Laser measurement system and method for gap between chip transfer carrier plate and substrate

Abstract

The invention relates to the technical field of chip precision measurement, and discloses a laser measurement system and method for a gap between a chip transfer carrier plate and a substrate, and the system comprises a laser transmitter, a transmission and reflection separation module, a displacement objective table, and an imaging screen. According to the laser measurement system for the gap between the chip transfer carrier plate and the substrate, the transfer carrier plate and the bearing substrate are arranged on the displacement objective table at intervals, so that a first light beam and a second light beam are reflected by the transfer carrier plate, refracted and then reflected, and reflected by the bearing substrate, refracted and then reflected; when the transfer carrier plate deflects or moves relative to the bearing substrate, the first light beam and the second light beam are reflected by the transfer carrier plate, refracted and reflected again, and reflected by the bearing substrate, and then the first light beam and the second light beam form a plurality of light spots on the imaging screen. The positions of the multiple light spots formed on the imaging screen are changed, the imaging screen measures the distance values of the changed light spots, and the precision measurement of the gap between the chip transfer carrier plate and the bearing substrate is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of chip precision measurement, and in particular to a laser measurement system and method for the gap between a chip transfer carrier and a substrate. Background Art

[0002] The new display technology of Micro-LED chips has the advantages of high brightness, high contrast, low power consumption, fast response speed and long life, and has been considered by the industry as an important development direction of the next generation of new display technology. The preparation process of Micro-LED chip display panels is numerous and complex. Among them, the Micro-LED chips grown on the carrier need to be accurately aligned and transferred to the receiving substrate. The consistency of the gap between the transfer carrier and the receiving substrate is the key to achieving large-scale transfer, which directly affects the yield and production efficiency of the entire product. For this reason, it is urgent to measure the gap between the Micro-LED chip transfer carrier and the receiving substrate closely, and then feed it back to the adjustment mechanism to adjust the gap between the chip transfer carrier and the receiving substrate to meet the required size specifications, so as to improve the transfer yield and efficiency of the chip.

[0003] Usually, during the transfer process, the gap between the transfer carrier and the receiving substrate needs to be controlled between 30 and 50 μm. When the gap between the transfer carrier and the receiving substrate is uneven, the transferred chip will be offset, overturned, and the chip transfer will be missing; especially when the carrier and the receiving substrate are not parallel, the chip transfer will be misaligned. The precise control of the gap between the transfer carrier and the receiving substrate directly determines the yield and efficiency of laser mass transfer. The precise measurement of the gap between the transfer carrier and the receiving substrate is also the prerequisite for precise adjustment of the gap, and is also the key to improving the yield and efficiency of laser mass transfer.

[0004] Due to the small gap between the transfer carrier and the receiving substrate, and the obstruction of chips with different arrangements, traditional contact measurement cannot achieve accurate measurement. It is urgent to break through the non-contact measurement method to measure the gap between the carrier and the substrate. Patent CN 116007515A proposes a white light interferometric focusing system and demodulation method, which calculates the gap value between the template and the substrate by using the feedback spectral value. However, in the measurement of the transfer gap of the Micro-LED chip, the GaN-based Micro-LED chip absorbs light in the blue-green band, so using the spectral signal to measure the transfer gap will cause a large error; Patent CN 115546172A proposes a method for measuring the transfer gap using machine vision, but this method is greatly affected by environmental factors such as lighting conditions and background noise, and puts forward certain requirements on the arrangement of the measured chip and the surface morphology of the measured substrate, which is difficult to meet the measurement needs during normal production; Patent CN 114623774A proposes a method for measuring the transfer gap by combining a light source and a photosensitive receptor, but this method can only achieve the overall gap measurement of the two substrates, and it is difficult to achieve a small range gap measurement of a specific area on the substrate, and the installation of the light source and the photosensitive receptor will increase the complexity of the machine layout.

[0005] To this end, this solution designs a laser measurement system and method for the gap between a chip transfer carrier and a substrate. After the laser beam is irradiated to the multi-interface refraction and reflection of the transfer carrier and the target basic surface, the reflected light spot projected onto the imaging screen is accurately measured multiple times to achieve the measurement of the gap between the chip carrier and the substrate. The use of 650nm laser for irradiation measurement avoids the problem that Micro-LED easily absorbs blue-green band light signals, solves the limitation that single-point laser cannot achieve range measurement, effectively reduces the influence of external environmental factors such as light, and greatly saves measurement costs while ensuring high precision, achieving high-precision measurement of the gap between the Micro-LED chip transfer carrier and the receiving substrate. Summary of the invention

[0006] The first object of the present invention is to provide a laser measurement system for the gap between a chip transfer carrier and a substrate, aiming to solve the problem of high-precision measurement of the gap between a chip transfer carrier and a receiving substrate.

[0007] In order to solve the above technical problems, a laser measurement system for the gap between a chip transfer carrier and a substrate is provided, comprising a laser transmitter, a transflection separation module, a displacement stage and an imaging screen; the transflection separation module comprises a first lens, a second lens and a reflector, the first lens and the second lens are offset and perpendicular, part of the light beam emitted by the laser transmitter is reflected by the first lens to generate a first light beam, and the other part is generated after passing through the first lens to generate a second light beam, the second light beam is emitted to the reflector, and is reflected by the reflector to the second lens to reflect the second light beam, so that the first light beam and the second light beam are parallel; a transfer carrier and a receiving substrate are placed on the displacement stage at intervals, the first light beam and the second light beam are reflected, refracted and then reflected by the transfer carrier and reflected, refracted and then reflected by the receiving substrate respectively; after the first light beam and the second light beam are reflected, refracted and then reflected by the transfer carrier and reflected, refracted and then reflected by the receiving substrate respectively, a plurality of light spots are formed on the imaging screen, and the imaging screen is used to measure the distance of each light spot;

[0008] Among them, when the transfer carrier is deflected or moved relative to the receiving substrate, the positions of multiple light spots formed on the imaging screen after the first light beam and the second light beam are reflected, refracted and then reflected by the transfer carrier and reflected, refracted and then reflected by the receiving substrate change, so that the imaging screen measures the distance value of each light spot after the change.

