High pixel density structure and method for manufacturing the same

Abstract

A method for fabricating a high pixel density LED structure is described. The method may include forming a backplane substrate and an LED substrate. The backplane substrate and the LED substrate may be bonded to one another, and the combined substrate may include an array of LED pixels. Each of the LED pixels may include a group of isolated subpixels. A quantum dot layer may be formed on at least one of the isolated subpixels of each of the LED pixels. The method may further include repairing at least one defective LED pixel by forming a replacement quantum dot layer on a subpixel of the defective LED pixel that does not have a quantum dot layer. The method may also include forming a UV barrier layer on the array of LED pixels after repairing the at least one defective LED pixel.

Description

Technical Field

[0001] Cross - reference to Related Applications

[0001] This application claims the benefit and priority of U.S. Non - Provisional Application No. 17 / 345,970, filed on June 11, 2021, entitled "HIGH PIXEL DENSITY STRUCTURES AND METHODS OF MAKING", the entire content of which is incorporated herein by reference.

[0002]

[0002] This technology relates to semiconductor processes and semiconductor products. More specifically, this technology relates to the manufacture of semiconductor structures and fabricated devices.

Background Art

[0003]

[0003] Light - emitting diode (LED) display devices made up of millions of micron - sized pixels are enabled by a manufacturing process that forms a complexly patterned material layer on a substrate surface. To manufacture the patterned material on the substrate, controlled methods of material deposition and removal are required. However, with new device designs, it can be difficult to manufacture high - quality material layers with very precise 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 this technology.

Summary of the Invention

[0005]

[0005] The technology includes an exemplary semiconductor processing method comprising forming a backplane substrate and an LED substrate. The backplane substrate and the LED substrate are coupled to each other, and the coupled substrate includes an array of LED pixels. Each LED pixel may include a group of isolated subpixels. A quantum dot layer may be formed on at least one of the isolated subpixels of each LED pixel. The method may further include repairing at least one defective LED pixel by forming a replacement quantum dot layer on a subpixel of the defective LED pixel that does not have a quantum dot layer. The method may also include forming a UV barrier layer on the array of LED pixels after repairing at least one defective LED pixel.

[0006]

[0006] In additional embodiments, each LED subpixel may include a gallium-nitrogen-containing light-emitting diode structure capable of emitting a first wavelength light characterized by a wavelength of about 400 nm or less. In further embodiments, a quantum dot layer is capable of absorbing the first wavelength light emitted from the gallium-nitrogen-containing light-emitting diode structure and emitting a second wavelength light characterized by a wavelength longer than the first wavelength light. In even further embodiments, a substitution quantum dot layer is capable of emitting light of the same wavelength as a quantum dot layer formed on a non-operating subpixel of a defective LED pixel. In even further embodiments, an unrepaired LED pixel includes a subpixel without a quantum dot layer after a UV barrier layer has been formed on the array of LED pixels. In even further embodiments, the array of LED pixels has a pixel density of about 1000 pixels or more per inch. In even further embodiments, the longest dimension of each isolated subpixel is about 10 μm or less. In even further embodiments, the method further includes forming a microlens on at least one of each subpixel of the LED pixel.

[0007]

[0007] The technology also includes additional semiconductor processing methods which may include forming a backplane substrate and an LED substrate. The backplane substrate and the LED substrate can be coupled together, and the coupled substrate includes an array of LED pixels. Each LED pixel may include at least four isolated subpixels. A quantum dot layer may be formed on at least three of the isolated subpixels of each LED pixel. Each quantum dot layer may be operable to emit visible light of a different wavelength than the other quantum dot layers of the LED pixel. The method may further include forming a UV barrier layer on the array of LED pixels. In embodiments, after forming the UV barrier layer, at least some of the LED pixels include at least one subpixel without a quantum dot layer.

[0008]

[0008] In an additional embodiment, a pixel isolation structure may be formed on the LED substrate before the LED substrate and the backplane substrate are joined together. In a further embodiment, a pixel isolation structure is formed on the joined substrate after the LED substrate and the backplane substrate are joined together. In yet another embodiment, an LED structure is formed on the LED substrate before the LED substrate and the backplane substrate are joined together. In yet another embodiment, an LED structure is formed on the joined substrate after the LED substrate and the backplane substrate are joined together. In a further embodiment, an additional backplane substrate is joined to the joined substrate on the exposed surface of the LED substrate.

[0009]

[0009] The technology further includes a semiconductor structure which may include a backplane layer, an array of LED pixels in contact with the backplane layer, and a UV barrier layer on the array of LED pixels. Each LED pixel may include at least four isolated subpixels. At least three of the isolated subpixels may include a quantum dot layer, and at least some of the LED pixels may include subpixels without a quantum dot layer.

[0010]

[0010] In an additional embodiment, the backplane layer includes a silicon-containing layer having a CMOS device that electrically contacts each of the isolated subpixels of the LED pixel. In a further embodiment, the semiconductor structure includes a pixel isolation structure between each of the subpixels of the LED pixel. The pixel isolation structure prevents light emitted from one of the subpixels from being absorbed by an adjacent subpixel. In another further embodiment, each subpixel may include a gallium-nitrogen-containing light-emitting diode structure. In yet another embodiment, at least one of the subpixels of the LED pixel further includes a microlens that contacts a UV barrier layer. In yet another embodiment, the semiconductor structure is incorporated into an LED display for a virtual reality headset or augmented reality glasses.

[0011]

[0011] The above technology may offer many advantages over conventional semiconductor processing methods and structures. For example, an embodiment of the processing method can produce a high-pixel-density display with fewer defective pixels than conventional processing methods. In a further embodiment, the processing method can produce a display having a pixel density of about 1000 pixels per inch or more by coupling a high-density LED substrate with a backplane substrate that includes a submicron-sized control circuit that can individually address the subpixels of each pixel of the display. In yet another embodiment, the high pixel density and low-pixel-defect structure create an improved viewing experience in displays viewed at close range, such as virtual reality headsets and augmented reality glasses. These and other embodiments will be described in more detail below, along with their many advantages and features, in conjunction with the accompanying drawings.

