阅读说明：本技术 微型器件的转移方法 (Transfer method of micro device ) 是由 陈来成 刘卫梦 华聪聪 于 2021-09-02 设计创作，主要内容包括：本申请涉及一种微型器件的转移方法,包括以下步骤：透明基板的一侧具有第一粘胶层,多个微型器件通过第一粘胶层粘附于透明基板；将透明基板的粘附有微型器件的一侧与一载体基板的具有第二粘胶层的一侧贴靠；确定使用的激光能量,对目标微型器件所在目标区域的第一粘胶层进行照射固化以降低粘度,使目标微型器件转移至载体基板上；将载体基板的粘附有目标微型器件的一侧与接收基板的接收侧对位贴靠,并降低第二粘胶层的粘度,使目标微型器件转移至接收基板上。通过选择激光能量对目标区域的第一粘胶层进行精准、快速的局部固化,并利用具有第二粘胶层的载体基板准确对位转移目标微型器件,提高了转移速度和转移精度,且转移过程高效易操作。(The application relates to a micro device transfer method, which comprises the following steps: one side of the transparent substrate is provided with a first adhesive layer, and the plurality of micro devices are adhered to the transparent substrate through the first adhesive layer; the side of the transparent substrate, on which the micro device is adhered, is attached to the side of a carrier substrate, which is provided with a second adhesive layer; determining the used laser energy, irradiating and curing the first adhesive layer of the target area where the target micro device is located to reduce the viscosity, and transferring the target micro device to the carrier substrate; and aligning and attaching the side, adhered with the target micro device, of the carrier substrate with the receiving side of the receiving substrate, and reducing the viscosity of the second adhesive layer to transfer the target micro device onto the receiving substrate. The first adhesive layer of the target area is accurately and quickly locally cured by selecting laser energy, and the carrier substrate with the second adhesive layer is used for accurately aligning and transferring the target micro device, so that the transferring speed and the transferring precision are improved, and the transferring process is efficient and easy to operate.)

1. A method for transferring a micro device, comprising the steps of:

s1, providing a transparent substrate, wherein one side of the transparent substrate is provided with a first adhesive layer, and the plurality of micro devices are adhered to the transparent substrate through the first adhesive layer;

s2, the side of the transparent substrate adhered with the micro device is attached to the side of a carrier substrate with a second adhesive layer;

s3, determining the laser energy to be used, irradiating the laser from the side of the transparent substrate, to which the micro device is not adhered, curing the first adhesive layer of the target area where the target micro device is positioned to reduce the viscosity of the first adhesive layer of the target area, and transferring the target micro device to the carrier substrate;

and S4, aligning and attaching the side, adhered with the target micro device, of the carrier substrate and the receiving side of the receiving substrate, and reducing the viscosity of the second adhesive layer to transfer the target micro device onto the receiving substrate.

2. The method for transferring a micro device according to claim 1, wherein in the step S3, the laser energy is used to determine at least one of a distance between a focused spot of the laser and the transparent substrate, a laser frequency, and a laser power.

3. The method for transferring a micro device according to claim 2, wherein the step S3 includes:

s31: determining target laser energy corresponding to a target viscosity difference of a first adhesive layer positioned in the target area before and after the first adhesive layer absorbs the laser energy based on a preset model;

s32: determining at least one of the distance between a focusing spot of laser and the transparent substrate, the laser frequency and the laser power according to the target laser energy;

s33: and irradiating the side, which is not adhered with the micro device, of the transparent substrate by using laser, curing the first adhesive layer of the target area where the target micro device is located so as to reduce the viscosity of the first adhesive layer at the target area, and transferring the target micro device onto the carrier substrate.

4. The method for transferring a micro device according to claim 3, wherein the step of S32 includes:

determining the distance between a focusing spot of laser and the transparent substrate according to the distance between the micro devices;

and determining the laser frequency and the laser power according to the target laser energy and the distance between the focusing spot of the laser and the transparent substrate.

5. The method for transferring a micro device according to claim 1, wherein the step of S4 comprises the steps of:

s41: aligning and attaching one side of the carrier substrate, on which the target micro device is adhered, to a receiving side of a receiving substrate;

s42: and carrying out heating and/or light radiation treatment on the carrier substrate, reducing the viscosity of the second adhesive layer, and transferring the target micro device onto the receiving substrate.

6. The method for transferring a Micro device according to claim 5, wherein the Micro device is a Micro-LED, and after the step of S41, the method further comprises:

the receiving substrate is warmed prior to transfer to bond the target micro device to the pads on the receiving side of the receiving substrate.

7. The method of transferring a micro device according to any one of claims 1 to 6, wherein alignment marks are provided on the transparent substrate, the carrier substrate, and the receiving substrate, respectively.

