CA2986503A1

CA2986503A1 - Microdevice transfer setup

Info

Publication number: CA2986503A1
Application number: CA2986503A
Authority: CA
Inventors: Reza Chaji
Original assignee: Vuereal Inc
Current assignee: Vuereal Inc
Priority date: 2017-11-23
Filing date: 2017-11-23
Publication date: 2019-05-23
Also published as: CN109830455A; CN109830455B; DE102019101489A1; CN116682777A; TWI686919B; TW201926633A

Abstract

This disclosure is related to integrating pixelated micro devices into a system substrate.

Description

MICRODEVICE TRANSFER SETUP

- 2 -INTEGRATION OF MICRO-DEVICES INTO SYSTEM SUBSTRATE
FIELD OF THE INVENTION
[0001] The present disclosure relates to the Integration of micro-devices into system substrate.
BRIEF SUMMARY
[0002] A few embodiments of this description are related to integration micro-devices into the system substrate. The system substrate may comprise micro light emitting diodes (LEDs), Organic LEDs, sensors, solid state devices, integrated circuits, (micro-electro-mechanical systems) MEMS, and/or other electronic components. Other embodiments are related to patterning and placing of micro devices in respect to the pixel arrays to optimize the micro-device utilizations in selective transfer process. The receiving substrate may be, but is not limited to, a printed circuit board (PCB), thin film transistor backplane, integrated circuit substrate, or, in one case of optical micro devices such as LEDs, a component of a display, for example a driving circuitry backplane. The patterning of micro device donor substrate and receiver substrate can be used in combination with different transfer technology including but not limited to pick and place with different mechanisms (e.g. electrostatic transfer head, elastomer transfer head), or direct transfer mechanism such as dual function pads and more.

[0003] In one embodiment, the micro devices are turned into arrays by continuous pixelation.

[0004] In another embodiment, the micro devices are separated and transferred to an intermediate substrate by filling the vacancies between the devices.

[0005] In another embodiment, the micro devices are post processed after being transferred to intermediate substrate.

BRIEF DESCRIPTION OF THE DRAWINGS

[0006] The foregoing and other advantages of the disclosure will become apparent upon reading the following detailed description and upon reference to the drawings.

[0007] FIG. IA shows an example of lateral functional structure on a donor substrate.

[0008] FIG. 1B shows the lateral structure after a current distribution layer deposited on top.

[0009] FIG. IC shows the lateral structure after patterning the dielectric, top conductive layer and deposition of another dielectric layer.

[0010] FIG. ID shows the lateral structure after patterning of second dielectric.

[0011] FIG. 1E shows the lateral structure after deposition and patterning of pads.

[0012] FIG. IF shows the lateral structure after bonding to a system substrate with bonding areas forming an integrated structure.

[0013] FIG. 1G shows the integrated structure after removing the donor substrate and patterning the bottom electrode.

[0014] FIG. 2A shows an example of lateral functional structure on donor substrate with pad layers.

[0015] FIG. 2B shows the lateral structure after patterning the pad layers and the contact and current distribution layers.

[0016] FIG. 2C shows the lateral structure after the distance between the patterned pads are filled.

[0017] FIG. 2D shows the lateral structure aligned and bonded to the system substrate through the patterned pads.

[0018] FIG. 2E shows the step of removing the device substrate.

[0019] FIG. 3A shows a mesa structure on the device (donor) substrate.

[0020] FIG. 3B shows the step of filling the empty space between the mesa structures.

[0021] FIG. 3C shows the step of transferring the devices (mesa structure) to a temporary substrate.

[0022] FIG. 3D shows the step of aligning and bonding the devices to the system substrate.

[0023] FIG. 3E shows the step of transferring the devices to the system substrate.

[0024] FIG. 3F shows a thermal profile for thermal transfer steps.

100251 FIG. 4A shows temporary substrate with grooves and devices transferred to it.
[0026] FIG. 4B shows the temporary substrate after cleaning the filling from between the device space and the grooves.
[0027] FIG. 4C shows the step of transferring the devices to system substrate by breaking the released surface.
[0028] FIG. 5A shows examples of micro devices with different anchors in filling layer.
[0029] FIG. 5B shows examples of micro devices after post processing the filling layer.
[0030] FIG. 5C shows exemplary top view of micro devices.
[0031] FIG. 5D shows transfer step used for transferring the micro devices to another substrate.
[0032] FIG. 5E shows transferred micro devices to the substrate.
[0033] the released surface.
[0034] FIG. 6A shows examples of mesa structure development.
[0035] FIG. 6B shows examples of mesa structure after the filling layer.
[0036] FIG. 6C shows exemplary of mesa structure transferred to a cartridge substrate.
[0037] FIG. 6D shows an exemplary mesa structure transferred to cartridge substrate after post processing.
[0038] FIG. 6E shows another exemplary mesa structure with an anchor formation.
[0039] FIG. 6F shows another exemplary mesa structure with an anchor formation.
[0040] FIG. 6G shows another exemplary mesa structure with sacrificial layer between anchor and micro device.
[0041] FIG 6-1A shows an optoelectronic device made of stacked layers with buffer layer and separation layer.
[0042] FIG 6-1B shows mesa structured formed based on the active layers.
[0043] FIG 6-1C shows the mesa structure are separated from the buffer layer [0044] FIG 6-2A shows a substrate has at least two separate islands that promote the growth of active, buffer and other layers needed for a optoelectronic devices.
[0045] FIG 6-2B shows cross section of the formed device on top of the islands [0046] FIG 6-2C shows a filler layer filling the space between the islands [0047] FIG. 7 shows a flowchart of developing micro device cartridge.
[0048] FIG. 8 shows an exemplary flowchart for transferring micro devices from cartridge to receiver substrate.
[0049] FIG. 9 shows another exemplary flowchart for transferring micro devices from cartridge to receiver substrate.
[0050] FIG. 10 shows another exemplary flowchart for developing multi-type micro device cartridge.
[0051] FIG. 11 shows an exemplary multi-type micro device cartridge.
[0052] FIG. 12 shows another exemplary multi-type micro device cartridge.
[0053] FIG. 13 shows a micro device substrate prepared for transferring to cartridge.
[0054] FIG 14A-E shows effect of block transfer of microdevices into receiver substrate and using edge skewing and flipping to reduce the abrapt non-uniformity.
[0055] FIG 15A-B shows effect of block transfer of microdevices into receiver substrate and using edge skewing and flipping to reduce the abrapt non-uniformity.
[0056] The present disclosure is susceptible to various modifications and alternative forms, specific embodiments or implementations as have been shown by way of example in the drawings and will be described in detail herein. It should be understood, however, that the disclosure is not intended to be limited to the particular forms disclosed.
Rather, the disclosure is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of an invention as defined by the appended claims.
DETAILED DESCRIPTION
[0057] A vertical optoelectronic stack layers where include a substrate, active layers, at least one buffer between active layers and substrate, and at least one separation layer between said buffer layer and active layers where the said active layers can be physically removed from the substrate by the means of changing the property of the said separation layer while the said buffer layer remains on the substrate.
[0058] In one embodiment, the process of changing the property of the said separation layer(s) where chemical reaction etchs or deform the separation layer.