[0012]

[0012] A further understanding of the nature and advantages of the disclosed technology can be obtained by referring to the remainder of this specification and the drawings. [Brief explanation of the drawing]

[0013] [Figure 1]Figures A and B are simplified top views showing a backplane and an LED substrate, including a fiducial for aligning the substrate for coupling, according to some embodiments of the present technology. [Figure 2] This is a top view showing a portion of an LED array according to an embodiment of this technology. [Figure 3] This is a split cross-sectional view showing an LED pixel according to an embodiment of this technology. [Figure 4] This is a cross-sectional view showing a gallium-nitrogen-containing LED structure according to an embodiment of this technology. [Figure 5] This figure shows an exemplary step in a method for forming a high-pixel-density semiconductor structure according to some embodiments of this technology. [Figure 6A] This is a cross-sectional view showing a semiconductor structure processed according to an embodiment of this technology. [Figure 6B] This is a cross-sectional view showing a semiconductor structure processed according to an embodiment of this technology. [Figure 6C] This is a cross-sectional view showing a semiconductor structure processed according to an embodiment of this technology. [Figure 6D] This is a cross-sectional view showing a semiconductor structure processed according to an embodiment of this technology. [Figure 6E] This is a cross-sectional view showing a semiconductor structure processed according to an embodiment of this technology. [Figure 7A] This is a cross-sectional view showing another semiconductor structure processed according to an embodiment of this technology. [Figure 7B] This is a cross-sectional view showing another semiconductor structure processed according to an embodiment of this technology. [Figure 7C] This is a cross-sectional view showing another semiconductor structure processed according to an embodiment of this technology. [Figure 7D] This is a cross-sectional view showing another semiconductor structure processed according to an embodiment of this technology. [Figure 7E] This is a cross-sectional view showing another semiconductor structure processed according to an embodiment of this technology. [Figure 7F]A cross-sectional view showing another semiconductor structure being processed according to an embodiment of the present technology. [Figure 8] A and B are cross-sectional views showing yet another semiconductor structure being processed according to an embodiment of the present technology. [Figure 9] A and B are cross-sectional views showing a further semiconductor structure being processed according to an embodiment of the present technology. [Figure 10] A and B are cross-sectional views showing yet another semiconductor structure being processed according to an embodiment of the present technology.

Embodiments for Carrying Out the Invention

[0014]

[0023] Some of the drawings are included as schematic views. It should be understood that the figures are for illustrative purposes and should not be considered to be to scale unless the scale is specifically stated. Further, as schematic views, the figures are provided to assist understanding and may not include all aspects or information compared to a realistic representation, and may include exaggerated materials for illustrative purposes.

[0015]

[0024] In the accompanying figures, similar components and / or features may be labeled with the same reference labels. Further, various components of the same type can be distinguished by attaching letters after the reference label to distinguish similar components. When only the first reference label is used in this specification, the description is applicable to any one of the similar components having the same first reference label regardless of the letter.

[0016]

[0025] This technology includes embodiments for manufacturing high-pixel-density light-emitting diode devices with a low number of defective pixels. Additional embodiments include high-pixel-density semiconductor structures that can be incorporated into proximity-view display devices such as virtual reality headsets and augmented reality glasses, as well as displays for high-resolution televisions, monitors, and electronic devices such as smartphones and tablets. Embodiments of this technology include methods for manufacturing semiconductor structures having approximately 1,000 pixels per inch (ppi) or more and with so few defective pixels that most viewers would not notice them.

[0017]

[0026] LCD display technology has rapidly increased display resolution over the past decade. Most LED TVs and monitors currently on the market have a pixel density of around 80 ppi (i.e., "4K" resolution), and the number of manufacturers offering 160 ppi (i.e., "8K" resolution) displays is also increasing. The display industry is beginning to unveil next-generation high-resolution displays called "micro-LED" displays (commonly known as μ-LEDs), which have a pixel density of up to 650 ppi. However, even the resolution of these micro-LED displays may not be high enough for many applications where viewers see the display at a very close distance (e.g., less than about 3 inches), such as virtual reality headsets and augmented reality glasses. Many of these applications require displays with a pixel density of around 1000 ppi or higher for a satisfactory user experience.

[0018]

[0027] Unfortunately, conventional control circuits for LCD subpixels fabricated from thin-film transistors suffer from increasing performance problems, particularly reduced response time and brightness, as pixel densities increase significantly beyond 600 ppi. Attempts to address these performance issues include the development of organic LED (OLED) technology that approaches pixel densities of less than 1000 ppi. However, these OLED technologies use organic polymer materials that can degrade over time, shortening the lifespan of the display. Improved methods and structures are needed to manufacture stable high-pixel-density structures for displays characterized by pixel densities of approximately 1000 ppi or higher.

[0019]

[0028] Another problem in manufacturing high-pixel-density structures is that a higher number of pixels means a greater chance of pixel defects occurring during the manufacturing process. Pixel defects include point defects of subpixels that do not emit light at all (i.e., "dead" subpixels), and subpixels that emit too much or too little light, causing color distortion throughout the pixel. Unfortunately, in high-pixel-density structures, as pixel dimensions decrease, it becomes increasingly difficult to isolate and replace point defects in subpixels without damaging adjacent subpixels and the control circuits of one or more backplane layers that electronically communicate with the subpixels. Improved methods are needed to replace subpixels in defective LED pixels and reduce the number of pixel defects in high-pixel-density structures.

[0020]

[0029] Another problem arising from increasing pixel density beyond approximately 1000 ppi is a characteristic known as crosstalk, where interference from light emitted by adjacent subpixels increases. Increased crosstalk between densely packed pixels and subpixels can cause discoloration and image distortion on the display. Improved manufacturing methods and structures are needed to isolate the light emitted from each subpixel and prevent increased crosstalk between each subpixel and its neighbors.

[0021]

[0030] Embodiments of this technology address the problems encountered when increasing the pixel density of a high-pixel-density display to approximately 1000 ppi or more. The embodiments include a manufacturing method for growing LED material on one substrate (LED substrate) and forming a control circuit for controlling light emission from the LED on a second substrate (backplane substrate). In the embodiments, the backplane substrate may be a silicon substrate on which CMOS circuits for addressing and activating each subpixel of the LED display are formed. The CMOS circuits may be characterized by a fast response time for activating subpixels with a maximum dimension of approximately 10 μm or less.

[0022]

[0031] Embodiments of this technology also address the problem of reducing the number of defective pixels in high-pixel-density structures. In embodiments, the manufacturing method may include forming at least one extra subpixel on each LED pixel that can function as a replacement subpixel if one of the other subpixels of the LED pixel is defective. In further embodiments, a defective LED pixel can be repaired by forming a quantum dot layer on the extra subpixel that emits light of approximately the same wavelength as the subpixel being replaced. After repairing the defective LED pixel, the manufacturing process is continued to produce a high-pixel-density structure with a small or no number of defective LED pixels.

[0023]

[0032] Embodiments of this technology further include a method for manufacturing a high-pixel-density structure having a pixel-separating element that prevents light emitted from one subpixel from interfering with light emitted from an adjacent subpixel. The pixel-separating element reduces crosstalk caused by light emitted from adjacent subpixels, thereby reducing discoloration and image distortion in displays incorporating the high-pixel-density structure.

[0024] LED-containing high pixel density structure

[0033] Figures 1A and 1B are top views showing a backplane substrate and an LED substrate that can be coupled to each other to form a high-pixel-density structure according to an embodiment of the present technology. Figure 1A shows a backplane substrate 102 and an LED substrate 104. In an embodiment, the backplane substrate 102 may be a silicon substrate on which a CMOS device structure 106 is formed for addressing and controlling subpixels of LED pixels. In a further embodiment, the LED substrate 104 may include a layer of LED material that forms subpixels of an array of LED pixels in a high-pixel-density structure. In a further embodiment, the LED substrate 104 may include a substrate growth layer such as silicon or sapphire on which other layers of LED material are formed. In the embodiment shown in Figure 1A, the LED structure may not be formed on the LED substrate 104 until the substrates are coupled to each other. In a further embodiment, the backplane substrate 102 and the LED substrate 104 further include fiducials 108 and 110, respectively, to assist in substrate alignment during coupling.

