Magnetic assembly micro device transfer assembly structure and transfer assembly method

Abstract

This invention discloses a magnetically assembled microdevice transfer assembly structure and method. The magnetically assembled microdevice transfer assembly structure includes: a temporary transfer microdevice with micro / nano scale, comprising the microdevice and a magnetic connection layer, the magnetic connection layer being detachably fixed to the microdevice; and a magnetic platform, comprising a magnetic generating layer and a patterned soft magnetic material layer sequentially arranged along a first direction. The magnetic generating layer is at least used to provide an adjustable magnetic field, and the magnetic generating layer and the magnetic connection layer located within the magnetic field are magnetically attracted. The patterned soft magnetic material layer is at least used to guide magnetic field lines in the magnetic field, thereby enabling the temporary transfer microdevice with micro / nano scale to be magnetically attracted and fixed to the magnetic platform, or enabling the temporary transfer microdevice with micro / nano scale to detach from the magnetic platform. This invention enables selective transfer of RGB three-color modules and subsequent yield testing and repair work by selectively adsorbing or retracting microdevices via magnetic attraction.

Description

Technical Field

[0001] This invention relates in particular to a magnetic assembly microdevice transfer assembly structure and transfer assembly method, belonging to the field of semiconductor technology. Background Technology

[0002] Micro-LED display technology refers to the miniaturization and arraying of micron-sized self-emissive light-emitting diode (LED) chips, integrating them into a high-density array on a driving panel through mass transfer and bonding technologies. This allows each Micro-LED unit to be individually controlled and driven, achieving monochrome or red, green, and blue (RGB) light emission. Compared with mainstream LCD and OLED displays, Micro-LED offers numerous advantages, including low power consumption, high efficiency, high integration, long lifespan, wide operating temperature range, and fast response time, and is considered a next-generation display technology.

[0003] However, Micro-LED still faces some key technological bottlenecks, with mass transfer being a crucial step towards mass production. Due to the small size of the LED chips to be transferred and the sheer number of chips, factors such as equipment precision, process yield, transfer time, transfer technology, detection methods, repeatability, and cost are essential considerations for mass transfer. Currently, the main solutions for mass transfer include precision gripping, selective release, self-assembly, and transfer printing technologies. Precision gripping, based on the type of force applied during transfer, is further categorized into electrostatic force, van der Waals force, and magnetic force.

[0004] Existing mass transfer technologies still cannot adequately meet the demands of mass production. Among them, transfer technology utilizes a transfer system to precisely control Micro-LEDs through a feedback module, ultimately transferring Micro-LEDs precisely onto a substrate to achieve mass transfer. For example, the mass transfer method based on roller transfer disclosed in CN113270341A has the advantages of high efficiency and speed, but the transfer cost is huge and the requirements are strict. Uneven pressure may lead to a decrease in transfer yield.

[0005] Electrostatic force and van der Waals force precision grasping utilize electrostatic attraction, repulsion and intermolecular forces to pick up or place Micro-LEDs. The applied force is affected by many factors such as chip size, picking speed, dielectric layer thickness and temperature. Therefore, this kind of mass transfer method cannot accurately guarantee accuracy and yield.

[0006] Fluid assembly technology involves placing chips within a fluid and controlling the fluid flow to disperse and align Micro-LEDs, ultimately allowing the Micro-LED chips to self-assemble onto a substrate. For example, the fluid assembly transfer method disclosed in CN111223798A offers low transfer costs and high precision, but it is difficult to achieve subsequent chip inspection and repair, as well as selective transfer of RGB colors. Furthermore, the impact of the fluid on the performance and lifespan of the Micro-LED chip is unknown, making it impossible to guarantee yield.

[0007] Magnetic assembly transfer technology precisely picks up and adsorbs Micro-LED chips using magnetic force, then aligns and brings the adsorbed Micro-LED chips into contact with a receiving substrate to complete mass transfer. This mass transfer technology not only has the advantages of high transfer accuracy and high transfer speed, but also can achieve selective transfer of RGB colors through magnetic selection. Subsequent yield testing and repair can also be performed through magnetic modules. Therefore, magnetic assembly mass transfer technology is a highly promising technology. For example, CN111244010A discloses a magnetic assembly process that uses micron-level electromagnetic coils in a transfer device to magnetically adsorb or release LED chips, which can greatly improve assembly efficiency. However, the manufacturing cost is high, the micron-level electromagnetic coils are difficult to manufacture, and crosstalk between electromagnetic coils cannot be avoided, which is not conducive to the realization of magnetic assembly. Summary of the Invention

[0008] The main objective of this invention is to provide a magnetic assembly microdevice transfer assembly structure and transfer assembly method, thereby overcoming the shortcomings of the prior art.

[0009] To achieve the aforementioned objectives, the technical solution adopted by this invention includes:

[0010] The present invention provides a magnetic assembly structure for transferring and assembling microdevices, including a magnetic platform and temporary transfer microdevices with micro-nano scale. The magnetic platform can magnetically attract / retract the temporary transfer microdevices, thereby realizing the transfer and assembly of microdevices.

[0011] Furthermore, the temporary transfer microdevice includes a microdevice and a magnetic connection layer, the magnetic connection layer being detachably fixed to the microdevice; the magnetic platform includes a magnetic generating layer and a patterned soft magnetic material layer sequentially stacked along a first direction, the magnetic generating layer being at least used to provide an adjustable magnetic field, the magnetic generating layer being magnetically attracted to the magnetic connection layer located within the magnetic field, and the patterned soft magnetic material layer being at least used to guide magnetic lines of force in the magnetic field, so that the temporary transfer microdevice with micro / nano scale can be magnetically attracted and fixed to the magnetic platform, or, the temporary transfer microdevice with micro / nano scale can be detached from the magnetic platform.

[0012] Furthermore, the patterned soft magnetic material layer has a plurality of attraction and fixing surfaces spaced apart along the second direction, and adjacent attraction and fixing surfaces are isolated by a low permeability material layer. Each attraction and fixing surface corresponds to a temporary transfer microdevice. The second direction intersects with the first direction. For example, the first direction may be the longitudinal direction of the temporary transfer microdevice, and the second direction may be the transverse direction of the temporary transfer microdevice, or it may be understood as the planar extension direction of the patterned soft magnetic material layer.

[0013] Furthermore, the attraction fixing surface is parallel to the bottom surface of the magnetic generating layer, and the bottom surface of the magnetic generating layer faces the magnetic generating layer.

[0014] Furthermore, the patterned soft magnetic material layer includes a plurality of patterned soft magnetic material layers spaced apart along the second direction, adjacent patterned soft magnetic material layers are isolated by a low permeability material layer, each patterned soft magnetic material layer has an attraction fixing surface, or the patterned soft magnetic material layer includes a single patterned soft magnetic material layer, the surface of the patterned soft magnetic material layer has a plurality of isolation grooves spaced apart along the second direction, the plurality of isolation grooves divide the surface of the patterned soft magnetic material layer to form a plurality of attraction fixing surfaces, and a low permeability material layer is disposed in the isolation groove.

[0015] Furthermore, the thickness of the patterned soft magnetic material layer is 1–5 cm.

[0016] Furthermore, the depth of the isolation groove is 5-10 μm.

[0017] Furthermore, the radial cross-sectional area of ​​each of the patterned soft magnetic material layers gradually decreases in the direction away from the magnetic generation layer.

[0018] Furthermore, the axial cross-section of each of the patterned soft magnetic material layers is trapezoidal.

[0019] Furthermore, the radial cross-sectional area of ​​the isolation groove gradually increases in the direction away from the magnetic generation layer.

[0020] Furthermore, the axial cross-section of each of the isolation grooves is triangular.

[0021] Furthermore, the surface of the low permeability material layer is flush with the surface of the patterned soft magnetic material layer.

[0022] Furthermore, the material of the low magnetic permeability layer includes resin.

[0023] Furthermore, the pattern of the patterned soft magnetic material layer is set according to the substrate fixing area and the LED size.

[0024] Furthermore, the magnetic connection layer is made of a high-permeability alloy containing at least one of iron, cobalt, and nickel.

