Laser mass transfer system and method based on digital micromirror device and scanning galvanometer

Abstract

This application provides a laser mass transfer system and method based on a digital micromirror device and a scanning galvanometer, belonging to the field of microelectronics manufacturing and laser micro / nano processing technology. The laser mass transfer system includes: a laser source configured to emit deep ultraviolet laser; a digital micromirror device configured to spatially modulate the deep ultraviolet laser to obtain a multi-level diffracted beam carrying target pattern information; a filtering module configured to spatially filter the multi-level diffracted beam to obtain a first-level diffracted beam; a scanning galvanometer configured to perform optical path reversal on the first-level diffracted beam; and a focusing module configured to focus the first-level diffracted beam after optical path reversal to obtain a focused beam. The chip on the donor substrate is configured to debond from the donor substrate under the irradiation of the focused beam and transfer to a receiving substrate below the donor substrate to achieve laser mass transfer.

Description

Technical Field

[0001] This application relates to the fields of microelectronics manufacturing and laser micro / nano processing technology, and more specifically, to a laser mass transfer system and method based on digital micromirror devices and scanning galvanometers. Background Technology

[0002] Micro-LED display technology is widely regarded as the next generation of core display technology due to its high brightness, long lifespan and extremely low power consumption.

[0003] However, how to transfer tens of millions of micron-sized Micro-LED chips from the epitaxial growth substrate to the target driving backplane at high speed and without damage remains the core technical bottleneck restricting the large-scale mass production of this technology. Summary of the Invention

[0004] In view of this, this application provides a laser mass transfer system and method based on digital micromirror devices and scanning galvanometers.

[0005] One aspect of this application provides a laser mass transfer system based on a digital micromirror device and a scanning galvanometer, comprising: a laser source configured to emit deep ultraviolet laser; a digital micromirror device configured to spatially modulate the deep ultraviolet laser to obtain a multi-order diffracted beam carrying target pattern information; a filtering module configured to spatially filter the multi-order diffracted beam to suppress the zero-order optical component and higher-order stray optical components of the multi-order diffracted beam to obtain a first-order diffracted beam; a scanning galvanometer configured to deflect the optical path of the first-order diffracted beam to change the irradiation position of the first-order diffracted beam; and a focusing module configured to focus the first-order diffracted beam after optical path deflection to obtain a focused beam; wherein a chip on a donor substrate is configured to debond from the donor substrate under the irradiation of the focused beam and transfer to a receiving substrate below the donor substrate to realize laser mass transfer.

[0006] According to an embodiment of this application, the donor substrate is configured to move at a constant speed along a first direction at a first speed value; wherein, the scanning galvanometer includes a first reflecting mirror surface, and the laser mass transfer system further includes: a synchronous motion device configured to control the first reflecting mirror surface to rotate around the rotation axis of the first reflecting mirror surface in a first rotation mode, wherein, in the first rotation mode, the first reflecting mirror surface is configured to control the irradiation position of the first-order diffraction beam, so that the focused spot formed by the focused beam on the plane where the donor substrate is located moves along the first direction at the first speed value.

[0007] According to an embodiment of this application, the donor substrate is configured to move at a constant speed along a first direction at a first speed value; wherein, the scanning galvanometer includes a first reflective mirror, and the laser mass transfer system further includes: a jumping motion device configured to, upon receiving a position jumping command, control the first reflective mirror to continuously rotate around the rotation axis of the first reflective mirror in a second rotation mode for a jumping duration, wherein, in the second rotation mode, the first reflective mirror is configured to control the irradiation position of the first-order diffraction beam, so that the focused beam forming a focused spot on the plane where the donor substrate is located moves along a second direction at a preset jumping speed value, the second direction being the opposite direction to the first direction.

[0008] According to an embodiment of this application, the above-mentioned jumping motion device is configured to: determine a jump distance value based on the above-mentioned position jump command; add the above-mentioned jump speed value and the above-mentioned first speed value to determine a relative speed value; and divide the above-mentioned jump distance value and the above-mentioned relative speed value to determine the above-mentioned jump duration.

[0009] According to an embodiment of this application, the scanning galvanometer further includes a second reflecting mirror, the rotation axis of which is perpendicular to the rotation axis of the first reflecting mirror. The laser mass transfer system further includes a longitudinal motion device configured to control the second reflecting mirror to rotate around the rotation axis of the second reflecting mirror in a third rotation mode. In the third rotation mode, the second reflecting mirror is configured to control the irradiation position of the first-order diffraction beam, so that the focused beam forming a focused spot on the plane where the donor substrate is located reciprocates along the third direction, wherein the third direction is a direction perpendicular to the first direction.

[0010] According to an embodiment of this application, the laser mass transfer system further includes a micromirror control module, which is configured to: acquire a defect distribution map, wherein the defect distribution map is used to characterize the distribution of defective chips on the donor substrate; determine a binarized target matrix based on the defect distribution map, wherein each element value of the binarized target matrix is ​​used to characterize whether a defective chip exists at the corresponding point on the donor substrate; generate an amplitude-type binary computational hologram based on the binarized target matrix; and control the deflection state of each micromirror unit in the digital micromirror device based on the color state of each pixel of the amplitude-type binary computational hologram.

[0011] According to an embodiment of this application, the filtering module includes: a first Fourier lens, wherein the digital micromirror device is located at the front focal plane of the first Fourier lens, and the first Fourier lens is configured to perform spatial Fourier transform processing on the multi-order diffracted beam to obtain a first beam; a spatial filter, wherein the spatial filter is located at the rear focal plane of the first Fourier lens, and the spatial filter is configured to absorb the zero-order light component and higher-order stray light component of the first beam to obtain a second beam; and a second Fourier lens, wherein the spatial filter is located at the front focal plane of the second Fourier lens, and the second Fourier lens is configured to perform inverse Fourier transform processing on the second beam to obtain a first-order diffracted beam.