[0009] Furthermore, the reflector is formed with a first reflective surface and a second reflective surface which are vertically arranged. After the second light beam is incident on the first reflective surface at a first angle, it is reflected to the second reflective surface, and then is emitted from the second reflective surface to the second lens at a second angle via the second reflective surface, wherein the angle difference between the first angle and the second angle is 180°, so that the first light beam and the second light beam are spaced parallel lights emitted to the displacement stage.

[0010] Furthermore, when there is local deformation on the surface of the transfer carrier or the receiving substrate, the positions of the light spots formed by the first light beam on the imaging screen are different relative to those of the second light beam, so that the distance values ​​of the light spots measured by the imaging screen are different.

[0011] Furthermore, the laser transmitter comprises a laser component, a collimating lens, a Galilean beam reducer and an aperture, wherein the aperture is arranged away from the laser component, the collimating lens is located between the laser component and the aperture, and the Galilean beam reducer is located between the collimating lens and the aperture.

[0012] Furthermore, the Galilean beam reduction assembly includes a convex lens and a concave lens, wherein the convex lens is arranged on a side close to the collimating lens, and the concave lens is arranged on a side close to the aperture, so as to reduce the beam of the laser emitted by the laser component.

[0013] Furthermore, the laser measurement system for the gap between the chip transfer carrier and the substrate also includes an identification component and a data processing module, the identification component includes a camera and a filter lens located at the camera lens, the data processing module is electrically connected to the camera, the camera is used to observe the light spots of the transfer carrier and the receiving substrate and the light spot position information on the imaging screen, and the data processing module is used to collect the light spots and light spot position information recorded by the camera.

[0014] The second object of the present invention is to provide a laser measurement method for the gap between a chip transfer carrier and a substrate, aiming to solve the problem of a high-precision measurement method for the gap between a chip transfer carrier and a receiving substrate.

[0015] In order to solve the above technical problems, a laser measurement method for the gap between a chip transfer carrier and a substrate is provided, which is applicable to the above-mentioned laser measurement system for the gap between a chip transfer carrier and a substrate, and comprises the following steps:

[0016] S1, placing the transfer carrier and the receiving substrate on the displacement stage in a wafer stacking unit structure;

[0017] S2, turning on the laser emitter, and deflecting the first lens, the second lens, and the reflector in the transmission-reflection separation module at a suitable angle, so that the first light beam and the second light beam are respectively reflected on the surfaces of the first lens and the second lens and then projected onto the transfer carrier and the receiving substrate;

[0018] S3, the first light beam and the second light beam are transmitted in the form of parallel light on the wafer stacking unit composed of the transfer carrier and the receiving substrate, and after being reflected and refracted in the wafer stacking unit, the first light beam and the second light beam respectively form four reflected light beams, and are projected on the imaging screen to form light spots;

[0019] S4, photographing the light spots in the imaging screen in S3 with a camera to obtain an image containing the eight light spots;

[0020] S5, performing image processing on the light spots in S4 based on the data processing module, extracting the center points and center coordinates of the eight light spots in the light spot image, and obtaining the nonlinear relationship between the light spots on the surfaces of the transfer carrier and the receiving substrate and the center points of the light spots in the imaging screen in S3 through calibration of the object points and the image points;

[0021] S6, based on the laser reflection measurement, the lower surface of the receiving substrate is used as the reference surface, and based on the center coordinates of the imaging screen light spot in S3, the position coordinates of the light spot projected on the upper and lower surfaces of the transfer carrier and the upper surface of the receiving substrate are derived and calculated;

[0022] S7, the displacement stage performs a uniform displacement in the horizontal direction, the camera continuously takes pictures of the light spot and the light spot image at a fixed frequency, the data processing module performs data analysis on the change of the center position of the light spot, calculates the thickness of the transfer carrier and the receiving substrate and the change of the gap between them, and derives the deflection angle required for leveling between the transfer carrier and the receiving substrate.

[0023] Furthermore, the spot spacing formed by the first light beam or the second light beam on the imaging screen is denoted as x. i , let the thickness of the i-th interface be d i , satisfying the relationship:

[0024]

[0025] Where i represents the number of layers measured (i = 1, 2, 3, 4, ...); θ i represents the incident angle of the light on the upper surface of the i-th layer; n i represents the refractive index of the i-th layer, where n 0 Specifically refers to the refractive index of air.

[0026] Furthermore, when the transfer carrier is deflected relative to the receiving substrate, the spot spacing originally formed on the imaging screen reflecting the thickness of the transfer carrier is recorded as x. 1 After the transfer carrier is deflected, the spot spacing reflecting the thickness of the transfer carrier re-formed on the imaging screen is x 1 ', then the spot spacing x formed by the imaging screen is 1 The distance x from the re-formed light spot on the imaging screen 1 'The difference is Δx, which satisfies the relationship:

[0027]

[0028] Wherein, Δx represents the spot spacing x formed by the imaging screen. 1 The spot spacing x re-formed with the imaging screen 1 ', α represents the deflection angle of the transfer carrier, counterclockwise deflection is positive, clockwise deflection is negative; θ 1 n represents the incident angle of the light on the upper surface of the transfer carrier; 1 n represents the refractive index on the upper surface of the transfer carrier; 2 represents the refractive index at the lower surface of the transfer carrier; d 1Indicates the thickness of the transfer carrier.

[0029] Furthermore, when the transfer carrier is deflected relative to the receiving substrate, the spot spacing x originally formed by the imaging screen 1 The distance x from the re-formed light spot on the imaging screen 1 'Difference Δx difference leveling, when the Δx value is negative, rotate clockwise to level the transfer carrier; when the Δx value is positive, rotate counterclockwise to level the transfer carrier.

