Background

Field

[0001] Embodiments of the present disclosure generally relate to micro-LEDs, and methods of forming micro-LEDs. In particular, a method for manufacturing red micro-LEDs on the same substrate, such as a silicon wafer, with pre existing blue micro-LEDs and/or green micro-LEDs, is disclosed.

Description of the Related Art

[0002] Micro-LEDs (light-emitting diodes) are being considered for use in next- generation display devices. To realize a full display of colors, conventional attempts of micro-LED pixels utilize red, green, and blue micro-LEDs. Blue and green micro-LEDs are typically built from a stack of layers based on hexagonal (wurtzite) gallium nitride (GaN), with the active emitter layers incorporating varying concentrations of Indium (InGaN) to modulate the color. The stack of layers are either grown as blanket films that are subsequently patterned and etched into micrometer-sized structures, or grown selectively as micrometer structures in pre-defined areas opened in between dielectric layers. These micro- LEDs are generally formed on sapphire due to the lattice-matching between sapphire and hexagonal GaN.

[0003] Sapphire substrates are generally limited in size (usually a diameter of four inches or less), and therefore, present challenges when scaling upward to produce enough micro-LEDs for mass production of large-screen display devices. While several development efforts of micro-LEDs on more abundant and larger silicon substrates are in progress, such as by selective growth of various structures of both hexagonal (wurtzite) GaN and cubic (zinc-blende) GaN crystal phases on both <1 11 > and <100> Si wafers, attempts so far have been deficient. Additionally, while blue and green micro-LEDs are generally based on GaN material, red micro-LEDs based on GaN perform poorly for a variety of technical reasons beyond the lattice-mismatch between the high indium- containing GaN emitter and the underlying GaN/sapphire or GaN/Si. Red micro- LEDs based on InGaP grown on GaAs substrates have improved performance and are more common. Thus, in order to form a red-green-blue pixel, micro- LEDs from multiple substrates are utilized. The micro-LEDs from the different substrates are diced and positioned (often referred to as a “pick-and-place” operation) onto a suitable host substrate, such as the one that eventually becomes a display device. The“picking-and-placing” of thousands of micro sized LEDs is tedious, time- consuming, expensive, and has its own technical limitations.

[0004] Therefore, there is a need in the art for improved micro-LEDs and micro-LED manufacturing methods.

SUMMARY

[0005] Embodiments of the present disclosure generally relate to micro- LEDs, and methods of forming micro-LEDs. In particular, a method for manufacturing red micro-LEDs on the same substrate, such as a silicon wafer, with pre-existing blue micro-LEDs and/or green micro-LEDs, is disclosed.

[0006] In an embodiment is provided a method of processing a substrate that includes masking GaN-based blue micro-LEDs, GaN-based green micro-LEDs, ora combination thereof disposed on a silicon substrate disposed in a processing system. The method further includes forming a plurality of AllnGaP-based red micro-LEDs on the silicon substrate.

[0007] In another embodiment is provided a device that includes a silicon substrate, a plurality of GaN-based blue micro-LEDs disposed on the silicon substrate, a plurality of GaN-based green micro-LEDs disposed on the silicon substrate, and a plurality of AllnGaP-based red micro-LEDs disposed on the silicon substrate.

[0008] In another embodiment is provided a non-transitory computer readable medium storing instructions that, when executed by a processor of a system, perform operations that include forming a plurality of GaN-based blue micro-LEDs on a silicon substrate, forming a plurality of GaN-based green micro- LEDs on the silicon substrate, masking the plurality of GaN-based blue micro- LEDs and the plurality of GaN-based green micro-LEDs on the silicon substrate, and forming a plurality of AllnGaP-based red micro-LEDs on the silicon substrate.

BRIEF DESCRIPTION OF THE DRAWINGS

[0009] So that the manner in which the above recited features of the present disclosure can be understood in detail, a more particular description of the disclosure, briefly summarized above, may be had by reference to embodiments, some of which are illustrated in the appended drawings. It is to be noted, however, that the appended drawings illustrate only exemplary embodiments and are therefore not to be considered limiting of its scope, may admit to other equally effective embodiments.