[0012] According to an embodiment of this application, the spatial filter is a stray light elimination aperture with a central through-hole, and the stray light elimination aperture is configured to absorb the zero-order light component and higher-order stray light component in the first beam that deviates from the optical axis of the stray light elimination aperture.

[0013] According to an embodiment of this application, the focusing module is a telecentric flat-field lens, which is configured to perform flat-field focusing on the first-order diffracted beam.

[0014] Another aspect of this application provides a laser mass transfer method based on a digital micromirror device and a scanning galvanometer, applied to the laser mass transfer system described above, comprising: emitting a deep ultraviolet laser; spatially modulating the deep ultraviolet laser to obtain a multi-order diffracted beam; spatially filtering the multi-order diffracted beam to suppress the zero-order optical component and higher-order stray optical components of the multi-order diffracted beam to obtain a first-order diffracted beam; reversing the optical path of the first-order diffracted beam to change the irradiation position of the first-order diffracted beam; focusing the first-order diffracted beam after optical path reversal to obtain a focused beam; wherein, the chip on the donor substrate is configured to debond from the donor substrate under the irradiation of the focused beam and transfer to a receiving substrate below the donor substrate to realize laser mass transfer.

[0015] According to embodiments of this application, by introducing a digital micromirror device (DMD), holographic diffraction patterns can be generated based on the dynamic programmable characteristics of the DMD. The period and pattern of the beam splitter array can be adjusted in real time by software, providing perfect versatility for chip arrays of different specifications and spacings. This eliminates the high customization costs and easily damaged replacement costs of traditional photomasks. Furthermore, a filtering module is introduced to use a frequency domain physical blocking mechanism to remove the zero-order high-energy direct light and stray background noise generated by the DMD, allowing only the first-order effective diffraction light to enter the subsequent optical path. This eliminates the risk of thermal damage to non-target chips from the physical source. In addition, a scanning galvanometer is used to refract the first-order diffraction beam, and a focusing module is used to focus the first-order diffraction beam, achieving large-range scanning control of the focused beam and greatly improving the overall transfer rate of laser mass transfer. Attached Figure Description

[0016] The above and other objects, features and advantages of this application will become clearer from the following description of embodiments of this application with reference to the accompanying drawings.

[0017] Figure 1 A schematic diagram of a laser mass transfer system based on a digital micromirror device and a scanning galvanometer according to an embodiment of this application is shown.

[0018] Figure 2 A schematic diagram of an amplitude-type binary computational hologram according to an embodiment of this application is shown.

[0019] Figure 3 A schematic diagram of a multifocal array of a first-order diffracted beam focused by a telecentric flat-field lens according to an embodiment of this application is shown.

[0020] Figure 4 A schematic diagram of the scanning path of the focused beam on the plane of the donor substrate according to an embodiment of this application is shown.

[0021] Figure 5 A schematic diagram of the actual scanning path of the focused spot according to an embodiment of this application is shown.

[0022] Figure 6 A schematic diagram showing the moving speed of the focused spot and the donor substrate according to an embodiment of this application is provided.

[0023] Figure 7 A flowchart of a laser mass transfer method based on a digital micromirror device and a scanning galvanometer according to an embodiment of this application is shown. Detailed Implementation

[0024] The embodiments of this application will now be described with reference to the accompanying drawings. However, it should be understood that these descriptions are exemplary only and are not intended to limit the scope of this application. In the following detailed description, numerous specific details are set forth to provide a thorough understanding of the embodiments of this application for ease of explanation. However, it will be apparent that one or more embodiments may be implemented without these specific details. Furthermore, descriptions of well-known structures and technologies are omitted in the following description to avoid unnecessarily obscuring the concepts of this application.

[0025] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the scope of this application. The terms "comprising," "including," etc., as used herein indicate the presence of the above-described features, steps, operations, and / or components, but do not exclude the presence or addition of one or more other features, steps, operations, or components.

[0026] All terms used herein (including technical and scientific terms) have the meanings commonly understood by those skilled in the art, unless otherwise defined. It should be noted that the terms used herein are to be interpreted in a manner consistent with the context of this specification, and not in an idealized or overly rigid way.

[0027] When using expressions such as "at least one of A, B and C", they should generally be interpreted in accordance with the meaning that is commonly understood by those skilled in the art (e.g., "a system having at least one of A, B and C" should include, but is not limited to, a system having A alone, a system having B alone, a system having C alone, a system having A and B, a system having A and C, a system having B and C, and / or a system having A, B and C, etc.).

[0028] Among various mass transfer solutions, ultraviolet short-pulse laser-assisted transfer technology has become a highly promising technical route due to its advantages such as non-contact processing and extremely short processing time. However, existing laser transfer optical path designs face a series of mutually restrictive technical barriers when moving towards industrial mass production.

[0029] First, traditional single-beam laser scanning processing has a physical limit to throughput. Currently, conventional equipment mostly uses a single beam combined with a two-dimensional scanning galvanometer for point-to-point serial processing. When dealing with chip arrays of tens of millions in scale, the transfer time for a single wafer is too long, and the production throughput is limited by the laser repetition rate and mechanical deflection limits, which cannot meet the requirements of mass production cycle time.

[0030] Second, static mask projection technology lacks dynamic response capability for defect removal. To improve efficiency, existing technologies often use physical static masks to shape laser light into arrays for parallel transfer. However, epitaxial wafer growth inevitably results in defective targets, and static masks cannot distinguish between good and defective products, leading to defective chips being transferred simultaneously, which greatly increases repair costs and reduces yield.