[0030] Implementing the embodiments of the present invention will have the following beneficial effects:

[0031] 1. In the laser measurement system for the gap between a chip transfer carrier and a substrate in this embodiment, since the transfer carrier and the receiving substrate are placed at intervals on the displacement stage, the first light beam and the second light beam are respectively reflected, refracted and then reflected by the transfer carrier and reflected, refracted and then reflected by the receiving substrate, so that the first light beam and the second light beam respectively form a plurality of light spots on the imaging screen, and then when the transfer carrier deflects or moves relative to the receiving substrate, the first light beam and the second light beam are respectively reflected, refracted and then reflected by the transfer carrier and reflected, refracted and then reflected by the receiving substrate, the positions of the plurality of light spots formed on the imaging screen change, and the imaging screen measures the distance value of each light spot after the change, thereby overcoming the problems of large measurement error and low measurement efficiency of the gap between the chip transfer carrier and the receiving substrate;

[0032] 2. In the laser measurement system for the gap between the chip transfer carrier and the substrate in the present embodiment, since the reflector is formed with a first reflective surface and a second reflective surface arranged vertically, after the second light beam is incident on the first reflective surface at a first angle, it is reflected to the second reflective surface, and then emitted from the second reflective surface to the second lens at a second angle via the second reflective surface, wherein the angle difference between the first angle and the second angle is 180°, so that the first light beam and the second light beam are spaced parallel light beams emitted to the displacement stage, and then when there is local deformation on the surface of the transfer carrier or the receiving substrate, the position of the light spot formed by the first light beam relative to the second light beam on the imaging screen is different, so that the distance values ​​of each light spot measured by the imaging screen are different, thereby avoiding the systematic error of measuring the transfer carrier or the receiving substrate with a single light beam, and improving the accuracy of the gap measurement between the transfer carrier and the receiving substrate;

[0033] 3. The laser measurement system for the gap between the chip transfer carrier and the substrate in this embodiment, since the laser emitter includes a laser component, a collimating lens, a Galileo beam reduction assembly and an aperture, the aperture is arranged away from the laser component, the collimating lens is located between the laser component and the aperture, and the Galileo beam reduction assembly is located between the collimating lens and the aperture, wherein the Galileo beam reduction assembly includes a convex lens and a concave lens, the convex lens is arranged close to the collimating lens, and the concave lens is arranged close to the aperture, so as to reduce the laser emitted by the laser component, thereby constraining the size of the light spot formed on the imaging screen, determining the center coordinates of the light spot and calculating the displacement of the light spot, and improving the accuracy of the gap measurement between the transfer carrier and the receiving substrate;

[0034] 4. The laser measurement method for the gap between the chip transfer carrier and the substrate in this embodiment is as follows: since the transfer carrier and the receiving substrate are arranged on the displacement stage in the structure of a wafer stacking unit; the laser emitter is turned on, and the first lens, the second lens and the reflector in the transmission and reflection separation module are deflected at a suitable angle, so that the first light beam and the second light beam are respectively reflected on the surfaces of the first lens and the second lens and projected onto the transfer carrier and the receiving substrate; the first light beam and the second light beam are transmitted on the wafer stacking unit composed of the transfer carrier and the receiving substrate in the form of parallel light, so that after reflection and refraction in the wafer stacking unit, the first light beam and the second light beam respectively form four reflected light beams, and are projected onto the imaging screen to form light spots; the camera captures the light spots in the imaging screen in step 3 to obtain an image containing 8 light spots; the data processing module processes the light spots in step 3 4 is subjected to image processing, and the center points and center coordinates of the eight light spots in the light spot image are extracted. Through the calibration of the object point and the image point, the nonlinear relationship between the light spots on the surfaces of the transfer carrier and the receiving substrate and the center points of the light spots in the imaging screen in step 3 is obtained; then, according to the laser reflection measurement, the lower surface of the receiving substrate is used as the reference surface, and according to the center coordinates of the light spots on the imaging screen in step 3, the position coordinates of the light spots projected on the upper and lower surfaces of the transfer carrier and the upper surface of the receiving substrate are derived and calculated; the displacement stage is uniformly displaced in the horizontal direction, and the camera continuously photographs the light spots and the light spot images at a fixed frequency. The data processing module performs data analysis and processing on the change of the center position of the light spot, calculates the thickness of the transfer carrier and the receiving substrate and the change of the gap between the two, and derives and determines the deflection angle required for leveling between the transfer carrier and the receiving substrate. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] 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, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0036] Figure 1 A schematic diagram of a laser measurement system for the gap between a chip transfer carrier and a substrate according to Embodiment 1 of the present invention;

[0037] Figure 2 This is a schematic diagram of the structure of the laser transmitter according to the first embodiment of the present invention;

[0038] Figure 3 This is a schematic structural diagram of a transflective-reflective separation module according to Embodiment 1 of the present invention;

[0039] Figure 4 This is a schematic structural diagram of a normal state of a wafer stacking unit according to Embodiment 1 of the present invention;

[0040] Figure 5 is a schematic structural diagram of a reflector according to Embodiment 1 of the present invention;

[0041] Figure 6 This is a schematic structural diagram of abnormal deflection of a wafer stacking unit according to Embodiment 1 of the present invention;

[0042] Figure 7 This is a flow chart of a laser measurement method for the gap between a chip transfer carrier and a substrate according to a second embodiment of the present invention.

[0043] Wherein: 100, chip transfer carrier and substrate gap laser measurement system; 110, laser transmitter; 111, laser components; 112, collimating lens; 113, Galileo beam shrinking assembly; 1131, convex lens; 1132, concave lens; 114, aperture; 115, first light beam; 116, second light beam; 120, transmissive-reflective separation module; 121, first lens; 122, second lens; 123, reflector; 1231, first reflection surface; 1232, second reflection surface; 130, displacement stage; 131, transfer carrier; 132, receiving substrate; 1301, wafer stacking unit; 140, imaging screen; 150, identification assembly; 151, camera; 152, filter lens; 160, data processing module. DETAILED DESCRIPTION

[0044] In order to facilitate the understanding of the present invention, the present invention will be described more fully below with reference to the relevant drawings. The preferred embodiments of the present invention are given in the drawings. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the understanding of the disclosure of the present invention more thorough and comprehensive.