[0059] In another embodiment, the process of changing the property of the said separation layer(s) where exposure to an optoelectronic wave deform the separation layer.
[0060] In another embodiment, the process of changing the property of the said separation layer(s) where change in the temperature deform the separation layer.
[0061] In one embodiment, reusing the buffer layers for developing new optoelectronic stack layers where include surface treatment.
[0062] In one embodiment, the surface treatment uses chemical or physical etching or polishing.
[0063] In another embodiment, the surface treatment uses deposition of an extra thin layer of buffer layer for resurfacing.
[0064] In one embodiment, the said optoelectronic device is a light emitting diode.
[0065] In one embodiment, the said separation layer can be zinc oxide [0066] An embodiment of this invention is a continuous pixelation structure that includes a fully or partially continuous active layers, pixelated contact and/or current spreading layers.
[0067] In this embodiment, a pad and/or bonding layers may exist on top of pixelated contact and/or current spreading layers.
[0068] In the above embodiment, a dielectric opening may exist on top of each pixelated contact and/or current spreading layers.
[0069] Another embodiment is a donor substrate that includes micro devices with bonding pads and filler layers filling the space between the said micro devices.
[0070] Another embodiment is a temporary substrate that includes a bond layer that the micro devices from donor substrate are bonded to it.
[0071] Another embodiment is a thermal transfer technique which includes the following steps:
1) aligning the micro devices on temporary substrate to the bonding pads of the system substrate 2) melting point of the bonding pads on the system substrate is higher than the melting point of bonding layer in temporary substrate 3) a thermal profile is created that melts both said bonding pads and layer and after that it keeps the bond layer melted a bond pad solidified 4) separating temporary substrate from the system substrate [0072] In another embodiment in said transfer technique, the thermal profile is created by both localized or global thermal sources or both.
[0073] Another embodiment is a micro device structure wherein at least one anchor holds the micro device to the donor substrate after the device is released from the donor substrate by a form of lift off process.
[0074] Another embodiment is a transfer technology for the said micro device structure where the anchor releases the micro device after or during the micro device is bonded to the a pad in a receiver substrate either by the push force or by pull force.
[0075] In another embodiment the anchor according to said micro device structure is made of at least one layer extending to the substrate from the side of the micro device.
[0076] In another embodiment, the anchor according to said micro device structure is made of a void and at least one layer on top of the void.
[0077] In another embodiment, the anchor according to said micro device structure is made of filling layers surrounding the devices.
[0078] Another embodiment is a structure according to said micro device structure where the viscosity of the layer between lift off micro device and donor substrate is increased to act as an anchor by controlling the temperature.
[0079] Another embodiment is a release process for the anchor in said micro device structure, where the temperature is adjusted to reduce the force between anchor and micro device.
[0080] Another embodiment which is a process of transferring micro devices into a receiver substrate where micro-devices are formed into a cartridge, and aligning the cartridge with selected landing areas in the receiver substrate and transferring micro devices in the cartridge associated with selected landing areas to the receiver substrate [0081] Another embodiment which is a process of transferring micro devices into a receiver substrate where micro-devices are formed into a cartridge , and selecting a set of micro devices with defective micro devices less than a threshold, and aligning the selected set of micro devices in the cartridge with selected landing areas in the receiver substrate, and transferring micro devices in the cartridge associated with selected landing areas to the receiver substrate [0082] An embodiment which includes the cartridge that has multi-type of micro-devices transferred into it.
[0083] An embodiment which is a micro device cartridge where a sacrificial layer separate at least one side of the micro device from the filler or bonding layer [0084] An embodiment which the sacrificial layer is removed to release the micro device from the filler or bonding layer.
[0085] An embodiment which the sacrificial layer releases the micro devices from the filler under some conditions such as high temperature.
[0086] The microdevices can be tested for extracting information related to micro devices including but not limited to defects, uniformity, operation condition, and more. In one embodiment, the microdevice(s) are temporarily bonded to a cartridge which has one or more electrode to test the microdevices. In one embodiment, another electrode is deposited after microdevices are located in the cartridge. This electrode can be used for testing the microdevices before or after patterning. In one embodiment, the cartridge is placed in a predefined position (it could be a holder). Either the cartridge and/or the receiver substrate are moved to get aligned. At least one selected microdevice is transferred to the receiver substrate. If more microdevices are available on/in the cartridge, either the cartridge or receiver substrate are moved to get aligned with a new area in the same receiver substrate or a new receiver substrate and at least another selected device(s) is transferred to the new place. This process can continue till the cartridge does not have enough microdevices when a new cartridge will be placed in the predefined position. In one case, transfer of the selected devices is controlled based on the information extracted from the cartridge. In one case, the defect information extracted from cartridge will be used to limit the number of defective devices transferred to the receiver substrate to below a threshold number by eliminating the transfer of a set of micro devices which have a defect number more than a threshold value or the cumulative number of transferred defects will be more than a threshold value. In another case, the cartridges will be binned based on one or more extracted parameters and each bin will be used for different applications. In another case, cartridges with close performance based on one or more parameters will be used in a one receiver substrate. The cases presented here, can be combined to improve the cartridge transfer performance.
[0087] In an embodiment, physical contact and pressure and/or temperature is used for transferring the devices from the cartridge into receiver substrate. Here, the pressure and/or temperature creates a bonding force (or grip force) to hold the microdevices to the receiver substrate and/or also the temperature can reduce the contact force of between microdevices and the cartridge. Thus enabling the transfer of microdevices to receiver substrate. In this case, the positions allocated to the microdevices on the receiver substrate have a higher profile compared to the rest of the receiver substrate to enhance the transfer process. In an embodiment, the cartridge does not have microdevices in areas that can be in contact with unwanted areas of the receiver substrate such as the positions allocated to the other type of micro devices during the transfer process. These two cases can be combined. In an embodiment, the allocated positions for the microdevices on the substrate have been selectively wetted with adhesive, or covered with bonding alloys, or an extra structure is placed on the allocated position. An stamping process, a separate cartridge, printing, or other process can be used. In an embodiment, the selected microdevices on the cartridge is moved closer to the receiver substrate to enhance the selective transferred. In another case, the receiver substrate apply a poll force to assist or initiate the micro device transfer from the cartridge. The poll force can be in combination with other forces.
[0088] In one embodiment a housing will support the micro devices in the cartridge. The housing can be fabricated around the micro device on the donor substrate or cartridge substrate, or fabricated separately and then micro devices are moved inside and bonded to the cartridge. In one case, there is at least one polymer (or another type of material) is deposited on top of the cartridge. The micro devices from donor substrate are pushed into this layer.
The micro devices are separated from the donor substrate selectively or generally. The layer can be cured before or after the devices are separated from the donor substrate. This layer can be patterned specially if multiple different devices are integrated into cartridge. In this case, the layer can be created for one type, the micro devices buried in the layer and separated from their donor. Then another layer is deposited and patterned for the next type of micro devices. Then, the second micro devices buried in the associated layer. In all cases, this layer can cover part of the micro devices or the entire devices. In another case, the housing is built by polymer, organic or other layers after the micro devices are transferred to cartridge. The housing can have different shapes. In one case the housing can match the device shape. The housing side walls can be shorter than the micro device height. The housing side wall can be connected to the micro device prior to the transfer cycle to provide support for different post processing of micro devices in the cartridge and packaging of the microdevice cartridges for shipment and storage. The housing side walls can be separated or the connection to the microdevice can be weakened from the device prior or during the transfer cycle by different means such as heating, etching, or light exposure. There can be a contact point that hold the device to the cartridge substrate. The contact point to the cartridge can be either bottom or top side of the device. The contact point can be weakened or eliminated prior or during the transfer by different means such as heat, chemical process, or light exposure. This process can be performed for some selected devices or be globally for all the micro devices on the cartridge. The contact can be also electrically conductive to enable testing the micro devices by biasing the devices at the contact point and other electrodes connected to the micro devices. The cartridge can be beneath the receiver substrate during the transfer cycle to prevent the micro devices to fell off from the housing if the contact point is removed or weakened globally.
[0089] In one embodiment, the micro device cartridge has at least one anchor that hold the micro devices to the cartridge surface. The cartridge and/or receiver substrate are moved so that some of the micro devices in the cartridge get aligned with some positions in the receiver substrate. This anchor breaks under pressure either during pushing the cartridge and the receiver substrate toward each other or pulling the device by the receiver substrate.
The micro devices stay on the receiver substrate permanently. The anchor can be on the side of the microdevice or at the top (or bottom) of the microdevice.
[0090] The top side is the side of the device facing the cartridge and bottom is the opposite side of the microdevices. The other sides are referred as sides or side walls.
[0091] In one embodiment the microdevices can be tested for extracting information related to micro devices including but not limited to defects, uniformity, operation condition, and more.