[0025] Furthermore, the patterned soft magnetic material layer has high permeability and magnetic induction intensity, while the area or magnetic loss of the hysteresis loop is small. The material of the patterned soft magnetic material layer includes ferrite, iron-silicon alloy or iron-silicon-aluminum alloy, etc.

[0026] In one specific embodiment, the microdevice is a vertical structure device, and the microdevice further includes an intermediate substrate, the vertical structure device being electrically connected to the intermediate substrate, and the magnetic connection layer being detachably fixed on the intermediate substrate.

[0027] Furthermore, the vertical structure device includes a first electrode, an epitaxial structure (or epitaxial wafer), and a second electrode. The intermediate substrate includes an intermediate substrate body, a first conductive layer, and a second conductive layer. Solder layers are electrically bonded to the first and second conductive layers. The second conductive layer of the intermediate substrate is electrically connected to the first electrode of the vertical structure device.

[0028] Furthermore, the material of the main body of the intermediate substrate is transparent, and the first conductive layer and the second conductive layer are transparent conductive layers. Of course, the intermediate substrate also includes a color conversion module and / or a driving module, etc. The structure of the intermediate substrate is known to those skilled in the art and will not be specifically limited here.

[0029] In another specific implementation, the microdevice is a flip-chip device, and the magnetic connection layer is detachably fixed to the flip-chip device.

[0030] Furthermore, the flip-chip device includes a first electrode, an epitaxial structure (or epitaxial wafer), and a second electrode, with the first electrode and the second electrode disposed on the same side of the epitaxial structure.

[0031] Furthermore, the first and second electrodes of the microdevice are disposed on the electrical surface (i.e., the epitaxial electrical surface) of the microdevice. Specifically, the first and second electrodes can be rotationally symmetric patterns / structures.

[0032] Furthermore, the temporary transfer microdevice also includes an adhesive layer, through which the magnetic connection layer is fixed to the microdevice, and the fixed bond between the adhesive layer and the microdevice can be released, thereby separating the magnetic connection layer from the microdevice.

[0033] Furthermore, the adhesive layer is made of a hot melt adhesive material, the adhesiveness of which decreases with increasing temperature; or, the adhesive layer is made of a thermally decomposable material, which decomposes and loses its adhesiveness after exceeding the thermal decomposition temperature; or, the adhesive layer is made of a photosensitive adhesive, which is cured by ultraviolet light and melts and loses its adhesiveness upon heating; or, the adhesive layer is made of a high-temperature resistant material that is soluble in a specific liquid.

[0034] Furthermore, the adhesive layer is made of strontium aluminate, and the specific liquid is water.

[0035] Furthermore, the magnetic generating layer includes a magnetic device and a magnetic adjustment mechanism, the magnetic adjustment mechanism cooperating with the magnetic device and at least used to adjust the magnetic attraction between the magnetic device and the magnetic connection layer.

[0036] Furthermore, the magnetic device includes a permanent magnet, and the magnetic adjustment mechanism includes a movable platform for driving the permanent magnet to move in a selected direction, and for changing the magnetic attraction between the magnetic device and the magnetic connection layer, at least by adjusting the distance between the permanent magnet and the temporary transfer microdevice.

[0037] Alternatively, the magnetic device includes an electromagnet, and the magnetic adjustment mechanism includes a control circuit electrically connected to a coil of the electromagnet, and alters the magnetic attraction between the magnetic device and the magnetic connection layer by adjusting the magnitude and / or direction of the current in the coil.

[0038] Furthermore, permanent magnets can be magnets or the like, while electromagnets include magnetic cores and coils wound around the magnetic cores.

[0039] Another aspect of the present invention provides a magnetic assembly microdevice transfer assembly method, comprising:

[0040] A microdevice is provided, on which a magnetic connection layer is disposed, thereby forming a temporary transfer microdevice;

[0041] A magnetic platform is provided, the magnetic platform comprising a magnetic generating layer and a patterned soft magnetic material layer sequentially stacked along a first direction, the magnetic generating layer being at least used to provide an adjustable magnetic field, and the patterned soft magnetic material layer being at least used to guide magnetic lines of force in the magnetic field; and the patterned soft magnetic material layer is positioned between the magnetic generating layer and the magnetic connection layer, and the magnetic field is adjusted so that the magnetic platform magnetically attracts and fixes the temporary transfer microdevice;

[0042] The temporary transfer microdevice is transferred onto the support substrate, and the temporary transfer microdevice is electrically connected to the support substrate.

[0043] By readjusting the magnetic field, the temporary transfer microdevice is detached from the magnetic platform;

[0044] Remove the magnetic connection layer of the temporary transfer microdevice.

[0045] Furthermore, the patterned soft magnetic material layer has a plurality of attraction and fixing surfaces spaced apart along the second direction, and adjacent attraction and fixing surfaces are isolated by a low permeability material layer. Each attraction and fixing surface corresponds to a temporary transfer microdevice. The second direction intersects with the first direction. For example, the first direction may be the longitudinal direction of the temporary transfer microdevice, and the second direction may be the transverse direction of the temporary transfer microdevice, or it may be understood as the planar extension direction of the patterned soft magnetic material layer.

[0046] Furthermore, the attraction fixing surface is parallel to the bottom surface of the magnetic generation layer.

[0047] Furthermore, the patterned soft magnetic material layer includes a plurality of patterned soft magnetic material layers spaced apart along the second direction, adjacent patterned soft magnetic material layers are isolated by a low permeability material layer, each patterned soft magnetic material layer has an attraction fixing surface, or the patterned soft magnetic material layer includes a single patterned soft magnetic material layer, the surface of the patterned soft magnetic material layer has a plurality of isolation grooves spaced apart along the second direction, the plurality of isolation grooves divide the surface of the patterned soft magnetic material layer to form a plurality of attraction fixing surfaces, and a low permeability material layer is disposed in the isolation groove.

[0048] Furthermore, the thickness of the patterned soft magnetic material layer is 1–5 cm.

[0049] Furthermore, the depth of the isolation groove is 5-10 μm.

[0050] Furthermore, the radial cross-sectional area of ​​each of the patterned soft magnetic material layers gradually decreases in the direction away from the magnetic generation layer.

[0051] Furthermore, the axial cross-section of each of the patterned soft magnetic material layers is trapezoidal.

[0052] Furthermore, the radial cross-sectional area of ​​the isolation groove gradually increases in the direction away from the magnetic generation layer.

[0053] Furthermore, the axial cross-section of each of the isolation grooves is triangular.

[0054] Furthermore, the surface of the low permeability material layer is flush with the surface of the patterned soft magnetic material layer.

[0055] Furthermore, the material of the low magnetic permeability layer includes resin.

[0056] Furthermore, the magnetic connection layer is made of a high-permeability alloy containing at least one of iron, cobalt, and nickel.

[0057] Furthermore, the patterned soft magnetic material layer has high permeability and magnetic induction intensity, while the area or magnetic loss of the hysteresis loop is small. The material of the patterned soft magnetic material layer includes ferrite, iron-silicon alloy or iron-silicon-aluminum alloy, etc.

[0058] In some more specific implementations, the magnetic assembly microdevice transfer assembly method includes:

[0059] First, an adhesive layer is disposed on the microdevice, and then the magnetic connection layer is disposed on the adhesive layer. The magnetic connection layer is fixed on the microdevice by the adhesive layer, thereby forming a temporary transfer microdevice. The fixed bonding state between the adhesive layer and the microdevice can be released.

[0060] Furthermore, the magnetic bonding layer is separated and removed from the microdevice by releasing the fixed bond between the adhesive layer and the microdevice.

[0061] Furthermore, the adhesive layer is made of hot melt adhesive material, and the magnetic assembly microdevice transfer assembly method specifically includes: heating the adhesive layer to reduce its stickiness, thereby separating the adhesive layer from the magnetic connection layer and the microdevice;

[0062] Alternatively, the adhesive layer is made of a thermally decomposable material, and the magnetic assembly microdevice transfer assembly method specifically includes: heating the adhesive layer to above its thermal decomposition temperature so that the adhesive layer thermally decomposes and loses its adhesiveness, and the adhesive layer separates from the magnetic connection layer and the microdevice;

[0063] Alternatively, the adhesive layer may be made of photosensitive adhesive, and the magnetic assembly microdevice transfer assembly method may specifically include: heating the adhesive layer to melt it and cause it to lose its adhesiveness, thereby separating the adhesive layer from the magnetic connection layer and the microdevice.