8. A method for transferring a micro device, comprising the steps of:

s10, providing a transparent substrate, wherein one side of the transparent substrate is provided with a first adhesive layer, and the plurality of micro devices are adhered to the transparent substrate through the first adhesive layer;

s20, aligning the side of the transparent substrate adhered with the micro device with a carrier substrate;

s30, determining target laser energy corresponding to the target viscosity difference of the first adhesive layer in the target area of the transparent substrate before and after the first adhesive layer absorbs the laser energy based on a preset model;

s40, determining at least one of the distance between the focusing spot of the laser and the transparent substrate, the laser frequency and the laser power according to the target laser energy;

and S50, irradiating the transparent substrate from the side without the micro device, curing the first adhesive layer in the target area to reduce the viscosity of the first adhesive layer in the target area, and transferring the target micro device in the target area to the carrier substrate.

9. The method for transferring a micro device according to claim 8, wherein the step S40 includes:

determining the distance between a focusing spot of laser and the transparent substrate according to the distance between the micro devices;

and determining the laser frequency and the laser power according to the target laser energy and the distance between the focusing spot of the laser and the transparent substrate.

10. The method of claim 8, wherein the viscosity of the first adhesive layer in the target area after absorbing the laser energy is 1/10-1/1000 of the initial viscosity.

11. The method of transferring a micro device according to claim 8, further comprising:

carrying out a plurality of groups of experiments;

collecting a plurality of sets of experimental data, wherein the experimental data comprise laser energy, viscosity difference of the first adhesive layer and a transfer result of the micro device from the transparent substrate to the carrier substrate;

and training an SVM model by taking multiple groups of experimental data as training data, and optimizing parameters of the SVM model by adopting a PSO algorithm to obtain the preset model.

12. The method for transferring a micro device according to claim 8, wherein the step S20 includes:

providing the carrier substrate, wherein one side of the carrier substrate is provided with a second adhesive layer;

and aligning and attaching the side, adhered with the micro device, of the transparent substrate to the side, provided with the second adhesive layer, of the carrier substrate.

13. The method of claim 12, wherein the second adhesive layer is an elastic material, and the viscosity of the second adhesive layer is less than the viscosity of the first adhesive layer before the first adhesive layer absorbs the laser energy and greater than the viscosity of the first adhesive layer after the first adhesive layer absorbs the laser energy.

Technical Field

The application relates to the technical field of micro devices, in particular to a transfer method of a micro device.

Background

An LED is a semiconductor electronic element capable of emitting light, and has advantages of high energy conversion efficiency, short reaction time, long service life, etc., and a Micro LED (Micro-LED) is a Micro device obtained by making a conventional LED structure into a thin film, a Micro-structure, and an array. The manufacturing of a large-size and high-resolution Micro-LED display screen requires the Transfer assembly of millions or tens of millions of micron-sized Micro-LED chips, Mass Transfer (MTP) requires the precise Transfer and fixation of micron-sized Micro-LED chips from a donor wafer onto a target substrate, and a mobile phone screen using Micro-LEDs is mounted at the current mainstream LED die-bonding speed in tens of days. Therefore, it is necessary to provide a new method for increasing the transfer speed and the transfer accuracy to speed up the industrialization of the Micro-LED display technology.

Disclosure of Invention

In view of the above technical problems, the present application provides a method for transferring a micro device, which can improve the transfer speed and the transfer precision, and the transfer process is efficient and easy to operate.

In order to solve the above technical problem, the present application provides a method for transferring a micro device, including the following steps:

s1, providing a transparent substrate, wherein one side of the transparent substrate is provided with a first adhesive layer, and the plurality of micro devices are adhered to the transparent substrate through the first adhesive layer;

s2, the side of the transparent substrate adhered with the micro device is attached to the side of a carrier substrate with a second adhesive layer;

s3, determining the laser energy to be used, irradiating the laser from the side of the transparent substrate, to which the micro device is not adhered, curing the first adhesive layer of the target area where the target micro device is positioned to reduce the viscosity of the first adhesive layer of the target area, and transferring the target micro device to the carrier substrate;

and S4, aligning and attaching the side, adhered with the target micro device, of the carrier substrate and the receiving side of the receiving substrate, and reducing the viscosity of the second adhesive layer to transfer the target micro device onto the receiving substrate.

Optionally, in the step S3, the laser energy is used to determine at least one of a distance between a focused spot of the laser and the transparent substrate, a laser frequency, and a laser power.

Optionally, the step S3 includes:

s31: determining target laser energy corresponding to a target viscosity difference of a first adhesive layer positioned in the target area before and after the first adhesive layer absorbs the laser energy based on a preset model;

s32: determining at least one of the distance between a focusing spot of laser and the transparent substrate, the laser frequency and the laser power according to the target laser energy;

s33: and irradiating the side, which is not adhered with the micro device, of the transparent substrate by using laser, curing the first adhesive layer of the target area where the target micro device is located so as to reduce the viscosity of the first adhesive layer at the target area, and transferring the target micro device onto the carrier substrate.

Optionally, the step S32 includes:

determining the distance between a focusing spot of laser and the transparent substrate according to the distance between the micro devices;

and determining the laser frequency and the laser power according to the target laser energy and the distance between the focusing spot of the laser and the transparent substrate.

Optionally, the viscosity of the first adhesive layer in the target area after absorbing the laser energy is 1/10-1/1000 of the initial viscosity.