[0045] It should be noted that when an element is referred to as being "fixed to" another element, it may be directly on the other element or there may be a central element. When an element is considered to be "connected to" another element, it may be directly connected to the other element or there may be a central element at the same time. The terms "vertical", "horizontal", "left", "right" and similar expressions used herein are for illustrative purposes only.

[0046] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art of the present invention. The terms used herein in the specification of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention. The term "and / or" used herein includes any and all combinations of one or more related listed items.

[0047] Embodiment 1

[0048] Please refer to Figure 1-Figure 6The first embodiment of the present invention provides a laser measurement system 100 for the gap between a chip transfer carrier and a substrate, comprising a laser emitter 110, a transmissive-reflective separation module 120, a displacement stage 130 and an imaging screen 140; the transmissive-reflective separation module 120 comprises a first lens 121, a second lens 122 and a reflector 123, the first lens 121 and the second lens 122 are vertically offset, a portion of the light beam emitted by the laser emitter 110 is reflected by the first lens 121 to generate a first light beam 115, and another portion of the light beam is reflected by the first lens 121 to generate a second light beam 116, the second light beam 116 is emitted to the reflector 123, and the second light beam 116 is emitted to the reflector 123. 123 is reflected to the second lens 122 to reflect the second light beam 116, so that the first light beam 115 and the second light beam 116 are parallel; the displacement stage 130 is provided with a transfer carrier 131 and a receiving substrate 132 at intervals, the first light beam 115 and the second light beam 116 are respectively reflected and refracted and reflected by the transfer carrier 131 and reflected and refracted and reflected by the receiving substrate 132; after the first light beam 115 and the second light beam 116 are respectively reflected and refracted and reflected by the transfer carrier 131 and reflected and refracted and reflected by the receiving substrate 132, a plurality of light spots are formed on the imaging screen 140, and the imaging screen 140 is used to measure the distance of each light spot. Specifically, the laser emitter 110 can emit a point-shaped collimated laser with a horizontal spot size of 10 to 50 μm, and the laser is a red laser with a wavelength of 650 nm; the first lens 121 is deflected and placed in a clockwise direction, and its placement angle is a. When the point-shaped collimated laser passes through the first lens 121, it will be reflected and refracted on its surface. The reflected light beam is the first light beam 115 and is emitted at an angle of 2a clockwise to the displacement stage 130. The refracted light beam is the second light beam 116 and continues to be emitted in a horizontal manner. After passing through the reflector 123, it rotates 180°, and then passes through the second lens 122. The second light beam 116 is emitted at an angle of 180-2b to the displacement stage 130. To ensure that the light beams are parallel, the first lens 121 and the second lens 122 are placed in the same position, and the deflection angle a of the first lens 121 and the deflection angle b of the second lens 122 are mutually complementary. In addition, the transfer carrier 131 and the receiving substrate 132 constitute a wafer stacking transfer unit, which is used to present the positional relationship between the transfer substrate and the receiving substrate 132 during the mass transfer of Micro-LED chips, that is, the gap between the transfer carrier 131 and the receiving substrate 132 is 30 to 50 μm during the mass transfer of Micro-LED chips.

[0049] Among them, when the transfer carrier 131 is deflected or moved relative to the receiving substrate 132, the positions of multiple light spots formed on the imaging screen 140 are changed after the first light beam 115 and the second light beam 116 are reflected, refracted and then reflected by the transfer carrier 131 and reflected, refracted and then reflected by the receiving substrate 132, so that the imaging screen 140 measures the distance value of each light spot after the change. In a specific application, since the displacement stage 130 is provided with a transfer carrier 131 and a receiving substrate 132 at intervals, the first light beam 115 and the second light beam 116 are respectively reflected, refracted and then reflected by the transfer carrier 131 and reflected, refracted and then reflected by the receiving substrate 132, so that the first light beam 115 and the second light beam 116 respectively form a plurality of light spots on the imaging screen 140. Then, when the transfer carrier 131 deflects or moves relative to the receiving substrate 132, that is, when the transfer carrier 131 deflects an angle relative to the receiving substrate 132, the angles of the first light beam 115 and the second light beam 116 after being reflected, refracted and then reflected by the transfer carrier 131 and reflected, refracted and then reflected by the receiving substrate 132 change, and when the transfer carrier 131 deflects a micro-angle relative to the receiving substrate 132, a plurality of light spots are formed on the imaging screen 140. The position of the light spot will also change significantly, so that the imaging screen 140 can be used to sensitively measure the distance value of each light spot after the change, and then measure whether the transfer carrier 131 is deflected relative to the receiving substrate 132; similarly, when the gap between the transfer carrier 131 and the receiving substrate 132 changes from 30 to 50 μm, the distances of the first light beam 115 and the second light beam 116 after reflection, refraction and re-reflection by the transfer carrier 131 and reflection, refraction and re-reflection by the receiving substrate 132 will change, and the positions of multiple light spots formed on the imaging screen 140 will also change significantly, and the position change of the light spots with such changes in displacement and deflection angles has independent distinguishability, that is, the spacing ratio of the light spots in the imaging screen 140 is different, and it is easy to identify the change in the deflection or movement of the transfer carrier 131 relative to the receiving substrate 132.

