CN109830455B

CN109830455B - Method for transferring micro device into system substrate

Info

Publication number: CN109830455B
Application number: CN201811405946.0A
Authority: CN
Inventors: 格拉姆雷扎·查济
Original assignee: Vuereal Inc
Current assignee: Vuereal Inc
Priority date: 2017-11-23
Filing date: 2018-11-23
Publication date: 2023-06-30
Anticipated expiration: 2038-11-23
Also published as: CA2986503A1; DE102019101489A1; TWI686919B; CN109830455A; CN116682777A; TW201926633A

Abstract

The present disclosure relates to integrating pixelated micro-devices into a system substrate.

Description

Method for transferring micro device into system substrate

Cross Reference to Related Applications

The present application claims priority from canadian application No. 2,986,503 filed on date 2017, 11, 23, which is incorporated herein by reference in its entirety.

Technical Field

The present invention relates to integrating micro devices into a system substrate.

Background

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

Disclosure of Invention

Some embodiments of the present description relate to integrating micro devices into a system substrate. The system substrate may include micro Light Emitting Diodes (LEDs), organic LEDs, sensors, solid state devices, integrated circuits, (microelectromechanical systems) MEMS, and/or other electronic components. Other embodiments relate to patterning and placement of micro devices in connection with pixel arrays for optimizing micro device usage during local transfer. The receiving substrate may be, but is not limited to, a Printed Circuit Board (PCB), a thin film transistor back plate, an integrated circuit substrate, or in one case of an optical micro device such as an LED, the receiving substrate may be a component of a display, e.g., a drive circuit back plate. Patterning of the microdevice donor substrate and receiving substrate may be used in conjunction with different transfer techniques, including but not limited to picking and placing using different mechanisms (e.g., electrostatic transfer heads, elastic transfer heads), or using direct transfer mechanisms (such as dual function pads, etc.).

According to one embodiment, a method of transferring a plurality of micro devices into a receiving substrate is provided. The method includes disposing a plurality of micro devices in one or more cassettes, aligning the one or more cassettes with a template having at least one alignment mark, bonding the one or more cassettes with the template, and aligning the template with a receiving substrate; and transferring the plurality of micro devices from the template into a receiving substrate.

According to another embodiment, a transfer apparatus is provided. The transfer apparatus includes a template housing at least one cartridge containing the microdevice; and a bonding device located on the template to assist transfer of the microdevice from the at least one cassette into the receiving substrate by a transfer force.

According to yet another embodiment, a method of transferring a plurality of micro devices into a system substrate is provided. The method includes disposing a plurality of micro devices on one or more cartridges in a system substrate; selecting one or more transferable micro device groups in each cartridge; identifying a number of defective micro devices in each transferable micro device group; and simultaneously adjusting the transfer of the defective micro device into the system substrate.

Drawings

The present invention will be described in more detail with reference to the accompanying drawings, which represent preferred embodiments thereof, wherein:

FIG. 1A shows a cross-sectional view of a lateral functional structure on a donor substrate according to an embodiment of the present invention;

FIG. 1B shows a cross-sectional view of the lateral structure of FIG. 1A with a current distribution layer deposited on the lateral structure;

FIG. 1C shows a cross-sectional view of the lateral structure of FIG. 1B after patterning a dielectric layer, a top conductive layer, and depositing a second dielectric layer;

FIG. 1D shows a cross-sectional view of the lateral structure after patterning the second dielectric layer;

FIG. 1E shows a cross-sectional view of the lateral structure after deposition and patterning of the pads;

FIG. 1F shows a cross-sectional view of the lateral structure after bonding to a system substrate through a bonding region to form an integrated structure;

FIG. 1G shows a cross-sectional view of the integrated structure after removal of the donor substrate and patterning of the bottom electrode;

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

FIG. 2B shows a cross-sectional view of the lateral structure of FIG. 2A after patterning the pad layer and the contact layer and the current distribution layer;

FIG. 2C shows a cross-sectional view of the lateral structure of FIG. 2A after filling the distance between the patterned pads;

FIG. 2D shows a cross-sectional view of the lateral structure of FIG. 2A aligned and bonded to a system substrate through patterned pads;

FIG. 2E shows a cross-sectional view of the lateral structure of FIG. 2A with the device substrate removed;

FIG. 3A shows a cross-sectional view of a mesa structure on a device (donor) substrate;

FIG. 3B shows a cross-sectional view of a step of filling the empty space between the mesa structures of FIG. 3A;

FIG. 3C shows a cross-sectional view of a step of transferring the device of FIG. 3B (mesa structure) to a temporary substrate;

FIG. 3D shows a cross-sectional view of a step of aligning and bonding the device of FIG. 3C to a system substrate;

FIG. 3E shows a cross-sectional view of a step of transferring a device to a system substrate;

fig. 3F shows the heat distribution of the heat transfer step.

Fig. 4A shows a cross-sectional view of a temporary substrate with a recess and a device transferred thereto;

FIG. 4B shows a cross-sectional view of the temporary substrate of FIG. 4A after cleaning the fill between the device spaces and the fill of the recess;

FIG. 4C shows a cross-sectional view of a step of transferring a device to a system substrate by breaking a release surface;

FIG. 5A shows a cross-sectional view of an embodiment of a micro device having different anchors in the fill layer;

fig. 5B shows a cross-sectional view of an example of a micro device after post-processing the fill layer;

FIG. 5C shows a top view of the micro device of FIG. 5B;

Fig. 5D shows a cross-sectional view of a transfer step for transferring a micro device to another substrate; and

fig. 5E shows a cross-sectional view of transferring a micro device to a substrate.

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

FIG. 6B shows a cross-sectional view of a step of filling the empty space between the mesa structures of FIG. 3A;

fig. 6C shows a cross-sectional view of a step of transferring the device of fig. 6B (mesa structure) to a temporary substrate;

FIG. 6D shows a cross-sectional view of a step of removing a portion of the bottom conductive layer of FIG. 6C;

FIG. 6E shows a cross-sectional view of an embodiment of a micro device having an anchor in the fill layer;

FIG. 6F illustrates a cross-sectional view of an embodiment of a micro device having an anchor in the fill layer;

FIG. 6G illustrates a cross-sectional view of an embodiment of a micro device having an anchor in the fill layer;

FIG. 6H shows a cross-sectional view of a preparation step in another embodiment of the invention;

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

FIG. 6J shows a cross-sectional view of a separation step in the embodiment of FIG. 6H;

FIG. 6K shows a top view of another embodiment of the present invention;

FIG. 6L shows a cross-sectional view of the embodiment of FIG. 6K;

FIG. 6M shows a cross-sectional view of the embodiment of FIGS. 6K and 6L with a filler material;

fig. 7A-7C illustrate an example flow chart for forming a microdevice cartridge;

FIG. 8 is a flow chart of a micro device mounting process of the present invention;

fig. 9A-9B illustrate an exemplary flow chart of a micro device mounting process of the present invention;

FIG. 10 is a flow chart of a micro device mounting process of the present invention;

11A-11B illustrate examples of donor or temporary (cartridge) substrates with different types of pixelated micro-devices;

fig. 12A-12B illustrate examples of donor or temporary (cartridge) substrates with different types of pixelated micro-devices;

fig. 13 shows an example of a donor substrate for the same type of microdevice, but with different spacing between groups of microdevices;

fig. 14A shows an example of a donor substrate or temporary substrate with non-uniform output over a microdevice tile;

FIG. 14B illustrates an example of a receiving substrate or system substrate having non-uniform output across multiple micro device tiles;

FIG. 14C illustrates an example of a system substrate with skewed micro-device tiles;

FIG. 14D illustrates an example of a system substrate with flipped micro-device tiles;

FIG. 14E shows an example of a system substrate with flipped and alternating micro-device tiles;

Fig. 15A shows an example of a donor substrate with two different pieces of microdevice;

FIG. 15B illustrates an example of a system substrate with different micro device blocks that are skewed;

FIG. 16A shows an example of a donor substrate with three different types of pixelated micro-device tiles;

FIG. 16B illustrates an example of a system substrate with multiple individual micro devices of different types from each block;

FIG. 17A illustrates an example of a cartridge substrate having a plurality of different types of pixelated micro-device tiles; and

fig. 17B illustrates an example of a cartridge substrate having offset blocks of a plurality of different types of pixelated micro-devices.

Fig. 18A-18E illustrate an example flow chart for forming a microdevice cartridge.

Fig. 19 illustrates an embodiment of using a template to transfer multiple cassettes to fill a system substrate with micro devices.

Fig. 20 shows an example of a template transfer system.

The disclosure is susceptible to various modifications and alternative forms, and can be implemented as specific embodiments or implementations as has been shown by way of example in the drawings and will be described in detail herein. However, it should be understood that the disclosure is not intended to be limited to the particular forms disclosed. Rather, the present disclosure is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the present invention as defined by the following appended claims.

Detailed Description

While the present teachings are described in connection with various embodiments and examples, this is not intended to limit the present teachings to these embodiments. On the contrary, the present teachings encompass various alternatives and equivalents, as will be appreciated by those of skill in the art.

Fig. 1A shows an embodiment comprising a donor substrate 110 with a lateral functional structure comprising a bottom planar sheet-like conductive layer 112, a functional layer 114 (e.g., a light emitting quantum well), and a top pixelated conductive layer 116.