[0010] Figure 1 is a flow diagram of a method for forming micro-LEDs on a substrate according to at least one embodiment.

[0011] Figure 2 schematically illustrates a starting substrate structure on which micro-LEDs may be formed according to at least one embodiment.

[0012] Figures 3A-3E schematically illustrate a substrate during operations associated with the flow diagram of Figure 1 according to at least one embodiment.

[0013] Figures 4A-4B schematically illustrate formation of micro-LEDs on a substrate, according to at least one embodiment.

[0014] Figure 5 is an processing system, according to at least one embodiment.

[0015] To facilitate understanding, identical reference numerals have been used, where possible, to designate identical elements that are common to the figures. It is contemplated that elements and features of one embodiment may be beneficially incorporated in other embodiments without further recitation.

DETAILED DESCRIPTION

[0016] Embodiments of the present disclosure generally relate to micro- LEDs, and methods of forming micro-LEDs. In particular, a method for manufacturing AllnGaP-based red micro-LEDs on the same substrate, such as a silicon wafer, with pre-existing GaN-based blue micro-LEDs and/or green micro-LEDs, is disclosed.

[0017] Figure 1 is a flow diagram of a method 100 for forming micro-LEDs on a substrate, according to at least one embodiment. In operation 102, a gallium nitride (GaN) layer is deposited on a <1 1 1 > surface of a silicon substrate. Metal Organic Chemical Vapor Deposition (MOCVD) can be used as the deposition method, but either Hydride Vapor Phase Epitaxy (HVPE) or a lower temperature method, such as molecular beam epitaxy (MBE) may also be used. In contrast to <100> silicon surfaces, the lattices of GaN and the <1 1 1 > silicon surface are sufficiently similar to allow a quality GaN layer to be formed thereon. In one example of operation 102, the deposition of GaN is a blanket deposition on the surface of a <11 1 > silicon wafer, to a thickness having a range of about 500 nanometers to about 10 micrometers, such as about 1 micrometer to about 5 micrometers, or about 2 micrometers to about 4 micrometers. One or more transition layers of AIN and/or AIGaN, are utilized between the silicon surface and the GaN to facilitate device formation. In such examples, the AIN layer(s) may be deposited to a thickness of about 100 nanometers (nm) to about 200 nm. The AIGaN layer(s) may be deposited to a thickness of about 200 nm to about 800 nm.

[0018] As shown in Figure 2, a <100> silicon substrate 200 (e.g., having a <100> exposed upper surface 220) may be utilized. The <100> exposed upper surface 220 may be first processed by, e.g., using a homoepitaxial growth process, to generate <1 1 1 > surfaces 222 prior to GaN deposition in operation 102. The < 1 1 1 > surfaces 222 may be formed from <100> exposed upper surface 220 by the formation of faceted surfaces. The <1 1 1 > surfaces 222 facilitate GaN deposition in a predetermined crystallographic orientation.

[0019] To generate the <1 1 1 > surfaces 222, a mask 253, such as silicon oxide or other oxide, is disposed on the upper surface 220 of the silicon substrate 200. Crystalline silicon 260 is epitaxially formed on exposed areas of the <100> exposed upper surface 220 of the si l i con substrate 200 to a height Hi which exceeds a height h^ of the mask, resulting in the <1 1 1 > surfaces 222 (e.g., faceted surfaces) of the formed crystalline silicon 260 (e.g., a faceted epitaxial silicon feature) being present above the mask 253. The <1 1 1 > surfaces 222 may be, for example, a silicon pyramid, pointed strip, or other similar feature. The <1 1 1 > surfaces 222 are grown by selective epitaxy deposition, for example, at a temperature of about 800 degrees Celsius or more. The <1 1 1 > surfaces 222 have a <1 1 1 > crystallographic orientation which facilitates growth of c-plane wurtzite GaN thereon (e.g., GAN layer or structure 262). In one example of operation 102, GaN is formed selectively on the <1 1 1 > surfaces 222 to a thickness of about 200 nanometers to about 1000 nanometers, such as 400 nanometers to about 800 nanometers. AIN and AIGaN transitional layers may similarly be used prior to the GaN deposition on the <1 1 1 > surfaces 222.

