Light absorbing barrier for LED fabrication process

Abstract

To provide improved semiconductor structures and semiconductor processing methods that can be used to produce high-quality materials and structures for LED display devices.SOLUTION: An exemplary processing method includes forming a group of LED structures on a substrate layer to form a patterned LED substrate. A light absorption barrier may be deposited on the patterned LED substrate. The method may further include exposing the patterned LED substrate to light. The light may be absorbed by surfaces of the LED structures that are in contact with the substrate layer and the light absorption barrier. The method may still further include separating the LED structures from the substrate layer. The bonding between the LED structures and the substrate layer may be weakened by the absorption of the light by the surfaces of the LED structures in contact with the substrate layer.SELECTED DRAWING: Figure 6

Description

[Technical Field]

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit of and priority to U.S. Non-Provisional Application No. 17 / 350,523, entitled "LIGHT ABSORBING BARRIER FOR LED FABRICATION PROCESSES," filed June 17, 2021, the entire contents of which are incorporated herein by reference.

[0002]

[0002] The present technology relates to semiconductor processes and semiconductor products. More particularly, the present technology relates to the fabrication of semiconductor structures and formed devices. [Background technology]

[0003] Light-emitting diode (LED) display devices, made up of pixels millions of microns in size, are made possible by manufacturing processes that create intricately patterned layers of material on a substrate surface. Fabricating patterned materials on a substrate requires controlled methods for material deposition and removal. However, with new device designs, it can be challenging to fabricate high-quality material layers with highly accurate dimensions.

[0004]

[0004] Therefore, there is a need for improved systems and methods that can be used to manufacture high quality materials and structures for LED display devices. These and other needs are addressed by the present technology. Summary of the Invention

[0005]

[0005] The present technology includes an exemplary semiconductor processing method that includes forming a group of LED structures on a substrate layer to form a patterned LED substrate. A light-absorbing barrier can be deposited on the patterned LED substrate. The method can further include exposing the patterned LED substrate to light. The light can be absorbed by surfaces of the LED structures in contact with the substrate layer and the light-absorbing barrier. The method can still further include separating the LED structures from the substrate layer. The bond between the LED structures and the substrate layer can be weakened by absorption of light by surfaces of the LED structures in contact with the substrate layer.

[0006] In additional embodiments, the group of LED structures may include a gallium-nitrogen containing material that generates nitrogen gas (N2) upon exposure to light at a surface of the LED structures in contact with the substrate layer. In further embodiments, the substrate may include sapphire (i.e., Al2O3). In still further embodiments, the light to which the LED substrate is exposed may be characterized by a peak intensity wavelength of about 300 nm or less. In still further embodiments, the light-absorbing barrier may include one or more layers of a dielectric material. In still further embodiments, the dielectric material may be characterized by a room temperature bandgap of about 4.3 eV or greater. In still further embodiments, the light-absorbing barrier is operable to transmit light emitted from the LED structures. In still further embodiments, the semiconductor further includes a backplane substrate coupled to the group of LED structures on the opposite side from the substrate layer. In still further embodiments, the light-absorbing barrier prevents light to which the patterned LED substrate is exposed from reaching the backplane substrate.

[0007] The present technology also includes additional semiconductor processing methods that may include forming an LED structure on a substrate layer. The method may further include forming a first portion of a light-absorbing barrier on the LED structure and the substrate layer, and forming at least one additional portion of a light-absorbing barrier on the first portion of the light-absorbing barrier. The method may still further include exposing the substrate layer to ultraviolet light, which is absorbed by the exposed portion of the light-absorbing barrier. After exposure, the LED structure can be separated from the substrate layer.

[0008] In additional embodiments, the first portion of the light-absorbing barrier may comprise a first dielectric material selected from the group including silicon oxide, silicon nitride, titanium oxide, titanium nitride, germanium oxide, tantalum oxide, tantalum nitride, manganese oxide, niobium oxide, antimony oxide, indium tin oxide, lanthanum oxide, yttrium oxide, zirconium oxide, aluminum oxide, aluminum nitride, hafnium oxide, and magnesium fluoride. In further embodiments, at least one additional portion of the light-absorbing barrier includes a second portion comprising a second dielectric material different from the first dielectric material. In still further embodiments, the ultraviolet light is characterized by a wavelength of about 300 nm or less. In still further embodiments, the method further includes forming a reflective layer on the light-absorbing barrier. In further embodiments, the light-absorbing barrier increases the reflectivity of the reflective layer for LED light emitted by the LED structure.

[0009] The present technology further includes a semiconductor structure that may include a plurality of LED structures, a backplane layer, and a light barrier region positioned between the LED structures and the backplane layer, wherein the light barrier region may be operable to absorb light having a wavelength of about 300 nm or less and transmit light having a wavelength of about 350 nm or more.

[0010] In additional embodiments, each of the plurality of LED structures may include an n-type doped gallium-nitrogen-containing region, a multiple quantum well layer in contact with the n-type doped gallium-nitrogen-containing region, and a p-type doped gallium-nitrogen-containing region in contact with the multiple quantum well layer. In further embodiments, the backplane layer may include an ultraviolet-absorbing polymer. In yet further embodiments, the light barrier region may include two or more layers of a dielectric material selected from the group including silicon oxide, silicon nitride, titanium oxide, titanium nitride, germanium oxide, tantalum oxide, tantalum nitride, manganese oxide, and niobium oxide, wherein the first layer of dielectric material is different from the second layer of dielectric material in contact with the first layer of dielectric material. In still further embodiments, the semiconductor structure may further include a reflective layer in contact with the light barrier region. In still further embodiments, the semiconductor structure may further include a light conversion region in contact with at least one of the LED structures, the light conversion region operable to absorb light generated by the LED structure and emit converted light characterized by a longer peak wavelength intensity.

