Optical detection system and detection device

Abstract

The application discloses an optical detection system and a detection device, the optical detection system comprises a first light source and a second light source, the first light source has a cavity, the cavity has a hemispherical light-emitting surface, light rays of the first light source pass through an internal space of the cavity and are directed to a to-be-detected object, a through hole is arranged on a cavity wall of the cavity, light rays of the second light source pass through the through hole and the internal space of the cavity and are directed to the to-be-detected object, and the optical detection system further comprises an information acquisition assembly, the information acquisition assembly collects optical information returned by the light rays of the first light source and the light rays of the second light source through the to-be-detected object through the through hole. According to the scheme, the edge region of the to-be-detected object is located in the illumination range of the first light source and the second light source, effective bright field illumination of the edge region of the to-be-detected object can be realized, and the notch inclined surface of the to-be-detected object also has relatively high illumination efficiency.

Description

Technical Field

[0001] This invention relates to the field of detection technology, and in particular to an optical detection system and detection equipment. Background Technology

[0002] Semiconductor chip manufacturing processes are extremely complex. A qualified semiconductor chip requires precise control of each process, and each process must not be contaminated by the previous processes. A small defect, when accumulated through several processes, can significantly affect the yield of the final product and increase manufacturing costs.

[0003] Therefore, the requirements for multi-semiconductor chip inspection equipment are becoming increasingly stringent. Multi-semiconductor chip inspection equipment not only needs to detect defects on the front side of semiconductor chips, but also needs to detect defects on the edges of semiconductor chips.

[0004] Because the slope of the edge region of a semiconductor chip varies greatly, current detection equipment cannot provide effective bright-field illumination for this region. This is especially true for... Figure 1 As shown, for the semiconductor chip 01 with a notch 011 in the edge region (for chip alignment), a vertical surface a and a slope b are formed at the notch 011. The illumination efficiency on the slope b is very low, which makes it impossible to clearly image the notch slope b.

[0005] Therefore, how to effectively illuminate the edge areas of semiconductor chips is a technical problem that needs to be solved by those skilled in the art. Summary of the Invention

[0006] To address the aforementioned technical problems, this invention provides an optical detection system comprising a first light source and a second light source. The first light source has a cavity with a hemispherical light-emitting surface. Light from the first light source passes through the internal space of the cavity and is directed towards the object under test. A through-hole is provided on the cavity wall. Light from the second light source passes through the through-hole and the internal space of the cavity and is directed towards the object under test. The optical detection system further includes an information acquisition component that acquires optical information from the light from the first light source and the light from the second light source reflected back by the object under test through the through-hole.

[0007] In one embodiment, the second light source is a coaxial light source, and the imaging optical axis of the information acquisition component is coaxial with the optical axis of the coaxial light source.

[0008] In one embodiment, the beam splitter of the coaxial light source has a beam splitting ratio of 50%:50%.

[0009] In one embodiment, a plurality of the coaxial light sources are provided, and each of the coaxial light sources is installed on the outer wall of the cavity of the first light source at equal intervals and corresponds one-to-one to the through holes on the first light source.

[0010] In one embodiment, the optical axes of at least two of the coaxial light sources intersect each other.

[0011] In one embodiment, the first light source is a dome light source having a circular opening facing the object to be measured.

[0012] In one embodiment, the light-emitting mode of the first light source and the second light source is a brightening strobe mode.

[0013] In one embodiment, the light-emitting mode of the first light source and the second light source satisfies 2500<n*t*L<5000, wherein t is the light-emitting time, L is the average luminance of light emission within time t, and n is the number of times the light sources emit light within one exposure time.

[0014] In one embodiment, the light-emitting mode of the first light source and the second light source is a constant light mode, and both the first light source and the second light source are provided with heat dissipation structures.

[0015] In one embodiment, the information acquisition assembly includes a detection unit, the detection unit includes a detector, and the aperture of the through hole on the first light source is not less than the clear aperture of the corresponding detector lens.