[0050] In one possible embodiment, the reflector 123 is formed with a first reflective surface 1231 and a second reflective surface 1232 which are vertically arranged. After the second light beam 116 is incident on the first reflective surface 1231 at a first angle, it is reflected to the second reflective surface 1232, and then is emitted from the second reflective surface 1232 to the second lens 122 at a second angle via the second reflective surface 1232, wherein the angle difference between the first angle and the second angle is 180°, so that the first light beam 115 and the second light beam 116 are spaced parallel lights emitted to the displacement stage 130. In a specific application, since the reflector 123 is formed with a first reflective surface 1231 and a second reflective surface 1232 which are vertically arranged, the second light beam 116 is incident on the first reflective surface 1231 at a first angle, reflected to the second reflective surface 1232, and emitted from the second reflective surface 1232 to the second lens 122 at a second angle via the second reflective surface 1232, wherein the angle difference between the first angle and the second angle is 180°, so that the first light beam 115 and the second light beam 116 are spaced parallel lights emitted to the displacement stage 130. It is worth noting that when the position of the second light beam 116 hitting the first reflective surface 1231 is different, the position of the second light beam 116 reflected to the second reflective surface 1232 is also different, that is, the width of the second light beam 116 between the first reflective surface 1231 and the second reflective surface 1232 is different, so that the width between the first light beam 115 and the second light beam 116 can be flexibly adjusted.

[0051] In a possible implementation, when there is local deformation on the surface of the transfer carrier 131 or the receiving substrate 132, the positions of the light spots formed by the first light beam 115 on the imaging screen 140 are different relative to the second light beam 116, so that the distance values ​​of each light spot measured by the imaging screen 140 are different. In specific applications, when there is local deformation on the surface of the transfer carrier 131 or the receiving substrate 132, if only one beam of light, such as the first beam 115 or the second beam 116, is used to measure the distance value of each light spot (a group of light spots) on the measuring imaging screen 140, then when the first beam 115 or the second beam 116 happens to fall into the local deformation area of ​​the transfer carrier 131 or the receiving substrate 132, there will be a problem of low measurement accuracy. Therefore, two beams of parallel light (separated by a certain distance) are introduced, that is, the first beam 115 and the second beam 116 simultaneously form multiple light spots (two groups of light spots) on the imaging screen 140. Only when the distance values ​​of each light spot in the two groups of light spots are the same, can the quality problems of the transfer carrier 131 or the receiving substrate 132 itself be verified.

[0052] In a possible implementation, the laser emitter 110 includes a laser component 111, a collimating lens 112, a Galileo beam reduction assembly 113 and an aperture 114. The aperture 114 is arranged away from the laser component 111, the collimating lens 112 is located between the laser component 111 and the aperture 114, and the Galileo beam reduction assembly 113 is located between the collimating lens 112 and the aperture 114. In a specific application, the laser component is mainly used to output a point-shaped red laser with a wavelength of 650nm; the collimating lens 112 is mainly used to collimate the laser with a certain scattering angle emitted by the laser for the first time, so that the laser propagates in a horizontal plane as a parallel beam; the pinhole aperture 114 is mainly used to further reduce the beam diameter of the light beam to meet the measurement requirements of measuring the transfer gap of the Micro-LED wafer; in addition, it can also eliminate stray light, reduce interference, and improve the beam quality.

[0053] In a possible implementation, the Galileo beam reduction assembly 113 includes a convex lens 1131 and a concave lens 1132, wherein the convex lens 1131 is disposed on a side close to the collimating lens 112, and the concave lens 1132 is disposed on a side close to the aperture 114, so as to reduce the beam of laser light emitted by the laser component 111. In a specific application, the Galileo beam reduction assembly 113 mainly reduces the parallel light beam after the first collimation, ensures the concentrated propagation of the light beam energy, reduces the subsequent energy loss through the aperture 114, and facilitates the subsequent laser imaging. The beam reduction process is as follows: after the first collimation, a wider parallel laser beam enters the system, and the laser beam first passes through the beam reduction convex lens 1131. The function of the convex lens 1131 is to make the beam begin to shrink through the convex lens with a longer focal length, but not to focus the beam completely to one point; after the laser beam passes through the convex lens 1131, it enters the beam reduction concave lens 1132 at a certain shrinking angle. The function of the concave lens 1132 is to use its negative focal length to offset the focusing effect of the beam reduction convex lens 1131, so that the laser beam is emitted horizontally with a smaller beam diameter.

[0054] In a possible embodiment, the chip transfer carrier and substrate gap laser measurement system 100 also includes an identification component 150 and a data processing module 160, the identification component 150 includes a camera 151 and a filter lens 152 located at the lens of the camera 151, the data processing module 160 is electrically connected to the camera 151, the camera 151 is used to observe the light spots of the transfer carrier 131 and the receiving substrate 132 and the light spot position information on the imaging screen 140, and the data processing module 160 is used to collect the light spots and light spot position information recorded by the camera 151. In specific applications, the camera 151 is mainly used to observe the light spots of the transfer carrier 131 and the receiving substrate 132 and to capture the specific position and changes of the light spots of the imaging screen 140. By monitoring the changes in the center position of the light spots and cooperating with the displacement module, continuous data acquisition is achieved to achieve accurate measurement of the height changes of the wafer gap; the filter lens 152 is mainly used to filter out the interference of stray light and improve the measurement accuracy; the data processing module 160 is mainly used to process the images collected by the camera 151 to extract the coordinates of the center point of the light spot, and use the nonlinear relationship between the object point and the image point to convert complex laser reflection data into accurate thickness, gap and leveling information.

[0055] In principle, a red laser with a wavelength of 650nm is used as the measurement light source. The scattered laser emitted by the laser component 111 is shaped by the laser emitter 110 and then emitted in the form of a microbeam horizontal laser. The size of the beam can be adjusted by changing the size of the aperture 114. The microbeam horizontal laser can achieve oblique incidence of two parallel laser beams after passing through the transflection separation module 120, thereby better ensuring the parallelism and consistency of the laser. After the two laser beams are reflected on the surfaces of the transfer carrier 131 and the receiving substrate 132, the optical imaging screen 140 is used to receive the light spot and the camera 151 is used to identify and capture the light spot, thereby avoiding damage to the camera 151 caused by direct laser irradiation and ensuring measurement accuracy. The measurement of two parallel laser beams can effectively reduce the displacement steps during platform measurement, reduce the need for manual intervention and mechanical errors.