[0011] The above techniques may offer numerous advantages over conventional semiconductor processing methods and structures. For example, embodiments of the processing methods may reduce the amount of short-wavelength light absorbed by a backplane substrate during illumination of a patterned LED substrate to separate substrate layers bonded to opposite sides of the backplane substrate. This reduces damage to the control circuitry of the backplane substrate from the short-wavelength ionizing light used to separate the substrate layers. In further embodiments, the processing methods form a light-absorbing barrier that blocks harmful short-wavelength radiation from reaching the backplane substrate and increases the extraction of light generated by the LED structure in useful directions. These and other embodiments, along with their many advantages and features, are described in more detail in conjunction with the following description and accompanying figures.

[0012] A further understanding of the nature and advantages of the disclosed technology may be realized by reference to the remaining portions of the specification and the drawings. [Brief explanation of the drawings]

[0013] [Figure 1] FIG. 1 illustrates a top plan view of one embodiment of an exemplary processing system in accordance with some embodiments of the present technique. [Figure 2A] 1A-1D illustrate exemplary steps in a method for forming an LED semiconductor device in accordance with some embodiments of the present technology. [Figure 2B] 10A-10C illustrate exemplary steps in another method for forming an LED semiconductor device, in accordance with some embodiments of the present technology. [Figure 3A] 1 is a cross-sectional view illustrating a semiconductor LED structure according to an embodiment of the present technology. [Figure 3B] 1 is a cross-sectional view illustrating a semiconductor LED structure according to an embodiment of the present technology. [Figure 4] 10A-10C are additional cross-sectional views illustrating semiconductor LED structures with substrate separation according to embodiments of the present technology. [Figure 5] 1 is a cross-sectional view of another semiconductor LED structure with substrate separation according to an embodiment of the present technology. [Figure 6] 10A and 10B are cross-sectional views illustrating semiconductor LED structures according to additional embodiments of the present technology. DETAILED DESCRIPTION OF THE INVENTION

[0014]

[0020] Some of the figures are included as schematic diagrams. It should be understood that the figures are for illustrative purposes and should not be considered to scale unless the scale is explicitly stated. Furthermore, the schematic diagrams are provided to aid in understanding and may not include all aspects or information compared to realistic representations. The figures may include exaggerated material for illustrative purposes.

[0015]

[0021] In the accompanying figures, similar components and / or features may be labeled with the same reference label. Furthermore, various components of the same type may be distinguished by following the reference label with a letter that distinguishes between the similar components. When only a first reference label is used herein, the description is applicable to any one of the similar components having the same first reference label, regardless of the letter.

[0016]

[0022] An LED display typically includes an LED structure that illuminates the display's pixels and a backplane substrate that contains control circuitry that addresses and activates the pixels. In many manufacturing processes, the LED structure is formed on an LED substrate and the control circuitry is formed on a separate backplane substrate. The two substrates are then bonded together to form the LED display structure. Often, the LED substrate is removed from the display structure and replaced with additional structures that convert the color and modify the light pattern emitted by the underlying LED structure.

[0017]

[0023] One technique for removing an LED substrate from a display structure is laser lift-off, which uses high-energy light to photodissociate the bond between the LED substrate and the underlying LED structure, including layers of LED material. For example, ultraviolet light from an excimer or solid-state laser can be used to photodissociate the bond between a sapphire LED substrate and the bonded gallium nitride-containing base region of an LED structure formed on the sapphire substrate. The ultraviolet light passes through the sapphire, photodissociating the gallium nitride into liquid gallium metal and nitrogen (N2) gas. As more gallium nitride photodissociates, the bond between the sapphire substrate and the LED structure weakens, and increasing nitrogen gas pressure forces the layers apart until they are completely separated.

[0018]

[0024] While laser lift-off is a clean and efficient technique for separating the LED substrate from the LED structures, it has a significant drawback: high-energy ultraviolet light can leak through the gaps between adjacent LED structures and damage the underlying backplane substrate. UV damage often causes the backplane substrate's control circuitry to malfunction, potentially resulting in one or more pixels in the LED display dying or firing out of sync. Furthermore, UV light can damage the polymer formed between the LED structures that helps bond the structures to the temporary carrier substrate that eventually replaces the backplane substrate. The light-damaged polymer can create permanent contaminated areas between the LED structures, potentially discoloring or distorting the image displayed by the device.

[0019]

[0025]

[0003] Embodiments of the present technology address problems caused by leaking ultraviolet light that damages the backplane substrate and other areas on an LED display during a laser lift-off process for removing an LED substrate from LED structures formed on the substrate. In embodiments, the present technology includes a process for forming a light-absorbing barrier on the LED structures and substrate layer of a patterned LED substrate. The light-absorbing barrier is operable to absorb high-energy light from the laser lift-off process and prevent it from reaching exposed areas of the backplane substrate between adjacent LED structures.