The cartridge is placed in a predefined position (it could be a holder).
Either the cartridge and/or the receiver substrate are moved to get aligned. At least one selected microdevice is transferred to the receiver substrate. If more microdevices are available on/in the cartridge, either the cartridge or receiver substrate are moved to get aligned with a new area in the same receiver substrate or a new receiver substrate and at least another selected device(s) is transferred to the new place. This process can continue till the cartridge does not have enough microdevices when a new cartridge will be placed in the predefined position. In one case, transfer of the selected devices is controlled based on the information extracted from the cartridge.
In one case, the defect information extracted from cartridge will be used to limit the number of defective devices transferred to the receiver substrate to below a threshold number by eliminating the transfer of a set of micro devices which have a defect number more than a threshold value or the cumulative number of transferred defects will be more than a threshold value. In another case, the cartridges will be binned based on one or more extracted parameters and each bin will be used for different applications. In another case, cartridges with close performance based on one or more parameters will be used in a one receiver substrate. The cases presented here, can be combined to improve the cartridge transfer performance.
[0092] In an embodiment, physical contact and pressure and/or temperature is used for transferring the devices from the cartridge into receiver substrate. Here, the pressure and/or temperature creates a bonding force (or grip force) to hold the microdevices to the receiver substrate and/or also the temperature can reduce the contact force of between microdevices and the cartridge. Thus enabling the transfer of microdevices to receiver substrate. In this case, the positions allocated to the microdevices on the receiver substrate have a higher profile compared to the rest of the receiver substrate to enhance the transfer process. In an embodiment, the cartridge does not have microdevices in areas that can be in contact with unwanted areas of the receiver substrate such as the positions allocated to the other type of micro devices during the transfer process. These two cases can be combined. In an embodiment, the allocated positions for the microdevices on the substrate have been selectively wetted with adhesive, or covered with bonding alloys, or an extra structure is placed on the allocated position. An stamping process, a separate cartridge, printing, or other process can be used. In an embodiment, the selected microdevices on the cartridge is moved closer to the receiver substrate to enhance the selective transferred. In another case, the receiver substrate apply a poll force to assist or initiate the micro device transfer from the cartridge. The poll force can be in combination with other forces.
[0093] One embodiment is a method of transferring the microdevices to a receiver substrate.
The method includes a) Preparing a cartridge which has a substrate where microdevices are located on at least one surface of the cartridge substrate and it has more microdevices in an area than micro device location in the same size corresponding area in the receiver substrate.
b) Testing the devices on the cartridge for extracting at least one parameter.
c) The cartridge is picked or transferred to a position with microdevices facing the receiver substrate.
d) The test data is used to select a set of microdevices on the cartridge.
e) The selected set of microdevices on cartridge and the a selected position on the receiver substrate are aligned. The set of the microdevices are transferred to the receiver substrate from the cartridge.
0 The process d and e can continue till the cartridge does not have any useful devices or the receiver substrate is fully populated.
[0094] One embodiment is a cartridge which has more than one type of microdevices that are located in the cartridge in the same pitch as in the receiver substrate.
[0095] One embodiment is a cartridge which has a substrate and the microdevices are located on the surface (directly or indirectly) and the microdevices are skewed in either rows or columns so that at least the edge of either one row or a column is not aligned with the edge of at least another row or a column.
[0096] One embodiment is a method of transferring the microdevices to a receiver substrate.
The method includes transferring an array of microdevices into a substrate where at least the edge of either one row or a columns of the transferred microdevices is not aligned with the edge of at least another row or a column of transferred devices.

