Large-curvature wafer defect detection device and detection light path

Abstract

The invention relates to the technical field of wafer defect detection, and discloses a large-curvature wafer defect detection device which comprises a beam splitter prism and an imaging lens group, a light source and a collimating lens group are arranged on the two sides of the incident plane of the beam splitter prism respectively, the light source, the beam splitter prism and the collimating lens group are sequentially arranged on the same straight line, and the large-curvature wafer defect detection device is formed by moving the light source. The light source can be close to or far away from the beam splitter prism, so that the incidence angle of the output light path in the detection light path is adjusted, the irradiation intensity of light rays is adjusted, the light source is close to the beam splitter prism, and when the light source detects a wafer with a large curved concave surface through the beam splitter prism, the brightness of the light rays irradiated on the edge of the large curved concave surface can be enhanced; therefore, the imaging lens group and the charge coupler can be completely imaged; the light source is far away from the beam splitter prism, so that when the light source detects the wafer with the large curved convex surface through the beam splitter prism, the brightness of the light irradiated to the center of the large curved concave surface can be reduced, and complete imaging of the charge coupler is facilitated.

Description

Technical Field

[0001] This invention relates to the field of wafer defect detection technology, specifically to a large warp wafer defect detection device and detection optical path. Background Technology

[0002] The "magic mirror," also known as the "transparent mirror," is a bronze mirror with special optical effects invented in the Western Han Dynasty of China. Its appearance is no different from that of an ordinary bronze mirror, but when sunlight shines on it, the patterns and inscriptions on the back of the mirror can be clearly seen when the light reflected from the mirror is projected onto the wall, as if the light passes through the lens and is reflected from behind. This phenomenon makes it a typical representative of ancient optical technology.

[0003] In the field of semiconductor inspection, wafer defect detection technology has been developed based on the optical principle of a "magic mirror." This technology can be used to detect defects such as pits and bumps on the wafer surface. Its core detection principle is as follows: after collimation, the light source shines on the wafer. Pits on the wafer will cause the light to converge, forming a bright spot at a suitable position of the observation point; conversely, bumps will appear as black spots.

[0004] Although existing "magic mirror" principle inspection equipment can meet the needs of concave and convex point inspection of ordinary planar wafers, there are still significant technical limitations for large warp wafers (such as concave and convex wafers with large radii of curvature): because the light source and imaging lens group of traditional equipment are fixed in position, the light path cannot be adjusted according to the warp shape of the wafer, resulting in the light illuminating the wafer surface not being perpendicular to the incident point and the reflected light convergence point being offset. As a result, the image acquired cannot completely cover the edge of the wafer, making it difficult to fully identify defects.

[0005] Therefore, to address the issue of not meeting existing requirements, we propose a large warp wafer defect detection device and detection optical path. Summary of the Invention

[0006] This invention provides a device and optical path for detecting large warpage wafer defects, which has the advantages of compact structure, low production cost, simple detection steps, and clear display of detection results, thus solving the problems mentioned in the background art.

[0007] This invention provides the following technical solution: a device for detecting large warpage wafer defects, comprising a beam splitter and an imaging lens group. A light source and a collimating lens group are respectively arranged on both sides of the incident surface of the beam splitter. The light source, beam splitter, and collimating lens group are arranged sequentially in a straight line. An imaging lens group is arranged on the refractive surface of the beam splitter. The imaging lens group and the light source can approach or move away from the beam splitter, and the imaging lens group approaches or moves away from the beam splitter synchronously with the light source. A charge-coupled device is arranged at the output end of the imaging lens group. The wafer body to be inspected is placed on the side of the collimating lens group away from the beam splitter. During inspection, the light source emits a light beam, which is transmitted through the beam splitter and then illuminates the surface of the wafer body to be inspected through the collimating lens group. The surface of the wafer body to be inspected reflects the input light beam to form an output light beam. After passing through the collimating lens group, the output light beam is refracted by the beam splitter onto the imaging lens group to form an image. The charge-coupled device converts the optical signal in the imaging lens group into a digital signal.

[0008] Specifically, the positions of the light source and the imaging lens group are adjusted by moving them closer to or further away from the beam splitter via a guide rail structure, and the distances between the light source and the imaging lens group and the beam splitter are adjusted proportionally.

[0009] Specifically, the distance between the light source and the beam splitter is 25-45mm, and the light source is an LED light source with a wavelength of 620-700nm.