[0020]

[0026] Additional embodiments of the present technology include processes for forming a light-absorbing barrier between an LED structure and a reflective layer that reflects light emitted by the LED structure in directions useful to the LED display. In embodiments, the light-absorbing barrier can absorb the high-energy ultraviolet light generated during the laser lift-off process while transmitting the low-energy ultraviolet and visible light generated by the LED structure. In further embodiments, the light-absorbing barrier can increase the reflectivity of the reflective layer to light generated by the LED structure.

[0021]

[0027] 1 is a top plan view illustrating one embodiment of a deposition, etch, bake, and cure chamber processing system 100 in accordance with some embodiments of the present technology. In the figure, a pair of front-opening unified pods 102 deliver substrates of various sizes that are placed in a low-pressure holding area 106 before being received by a robotic arm 104 and placed in one of the substrate processing chambers 108a-f arranged in tandem sections 109a-c. A second robotic arm 110 can be used to shuttle substrate wafers from the holding area 106 to the substrate processing chambers 108a-f. Each substrate processing chamber 108a-f can be equipped to perform numerous substrate processing steps, including physical vapor deposition processes described herein, as well as dry etching processes, cyclical layer deposition processes, atomic layer deposition processes, chemical vapor deposition processes including metalorganic chemical vapor deposition processes, etching processes, pre-cleaning processes, planarization processes including chemical mechanical polishing processes, annealing processes, plasma treatment processes, degassing processes, alignment processes, and other semiconductor manufacturing processes.

[0022]

[0028] The substrate processing chambers 108a-f may include one or more system components for depositing, annealing, curing, and / or etching a material film on a substrate or wafer. In one configuration, two pairs of processing chambers, e.g., 108c-d and 108e-f, can be used to deposit material on a substrate, and a third pair of processing chambers, e.g., 108a-b, can be used to planarize, anneal, cure, or otherwise process the deposited film. In another configuration, all three pairs of chambers, e.g., 108a-f, can be configured to both deposit and cure a film on a substrate. One or more of the described processes can be performed in additional chambers separate from the fabrication system shown in different embodiments. It will be understood that additional configurations of deposition, etch, anneal, and cure chambers for material films are contemplated by system 100. Furthermore, any number of other processing systems can be used with the present technology, which can incorporate chambers for performing any of the specific steps. In some embodiments, a chamber system that can provide access to multiple processing chambers while maintaining a vacuum environment in various sections, such as the holding and transfer areas described, can enable steps to be performed in multiple chambers while maintaining a particular vacuum environment between separate processes.

[0023]

[0029] System 100, or more specifically, a chamber incorporated into system 100 or another processing system, can be used to fabricate semiconductor LED structures in accordance with some embodiments of the present technology. FIGS. 2A and 2B illustrate exemplary steps in methods 200 and 250 for forming LED semiconductor structures in accordance with some embodiments of the present technology. Methods 200 and 250 can be performed in one or more processing chambers, such as, for example, a chamber incorporated into system 100. Methods 200 and 250 may or may not include one or more steps prior to the start of the method, including front-end processing, deposition, etching, polishing, cleaning, or any other steps that may be performed before the described steps. The method may also include numerous optional steps that may or may not be specifically related to some embodiments of the method in accordance with the present technology.

[0024]

[0030] FIG. 2A illustrates exemplary steps in a method 200 of forming an LED semiconductor structure in accordance with an embodiment of the present technology. Method 200 includes providing an LED substrate in step 205. As described below, in embodiments, the LED substrate may be made of sapphire or another LED substrate material. In step 210, a transparent conductive layer may be deposited on the LED substrate material. In embodiments, the transparent conductive layer may include indium tin oxide or another transparent conductive material. In step 215, layers of materials that will form the LED structure may be deposited and etched to form the LED structure. As described below, in embodiments, these layers of materials may include, among other layers, an n-type doped GaN layer, layers for a multiple quantum well (MQW) structure, and a p-type doped GaN layer. In further embodiments, layers of materials for the LED structure may be blanket deposited on the transparent conductive layer and then pattern-etched to form the LED structure.

[0025]

[0031] In embodiments of method 200, the method includes forming a light barrier region on the LED structure at step 220. As described below, embodiments of the light barrier region include one or more layers of dielectric material that block the passage of high-energy, short-wavelength light while allowing the passage of light generated by the LED structure. Also, in embodiments of method 200, contact openings may be formed in the light barrier region at step 225. Conductive contact pads for the n-type and p-type doped portions of the LED structure may be formed through the contact openings at step 230. The LED substrate is then polished at step 235 and cut into LED substrate chips at step 240.

[0026]

[0032] In embodiments, the LED substrate chip can be bonded directly to a backplane substrate, with the LED substrate layer removed from the bonded structure by a laser lift-off technique. In additional embodiments, the LED substrate chip can first be bonded to a polymer layer. The combined LED substrate chip and polymer layer can then be bonded to another substrate layer, such as a backplane substrate layer. In yet additional embodiments, the LED substrate can be removed from the LED substrate chip by a laser lift-off technique before or after bonding the combined LED substrate chip and polymer layer to another substrate layer. The light barrier region of the LED substrate chip prevents the high-energy, short-wavelength light used in the laser lift-off technique from damaging the polymer material of the polymer layer. In embodiments in which the combined LED substrate chip and polymer layer are bonded to another substrate layer before the laser lift-off technique, the light barrier region prevents the laser lift-off light from damaging both the polymer layer and the additional substrate layer.