[0097] One embodiment is a method of transferring the microdevices to a receiver substrate.
The method includes transferring an array of devices from a donor substrate to a receiver substrate where in any area on the receiver substrate similar to the size of transferred array at least there is either one row or column that has micro devices from two different areas from the donor substrate corresponding to the transferred array.
[0098] One embodiment is a process of transferring arrays of micro devices into a receiver substrate where the micro devices are skewed at the edges of the array to eliminate abrupt change [0099] Another embodiment is a process of transferring arrays of micro devices into a receiver substrate where the performance of the micro devices at the adjacent edges of two arrays of micro devices are matched prior to the transfer.
[00100] Another embodiment is a process of transferring arrays of micro devices into a receiver substrate where the array of micro devices is populated at least from two different areas of micro-device donor substrates [00101] Another embodiment is a process of transferring array of micro devices into a receiver substrate from cartridge where several micro-device cartridges are placed in different positions corresponding to different areas of the receiver substrate, then the cartridges are aligned with the receiver substrate, and micro-devices are transferred from cartridges to the receiver substrate [00102] In this case, the distance between adjacent cartridges are chosen to avoid overlapping the same area with cartridges with the same devices during different transfer cycles.
[00103] Another embodiment is a method of transferring microdevices into a receiver substrate where microdevices are arranged in a cartridge that can be released after transferred to a receiver substrate;
the cartridges are arranged in a template that has alignment mark for aligning the cartridges with the template;
the said template is aligned with the receiver substrate; and at least one microdevice is transferred to the receiver substrate [00104] In one embodiment, the method of transfer process of aligning template with receiver substrate may include stretching the template [00105] Another embodiment is a transfer setup that includes a template holding more than one cartridges filled with microdevices a bonding apparatus that assist the transfer of microdevices from at least one cartridge to a receiver substrate by means of generating a transfer force [00106] In one case, at least two cartridges have different bonding apparatus.
[00107] In one case, a support structure fixing the receiver or the template.
[00108] the support structure can be a suction apparatus, a spring loaded pin, a gas bed made of pressured gas such as air or nitrogen, etc.
[00109] In one embodiment, a height adjusting apparatus between the template and the cartridge.
[00110] FIG. IA shows an example of a donor substrate 110 with a lateral functional structure consisting of a bottom conductive layer 112, functional layer (e.g.
quantum wells) 114, and top conductive layer 116. The top conductive layer 116 can consist of few different layers. In one case, as shown in FIG. 1B, a current distribution layer 118 is deposited on top of the conductive layer 116. The current distribution layer 118 can be patterned. In one case, the patterning can be done through lift off. In another case, the patterning can be done through photolithography. In this case, a dielectric layer can be deposited and patterned first and then used as hard mask for patterning the current distribution layer 118. After the patterning of current distribution layer 118, the top conductive layer 116 can be patterned as well.
After this step, a dielectric layer 120 can be deposited after patterning the current distribution layer 118 (and/or conductive layer 116), as shown in FIG. IC. The dielectric layer 120 can also be patterned to create opening 130 as shown in FIG. ID. Some layers 128 can also be used to level the surface, as shown in FIG. 1G
[00111] As shown in FIG. 1E, a pad 132 is deposited on the top of the current distribution layer 118. The developed structure with pads 132 is bonded to the system substrate with pads 154, as shown in FIG. IF. The pads in in the system substrate can be separated by a dielectric layer 156. Other layers 152 such as circuitry, planarization layers, conductive traces can be between the system substrate pads 154 and the substrate 150. The bonding can be done either through fusion, anodic, thermocompression, eutectic, or adhesive bonding. There can also be one or more other layers deposited in between the system and lateral devices.
[00112] As shown in FIG. 1G, the donor substrate can be removed from the lateral functional devices. The conductive layer 112, can be thinned and/or partially or fully patterned.
Reflective layer or black matrix 170 can be deposited and patterned to cover the areas between the pixels. After this stage, other layers can be deposited and patterned depending on the function of the devices. For example, a color conversion layer can be deposited in order to adjust the color of the light produced by the lateral devices and the pixels in the system substrate. One or more color filters can be also deposited before or/and after the color conversion layer. The dielectric layers in these devices can be organic such as polyamide or inorganic such as SIN, Si02, A1203, and others. The deposition can be done with different process such as Plasma-enhanced chemical vapor deposition (PECVD), Atomic layer deposition (ALD), and other methods.
The layer can be a composition of one deposited material or different material deposited separately or together.
The bonding materials can be deposited only as part of the pads 132 of donor substrate 110 or system substrate pads 154. There can also be some annealing process for some of the layers. For example, the current distribution layer can be annealed depending on the materials. In one example, it can be annealed at 500 C for 10 minutes. The annealing can also be done after different steps.
[00113] FIG. 2A shows an exemplary embodiment of a donor substrate 210 with lateral functional structure consists of conductive layer 212, functional layers 214, conductive layer 216, current distribution layer 218 and/or bonding pad layer 232. FIG.
2B shows the patterning of all or one of the layers 216, 218, 232. Some layers 228 can be used to level the surface, as shown in FIG. 2C. The layers 228 can also do other functions such as black matrix.
The developed structure with pads 232 is bonded to the system substrate with substrate pads 254, as shown in FIG. 2D. The pads in in the system substrate can also be separated by a dielectric layer 256. Other layers 252 such as circuitry, planarization layers, and conductive traces can be between the system substrate pads 254 and the substrate 250. The bonding can be done, for example, through fusion, anodic, thermocompression, eutectic, or adhesive bonding. There can also be other layers deposited in between the system and lateral devices.
[00114] The donor substrate can be removed from the lateral functional devices. The conductive layer 212 can be thinned and/or patterned. Reflective layer or black matrix 270 can be deposited and patterned to cover the areas between the pixels. After this stage, other layers can be deposited and patterned depending on the function of the devices. For example, color conversion layer can be deposited in order to adjust the color of the light produced by the lateral devices and the pixels in the system substrate. One or more color filters can be also deposited before or/and after the color conversion layer. The dielectric layers in these devices can be organic such as polyamide or inorganic such as SiN, SiO2, A1203, and others.
The deposition can be done with different process such as Plasma-enhanced chemical vapor deposition (PECVD), Atomic layer deposition (ALD), and other methods. The layer can be a composition of one deposited material or different material deposited separately or together. The material of the bonding pads 232 can be deposited as part of the pads 232 of donor substrate 210 or system substrate pads 254. There can also be some annealing process for some of the layers. For example, the current distribution layer can be annealed depending on the materials. In an example, it can be annealed at 500 C for 10 minutes. The annealing can also be done after different steps.
[00115] In another embodiment shown in FIG. 3A, a mesa structure is developed on the substrate 310. The devices are etched through different layers 312, 314, and 316. One can only etch partially or leave some of the layers such as 316. Also, the etching process can be done in stages. For example, after etching through active layers 314 and maybe part of layer 316, one can add MIS structures and then continue etching through layer 316. The contact 332 can be deposited before or after the etching. In another case a multi-layer contact 332 is used. In this case, it is possible that part of the contact layers are deposited before etching and part of them after. For example, the layers that create the ohmic contact through annealing with layer 316 can be deposited first. In one example, this layer can be gold and nickel. Other layers 372 such as dielectric, or MIS (metal insulator structure) can be also used. Another layer that can cover the entire device or only part of it (e.g. walls) is a sacrificial layer (s). This layer (s) can be used later on to separate the device from a substrate or from the filler layers. This layer can be etched away or deform by temperature. After forming the micro-devices, a filler layer 374 such as polyamide can be deposited, as shown in FIG. 3B. The filler layer can be also deposited after the transfer of the device to temporarily substrate. Using filler layer 374 before transfer, the lift off process can be more reliable.
[00116] The devices are bonded to a temporary substrate 376 through a bonding layer 378. in another case, the filler layer 374 can be on temporary substrate 376.
During the bonding process, the filler layer 374 is moved between the micro devices. In one case, the temporary substrate 376 has a conductive layer that temporary connect or coupled to at least one of the micro devices electrodes. The conductive layer can be the same as bonding layer or the temporary substrate. The conductive layer can be global or patterned. The conductive can be used to bias the micro devices for testing the micro devices (devices) to extract the defects and device performance. The source of bonding from the bonding layer 378 can vary, for example, and comprise one or more of electrostatic, electromagnetic, adhesive, or Van-Der-Waals force, or thermal bonding. In case of the thermal bonding, the bonding layer 378 has a melting temperature of T1. To accommodate some surface profile non-uniformity, pressure can be applied during the bonding process. It is possible to remove either temporary or donor substrate and leave the device on either of them. The process is explained herein based on leaving the devices in the temporary substrate, however, similar steps can be used when the devices are left on donor substrate. After this stage, an extra process can be done on the micro devices such as thinning the device, creating a contact bond 380 and removing the filler layer 374. Part of all of filler layer 374 can be left in place to protect the devices (micro devices) during the transfer to system substrate from misplacement or tilting. In this case, the device needs to be separated from the filler layer 374 during transfer. In one case, the filler layer is also the bonding layer or part of the bonding layer. The process of separating devices from the filler layer 374 can be one of the methods used for bonding layer. The devices can be transferred to a system substrate as shown in FIG. 3D. The transfer can be done using different techniques. In one case, a thermal bonding is used for transfer. In one case, the temperature is applied selectively either through the temporary substrate or through receiver substrate. The source of thermal energy can be applying current, lights, or direct thermal sources. In the case of electrical current, current can be applied directly to the micro devices. In another case, the bonding layer on the pads 382 has a melting point of T2 where 12 > Ti. Here, the temperature higher than T2 will melt both the bonding layer 378 and bonding on pads 382. Reducing the temperature between TI and T2.
[00117] At this point, the device is bonded with contact bond 380 as the bonding layer is solidified but it is still melted in bonding layer 378. Therefore moving the temporary substrate 376 will leave the micro devices on system substrate 390, as shown in FIG. 3E. This can be selective by applying localized heating to the selected pads. Also, global temperature can be used in addition to the localized heating to improve the transfer speed.
Here, the global temperature on the temporary substrate or system substrate can bring the temperature close to the melting point of the bonding layers and localized temperature can be used to melt the bonding layers corresponding selected devices. In another case, the temperature can be raised close to the melting point of bonding layer 378 and temperature transfer from the pads 382 through the device melt the selected areas for the devices in contact with the heated pads.
[00118] An example of a thermal profile is shown in FIG. 3F where the melting temperature Tr melts both bond pads 382 and bonding layer 378 and solidifying temperature Ts solidify the bond pads 382 while the bonding layer 378 is still melted. It is possible that the melting temperature of bond pads increases after curing resulting in higher Is for bonding pad.
Here, other forces in combination or stand alone can be also used to hold the device on the bond pads 382. In another case, the temperature profile can be created by applying current through the device. As the contact resistance will be higher prior to bonding, the power dissipated across the bond pads 382 and device will be high melting both bonding pads 382 and bonding layer 378. As the bonding forms, the resistance will drop resulting in smaller power dissipation and so reducing the localized temperature. The voltage or current going through the pads 382 can be used as indicator of bonding quality and when to stop the process. The donor substrate and temporary substrate can be the same or different. After the device is transferred to the system substrate, different process steps can be done. These extra processing steps can be planarization, electrode deposition, color conversion deposition and patterning, color filter deposition and patterning, and more.