[0064] Alternatively, the adhesive layer may be made of a high-temperature resistant material that is soluble in a specific liquid. The magnetic assembly microdevice transfer assembly method may specifically include: contacting the adhesive layer with a specific liquid to dissolve the adhesive layer in the specific liquid, thereby separating the adhesive layer from the magnetic connection layer and the microdevice.

[0065] Furthermore, the adhesive layer is made of strontium aluminate, and the specific liquid is water.

[0066] Furthermore, the microdevice is a vertical structure device, and the microdevice also includes an intermediate substrate. The vertical structure device is electrically connected to the intermediate substrate. The magnetic assembly microdevice transfer assembly method specifically includes:

[0067] An adhesive layer is disposed on the intermediate substrate to fix the magnetic connection layer on the intermediate substrate.

[0068] Furthermore, the microdevice is a flip-chip structure device, and the magnetic assembly microdevice transfer assembly method specifically includes: setting an adhesive layer on the flip-chip structure device, and fixing the magnetic connection layer on the flip-chip structure device with the adhesive layer.

[0069] Furthermore, the magnetic generating layer includes a magnetic device and a magnetic adjustment mechanism, the magnetic adjustment mechanism cooperating with the magnetic device and at least used to adjust the magnetic attraction between the magnetic device and the magnetic connection layer.

[0070] Furthermore, the magnetic device includes a permanent magnet, the magnetic adjustment mechanism includes a movable platform, and the magnetic assembly microdevice transfer assembly method specifically includes: driving the permanent magnet to move along a selected direction by the movable platform, and changing the magnetic attraction between the magnetic device and the magnetic connection layer by at least adjusting the distance between the permanent magnet and the temporary transfer microdevice, so that the magnetic platform and the temporary transfer microdevice are magnetically attracted or retracted.

[0071] Alternatively, the magnetic device includes an electromagnet, and the magnetic adjustment mechanism includes a control circuit. The control circuit is electrically connected to the coil of the electromagnet. The magnetic assembly microdevice transfer assembly method specifically includes: adjusting the magnitude and / or direction of the current in the coil contained in the electromagnet using the control circuit to change the direction of the magnetic field or to turn the electromagnet on or off, thereby changing the magnetic attraction between the magnetic device and the magnetic connection layer, so that the magnetic platform and the temporary transfer microdevice are magnetically attracted or retracted.

[0072] Specifically, after the adhesive layer is treated to lose its adhesiveness and the connected magnetic bonding layers detach from the adhesive layer, the detached magnetic bonding layers are recycled.

[0073] In one specific implementation, a magnetic assembly microdevice transfer assembly method may include the following steps:

[0074] S1.a: Providing temporary transfer microdevices: The magnetic connection layer is connected to the microdevice through the adhesive layer to form temporary transfer microdevices;

[0075] S1.b: Provide a support substrate: at least one fixing area and a circuit wiring layer are formed on the support substrate body;

[0076] S1.c: Providing a magnetic platform: The magnetic platform includes a magnetic generating layer and a patterned soft magnetic material layer sequentially disposed along a first direction;

[0077] S2: Magnetic Assembly: Using a magnetic generation layer to magnetically connect temporary transfer microdevices to a magnetic platform;

[0078] S3: Temporary transfer microdevice bonding to the support substrate: The moving magnetic platform precisely aligns the microdevice in the temporary transfer microdevice with the fixed area of ​​the support substrate and places it in the fixed area for electrical connection.

[0079] S4: Demagnetization: Adjust the magnetic generation layer of the magnetic platform to make the magnetic platform lose its magnetic connection with the temporary transfer microdevice, and then remove the magnetic platform;

[0080] S5: Demagnetizing bonding layer: The adhesive layer is treated to make it lose its stickiness and remove residual adhesive. The connected magnetic bonding layer detaches from the adhesive layer.

[0081] Further, step S1.a specifically includes: forming a first electrode and a second electrode on both sides of the epitaxial structure of the vertical microdevice, forming a first conductive layer and a second conductive layer on one side of the electrical surface of the intermediate substrate, electrically bonding a solder layer on the first conductive layer and the second conductive layer, electrically connecting the first electrode of the epitaxial structure of the vertical microdevice to the first conductive layer on the intermediate substrate, and then bonding the magnetic connection layer to the back plate of the intermediate substrate through an adhesive layer to form a temporary transfer microdevice; or, forming a first electrode and a second electrode on one side of the electrical surface of the epitaxial structure of the flip-chip microdevice, and bonding the magnetic connection layer to the back plate of the flip-chip microdevice through an adhesive layer to form a temporary transfer microdevice.

[0082] It should be noted that the magnetic connection layer in this invention is not covered on the electrode by sputtering or deposition, but is connected to the microdevice by the adhesion of the adhesive layer. Specifically, the magnetic connection layer can be diced first and then bonded to the microdevice, or the entire magnetic connection layer can be directly bonded to the microdevice wafer and then diced.

[0083] Furthermore, step S1.b specifically includes: forming at least one fixed area, a first circuit wiring layer and a second circuit wiring layer on the support substrate body, each fixed area can accommodate a vertical structure microdevice, wherein the first circuit wiring layer will be electrically connected to the second conductive layer on the intermediate substrate for temporary transfer of the microdevice, and the second circuit wiring layer is disposed in the fixed area and will be electrically connected to the second electrode of the vertical structure microdevice.

[0084] Alternatively, at least one fixed area and a circuit wiring layer can be formed on the support substrate body. Each fixed area can accommodate a flip-chip microdevice. The circuit wiring layer is disposed in the fixed area and electrically connected to the first electrode and the second electrode of the flip-chip microdevice.

[0085] Compared with the prior art, the advantages of the present invention include:

[0086] 1) The present invention provides a magnetic assembly microdevice transfer assembly structure and transfer assembly method, which achieves selective magnetic attraction or retraction of magnetic microdevices by using a patterned soft magnetic material layer in conjunction with a magnetic generation layer. It can complete the selective transfer of RGB three-color modules and subsequent yield detection and repair work. Compared with the existing magnetic assembly method, its structure has low manufacturing cost and simple manufacturing method, and can also effectively avoid the crosstalk problem in magnetic assembly.

[0087] 2) The present invention provides a magnetic assembly microdevice transfer assembly structure and transfer assembly method, which eliminates the influence of regional non-uniformity inherited from the epitaxial layer on the display effect after transfer caused by the relative position of the device determined by the relative position on the epitaxial layer in conventional mass transfer through the random grasping method of magnetic assembly;

[0088] 3) The present invention provides a magnetic assembly microdevice transfer assembly structure and transfer assembly method, which can eliminate the influence of the magnetic material layer on the microdevices after mass transfer by operating the demagnetizing material layer. Attached Figure Description

[0089] Figure 1a This is a cross-sectional structural schematic diagram of the vertical structure microdevice in Embodiment 1 of the present invention;

[0090] Figure 1b This is a schematic cross-sectional view of the intermediate substrate in Embodiment 1 of the present invention;

[0091] Figure 1c This is a cross-sectional structural schematic diagram of a magnetic temporary microdevice composed of a magnetic connection layer, an adhesive layer, an intermediate substrate, and a vertical structure microdevice in Embodiment 1 of the present invention.

