Imaging system for MLED wafer defect detection

Abstract

The imaging system for MLED wafer defect detection is based on the AOI defect detection module and the central wavelength detection module, appearance defects can be effectively detected through the AOI defect detection module, and spectral analysis of a single pixel can be achieved through the central wavelength. And meanwhile, the spectrum of each chip can be positioned. The brightness, the color and the defects of the chip are efficiently detected, and the detection requirements of different types of chips are met. In combination with a high-resolution sensor and an intelligent automatic adjustment function, the system can adjust light source and light path conditions in real time, so that the detection efficiency and accuracy are improved.

Description

Technical Field

[0001] The invention relates to the technical field of MLED, and in particular to an imaging system for MLED wafer defect detection. Background Art

[0002] At present, wafer inspection methods are divided into contact inspection and non-contact inspection. Contact inspection is mainly used now. The representative method of contact inspection is electroluminescence inspection, that is, a micro-electrical probe is used to contact the two electrodes of Micro-LED respectively and inject current to record the electrical and luminous properties of the LED chip. Since the electrical probe needs to contact the LED electrode, the chip electrode, surface and probe may be damaged during the vertical movement, especially when the chip size is less than 50μm, the fine production of the probe and the precise alignment with the chip electrode become more difficult. This damage not only increases the risk of chip damage, but also accelerates the wear of the probe, which leads to a sharp increase in the cost of inspection. And taking Micro-LED as an example, an 8K display requires approximately 90 million Micro-LED chips. The inspection requirements involve the precise arrangement of millions of chips, and the brightness and color consistency requirements of each chip are extremely high, which makes the overall defect detection process extremely complicated.

[0003] Therefore, the accuracy and cost of MLED wafer defect detection are currently facing challenges. Summary of the invention

[0004] In view of the problems existing in the prior art, the present invention provides an imaging system for MLED wafer defect detection to solve the technical problems in the prior art that both the accuracy and detection cost of MLED wafer defect detection are challenged.

[0005] The present invention provides an imaging system for MLED wafer defect detection, comprising:

[0006] An imaging module, comprising a first image receiving objective lens, a second image receiving objective lens, a first beam splitter prism, a second beam splitter prism, a first image sensor, and a second image sensor;

[0007] The AOI defect detection module comprises a first light source, a first lens, a first sensor, a third beam splitter prism, a second beam splitter prism and a high-power objective lens, wherein the first light source sequentially passes through the first lens, the first sensor, the first beam splitter prism, the second beam splitter prism and the high-power objective lens, and is irradiated on the sample to form sample scattered light, and the sample scattered light is collimated by the high-power objective lens, passes through the second beam splitter prism and the first beam splitter prism, and is split by the first beam splitter prism to pass through the first image receiving objective lens, the first image sensor, the second image receiving objective lens and the second image sensor to form an image, and the first central optical axes of the first image receiving objective lens and the first beam splitter prism are coaxially arranged;

[0008] The central wavelength detection module comprises a second light source, a second lens, and a second sensor. The second light source passes through the second lens, the second sensor, the third beam splitter prism, the second beam splitter prism, and the high-power objective lens in sequence, and is irradiated on the sample to form fluorescence. The fluorescence is collimated by the high-power objective lens, passes through the second beam splitter prism and the first beam splitter prism, and is split by the first beam splitter prism to pass through the first image receiving objective lens, the first image sensor, the second image receiving objective lens, and the second image sensor to form an image, and then the central wavelength is calculated. The second central optical axes of the second image receiving objective lens and the first beam splitter prism are coaxially arranged.

[0009] Optionally, the imaging module further includes:

[0010] A bandpass filter is disposed between the first beam splitter prism and the second beam splitter prism, and the bandpass filter is coaxially disposed with the first central optical axis of the first beam splitter prism and the first central optical axis of the second beam splitter prism.

[0011] Optionally, the third beam splitter prism comprises:

[0012] The third beam splitter prism adopts a dichroic mirror.

[0013] Optionally, the first light source includes:

[0014] The first light source is a white light LED, and the transmittance satisfies λ1=400-700nm.

[0015] Optionally, the second light source includes:

[0016] The second light source adopts a purple LED, and the transmittance satisfies λ2≤380nm.

