Micro device block transfer

Abstract

A structure and method for integrating a block of a microdevice into a system backplane are disclosed. A process for forming a block of a microdevice and forming a transfer template to facilitate the transfer of the block of the microdevice to the system backplane is schematically described. Additionally, an embodiment relates to a microdevice in which a block is formed from different wafers and substrates.

Description

Technology Field

[0001] The present disclosure relates to integrating a microdevice into a system substrate.

[0002] The present invention relates to a method for transferring a microdevice to a system backplane, the method comprising the steps of: embedding a microdevice in a housing structure having a buffer layer; bonding the housing structure to a temporary substrate with a bonding layer; having a release layer between the housing structure and the temporary substrate; singulating the housing structure around a set of microdevices forming a block of microdevices; and forming a transfer template for transferring the microdevice into a system backplane using the block of microdevices. Brief explanation of the drawing

[0003] The foregoing advantages and other advantages of the present disclosure will become apparent when reading the following detailed description and referring to the drawings. FIG. 1a illustrates an exemplary microdevice embedded in a housing structure and a release layer. FIG. 1b illustrates an exemplary embodiment of a microdevice limited to a block layer set on a release layer on the top of a substrate. FIG. 2 illustrates a process of forming a template for transferring a microdevice into a system backplane using a block-shaped microdevice. FIG. 3 illustrates one exemplary arrangement of blocks (610) in a transfer template. FIG. 4 illustrates process steps for forming a multi-device template from different wafers. FIGS. 5a to 5e illustrate the transfer process of blocks having different microdevices from different substrates. While the present disclosure allows for various modifications and alternative forms, specific embodiments or embodiments are illustrated in the drawings by way of example and will be described in detail herein. However, it should be understood that the present disclosure is not intended to be limited to the specific forms disclosed. Rather, the present disclosure is intended to encompass all modifications, equivalents, and alternatives within the spirit and scope of the invention as defined by the appended claims. Specific details for implementing the invention

[0004] In this description, the terms "device" and "micro device" are used interchangeably. However, it is obvious to those skilled in the art that the embodiments described herein are independent of device size.

[0005] Some embodiments of this description relate to integrating microdevices within a receiving substrate. The system substrate may include micro light-emitting diodes (LEDs), organic LEDs, sensors, solid-state devices, integrated circuits, micro-electro-mechanical systems (MEMS), and / or other electronic components.

[0006] The receiving substrate may be, but is not limited to, a printed circuit board (PCB), a thin-film transistor backplane, an integrated circuit board, or, in the case of an optical microdevice such as an LED, a component of a display, e.g., a driving circuit backplane. The patterning of the microdevice donor substrate and the receiving substrate may be used in combination with various transfer technologies, and such transfer technologies include, but are not limited to, pick-and-place having various mechanisms (e.g., electrostatic transfer heads, elastomeric transfer heads) or direct transfer mechanisms (e.g., dual-function pads).

[0007] Various embodiments according to the provided structure and process are described in detail below.

[0008] FIG. 1a illustrates an example of a microdevice (400) embedded in a housing structure (402) having a buffer layer (404). The structure is bonded to a temporary substrate (406) with a bonding layer (408). The bonding layer may be identical to the housing layer. A release layer (410) may be present between the housing structure and the temporary substrate (406). The bonding layer (408) may be identical to the release layer (410). Other layers, such as bonding, pads, anchors, etc., may be present on the microdevice (400). These layers are described as layers (412).

[0009] FIG. 1b illustrates an embodiment in which a microdevice (400) is confined to a block (420). Such a block (420) can be developed by singulating a housing layer(s) around a set of microdevices. Here, the release layer (410) may be patterned or continuous. The housing material may be various types of polymers (e.g., polyamide, BCB, SU8) or other dielectrics.

