Illumination apparatus comprising passive optical nanostructures

Abstract

To manufacture appropriate passive optical structures which work well with light-emitting elements having the size of micro-LEDs.SOLUTION: An illumination apparatus is manufactured by selectively removing passive optical nanostructures from a monolithic array of light-emitting elements while preserving their relative spatial positions. The nanostructures are selected such that, in at least one direction, for each pair of at least one pair of the selectively removed passive optical nanostructures, there is at least one nanostructure that is not selected and that was positioned in the monolithic array between the pair of selectively removed passive optical nanostructures in the at least one direction, forming a non-monolithic array of passive optical nanostructures with the selectively removed passive optical nanostructures while preserving their relative spatial positions, and aligning each of the passive optical nanostructures of the non-monolithic array with a respective light-emitting element of the non-monolithic array of light-emitting elements.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present disclosure generally relates to a method of manufacturing an illumination device including a display device including a passive optical nanostructure and a change in light output from an illumination device. The illumination device can be used for applications such as ambient illumination or for an image display.

Background Art

[0002] In illumination devices, passive optical structures (e.g., polarizing elements, color conversion elements, etc.) are often incorporated to control the way the illumination device provides light. One type of illumination device is an illumination device that uses micro LEDs as light emitting elements. It tends to be difficult to manufacture a suitable passive optical structure that functions well with light emitting elements of the size of micro LEDs.

Summary of the Invention

[0003] According to the present disclosure, a method of manufacturing an irradiation device is provided, the method comprising: forming a non-monolithic array of light-emitting elements; forming a first monolithic array of first passive optical nanostructures; selectively removing a plurality of the first passive optical nanostructures from the first monolithic array in a manner that maintains the relative spatial positions of the selectively removed first passive optical nanostructures, wherein the plurality of first passive optical nanostructures to be selectively removed from the first monolithic array are selected such that, in at least one direction, for at least one pair of the selectively removed first passive optical nanostructures in the at least one direction, there is at least one respective non-selected first passive optical nanostructure disposed in the first monolithic array between each pair of the selectively removed first passive optical nanostructures in the at least one direction; forming a first non-monolithic array of first passive optical nanostructures having the selectively removed first passive optical nanostructures in a manner that maintains the relative spatial positions of the selectively removed first passive optical nanostructures; and aligning each of the first passive optical nanostructures of the first non-monolithic array with a respective light-emitting element of the non-monolithic array of light-emitting elements.

[0004] Advantageously, at least some of the light-emitting elements of the array of light-emitting elements may comprise aligned passive optical nanostructures. In a very thin stack, the optical function may be improved. Alignment can be achieved for many light-emitting elements and passive optical elements in a few steps, reducing cost and complexity. The size of the monolithic array may be smaller than the size of the irradiation device. The cost of equipment for providing the monolithic wafer can be reduced. The area of the monolithic wafer between the aligned passive optical elements can be used for further alignment steps, improving yield and reducing cost.

[0005] The non-monolithic array of light-emitting elements can be formed on a support substrate. Advantageously, light-emitting elements can be provided to maintain dimensional stability and provide control electrodes and electronic devices at low cost.

[0006] The method may further include sandwiching a non-monolithic array of light-emitting elements and a first non-monolithic array of first passive optical nanostructures between a support substrate and another substrate facing the support substrate, such that each first passive optical nanostructure is aligned with a respective light-emitting element. Advantageously, the array of passive optical nanostructures and the array of light-emitting elements may each have high dimensional stability.

[0007] The method may further include transferring the first non-monolithic array of first passive optical nanostructures onto another substrate before sandwiching. Advantageously, alignment can be achieved for many light-emitting elements and passive optical elements in a small number of steps, reducing cost and complexity.

[0008] The method may further include transferring each of the first passive optical nanostructures of the first non-monolithic array to a respective one of the light-emitting elements of the non-monolithic array of light-emitting elements before sandwiching. Alignment of the light-emitting elements and the passive optical nanostructures can be maintained with respect to substrates having different thermal expansions. The distance between the light-emitting elements and the passive optical nanostructures can be narrowed, enhancing the light coupling efficiency from the light-emitting elements to the passive optical nanostructures.

[0009] The method may further include stacking each of the first passive optical nanostructures of the first non-monolithic array of passive optical nanostructures on a respective light-emitting element of the non-monolithic array of light-emitting elements. Advantageously, the nanostructures can be arranged to receive light from the light-emitting elements.

[0010] The method may further include measuring the optical or electrical properties of the first passive optical nanostructures for at least two regions of the first monolithic array, classifying the measurement of the optical or electrical properties of each region as above or below a predetermined measurement threshold of the optical or electrical properties, and selectively removing only the first passive optical nanostructures from the regions where the measurement of the optical or electrical properties is above or alternatively below the predetermined measurement threshold. Advantageously, the performance of each transferred passive optical nanostructure exceeds a predetermined threshold. The uniformity of the device is improved and the rework cost is reduced. Only the regions of the monolithic wafer containing suitable passive optical elements can be used so that the tolerance of the uniformity of the monolithic wafer is relaxed. The process yield is improved and the cost of the device is reduced. The uniformity of the output of the irradiation device can be enhanced.

[0011] The method may further include providing a substrate that is transparent to light in an electromagnetic wavelength band, forming a release layer on the first substrate, the release layer being configured to at least partially separate from the substrate when exposed to light in the electromagnetic wavelength band, and forming a first monolithic array of the first passive optical nanostructures on the release layer. Advantageously, a substrate suitable for optical addressing during transfer can be provided.

[0012] Selectively removing a plurality of the first passive optical nanostructures may include irradiating the regions of the release layer in which the selected plurality of the first passive optical nanostructures are formed with light in the electromagnetic wavelength band through the substrate, thereby at least partially separating the selected plurality of the first passive optical nanostructures from the substrate. A controllable optical irradiation system can be provided to select which passive optical nanostructures to separate. Advantageously controllable selection of the transferred passive optical nanostructures can be achieved.

[0013] Irradiation can at least partially separate a selected plurality of first passive optical nanostructures from the remainder of the first monolithic array of first passive optical nanostructures. In the removal transfer step, only the desired elements to be removed are separated. The advantageously transferred passive optical nanostructures can have high uniformity. The cost of the transferred passive optical nanostructures is reduced and the yield is improved.

[0014] The selected plurality of first passive optical nanostructures can be at least partially separated from the remainder of the first monolithic array of first passive optical nanostructures by etching, scribing, or ablation. Advantageously, the passive optical nanostructures can be provided with a suitably formed shape and edge quality.

[0015] Irradiation can include a plurality of shaped laser beams. Advantageously, a plurality of passive optical nanostructures can be extracted with high processing speed, accuracy, and efficiency. The cost may be reduced.

[0016] The electromagnetic wavelength band can be the ultraviolet wavelength band. The bonding of the release layer can be advantageously broken without damaging the passive optical nanostructures.

[0017] Irradiation can dissociate the material of the release layer to form a gas. Light in the electromagnetic wavelength band may dissociate the layer of material forming the first passive optical nanostructures. Uniform delamination of the passive optical nanostructures can be achieved, advantageously enhancing the reliability of extraction and reducing costs.

[0018] The method may include transferring a plurality of selectively removed first passive optical nanostructures to a transfer member, and transferring each of the plurality of selectively removed first passive optical nanostructures from the transfer member to respective light-emitting elements. Advantageously, damage to the array of light-emitting elements during the transfer step may be reduced and the yield may be increased. The transfer member may have a different rigidity from the support substrate of the monolithic array of first passive optical nanostructures and the respective light-emitting elements. The transfer member may comprise a material for achieving optimization of the alignment between the light-emitting element and the respective passive optical elements.