[0017] Optionally, the first lens and the second lens include:

[0018] The focal lengths of the first lens and the second lens satisfy:

[0019] f=D / (2·tan(θ / 2))

[0020] Wherein, f represents the focal length, D represents the clear aperture, and θ represents the divergence angle of the first light source or the second light source.

[0021] Optionally, the light transmittance of the bandpass filter includes:

[0022] The transmittance of the bandpass filter satisfies λ3≤400nm reflection, λ3=400-700nm transmission, and λ3>700nm reflection.

[0023] Optionally, the calculating the central wavelength includes:

[0024] The calculation of the central wavelength is expressed as:

[0025]

[0026] Wherein: I1 represents the image light intensity received by the first image sensor, I2 represents the image light intensity received by the second image sensor, L represents the gradient wavelength spectrum width of the splitting surface of the first splitting prism, W represents the central wavelength of the splitting surface of the first splitting prism, and σ represents the conversion coefficient between theoretical transmittance and actual transmittance.

[0027] Compared with the prior art, the present invention has the following advantages:

[0028] The present invention includes an AOI defect detection module and a central wavelength detection module. Not only can the appearance defects be effectively detected through the AOI defect detection module, but also the spectrum analysis of a single pixel can be realized through the central wavelength. At the same time, the spectrum of each chip can be located. The brightness, color and defects of the chip can be efficiently detected, and the detection requirements of different types of chips can be met. Combined with high-resolution sensors and intelligent automatic adjustment functions, the system can adjust the light source and light path conditions in real time, thereby improving detection efficiency and accuracy. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the invention and, together with the description, serve to explain the principles of the invention.

[0030] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, for ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative labor.

[0031] Figure 1 It is a schematic diagram of the system structure of the present invention;

[0032] Figure 2 for Figure 1 The enlarged structural diagram at A in the middle;

[0033] Figure 3 is a schematic diagram of a transmittance curve of the light splitting surface of the first light splitting prism in the present invention;

[0034] Figure 4 is a schematic diagram of imaging of the first image sensor in the present invention;

[0035] Figure 5 It is a schematic diagram of imaging of the second image sensor in the present invention.

[0036] Description of reference numerals:

[0037] 1. First imaging objective lens; 2. Second imaging objective lens; 3. First dichroic prism; 4. Second dichroic prism; 5. First image sensor; 6. Second image sensor; 7. First light source; 8. First lens; 9. First sensor; 10. Third dichroic prism; 11. High-power objective lens; 12. Second light source; 13. Second lens; 14. Second sensor; 15. Bandpass filter; 16. Sample. DETAILED DESCRIPTION

[0038] In order to make the purpose, technical scheme and advantages of the embodiments of the present application clearer, the technical scheme in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, rather than all of the embodiments. Based on the embodiments in the present application, all other implementation cases obtained by ordinary technicians in this field without making creative work are within the scope of protection of this application. The functional units with the same labels in the examples of the present invention have the same and similar structures and functions.

[0039] See also Figure 1 and Figure 2 The present invention provides an imaging system for MLED wafer defect detection, comprising:

[0040] An imaging module, comprising a first image receiving lens 1, a second image receiving lens 2, a first beam splitter prism 3, a second beam splitter prism 4, a first image sensor 5 and a second image sensor 6;

[0041] The AOI defect detection module comprises a first light source 7, a first lens 8, a first sensor 9, a third beam splitter prism 10, a second beam splitter prism 4 and a high-power objective lens 11. The first light source 7 sequentially passes through the first lens 8, the first sensor 9, the first beam splitter prism 3, the second beam splitter prism 4 and the high-power objective lens 11, and is irradiated on the sample 16 to form sample scattered light. The sample scattered light is collimated by the high-power objective lens 11, passes through the second beam splitter prism 4 and the first beam splitter prism 3, and is split by the first beam splitter prism 3 to pass through the first image receiving objective lens 1, the first image sensor 5, the second image receiving objective lens 2, and the second image sensor 6 to form an image, and the first central optical axes of the first image receiving objective lens 1 and the first beam splitter prism 3 are coaxially arranged;

