TWI815968B - Integration of microdevices into system substrate - Google Patents

Abstract

In a micro-device integration process, a donor substrate is provided on which to conduct the initial manufacturing and pixelation steps to define the micro devices, including functional, e.g. light emitting layers, sandwiched between top and bottom conductive layers. The micro-devices are then transferred to a system substrate for finalizing and electronic control integration. The transfer may be facilitated by various means, including providing a continuous light emitting functional layer, breakable anchors on the donor substrates, temporary intermediate substrates enabling a thermal transfer technique, or temporary intermediate substrates with a breakable substrate bonding layer.

Description

Integrate microdevices into system substrates

The present invention relates to optoelectronic microdevices, and more particularly to the integration of optoelectronic microdevices into system substrates with enhanced bonding and conductivity capabilities.

It is an object of the present invention to overcome the shortcomings of the prior art by providing a system and method for transferring microdevices from a donor substrate to a system substrate.

According to an embodiment of the present invention, a method for manufacturing a pixelated structure includes: providing a donor substrate; depositing a first conductive layer on the donor substrate; and depositing a completely or partially continuous light-emitting functional layer on the first conductive layer. ; depositing a second conductive layer on the functional layer; patterning the second conductive layer to form pixelated structures; providing bonding contacts for each pixelated structure; securing the bonding contacts to the system substrate; and Remove the donor substrate.

In one embodiment, the microdevice is made into an array using continuous pixelation.

In another embodiment, the devices are separated and transferred to an intermediate substrate by filling the voids between the microdevices.

In another embodiment, the microdevice is post-processed after transfer to the intermediate substrate.

According to one embodiment, a bonding structure may be provided. The bonding structure may include a plurality of microdevices on a donor substrate, wherein each microdevice includes one or more conductive pads formed on a surface of the microdevice; and the temporary material covers each microdevice or the one or more At least a portion of the conductive pad. In one case, the temporary material acts as an anchor that holds the plurality of microdevices inside the housing structure in the donor substrate.

According to one embodiment, a method for integrating a microdevice on a backplane can be provided. The method includes: providing a microdevice substrate composed of one or more microdevices; connecting pads on the microdevice and corresponding pads on the backplane. bonding pads to bond a selected set of microdevices from the substrate to the backplane; and detaching the microdevice substrate to leave the bonded selected set of microdevices on the backplane.

Cross-references to related applications

This application is a partial continuation of U.S. Application No. 15/820,683 filed on November 22, 2017 and claims its priority. The U.S. Application No. 15/820,683 claims the priority and rights of the following applications: U.S. Provisional Patent Application No. 62/426,353 filed on November 25, 2016, U.S. Provisional Patent Application No. 62/473,671 filed on March 20, 2017, U.S. Provisional Patent Application filed on April 7, 2017 No. 62/482,899 and U.S. Provisional Patent Application No. 62/515,185 filed on June 5, 2017, and Canadian Patent Application No. 2,984,214 filed on October 30, 2017, each of which One is incorporated herein by reference in its entirety.

This application also claims the rights and interests of U.S. Provisional Patent Application No. 62/734,679 filed on September 21, 2018 and U.S. Provisional Patent Application No. 62/809,161 filed on February 22, 2019. These provisional patent applications The case is incorporated by reference in its entirety.

This application further claims U.S. Provisional Patent Application No. 62/746,300, filed on October 16, 2018, which is incorporated herein by reference in its entirety.

Although the present teachings are described in conjunction with various embodiments and examples, the present teachings are not intended to be limited to these embodiments. On the contrary, the present teachings cover various alternatives and equivalents, as those skilled in the art will understand.

Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the invention.

As used in this specification and claims, the singular forms "a/an" and "the" include plural referents unless the context clearly dictates otherwise.

In this specification, the terms "device", "vertical device" and "micro device" are used interchangeably. However, those skilled in the art will appreciate that the embodiments described herein are independent of device size.

In this specification, the terms "donor substrate" and "temporary substrate" are used interchangeably.

In this specification, the terms "receptor substrate", "system substrate" and "backplane" are used interchangeably.

Examples of optoelectronic devices are sensors and light emitting devices, such as light emitting diodes (LEDs).

The present invention relates to a microdevice array display device in which the microdevice array can be bonded to a backplane using a reliable method. Microdevices can be fabricated above microdevice substrates. Microdevice substrates may include microLEDs, inorganic LEDs, organic LEDs, sensors, solid state devices, integrated circuits, microelectromechanical systems (MEMS), and/or other electronic components.

LEDs and LED arrays can be classified as vertical solid-state devices. The microdevice can be a sensor, LED, or any other solid device grown, deposited, or monolithically fabricated on a substrate. The substrate may be a native substrate or a receptor substrate for the device layer to which the device layer or solid state device is transferred.

The receptor substrate can be any substrate and can be rigid or flexible. The receptor substrate may include, but is not limited to, a printed circuit board, a thin film transistor (TFT) backplane, an integrated circuit substrate, or in the case of an optical microdevice such as an LED, a component of a display such as a driver circuit backplane. Microdevice patterning on device donor and acceptor substrates can be performed with different transfer techniques such as pick-and-place with different mechanisms (e.g., electrostatic transfer heads, elastomeric transfer heads) or direct transfer mechanisms (e.g., dual-function pads) Use in combination.

In this disclosure, a contact pad in the receptor substrate refers to a designated area in the receptor substrate to which the microdevice is transferred. The contact pads may include bonding material that permanently retains the microdevice. Contact pads can be stacked in multiple layers to provide a mechanically stable structure with improved bonding and electrical conductivity capabilities.

System substrates can be made of glass, silicon, plastic, or any other commonly used material. The system substrate may also have active electronic components such as (but not limited to) transistors, resistors, capacitors, or any other electronic components commonly used in system substrates. In some cases, the system substrate may be a substrate having columns and rows of electrical signals. The system substrate may be a backplane with circuitry to derive the micro-LED devices.

Figure 1A shows an embodiment of a donor substrate 110 with lateral functional structures including a bottom planar or sheet-like conductive layer 112; a functional layer 114, such as a luminescent quantum well; and a top pixelated conductive layer 116. Conductive layers 112 and 116 may be composed of doped semiconductor materials or other suitable types of conductive layers. Top conductive layer 116 may include several different layers. In one embodiment, as shown in FIG. 1B , a current distribution layer 118 is deposited on top of the conductive layer 116 . Current distribution layer 118 may be patterned. In one embodiment, patterning can be performed by lift off. In another case, patterning can be performed by photolithography. In embodiments, the dielectric layer may be deposited and patterned first and then used as a hard mask to pattern the current distribution layer 118 . After patterning the current distribution layer 118, the top conductive layer 116 can also be patterned to form a pixel structure. After patterning the current distribution layer 118 and/or the conductive layer 116, a final dielectric layer 120 may be deposited over and between the patterned conductive layer 116 and the current distribution layer 118, as shown in FIG. 1C. The dielectric layer 120 may also be patterned to create openings 130 as shown in FIG. 1D to provide access to the current distribution layer 118 . An additional leveling layer 128 may also be provided to flatten the upper surface, as shown in Figure 1E.

As shown in FIG. 1E , a pad 132 is deposited in each opening 130 on top of the current distribution layer 118 . The resulting structure with pads 132 is bonded to system substrate 150 with pads 154, as shown in Figure IF. Pads 154 in system substrate 150 may be separated by dielectric layer 156 . Other layers 152 may be present between the system substrate pads 154 and the system substrate 150, such as circuitry, planarization layers, conductive traces. System substrate pad 154 may be bonded to pad 132 by fusion bonding, anodic bonding, thermocompression bonding, eutectic bonding, or adhesive bonding. One or more other layers may also be deposited between the system device and the lateral device.

As shown in FIG. 1G , the donor substrate 110 may be removed from the lateral functional devices, such as the conductive layer 112 . Conductive layer 112 may be thinned and/or partially or fully patterned. A reflective layer or black matrix 170 may be deposited and patterned to cover the areas on conductive layer 112 between pixels. After this stage, other layers can be deposited and patterned according to the functionality of the device. For example, a color conversion layer may be deposited to adjust the color of light produced by lateral devices and pixels in system substrate 150. One or more color filters may also be deposited before and/or after the color conversion layer. The dielectric layer in these devices, such as the dielectric layer 120, can be an organic material such as polyamide or an inorganic material such as SiN, SiO ₂ , Al ₂ O ₃ or the like. This deposition can be performed using different processes, such as plasma enhanced chemical vapor deposition (PECVD), atomic layer deposition (ALD), and other methods. Each layer may be one deposited material or a combination of different materials deposited separately or together. The bonding material may be deposited only as a portion of the pads 132 of the donor substrate 110 or the system substrate pads 154 . There may also be some annealing process for some of the layers. For example, current distribution layer 118 may be annealed depending on the material. In one example, current distribution layer 118 may be annealed at 500°C for 10 minutes. Annealing can also be performed after different steps.

Figure 2A shows an exemplary embodiment of a donor substrate 210 with lateral functional structures including a first top planar or sheet-like conductive layer 212; a functional layer 214, such as a light emitting layer; and a second bottom pixelated conductive layer. layer 216; current distribution layer 218; and/or bonding pad layer 232. Figure 2B shows patterning all or one of layers 216, 218, 232 to form pixel structures. Conductive layers 212 and 216 may be composed of multiple layers including highly doped semiconductor layers. Layers 228, such as dielectric, may be used between patterned layers 216, 218, and 232 to flatten the upper surfaces of the lateral functional structures, as shown in Figure 2C. Layer 228 may also have other functions, such as a black matrix. The resulting structure with pads 232 is bonded to system substrate 250 with substrate pads 254, as shown in Figure 2D. The pads 254 in the system substrate may also be separated by a dielectric layer 256 . Other layers 252 may be present between system substrate pads 254 and system substrate 250, such as circuitry, planarization layers, and conductive traces. The bonding can be performed, for example, by melt bonding, anodic bonding, thermocompression bonding, eutectic bonding or adhesive bonding. Other layers may also be deposited between the system device and the lateral device.

Donor substrate 210 is removable from the lateral functional device. Conductive layer 212 may be thinned and/or patterned. A reflective layer or black matrix 270 may be deposited and patterned to cover the areas on conductive layer 212 between pixels. After this stage, other layers can be deposited and patterned according to the functionality of the device. For example, a color conversion layer may be deposited to adjust the color of light produced by lateral devices and pixels in system substrate 250. One or more color filters may also be deposited before and/or after the color conversion layer. The dielectric layers in these devices, such as 228 and 256, can be organic materials such as polyamide or inorganic materials such as SiN, SiO ₂ , Al ₂ O ₃ and other materials. Different processes can be used to perform this deposition, such as PECVD, ALD and other methods. Each layer may be one deposited material or a combination of different materials deposited separately or together. The material of bond pad 232 may be deposited as part of pad 232 of donor substrate 210 or system substrate pad 254 . There may also be some annealing process for some of the layers. For example, current distribution layer 218 may be annealed depending on the material. In an example, the current distribution layer may be annealed at 500°C for 10 minutes. Annealing can also be performed after different steps.

In another embodiment shown in Figure 3A, a mesa structure is created on a donor substrate 310. Microdevice structures are formed by etching through different layers, such as the first bottom conductive layer 312, the functional layer 314, and the second top conductive layer 316. Top contact 332 may be deposited before or after etching on top of top conductive layer 316 . In another case, multi-layer contacts 332 may be used. In this case, a portion of the contact layer 332 may be deposited before etching, and a portion of the contact layer 332 may be deposited after etching. For example, an initial contact layer that creates an ohmic contact by annealing the conductive layer 316 may be deposited first. In one example, the initial contact layer may be gold or nickel. Other layers 372, such as dielectric or metal insulator structures (MIS), may also be used between mesa structures to isolate and/or insulate each structure. After forming the microdevice, a filler layer 374, such as polyamide, may be deposited, as shown in Figure 3B. Fill layer 374 may be patterned if only selected microdevices are transferred to cassette (temporary) substrate 376 during subsequent steps. The filler layer 374 may also be deposited after the device is transferred to the temporary substrate. The filler layer 374 may serve as a housing for the microdevice. The peeling process may be more reliable if the filler layer 374 is used prior to transfer.

The device is bonded to a temporary substrate (cassette) 376 . For example, the source of bonding may vary and may include one or more of the following: electrostatic bonding, electromagnetic bonding, adhesive bonding, Van-Der-Waals force bonding, or thermal bonding . For thermal bonding, a substrate bonding layer 378 with a melting temperature T1 may be used. Bonding layer 378 may be conductive or may include a conductive layer and a bonding layer, which may be adhesive bonding, thermal bonding, or light-assisted bonding. The conductive layer may be used to bias devices on substrate 376 to identify defects and characterize device performance. This structure can be used with other embodiments presented here. To account for certain surface profile non-uniformities, pressure can be applied during the bonding process. Temporary substrate 376 or donor substrate 310 can be removed and the device left on either. The process explained herein is based on leaving the device on the temporary substrate 376, however, similar steps may be used when the device is left on the donor substrate 310. After this, additional processes may be performed on the microdevice, such as thinning the device, creating a contact bonding layer 380 on the bottom conductive layer 312, or removing the filler layer 374. The device may be transferred to system substrate 390, as shown in Figures 3D and 3E. Different techniques can be used to perform this transfer. In one case, thermal bonding is used to perform the transfer. In this case, the melting point of the contact bonding layer 380 on the system substrate contact pad 382 is T2, where T2 > T1. Here, temperatures above T2 will melt both the substrate bonding layer 378 and the contact bonding layer 380 on the pad 382.

In subsequent steps, the temperature is reduced to between T1 and T2. At this time, the device is bonded to the system substrate 390 through the contact bonding layer 380, so that the contact bonding layer 380 is solidified, but the substrate bonding layer 378 is melted. Therefore, temporary substrate 376 is moved such that the microdevice remains on system substrate 390, as shown in Figure 3E. This process can be made selective by applying localized heating to selected pads 382 . Furthermore, in addition to local heating, global temperature can be used, such as placing the substrates 376 and 390 in an oven and performing the process by increasing the overall atmosphere therein, thereby increasing the transfer speed. Here, the global temperature on the temporary substrate 376 or the system substrate 390 can bring the temperature close to the melting point of the contact bonding layer 380, for example, between 5°C and 10°C below the melting point, and the local temperature can be used to melt the material in contact with the selected device. Corresponding contact bonding layer 380 and substrate bonding layer 378. In another case, the temperature may be raised close to the melting point of the substrate bonding layer 378 (higher than the melting point of the contact bonding layer 378), for example, between 5°C and 10°C lower than the melting point, and for the same purpose as after heating For devices in contact with pad 382 , selected areas of substrate bonding layer 378 are melted by temperature transfer from the device to pad 382 .