[0025]

[0034] Figure 1B shows another embodiment of the backplane substrate 152 and LED substrate 154. In this embodiment, the backplane substrate 152 may be a silicon substrate on which a CMOS device structure 156 is formed for addressing and controlling subpixels of LED pixels. In the embodiment shown in Figure 1B, the LED structure 162 is formed on the LED substrate 154 before the LED substrate is coupled to the backplane substrate 152. In additional embodiments, the backplane substrate 152 and LED substrate 154 further include fiducials 158 and 160, respectively, to assist in substrate alignment during coupling.

[0026]

[0035] Figure 2 is a top view showing a portion of an LED array 200 according to an embodiment of the present technology. In the illustrated embodiment, a portion of the LED array 200 includes four LED pixels 202, each containing four subpixels 204a to d. The subpixels 204a to d include three subpixels 204a to c that are operable to emit visible light of different average peak wavelengths, and a fourth subpixel 204d that can function as a replacement subpixel if any of the other three subpixels 204a to c fail during the manufacturing of a high-pixel-density structure. In the embodiment, the three subpixels 204a to c may be operable to emit visible light in the red, green, and blue portions of the electromagnetic spectrum. In a further embodiment, subpixel 204a may be a red subpixel capable of emitting visible light characterized by peak intensity wavelengths of approximately 580 nm or higher, approximately 585 nm or higher, approximately 590 nm or higher, approximately 595 nm or higher, approximately 600 nm or higher, approximately 605 nm or higher, approximately 610 nm or higher, approximately 615 nm or higher, approximately 620 nm or higher, or higher. In a further embodiment, subpixel 204b may be a green subpixel capable of emitting visible light characterized by peak intensity wavelengths of 500 nm to 580 nm. In further embodiments, the subpixel 204c may be a blue subpixel capable of emitting visible light characterized by peak intensity wavelengths of approximately 500 nm or less, approximately 490 nm or less, approximately 480 nm or less, approximately 470 nm or less, approximately 460 nm or less, approximately 450 nm or less, approximately 440 nm or less, approximately 430 nm or less, approximately 420 nm or less, approximately 410 nm or less, approximately 400 nm or less, or less. In further embodiments, the light emitted from the subpixel may be characterized by spectral bandwidths of approximately 100 nm or less, approximately 90 nm or less, approximately 80 nm or less, approximately 70 nm or less, approximately 60 nm or less, approximately 50 nm or less, approximately 40 nm or less, approximately 30 nm or less, approximately 20 nm or less, or less.

[0027]

[0036] In the embodiment shown in Figure 2, subpixels 204a-d are shown as squares, and pixel 202 is shown as a square arrangement of four square subpixels. It will be understood that embodiments of subpixels 204a-d may have additional shapes among other types of shapes, such as rectangles, parallelograms, trapezoids, pentagons, hexagons, heptagons, octagons, nonagons, circles, and ellipses. In further embodiments, pixel 202 may also be arranged in additional shapes among other types of shapes, such as rectangles, parallelograms, trapezoids, circles, and ellipses. In further embodiments, each of subpixels 204a-d may be characterized by a longest dimension (e.g., diagonal length) of about 10 μm or less, about 9 μm or less, about 8 μm or less, about 7 μm or less, about 6 μm or less, about 5 μm or less, or less. In further embodiments, each of the pixels 202 may be characterized by a maximum dimension of approximately 25 μm or less, approximately 22.5 μm or less, approximately 20 μm or less, approximately 17.5 μm or less, approximately 15 μm or less, approximately 12.5 μm or less, approximately 10 μm or less, or less.

[0028]

[0037] Figure 3 is a split cross-sectional view showing an LED pixel 300 according to an embodiment of the present technology. In the illustrated embodiment, an LED pixel such as the pixel 202 shown in Figure 2 is cut and split between subpixels 204a-b and 204c-d to reveal the cross-sectional liner arrangement of red, green, blue, and blank subpixels 302a-d. The subpixels 302a-d are separated from each other by a pixel isolation structure 304 between adjacent subpixels. In the embodiment, one or more of the subpixels 302a-d may include a microlens 306 disposed on a UV barrier layer 308. In a further embodiment, each subpixel 302a-c may further include quantum dot layers 310a-c that are operable to emit different peak intensity wavelengths of visible light (e.g., red, green, and blue light). A fourth subpixel 302d may include a matrix material without a quantum dot layer, unless it functions as a replacement subpixel for one of the other subpixels.

[0029]

[0038] The subpixels 302a-d may include an LED structure 312 that can operate to generate short-wavelength light, thereby exciting quantum dot layers 310a-c to emit longer-wavelength visible light. In an additional embodiment, the LED structure 312 may be activated independently by a backplane substrate 314. In an embodiment, the backplane substrate 314 may include a pair of first contacts 316 and second contacts 318 formed on a semiconductor layer 318 that independently deals with the LED structure 312. In an embodiment, the contacts may be made of a conductive material such as copper, aluminum, gold, tungsten, chromium, or nickel, among other conductive materials. In yet another embodiment, the LED structure 312 may be positioned between transparent conductive layers 322 and 324 that form part of a conductive path between the LED structure and the contacts of the backplane substrate 314. In an additional embodiment, the transparent conductive layers may be made of indium tin oxide or indium zinc oxide, among other transparent conductive materials. In a further embodiment, the mirror layer 326 can be positioned adjacent to the transparent electrical layer 324 to reflect the light emitted by the LED structure toward the quantum dot layer. In a further embodiment, the mirror layer may be made of one or more reflective metals such as copper, aluminum, chromium, silver, platinum, or molybdenum. In a further embodiment, a conductive bonding layer 328 that bonds the LED substrate to the backplane substrate may be positioned between the mirror layer 326 and the backplane substrate 314. In a further embodiment, the conductive bonding layer may be made of one or more conductive materials such as tin, gold, or indium, among other conductive materials.

[0030]

[0039] In additional embodiments, an electrically insulating passivation layer 329 may be positioned around the LED structure 312 and adjacent conductive layers (e.g., transparent conductive layers 322 and 324, mirror layer 326, and coupling layer 328). The passivation layer 329 electrically isolates the LED structure 312 from other conductive materials of subpixels 302a-d, allowing only the first and second contacts 316 and 318 to electrically switch the LED structure on and off. In embodiments, the passivation layer may be made of a dielectric material such as silicon oxide, silicon nitride, aluminum oxide, or aluminum nitride, among other dielectric materials. In further embodiments, subpixels 302a-d can be independently switched on and off by transmitting electrical signals through the first and second contacts 316 and 318. The electrical signals can pass through the contacts and other conductive layers such as the coupling layer 328, mirror layer 326, and transparent conductive layers 322 and 324 to activate the LED structure and cause the LED structure to emit light.