Optionally, the second adhesive layer is made of an elastic material, and the viscosity of the second adhesive layer is less than the viscosity of the first adhesive layer before the first adhesive layer absorbs the laser energy and is greater than the viscosity of the first adhesive layer after the first adhesive layer absorbs the laser energy.

Optionally, the method further comprises:

carrying out a plurality of groups of experiments;

collecting a plurality of sets of experimental data, wherein the experimental data comprise laser energy, viscosity difference of the first adhesive layer and a transfer result of the micro device from the transparent substrate to the carrier substrate;

and training an SVM model by taking multiple groups of experimental data as training data, and optimizing parameters of the SVM model by adopting a PSO algorithm to obtain the preset model.

Optionally, the step of S4 includes the following steps:

s41: aligning and attaching one side of the carrier substrate, on which the target micro device is adhered, to a receiving side of a receiving substrate;

s42: and carrying out heating and/or light radiation treatment on the carrier substrate, reducing the viscosity of the second adhesive layer, and transferring the target micro device onto the receiving substrate.

Optionally, the Micro device is a Micro-LED, and after the step S41, the method further includes:

the receiving substrate is warmed prior to transfer to bond the target micro device to the pads on the receiving side of the receiving substrate.

Optionally, alignment marks are respectively disposed on the transparent substrate, the carrier substrate, and the receiving substrate.

The present application also provides a second method of transferring a micro device, comprising the steps of:

s10, providing a transparent substrate, wherein one side of the transparent substrate is provided with a first adhesive layer, and the plurality of micro devices are adhered to the transparent substrate through the first adhesive layer;

s20, aligning the side of the transparent substrate adhered with the micro device with a carrier substrate;

s30, determining target laser energy corresponding to the target viscosity difference of the first adhesive layer in the target area of the transparent substrate before and after the first adhesive layer absorbs the laser energy based on a preset model;

s40, determining at least one of the distance between the focusing spot of the laser and the transparent substrate, the laser frequency and the laser power according to the target laser energy;

and S50, irradiating the transparent substrate from the side without the micro device, curing the first adhesive layer in the target area to reduce the viscosity of the first adhesive layer in the target area, and transferring the target micro device in the target area to the carrier substrate.

Optionally, the step S40 includes:

determining the distance between a focusing spot of laser and the transparent substrate according to the distance between the micro devices;

and determining the laser frequency and the laser power according to the target laser energy and the distance between the focusing spot of the laser and the transparent substrate.

Optionally, in the second method, the viscosity of the first adhesive layer in the target area after absorbing the laser energy is 1/10-1/1000 of the initial viscosity.

Optionally, the second method further includes:

carrying out a plurality of groups of experiments;

collecting a plurality of sets of experimental data, wherein the experimental data comprise laser energy, viscosity difference of the first adhesive layer and a transfer result of the micro device from the transparent substrate to the carrier substrate;

and training an SVM model by taking multiple groups of experimental data as training data, and optimizing parameters of the SVM model by adopting a PSO algorithm to obtain the preset model.

Optionally, the step S20 includes:

providing the carrier substrate, wherein one side of the carrier substrate is provided with a second adhesive layer;

and aligning and attaching the side, adhered with the micro device, of the transparent substrate to the side, provided with the second adhesive layer, of the carrier substrate.

Optionally, in the second method, the second adhesive layer is made of an elastic material, and the viscosity of the second adhesive layer is less than the viscosity of the first adhesive layer before the first adhesive layer absorbs the laser energy and greater than the viscosity of the first adhesive layer after the first adhesive layer absorbs the laser energy.

Optionally, after the step of S50, the method further includes the following steps:

and S60, aligning and attaching the side, adhered with the target micro device, of the carrier substrate and the receiving side of the receiving substrate, and reducing the viscosity of the second adhesive layer to transfer the target micro device onto the receiving substrate.

Optionally, the step of S60 includes the following steps:

s61: aligning and attaching one side of the carrier substrate, on which the target micro device is adhered, to a receiving side of a receiving substrate;

s62: and carrying out heating and/or light radiation treatment on the carrier substrate, reducing the viscosity of the second adhesive layer, and transferring the target micro device onto the receiving substrate.

Optionally, the Micro device is a Micro-LED, and after the step S61, the method further includes:

the receiving substrate is warmed prior to transfer to bond the target micro device to the pads on the receiving side of the receiving substrate.

Optionally, in the second method, alignment marks are respectively disposed on the transparent substrate, the carrier substrate, and the receiving substrate.

The transfer method of the micro device comprises the following steps: one side of the transparent substrate is provided with a first adhesive layer, and the plurality of micro devices are adhered to the transparent substrate through the first adhesive layer; the side of the transparent substrate, on which the micro device is adhered, is attached to the side of a carrier substrate, which is provided with a second adhesive layer; determining the used laser energy, irradiating and curing the first adhesive layer of the target area where the target micro device is located to reduce the viscosity, and transferring the target micro device to the carrier substrate; and aligning and attaching the side, adhered with the target micro device, of the carrier substrate with the receiving side of the receiving substrate, and reducing the viscosity of the second adhesive layer to transfer the target micro device onto the receiving substrate. The first adhesive layer of the target area is accurately and quickly locally cured by selecting laser energy, and the carrier substrate with the second adhesive layer is used for accurately aligning and transferring the target micro device, so that the transferring speed and the transferring precision are improved, and the transferring process is efficient and easy to operate.