[0031] Third, the high energy density required for laser transfer and the damage limit of the Digital Micromirror Device (DMD) jointly constrain the expansion of the processing field of view. Introducing a DMD is an inevitable trend to achieve dynamic selective transfer. However, in parallel array processing, the energy density of the laser reaching the interface must be higher than the stripping threshold. If an attempt is made to simply expand the field of view of the optical system to increase the processing area per pass, the laser energy will be severely diluted; if the total laser power is forcibly increased to compensate for the energy deficiency, it will be limited by the material properties of the DMD itself and the laser-induced damage threshold, leading to the instantaneous burnout of the micromirror array. Therefore, the system cannot expand the processing field of view per pass indefinitely while ensuring the high energy density required for transfer.

[0032] Fourth, continuous transfer methods using uniform motion of the mask or donor substrate pose a "tailing" risk at high speeds. Given the limited field of view in a single projection, existing technologies often employ continuous uniform movement of the donor substrate to stitch together large-area transfers. However, when pursuing high output and significantly increasing mechanical speed, especially during the extremely short duration of a continuous laser pulse train, microscopic relative displacement occurs between the laser beam and the donor substrate. This can lead to severe laser energy "tailing" or scratches on the target chip's surface, disrupting the uniformity of force on the chip and completely destroying the alignment accuracy of mass transfers.

[0033] Fifth, there is the problem of secondary diffraction damage directly introduced by the dynamic modulation of the DMD. The DMD is essentially a two-dimensional blazed grating composed of a micrometer-scale array of mirrors. When irradiated with highly coherent ultraviolet laser, it inevitably generates extremely concentrated zero-order undiffracted light and secondary diffracted light. In a conventional optical path, this high-energy direct-path light is synchronously projected onto the wafer along with the target spot, causing accidental stripping or severe thermal damage to non-target chip areas, compromising transfer security.

[0034] Sixth, large field-of-view scanning leads to severe field curvature distortion and the risk of non-perpendicular incidence. When attempting to expand the limited array spot coverage by using galvanometer deflection, ordinary focusing lenses will produce significant field curvature distortion at the edge of the field of view, causing the spot to defocus; at the same time, the edge rays are incident on the substrate at an inclined angle, causing the chip to be subjected to lateral shear force at the moment of stimulated desorption, resulting in tilting or landing point deviation, making it difficult to ensure the consistency of the entire field of view.

[0035] In summary, there is an urgent need for a highly efficient parallel processing system that can completely break through the limitations, take into account ultra-high throughput and dynamic flexibility, and has no optical distortion, no trailing, and no stray light pollution.

[0036] Figure 1 A schematic diagram of a laser mass transfer system based on a digital micromirror device and a scanning galvanometer according to an embodiment of this application is shown.

[0037] like Figure 1 As shown, the laser mass transfer system based on digital micromirror devices and scanning galvanometers includes: a laser source 110, a digital micromirror device 120, a filtering module 130, a scanning galvanometer 140, and a focusing module 150.

[0038] The laser source 110 is configured to emit deep ultraviolet laser.

[0039] The laser source 110 can be implemented based on an ultrafast laser source module to provide deep ultraviolet laser with extremely short pulse widths. Simultaneously, to address the potential energy degradation at the extreme edge of the field of view, a beam-expanding and collimating optical path can be set between the laser source 110 and the digital micromirror device 120 to perform extremely uniform flat-top pre-shaping of the beam, ensuring that the large-area beam covering the working area of ​​the digital micromirror device 120 has an absolutely uniform energy distribution.

[0040] The digital micromirror device 120 is configured to spatially modulate the amplitude of a deep ultraviolet laser to obtain a multi-level diffracted beam carrying target pattern information.

[0041] In the embodiments of this application, a binary target matrix can be generated based on the defect distribution map provided by the Automatic Optical Inspection (AOI) received by the host computer. Based on the binary target matrix, a corresponding amplitude-type binary computational hologram can be generated by holographic encoding algorithm. The amplitude-type binary computational hologram is then loaded into the digital micromirror device 120 to realize the spatial amplitude modulation of the incident deep ultraviolet laser by the digital micromirror device 120, and to cut out a high-energy-density local array beam, i.e., a multi-level diffraction beam, in real time, corresponding to the arrangement of good chips.

[0042] The filtering module 130 is configured to perform spatial filtering on the multi-order diffraction beam to suppress the zero-order light component and higher-order stray light component of the multi-order diffraction beam, so as to obtain the first-order diffraction beam.

[0043] The filtering module 130 may include two sets of conjugate Fourier lenses and a spatial filter, used to relay the multi-order diffraction beam generated by the digital micromirror device 120 to the scanning galvanometer, and to completely cut off harmful zero-order light and high-order diffraction stray light in the middle.

[0044] The scanning galvanometer 140 is configured to deflect the optical path of the first-order diffracted beam to change the illumination position of the first-order diffracted beam.

[0045] The focusing module 150 is configured to focus the first-order diffracted beam after optical path deflection to obtain a focused beam. The chip on the donor substrate is configured to debond with the donor substrate under the illumination of the focused beam and transfer to the receiving substrate below the donor substrate to achieve mass laser transfer. The first-order diffracted beam, after being filtered by the filtering module 130, then enters the scanning galvanometer 140. The scanning galvanometer 140 can achieve a large-scale movement of the first-order diffracted beam by utilizing the deflection of a micro mechanical mirror. Since the first-order diffracted beam forms a focused beam after passing through the focusing module, a large-scale high-speed movement of the focused spot formed on the surface of the donor substrate is achieved. At the same time, both the donor substrate and the receiving substrate can be placed on a global uniform speed direct drive support platform. The global uniform speed direct drive support platform is located at the bottom of the optical path and is responsible for supporting the continuous, stop-and-go constant speed translation of the donor substrate and the receiving substrate in the X-axis direction.