[0010] Specifically, a quarter-wave plate is disposed between the collimating lens group and the beam splitter prism. The beam splitter prism is a polarizing beam splitter prism. The quarter-wave plate and the polarizing beam splitter prism work together to eliminate stray light.

[0011] An optical path for detecting large warpage wafer defects, based on the aforementioned large warpage wafer defect detection device, includes an input optical path and an output optical path. The input optical path includes an illumination optical path, a transmission beam optical path, and a straightening optical path. The illumination beam is formed by a light source illuminating a beam splitter. The transmission beam is formed by the illumination beam passing through the beam splitter and then illuminating a collimating lens group. The straightening beam is formed by the transmission beam being straightened by the collimating lens group and then illuminating the wafer body. The output optical path includes a reflection optical path, a detection beam optical path, a receiving optical path, and an imaging optical path. The reflection beam is formed by the wafer body reflecting the straightening beam onto the collimating lens group. The detection beam is formed by the reflection beam illuminating the incident surface of the beam splitter. The receiving beam is formed by the detection beam being refracted by the beam splitter and then illuminating an imaging lens group. The imaging beam is formed by the receiving beam being imaged by the imaging lens group and then input to a charge-coupled device (CCD). The CCD converts the optical signal of the imaging optical path into an electrical signal for imaging.

[0012] Specifically, the illumination angles of the transmitted beam path and the straightened beam path increase as the path of the illumination beam path shortens, in order to detect a wafer body with a concave surface.

[0013] Specifically, the illumination angles of the transmitted beam path and the straightening beam path decrease as the path of the illumination beam path increases, in order to detect wafer bodies with convex surfaces.

[0014] The present invention has the following beneficial effects:

[0015] 1. By using a beam splitter, the illumination light path and the receiving light path are separated, so that the input light path and the output light path can be operated simultaneously on a single beam splitter. This simplifies the detection device, reduces equipment costs, and makes reasonable use of the optical properties of the beam splitter itself to eliminate detection stray light and improve detection accuracy.

[0016] 2. By moving the light source, the light source can be brought closer to or further away from the beam splitter, thereby adjusting the incident angle of the output light path in the detection beam path, and thus adjusting the illumination intensity of the light. By bringing the light source closer to the beam splitter, when the light source passes through the beam splitter to detect a wafer with a large warp concave surface, the light illuminating the edge of the large warp concave surface can be brightened, so as to facilitate complete imaging of the imaging lens group and the charge coupler. By moving the light source further away from the beam splitter, when the light source passes through the beam splitter to detect a wafer with a large warp convex surface, the light illuminating the center of the large warp concave surface can be brightened, so as to facilitate complete imaging of the imaging lens group and the charge coupler.

[0017] 3. By setting up a beam splitter with a polarization structure and cooperating it with a quarter-wave plate, the ambient stray light of the detection device is eliminated, thereby improving the accuracy of the output optical path and the feedback optical path, making the imaging results of the imaging lens group and the charge coupler clearer. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the structure of a large warp wafer defect detection device and detection method according to the present invention; Figure 2 This is a schematic diagram of the input optical path in this invention; Figure 3 This is a schematic diagram of the output optical path structure in this invention; Figure 4 This is a schematic diagram illustrating the movement of the light source in this invention; Figure 5 This is a schematic diagram showing the position of the light source used for detecting planar wafers in this invention; Figure 6 This is a schematic diagram showing the position of the light source used for detecting concave wafers in this invention; Figure 7This is a schematic diagram of the position and structure of the light source used for detecting convex wafers in this invention; Figure 8 This is a schematic diagram of a large warp wafer defect detection device with a stray light elimination structure according to the present invention; Figure 9 This is a schematic diagram of the imaging lens group in this invention; Figure 10 This is a schematic diagram of the imaging optics simulation in this invention; Figure 11 This is a schematic diagram of the imaging lens group after eliminating stray light in this invention.