[0027]

[0033] Figure 2B illustrates exemplary steps in another method 250 of forming an LED semiconductor structure according to some embodiments of the present technology. Method 250 describes steps for forming the semiconductor structure embodiments shown in simplified schematic form in Figures 3A, 3B, 4, 5, and 6, which illustrations will be described in conjunction with the steps of method 250. It should be understood that Figures 3A, 3B, 4, 5, and 6 show only partial schematic views with limited detail, and that in some embodiments, a substrate may include any number of semiconductor sections having the aspects illustrated in the figures, as well as alternative structural aspects that can still benefit from any aspect of the present technology.

[0028]

[0034] In an embodiment, method 250 includes forming an LED structure on a substrate in step 255. An embodiment of the process includes providing a substrate, such as substrates 312, 412, and 512 shown in FIGS. 3A, 3B, 4, and 5. In an embodiment, substrates 312, 412, and 512 may be formed from a material characterized by a room-temperature (-23°C) bandgap between the valence band and the conduction band that allows transmission of ultraviolet light used in the laser lift-off process. In additional embodiments, the substrate material may be characterized by a room-temperature bandgap of about 5 electron volts (eV) or greater, about 6 eV or greater, about 7 eV or greater, about 8 eV or greater, about 9 eV or greater, about 10 eV or greater, or greater. In further embodiments, the substrate material may be sapphire (bandgap = 9.9 eV) or quartz (bandgap - 10 eV). In still further embodiments, the substrate material may be flat or patterned sapphire. In embodiments, the planar sapphire substrate may be characterized by a smooth interface between the substrate and the LED structure formed thereon. In additional embodiments, the patterned sapphire substrate may include one or more patterned structures, such as dome structures, pyramid structures, or column structures, among other patterned structures. In still additional embodiments, the individual units of the patterned structures may be characterized by a longest dimension of about 3000 nm or less, about 2000 nm or less, about 1000 nm or less, about 500 nm or less, about 250 nm or less, or less. In yet other embodiments, the substrate 312, 412, 512 may be characterized by a thickness of about 200 μm or more, about 500 μm or more, about 750 μm or more, about 1000 μm or more, about 1250 μm or more, about 1500 μm or more, or more.

[0029]

[0035] Embodiments of step 255 may also include forming an LED structure on substrate 312, 412, and 512. These LED formation steps may include forming an n-type doped gallium-nitrogen-containing layer on the substrate. For example, FIGS. 3A and 3B illustrate an n-type doped gallium nitride (GaN) layer 308 formed on substrate 312. In additional embodiments, n-type doped layer 308 may include one or more of gallium nitride (GaN), aluminum indium gallium nitride (AlInGaN), indium gallium nitride (InGaN), and aluminum gallium nitride (AlGaN). In further embodiments, n-type doped layer 308 may include gallium-free indium-nitride materials such as indium nitride (InN) and aluminum indium nitride (AlInN), among other gallium-free nitride materials.

[0030]

[0036] Embodiments of forming an LED structure in step 255 may further include forming layers of a multiple quantum well (MQW) structure on an n-doped layer of the LED structure. For example, FIGS. 3A and 3B illustrate an MQW structure 310 formed on an n-doped layer 308. In embodiments, the MQW structure 310 may include one or more quantum well layers formed on the n-doped layer 308. In additional embodiments, the MQW structure 310 may include one or more layers of InGaN-containing material, which may be collectively referred to as an InGaN / GaN superlattice (SL), deposited on a gallium-nitrogen-containing n-doped region 308. In embodiments, the number of quantum well layers in the MQW structure 310 may be about 2 or more quantum well layers, about 3 or more quantum well layers, about 4 or more quantum well layers, about 5 or more quantum well layers, about 6 or more quantum well layers, about 7 or more quantum well layers, about 8 or more quantum well layers, about 9 or more quantum well layers, about 10 or more quantum well layers, or more. In other further embodiments, the quantum well layer may include indium, gallium, and nitrogen (e.g., InGaN). In still further embodiments, the quantum well layer may be characterized by a thickness of about 1 nm or more, about 2 nm or more, about 3 nm or more, about 4 nm or more, about 5 nm or more, or more.

[0031]

[0037] Embodiments of forming an LED structure in step 255 may still further include forming a p-type doped layer on a multiple quantum well (MQW) structure. For example, FIGS. 3A and 3B illustrate a p-type doped layer 306 formed on an MQW structure 310. In embodiments, the p-type doped layer 306 may be made of one or more of gallium nitride (GaN), aluminum indium gallium nitride (AlInGaN), indium gallium nitride (InGaN), and aluminum gallium nitride (AlGaN). In further embodiments, the p-type doped layer 306 may include gallium-free indium-nitride materials such as indium nitride (InN) and aluminum indium nitride (AlInN), among other gallium-free nitride materials.

[0032]

[0038] In embodiments, LED structures including n-type doped layers, MQW structures, and p-type doped layers can be formed by first depositing a blanket layer of material on the substrates 312, 412, and 512, and then patterning and etching the individual structures on the substrate. In additional embodiments, the individual structures can be grown directly on the substrates 312, 412, and 512. In further embodiments, gallium-nitrogen-containing materials can be deposited on portions of the substrates 312, 412, and 512 exposed by a patterned layer (not shown) using metalorganic chemical vapor deposition (MOCVD) of the gallium-nitrogen-containing material. In further embodiments, MOCVD can include delivering a deposition precursor to the exposed portions of the substrates 312, 412, and 512. In embodiments, the deposition precursor can include one or more alkylgallium compounds, such as trimethylgallium and triethylgallium, among other gallium compounds. In additional embodiments, the deposition precursor can also include ammonia (NH) to provide the nitrogen component of the gallium-nitrogen-containing material. In yet additional embodiments, molecular beam epitaxy (MBE) can be used to form components of the LED structure.