[0010] FIG. 2 illustrates a process (500) for forming a template for transferring a microdevice into a system backplane using a block of microdevices. During the first step (502), the microdevice within the block is characterized for at least one parameter. This characterization may be performed via visual inspection, luminance, or electrical measurement. The extracted parameter may be electrical, optical, physical, or of other types. The block may be mapped based on the extracted parameter. A set of blocks may be selected and transferred to a transfer template. The selection may be made based on the performance or defects of the blocks (506). Here as well as in part of step (504), a set of blocks is selected if the defective microdevice within the block is smaller than a set threshold or if the performance of the microdevice within the block is within a set threshold. Additionally, the performance difference between the blocks is within the threshold. Transferring the block to the transfer template may be performed by various processes such as pick-and-place, laser ablation, or offset printing. In some cases, pick and place may be used. During the pick-up process, the release layer is activated, and as a result, the block can be separated from the temporary substrate. The block is then moved to a transfer template and placed on the template. The placement process may also include bonding. The bonding step may be adhesive. After a set of blocks is transferred to the transfer template, the blocks can be fixed in place (508). The fixing process may include curing, flattening, filler, or other process steps. In the case of laser ablation, there may be a layer underneath each block that expands significantly under the emission of a specific laser and pushes the block onto the template.

[0011] A transfer template can be used to transfer microdevices into a system backplane (520). In one approach, the microdevices are transferred directly from the template into the system backplane. Here, the transfer template is aligned with a part of the backplane. Then, a set of microdevices selected from the template is placed on the backplane. Placement can be achieved by bonding or laser separation. In another case, the microdevices are picked from the template and then transferred from the system backplane.

[0012] FIG. 3 illustrates an exemplary arrangement of blocks (610) in a transfer template (600). The skew of the blocks may be different or fixed. Skew can reduce some visual artifacts caused by sharp edges. The template may have indentations on the edges. And the edges between the templates are fitted to the edges of adjacent templates.

[0013] FIG. 4 illustrates a process step (700) for forming a multi-device template using microdevices blocked from different wafers to form a transfer template for transferring microdevices into a system backplane. During the first step (702 and 704), blocks of microdevices within different wafers are characterized for at least one parameter. This characterization may be performed via visual inspection, luminance, or electrical measurement. The extracted parameter may be electrical, optical, physical, or of other types. Blocks may be mapped based on the extracted parameter. A set of blocks from different wafers may be selected and transferred to the transfer template. The selection may be made based on the performance or defects of the blocks (706). Here, too, a set of blocks is selected if the number of defective microdevices within the blocks is less than a set threshold, or if the performance of the microdevices within the blocks is within a set threshold. Additionally, the performance difference between the blocks is within the threshold. Transferring the blocks to the template may be performed by various processes. In some cases, pick and place may be used. During the pick-up process, the release layer is activated, and as a result, the block can be separated from the temporary substrate. The block is then moved to a transfer template and placed on the template. The placement process may also include bonding. The bonding step may be adhesive. After the set of blocks is transferred to the transfer template, the blocks can be fixed in place (708). The fixing process may include curing, flattening, filler, or other process steps.

[0014] A template can be used to transfer microdevices into the system backplane (720). In one approach, the microdevices are transferred directly from the template into the system backplane, where the template is aligned with a part of the system backplane. Then, a set of microdevices selected from the template is placed on the backplane. Placement can be achieved by bonding or laser separation. In another case, the microdevices are picked from the template and then transferred from the system backplane.

[0015] FIGS. 5a through 5e illustrate different microdevices (800-a, 800-b, and 800-c) from different substrates (806-a, 806-b, and 806-c). The microdevices are embedded in blocks (820-a, 820-b, and 820-c). A release layer (810-a, 810-b, and 810-c) capable of separating the microdevice blocks from the substrate is used. The release layer (810-a, 810-b, and 810-c) may be patterned or may cover the entire surface of the transfer template. The pattern may be identical to the block pattern. After mapping the microdevices, at least one block from each substrate (806-a, 806-b, and 806-c) is transferred to a transfer template (850). A bonding layer (840) for holding the blocks is present on the transfer template. The template can be patterned to match the location of each block or cover the entire transfer template. The blocks on the transfer template are placed in appropriate locations to correspond to device locations (882-a, 882-b, and 882-c) on the system substrate (880).