[0019] The method is forming a monolithic array of passive optical nanostructures on a first substrate, the first substrate being opaque to light in an electromagnetic wavelength band, and transferring the passive optical nanostructures of the monolithic array onto a second substrate, the second substrate being transparent to light in the electromagnetic wavelength band, and irradiating a plurality of first passive optical nanostructures through the second substrate with light in the electromagnetic wavelength band, thereby at least partially separating the plurality of passive optical nanostructures from the second substrate. A substrate suitable for forming high-performance passive optical nanostructures can be provided, and a separate substrate suitable for selective transfer can be provided. The growth or patterning and transfer performance of the passive optical nanostructures can be adjusted individually to improve the performance of the passive optical nanostructures. The yield can be improved and the cost can be reduced.

[0020] Selectively removing a plurality of first passive optical nanostructures may include adhering the plurality of first passive optical nanostructures to a first adhesive substrate in a manner that maintains the relative spatial positions of the first passive optical nanostructures. The method may further include transferring the plurality of removed first passive optical nanostructures from the first adhesive substrate to a second adhesive substrate in a manner that maintains the relative spatial positions of the selectively removed light-emitting elements, and transferring the first passive optical nanostructures from the second adhesive substrate to a support substrate in a manner that maintains the relative spatial positions of the selectively removed light-emitting elements. Advantageously, uniform alignment between the passive optical nanostructures and the light-emitting elements can be maintained during the transfer and alignment steps.

[0021] Each of the first passive optical nanostructures may include a first surface and a second surface opposite the first surface, and the first passive optical nanostructures are adhered to a first adhesive substrate such that their first surfaces are adhered to the first adhesive substrate and their second surfaces are exposed. The first passive optical nanostructures may be transferred to a second adhesive substrate such that their second surfaces contact the second adhesive substrate and their first surfaces are exposed. The first passive optical nanostructures may be transferred to a support substrate such that their first surfaces contact the support substrate and their second surfaces are exposed. The adhesive force between the first passive optical nanostructures and the second adhesive substrate may be greater than the adhesive force between the first passive optical nanostructures and the first adhesive substrate. The passive optical nanostructures may be provided with an optical input side configured to receive light from respective aligned light-emitting elements. The adhesive force between the first passive optical nanostructures and the support substrate may be greater than the adhesive force between the first passive optical nanostructures and the second adhesive substrate. Advantageously, there is a possibility of improving the optical performance.

[0022] The support substrate may be a planar substrate. Advantageously, a uniform light output can be achieved. The substrate may be suitable for handling in semiconductor processing equipment. The substrate may be flexible.

[0023] Each of the light-emitting elements may be a micro-LED including a maximum dimension of up to 300 micrometers, preferably up to 200 micrometers, and most preferably up to 100 micrometers. Advantageously, a high-resolution array can be provided.

[0024] Each of the first passive optical nanostructures can have a maximum dimension of up to 400 micrometers, preferably up to 250 micrometers, and most preferably up to 150 micrometers. The maximum dimension of each of the first passive optical nanostructures can be greater than or equal to the maximum dimension of the emission region of the light-emitting element aligned with that first passive optical nanostructure. Advantageously, light from the light-emitting element can be input into the passive optical nanostructure. The range of the passive optical nanostructure can be reduced. Crosstalk between adjacent elements can be reduced.

[0025] The first passive optical nanostructure includes one or more sub-features having a maximum dimension of up to 5 micrometers, preferably up to 1 micrometer, and most preferably up to 0.5 micrometers. Advantageously, diffusive artifacts can be reduced or eliminated.

[0026] The first passive optical nanostructure includes any one of the types of wire grid polarizer, shape birefringent retarder, quantum dot or quantum rod color conversion structure, distributed Bragg reflector, metamaterial, dichroic stack, hologram, moth-eye structure, nanoblack material, nanocolimator, air gap surrounding a nanocolumn, photonic crystal.

[0027] The first passive optical nanostructure can be a wire grid polarizer. Advantageously, the output of the light-emitting element can be polarized in a polarization state having a first electric vector transmission direction. Light in an orthogonal polarization state can be scattered within the light-emitting element and / or other passive optical nanostructures and recycled as light having the first polarization state. Advantageously, the efficiency may be improved. Such a device can be used to provide highly efficient illumination to a display equipped with an input polarizer such as a liquid crystal display.

[0028] At least one of the wire grid polarizers can be aligned with each light-emitting element in a first orientation, and at least one other wire grid polarizer can be aligned with each light-emitting element in a second orientation, the second orientation being orthogonal to the first orientation. Advantageously, a stereoscopic display can be provided.

[0029] The first passive optical nanostructure can include a shape birefringent retarder. Advantageously, optical retardance can be achieved to provide a change in the polarization output. In a polarization output device, the recycling efficiency may be improved. Circular output polarization can be provided to a stereoscopic display to provide head tilting to a user using circular analyzer eyewear.

[0030] The first passive optical nanostructure can include a distributed Bragg reflector. Advantageously, the spectral output of an illumination device can be changed.

[0031] The first passive optical nanostructure can include a metamaterial. Advantageously, the refractive index characteristics of an illumination device can be changed.

[0032] The first passive optical nanostructure can include a dichroic stack. Advantageously, the spectral output characteristics of an illumination device can be changed.

[0033] The first passive optical nanostructure can include a hologram. Advantageously, the directivity output characteristics of an illumination device can be changed.

[0034] The first passive optical nanostructure can include a moth-eye structure. The first passive optical nanostructure can include a nanoblack material. Advantageously, the reflectivity of an illumination device can be reduced and the contrast can be improved.

[0035] The first passive optical nanostructure can include a nanocollimator. Advantageously, the directivity of the light output can be changed. A privacy illumination device can be provided.

[0036] The first passive optical nanostructure may include an air gap surrounding the nanocolumns. Advantageously, the illumination device can be coupled to another substrate to enhance dimensional stability. The output can be coupled to the optical device within the critical angle, enhancing the coupling efficiency and reducing stray light.

[0037] The first passive optical nanostructure may include a photonic crystal. Advantageously, the spectrum and / or the directional output can be modified to improve the functionality.

[0038] The color conversion structure may be photoluminescence. The first passive optical nanostructure may be a quantum dot or quantum rod color conversion structure. Advantageously, a high color conversion efficiency can be achieved. The spectral bandwidth can be controlled.

[0039] At least one of the light-emitting elements of the non-monolithic array of light-emitting elements may not have a quantum dot or quantum rod color conversion structure aligned therewith. Advantageously, the output efficiency increases in at least one wavelength band.

[0040] The method is a method of forming a second monolithic array of second passive optical nanostructures and selectively removing a plurality of second passive optical nanostructures from the second monolithic array while maintaining the relative spatial positions of the selectively removed second passive optical nanostructures, wherein a plurality of second passive optical nanostructures to be selectively removed from the second monolithic array are selected, and as a result, in at least one direction, for at least one pair of selectively removed second passive optical nanostructures in at least one direction, for each pair, there is at least one respective non-selected second passive optical nanostructure arranged in the second monolithic array between the pair of selectively removed second passive optical nanostructures in at least one direction, the selectively removing, and a method of maintaining the relative spatial positions of the selectively removed second passive optical nanostructures, forming a second non-monolithic array of second passive optical nanostructures having the selectively removed second passive optical nanostructures, and aligning each of the second passive optical nanostructures of the second non-monolithic array of second passive optical nanostructures with each of the light-emitting elements of the non-monolithic array of light-emitting elements. Advantageously, further modification and alignment of the light output of the light-emitting elements can be achieved.