Conductive layers

112 and 116 may comprise doped semiconductor materials or other suitable types of conductive layers. The top conductive layer 116 may comprise a plurality of different layers. In one embodiment, as shown in fig. 1B, a current distribution layer 118 is deposited on top of the conductive layer 116. The current distribution layer 118 may be patterned. In one embodiment, patterning may be accomplished by lift-off. In another case, patterning may be accomplished by photolithography. In an embodiment, a dielectric layer may be deposited and patterned first, and then used as a hard mask for patterning the current distribution layer 118. After patterning the current distribution layer 118, the top conductive layer 116 may also be patterned, thereby forming a pixel structure. As shown in fig. 1C, after patterning the current distribution layer 118 and/or the conductive layer 116, a final dielectric layer 120 may be deposited over the patterned conductive layer 116 and the current distribution layer 118 and between the patterned conductive layer 116 and the current distribution layer 118. The dielectric layer 120 may also be patterned to create openings 130 as shown in fig. 1D, providing access to the patterned current distribution layer 118. As shown in fig. 1E, an additional planarizing layer 128 may also be provided to planarize the upper surface.

As shown in fig. 1E, a pad 132 is deposited on top of the current distribution layer 118 in each opening 130. As shown in fig. 1F, the formed structure with pads 132 is bonded to a system substrate 150 with pads 154. The pads 154 in the system substrate 150 may be separated by a dielectric layer 156. Other layers 152, such as circuitry, planarization layers, conductive traces, may be located between the system substrate pads 154 and the system substrate 150. Bonding of substrate system pads 154 to pads 132 may be accomplished by fusion, anodic plating, thermal compression, eutectic or adhesive bonding. One or more other layers may also be deposited between the system and the lateral devices.

As shown in fig. 1G, the donor substrate 110 may be removed from the lateral functional device (e.g., 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 the conductive layer 112 between pixels. After this stage, other layers may be deposited and patterned according to the function of the device. For example, a color conversion layer may be deposited to adjust the color of light produced by the lateral devices and pixels in the system substrate 150. One or more color filters may also be deposited before the color conversion layer or/and after the color conversion layer. The dielectric layers in these devices (e.g., dielectric layer 120) may be organic (such as polyamide) or inorganic (such as SiN, siO) ₂ 、Al ₂ O ₃ Etc.). Deposition may be accomplished by different processes, such as by 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 as only a portion of the bond pads 132 of the donor substrate 110 or the system substrate bond pads 154. For some layers, there may also be some annealing process. For example, the current distribution layer 118 may be annealed according to the material. In one example, the current distribution layer 118 may be annealed at 500 ℃ for 10 minutes. Annealing may also be accomplished after various steps.

Fig. 2A illustrates an exemplary embodiment of a donor substrate 210 having a lateral functional structure including a first top planar or sheet-like conductive layer 212, a functional layer (e.g., light-emitting layer) 214, a second bottom pixelated conductive layer 216, a current distribution layer 218, and/or a bond pad layer 232. Fig. 2B shows the patterning of all or one of the

layers

216, 218, 232 forming the pixel structure.

Conductive layers

212 and 216 may be comprised of multiple layers including highly doped semiconductor layers. As shown in fig. 2C, some layer 228 (e.g., a dielectric layer) may be used between the

patterned layers

216, 218, and 232 to planarize the upper surface of the lateral functional structure. Layer 228 may also perform other functions, such as a black matrix. As shown in fig. 2D, the formed structure with pads 232 is bonded to a system substrate 250 with substrate pads 254. Pads 254 in the system substrate may also be separated by dielectric layer 256. Other layers 252, such as circuitry, planarization layers, conductive traces, may be located between the system substrate pads 254 and the system substrate 250. Bonding may be accomplished, for example, by fusion, anodic plating, thermal compression, eutectic or adhesive bonding. There may also be other layers deposited between the system and the lateral devices.

The donor substrate 210 may be removed from the lateral function 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 the conductive layer 212 between pixels. After this stage, other layers may be deposited and patterned according to the function of the device. For example, a color conversion layer may be deposited to adjust the color of light produced by pixels in the lateral devices and system substrate 250. One or more color filters may also be deposited before the color conversion layer or/and after the color conversion layer. The dielectric layers in these devices (e.g., dielectric layers 228 and 256) may be organic (such as polyamide) or inorganic (such as SiN, siO) ₂ 、Al ₂ O ₃ Etc.). Deposition may be accomplished by different processes, such as by 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 material of bond pad 232 may be deposited as part of either pad 232 of donor substrate 210 or system substrate pad 254. For some layers, there may also be some annealing process. For example, current distribution layer 218 may be annealed based on the material. In an example, current distribution layer 218 may be annealed at 500 ℃ for 10 minutes. Annealing may also be accomplished after various steps.

In another embodiment shown in fig. 3A, a mesa structure is formed on a donor substrate 310. The micro device structure is formed by etching through the different layers (e.g., the first bottom conductive layer 312, the functional layer 314, and the second top conductive layer 316). A top contact 332 may be deposited on top of the top conductive layer 316 either before or after etching. In another case, a multi-layer contact 332 may be used. In this case, a portion of the contact layer 332 may be deposited before etching, and the other portion of the contact layer 332 may be deposited after etching. For example, an initial contact layer may be first deposited that creates an ohmic contact with the top conductive layer 316 by annealing. In one example, the initial contact layer may be gold and nickel. Other layers 372, such as dielectric layers or MIS (metal insulator structures), may also be used between mesa structures to isolate and/or insulate each structure. As shown in fig. 3B, after the microdevice is formed, a fill layer 374, such as polyamide, may be deposited. The fill layer 374 may also be patterned if only selected microdevices are transferred to the cartridge (temporary) substrate 376 during the next step. A fill 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 micro device. The use of the filler layer 374 prior to transfer may make the stripping process more reliable.

The device is bonded to a temporary substrate (box) 376. The bonding source may vary and may include, for example, one or more of electrostatic bonding, electromagnetic bonding, adhesive bonding, or Van Der Waals force bonding, or thermal bonding. In the case of thermal bonding, a substrate bonding layer 378 having a melting temperature of T1 may be used. The bonding layer 378 may be electrically conductive or include a conductive layer and a bonding layer that may be adhesive bonding, thermal bonding, or light assisted bonding. The conductive layer may be used to bias devices on the substrate 376 to identify defects and characterize performance. This structure may be used in other embodiments presented herein. To accommodate some surface profile non-uniformities, pressure may be applied during bonding. One of the temporary substrate 376 or the donor substrate 310 may be removed and the device left on either of them. This process is illustrated herein based on leaving the device in the temporary substrate 376, however, similar steps may be used when the device is left on the donor substrate 310. After this stage, additional processing may be performed on the micro device, such as thinning the device, forming contact bonds 380 on the bottom conductive layer 312, and removing the fill layer 374. As shown in fig. 3D and 3E, the device may be transferred to a system substrate 390. The transfer may be accomplished using different techniques. In one case, the transfer is performed using thermal bonding. In this case, the contact bonding layer 380 on the system substrate contact pad 382 has a melting point of T2, where T2> T1. Here, a temperature higher than T2 will melt both the substrate bond layer 378 and the contact bond layer 380 on the pad 382.

In a subsequent step, the temperature is reduced to between T1 and T2. At this time, since the contact bonding layer 380 is solidified while the substrate bonding layer 378 is still melted, the device is bonded to the system substrate 390 through the contact bonding layer 380. As shown in fig. 3E, moving temporary substrate 376 will leave the micro devices on system substrate 390. This may be selected by applying localized heating to selected pads 382. Furthermore, in addition to localized heating, a global temperature may be used (e.g., by placing

substrates

376 and 390 in an oven and performing the process therein by raising the overall ambient temperature therein) to increase the transfer rate. Here, the global temperature on temporary substrate 376 or system substrate 390 may be such that the temperature approaches the melting point of contact bonding layer 380 (e.g., to a difference of 5 ℃ to 10 ℃) and the local temperature may be used to melt contact bonding layer 380 and substrate bonding layer 378 corresponding to the selected device. In another case, the temperature may be raised near the melting point of the substrate bonding layer 378, e.g., to a temperature that differs by 5 ℃ to 10 ℃ (above the melting point of the contact bonding layer 378), and for devices in contact with the heated pads 382, the temperature transferred from the pads 382 via the devices melts selected regions of the substrate bonding layer 378.

An example of a thermal profile is shown in fig. 3F, where the melting temperature Tr melts both the contact bonding layer 380 and the substrate bonding layer 378, and the solidification temperature Ts solidifies the contact bonding layer 380 and the bonding pad 382 together, while the substrate bonding layer 378 remains melted. The melting may be localized or at least make the bonding layer soft enough to release the micro-device or activate the alloying process. Other forces, combined or independent, may also be used to hold the device to the bond pad 382. In another case, the temperature profile may be generated by applying a current through the device. Since the contact resistance will be higher before bonding, the power dissipated across the bond pad 382 and the device will be high, melting both the contact bonding layer 380 and the substrate bonding layer 378. As the bond forms, the resistance will decrease and thus the power consumption will decrease, lowering the local temperature. The voltage or current through the pad 382 can be used as an indication of the bond quality and when to stop the process. The donor substrate 310 and the temporary substrate 376 may be the same or different. After the device is transferred to the system substrate 390, various process steps may be completed. These additional process steps may be planarization, electrode deposition, color conversion deposition and patterning, color filter deposition and patterning, and the like.

In another embodiment, the temperature at which the micro-devices are released from the cartridge substrate 376 increases as the alloy starts to form. In this case, when forming the bonding alloy on the bonding pad 382 of the receiving substrate 390, the temperature may be kept constant and the bonding layer solidified, thereby holding the micro device in place on the receiving substrate 390. At the same time, the bonding layer 378 on the cartridge substrate 376 that is connected to the selected micro device remains melted (or soft enough) to release the device. Here, a portion of the material required to form the alloy may be located on the micro device and other portions of the material deposited on the bond pad 382.