[0019] In the diagram: 1. Light source; 2. Beam splitter prism; 3. Collimating lens group; 4. Imaging lens group; 5. Charge-coupled device (CCD); 6. Wafer body; 7. Quarter-wave plate; 11. Illumination optical path; 12. Transmitted beam optical path; 13. Straightening optical path; 14. Reflected optical path; 15. Detection beam optical path; 16. Receiving optical path; 17. Imaging optical path. Detailed Implementation

[0020] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0021] like Figures 1 to 11 As shown, a device for detecting large warpage wafer defects and its detection optical path include a beam splitter 2 and an imaging lens group 4. A light source 1 and a collimating lens group 3 are respectively arranged on both sides of the incident surface of the beam splitter 2. The wafer body 6 to be inspected is placed on the side of the collimating lens group 3 away from the beam splitter 2. The light source 1, beam splitter 2, collimating lens group 3 and wafer body 6 are arranged sequentially in a straight line. During detection, the light source 1 emits a light beam, which passes through the beam splitter 2. The beam splitter 2 splits and diffuses the light beam, causing it to illuminate the collimating lens group 3. The collimating lens group 3 straightens the light beam. The light beam is irradiated onto the wafer body 6. The refractive surface of the beam splitter 2 is provided with an imaging lens group 4, and the output end of the imaging lens group 4 is provided with a charge coupler 5. The wafer body 6 reflects the light beam irradiated by the light source 1 and straightens it after passing through the collimating lens group 3, and then irradiates the beam splitter 2. The beam splitter 2 refracts the reflected light beam so that it enters the imaging lens group 4. The imaging lens group 4 receives the light signal and performs optical imaging. The charge coupler 5 converts the light signal in the imaging lens group 4 into an electrical signal to output a digital image, so as to complete the surface defect detection of the large warp wafer.

[0022] In this embodiment, the illumination light path 11 and the receiving light path 16 are separated by the beam splitter 2, so that the output light path and the feedback light path can be operated simultaneously on a single beam splitter 2. This simplifies the detection device and reduces equipment costs. Compared with existing detection devices, this device has a simpler principle, making it easier and faster to debug and use. Moreover, the device has lower costs and higher detection accuracy, thus achieving the goal of cost reduction and efficiency improvement.

[0023] More specifically, such as Figure 2 As shown, the light source 1 illuminates the beam splitter 2 to form an illumination light path 11. The illumination light path 11 passes through the beam splitter 2 and illuminates the collimating lens group 3 to form a transmission beam light path 12. The transmission beam light path 12 is straightened by the collimating lens group 3 and then illuminates the wafer body 6 to form a straightening light path 13. That is, the illumination light path 11, the transmission beam light path 12 and the straightening light path 13 constitute the input light path in which the light source 1 emits a beam of light and acts on the surface of the wafer body 6.

[0024] More specifically, such as Figure 3 and Figure 9 , Figure 10 As shown, the wafer body 6 reflects the straightening optical path 13 onto the collimating lens group 3 to form a reflected optical path 14. The reflected optical path 14 illuminates the incident surface of the beam splitter 2 to form a detection beam optical path 15. The detection beam optical path 15 is refracted by the beam splitter 2 and illuminates the imaging lens group 4 to form a receiving optical path 16. The receiving optical path 16 illuminates the charge coupler 5 through the imaging lens group 4 to form an imaging optical path 17. The charge coupler 5 converts the optical signal in the imaging optical path 17 into an electrical signal. That is, the output optical path formed by the reflected optical path 14, the detection beam optical path 15 and the receiving optical path 16 is composed of the beam reflected by the wafer body 6 acting on the charge coupler 5 for imaging.

[0025] The working principle of this embodiment is as follows: During inspection, if the surface of the wafer body 6 has uneven defects, the reflected light path 14 will be imaged onto the imaging lens group 4 after passing through the collimating lens group 3 and the beam splitter prism 2. The image on the imaging lens group 4 will have dark spots or bright spots. Dark spots indicate that the surface of the wafer body 6 has convex spots, and bright spots indicate that the surface of the wafer body 6 has concave spots. The charge coupler 5 converts the light from the imaging lens group 4 into electrical signals to output a digital image, uniformly converting the dark spots or bright spots into defect points and classifying and labeling them, thereby completing the surface defect detection work of the large warp wafer body 6.

[0026] It should be noted that: such as Figure 4 As shown, in the beam splitter 2, any two symmetrical side walls around it are incident surfaces, while the side perpendicular to the incident surface is the refractive surface.

[0027] Moreover, the charge coupler 5 can be replaced by a CCD camera, which is any digital camera with a charge-coupled image sensor that can convert optical images into digital signals.

[0028] In the input optical path, the illumination optical path 11 refers to the light beam emitted by the light source 1 entering through the incident surface on one side of the beam splitter 2 and being transmitted to the other incident surface of the beam splitter 2. The beam splitter 2 also refracts a beam of light from the refracting surface of the illumination optical path 11. The direction of this beam is opposite to the position of the imaging mirror group 4. It is an additional ray that does not participate in the input optical path and the output optical path.

