Methods of forming displays and displays

Abstract

A method of forming a display includes: bonding a backplane including a plurality of backplane electrical contacts to a monolithic light-emitting diode (LED) structure including corresponding plurality of electrical contacts, wherein the bonding includes forming a reversible bond between at least one of the plurality of backplane electrical contacts and a corresponding electrical contact of the monolithic LED structure; and removing material from the monolithic LED structure to provide a plurality of physically isolated LED dies, thereby enabling the removal and / or replacement of at least one physically isolated LED die by reversing the reversible bond between the at least one of the plurality of backplane electrical contacts and the corresponding electrical contact of the monolithic LED structure.

Description

Technical Field

[0001] This invention relates to the formation of displays. Specifically, but not exclusively, this invention relates to a monolithic micro-light-emitting diode (LED) display and a method for forming a monolithic micro-LED display, the display having the ability to replace pixels. Background Technology

[0002] As is well known, light-emitting diode (LED) devices provide a highly efficient and controllable light source for display applications. Advantageously, implementing LED devices as micro-LED arrays with small pixels of ultra-fine pitch enables the production of high-resolution displays. However, the presence of any defective LED device in such an array is problematic. Typically, to provide an acceptable display, the number of dead pixels (e.g., defective LED devices in a micro-LED array) is preferably less than 2 dead pixels per 2 million pixels (i.e., a yield of 99.9999%).

[0003] Achieving such high yields using known processes may be difficult. To reduce defective pixels in LED devices, redundancy schemes are known to be implemented, where spare devices are placed in the LED array to provide light to the pixels in the event of any device failure. However, this redundancy scheme uses additional space, which impacts the provision of tightly packaged small LED devices (dies) and therefore the pixels in micro-LED displays.

[0004] While monolithic growth of device arrays is advantageous for providing miniature LED arrays with ultra-fine pitch, it is difficult to repair any defective LED devices because they become part of the integrated structure. Therefore, achieving monolithically formed ultra-fine LED arrays with sufficient pixel yield is challenging. Summary of the Invention

[0005] To mitigate at least some of the aforementioned problems, a method for forming a display is provided, the method comprising: bonding a backplane including a plurality of backplane electrical contacts to a monolithic light-emitting diode (LED) structure including corresponding plurality of electrical contacts, wherein the bonding comprises forming a reversible bond between at least one of the plurality of backplane electrical contacts and a corresponding electrical contact of the monolithic LED structure; and removing material from the monolithic LED structure to provide a plurality of physically isolated LED dies, thereby enabling the removal and / or replacement of at least one physically isolated LED die by reversing the reversible bond between the at least one of the plurality of backplane electrical contacts and the corresponding electrical contact of the monolithic LED structure.

[0006] A display is also provided, comprising: a backplane including a plurality of backplane electrical contacts bonded to a plurality of physically isolated light-emitting diode (LED) dies having electrical contacts, wherein at least one of the plurality of backplane electrical contacts is bonded to a corresponding electrical contact of the plurality of physically isolated LED dies using reversible bonding, thereby enabling the removal and / or replacement of at least one physically isolated LED die by reversing the reversible bonding between the at least one backplane electrical contact and the corresponding electrical contact of the plurality of physically isolated LED dies, wherein the plurality of physically isolated LED dies are formed of a monolithic LED structure.

[0007] Advantageously, forming the display by bonding a backplane to a monolithic LED structure, removing material, and forming a reversible bond between at least one of the multiple backplane electrical contacts and a corresponding electrical contact of the monolithic LED structure means that individual LED dies can be identified and replaced, thereby ensuring a sufficiently high yield of functional devices in the display without needing to use space for redundancy. Advantageously, an array of luminescent pixels can be provided in a high-resolution display with the ability to replace individual LED dies when needed.

[0008] Preferably, at least one of these backplane electrical contacts is reversibly bonded to the corresponding electrical contact of the monolithic LED structure using metal-to-metal bonding and / or eutectic bonding. Advantageously, such bonding facilitates the removal and replacement of LED devices while providing conductivity to form a properly functioning device, and simultaneously providing a reflective surface to aid in light extraction from the individual LED device.

[0009] Preferably, the method includes: removing at least one physically isolated light-emitting diode (LED) die; and replacing the at least one physically isolated LED die with one or more different LED dies. Advantageously, the display is adapted to provide light emission from individual light-emitting devices arranged in an array having preferred light emission characteristics.