[0046] Through the embodiments of this application, by introducing a digital micromirror device (DMD), holographic diffraction patterns can be generated based on the dynamic programmable characteristics of the DMD. The period and pattern of the beam splitter array can be adjusted in real time by software, providing perfect versatility for chip arrays of different specifications and spacings. This eliminates the high customization costs and easily damaged replacement costs of traditional photomasks. Furthermore, a filtering module is introduced to use a frequency domain physical blocking mechanism to remove the zero-order high-energy direct light and stray background noise generated by the DMD, allowing only the first-order effective diffraction light to enter the subsequent optical path. This eliminates the risk of thermal damage to non-target chips from the physical source. In addition, a scanning galvanometer is used to refract the first-order diffraction beam, and a focusing module is used to focus the first-order diffraction beam, achieving large-range scanning control of the focused beam and greatly improving the overall transfer rate of laser mass transfer.

[0047] In one specific embodiment of this application, a micromirror control module can be introduced to control the digital micromirror device (DMM) to achieve spatial amplitude modulation of deep ultraviolet laser light. The specific control flow of the micromirror control module is as follows: A defect distribution map is obtained, which characterizes the distribution of defective chips on the donor substrate; a binarized target matrix is ​​determined based on the defect distribution map, where each element value of the binarized target matrix characterizes whether a defective chip exists at the corresponding point on the donor substrate; an amplitude-type binary computational hologram is generated based on the binarized target matrix, where the color state of each pixel in the amplitude-type binary computational hologram corresponds to each element value of the binarized target matrix; and the deflection state of each corresponding micromirror unit in the digital micromirror device is controlled based on the color state of each pixel in the amplitude-type binary computational hologram.

[0048] In the laser mass transfer system of this application embodiment, the digital micromirror device (DMM) operates as a dynamically programmable holographic diffraction device. During mass transfer, the system is no longer limited to a quartz mask of fixed size and pattern. For randomly distributed defects on the wafer, the control system calculates and generates corresponding binary computational holograms in real time based on the coordinate distribution of the good chips. When the computational hologram is loaded onto the DMM, each micromirror unit collaboratively forms a specific spatial amplitude distribution, ensuring that after diffraction and subsequent filtering, the incident light forms a high-energy-density focused spot only in the area aligned with the good chips, while the defective areas receive no effective laser irradiation. Because the DMM has a refresh rate of tens of thousands of hertz, the system can instantaneously switch between binary computational holograms of different regions during continuous scanning of the scanning galvanometer, achieving 100% yield and absolute selective transfer with extremely high throughput.

[0049] Figure 2 A schematic diagram of an amplitude-type binary computational hologram according to an embodiment of this application is shown.

[0050] Figure 2 The amplitude-type binary computational hologram shown is generated based on the iterative optimization of the Gerchberg-Saxton (GS) algorithm and using Li's binary encoding. The reflectivity of this amplitude-type binary computational hologram has only two states: 0 (black) and 1 (white). Therefore, the brightness distribution in the pattern directly corresponds to the "on" or "off" state of the micromirror unit on the digital micromirror device.

[0051] If digital micromirror devices are directly introduced into a laser mass transfer system, the pixel grid on the surface of the digital micromirror device will cause strong optical diffraction. The untreated diffracted light field contains extremely high-energy and uncontrolled zero-order light (DC component), which will directly destroy the chip at the center of the transfer array. Therefore, a filtering module is needed to filter the patterned beam of the digital micromirror device.

[0052] In one specific embodiment of this application, the filtering module can be configured as follows: including a first Fourier lens, a spatial filter, and a second Fourier lens, to filter multi-order diffracted beams. A digital micromirror device is located at the front focal plane of the first Fourier lens, and the spatial filter is located at the rear focal plane of the first Fourier lens and the front focal plane of the second Fourier lens. The first Fourier lens is configured to perform a spatial Fourier transform on the multi-order diffracted beam to obtain a first beam; the spatial filter is configured to absorb the zero-order light component and higher-order stray light components of the first beam to obtain a second beam; the second Fourier lens is configured to perform an inverse Fourier transform on the second beam to obtain a first-order diffracted beam. Furthermore, the spatial filter can be a stray light removal aperture with a central through-hole, configured to absorb the zero-order light component and higher-order stray light components of the first beam that deviate from the optical axis of the stray light removal aperture.

[0053] The digital micromirror device (DMM) is located at the front focal plane of the first Fourier lens. By adjusting the bias angle of the deep ultraviolet laser incident on the DMM, it can be ensured that the first-order diffraction component of the multi-order diffraction beam output by the DMM converges at the center of the de-scratching aperture. After passing through the first Fourier lens, the multi-order diffraction beam undergoes a spatial Fourier transform on the back focal plane (i.e., the spectral plane) of the first Fourier lens. At this time, the first-order diffraction component carrying the useful array pattern is strongly focused at the exact center of the optical axis, while the high-energy zero-order DC component deviates from the optical axis distribution. By precisely setting a de-scratching aperture on this spectral plane as a spatial filter, this de-scratching aperture has only a central aperture, allowing the first-order diffraction component to pass through the central aperture while the second-order diffraction components and the zero-order light component are absorbed. The clean beam passing through the stray light elimination aperture then enters the second Fourier lens. After inverse Fourier transform, a high-contrast array light field image without zero-order interference is perfectly reconstructed at the back focal plane of the second Fourier lens (i.e., at the entrance pupil of the scanning galvanometer), which is the first-order diffracted beam.

[0054] By utilizing a conjugate Fourier optical system and a precision spatial filter, the diffraction light field of digital micromirror devices can be physically blocked and cleaned in the spatial frequency domain. By safely isolating and absorbing destructive zero-order high-energy stray light and secondary diffraction light, only first-order effective diffraction light is allowed to enter the subsequent optical path, eliminating the risk of thermal damage to non-target chips from the physical source and ensuring the absolute safety of the transfer process.

[0055] To avoid problems such as insufficient chip stripping energy, tilting, and flipping caused by image plane curvature or tilted incident light at the scanning edge, the focusing module in the laser mass transfer system can be equipped with a telecentric flat-field lens, which is configured to perform flat-field focusing on the first-order diffracted beam.