[0056] Embodiment 2

[0057] The subject matter protected by this embodiment is different from that of the first embodiment, and the specific differences are as follows:

[0058] Please refer to Figure 7 The second embodiment of the present invention provides a laser measurement method for the gap between a chip transfer carrier 131 and a substrate, which is applicable to the laser measurement system 100 for the gap between a chip transfer carrier and a substrate, and includes the following steps:

[0059] S1, placing the transfer carrier 131 and the receiving substrate 132 on the displacement stage 130 in the structure of a wafer stacking unit 1301;

[0060] S2, turning on the laser emitter 110, and deflecting the first lens 121, the second lens 122 and the reflector 123 in the transmission-reflection separation module 120 at a suitable angle, so that the first light beam 115 and the second light beam 116 are respectively reflected on the surfaces of the first lens 121 and the second lens 122 and projected onto the transfer carrier 131 and the receiving substrate 132;

[0061] S3, the first light beam 115 and the second light beam 116 are transmitted in the form of parallel light on the wafer stacking unit 1301 composed of the transfer carrier 131 and the receiving substrate 132. After being reflected and refracted in the wafer stacking unit 1301, the first light beam 115 and the second light beam 116 respectively form four reflected light beams, and are reflected on the imaging screen 140

[0062] The light spot is projected upward;

[0063] S4, photographing the light spots in the imaging screen 140 in S3 with the camera 151 to obtain an image containing 8 light spots;

[0064] S5, based on the data processing module 160, the light spot in S4 is processed to extract

[0065] The center point and center coordinates of the 8 focused light spots are obtained by calibrating the object point and the image point to obtain the transfer carrier 131

[0066] and a nonlinear relationship between the light spot on the surface of the receiving substrate 132 and the center point of the light spot in the imaging screen 140 in S3;

[0067] S6, according to the laser reflection measurement, the lower surface of the receiving substrate 132 is used as the reference surface, and the imaging screen in S3 is used as the reference surface.

[0068] The center coordinates of the light spot 140 are derived and calculated by projecting the light spot on the upper and lower surfaces of the transfer carrier 131 and the receiving substrate 132

[0069] Position coordinates of the upper surface;

[0070] S7. The displacement stage 130 is displaced at a uniform speed in the horizontal direction, and the camera 151 continuously photographs the light spot and the light spot image at a fixed frequency. The data processing module 160 performs data analysis on the change in the center position of the light spot, calculates the thickness of the transfer carrier 131 and the receiving substrate 132 and the change in the gap between them, and derives the deflection angle required for leveling between the transfer carrier 131 and the receiving substrate 132. In a specific application, the transfer carrier 131 and the receiving substrate 132 are fixed on the displacement stage in the structure of the wafer stacking unit 1301; the laser emitter 110 is turned on, and the first lens 121 and the second lens 122 of the transmissive-reflective separation module 120 are deflected at a suitable angle so that the laser can be effectively transmitted to the transfer carrier 131 and the receiving substrate 132 after being reflected on the surface of the first lens 121 and the second lens 122; the two laser beams are transmitted on the transfer carrier 131 and the receiving substrate 132 in the form of parallel light.

[0071] On the wafer stacking unit 1301 composed of the transfer carrier 131 and the receiving substrate 132, after reflection and refraction in the wafer stacking unit 1301, each laser beam forms four reflected light beams, and images are formed on the optical imaging screen 140; the laser spot in step 3 is photographed by the camera 151 to obtain an image containing 8 laser spots; the spot image in step 4 is processed by a computer to extract the center points and center coordinates of the 8 relay light spots in the spot image, and the transfer carrier 131 and the receiving substrate 132 are obtained by calibrating the object point and the image point.

[0072] The nonlinear relationship between the light spot on the surface and the center point of the laser spot described in step 3; using the principle of laser reflection measurement, taking the lower surface of the receiving substrate 132 as the reference plane, according to the center of the laser light plate described in step 3 Coordinates, derived light The spots are transmitted on the upper and lower surfaces of the transfer substrate, receiving the actual position coordinates of the upper surface of the substrate 132; The displacement module is used to perform uniform displacement in the x direction, the camera 151 is used to continuously photograph the light spot image at a fixed frequency, and the data processing module 160 is used to perform data analysis on the change of the center position of the light spot. The change of the thickness of the transfer carrier 131 and the receiving substrate 132 and the wafer gap, as well as the deflection angle required for leveling between the transfer carrier 131 and the receiving substrate 132 can be calculated.

[0073] In a possible implementation manner, the spot spacing formed by the first light beam 115 or the second light beam 116 on the imaging screen 140 is denoted as x. i , let the thickness of the i-th interface be d i , satisfying the relationship:

[0074]

[0075] Where i represents the number of layers measured (i = 1, 2, 3, 4, ...); θ i represents the incident angle of the light on the upper surface of the i-th layer; ni represents the refractive index of the i-th layer, where n 0 Specifically refers to the refractive index of air. In a specific application, a laser multi-reflection measurement system is constructed, and a micro-beam horizontal laser is emitted by the laser emitter 110, wherein the beam size of the micro-beam horizontal laser is mainly determined by the pinhole aperture 114. In actual measurement, since the spacing between the chips on the transfer carrier 131 and the receiving substrate 132 is about 70μm, in order to ensure better measurement accuracy, a pinhole aperture 114 with a diameter of 50μm can be selected; the laser first passes through the first lens 121 in the transmissive-reflective separation module 120 and is separated into a first light beam 115 and a second light beam 116, wherein the clockwise deflection angle of the first lens 121 is a, and the first light beam 115 is emitted to the wafer stack transfer unit 1301 at a deflection angle of 2a, and the second light beam 116 is emitted to the wafer stack transfer unit 1301 at a deflection angle of 2a. The horizontal angle continues to propagate, and after passing through the reflector 123, a 180° deflection on the horizontal plane is achieved. The reflected second light beam 116 is reflected on the surface of the second lens 122. Since the counterclockwise deflection angle of the second lens 122 is b, the second light beam 116 is emitted to the wafer stack transfer unit 1301 at an angle of 180°-2b. It can be seen that the angle of 180°-2b is equal to the angle of 2a, that is, when the relationship between a and b is a complementary relationship, the second light beam 116 can form a horizontal laser at the same angle as the first light beam 115 and emit it to the wafer stack transfer unit 1301. The laser is reflected and refracted in the wafer stack transfer unit 1301. According to the laser reflection measurement principle, it can be inferred that the laser spacing x i With the measured thickness d i The relationship between them is as follows:

[0076]

[0077] Where i represents the number of layers measured (i = 1, 2, 3, 4, ...); θ i represents the incident angle of the light on the upper surface of the i-th layer; n i represents the refractive index of the i-th layer, where n 0 Specifically refers to the refractive index of air.