[0033]

[0039] Embodiments of forming an LED structure in step 255 may further include forming contact pads on the n-doped and p-doped layers of the LED structure. For example, Figures 3A and 3B show an n-pad 302 contacting an n-doped layer 308 and a p-pad 304 contacting a p-doped layer 306. The contact pads may be made of conductive materials such as copper, aluminum, tungsten, chromium, nickel, silver, gold, platinum, palladium, titanium, tin, and / or indium, among other conductive materials.

[0034]

[0040] Method 250 may further include forming a light-absorbing barrier on the LED structures and the LED substrate at step 260. In embodiments, portions of the light-absorbing barrier may be formed directly between the LED structures on substrate 312, 412, and 512. For example, FIGS. 4 and 5 illustrate light-absorbing barriers 414 and 514 formed between LED structures 405a and 405b and between LED structures 505a and 505b, respectively. The light-absorbing barrier prevents high-energy UV radiation from penetrating the light-absorbing barrier between the LED structures and damaging underlying materials, such as the backplane substrate and polymer layers. For example, in the embodiment shown in FIG. 4, light-absorbing barrier 414 prevents high-energy UV radiation transmitted through substrate 412 from penetrating the region between LED structures 405a and 405b and reaching the underlying backplane layers 418 and 420. In the embodiment shown in FIG. 5, light-absorbing barrier 514 prevents high-energy ultraviolet light transmitted through substrate 512 from penetrating the region between LED structure 505a and LED structure 505b and reaching polymer material 522.

[0035]

[0041] In embodiments, the light-absorbing barriers 314, 414, 514, and 614 shown in Figures 3B, 4, 5, and 6 can include one or more layers of material that can absorb high-energy UV radiation used in laser lift-off processes and transmit longer wavelengths of light, including those emitted by the LED structure. In additional embodiments, the light-absorbing barriers can absorb high-energy UV radiation and wavelengths of about 350 nm or less, about 340 nm or less, about 330 nm or less, about 320 nm or less, about 310 nm or less, about 300 nm or less, about 290 nm or less, about 280 nm or less, about 270 nm or less, about 260 nm or less, about 250 nm or less, or less. In further embodiments, the light-absorbing barriers can absorb about 50% or more, about 60% or more, about 70% or more, about 80% or more, about 90% or more, about 92.5% or more, about 95% or more, about 99% or more of the high-energy UV radiation that reaches the barrier. In other further embodiments, the light-absorbing barrier may transmit low energy ultraviolet and visible light of about 350 nm or greater, about 360 nm or greater, about 370 nm or greater, about 380 nm or greater, about 390 nm or greater, about 400 nm or greater, or greater. In further embodiments, the light-absorbing barrier may transmit longer wavelength light that reaches the barrier at a transmittance level of about 50% or greater, about 60% or greater, about 70% or greater, about 80% or greater, about 90% or greater, about 92.5% or greater, about 95% or greater, about 99% or greater, or greater.

[0036]

[0042] In additional embodiments, the light-absorbing barrier may be made of one or more layers of a dielectric material. In further embodiments, the dielectric material may be selected from silicon oxide, silicon nitride, titanium oxide, titanium nitride, germanium oxide, tantalum oxide, tantalum nitride, manganese oxide, niobium oxide, antimony oxide, indium tin oxide, lanthanum oxide, yttrium oxide, zirconium oxide, aluminum oxide, aluminum nitride, hafnium oxide, and magnesium fluoride, among other dielectric materials. In yet further embodiments, the light-absorbing barrier may be a multilayer barrier including two or more layers, three or more layers, four or more layers, five or more layers, six or more layers, seven or more layers, eight or more layers, nine or more layers, ten or more layers, or more. In still additional embodiments, the light absorbing barrier may have a thickness of about 25 nm or more, about 50 nm or more, about 75 nm or more, about 100 nm or more, about 125 nm or more, about 150 nm or more, about 175 nm or more, about 225 nm or more, about 250 nm or more, about 275 nm or more, about 300 nm or more, about 325 nm or more, about 350 nm or more, about 375 nm or more, or about 400 nm or more.

[0037]

[0043] Method 250 may optionally include forming a reflective layer on the light-absorbing barrier at step 265. In embodiments, the reflective layer may be operable to reflect light emitted from the LED structure and transmitted through the light-absorbing barrier in a direction useful for displaying an image on the LED display. FIG. 6 illustrates an embodiment of a reflective layer 615 formed on the light-absorbing barrier 614 that is operable to reflect light emitted by the MQW structure of the LED structure 605 in a direction toward a light-conversion structure 625 where the light emitted by the LED structure is converted to visible light for the LED display. In additional embodiments, the reflective layer 615 may be made of one or more reflective metals, such as aluminum, silver, or copper. In still additional embodiments, the reflective layer may have a thickness of about 50 nm or more, about 100 nm or more, about 150 nm or more, about 200 nm or more, about 250 nm or more, about 300 nm or more, or more. In another further embodiment, the reflective layer 615 may be formed on the light absorbing barrier 614 by sputtering, physical vapor deposition, chemical vapor deposition, and electroplating, among other formation techniques.