FIG. 3F shows an example of a thermal profile where the melting temperature Tr melts the contact bonding layer 380 and the substrate bonding layer 378 and the solidification temperature Ts solidifies the contact bonding layer 380 with the bonding pad 382 while the substrate bonding layer 378 Still melted. Melting may be localized or may at least soften the bonding layer enough to release the microdevice or activate the alloy forming process. Here, other forces may also be used in combination or alone to retain the device on bond pad 382. In another instance, a temperature profile can be generated by applying electrical current through the device. Because the contact resistance will be high prior to bonding, the power dissipated on bond pad 382 and the device will be high, melting contact bonding layer 380 and substrate bonding layer 378 . As the bond forms, the resistance will decrease and power dissipation will decrease, thereby lowering the local temperature. The voltage or current across pad 382 can be used to indicate the quality of the bond and when to stop the process. Donor substrate 310 and temporary substrate 376 may be the same or different. After the device is transferred to the system substrate 390, various process steps may be performed. These additional processing steps may be planarization, electrode deposition, color conversion deposition and patterning, color filter deposition and patterning, etc.

In another embodiment, the temperature used to release the microdevice from the cassette substrate 376 increases as the alloy begins to form. In this case, the temperature can be held constant while the bonding alloy is formed on the bonding pads 382 of the receptor substrate 390 and the bonding layer solidifies, thereby keeping the microdevice in place on the receptor substrate 390 at. At the same time, the bonding layer 378 on the cartridge 376 connected to the selected microdevice is still melted (or soft enough) to release the device. Here, a portion of the material required to form the alloy can be on the microdevice and another portion is deposited on bond pad 382 .

In another embodiment, a filler layer 374 may be deposited on top of the cassette substrate 376 to form a polymer filler/bonding layer 374/378. Next, the microdevice from the donor substrate 310 can be pushed into the polymer filler/bonding layer 374/378. Next, the microdevice may be selectively or generally separated from the donor substrate 310. The polymer filler/bonding layer 374/378 may be cured before or after separating the microdevice from the donor substrate 310. The polymer filler/bonding layers 374/378 may be patterned, especially where multiple different devices are integrated into the cassette substrate 376. In this case, the polymer filler/bonding layer 374/378 may be created for one type, with the microdevice buried in this layer and separated from its donor 310. Next, another polymer filler/bonding layer 374/378 is deposited and patterned for the next type of microdevice. Next, the second microdevice can be buried in the associated layer 374/378. In all cases, the polymer filler/bonding layer 374/378 may cover some or all of the microdevice.

Another method of increasing temperature can be the use of microwaves or lamps. Thus, a layer may be deposited on: bonding pad 382; a portion of bonding pad 382; a microdevice; or a portion of box 376 that absorbs microwaves or light and locally heats the microdevice. Alternatively, cartridge 376 and/or receptor substrate 390 may contain heating elements that can selectively and/or globally heat the microdevice.

Other methods may also be used to separate the microdevice from the temporary substrate 376, such as chemical, optical, or mechanical forces. In one example, the microdevice may be covered with a sacrificial layer that may be debonded to the temporary substrate 376 by chemical, optical, thermal, or mechanical forces. The debonding process can be selective or global. Global debonding transfer to system substrate 390 is optional. If the debonding process of the device from the temporary substrate (cassette) 376 is selective, transfer forces may be applied to the system substrate 390 selectively or globally.

The transfer process from the cartridge 376 to the receptor substrate 390 can be based on different mechanisms. In one case, the cartridge 376 has a bonding material that releases the device in the presence of light while the same light cures the bond of the device to the receptor substrate.

In another embodiment, the temperature used to cure the bonding layer 380 of the device to the receptor substrate 390 causes the device to be released from the cartridge 376 .

In another instance, the electrical current or voltage solidifies the device-to-donor substrate 310 bonding layer 380 . The same current or voltage can cause the device to be released from box 376. Here, the release can be a function of the piezoelectric effect produced by electrical current or temperature.

In another approach, after the bonding of the device to the receptor substrate 390 is cured, the bonded device is pulled from the cassette 376 . Here, the force holding the device to the box 376 is less than the force bonding the device to the receptor substrate 390.

In another approach, the box 376 has vias that can be used to push the device out of the box 376 and into the receptor substrate 390. This pushing can be done in different ways, such as using microrod arrays or by pneumatic means. For pneumatic structures, disconnect the selected device. For microrods, the selected device is moved toward the receptor substrate 390 by passing the microrod through its associated via. The microrods can have different temperatures to facilitate transfer. After the transfer of the selected device is complete, the micrometer rods are retracted and the same rods are aligned with the vias of another set of microdevices, or a new device is transferred using the set of vias aligned with the new selected microdevice.

In one embodiment, the box 376 can be stretched to increase device spacing within the box 376 to increase throughput. For example, if the box 376 is 1 × 1 cm ² with a device pitch of 5 microns and a pixel pitch of the receptor substrate 390 (e.g., a display) of 50 microns, the box 376 can be filled with 200 × 200 (40,000) pixels at a time . However, if the box 376 is stretched to 2 × 2 cm ² with a device pitch of 10 microns, the box 376 can be filled with 400 × 400 (160,000) pixels at a time. In another instance, the cartridge 376 may be stretched such that at least two microdevices on the cartridge 376 become aligned with two corresponding locations in the receptor substrate. This stretching can be done in one or more directions. Cassette substrate 376 may include or consist of a stretchable polymer. The microdevice is also fixed in another layer or the same layer as the cassette substrate 376.

Combinations of the methods described above may also be used to transfer microdevices from cassette 376 to receptor substrate 390.

During the production of the cassette (temporary substrate) 376, the microdevice can be tested to identify different defects and device performance. In one embodiment, the device can be biased and tested before the top electrode is separated. If the device is an emissive device, a camera (or sensor) can be used to extract defects and device performance. If the device is a sensor, stimulation can be applied to the device to extract defects and performance. In another embodiment, top electrodes 332 may be patterned into groups for testing before patterning into individual devices. In another example, a temporary common electrode between more than one device is deposited or coupled to the device to extract device performance and/or extract defects.

The methods described above with respect to Figures 3A-3D - including but not limited to separation, formation of filler layers, different actions of filler layers, testing, and other structures - can be used for other structures including the structures described below.

The methods discussed here for transferring microdevices from cassette (temporary substrate) 376 to receptor substrate 390 are applicable to all cassette and receptor substrate configurations presented here.

The device on the donor substrate 310 can be produced with two contacts 332 and 380 on the same side facing away from the donor substrate 310 . In this embodiment, the conductive layer on box 376 may be patterned to independently bias the two contacts 332 and 380 of the device. In one case, the device may be transferred directly from the cassette substrate 376 to the receptor substrate 390. Here, the contacts 332 and 380 may not be directly bonded to the receptor substrate 390, that is, the receptor substrate 390 does not need to have special pads. In this case, a conductive layer is deposited and patterned to connect contacts 332 and 380 to the appropriate connections in receptor substrate 390. In another embodiment, the device may first be transferred from the cassette 376 to a temporary substrate before being transferred to the recipient substrate 390. Here, contacts 332 and 380 may be bonded directly to receptor substrate pad 382. The device can be tested in the box 376 or on a temporary substrate.

In another embodiment shown in Figure 4A, a mesa structure as described above is created on a donor substrate by etching through different layers, such as a first bottom conductive layer 412; a functional layer 414, e.g. the light-emitting layer; and the second top conductive layer 416 formed with microdevice structures. Top contact 432 may be deposited before or after etching on top of top conductive layer 416 .

The temporary substrate 476 includes a plurality of grooves 476-2 initially filled with a filler material, such as a soft material such as a polymer or a solid material such as _SiO2 , SiN, or the like. Groove 476-2 is beneath the surface and/or substrate bonding layer 478. The device is transferred to temporary substrate 476 on top of slot 476-2 and includes contact pads 432. Furthermore, each microdevice may include other passivation layers and/or MIS layers 472 surrounding each microdevice for isolation and/or protection. Filling material 474 may be used to fill the spaces between devices. After post-processing the device, another lower contact pad 480 may be deposited on an opposing surface of the device. Prior to depositing lower contact pad 480, contact layer 412 may be thinned. Next, the filler material 474 may be removed, and the trench may be evacuated by any suitable means, such as chemical etching or evaporation, to cause or facilitate release of the surface and/or selected regions of the bonding layer 478 . The device can be transferred to the system (receptor) substrate 490 using a process similar to that previously described above. Additionally, in another embodiment, forces exerted from pad 432, such as push or pull forces, may damage the surface above evacuated trench 476-2 and/or bonding layer 478 while maintaining unselected mesa structures attached. to the temporary baseboard. This force can also release the device from the temporary base plate 476, as shown in Figures 4B and 4C. The depth of slot 476-2 may be selected to manage some microdevice height differences. For example, if the height difference is H, the depth of the groove can be greater than H.

The device on the substrate 310 can be produced with two contacts 432 and 480 on the same side facing away from the substrate 310 . In this case, the conductive layer on box 476 can be patterned to independently bias the two contacts of the device. In one case, the device can be transferred directly from the cassette substrate 476 to the recipient substrate. Here, contacts 432 and 480 will not be directly bonded to the receptor substrate (the receptor substrate does not need to have special pads). In this case, a conductive layer is deposited and patterned to connect contacts 432 and 380 to the appropriate connections in the receptor substrate. In another case, the device may be transferred from the cassette 476 to the temporary substrate before being transferred to the recipient substrate. Here, contacts 432 and 480 can be bonded directly to the receptor substrate pads. The device can be tested in a box or on a temporary substrate.

In another embodiment shown in Figure 5A, a mesa structure as described above is created on a donor substrate 510 by etching through different layers, such as a first bottom conductive layer 512; a functional layer 514, For example, the light emitting layer; and the second top conductive layer 516 is formed with a microdevice structure. Top contact pad 532 may be deposited before or after etching on top of top conductive layer 516 . Furthermore, each microdevice may include additional passivation and/or MIS layers 572 surrounding each microdevice for isolation and/or protection. In this embodiment, the device may be provided with different anchors whereby the anchors retain the device to the donor substrate 510 after the device is peeled off. This peeling can be performed by laser. In the example, the laser only scans the device. In embodiments, a mask may be used that has openings for the device only on the backside of the donor substrate 510 to block laser light from other areas. The mask may be separate from the donor substrate 510 or may be part of the donor substrate. In another case, another substrate can be attached to the device to hold the device before the stripping process. In another case, a filler layer 574, such as a dielectric, may be used between devices.

In the first illustrated case, layer 592 provides for retaining the device to donor substrate 510 . Layer 592 may be a separate layer or a portion of the layers of the microdevice that was not etched during creation of the mesa structure. In another case, layer 592 may be a continuation of one of layers 572. In this case, layer 592 may be a metal layer or a dielectric layer (SiN or SiO ₂ or other materials). In another case, the anchor is created as a separate structure including extensions 594, voids/gaps 596, and/or bridges 598. Here, a sacrificial layer having the same shape as void/gap 596 is deposited and patterned. Next, an anchoring layer is deposited and patterned to form bridges 598 and/or extensions 594. The sacrificial material may later be removed to create void/gap 596. Extension 594 may also be avoided. Similar to the previous anchor 592, the other anchor may be constructed from different structural layers. In another case, the filling layer 574 acts as an anchor. In this case, fill layer 574 may be etched or patterned, or left as is.

Figure 5B shows the sample after the filler layer 574 is removed and/or etched to form anchors. In another instance, after peeling off, the adhesion of the bridging layer 598 is sufficient to hold the device in place and act as an anchor. For illustration purposes only, the final device is shown on the right side of Figure 5B in one substrate 510. One or a combination of these devices can be used in the substrate.

As shown in Figure 5C, the anchors can cover at least a portion of the perimeter of the device or the entire perimeter of the device, or they can be patterned to form arms 594 and 592. Either of these structures can be used with any anchoring structure.

Figure 5D shows an example of transferring a device to a receptor substrate 590. Here, the microdevice is bonded to pad 582 or placed in a predetermined area without any pads. Pressure or separation forces can release the anchor by breaking it. In another case, temperature can also be used to release the anchor. The temperature can be controlled to increase the viscosity of the layer between the microdevice exfoliation and the donor substrate 510 to act as an anchor. Figure 5E shows the device after transfer to the recipient substrate 590 and shows possible release points 598-2 in the anchor. Anchors may also be connected to the donor substrate 510 directly or indirectly through other layers.

The device on the donor substrate 510 can be produced with two contacts 532 and 480 on the same side facing away from the donor substrate 510 . In one case, the device can be transferred directly from donor substrate 510 to acceptor substrate 590. Here, contacts 532 and 480 may be bonded directly to receptor substrate pad 582. The device can be tested in the donor substrate 510 or in a cassette. In another embodiment, the device may first be transferred from the donor substrate 510 to the cassette substrate before being transferred to the acceptor substrate 590. Here, the contacts 532 will not be directly bonded to the receptor substrate 590 , ie, the receptor substrate 590 does not need to have special pads 582 . In this case, a conductive layer is deposited and patterned to connect contacts 532 to the appropriate connections in receptor substrate 590.

System substrates or receptor substrates 390, 490, and 590 may include micro-LEDs, organic LEDs, sensors, solid-state devices, integrated circuits, MEMS (micro-electromechanical systems), and/or other electronic components. Other embodiments relate to pixel array patterning and placement of microdevices to optimize microdevice utilization during selective transfer. The system substrate or receptor substrate 390, 490 and 590 may be, but is not limited to, a printed circuit board (PCB), a thin film transistor backplane, an integrated circuit substrate, or in one case an optical microdevice such as an LED, a component of a display, e.g. Drive circuit system backplane. Patterned microdevice donor and acceptor substrates can be used in combination with different transfer techniques, including but not limited to using different mechanisms (e.g., electrostatic transfer heads, elastomeric transfer heads) or direct transfer mechanisms such as dual-function pads Pick and place.