The transfer method of the micro device comprises the following steps: providing a transparent substrate, wherein one side of the transparent substrate is provided with a first adhesive layer, and a plurality of micro devices are adhered to the transparent substrate through the first adhesive layer; aligning one side of the transparent substrate, which is adhered with the micro device, with a carrier substrate; determining target laser energy corresponding to a target viscosity difference of a first adhesive layer in a target area of the transparent substrate before and after the first adhesive layer absorbs the laser energy based on a preset model; determining at least one of the distance between a focusing spot of the laser and the transparent substrate, the laser frequency and the laser power according to the target laser energy; and irradiating the side of the transparent substrate, to which the micro device is not adhered, by using laser, curing the first adhesive layer in the target area to reduce the viscosity of the first adhesive layer in the target area, and transferring the target micro device in the target area to the carrier substrate. By selecting laser energy, the fluctuation range of the polymerization initiator corresponding to the optimal distance between the focusing spot of the laser and the transparent substrate can not influence adjacent micro devices, particularly micro devices which do not need to be transferred, and by regulating the optimal distance and determining corresponding laser frequency and laser power, the first adhesive layer of a target area can be accurately and quickly locally cured, so that the target micro devices can be transferred without transferring the adjacent micro devices, and the transfer precision is improved.

Drawings

Fig. 1 is a schematic flow chart illustrating a method of transferring a micro device according to a first embodiment;

fig. 2 is a schematic view showing a step S1 in the transfer method of the micro device according to the first embodiment;

fig. 3 is a schematic view showing a step S2 in the transfer method of the micro device according to the first embodiment;

fig. 4 is one of schematic diagrams of a step S3 in the transfer method of the micro device shown in the first embodiment;

fig. 5 is a second schematic view of the step S3 in the transfer method of the micro device shown in the first embodiment;

fig. 6 is one of schematic diagrams of a step S4 in the transfer method of the micro device shown in the first embodiment;

fig. 7 is a second schematic view of the step S4 in the transfer method of the micro device shown in the first embodiment;

fig. 8 is a flowchart illustrating a transfer method of a micro device according to a second embodiment.

Detailed Description

The following description of the embodiments of the present application is provided for illustrative purposes, and other advantages and capabilities of the present application will become apparent to those skilled in the art from the present disclosure.

In the following description, reference is made to the accompanying drawings that describe several embodiments of the application. It is to be understood that other embodiments may be utilized and that mechanical, structural, electrical, and operational changes may be made without departing from the spirit and scope of the present application. The following detailed description is not to be taken in a limiting sense, and the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the application.

Although the terms first, second, etc. may be used herein to describe various elements in some instances, these elements should not be limited by these terms. These terms are only used to distinguish one element from another.

Also, as used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, unless the context indicates otherwise. It will be further understood that the terms "comprises," "comprising," "includes" and/or "including," when used in this specification, specify the presence of stated features, steps, operations, elements, components, items, species, and/or groups, but do not preclude the presence, or addition of one or more other features, steps, operations, elements, components, species, and/or groups thereof. The terms "or" and/or "as used herein are to be construed as inclusive or meaning any one or any combination. Thus, "A, B or C" or "A, B and/or C" means "any of the following: a; b; c; a and B; a and C; b and C; A. b and C ". An exception to this definition will occur only when a combination of elements, functions, steps or operations are inherently mutually exclusive in some way.

First embodiment

Fig. 1 is a schematic flow chart illustrating a method of transferring a micro device according to a first embodiment. As shown in fig. 1, the transfer method of the micro device of the present application includes the following steps:

s1, providing a transparent substrate, wherein one side of the transparent substrate is provided with a first adhesive layer, and the plurality of micro devices are adhered to the transparent substrate through the first adhesive layer;

s2, the side of the transparent substrate adhered with the micro device is attached to the side of a carrier substrate with a second adhesive layer;

s3, determining the laser energy to be used, irradiating the laser from the side of the transparent substrate, to which the micro device is not adhered, curing the first adhesive layer of the target area where the target micro device is located to reduce the viscosity of the first adhesive layer of the target area, and transferring the target micro device to the carrier substrate;

and S4, aligning and attaching the side of the carrier substrate, on which the target micro device is adhered, with the receiving side of the receiving substrate, and reducing the viscosity of the second adhesive layer to transfer the target micro device onto the receiving substrate.