In another embodiment, a filler layer 374 may be deposited on top of the cartridge substrate 376 to form a combined filler layer 374/bonding layer 378. The microdevices from the donor substrate 310 may then be pushed into the polymeric filler layer 374. The microdevice may then be separated from the donor substrate 310 either locally or globally. The polymeric bonding layer 378/378 may be cured before or after the device is separated from the donor substrate 310. If multiple different devices are integrated into the box substrate 374, a specially patterned polymeric bonding layer 37/378 may be created for one type of micro device to embed the micro device in the layer and separate the micro device from its donor 310. Then, another polymeric bonding layer 378 is deposited and patterned for the next type of micro device. The second micro device may then be buried in the associated layer 374. In all cases, the polymeric bonding layer 374 may cover a portion of the microdevice or the entire device.

Another method of increasing the temperature may be the use of microwaves or light. Thus, a layer may be deposited over the bond pad 382, a portion of the pad 382, the micro device (or over a portion of the cartridge substrate 376 that absorbs microwaves or light and locally heats the micro device). Alternatively, the cartridge substrate 376 and/or the receiving substrate 390 may include heating elements that may selectively and/or globally heat the micro-devices.

Other methods may also be used to separate the micro-device from temporary substrate 376, such as chemical, optical, or mechanical forces. In one example, the micro-device may be covered by a sacrificial layer that may be peeled from temporary substrate 376 by chemical, optical, thermal, or mechanical forces. This stripping process may be selective or global. In the case of global lift-off, transfer to the system substrate 390 is selective. If the device-to-temporary substrate (cassette) 376 peel process is local, a transfer force may be applied to the system substrate 390 either locally or globally.

The transfer from the cassette 376 to the receiving substrate 390 may be performed based on different mechanisms. In one case, the cassette 376 has a bonding material that releases the device in the presence of light and the same light cures the bonding of the device to the receiving substrate.

In another embodiment, the temperature used to cure the bonding layer 380 of the device to the receiving substrate 390 releases the device from the cassette 376.

In another case, the current or voltage cures the bonding layer 380 of the device to the donor substrate 310. The same current or voltage may release the device from the cartridge 376. Here, the release may be a function of the piezoelectric or temperature generated by the current.

In another method, after curing the bond of the device and the receiving substrate 390, the bonded device is pulled out of the cassette 376. Here, the force holding the device to the cassette 376 is smaller than the force bonding the device to the receiving substrate 390.

In another approach, the cassette 376 has through holes that can be used to push the devices out of the cassette 376 into the receiving substrate 390. Pushing may be accomplished in different ways, such as pushing using a micro-rod array or pushing pneumatically. In the case of a pneumatic structure, the selected device may be pneumatically pushed to the receiving substrate 390 or disconnected from the pulling force of the selected device. In the case of a micro-bar, the selected device is moved toward receiving substrate 390 by passing the micro-bar through the through-hole associated with the selected device. The micro-rods may have different temperatures to facilitate transfer. After the transfer of the selected device is completed, the microrod is retracted. The same bar is aligned with the through holes of another set of micro devices or the set of micro bars aligned with the newly selected set of micro devices is used to transfer the new devices.

In one embodiment, the cassette 376 may be stretched to increase the device pitch in the cassette 376 to increase throughput. For example, if the area of the cassette 376 is 1X1cm ² And has a 5 micron device pitch, and receiving substrate 390 (e.g., display) has a 50 micron pixel pitch, then box 376 may fill 200x200 (40,000) pixels at a time. However, if the cassette 376 is stretched to have a thickness of 2x2cm ² And with a 10 micron device pitch, the box 376 may fill 400x400 (160,000) pixels at a time. In another case, the cassette 376 may be stretched such that at least two devices on the cassette 376 are aligned with two corresponding locations in the receiving substrate. Stretching may be accomplished in one or more directions. The cartridge substrate 376 may comprise or consist of a stretchable polymer. The micro devices are also fixed in another layer or in the same layer as the cartridge substrate 376.

Combinations of the above methods may also be used in the transfer process of the microdevice from the cassette 376 to the receiving substrate 390.

During formation of the cassette (temporary substrate) 376, the device may be tested to identify different defects and device performance. In one embodiment, the device may be biased and tested prior to separating the top electrode. In the case where the device is of the emissive type, a camera (or sensor) may be used to extract defects and device performance. Where the device is a sensor, stimulus may be applied to the device to extract defects and performance. In another embodiment, the top electrodes 332 may be patterned into groups for testing prior to patterning into individual devices. In another example, a temporary common electrode between more than one device is deposited or coupled to the devices to extract device performance and/or to extract defects.

The methods described above in connection with fig. 3A-3D, including but not limited to separation, formation of a fill layer, different roles of a fill layer, testing, and other structures, may be used with other structures including the embodiments described below.

The methods discussed herein for transferring micro devices from the cassette 376 (temporary substrate) to the receiving substrate 390 are applicable to all configurations of cassettes and receiving substrates presented herein.

The device on the donor substrate 310 may be formed with two

contacts

332 and 380 on the same side facing away from the donor substrate 310. In this embodiment, the conductive layer on the cassette 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 cartridge substrate 376 to the receiving substrate 390. Here, the

contacts

332 and 380 may not be directly bonded to the receiving substrate 390, i.e., the receiving substrate 390 need not have a specific pad. In this case, a conductive layer is deposited and patterned to connect

contacts

332 and 380 to the appropriate connections in receiving substrate 390. In another embodiment, the device may be first transferred from the cassette 376 to a temporary substrate before being transferred to the receiving substrate 390. Here, the

contacts

332 and 380 may be directly bonded to the receiving substrate pad 382. The devices may be tested in the cassette 376 or in a temporary substrate.

In another embodiment shown in fig. 4A, a mesa structure is formed on a donor substrate as described above, wherein the micro device structure is formed by etching through different layers, such as a first bottom conductive layer 412, a functional layer (e.g., a light emitting layer) 414, and a second top conductive layer 416. Top contact 432 may be deposited on top of top conductive layer 416 either before or after etching.

Temporary substrate 476 includes a substrate that is initially filled with a filler material (e.g., a soft material such as a polymer or a material such as SiO ₂ Solid material of SiN, etc.) a plurality of grooves 476-2. The recess 476-2 is located below the surface and/or substrate bonding layer 478. The device is transferred to temporary substrate 476 on top of recess 476-2 and includes contact pads 432. In addition, each micro-device may include other passivation layers and/or MIS layers 472 surrounding each micro-device for isolation and/or protection. The space between the devices may be filled with a fill material 474. After post-processing the deviceAnother lower contact pad 480 may be deposited on the opposite surface of the device. The contact layer 412 may be thinned prior to depositing the lower contact pad 480. The filler material 474 may then be removed and the grooves may be emptied, for example, by various suitable methods (such as chemical attack or evaporation) to enable or facilitate release of the surface and/or selected sections of the bonding layer 478. The device may be transferred to the system (receiving) substrate 490 using similar processes as previously described above. Further, in another embodiment, a force (e.g., pushing or pulling) applied from the pads 432 may fracture the surface above the evacuated grooves 476-2 and/or the bonding layer 478 while maintaining the attachment of the unselected mesa structures to the temporary substrate. As shown in fig. 4B and 4C, this force may also release the device from temporary substrate 476. The depth of the recess 476-2 may be selected to account for some micro device height differences. For example, if the height difference is H, the depth of the groove may be greater than H.

Devices on substrate 310 may be formed with two

contacts

432 and 480 on the same side facing away from substrate 310. In this case, the conductive layer on the cartridge substrate 476 may be patterned to independently bias the two contacts of the device. In one case, the device may be transferred directly from the cartridge substrate 476 to the receiving substrate. Here, the

contact portions

432 and 480 will not be directly bonded to the receiving substrate (the receiving substrate need not have a specific pad). In this case, a conductive layer is deposited and patterned to connect

contacts

432 and 380 to the appropriate connections in the receiving substrate. In another case, the device may be first transferred from the cassette 476 to a temporary substrate before being transferred to a receiving substrate. Here, the

contact parts

432 and 480 may be directly bonded to the receiving substrate pad. The device may be tested in a cartridge or in a temporary substrate.

In another embodiment shown in fig. 5A, a mesa structure is formed on a donor substrate 510, as described above, wherein the micro device structure is formed by etching through different layers, such as a first bottom conductive layer 512, a functional layer (e.g., a light emitting layer) 514, and a second top conductive layer 516. The top contact pad 532 may be deposited on top of the top conductive layer 516 before or after etching. In addition, each micro-device may include other passivation layers and/or MIS layers 572 surrounding each micro-device for isolation and/or protection. In this embodiment, the device may be provided with different anchors, whereby the anchors hold the device to the donor substrate 510 after peeling the device. The stripping may be accomplished by a laser. In an example, the laser simply scans the device. In an embodiment, a mask with openings only for devices may be used at the back side of the donor substrate 510 to block laser light from other areas. The mask may be separate or may be part of the donor substrate 510. In another case, another substrate may be attached to the device prior to the lift-off process to hold the device. In another case, a fill layer 574 (e.g., a dielectric layer) may be used between devices.

In the first case shown, layer 592 is disposed to hold the device to donor substrate 510. Layer 592 can be a separate layer or a portion of a layer of a microdevice that is not etched during formation of the mesa structure. In another case, layer 592 may be a continuation of one of layers 572. In this case, layer 592 can be a metal layer or a dielectric layer (SiN or SiO) ₂ Or other material). In another instance, the anchor portion is formed as a separate structure including the extension 594, the void/gap 596, and/or the bridge portion 598. Here, the sacrificial layer is deposited and patterned to have the same shape as the gap/void 596. The anchor layer is then deposited and patterned to form bridge 598 and/or extension 594. The sacrificial material may be later removed to create voids/gaps 596. The extension 594 may also be omitted. Similar to the previous anchor 592, another anchor may be made of a different structural layer. In another case, the filler layer 574 acts as an anchor. In this case, the filler layer 574 may be etched or patterned or left intact.