[0031]

[0040] In further embodiments, the wavelength of light emitted by the LED structure 312 may be shorter (i.e., have higher energy) than the wavelength emitted by any of the quantum dot layers 310a to c. In additional embodiments, the LED structure 312 may be operable to emit light characterized by peak intensity wavelengths of approximately 400 nm or less, approximately 395 nm or less, approximately 390 nm or less, approximately 385 nm or less, approximately 380 nm or less, approximately 375 nm or less, approximately 370 nm or less, approximately 365 nm or less, approximately 360 nm or less, approximately 355 nm or less, approximately 350 nm or less, or less. In even further embodiments, the LED structure 312 may emit light with the same peak intensity wavelength as ultraviolet light or with a peak intensity wavelength different from ultraviolet light.

[0032]

[0041] In the embodiment, the LED structure 312 may be a gallium-nitrogen-containing LED structure. Figure 4 is a simplified cross-sectional view showing a gallium-nitrogen-containing LED structure 400 that may be included in the high-pixel-density structure of the present technology. In the illustrated embodiment, the LED structure 400 is an epitaxially formed gallium nitride LED structure on a substrate 402. In additional embodiments, the substrate 402 may be a silicon substrate or a sapphire substrate, among other types of substrates. The LED structure further includes an n-doped GaN layer 404 and a p-doped GaN layer 408. Formed between the n-doped GaN layer 404 and the p-doped GaN layer 408 is a multiple quantum well (MQW) region 406 from which light emitted by the LED structure is generated. The LED structure 400 may further include a conductive N-pad contact 410 that forms a path for current to pass through the n-doped GaN layer 404. The LED structure 400 may also include a conductive P-pad contact 412 that forms a path for current to pass through the p-doped GaN layer 408. N-pad contacts 410 and P-pad contacts 412 can be connected to the conductive layer of the LED subpixel, or they can be directly connected to the contacts of the control circuit on the backplane substrate. In an embodiment, an electrical signal from the control circuit creates a current flow through the LED structure 400, causing light emission from the MQW region 406 of the structure. In an additional embodiment, the MQW region 406 is formed to emit light characterized by a reproducible peak intensity wavelength and quantum efficiency for an applied electrical signal (e.g., current and / or voltage). In an embodiment, the peak intensity wavelength of the light emitted from the MQW region 406 may be an ultraviolet wavelength.

[0033]

[0042] Figure 4 shows an LED structure 400 fully formed on a substrate 402. In additional embodiments described later, the substrate 402 may be removed from the layer of LED material forming the LED structure 400 before the structure is formed. In some of these embodiments, the LED substrate and the backplane substrate are bonded to each other before the LED material is formed within individual LED structures such as structure 400. In additional embodiments, the substrate 402 is separated from the layer of LED material bonded to the backplane substrate before the layer of LED material is formed within the LED structure.

[0034]

[0043] Returning to Figure 3, the short-wavelength light emitted by the LED structure 312 excites the quantum dot layers 310a to c, causing them to emit longer-wavelength light. As described above, each quantum dot layer 310a to c can absorb light from its respective LED structure 312 and operate to emit light from different parts of the electromagnetic spectrum. In the illustrated embodiment, quantum dot layer 310a can operate to emit light from the red part of the spectrum, quantum dot layer 310b can operate to emit light from the green part of the spectrum, and quantum dot layer 310c can operate to emit light from the blue part of the spectrum. The light generated by the quantum dot layers 310a to c and the LED structure 312 absorbs the ultraviolet light generated by the LED structure 312 but passes through the UV barrier layer 308, which allows visible light from the quantum dot layers 310a to c to pass through. In some embodiments, light that has passed through the UV barrier layer 308 can be focused by the microlens 306, further improving the quality of the image displayed by the high-pixel-density structure.

[0035]

[0044] In embodiments of this technology, the LED structure 312 can emit light characterized by the same or nearly the same peak intensity wavelength. These embodiments address the problems relating to gallium-nitrogen-containing LED structures having significantly different quantum efficiencies in emission at different peak intensity wavelengths. These differences are particularly pronounced between gallium-nitrogen-containing LED structures emitting red and blue visible light. Gallium-nitrogen-containing LED structures have significantly higher quantum efficiencies in blue light emission than in red light emission, often requiring additional structural and processing techniques to compensate for this. In embodiments of this technology, the LED structure 312 may be formed to emit light at the same or nearly the same peak intensity wavelength, and may be selected to emit light at wavelengths that have high quantum efficiency for the gallium-nitrogen-containing LED structure. In additional embodiments, the peak intensity wavelength may be an ultraviolet wavelength that is absorbed by the quantum dot layer and causes the quantum dot layer to emit visible wavelength light. In contrast to gallium-nitrogen-containing LED structures, which have a wide range of variation in the quantum efficiency of light emitted between the blue and red regions of the visible spectrum, quantum dot layers have a narrower variation in quantum efficiency for light absorbed at ultraviolet wavelengths to cause emission at different wavelengths of the visible spectrum.

[0036]

[0045] In embodiments, the variation range of the quantum efficiency of visible light emitted from the quantum dot layers 310a-c may be about 25% or less, about 15% or less, about 10% or less, about 5% or less, about 2.5% or less, about 1% or less, or less. In additional embodiments, the quantum dot layers may be characterized by a quantum efficiency of about 50% or more, about 60% or more, about 70% or more, about 80% or more, about 90% or more, about 95% or more, about 97% or more, about 98% or more, about 99% or more, or higher.

[0037]

[0046] In further embodiments, crosstalk caused by light generated from adjacent and nearby subpixels can be reduced or eliminated by the pixel isolation structure 304 between adjacent subpixels. In embodiments, the reduction in the intensity of light from adjacent and nearby pixels may be about 50% or more, about 60% or more, about 70% or more, about 80% or more, about 90% or more, about 95% or more, about 99% or more, or more. In additional embodiments, the pixel isolation structure 304 may include a core column of pixel isolation material covered by one or more additional layers of material, such as a layer of reflective material such as aluminum or copper. In embodiments, the material of the core column may include metallic or dielectric materials, among other types of materials. In further embodiments, the metallic material may include one or more of silicon, tungsten, copper, and aluminum, among other metals. In even further embodiments, the dielectric material may include one or more of silicon oxide, silicon nitride, silicon carbide, photoresist materials, or dielectric organic polymer materials, among other dielectric materials.

[0038]

[0047] In some embodiments, the pixel isolation structure 304 may extend from the backplane substrate 314 to the upper surface of the quantum dot layers 310a to c. In further embodiments, the pixel isolation structure 304 may extend to the UV barrier layer 308, and in even further embodiments, to the apex of the microlens 306. In additional embodiments, the pixel isolation structure 304 may have a height of about 2.5 μm or more, about 5 μm or more, about 7.5 μm or more, about 10 μm or more, about 12.5 μm or more, about 15 μm or more, about 17.5 μm or more, about 20 μm or more, or greater. In even further embodiments, the pixel isolation structure 304 may have a width of about 1 μm or more, about 2 μm or more, about 3 μm or more, about 4 μm or more, about 5 μm or more, about 6 μm or more, about 7 μm or more, about 8 μm or more, about 9 μm or more, about 10 μm or greater, or greater. In further embodiments, the pixel separation structure 304 may have a height-to-width aspect ratio of approximately 1.5:1 or greater, approximately 2:1 or greater, approximately 2.5:1 or greater, approximately 3:1 or greater, approximately 3.5:1 or greater, approximately 4:1 or greater, approximately 4.5:1 or greater, approximately 5:1 or greater, or greater.