[0038]

[0044] In additional embodiments, the light-absorbing barrier 614 in contact with the reflective layer 615 can increase the reflectivity of the reflective layer at the wavelengths of light emitted by the LED structure 605. For example, the reflective layer 615 can be characterized by a reflectivity without the light-absorbing barrier 614 of about 92% or less, about 91% or less, about 90% or less, about 89% or less, about 88% or less, about 87% or less, about 86% or less, about 85% or less, or less. Meanwhile, the reflective layer 615 can be characterized by a reflectivity with the light-absorbing barrier 614 of about 92% or more, about 93% or more, about 94% or more, about 95% or more, about 96% or more, about 97% or more, about 98% or more, about 99% or more, or more. In still further examples, the increase in reflectivity of the reflective layer in the presence of the light-absorbing barrier can be about 2.5% or more, about 5% or more, about 7.5% or more, about 10% or more, or more.

[0039]

[0045] Method 250 may also further include separating the LED substrate from the LED structure in step 270. In embodiments, this separation step may include a laser lift-off process using high-energy ultraviolet light to photodissociate the bond between the LED substrate and the surface of the LED structure in contact with the substrate. In the embodiment shown in FIGS. 4 and 5, the high-energy ultraviolet light photodissociates gallium nitride (GaN) in the n-doped base layers of LED structures 405a-b and 505a-b, which are in contact with LED substrate 412 and 512. Photodissociation of the GaN material produces liquid gallium (Ga) and nitrogen gas 403, 503. The loss of solid GaN material and the increasing pressure buildup of nitrogen gas cause separation between LED structures 405a-b and 505a-b and substrate layer 412 and 512. In some embodiments, little or no force is required to separate the LED structure from the substrate layer.

[0040]

[0046] As described above, in embodiments, a portion of the light-absorbing barrier 414, 514 is formed between the LED structures 405a and 405b, 505a and 505b on the substrate 412, 512. In embodiments, the light-absorbing barrier is formed over the LED structures, with no portion of the light-absorbing barrier formed at the interface between the base region of the LED structures and the substrate on which the LED structures are formed. This allows high-energy UV light transmitted through the substrate layers to be absorbed by the light-absorbing barrier formed directly on the material of the base region of the LED structures and on the substrate between the LED structures. Absorption of high-energy UV light by the light-absorbing barriers 414, 514, and 614 prevents the light from damaging underlying materials and components of the LED semiconductor structures 400, 500, and 600 shown in FIGS. 4, 5, and 6. In embodiments, these include the solder bumps 416, 616, backplane contacts 418, 618, and backplane substrates 420, 620 shown in FIGS. 4 and 6. These also include the polymer material 522 and temporary substrate 524 shown in FIG.

[0041]

[0047] In embodiments, the high energy ultraviolet light used in the separation process 270 may be characterized by a peak intensity photon energy of about 4 eV or greater, about 4.1 eV or greater, about 4.2 eV or greater, about 4.3 eV or greater, about 4.4 eV or greater, about 4.5 eV or greater, about 4.6 eV or greater, about 4.7 eV or greater, about 4.8 eV or greater, about 4.9 eV or greater, about 5 eV or greater, about 5.1 eV or greater, about 5.2 eV or greater, about 5.3 eV or greater, about 5.4 eV or greater, about 5.5 eV or greater, or greater. In additional embodiments, the high-energy ultraviolet radiation may be characterized by a peak intensity wavelength of about 350 nm or less, about 340 nm or less, about 330 nm or less, about 320 nm or less, about 310 nm or less, about 300 nm or less, about 290 nm or less, about 280 nm or less, about 270 nm or less, about 260 nm or less, about 250 nm or less, about 240 nm or less, about 230 nm or less, about 220 nm or less, about 210 nm or less, about 200 nm or less, or less. In still further embodiments, the high-energy ultraviolet radiation may be produced by an excimer laser characterized by a peak emission wavelength of 157 nm (F2), 193 nm (ArF), 248 nm (KrF), 282 nm (CeBr), 308 nm (XeCl), or 351 nm (XeF), among other peak emission wavelengths. In additional embodiments, the high energy ultraviolet light is emitted from a solid-state laser (e.g., a frequency-doubled Nd laser) characterized by a peak emission wavelength of 300 nm or less (e.g., 266 nm). 3+ This can be generated by a laser (such as a YAG laser).

[0042]

[0048] Method 250 may also optionally include forming a light conversion region in step 275. In embodiments, a light conversion region may be formed on an LED structure to convert light emitted by the LED structure to longer wavelength light that is transmitted through pixels or subpixels of an LED display. For example, FIG. 6 shows a light conversion region 625 formed on an LED structure 605. The light conversion region 625 absorbs light emitted by the LED structure 605 and emits longer wavelength light from the LED display. In embodiments, the light emitted by the LED structure 605 may be characterized by a peak intensity wavelength of about 425 nm or less, about 415 nm or less, about 405 nm or less, about 395 nm or less, about 385 nm or less, about 375 nm or less, about 365 nm or less, about 355 nm or less, or less. This light can be absorbed by the light conversion region 625, causing this region to emit longer wavelength light characterized by a peak intensity wavelength of about 400 nm or greater, about 425 nm or greater, about 500 nm or greater, about 525 nm or greater, about 550 nm or greater, about 575 nm or greater, about 600 nm or greater, about 625 nm or greater, about 650 nm or greater, about 675 nm or greater, about 700 nm or greater, or greater.