[0016] Method modalities

[0017] The present invention A method for transferring a microdevice to a system backplane is described, comprising the steps of: embedding the microdevice in a housing structure having a buffer layer; bonding the housing structure to a temporary substrate with a bonding layer; having a release layer between the housing structure and the temporary substrate; singulating the housing structure around a set of microdevices forming a block of microdevices; and forming a transfer template for transferring the microdevice into the system backplane using the block of microdevices. The method further comprises the microdevices in the block being characterized for at least one parameter, wherein the characterization is performed via visual inspection, luminance, or electrical measurement. The extracted parameter is of an electrical, optical, or physical type, and the block of microdevices is mapped based on the extracted parameter.

[0018] The method further comprises selecting a set of blocks of microdevices and transferring them to a transfer template, wherein the selection is based on the performance or defects of the blocks of microdevices, and the set of blocks of microdevices is selected when the number of defective microdevices within the blocks is less than a set threshold or the performance of the microdevices within the blocks is within a set threshold. Additionally, the performance difference between the blocks of microdevices is within the threshold. In the method, transferring the blocks of microdevices to the transfer template is performed by a pick-and-place process, laser ablation, or offset printing, and during the pick-and-place process, a release layer is activated to separate the blocks of microdevices from a temporary substrate. Here, in the case of laser ablation, there is a layer beneath each block of microdevices that expands under the emission of a specific laser and pushes the blocks of microdevices into the template. Additionally, the blocks are moved to the transfer template and placed on the transfer template, and the placement on the block process involves adhesive bonding. Here, the set of blocks of microdevices transferred to the transfer template is fixed in place by a fixing process. Additionally, the fixing process includes curing, planarization, covering with a filler or a different layer. Here, the microdevice is picked from the transfer template and then transferred on the system backplane, and the microdevice is picked from the transfer template and then transferred on the system backplane.

[0019] The method also includes cases where the bonding layer is identical to the release layer. Additionally, additional layers such as a bonding layer, pads, and anchors exist on the microdevice. Furthermore, the microdevice is transferred directly from a transfer template into a system backplane, where the transfer template is aligned with a part of the system backplane, and a set of blocks of microdevices selected from the transfer template are placed on the system backplane by a placement process, the placement process being performed by bonding or laser separation.

[0020] The method also includes cases where microdevices originate from different wafers, and blocks of microdevices within the different wafers are characterized for at least one parameter.

[0021] The method also includes cases where microdevices from different substrates are embedded in separate microdevice blocks. Here, the release layer is used for the microdevice blocks from the substrates, and the release layer is patterned or covers the entire surface of the transfer template.

[0022] Although specific embodiments and applications of the present invention have been illustrated and described, it should be understood that the present invention is not limited to the exact configurations and compositions disclosed herein, and that various modifications, changes, and variations may become apparent from the foregoing description without departing from the spirit and scope of the present invention as defined in the appended claims.