[0042] The central wavelength detection module includes a second light source 12, a second lens 13, and a second sensor 14. The second light source 12 passes through the second lens 13, the second sensor 14, the third beam splitter prism 10, the second beam splitter prism 4, and the high-power objective lens 11 in sequence, and is irradiated on the sample 16 to form fluorescence. The fluorescence is collimated by the high-power objective lens 11, passes through the second beam splitter prism 4 and the first beam splitter prism 3, and is split by the first beam splitter prism 3 to pass through the first image receiving objective lens 1, the first image sensor 5, the second image receiving objective lens 2, and the second image sensor 6 to form an image, and the central wavelength is calculated, and the second central optical axes of the second image receiving objective lens 2 and the first beam splitter prism 3 are coaxially arranged.

[0043] In this embodiment, in the AOI defect detection module, the distance between the first light source 7 and the first lens 8 can be adjusted to achieve uniform lighting and avoid shadow and reflection interference; the sample scattered light is received and collimated by the high-power objective lens 11, and then transmitted to the imaging module. The image generated by the imaging module can be used for appearance defect detection through the connected intelligent electronic device.

[0044] In the central wavelength detection module, the distance between the second light source 12 and the second lens 13 can also be adjusted to achieve uniform lighting, avoid shadow and reflection interference, use a collimating lens to shape the light beam, reduce the spot area, and improve light utilization; this module mainly uses the corresponding relationship between dual camera pixels to achieve spectral analysis of a single pixel. At the same time, the spectrum of each chip can be located.

[0045] The first image sensor 5 and the second image sensor 6 use high-resolution (6500W pixels) and high-sensitivity image sensors (such as CCD, CMOS, sCCD, sCMOS, etc.), which can capture tiny defects and have a high frame rate to meet dynamic detection requirements. Combined with real-time monitoring sensors, the incident angle and light intensity of the light source are automatically adjusted.

[0046] In another embodiment, the imaging module further includes:

[0047] The bandpass filter 15 is disposed between the first beam splitter prism 3 and the second beam splitter prism 4 , and the bandpass filter 15 is coaxial with the first central optical axis of the first beam splitter prism 3 and the first central optical axis of the second beam splitter prism 4 .

[0048] The light transmittance of the bandpass filter 15 should satisfy reflection, transmission, and reflection, thereby effectively screening the required light wavelength.

[0049] In another embodiment, the third beam splitter prism 10 is a dichroic mirror. The dichroic mirror effectively splits light and guides the light into the chip to be detected, ensuring that the optical path is efficient and accurate. By automatically adjusting the incident angle and intensity of the light source, the detection conditions are optimized in real time, further improving the detection efficiency.

[0050] In another embodiment, the first light source 7 is a white light LED, and the light transmittance satisfies.

[0051] In another embodiment, the second light source 12 is a purple LED, and the transmittance satisfies.

[0052] In another embodiment, the focal lengths of the first lens 8 and the second lens 13 satisfy:

[0053] f=D / (2·tan(θ / 2))

[0054] Wherein, f represents the focal length, D represents the aperture, represents the divergence angle of the first light source 7 or the second light source 12, and the coating parameters should cover the wavelength range = 350nm ~ 700nm, and the absorption transmittance (AbsT) ≥ 99.7%.

[0055] In another embodiment, the calculation of the central wavelength is expressed as:

[0056]

[0057] Wherein: I1 represents the image light intensity received by the first image sensor 5, I2 represents the image light intensity received by the second image sensor 6, L represents the gradient wavelength spectrum width of the splitting surface of the first splitting prism 3, W represents the central wavelength of the splitting surface of the first splitting prism 3, and σ represents the conversion coefficient between theoretical transmittance and actual transmittance.

[0058] In actual use, see Figure 3 , the central wavelength is selected as 550nm, L=300, the light intensities received by the first image sensor 5 and the second image sensor 6 are I1=50, I2=148, σ=0.998, then:

[0059] λc=550+300*0.998*(50-148) / (2*200)=450nm

[0060] The fluorescence center wavelength of sample 16 is selected as 450 nm.

[0061] See also Figure 4 and Figure 5 , please refer to the image collected in this embodiment.