[0016] In one embodiment, the detector is an area array detector, and the lens of the detector is an object-side telecentric lens.

[0017] In one embodiment, the photographing mode of the detection unit is that all the detectors perform exposure imaging simultaneously.

[0018] In one embodiment, the photographing mode of the detection unit is that the detector takes pictures in multiple steps along the extension direction of the optical axis, and moves by a depth of field length along the optical axis after each photographing.

[0019] In addition, the present invention further provides a detection device, comprising a bearing system for bearing an object to be detected and the optical detection system according to any one of the above, wherein the bearing system can rotate, and the optical detection system detects the object to be detected placed on the bearing system.

[0020] The optical detection system provided by the present invention uses the combination of the first light source and the second light source to achieve effective bright-field illumination of the object to be detected. In application, by placing the edge region of the object to be detected within the irradiation range of the first light source and the second light source, effective bright-field illumination of the edge region of the object to be detected can be achieved, and high illumination efficiency can also be obtained on the notch slope of the object to be detected. Attached Figure Description

[0021] Figure 1 A schematic diagram showing a notch at the edge of a semiconductor chip;

[0022] Figure 2 This is a three-dimensional schematic diagram of an embodiment of the optical detection system provided by the present invention;

[0023] Figure 3 for Figure 2 A sectional view;

[0024] Figure 4 for Figure 2 A schematic diagram showing the positions of the optical axes of the three coaxial light sources and the wall of the notch;

[0025] Figure 5 for Figure 2 Rear view of the central dome light source.

[0026] The annotations in the attached figures are explained as follows:

[0027] 01 chip, 011 notch, a vertical surface, b inclined surface;

[0028] 10 dome light sources, 101 through holes; 20 coaxial light sources; 30 detectors. Detailed Implementation

[0029] To enable those skilled in the art to better understand the technical solution of the present invention, the technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0030] like Figure 2 As shown, the optical detection system provided by the present invention includes a first light source, a second light source, and an information acquisition component.

[0031] The first light source has a cavity with a hemispherical luminescent surface. The light from the first light source is emitted from the luminescent surface of the cavity, passes through the internal space of the cavity, and is directed towards the object to be tested, specifically towards the edge region of the object.

[0032] The cavity wall of the first light source is provided with a through hole 101 (combined with...) Figure 5 (Understanding). The light from the second light source passes through the through-hole 101 on the first light source and is directed toward the object to be measured, specifically toward the edge region of the object.

[0033] The information acquisition component collects optical information from the light from the first light source and the light from the second light source reflected back by the object under test through the through hole 101 on the first light source.

[0034] By applying this solution, effective bright-field illumination can be provided for the edge area of ​​the object under test, ensuring that the edge area of ​​the object under test can be clearly imaged during the inspection process, and preventing defects on the edge area of ​​the object under test from being missed.

[0035] Specifically, the first light source can be a dome light source 10, which has a circular opening facing the object to be measured. Light passes through the circular opening and illuminates the object to be measured.

[0036] Specifically, the second light source can be a coaxial light source 20, and the beam splitting ratio of the beam splitter of the coaxial light source 20 is preferably 50%:50% to obtain higher light efficiency.

[0037] The coaxial light source 20 can be mounted on the outer wall of the cavity of the first light source. The number of coaxial light sources can be one or more (i.e., two or more). Three coaxial light sources 20 are set in the figure. When multiple coaxial light sources 20 are set, multiple through holes 101 need to be set on the first light source accordingly. The light from each coaxial light source 20 passes through the through holes 101 on the first light source and illuminates the object under test.

[0038] Each through hole 101 can be arranged at equal intervals so that each coaxial light source 20 can be installed at equal intervals on the outer wall of the cavity of the first light source, thus achieving better illumination uniformity.