[0020] In another example of operation 102, the crystalline silicon 260 formed as described above has a height Hi . Height Hi is about equal to a height of the GaAs featured formed during subsequent operation 1 12 of Figure 1. In another example of operation 102, the height Hi of the crystalline silicon 260 feature above an upper surface of a mask 253 is about 40 nm to about 400 nm. In another example of operation 102, the epitaxial formation of the <1 1 1 > surfaces 222 may be halted before a peak or apex forms between the <1 1 1 > surfaces 222, to mitigate GaN bridging. Additionally or alternatively, it is contemplated that any formed peaks may be polished off the silicon prior to formation of GaN, for example, by chemical mechanical polishing.

[0021] In another example of operation 102, a GaN l a y e r o r structure 262 in the form of vertical rods are grown on upper surface 220 (which may be a <1 11 > surface) of a silicon substrate 200. The GaN layer or structure 262 is formed by depositing a mask, such as a silicon oxide mask, on the silicon substrate 200, and patterning the mask 253 to expose predetermined areas of the silicon substrate 200 for selective growth of the rods. The rods are then formed in the openings of the mask 253 using a deposition process, such as MOCVD, and aided by a nucleation layer such as AIN having a thickness of about 2 nm to about 50 nm. The rods may have diameters from a few hundred to a few thousand nanometers, such as about 300 nm or about 3000 nm, and heights that are about three to about eight times the diameter of each respective rod. FIG. 3A depicts an example of the resulting GaN rod structures, e.g., blue and green micro-LEDs 350.

[0022] Once the GaN layer or structure 262 is formed at operation 102, the GaN layer or structure 262 is then further processed in operation 104 to develop respective areas for green micro-LEDs and blue micro-LEDs. Such areas may be developed by application of appropriate active emitter layers thereon by, e . g . , forming multi-quantum wells (MQWs) with alternating layers of indium gallium nitride (InGaN) and GaN, each layer being about two to four nanometers thick. The indium concentration of the InGaN layer is selected to provide a desired color output (e.g., green) for the micro-LED. MQWs with higher indium concentrations emit at longer wavelengths. Green color for example requires higher indium concentration than blue color. It is to be noted that the bulk GaN layer below the MQW is doped, either n-type or p-type, and an oppositely doped GaN layer or structure 262 above the MQW is also utilized so as to form a diode. The oppositely doped GaN layer, along with other layer details that may be designed-in to enhance micro-LED performance, such as strain relief layers, electron blocking layers, cladding layers, etc., are also contemplated for inclusions in operation 104 around the MQW formation. Metallic contacts are also applied to the doped layers to finish off the micro- LED, but in this method, are applied after completing all the operations covered in Figure 1 (e.g., after operation 1 14).

[0023] In one example of operation 104, blanket deposition of the MQWs on top of the doped blanket GaN from operation 102, can target one particular indium concentration of the InGaN layers, followed by masking and etching, to create micrometer- sized areas for the micro-LEDs of one color, either blue or green, but not both. Stated otherwise, MQWs for blue and green micro- LEDs are formed separately. It is contemplated, however, in another example of operation 104 that, separate larger areas on the blanket GaN allocated for the other color, may be masked with silicon oxide prior to the above operations for forming the first color (e.g., blue) micro-LED. Wet etching and exposing those allocated (e.g., masked) areas then allows subsequent formation therein of the second color (e.g., green) micro-LEDs. This is done by depositing the higher indium-containing MQW and patterning, in a similar manner as above, while masking the already built micro-LEDs of the first color (e.g., blue).