Referring to fig. 2, in step S1, a photosensitive material with variable viscosity is coated on a first surface of a transparent substrate 100 to form a first adhesive layer 101, and the first adhesive layer 101 can be formed by a coating method such as spin coating or electrostatic spinning. The first adhesive layer 101 may be a photosensitive adhesive material for ultraviolet, infrared, and the like, and the first adhesive layer 101 adopted in this embodiment is an ultraviolet-sensitive adhesive material, optionally, the ultraviolet-sensitive adhesive material includes the following components by weight percent: 20-50% of (methyl) acrylic acid alkyl ester, 15-40% of (methyl) acrylic acid hydroxyalkyl ester, 10-15% of N atom polar monomer, 10-20% of reactive diluent, 0.1-2% of chain transfer agent, 0.5-1% of thermal initiator and 0.5-1% of photoinitiator. Alternatively, the transparent substrate 100 may be a sapphire substrate or other transparent material, and the plurality of micro devices 102 are peeled off from the sapphire substrate by means of transfer printing and transferred onto the first adhesive layer 101 of the transparent substrate 100, so as to be adhered to the first surface of the transparent substrate 100 by the first adhesive layer 101. Optionally, the Micro device 102 comprises a Micro-LED.

Referring to fig. 3, in step S2, the side of the transparent substrate 100 to which the micro device 102 is adhered is abutted against the side of the carrier substrate 105 having the second adhesive layer 104, so that the micro device 102 is in contact with the second adhesive layer 104, and the viscosity of the second adhesive layer 104 is smaller than the viscosity of the first adhesive layer 101 before absorbing the laser energy and larger than the viscosity of the first adhesive layer 101 after absorbing the laser energy, so that after the first adhesive layer 101 is irradiated with the laser and the viscosity is reduced, the adhesion between the micro device 102 on the first adhesive layer 101 at the laser irradiation position and the first adhesive layer 101 is smaller than the adhesion between the micro device 102 and the second adhesive layer 104, and the micro device 102 is transferred from the transparent substrate 100 to the carrier substrate 105.

Optionally, the second adhesive layer 104 is an elastic material, which can fix the micro devices 102 on one hand, and can also serve as a buffer layer to absorb part of the stress when the transparent substrate 100 is attached to the carrier substrate 105 to reduce the breakage of the micro devices 102. Optionally, the second adhesive layer 104 is a viscosity-variable material, including but not limited to a heat-sensitive material, a photosensitive material, a single-component polymer, and a multi-component polymer.

Referring to fig. 4 and 5, the transparent substrate 100 and the carrier substrate 105 are provided with alignment marks for alignment, and in step S3, the laser 103 is irradiated from the side of the transparent substrate 100 where the micro devices 102 are not adhered, and the first adhesive layer 101 in the target area where the target micro devices 102 are located is cured to reduce the viscosity of the first adhesive layer 101 in the target area, so that the target micro devices 102 are transferred onto the carrier substrate 105. By providing the carrier substrate 105 of the second adhesive layer 104 to pick up the target micro device 102 from the transparent substrate 100 in a contact manner, the target micro device 102 can be prevented from being displaced during the transfer process, and the positioning accuracy is higher.

Alternatively, a focused spot of the laser 103 at the minimum spot size of a specific lens is obtained by balancing diffraction and a spot effect, the transparent substrate 100 and the carrier substrate 105 which are attached to each other are adjusted to a proper position, and the laser 103 is irradiated from the second surface of the transparent substrate 100, so that the laser 103 is used as a polymerization initiator of the photosensitive material of the first adhesive layer 101, the first adhesive layer 101 in the target area where the target micro devices 102 with a specific pitch are located is locally cured, and the viscosity of the first adhesive layer 101 in the target area is reduced. The target micro device 102, i.e. the micro device 102 to be transferred, and optionally the laser 103 may be an active laser such as ultraviolet, infrared, etc., and the viscosity of the first adhesive layer 101 in the target area after absorbing the laser energy is preferably 1/10-1/1000 of the initial viscosity.

Optionally, in step S3, the laser energy is used to determine at least one of a distance between the focused spot of the laser 103 and the transparent substrate 100, a laser frequency, and a laser power. Optionally, the step of S3, including:

s31: determining target laser energy corresponding to a target viscosity difference of a first adhesive layer positioned in a target area before and after the first adhesive layer absorbs the laser energy based on a preset model;

s32: determining at least one of the distance between a focusing spot of the laser and the transparent substrate, the laser frequency and the laser power according to the target laser energy;

s33: and irradiating the side, which is not adhered with the micro device, of the transparent substrate by using laser, curing the first adhesive layer of the target area where the target micro device is positioned so as to reduce the viscosity of the first adhesive layer positioned in the target area, and transferring the target micro device onto the carrier substrate.

Optionally, the preset model is optimized based on experimental data, and is used for characterizing a relationship between laser energy of the laser 103, a viscosity difference of the first adhesive layer 101 before and after absorbing the laser energy, and a transfer result of the micro device 102 from the transparent substrate 100 to the carrier substrate 105. Before the step S31, a target viscosity difference before and after the laser energy is absorbed by the first adhesive layer 101 may be determined according to reference factors such as a material type of the first adhesive layer 101, a thickness of the first adhesive layer 101, a size of the target micro device, and the like, and then the target viscosity difference is input into a preset model, and based on the laser energy and the transfer result output by the preset model, the laser energy that may be selected when the transfer result is successful is determined, that is, the target laser energy.