[0039] The optical axes of each coaxial light source 20 can intersect each other, thus ensuring high illumination efficiency on all walls of the notch when there is a notch in the edge region of the object under test. For example, in the illustrated embodiment (e.g.) Figure 4 As shown, when the notch 011 at the edge of the object under test is moved into the circular opening area of ​​the dome light source, the optical axis of the central coaxial light source intersects with the optical axes of the two coaxial light sources at a point, and then disperses to illuminate the wall surface of the notch 011. The optical axis of the central coaxial light source illuminates the vertical surface of the notch 011, and the light from the two coaxial light sources illuminates the inclined surfaces on both sides of the notch. There is high illumination efficiency on both the vertical and inclined surfaces of the notch.

[0040] Specifically, a large diameter of the dome light source 10 would result in a large system footprint, and would also increase the overall size of the coaxial light source 20 and the dome light source 10 in the optical axis direction (i.e., Figure 3 If the distance (M) is too large, the imaging distance of the information acquisition component will be too far, which is not conducive to clear imaging and also to the safety of loading and unloading the object under test. Therefore, the dome light source only needs to meet the opening requirements of the through hole 101, and does not need to be too large. It is more appropriate to set the diameter of the dome light source 10 to be about 50mm, and the overall size of the coaxial light source 20 and the dome light source 10 in the optical axis direction to be less than 110mm.

[0041] Specifically, the coaxial light source 20 and the dome light source 10 can be light sources with a brightened strobe illumination mode. The brightened strobe illumination is a commonly used illumination mode in the industry. In this illumination mode, the light source emits a very high light intensity in a very short time, and the time length is close to the exposure time of the camera, and the light source does not emit light during other non-exposure periods. The total heat generated by this type of light source is relatively small.

[0042] When the coaxial light source 20 and the dome light source 10 are set as light sources in the brightened strobe mode, the preferred configuration is as follows: the illumination time t is configured to be within 70us, the average illumination brightness L is configured to be above 700,000 nit, the duty cycle η is configured to be less than 50%, the lens exposure time nt / η is configured to be 70us, and the number of illumination times n of the light source within one exposure time is configured to be 1 time.

[0043] It should be noted that different chip forming processes result in different surface optical reflection characteristics. Therefore, when detecting different chips, it is necessary to adaptively adjust the strobe time. The adjustment basis is that an image with an average gray level of about 200 DN (Digital Number, pixel brightness value of remote sensing image) is obtained in a relatively short time, and there is no obvious saturation point in the image.

[0044] Alternatively, the coaxial light source 20 and the dome light source 10 can also be light sources whose illumination mode satisfies 2500<n*t*L<5000, wherein t is the illumination time in us, L is the average illumination brightness in nit, and n is the number of illumination times of the light source within one exposure time.

[0045] Alternatively, the coaxial light source 20 and the dome light source 10 can also be constant light sources provided with a heat dissipation structure. The heat dissipation can be specifically air cooling or water cooling.

[0046] Specifically, when the second light source is the coaxial light source 20, the imaging optical axis of the information acquisition component can be arranged coaxially with the optical axis of the coaxial light source 20, which makes the imaging clearer and the detection accuracy higher. The information acquisition component comprises a detection unit, the detection unit comprises a detector 30, and the imaging optical axis of the information acquisition component is the lens optical axis of the detector 30.

[0047] In the illustrated embodiment, three detectors 30 are provided, the lens optical axes of the three detectors 30 respectively coincide with the optical axes of the three coaxial light sources 20, and the apertures of the three through holes on the dome light source 10 are all not less than the light-passing aperture of the lens of the corresponding detector 30.

[0048] Specifically, the detector 30 is preferably an area array detector, and the lens of the detector is preferably an object-side telecentric lens, which can obtain clearer imaging.

[0049] Specifically, the imaging mode of the detection unit can be simultaneous exposure imaging of all detectors 30. During exposure imaging, each coaxial light source 20 and the dome light source 10 emit light synchronously. In this way, the entire area of ​​the target location of the object under test can be imaged in one go.