Figure 6A shows an alternative embodiment of the mesa structure of Figures 3A-3F, wherein the mesa structure is initially unetched through all layers. Here, some portion of buffer layer 312 and/or contact layer 312 may remain during the initial steps. The mesa structure is created on the donor substrate 310. Microdevice structures are formed by etching through different layers, such as the first bottom conductive layer 312, the functional layer 314, and the second top conductive layer 316. Top contact 332 may be deposited before or after etching on top of top conductive layer 316 . The mesa structure may include other layers 372 that will be deposited and patterned before or after forming the mesa structure. These layers can be dielectric, MIS, contacts, sacrificial, etc. After the mesa structure is created, one or more filler layers 374, such as dielectric material, are used between and around the microdevices to hold the microdevices together. The microdevice is bonded to temporary substrate 376 via one or more substrate bonding layers 378 . One or more bonding layers 378 may provide one or more different forces, such as electrostatic force, chemical force, physical force, thermal force, etc. After removing the device from the donor substrate 310, as described above, additional portions of the bottom conductive layer 312 may be etched away or patterned to separate the device (Fig. 6C). Other layers such as contact bonding layer 380 may be deposited and patterned. Here, the filler layer 374 can be etched to separate the microdevices, or the sacrificial layer can be removed to separate the devices. In another embodiment, temperature may be applied to separate the device from the filler layer 374 and prepare it for transfer to the receptor substrate 390. This separation can optionally be performed as described above. In another embodiment, the filler layer 374 may be etched to form a housing, base, or anchor 375 that at least partially surrounds each microdevice, such as in the shape of a frustum or truncated pyramid, as shown in Figure 6E. Another layer may be deposited over base 375 and used to form anchor 598-2. After the additional layer 598-2 is formed, the filler base layer 375 may be left in place or removed from the anchoring device. Figure 6G shows a device with sacrificial layer 372-2. The sacrificial layer 372-2 may be removed by etching or may be thermally deformed or thermally removed.

In another embodiment, the anchors are the same as the housing 375 and are constructed from polymer, organic, or other layers after the microdevice is transferred to the cartridge 376 . Housing 375 can have different shapes. In one case, the housing may match the shape of the device. The housing side walls can be shorter than the microdevice height. The housing side walls may be connected to the microdevices prior to the transfer cycle to provide support for post-processing of the different microdevices in the box 376 and packaging of the microdevice boxes for shipping and storage. The housing sidewalls may be detached, or the connection from the device to the microdevice may be weakened before or during the transfer cycle by various means such as heating, etching, or exposure.

The device on the donor substrate 310 can be produced with two contacts 332 and 380 on the same side facing away from the donor substrate 310 . In this case, the conductive layer on box 376 can be patterned to independently bias the two contacts 332 and 380 of the device. In one case, the device may be transferred directly from the cassette substrate 376 to the receptor substrate 390. Here, contacts 332 and 380 will not be directly bonded to receptor substrate 390, ie, receptor substrate 390 does not need to have special pads. In this case, a conductive layer is deposited and patterned to connect contacts 332 and 380 to the appropriate connections in receptor substrate 390. In another embodiment, the device may first be transferred from the cassette 376 to a temporary substrate before being transferred to the recipient substrate 390. Therefore, contacts 332 and 380 can be bonded directly to the receptor substrate pads. The device can be tested in the box 376 or on a temporary substrate.

Due to the mismatch between the substrate lattice and the microdevice layer, the layer growth contains several defects such as dislocations, voids, etc. To reduce defects, at least one first buffer layer 6114 and/or second buffer layer 6118 may first be deposited on the donor substrate 6110 with a separation layer 6116 therebetween or adjacent thereto, and then the buffer layer 6114 and/or An active layer 6112 is deposited over 6118. The thickness of buffer layers 6114 and 6118 may be considerable, for example, as thick as donor substrate 6110. During separation (peeling) of the microdevice from the donor substrate 6110, the buffer layers 6114/6118 may also be separated. Therefore, buffer layer deposition should be repeated each time. FIG. 6H shows the structure on the substrate 6110, in which the separation layer 6116 is between the first buffer layer 6114 and the actual device layer 6112. A second buffer layer 6118 may be present between the separation layer 6116 and the device layer 6112. The second buffer layer 6118 can also prevent contaminants from the separation layer 6116 from penetrating into the device layer 6112. Buffer layers 6114 and 6118 may each include more than one layer. Separation layer 6116 may also include a stack of different materials. In one example, separation layer 6116 responds to wavelengths of light that other layers do not respond to. This light source can be used to separate the actual device 6112 from one or more buffer layers 6114/6118 and the donor substrate 6110. In another example, separation layer 6116 reacts to a chemical, while the same chemical does not affect the other layers. This chemical may be used to remove or change the properties of separation layer 6116 to separate the device from one or more buffer layers 6114/6118 and substrate 6110. This approach allows the first buffer layer 6114 to remain intact on the donor substrate 6110, and therefore, the first buffer layer can be reused for the next device generation. Some surface treatment such as cleaning or buffering can be performed before the next device deposition. In another example, one or more buffer layers 6114/6118 may include zinc oxide.

Before the separation process (stripping), the microdevices can be separated by different etching processes, as shown in Figure 6I. The etching may etch second buffer layer 6118, if present, and may etch part or all of separation layer 6116 and device layer 6112. In another example, the second buffer layer 6118 or the separation layer 6116 is not etched. After the etching step, the microdevice is temporarily (or permanently) bonded to another substrate 6150, and the separation layer 6116 is removed or modified to separate the microdevice from the first and second buffer layers 6114, 6118. As shown in Figure 6J, the first buffer layer 6114 can remain substantially intact on the donor substrate 6110.

In another embodiment shown in FIGS. 6K to 6M , layers, such as a first bottom conductive layer 312 , a functional layer 314 and a second top conductive layer 316 , may be formed in the form of islands 6212 on the donor substrate 6210 . Figure 6K shows a top view of islands 6212 formed in a microdevice array. The size of the islands 6212 can be the same as the box size or a multiple of the box size. Islands 6212 may be formed starting from or after the buffer layer 6114/6118. Here, surface treatments or gaps 6262, 6263 can be created on the surface to initiate film growth into islands (Figure 6L). To process the microdevice, the gaps may be filled with a filler layer 6220, as shown in Figure 6M. Filler 6220 may be composed of a polymer layer, a metal layer, or a dielectric layer. After processing the microdevice, filler layer 6220 may be removed.

Figure 7 highlights the process of producing a microdevice cartridge. During a first step 702, a microdevice is prepared on a donor substrate, such as 310 or 510. During this step, the device is formed and post-processing is performed on the device. During a second step 704, the device is prepared to be separated from the donor substrate 310 or 510. This step may involve securing the microdevice by using anchors, such as 375, 476-1, 592, 594, 598, or 598-2, and fillers, such as 374, 472, and 574. During the third step 706, a cassette or temporary substrate, such as 376 or 476, is formed from the preprocessed microdevices from the first step 702 and the second step 704. In one case, during this step, the microdevice is directly or indirectly bonded to the cassette substrate 376 or 476 via a bonding layer, such as 378 or 478. Next, the microdevice is separated from the microdevice cartridge substrate 376 or 476. In another embodiment, a cartridge is formed on a microdevice donor substrate, such as 510. After the device is secured to the cassette substrate 376, 476, or 510, additional processing steps may be performed, such as removing layers, such as 312, 374, 472, 574; or adding electrical layers (eg, contacts 380 or 480) or optical layers (lenses, reflectors, etc.). During a fourth step 708 , the cassette 376 or 476 is moved to a receptor substrate, such as 390 , 490 or 590 to transfer the device to the receptor substrate 390 , 490 or 590 . Some of these steps can be rearranged or combined. While the microdevice is still on a cassette substrate, such as 376 or 476, or after the microdevice has been transferred to a recipient substrate, such as 390, 490, or 590, testing step 707A may be performed on the microdevice to determine whether the microdevice is defective. . The defective microdevice may be removed or repaired in situ in step 707B. For example, a predetermined number of a set of microdevices may be tested, and if the number of defects exceeds a predetermined threshold, the entire set of microdevices may be removed, at least some of the defective microdevices may be removed, and/or the defective microdevices may be repaired at least some of the microdevices.

Figure 8 shows the steps of transferring the device from the cassette 376, 476 or 510 to the receptor substrate 390, 490 or 590. Here, during a first step 802, the cassette 376, 476 or 510 is loaded (or picked up) or, in another embodiment, the backup equipment arm is preloaded with the cassette 376, 476 or 510. During a second step 804, the cartridge 376, 476, or 510 is aligned with a portion (or all) of the receptor substrate. This alignment can be performed using dedicated alignment marks on the cartridge 376, 476 or 510 and the receptor substrate 390, 490 or 590 or using a microdevice and landing areas on the receptor substrate 390, 490 or 590. During the third step, the microdevice is transferred to the selected landing area. During the fourth step 808, if the receptor substrate 390, 490, or 590 is completely filled, the cassette substrate 376, 476, or 510 is moved to the next step, such as another receptor substrate 390, 490, in step 810. or 590. If the current receptor substrate 390, 490 or 590 requires further filling, additional transfer steps are performed using one or more additional cassettes 376, 476 or 510. Before a new transfer cycle, if the cassette 376, 476 or 510 does not have enough devices, the cycle begins with the first step 802. If the cassette 376, 476, or 510 has sufficient devices in step 812, then in step 814 the cassette 376, 476, or 510 is offset (or moved and aligned) to a new area of the receptor substrate 390, 490, or 590, and The new loop continues to step 806. Some of these steps may be combined and/or rearranged.

Figure 9 shows the steps of transferring a device from a cassette, such as temporary substrate 376, 476 or 510, to a recipient substrate, such as 390, 490 or 590. Here, during a first step 902, the cassette 376 or 476 is loaded (or picked up), or in another embodiment, the backup equipment arm is preloaded with the cassette. During the second step 902-2, a set of microdevices is selected in the bin 376, 476 or 510 such that the number of defects therein is less than a threshold. During a third step 904, the cartridge 376, 476, or 510 is aligned with a portion (or all) of the receptor substrate. This alignment can be performed using dedicated alignment marks on the cassette 376, 476 or 510 and/or the receptor substrate 390, 490 or 590 or using a microdevice and landing areas on the receptor substrate 390, 490 or 590. Next, during a third step 906, the microdevice may be transferred to the selected landing area. In optional step 906-1, selected microdevices in the cartridge may be connected to the receptor substrate. In optional step 906-2, the connection of the microdevice to the receptor substrate may be tested, for example by turning on the microdevice by biasing through the receptor substrate 390, 490 or 590. If individual microdevices are found to be defective or non-functional, an additional adjustment step 906-3 may be performed to correct or repair some or all of the non-functional microdevices.

If the receptor substrate is completely filled, the receptor substrate 390, 490 or 590 moves to the next step. If the receptor substrate 390, 490 or 590 requires further filling, additional transfer steps from one or more additional cassettes 376, 476 or 510 are performed. If 376, 476 or 510 does not have sufficient devices before a new transfer cycle, the cycle begins with the first step 902. If the cassette 376, 476 or 510 has sufficient devices, then in step 902-2, the cassette 376, 476 or 510 is offset (or moved and aligned) to a new area of the receptor substrate 390, 490 or 590.

Figure 10 shows exemplary process steps for generating multiple types of microdevice boxes 376, 476, 510, or 1108. During a first step 1002, at least two different microdevices are prepared on different donor substrates, such as 310 or 510. During this step, the device is formed and post-processing is performed on the device. During a second step 1004, the device is prepared to be separated from a donor substrate, such as 310 or 510. This step may involve securing the microdevice by using anchors, such as 375, 476-1, 592, 594, 598, and 598-2, and fillers, such as 374, 472, and 574. During a third step 1006, the first device is moved to box 376, 476, 510, or 1108. During a fourth step 1008, at least a second microdevice is moved to box 376, 476, 510, or 1108. In one case, during this step, the microdevice is directly or indirectly bonded to the cassette substrate 376, 476, 510, or 1108 via a bonding layer, such as 378 or 478. Next, the microdevice is separated from the microdevice cassette substrate 310 or 510. For direct transfer, different types of microdevices can have different heights. For example, a second type of microdevice transferred to cassette 376, 476, 510, or 1108 may be slightly higher than a first type of microdevice (or, for the second microdevice type, on cassette 376, 476, 510, or 1108 The position can be slightly higher). Here, after the box 376, 476, 510, or 1108 is completely filled, the microdevice height may be adjusted to flatten the surface of the box 376, 476, 510, or 1108. This can be done by adding material to shorter microdevices or removing material from taller devices. In another instance, the landing areas on the receptor substrate 390, 490, or 590 may have different heights associated with differences in the cartridges 376, 476, 510, or 1108. Another method of filling boxes 376, 476, 510 or 1108 is based on picking. The microdevice can be moved to cassette 376, 476, 510, or 1108 using a pick-up process. Here, the force elements on the pick-up head may be uniform for microdevices in a cluster of one of cassettes 376, 476, 510, or 1108, or a single force element may be used for each microdevice. Furthermore, the microdevice may be moved to box 376, 476, 510, or 1108 in other ways. In another embodiment, additional devices are moved away from the cassette substrate 376, 476, 510, or 1108 of the first or second (or third or other) microdevice and other types of microdevices are transferred to the cassette 376, In the empty space on 476, 510 or 1108. After the device is secured to the cassette substrate 376, 476, 510, or 1108, other processing steps may be performed, such as adding filler layers 374, 474, or 574; removing some layers; or adding electrical layers (e.g., contacts 380, 480 or 580) or optical layer (lens, reflector). The device can be tested after or before it is used to fill receptor substrate 390, 490, or 590. The test can be electrical or optical or a combination of both. This test identifies defects and/or performance of the device on the box. During the last step 1010, the cassette 376, 476, 510 or 1108 is moved to the receptor substrate 390, 490 or 590 to transfer the device to the receptor substrate 390, 490 or 590. Some of these steps can be rearranged or combined.

The transfer process described herein (eg, Figures 7, 8, 9, and 10) may include a stretching step to increase the spacing of the microdevices on the cartridge 376, 476, 510, or 1108. This step can be performed before alignment or as part of the alignment step. This step can increase the number of microdevices aligned with the landing areas (or pads) on the receptor substrate 390, 490, or 590. Additionally, this step may match the spacing between microdevice arrays including at least two microdevices on the cassette 376, 476, 510, or 1108 to match the landing areas (or pads 382) on the receptor substrate 390, 490, or 590 spacing.