[0024] Mask and wet etch processes are selected to minimize or avoid damage to the previously-formed micro-LEDs. Existing active emitter layers of the blue micro-LEDs can also be damaged if the typically high temperature (> about 800°C) process of MOCVD or HVPE are used for the active layers of the green micro-LEDs. This can be avoided by using low temperature sources of nitrogen (such as hydrazine, or plasma activation of either N ₂ or NH ₃ ) for deposition below 700 degrees Celsius such as 650 degrees Celsius. In one example, plasma activated N2 or NHs is utilized at pressures below about 10 torr, such as below about 5 torr or below about 3 torr. Hydrazine (in the absence of plasma) may be utilized at a pressure below about 400 torr, such as below about 300 torr. It is contemplated that etching to form the micrometer sized areas could possibly damage the active emitter layers at the edge of the shapes, resulting in lower light output efficiency. Passivation layers to mitigate the possible damage caused by etching can optionally be applied at some later operation after completing all the operations covered in Figure 1.

[0025] In another example of operation 104, both blue and green micro- LEDs may be formed using a blanket deposition. The blanket GaN formed on the substrate in operation 102 is patterned to form first areas of micrometer sized GaN corresponding to locations for forming blue micro-LEDs and second areas of micrometer sized GaN corresponding to locations for forming green micro-LEDs. MQWs at one indium concentration for blue are then formed on the first locations while masking the second locations, and subsequently MQWs at a higher indium concentration for green are formed on the second locations while masking the first locations. Again, low-temperature nitrogen sources may be utilized for the second locations to achieve predetermined thermal budgets. The micrometer- sized areas patterned from blanket layers to form the micro- LEDs in this example or the previous example (e.g., patterned either before or after growth of the MQW and doped GaN) can have any shape such as a round disc, a square, or a rectangle. The sizes of the shapes can range from less than about a micrometer to a few micrometer, such as from about 0.8um to about 8um, however other sizes are also contemplated.

[0026] Alternatively, and in another example of operation 104, it is contemplated that MQWs may be formed on both the first locations and the second locations simultaneously and without masks by taking advantage of pattern dependence (also termed micro-loading) in MOCVD. In such an example, the first locations (e.g., locations for respective micro-LEDs of a first color) are spaced closer to one another than second locations (e.g., locations for respective micro-LEDs of a second color), which results in a lower concentration of indium being incorporated into the MQWs at first locations during formation. The lower concentration of indium results in a blue emission, while a relatively higher concentration results in a green emission. The first locations can be spaced about 0.2 micrometers to about 1 .2 micrometers apart (e.g., about 1.2 micrometer pitch) while the second locations can be spaced about 1 micrometer to about 2 micrometers apart, such as about 1.6 micrometers apart. Such spacing results in an indium concentration of about 15 atomic percent InGaN in the MQW of the blue micro-LEDs, and about 25 atomic percent InGaN in the MQW of the green micro-LEDs.

[0027] In yet another example of operation 104, utilizing the GaN-on-faceted- silicon-structures as described earlier with respect to operation 102, both the green micro-LEDs and blue micro-LEDs respective areas are developed simultaneously during the same deposition of MQWs by taking advantage of the MOCVD micro-loading phenomena. That is, areas created in operation 102 with lower areal density of structures will have at operation 104 active emitter layers with higher indium concentration (longer wavelength emission such as green) than the other areas with higher areal density of structures. Such outcomes at operation 104 are similarly achieved when using the example of GaN rod structures from operation 102.

[0028] Referring back to method 100, once the active layers (including the MQWs and doped GaN) for the green and blue micro-LEDs are formed in a desired pattern, a mask, such as silicon oxide, is positioned over the substrate at operation 106. Figure 3A schematically illustrates a substrate 352 having either blue or green or both micro-LEDs 350 thereon (completed after operation 104 of Figure 1 ). While Figure 3A depicts, as one example, rod GaN structures used for micro-LEDs, e.g. , blue and green micro-LEDs 350, other structures for operation 104 may be used. Figures 3B-3E schematically illustrate the example structures associated with operations 106-114 of Figure 1. In one example of operation 106, the mask 353 illustrated in Figure 3B may partially include the pre-existing mask already deposited at operation 104 over the blue micro-LEDs, or alternatively, the mask existing over the blue micro-LEDs may be removed, and a fresh mask may be positioned over the substrate and then patterned to expose predetermined areas for red micro-LED formation. In another example of operation 106, the mask 353 is formed from silicon oxide. Presence of the mask 353 protects the blue and green micro-LEDs 350 during formation of red micro-LEDs during subsequent processing.