[0039] Manufacturing method for high-pixel-density LED structures

[0048] Figure 5 is a flowchart showing selected steps in a method 500 for forming a high-pixel-density LED structure according to an embodiment of the present technology. Method 500 may or may not include one or more steps prior to the commencement 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 include a number of optional steps that may or may not be specifically related to certain embodiments of the method relating to the present technology. Method 500 describes steps for forming an embodiment of a semiconductor structure shown in a simplified schematic form in Figures 6A-6E, 7A-7F, 8A-8B, 9A-9B, and 10A-10B, and these illustrations will be described in conjunction with the steps of Method 500. Figures 6A–6E, 7A–7F, 8A–8B, 9A–9B, and 10A–10B are merely illustrative partial schematic diagrams with limited detail, and it should be understood that in some embodiments, the substrate may include any number of semiconductor sections having the configuration illustrated in the figures, as well as alternative structural configurations that may also benefit from any of the embodiments of this technology.

[0040]

[0049] The embodiments described in Method 500 include the steps of developing a high-pixel-density LED structure. Method 500 may include forming a backplane substrate 505 and forming an LED substrate 510. In embodiments, the backplane substrate may include a backplane layer that includes at least a portion of a control circuit for activating the subpixels of each LED pixel in the high-pixel-density LED structure. In additional embodiments, the backplane layer may be a silicon layer on which elements of the control circuit are formed, including contacts for forming conductive paths through the junction surface between the backplane substrate and the LED substrate.

[0041]

[0050] In the embodiment of the high-pixel-density structure 600 shown in Figure 6A, a separate backplane substrate 602 and an LED substrate 604 are provided. The backplane substrate 602 includes a backplane layer 606 on which first contacts 608 and second contacts 610 are formed. The backplane substrate 602 also includes an electrically insulating passivation layer 612. In the illustrated embodiment, the high-pixel-density structure 600 may be part of a flip-chip LED structure in which all control circuits of the structure are formed on the backplane substrate 602 and positioned on one side of the LED structure. The LED substrate 604 includes a gallium-nitrogen-containing layer 614 formed on the LED substrate layer 616. The LED substrate 604 also includes a transparent conductive layer 618, a mirror layer 620, and a bonding layer 622 formed on the gallium-nitrogen-containing layer 614 on the side opposite to the side in contact with the LED substrate layer 616. In the embodiment shown in Figure 6A, the LED structure is not formed in the layers of LED material and surrounding material until the backplane substrate 602 and the LED substrate 604 are bonded together.

[0042]

[0051] Figure 7A also shows a portion of a high-pixel-density structure 700 having separate backplane substrates 702 and LED substrates 704 according to an embodiment. The backplane substrate 702 includes a backplane layer 706 on which a first contact 708 is formed. The backplane substrate 702 also includes an electrically insulating passivation layer 712. In the illustrated embodiment, the high-pixel-density structure 700 may also be part of a vertical LED structure in which part of the control circuit of the structure is formed on the backplane substrate 702 and another part of the control circuit (not shown) is positioned on the side of the LED structure opposite the backplane substrate 702. The LED substrate 704 may include a stack of LED material layers formed on the substrate layer 716. The LED material layers may include a gallium-nitrogen-containing layer 714, a transparent conductive layer 718, a mirror layer 720, and a bonding layer 722. In the embodiment shown in Figure 7A, the LED structure is not formed on the LED material layers until after the backplane substrate 702 and the LED substrate 704 are bonded to each other.

[0043]

[0052] Figure 8A shows another embodiment of a part of a high-pixel-density structure 800 having separate backplane substrates 802 and LED substrates 804. The backplane substrate 802 includes a backplane layer 806 on which a first contact 808 is formed. The backplane substrate 802 also includes an electrically insulating passivation layer 812. In the illustrated embodiment, the high-pixel-density structure 800 may be part of a vertical LED structure in which part of the control circuit of the structure is formed on the backplane substrate 802 and another part of the control circuit (not shown) is positioned on the side of the LED structure opposite the backplane substrate 802. The LED substrate 804 may include a stack of LED material layers formed on the substrate layer 816. The LED material layers may include a gallium-nitrogen-containing layer 814, a transparent conductive layer 818, a passivation layer 819, a mirror layer 820, and a bonding layer 822. In the embodiment shown in Figure 8A, the LED structure is already formed on the LED material layers before the backplane substrate 802 and the LED substrate 804 are bonded to each other.

[0044]

[0053] Figure 9A shows yet another embodiment of a part of a high-pixel-density structure 900 having separate backplane substrates 902 and LED substrates 904. The backplane substrate 902 includes a backplane layer 906 on which a first contact 908 is formed. The backplane substrate 902 also includes an electrically insulating passivation layer 912. In the illustrated embodiment, the high-pixel-density structure 900 may be part of a vertical LED structure in which part of the control circuit of the structure is formed on the backplane substrate 902 and another part of the control circuit (not shown) is positioned on the side of the LED structure opposite the backplane substrate 902. The LED substrate 904 may include a stack of LED material layers formed on a substrate layer 916. The LED material layers may include a gallium-nitrogen-containing layer 914, a transparent conductive layer 918, a mirror layer 920, and a bonding layer 922. The LED substrate 904 may also include a pixel isolation structure 924 formed in a direction perpendicular to the other layers of the LED substrate 904. In the embodiment, the pixel isolation structure 924 may be made of a reflective and conductive material (e.g., a metal) and may be surrounded by an electrically insulating pixel isolation passivation layer 926 to prevent the pixel isolation structure from short-circuiting to the LED structure formed in the gallium-nitrogen-containing layer 914. In the embodiment shown in Figure 9A, the LED structure and the pixel isolation structure are already formed in the LED material layer before the backplane substrate 902 and the LED substrate 904 are bonded to each other.

[0045]

[0054] Figure 10A shows yet another embodiment of a part of a high-pixel-density structure 1000 having separate backplane substrates 1002 and LED substrates 1004. The backplane substrate 1002 includes a backplane layer 1006 on which a first contact 1008 is formed. The backplane substrate 1002 also includes an electrically insulating passivation layer 1012. In the illustrated embodiment, the high-pixel-density structure 1000 may be part of a vertical LED structure in which part of the control circuit of the structure is formed on the backplane substrate 1002, and another part of the control circuit (not shown) is positioned on the side of the LED structure opposite the backplane substrate 1002. The LED substrate 1004 may include a stack of LED material layers formed on the substrate layer 1016. The LED material layers may include a gallium-nitrogen-containing layer 1014, a transparent conductive layer 1018, a mirror layer 1020, and a bonding layer 1022. The LED substrate 1004 may also include a pixel isolation structure 1024 formed in a direction perpendicular to the other layers of the LED substrate 1004. In embodiments, the pixel isolation structure 1024 may be made of a reflective and conductive material (e.g., a metal) and may be surrounded by an electrically insulating pixel isolation passivation layer 1026 to prevent the pixel isolation structure from short-circuiting the LED structure formed on the gallium-nitrogen-containing layer 1014. In additional embodiments, the LED substrate 1004 may include a mirror layer 1020 and a dielectric layer 1028 in contact with the pixel isolation structure 1024. In the embodiment shown in Figure 10A, the LED structure and the pixel isolation structure are already formed on the LED material layer before the backplane substrate 1002 and the LED substrate 1004 are bonded to each other.