[0062] The present invention is based on the AOI defect detection module and the central wavelength detection module. Not only can the appearance defects be effectively detected through the AOI defect detection module, but also the spectrum analysis of a single pixel can be realized through the central wavelength. At the same time, the spectrum of each chip can be located. The brightness, color and defects of the chip can be efficiently detected, and the detection requirements of different types of chips can be adapted. Combined with high-resolution sensors and intelligent automatic adjustment functions, the system can adjust the light source and light path conditions in real time, thereby improving detection efficiency and accuracy.

[0063] It should be noted that, in this article, relational terms such as "first" and "second" are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, the elements defined by the sentence "comprise a ..." do not exclude the existence of other identical elements in the process, method, article or device including the elements.

[0064] The foregoing is merely a specific embodiment of the present invention, which enables those skilled in the art to understand or implement the present invention. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to the widest scope consistent with the principles and novel features claimed herein.

Claims

1. An imaging system for MLED wafer defect detection, characterized in that: include: An imaging module, comprising a first image receiving objective lens, a second image receiving objective lens, a first beam splitter prism, a second beam splitter prism, a first image sensor, and a second image sensor; The AOI defect detection module comprises a first light source, a first lens, a first sensor, a third beam splitter prism, a second beam splitter prism and a high-power objective lens, wherein the first light source sequentially passes through the first lens, the first sensor, the first beam splitter prism, the second beam splitter prism and the high-power objective lens, and is irradiated on the sample to form sample scattered light, and the sample scattered light is collimated by the high-power objective lens, passes through the second beam splitter prism and the first beam splitter prism, and is split by the first beam splitter prism to pass through the first image receiving objective lens, the first image sensor, the second image receiving objective lens and the second image sensor to form an image, and the first central optical axes of the first image receiving objective lens and the first beam splitter prism are coaxially arranged; The central wavelength detection module comprises a second light source, a second lens, and a second sensor. The second light source passes through the second lens, the second sensor, the third beam splitter prism, the second beam splitter prism, and the high-power objective lens in sequence, and is irradiated on the sample to form fluorescence. The fluorescence is collimated by the high-power objective lens, passes through the second beam splitter prism and the first beam splitter prism, and is split by the first beam splitter prism to pass through the first image receiving objective lens, the first image sensor, the second image receiving objective lens, and the second image sensor to form an image, and then the central wavelength is calculated. The second central optical axes of the second image receiving objective lens and the first beam splitter prism are coaxially arranged.

2. The imaging system for MLED wafer defect detection according to claim 1, characterized in that: The imaging module further includes: A bandpass filter is disposed between the first beam splitter prism and the second beam splitter prism, and the bandpass filter is coaxially disposed with the first central optical axis of the first beam splitter prism and the first central optical axis of the second beam splitter prism.

3. The imaging system for MLED wafer defect detection according to claim 1, characterized in that: The third beam splitter prism comprises: The third beam splitter prism adopts a dichroic mirror.

4. The imaging system for MLED wafer defect detection according to claim 1, characterized in that: The first light source comprises: The first light source adopts a white light LED, and the transmittance satisfies λ1=400-700nm.

5. The imaging system for MLED wafer defect detection according to claim 1, characterized in that: The second light source comprises: The second light source adopts a purple LED, and the transmittance satisfies λ2≤380nm.

6. The imaging system for MLED wafer defect detection according to claim 1, characterized in that: The first lens and the second lens include: The focal lengths of the first lens and the second lens satisfy: f=D / (2·tan(θ / 2)) Wherein, f represents the focal length, D represents the clear aperture, and θ represents the divergence angle of the first light source or the second light source.

7. The imaging system for MLED wafer defect detection according to claim 2, characterized in that: The light transmittance of the bandpass filter includes: The transmittance of the bandpass filter satisfies λ3≤400nm reflection, λ3=400-700nm transmission, and λ3>700nm reflection.

8. The imaging system for MLED wafer defect detection according to claim 1, wherein the calculating center wavelength comprises: The calculation of the central wavelength is expressed as: Wherein: I1 represents the image light intensity received by the first image sensor, I2 represents the image light intensity received by the second image sensor, L represents the gradient wavelength spectrum width of the splitting surface of the first splitting prism, W represents the central wavelength of the splitting surface of the first splitting prism, and σ represents the conversion coefficient between theoretical transmittance and actual transmittance.

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