[0029] At operation 108, the mask 353 is patterned corresponding to predetermined regions of formation for red micro-LEDs. The regions may be in the shape of, e.g., a square or a rectangular stripe. A photoresist 354 is applied over the mask 353, as shown in Figure 3B, to facilitate lithographic patterning. The mask 353 is removed by a fluorine-based wet or dry etchant, such as HF, CF ₄ , or NF ₃ , to expose portions of the substrate surface 351 at the bottom of a well or opening 355 (e.g. , a trench opening) within the mask 353, as shown in Figure 3C. Completion of operation 108 leads to the formation of a plurality of openings 355.

[0030] At operation 1 10, the substrate surface 351 is cleaned by exposure to a wet or dry etchant. In one example of operation 1 10, where the blue and green micro-LEDs 350 were earlier formed on the substrate 352 having <1 11 > orientation, the exposed areas of th e su bstrate su rface 351 depicted in Figure 3C already have a desirable crystallographic orientation for gallium arsenide (GaAs) growth. In another example of operation 1 10, where the blue and green micro-LEDs 350 were earlier formed on substrate 352 having <100> orientation, the exposed areas of the substrate surface 351 are first subjected (prior to etching in operation 110 to clean the substrate 352) to an etching process, such as a wet etch using tetramethylammonium hydroxide or dry etch using CI2, to form V-shaped facets 356 into the su bstrate surface 351 as depicted in Figure 3D. The resulting or V-shaped facets 356 have the <1 1 1 > crystallographic orientation that facilitates formation of GaAs material 358 within openings 355 in the mask 353. Cleaning of the su bstrate surface 351 is performed at low temperatures in line with predetermined thermal budgets. The Applied Materials SiCoNi™dry clean is one example useful for application with aspects of this disclosure.

[0031] At operation 1 12, GaAs material 358 is formed on the exposed, etched, and/or cleaned surfaces of the substrate (e.g., substrate surface 351 having < 1 1 1 > orientation or V-shaped facets 356 of the substrate 352). The GaAs material 358 is selectively grown during a chemical vapor deposition process, such as metal organic chemical vapor deposition, using gallium-containing precursor gases, arsenic-containing precursor gases, or a combination thereof, including trimethylgallium, triethylgallium, arsine, and tertiarybutylarsine. The GaAs material 358 is formed vertically upwards within the openings 355 in the mask 353, using the <1 1 1 > crystallographic orientation of the underlying exposed areas of the substrate surface 351 as an epitaxial template. As the GaAs material 358 height exceeds the height of the mask 353 features during the deposition process, it is contemplated that the shape and width of the GaAs material 358 may change. Facet formation may occur as the height of the GaAs material 358 exceeds the height of the mask 353. In one example of operation 1 12, the GaAs material 358 may taper outward at surface 357 such that a width of the GaAs material 358 formed in each respective mask 353 feature has a width greater than a width of the respective opening 355 in the mask 353 at a height above the upper surface of the mask 353. Such a formation may be influenced by the crystallographic tendencies of the GaAs material 358 during formation as facilitated by the deposition conditions, including temperature, flow of growth precursors, and growth rate.

[0032] In another example of operation 1 12, the base portion of the GaAs material 358 (and the openings 355) have a width within a range of about 100 nanometers to about 1000 nanometers. The width of the GaAs material 358 above the mask 353 may be grown to about 200nm to about 2000nm depending on, at least, the predetermined height, the opening 355, and/or the chosen growth conditions. During GaAs material 358 growth, the process temperature may be maintained at less than 650C, such as 600C, to avoid damage to the previously developed GaN blue and/or green micro-LEDs 350.