[0046]

[0055] In embodiments of this technology, method 500 may further include the steps of patterning an LED structure in step 515, separating subpixels in step 520, and bonding a backplane substrate and an LED substrate to each other in step 525. In embodiments, steps 515, 520, and 525 may be performed in different orders. In some embodiments, the LED structure may be patterned on the LED substrate in step 515 before the backplane substrate and the LED substrate are bonded to each other in step 525. In additional embodiments, the backplane substrate and the LED substrate are bonded to each other in step 525 before the LED structure is patterned on the LED substrate (or LED layer material) in step 515. In further embodiments, the subpixels may be separated to each other in step 520 before or after the LED structure is formed on the LED substrate in step 515, and before or after the backplane substrate and the LED substrate are bonded to each other in step 525.

[0047]

[0056] Figure 6B shows an embodiment in which the backplane substrate 602 and the LED substrate 604 are bonded to each other before the LED structure is patterned on the LED substrate or before the pixel isolation structure is formed. In the illustrated embodiment, when the backplane substrate 602 and the LED substrate 604 are bonded to each other, a first contact 608 is formed through the passivation layer 612, and a conductive bonding surface is formed between the first contact and the bonding layer 622. After the substrates 602 and 604 are bonded to each other, the LED structure is patterned on the combined substrates as shown in Figures 6C and 6D. Figure 6C shows a conductive via 624 formed between a second contact 610 and the surface of the gallium-nitrogen-containing layer 614 opposite to the surface electrically in contact with the first contact 608. In additional embodiments, the first contact 608 may be electrically in contact with a P-pad contact (not shown) of the gallium-nitrogen-containing layer 614, and the second contact 610 may be electrically in contact with an N-pad contact (not shown) of the layer 614. In further embodiments, an electrically insulating passivation layer 626 may be in contact with the via 624 to prevent an electrical short circuit between the p-doped and n-doped regions of the gallium-nitrogen-containing layer 614. Figure 6D illustrates the LED structure after patterning on a backplane substrate 602. In the illustrated embodiment, another electrically insulating passivation layer 628 is formed around the LED structure in preparation for the formation of the pixel separation process.

[0048]

[0057] Figure 6E shows a pixel isolation structure formed around a previously formed LED structure. In the illustrated embodiment, the pixel isolation structure includes a mirror layer 630 and pixel isolation pillars 632. The mirror layer 630 may be operable to reflect light emitted from the gallium-nitrogen-containing layer 614 toward a quantum dot layer (not shown) subsequently formed above the LED structure between the pixel mirror layer and the pixel isolation pillars 632. In a further embodiment, a portion of the mirror layer 630 formed above the LED passivation layer 628 can be removed to allow light emitted by the gallium-nitrogen-containing layer 614 to pass through the space holding the quantum dot layer. The LED passivation layer 628 is designed to have high transmittance of emitted light.

[0049]

[0058] Figure 7B also shows the backplane substrate 702 and LED substrate 704 bonded to each other before the LED structure is patterned onto the LED substrate or when the pixel isolation structure is formed. The first contact 708 is formed through the passivation layer 712 when the backplane substrate 702 and the LED substrate 704 are bonded to each other, forming a conductive junction surface between the contact and the bonding layer 722. After the substrates 702 and 704 are bonded to each other, the LED structure is patterned onto the combined substrates as shown in Figure 7C. In the illustrated embodiment, the LED structure is patterned on the backplane substrate 702 and before the pixel isolation structure is formed, another electrically insulating passivation layer 728 and mirror layer 730 are formed around the LED structure.

[0050]

[0059] Figure 7D shows a pixel isolation structure formed around a previously formed LED structure. In the illustrated embodiment, the pixel isolation structure includes additional portions of a mirror layer 731 and pixel isolation pillars 732. The pixel isolation structure further includes an additional transparent conductive layer 734 formed on the sidewalls of the pixel isolation structure and on the surface of the gallium-nitrogen-containing layer 714. The mirror layer 731 may be operable to reflect light emitted from the gallium-nitrogen-containing layer 714 toward a quantum dot layer (not shown) subsequently formed above the LED structure between the pixel mirror layer and the pixel isolation pillars 732. In further embodiments, portions of the mirror layer 730 and the LED passivation layer 728 can be removed and replaced with the additional transparent conductive layer 734. Light emitted from the gallium-nitrogen-containing layer 714 can pass through the additional transparent conductive layer 734 and enter the space holding the quantum dot layer.

[0051]

[0060] Figures 7E and 7F show another embodiment for patterning an LED structure and separating subpixels according to an embodiment of the present technology. Figure 7E shows a dielectric material 750 deposited and patterned on an LED substrate layer having an LED structure. The patterned dielectric material 750 can form sacrificial pillars on which the pixel separation structure can be formed. In the illustrated embodiment, a passivation layer 752 and pixel separation pillars 754 are deposited and patterned on the patterned dielectric material 750. Figure 7F shows the state after the patterned dielectric material has been removed, with a gallium-nitrogen-containing layer 714 formed at the bottom and openings containing the pixel separation structure formed in the sidewalls (including the passivation layer and pixel separation pillars). In an additional embodiment, another transparent conductive layer 756 may be formed on the gallium-nitrogen-containing layer 714 and the pixel separation structure.

[0052]

[0061] Figure 8B shows an embodiment in which the backplane substrate 802 and LED substrate 804 are bonded to each other after the LED structure has been patterned onto the LED substrate. In the illustrated embodiment, when the backplane substrate 802 and LED substrate 804 are bonded to each other, a contact 808 is formed through the passivation layer 812, forming a conductive junction surface between the contact and the bonding layer 822. In another embodiment, the substrate layer is removed to expose the gallium-nitrogen-containing layer 814. In an additional embodiment, a pixel isolation structure (not shown) may be formed along the sidewall of the LED structure, including the sidewalls of the bonding layer 822, the mirror layer 820, and the passivation layer 819. In yet another embodiment, the pixel isolation structure may include an electrically insulating passivation layer and columns of pixel isolation material such as a metal or dielectric material. In yet another embodiment, the pixel isolation structure may include an additional mirror layer formed on the internal sidewall of the structure to reflect light toward a quantum dot layer (not shown) positioned in an opening formed by the pixel isolation structure and the LED structure.