Claims

Claim 1 A method for transferring a microdevice to a system backplane, comprising: embedding the microdevice in a housing structure having a buffer layer; bonding the housing structure to a temporary substrate with a bonding layer; having a release layer between the housing structure and the temporary substrate; singulating the housing structure around a set of microdevices forming a block of microdevices; and forming a transfer template for transferring the microdevice into the system backplane using the block of microdevices, wherein the microdevice is transferred from the transfer template into the system backplane together with the housing structure that embeds the space between adjacent first and second microdevices within the block, and the microdevice is disposed on the system backplane together with the housing structure. Claim 2 A method according to claim 1, wherein the microdevice within the block is characterized for at least one parameter. Claim 3 In paragraph 2, the method wherein the above characterization is performed through visual inspection, luminance, or electrical measurement. Claim 4 In paragraph 2, the extracted parameter is of an electrical, optical, or physical type, method. Claim 5 In paragraph 4, the method wherein the blocks of the microdevice are mapped based on the extracted parameters. Claim 6 A method according to claim 1, wherein a set of blocks of a microdevice is selected and transferred to the transfer template, and the selection is based on the performance or defects of the blocks of the microdevice. Claim 7 A method according to claim 6, wherein a set of blocks of the microdevices is selected when the defective microdevices within the blocks are smaller than a set threshold or the performance of the microdevices within the blocks is within the set threshold. Claim 8 In claim 7, the method wherein the performance difference between blocks of the microdevice is within a threshold. Claim 9 In claim 6, the method of transferring the block of the microdevice to the transfer template is performed by a pick-and-place process, laser ablation, or offset printing. Claim 10 In claim 9, a method in which, during the pick-and-place process, the release layer is activated so that a block of the microdevice is separated from the temporary substrate. Claim 11 In paragraph 10, the method wherein the block is moved to the transfer template and placed on the transfer template. Claim 12 In claim 11, the method wherein the block is bonded to the transfer template using an adhesive material. Claim 13 In claim 11, a method wherein a set of blocks of the microdevice transferred to the transfer template is fixed in place by a fixing process. Claim 14 In paragraph 13, the fixing process comprises curing, leveling, covering with a filler or a different layer. Claim 15 In claim 1, the bonding layer is the same as the release layer, method. Claim 16 A method according to claim 1, wherein additional layers such as a bonding layer, a pad, and an anchor exist on the microdevice. Claim 17 A method according to claim 13, wherein the microdevice is transferred directly from the transfer template into the system backplane, wherein the transfer template is aligned with a part of the system backplane and a set of blocks of microdevices selected from the transfer template are placed on the system backplane by a placement process. Claim 18 In paragraph 17, the above-mentioned placement process is performed by bonding or laser separation, a method. Claim 19 delete Claim 20 A method according to claim 1, wherein the microdevice is derived from a different wafer. Claim 21 A method according to claim 20, wherein blocks of the microdevice in different wafers are characterized for at least one parameter. Claim 22 In paragraph 21, the above characterization is performed through visual inspection, luminance, or electrical measurement. Claim 23 In paragraph 21, the extracted parameter is of an electrical, optical, or physical type, a method. Claim 24 In paragraph 23, the method wherein the blocks of the microdevice are mapped based on the extracted parameters. Claim 25 A method according to claim 20, wherein a set of blocks of a microdevice is selected and transferred to the transfer template, and the selection is based on the performance or defects of the blocks of the microdevice. Claim 26 A method according to claim 25, wherein a set of blocks of the microdevices is selected when the defective microdevices within the blocks are smaller than a set threshold or the performance of the microdevices within the blocks is within the set threshold. Claim 27 In claim 26, a method in which the performance difference between blocks of the microdevice is within a threshold. Claim 28 In paragraph 25, the method of transferring the block of the microdevice to the transfer template is performed by a pick-and-place process. Claim 29 In claim 28, the release layer is activated so that a block of the microdevice is separated from the temporary substrate. Claim 30 In paragraph 29, the method wherein the block is moved to the transfer template and placed on the transfer template. Claim 31 In paragraph 30, the method wherein the block is bonded to the transfer template using an adhesive material. Claim 32 In paragraph 30, a method wherein a set of blocks of the microdevice transferred to the transfer template is fixed in place by a fixing process. Claim 33 In paragraph 32, the fixing process comprises a curing, leveling, filler, or other process step. Claim 34 A method according to claim 32, wherein the microdevice is transferred directly from the transfer template into the system backplane, wherein the transfer template is aligned with a part of the system backplane and a set of blocks of microdevices selected from the transfer template are placed on the system backplane by a placement process. Claim 35 In paragraph 34, the above-mentioned placement process is performed by bonding or laser separation, a method. Claim 36 delete Claim 37 A method according to claim 1, wherein the microdevice from a different substrate is embedded in a separate microdevice block. Claim 38 In claim 37, the release layer is used in the microdevice block from the substrate, a method. Claim 39 In paragraph 38, the release layer is patterned or covers the entire surface of the transfer template. Claim 40 A method according to claim 37, wherein after the blocks of the microdevices are mapped, at least one microdevice block from each substrate is transferred to the transfer template. Claim 41 A method according to claim 40, wherein a bonding layer for holding the block exists on the transfer template. Claim 42 In paragraph 41, the transfer template is patterned to match the position of each block or covers the entire transfer template. Claim 43 A method according to claim 41, wherein the microdevice block on the transfer template is positioned at a location corresponding to the microdevice location as the system backplane. Claim 44 In claim 9, in the case of the laser ablation, a method having a layer underneath each microdevice block that expands under the emission of a specific laser and pushes the microdevice block into the template.

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