[0033] Once the GaAs material 358 is deposited to a predetermined height, MQWs 359 are formed at operation 1 14 on the upper surface of the GaAs as shown in Figure 3D. The MQWs 359 for the red micro-LEDs are formed of alternating layers of aluminum indium gallium phosphide (AllnGaP) and indium gallium phosphide (InGaP), which are formed via, e.g., MOCVD at a temperature of about 650 degrees Celsius or less. Each respective opening 355 formed in the patterning of operation 108 includes a GaAs material 358 feature with a MQW 359 formed thereon, resulting in a plurality of red micro-LEDs.

[0034] Subsequently, the mask 353 formed over the blue and green micro- LEDs 350 is removed, and further processing may occur. For example, contacts may be applied to the micro-LEDs. Additionally or alternatively, the substrate may be diced into units which each include red green blue (RGB) micro- LEDs. In the latter example, the masking and deposition operation described above are selected to position a respective red, green, and blue micro-LED in close proximity to one another to facilitate dicing into RGB units, e.g., an RGB pixel. In yet another example, dicing may be omitted, and the substrate having RGB micro-LEDs thereon is bonded directly to a substrate having a predetermined CMOS layout formed thereon. In such an example, the RGB micro-LED layout is selected to correspond to the predetermined CMOS layout. Because dicing and pick-and-place operations are omitted in such an example, throughput is increased and manufacturing costs are reduced.

[0035] Figure 3E illustrates a plan view of an area on the substrate 352, e.g., a silicon substrate. The area 360 includes blue micro-LEDs, the area 361 includes green micro-LEDs, and the area 362 includes red micro-LEDs all formed on a single substrate 352. While the substrate 352 is shown with a plurality of micro-LEDs clustered together for each color (RGB), any number of micro-LEDs for each color may be designed into an area, depending on, e.g., the size of each emitting GaN and GaAs microstructure, the light output or intensity for each color, and/or the area size to be filled. In one example, a designated area includes one round-shaped blue micro-LED structure, one round-shaped green micro-LED structure, and one red micro-LED stripe. In another example, a designated area includes a cluster of a different number of each respective color LED. For example, the designated area could include a cluster of three square-shaped blue micro-LEDs, ten round-shaped green micro-LEDs, and five red micro-LED stripes. Lines delineating different areas (e.g., individual pixel areas) may be defined in patterning according to device design parameters.

[0036] Additionally, while the green micro-LEDs of area 361 are shown in Figure 3E as having similar dimensions as the blue micro-LEDs in area 360, it is contemplated that the dimensions of each micro-LED may be adjusted to form micro-LEDs of different physical dimensions. Similarly, while the red micro- LEDs of area 362 are shown in Figure 3E as having different dimensions than the blue micro-LEDs of area 360 and green micro-LEDs of area 361 , it is contemplated that the dimensions of each may be adjusted to form micro- LEDs of similar physical dimensions. Alternatively, the dimensions of each micro-LED may be adjusted to form micro-LEDs of similar light (e.g., intensity) output.

[0037] Figures 4A-4B schematically illustrate formation of micro-LEDs on a silicon substrate 452, according to another embodiment. In such examples, the blue and green micro-LEDs are formed by masking an upper surface

460 of the silicon substrate 452 having a <001 > orientation, and etching into the silicon substrate 452 to expose surfaces 464 within the etched features 465 of the silicon substrate 452. The surfaces 464 having a <1 1 1 > orientation within the etched features 465 facilitate growth of cubic (zinc-blended) GaN 466 on silicon. Cubic (zinc-blended) GaN 466 is formed in the etched features 465, and subsequently, InGaN/GaN MQWs are formed thereon, as described above. AllnGaP-based red micro-LEDs may then be formed on the substrate 452 as described above, for example, in operations 106-1 14 of Figure 1. A plan view of such a silicon substrate 452 is shown in Figure 4B. The silicon substrate 452 includes areas 461 , 462, and 463 of green, blue, and red (respectively) micro-LEDs. Notably, the spacing between adjacent green micro-LEDs in area

461 is greater than the spacing between adjacent blue micro-LEDs in area 462 to facilitate differences in indium concentration of respective MQWs to adjust emission color.