Fig. 5B shows the sample after removal of the filler layer 574 and/or etching of the filler layer to create the anchor 574. In another case, after peeling, the adhesion of the bridging layer 598 is sufficient to hold the device in place and act as an anchor. The final device is on the right side of fig. 5B; these devices are shown on one substrate 510 for illustrative purposes only. Any one or combination of them may be used on the substrate. As shown in fig. 5C, anchor 574 may cover at least a portion or the entire periphery of the device, or anchor 574 may be patterned to form

arms

594 and 592. For any anchor structure, any structure may be used. Fig. 5D shows one example of transferring a device to a receiving substrate 590. Here, the micro device is bonded to the pad 582 or placed in a predetermined area without using any pad. The compressive or separation force may release the anchor by breaking the anchor. In another case, temperature may also be used to release the anchor. The viscosity of the layer between the micro device and the peeling of the donor substrate 510 may be increased by controlling the temperature to act as an anchor. Fig. 5E shows the device after transfer to the receiving substrate 590 and shows a possible release point 598-2 in the anchor portion. The anchors may also be directly connected to the donor substrate 510 or indirectly connected to the donor substrate 510 through other layers.

The device on the donor substrate 510 may be formed with two

contacts

532 and 480 on the same side facing away from the donor substrate 510. In one case, the device may be transferred directly from the donor substrate 510 to the receiving substrate 590. Here, the

contacts

532 and 480 may be directly bonded to the receiving substrate pad 582. The device may be tested in the donor 510 or in the cartridge substrate. In another embodiment, the device may first be transferred from the donor cassette 510 to the cassette substrate before being transferred to the receiving substrate 590. Here, the contact 532 will not be directly bonded to the receiving substrate 590, i.e., the receiving substrate 590 need not have a specific pad 582. In this case, a conductive layer is deposited and patterned to connect the contacts 532 to the appropriate connections in the receiving substrate 590.

The system or receiving

substrates

390, 490, and 590 may include micro Light Emitting Diodes (LEDs), organic LEDs, sensors, solid state devices, integrated circuits, (microelectromechanical systems) MEMS, and/or other electronic components. Other embodiments relate to patterning and placement of micro devices in connection with pixel arrays to optimize micro device usage during selective transfer. The system or receiving

substrates

390, 490, and 590 may be, but are not limited to, printed Circuit Boards (PCBs), thin film transistor backplanes, integrated circuit substrates, or in the case of one optical micro device such as an LED, may be a component of a display, for example, a drive circuit backplane. Patterning of the microdevice donor substrate and receiving substrate may be used in conjunction with different transfer techniques, including but not limited to picking and placing using different mechanisms (e.g., electrostatic transfer heads, elastic transfer heads), or using direct transfer mechanisms (such as dual function pads, etc.).

Fig. 6A shows an alternative embodiment of the mesa structure of fig. 3A-3F, wherein initially the mesa structure is not etched through all layers. Here, some portions of the buffer layer 312 and/or the contact layer 312 may remain during the initial step. A mesa structure is formed on donor substrate 310. The micro device structure is formed by etching through the different layers (e.g., the first bottom conductive layer 312, the functional layer 314, and the second top conductive layer 316). Top contact 332 may be deposited on top of top conductive layer 316 either before or after etching. The mesa structure may include other layers 372, which other layers 372 will be deposited and patterned before or after the mesa structure is formed. These layers may be dielectrics, MIS layers, contacts, sacrificial layers, etc. After the mesa structure is formed, a fill layer(s) 374 (e.g., dielectric material) is used between or around the micro devices to secure the micro devices together. The micro devices are bonded to temporary substrate 376 by substrate bonding layer(s) 378. The bonding layer(s) 378 may provide one or more different forces such as electrostatic forces, chemical forces, physical forces, heat, and the like. As described above, after the device is removed from the donor substrate 310, 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 fill layer 374 may be etched to separate the micro devices or the sacrificial layer may be removed to separate the devices. In another embodiment, temperature may be applied to separate the device from the fill layer 374 and to prepare the device for transfer to the receiving substrate 390. The separation may be accomplished selectively, as described above. As shown in fig. 6E, in another embodiment, the filler layer 374 can be etched to form a shell, base, or anchor 375 (e.g., in a truncated cone shape or a truncated cone shape) at least partially surrounding each micro-device. Another layer may be deposited over the substrate 375 and used to fabricate the anchor 598-2. After forming the additional layer 598-2, the filling base layer 375 may be left behind or removed from the anchor arrangement. Fig. 6G shows a device with a sacrificial layer 372-2. The sacrificial layer 372-2 may be removed by etching or may be thermally deformed or removed thermally.

In another embodiment, the anchors are identical to the housing 375 and are composed of a polymer, organic, or other layer after the microdevice is transferred to the cassette 376. The housing 375 may have different shapes. In one case, the housing may be matched to the device shape. The housing sidewalls may be shorter than the height of the micro-device. The housing sidewalls may be connected to the microdevices prior to the transfer cycle to provide support for different post-processing of the microdevices in the cartridge 376 and packaging of the microdevice cartridge for shipping and storage. The housing sidewalls may be separate or the connection to the micro-device may be weakened from the device by different means (such as heat, etching or exposure) prior to or during the transfer cycle.

The device on the donor substrate 310 may be formed with two

contacts

332 and 380 on the same side facing away from the donor substrate 310. In this case, the conductive layer on the cassette 376 may be patterned to independently bias the two

contacts

332 and 380 will not be directly bonded to the receiving substrate 390, i.e., the receiving substrate 390 need not have specific pads. In this case, a conductive layer is deposited and patterned to connect

contacts

332 and 380 to the appropriate connections in receiving substrate 390. In another embodiment, the device may be first transferred from the cassette 376 to a temporary substrate before being transferred to the receiving substrate 390. Accordingly,

contacts

332 and 380 may be directly bonded to the receiving substrate pads. The device may be tested in a cassette 376 or in a temporary substrate.

Due to the mismatch between the substrate lattice and the micro device layer, the growth of the layer 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 located between the first buffer layer 6114 and the second buffer layer 6118 or adjacent to the first buffer layer 6114 and the second buffer layer 6118, and then an active layer 6112 is deposited over the buffer layer 6114 and/or buffer layer 6118. The thickness of the buffer layers 6114 and 6118 may be greater, such as the thickness of the donor substrate 6110. The buffer layer 6114/6118 may also be separated during separation (lift-off) of the microdevice from the donor substrate 6110. Thus, buffer layer deposition should be repeated each time. Fig. 6H shows a structure over a substrate 6110, in which a separation layer 6116 is located between a first buffer layer 6114 and an 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 may also block contaminants from the separation layer 6116 from penetrating into the device layer 6112. The two

buffer layers

6114 and 6118 may include more than one layer. The separation layer 6116 may also include a stack of different materials. In one example, the separation layer 6116 reacts to the wavelength of light that the other layers do not respond to. This light source can be used to separate the actual device 6112 from the buffer layer(s) 6114/6118 and donor substrate 6110. In another example, separation layer 6116 reacts with chemicals, while the same chemicals do not affect other layers. Such a chemical may be used to remove the separation layer 6116 or to change the properties of the separation layer 6116 to separate the device from the buffer layer(s) 6114/6118 and the substrate 6110. The method leaves the first buffer layer 6114 on the donor substrate 6110 intact and thus the first buffer layer 6114 can be reused in the next device formation. Some surface treatment, such as cleaning or buffering, may be completed before the next device deposition. In another example, the buffer layer(s) 6114/6118 can include zinc oxide.

As shown in fig. 6I, the micro devices may be separated by different etching processes prior to the separation process (lift-off). The etching may etch part or all of the second buffer layer 6118 (if present) and the separation layer 6116, as well as the device layer 6112. In another example, the second buffer layer 6118 or the separation layer 6116 is not etched. After the etching step, the micro device is temporarily (or permanently) bonded to another substrate 6150, and the separation layer 6116 is removed or modified to separate the micro device from the buffer layer(s) 6114/6118. As shown in fig. 6J, the first buffer layer 6114 may remain substantially intact on the donor substrate 6110.

In another embodiment shown in fig. 6K-6M, layers (e.g., first bottom conductive layer 312, functional layer 314, and second top conductive layer 316) may be formed as islands 6212 on a donor substrate 6210. Fig. 6K shows a top view of islands 6212 formed as an array of micro devices. Island 6212 may be a same size cartridge or multiple size cartridges. Island 6212 may be formed starting from buffer layer 6114/6118 or after the buffer layer. Here, surface treatments or

gaps

6262, 6263 may be formed on the surface to start the growth of the film as islands (fig. 6L). As in fig. 6M, to process the micro device, the gap may be filled by a filling layer 6220. The filler 6220 may comprise a polymer, metal, or dielectric layer. After processing the microdevice, the fill layer 6220 may be removed.