[0092] Figure 1d This is a partial cross-sectional structural diagram of the supporting substrate in Embodiment 1 of the present invention;

[0093] Figure 1e This is a partial cross-sectional structural diagram of the magnetic platform in Embodiment 1 of the present invention;

[0094] Figure 1f This is a partial cross-sectional schematic diagram of the magnetic platform after magnetic connection with the temporary magnetic microdevice in Embodiment 1 of the present invention;

[0095] Figure 1gThis is a partial cross-sectional schematic diagram of the bonding between the magnetic temporary microdevice and the support substrate in Embodiment 1 of the present invention;

[0096] Figure 1h This is a bottom view of the magnetic temporary microdevice in Embodiment 1 of the present invention;

[0097] Figure 1i This is a top view of the supporting substrate structure in Embodiment 1 of the present invention;

[0098] Figure 2a This is a cross-sectional view of the flip-chip microdevice in Embodiment 2 of the present invention;

[0099] Figure 2b This is a schematic cross-sectional view of the magnetic temporary microdevice composed of a magnetic connection layer, an adhesive layer, and a flip-chip structure microdevice in Embodiment 2 of the present invention.

[0100] Figure 2c This is a partial cross-sectional view of the supporting substrate in Embodiment 2 of the present invention;

[0101] Figure 2d This is a partial cross-sectional structural diagram of the magnetic platform in Embodiment 2 of the present invention;

[0102] Figure 2e This is a partial cross-sectional schematic diagram of the magnetic platform after magnetic connection with the temporary magnetic microdevice in Embodiment 2 of the present invention;

[0103] Figure 2f This is a partial cross-sectional schematic diagram of the bonding between the magnetic temporary microdevice and the supporting substrate in Embodiment 2 of the present invention;

[0104] Figure 2g This is a bottom view of the structure of the magnetic temporary microdevice in Embodiment 2 of the present invention;

[0105] Figure 2h This is a top view of the supporting substrate structure in Embodiment 2 of the present invention. Detailed Implementation

[0106] In view of the shortcomings of the prior art, the inventors of this invention, through long-term research and extensive practice, have proposed the technical solution of this invention. The following will further explain and illustrate this technical solution, its implementation process, and its principles.

[0107] The microdevices in this invention are devices with micro-nano scales, such as Micro-LED chips.

[0108] This invention provides a magnetic assembly structure and method for transferring and assembling microdevices. It utilizes magnetic force to precisely pick up and attract microdevices such as Micro-LED chips, and then aligns and brings the Micro-LED chips into contact with a receiving substrate via a magnetic platform, thereby completing mass transfer. This mass transfer technology not only boasts advantages such as high transfer accuracy and high transfer speed, but also allows for selective transfer of RGB colors through magnetic selection. Subsequent yield testing and repair can also be performed using the magnetic module. Therefore, magnetic assembly mass transfer technology is a highly promising technology.

[0109] The present invention provides a magnetic assembly structure and method for transferring and assembling microdevices. Utilizing the advantages of magnetic assembly, compared with other mass transfer methods, it achieves selective adsorption or retraction of magnetically attached chips by using a designed magnetic platform and magnetic attraction structure, thus completing the selection of RGB three-color modules and yield testing and repair. Compared with other magnetic assembly methods, the present invention can also selectively demagnetize materials, effectively eliminating the influence of magnetism on the device.

[0110] In this invention, selective transfer of RGB colors is achieved using three different patterned soft magnetic material layers. For soft magnetic material R, only the red LED transfer area is etched; for soft magnetic material G, only the green LED transfer area is etched; and for soft magnetic material B, only the blue LED transfer area is etched. Generally, in full-color LED displays, the layout can also be designed with equidistant RGB colors. Therefore, only one patterned soft magnetic material layer is needed for three transfers to achieve RGB color transfer.

[0111] The following will further explain the technical solution, its implementation process and principle in conjunction with the accompanying drawings and specific implementation examples. Unless otherwise specified, the microdevices, intermediate substrates, conductive layers, circuit wiring layers, support substrates, magnetic devices and related reagents and medicines involved in the embodiments of the present invention are all known to those skilled in the art. The processing technology of the electronic devices used in the embodiments of the present invention are all known to those skilled in the art, and their specific process parameters are not limited or described here.

[0112] Example 1

[0113] A magnetic assembly microdevice transfer assembly structure and a corresponding transfer and assembly method.

[0114] Please see Figures 1a-1i , Figures 1a-1i The diagram shows the components and overall structure of a magnetically assembled microdevice transfer structure provided in Embodiment 1. Figure 1a This is a cross-sectional schematic diagram of a vertical structure microdevice, which includes a vertical structure microdevice body 101, a first electrode 102, and a second electrode 103. Figure 1b This is a cross-sectional structural diagram of an intermediate substrate. The intermediate substrate includes an intermediate substrate body 201, a first conductive layer 202, a second conductive layer 203, and a solder layer 204 electrically bonded to the first conductive layer 202 and the second conductive layer 203. Figure 1c It is a cross-sectional schematic diagram of a temporary transfer microdevice formed by connecting a magnetic connection layer, an adhesive layer, an intermediate substrate, and a vertical structure microdevice. The magnetic connection layer 206 is connected to the intermediate substrate through the adhesive layer 205. Figure 1d It is a cross-sectional structural diagram of the support substrate, including a support substrate body 301, a plurality of fixing areas 304 disposed on the support substrate body 301, a first circuit wiring layer 303 disposed around the fixing areas, a second circuit wiring layer 302 disposed at the bottom of the fixing areas, and a solder layer 305 electrically bonded to the second circuit wiring layer 302. Figure 1e This is a cross-sectional structural diagram of the magnetic platform, which includes a magnet 401, a magnetic adjustment mechanism 402, a patterned soft magnetic material layer 403, and a low magnetic permeability material layer 404. Figure 1f This is a partial cross-sectional schematic diagram of the magnetic platform after the temporary transfer of microdevices via magnetic connection. Figure 1g This is a partial cross-sectional schematic diagram of the bonding between the temporary transfer microdevice and the support substrate; Figure 1h This is a schematic diagram of the temporary transfer microdevice from a bottom view. Figure 1i This is a top view of the supporting substrate.

[0115] The following details the connection relationships between the various structures in this example:

[0116] Please see Figures 1a-1i A first electrode 102 and a second electrode 103 are respectively disposed on both sides of the epitaxial surface of the vertical structure microdevice body 101. A first conductive layer 202 and a second conductive layer 203 are respectively disposed on one side of the electrical surface of the intermediate substrate body 201. A solder layer 204 is electrically bonded to the first conductive layer 202 and the second conductive layer 203. A magnetic connection layer 206 is connected to the intermediate substrate body 201 through an adhesive layer 205. The second conductive layer 203 of the intermediate substrate is electrically connected to the first electrode 102 of the vertical structure microdevice through the solder layer 204 to form a temporary transfer microdevice.

[0117] A plurality of fixing regions 304 are arrayed on the support substrate body 301. Each fixing region 304 corresponds to each temporary transfer microdevice, and the size (mainly radial cross-sectional area) of the fixing region 304 is larger than the size of the vertical structure microdevice body 101 but smaller than the size of the intermediate substrate body 201. In addition, a first circuit wiring layer 303 is disposed around the fixing region 304 of the support substrate body 301, and a second circuit wiring layer 302 is disposed at the bottom of the fixing region 304. A solder layer 305 is electrically bonded to the second circuit wiring layer 302. The first circuit wiring layer 303 is electrically connected to the first conductive layer 202 of the intermediate substrate through the solder layer 204, and the second circuit wiring layer 302 is electrically connected to the second electrode 103 of the vertical structure microdevice through the solder layer 305.

[0118] The patterned soft magnetic material layer 403 can be obtained by etching a patterned soft magnetic material layer. The etched trenches are filled with a low magnetic permeability material layer 404. A magnet 401 and a magnetic adjustment mechanism 402 are provided on the patterned soft magnetic material layer 403. The magnetic adjustment mechanism 402 can control the magnet 401 to move closer to or further away from the patterned soft magnetic material layer 403 in the vertical direction (i.e., the first direction), thereby completing the magnetic attraction or retraction operation.