[0010] Preferably, the method includes: removing at least one physically isolated LED die by increasing the temperature of the display, thereby enabling the removal of the at least one physically isolated LED die at the reversible bond between the backplane electrical contact and a corresponding electrical contact associated with the monolithic LED structure. Preferably, increasing the temperature of the display includes raising the temperature of the reversible bond above the eutectic temperature of the reversible bond. Preferably, the reversible bond includes at least one of AuSn eutectic bonding, CuSn eutectic bonding, and InSn eutectic bonding. Advantageously, a controllable method is proposed that simultaneously achieves conductivity, reversible bonding, and relatively high reflectivity for enhanced light extraction.

[0011] Preferably, removing at least one physically isolated LED die includes overcoming the electrostatic force of the reversible bond, preferably wherein the electrostatic force of the reversible bond is at least one of Au-Au metal bonding and Cu-Cu metal bonding. Advantageously, metal-metal bonds can be provided that simultaneously achieve conductivity, reversible bonding, and relatively high reflectivity for enhanced light extraction.

[0012] Preferably, the method includes: testing at least one of the plurality of physically isolated light-emitting diode (LED) dies; identifying one or more defective LED dies; removing the defective LED die; and replacing the one or more removed LED dies. Advantageously, a display with high-yield operating devices is provided based on monolithically grown LED devices, thereby providing a high-resolution display.

[0013] Preferably, the method includes forming a conformal metal layer on at least a portion of these physically isolated LED dies, thereby reducing optical crosstalk between the physically isolated LED dies. Advantageously, this enhances light extraction from individual LED dies and improves the contrast between pixels associated with LED dies.

[0014] Preferably, the method includes forming a transparent conductive layer on the plurality of isolated light-emitting diode dies to provide a common electrode. Advantageously, multiple devices in the array are simultaneously contacted, thereby efficiently fabricating a large number of devices.

[0015] Preferably, the method includes forming one or more magnetic metal regions associated with at least one of these physically isolated LED dies, thereby facilitating the removal of the physically isolated LED dies. Advantageously, the removal of the individual dies is enhanced by using a magnetic material, thereby overcoming any residual forces that would aid in the removal of the individual LED devices.

[0016] Preferably, at least one of these reversible bonds is at least partially laterally surrounded by a dielectric layer, thereby separating the backplane and the monolithic LED structure. Preferably, the dielectric layer comprises at least one of SiO2, Si3N4, Su-8, SrF2, PDMS, and PMMA. Advantageously, the dielectric layer allows for uniform processing without hindering the removal of individual LED dies.

[0017] Preferably, the plurality of contacts of the monolithic light-emitting structure comprises a highly reflective metal, preferably one of nickel (Ni) and silver (Ag). Advantageously, this metal also provides conductivity and facilitates light extraction.

[0018] Preferably, removing material from the monolithic LED structure involves forming a discontinuity in at least one layer of the monolithic LED structure. Preferably, the at least one layer of the monolithic LED structure is an n-type layer, more preferably, the n-type layer is an n-doped gallium nitride layer. Advantageously, forming the discontinuity enables the removal and replacement of individually physically isolated dies. Attached Figure Description

[0019] Specific embodiments will now be described by way of example only, with reference to the accompanying drawings, in which:

[0020] Figure 1A The epitaxial crystal structure is shown;

[0021] Figure 1B The process of forming the countertop is shown. Figure 1A Epitaxial crystal structure;

[0022] Figure 1C It shows the further processed Figure 1B The structure;

[0023] Figure 1D It shows the further processed Figure 1C The structure;

[0024] Figure 1E It shows the further processed Figure 1D The structure;

[0025] Figure 2 The processed backplate is shown;

[0026] Figure 3A Showing the bonding to Figure 2 The back panel Figure 1E The structure;

[0027] Figure 3B It shows the further processed Figure 3A The structure;

[0028] Figure 3C It shows the further processed Figure 3B The structure;

[0029] Figure 3D This shows the process of further processing to remove the LED die. Figure 3C The structure;

[0030] Figure 4A It shows a replacement LED die Figure 3D The structure;

[0031] Figure 4B It shows the further processed Figure 4A The structure;

[0032] Figure 4C It shows the further processed Figure 4B The structure;

[0033] Figure 4D It shows the further processed Figure 4C The structure; and

[0034] Figure 5 It shows the further processed Figure 3B The structure. Detailed Implementation