FIG. 11 shows an example of a multi-type microdevice cassette 1108 similar to temporary substrate 376, 476, or 510. Box 1108 contains three different types, eg, colors (red, green, and blue) of microdevices 1102, 1104, 1106. But many more device types can exist. The distances x1, x2, x3 between the microdevices are related to the spacing of the landing areas in the receptor substrate 390, 490 or 590. There may be different spacings x4, y2 after several devices that may be related to the pixel spacing in the receptor substrate 390, 490 or 590. This pitch compensates for the mismatch between pixel pitch and microdevice pitch (landing area pitch). In this case, if pick and place is used to create the cassette 1108, the force elements may take the form of columns corresponding to each microdevice type, or the force elements may be separate elements for each microdevice.

FIG. 12 shows an example of a multi-type microdevice cassette 1208 similar to temporary substrate 376, 476, or 510. Box 1208 contains three different types, eg, colors (red, green, and blue) of microdevices 1202, 1204, 1206. Other areas 1206-2 may be empty, filled with spare microdevices, or contain a fourth different type of microdevices. The distances x1, x2, x3 between the microdevices are related to the spacing of the landing areas in the receptor substrate 390, 490 or 590. There may be different spacings x4, y2 after several arrays of devices possibly related to the pixel spacing in the receptor substrate 390, 490 or 590. This pitch compensates for the mismatch between pixel pitch and microdevice pitch (landing area pitch).

Figure 13 shows an example of a microdevice 1302 prepared on a donor substrate 1304 similar to donor substrate 310 or 510 prior to transfer to a multi-type microdevice cassette 376, 476, 510, 1108, 1208. Here, support layers 1306 and 1308 may be used with a single device or a group of devices. Here, the spacing may match the spacing in the boxes 376, 476, 510, 1108, 1208, or the spacing may be a multiple of the box pitch.

In all of the above structures, the microdevice can be moved from the first cassette to the second cassette before filling the substrate with the microdevice. Additional processing steps may be performed after the transfer, or some of the processing steps may be divided between the first cassette structure and the second cassette structure.

Figure 14A shows an embodiment of a microdevice in a donor substrate 1480 similar to donor substrate 310 or 510. Due to manufacturing defects and material defects, the output power of the microdevice may gradually decrease or increase on the donor substrate 1480, that is, there is a non-uniformity, as shown by the coloration from dark to light. Since devices may be transferred together into a block, such as block 1482, or devices may be transferred sequentially one or more at a time into receptor substrates 390, 490, or 590, adjacent ones of receptor substrates 390, 490, or 590 The device gradually degrades. However, a worse problem may occur where one block, such as 1482, or a series of adjacent blocks ends and another block, such as 1483, or another series of blocks begins, such as along the intersection line 1484, which may result in the output A sudden change in performance, as shown in Figure 14B. This sudden change can cause visual artifacts in optoelectronic devices such as displays.

To address the issue of non-uniformity, one embodiment shown in Figure 14C includes using separate blocks 1482 and 1483 above and below the display to deflect or stagger the individual blocks so that the edges or intersections of the blocks The lines are not clear lines, thus eliminating the crossing lines 1484, and thereby, the device blocks create a skewed pattern on the display. Therefore, the average impact of sharp transitions is significantly reduced. The skew can be random and can have different profiles.

Figure 14D shows another embodiment in which micromechanical devices in adjacent blocks are flipped so that devices with similar performance are adjacent to each other, for example, the performance in the first block 1482 decreases from the first outside A to the first inside B , while the performance of the second adjacent block 1483 increases from the second inner side B adjacent to the first inner side B to the second outer side A, this can keep the changes and transitions between blocks very smooth and eliminate long sharp intersections 1484 .

Figure 14E shows an exemplary combination of flipping devices, eg, alternating high performance devices with low performance devices on the inside and beveling the edges to further improve average uniformity. In the embodiment shown, the device performance alternates between high and low in both directions, namely in adjacent horizontal blocks and in adjacent vertical blocks.

In one case, the performance of the microdevices at the edge of the block is matched to adjacent transferred blocks (arrays) prior to transfer to receptor substrate 390, 490, or 590.

Figure 15A shows the use of two or more blocks 1580, 1582 to populate blocks in a receptor substrate 1590. In the embodiment shown, skew or flip methods can be used to further improve average uniformity, as shown in Figure 15B. The higher (or lower) output power sides B and C from blocks 1580 and 1582 respectively can be positioned adjacent to each other, in addition to biasing the connections between blocks using the connections of the blocks above and below the blocks. Oblique or staggered. Furthermore, a random or defined pattern may be used to fill a box or receptor substrate 1590 with more than one block.

Figure 16A shows a sample with more than one block 1680, 1682, and 1684. Blocks 1680, 1682, and 1684 may be from the same donor substrate 310 or 510 or from different donor substrates 310 or 510. Figure 16B shows an example of filling box 1690 with different blocks 1680, 1682, and 1684 to eliminate any non-uniformity found in the blocks.

Figures 17A and 17B show a structure with multiple boxes 1790. As described above, the location of the cartridge 1790 is selected in a manner that eliminates overlap of the same area in the receptor substrate 390, 490, 590, or 1590 with a cartridge 1790 having the same microdevice during different transfer cycles. In one example, the cassettes 1790 can be independent, meaning that a separate arm or controller handles each cassette independently. In another embodiment, the alignment may be performed independently, but other operations may be performed simultaneously. In this embodiment, the receptor substrate 390, 490, 590, or 1590 is movable for easy transfer after alignment. In another example, the boxes 1790 are moved together for easy transfer after alignment. In another example, both the cartridge 1790 and the receptor substrate 390, 490, 590, or 1590 are removable to facilitate transfer. In another case, the box 1790 may be assembled in advance. In this case, a frame or base plate may hold the assembled box 1790.

The distances X3, Y3 between boxes 1790 may be multiples of the widths X1, X2 or lengths Y1, Y2 of the boxes 1790. The distance can be a function of movement steps in different directions. For example, Movement steps made directly or indirectly). The same applies to the distance Y3 between boxes 1790 and the lengths Y1 and Y2. As shown in Figure 17A, the box 1790 can be aligned in one or two directions. As shown in Figure 17B, in another example, the box 1790 is misaligned in at least one direction. Each cartridge 1790 may have independent controls for applying pressure and temperature to the receptor substrate 390, 490, 590, or 1590. Other arrangements are possible depending on the direction of movement between receptor substrate 390, 490, 590 or 1590 and cartridge 1790.

In another example, the cartridge 1790 may have different devices and thus fill different areas in the receptor substrate 390, 490, 590, or 1590 with different devices. In this case, the relative positions of the cassette 1790 and the receptor substrate 390, 490, 590 or 1590 change after each transfer cycle to fill the different areas with all the required microdevices from the different cassettes 1790.

In another embodiment, several arrays of boxes 1790 are prepared. Here, after transferring the devices from the first cassette array to the receptor substrate 390, 490, 590 or 1590, the receptor substrate 390, 490, 590 or 1590 is moved to the next microdevice array to fill the receptor substrates 390, 490 , 590 or the remaining areas in 1590 or receive different devices.

In another example, the cassette 1790 may be on a curved surface, and thus circular movement will provide contact points to transfer the microdevice into the receptor substrate 390, 490, 590, or 1590.

The vertical optoelectronic stack layer includes a substrate, an active layer, at least one buffer layer between the active layer and the substrate, and at least one separation layer between the buffer layer and the active layer, wherein the buffer layer can be maintained at On the substrate, the active layer is physically removed from the substrate by changing the properties of the separation layer.

In one embodiment, the process of changing the properties of the one or more separation layers includes chemically reactive etching or deformation of the separation layers.

In another embodiment, changing the properties of the one or more separation layers includes exposure to photoelectron waves, thereby deforming the separation layers.

In another embodiment, changing the properties of the one or more separation layers includes changing the temperature, thereby deforming the separation layers.

In one embodiment, reusing the buffer layer to create new optoelectronic stack layers involves surface treatment.

In one embodiment, the surface treatment uses chemical or physical etching or polishing.

In another embodiment, surface treatment uses deposition of additional thin or buffer layers to reform the surface.

In one embodiment, the optoelectronic device is an LED.

In one embodiment, the separation layer is zinc oxide.

Embodiments of the present invention include continuous pixelated structures that include fully or partially continuous active layers, pixelated contact layers, and/or current spreading layers.

In this embodiment, there may be a pad layer and/or a bonding layer on top of the pixelated contact layer and/or current spreading layer.

In the above embodiments, there may be a dielectric opening on top of each pixelated contact layer and/or current spreading layer.

Another embodiment includes a donor substrate including microdevices having bonding pads and a filler layer filling spaces between the microdevices.

Another embodiment includes a temporary substrate that includes a bonding layer to which microdevices from the donor substrate are bonded.

Another embodiment includes a heat transfer technique that includes the following steps:

1) Align the microdevice on the temporary substrate with the bonding pads on the system substrate;

2) Verify that the melting point of the bonding pads on the system substrate is higher than the melting point of the bonding layer in the temporary substrate;

3) Produce a thermal profile that melts both the bonding pad and the bonding layer and thereafter causes the bonding layer to remain melted and the bonding pad to remain solid; and

4) Separate the temporary base board from the system base board.

In another embodiment of the transfer technique, the thermal profile is generated by local or global heat sources or both.

Another embodiment includes a microdevice structure wherein at least one anchor retains the microdevice to the donor substrate after the microdevice is released from the donor substrate by a lift-off process.

Another embodiment includes a transfer technique for a microdevice structure in which an anchor releases the microdevice after or during bonding of the microdevice to a pad in a recipient substrate by push or pull force.

In another embodiment, the anchor according to the microdevice structure consists of at least one layer extending from the side of the microdevice to the substrate.

In another embodiment, the anchor according to the microdevice structure consists of a void or at least one layer on top of a void.

In another embodiment, an anchor according to a microdevice structure consists of a filling layer surrounding the device.

Another embodiment includes a structure according to a microdevice structure, wherein the viscosity of the layer between the exfoliated microdevice and the donor substrate is increased by controlling the temperature to act as an anchor.

Another embodiment includes a release process for an anchor in a microdevice structure, where the temperature is adjusted to reduce the force between the anchor and the microdevice.

Another embodiment includes a process of transferring a microdevice into a receptor substrate, wherein the microdevice is formed in a cassette; aligning the cassette with a selected landing area in the receptor substrate; and associating the cassette with the selected landing area The microdevice is transferred to the receptor substrate.

Another embodiment includes a process of transferring microdevices into a recipient substrate, wherein the microdevices are formed in a cassette; selecting a set of microdevices in which defective microdevices are less than a threshold; and combining the selected set of microdevices in the cassette with Aligning the selected landing area in the receptor substrate; and transferring the microdevice associated with the selected landing area in the cassette to the receptor substrate.

Embodiments include cassettes with multiple types of microdevices transferred therein.

Embodiments include microdevice cassettes in which a sacrificial layer separates at least one side of the microdevice from a filler layer or a bonding layer.

In embodiments, the sacrificial layer is removed to release the microdevice from the filler layer or bonding layer.

In embodiments, the sacrificial layer releases the microdevice from the filler under certain conditions such as high temperature.

The microdevice can be tested to extract information related to the microdevice, including but not limited to defects, uniformity, operating conditions, etc. In one embodiment, one or more microdevices are temporarily bonded to a cartridge having one or more electrodes for testing the microdevices. In one embodiment, the other electrode is deposited after the microdevice is positioned in the cassette. This electrode can be used to test microdevices before or after patterning. In one embodiment, the cartridge is placed in a predetermined position (the predetermined position may be a holder). The cassette and/or receptor substrate are moved for alignment. At least one selected device is transferred to the receptor substrate. If more microdevices become available on/in the cassette, the cassette or receptor substrate is moved to align with a new area or receptor substrate in the same receptor substrate, and at least one other selected device is moved to the new location. This process can continue until the cartridge does not have enough microdevices, at which point a new cartridge can be placed in the predetermined position. In one example, transfer to the selected device is controlled based on information extracted from the box. In one example, defect information extracted from the cassette can be used to limit the number of defective devices transferred to the recipient substrate to below a threshold number by eliminating transfers to a set of devices with a number of defects above a threshold, or so The cumulative number of transfer defects will exceed the threshold. In another example, the boxes will be binned based on one or more extracted parameters, and each bin will be used for a different application. In another case, cassettes with similar performance based on one or more parameters will be used in a receptor substrate. The examples presented here can be combined to improve cartridge transfer performance.

In embodiments, physical contact and pressure and/or temperature may be used to transfer the device from the cassette to the receptor substrate. Here, pressure and/or temperature can create bonding forces (clamping forces) for holding the microdevice to the receptor substrate, and/or temperature can reduce the contact force between the microdevice and the cartridge. Thus, transfer of the microdevice to the receptor substrate is achieved. In this case, the location assigned to the microdevice on the receptor substrate may have a higher profile compared to the rest of the receptor to enhance the transfer process. In an embodiment, the cassette does not have microdevices in areas that may come into contact with unused areas of the receptor substrate, such as locations assigned to other types of microdevices during the transfer process. These two instances can be combined. In embodiments, the assigned location of the microdevice on the substrate may have been wetted with an adhesive or may have been covered with a bonding alloy, or additional structures may have been placed at the assigned location. During the stamping process, separate boxes, printing or other processes may be used. In embodiments, selected microdevices on the cartridge can be moved closer to the receptor substrate to enhance selective transfer. In another case, the receptor substrate exerts a pulling force to assist or initiate transfer of the microdevice from the cassette. Pull forces can be combined with other forces.

In one embodiment, the housing may support the microdevice in the cartridge. The housing can be made around or separately from the microdevice on the donor substrate or cassette substrate, and then the microdevice is moved inside and bonded to the cassette. In one embodiment, at least one polymer (or another type of material) can be deposited on top of the cassette substrate. Microdevices from the donor substrate are pushed into the polymer layer. The microdevice is selectively or generally separated from the donor substrate. This layer can be cured before or after separation of the device from the donor substrate. This layer can be patterned, especially if multiple different devices are integrated into the box. In this case, the layer may be created for one type, in which the microdevice is buried and separated from its donor. Next, another layer is deposited and patterned for the next type of microdevice. Next, the second microdevice is buried in the associated layer. In all cases, this layer may cover some or all of the microdevices. In another case, the housing is constructed from polymer, organic, or other layers after the microdevice is transferred to the cartridge. The housing can have different shapes. In one case, the housing may match the shape of the device. The housing side walls can be shorter than the microdevice height. The housing side walls can be attached to the microdevice prior to the transfer cycle to provide support for post-processing of different microdevices in the cassette and packaging of the microdevice cassette for shipping and storage. The housing sidewalls may be detached, or the connections from the device to the microdevice may be weakened before or during the transfer cycle by various means such as heating, etching, or exposure. There may be contact points holding the microdevice to the cassette substrate. The contact point to the box can be the bottom or top side of the device. Contact points can be weakened or eliminated before or during transfer by various means such as heat, chemical processes or exposure. This process can be performed for a few selected devices or it can be performed globally for all microdevices on the box. The contacts may also be conductive to enable testing of the microdevice by biasing the device at the contacts and other electrodes connected to the microdevice. During the transfer cycle, the cassette can be under the receptor substrate to prevent the microdevice from falling out of the housing if the contacts are globally removed or weakened.