Optionally, to obtain the preset model, the method of the present application further includes:

carrying out a plurality of groups of experiments;

collecting a plurality of groups of experimental data, wherein the experimental data comprise laser energy, viscosity difference of the first adhesive layer and a transfer result of the micro device from the transparent substrate to the carrier substrate;

and training the SVM model by taking the multiple groups of experimental data as training data, and optimizing parameters of the SVM model by adopting a PSO algorithm to obtain a preset model.

Alternatively, the transfer system of the micro device 102 is composed of an XY stage, a Z stage, an orientation stage, and an optical camera, the positioning resolution of the XY stage is 0.5 μm, and the transparent substrate 100 moves up and down along the Z stage to be in contact with or separated from the carrier substrate 105. The result of transferring the micro devices 102 from the transparent substrate 100 to the carrier substrate 105 was mainly influenced by two factors, i.e., the viscosity difference of the first adhesive layer 101 before and after absorbing the laser energy and the laser energy, and in the experiment, software was used to control the motion controller of the transfer system, specifically, to regulate the laser energy (adjusting the laser frequency, power and distance between the focus spot and the transparent substrate 100), and then to move the transparent substrate 100 downward along the Z-axis until the micro devices 102 on the transparent substrate 100 and the second adhesive layer 104 on the carrier substrate 105 were in contact. The laser 103 acts as a polymerization initiator for the photo-sensitive material of the first adhesive layer 101 to change the viscosity of the first adhesive layer 101 at the location of the micro device 102 to be transferred.

Optionally, to distinguish whether the result of the transfer of the micro device 102 from the transparent substrate 100 to the carrier substrate 105 was successful, a classifier model based on SVM (Support Vector Machine) is required. The present embodiment introduces a gaussian kernel function as a kernel function of the SVM-based classifier model to recognize the characteristic signal, the transfer experiment of the microdevice 102 from the transparent substrate 100 to the carrier substrate 105 is repeatedly performed several hundred times, the laser energy and the viscosity difference of the first adhesive layer 101 before and after absorbing the laser energy are extracted from the experimental data as the characteristic signal, and the training data includes a large amount of laser energy, the viscosity difference of the first adhesive layer 101, and the transfer result of the microdevice 102 from the transparent substrate 100 to the carrier substrate 105.

When the SVM is used to process non-linear indivisible samples, the original dimensional space data may first be mapped to a higher dimensional space. Given a training set T:

T＝{(X₁,Y₁),(X₁,Y₁),…,(X_N,Y_N) In which X_i∈Rn,Y_i∈{+1,-1},i＝1,2,...N；

Wherein x is_iAnd y_jThe input vector and the output vector are respectively, the input vector is the laser energy and the viscosity difference of the first adhesive layer 101 before and after absorbing the laser energy as characteristic signals, the output vector is the transfer result of the micro device 102 from the transparent substrate 100 to the carrier substrate 105, the transfer result can be represented by 1 as success, and the output vector is represented by-1 as failure. In this embodiment, the optimal cost parameter C > 0 is selected, and a gaussian kernel function is selected as the kernel function K (x, y):

the corresponding SVM is a gaussian radial basis function classifier, in which case the classification decision function is:

the training parameters of the SVM model with a Gaussian kernel function are optimal cost parameters (C) for controlling the overfitting of the model. The classification performance of the SVM model depends on C, and in order to improve classification, parameters of the SVM model are optimized by using a PSO (Particle Swarm Optimization) algorithm. The PSO algorithm can realize global optimization by iteratively searching for an optimal solution and utilizing a local optimal value.

In general, each laser power (p) and the difference in adhesion (a) can be expressed as,

p_id(f+1)＝w×p_id(f)+c₁×rabd₁×(pbest_d(f)-a_id(f))+c₂×rand₂×(gbest_d(f)-a_id(f))

a_id(f+1)＝a_id(f)+p_id(f+1)

wherein p is_id(f +1) tableShowing the energy of particle i at the d-th iteration; a is_id(f +1) represents the position of particle i at the d-th iteration; w is the inertial weight controlling the influence of the laser energy of the previous step; t is the number of iterations; f is the laser frequency; c. C₁And c₂A non-negative learning factor; rand₁And rand₂Is [0,1 ]]Random numbers within the range as memory; pbest_dAnd gbest_dAnd respectively representing the positions of the local optimal solution and the global optimal solution of the particle i after the d-th iteration.

Finally, classification accuracy can be achieved based on the SVM model, and the transfer process is optimized by adjusting the transfer parameters of the model. The prediction based on the SVM model enables optimization of the microdevice transfer process and facilitates automated mass transfer of the microdevice 102.

In practical implementation, the step of obtaining the preset model may be performed before the step of S31, and the preset model may be retrained and optimized again by using the transition result based on the preset model in the step of S4 as experimental data.

Optionally, the step of S32, including:

determining the distance between the focusing spot of the laser and the transparent substrate according to the distance between the micro devices;

and determining the laser frequency and the laser power according to the target laser energy and the distance between the focusing spot of the laser and the transparent substrate.

Optionally, the laser used in this embodiment is a solid laser, and is composed of a laser working substance, a pump source, a light-gathering cavity and an optical resonant cavity, wherein the working substance is a crystal or glass seed as a matrix material, and a small amount of active ions are uniformly doped in the crystal or glass seed. Tunable Ce is selected in the embodiment³⁺A laser, which focuses a laser beam by means of a mirror, focuses a large beam to a single precise spot, and the thermal density of the spot is extremely high, and an optimal polymerization initiator can be obtained by adjusting the position of the transparent substrate 100.