[0035] As mentioned above, while monolithically grown LED devices are advantageous for producing micro-LED displays with ultra-fine pitch for high-resolution display applications, there are difficulties associated with defective LED dies in the display array. Refer to Figures 1 to... Figure 5 The described process and structure enable the repair and replacement of monolithic microLED displays, achieving the necessary yield requirements while avoiding the need to transfer large numbers of pixels using methods such as pick-and-place mass transfer. This method and structure enable the provision of pixel display arrays, for example, in which the luminescent surface area of ​​each pixel is less than or equal to 100 μm. 2 Preferably less than or equal to 16 μm 2 Furthermore, the pixel pitch is less than 10 μm, preferably less than 4 μm, and more preferably less than 3 μm.

[0036] Advantageously, while the methods and structures described herein are used to replace defective dies, in other examples, they are used to provide LED dies in an array configured to emit light at different wavelengths compared to dies formed in a monolithically grown LED device array. For example, it is known to provide highly efficient LED devices based on nitride materials configured to emit light with a dominant peak wavelength of blue or green, but providing red light using such materials is challenging. Gallium arsenide (GaAs)-based materials are, for example, a well-established technology for LED dies emitting red light. Therefore, in this example, the methods described herein are used to replace LED dies in a monolithically grown nitride-based LED die array to provide light at a different wavelength. Advantageously, the number of dies transferred to the monolithically grown array is far less than the total number of dies in the array, thus providing a more efficient and practical method for forming high-resolution multicolor microLED arrays.

[0037] Figure 1AA cross-sectional view of the epitaxial crystal structure 100A is shown. The epitaxial crystal structure 100A is a structure formed from crystal layers that are sequentially grown or deposited to provide a light-emitting structure. The epitaxial crystal structure 100A is provided using metal-organic chemical vapor deposition (MOCVD). In another example, alternative and / or additional growth and / or deposition methods (e.g., molecular beam epitaxy (MBE)) are used to provide the epitaxial crystal structure 100A. Advantageously, the epitaxial crystal structure 100A is provided using a continuous growth process and has high crystal quality and low defect density. In another example, the epitaxial structure 100A is provided using multiple growth steps that enable the selective provision of specific properties, such as emitting light of different wavelengths upon radiative recombination of charge carriers from different regions of the epitaxial crystal structure 100A.

[0038] exist Figure 1A The diagram shows a growth substrate 102 on which an n-type region 104 is grown. The growth substrate 102 is a silicon substrate. Alternatively, in another example, a different material is used to provide the growth substrate 102. The n-type region 104 is formed of n-type doped gallium nitride (GaN). In another example, the n-type region 104 is formed by additional and / or alternative layers. For example, a further buffer layer is included. On top of the n-type region 104, an active region 106 is shown. The active region 106 is configured to emit light upon recombination of carriers injected from the n-type and p-type regions. The active region 106 includes a multiple quantum well (MQW) structure. In another example, the active region includes a single quantum well (SQW) structure. The active region 106 is configured to emit light with a controllable dominant peak wavelength. In another example, different portions of the active region 106 are configured to emit light with different dominant peak wavelengths.

[0039] On top of the active region 106, a p-type region 108 is shown. The p-type region 108 is formed of p-type doped GaN. In another example, the p-type region 108 is formed by additional and / or alternative layers.

[0040] Epitaxial crystal structure 100A is based on a III-V group material (such as a III-nitride material, for example, a GaN-based material). While this structure is shown as a nitride-based structure, in other examples, different materials are used to provide a monolithic array of light-emitting devices. Although an n-type region 104, an active region 106, and a p-type region 108 are shown, those skilled in the art will understand that in other examples, additional layers and / or alternative layers are used to provide the epitaxial crystal structure 100A. Once as shown... Figure 1A An epitaxial crystal structure 100A is provided, and this epitaxial crystal structure is processed to form multiple monolithically grown LED devices. This is in Figure 1B As shown in the image. Figure 1B It shows the basis Figure 1A A cross-sectional view of the processed structure 100B of the epitaxial crystal structure 100A, in which mesa 110 has been formed.

[0041] Mesa 110 each includes portions of a p-type region 108 and an active region 106. Mesa 110 is shown as having been formed on an n-type region 104. Mesa 110 is formed by selectively patterning and etching the epitaxial crystal structure 100A using known techniques. Those skilled in the art will understand that alternatively and / or additionally, mesa 110 is formed from different layers and / or additional layers.