[0043]

[0049] In embodiments, the light conversion layer 625 may be a quantum dot layer. In additional embodiments, the quantum dot layer may be operable to convert shorter wavelengths of light from the LED structure 605 to one of red light, green light, or blue light. Additional quantum dot layers may be formed on other LED structures (not shown) to convert shorter wavelengths of light emitted by the LED structures to other red, green, and blue light. In further embodiments, a combination of three quantum dot layers on three LED structures may form an LED pixel including subpixels operable to emit red, green, and blue light. In many embodiments, a sequential process may be used to form a red quantum dot layer on one of the subpixels of each LED pixel, then a green quantum dot layer on another of the subpixels, and then a blue quantum dot layer on yet another of the subpixels. After the formation of the blue quantum dots, each LED pixel in the array of LED pixels includes red, green, and blue subpixels.

[0044]

[0050] In additional embodiments, forming a quantum dot layer operable to emit a specific color of visible light (e.g., red light, green light, or blue light) in an LED subpixel may include dispensing a photocurable fluid onto a high pixel density LED structure, activating one of the subpixels of each LED pixel in the array of LED pixels to irradiate and cure the photocurable fluid on that subpixel, and removing uncured photocurable fluid from the other subpixels that were not activated. These formation steps may be repeated for subpixels that emit light of each color in the array of LED pixels. In embodiments, the formation steps cause the quantum dot layer to self-align with activated subpixels of the LED pixels across the entire array of LED pixels. No precise alignment steps are required to form the quantum dot layer on the appropriate group of subpixels. The self-alignment of the quantum dot layer becomes increasingly beneficial as the size of the subpixels decreases and pixel density increases.

[0045]

[0051] In embodiments, the photocurable fluid may include one or more crosslinking compounds, a photoinitiator, and a color conversion agent. In additional embodiments, the crosslinking compound may include a monomer that forms a polymer when cured. In further embodiments, the monomer may include an acrylate monomer, a methacrylate monomer, and an acrylamide monomer. In even more embodiments, the crosslinking compound may include a negative photoresist material, such as SU-8 photoresist. In further embodiments, the photoinitiator may include phosphine oxide compounds and keto compounds, among other types of photoinitiator compounds, that generate radicals that initiate the curing of unsaturated compounds when excited by ultraviolet light. Commercially available photoinitiator compounds include Irgacure 184, Irgacure 819, Darocur 1173, Darocur 4265, Darocur TPO, Omnicat 250, and Omnicat 550, among other photoinitiators. In still further embodiments, the color conversion agent may include quantum dot materials capable of absorbing shorter wavelength (i.e., higher energy) light from the LED structure and emitting longer wavelength light corresponding to the color of the light emitted by the subpixel. In embodiments, these quantum dot materials may include nanoparticles made of one or more types of inorganic semiconductor materials such as indium phosphide, silver-indium-gallium-sulfur (AIGS), cadmium selenide, cadmium telluride, zinc selenide, zinc sulfide, silicon, silicates, graphene, doped inorganic oxides, among other semiconductor materials.

[0046]

[0052] Embodiments of the present technology, such as method 250, include processes for fabricating LED semiconductor structures that reduce damage to the structure's backplane components caused by the laser lift-off process. These processes include forming a light-absorbing barrier between LED structures formed on a substrate in the region of the removable LED substrate. The light-absorbing barrier absorbs high-energy ultraviolet light that would otherwise penetrate the inter-device region and photoionize the backplane substrate material. In additional embodiments, a light-absorbing barrier that absorbs high-energy ultraviolet light can improve the transmittance and reflectance of low-energy ultraviolet and visible light. In embodiments of the present technology that include an LED semiconductor structure that includes both a light-absorbing barrier and a reflective layer, the light-absorbing barrier can increase the fraction of light emitted by the LED structure that is reflected by the reflective layer by several percent. Thus, embodiments of the present technology provide a method for fabricating LED displays that reduce damage from the laser lift-off process and increase useful light emission due to the improved reflectivity of the combined light-absorbing barrier and reflective layer.

[0047]

[0053] In the foregoing specification, for purposes of explanation, numerous details have been set forth in order to provide an understanding of various embodiments of the present technology. However, it will be apparent to one skilled in the art that particular embodiments may be practiced without some of these details or with additional details.

[0048]

[0054] Although several embodiments have been disclosed, those skilled in the art will recognize that various modifications, alternative structures, and equivalents can be used without departing from the spirit of the embodiments. Moreover, to avoid unnecessarily obscuring the present technology, some well-known processes and elements have not been described. Therefore, the above specification should not be construed as limiting the scope of the present technology. Furthermore, while a method or process may be described sequentially or stepwise, it should be understood that steps may be performed simultaneously or in an order different from that listed.

[0049]

[0055] Where a range of values ​​is provided, it is understood that each intervening value, to the smallest fraction of the unit of the lower limit, between the upper and lower limit of that range is also specifically disclosed, unless the context clearly dictates otherwise. Any narrower range between any stated value or unstated intervening value in a stated range and any other stated or intervening value in that stated range is also included. The upper and lower limits of these smaller ranges may independently be included or excluded, and each range where the smaller range includes one, both, or neither limit is also included within the technology, subject to any specifically excluded limit in the stated range. Where a stated range includes one or both of the limits, ranges excluding either or both of those included limits are also included.