[0038] Figure 5 is a processing system 530 according to at least one embodiment. The processing system 530 may be one system utilized to practice aspects of the disclosure. However, it is contemplated that other processing systems may additionally or alternatively be utilized.

[0039] The processing system 530 includes a factory interface 532 for receiving cassettes 534. The factory interface 532 is coupled to a buffer station 536 through which substrates are transferred by a factory interface robot 538. Substrates are received from the buffer station 536 by a transfer robot 540 positioned in a transfer chamber 542. The transfer chamber is coupled to one or more processing chambers 500a-500e. It is contemplated that processing chambers 500a-500e may include, for example, one or more cleaning chambers such as SiCoNi® chambers, one or more MOCVD chambers, available from Applied Materials, of Santa Clara, California, and one or more passivation chambers, such as one or more ALD passivation chambers for AI2O3, S1O2, AIN, or one or more CVD passivation chambers for AI2O3, S1O2, AIN, or H2S, available from Applied Materials, of Santa Clara, California. While five processing chambers 500a-500e are shown, it is contemplated that more or less processing chambers may be utilized. Additionally, while the processing chambers 500a-500e are shown in a clustered configuration, it is contemplated that the process chambers may operate in a non-clustered configuration.

[0040] A processor 548 is coupled to the processing system 530 to control aspects thereof. The processor 548 can include a processor that executes program code instructions stored on a tangible, non-transitory computer- readable medium to perform and/or control various operations described herein. The computer-readable medium can include any suitable memory for storing instructions, such as read-only memory (ROM), random access memory (RAM), flash memory, an electrically erasable programmable ROM (EEPROM), a hard disk drive, a compact disc ROM (CD-ROM), a floppy disk, punched cards, magnetic tape, and the like. The processor 548 can control operations of the processing system 530 to facilitate operations of methods described herein.

Embodiments Listing

[0041] The present disclosure provides, among others, the following aspects, each of which may be considered as optionally including any alternate aspects.

[0042] Clause 1 . A method of processing a substrate, comprising: masking GaN-based blue micro-LEDs, GaN-based green micro-LEDs, or a combination thereof disposed on a silicon substrate disposed in a processing system; and forming a plurality of AllnGaP-based red micro-LEDs on the silicon substrate.

[0043] Clause 2. The method of claim 1 , wherein the forming a plurality of AllnGaP-based red micro-LEDs on the silicon substrate comprises selectively depositing GaAs structures in patterned areas at temperatures less than 650°C.

[0044] Clause 3. The method of Clause 1 or Clause 2, wherein the GaN- based blue micro-LEDs, the GaN-based green micro-LEDs, or combination thereof are GaN structures selectively deposited prior to masking GaN-based blue micro-LEDs, GaN-based green micro-LEDs, or a combination thereof.

[0045] Clause 4. The method of Clause 3, wherein the GaN-based blue micro-LEDs, the GaN-based green micro-LEDs, or combination thereof are formed on <1 1 1 > facetted epitaxially grown silicon features.

[0046] Clause 5. The method of Clause 3 or Clause 4, wherein the GaN- based blue micro-LEDs, the GaN-based green micro-LEDs, or combination thereof are formed on <1 1 1 > surfaces of features etched into the silicon substrate.

[0047] Clause 6. The method of any one of Clauses 3-5, wherein the GaN- based blue micro-LEDs, the GaN-based green micro-LEDs, or combination thereof comprise vertical rods.

[0048] Clause 7. The method of any one of Clauses 1-6, wherein the GaN- based blue micro-LEDs, the GaN-based green micro-LEDs, or combination thereof are formed from blanket layers.

[0049] Clause 8. The method of any one of Clauses 1 -7, wherein the masking GaN-based blue micro-LEDs, the GaN-based green micro-LEDs, or a combination thereof comprises masking both of the GaN-based blue micro-LEDs and the GaN-based green micro-LEDs.