[0041] The first passive optical nanostructure can be a different type of passive optical nanostructure from the second passive optical nanostructure. The first monolithic array of first passive optical nanostructures can be formed separately from the second monolithic array of second passive optical nanostructures. The method can further include stacking each of the second passive optical nanostructures of the second non-monolithic array of passive optical nanostructures on either the respective light-emitting element or the respective first passive optical nanostructure. Advantageously, multiple optical modifications can be achieved with a very thin optical thickness and low cost.

[0042] At least one of the light-emitting elements having the first passive optical nanostructure aligned therewith does not have the second passive optical nanostructure aligned therewith, and / or at least one of the light-emitting elements having the second passive optical nanostructure aligned therewith may not have the first passive optical nanostructure aligned therewith. Advantageously, the output of the entire array of light-emitting elements can be modified to provide different performances, such as color, polarization state, and emission cone solid angle, for different light-emitting elements.

[0043] A non-monolithic array of light-emitting elements is to selectively remove a plurality of light-emitting elements from a monolithic array in such a way as to form a monolithic array of light-emitting elements and maintain the relative spatial positions of the selectively removed light-emitting elements, wherein a plurality of light-emitting elements selectively removed from the first monolithic array are selected, and as a result, in at least one direction, for at least one pair of the selectively removed light-emitting elements in at least one direction, for each pair, there is at least one non-selected light-emitting element arranged in the first monolithic array between the pair of the selectively removed light-emitting elements in at least one direction, and to form a non-monolithic array of light-emitting elements having the selectively removed light-emitting elements in a way that maintains the relative spatial positions of the selectively removed light-emitting elements. Advantageously, a low-cost array of sparsely separated light-emitting elements can be provided at low cost and with high efficiency.

[0044] The method may further include forming an irradiation device having a first non-monolithic array of aligned first passive optical nanostructures and a non-monolithic array of light-emitting elements. Advantageously, the optical function of the irradiation device is greater than that achievable by the light-emitting element array alone and has high efficiency and uniformity in a thin structure.

[0045] The method may further include forming a display device including an illumination device. Advantageously, a high-efficiency, low-cost, and thin display may include an optical output arranged to achieve at least a portion of a color display, a stereoscopic display, a privacy display, a low-glare display. The display may be flexible and bendable.

[0046] According to a second aspect of the present disclosure, there is provided an illumination device that may include a non-monolithic array of light-emitting elements and a non-monolithic array of passive optical nanostructures from a monolithic array of passive optical nanostructures, each of the passive optical nanostructures being aligned with a respective light-emitting element of the non-monolithic array of light-emitting elements, the passive optical nanostructures of the non-monolithic array of passive optical nanostructures being arranged with their original positions held relative to each other within the monolithic array, and for at least one pair of passive optical nanostructures of the non-monolithic array in at least one direction, for each respective pair, there is at least one respective passive optical nanostructure in the monolithic array of passive optical nanostructures arranged between the pair of passive optical nanostructures in the at least one direction and not arranged between them in the non-monolithic array of passive optical nanostructures.

[0047] The illumination device may be a backlight for a transmissive spatial light modulator. Advantageously, a privacy backlight can be achieved. The nanostructures can be arranged to convert blue light into multiple spectral bands to provide white light. The backlight may be highly efficient and may be arranged in a thin package. Privacy display illumination may be provided.

[0048] The illumination device may further include a control system arranged to provide image data to the light-emitting elements. The light-emitting elements may be addressable and drivable as pixels. Advantageously, high-dynamic-range operation can be achieved when the illumination device is arranged for use as a backlight.

[0049] According to a third aspect of the present disclosure, a display device including the irradiation device of the second aspect is provided. Advantageously, a very thin thickness can be achieved with high-quality light output and low cost.

[0050] Any aspect of the present disclosure can be applied in any combination.

[0051] Embodiments of the present disclosure can be used in various optical systems. The present embodiments can include or operate with various projectors, projection systems, optical components, displays, microdisplays, computer systems, processors, self-contained projection systems, visual and / or audiovisual systems, and electrical and / or optical devices. Aspects of the present disclosure can be used with substantially any device related to optical and electrical devices, optical systems, presentation systems, or any type of device that can include an optical system. Thus, embodiments of the present disclosure can be used in optical systems, devices used in visual and / or optical presentations, visual peripherals, etc., as well as in a number of computing environments.

[0052] Before proceeding to the details of the disclosed embodiments, it should be understood that the disclosure is not limited to the details of the particular arrangements shown in its application or creation, as other embodiments are possible. Further, aspects of the present disclosure can be described in different combinations and arrangements to define embodiments unique to itself. Also, the terms used herein are for the purpose of description and not for the purpose of limitation.

[0053] These and other advantages and features of the present disclosure will become apparent to those skilled in the art by reading the entire disclosure.

Brief Description of the Drawings

[0054] Embodiments are shown by way of example in the accompanying drawings, and like reference numerals indicate like parts.

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Embodiments for Carrying Out the Invention

[0055] In this specification, unless otherwise modified by the term "packaged", "LED" or "micro-LED" refers to a monolithic wafer, i.e., an unpackaged LED die directly extracted from a semiconductor device. A micro-LED can be formed by an array extraction method in which a plurality of LEDs are removed in parallel from a monolithic epitaxial wafer and can be arranged with a positional tolerance of less than 5 micrometers. This is different from a packaged LED. A packaged LED typically includes a lead frame with solder terminals suitable for a standard surface-mount PCB (printed circuit board) assembly and a plastic or ceramic package. The size of the packaged LED and the limitations of PCB assembly technology mean that it is difficult to assemble a display formed from packaged LEDs with a pixel pitch of less than about 1 mm. The accuracy of components placed by such an assembly machine is typically about plus or minus 30 micrometers. Such sizes and tolerances prevent their application to very high-resolution displays.

[0056] Here, the structures and operations of various directional display devices will be described. In this description, common elements have common reference numerals. Note that any disclosure regarding an element applies to each device provided with the same or corresponding elements. Thus, for the sake of brevity, such disclosures are not repeated.

[0057] FIG. 1 is a schematic diagram showing a part of the structure of an irradiation device 100 according to an embodiment. The irradiation device 100 can be any type of irradiation device, for example, a light emission modulator, a backlight for a transmissive spatial light modulator, or an environmental irradiation device. The irradiation device 100 can form part of a display device such as a computer monitor, a television, or other types of displays.

[0058] The irradiation device 100 includes a planar support substrate 200. The support substrate can be a planar substrate and can be flexible or rigid.

[0059] The LED 110 of the non-monolithic array and a plurality of different types of passive optical nanostructures 300, 400, 500, 600, 800 are arranged on a support substrate 200. The support substrate 200 constitutes a backplane to which the LED 110 is attached. The LED 110 is a micro-LED, that is, an LED with a maximum dimension of up to 300 micrometers (however, preferably, the maximum dimension of each LED 110 is up to 200 micrometers, and most preferably up to 100 micrometers). Each LED 110 of the above dimensions of the LED may include a single light-emitting region, or may include a plurality of light-emitting regions provided by an electrode arrangement, or may include an array of nanoemitters, such as quantum rod emitters.