[00119] Other methods also can be used to separate the micro devices from the temporary substrate such as chemical, optical, or mechanical force. In one example, the micro devices can be covered by a sacrificial layer that can be debonded from the temporary substrate by chemical, optical. thermal, or mechanical forces. The debonding process can be selective or global. In case of global debonding transfer to system substrate is selective.
If debonding process of the device from temporary substrate (cartridge) is selective, the transfer force to the system substrate can be applied either selectively or globally.
[00120] The process of transfer from cartridge to receiver substrate can be based on different mechanism. In one case, the cartridge has bonding materials that releases the device at the presence of a light while the same light cure the bonding of device to the receiver substrate.
[00121] In another case, the temperature for curing the bonding of device to the receiver substrate releases the device from the cartridge.
[00122] In another case, the electrical current or voltage cures the bonding of the device to the substrate. The same current or voltage can release the device from the cartridge.
Here the release could be function of piezoelectric, or temperature created by the current.
[00123] In another method, after curing the bonding of the device to the receiver substrate, the bonded devices are polled out of the cartridge. Here, the force holding the device to the cartridge is less than the force bonding the device to the receiver substrate.
[00124] In another method, the cartridge has vias which can be used to push devices out of cartridge into the substrate. The push can be done with different means such as using array of micro rods, or pneumatically. In case of pneumatic structure, the selected devices can be pushed by the pneumatic force to the receiver substrate or the poll force of selected devices are disconnected. In case of micro rods, the selected devices are moved toward receiver substrate by passing the micro rods through the associated vias with the selected devices.
The micro rods can have different temperature to facilitate the transfer. After the transfer of selected devices are finished, the micro rods are retracted. either the same rods are aligned with vias of another set of micro devices or a set aligned with the new selected micro devices is used to transfer the new devices.