[0050] Clause 9. The method of The method of any one of Clauses 1-8, wherein the processing system includes a transfer chamber coupled to a cleaning chamber, a MOCVD chamber, and a passivation chamber.

[0051] Clause 10. A device comprising: a silicon substrate; a plurality of GaN- based blue micro-LEDs disposed on the silicon substrate; a plurality of GaN- based green micro-LEDs disposed on the silicon substrate; and a plurality of AllnGaP-based red micro-LEDs disposed on the silicon substrate.

[0052] Clause 1 1. A non-transitory computer readable medium storing instructions that, when executed by a processor of a system, perform operations comprising: forming a plurality of GaN-based blue micro-LEDs on a silicon substrate disposed in a processing system; forming a plurality of GaN-based green micro-LEDs on the silicon substrate; masking the plurality of GaN-based blue micro-LEDs, the plurality of GaN-based green micro-LEDs, or a combination thereof on the silicon substrate; and forming a plurality of AllnGaP-based red micro-LEDs on the silicon substrate.

[0053] Clause 12. The non-transitory computer readable medium of Clause 1 1 , wherein the forming a plurality of AllnGaP-based red micro-LEDs on the silicon substrate comprises selectively depositing GaAs structures in patterned areas at temperatures less than 650°C.

[0054] Clause 13. The non-transitory computer readable medium of Clause 1 1 or Clause 12, wherein the plurality of GaN-based blue micro-LEDs, the plurality of GaN-based green micro-LEDs, or a combination thereof are GaN structures selectively deposited prior to the masking.

[0055] Clause 14. The non-transitory computer readable medium of Clause 13, wherein the plurality of GaN-based blue micro-LEDs, the plurality of GaN- based green micro-LEDs, or a combination thereof are formed on <1 1 1 > surfaces of features etched into the silicon substrate.

[0056] Clause 15. The non-transitory computer readable medium of Clause 13 or Clause 14, wherein the plurality of GaN-based blue micro-LEDs, the plurality of GaN-based green micro-LEDs, or a combination thereof are formed on <1 1 1 > facetted epitaxially grown silicon features.

[0057] Clause 16. The non-transitory computer readable medium of any one of Clauses 13-15, wherein the plurality of GaN-based blue micro-LEDs, the plurality of GaN-based green micro-LEDs, or a combination thereof comprise vertical rods. [0058] Clause 17. The non-transitory computer readable medium of any one of Clauses 1 1-16, wherein the plurality of GaN-based blue micro-LEDs, the plurality of GaN-based green micro-LEDs, or a combination thereof are formed from blanket layers.

[0059] Clause 18. The non-transitory computer readable medium of any one of Clauses 1 1-17, wherein the masking comprises masking both of the GaN- based blue micro-LEDs and the GaN-based green micro-LEDs.

[0060] Clause 19. The non-transitory computer readable medium of any one of Clauses 1 1-18, wherein the processing system includes a transfer chamber coupled to a cleaning chamber, a MOCVD chamber, and a passivation chamber.

[0061] Clause 20. The non-transitory computer readable medium of any one of Clauses 1 1-19, wherein the forming a plurality of AllnGaP-based red micro- LEDs on the silicon substrate comprises selectively depositing GaAs structures in patterned areas at temperatures less than 600°C.

[0062] While aspects herein are described with deposition techniques such as MOCVD, other deposition techniques, such as molecular beam epitaxy (MBE), are also contemplated.

[0063] The present disclosure include methods for forming red, blue, and green micro-LEDs on a single substrate. Formation of red, blue, and green micro-LEDs on silicon substrates can , at least, provide increased productivity, due to a reduced number of operations, the omission of pick-and- place processes, and the increased size of silicon substrates compared to conventionally-used sapphire substrates.

[0064] While the foregoing is directed to embodiments of the present disclosure, other and further embodiments of the disclosure may be devised without departing from the basic scope thereof, and the scope thereof is determined by the claims that follow.