[0056] In the embodiments of this application, the telecentric plan lens can be an F-θ image-side telecentric plan lens specifically optimized for ultraviolet lasers, which has three major optical characteristics: extremely low field curvature, linear displacement, and absolute telecentric incidence.

[0057] Extremely low field curvature: Forcefully flatten the spherical focal plane into an absolute plane to ensure that the chip at the center and edge receives a flat-top light spot of completely equal size and constant energy density.

[0058] Linear displacement: The optical distortion is specially designed to make the scanning image height linearly related to the scanning galvanometer deflection angle, which simplifies the coordinate interpolation algorithm in the high-speed scanning process.

[0059] Absolute telecentric incidence: Through complex pupil correction, it is ensured that the principal rays of all array beams emitted from the lens are strictly parallel to the optical axis and perpendicular to the wafer surface, whether at the center or edge of the field of view (telecentricity error less than 1 degree). This characteristic ensures that the expansion reaction force generated by the vaporization of the sacrificial layer is absolutely vertically downward, guaranteeing that the Micro-LED chip lands smoothly and accurately on the receiving substrate.

[0060] In summary, by using a telecentric flat-field lens coupled with a high-speed scanning galvanometer and forcibly correcting the optical path through telecentric optical design to counteract the field curvature effect caused by large-angle deflection, it can be ensured that each array laser beam penetrates the donor substrate in a strictly absolute vertical state throughout the entire working area. This eliminates chip positioning errors or even flipping caused by lateral thrust, ensuring that the Micro-LED chip lands stably and vertically onto the receiving substrate without tilting.

[0061] Figure 3 A schematic diagram of a multifocal array of a first-order diffracted beam focused by a telecentric flat-field lens according to an embodiment of this application is shown.

[0062] like Figure 3 As shown, the figure includes a 10×10 two-dimensional regular dot matrix with a total of 100 focused light spots arranged in a uniform row and column grid. The vast majority of the light spots are uniform circular bright spots with basically the same brightness and size, indicating that the energy distribution of most focal points is uniform, and each array laser beam is arranged in a strict positional relationship.

[0063] In embodiments of this application, the donor substrate is configured to move at a constant speed along a first direction. To ensure proper alignment between the focused laser spot and the moving donor substrate for more precise laser mass transfer, the laser mass transfer system of this application may further include a synchronous motion device and a jumping motion device.

[0064] The synchronous motion device is configured to control the first reflecting mirror to rotate around the rotation axis of the first reflecting mirror in a first rotation mode. In the first rotation mode, the first reflecting mirror is configured to control the irradiation position of the first-order diffraction beam so that the focused spot formed by the focused beam on the plane where the donor substrate is located moves along the first direction at a first speed value.

[0065] When the illumination position of the first-order diffracted beam in the ground coordinate system remains unchanged, the illumination position of the focused beam formed based on the first-order diffracted beam in the ground coordinate system also remains fixed. At this time, since the donor substrate maintains a global high-speed uniform motion in the ground coordinate system, the focused spot formed by the focused beam will produce a high-speed tailing effect on the donor substrate. That is, the donor substrate as a whole performs a global translational motion relative to the focused beam at a constant speed. The irradiation area of ​​the substrate by the focused beam continuously extends and overlaps with the movement of the donor substrate. The originally clear beam pattern cannot be instantly fixed at the same position on the substrate, and finally a beam tail phenomenon extending and elongating along the direction of substrate movement is formed in the light-receiving area of ​​the donor substrate. Therefore, this application introduces "flying scan" control logic into the laser mass transfer system. While the donor substrate maintains a global high-speed uniform motion, the illumination position of the first-order diffracted beam is controlled by a scanning galvanometer, so that the focused spot and the moving donor substrate remain relatively stationary, eliminating the tailing effect and ensuring nanometer-level alignment accuracy under high production capacity.

[0066] The jumping motion device is configured to, upon receiving a position jump command, control a first reflecting mirror to continuously rotate around its rotation axis in a second rotation mode for a jump duration. In the second rotation mode, the first reflecting mirror is configured to control the irradiation position of the first-order diffraction beam, causing the focused beam to form a focused spot on the plane of the donor substrate, which moves along a second direction at a preset jump speed value. The second direction is opposite to the first direction. The jump duration can be obtained by: determining a jump distance value based on the position jump command; adding the jump speed value and the first speed value to determine the relative speed value; and dividing the jump distance value by the relative speed value to determine the jump duration.

[0067] After completing the mass laser transfer in a certain area, the jumping motion device controls the irradiation position of the first-order diffraction beam, so that the focused spot formed by the focused beam on the plane where the donor substrate is located jumps along the second direction. That is, when the processing of the current column is completed and the processing position of the next column is jumped, the algorithm pre-extracts the flyback stabilization time and calculates the displacement of the donor substrate along the first direction during this period. At the same time, the scanning galvanometer directly corrects the target coordinates to the "predicted future spatial position", realizing seamless connection across columns.

[0068] In the embodiments of this application, in order to strictly lock the movement speed of the donor substrate to the opto-mechatronic rhythm, a [system / mechanical framework] can be established. The equilibrium equations (where This is the jump distance value. (This refers to the total time consumed by the scanning time and jump time of the focused spot in a single column). By setting the movement speed of the donor substrate as described above, the scanning galvanometer's idle waiting or missed scans are eliminated, pushing the mechanical throughput to its theoretical limit while ensuring accuracy.

[0069] In parallel array processing, the energy density of the laser reaching the interface must be higher than the stripping threshold. Attempting to increase the processing area per pass simply by expanding the field of view of the optical system would severely dilute the laser energy. Forcibly increasing the total laser power to compensate for the energy deficiency would be limited by the material properties of the digital micromirror device itself and the laser-induced damage threshold, leading to the instantaneous burnout of the micromirror array. To overcome the energy density constraint and balance high energy threshold with large-area, lossless, high-speed transfer, a longitudinal motion device can be introduced. This device controls the irradiation position of the first-order diffraction beam, causing the focused spot formed by the focused beam on the plane of the donor substrate to reciprocate along a third direction, thus expanding the coverage area of ​​the single macroscopic processing zone. In other words, the laser mass transfer system of this embodiment only needs to maintain a suitable initial projection field of view initially, while the large-area coverage of the processing area is accomplished by the downstream scanning galvanometer reciprocating along a third direction.