[0060] Each of the passive optical nanostructures 300, 400, 500, 600, 800 is aligned and stacked with each LED 110 such that each LED 110 has a plurality of different types of passive optical nanostructures stacked thereon. In this way, each type of passive optical nanostructure 300, 400, 500, 600, 800 of the non-monolithic array is formed on the non-monolithic array of LED 110. Each of the passive optical nanostructures 300, 400, 500, 600, 800 has a maximum dimension of up to 400 micrometers (however, preferably, the maximum dimension of each passive optical nanostructure is up to 250 micrometers, and most preferably up to 150 micrometers). The maximum dimension of each of the passive optical nanostructures 300, 400, 500, 600, 800 is greater than or equal to the maximum dimension of the light-emitting region of each LED 110.

[0061] Each of the passive optical nanostructures can include one or more sub-features with a maximum dimension of up to 5 micrometers (however, the maximum dimension of each sub-feature is preferably up to 1 micrometer, and most preferably up to 0.5 micrometer). Examples of sub-features include, but are not limited to, conductive ridges, quantum rods, quantum dots, columnar dielectric structures, elongated dielectric structures, columnar nanoblack structures, and holographic refractive index patterning structures.

[0062] At least one of the LEDs 110 has the same combination of passive optical nanostructures of the stacked type as another one of the LEDs 110. However, not all of the LEDs 110 have the same combination of passive optical nanostructures of the stacked type on them. In other words, at least one of the LEDs 110 has a different combination of passive optical nanostructures stacked on at least another one of the LEDs 110. The passive optical nanostructures 300, 400, 500, 600, 800 act to manipulate and / or change the characteristics of the light output by the LEDs 110, such that the light output by each LED 110 has certain desired characteristics after passing through the passive optical nanostructures stacked on the LED 110. Particularly desirable characteristics vary depending on the combination of types of passive optical nanostructures through which the light passes. For example, as indicated by reference numerals 934BL, 934BR, 934GR, 934GL, 934RL, and 934RR, depending on the combination of types of the passed passive optical nanostructure team, the light has different states of circular polarization (i.e., clockwise or counterclockwise) and different states of color (e.g., red, blue, or green). Some of the LEDs 110 may provide other visible light wavelength bands or may be infrared (IR) or ultraviolet (UV) emitters.

[0063] The different types of passive optical nanostructures 300, 400, 500, 600, 800 include a moth-eye structure 300, a quantum rod structure 400, a wire grid polarizer 500, a shape birefringent retarder 600, and a collimating nanostructure 800, which will be described in detail below with reference to FIG. 2.

[0064] Although not shown, it will be understood that the irradiation device may include other components such as a control system for addressing and driving the LEDs as pixels using image data. Such a control system may include circuits at the edge of the substrate 200 or within the array of LEDs, or a combination of the two.

[0065] FIG. 2 is a schematic diagram showing an example of a combination of different types of passive optical nanostructures that can be stacked on the LED 110 within the irradiation device 100 of FIG. 1. Features of the embodiment of FIG. 2 not discussed in further detail may be assumed to correspond to features with equivalent reference numerals discussed above, including potential variations of the features.

[0066] In this example, in order from the bottom, the stack includes the LED 110, the moth-eye structure 300, the quantum rod structure 400, the collimating nanostructure 800, the wire grid polarizer 500, and the shape birefringent retarder 600. The LED 110 is configured to emit light 922 (e.g., non-polarized Lambertian blue light) toward the moth-eye structure 300.

[0067] The moth-eye structure 300 is configured to receive the light 922 emitted by the LED 110. The moth-eye structure provides a refractive index gradient at the output of the LED, advantageously improving the extraction of light from the LED 110.

[0068] The moth-eye structure 300 is configured to output light 924 toward the quantum rod structure 400. The quantum rod structure 400 is configured to receive the light 924 from the moth-eye structure 300 and convert the color of the light 924 (e.g., by a photoluminescence color conversion mechanism). The quantum rod structure 400 is configured to output the color-converted light 926 toward the collimating nanostructure 800. The collimating nanostructure 800 is configured to receive the color-converted light 926 from the quantum rod structure 400 and collimate at least a portion of the color-converted light 926. At least a portion of the light received by the collimating nanostructure 800 is reflected back toward the quantum rod structure 400 and reused, for example, by an optical collimation design that may be a microprism. Advantageously, the efficiency of the light output is improved.

[0069] The collimating nanostructure 800 is configured to output collimated light 930 towards the wire grid polarizer 500. The wire grid polarizer 500 is configured to receive the collimated light 930 from the collimating nanostructure 800 and linearly polarize the light in a specific polarization state. The wire grid polarizer 500 is configured to output linearly polarized light 932 towards the form birefringent retarder 600. The form birefringent retarder 600 is configured to receive the linearly polarized light 932 from the wire grid polarizer 500 and convert the linearly polarized light into circularly polarized light. The state of the circularly polarized light depends on the direction of the linearly polarized light caused by the wire grid polarizer 500. The form birefringent retarder 600 is configured to output circularly polarized light for use by the irradiation device 100 for irradiation.

[0070] It will be understood that the passive optical nanostructures shown by FIGS. 1 and 2 are not the only types envisioned. Other types of passive optical nanostructures such as quantum dot color conversion structures, Fabry-Perot resonator structures including IGZO layers for selective color reflection, distributed Bragg reflectors, metamaterials, dichroic stacks, holograms, nanoblack materials, air gaps surrounding nanocolumns, etc., in addition to or instead of any of those described with reference to FIGS. 1 and 2, a photonic crystal can be stacked on the LED 110.

[0071] As a comparison with this embodiment, the growth of a stack of nanostructure layers directly grown on micro LEDs on a monolithic LED wafer is considered here. The process growth conditions of each nanostructure may not be compatible or may damage the already deposited layers. Furthermore, the growth of each nanostructure results in an excellent device yield. When various nanostructure growth processes are completed, the overall yield loss is the sum of the individual yield losses and can be very low for the irradiation device itself.

[0072] In this embodiment, the growth and fabrication of each nanostructured layer can be optimized individually. Since only good nanostructured elements are transferred, the yield of the entire device is improved and the optical performance is enhanced.

[0073] The transfer from each nanostructured substrate can be parallel, and as a result, many elements can be aligned in a single step. Since alignment at the micron scale is required, this reduction in alignment steps advantageously achieves a substantial cost reduction.

[0074] Furthermore, in the case of an irradiation device using micro-LEDs, since it is difficult to combine micro-LEDs with conventional ones due to the small size of micro-LEDs, a stack of passive optical nanostructures tends to be desirable compared to conventional large-scale optical structures. However, a stack of passive optical nanostructures tends to be difficult to manufacture. For example, the growth of a stack of nanostructures tends to suffer from problems such as overgrowth, lack of sufficient seed substrate surface quality, and low wafer uniformity, resulting in a very low yield. Next, a method for manufacturing a stack of passive optical nanostructures that can avoid and / or address the above problems will be described.

[0075] FIG. 3 is a flowchart showing the steps of a method for manufacturing a passive optical nanostructure for use in an irradiation device such as the irradiation device 100 of FIG. 1.