Fig. 7A highlights the process of forming a microdevice cartridge. During a first step 702, a micro device is prepared on a donor substrate (e.g., donor substrate 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 ready to be detached from the

donor substrate

310 or 510. This step may include securing the microdevice by using anchors (e.g., anchors 375, 476-1, 592, 594, 598, and 598-2) or fillers (e.g.,

fillers

374, 472, and 574). During a third step 706, a cartridge substrate or temporary substrate (e.g., cartridge substrate 376 or 476) is formed by the microdevices pretreated in the first and

second steps

702, 704. In one case, during this step, the microdevice is bonded directly or indirectly to the

cartridge substrate

376 or 476 through a bonding layer (e.g., bonding layer 378 or 478). The microdevice is then separated from the

microdevice cartridge substrate

376 or 476. In another embodiment, the cartridge is formed on a microdevice donor substrate (e.g., donor substrate 510). After the device is secured to the

cartridge substrate

376, 476 or 510, other processing steps may be performed, such as removing some of the layers (e.g., layers 312, 374, 472, 574), adding electrically related layers (e.g., contacts 380 or 480), or optical layers (lenses, reflectors). The

cassette

376 or 476 is moved to a receiving substrate (e.g., receiving

substrate

390, 490, or 590) to transfer the device to the receiving

substrate

390, 490, or 590. Some of these steps may be rearranged or combined. Test step 707A may be performed on the microdevice while the microdevice is still on a cartridge substrate (e.g., cartridge substrate 376 or 476) or after the microdevice has been transferred to a receiving substrate (e.g., receiving

substrate

390, 490 or 590) to determine whether the microdevice is defective. In 707B, the defective microdevice may be removed or fixed in place. For example, a micro device group having a predetermined number may be tested, and if the number of defects exceeds a predetermined threshold, the entire micro device group may be removed, at least some of the defective micro devices may be removed, and/or at least some of the defective micro devices may be repaired.

Fig. 7B highlights the process of forming a microdevice cartridge. During a first step 702, a micro device is fabricated on a substrate. During this step, the device is formed and post-processing is performed on the device. During a second step 704, the device is ready to be separated from the substrate. This step may include securing the microdevice by using anchors or fillers. During a third step 706, a box is formed from the microdevices pretreated in the first step 702 and the second step 704. During step 707A, a microdevice group associated with a pixel in the system substrate has been identified as having a defect greater than a threshold, and during step 707B, the microdevice associated with the microdevice group is removed. In one case, during this step, the microdevice is bonded directly or indirectly to the cartridge substrate through a bonding layer. The microdevice is then separated from the microdevice substrate. In another case, the cartridge is formed on the micro device substrate. After the device is mounted on the cartridge substrate, other processing steps may be performed, such as removing some layers, adding electrically related layers (e.g., contacts) or optical layers (lenses, reflectors). The cassette is moved to the receiving substrate to transfer the devices to the receiving substrate. Some of these steps may be rearranged or combined.

Fig. 7C highlights the process of forming a microdevice cartridge. During a first step 702, a micro device is fabricated on a substrate. During this step, the device is formed and post-processing is performed on the device. During a second step 704, the device is ready to be separated from the substrate. This step may include securing the microdevice by using anchors or fillers. During a third step 706, a box is formed from the microdevices pretreated in the first step 702 and the second step 704. During step 707, defective micro devices in the box have been identified, and if the number of defects is greater than a threshold, some or all of the defective micro devices are repaired during step 707B. In one case, during this step, the microdevice is bonded directly or indirectly to the cartridge substrate through a bonding layer. The microdevice is then separated from the microdevice substrate. In another case, the cartridge is formed on the micro device substrate. After the device is mounted on the cartridge substrate, other processing steps may be performed, such as removing some layers, adding electrically related layers (e.g., contacts) or optical layers (lenses, reflectors). The cassette is moved to the receiving substrate to transfer the devices to the receiving substrate. Some of these steps may be rearranged or combined.

Fig. 8 shows the step of transferring the device from the

cassette

376, 476 or 510 to the receiving

substrate

390, 490 or 590. Here, during the first step 802, the

cassette

376, 476 or 510 is loaded (or picked up), or in another embodiment, the standby arm is preloaded with the

cassette

376, 476 or 510. During a second step 804, the

cassette

376, 476 or 510 is aligned with a portion (or all) of the receiving substrate. Alignment may be performed by using a dedicated alignment mark on the

cassette

376, 476 or 510 and the receiving

substrate

390, 490 or 590 or by using a micro device and landing on the receiving

substrate

390, 490 or 590. During the third step, the microdevice is transferred to the selected landing area. If the receiving

substrate

390, 490 or 590 is completely filled, the

cartridge substrate

376, 476 or 510 is moved to the next step (e.g., another receiving

substrate

390, 490 or 590). If further filling of the

current receiving substrate

390, 490 or 590 is required, a further transfer step is performed with one or more

further cassettes

376, 476 or 510. The cycle begins with a first step 802 if the

cartridge

376, 476 or 510 does not have enough devices prior to a new transfer cycle. If the

cassette

376, 476 or 510 has sufficient devices, then the

cassette

376, 476 or 510 is shifted (or moved and aligned) to a new area in the receiving

substrate

390, 490 or 590 in step 814 and the new cycle continues to step 806. Some of these steps may be combined and/or rearranged.

Fig. 9A illustrates a step of transferring a device from a cassette (e.g.,

temporary substrate

376, 476, or 510) to a receiving substrate (e.g., receiving

substrate

390, 490, or 590). Here, during the first step 902, the

cassette

376 or 476 is loaded (or picked up), or in another embodiment, the standby device arm is preloaded with cassettes. During a second step 902-2, a group of micro devices having a number of defects in the group of micro devices less than a threshold is selected in

box

376, 476 or 510. During the third step 904, the

cassette

376, 476 or 510 is aligned with a portion (or all) of the receiving substrate. Alignment may be performed by using dedicated alignment marks on the

cassette

376, 476 or 510 and/or the receiving

substrate

390, 490 or 590 or by using landing on the micro device and receiving

substrate

390, 490 or 590. Then, during a third step 906, the micro device may be transferred to the selected landing area. In optional step 906-2, the micro device may be turned on, for example, by biasing the receiving

substrate

390, 490 or 590, to test the connection of the micro device to the receiving substrate. If individual micro-devices are found to be defective or nonfunctional, additional tuning steps 906-3 may be performed to correct or repair some or all of the nonfunctional micro-devices.

If the receiving substrate is completely filled, the receiving

substrate

390, 490 or 590 is moved to the next step. If further filling of the receiving

substrate

390, 490 or 590 is required, a further transfer step is performed by one or more

further cassettes

376, 476 or 510. The cycle begins at the first step 902 if the

cartridge

376, 476 or 510 does not have sufficient devices prior to a new transfer cycle. If the

cassette

376, 476 or 510 has sufficient devices, the

cassette

substrate

390, 490 or 590 in step 902-2.

Fig. 10 illustrates exemplary process steps for forming multi-type

micro device cartridges

376, 476, 510, or 1108. During a first step 1002, at least two different micro devices are fabricated on different donor substrates (e.g., donor substrate 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 ready to be detached from a donor substrate (e.g., donor substrate 310 or 510). This step may include securing the microdevice by using anchors (e.g., anchors 375, 476-1, 592, 594, 598, and 598-2) or fillers (e.g.,

fillers

374, 472, and 574). During a third step 1006, the first device is moved to

box

376, 476, 510 or 1108. During the fourth step 1008, at least the second microdevice is moved to

cassette

376, 476, 510 or 1108. In one case, during this step, the microdevice is bonded directly or indirectly to the

cartridge substrate

376, 476, 510, or 1108 through a bonding layer (e.g., bonding layer 378 or 478). The microdevice is then separated from the

microdevice donor substrate

310 or 510. In the case of direct transfer, different types of microdevices may have different heights to aid in direct transfer. For example, the second type of microdevice transferred to

cassette

376, 476, 510 or 1108 may be slightly higher than the first type of microdevice (or the location of the second type of microdevice on

cassette

376, 476, 510 or 1108 may be slightly higher). Here, after the

cassettes

376, 476, 510, or 1108 are completely filled, the micro device height may be adjusted to planarize the surface of the

cassettes

376, 476, 510, or 1108. This may be accomplished by adding material to the shorter micro-devices or by removing material from the taller micro-devices. In another case, the landing areas on the receiving

substrate

390, 490, or 590 may have different heights associated with differences in

cassettes

376, 476, 510, or 1108. Another method of filling the

cassettes

376, 476, 510 or 1108 is based on pick and place. The micro devices may be moved to

cassettes

376, 476, 510, or 1108 by a pick and place process. Here, the force elements on the pick and place head may be uniform for the micro-devices in one cluster in

cassettes

376, 476, 510 or 1108, or the force elements may be individual for each micro-device. In addition, the microdevice may be moved to

cassette

376, 476, 510 or 1108 in other ways. In another embodiment, additional devices in the first or second microdevice (third or other microdevice) are removed from the

cassette substrate

376, 476, 510 or 1108, and other types of microdevices are transferred into empty areas on the

cassette

376, 476, 510 or 1108. After the device is secured to the

cartridge substrate

376, 476, 510 or 1108, other processing steps may be performed, such as adding a

fill layer

374, 474 or 574, removing some layers, adding electrically related layers (e.g.,

contacts

380, 480 or 580), or optical layers (lenses, reflectors). The device may be tested before each time for filling the receiving

substrate

390, 490 or 590. The test may be electrical or optical or a combination of both. The test may identify defects and/or performance of the devices on the cartridge. During a final step 1010,

cassette

376, 476, 510, or 1108 is moved to receiving

substrate

390, 490, or 590 to transfer the device to receiving

substrate

390, 490, or 590. Some of these steps may be rearranged or combined.

The transfer processes described herein (e.g., fig. 7, 8, 9, and 10) may include a stretching step to increase the pitch of the micro devices on

cassettes

376, 476, 510, or 1108. This step may be done prior to alignment or as part of the alignment step. This step may increase the number of micro devices aligned with landing areas (or pads) on the receiving

substrate

390, 490, or 590. In addition, it may match the spacing between the array of micro devices on the

cassettes

376, 476, 510, 1108, including at least two micro devices, to the spacing of the landing areas (or pads 382) on the receiving

substrate

390, 490, or 590.

