diagram of the image acquired by Scheme 2 in the prior art;

[0031] Figure 4 This is a schematic diagram of a wafer edge width detection system according to an embodiment of the present invention;

[0032] Figure 5 This is a schematic diagram of an image captured by the detection camera of the present invention.

[0033] The reference numerals in the attached figures are as follows:

[0034] a-pattern segment; b-flat front segment; c-sloping segment. Detailed Implementation

[0035] In this document, unless otherwise stated, the terms “upper,” “lower,” “left,” “right,” “inner,” “outer,” “front,” “back,” “top,” “bottom,” etc., are used to indicate orientation or positional relationship based on the accompanying drawings, and are only for the convenience of describing the invention and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a characteristic orientation and operation, and therefore should not be construed as a limitation of the invention.

[0036] The specific embodiments of the present invention will now be described in more detail with reference to the accompanying drawings. The advantages and features of the present invention will become clearer from the following description. It should be noted that the drawings are all in a very simplified form and use non-precise proportions, and are only used to facilitate and clarify the illustration of the embodiments of the present invention.

[0037] Figure 4 This is a schematic diagram of a wafer edge width detection system according to an embodiment of the present invention. Please refer to it. Figure 4 This invention provides a wafer edge width detection system for detecting the width of the WEE & EBR area. The detection system includes an image acquisition component, a through-beam light source, and an image data processing module.

[0038] The image acquisition component includes a detection camera and an illumination light source. The image acquisition component is located on the front side of the wafer, and its field of view covers the edge region of the wafer and the background region outside the edge region. The edge region of the wafer (referring to the WEE & EBR area) includes a flat frontside section and a bevel section. It is understood that both WEE (Wafer Edge Exposure) and EBR (Edge Bead Removal) processes target the outermost annular region of the wafer. Although WEE and EBR have different specific mechanisms (one uses light, the other uses a solvent), their effective ranges highly overlap. This invention aims to detect the width of the WEE & EBR area. The illumination light source is configured to emit a light beam of a first preset wavelength.

[0039] A through-beam light source is located on the back side of the wafer and opposite the image acquisition component. The through-beam light source is configured to emit a beam of light with a second preset wavelength. The through-beam light source is unobstructed outside the wafer, allowing its light to enter the inspection camera. The emission direction of the through-beam light source is perpendicular to the mirror surface of the inspection camera, ensuring that the light from the through-beam light source enters the inspection camera perpendicularly. A portion of the beam emitted by the through-beam light source is blocked by the edge of the wafer, while the remaining portion illuminates the background area outside the wafer edge.

[0040] The image acquisition component is used to acquire images of the edge region of the wafer and the background region outside the edge region. Due to the illumination of the through light source, there is a large grayscale difference between the image of the edge region and the image of the background region, so the edge region of the wafer can be accurately and effectively distinguished from the background region outside, thus achieving clear and stable imaging of the wafer outline.

[0041] In existing technologies, the detection camera perceives the background area and segment C as black with minimal grayscale difference, thus failing to effectively distinguish between the two. However, in this patent, the background area outside the wafer, illuminated by the through-beam light source, receives a significant amount of light, resulting in a white appearance. Because the wafer's edge partially blocks the beam emitted by the through-beam light source, and the beveled section of the wafer (i.e....) Figure 4 In the c-segment of the wafer, only a very small amount of light enters the detection camera due to scattering, resulting in the camera displaying the beveled segment as black. The flat section on the front side of the wafer (i.e., the...) Figure 4 Section b) has a smooth surface, reflecting most of the light from the illuminating light source into the detection camera, resulting in a light gray color appearing in the camera's discrimination effect. The pattern section (i.e....) Figure 4 (segment a) Due to the presence of a pattern, the detection camera recognizes colors other than black, white, and gray. Figure 5 To detect the images captured by the camera, Figure 5 The left image is the overall image, and the right image is a partial image of the wafer edge. It can be understood that the image actually captured by the detection camera is the right image, while the left image is the result of stitching together multiple images captured at different edges. The detection camera identifies segments a, b, and c with different colors (large grayscale differences), accurately and effectively distinguishing each segment, and can measure the lateral width of segments b and c. That is, the width of the WEE&EBR area is the sum of the lateral widths of segments b and c. The specific colors mentioned above are only examples; other colors may be used in other embodiments, but the common points are a clear distinction between the background area, segments c, b, and a.