[0070] The specific configuration is as follows: The scanning galvanometer includes a second reflecting mirror, and the rotation axis of the second reflecting mirror is perpendicular to the rotation axis of the first reflecting mirror. The longitudinal motion device is configured to control the second reflecting mirror to rotate around its rotation axis in a third rotation mode. In the third rotation mode, the second reflecting mirror is configured to control the irradiation position of the first-order diffraction beam, so that the focused beam forming a focused spot on the plane where the donor substrate is located reciprocates along a third direction, which is perpendicular to the first direction.

[0071] By employing a synergistic strategy of ensuring high energy density through a small projection field of view and expanding the equivalent processing area through high-speed two-dimensional deflection of the scanning galvanometer, the overall transfer rate can be greatly improved while effectively protecting the digital micromirror device from being burned out by high power.

[0072] By using a microlens array to perform high-precision pre-light field homogenization on the incident deep ultraviolet laser, and then using high-frequency dynamic binary modulation, the laser mass transfer system is endowed with the ability to selectively remove 100% pure good chips with defects, thus eliminating the cost of preparing and replacing static masks from the source.

[0073] Figure 4 A schematic diagram of the scanning path of the focused beam on the plane of the donor substrate according to an embodiment of this application is shown.

[0074] like Figure 4 As shown, the donor substrate is V stageThe focused beam moves along the first direction at a speed of V, and the focused spot on the plane where the donor substrate is located reciprocates along the third direction at a speed of V. laser The irradiation position moves from the lower right to the upper right, then moves a distance along the second direction, and then moves from top to bottom for one column length, repeating this process until the irradiation position reaches the lower left of the donor substrate.

[0075] Figure 5 A schematic diagram of the actual scanning path of the focused spot according to an embodiment of this application is shown.

[0076] like Figure 5 As shown, with the ground as the reference frame, the focused spot begins at the lower left corner extreme position with a V-shaped trajectory. stage The speed follows the donor substrate scanning to the right along the first direction. After processing one spot array, it needs to scan along the third direction at a speed of V. laser The focusing spot moves upwards at a speed that switches the switching area, repeating this process. The focusing spot moves in a stepped pattern from the lower left to the upper right. Then, under the control of the jumping motion device, the focusing spot rapidly jumps from its upper right extreme position to its upper left extreme position, thus completing half a processing cycle. Next, the focusing spot moves at a V-shaped speed... stage The speed follows the donor substrate to the right along the first direction, scanning at a speed of V. After processing one spot array, it needs to scan along the third direction. laser The focusing spot moves downwards at a speed that switches areas, repeating this process. The focused spot moves in a stepped pattern from the upper left to the lower right, completing half a processing cycle. Then, under the control of the jumping motion device, the focused spot rapidly jumps from its lower right extreme position to its initial lower left extreme position, thus completing the entire processing cycle. Overall, the actual scanning path of the focused spot is a "bidirectional Z-shaped loop."

[0077] Figure 6 A schematic diagram showing the moving speed of the focused spot and the donor substrate according to an embodiment of this application is provided.

[0078] like Figure 6 As shown, Figure 6 (a) represents the velocity of the focused spot along the first direction. Figure 6 (b) represents the velocity of the focused spot along a third direction. Figure 6 (c) represents the velocity of the donor substrate along the first direction. Since the first and second directions are opposite, the jump velocity of the focused spot in the second direction is 400 mm / s. The focused spot and the donor substrate have the same velocity along the first direction, both 10 mm / s, to ensure that the laser beam remains relatively stationary with the moving donor substrate, eliminating the trailing effect, and as... Figure 6 As shown in (a), the focused spot only moves along the first direction during the time it interacts with the donor substrate. Figure 6As shown in (b), the scanning speed of the focused spot in the third direction is 200 mm / s.

[0079] Figure 7 A flowchart of a laser mass transfer method based on a digital micromirror device and a scanning galvanometer according to an embodiment of this application is shown.

[0080] like Figure 7 As shown, the laser mass transfer method based on digital micromirror devices and scanning galvanometers includes operations S710~S750.

[0081] When operating the S710, it emits a deep ultraviolet laser.

[0082] By operating the S720, spatial amplitude modulation of the deep ultraviolet laser is performed to obtain a multi-level diffraction beam.

[0083] When operating the S730, spatial filtering is performed on the multi-order diffracted beam to suppress the zero-order light component and higher-order stray light component of the multi-order diffracted beam, thus obtaining the first-order diffracted beam.

[0084] In operation S740, the optical path of the first-order diffracted beam is deflected to change the illumination position of the first-order diffracted beam.

[0085] When operating the S750, the first-order diffracted beam after optical path refraction is focused to obtain a focused beam.

[0086] The chip on the donor substrate is configured to debond from the donor substrate under the illumination of a focused beam and transfer to a receiving substrate below the donor substrate to achieve mass laser transfer.

[0087] In one specific embodiment of this application, laser mass transfer based on digital micromirror devices and scanning galvanometers can be achieved through the following steps.

[0088] First, wafer loading, parameter calculation, and feedforward control calibration are performed. A transparent sapphire donor wafer with a high-density Micro-LED array is placed on a high-precision direct-drive platform, with the sapphire substrate facing upwards to receive the laser. The epitaxial wafer is bonded to the target receiving substrate with a receiving adhesion layer at micron-level spacing. The control system imports a "two-dimensional topological defect distribution map of defective grains" provided by an external AOI.