[0078] In a possible implementation, when the transfer carrier 131 deflects relative to the receiving substrate 132, the spot spacing originally formed on the imaging screen 140 reflecting the thickness of the transfer carrier 131 is x 1 , transfer carrier 131

[0079] After deflection, the spot spacing reflecting the thickness of the transfer carrier 131 formed on the imaging screen 140 is x 1 ', then the spot spacing x originally formed by the imaging screen 140 1 The distance x from the newly formed light spot on the imaging screen 140 1 'The difference is Δx, which satisfies the relationship:

[0080]

[0081] Wherein, Δx represents the spot spacing x originally formed by the imaging screen 140 1 The spot spacing x re-formed with the imaging screen 140 1 ', α represents the deflection angle of the transfer carrier 131, counterclockwise deflection is positive, clockwise deflection is negative; θ 1 represents the incident angle of the light on the upper surface of the transfer carrier 131; n 1 Indicates that the carrier board 131 is being transferred

[0082] The refractive index of the upper surface; n 2 represents the refractive index of the lower surface of the transfer carrier 131; d 1 Indicates the thickness of the transfer carrier 131. In a specific application, when the transfer carrier 131 in the wafer stack transfer unit 1301 is deflected, the optical path can be known according to the laser reflection principle:

[0083]

[0084] Wherein, Δx represents the spot spacing x originally formed by the imaging screen 140 1 The spot spacing x re-formed with the imaging screen 140 1 ', α represents the deflection angle of the transfer carrier 131, counterclockwise deflection is positive, clockwise deflection is negative; θ 1 represents the incident angle of the light on the upper surface of the transfer carrier 131; n 1 Indicates that the carrier board 131 is being transferred

[0085] The refractive index of the upper surface; n 2 represents the refractive index of the lower surface of the transfer carrier 131; d 1 Indicates transfer carrier 131 thick Spend.

[0086] In a possible implementation manner, when the transfer carrier 131 deflects relative to the receiving substrate 132, according to the spot spacing x originally formed by the imaging screen 140 1 The distance x from the newly formed light spot on the imaging screen 140 1'Difference Δx difference leveling, when Δx value is negative, rotate the leveling transfer carrier 131 clockwise; when Δx value is positive, rotate the leveling transfer carrier 131 counterclockwise. In specific applications, the reflected light beam of the laser after being reflected by the wafer stacking unit 1301 is transmitted on the optical imaging screen 140 to form a light spot, and each laser beam forms four light spots arranged up and down. During the measurement process, the displacement stage 130 is operated to move along the x direction at a uniform speed and consistent step length, and the camera 151 is combined to capture the light spot image. Among them, the filter lens 152 can use a bandpass filter with a central wavelength of 650nm and a bandwidth of only 14nm. After the camera 151 captures a sufficient amount of spot images, the data processing module 160 is used to process the images and data. The processing process mainly includes distortion correction, median filtering, threshold segmentation and center position extraction. The center position spacing between the laser spots can be used to calculate the changes in the wafer thickness and wafer gap between the transfer carrier 131 and the receiving substrate 132, as well as the deflection angle required for leveling between the transfer carrier 131 and the receiving substrate 132, that is, according to the spot spacing x originally formed on the imaging screen 140 1 The distance x from the newly formed light spot on the imaging screen 140 1 'Difference Δx is used for leveling. When the value of Δx is negative, the transfer carrier 131 is rotated clockwise for leveling; when the value of Δx is positive, the transfer carrier 131 is rotated counterclockwise for leveling.

[0087] The above-mentioned embodiments only express several implementation methods of the present invention, and the description thereof is relatively specific and detailed, but it cannot be understood as limiting the scope of the patent application. It should be pointed out that, for a person of ordinary skill in the art, several variations and improvements can be made without departing from the concept of the present invention, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be subject to the attached claims.

Claims

1. A laser measurement system for the gap between a chip transfer carrier and a substrate, characterized in that: include: Laser transmitter; A transmissive-reflective separation module, the transmissive-reflective separation module comprising a first lens, a second lens and a reflector, the first lens and the second lens are offset and perpendicular, a portion of the light beam emitted by the laser emitter is reflected by the first lens to generate a first light beam, and another portion of the light beam is generated after passing through the first lens to generate a second light beam, the second light beam is emitted to the reflector, and is reflected by the reflector to the second lens to reflect the second light beam, so that the first light beam and the second light beam are parallel; A displacement stage, wherein a transfer carrier and a receiving substrate are placed at intervals on the displacement stage, and the first light beam and the second light beam are respectively reflected, refracted and then reflected by the transfer carrier and reflected, refracted and then reflected by the receiving substrate; An imaging screen, wherein the first light beam and the second light beam are respectively reflected, refracted and then reflected by the transfer carrier and reflected, refracted and then reflected by the receiving substrate, thereby forming a plurality of light spots on the imaging screen, and the imaging screen is used to measure the distance of each light spot; Among them, when the transfer carrier is deflected or moved relative to the receiving substrate, the positions of multiple light spots formed on the imaging screen after the first light beam and the second light beam are reflected, refracted and then reflected by the transfer carrier and reflected, refracted and then reflected by the receiving substrate change, so that the imaging screen measures the distance value of each light spot after the change.