[0076] In step S1, a single type of passive optical nanostructure of a monolithic array grows on a growth substrate. The passive optical nanostructure may be any suitable type of passive optical nanostructure, including, but not limited to, a wire grid polarizer, a shape birefringent retarder, a quantum dot or quantum rod color conversion structure, a distributed Bragg reflector, a metamaterial, a dichroic stack, a hologram, a moth-eye structure, a nanoblack material, a nanocollimator, an air gap surrounding a nanocolumn, a photonic crystal. The growth substrate can undergo further processing such as etching to define the individual size of the optical nanostructure.

[0077] In step S2, the monolithic array is inspected. For example, the optical or electrical properties of the passive optical nanostructures can be measured for a plurality of different regions of the monolithic array of passive optical nanostructures as part of the inspection. The optical properties include, but are not limited to, reflectivity, transmittance, spectral characteristics, retardance, photoluminescence, and polarization extinction. The electrical properties include, but are not limited to, conductivity.

[0078] The inspection may further identify defective particles, scratches, and the uniformity of the characteristics of the entire monolithic array.

[0079] In step S3, based on the inspection performed in step S2, passive optical nanostructures that meet and / or do not meet a predetermined criterion are identified. More specifically, passive optical nanostructures that exceed a predetermined measurement threshold of optical or electrical properties are classified as meeting the criterion, and passive optical nanostructures that fall below the predetermined measurement threshold of optical or electrical properties are classified as not meeting the criterion, or vice versa. The purpose of the inspection is to identify normal devices before subsequent transfer.

[0080] In step S4, the selection of passive optical nanostructures that meet the criterion is extracted / removed from the monolithic array. The extraction / removal is selective in the sense that one or more passive optical nanostructures that meet the criterion are not selected for extraction / removal. One or more passive optical nanostructures that meet the criterion but are not selected for extraction / removal can be arranged among the passive optical nanostructures selected for extraction / removal. The selected passive optical nanostructures are extracted / removed from the monolithic array in a way that maintains their relative spatial positions. In this way, the selected passive optical nanostructures are extracted / removed such that their relative spacing remains unchanged. The sparse array can be extracted at a pitch that matches LED110. The alignment of the selected nanostructures to LED110 can be provided in a single step.

[0081] In step S5, the removed passive optical nanostructures are transferred to a support substrate. More specifically, each of the removed passive optical nanostructures is transferred to a respective LED on the support substrate. The removed passive optical nanostructures are transferred in a manner that maintains their relative spatial positions. In this way, the relative spatial positions of the passive optical nanostructures within the initial monolithic array are maintained even after the passive optical structures are on the support substrate. This preservation of spatial position tends to enable the passive optical nanostructures to be placed on the support substrate with high precision.

[0082] In step S6, it is determined whether the desired non-monolithic array of passive optical nanostructures is complete. If the desired array is not complete, the method returns to step S4, extracts more passive optical nanostructures that meet the criteria, and transfers them to the support substrate. If the passive optical nanostructures of the desired non-monolithic array are complete, the method returns to step S1 and repeats using different types of passive optical nanostructures.

[0083] Method steps S1 - S6 are continuously repeated with different types of passive optical nanostructures until different types of passive optical nanostructures for all desired non-monolithic arrays are formed and stacked on the support substrate. In this way, a stack of various types of passive optical nanostructures is created for each LED, as shown, for example, in FIGS. 1 and 2. Combinations of the same or different types of passive optical nanostructures can be stacked on different LEDs, and generally, it will be understood that each LED can have any combination of types of passive optical nanostructures stacked in any order as desired.

[0084] FIGS. 4 - 5 are schematic diagrams further showing steps S2 and S3 of the method of FIG. 3. FIG. 4 is a schematic diagram showing an example of region 950 of passive optical nanostructures 938 of a monolithic array 900 of passive optical nanostructures. Features of the embodiments of FIGS. 4 and 5 not discussed in further detail may be assumed to correspond to features with equivalent reference numbers discussed above, including potential variations of the features.

[0085] Figure 4 shows the measured property variations across the entire wafer 900. The passive optical nanostructures 30 are grown or deposited within the monolithic array 900. Variations in process conditions across the entire wafer 900 can provide variations in optical or electrical properties that can be divided into individual performance regions, as shown in Figure 4. Different regions of the wafer may be included in different property groups. For example, all those items within the contour 950 may be within a first target property group, and all items within the region 940 may be outside the target property group. Within each property group 950, the passive optical nanostructures can be divided into performance bins. In an exemplary example, the passive optical nanostructure (PON) can be a reflective wire grid polarizer passive optical nanostructure. The property groups outside the contour 950 may have a polarization extinction ratio of less than 20:1, and the passive optical nanostructure 938 may be rejected and not transferred. Within the contour 950, the elements can be binned by the contour, for example, with extinction ratios of 20:1 to 25:1 and 25:1 to 30:1. Advantageously, the PONs 938 that fall below performance are not transferred, improving the performance of the device.

[0086] As a comparison with this embodiment, in the monolithic transfer method, the entireties of both the active LED wafer and the passive optical nanostructure wafer are lost outside the contour 950. Advantageously, this embodiment achieves cost reduction.

[0087] It may further be desirable not to transfer the passive optical nanostructures in regions of defects and scratches and non-functional passive optical nanostructures.

[0088] Figure 5 is a schematic diagram showing a plurality of passive optical nanostructures of the monolithic array 900. In this case, what is indicated by the square 942 does not meet the standard, which may be, for example, light transmission exceeding a specific threshold. The other passive optical nanostructures 938 meet this standard. Faulty devices are identified and only known good dies are transferred. Advantageously, the yield of the final irradiation device can be improved.

[0089] Figures 6A-6C are schematic diagrams for further explaining step S6 of FIG. 3. More specifically, these figures show the process of completing a non-monolithic array of desired passive optical nanostructures by filling gaps where passive optical nanostructures are desired but not transferred from a monolithic array. The features of the embodiments of FIGS. 6A-6C not discussed in further detail may be assumed to correspond to features with equivalent reference numbers discussed above, including potential variations of the features.

[0090] FIG. 6A shows a support substrate 200 on which an array of qualified optical elements within characteristic group 950 of FIG. 4 and the qualified passive optical nanostructures 938 of FIG. 5 are transferred in a first transfer step. The wafer placement boundary 903A indicates the extent of the monolithic wafer of passive optical nanostructures, and the missing element 951 indicates the position that has not been transferred.

[0091] FIG. 6B shows the transferred passive optical nanostructures 938 in at least one subsequent transfer step from a plurality of wafer placements indicated by wafer placement boundaries 903B, 903C, and 903D. Advantageously, the support substrate 200 is filled with devices.

[0092] FIG. 6C shows the assembled support substrate 200 with a complete set of qualified passive optical nanostructures 938. Advantageously, high uniformity and reliability can be achieved.

[0093] Next, the extraction of the array of passive optical nanostructures 938 will be described.

[0094] Figures 7A-7I are schematic diagrams showing steps S1, S4, and S5 of the method of FIG. 3. The features of the embodiments of FIGS. 7A-7I not discussed in further detail may be assumed to correspond to features with equivalent reference numbers discussed above, including potential variations of the features.

[0095] First, as shown in FIG. 7A, a growth substrate 900 is provided. The growth substrate 900 is transparent to light in a specific electromagnetic wavelength band. The growth substrate 900 can be formed, for example, from sapphire and can be transparent to UV light.

[0096] Next, as shown in FIG. 7B, a release layer 901 is formed on the growth substrate 900. The release layer 901 can be formed from undoped gallium nitride (e.g., U-GaN). The release process can include the use of short laser pulses to facilitate the excision process without causing thermal damage to adjacent materials. Alternatively, another material with photo-release layer properties such as polyimide may be used. Alternatively, the layer can be a release layer that can be removed by etching or heat treatment.