In one embodiment, a microdevice cassette may include at least one anchor to secure the microdevice to a surface of the cassette. The cassette and/or receptor substrate are moved such that some microdevices in the cassette are aligned with certain locations in the receptor substrate. This anchor can break under pressure during pushing of the cassette and receptor substrate toward each other or pulling the device by the receptor substrate. The microdevice can remain permanently on the receptor substrate. The anchors can be on the sides of the microdevice or on the top (or bottom) of the microdevice.

The top side is the side of the device facing the box and the bottom side is the opposite side of the microdevice. The other sides are called sides or side walls.

In one embodiment, a microdevice may be tested to extract information related to the microdevice, including but not limited to defects, uniformity, operating conditions, etc. The box can be placed in a predetermined position (which can be a holder). The cassette and/or receptor substrate can be moved for alignment. At least one selected microdevice can be transferred to the recipient substrate. If more microdevices become available on/in the cassette, the cassette or receptor substrate can be moved to align with a new area or new receptor substrate in the same receptor substrate, and at least one other selected device can be transferred to the new Location. This process can continue until the box does not have enough microdevices, at which point a new box will be placed in the predetermined position. In one case, transfer to the selected device may be controlled based on information extracted from the box. In one case, defect information extracted from the cassette may be used to transfer a number of defective devices to be transferred to a recipient substrate by eliminating a set of microdevices where the number of defects exceeds a threshold or the cumulative number of transferred defects exceeds a threshold. Limit to below threshold number. In another case, the boxes will be binned based on one or more extracted parameters, and each bin can be used for a different application. In another instance, cassettes with similar performance based on one or more parameters can be used in one receptor substrate. The examples presented here can be combined to improve cartridge transfer performance.

One embodiment includes a method of transferring a device to a receptor substrate. This method contains:

a) Preparing a cassette having a substrate, wherein a microdevice is positioned on at least one surface of the cassette substrate, and the substrate has a greater Multiple microdevices.

b) Test the device on the box by extracting at least one parameter.

c) Pick up the cassette or transfer the cassette to a location with the microdevice facing the receptor substrate.

d) Use the test data to select a set of microdevices on the box.

e) Align the selected set of microdevices on the cassette with the selected locations on the receptor substrate. The set of microdevices is transferred from the cassette to the recipient substrate.

f) Processes d and e can continue until the box does not have any useful devices or the receptor substrate is completely filled.

One embodiment includes a cassette having more than one type of microdevice positioned in the cassette at the same spacing as in the receptor substrate.

One embodiment includes a cartridge having a substrate with microdevices positioned (directly or indirectly) on a surface thereof, and the microdevices are skewed in any column or row such that at least one edge of any column or row is not aligned with at least one other column or row. Row edges aligned.

One embodiment is a method of transferring a device to a receptor substrate. The method includes transferring an array of microdevices into a substrate, wherein edges of the transferred microdevices of at least any column or row are not aligned with edges of transferred devices of at least another column or row.

One embodiment includes a method of transferring a device to a receptor substrate. The method includes transferring an array of devices from a donor substrate to a recipient substrate, wherein in any area on the acceptor substrate that is similar in size to the transferred array, there are at least two devices from the donor substrate corresponding to the transferred array. Any column or row of microdevices in different areas.

One embodiment includes a process of transferring an array of microdevices into a receptor substrate, where the microdevices are deflected at the edges of the array to eliminate sudden changes.

Another embodiment includes a process for transferring a microdevice array into a recipient substrate, wherein the properties of the microdevices at adjacent edges of the two microdevice arrays are matched prior to transfer.

Another embodiment includes a process of transferring a microdevice array into a recipient substrate, wherein the microdevice array is populated from at least two different areas of a microdevice donor substrate.

Another embodiment includes a process of transferring a microdevice array from a cassette into a receptor substrate, wherein a number of microdevice cassettes are placed in different locations corresponding to different areas of the receptor substrate, followed by aligning the cassettes with the receptor substrate , and transfer the microdevice from the cassette to the receptor substrate. Different anchor solutions for fixing microdevices to donor substrates

The process of integrating microdevices into a system substrate involves creating and preparing a donor substrate, transferring a preselected array of microdevices to a recipient substrate, and subsequently (or simultaneously) electrically or mechanically bonding the microdevices to the system substrate. During bonding between two substrates, curing agents are applied before or after alignment of the microdevice and system substrates to assist in the formation of strong bonds. Curing agents include one of the following: polyamide, SU8, PMMA, BCB film layers, epoxy resins, and UV curable adhesives, and curing is performed in one of the following: electric current, light, heat, or mechanical force or chemical reaction. However, the current/voltage requirements for curing may be higher than the microdevice can withstand.

To avoid damaging microdevices, structures and methods are needed to integrate microdevices into system substrates with enhanced bonding and conductivity capabilities. And another/alternative current/voltage path can be formed to avoid damage to the microdevice.

According to one embodiment, a bonding structure may be provided. The bonding structure may include a plurality of microdevices on a donor substrate, each microdevice including one or more conductive pads formed on a surface of the microdevice; and a temporary material covering each microdevice or the one or more conductive pads At least part of the pad.

In one case, the temporary material acts as an anchor that holds the plurality of microdevices inside the housing structure in the donor substrate.

In another instance, all or part of a microdevice can be covered with a temporary conductive material, which can redirect electrical current through the temporary conductive material rather than the microdevice, and thus avoid damaging the microdevice.

In one case, the microdevice may have one conductive pad on each side of the microdevice. In another case, a microdevice may have more than one conductive pad on one side.

Figure 18 illustrates a donor substrate 1802 holding a plurality of microdevices via a donor force element in accordance with an embodiment of the present invention. Donor substrate 1802 may be a growth substrate onto which the microdevice is fabricated or grown or another temporary substrate that has been transferred thereon. The following is described with reference to gallium nitride (GaN) based LEDs, however the structure currently described can be used for any type of LED with different material systems.

Basically, GaN-based microLEDs are fabricated by depositing stacks of materials on a sapphire substrate. Conventional GaN LED devices include a substrate such as sapphire, an n-type GaN layer or buffer layer (such as GaN) formed on the substrate, an active layer/semiconductor layer such as a multi-quantum well (MQW) layer, and a p-type GaN layer.

As shown in FIG. 18 , the plurality of microdevices on the donor substrate 1802 may have conductive pads 1814 , 1816 on both the top and bottom of the stack 1806 of semiconductor layers. The receptor substrate 1808 has at least one receptor force element 1818 for each selected microdevice selected for transfer to the receptor substrate 1808 . In one case, the force-receiving element is a current/voltage curable component. Here, current/voltage 1810 is applied to the selected force-receptive element (eg, 1818), causing it to harden and hold the microdevice in place. In one example, the force-receptor element may include monomers that form polymers under applicable charges. In another example, the force-receiving element is a medium with high resistance traces that generate heat under applicable current/voltage, and the heat generated causes local solidification of the medium.

Donor substrate 1802 has at least one donor force element 1804. Force-donor element 1804 is an element that loses its adhesive properties when exposed to electrical current or voltage. Here, voltage/current 1812 is applied to the donor force element 1804 holding the selected device for transfer. In one example, the force-donor element is a polymer that decomposes (oxidizes) under the application of a charge. In another example, the force donor element is a highly resistive trace that ignites at the applicable current/voltage.

Figure 19 shows a microdevice with more than one conductive pad on one side in accordance with an embodiment of the present invention. Here, in one example, the microdevice may have two conductive/contact pads 1904, 1906 at the bottom of the semiconductor layer stack on the donor substrate 1902. The receptor substrate 1908 has a receptor force element 1918 that corresponds to a contact pad for each microdevice selected for transfer to the receptor substrate 1908 . The force-receiving element is a current/voltage curable component. Here, current/voltage 1910 is applied to the selected force-receptor element (eg, 1918), causing it to harden and hold the microdevice in place.

Voltage/current 1910, 1912 may be applied to selected force-receptor elements (eg, 1918) to solidify them, causing them to harden and hold the microdevice in place.

In one case, the microdevice can be used as part of a bias loop. Here, voltage/current 1914 may be applied via donor substrate 1902, or voltage/current 1910, 1912 may be applied to acceptor substrate 1908 through the microdevice and through either donor substrate 1902 or acceptor substrate 1908.

However, the current/voltage requirements for curing the force-receptor element may be higher than the microdevice can withstand. To avoid damaging the microdevice, another/alternative current/voltage path may be formed. In another instance, part of a microdevice or the entire microdevice can be covered with a temporary conductive material, which can redirect electrical current through the temporary conductive material instead of the microdevice and avoid damaging the microdevice.

20A-20I illustrate examples of microdevices partially/fully covered with temporary conductive material in accordance with some embodiments of the present invention.

Part or all of the microdevice can be covered with a temporary conductive material, which can redirect electrical current through the temporary conductive material rather than the microdevice, and thus avoid damage to the microdevice. In one case, the temporary material may be a temporary conductive material. The conductive material can be connected as a sheet or trace to the same conductive material or a different conductive material on the donor substrate.

In one embodiment, the microdevice may be inside the housing structure. There may be some sacrificial layer between the housing wall and the microdevice. In another embodiment, there may also be bonding material between the donor substrate and the microdevice and the conductive pad (a material similar to the housing wall) or a combination thereof.

In one embodiment, the temporary layer may also act as an anchor to hold the device in place. In another embodiment, there may be anchors holding the microdevice into the donor substrate. The anchors may be the same material as the shell material or a different material. In one case, the housing may extend almost to the edge of the microdevice. In another case, the housing wall is shorter than the microdevice. It is also possible to have a housing that is taller than the microdevice.

In another instance, the temporary conductive material may be replaced by a non-conductive material.

In the case of both conductive and non-conductive temporary materials, the temporary material can hold the microdevice in place after the sacrificial layer is removed or released. The microdevice can be transferred to another substrate. During the transfer process, temporary materials are removed or separated from the shell structure. The separation process can be mechanical (eg, push or pull), optical, thermal, or chemical.

The microdevice can be covered with the temporary material/layer before being transferred to the recipient substrate, or it can be covered after being transferred to the recipient substrate. In one case, the housing material is coated on the substrate between microdevices. It can be bonded to the donor substrate, and then the shell material can be cured. In another instance, there may be different materials used on the surface of the donor substrate that may be electrically coupled to the microdevice or temporary layer. In another case, the housing material is coated on top of the donor substrate. Next, the microdevice is bonded and pushed into the material, and the material then solidifies. The shell material can be epoxy, polymer, or other types of materials. In one case, BCB or polyamide can be used as the shell material.

The temporary material can be patterned to create openings on top of the donor substrate. This opening may facilitate certain processes, such as removal of the sacrificial layer, to separate the microdevice from the housing sidewall.

20A1-20A2 illustrate examples of highlighting temporary conductive material covering the surface of a microdevice in accordance with some embodiments of the invention.

Referring to Figure 20A1, here, the microdevice is inside a housing structure 2006a. There may be some sacrificial layer between the housing structure/wall 2006a and the microdevice 2016. In one case, the sacrificial layer 2008a may be a patterned sacrificial layer to cover the length of the housing. In another instance, sacrificial layer 2008b may be provided to the length of the microdevice. The bonding material 2010a, the conductive pad 2004a, or a material similar to the housing wall or a combination thereof may be used between the donor substrate and the microdevice. And the anchor 2014a can hold the microdevice in the donor substrate. The anchors may be the same material as the shell material or a different material. Temporary conductive material 2002a may cover the surface of microdevice 2016 including conductive pad 2004a and housing 2006a. This structure facilitates the transfer of microdevices to inspect defective microdevices on the system substrate.

In another embodiment, the housing wall may extend almost to the edge of the microdevice.

Figure 20A2 shows a cross-sectional view of a microdevice on a device (donor) substrate in which the temporary conductive material does not cover the entire surface of the microdevice according to an embodiment of the present invention. Here, the housing 200b and the sacrificial layer 2008b may extend almost to the edge of the microdevice 2016. Temporary conductive material 2002a may include conductive pad 2004a. Traces on the donor substrate or the conductive layer between the donor substrates may couple the conductive material to the current/voltage source.

20B1 shows a cross-sectional view of a microdevice on a device (donor) substrate with a temporary conductive material covering a portion of the microdevice's conductive pad in accordance with an embodiment of the present invention. Here, the conductive pads such as 2004c are patterned conductive pads, and the sacrificial layer 2008c is also a patterned sacrificial layer deposited around the microdevice and the conductive pads. Temporary conductive material 2002a may cover the surface of microdevice 2016 including conductive pad 2004a and a portion of housing 2006a. In another case, the sacrificial layer may extend to only a portion of the microdevice. Temporary conductive material 2002a may be coupled to a current source/voltage to promote curing or debonding. Traces on the donor substrate or the conductive layer between the donor substrates may couple the conductive material to the current/voltage source.

Figure 20B2 shows a cross-sectional view of a microdevice on a device (donor) substrate in which the temporary conductive material does not cover the entire surface of the microdevice according to an embodiment of the present invention. Here, housing 2006b may extend almost to the edge of the microdevice. Temporary conductive material 2002a may include a portion of conductive pad 2004b.

Figure 20C1 shows an example of temporary conductive material forming a current/voltage path between conductive pads 2004c, 2006c, which may be on the top and bottom or the same side of the microdevice. Here, temporary conductive material 2002c also covers the microdevice, which facilitates selective transfer of the microdevice to the system substrate. This structure helps redirect electrical current through the temporary conductive material rather than the microdevice, and thus avoids damage to the microdevice.

Figure 20C2 shows an example where there is no bonding material between the donor substrate and the microdevice. The temporary conductive material forms a current/voltage path between conductive pads 2004c, 2006c, which may be on the top and bottom or the same side of the microdevice. Temporary conductive material 2002c also covers one of the surfaces of the microdevice. Here, the temporary conductive material acts as a bonding material to the microdevice.