Fig. 11A-11B illustrate examples of multi-type micro-device cassettes 1108 that are similar to

temporary substrates

376, or 510. In fig. 11A, cartridge 1108 includes three different types of

microdevices

1102, 1104, 1106, e.g., three colors (red, green, and blue). But there may be more device types. The distances x1, x2, x3, y1 between the micro devices are related to the pitch of the landing areas in the receiving

substrate

390, 490 or 590. After several devices, which may be related to pixel pitch in the receiving

substrate

390, 490 or 590, there may be different pitches x4, y2. This pitch will compensate for the mismatch between the pixel pitch and the micro device pitch (landing area pitch). In this case, if pick and place forming box 1108 is used, the force elements may be in the form of columns corresponding to the columns of each micro device type, or the force elements may be separate elements for each micro device. In fig. 11B, cartridge 1108 includes three different types of

microdevices

1102, 1104, 1106, e.g., three colors (red, green, and blue). A plurality of micro-devices 1102, 1104, 1106 of each color may be arranged in a cartridge. Some micro-devices may be arranged between three different

colored micro-devices

1102, 1104, 1106. The distances x1, x2, x3, y1 between the micro devices are related to the pitch of the landing areas in the receiving

substrate

390, 490 or 590. These different arrangements of pixelated micro-devices on donor substrates or temporary (cartridge) substrates may be used.

Fig. 12A-12B illustrate examples of multi-type microdevice cartridge 1208 that are similar to

temporary substrates

376, 476, or 510. In fig. 12A, cartridge 1208 includes three different types of micro-devices 1202, 1204, 1206, for example, three colors (red, green, and blue) of micro-devices. The other region 1206-2 may be empty, filled with spare micro-devices, or include a fourth micro-device of a different type. The distance x1, x2, y1, y2 between the micro devices is related to the pitch of the landing areas in the receiving

substrate

390, 490 or 590. After several device arrays, which may be related to pixel pitch in the receiving

substrate

390, 490 or 590, there may be different pitches x4, y4. This pitch will compensate for the mismatch between the pixel pitch and the micro device pitch (landing area pitch). In fig. 12B, cartridge 1208 includes three different types of micro-devices 1202, 1204, 1206, for example, three colors (red, green, and blue) of micro-devices. A plurality of micro-devices 1202, 1204, 1206 for each color may be arranged in a cartridge. Some micro-devices may be arranged between three differently colored

micro-devices

202, 1204, 1206. The distance x1, x2, y1, y2 between the micro devices is related to the pitch of the landing areas in the receiving

substrate

390, 490 or 590. These different arrangements of pixelated micro-devices on a donor substrate or temporary (cartridge) substrate may be used to map the micro-devices on a backplane.

Fig. 13 illustrates one example of a microdevice 1302 fabricated on a donor substrate 1304 similar to the

donor substrate

310 or 510 prior to transfer to a

multi-type microdevice cartridge

376, 476, 510, 1108, 1208. Here,

support layers

1306 and 1308 may be used for individual devices or groups of devices. Here, the pitch may match the pitch in the

cassettes

376, 476, 510, 1108, 1208, or the pitch may be a multiple of the cassette pitch.

In all of the above structures, the micro devices may be moved from the first cassette to the second cassette before filling the substrate with the micro devices. Additional processing steps may be performed after the transfer. Alternatively, some of the processing steps may be distributed between the first and second cartridge structures.

Fig. 14A illustrates an embodiment of a micro device in a donor substrate 1480 similar to

donor substrate

310 or 510. Due to manufacturing and material imperfections, the micro-devices may have a gradually decreasing or gradually increasing output power, i.e. non-uniformity of output power, on the donor substrate 1480, as shown in the drawing with a dark to light color. Since devices may be transferred together in one block (e.g., block 1482) into the receiving

substrate

390, 490, or 590, or one or more at a time sequentially into the receiving

substrate

390, 490, or 590, adjacent devices in the receiving

substrate

390, 490, or 590 gradually degrade. However, more serious problems may occur at one block (e.g., block 1482) or series of adjacent block ends with another block (e.g., block 1483) or series of block starts (e.g., along intersection line 1484), which may result in abrupt changes in output performance as shown in fig. 14B. This abrupt change may lead to visual artifacts of the optoelectronic device (such as a display).

To address the issue of non-uniformity, one embodiment shown in fig. 14C includes skewing or interleaving individual blocks 1482 and 1483 with blocks above and below them in the display such that the edges or intersecting lines of the blocks are not sharp lines of change, thereby eliminating intersecting lines 1484 and thereby the device blocks form a skewed pattern on the display. Thus, the average impact of abrupt transitions is significantly reduced. The skew may be random and may have different profiles.

Fig. 14D illustrates another embodiment in which micro-devices in adjacent blocks are flipped such that devices with similar properties are adjacent to each other, e.g., the properties of a first block 1482 decrease from a first outside a to a first inside B, while the properties of an adjacent second block 1483 increase from a second inside B adjacent to the first inside a to the second outside a, which may allow the change and transition between blocks to remain smooth and eliminate long abrupt intersections 1484.

Fig. 14E shows an exemplary combination of flipping devices (e.g., high performance devices and low performance devices alternating at the inside) and beveling the edges to further improve average uniformity. In the illustrated embodiment, device performance alternates between high and low in both directions, i.e., between adjacent horizontal blocks and adjacent vertical blocks.

In one case, the performance of the micro devices at the edges of the blocks matches that of an adjacent transfer block (array) prior to transfer to the receiving

substrate

390, 490 or 590.

Fig. 15A shows the use of two or

more blocks

1580, 1582 to fill blocks in a receiving substrate 1590. In the illustrated embodiment, a skew or flip approach as shown in fig. 15B may be used to further improve average uniformity. The higher (or lower) output power sides B and C from

blocks

1580 and 1582, respectively, may be positioned adjacent to each other and the connections between the blocks staggered or skewed with the connections of the blocks above and below the blocks. Further, a random pattern or defined pattern may be used to fill a cartridge substrate or receiving substrate 1590 having more than one block.

Fig. 16A shows a sample with more than one

block

1680, 1682, and 1684.

Blocks

1680, 1682, and 1684 can be from the

same donor substrate

310 or 510 or from

different donor substrates

310 or 510. Fig. 16B shows an example of filling the box 1690 with

different blocks

1680, 1682, and 1684 to eliminate the non-uniformities found in any one block.

Fig. 17A and 17B show a structure having a plurality of cartridges 1790. As described above, the position of the cartridge 1790 is selected in a manner that eliminates overlapping of the same region in the receiving

substrate

390, 490, 590 or 1590 with the cartridge 1790 having the same microdevice during different transfer cycles. In one example, the cartridges 1790 may be independent, meaning that a separate arm or controller processes each cartridge independently. In another embodiment, alignment may be done in opposition, but other actions may be performed simultaneously. In this embodiment, after alignment, the receiving

substrate

390, 490, 590 or 1590 may be moved to facilitate transfer. In another example, after alignment, the cartridges 1790 move together to facilitate transfer. In another example, both the cartridge 1790 and the receiving

substrate

390, 490, 590, or 1590 can be moved to facilitate transfer. In another case, the cartridge 1790 may be assembled in advance. In this case, the frame or substrate may hold the assembled box 1790.

The distance X3, Y3 between boxes 1790 may be several times the width X1, X2 or several times the length Y1, Y2 of the boxes 1790. The distance may be a function of the number of steps moved in different directions. For example, x3=kx1+hx2, where K is the number of steps to the left (direct or indirect) for filling the receiving

substrate

390, 490, 590 or 1590, and H is the number of steps to the right (direct or indirect) for filling the receiving

substrate

390, 490, 590 or 1590. The same functional relationship may be used for distance Y3 and lengths Y1 and Y2 between boxes 1790. As shown in fig. 17A, the cartridges 1790 may be aligned in one or both directions. In another example shown in fig. 17B, the boxes 1790 are not aligned in at least one direction. Each of the cartridges 1790 may have independent controls to apply pressure and temperature to the receiving

substrate

390, 490, 590 or 1590. Other arrangements may also exist depending on the direction of movement between the receiving

substrate

390, 490, 590 or 1590 and the cassette 1790.

In another example, the cartridge 1790 can have different devices and thus fill different areas in the receiving

substrate

390, 490, 590, or 1590 with different devices. In this case, the relative position of the cartridge 1790 and the receiving

substrate

390, 490, 590 or 1590 is changed after each transfer cycle to fill different areas with all of the desired micro devices from different cartridges 1790.

In another embodiment, an array of several cartridges 1790 is prepared. Here, after the devices are transferred from the first array of cassettes to the receiving

substrate

390, 490, 590 or 1590, the receiving

substrate

390, 490, 590 or 1590 is moved to the next array of micro devices to fill the remaining area in the receiving

substrate

390, 490, 590 or 1590 or to receive a different device.

In another example, the cartridge 1790 can be located on a curved surface, and thus the arcuate movement provides contact for transferring the micro device into the receiving

substrate

390, 490, 590 or 1590.

Fig. 18A-18E emphasize the process of forming a microdevice cartridge and reducing defective microdevices. In fig. 18A, during a first step 1802, a group of micro devices is prepared on a substrate. During a second step 1804, a group of micro devices may be found that are associated with pixels in the system substrate, wherein the number of defective micro devices is greater than a threshold. During a third step 1806, some or all of the defective microdevices may be repaired before the system substrate is filled with the set of microdevices of the cartridge. Some of these steps may be rearranged or combined.

In fig. 18B, during a first step 1802, a group of micro devices is prepared on a substrate. During a second step 1804, a group of micro devices may be found that are associated with pixels in the system substrate, wherein the number of defective micro devices is greater than a threshold. During a third step 1806, the micro devices in the set of micro devices may be removed.