[00125] In one case, the cartridge can be stretched to increase the device pitch in the cartridge in order to increase the throughput. For example, if the cartridge is lx1 cm2 with 5-micrometer device pitch, and receiver substrate (e.g. display) has 50 micrometer pixel pitch, the cartridge can populate 200x200 (40,000) pixels at once. However, if the cartridge is stretched to 2x2 cm2 with 10 micrometer device pitch, the cartridge can populate 400x400 (160,000) pixels at once. In another case, the cartridge can be stretched so that at least two micro devices on the cartridge becomes aligned with two corresponding positions in a receiver substrate. The stretch can be done in one or more direction. The cartridge substrate can consist of a stretchable polymer. The micro devices are also secured in another layer or the same layer as the substrate.
[00126] A combination of the methods described above can also be used for transfer process of micro devices from cartridge to the receiver substrate.
[00127] During development of cartridge (temporary substrate), the devices can be tested to identify different defects and device performance. In one case, before separating the top electrode the devices are biased and tested. In case the devices are emissive types, a camera (or sensor) can be used to extract the defects and device performance. In case the devices are sensors, a stimulus can be applied to the devices to extract defects and performance. In another case, the top electrode can be patterned to group for testing before being patterned to individual devices. In another case, a temporary common electrode between more than one devices is deposited or coupled to the devices to extract the device performance and/or extract the defects.
[00128] The methods described in the above related to FIG3 A-D
including but not limited to separation, formation of filler layers, different roles of filler layer, testing, and other structure can be used for the other structures including the ones described hereafter.
[00129] In another embodiment shown in FIG. 4A, the temporary substrate 476 has some grooves 476-2 that are filled. The grooves are underneath the surface and/or bonding layer 478. The devices are transferred on top of the grooves 476-2 and the devices have a pad 432, contact layers 416, 412 and active layers 414. Also, it may have other passivation layers and/or MIS layer 472. The space between the devices is filled with filling material 474 . After post processing the devices another pad 480 can be deposited on the opposite surface of the device.
The contact layer 412 can be thinned. The filling material 474 is then removed and the grooves are emptied to release the surface and/or the bonding layer. A similar process as previously described can be used to transfer the devices to the system substrate 490. In addition, in another embodiment, the forces from the pads can break the surface and/or bonding layer 478. This can release the devices from the temporary substrate as well, as shown in FIG. 4B
and FIG. 4C.
[00130] In another embodiment shown in FIG. 5A, devices are shown with different anchors. After liftoff of the devices, the anchor holds the device to the substrate. The lift off can be done by laser. In an example, only the devices are scanned by laser. In an embodiment a mask can be used that has an opening for the device only at the back of the donor substrate to block the laser from the other area. The mask can be separate or part of the donor substrate. In another case, another substrate can be connected to the devices before the liftoff process to hold the devices. In another case, a filler layer can be used between the devices.
[00131] In another case, a layer 592 holds the device to the donor substrate 510. This layer can be a separate layer or part of the layers of the micro devices that are not etched during development of mesa structure comprising contact layers 512, 516, active layer 514 and pad 532.
In another case, this layer can be the continuation of one of the layers 572.
In this case, it can be either the metal or dielectric layer (SiN or SiO2, or other materials). In another case, the anchor is developed as a separate structure comprising extension 594, void/gap 596, or bridge 598. Here, a sacrificial layer is deposited and patterned with the same shape as the gap/void 596. Then the anchor layer is deposited and patterned to form the bridge 598 and/or extension 594. The sacrificial material can be removed later to create the void/gap 596. One can avoid the extension 594 as well. Similar to the previous anchor 592, this anchor can be made of different structural layers. In another case, the filling layers 574 act as anchor. In this case, the filling layers 574 can be etched or patterned or left as it is.
[00132] FIG. 5B shows the samples after removing the filler layer and or etching it to create the anchor 574. In another case, the adhesive force of the 598 layer after liftoff is enough to hold the device in place and act as an anchor. The final device on right side of FIG. 5B; these devices are shown in one substrate for illustration purposes only. One can use either one or combination of them in a substrate. A shown in FIG. 5C, the anchor can be covering the entire periphery of the device 574 or can be patterned to arms 594 and 592. Either of the structures can be used for any of the anchor structure. FIG. 5D shows one example of transferring the devices to a receiver substrate 590. Here the devices are bonded to the pads 582 or placed in a predefined area without any pads. The pressure force or separation force can release the anchor by breaking them. In another case, temperature can also release the anchor. Fig 5E shows the devices after being transferred to the receiver substrate and shows the possible release point 598-2 in the anchors. The anchor can also be directly connected to substrate or indirectly through other layers.
[00133] FIG. 6A shows a samples where the mesa structure is not etched through all layers. Here, the buffer layers 312 and/or some contact layer can stay. The mesa structure can include other layers that will be deposited and patterned before forming or after forming the mesa structure. These layers can be dielectric, MIS layer, contact, sacrificial layer and more.
After the mesa structure development, a filler layer (s) 374 is used to secure the devices.Here, the devices are bonded to a bonding layer(s) 378. Bonding layer(s) 378 can provide one or more of different forces such as electrostatic, chemical, physical, thermal or so on.
After the devices are removed from the donor substrate 310, the extra layers 312 can be etched away or patterned to separate the devices (FIG 6(C)). Other layers can be deposited and patterned such as contact layer. Here, one can etch the filler layer to separate the devices, or remove the sacrificial layer to separate the devices. Another case, temperature can be applied to separate the devices from the filler layer and make them ready to be transferred to receiver substrate. the separation can be done selectively. In, another case, the filler layer can be etched to form a (base for) anchor 374 as shown in FIG 6E. Another layers can be used to make the anchors 598-2. the filler layer can left or be removed from the anchor setup after forming the extra layers 598-2.
FIG 6G shows a device with a sacrificial layer 372-2. This layer can be either remove by etching or can be thermalling deformed or removed.
[00134] Due to mismatch between the substrate crystal lattice and the micro device layers, the growth of the layers contain several defects such as dislocation, void, and more. To reduce the defects, a buffer layer is deposited first and the active layers are followed subsequently. The thickness of this buffer layer is substantial. During the separation (lift off) of the microdevice from the substrate, the buffer layer is also separated.
Therefore, the buffer layer deposition should be repeated every time. FIG 6-1 A shows a structure on a substrate 6110 where there is a separation layer 6116 between buffer layer 6114 and actual device layers (6112). There can be another buffer layer 6118 between the separation layer 6116 and device layers 6112. The extra buffer layer 6118 can also block the contamination from separation layer to penetrate to the the device layers. Both buffer layers, 6110 and 6118 can have more than one layer. The separation layer can be also stack of different materials. In once case, the layer 6116 react to a wavelength of light that other layers are not responding to. This light source can be used to separate the actual device from the buffer layer and substrate. In another case, the layer 6116 reacts to chemicals while the same chemical do not affect other layers. This chemical can be used to remove or change the property of the layer 6116 to separate the device from the buffer layer 6114 and substrate 6110. This method leaves the buffer layer 6114 intact on the substrate 6110 and therefore it can be reused. for next device development. Before the next device deposition, some surface treatment such as cleaning or buffering can be done.
In one case the buffer layer can be zinc-oxide.
[00135] The microdevices can be separated by different etching process as demonstrated in FIG 6-1B prior to the separation process (lift off). The etching can etch the second buffer layer (if exist) 6118 and also part or all of the separation layer 6116. In another case, either the second buffer layer 6118 or separation layer 6116 are not etched. after this step, the microdevices are temporarily (or permanently) bonded to another substrate 6150 and the separation layer 6116 is removed or modified to separate the microdevices from the first buffer layer(s) 6114. As demonstrated in FIG 6-1C, the buffer layer stay intact on the substrate.
[00136] In another embodiment demonstrated in FIG 6-2, the layers are formed on the substrate 6210 as island. FIG 6-2A shows a top view of the islands. The island can be the same size or multiple size of the cartridge. The island can be formed starting from the buffer layers or after the buffer layer. Here surface treatment or gaps 6262, 6263 can be formed on the the surface to initiate the growth of the films as islands (FIG 6-28). To process the microdevices, the gaps can be filed by filler layers 6220. The filler can be polymer, metals, or dielectric layers.
After processing the microdevices, the filler layers 6220 can be removed.
[00137] FIG. 7 highlights the process of developing micro-device cartridges. During the first step 702, the micro-devices are prepared on a substrate. During this step, the devices are formed and post processing are performed on the devices. During the second step 704, the devices are prepared to be separated from the substrate. This step can involve securing the micro-devices by using anchor or fillers. During the third step 706, the cartridge is formed from the preprocessed micro devices in first and second steps 702, 704. In one case, during this step, the micro devices are bonded to the cartridge substrate through a bonding layer directly or indirectly. Then the micro devices are separated from the micro device substrates. in another case, the cartridge is formed on the micro-device substrate. After the devices are secured on the cartridge substrate, other processing steps can be done such as removing some layers, adding electrical (e.g. contact) or optical (lense, reflectors, ...) layers. The cartridge is moved to the receiver substrate to transfer the devices to the receiver substrate. Some these steps can be rearranged or merged.
[00138] FIG. 8 shows the steps of transferring the devices from the cartridge to the receiver substrate. Here, during the first step 802, a cartridge is loaded (or picked) or in another embodiment, a spare equipment arm is pre-loaded with the cartridge. During the second step 804, the cartridge is aligned with part (or all of) of the receiver substrate.
The alignment can be done through using dedicated alignment mark on cartridge and the substrate, or using the micro devices and the landing are on the receiver substrate. the micro devices are transferred to the selected landing areas during the third steps. If the receiver substrate is fully populated, the substrate is moved to the next steps. If further population is needed, it goes to further transfer steps. Before a new transfer cycle, if the cartridge does not have enough devices, the cycle start from first step 802. if the cartridge has enough devices, the cartridge is offset (or moved and aligned) to a new area of the receiver substrate 814 and new cycle continous to step 806. some of these steps can be merged and/or rearranged.
[00139] FIG. 9 shows the steps of transferring the devices from the cartridge to the receiver substrate. Here, during the first step 902, a cartridge is loaded (or picked) or in another embodiment, a spare equipment arm is pre-loaded with the cartridge. During the second step 902-2, a set of micro-devices is selected in cartridge that the number of defects in them is less than a threshold. During the third step 904, the cartridge is aligned with part (or all of) of the receiver substrate. The alignment can be done through using dedicated alignment mark on