[0089] The main control system solves the dynamic matching equation for the donor substrate velocity based on the required transfer pitch. The calculated limiting dynamic equilibrium velocity V is then... stage The control commands are written into the driver platform, enabling it to start and maintain continuous, constant-speed translation in the first direction without any stops. Simultaneously, the feedforward kinematic compensation matrix and the bidirectional hysteresis calibration parameters for odd and even rows are preloaded into the underlying FPGA control card.

[0090] Pre-amplitude homogenization and high-energy-density spatial dynamic modulation. The laser source is activated to emit deep ultraviolet laser light. The deep ultraviolet laser first undergoes high-precision pre-amplitude homogenization and shaping through a lens array at the front end of the optical path, transforming the original Gaussian beam into a collimated beam with an absolutely flat-top energy distribution, which then illuminates the working surface of the digital micromirror device (DMM). To balance the stripping threshold and device lifetime, the initial projection field of view at the DMM is artificially limited to the maximum spatial size that can reach the chip's energy release threshold, while ensuring that the total power borne by the target surface of the DMM is strictly within the laser-induced damage threshold of its material. Based on the amplitude-type binary computational hologram calculated in real time by the control system, the DMM rapidly adjusts the deflection state of its surface micromirror array. Specifically, each micromirror unit independently flips to +12 degrees (On state) or -12 degrees (Off state) based on the encoded data of the hologram, thereby forming a dynamic binary spatial amplitude-type diffraction grating on the working surface of the DMM. The incident deep ultraviolet laser is modulated by the spatial amplitude of the dynamic diffraction grating and diffracts. In the spatial domain, it interferes and reconstructs a three-dimensional diffraction light field that carries only the high-quality chip arrangement position information, i.e., a multi-level diffraction beam.

[0091] Fourier spectral spatial filtering and zero-order stray light purification. A multi-order diffracted beam modulated by a digital micromirror device enters the filtering module. After passing through the first Fourier lens, the multi-order diffracted beam undergoes a spatial Fourier transform on its back focal plane (spectral plane). At this point, the first-order diffracted light component carrying the target pattern information is focused at the exact center of the optical axis, while the high-energy and uncontrolled zero-order DC undiffracted light component deviates from the optical axis. A custom spatial filter placed on this spectral plane has only a tiny aperture at its exact center, intercepting and completely absorbing the critically off-center zero-order light component and the secondary diffracted light component. The pure first-order diffracted light component then passes through the central aperture into the second Fourier lens. After undergoing an inverse Fourier transform by the second Fourier lens, a high-contrast, zero-noise pure matrix light field image—the first-order diffracted beam—is perfectly reconstructed at the entrance pupil of the scanning galvanometer.

[0092] The substrate undergoes continuous one-dimensional motion and dynamic tracking in the same direction as the scanning galvanometer. A first-order diffracted beam enters the scanning galvanometer. During the processing cycle, the underlying mechanical platform carries the donor substrate forward at a constant speed along the first direction. When the system releases the focused beam to peel off a specific area, the control card drives the servo motor of the first reflective mirror to perform microsecond-level unidirectional reverse tracking. During the microsecond-level duration of the focused beam's action, the scanning galvanometer guides the first-order diffracted beam to change its irradiation position, ensuring that the speed and direction of the focused spot's deflection are strictly equal to the speed and direction of the donor substrate's movement. This dynamic tracking mechanism maintains an absolute "relative velocity of zero" for the focused spot on the plane of the donor substrate during the light-emitting process, completely eliminating high-speed trailing and energy smearing caused by continuous mechanical motion at a physical level, ensuring that the focused beam's energy is perfectly focused on the target center.

[0093] Bidirectional Z-shaped cyclic processing. In the embodiments of this application, the scanning galvanometer's control of the X-axis corresponds to the first direction, and the scanning galvanometer's control of the Y-axis corresponds to the third direction. Within a column of micro-processing areas, the scanning galvanometer does not perform continuous scanning on the Y-axis, but instead adopts a stepped, intermittent jump: i.e., a cycle of "locking the Y-axis, releasing the laser (X-axis follow-up tracking) -> turning off the laser -> rapid jump and row change on the Y-axis". When the focused spot is gradually processed from the initial position to the current field-of-view boundary limit on the Y-axis, cross-column reversal control is executed. The feedforward kinematic compensation algorithm is used to pre-extract the flyback time required for the scanning galvanometer's large-angle jump and the mechanical stability of the lens. The algorithm automatically calculates the mechanical displacement within this flyback time based on the current velocity of the donor substrate, and performs advance correction on the next X-axis target coordinate of the scanning galvanometer, calculates the predicted future spatial position equation, and the scanning galvanometer directly jumps to this future position to dock with the donor substrate, achieving seamless column change and splicing. Subsequently, a "top-down" reverse scanning cycle is initiated. To address the micro-grid misalignment caused by electromagnetic and mechanical hysteresis during the alternating upward and downward scanning of the scanning galvanometer, the control card injects bidirectional hysteresis compensation parameters online, applying sub-micron-level reverse dynamic adjustments to the row coordinates during the downward scanning cycle. During this bidirectional Z-shaped flying scan, the first-order diffracted beam undergoes final focusing correction through a telecentric flat-field lens, ensuring that regardless of whether the focused spot is at the center of the field of view or the physical limit edge of the Y-axis, each sub-beam of the multi-beam array penetrates the sapphire interface with an angle strictly perpendicular to the donor substrate and an absolutely constant energy density. When the focused spot reaches the edge of the donor substrate, the Z-shaped flying scan stops, a donor substrate repositioning operation is performed, and the process is re-aligned with the receiving substrate below before initiating a new transfer process.

[0094] Those skilled in the art will understand that the features described in the various embodiments of this application can be combined and / or combined in various ways, even if such combinations or combinations are not explicitly described in this application. In particular, the features described in the various embodiments of this application can be combined and / or combined in various ways without departing from the spirit and teachings of this application. All such combinations and / or combinations fall within the scope of this application.