The process of adjusting the polymerization initiator is realized by adjusting the distance between the focusing spot of the laser 103 and the transparent substrate 100 (or the first adhesive layer 101), the distance between the focusing spot and the transparent substrate 100 directly affects the polymerization degree and fluctuation range of the first adhesive layer 101 in the target area corresponding to the target micro device 102 reached by the polymerization initiator, and the fluctuation range of the polymerization initiator corresponding to the optimal distance between the focusing spot and the transparent substrate 100 cannot affect the adjacent micro device 102, especially cannot affect the micro device 102 not to be transferred, so that after the required laser energy is determined, the optimal distance is regulated and controlled, and the corresponding laser frequency and laser power are further determined, so that the target micro device 102 can be ensured to be transferred without transferring the adjacent micro device 102, and the transfer accuracy is improved. Optionally, the laser focusing device may be one or more.

Optionally, the step of S4, including the steps of:

s41: aligning and attaching one side of the carrier substrate, on which the target micro device is adhered, to a receiving side of the receiving substrate;

s42: and (3) carrying out heating and/or light radiation treatment on the carrier substrate, and reducing the viscosity of the second adhesive layer to transfer the target micro device onto the receiving substrate.

Alternatively, referring to fig. 6 and 7, alignment marks (not shown in fig. 6 and 7) are respectively disposed on the carrier substrate 105 and the receiving substrate 106, and the carrier substrate 105 and the receiving substrate 106 are aligned by the alignment marks. Optionally, the second adhesive layer 104 is an elastic material, which can fix the micro devices 102 on one hand, and can also serve as a buffer layer to absorb part of the stress to reduce the breakage of the micro devices 102 when the carrier substrate 105 is attached to the receiving substrate 106. Alternatively, the second adhesive layer 104 may be a viscosity-variable material, including but not limited to a heat-sensitive material, a photosensitive material, a single-component polymer, or a multi-component polymer, so that the viscosity of the second adhesive layer 104 can be reduced by subjecting the carrier substrate 105 to heating and/or light irradiation, and the target micro device 102 can be transferred to the receiving substrate 106 when the bonding force between the target micro device 102 and the receiving substrate 106 is greater than the bonding force between the target micro device and the carrier substrate 105.

Optionally, the Micro device 102 is a Micro-LED, and after the step of S41, the method further includes:

the receiving substrate is warmed prior to transfer to bond the target micro devices to the pads on the receiving side of the receiving substrate.

After the target micro device 102 is bonded to the solder pads on the receiving side of the receiving substrate 106, the bonding force between the target micro device 102 and the receiving substrate 106 will be greater than the adhesion force with the carrier substrate 105, and the target micro device 102 can be transferred to the receiving substrate 106 by separating the carrier substrate 105 from the receiving substrate 106.

Through the mode, the alignment problem of micro device transfer in the laser lift-off technology is improved, the adhesive layer is utilized to bear the target micro device which is locally solidified, the alignment effect can be improved, the micro device is easy to peel off, and the reject ratio of the micro device is reduced. In addition, the laser local solidification is adopted, a mask pattern does not need to be prepared, the process is simple and easy to operate, the cost is reduced, and the method is an effective method for efficient selective batch transfer of the micro devices.

The transfer method of the micro device comprises the following steps: one side of the transparent substrate is provided with a first adhesive layer, and the plurality of micro devices are adhered to the transparent substrate through the first adhesive layer; the side of the transparent substrate, on which the micro device is adhered, is attached to the side of a carrier substrate, which is provided with a second adhesive layer; determining the used laser energy, irradiating and curing the first adhesive layer of the target area where the target micro device is located to reduce the viscosity, and transferring the target micro device to the carrier substrate; and aligning and attaching the side, adhered with the target micro device, of the carrier substrate with the receiving side of the receiving substrate, and reducing the viscosity of the second adhesive layer to transfer the target micro device onto the receiving substrate. The first adhesive layer of the target area is accurately and quickly locally cured by selecting laser energy, and the carrier substrate with the second adhesive layer is used for accurately aligning and transferring the target micro device, so that the transferring speed and the transferring precision are improved, and the transferring process is efficient and easy to operate.

Second embodiment

Fig. 8 is a flowchart illustrating a transfer method of a micro device according to a second embodiment. As shown in fig. 8, the transfer method of the micro device of the present application includes the following steps:

s10, providing a transparent substrate, wherein one side of the transparent substrate is provided with a first adhesive layer, and the plurality of micro devices are adhered to the transparent substrate through the first adhesive layer;

s20, aligning the side of the transparent substrate adhered with the micro device with a carrier substrate;

s30, determining target laser energy corresponding to the target viscosity difference of the first adhesive layer in the target area of the transparent substrate before and after the first adhesive layer absorbs the laser energy based on a preset model;

s40, determining at least one of the distance between the focusing spot of the laser and the transparent substrate, the laser frequency and the laser power according to the target laser energy;

and S50, irradiating the transparent substrate from the side without the micro device, curing the first adhesive layer in the target area to reduce the viscosity of the first adhesive layer in the target area, and transferring the target micro device in the target area to the carrier substrate.