- 25 -cartridge and the substrate, or using the micro devices and the landing are on the receiver substrate. The micro devices are transferred to the selected landing areas during the third steps. If the receiver substrate is fully populated, the substrate is moved to the next steps. If further population is needed, it goes to further transfer steps. Before a new transfer cycle, if the cartridge does not have enough devices, the cycle start from first step 902. if the cartridge has enough devices, the cartridge is offset (or moved and aligned) to a new area of the receiver substrate 902-2.
[00140] FIG
10 shows an exemplary processing steps for developing multi-type micro device cartridge. During the first step 1002, at least two different micro-devices are prepared on a difference substrates. During this step, the devices are formed and post processing are performed on the devices. During the second step 1004, the devices are prepared to be separated from the substrates. This step can involve securing the micro-devices by using anchor or fillers.
During the third step 1006, the first devices are moved to the cartridge.
During the fourth step 1008, at least second micro devices are moved to the cartridge. In one case, during this step, the micro devices are bonded to the cartridge substrate through a bonding layer directly or indirectly.
Then the micro devices are separated from the micro device substrates. In case of direct transfer, the different type of micro device can have different height to assist the direct transfer. For example, the second type of micro device that being transferred to the cartridge can be slightly taller than the first one (or the location on the cartridge can be slightly higher for the second micro device types). Here, after the cartridge is fully populated, the micro device height can be adjusted to make the surface of cartridge planar. This can be done either by adding materials to the shorter micro devices or by removing material from taller micro devices.
In another case, the landing area on the receiver substrate can have different height associated with the difference in the cartridge. Another method of populating the cartridge is based on pick and place. The micro devices can be moved to the cartridge by means of pick-and-place process.
Here, the force element on the pick-and-pance head can be unified for the micro devices in one cluster in the cartridge or it can be single for each micro devices. Also, they can be moved to the cartridge with other means. In another case, the extra devices are moved away from the substrate of first or second (third or other) micro devices and the other types of the micro devices are transferred into

- 26 -the empty areas. After the devices are secured on the cartridge substrate, other processing steps can be done such as adding filler layer, removing some layers, adding electrical (e.g. contact) or optical (lense, reflectors, ...) layers. The devices can be test after each before being used to populate the receiver substrate. The test can be electrical or optical or combination of two. the test can identify defects and/or performance of the devices on the cartridge.
The cartridge is moved to the receiver substrate during the last step 1010 to transfer the devices to the receiver substrate. Some these steps can be rearranged or merged.
[00141] FIG 11 shows one example of multi-type micro-device cartridge.
This cartridge includes three different micro devices 1102, 1104, 1106. It can have more device types.
The distance between micro devices xl, x2,x3 are related to the pitch of the landing areas in the receiver substrate. After few devices which can be related to the pixel pitch in the receiver substrate, there can be a different pitch x4, y2. This pitch is to compensate for mismatch between the pixel pitch and micro device pitch (landing area pitch). In this case, if pick and place is used for developing the cartridge, the force elements can be in form of columns corresponding to the column of each micro device types or it can be separate element for each micro device.
[00142] FIG 12 shows one example of multi-type micro-device cartridge.
This cartridge includes three different micro devices 1202, 1204, 1206. The other area 1206-2 can be spare micro devices (It can have more device types. The distance between micro devices xl, x2,x3 are related to the pitch of the landing areas in the receiver substrate.
After few devices which can be related to the pixel pitch in the receiver substrate, there can be a different pitch x4, y2. This pitch is to compensate for mismatch between the pixel pitch and micro device pitch (landing area pitch).
[00143] FIG 13 shows one example of micro devices 1302 prepared on substrate 1304 before transferring to multi-type micro-device cartridge. Here, one can use supporting layers 1306 1308 for individual device or for a group of devices. Here, the pitch can match the pitch in the cartridge or it can be multiple of cartridge pitch.
[00144] In all the structures above, it is possible to move the micro devices from the first cartridge to a second one prior to using them in populating a substrate.
Extra processing step

- 27 -can be done after transfer. or some of the the processing steps can be divided between first and secondary cartridge structure.
[00145] FIG 14A shows an example of microdevices in donor substrate 1480. The microdevices can have gradual non-uniformity across the donor substrate. Since the devices are transferred in block 1482 into the receiver substrates, the adjacent devices in the receiver substrate where one block end and another one starts 1484 can result in abrupt change as demonstrated in FIG I4B. This change can result in visual artifact for optoelectronic devices such as displays. In one embodiment shown in FIG 14C, the edge of the blocks are not sharp lines and the devices are skewed. Therefore, the average impact of the sharp transition is reduced significantly. The skew can be random and can have different profiles. FIG.
14D shows another embodiment where the microdevices in adjacent blocks are flipped so that the devices with similar performance are stay adjacent. This can keep the changes very smooth.
FIG. 14E shows an exemplary combination of flipping the devices and skewing the edges to improve the average uniformity furthermore. Here, the examples shows the device non-uniformity in one direction.
However, it can be in both directions so the methods described here can be used in both direction.
[00146] In one case, the performance of micro devices at the edges is matched for adjacent transferred block (array) prior to the transfer.
[00147] FIG 15A shows using two or more blocks 1582-1 1582-2, to populate a block in the receiver substrate. Here also the method of skewing or flipping can be used for further improving the average uniformity as demonstrated in FIG 15B. Also, random or defined pattern can be used to populate the cartridge with more than one block. FIG
16A shows a samples with more than one blocks. The blocks can be from the same donor substrate or different donor substrates. FIG 16B shows an example of populating cartridge from different blocks.
[00148] FIG 17 A and B show an structures with multiple cartridges 1790. Here, the position of cartridges are chosen in away to eliminate overlapping the same area in the receiver substrate with cartridges with the same micro-devices during different transfer cycle. In one case, the cartridge can be independent which means separate arms or controller is handling each cartridge independently. In another case, the alignment can be done independently, but the other