[0119] The vertical structure microdevice is a vertical structure Micro-LED chip, which is approximately cylindrical in shape. The diameter of the main body 101 of the vertical structure microdevice is 5μm. The diameter of the first electrode 102 is smaller than the diameter of the main body 101, with a diameter of 3μm. The diameter of the second electrode 103 is 5μm. The intermediate substrate body 201 is transparent glass. The first conductive layer 202 and the second conductive layer 203 disposed on the intermediate substrate body 201 are annular structures with inner and outer diameters of 12μm and 15μm, respectively. The second conductive layer 203 is approximately circular with a diameter of 3μm. Solder layers 204 are electrically bonded to the first and second conductive layers 203, and their shape and diameter correspond to those of the first and second conductive layers 202 and 203, respectively.

[0120] The fixing area 304 on the support substrate body 301 is an approximately cylindrical groove, the size of which corresponds to the vertical structure microdevice; the second circuit wiring layer 302 at the bottom of the fixing area 304 is approximately cylindrical with a diameter of 3μm; the first circuit wiring layer 303 around the fixing area 304 is approximately cylindrical with a diameter of 15μm; the shape and diameter of the solder layer 305 electrically bonded to the second circuit wiring layer 302 are consistent with the second circuit wiring layer 302; the magnet 401 in the magnetic platform can be made by magnetizing materials such as iron, cobalt, and nickel. For example, the patterned soft magnetic material layer can be made of iron-silicon alloys, iron-silicon-aluminum alloys, etc.

[0121] The following details the magnetic assembly microdevice transfer and assembly method of Embodiment 1 of the present invention.

[0122] Step S1. Fabricate a temporary transfer microdevice.

[0123] A. Fabrication of vertical structure microdevices.

[0124] The substrate of the vertical structure microdevice epitaxial wafer is peeled off by laser lift-off to obtain a vertical structure microdevice epitaxial structure array. The mesa distributed in an array is fabricated on the vertical structure microdevice epitaxial wafer by etching process. Then, multiple deep trenches are etched between each mesa to form isolation, thereby obtaining multiple vertical structure microdevice bodies 101 distributed in an array.

[0125] Then, a first electrode 102 is fabricated on the platform through processes such as evaporation and sputtering. The first electrode 102 is in contact with the p-type epitaxial layer of the vertical structure microdevice body 101. Then, a second electrode 103 is fabricated on the n-type epitaxial layer side of the vertical structure microdevice body 101 through processes such as evaporation and sputtering. The first electrode 102 and the second electrode 103 include a current diffusion layer and a bump under-metallization layer. The material of the current diffusion layer can be ITO, and the bump under-metallization layer can be a material such as Cr / Pt / Au that has good contact with the ITO current diffusion layer.

[0126] B. Preparation of intermediate substrate.

[0127] Transparent glass is selected as the intermediate substrate 201. Multiple mesa are etched in an array using an etching process. Then, a first conductive layer 202 and a second conductive layer 203 are prepared on the mesa of the transparent glass using processes such as evaporation and sputtering. These layers can be made of patternable transparent conductive thin film materials such as ITO.

[0128] Solder layer 204 is prepared on first conductive layer 202 and second conductive layer 203 using processes such as vapor deposition and sputtering. Solder layer 204 may include a metallization layer under the bump and a metal bump layer. The material of the metallization layer under the bump can be a material such as Cr / Pt / Au that has good contact with the ITO current diffusion layer. The metal bump layer can be selected from solder bumps such as AuSn, SnAg, SnAgCu, InSn, or Au bumps, Cu bumps, etc.

[0129] C. Intermediate substrates are connected to vertical structure microdevices to form microdevices.

[0130] The vertical structure microdevice is moved above the second conductive layer 203 of the intermediate substrate, so that the first electrode 102 of the vertical structure microdevice and the solder layer 204 on the second conductive layer 203 of the intermediate substrate are aligned. Then the vertical structure microdevice is placed down so that the first electrode 102 of the vertical structure microdevice and the solder layer 204 on the second conductive layer 203 of the intermediate substrate are in contact. Then, it is heated and soldered to form an electrical connection.

[0131] D. The magnetic connection layer 206 is connected to the intermediate substrate of the microdevice through the adhesive layer 205 to form a temporary transfer microdevice.

[0132] The adhesive layer 205 is made of hot melt adhesive. By heating the adhesive layer 205 to its melting point and then cooling it to solidify, the magnetic connection layer 206 is bonded to the backplate of the interposer substrate 201 to form a temporary transfer microdevice. Figure 1h This is a bottom-view schematic diagram of a temporary transfer of microdevices.

[0133] Step S2. Fabrication of the support substrate

[0134] The support substrate body 301 is a silicon substrate. Multiple fixing regions 304 are prepared on the support substrate body 301 using an etching process. The depth of the fixing regions 304 is approximately the same as the thickness of each vertical structure microdevice, about 5 μm. A first circuit wiring layer 303 is deposited around the fixing regions 304, and a second circuit wiring layer 302 is deposited at the bottom of the fixing regions 304. A solder layer 305 is prepared on the surface of the second circuit wiring layer 302 using a process such as vapor deposition. An oxide insulating layer (not shown) is deposited on the first circuit wiring layer 303 and the second circuit wiring layer 302, and an opening for connection with the temporary transfer microdevice is etched. The above steps avoid short circuits caused by solder flow in subsequent soldering processes. Figure 1i This is a top view of the substrate.

[0135] Step S3. Create a magnetic platform.

[0136] Patterned soft magnetic material layer 403 is obtained by patterning and etching the magnetic surface of the patterned soft magnetic material layer. Only the patterned soft magnetic material layer corresponding to the center of the magnet is etched because the uniformity of the magnet edge is poor and the edge position transfer yield is low. Then, the grooves left after etching are filled with a low permeability material.

[0137] A magnetic adjustment mechanism 402 and a magnet 401 are provided above the patterned soft magnetic material layer 403. The magnetic adjustment mechanism 402 can control the magnet 401 to move closer to or further away from the patterned soft magnetic material layer in the vertical direction, thereby completing the magnetic attraction or retraction process.

[0138] Step S4. Magnetic assembly.

[0139] The moving magnetic platform approaches the temporary transfer microdevice and moves the magnetic adjustment mechanism 402 in the vertical direction, so that the magnetic lines of force generated by the magnet 401 are sufficient to pass through the patterned soft magnetic material layer 403, so that the temporary transfer microdevice and the magnetic platform can be magnetically connected.

[0140] Step S5. Temporarily transfer the microdevice to the support substrate for bonding.

[0141] The magnetic platform with the temporarily transferred microdevice magnetically connected is moved, and the temporarily transferred microdevice is precisely placed in the fixed area 304 of the support substrate according to the alignment marks. The first conductive layer 202 of the intermediate substrate and the first circuit wiring layer 303 of the support substrate are electrically connected through the solder layer 204 by reflow soldering or thermoforming. The second electrode 103 of the vertical structure microdevice is electrically connected to the second circuit wiring layer 302 of the support substrate through the solder layer 305.

[0142] Step S6. Demagnetizing connection and demagnetizing connection layer.

[0143] The moving magnetic adjustment mechanism 402 moves the magnet 401 away from the patterned soft magnetic material layer 403, causing the magnetic platform to lose its magnetic connection with the temporary transfer microdevice. Then the magnetic platform is removed, completing the demagnetization connection.

[0144] In the temporary transfer microdevice, the adhesive layer 205 is a hot melt adhesive. The hot melt adhesive material is melted by heating it to a temperature higher than the melting point of the hot melt adhesive, causing the magnetic connection layer 206 to lose its connection with the intermediate substrate. The magnet or magnetic platform is moved to magnetically detach it from the magnetic connection layer 206, thus completing the demagnetization of the connection layer and the transfer assembly of the magnetically assembled microdevice.