Optionally, the step of S40, including:

determining the distance between the focusing spot of the laser and the transparent substrate according to the distance between the micro devices;

and determining the laser frequency and the laser power according to the target laser energy and the distance between the focusing spot of the laser and the transparent substrate.

Optionally, the viscosity of the first adhesive layer in the target area after absorbing the laser energy is 1/10-1/1000 of the initial viscosity.

Optionally, the method further comprises:

carrying out a plurality of groups of experiments;

collecting a plurality of groups of experimental data, wherein the experimental data comprise laser energy, viscosity difference of the first adhesive layer and a transfer result of the micro device from the transparent substrate to the carrier substrate;

and training the SVM model by taking the multiple groups of experimental data as training data, and optimizing parameters of the SVM model by adopting a PSO algorithm to obtain a preset model.

Optionally, the step of S20, including:

providing a carrier substrate, wherein one side of the carrier substrate is provided with a second adhesive layer;

and aligning and attaching the side of the transparent substrate, on which the micro device is adhered, to the side of the carrier substrate, on which the second adhesive layer is arranged.

Optionally, in the second method, the second adhesive layer is made of an elastic material, and the viscosity of the second adhesive layer is less than the viscosity of the first adhesive layer before the first adhesive layer absorbs the laser energy and greater than the viscosity of the first adhesive layer after the first adhesive layer absorbs the laser energy.

Optionally, after the step of S50, the method further includes the following steps:

and S60, aligning and attaching the side of the carrier substrate, on which the target micro device is adhered, with the receiving side of the receiving substrate, and reducing the viscosity of the second adhesive layer to transfer the target micro device onto the receiving substrate.

Optionally, the step of S60, including the steps of:

s61: aligning and attaching one side of the carrier substrate, on which the target micro device is adhered, to a receiving side of the receiving substrate;

s62: and (3) carrying out heating and/or light radiation treatment on the carrier substrate, and reducing the viscosity of the second adhesive layer to transfer the target micro device onto the receiving substrate.

Optionally, the Micro device is a Micro-LED, and after the step S61, the method further includes:

the receiving substrate is warmed prior to transfer to bond the target micro devices to the pads on the receiving side of the receiving substrate.

Optionally, the transparent substrate, the carrier substrate and the receiving substrate are respectively provided with an alignment mark.

An implementation manner of the above steps may be the same as that described in the first embodiment, and is not described herein again.

In another implementation manner, in step S50, the laser may be used to irradiate the transparent substrate from the side where the micro devices are not adhered, cure the first adhesive layer in the target area to reduce the viscosity of the first adhesive layer in the target area, and allow the target micro devices in the target area to fall off the transparent substrate and be transferred to a carrier substrate, in which the carrier substrate is only required to be placed a specified distance below the transparent substrate for alignment. In addition, in this implementation, the carrier substrate can also be provided with a second adhesive layer on the side for receiving the micro device, so that after the target micro device falls off from the transparent substrate, the target micro device can be buffered and positioned, and the transfer precision is improved. In this implementation, after the target micro device is transferred to a carrier substrate, the transfer may be ended, or step S60 may still be performed, and the process of transferring the target micro device from the carrier substrate to the receiving substrate is the same as the first implementation, and is not described herein again.

The transfer method of the micro device comprises the following steps: providing a transparent substrate, wherein one side of the transparent substrate is provided with a first adhesive layer, and a plurality of micro devices are adhered to the transparent substrate through the first adhesive layer; aligning one side of the transparent substrate, which is adhered with the micro device, with a carrier substrate; determining target laser energy corresponding to a target viscosity difference of a first adhesive layer in a target area of the transparent substrate before and after the first adhesive layer absorbs the laser energy based on a preset model; determining at least one of the distance between a focusing spot of the laser and the transparent substrate, the laser frequency and the laser power according to the target laser energy; and irradiating the side of the transparent substrate, to which the micro device is not adhered, by using laser, curing the first adhesive layer in the target area to reduce the viscosity of the first adhesive layer in the target area, and transferring the target micro device in the target area to the carrier substrate. By selecting laser energy, the fluctuation range of the polymerization initiator corresponding to the optimal distance between the focusing spot of the laser and the transparent substrate can not influence adjacent micro devices, particularly micro devices which do not need to be transferred, and by regulating the optimal distance and determining corresponding laser frequency and laser power, the first adhesive layer of a target area can be accurately and quickly locally cured, so that the target micro devices can be transferred without transferring the adjacent micro devices, and the transfer precision is improved.

The above embodiments are merely illustrative of the principles and utilities of the present application and are not intended to limit the application. Any person skilled in the art can modify or change the above-described embodiments without departing from the spirit and scope of the present application. Accordingly, it is intended that all equivalent modifications or changes which can be made by those skilled in the art without departing from the spirit and technical concepts disclosed in the present application shall be covered by the claims of the present application.