[0029] In the output optical path, the receiving optical path 16 is formed by the refraction of the detection beam optical path 15 from the incident surface of the beam splitter 2 away from the light source 1. The detection beam optical path 15 and the transmission beam optical path 12 are opposite in direction, and the receiving optical path 16 is opposite in direction to the additional light refracted by the illumination optical path 11. This greatly avoids the influence of refracted stray light and improves the imaging clarity of the imaging lens group 4 and the imaging accuracy of the charge coupler 5.

[0030] like Figures 1 to 7 As shown, the distances between the light source 1 and the imaging lens group 4 relative to the beam splitter 2 are adjusted proportionally, and the wafer body 6 is a planar wafer, a convex wafer, or a concave wafer. In this embodiment, as the light source 1 approaches or moves away from the beam splitter 2, the illumination angle of the straightening optical path 13 can be adjusted so that the detection optical path can perform defect detection on the planar wafer, the convex wafer, and the concave wafer respectively.

[0031] In this embodiment, when the light source 1 and the beam splitter 2 are in their initial positions, the detection optical path in the detection device is used to detect the wafer body 6 of the plane.

[0032] If the light source 1 and the beam splitter 2 approach the beam splitter 2 simultaneously, the detection optical path in the detection device is used to detect the concave wafer body 6.

[0033] If the light source 1 and the beam splitter 2 approach the beam splitter 2 and move away from the beam splitter 2 simultaneously, the detection optical path in the detection device is used to detect the convex wafer body 6.

[0034] like Figure 4 and Figure 6As shown, when detecting the concave wafer body 6, the illumination angles of the transmitted beam path 12 and the straightening beam path 13 increase as the path of the illumination beam path 11 shortens, in order to detect the concave wafer body 6. More specifically, when the light source 1 approaches the beam splitter 2, the path length of the illumination beam path 11 becomes shorter. At this time, the incident angle between the beam emitted by the light source 1 and the beam splitter 2 increases. Therefore, when the beam is transmitted through the beam splitter 2 and irradiates the collimating lens group 3, its illumination angle also increases. As a result, the convergence point of the receiving beam path 16 refracted by the beam splitter 2 from the concave surface of the concave wafer body 6 will also move accordingly. Therefore, it is necessary to move the imaging lens group 4 synchronously to enable it to receive all the receiving beam paths 16 so that it can be imaged by the charge coupler 5.

[0035] like Figure 4 and Figure 7 As shown, when detecting the convex wafer body 6, the illumination angles of the transmitted beam path 12 and the straightening beam path 13 decrease as the path of the illumination beam path 11 increases, so as to detect the convex wafer body 6. More specifically, when the light source 1 moves away from the beam splitter 2, the path length of the illumination beam path 11 becomes longer. At this time, the incident angle between the beam emitted by the light source 1 and the beam splitter 2 decreases. Therefore, when the beam is transmitted through the beam splitter 2 and irradiates the collimating lens group 3, its illumination angle also decreases. As a result, the convergence point of the receiving beam path 16 refracted by the beam splitter 2 from the concave surface of the concave wafer body 6 will also move accordingly. Therefore, it is necessary to move the imaging lens group 4 synchronously so that it can receive the entire receiving beam path 16 so that it can be imaged by the charge coupler 5.

[0036] like Figure 1 As shown, the positions of the light source 1 and the imaging lens group 4 are adjusted by the guide rail structure to move closer to or further away from the beam splitter 2. The distance between the light source 1 and the beam splitter 2 is 25-45mm. The light source 1 is an LED light source with a wavelength of 620-700nm. The use of LED light source 1 makes the cost of the equipment lower.

[0037] In this embodiment, when the distance between the light source 1 and the beam splitter prism 2 is 25mm, the output light path illuminates the large-curvature concave wafer body 6, so that the defects of the large-curvature concave wafer body 6 are most clearly displayed in the feedback light path reflected by the concave surface of the wafer body 6.

[0038] When the distance between the light source 1 and the beam splitter prism 2 is 45mm, the output light path illuminates the large-curved convex wafer body 6, making the defects of the large-curved convex wafer body 6 most clearly displayed in the feedback light path reflected by the convex surface of the wafer body 6.