[0053]

[0062] Figure 9B shows an embodiment in which the backplane substrate 902 and the LED substrate 904 are bonded to each other after at least a portion of the LED structure and pixel isolation structure have been patterned onto the LED substrate. In the illustrated embodiment, when the backplane substrate 902 and the LED substrate 904 are bonded to each other, a contact 908 is formed through the passivation layer 912, forming a conductive bonding surface between the contact and the bonding layer 922. In the embodiment, the substrate layer is removed to expose the gallium-nitrogen-containing layer 914 and the top of the pixel isolation structure 924. In the embodiment, an additional transparent conductive layer 928 may be formed on the gallium-nitrogen-containing layer 914 and the pixel isolation structure 924.

[0054]

[0063] Figure 10B shows another embodiment in which the backplane substrate 1002 and the LED substrate 1004 are bonded to each other after at least a portion of the LED structure and pixel isolation structure have been patterned onto the LED substrate. In the illustrated embodiment, conductive interconnects 1030 are formed on the dielectric layer 1028 to form conductive paths between the contacts 1008 of the backplane layer 1006 and the mirror layer 1020, transparent conductive layer 1018, and gallium-nitrogen-containing layer 1014 of the LED structure. In the embodiment, the substrate layer 1016 is removed to expose the top of the gallium-nitrogen-containing layer 1014 and the pixel isolation structure 1024. In the embodiment, an additional transparent conductive layer 1032 may be formed on the gallium-nitrogen-containing layer 1014 and the pixel isolation structure 1024.

[0055]

[0064] Returning to Figure 5, Method 500 may also further include, in step 530, the formation of quantum dot layers in the separated LED subpixel structure. In embodiments, the formation of quantum dot layers may include a series of steps for forming quantum dot layers operable to emit light characterized by a specific peak intensity wavelength in one of the subpixels of each LED pixel in the array of LED pixels. In further embodiments, the series of steps may include forming a red quantum dot layer in one of the subpixels of each LED pixel, then forming a green quantum dot layer in another subpixel, then forming a blue quantum dot layer in yet another subpixel. After the formation of the blue quantum dot, each LED pixel in the array of LED pixels contains red, green, and blue subpixels.

[0056]

[0065] In additional embodiments, the formation of a quantum dot layer capable of emitting visible light of a specific color (e.g., red, green, 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 and curing it by irradiating that subpixel with the photocurable fluid, and removing the uncured photocurable fluid from the other unactivated subpixels. These formation steps can be repeated for subpixels that emit light of each color in the array of LED pixels. In embodiments, the formation steps self-align the quantum dot layer with the activated subpixels of the LED pixels across the entire array of LED pixels. A precise alignment step is not required to form the quantum dot layer on the appropriate group of subpixels. Self-alignment of the quantum dot layer becomes increasingly beneficial as the subpixel size decreases and the pixel density increases.

[0057]

[0066] In some embodiments, the photocurable fluid may comprise one or more crosslinking compounds, a photoinitiator, and a color converter. In additional embodiments, the crosslinking compound may comprise a monomer that forms a polymer when cured. In further embodiments, the monomer may comprise acrylate monomers, methacrylate monomers, and acrylamide monomers. In even further embodiments, the crosslinking compound may comprise a negative photoresist material such as SU-8 photoresist. In even further embodiments, the photoinitiator may comprise 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 further embodiments, the color converter may include quantum dot materials that can absorb shorter wavelength (i.e., higher energy) light from the LED structure and emit longer wavelength light corresponding to the color of the light emitted by the subpixels. In embodiments, these quantum dot materials may include nanoparticles made of one or more types of inorganic semiconductor materials such as indium phosphide, zinc selenide, zinc sulfide, silicon, silicates, graphene, and doped inorganic oxides, among other semiconductor materials.

[0058]

[0067] Method 500 may also include testing subpixels after the formation of the quantum dot layer in step 535. In some embodiments, subpixels may be tested after the formation of each color of the quantum dot layer. In additional embodiments, subpixels may be tested after all quantum dot layers have been formed. In further embodiments, the testing step may include activating all subpixels and detecting which subpixels are defective. In embodiments, these defects may include, among other types of defects, subpixels that do not produce any light, subpixels that do not produce light at a certain intensity, and subpixels that do not produce light at a target intensity (e.g., subpixels that are too dim or too bright).

[0059]

[0068] Method 500 may further include replacing defective subpixels in step 540. In embodiments, the replacement may include forming a replacement quantum dot layer on subpixels that lack a quantum dot layer (blank) in the LED pixel. The replacement quantum dot layer is operable to emit light of the same wavelength as the defective subpixel to be deactivated. The replacement step 540 can significantly reduce the number of defective LED pixels in a high-pixel-density structure. In embodiments, the percentage of defective subpixels in a high-pixel-density structure may be reduced to about 75% or more, about 85% or more, about 95% or more, about 99% or more, or even higher. In additional embodiments, after the replacement step 540, the number of defective LED pixels in the high-pixel-density structure may be approximately 1 or less per 1,000 pixels, approximately 1 or less per 5,000 pixels, approximately 1 or less per 10,000 pixels, approximately 1 or less per 25,000 pixels, approximately 1 or less per 50,000 pixels, approximately 1 or less per 75,000 pixels, approximately 1 or less per 100,000 pixels, approximately 1 or less per 250,000 pixels, approximately 1 or less per 500,000 pixels, approximately 1 or less per 750,000 pixels, approximately 1 or less per 1,000,000 pixels, or less.

[0060]

[0069] Method 500 may further include, in step 545, forming a UV barrier layer on the subpixels of the LED pixels. In embodiments, the UV barrier layer may be formed on the quantum dot layer in subpixels containing the quantum dot layer, and on the LED structure in subpixels without the quantum dot layer. In further embodiments, the UV barrier layer may be a dielectric layer that transmits visible light emitted by the quantum dot layer and absorbs UV light generated by the LED structure of the subpixel. In embodiments, the dielectric layer may be a silicon oxide layer deposited by chemical vapor deposition or physical vapor deposition. In additional embodiments, the UV barrier layer may be made of an organic polymer such as polyacrylate, polymethyl methacrylate, and a copolymer of polyacrylate and polymethyl methacrylate. In yet another embodiment, the UV barrier layer may be made of a commercially available material such as Tinuvin CarboProtect from BASF and the Eversorb series from Everlight. In embodiments, the UV barrier layer can reduce the proportion of UV light in the total light emitted from the high-pixel-density structure to about 5% or less, about 2.5% or less, about 1% or less, about 0.5% or less, about 0.1% or less, about 0.05% or less, about 0.01% or less, or less. In additional embodiments, the UV barrier layer can transmit visible light from the quantum dot layer at about 50% or more, about 75% or more, about 85% or more, about 90% or more, about 95% or more, about 99% or more, or more.