[0145] Example 2

[0146] Please see Figures 2a-2h , Figures 2a-2h The diagram shows the components and overall structure of a magnetically assembled microdevice transfer structure provided in Embodiment 2. Figure 2a This is a cross-sectional view of a flip-chip microdevice, which includes a flip-chip microdevice body 111, a first electrode 112, and a second electrode 113. Figure 2b This is a schematic diagram of the cross-sectional structure of a temporary transfer microdevice formed by connecting a magnetic connection layer, an adhesive layer, and a flip-chip structure microdevice. Figure 2c This is a cross-sectional structural diagram of the support substrate. The support substrate includes a support substrate body 311. The support substrate body 311 has several fixing areas 314. The bottom of the fixing area 314 is provided with a first circuit wiring layer 312 and a second circuit wiring layer 313, as well as a solder layer 315 electrically bonded to the first circuit wiring layer 312 and the second circuit wiring layer 313. Figure 2dThis is a cross-sectional structural diagram of the magnetic platform, which includes an electromagnet 411, a control circuit 412, a patterned soft magnetic material layer 413, and a low permeability material layer 414. Figure 2e This is a cross-sectional schematic diagram of the magnetic platform after the temporary transfer of microdevices via magnetic connection. Figure 2f This is a cross-sectional schematic diagram of the temporary transfer microdevice bonding to the substrate; Figure 2g This is a bottom-view schematic diagram of the temporary transfer microdevice structure in Embodiment 2 of the present invention; Figure 2h This is a top view of the substrate structure in Embodiment 2 of the present invention. In both the first circuit wiring layer 312 and the second circuit wiring layer 313, only the contact electrodes are located at the bottom of the fixed area 314, and the remaining wiring layers are deposited with passivation layers for insulation.

[0147] The following details the connection relationships between the various structures in this example.

[0148] Please see Figures 2a-2f The flip-chip microdevice body 111 has a first electrode 112 and a second electrode 113 on its epitaxial side, wherein the first electrode 112 serves as the anode of the flip-chip microdevice and the second electrode 113 serves as the cathode of the flip-chip microdevice; the magnetic connection layer 115 is connected to the flip-chip microdevice body 111 through the adhesive layer 114 to form a temporary transfer microdevice.

[0149] The supporting substrate body 311 has an array of fixed areas 314, each fixed area 314 being larger than the size of the flip-chip microdevice body 111. In addition, the bottom of the fixed areas 314 is provided with a first circuit wiring layer 312 and a second circuit wiring layer 313, and a solder layer 305 is electrically bonded to the first circuit wiring layer 312 and the second circuit wiring layer 313. The first circuit wiring layer 312 is electrically connected to the first electrode 112 of the flip-chip microdevice through the solder layer 315, and the second circuit wiring layer 313 is electrically connected to the second electrode 313 of the flip-chip microdevice through the solder layer 315.

[0150] The patterned soft magnetic material layer 413 is obtained by etching the patterned soft magnetic material layer. The etched trenches are filled with a low permeability material layer 414. An electromagnet 411 and a control circuit 412 are provided on the patterned soft magnetic material layer 413. The control circuit 412 controls the magnetic field of the electromagnet 411 by controlling the switching of the current in the coil of the electromagnet 411, thereby enabling the magnetic platform to perform magnetic attraction or retraction operations.

[0151] Specifically, the flip-chip microdevice is a flip-chip Micro-LED chip, which is approximately cylindrical in shape. The diameter of the main body 111 of the flip-chip microdevice is 10μm. The first electrode 112 is approximately circular in shape with a diameter of 3μm. The second electrode 113 is annular with an inner diameter of 6μm and an outer diameter of 9μm.

[0152] The fixing area 314 on the supporting substrate body 311 is approximately circular in shape and larger than the size of the flip-chip microdevice. The first circuit wiring layer 312 at the bottom of the fixing area is approximately circular with a diameter of 3μm. The second circuit wiring layer is approximately annular with an inner diameter of 6μm and an outer diameter of 9μm. The solder layer 315, which is electrically bonded to the first circuit wiring layer 312 and the second circuit wiring layer 313, is also approximately circular in shape and has a size of 3μm, and is basically the same as the first circuit wiring layer 312 and the second circuit wiring layer 313. The core of the electromagnet 411 in the magnetic platform can be made of pure iron, and the patterned soft magnetic material layer can be made of iron-silicon alloy, iron-silicon-aluminum alloy, etc.

[0153] The following details the magnetic assembly microdevice transfer and assembly method of Embodiment 2 of the present invention.

[0154] Step S1. Fabricate a temporary transfer microdevice.

[0155] A. Fabrication of flip-chip microdevices.

[0156] First, multiple arrayed mesa are fabricated on the epitaxial wafer of the flip-chip microdevice (i.e., the flip-chip microdevice body) using an etching process. Then, multiple deep trenches are etched between each mesa to form isolation, thereby obtaining multiple arrayed flip-chip microdevice bodies 111.

[0157] Then, a first electrode 112 and a second electrode 113 are fabricated on the platform through processes such as evaporation and sputtering. The first electrode 112 is in contact with the p-type epitaxial layer of the flip-chip microdevice body 111, and the second electrode 113 is in contact with the n-type epitaxial layer of the flip-chip microdevice body 111. The first electrode 112 and the second electrode 113 include a current diffusion layer and a bump under-metallization layer. The current diffusion layer can be made of ITO, and the bump under-metallization layer can be made of materials such as Cr / Pt / Au that have good contact with the ITO current diffusion layer.

[0158] B. The magnetic connection layer 115 is connected to the flip-chip microdevice through the adhesive layer 114 to form a temporary transfer microdevice.

[0159] The adhesive layer 114 is made of a thermolytic adhesive, which is melted by heating to a melting temperature (but not exceeding the thermolytic decomposition temperature) and then cooled and solidified. This allows the magnetic connection layer 115 to bond with the flip-chip microdevice through the adhesive layer 114, forming a temporary transfer microdevice. Figure 2f This is a bottom-view schematic diagram of a temporary transfer of microdevices.

[0160] Step S2. Fabricate the support substrate.

[0161] The support substrate body 311 is a silicon substrate. Multiple fixing regions 314 are prepared on the support substrate body 311 using an etching process. The purpose is to block side light transmission. The depth of the fixing region 314 is approximately the same as the thickness of each flip-chip microdevice, about 5 μm.

[0162] A first circuit wiring layer 312 and a second circuit wiring layer 313 are deposited at the bottom of the fixed area 314. A solder layer 315 is formed on the surface of the first circuit wiring layer 312 and the second circuit wiring layer 313 using a process such as vapor deposition. An oxide insulating layer (not shown) is deposited on the first circuit wiring layer 312 and the second circuit wiring layer 313, and an opening for connection with the temporary transfer microdevice is etched out. The above approach avoids short circuits caused by solder flow in subsequent soldering processes.

[0163] Step S3. Create a magnetic platform.

[0164] Patterned soft magnetic material layer 413 is obtained by patterning and etching the magnetic attraction surface of the patterned soft magnetic material layer, and the grooves left after etching are filled with a low magnetic permeability material.

[0165] At least one electromagnet 411 and a control circuit 412 are disposed on the patterned soft magnetic material layer 413. The core of the electromagnet is made of pure iron material, and the coil is made of copper material and wound around the outer surface of the core in a spiral manner according to a specified number of turns. The two ends of the coil are connected to the control circuit 412. The control circuit 412 controls the magnetic field generated by the electromagnet 411 by controlling the current of the coil of the electromagnet 411, thereby completing the magnetic attraction or retraction process.

[0166] Step S4. Magnetic assembly.

[0167] The moving magnetic platform approaches the temporary transfer microdevice and adjusts the control circuit 412, causing the electromagnet 411 to generate a magnetic field. The generated magnetic lines of force pass through the patterned soft magnetic material layer 413, enabling the temporary transfer microdevice to complete a magnetic connection with the magnetic platform.

[0168] Step S5. Temporarily transfer the microdevice to the support substrate for bonding.

[0169] The magnetic platform with the temporarily transferred microdevice magnetically connected is moved, and the temporarily transferred microdevice is precisely placed in the fixed area 314 according to the alignment marks. The first electrode 112 of the flip-chip microdevice is electrically connected to the first circuit wiring layer 312 of the supporting substrate through the solder layer 315 by reflow soldering or thermoforming. The second electrode 113 of the flip-chip microdevice is electrically connected to the second circuit wiring layer 313 of the supporting substrate through the solder layer 315.

[0170] Step S6. Demagnetizing connection and demagnetizing connection layer.