[0042] Once such Figure 1B As shown, a platform 110 is formed, and the process then moves to... Figure 1C In this figure, the conformal layer 112 is deposited on the platform 110. Figure 1C A cross-sectional view of the machined structure 100C is shown. This machined structure is... Figure 1B A fabricated version of structure 100B is shown. A conformal layer 112 formed on mesa 110 is illustrated. The conformal layer 112 is deposited using known deposition techniques and is formed to prevent irreversible bonding with other layers in later stages. The conformal layer 112 is a dielectric layer formed of silicon dioxide (SiO2). Alternatively and / or additionally, in other examples, the conformal layer is a dielectric layer formed of different materials, such as silicon nitride (Si3N4), photoresist (e.g., Su-8), strontium fluoride (SrF2), polydimethylsiloxane (PDMS), or polymethyl methacrylate (PMMA). In other examples, this or any other suitable material is used to prevent reversible bonding at contacts, while the portion of the conformal layer 112 in contact with the backplane (to which the final structure will be bonded).

[0043] The conformal layer 112 is further processed to provide contact with the p-type region 108. This is in Figure 1D As shown in the image. Figure 1D A cross-sectional view of the fabricated epitaxial structure 100D is shown, which is about Figure 1C The described structure is a machined version of 100C. Figure 1C The structure 100C is processed to selectively pattern and etch windows through the conformal layer 112, thereby exposing at least a portion of each of the mesa 110, on which p-type contacts that will contact the p-type region 108 will be formed. Once the windows are provided, p-type contacts 114 are formed in the windows on the mesa 110.

[0044] The p-type electrical contact 114 is formed of metal. In this example, the metal is relatively highly reflective. Advantageously, the use of a relatively highly reflective p-type electrical contact 114 facilitates light extraction from the individual LED dies formed on the mesa 110 of the monolithic growth structure 100. The p-type electrical contact 114 is formed to achieve metal bonding (such as gold-gold (Au-Au) or copper-copper (Cu-Cu) bonding) and eutectic bonding (gold-tin (Au-Sn), copper-tin (Cu-Sn), indium-tin (InSn)) with the backplane. Alternatively and / or additionally, in other examples, the p-type electrical contact 114 is formed of any suitable reflective conductive material that can be used to form reversible bonding. In this example, the p-type electrical contact 114 is formed of nickel and / or silver. The p-type electrical contact 114 is used to form reversible bonding with other backplane devices and is therefore formed of a material that facilitates such reversible bonding. This will be described in more detail below.

[0045] Once such Figure 1D As shown, a p-type electrical contact 114 is formed on the platform 110, and the process then moves to... Figure 1E The content shown. In Figure 1E The diagram shows a cross-sectional view of structure 100E, which is a... Figure 1D It is obtained by further processing the epitaxial structure 100D to make the structure planar.

[0046] Therefore, in Figure 1E The diagram shows material 116 deposited into the gaps formed between mesa 110, the surface of which has been planarized. This planarization is achieved by deposition of material 116 and chemical mechanical polishing to form a flat surface suitable for bonding to another device. In another example, alternative and / or additional methods are used to planarize the surface opposite to the growth substrate 102. Material 116 is a metal. In another example, alternative and / or additional materials 116, such as dielectric materials, are used. Once structure 100E is provided, it is bonded to a backplane structure, as referenced below. Figure 2 As shown in Figure 3.

[0047] Figure 2 A fabricated backplane 200 is shown, which has been processed to reversibly bond to a monolithically grown LED array, as described above with respect to Figure 1.

[0048] Figure 2A CMOS backplane 202 with a dielectric layer 204 deposited thereon is shown. The dielectric layer 204 is processed to pattern and selectively etch windows, and material is deposited in these windows using known techniques to form backplane electrical contacts 206. The formation of the windows exposes portions of the CMOS backplane 202, and p-type contacts can be connected to these portions to control light emission from individual LED devices in an LED device array. While the backplane 202 is a CMOS backplane 202, in other examples, additional and / or alternative backplanes are used to bond to LED-based structures to form a properly functioning display.