[0061]

[0070] Method 500 may also further include, in step 550, forming microlenses on one or more subpixels of the LED pixels in the array of LED pixels. In embodiments, microlenses may be formed on two or more subpixels, three or more subpixels, and all subpixels in each LED pixel. In additional embodiments, the microlenses may be convex lenses, concave lenses, Fresnel lenses, among other lens shapes. In further embodiments, the microlenses may be made of an inorganic or organic material that can transmit visible light emitted from the subpixels. In additional embodiments, the microlenses may be made of polymers such as polydimethylsiloxane, polyacrylate, polymethyl methacrylate, polybutyl methacrylate, polystyrene, and poly(benzyl methacrylate), among other polymers. In further embodiments, the microlenses may be made of inorganic materials such as silica, zinc oxide, and aluminum oxide, among other inorganic materials. Among other applications, microlenses improve image quality for specific uses such as VR headsets and AR glasses by bending and focusing light emitted by high-pixel-density structures.

[0062]

[0071] Embodiments of the Method, such as Method 500, may be used to manufacture high-pixel-density structures having pixel densities of approximately 1000 ppi or more, approximately 1250 ppi or more, approximately 1500 ppi or more, approximately 1750 ppi or more, approximately 2000 ppi or more, approximately 2500 ppi or more, approximately 2750 ppi or more, approximately 3000 ppi or more, or higher. In embodiments, the Method includes reducing crosstalk between adjacent subpixels by forming and separating subpixels. In additional embodiments, the Method enables the manufacture of high-pixel-density structures with fewer defective pixels by testing subpixels and replacing defective subpixels by forming replacement quantum dot layers on blank subpixels that previously lacked quantum dot layers. The Method enables the manufacture of high-pixel-density structures that can be incorporated into display devices such as virtual reality headsets and augmented reality glasses that require both high pixel density, fast response time, and high-quality image display capabilities.

[0063]

[0072] The foregoing description includes numerous details to provide an understanding of various embodiments of the Technology for illustrative purposes. However, it will be apparent to those skilled in the art that certain embodiments may be carried out without some of these details, or with additional details.

[0064]

[0073] While several embodiments have been disclosed, it will be recognized by those skilled in the art that various modifications, alternative structures, and equivalents can be used without departing from the spirit of the embodiments. Furthermore, to avoid unnecessarily obscuring the Art, some well-known processes and elements have not been described. Therefore, the above details should not be construed as limiting the scope of the Art. Moreover, while methods or processes may be described sequentially or stepwise, it should be understood that steps may be performed simultaneously or in an order different from that listed.

[0065]

[0074] Where a range of values ​​is provided, unless the context explicitly indicates otherwise, each intervening value between the upper and lower limits of that range, down to the smallest unit of the lower limit, is also specifically disclosed. This includes any narrower range between any unlisted intervening value of any listed value or range and any other listed value or intervening value of that range. The upper and lower limits of these smaller ranges may be independently included in or excluded from the range, and each range that includes one or both limits, or neither, is also included in this technology according to any specifically excluded limits in the listed range. Where a listed range includes one or both limits, ranges that exclude one or both of those included limits are also included.

[0066]

[0075] As used herein and in the appended claims, the singular forms "a," "an," and "the" include multiple references unless the context explicitly indicates otherwise. For example, a reference to "a pixel" includes multiple such pixels, and a reference to "the layer" includes one or more layers and their equivalents that are well known to those skilled in the art.

[0067]

[0076] Furthermore, as used herein and in the following claims, the terms “comprise,” “comprising,” “contain,” “containing,” “include,” and “including” specify the presence of the described feature, integer, component, or process, but do not preclude the presence or addition of one or more other features, integers, components, processes, operations, or groups.

Claims

1. A semiconductor processing method, Forming a backplane substrate and an LED substrate, The method involves bonding the backplane substrate to the LED substrate, wherein the bonded substrate includes an array of LED pixels, each of the LED pixels includes a group of subpixels separated on the backplane substrate by a pixel separation structure, and the pixel separation structure forms subpixel recesses in the separated subpixels. Filling the subpixel recess with a quantum dot layer in at least one of the separated subpixels of each LED pixel, wherein at least one of the subpixel recesses of each LED pixel is left without quantum dot material, exposing the subpixel without the quantum dot layer. To repair an LED pixel having at least one defect by filling the subpixel recess with a replacement quantum dot layer in a subpixel lacking a quantum dot layer of that LED pixel having at least one defect, After repairing the at least one defective LED pixel, a UV barrier layer is formed on the array of LED pixels. A method that includes this.

2. The semiconductor processing method according to claim 1, wherein each LED subpixel includes a gallium-nitrogen-containing light-emitting diode structure capable of emitting a first wavelength light characterized by a wavelength of 400 nm or less.

3. The semiconductor processing method according to claim 2, wherein the quantum dot layer is operable to absorb the first wavelength light emitted from the gallium-nitrogen-containing light-emitting diode structure and to emit a second wavelength light characterized by a wavelength longer than the first wavelength light.

4. The semiconductor processing method according to claim 1, wherein the substitution quantum dot layer is operable to emit light of the same wavelength as the quantum dot layer formed on the non-operating subpixel of the defective LED pixel.

5. The semiconductor processing method according to claim 1, wherein the unrepaired LED pixels include subpixels without a quantum dot layer after the UV barrier layer has been formed on the array of LED pixels.

6. The semiconductor processing method according to claim 1, wherein the array of LED pixels has a pixel density of 1,000 pixels or more per inch.

7. The semiconductor processing method according to claim 1, wherein the longest dimension of each of the separated subpixels is 10 μm or less.

8. The semiconductor processing method according to claim 1, further comprising forming a microlens on at least one of the subpixels of each of the LED pixels.

9. A semiconductor processing method, Forming a backplane substrate and an LED substrate, The method of bonding the backplane substrate to the LED substrate, wherein the bonded substrate includes an array of LED pixels, each of the LED pixels includes at least four subpixels separated on the backplane substrate by a pixel separation structure, and the pixel separation structure forms subpixel recesses in the separated subpixels, Filling the subpixel recesses of at least three of the isolated subpixels of each of the LED pixels with a quantum dot layer, wherein at least one of the subpixel recesses of each of the LED pixels is left without a quantum dot layer, exposing the subpixel without a quantum dot layer, and each of the quantum dot layers is operable to emit visible light of a different wavelength than the other quantum dot layers of the LED pixel, The method involves forming a UV barrier layer on the array of LED pixels, wherein, after forming the UV barrier layer, at least a portion of the LED pixels include at least one subpixel without a quantum dot layer. A method that includes this.

10. The semiconductor processing method according to claim 9, wherein a pixel separation structure is formed on the LED substrate before it is bonded to the backplane substrate.

11. The semiconductor processing method according to claim 9, wherein a pixel separation structure is formed on the bonded substrate after the LED substrate is bonded to the backplane substrate.

12. The semiconductor processing method according to claim 9, wherein an LED structure is formed on the LED substrate before it is bonded to the backplane substrate.

13. The semiconductor processing method according to claim 9, wherein an LED structure is formed on the bonded substrate after the LED substrate is bonded to the backplane substrate.

14. The semiconductor processing method according to claim 9, wherein an additional backplane substrate is bonded to the bonded substrate on the exposed surface of the LED substrate.

Images