[0050] Alternatively, the detection unit can also employ a multi-step imaging mode along the optical axis. Each time an image is captured, it moves along the optical axis by one depth of field until the entire target area of ​​the object under test is clearly imaged. Then, the clear portions of all images are selected and stitched together to form a clear image. This method yields a clearer image.

[0051] In addition, the present invention also provides a detection device, including a support system for carrying the object to be tested and an optical detection system as described in any of the above. The support system is capable of rotating the object to be tested, and the optical detection system detects the object to be tested placed on the support system.

[0052] The optical detection system and detection equipment provided by this invention have been described in detail above. Specific examples have been used to illustrate the principles and implementation methods of this invention. The descriptions of the embodiments above are only for the purpose of helping to understand the method and core ideas of this invention. It should be noted that those skilled in the art can make various improvements and modifications to this invention without departing from its principles, and these improvements and modifications also fall within the protection scope of the claims of this invention.

Claims

1. An optical inspection system, characterized in that, The optical detection system comprises a first light source and three second light sources, wherein the first light source is provided with a cavity, the cavity has a hemispherical light-emitting surface, light from the first light source travels through the internal space of the cavity to irradiate a object to be detected, a through hole (101) is arranged on the cavity wall of the cavity, light from the second light sources travels through the through hole (101) and the internal space of the cavity to irradiate the object to be detected, the optical detection system further comprises an information collection assembly, and the information collection assembly collects optical information of the light from the first light source and the light from the second light sources reflected back by the object to be detected through the through hole (101); Optical axes of the three second light sources intersect at one point, and the optical axis of one second light source is located between the optical axes of the other two second light sources, the middle second light source can irradiate the vertical surface of the notch (011) at the edge of the object to be detected, and the two second light sources on both sides can irradiate the two side slopes of the notch (011) at the edge of the object to be detected; the second light source is a coaxial light source (20), and the imaging optical axis of the information collection assembly is coaxial with the optical axis of the coaxial light source (20); the first light source is a dome light source (10) and has a circular opening facing the object to be detected.

2. The optical detection system according to claim 1, characterized in that, The light splitting ratio of the dichroic beam splitter of the coaxial light source (20) is 50%:50%.

3. The optical detection system according to claim 1, characterized in that, Each coaxial light source (20) is installed on the outer wall surface of the cavity of the first light source at equal intervals and corresponds to the through holes (101) on the first light source one by one.

4. The optical inspection system according to any one of claims 1-3, characterized in that, The light-emitting modes of the first light source and the second light sources are brightening stroboscopic modes; Alternatively, the light-emitting modes of the first light source and the second light sources satisfy 2500<n*t*L<5000, wherein t is the light-emitting time, L is the average light-emitting brightness within the time t, and n is the number of light emissions of the light sources in one exposure time; Alternatively, the light-emitting modes of the first light source and the second light sources are constant light modes, and both the first light source and the second light sources are provided with heat dissipation structures.

5. The optical inspection system according to any one of claims 1-3, characterized in that, The information collection assembly comprises a detection unit, the detection unit comprises a detector (30), and the aperture of the through hole (101) on the first light source is not smaller than the light-passing aperture of the lens of the corresponding detector (30).

6. The optical detection system according to claim 5, characterized in that, The detector (30) is an area array detector, and the lens of the detector (30) is an object-side telecentric lens.

7. The optical inspection system according to claim 5, characterized in that, The photographing mode of the detection unit is that all the detectors (30) perform exposure imaging simultaneously; Alternatively, the photographing mode of the detection unit is that the detector (30) performs multi-step photographing along the extending direction of the optical axis, and the detector moves a depth of field length along the optical axis after each photographing.

8. A testing device, characterized in that, Comprises a carrying system for carrying an object to be detected and the optical detection system according to any one of claims 1-7, wherein the carrying system is rotatable, and the optical detection system detects the object to be detected placed on the carrying system.

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