[0049] Back panel contact 206 is designed to be with Figure 1E The p-type electrical contacts 114 of the structure 100E shown form a reversible bond. Therefore, backplate contacts 206 are formed to achieve metallic bonding (such as gold-gold (Au-Au) or copper-copper (Cu-Cu) bonding) and eutectic bonding (such as gold-tin (Au-Sn), copper-tin (Cu-Sn), indium-tin (InSn)). Therefore, for forming... Figure 1E The material combination of the p-type contact 114 and the backplate electrical contact 206 of the structure 100E shown was selected to provide a material combination that can reversibly bond.

[0050] The dielectric layer 204 is formed of silicon dioxide. Alternatively and / or additionally, the dielectric layer 204 is formed of silicon nitride, Su-8, SrF2, PDMS, PMMA, or any other suitable material. The dielectric layer 204 is formed such that it contacts the conformal layer 112, and therefore, the aim is to prevent oxide-oxide combinations from forming during bonding, so that the dielectric layer 204 does not form irreversible bonds with the conformal layer 112. Therefore, the material combination used to form the conformal layer 112 and the dielectric layer 204 is selected to provide a material combination that provides reversible bonding at the electrical contacts rather than at other portions of the interface between the processed backplane 200 and the monolithically grown epitaxial structure 100E.

[0051] Once the processed backplate 200 and structure 100E are provided, they are bonded together. This is in Figure 3A As shown in the image.

[0052] Figure 3A Structure 300A shows Figure 1E 100E structure bonded to Figure 2A cross-sectional view of the fabricated structure 200 is shown. Structure 100E and fabricated structure 200 are bonded using thermocompression bonding technology. In another example, additional and / or alternative techniques are used to bond structures 100E and 200. Accordingly, p-type electrical contacts 114 are aligned with backplane contacts 206 of the fabricated backplane 200. Although the combined structure 300A is shown in cross-section, those skilled in the art will understand that this process is used for monolithically growing and bonding a two-dimensional LED device array to the flat surface of the fabricated backplane 200 on the growth substrate 102. The p-type electrical contacts 114 of the monolithically grown LED array are arranged to overlap with the backplane contacts 206 of the backplane 200, thereby forming a reversible bond between the p-type contacts 114 of the monolithically grown LED array and the backplane contacts 206 of the backplane 200.

[0053] Once the backplate 200 is bonded to the structure 100E to provide Figure 3A For structure 300A, the growth substrate 102 of epitaxial crystal structure 100A is removed. This is in Figure 3B As shown in the image. Figure 3B Structure 300B is shown, which is a... Figure 3A The structure 300A is obtained by processing to remove the growth substrate 102. Once the growth substrate 102 is removed, the n-type region 104 is exposed and can be selectively patterned and etched using known techniques. This is in Figure 3C As shown in the image.

[0054] Figure 3C A cross-sectional view of structure 300C is shown, which is a... Figure 3B The structure 300B is further processed to selectively etch through the n-type region 104, the conformal layer 112, and the planarization material 116, so as to expose at least a portion of the dielectric layer 204 associated with the backplane 200 through the etched trench 302. Advantageously, such etching physically isolates the structure from the aforementioned... Figure 1B The described formation consists of individual mesa 110 associated with LED dies (and thus associated pixels). This physical isolation of the LED dies creates discontinuous n-type regions 104 because etched channels 302 surround the individual LED dies to physically isolate them. Advantageously, a monolithically grown array of LED devices is formed, enabling the provision of a high-resolution pixel array while further achieving individual isolation of the LED dies.

[0055] Physically isolating individual LED dies associated with each pixel means that individual pixels (or LED dies) are bonded to the backplate 202 via a bond between the backplate contacts 206 of the backplate and the p-type electrical contacts 114 of the LED die. There is no apparent bond between the dielectric layer 204 and the conformal layer 112, or between the planarization material 116 and the dielectric layer 204. The bond between the backplate contacts 206 of the backplate 200 and the p-type electrical contacts 114 of the LED die is a reversible bond, meaning that these bonds can be broken to remove the die, and these bonds can be reformed to bond a replacement die in the same location. This reversible bond is a metal-to-metal bond formed by thermocompression bonding or a eutectic bond. In another example, alternative and / or additional reversible bonds are formed using other suitable materials to provide a reversible conductive bond between the backplate 200 and the LED die.

[0056] Once the individual dies are isolated, they can be tested to identify any defective dies. Once a defective die is identified, it can be removed by reversibly breaking the bond between a specific backplane contact 206 on the backplane and the associated p-type contact 114 of the defective die / pixel. Such dies are removed once identified. This is in Figure 3D As shown in the image.