[0097] Next, as shown in FIG. 7C, a monolithic array of passive optical nanostructures 938 is formed (e.g., grown) on the release layer 901.

[0098] Next, as shown in FIG. 7D, a transfer member 902 with an adhesive layer 904 formed thereon is provided.

[0099] Next, as shown in FIG. 7E, the transfer member 902 is adhered to the monolithic array of passive optical nanostructures 938 using the adhesive layer 904. Further, the region 912 of the release layer 901 corresponding to the selected qualified passive optical nanostructures 938 is irradiated through the growth substrate 900 with light in a specific electromagnetic wavelength band to which the growth substrate 900 is transparent. The irradiation can include a plurality of shaped laser beams.

[0100] As shown in FIG. 7F, the irradiation separates the selected passive optical nanostructures 938, together with the portion of the release layer 901 attached to the selected passive optical nanostructures 938, at least partially from the remaining portion of the passive optical nanostructures 938 and the monolithic array of the growth substrate 900. This can be achieved at least in part by irradiation that dissociates the layer of material forming the release layer 901 to form a gas. The selected passive optical nanostructures 938 remain adhered to the transfer member 902 via the adhesive layer 904, whereby they can be removed by lifting them together with the transfer member 902. In addition to irradiation, etching and / or scribing can also be used to assist in separating the selected passive optical nanostructures from the remaining portion of the monolithic array.

[0101] As shown in FIG. 7G, next, the portion of the release layer still attached to the removed passive optical nanostructures 938 is removed, for example, by etching or cleaning.

[0102] Next, as shown in FIGS. 7H and 7I, the removed passive optical nanostructures 938 are transferred from the transfer member 902 to the respective LEDs 110 on the support substrate 200. The transfer can include irradiating the passive optical nanostructures 938 with light 910 to separate them from the carrier substrate, and / or adhering the passive optical nanostructures 938 to the LEDs 110 with an adhesive 906. Alternatively, a thermal process or differential bonding adhesion can be used. Next, the passive optical nanostructures 938 can be washed to remove excess material. In this exemplary embodiment, some of the passive optical nanostructures 938 are shown to be the same size as the LEDs 110, but they can be larger or smaller.

[0103] FIGS. 8A - 8B are schematic diagrams showing an alternative method of growing the passive optical nanostructures 938 as shown in FIGS. 7A - 7C. The features of the embodiments of FIGS. 8A - 8B, which are not discussed in further detail, can be assumed to correspond to the features with the same reference numbers discussed above, including potential variations of the features.

[0104] Instead of growing on a substrate that is transparent to light in the electromagnetic wavelength band, as shown in FIG. 8A, the monolithic array of passive optical nanostructures 938 grows on a substrate 900a that is opaque to light in the electromagnetic wavelength band. Next, as shown in FIG. 8B, the monolithic array of passive optical nanostructures 938 is transferred to a substrate 900b that is transparent to light in the electromagnetic wavelength band. Next, the steps shown in FIGS. 7D-7I can be performed. The transfer can use a release layer (not shown) or a layer on the etched substrate 900a (not shown).

[0105] FIG. 9 is a schematic diagram showing additional steps that can be performed between step 7G and step 7H. Features of the embodiment of FIG. 9 not discussed in further detail may be assumed to correspond to features with equivalent reference numerals discussed above, including potential variations of the features.

[0106] As shown in FIG. 9, the removed passive optical nanostructures 938 are transferred from a transfer member 902 to another transfer member 902a in a manner that maintains the relative spatial position of the selectively removed light-emitting elements. This is achieved by adhering the passive optical nanostructures 938 to the adhesive layer 904a of the other transfer member 902a while the passive optical nanostructures are still adhered to the adhesive layer 904 of the transfer member 902 and pulling the two carrier substrates 902, 902a apart. Since the adhesion force of the adhesive layer 904a to the passive optical nanostructures is greater than the adhesion force of the adhesive layer 904, the passive optical nanostructures separate from the adhesive layer 904 and adhere to the adhesive layer 904a. In this way, the passive optical nanostructures are inverted so that their respective different opposing surfaces are exposed. The strength of the adhesive layer 904 can be changed, for example, by heat and / or UV light.

[0107] Figures 10A to 10E are schematic diagrams showing a moth-eye structure 300 as one type of passive optical nanostructure that can be manufactured according to the above method with reference to Figures 3 to 9. The features of the embodiments of Figures 10A to 10E not discussed in more detail can be assumed to correspond to the features with equivalent reference numerals discussed above, including potential variations of the features.

[0108] As shown in Figure 10A, the moth-eye structure 300 is attached and grown on a base layer 301 over a release layer 901. Figures 10B to 10D show the removal and transfer of the moth-eye structure 300 onto the LED 110 on the support substrate 200 by the above method. Figure 10E is a schematic diagram showing a non-monolithic array of moth-eye structures 300 formed over a non-monolithic array of LEDs 38R, 38G, 38B.

[0109] Advantageously, the efficiency of light extraction from each LED can be increased.

[0110] Figures 11A to 11G are schematic diagrams showing a quantum rod structure 400 as one type of passive optical nanostructure that can be manufactured according to the above method with reference to Figures 3 to 9. The features of the embodiments of Figures 11A to 11G not discussed in more detail can be assumed to correspond to the features with equivalent reference numerals discussed above, including potential variations of the features.

[0111] As shown in Figure 11A, the quantum rod structure 400 includes a plurality of quantum rods 402 on a growth substrate 401. In an exemplary example, each quantum rod 402 includes an n-doped inner rod structure 403, a plurality of quantum wells 404, and a p-doped outer layer 406. The materials can include, for example, GaN, InGaN, AlInGaP, and other known wavelength-converting photoluminescence materials.

[0112] The quantum rods 402 are disposed over the LED 110 and convert the wavelength of light from the LED 110, for example, converting blue light to red light or ultraviolet radiation to red and green light.

[0113] Compared with coating a quantum dot material on an LED, quantum rods grown on a wafer can be placed with high precision and can be conveniently patterned to provide coverage of the light-emitting region of the LED. Advantageously, the efficiency may be improved. The nanorods can be selected from region 952 of the wafer of FIG. 4 to provide a color change that matches the color output of the aligned LEDs. Advantageously, the accuracy of color conversion may be improved.

[0114] FIGS. 11B-11E show the removal and transfer of the quantum rod structure 400 to the LED 110 on the support substrate 200 by the above method. FIG. 11F is a schematic diagram showing non-monolithic arrays of quantum rod structures 400R, 400G formed on non-monolithic arrays of LEDs 38B for the purpose of converting blue light to red or green light, or UV light to blue, green, or red light. As shown, not all of the LEDs 38B have quantum rod structures 400R, 400G stacked thereon. FIG. 11G is a schematic diagram showing another non-monolithic array of quantum rod structures 400R, 400G, 400B formed on non-monolithic arrays of LEDs 38UV for the purpose of converting UV light to red, green, or blue light. As shown, in this array, all of the LEDs 38UV have quantum rod structures 400R, 400G, 400B stacked thereon.

[0115] FIGS. 12A-12E are schematic diagrams showing a wire grid polarizer 500 as one type of passive optical nanostructure that can be fabricated according to the above method with reference to FIGS. 3-9. The features of the embodiments of FIGS. 12A-12E, which are not discussed in further detail, may be assumed to correspond to features with equivalent reference numbers discussed above, including potential variations of the features.