20D shows another example of temporary conductive material 2002d forming a current/voltage path between conductive pads 2004d, 2006d of a microdevice when the temporary conductive material 2002d and conductive pads do not cover the entire surface of the microdevice. Here, the conductive pad, such as 2004d, is a patterned conductive pad, and temporary material is deposited on the patterned conductive pad.

Figure 2OE shows another example where temporary conductive material 2002e forms a current/voltage path for more than one pad on the surface of a microdevice. Here, the conductive material shorts the conductive pads to the surface of the microdevice. Conductive material covers or is connected to pads 2004e, 2006e, 2008e, 2010e. And traces (directly or indirectly) on the donor substrate can connect some conductive materials together. Here, the conductive material can partially or completely cover the conductive pad depending on the voltage and current requirements.

Figure 2OF shows an example of conductive pads 2008f, 201Of on a surface that are not shorted together by conductive layer 2002f. Here, the pad may be fully or partially covered by conductive layer 2002f, as shown. And there is no bonding material between the donor substrate and the microdevice. The temporary conductive material acts as a bonding material for the microdevice.

Figure 20G shows another example where temporary conductive material 2002g forms a current/voltage path for more than one pad on the surface of a microdevice. Here, the conductive material forms a path between the surface facing the donor substrate and the surface remote from the donor substrate. And in one case, it shorted the pads to the surface. Here, the conductive material covers conductive pads 2012g, 2014g or is connected to conductive pads 2008g, 2010g.

Figure 20H shows an example of conductive pads 2008h, 2010h on a surface that are not shorted together by conductive layer 2002h. Here, conductive pads 2012h, 2014h may be fully covered, or conductive pads 2008h, 2010h may be partially covered, as shown. In all cases, conductive material 2004h may directly couple the surface remote from the donor substrate to the conductive layer at the donor substrate. In another case, it will indirectly couple a surface remote from the donor substrate to the conductive layer 2006h at the donor substrate.

20I1 and 20I2 illustrate examples in which there are no conductive pads on the surface away from the donor substrate. Here, there are no conductive pads on the surface of the microdevice away from the donor substrate. In this case, the temporary material 2002h holds the device in place after the sacrificial layers 2006a, 2008a are removed. The temporary material is removed or separated from the housing after the microdevice is transferred to another substrate, releasing the microdevice from the donor substrate.

21A-21D show top views of different microdevices constructed from temporary materials (conductive or non-conductive) in accordance with embodiments of the present invention. The temporary material can be patterned to create openings on top of the donor substrate. This opening may facilitate certain processes, such as removal of the sacrificial layer, to separate the microdevice from the housing sidewall. This treatment can be performed before or after the microdevice is transferred into the recipient substrate. In one case, chemical etching may be used to remove (or modify) the sacrificial layer. In another case, electromagnetic signals (eg, microwaves or light) can be used to release the device by removing/modifying the sacrificial layer. Here, the temporary layer can also act as an anchor to hold the device in place. If the temporary layer does not assist in the bonding process, it does not need to connect (or cover) the pads on the microdevice.

Figure 21A shows an exemplary top view representation of Figure 20A in accordance with an embodiment of the present invention. Here, microdevice 2102 on donor substrate 2104 has conductive pad 2106 surrounded by temporary conductive material 2108 and sacrificial layer 2110. Here, traces of conductive material on top of the donor substrate may be connected as meshes, columns or rows. There may be access points on top of the donor substrate to bias the temporary layer via traces.

Figure 21B1 shows an exemplary top view representation of Figure 20B. Here, the traces on the top of the donor substrate can be connected as meshes, columns or rows. There may be access points on top of the donor substrate to bias the temporary layer via traces. Microdevice 2102 on donor substrate 2104 has patterned conductive pad 2106-1 surrounded by sacrificial layer 2110. Traces of temporary conductive material on top of the donor substrate may be connected as meshes, columns, or rows. There may be access points on top of the donor substrate to bias the temporary layer via traces.

Figure 21B2 shows an example where the temporary material is not connected to the pad. Microdevice 2102 on donor substrate 2104 has conductive pad 2106-2 surrounded by sacrificial layer 2110, and traces of temporary conductive material on top of the donor substrate may be connected as meshes, columns, or rows. This may be used for other embodiments or related structures in the invention.

21C shows the exemplary top view representation of FIG. 20E where microdevice 2102 has more than one pad (2106-3, 2106-4) on donor substrate 2104 surrounded by temporary conductive material 2108 and sacrificial layer 2110. Here, the traces on the top of the donor substrate 2104 may be connected as meshes, columns, or rows. And the traces for each pad can be handled in separate connection groups. There may be access points on top of the donor substrate to bias the temporary layer via traces.

21D shows the exemplary top view representation of FIG. 20F, wherein microdevice 2102 has one or more patterned conductive pads (2106-3, 2106-4) on donor substrate 2104 surrounded by temporary conductive material 2108 and sacrificial layer 2110. superior. Here, the traces on the top of the donor substrate 2104 may be connected as meshes, columns, or rows. And the traces for each pad can be handled in separate connection groups. There may be access points on top of the donor substrate to bias the temporary layer via traces. Release of microdevices from donor substrate via breakable anchors

Some embodiments of the present invention illustrate that microdevices can be provided with different temporary anchors whereby the temporary anchors hold the device to the donor substrate and can selectively move toward or away from the surface of the donor substrate after the device is peeled off. Therefore, as the donor substrate becomes close to the acceptor substrate, some selected devices approach or are connected to the acceptor substrate, while other microdevices remain at a significant distance from the acceptor substrate. The temporary anchor releases the microdevice after or during bonding of the microdevice to the pad in the receptor substrate by either push or pull force. The anchor can break under pressure during pushing the donor and recipient substrates toward each other or pulling the microdevice by the recipient substrate. The microdevice can be permanently retained on the receptor substrate. The anchors can be on one side of the microdevice or at the top (or bottom) of the microdevice.

22A-22C illustrate a microdevice on a donor substrate in which the microdevice is selectively movable toward or away from a surface of the donor substrate in accordance with embodiments of the present invention.

Referring to Figure 22A, according to one embodiment, a stack includes electrodes 2204, 2206 and an electroactive polymer (EPE) layer 2208 formed under a microdevice (eg, 2210, 2212 on top of a donor substrate 2214). The movement of the donor substrate and/or the acceptor substrate causes some microdevices in the donor substrate to become aligned with some positions in the acceptor substrate. In one case, applying a voltage to the stack causes the stack to become thinner, and thus bring the device closer to the surface of the receptor substrate.

Referring to Figure 22B, according to another embodiment, a stack includes electrodes 2208, 2206 and an electroactive polymer (EPE) layer 2222 formed under a microdevice (eg, 2210, 2212 on top of a donor substrate 2214). In one case, electrodes may be disposed around the EPE layer. The EPE layer can be as thin or thick as desired. When a voltage is applied to the stack including the electrodes and the EPE layer, the stack becomes thicker. In one case, the housing and anchors may also hold the microdevices 2210, 2212 in place.

Figure 22C shows another example where stacked electrodes and microdevice 2210, 2212 structures on top of EPE 2222, 2220 are surrounded by a housing structure 2226. Additionally, anchors 2234 retain microdevices 2210, 2212 within housing structure 2226. In another case, a bonding layer may hold the microdevice on top of the stacked EPE. The housing can have different shapes. In one case, the housing may match the shape of the device. The housing side walls can be shorter than the microdevice height. The housing sidewalls can be connected to the microdevice prior to the transfer cycle to provide support for different post-processing of the microdevice.

During the transfer of microdevices 2210, 2212 from the donor substrate 2214 to the recipient substrate, the EPE stack 2222 pushes the microdevice 2210 forward. This push releases the anchor 2234 and the microdevice can be placed on the surface of the receptor substrate.

Figures 23A-23B illustrate another embodiment of a microdevice on a donor substrate, wherein the microdevice is selectively movable toward or away from the surface of the donor substrate.

In Figure 23A, according to another embodiment, stacks of different materials 2304, 2308, 2310 with different coefficients of thermal expansion are formed on top of a donor substrate 2320 below microdevices 2312, 2314, 2318, respectively. As the temperature of the stack 2308 changes, the stack 2308 becomes distorted and pushes the device 2314 further away from the surface of the donor substrate. In one case, applying a current through the stack changes the temperature. Here, electrodes 2302, 2306 can carry electrical current. In another instance, a light-absorbing layer that is part of the stack converts light into thermal energy. In another case, the stack can resonate to a specific signal frequency such as microwave or ultrasound. This resonance can increase the temperature or directly deform the stack.

Figure 23B shows another example where the microdevice 2312, 2314, 2318 structure on top of the stacked layers 2304, 2308, 2310 is surrounded by a housing 2322. Additionally, anchors 2332, 2326 retain devices 2312, 2314, and 2318 within the housing structure. The anchor can be connected to the microdevice or housing. During the transfer of device 2314 from donor substrate 2320 to recipient substrate, stack 2308 pushes microdevice 2314 forward. This push releases anchor 2326 and microdevice 2314 can be placed on the surface of the receptor substrate.

Figure 24 shows another example of a microdevice on a donor substrate in which the microdevice is selectively movable toward or away from a surface of the donor substrate in accordance with an embodiment of the present invention.

Here, the microdevice 2410, 2414, 2418 structures on top of the stack 2404 are surrounded by a housing 2422. Additionally, anchors 2426, 2428 retain devices 2410, 2414, and 2418 within the housing structure. During the transfer of device 2414 from the donor substrate to the acceptor substrate, the electroactive polymer layer changes to gas 2456, and the pressure created by this change pushes microdevice 2414 forward. This push/pull force releases anchor 2426 and microdevice 2414 can be placed on the surface of the receptor substrate. Thermal, optical, electrical or chemical forces can cause layer 2404 to change into a gas. In one instance, absorbing layer 2458 can absorb light and heat layer 2404-1 and create gas pressure that pushes the microdevice forward. Microdevice box structure

Some embodiments of the invention also disclose methods of integrating a monolithic microdevice array into a system substrate or selectively transferring a microdevice array to a system substrate.

According to one embodiment, a method for integrating a microdevice on a backplane may be provided, including: providing a microdevice substrate including one or more microdevices; and connecting pads on the microdevice to corresponding solder pads on the backplane. The disk bonds a set of selective microdevices from the substrate to the backplane; and leaves the set of bonded selective microdevices on the backplane by separating the microdevice substrate.

In one embodiment, an array of microdevices can be produced on a microdevice substrate, where the microdevices can be produced by etching one or more planar layers.

In another embodiment, one or more planarization layers can be formed on the microdevice substrate and cured by temperature, light, or other sources.

In one embodiment, an intermediate substrate may be provided, wherein, in one case, one or more bonding layers may be formed on the intermediate substrate or on the planarization layer.

In another embodiment, the microdevice substrate may be removed by laser or chemical lift-off.

In one embodiment, there may be openings in the buffer layer that allow the microdevice to connect to the planarization layer. In one case, the electrodes may be placed on top or bottom of the planarization layer.

In another embodiment, after removing the microdevice substrate, additional processing may occur, such as removing additional common layers, or thinning the planarization layer and/or the microdevice.

In one case, more pads can be added to the microdevice. The pads can be conductive or purely used for bonding to the system substrate. In one case, the buffer layer may connect at least one microdevice to the test pad. Test pads can be used to bias the microdevice and test its functionality. Testing can be done at the wafer level or at the intermediate (cassette) level. The pads are accessible at intermediate levels after removing too many layers.

In one case, the microdevice can have more than one contact at the top side, and the buffer layer can be patterned to connect the contact of at least one of the microdevice to the test pad.

In one embodiment, a backplane may be provided. In one case, the backplane may have transistors and other components for the pixel circuitry to drive the microdevice. In another case, the backplane may be a substrate without components.

In one embodiment, one or more pads may be provided on the backplane for the bonding process. In one case, pads on the backplane or on the microdevice can create a force that pulls out of the microdevice.

After the microdevice is transferred to the backplane, it is possible to detect the position/positioning of the microdevice and adjust the patterning of other layers to match the alignment during transfer. In one case, different components may be used to detect the position of the microdevice, such as a camera or probe tip. In another instance, offsets in transfer settings can be used to identify misalignments in the location of microdevices on a system substrate. In yet another case, the color filter or conversion layer may also be adjusted based on the location of the microdevice. In one case, some random shifts in microdevice position can be induced to reduce optical artifacts.

In one embodiment, the pattern on the microdevice can be modified (e.g., electrodes that couple the microdevice to a signal, functionally tunable layers such as color filters or color conversion, open vias in passivation/planarization layers, or backplane layer).

In one case, the location/shape of the electrodes may be modified based on the location of the microdevice. In another case, there may be some extension of each electrode whose position or length may be modified based on the location of the microdevice.

Figure 25A shows a cross-sectional view of a microdevice array on a microdevice substrate according to one embodiment of the present invention. Here, a microdevice substrate 2502 is provided. Microdevice array 2504 may be produced on microdevice substrate 2502. In one case, the microdevice may be a microLED. In another instance, the microdevice may be any microdevice typically manufactured in planar batches, including LEDs, OLEDs, sensors, solid state devices, integrated circuits, MEMS, and/or other electronic components.

In one case, one or more planar active layers may be formed on the substrate. The planar active layer may include a first bottom conductive layer, a functional layer (eg, a light emitting layer), and a second top conductive layer. Microdevices can be created by etching planar active layers. In one case, the etching may reach all the way to the microdevice substrate. In another case, there may be partial etching on the planar layer to leave some on the surface of the microdevice substrate. Additional layers can be deposited and patterned before or after forming the microdevice.

Figure 25B shows a cross-sectional view of a microdevice array with a buffer layer according to one embodiment of the invention. Here, buffer layer 2506 may be formed on microdevice array 2504. Buffer layer 2506 may extend over the surface of microdevice substrate 2502. The buffer layer can be electrically conductive. In one case, the buffer layer may be a patterned buffer layer. In another case, the buffer layer may be a common buffer layer. In one embodiment, buffer layer 2506 may include electrodes that may be patterned or used as a common electrode.

Figure 25C shows a cross-sectional view of a microdevice array with a planarization layer according to one embodiment of the present invention. A planarization layer 2508 may be deposited on top of the microdevice substrate 2502 around each microdevice 2504 . Planarization layer 2508 may be used for isolation and/or protection of microdevices. The planarization layer may include polymers such as polyamide, SU8 or BCB. The planarization layer can be cured. In one case, the planarization layer may be cured via temperature, light, or some other source.