[0057] exist Figure 3D The image shows a further processed form to provide structure 300D. Figure 3C The cross-sectional view of structure 300C, through this processing, Figure 3C The central LED has been removed 304. This removal is facilitated by heating the area associated with the backplate contacts 206 and p-type electrical contacts 114 of the backplate 200 above a temperature threshold that allows the LED die to separate from the backplate 200. This temperature threshold that allows the LED die to separate from the backplate 200 is the eutectic temperature of the eutectic bonding. In another example, the temperature threshold is based on different metrics, such as the melting point of the metal or other suitable temperatures. Once the force bonding the backplate contacts 206 of the backplate 200 to the p-type electrical contacts 114 of the LED device is sufficiently small, the defective die is removed by a suction process. In another example, additional and / or replacement techniques are used to remove selected LED dies. Additionally, in another example, plasma treatment is used to remove any residual material left on the surface during the removal process. Once the defective die has been removed, a replacement die can be deposited. This is in Figure 4A As shown in the image.

[0058] Figure 4A A cross-sectional view of structure 400A is shown, which is a... Figure 3DThe structure 300D is further processed to provide a replacement LED die 402. The replacement LED die 402 (which includes an n-type region, a p-type region, an active region, and a p-type contact 414) contacts the backplate 202 via the backplate contact 206 of the backplate 200 and the p-type contact 414 of the replacement LED die 402, thereby forming a eutectic bond between the backplate contact 206 and the p-type contact 414. A conformal layer 404 is formed on the LED die 402 in a manner similar to the conformal layer 112 of the monolithic growth structure described with respect to Figures 1 to 3. Although this bonding is a eutectic bond, in other examples, alternative and / or additional bonding methods are used to secure the LED die 402 in the structure 400A.

[0059] Although about Figure 3D and Figure 4A The process illustrated demonstrates the replacement of a defective die. Additionally and / or alternatively, in other examples, the LED die can be removed to replace it with a different device. For instance, in cases where the method for forming a high-efficiency red-emitting LED differs from the method for forming high-efficiency blue and / or green-emitting LEDs, a red-emitting device (such as an AlInGaP-based red-emitting LED) can be inserted into a monolithically grown array of such high-quality blue and / or green-emitting LEDs. Advantageously, the number of replacement LEDs inserted to provide a multi-color LED array is significantly less than that required by a pick-and-place technique.

[0060] Once such Figure 4A As shown, the defective / unwanted die was replaced, and the process then moved to... Figure 4B .exist Figure 4B The image shows the process of processing to provide... Figure 4B Structure 400B Figure 4A A cross-sectional view of structure 400A. Structure 400B includes a conformal metal layer 406 deposited on structure 400A. This conformal layer 406 serves to reduce optical crosstalk between pixels associated with the light-emitting device dies in the display array. Once in Figure 4B A conformal metal layer 406 was deposited in the middle, and the process then moved to Figure 4C .

[0061] exist Figure 4C The image shows a cross-sectional view of structure 400C, which is a... Figure 4BThe structure 400D is further processed by anisotropic etching of the metal conformal layer 406. This anisotropic etching results in the metal being left on the sidewalls of the light-emitting die. Once this anisotropic etching is performed, a filler material 408 is formed in the gaps between the LED devices. This filler material 408 is deposited using known techniques and planarized using chemical mechanical polishing. In another example, alternative and / or additional methods are used to planarize the n-type side of the device in structure 400C. Once structure 400C is planarized, the process moves to providing Figure 4D The structure shown.

[0062] Figure 4D A cross-sectional view of structure 400D is shown, which is a... Figure 4C The structure 400C is further processed to deposit a transparent conductive material layer 410. This layer is formed of indium tin oxide (ITO). Alternatively and / or additionally, in other examples, different conductive transparent materials are used. The transparent conductive material layer 410 enables the formation of n-type contacts with the n-type regions 104 of multiple currently isolated dies. In other examples, alternative and / or additional layers, such as metal tracks, are used to assist current diffusion.

[0063] Accordingly, a method for providing repaired and / or replaced dies in a monolithically grown die array is described, wherein multiple dies provide a light source at a light-emitting surface associated with a pixel driven by a CMOS backplane 202.