[0039] like Figure 8 and Figure 11As shown, a quarter-wave plate 7 is disposed between the collimating lens group 3 and the beam splitter 2. The beam splitter 2 is a polarizing beam splitter. The quarter-wave plate 7 works in conjunction with the polarizing beam splitter to eliminate stray light. The polarizing beam splitter and the quarter-wave plate 7 can eliminate stray light generated by reflection from optical elements in the detection device, thereby improving the accuracy of the output optical path and the feedback optical path, making the imaging results of the imaging lens group 4 and the charge coupler 5 clearer. Especially in the detection of wafers with large warp surfaces, the effect of eliminating stray light is more significant.

Claims

1. A device for detecting large warpage defects in wafers, characterized in that, The device includes a beam splitter (2) and an imaging lens group (4). A light source (1) and a collimating lens group (3) are respectively arranged on both sides of the incident surface of the beam splitter (2). The light source (1), beam splitter (2) and collimating lens group (3) are arranged in a straight line. An imaging lens group (4) is arranged on the refractive surface of the beam splitter (2). The imaging lens group (4) and the light source (1) can approach or move away from the beam splitter (2). The imaging lens group (4) approaches or moves away from the beam splitter (2) synchronously with the light source (1). A charge coupler (5) is arranged at the output end of the imaging lens group (4). A wafer body (6) to be inspected is placed on the side of the collimating lens group (3) away from the beam splitter (2). During testing, the light source (1) emits a light beam, which is transmitted through the beam splitter (2) and then irradiates the surface of the wafer body (6) under test through the collimating lens group (3). The surface of the wafer body (6) under test reflects the input light beam to form an output light beam. After the output light beam passes through the collimating lens group (3), it is refracted by the beam splitter (2) onto the imaging lens group (4) to form an image. The charge coupler (5) converts the optical signal in the imaging lens group (4) into a digital signal.

2. The wafer defect detection device with large warpage according to claim 1, characterized in that: The distances between the light source (1) and the imaging lens group (4) relative to the beam splitter (2) are adjusted proportionally.

3. The wafer defect detection device with large warpage according to claim 2, characterized in that: The positions of the light source (1) and the imaging lens group (4) are adjusted by moving them closer to or further away from the beam splitter (2) via a guide rail structure.

4. The wafer defect detection device with large warpage according to claim 3, characterized in that: The distance between the light source (1) and the beam splitter (2) is 25-45 mm. The light source (1) is an LED light source with a wavelength of 620-700 nm.

5. The wafer defect detection device with large warpage according to claim 1, characterized in that: A quarter-wave plate (7) is provided between the collimating lens group (3) and the beam splitter (2). The beam splitter (2) is a polarizing beam splitter. The quarter-wave plate (7) works with the polarizing beam splitter to eliminate stray light.

6. A detection optical path for a large warp wafer defect detection device, characterized in that, The device for detecting large warpage wafer defects based on claims 1 to 5 includes an input optical path and an output optical path. The input optical path includes an illumination optical path (11), a transmission beam optical path (12), and a straightening optical path (13). The illumination optical path (11) is formed by the light source (1) illuminating the beam splitter (2). The transmission beam optical path (12) is formed by the illumination optical path (11) passing through the beam splitter (2) and then illuminating the collimating lens group (3). The straightening optical path (13) is formed by the transmission beam optical path (12) being straightened by the collimating lens group (3) and then illuminating the wafer body (6). The output optical path includes a reflection optical path (14), a detection beam optical path (15), a receiving optical path (16), and an imaging optical path (17). The reflection optical path (14) is formed by the wafer body (6) reflecting the straightening optical path (13) onto the collimating lens group (3). The detection beam optical path (15) is formed by the reflection optical path (14) illuminating the incident surface of the beam splitter (2). The receiving optical path (16) is formed by the detection beam optical path (15) being refracted by the beam splitter (2) and then illuminating the imaging lens group (4). The imaging optical path (17) is formed by the receiving optical path (16) receiving the image through the imaging lens group (4) and then inputting it to the charge coupler (5). The charge coupler (5) converts the optical signal of the imaging optical path (17) into an electrical signal for imaging.

7. The detection optical path of the large warp wafer defect detection device according to claim 6, characterized in that: The illumination angles of the transmitted beam path (12) and the straightening beam path (13) increase as the path of the illumination beam path (11) shortens, in order to detect a wafer body (6) with a concave surface.

8. The detection optical path of the large warp wafer defect detection device according to claim 7, characterized in that: The illumination angles of the transmitted beam path (12) and the straightening beam path (13) decrease as the path of the illumination beam path (11) increases, in order to detect a wafer body (6) with a convex surface.

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