In fig. 18C, during a first step 1802, a set of non-transferable micro devices with a number of defective micro devices greater than a threshold value associated with pixels in a system substrate may be found for each of the set of cartridges. During a second step 1804, a subset of cartridges may be selected in which the intersection of the non-transferable micro devices is greatest. During a third step 1806, the subset of cassettes may be used to fill the system substrate.

In fig. 18D, during a first step 1802, defects in different groups of micro devices in different cartridges that are associated with pixels in a system substrate may be found. During a second step 1804, defects in different groups of micro devices in different cartridges that are associated with pixels in the system substrate may be selected. During a third step 1806, the system substrate may be filled with a subset of cassettes.

In fig. 18E, during a first step 1802, defects in different groups of micro devices in different cartridges that are associated with pixels in a system substrate may be found. During a second step 1804, a subset of cartridges may be selected in which the number of micro-device groups in the selected cartridges that are associated with pixels in the system substrate above a threshold value are optimized. During a third step 1806, the subset of cassettes may be used to fill the system substrate.

Fig. 19 illustrates an embodiment of using a template to transfer multiple cassettes to fill a system substrate with micro devices. Here, the template has more than one box. During a first step 1902, at least one cassette is aligned with a template having some alignment marks to facilitate an alignment process. During a second step 1906, at least one cassette is bonded to the template. The bonding mechanism may be in different forms such as thermal, optical, vacuum, van der Waals forces, mechanical clamping, and the like. There may be loops 1904 that repeat

steps

1902, 1906 to join more cartridges to the template. The template is then aligned with the receiving substrate.

Fig. 20 shows an example of a template transfer system. Here, the template 2002 has a plurality of cartridges 2004 that may be loaded on the structure 2002-2. The structure 2002-2 may provide greater rigidity and may also provide high configurability. The height configuration may be controlled independently for each structure 2002-2. The structure 2002-2 may be the same size as, smaller than, or larger than the size of the cassette. This structure 2002-2 may also be a bonding means to assist in transferring the microdevice from the cartridge 2004 into the receiving substrate 2010. The bonding means may provide pressure, temperature, optics and other types of forces to assist in the transfer. In another instance, the bonding device 2006 is located at the other side of the template 2002. In addition, some support structures 2008 may hold the form in place. Support structures 2008 may be located at either side of template 2002. In one case, the support structure may be identical to the bonding means. In another case, each cassette has a separate coupling means. In another case, the coupling means of at least more than one cartridge are identical. The receiving substrate 2010 also has

support structures

2014, 2016. The support structure may be located at either side of the receiving substrate. In one instance, the receiving substrate may have a bonding device 2012 that may assist or initiate the bonding process. One of the

bonding devices

2006 or 2012 may be used for bonding. The support structure 2014 may be identical to the receiving engagement device 2012. In another case, multiple templates may be used to fill the receiving substrate. Here, each template may be independently aligned with the receiving substrate.

The support structure may be a suction device, a magnetic force, a spring loaded pin, a gas bed made of a compressed gas such as air or nitrogen.

The region between the cartridge 2004 on the template 2002 and the bonding device 2006 may have different thermal and/or mechanical properties. In one case, the region may be made of a different material having a higher thermal conductivity. In another instance, the through holes may be formed in different areas or in at least one area and other areas of the template between the cartridge 2004 and the device 2006. The size of the vias may be adjusted for each region to adjust the mechanical properties. In another case, the vias may be filled with different materials to tailor the mechanical and/or thermal properties of different regions of the template 2002.

The vertical photovoltaic stack layer comprises 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 active layer is physically removable from the substrate by changing a property of the separation layer while the buffer layer remains on the substrate.

In one embodiment, the process of changing the properties of the separation layer(s) includes chemical reactive etching or deforming the separation layer.

In another embodiment, the process of changing the properties of the separation layer(s) includes exposure to an electro-optical wave, thereby deforming the separation layer.

In another embodiment, the process of changing the properties of the separation layer(s) includes changing the temperature, thereby deforming the separation layer.

In one embodiment, reusing the buffer layer to form a new photovoltaic stack includes surface treatment.

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

In another embodiment, the surface treatment uses deposition of an additional thin layer of buffer layer for resurfacing.

In one embodiment, the optoelectronic device is a light emitting diode.

In one embodiment, the separation layer may be zinc oxide.

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

In this embodiment, the pads and/or bonding layer may be present on top of the pixelated contacts and/or the current spreading layer.

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

Another embodiment includes a donor substrate including micro devices having bond pads and a filler layer filling spaces between the micro devices.

Another embodiment includes a temporary substrate having a bonding layer to which a microdevice from a donor substrate is bonded.

Another embodiment includes a thermal transfer technique comprising the steps of:

1) Aligning the micro devices on the temporary substrate with bond pads of the system substrate;

2) The melting point of the bonding pads on the system substrate is higher than the melting point of the bonding layers in the temporary substrate;

3) Generating a heat profile, melting both the bond pad and the bond layer, then allowing the bond layer to remain melted and the bond pad to solidify; and

4) Separating the temporary substrate from the system substrate;

in another embodiment in the transfer technique, the heat distribution is generated by a local heat source or a global heat source or both.

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

Another embodiment includes a transfer technique of the micro device structure wherein the anchor releases the micro device after or during bonding of the micro device to a pad in the receiving substrate by pushing or by pulling.

In another embodiment, the anchor portion according to the micro device structure includes at least one layer extending from a side portion of the micro device to the substrate.

In another embodiment, an anchor portion according to a micro device structure includes a void and at least one layer on top of the void.

In another embodiment, the anchor portion according to the micro device structure includes a filler layer surrounding the device.

Another embodiment includes a structure according to the micro device structure wherein the viscosity of the layer between the lift-off micro device and the donor substrate is increased by controlling the temperature to act as an anchor.

Another embodiment includes a release process of the anchor in the micro-device structure, wherein the temperature is adjusted to reduce the force between the anchor and the micro-device.

Another embodiment includes a process of transferring a micro device into a receiving substrate, wherein the micro device is formed in a cassette; aligning the cassette with the selected landing areas in the receiving substrate; and transferring the microdevices in the cassette associated with the selected landing areas to a receiving substrate.

Another embodiment includes a process of transferring a micro device into a receiving substrate, wherein the micro device is formed into a cassette; selecting a microdevice group having defective microdevices less than a threshold; aligning the selected set of micro devices in the cartridge with the selected landing areas in the receiving substrate; and transferring the microdevices in the cassette associated with the selected landing areas to a receiving substrate.

An embodiment includes a cartridge having multiple types of microdevices transferred therefrom.

An embodiment includes a microdevice cartridge in which a sacrificial layer separates at least one side of the microdevice from a filler layer or bonding layer.

One embodiment wherein the sacrificial layer is removed to release the micro device from the filler layer or bonding layer.

One embodiment, wherein the sacrificial layer releases the micro device from the filler under conditions such as high temperature.

The microdevice may be tested to extract information about the microdevice, including but not limited to defects, uniformity, operating conditions, and the like. In one embodiment, the microdevice(s) are temporarily bonded to a cartridge having one or more electrodes for testing the microdevice. In one embodiment, the other electrode is deposited after the microdevice is located in the cartridge. This electrode can be used to test the micro device either before or after patterning. In one embodiment, the cartridge is placed in a predetermined position (which may be a receptacle). The cassette and/or receiving substrate are moved for alignment. At least one selected micro device is transferred to a receiving substrate. If there are more micro devices on/in the cassette, the cassette or receiving substrate is moved to align with a new area or new receiving substrate in the same receiving substrate and at least one other selected device(s) is (are) transferred to a new location. This process may continue until the cartridge does not have enough microdevices, at which point a new cartridge may be placed in the predetermined location. In one example, the transfer of the selected device is controlled based on information extracted from the cartridge. In one example, defect information extracted from the cassette may be used to limit the number of defective devices transferred to the receiving substrate to below a threshold number by eliminating the transfer of groups of micro devices that would exceed the threshold by having more than a threshold number of defects or an accumulated number of defects transferred. 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, a cassette having access performance based on one or more parameters would be used in one receiving substrate. The examples given herein may 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 into the receiving substrate. Here, the pressure and/or temperature may create a bonding force (clamping force) to hold the microdevice to the receiving substrate and/or temperature may also reduce the contact force between the microdevice and the cassette. Thus, the micro device can be transferred to the receiving substrate. In this case, the locations on the receiving substrate assigned to the micro devices have a higher configurability than the rest of the receiving substrate to enhance the transfer process. In embodiments, the cassette may not have micro-devices in certain areas that may be in contact with undesired areas of the receiving substrate (such as locations assigned to other types of micro-devices during the transfer process). These two examples may be combined. In embodiments, the dispensing locations of the microdevices on the substrate may be selectively wetted with an adhesive, or covered with a bonding alloy, or additional structures placed on the dispensing locations. During stamping, a separate box, printing, or other process may be used. In an embodiment, selected micro-devices on the cassette may be moved closer to the receiving substrate to enhance localized transfer. In another case, the receiving substrate applies a pulling force to assist or initiate transfer of the microdevice from the cartridge. The pulling force may be combined with other forces.