[0064] Technical personnel should understand that different and / or additional layers can always be implemented to provide advantageous functionality. For example, Figure 5 It demonstrates how to enhance the stripping of selected dies. Figure 5 Structure 500 is shown, which is Figure 3B The structure is obtained by attaching a magnetic material 502 associated with each die. Such a magnetic material 502 (e.g., iron, nickel, cobalt) is deposited on the pixel-associated portion of each LED device. In another example, alternative and / or additional configurations are used to provide the magnetic functionality associated with each die. The magnetic material 502 is used to facilitate stripping after pixel isolation. Once repair and / or replacement of defective and / or unwanted dies have been performed, the magnetic material 502 is etched away, thereby enabling further deposition as described above. Figure 4D The transparent conductive material 410 is described.

[0065] Advantageously, the method described herein enables repairs to be performed on a single microdisplay, thereby allowing the necessary yield requirements to be met. Furthermore, the method enables the deposition of light-emitting LEDs of different colors on a single microdisplay, such as depositing red LED dies onto a blue / green single microdisplay.

[0066] Although the processes described above are shown in a specific order, alternative and / or additional steps are provided in other examples to achieve the removal and replacement of LED dies in a monolithically grown LED device array.

[0067] Although the epitaxial structures described herein are based on the principle of first performing n-type growth on a growth substrate, then forming active and p-type regions, and subsequently forming p-type contacts on top of the mesa for connection to a backplane, those skilled in the art will understand that, in other examples, these techniques are applicable to structures formed in different ways, such as those based on a reverse growth sequence, and / or having additional or alternative layers, and / or having n-type contacts formed on the mesa for reversible bonding at corresponding contacts on the backplane.

Claims

1. A method of forming a display, comprising: The backplane, which includes multiple backplane electrical contacts, is planarized to provide a first planarized surface; The monolithic light-emitting diode structure, which includes multiple electrical contacts, is planarized to provide a second planarized surface, wherein the multiple electrical contacts correspond to the multiple electrical contacts of the backplate; The first planarized surface is bonded to the second planarized surface, wherein the bonding includes forming a reversible bond between at least one of the plurality of backplane electrical contacts and the corresponding electrical contact of the monolithic light-emitting diode structure; as well as The monolithic LED structure is then selectively etched to provide a plurality of physically isolated LED dies, thereby enabling the removal and / or replacement of at least one physically isolated LED die by reversing the reversible bonding between at least one of the plurality of backplane electrical contacts and the corresponding electrical contact of the monolithic LED structure.

2. The method according to claim 1, wherein, At least one of these backplane electrical contacts is reversibly bonded to the corresponding electrical contact of the monolithic light-emitting diode structure using metal-to-metal bonding and / or eutectic bonding.

3. The method according to any of the preceding claims, comprising: Remove at least one physically isolated LED die; as well as Replace the at least one physically isolated LED die with one or more different LED dies.

4. The method according to claim 3, wherein, Removing at least one physically isolated LED die involves increasing the temperature of the display, thereby enabling the removal of the at least one physically isolated LED die at the reversible bond between the backplane electrical contacts and the corresponding electrical contacts associated with the monolithic LED structure.

5. The method according to claim 3, wherein, Removing at least one physically isolated LED die involves overcoming the electrostatic force of the reversible bond.

6. The method according to claim 1, comprising: Test at least one of the multiple physically isolated LED dies; Identify one or more defective LED dies; Remove defective LED chips; as well as Replace one or more of the removed defective LED dies.

7. The method according to claim 1, comprising: A conformal metal layer is formed on at least a portion of these physically isolated LED dies to reduce optical crosstalk between physically isolated LED dies.

8. The method according to claim 1, comprising: A transparent conductive layer is formed on the multiple isolated light-emitting diode dies to provide a common electrode.

9. The method according to claim 1, comprising: One or more magnetic metal regions are formed associated with at least one of these physically isolated LED dies, thereby facilitating the removal of the physically isolated LED dies.

10. The method according to claim 1, wherein, At least one of these reversible bonds is at least partially surrounded laterally by a dielectric layer, thereby separating the backplane from the monolithic LED structure.

11. The method according to claim 1, wherein, The multiple contacts of this monolithic light-emitting diode structure include highly reflective metal.

12. The method according to claim 1, wherein, Removing material from the monolithic LED structure involves forming a discontinuity in at least one layer of the monolithic LED structure.

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