[0042] Furthermore, the first preset wavelength and the second preset wavelength are outside the photosensitive wavelength range of the photoresist on the wafer. In other words, the first preset wavelength and the second preset wavelength avoid the photosensitive wavelength of the LITHO region (specifically, the patterned area on the wafer that has been coated with photoresist and is about to be or is undergoing photolithography exposure, i.e., the pattern segment). For example, both the illumination light source and the through-beam light source are white light sources using light-emitting diodes (LEDs), and the first preset wavelength and the second preset wavelength can be 400-800 nm. It is understood that photoresist is a photosensitive material that is extremely sensitive to light of a specific wavelength. If the wavelength of the through-beam light source used for detection falls within the photosensitive range of the photoresist, it will accidentally expose the photoresist, causing serious process defects and product scrap. Setting the first preset wavelength and the second preset wavelength outside the photosensitive wavelength range of the photoresist on the wafer is an important safety design of this invention, ensuring that the detection action itself will not damage the wafer, allowing this detection method to be safely integrated into the photolithography production line. The selected 400-800nm ​​light source wavelength is outside the mainstream photoresist photosensitive wavelength range, which fundamentally eliminates the risk of detection light interfering with the photolithography process and causing accidental exposure. This allows the detection method of the present invention to be safely integrated into the online production line and realize real-time monitoring.

[0043] For example, the through-beam light source is a ring light source or multiple light sources arranged in a ring to illuminate the edge of the wafer and the background area outside the wafer edge. The through-beam light source can also be a reflective light source; for example, the through-beam light source includes a reflector disposed on the back side of the wafer to reflect the light from the illuminating light source. Preferably, an auxiliary light source is added to the front side of the wafer to enhance the light reflected by the reflector.

[0044] Furthermore, the detection system also includes an image data processing module, which processes the images collected by the detection camera and measures the width of the edge region of the wafer.

[0045] Furthermore, the detection system also includes a controller electrically connected to the through-beam light source for controlling its on / off state. In other embodiments, the controller may also control the on / off state of the illumination light source, which is not limited here. It is understood that the controller may also synchronize with the start and stop of the detection job. The intelligent linkage between the on / off state of the through-beam light source and the detection job, illuminating it only when needed, reduces energy consumption and heat load, extends the lifespan of the light source, and meets the requirements of semiconductor manufacturing automation and lean production. After the detection job begins, the controller controls the through-beam light source to turn on. After the through-beam light source is activated, the detection camera begins to collect relevant images of the wafer edge area and background area, processes them through the image data processing module, and outputs the processing results to the user. After the detection job ends, the controller controls the through-beam light source to turn off.

[0046] According to another aspect of the present invention, the present invention also provides a wafer edge width detection method, which employs the wafer edge width detection system described above, and the detection method includes:

[0047] The through-beam light source is activated to illuminate the background area outside the wafer edge;

[0048] The image acquisition component acquires an image containing the edge region of the wafer and the background region outside the edge region;

[0049] The width of the edge region of the wafer is measured based on the image acquired by the image acquisition component.

[0050] In another aspect, the present invention also provides a storage medium storing a program that can be read and written, wherein the program, when executed, implements the wafer edge width detection method as described above.

[0051] With the above configuration, the present invention achieves the following significant technical effects:

[0052] Fundamentally solves the imaging problem: By introducing a through-beam light source, an extremely high optical contrast is actively created between the edge region of the wafer and the background region (the background region is bright, and the beveled section of the wafer edge is dark), which completely overcomes the boundary blurring problem caused by the rough surface of the beveled section and light scattering in traditional methods, and achieves clear and stable imaging of the wafer outline.

[0053] Improved detection accuracy and stability: By eliminating the need to move the wafer for segmented imaging to measure the distance of each segment and then summing the results, direct, one-time measurement of the WEE&EBR area width (edge ​​width) is achieved. This eliminates the cumulative error introduced by mechanical movement, significantly improving measurement accuracy, repeatability, and stability.

[0054] In summary, this invention transforms the width detection of the WEE & EBR region from an auxiliary means that is susceptible to interference and has limited accuracy into a highly reliable, high-precision, and online-integratable basic process monitoring capability, providing key technical support for improving semiconductor manufacturing yield and process control.

[0055] It should be noted that references to "an embodiment," "an embodiment," "a specific embodiment," "some embodiments," etc., in the specification only indicate that the described embodiment may include a specific feature, structure, or characteristic. Furthermore, such phrases do not necessarily refer to the same embodiment. Additionally, when a specific feature, structure, or characteristic is described in conjunction with an embodiment, whether explicitly described or not, implementing such a feature, structure, or characteristic in conjunction with other embodiments is within the knowledge of those skilled in the art.