In one embodiment, the housing will support the micro devices in the cartridge. The housing may be fabricated around the microdevice on the donor substrate or the cartridge substrate, or the housing may be fabricated separately, and then the microdevice moved into the housing and bonded to the cartridge. In one embodiment, there may be at least one polymer (or another type of material) deposited on top of the cartridge substrate. The microdevice from the donor substrate is pushed into the polymer layer. The microdevice may be separated from the donor substrate locally or globally. The layer may be cured before or after the device is separated from the donor substrate. If multiple different devices are integrated into the cartridge, this layer may be specially patterned. In this case, a type of layer may be created, burying the microdevice in the layer and separating the microdevice from its donor. Then, another layer is deposited and patterned for the next type of microdevice. The second micro-device is then buried in the associated layer. In all cases, this layer may cover a portion of the microdevice or the entire device. In another case, the housing is constructed from a polymer, organic, or other layer after the microdevice is transferred to the cartridge. The housing may have different shapes. In one case, the housing may be matched to the device shape. The housing sidewalls may be shorter than the height of the micro-device. The housing sidewalls may be connected to the microdevices prior to the transfer cycle to provide support for different post-processing of the microdevices in the cartridge and packaging of the microdevice cartridge for shipping and storage. The housing sidewalls may be separated or the connection to the micro-device may be weakened from the device by different means (such as heat, etching or exposure) prior to or during the transfer cycle. There may be contact points that hold the micro device to the cartridge substrate. The contact point with the cartridge may be the bottom side or the top side of the device. The contact points may be weakened or eliminated before or during transfer by different means such as heat, chemical treatment or exposure. This process may be performed for some selected devices, or may be performed globally for all micro devices on the cartridge. The contacts may also be conductive to enable testing of the device by biasing the device at the contact points and other electrodes connected to the micro device. During the transfer cycle, the cassette may be positioned under the receiving substrate to prevent the microdevice from falling out of the housing when the contact points are globally removed or weakened.

In one embodiment, the microdevice cartridge may include at least one anchor portion that holds the microdevice to the cartridge surface. The cassette and/or receiving substrate are moved so that some of the micro devices in the cassette are aligned with some of the locations in the receiving substrate. This anchor may fracture under pressure during pushing the cassette and receiving substrate towards each other or during pulling the device by the receiving substrate. The micro-device may be permanently left on the receiving substrate. The anchors may be located on the sides of the micro-device or at the top (or bottom) of the micro-device.

The top side is the side of the device facing the cartridge and the bottom is the opposite side of the micro device. The other side refers to the side or sidewall.

In one embodiment, the microdevice may be tested to extract information about the microdevice, including but not limited to defects, uniformity, operating conditions, and the like. The cartridge may be placed in a predetermined position (which may be a receptacle). The cassette and/or receiving substrate may be moved for alignment. At least one selected micro-device may be transferred to a receiving substrate. If there are more micro devices on/in the cassette, the cassette or receiving substrate may be moved to align with a new area or new receiving substrate in the same receiving substrate and at least another selected device(s) may be transferred to a new location. This process may continue until the cartridge does not have enough microdevices, at which point a new cartridge will be placed in the predetermined location. In one case, the transfer of the selected device may be controlled based on information extracted from the cartridge. In one case, the defect information extracted from the cassette may be used to limit the number of defective devices transferred to the receiving substrate to below the threshold number by eliminating the transfer of the group of micro devices having more than the threshold number of defects or the cumulative number of defects transferred would exceed the threshold. In another case, the boxes will be binned based on one or more extracted parameters, and each bin may be used for a different application. In another case, a cassette having access performance based on one or more parameters would be used in one receiving substrate. The examples given herein may be combined to improve cartridge transfer performance.

One embodiment includes a method of transferring a micro device to a receiving substrate. The method comprises the following steps:

a) A cassette is prepared having a substrate, wherein the micro devices are located on at least one surface of the cassette substrate, and the cassette has more micro device sites in one region than in a corresponding region of the same size in a receiving substrate.

b) By extracting the devices on the at least one parameter test cartridge.

c) The cassette is picked up or transferred to a position where the micro devices face the receiving substrate.

d) The test data is used to select groups of micro devices on the cartridge.

e) The selected group of micro devices on the cassette is aligned with the selected location on the receiving substrate. The set of micro devices is transferred from the cassette to a receiving substrate.

f) Processes d and e may continue until no active devices in the cartridge or receiving substrate is completely filled.

One embodiment includes a cartridge having more than one type of micro-device located in the cartridge at the same pitch as the pitch in the receiving substrate.

One embodiment includes a cartridge having a substrate, wherein the micro devices are located (directly or indirectly) on a surface of the cartridge and the micro devices are skewed in a row or column such that an edge of at least one row or column is not aligned with an edge of at least another row or column.

One embodiment is a method of transferring a micro device to a receiving substrate. The method includes transferring an array of micro devices into a substrate, wherein an edge of at least one row or column of transferred micro devices is not aligned with an edge of at least another row or column of transferred devices.

One embodiment includes a method of transferring a micro device to a receiving substrate. The method includes transferring an array of devices from a donor substrate to a receiving substrate, wherein in any region on the receiving substrate that is similar in size to the transfer array, there is at least one row or column having micro devices from two different regions of the donor substrate that correspond to the transfer array.

One embodiment includes a process of transferring an array of micro devices into a receiving substrate, where the micro devices are skewed at the edges of the array to eliminate abrupt changes.

Another embodiment includes a process of transferring an array of micro devices into a receiving substrate, wherein prior to the transferring, performance of the micro devices at adjacent edges of two arrays of micro devices is matched.

Another embodiment includes a process for transferring an array of micro devices into a receiving substrate, wherein the array of micro devices is filled with micro devices from at least two different regions of a micro device donor substrate.

Another embodiment includes a process of transferring microdevices from a cassette into a receiving substrate, wherein a plurality of microdevice cassettes are located in different positions corresponding to different areas of the receiving substrate, and then aligning the cassette with the receiving substrate, and transferring microdevices from the cassette to the receiving substrate.

According to some embodiments, aligning the template with the receiving substrate includes stretching the template and the combination of one or more cassettes and the template by one of: thermal bonding, optical bonding, vacuum bonding, van der Waals forces, or mechanical clamping.

According to another embodiment, a transfer apparatus is provided. The transfer apparatus includes a template that houses at least one cassette containing the micro devices and a bonding device located on the template to assist transfer of the micro devices from the at least one cassette to a receiving substrate by a transfer force.

According to a further embodiment, each cartridge has a separate coupling means. The transfer apparatus further comprises a support structure for holding the template in place and a height adjustment device between the template and the at least one cassette. The support structure comprises one of the following: suction means, spring loaded pins and a pneumatic bed made of compressed gas.

According to a further embodiment, the region between the at least one cassette and the bonding means on the template has different thermal and mechanical properties, and a plurality of through holes are formed on the template in different regions between the cassette and the bonding means. The size of the plurality of vias is adjusted for each region to adjust thermal and mechanical properties.

According to another embodiment, wherein adjusting the transfer of the defective micro device comprises: repairing or removing defective microdevices in each bin if the sum of the number of defective microdevices is greater than a threshold, selecting a subset of one or more bins, wherein the intersection of the non-transferable group of microdevices is the largest, and using the subset of bins to adjust the transfer to the system substrate; selecting a subset of the cassettes, wherein the sum of the number of defective micro devices is less than a threshold value, and filling the system substrate with the subset of cassettes; selecting a subset of the cassettes, wherein a sum of the number of defective micro devices above a threshold is optimized, and filling the system substrate with the subset of cassettes.

According to yet another embodiment, the method further comprises biasing the micro devices through the system substrate to test connections between the transferred micro devices and the receiving substrate and adjusting bonding parameters to repair the number of identified defective micro devices.

The foregoing description of one or more embodiments of the invention has been presented for the purposes of illustration and description. It 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 teaching. It is intended that the scope of the invention be limited not by this detailed description, but rather by the claims appended hereto.

Claims

1. A method of transferring a plurality of micro devices into a receiving substrate, the method comprising:

disposing the plurality of micro devices in one or more cartridge substrates;

aligning the one or more cartridge substrates with a template having at least one alignment mark;

bonding the one or more cartridge substrates to the template;

aligning the template with the receiving substrate; and

transferring the plurality of micro devices from the template into the receiving substrate,

wherein aligning the template with the receiving substrate comprises stretching the template.

2. The method of claim 1, wherein the one or more cartridge substrates are bonded to the template by one of: thermal bonding, optical bonding, vacuum bonding, van der Waals forces, or mechanical clamping.

3. A method of transferring a plurality of micro devices into a system substrate, the method comprising:

disposing the plurality of micro devices on one or more cartridge substrates in the system substrate;

selecting one or more transferable micro device groups in each cartridge substrate;

identifying a number of defective micro devices in each transferable micro device group; and

while adjusting the transfer of the defective micro-device into the system substrate,

wherein adjusting the transfer of the defective micro device comprises: each of the cartridge substrates is stretched such that at least two micro devices on each of the cartridge substrates are aligned with two corresponding locations in the system substrate.

4. The method of claim 3, wherein adjusting the transfer of the defective micro device further comprises: in the case where the sum of the numbers of defective micro devices is greater than a threshold value, the defective micro devices in each of the cartridge substrates are repaired or removed.

5. The method of claim 3, wherein adjusting the transfer of the defective micro device further comprises:

selecting a subset of the one or more cartridge substrates in which an intersection of a non-transferable set of the collection of microdevices is greatest, and

the subset of the cartridge substrates is used to transfer to the system substrate.

6. The method of claim 3, wherein adjusting the transfer of the defective micro device further comprises:

selecting a subset of the cartridge substrates in which the sum of the number of defective micro devices is less than a threshold value; and

the subset of the cartridge substrates is used to fill the system substrate.

7. The method of claim 3, wherein adjusting the transfer of the defective micro device further comprises:

selecting a subset of the cartridge substrates in which a sum of the number of defective micro devices above a threshold is optimized; and

the subset of the cartridge substrates is used to fill the system substrate.

8. A method according to claim 3, further comprising:

the micro devices are biased by the system substrate to test connections between the transferred micro devices and the system substrate.

9. A method according to claim 3, further comprising:

the bonding parameters are adjusted to repair the identified number of defective micro devices.