Figure 25D shows a cross-sectional view of a microdevice array bonded to an intermediate substrate according to one embodiment of the present invention. In one embodiment, one or more bonding layers 2512 may be formed on planarization layer 2508. Bonding layer 2512 may be the same or a different layer than the planarization layer. In another case, a bonding layer may be formed on top of the intermediate substrate (box) 2510. The bonding layer may provide one or more different forces such as electrostatic, chemical, physical or thermal. Bonding layer 2512 may contact planarization layer 2508. To form a contact between the planarization layer and the bonding layer, the bonding layer is cured by pressure, temperature, light, or other sources.

In one embodiment, after the intermediate substrate 2510 is formed over the bonding layer, the microdevice substrate 2502 can be removed, which can be performed by laser or chemical lift-off.

In one case, there may be openings in buffer layer 2506 that allow microdevice 2504 to connect to planarization layer 2508 . This connection acts as an anchor. In one case, the buffer layer can be etched to form a housing, substrate, or anchor that at least partially surrounds each microdevice. After peeling off, the anchors can hold the microdevice to the substrate. In another instance, the buffer layer may couple at least one of the microdevice pads to the electrode. Electrodes can be placed on top or bottom of the planarization layer.

Figure 25E shows a cross-sectional view of a microdevice array with pads according to one embodiment of the invention. The microdevice substrate can be removed to enable a flexible system or for post-processing steps performed on the side of the system facing the substrate. After the substrate is removed, additional processes can be performed. These processes include one of the following: removing additional common layers or thinning planarization layers and/or microdevices. In one case, one or more pads 2520 may be added to microdevice 2504. In one case, these pads may be conductive. In another case, these pads are used purely for bonding to the system substrate. In one case, buffer layer 2506 may be conductive.

In one embodiment, buffer layer 2506 may connect one or more microdevices to test pads. Test pads can be used to bias microdevices and test their functionality. In one case, testing can be performed at the wafer/substrate level. In another case, testing can be performed at the intermediate (box) level. The pads are accessible at intermediate levels after removing too many layers.

In one case, if the microdevice has more than one contact at the top side, the buffer layer can be patterned to connect the contact of at least one of the microdevice to the test pad.

Figure 26 shows a cross-sectional view of a microdevice array bonded to an intermediate substrate and a backplane in accordance with one embodiment of the present invention. Here, backplane 2630 is available. In one case, the backplane can be manufactured using a TFT process. In another case, the backplane may be fabricated using chiplets fabricated using complementary metal oxide semiconductor (CMOS) or other processes.

In one embodiment, the backplane may have transistors and other components for the pixel circuitry to drive the microdevice. In another embodiment, the backplane may be a substrate without components. One or more pads 2622 may be formed on the backplane 2630 to bond the backplane to the microdevice array. In one case, the one or more pads on the backplane may be conductive.

In one embodiment, buffer layer 2606 may be removed or deformed to release the microdevice. Pads 2622 on the backplane or pads 2620 on the microdevice can create a force that pulls the selected microdevice 2640 out. In another embodiment, the buffer layer 2606 or housing may be etched back, reduced, or removed. The housing can be removed from the empty LED spot.

Figure 27A illustrates process steps for extracting a microdevice location according to one embodiment of the present invention. After the microdevice is transferred to the backplane, the position of the microdevice on the backplane can be detected, and if there is a misalignment during the transfer, the patterning of other layers can be adjusted to match this transfer misalignment. The process steps include: step 2702, placing the microdevice on the system substrate; step 2704, using a camera, surface profilometer (optical, ultrasonic, electrical) or other means to extract the position of the microdevice on the system substrate; step 2706, possibly modifying the a pattern of microdevices, wherein the pattern may include one of the following: electrodes coupling the microdevice to a signal, a functionally tunable layer (such as a color conversion or color filter), an open via in a passivation/planarization layer, or backplane layer. Some reference structure may be present on the system substrate to first calibrate the tools used to extract the position of the microdevice, or the reference may be used to find the relative position of the microdevice.

In one embodiment, different components may detect the location of the microdevice. For example, a camera, probe tip, surface profilometer (optical, ultrasonic, electrical) or other means may detect/extract the position/positioning of the microdevice. In another embodiment, a shift in the transfer setting may identify a misalignment of the location of the microdevice on the system substrate/backplane.

For example, in one case, metallization patterning can avoid short circuits. In another case, color filters or color transitions may also be adjusted based on the location of the microdevice. This can reduce the tolerance required to place the microdevice. It is also possible to induce some random offset in the position of the microdevice to reduce optical artifacts.

Figure 27B illustrates position/shape modification of an electrode based on a microdevice according to one embodiment of the present invention. One or more microdevices 2710, 2712, or 2714 may have contact pads 2706. In one instance, the position/shape of electrodes 2702, 2704 may be modified based on the position of microdevice 2710, 2712, 2714. In another case, the location/shape of the electrodes may be modified based on the location of the vias. In another case, the location of the vias in the planarization/passivation layer may be modified based on the microdevice location.

Figure 27C shows an extension provided to an electrode according to one embodiment of the invention. In one case, the location of electrode 2702 may be modified. And there may be some extension 2720 for each electrode such that its position or length may be modified based on the location of the microdevice 2710, 2712, or 2714. This can be used for common electrodes or individual electrodes.

According to one embodiment, a bonding structure may be provided. The bonding structure may include a plurality of microdevices on a donor substrate, each microdevice including one or more conductive pads formed on a surface of the microdevice; and a surface for covering each microdevice or the one or more conductive pads. Temporary material for at least a portion of the pad, wherein the temporary material is coupled to a current/voltage source to redirect current through the temporary material to the one or more conductive pads. The temporary material includes conductive material or non-conductive material, and wherein the temporary conductive material further completely or partially covers the one or more conductive pads.

According to another embodiment, the method may further include a conductive layer at the donor substrate to couple the temporary conductive material to the current/voltage source; a housing structure to cover at least a portion of each microdevice on the donor substrate , where the temporary material acts as an anchor holding the plurality of microdevices within the housing structure in the donor substrate.

According to yet another embodiment, the method may further include at least one sacrificial layer between the housing structure and each microdevice, wherein the temporary material is patterned to form openings on the top surface of the donor substrate. The openings at the top surface of the donor substrate are used to release the microdevices from the side walls of the housing structure by removing the sacrificial layer. After the sacrificial layer is removed, temporary materials hold each microdevice in place and the sacrificial layer is removed using a chemical etching process or an electromagnetic signal.

According to other embodiments, the temporary material is separated from the housing structure after each microdevice is transferred to the receptor substrate by one of the following processes: mechanical, optical, thermal, and chemical. Conductive traces on the top surface of the donor substrate connect as one of: mesh, column, or row.

According to some embodiments, multiple access points on the top surface of the donor substrate are used to bias the temporary material via conductive traces. The temporary material forms a pathway between a surface facing the donor substrate and a surface facing away from the donor substrate.

According to one embodiment, a method of bonding at least one microdevice to a receptor substrate is provided. The method includes forming a stack including an electrode and an electroactive polymer layer on a donor substrate below the at least one microdevice; A voltage is applied to the stack such that at least one microdevice is within contact/proximity of the surface of the receptor substrate.

According to some embodiments, the method may further comprise: providing a housing structure around the at least one microdevice; and providing anchors to retain the at least one microdevice inside the housing structure.

According to another embodiment, the anchor releases the microdevice on the surface of the receptor substrate by one of pushing or pulling forces, the stack further includes an absorbing layer that converts light into thermal change, and the electroactive polymer layer becomes a gas, And the pressure generated by the change pushes the at least one microdevice to the surface of the receptor substrate.

According to one embodiment, a method for integrating micro devices on a backplane may be provided, including: forming a buffer layer on or over the one or more micro devices extending above the substrate; forming a planarization layer on the buffer layer, the The planarization layer includes a polymer, and wherein the polymer includes one of polyamide, SU8, or BCB; and a bonding layer is deposited between the planarization layer and the intermediate substrate.

According to another embodiment, the method may further include curing the bonding layer after contacting the planarization layer, and removing the microdevice substrate by laser or chemical lift-off. The bonding layer is cured by pressure, temperature or light.

According to another embodiment, the method may further include removing the microdevice substrate by one of laser or chemical lift-off, and wherein bonding a set of selective microdevices from the substrate to the backplane includes the steps of: aligning the microdevices bringing the device and the backplane into contact; removing the buffer layer to release the microdevices; creating a force to pull out the selected set of microdevices; and bonding the selected set of microdevices to the backplane.

According to another embodiment, the method may further include providing openings in the buffer layer to connect the microdevice to the planarization layer. The buffer layer is conductive, wherein the buffer layer connects the at least one microdevice to the test pad.

According to another embodiment, the method may further include: providing an electrode on either the top or bottom of the planarization layer; coupling at least one microdevice to the electrode via the buffer layer; extracting the location of the microdevice on the backplane; and The position of the electrode is extended to the extraction position of the microdevice on the backplane, where the position of the microdevice is extracted by a camera, a probe tip, or a surface profilometer.

In summary, the present invention provides a microdevice integration process and electronic control integration that are transferred to a system substrate to complete. This transfer can be facilitated by various means, including providing temporary materials, breakable anchors on the donor substrate, or temporary intermediate substrates.

The foregoing description of one or more embodiments of the invention has been presented for purposes of illustration and description. The above description is not intended to be exhaustive or to limit the invention to the precise form disclosed. Many modifications and variations are possible in light of the above teachings. It is intended that the scope of the invention be limited not by this detailed description but by the scope of the patent claims appended hereto.

110:Donor substrate 112: Bottom plane or sheet conductive layer 114: Functional layer 116: Top pixelated conductive layer 118:Current distribution layer 120:Dielectric layer 128: Leveling layer 130:Open your mouth 132: Pad 150: System base board 152:Other layers 154: Pad 156:Dielectric layer 170: Reflective layer or black matrix 210:Donor substrate 212: First top plane or sheet conductive layer 214: Functional layer 216: Second bottom pixelated conductive layer 218:Current distribution layer 228:Layer 232: Pad layer 250: System base board 252:Other layers 254:Substrate pad 256:Dielectric layer 270: Reflective layer or black matrix 310: Donor substrate 312: First bottom conductive layer 314: Functional layer 316: Second top conductive layer 332:Top contact 372:Layer 372-2:Sacrificial layer 374: Filling layer 376: Cassette (temporary) base plate 378:Substrate bonding layer 380: Contact bonding layer 382: Pad 390: System base board 412: First bottom conductive layer 414: Functional layer 416: Second top conductive layer 432: Top contact 472:MIS layer 474:Filling material 476:Temporary base plate 476-1:Anchor 476-2:Slot 478:Substrate bonding layer 480: Lower contact pad 490: System (receptor) substrate 510: Donor substrate 512: First bottom conductive layer 514: Functional layer 516: Second top conductive layer 532: Top contact pad 572:MIS layer 574: Filling layer 582: Pad 590: Receptor substrate 592:Layer 594:Extension 596:gap/gap 598:Bridge 598-2: Possible release point 6110:Donor substrate 6112:Device layer 6114: First buffer layer 6116:Separation layer 6118: Second buffer layer 6150:Substrate 6262: Gap 6263: Gap 6212:Island 6210:Donor substrate 6220: Filling layer 1102: Micro device 1104: Micro device 1106: Micro device 1108:box 1202: Micro device 1204: Micro device 1206: Micro device 1206-2:Other areas 1208:Multiple types of micro device boxes 1302: Micro device 1304:Donor substrate 1306:Support layer 1308:Support layer 1480:Donor substrate 1482: block 1483: block 1484: Cross lines 1580: block 1582: block 1590:Acceptor substrate 1680: block 1682: block 1684: block 1690:box 1790:Box 1802:Donor substrate 1804:Force force component 1806:Stacking 1812:Voltage/Current 1814:Conductive pad 1816:Conductive pad 1818: force-receiving element 1902:Donor substrate 1904: Conductive/contact pad 1906: Conductive/contact pad 1908: Receptor substrate 1910:Current/Voltage 1912:Voltage/Current 1914:Voltage/Current 1918: force-receiving element 2002a: Temporary conductive materials 2002c: Temporary conductive materials 2002d: Temporary conductive materials 2002e: Temporary conductive materials 2002f: Conductive layer 2002g: Temporary conductive materials 2002h: Conductive layer 2004a: Conductive Pad 2004c: Conductive Pad 2004d: Conductive Pad 2004e: Pad 2004h: Conductive materials 2006a: Shell structure 2006b: Shell 2006e: Pad 2006c: Conductive Pad 2006d: Conductive Pad 2006h: Conductive layer 2008a: Sacrificial layer 2008b: Sacrificial layer 2008c: Sacrificial layer 2008e:Sacrificial layer 2008f: Conductive Pad 2008g: Conductive Pad 2008h: Conductive Pad 2010a: Bonding Materials 2010e: Pad 2010f: Conductive Pad 2010g: Conductive Pad 2010h: Conductive Pad 2012g: Conductive Pad 2012h: Conductive Pad 2014a: Anchors 2014g: Conductive Pad 2014h: Conductive Pad 2016: Microdevices 2102:Microdevice 2104:Donor substrate 2106:Conductive pad 2106-1: Conductive Pad 2106-2: Conductive Pad 2106-3: Conductive Pad 2106-4: Conductive Pad 2108: Temporary conductive materials 2110: Temporary conductive materials 2204:Electrode 2206:Electrode 2208:Electroactive polymer (EPE) layer 2210: Micro device 2212: Micro device 2214:Donor substrate 2220:EPE 2222:EPE 2226: Shell structure 2234:Anchor 2302:Electrode 2304: stacked layer 2306:Electrode 2308:Stacking layer 2310: stacked layer 2312: Micro device 2314: Micro device 2318: Micro device 2320:Donor substrate 2322: Shell 2326:Anchor 2332:Anchor 2404:Stacking layer 2404-1:Layer 2410: Micro device 2414: Micro device 2418: Micro device 2422: Shell 2426:Anchor 2428:Anchor 2456:Gas 2458:Absorption layer 2502:Microdevice substrate 2504: Microdevice Array 2506:Buffer layer 2508: Planarization layer 2510: Intermediate substrate 2512: Bonding layer 2520: Pad 2606:Buffer layer 2620: Pad 2622: Pad 2630:Back plate 2640: Micro device 2702:Electrode 2704:Electrode 2706: Contact pad 2710:Microdevice 2712: Micro device 2714:Microdevice 2720:Extension

The invention will be described in more detail with reference to the accompanying drawing which shows a preferred embodiment of the invention, in which:

Figure 1A shows a cross-sectional view of a lateral functional structure on a donor substrate in accordance with an embodiment of the invention;

1B shows a cross-sectional view of the lateral structure of FIG. 1A with a current distribution layer deposited thereon, in accordance with an embodiment of the present invention;

1C shows a cross-sectional view of the lateral structure of FIG. 1B after patterning a top dielectric conductive layer and depositing a second dielectric layer in accordance with an embodiment of the present invention;

1D shows a cross-sectional view of a lateral structure after patterning a second dielectric layer in accordance with an embodiment of the present invention;

1E shows a cross-sectional view of a lateral structure after pad deposition and patterning in accordance with an embodiment of the present invention;

1F shows a cross-sectional view of a lateral structure after bonding to a system substrate through a bonding region to form an integrated structure according to an embodiment of the present invention;

1G shows a cross-sectional view of the integrated structure after removing the donor substrate and patterned bottom electrode according to an embodiment of the present invention;

1H shows a cross-sectional view of the integrated structure after removing the donor substrate and patterned bottom electrode according to an embodiment of the present invention;

2A shows a cross-sectional view of another embodiment of a lateral functional structure on a donor substrate with a pad layer;

2B shows a cross-sectional view of the lateral structure of FIG. 2A after patterning the pad layer and contact layer and current distribution layer in accordance with an embodiment of the present invention;

2C shows a cross-sectional view of the lateral structure of FIG. 2A after filling the distance between patterned pads in accordance with an embodiment of the present invention;

2D shows a cross-sectional view of the lateral structure of FIG. 2A aligned and bonded to a system substrate with patterned pads in accordance with an embodiment of the present invention;

2E shows a cross-sectional view of the lateral structure of FIG. 2A with a device substrate removed according to an embodiment of the present invention;

3A shows a cross-sectional view of a mesa structure on a device (donor) substrate according to an embodiment of the invention;

3B shows a cross-sectional view of steps with the empty spaces between the mesa structures of FIG. 3A filled, in accordance with an embodiment of the present invention;

Figure 3C shows a cross-sectional view of steps in which the device (mesa structure) of Figure 3B is transferred to a temporary substrate according to an embodiment of the invention;

Figure 3D shows a cross-sectional view of steps in which the device of Figure 3C is aligned and bonded to a system substrate in accordance with an embodiment of the present invention;

3E shows a cross-sectional view of steps in which a device is transferred to a system substrate in accordance with an embodiment of the present invention;

Figure 3F shows a thermal curve of a thermal transfer step according to an embodiment of the invention;

4A shows a cross-sectional view of a temporary substrate with a slot and a device transferred thereto, in accordance with an embodiment of the present invention;

4B shows a cross-sectional view of the temporary substrate of FIG. 4A after cleaning of filler between the device space and the slot in accordance with an embodiment of the present invention;

4C shows a cross-sectional view of steps in which a device is transferred to a system substrate by destroying a released surface, according to an embodiment of the present invention;

Figure 5A shows a cross-sectional view of a microdevice with different anchors in a filling layer according to an embodiment of the invention;

5B shows a cross-sectional view of a microdevice after post-processing a filling layer in accordance with an embodiment of the invention;

Figure 5C shows a top view of the microdevice of Figure 5B according to an embodiment of the present invention;

5D shows a cross-sectional view of a transfer step for transferring a microdevice to another substrate in accordance with an embodiment of the invention;

Figure 5E shows a cross-sectional view of transferring a microdevice to a substrate in accordance with an embodiment of the invention;

6A shows a cross-sectional view of a mesa structure on a device (donor) substrate according to another embodiment of the invention;

Figure 6B shows a cross-sectional view of steps with the empty spaces between the mesa structures of Figure 6A filled;

Figure 6C shows a cross-sectional view of steps in which the device (mesa structure) of Figure 6B is transferred to a temporary substrate according to an embodiment of the invention;

6D shows a cross-sectional view of steps in which a portion of the bottom conductive layer of FIG. 6C is removed according to an embodiment of the present invention;

Figure 6E shows a cross-sectional view of a microdevice with anchors in a filling layer according to an embodiment of the invention;

Figure 6F shows a cross-sectional view of a microdevice with anchors in a filling layer according to an embodiment of the invention;

6G shows a cross-sectional view of a microdevice with anchors in a filling layer according to an embodiment of the invention;

Figure 6H shows a cross-sectional view of preliminary steps in another embodiment of the invention;

6I shows a cross-sectional view of the etching step in the embodiment of FIG. 6H according to an embodiment of the present invention;

Figure 6J shows a cross-sectional view of the separation step in the embodiment of Figure 6H according to an embodiment of the present invention;

6K shows a top view of another embodiment of the present invention according to an embodiment of the present invention;

Figure 6L shows a cross-sectional view of the embodiment of Figure 6K according to an embodiment of the present invention;

6M shows a cross-sectional view of the embodiment of FIGS. 6K and 6L with filler material in accordance with an embodiment of the present invention;

Figure 7 is a flow chart of the process of the embodiment of the present invention;

Figure 8 is a flow chart of a microdevice installation process according to an embodiment of the present invention;

Figure 9 is a flow chart of a microdevice installation process according to an embodiment of the present invention;

Figure 10 is a flow chart of a microdevice installation process according to an embodiment of the present invention;

Figure 11 shows examples of donor or temporary (box) substrates with different types of pixelated microdevices according to embodiments of the present invention;

Figure 12 shows examples of donor or temporary (box) substrates with different types of pixelated microdevices according to embodiments of the present invention;

13 shows an example of a donor substrate for the same type of microdevice but with different spacing between groups of microdevices in accordance with an embodiment of the present invention;

14A shows an example of a donor substrate or temporary substrate with non-uniform output on a microdevice block according to an embodiment of the present invention;

14B shows an example of a receptor substrate or system substrate with non-uniform output across multiple microdevice tiles in accordance with an embodiment of the present invention;

14C shows an example of a system substrate with skewed microdevice blocks in accordance with embodiments of the present invention;

14D shows an example of a system substrate with a flipped microdevice block according to an embodiment of the present invention;

14E shows an example of a system substrate with flipped and alternating microdevice tiles in accordance with an embodiment of the present invention;

Figure 15A shows an example of a donor substrate with two different microdevice blocks according to an embodiment of the invention;

15B shows an example of a system substrate with skew blocks of different microdevices according to an embodiment of the present invention;

Figure 16A shows an example of a donor substrate with three different types of pixelated microdevice blocks in accordance with embodiments of the present invention;

16B shows an example of a system substrate with multiple different types of individual microdevices from each block in accordance with an embodiment of the invention;

17A shows an example of a cassette substrate with multiple different types of pixelated microdevice tiles in accordance with embodiments of the present invention;

17B shows an example of a cassette substrate with multiple different types of offset pixelated microdevice blocks in accordance with embodiments of the present invention;

Figure 18 illustrates a donor substrate holding a microdevice via a donor force element in accordance with an embodiment of the present invention.

Figure 19 shows an example of a microdevice with more than one contact pad on one side in accordance with an embodiment of the present invention.

Figures 20A1-20A2 illustrate examples of highlighted temporary conductive material covering microdevices in accordance with some embodiments of the invention.

Figures 20B1-20B2 illustrate another example of a highlighted temporary conductive material covering a microdevice in accordance with some embodiments of the invention.

Figures 20C1-20C2 illustrate another example of a highlighted temporary conductive material covering a microdevice in accordance with some embodiments of the invention.

20D-20H illustrate another example of a highlighted temporary conductive material covering a microdevice in accordance with some embodiments of the invention.

Figures 20I1-20I2 illustrate another example of a highlighted temporary conductive material covering a microdevice in accordance with some embodiments of the invention.

Figure 21A shows an exemplary top view representation of Figure 20A in accordance with an embodiment of the present invention.

Figure 21B1 shows an exemplary top view representation of Figure 20B1 in accordance with an embodiment of the present invention.

Figure 21B2 shows another exemplary top view representation of Figure 20B2 in accordance with an embodiment of the present invention.

Figure 21C shows an exemplary top view representation of Figure 20E in accordance with an embodiment of the present invention.

Figure 21D shows an exemplary top view representation of Figure 20F, in accordance with an embodiment of the present invention.

22A-22C illustrate a microdevice on a donor substrate in which the microdevice is selectively movable toward or away from a surface of the donor substrate in accordance with embodiments of the present invention.

23A-23B illustrate a microdevice on a donor substrate in which the microdevice is selectively movable toward or away from a surface of the donor substrate in accordance with embodiments of the present invention.

Figure 24 shows another example of a microdevice on a donor substrate in which the microdevice is selectively movable toward or away from a surface of the donor substrate in accordance with an embodiment of the present invention.

Figure 25A shows a cross-sectional view of a microdevice array on a microdevice substrate according to one embodiment of the present invention.

Figure 25B shows a cross-sectional view of a microdevice array with a patterned buffer layer according to one embodiment of the present invention.

Figure 25C shows a cross-sectional view of a microdevice array with a planarization layer according to one embodiment of the present invention.

Figure 25D shows a cross-sectional view of a microdevice array bonded to an intermediate substrate according to one embodiment of the present invention.

Figure 25E shows a cross-sectional view of a microdevice array with pads according to one embodiment of the invention.

Figure 26 shows a cross-sectional view of a microdevice array bonded to an intermediate substrate and a backplane in accordance with one embodiment of the present invention.

Figure 27A illustrates process steps for extracting a microdevice location according to one embodiment of the present invention.

Figure 27B illustrates position/shape modification of an electrode based on a microdevice according to one embodiment of the present invention.

Figure 27C shows an extension provided to an electrode according to one embodiment of the invention.

The use of the same reference numbers in different drawings indicates similar or identical elements.

The invention is susceptible to various modifications and alternative forms, and the specific embodiments or implementations are shown as examples in the drawings and will be described in detail herein. However, this invention is not limited to the specific forms disclosed. Indeed, the invention is intended to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the invention as defined by the appended claims.

110:Donor substrate

112: Bottom plane or sheet conductive layer

114: Functional layer

116: Top pixelated conductive layer

Claims (30)

A bonding structure consisting of: a plurality of microdevices located on the donor substrate, each microdevice including one or more conductive pads formed on a surface of the microdevice; and A temporary material covering at least a portion of each microdevice or the one or more conductive pads, wherein the temporary material is coupled to a current/voltage source to redirect current through the temporary material to the one or more conductive pads. The bonding structure of claim 1, wherein the temporary material includes conductive material or non-conductive material. For example, the bonding structure of request item 1 further includes: A conductive layer at the donor substrate that couples the temporary conductive material to the current/voltage source. The bonding structure of claim 2, wherein the temporary conductive material further completely or partially covers the one or more conductive pads. For example, the bonding structure of request item 1 further includes: A housing structure covering at least a portion of each microdevice on the donor substrate. The bonded structure of claim 5, wherein the temporary material acts as an anchor holding the plurality of microdevices inside the housing structure in the donor substrate. For example, the bonding structure of request item 1 further includes: At least one sacrificial layer is located between the housing structure and each microdevice. The bonded structure of claim 1, wherein the temporary material is patterned to form openings on the top surface of the donor substrate. The bonding structure of claim 8, wherein the opening at the top surface of the donor substrate is used to release the microdevice from the sidewall of the housing structure by removing the sacrificial layer. The bonded structure of claim 9, wherein the temporary material holds each microdevice in place after removal of the sacrificial layer, and wherein the sacrificial layer is removed using a chemical etching process or an electromagnetic signal. The bonded structure of claim 8, wherein the temporary material is separated from the housing structure after each microdevice is transferred to the receptor substrate by one of the following processes: mechanical process, optical process, thermal process and chemical process. The bonding structure of claim 11, wherein the conductive traces on the top surface of the donor substrate are connected as one of: meshes, columns, or rows. The bonding structure of claim 11, wherein access points on the top surface of the donor substrate are used to bias the temporary material via the conductive traces. The bonding structure of claim 1, wherein the temporary material forms a passage between a surface facing the donor substrate and a surface facing away from the donor substrate. A method of placing at least one microdevice onto a receptor substrate, the method comprising: Forming a stack including an electrode and an electroactive polymer layer on the donor substrate below the at least one microdevice; A voltage is applied to the stack to cause at least one microdevice to contact/adjacent the surface of the receptor substrate. The method of claim 15 further includes: providing a housing structure around the at least one microdevice; and Anchors are provided to retain the at least one microdevice within the housing structure. The method of claim 15, wherein the anchor releases the microdevice on the surface of the receptor substrate by one of pushing force or pulling force. The method of claim 15, wherein the stack further includes an absorbing layer that converts light into thermal changes. The method of claim 15, wherein the electroactive polymer layer changes to a gas, and the pressure generated by the change pushes the at least one microdevice to the surface of the receptor substrate. A method of integrating micro devices on a backplane, the method includes: providing a microdevice substrate including one or more microdevices; selectively bonding a set of the microdevices from the substrate to the backplane by connecting contact pads on the microdevices to corresponding pads on the backplane; The set of bonded selective microdevices is left on the backplane by separating the microdevice substrate. The method of claim 20 further includes: forming a buffer layer on or over the one or more microdevices extending above the substrate; Forming a planarization layer on the buffer layer, the planarization layer includes a polymer, and wherein the polymer includes one of polyamide, SU8, or BCB; and A bonding layer is deposited between the planarization layer and the intermediate substrate. The method of claim 21, which further includes The bonding layer is cured after contacting the planarization layer, wherein the bonding layer is cured by any of pressure, temperature, or light. The method of claim 20, which further includes The microdevice substrate is removed by one of laser or chemical lift-off. The method of claim 20, wherein the pads on the microdevices and the corresponding pads on the backplane are conductive. The method of claim 20, wherein bonding the set of selective microdevices from the substrate to the backplane includes the following steps: Align and contact the microdevices with the backplane; removing the buffer layer to release the microdevices; Generating a force that pulls out the selected set of microdevices; and The selected set of microdevices are bonded to the backplane. The method of claim 20, which further includes Openings are provided in the buffer layer to allow the microdevices to connect to the planarization layer. The method of claim 21, wherein the buffer layer is conductive. The method of claim 21, wherein the buffer layer connects at least one microdevice to the test pad. The method of claim 21, which further includes providing electrodes on either the top or bottom of the planarization layer; and At least one microdevice is coupled to the electrode via the buffer layer. The method of claim 21, which further includes Extract the location of the microdevice on the backplane; and The location of the electrode is extended to an extraction location of the microdevice on the backplane, where the location of the microdevice is extracted by one of a camera, a probe tip, or a surface profilometer.