[0056] It should be noted that the various embodiments in this specification are described in a progressive manner, with each embodiment focusing on the differences from other embodiments. Similar or identical parts between embodiments can be referred to interchangeably. For the systems disclosed in the embodiments, since they correspond to the methods disclosed in the embodiments, the descriptions are relatively simple, and relevant parts can be referred to the method section.

[0057] It should also be noted that although the present invention has been disclosed above with reference to preferred embodiments, these embodiments are not intended to limit the present invention. For any person skilled in the art, many possible variations and modifications can be made to the technical solutions of the present invention based on the disclosed technical content, or equivalent embodiments can be modified accordingly, without departing from the scope of the present invention. Therefore, any simple modifications, equivalent changes, and modifications made to the above embodiments based on the technical essence of the present invention without departing from the content of the present invention shall still fall within the scope of protection of the present invention.

[0058] It should also be understood that, unless otherwise specified or indicated, the terms “first,” “second,” “third,” etc., in the specification are used only to distinguish the various components, elements, and steps in the specification, and not to indicate the logical or sequential relationships between the various components, elements, and steps.

[0059] Furthermore, it should be recognized that the terminology described herein is used only to describe particular embodiments and not to limit the scope of the invention. It must be noted that the singular forms “a” and “an” used herein and in the appended claims include plural bases unless the context clearly indicates otherwise. For example, a reference to “a step” or “an apparatus” means a reference to one or more steps or apparatuses, and may include secondary steps and secondary apparatuses. All conjunctions used should be understood in the broadest sense. Also, the word “or” should be understood to have the definition of logical “or” rather than logical “exclusive OR”, unless the context clearly indicates otherwise. Furthermore, implementation of the methods and / or devices in embodiments of the invention may include performing selected tasks manually, automatically, or in combination.

Claims

1. A wafer edge width detection system, characterized in that, include: An image acquisition component includes a detection camera and an illumination light source. The image acquisition component is located on the front side of a wafer. The field of view of the image acquisition component covers the edge region of the wafer and the background region outside the edge region. The edge region of the wafer includes a flat section and a beveled section on the front side. The illumination light source is configured to emit a light beam of a first preset wavelength. A through-beam light source is located on the back side of the wafer and is positioned opposite the image acquisition component. The through-beam light source is configured to emit a light beam of a second preset wavelength. The light emission direction of the through-beam light source is perpendicular to the mirror surface of the detection camera. Part of the light beam emitted by the through-beam light source is blocked by the edge of the wafer, and the other part is used to illuminate the background area outside the edge of the wafer. The image acquisition component is used to acquire images of the edge region of the wafer and the background region outside the edge region. Due to the illumination of the through light source, there is a grayscale difference between the image of the edge region and the image of the background region.

2. The wafer edge width detection system as described in claim 1, characterized in that, The first preset wavelength and the second preset wavelength are outside the photosensitive wavelength range of the photoresist on the wafer.

3. The wafer edge width detection system as described in claim 1, characterized in that, Both the illumination light source and the through light source are white light sources using light-emitting diodes (LEDs).

4. The wafer edge width detection system as described in claim 1, characterized in that, The through-beam light source is a reflective light source, and the through-beam light source includes a reflector disposed on one side of the back of the wafer for reflecting the light from the illumination light source.

5. The wafer edge width detection system as described in claim 4, characterized in that, An auxiliary light source is added to one side of the front of the wafer to enhance the light reflected by the reflector.

6. The wafer edge width detection system as described in claim 1, characterized in that, The through-beam light source is a ring light source or multiple light sources arranged in a ring to illuminate the edge of the wafer and the background area outside the wafer edge.

7. The wafer edge width detection system as described in claim 1, characterized in that, The detection system also includes a controller, which is electrically connected to the through-beam light source and is used to control the opening and closing of the through-beam light source.

8. The wafer edge width detection system as described in claim 1, characterized in that, The detection system also includes an image data processing module, which processes the images collected by the detection camera and measures the width of the edge region of the wafer.

9. A method for detecting the edge width of a wafer, characterized in that, The wafer edge width detection system as described in any one of claims 1-8 includes the following detection method: The through-beam light source is activated to illuminate the background area outside the wafer edge; The image acquisition component acquires an image containing the edge region of the wafer and the background region outside the edge region; The width of the edge region of the wafer is measured based on the image acquired by the image acquisition component.

10. A storage medium having a program stored thereon, characterized in that, When the program is executed, it implements the wafer edge width detection method as described in claim 9.

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