[0171] The control circuit 412 is adjusted to turn off the current in the coil of electromagnet 411, so that the magnetic platform loses its magnetic connection with the temporary transfer microdevice. Then the magnetic platform is removed to complete the demagnetization connection.

[0172] In the temporary transfer microdevice, the adhesive layer 114 is a thermally decomposable adhesive. The thermally decomposable adhesive material is thermally decomposed by heating it to a temperature higher than the thermal decomposition point of the thermally decomposable adhesive, causing the magnetic connection layer 115 to lose connection with the flip-chip microdevice. The magnetic connection layer 115 is magnetically detached by moving the magnet or magnetic platform, thus completing the demagnetization of the connection layer and completing the transfer assembly of the magnetically assembled microdevice in Example 2.

[0173] Example 3

[0174] Example 3 provides a magnetic assembly microdevice transfer structure and corresponding transfer and assembly method that are basically the same as the device structure and fabrication method in Example 1 / Example 2, except that:

[0175] In Example 3, the adhesive layer material is photosensitive adhesive. The adhesive layer can be cured by ultraviolet light irradiation to combine the magnetic connection layer with the microdevice to form a temporary transfer microdevice. In the demagnetizing connection layer step, the photosensitive adhesive is melted and loses its adhesiveness by heating it to a temperature higher than the melting point of the photosensitive adhesive. Then, the magnetic connection layer is magnetically detached by moving a magnet or magnetic platform to complete the demagnetizing connection layer. Specifically, the photosensitive adhesive can be photosensitive resin.

[0176] Example 4

[0177] Example 4 provides a magnetic assembly microdevice transfer structure and corresponding transfer and assembly method that are basically the same as the device structure and fabrication method in Example 1 / Example 2, except that:

[0178] In Example 4, the adhesive layer material is a high-temperature resistant material that is soluble in a specific liquid. The adhesive layer is formed by heating and curing the material dissolved in the specific liquid to bond the magnetic connection layer and the microdevice, creating a temporary transfer microdevice. In the demagnetizing connection layer step, the adhesive layer material is dissolved and loses its adhesiveness by immersing the device in the specific liquid. Then, a magnet or magnetic platform is moved to magnetically detach the magnetic connection layer, completing the demagnetizing connection layer process. Specifically, the high-temperature resistant material that is soluble in the specific liquid can be strontium aluminate.

[0179] It should be understood that the above embodiments are merely illustrative of the technical concept and features of the present invention, and are intended to enable those skilled in the art to understand the content of the present invention and implement it accordingly. They should not be construed as limiting the scope of protection of the present invention. All equivalent changes or modifications made in accordance with the spirit and essence of the present invention should be covered within the scope of protection of the present invention.

Claims

1. A magnetic assembly microdevice transfer assembly structure, characterized in that, include: A temporary transfer microdevice with micro / nano scale includes a microdevice and a magnetic connection layer, wherein the magnetic connection layer is detachably fixed to the microdevice; A magnetic platform includes a magnetic generating layer and a patterned soft magnetic material layer stacked sequentially along a first direction. The magnetic generating layer is at least used to provide an adjustable magnetic field. The magnetic generating layer and the magnetic connection layer located within the magnetic field are magnetically attracted. The patterned soft magnetic material layer is at least used to guide magnetic lines of force in the magnetic field, so that temporary transfer microdevices with micro / nano scales can be magnetically attracted and fixed on the magnetic platform, or, so that temporary transfer microdevices with micro / nano scales can detach from the magnetic platform.

2. The magnetic assembly microdevice transfer assembly structure according to claim 1, characterized in that: The patterned soft magnetic material layer has a plurality of attraction and fixing surfaces spaced apart along a second direction. Adjacent attraction and fixing surfaces are isolated by a low permeability material layer. Each attraction and fixing surface corresponds to a temporary transfer microdevice. The second direction intersects with the first direction.

3. The magnetic assembly microdevice transfer assembly structure according to claim 2, characterized in that: The attraction fixing surface is parallel to the bottom surface of the magnetic generation layer.

4. The magnetic assembly microdevice transfer assembly structure according to claim 2, characterized in that: The patterned soft magnetic material layer includes a plurality of patterned soft magnetic material layers spaced apart along a second direction. Adjacent patterned soft magnetic material layers are separated by a low permeability material layer. Each patterned soft magnetic material layer has an attraction and fixing surface. Alternatively, the patterned soft magnetic material layer includes a single patterned soft magnetic material layer. The surface of the patterned soft magnetic material layer has a plurality of isolation grooves spaced apart along the second direction. The plurality of isolation grooves divide the surface of the patterned soft magnetic material layer to form a plurality of attraction and fixing surfaces. A low permeability material layer is disposed within the isolation grooves.

5. The magnetic assembly microdevice transfer assembly structure according to claim 4, characterized in that: The thickness of the patterned soft magnetic material layer is 1cm to 5cm.

6. The magnetic assembly microdevice transfer assembly structure according to claim 4, characterized in that: The depth of the isolation groove is 5μm to 10μm.

7. The magnetic assembly microdevice transfer assembly structure according to claim 4, characterized in that: The radial cross-sectional area of ​​each of the patterned soft magnetic material layers gradually decreases in the direction away from the magnetic generation layer.

8. The magnetic assembly microdevice transfer assembly structure according to claim 7, characterized in that: The axial cross-section of each of the patterned soft magnetic material layers is trapezoidal.

9. The magnetic assembly microdevice transfer assembly structure according to claim 4, characterized in that: The radial cross-sectional area of ​​the isolation groove gradually increases in the direction away from the magnetic generation layer.

10. The magnetic assembly microdevice transfer assembly structure according to claim 9, characterized in that: The axial cross-section of each of the isolation grooves is triangular.

11. The magnetic assembly microdevice transfer assembly structure according to claim 4, characterized in that: The surface of the low permeability material layer is flush with the surface of the patterned soft magnetic material layer.

12. The magnetic assembly microdevice transfer assembly structure according to claim 4, characterized in that: The material of the low magnetic permeability layer includes resin.

13. The magnetic assembly microdevice transfer assembly structure according to claim 1 or 2, characterized in that: The magnetic connection layer is made of an alloy containing at least one of iron, cobalt, and nickel.

14. The magnetic assembly microdevice transfer assembly structure according to claim 13, characterized in that: The patterned soft magnetic material layer is made of ferrite, iron-silicon alloy, or iron-silicon-aluminum alloy.

15. The magnetic assembly microdevice transfer assembly structure according to claim 1, characterized in that: The microdevice is a vertical structure device, and the microdevice further includes an intermediate substrate, the vertical structure device is electrically connected to the intermediate substrate, and the magnetic connection layer is detachably fixed on the intermediate substrate; Alternatively, the microdevice may be a flip-chip device, and the magnetic connection layer may be detachably fixed to the flip-chip device.

16. The magnetic assembly microdevice transfer assembly structure according to claim 1 or 15, characterized in that: The temporary transfer microdevice also includes an adhesive layer, through which the magnetic connection layer is fixed to the microdevice, and the fixed bond between the adhesive layer and the microdevice can be released, thereby separating the magnetic connection layer from the microdevice.

17. The magnetic assembly microdevice transfer assembly structure according to claim 16, characterized in that: The adhesive layer is made of hot melt adhesive, the adhesiveness of which decreases with increasing temperature; or, the adhesive layer is made of thermally decomposable material, which decomposes and loses its adhesiveness after exceeding the thermal decomposition temperature; or, the adhesive layer is made of photosensitive adhesive, which is cured by ultraviolet light and melts and loses its adhesiveness after heating; or, the adhesive layer is made of strontium aluminate.

18. The magnetic assembly microdevice transfer assembly structure according to claim 1, characterized in that: The magnetic generating layer includes a magnetic device and a magnetic adjustment mechanism. The magnetic adjustment mechanism cooperates with the magnetic device and is used at least to adjust the magnetic attraction between the magnetic device and the magnetic connection layer.