2. The chip transfer carrier and substrate gap laser measurement system according to claim 1, characterized in that: The reflector is formed with a first reflecting surface and a second reflecting surface which are vertically arranged. After the second light beam is incident on the first reflecting surface at a first angle, it is reflected to the second reflecting surface, and then is emitted from the second reflecting surface to the second lens at a second angle via the second reflecting surface, wherein the angle difference between the first angle and the second angle is 180°, so that the first light beam and the second light beam are spaced parallel lights emitted to the displacement stage.

3. The chip transfer carrier and substrate gap laser measurement system according to claim 2, characterized in that: When there is local deformation on the surface of the transfer carrier or the receiving substrate, the positions of the light spots formed by the first light beam on the imaging screen are different relative to those of the second light beam, so that the distance values ​​of the light spots measured by the imaging screen are different.

4. The laser measurement system for the gap between a chip transfer carrier and a substrate according to any one of claims 1 to 3, characterized in that: The laser transmitter comprises a laser component, a collimating lens, a Galilean beam reduction assembly and an aperture, wherein the aperture is arranged away from the laser component, the collimating lens is located between the laser component and the aperture, and the Galilean beam reduction assembly is located between the collimating lens and the aperture.

5. The laser measurement system for the gap between a chip transfer carrier and a substrate according to claim 4, characterized in that: The Galilean beam reduction assembly comprises a convex lens and a concave lens. The convex lens is arranged close to a side of the collimating lens, and the concave lens is arranged close to a side of the aperture, so as to reduce the beam of the laser emitted by the laser component.

6. The chip transfer carrier and substrate gap laser measurement system according to claim 1, characterized in that: The chip transfer carrier and substrate gap laser measurement system also includes an identification component and a data processing module. The identification component includes a camera and a filter lens located at the camera lens. The data processing module is electrically connected to the camera. The camera is used to observe the light spots of the transfer carrier and the receiving substrate and the light spot position information on the imaging screen. The data processing module is used to collect the light spots and light spot position information recorded by the camera.

7. A laser measurement method for the gap between a chip transfer carrier and a substrate, characterized in that: A laser measurement system for the gap between a chip transfer carrier and a substrate according to any one of claims 1 to 6, comprising the steps of: S1, placing the transfer carrier and the receiving substrate on the displacement stage in a wafer stacking unit structure; S2, turning on the laser emitter, and deflecting the first lens, the second lens, and the reflector in the transmission-reflection separation module at a suitable angle, so that the first light beam and the second light beam are respectively reflected on the surfaces of the first lens and the second lens and then projected onto the transfer carrier and the receiving substrate; S3, the first light beam and the second light beam are transmitted in the form of parallel light on the wafer stacking unit composed of the transfer carrier and the receiving substrate, and after being reflected and refracted in the wafer stacking unit, the first light beam and the second light beam respectively form four reflected light beams, and are projected on the imaging screen to form light spots; S4, photographing the light spots in the imaging screen in S3 with a camera to obtain an image containing the eight light spots; S5, performing image processing on the light spots in S4 based on the data processing module, extracting the center points and center coordinates of the eight light spots in the light spot image, and obtaining the nonlinear relationship between the light spots on the surfaces of the transfer carrier and the receiving substrate and the center points of the light spots in the imaging screen in S3 through calibration of the object points and the image points; S6, based on the laser reflection measurement, the lower surface of the receiving substrate is used as the reference surface, and based on the center coordinates of the imaging screen light spot in S3, the position coordinates of the light spot projected on the upper and lower surfaces of the transfer carrier and the upper surface of the receiving substrate are derived and calculated; S7, the displacement stage performs a uniform displacement in the horizontal direction, the camera continuously takes pictures of the light spot and the light spot image at a fixed frequency, the data processing module performs data analysis on the change of the center position of the light spot, calculates the thickness of the transfer carrier and the receiving substrate and the change of the gap between them, and derives the deflection angle required for leveling between the transfer carrier and the receiving substrate.

8. The laser measurement method for the gap between a chip transfer carrier and a substrate according to claim 7, characterized in that: The spot spacing formed by the first light beam or the second light beam on the imaging screen is x. i , let the thickness of the i-th interface be d i , satisfying the relationship: Where i represents the number of layers measured (i = 1, 2, 3, 4, ...); θ i represents the incident angle of the light on the upper surface of the i-th layer; n i represents the refractive index of the i-th layer, where n0 specifically refers to the refractive index of air.

9. The laser measurement method for the gap between the chip transfer carrier and the substrate according to claim 8, characterized in that: When the transfer carrier is deflected relative to the receiving substrate, the spot spacing originally formed on the imaging screen reflecting the thickness of the transfer carrier is x1, and after the transfer carrier is deflected, the spot spacing re-formed on the imaging screen reflecting the thickness of the transfer carrier is x1'. Then, the difference between the spot spacing x1 originally formed on the imaging screen and the spot spacing x1' re-formed on the imaging screen is Δx, which satisfies the relationship: In the formula, Δx represents the difference between the original spot spacing x1 formed by the imaging screen and the re-formed spot spacing x′1 by the imaging screen, α represents the deflection angle of the transfer carrier, counterclockwise deflection is positive, and clockwise deflection is negative; θ1 represents the incident angle of the light on the upper surface of the transfer carrier; n1 represents the refractive index on the upper surface of the transfer carrier; n2 represents the refractive index on the lower surface of the transfer carrier; d1 represents the thickness of the transfer carrier.

10. The laser measurement method for the gap between a chip transfer carrier and a substrate according to claim 9, characterized in that: When the transfer carrier is deflected relative to the receiving substrate, the transfer carrier is leveled according to the difference Δx between the original spot spacing x1 formed by the imaging screen and the spot spacing x′1 re-formed by the imaging screen. When the value of Δx is negative, the transfer carrier is leveled by rotating clockwise; when the value of Δx is positive, the transfer carrier is leveled by rotating counterclockwise.

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