[0116] As shown in FIG. 12A, the wire grid polarizer 500 is attached to and grows on the base layer 501 on the release layer 901. FIGS. 12B to 12D show the removal of the wire grid polarizer 500 and the transfer to the LED 110 on the support substrate 200 by the above method. FIG. 12E is a schematic diagram showing non-monolithic array wire grid polarizers 500P, 500S formed on the non-monolithic array of LEDs 110. As shown, some wire grid polarizers 500P polarize light in a first direction, and some wire grid polarizers 500S polarize light in a second direction orthogonal to the first direction. This is achieved by arranging the wire grid polarizers 500S, 500P on the LED 110 in different, orthogonal directions according to the required polarization direction. The wire grid polarizer 500 can be arranged in other orientations, for example, + / - 45 degrees.

[0117] FIGS. 13A to 13B are schematic diagrams showing a collimating nanostructure 800 as one type of passive optical nanostructure that can be manufactured according to the above method with reference to FIGS. 3 to 9. The features of the embodiments of FIGS. 13A and 13B not discussed in further detail can be assumed to correspond to the features with equivalent reference numerals discussed above, including potential variations of the features.

[0118] As shown in FIG. 13A, the collimating nanostructure 800 is formed by being attached to a base layer 801 having a gap 802 between adjacent collimating nanostructures 800. As shown in FIG. 13B, the light emitted from the LED is received by the collimating nanostructure 800. Some light 923 is not deflected by the collimating nanostructure 800 and passes through the gap 802, some light 925 is deflected by the inclined side 804 of the collimating nanostructure 800 so as to be parallelized and continue to move away from the LED, and some light 921 is reflected by the collimating nanostructure 800 towards the LED.

[0119] Figures 14A - 14B are schematic diagrams showing an air gap surrounding a nanocolumn 700 as one type of passive optical nanostructure that can be manufactured according to the above method with reference to Figures 3 - 9. The features of the embodiments of Figures 14A - 14B not discussed in further detail can be assumed to correspond to features with equivalent reference numbers discussed above, including potential variations of the features.

[0120] As shown in Figure 14A, the air gap surrounding the nanocolumn 700 is sandwiched between the LED 110 and the substrate 720. The air gap surrounding the nanocolumn 700 includes a plurality of pillars 702 extending from a base layer 701. The pillars 702 act to separate the substrate 720 from the LED 110 and define an air gap 704 between the LED 110 and the substrate 720. As shown in Figure 14B, the pillars 702 are coupled to the substrate 720 by an adhesive layer 706.

[0121] The color conversion layer 438 is disposed between the base layer 701 and the LED 110. During operation, light from the LED 110 reaching the interface between the base layer 701 and the air gap 704 is totally internally reflected when it strikes the interface at an incident angle greater than the critical angle. Thus, only light that strikes the interface at an incident angle less than the critical angle passes through the interface. Ray 740 is a ray of light that has not been color - converted by the color conversion layer 438 and passes through the air gap 704 because the incident angle at the interface is less than the critical angle. Ray 722 is a ray of light that has been color - converted by the color conversion layer 438 and passes through the air gap 704 because the incident angle at the interface is less than the critical angle. Ray 724 is a ray of light that has been color - converted by the color conversion layer 438 and is totally reflected at the interface. This advantageously means that the light reaching the substrate 720 through the air gap is limited in the range of angles and thus tends to be less scattered, focused, and less likely to be captured in a propagating mode induced, for example, within one of the substrate layers, such as 720.

[0122] Next, the desirable dimensional characteristics of the passive optical nanostructure 130 for a nominal wavelength of 550 nm will be described. Each of the spacers 132 has a height h that is greater than the wavelength λ of the light passing through the air gap 133. The width w and pitch p of the spacers 132 are configured to minimize the diffusive light scattering from the spacers 132 of the light passing through the air gap 133 and to minimize the guiding of light within the spacers 132.

[0123] The pitch p may be less than 2λ, preferably less than λ, more preferably less than λ / 2, and most preferably less than λ / 5. The ratio w / p can be less than 0.5, preferably less than 0.3, and more preferably less than 0.1. Such an element can provide high-angle diffraction or zero-order diffraction. Advantageously, diffraction scattering from the spacers and the gap between the spacers can be reduced, and light scattering between adjacent curved reflectors 222A, 222B can be minimized. Such an element can be provided by lithographic manufacturing techniques on a monolithic wafer. The element can be transferred from the monolithic wafer or configured to provide a replication tool as described elsewhere in this specification.

[0124] As a comparison with the passive optical nanostructure, for example, a passive optical microstructure with a pitch p of 20 microns and a width w of 5 microns can be used to achieve a low effective refractive index and small-angle diffraction scattering. Such a spacer guides the incident light within the spacer and provides a Lambertian input to the optical structure 220. Unwanted crosstalk may be provided between the reflectors 220A, 220B.

[0125] The air gap surrounding the nanocolumn 700 has an effective refractive index n given by the following equation 1 having:

Equation

[0126] While realizing the coupling to the LED by the external substrate, light can be input to the optical element with a controlled conical angle and high efficiency. The optical crosstalk of the irradiation system can be reduced, and the mechanical and thermal stability can be improved.

[0127] It may be desirable to provide a very low light reflectivity in the region around the LED.

[0128] Figures 15A - 15C are schematic diagrams showing further steps that can be performed in addition to the fabrication and stacking of the passive optical nanostructures described above. The features of the embodiments of Figures 15A - 15C not discussed in further detail may be assumed to correspond to features with equivalent reference numerals discussed above, including potential variations of the features.

[0129] As shown in Figure 15A, before the LED 110 is placed on the support substrate 200, a nanoblack structure is formed on the support substrate 200 around the space where the LED 110 will be placed. The nanoblack structure 850 surrounds the space 40 but is not disposed in the space 40.

[0130] The nanoblack structure absorbs a very high percentage of the incident light by multiple reflections within the columnar absorption surface. Advantageously, stray light can be significantly reduced. In common with other passive optical nanostructures described elsewhere in this specification, the high - absorption nanoblack material can be fabricated using semiconductor processing equipment on a wafer and is thus expensive over a large area. It would be desirable to minimize the total area of use of the nanoblack material.

[0131] As shown in Figure 15B, next, the LED 110 is placed in the space 40 so as to be surrounded by the nanoblack structure 850.

[0132] Next, as shown in FIG. 15C, various passive optical nanostructures 300, 400, 500, 600 are sequentially stacked on the LED 110 using any of the above methods. The nanoblack structure 850 acts to block the light radiated from the LED 110 at a wide angle, helping to provide a more directional light output. The nanoblack structure also suppresses the reflection of ambient light incident on the display, improving the contrast of the display. Further crosstalk between adjacent LEDs is significantly reduced, improving the image fidelity in display applications.

[0133] FIGS. 16A-16E are schematic diagrams showing further steps that can be performed in addition to the fabrication and stacking of the passive optical nanostructures described above. The features of the embodiments of FIGS. 16A-16E not discussed in further detail can be assumed to correspond to features with equivalent reference numerals discussed above, including potential variations of the features.

[0134] As shown, a well 830 using a material such as photoresist can be formed around the LED 110 on the support substrate 200 after the LED 110 is disposed on the support substrate 200. Next, various passive optical nanostructures 300, 400, 500, 600 are sequentially stacked on the LED 110 using any of the above methods. The well 830 acts to block the light radiated from the LED 110 at a wide angle, helping to provide a more directed and controlled light output. The well can further have slanted metallized sides to direct the light more efficiently forward.