- 28 -actions can be synchronized. In this case, the substrate can move to facilitate the transfer after the alignment. In another case, the cartridges move together to facilitate the transfer after the alignment. In another case, both can move to facilitate the transfer. In another case, the cartridges can be assembled in advanced. In this case, a frame or substrate can hold the assembled cartridges. The distance X3, Y3 between cartridge 1790 can be a multiple of the width X 1, X2 or length Y I, Y2 of the cartridge 1790. It can be a function of moving steps to different direction.
For example, X3 = KX1+HX2, where K is the movement step to left (directly or indirectly) and II is the movement steps to the right (directly or indirectly) for populating a substrate. The same can be used for distance between cartridge Y3 and the length of Y1 and Y2. As shown in FIG
17A, the cartridges can be aligned in one or two direction. In another case, shown in FIG 17B, the cartridges are not aligned in at least one direction. Each cartridge can have independent control for applying pressure and temperature toward the substrate. The Other arrangement is also possible depending on the direction of movement between substrate and cartridges.
[00149] In another case, the cartridges can have different devices and therefore populating different areas in the receiver substrate with different devices.
In this case, relative position of cartridges and receiver substrate changes after each transfer cycle to populate different area with all the required micro devices from different cartridges.
[00150] In another case, several array of cartridges are prepared. Hereafter devices are transferred to the receiver substrate from first array of cartridges, the receiver is moved to the next array of micro devices to fill the remaining areas in the receiver substrate or receive different devices.
[00151] In another case, the cartridges can be on a curve surface and therefore circular movement provide contact for transferring micro devices into substrate.
[00152] The process of micro devices generally starts by developing a stack of crystalline layers on top of a substrate. Then by extra processing steps, the stack of the films is transformed into micro devices. In some cases, the substrate has different crystalline lattice compared to the crystal lattice of the stacked layers. In one case, a thick buffer layer is deposited first to masks the defects caused by the lattice mismatch. The main challenge is that the buffer

- 29 -layer is thick and therefore causes the cost goes high and the throughput to drop. Moreover, the buffer layer does not eliminate all the defects.
[00153] In one case, a sacrificial layer is used between buffer layer and the stacked layers. Therefore, instead of lifting off the stacked layers and the buffer layers to transfer the micro devices, the layers after the sacrificial layer are liftoff.
[00154] FIG 19 shows an embodiments using a template for transferring multiple cartridges to populate a system substrate with micro devices, here, the template have more than one cartridge, during first step 1902, at least one cartridge is aligned with the template which has some alignment mark facilitating the alignment process. During the second step 1904, at least one cartridge is bonded to the template. The bonding mechanism could be different forms such as thermal, optical, vacuum, van der waals, etc. There can be a loop 1906, that repeats the steps 1902, 1904 to bond more cartridges to the template. Then the template is aligned with the receiver substrate.
[00155] FIG 20 shows an example of a template transfer system. Here, the template 2002, has multiple cartridges 2004 which can be loaded on a structure 2002-2.
The said structure 2002-2 can offer more rigidity and also a high profile. The height profile can be controlled independently for each structure 2002-2. The structure 2002-2 can be the same size, smaller or larger than the cartridge. This structure 2002-2 can be also a bonding apparatus that assist the transfer of microdevices from the cartridge 2004 into receiver substrate 2010.
The bonding apparatus can provide pressure, temperature, optical, and other type of force to assist the transfer.
In another case, the bonding apparatus 2006 is at the other side of the template 2002. Also, some support structure 2008 can hold the template in place. The support 2008 can be at either side of the template 2002. In one case, the support structure can be the same as the bonding apparatus. In another case, there is a separate bonding apparatus for each cartridge. In another case, the bonding apparatus is the same for at least more than one cartridges. The receiver substrate 2010 also has support structures 2014, 2016. The support structure can be at either side of the receiver substrate. In one case, the receiver substrate may have bonding apparatus 2012 that can assist or initiate the bonding process. Either bonding apparatus 2006 or 2012 can be used for bonding.
The support structure 2014 can be the same as the receiver bonding apparatus 2012. In another

- 30 -case, multiple template can be used to populate a receiver substrate. Here, each template can be aligned independently with the receiver substrate.
[00156] The support structure can be a suction apparatus, magnetic, a spring loaded pin, a gas bed made of pressured gas such as air or nitrogen, etc.
[00157] the area between cartridge 2004 and bonding apparatus 2006 on the template 2002 can have different thermal and or mechanical property. In one case it can be made of different material with higher thermal conduction. In another case, vias may form on template in either different areas or at least in one of the area between the cartridge 2004 and apparatus 2006 and the other areas. The size of the VIAs can be adjusted for each area to adjust the mechanical property. In another case, the VIAs can be filed with different materials to adjust the mechanical and or thermal property of different areas of the template 2002, [00158] The invention being thus described, it will be obvious that the same may be varied in many ways. Such variations are not to be regarded as a departure from the scope of the invention, and all such modifications as would be obvious to one skilled in the art are intended to be included within the scope of the following claims.

Claims

WHAT IS CLAIMED IS:

1. A method of transferring microdevices into a receiver substrate where microdevices are arranged in a cartridge that can be released after transferred to a receiver substrate;
the cartridges are arranged in a template that has alignment mark for aligning the cartridges with the template;
the said template is aligned with the receiver substrate; and at least one microdevice is transferred to the receiver substrate

2. The method of transfer according to claim 1 where the process of aligning template with receiver substrate may include stretching the template

3. A transfer setup that includes a template holding more than one cartridges filled with microdevices a bonding apparatus that assist the transfer of microdevices from at least one cartridge to a receiver substrate by means of generating a transfer force

4. The transfer setup according to claim 3 where at least two cartridges have different bonding apparatus.

5. The transfer setup according to claim 3 where some support structure fixing the receiver or the template.

6. The transfer setup according to claim 5 where the support structure can be a suction apparatus

7. The transfer setup according to claim 5 where the support structure can be a spring loaded pin.

8. The transfer setup according to claim 5 where the support structure can be a gas bed made of pressured gas such as air or nitrogen, etc.

9. The transfer setup according to claim 3 where there can be a height adjusting apparatus between the template and the cartridge