[0050]

[0056] As used in this specification and the appended claims, the singular forms "a," "an," and "the" include plural references unless the context clearly dictates otherwise. Thus, for example, reference to "a trench" includes a plurality of such trenches, reference to "the layer" includes a reference to one or more layers and equivalents thereof known to those skilled in the art, and so forth.

[0051]

[0057] Also, as used in this specification and the claims that follow, the terms "comprise," "comprising," "contain," "containing," "include," and "including" specify the presence of stated features, integers, components, or steps, but they do not exclude the presence or addition of one or more other features, integers, components, steps, operations, or groups.

Claims

1. 1. A semiconductor processing method comprising: forming a group of LED structures on a substrate layer to form a patterned LED substrate; depositing a light-absorbing barrier on the patterned LED substrate; exposing the patterned LED substrate to light, wherein the light is absorbed by surfaces of an LED structure in contact with the substrate layer and a light absorbing layer; separating the LED structure from the substrate layer, wherein the bond between the LED structure and the substrate layer is weakened by absorption of the light by a surface of the LED structure in contact with the substrate layer; A semiconductor processing method comprising:

2. 10. The semiconductor processing method of claim 1, wherein the group of LED structures comprises a gallium-nitrogen containing material, the gallium-nitrogen containing material generating nitrogen gas upon exposure to the light at a surface of the LED structure in contact with the substrate layer.

3. The semiconductor processing method of claim 1 , wherein the substrate layer comprises sapphire.

4. 10. The semiconductor processing method of claim 1, wherein the light is characterized by a peak intensity wavelength of about 300 nm or less.

5. 10. The semiconductor processing method of claim 1, wherein said light absorbing barrier comprises one or more layers of a dielectric material, said dielectric material characterized by a room temperature bandgap of about 4.3 eV or greater.

6. 10. The semiconductor processing method of claim 1, wherein said light absorbing barrier is operable to transmit light emitted from said LED structure.

7. 10. The semiconductor processing method of claim 1, wherein the semiconductor further comprises a backplane substrate coupled to the group of LED structures on an opposite side of the substrate layer.

8. 8. The semiconductor processing method of claim 7, wherein the light absorbing barrier prevents the light to which the patterned LED substrate is exposed from reaching the backplane substrate.

9. 1. A semiconductor processing method comprising: forming an LED structure on a substrate layer; forming a first portion of a light-absorbing barrier over the LED structure and the substrate layer; forming at least one additional portion of the light absorbing barrier on a first portion of the light absorbing barrier; exposing the substrate layer to ultraviolet light, the ultraviolet light being absorbed by exposed portions of the light absorbing barrier; separating the LED structure from the substrate layer; A semiconductor processing method comprising:

10. 10. The semiconductor processing method of claim 9, wherein the first portion of the light absorbing barrier comprises a first dielectric material selected from the group consisting of silicon oxide, silicon nitride, titanium oxide, titanium nitride, germanium oxide, tantalum oxide, tantalum nitride, manganese oxide, niobium oxide, antimony oxide, indium tin oxide, lanthanum oxide, yttrium oxide, zirconium oxide, aluminum oxide, aluminum nitride, hafnium oxide, and magnesium fluoride.

11. 11. The semiconductor processing method of claim 10, wherein the at least one additional portion of the light absorbing barrier includes a second portion comprising a second dielectric material different from the first dielectric material.

12. 10. The semiconductor processing method of claim 9, wherein the ultraviolet radiation is less than or equal to about 300 nm.

13. 10. The semiconductor processing method of claim 9, further comprising forming a reflective layer on the light-absorbing barrier.

14. 14. The semiconductor processing method of claim 13, wherein the light absorbing barrier increases the reflectivity of the reflective layer to LED light emitted by the LED structure.

15. 1. A semiconductor structure comprising: a plurality of LED structures; a backplane layer; a light barrier region positioned between the LED structure and the backplane layer, the light barrier region operable to absorb light having a wavelength of about 300 nm or less and transmit light having a wavelength of about 350 nm or more; 1. A semiconductor structure comprising:

16. 16. The semiconductor structure of claim 15, wherein each of the plurality of LED structures includes an n-type doped gallium-nitrogen containing region, a multiple quantum well layer in contact with the n-type doped gallium-nitrogen containing region, and a p-type doped gallium-nitrogen containing region in contact with the multiple quantum well layer.

17. 16. The semiconductor structure of claim 15, wherein the backplane layer comprises an ultraviolet absorbing polymer.

18. 16. The semiconductor structure of claim 15, wherein the light barrier region comprises two or more layers of a dielectric material selected from the group consisting of silicon oxide, silicon nitride, titanium oxide, titanium nitride, germanium oxide, tantalum oxide, tantalum nitride, manganese oxide, and niobium oxide, and wherein a first layer of dielectric material is different from a second layer of dielectric material in contact with the first layer of dielectric material.

19. 16. The semiconductor structure of claim 15, further comprising a reflective layer in contact with the light barrier region.

20. 16. The semiconductor structure of claim 15, wherein the semiconductor structure further comprises a light conversion region in contact with at least one of the LED structures, the light conversion region operable to absorb light generated by the LED structure and emit converted light characterized by a longer peak intensity wavelength.

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