[0095] The embodiments of this application have been described above. However, these embodiments are merely illustrative and not intended to limit the scope of this application. Although various embodiments have been described above, this does not mean that the measures in the various embodiments cannot be used advantageously in combination. Without departing from the scope of this application, those skilled in the art can make various substitutions and modifications, all of which should fall within the scope of this application.

Claims

1. A laser mass transfer system based on a digital micromirror device and a scanning galvanometer, comprising: The laser source is configured to emit deep ultraviolet laser light. A digital micromirror device is configured to spatially modulate the deep ultraviolet laser to obtain a multi-level diffraction beam carrying target pattern information; The filtering module is configured to perform spatial filtering on the multi-level diffraction beam to suppress the zero-order light component and higher-order stray light component of the multi-level diffraction beam, so as to obtain a first-order diffraction beam. A scanning galvanometer is configured to deflect the optical path of the first-order diffracted beam to change the illumination position of the first-order diffracted beam. The focusing module is configured to focus the first-order diffracted beam after optical path deflection to obtain a focused beam; The chip on the donor substrate is configured to debond with the donor substrate under the irradiation of the focused beam and transfer to a receiving substrate below the donor substrate to achieve mass laser transfer.

2. The laser mass transfer system according to claim 1, characterized in that, The donor substrate is configured to move at a constant speed value along a first direction; The scanning galvanometer includes a first reflecting mirror, and the laser mass transfer system further includes: A synchronous motion device is configured to control the first reflective mirror to rotate around the rotation axis of the first reflective mirror in a first rotation mode, wherein, in the first rotation mode, the first reflective mirror is configured to control the irradiation position of the first-order diffraction beam, so that the focused spot formed by the focused beam on the plane where the donor substrate is located moves along the first direction at the first speed value.

3. The laser mass transfer system according to claim 1, characterized in that, The donor substrate is configured to move at a constant speed value along a first direction; The scanning galvanometer includes a first reflecting mirror, and the laser mass transfer system further includes: A jumping motion device is configured to, upon receiving a position jumping command, control the first reflective mirror to continuously rotate around the rotation axis of the first reflective mirror in a second rotation mode for a jumping duration. In the second rotation mode, the first reflective mirror is configured to control the irradiation position of the first-order diffraction beam, so that the focused beam forming a focused spot on the plane where the donor substrate is located moves along a second direction at a preset jumping speed value, the second direction being the opposite direction to the first direction.

4. The laser mass transfer system according to claim 3, characterized in that, The jumping motion device is configured as follows: The jump distance value is determined based on the position jump command; Add the jump speed value and the first speed value to determine the relative speed value; The jump duration is determined by dividing the jump distance value by the relative speed value.

5. The laser mass transfer system according to claim 2, characterized in that, The scanning galvanometer further includes a second reflecting mirror, the rotation axis of which is perpendicular to the rotation axis of the first reflecting mirror. The laser mass transfer system further includes: A longitudinal motion device is configured to control the second reflective mirror to rotate around the rotation axis of the second reflective mirror in a third rotation mode, wherein, in the third rotation mode, the second reflective mirror is configured to control the irradiation position of the first-order diffraction beam, so that the focused beam forming a focused spot on the plane where the donor substrate is located reciprocates along a third direction, the third direction being a direction perpendicular to the first direction.

6. The laser mass transfer system according to claim 1, characterized in that, The laser mass transfer system also includes a micromirror control module, which is configured as follows: Obtain a defect distribution map, wherein the defect distribution map is used to characterize the distribution of defective chips on the donor substrate; Based on the defect distribution map, a binarized target matrix is ​​determined, wherein each element value of the binarized target matrix is ​​used to characterize whether there is a defective chip at the corresponding point on the donor substrate; Based on the binarized target matrix, an amplitude-type binary computational hologram is generated; Based on the color state of each pixel in the amplitude-type binary computational hologram, the deflection state of each corresponding micromirror unit in the digital micromirror device is controlled.

7. The laser mass transfer system according to claim 1, characterized in that, The filtering module includes: The first Fourier lens, wherein the digital micromirror device is located at the front focal plane of the first Fourier lens, and the first Fourier lens is configured to perform spatial Fourier transform processing on the multi-level diffracted beam to obtain a first beam. A spatial filter is located at the back focal plane of the first Fourier lens. The spatial filter is configured to absorb the zero-order light component and higher-order stray light component of the first beam to obtain a second beam. The second Fourier lens, wherein the spatial filter is located at the front focal plane of the second Fourier lens, is configured to perform inverse Fourier transform processing on the second beam to obtain a first-order diffracted beam.

8. The laser mass transfer system according to claim 7, characterized in that, The spatial filter is a stray light elimination aperture with a central through-hole, and the stray light elimination aperture is configured to absorb the zero-order light component and higher-order stray light component in the first beam that deviate from the optical axis of the stray light elimination aperture.

9. The laser mass transfer system according to claim 1, characterized in that, The focusing module is a telecentric flat-field lens, which is configured to perform flat-field focusing on the first-order diffracted beam.

10. A laser mass transfer method based on a digital micromirror device and a scanning galvanometer, applied to the laser mass transfer system as described in any one of claims 1-9, comprising: Emitting deep ultraviolet laser; Spatial amplitude modulation of the deep ultraviolet laser is performed to obtain a multi-level diffracted beam; Spatial filtering is performed on the multi-order diffracted beam to suppress the zero-order light component and higher-order stray light component of the multi-order diffracted beam, so as to obtain a first-order diffracted beam. The optical path of the first-order diffracted beam is deflected to change the illumination position of the first-order diffracted beam; The first-order diffracted beam after optical path refraction is focused to obtain a focused beam; The chip on the donor substrate is configured to debond from the donor substrate under the irradiation of the focused beam and transfer to a receiving substrate below the donor substrate to achieve mass laser transfer.

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