19. The magnetic assembly microdevice transfer assembly structure according to claim 18, characterized in that: The magnetic device includes a permanent magnet, and the magnetic adjustment mechanism includes a movable platform for driving the permanent magnet to move in a selected direction, and for changing the magnetic attraction between the magnetic device and the magnetic connection layer, at least by adjusting the distance between the permanent magnet and the temporary transfer microdevice. Alternatively, the magnetic device includes an electromagnet, and the magnetic adjustment mechanism includes a control circuit electrically connected to a coil of the electromagnet, and alters the magnetic attraction between the magnetic device and the magnetic connection layer by adjusting the magnitude and / or direction of the current in the coil.

20. A method for transferring and assembling magnetically assembled microdevices, characterized in that... include: A microdevice is provided, on which a magnetic connection layer is disposed, thereby forming a temporary transfer microdevice; A magnetic platform is provided, the magnetic platform comprising a magnetic generating layer and a patterned soft magnetic material layer stacked sequentially along a first direction, the magnetic generating layer being used at least to provide an adjustable magnetic field, and the patterned soft magnetic material layer being used at least to guide magnetic field lines in the magnetic field; Furthermore, the patterned soft magnetic material layer is positioned between the magnetic generating layer and the magnetic connection layer, and the magnetic field is adjusted so that the magnetic platform magnetically attracts and fixes the temporary transfer microdevice. The temporary transfer microdevice is transferred onto the support substrate, and the temporary transfer microdevice is electrically connected to the support substrate. By readjusting the magnetic field, the temporary transfer microdevice is detached from the magnetic platform; Remove the magnetic connection layer of the temporary transfer microdevice.

21. The magnetic assembly microdevice transfer and assembly method according to claim 20, characterized in that: The patterned soft magnetic material layer has a plurality of attraction and fixing surfaces spaced apart along a second direction. Adjacent attraction and fixing surfaces are isolated by a low permeability material layer. Each attraction and fixing surface corresponds to a temporary transfer microdevice. The second direction intersects with the first direction.

22. The magnetic assembly microdevice transfer and assembly method according to claim 21, characterized in that: The attraction fixing surface is parallel to the bottom surface of the magnetic generation layer.

23. The magnetic assembly microdevice transfer and assembly method according to claim 21, characterized in that: The patterned soft magnetic material layer includes a plurality of patterned soft magnetic material layers spaced apart along a second direction. Adjacent patterned soft magnetic material layers are separated by a low permeability material layer. Each patterned soft magnetic material layer has an attraction and fixing surface. Alternatively, the patterned soft magnetic material layer includes a single patterned soft magnetic material layer. The surface of the patterned soft magnetic material layer has a plurality of isolation grooves spaced apart along the second direction. The plurality of isolation grooves divide the surface of the patterned soft magnetic material layer to form a plurality of attraction and fixing surfaces. A low permeability material layer is disposed within the isolation grooves.

24. The magnetic assembly microdevice transfer and assembly method according to claim 23, characterized in that: The thickness of the patterned soft magnetic material layer is 1 cm to 5 cm.

25. The magnetic assembly microdevice transfer and assembly method according to claim 23, characterized in that: The depth of the isolation groove is 5μm~10μm.

26. The magnetic assembly microdevice transfer and assembly method according to claim 23, characterized in that: The radial cross-sectional area of ​​each of the patterned soft magnetic material layers gradually decreases in the direction away from the magnetic generation layer.

27. The magnetic assembly microdevice transfer and assembly method according to claim 26, characterized in that: The axial cross-section of each of the patterned soft magnetic material layers is trapezoidal.

28. The magnetic assembly microdevice transfer and assembly method according to claim 23, characterized in that: The radial cross-sectional area of ​​the isolation groove gradually increases in the direction away from the magnetic generation layer.

29. The magnetic assembly microdevice transfer and assembly method according to claim 28, characterized in that: The axial cross-section of each of the isolation grooves is triangular.

30. The magnetic assembly microdevice transfer and assembly method according to claim 23, characterized in that: The surface of the low permeability material layer is flush with the surface of the patterned soft magnetic material layer.

31. The magnetic assembly microdevice transfer and assembly method according to claim 23, characterized in that: The material of the low magnetic permeability layer includes resin.

32. The magnetic assembly microdevice transfer and assembly method according to claim 23, characterized in that: The magnetic connection layer is made of an alloy containing at least one of iron, cobalt, and nickel.

33. The magnetic assembly microdevice transfer and assembly method according to claim 23, characterized in that: The patterned soft magnetic material layer is made of ferrite, iron-silicon alloy, or iron-silicon-aluminum alloy.

34. The magnetic assembly microdevice transfer and assembly method according to claim 20, characterized in that, include: First, an adhesive layer is disposed on the microdevice, and then the magnetic connection layer is disposed on the adhesive layer. The magnetic connection layer is fixed on the microdevice by the adhesive layer, thereby forming a temporary transfer microdevice. The fixed bonding state between the adhesive layer and the microdevice can be released. Furthermore, the magnetic bonding layer is separated and removed from the microdevice by releasing the fixed bond between the adhesive layer and the microdevice.

35. The magnetic assembly microdevice transfer and assembly method according to claim 34, characterized in that: The adhesive layer is made of hot melt adhesive material. The magnetic assembly microdevice transfer assembly method specifically includes: heating the adhesive layer to reduce its stickiness, thereby separating the adhesive layer from the magnetic connection layer and the microdevice. Alternatively, the adhesive layer is made of a thermally decomposable material, and the magnetic assembly microdevice transfer assembly method specifically includes: heating the adhesive layer to above its thermal decomposition temperature so that the adhesive layer thermally decomposes and loses its adhesiveness, and the adhesive layer separates from the magnetic connection layer and the microdevice; Alternatively, the adhesive layer may be made of photosensitive adhesive, and the magnetic assembly microdevice transfer assembly method may specifically include: heating the adhesive layer to melt it and cause it to lose its adhesiveness, thereby separating the adhesive layer from the magnetic connection layer and the microdevice. Alternatively, the adhesive layer may be made of strontium aluminate, and the magnetic assembly microdevice transfer assembly method may specifically include: contacting the adhesive layer with water to dissolve the adhesive layer in the water, thereby separating the adhesive layer from the magnetic connection layer and the microdevice.

36. The magnetic assembly microdevice transfer and assembly method according to claim 34, characterized in that: The microdevice is a vertical structure device, and the microdevice also includes an intermediate substrate. The vertical structure device is electrically connected to the intermediate substrate. The magnetic assembly microdevice transfer assembly method specifically includes: An adhesive layer is disposed on the intermediate substrate to fix the magnetic connection layer on the intermediate substrate.

37. The magnetic assembly microdevice transfer and assembly method according to claim 34, characterized in that: The microdevice is a flip-chip structure device, and the magnetic assembly microdevice transfer assembly method specifically includes: setting an adhesive layer on the flip-chip structure device, and fixing the magnetic connection layer on the flip-chip structure device with the adhesive layer.

38. The magnetic assembly microdevice transfer and assembly method according to claim 20, characterized in that: The magnetic generating layer includes a magnetic device and a magnetic adjustment mechanism. The magnetic adjustment mechanism cooperates with the magnetic device and is used at least to adjust the magnetic attraction between the magnetic device and the magnetic connection layer.

39. The magnetic assembly microdevice transfer and assembly method according to claim 20, characterized in that: The magnetic device includes a permanent magnet, the magnetic adjustment mechanism includes a movable platform, and the magnetic assembly microdevice transfer assembly method specifically includes: driving the permanent magnet to move along a selected direction by the movable platform, and changing the magnetic attraction between the magnetic device and the magnetic connection layer by at least adjusting the distance between the permanent magnet and the temporary transfer microdevice, so that the magnetic platform and the temporary transfer microdevice are magnetically attracted or retracted. Alternatively, the magnetic device includes an electromagnet, the magnetic adjustment mechanism includes a control circuit, the control circuit is electrically connected to the electromagnet, and the magnetic assembly microdevice transfer assembly method specifically includes: adjusting the magnetic field direction of the electromagnet or turning the electromagnet on and off with the control circuit to change the magnetic attraction between the magnetic device and the magnetic connection layer, so that the magnetic platform and the temporary transfer microdevice are magnetically attracted or retracted.

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