[0135] The well is formed on a monolithic wafer and can be transferred by the methods described elsewhere in this specification.

[0136] Next, a method of manufacturing an optical device including a light-emitting element 110 and a passive optical element including an air gap surrounding the nanocolumn of the present embodiment will be described.

[0137] Figures 17A - 17B are schematic diagrams showing cross - sectional views of a method for attaching an optical structure 220 to a support substrate 200 during the manufacture of the irradiation device 100. The features of the embodiments of Figures 17A - 17B not discussed in further detail may be assumed to correspond to features with equivalent reference numerals discussed above, including potential variations of the features.

[0138] As shown in Figure 17A, first, the optical structure 220 is disposed on the support substrate 200, and the support substrate 200 has a passive optical nanostructure including an air gap surrounding the nanocolumn 700, a light - emitting element 110, a reflective mask 35, and an output mask 150 including an opaque region 151 and an aperture region 152 attached thereto.

[0139] The opaque light - absorbing region 151 of the output mask 150 can be formed from any suitable opaque material, for example, by printing a black material on the substrate 200. The opaque region 151 may alternatively or additionally include other similar materials such as a nanostructured black absorber, "nanoblack", or those sold by Acktar (Kiryat - Gat, Israel). Advantageously, a very low reflectivity can be achieved from the front of the irradiation device.

[0140] The optical structure 220 includes a plurality of concave - curved reflective surfaces 222A, 222B, and each of the curved reflective surfaces 222A, 222B is arranged to be aligned with a respective light - emitting element 110 using the optical axis 199.

[0141] The optical structure 220 can be formed from a transparent body and a reflective material disposed on top of the curved reflectors 222A, 222B. The body of the optical structure 220 can be a glass or polymer material. The surface relief structure of the curved reflector can be provided, for example, by a molding or casting process of a polymer material. The reflective layer can be formed on a deposited metal coating including the curved reflectors 222A, 222B, for example, a silver or aluminum material, as well as a surface adhesion promoter and a protective layer.

[0142] Next, as shown in FIG. 17B, an adhesive layer 206 is formed between the optical structure 220 and the support substrate 200 to attach the optical structure 220 to the support substrate 200. The adhesive layer 206 fills the space around the light-emitting element 110 and the passive optical nanostructure 700. The adhesive of the adhesive layer 206 is injected in liquid form into the space between the optical structure 220 and the support substrate 200 and can then be set to a solid form, for example, by UV and / or heat curing, to bond the optical structure 220 to the support substrate 200. Advantageously, thermal and mechanical variations during operation are minimized.

[0143] During operation, the light ray 180 is output by the light-emitting element 110 and directed towards the passive optical nanostructure 700 including the air gap surrounding the nanocolumns. The light output from the nanostructure 700 is provided within the critical angle θc of the material of the optical structure 220. The light from the light-emitting element 110 is directed only towards the aligned curved reflecting surface 222B and not towards the curved reflecting surface 222A.

[0144] After reflection at the curved reflecting surface 222B, the light ray 180 is directed towards the opening 152 of the output mask 150 and not substantially towards the opaque region 150. The light is transmitted through the opening region 152 to the observer. The reflective mask 35 is arranged to block the light rays from the light-emitting elements passing through the opening 152 without reflection from the curved reflecting surface 222B. Advantageously, Fresnel reflection in the gap between the optical substrate 220 and the support substrate 200 is reduced, the optical efficiency is improved, and crosstalk between adjacent channels is reduced.

[0145] The light ray 180 is directed towards the respective aligned openings 152B rather than the opening 152A, advantageously reducing crosstalk between adjacent channels. The light-emitting element 110 may comprise image data, and the illumination device may be a display device. Reflection from the opaque region 151 of the output mask 150 can be reduced, and advantageously, the image contrast in a brightly illuminated environment can be increased.

[0146] It may be desirable to provide a passive optical element 700 on the optical structure 220.

[0147] Figures 18A - 18B show cross - sectional views of another method of attaching the optical structure 150 to the support substrate 200 during the manufacture of the irradiation device 100. The features of the embodiments of Figures 18A - 18B not discussed in further detail may be assumed to correspond to the features with equivalent reference numerals discussed above, including potential variations of the features.

[0148] As shown in Figure 18A, in the method, the optical structure 220 is disposed on the support substrate 200, the support substrate 200 has the light - emitting element 110, the reflection mask 35 and the output mask 150 attached thereto, and the optical structure 150 has the passive optical nanostructure 700 attached thereto.

[0149] Each passive optical nanostructure 700 is attached to the optical structure 220 so as to be aligned with the respective curved reflective surfaces 222A, 222B of the optical structure 220. The optical structure 220 is arranged such that each of its curved reflective surfaces 222A, 222B is aligned with the respective light - emitting element 110.

[0150] Next, as shown in Figure 18B, an adhesive layer 206 is formed between the optical structure 220 and the support substrate 200 to attach the optical structure 220 to the support substrate 200. The adhesive layer 206 fills the space around the light - emitting element 110 and the passive optical nanostructure 130. The adhesive of the adhesive layer 206 can be injected in liquid form into the space between the optical structure 150 and the support substrate 200 and then set to a solid form to bond the optical structure 150 to the support substrate 200. The operation of the structure is the same as that shown in Figure 17B.

[0151] Compared with the arrangement of Figure 17B, the passive optical nanostructure 700 is not formed on the light - emitting element, advantageously reducing complexity and improving the yield of the substrate 200. The passive optical nanostructure 700 is provided with high uniformity and low cost, as shown elsewhere in this specification. Advantageously, the uniformity of the device can be enhanced.

[0152] In some cases, it may be desirable to provide an optical element on the optical structure 220.

[0153] FIGS. 19A - 19C show cross - sectional views of a method of manufacturing the irradiation device 100. The features of the embodiments of FIGS. 19A - 19C not discussed in further detail can be assumed to correspond to the features with the same reference numerals discussed above, including potential variations of the features.

[0154] As shown in FIGS. 19A and 19B, in the method, the passive optical nanostructures 700 are first attached to the optical structure 220 such that each passive optical nanostructure 700 is aligned with a respective curved reflective surface 222A, 222B of the optical structure 220. Next, the light - emitting elements 110 are attached to the passive optical nanostructures 700 such that each light - emitting element 110 is aligned with a respective passive optical nanostructure 700. Next, as shown in FIG. 19C, a further support substrate 53 including the reflective mask 35 is coupled to the optical structure 220 using the adhesive layer 206 as described above with reference to FIGS. 17A - 17B and FIGS. 18A - 18B. The substrate 35 may optionally further include drive electrodes and circuitry (not shown).

[0155] Advantageously, the alignment of the light - emitting elements 110 with the curved reflective surfaces 222A, 222B is achieved during the attachment step, enhancing the uniformity of the alignment.

[0156] In the embodiments of FIGS. 17A - 19C, the passive optical element may further include other passive optical elements to provide further modification of the light output, as described elsewhere in this specification.

[0157] As further shown in FIG. 19B, the passive optical elements 1000A, 1000B can be formed in the aperture regions 152A, 152B using the methods described elsewhere in this specification. The polarization, color, and reflectivity of the light passing through the aperture 152 can be changed. Further, since such passive optical elements are away from the light - emitting elements 110, degradation due to heating is reduced, advantageously extending the lifespan.

[0158] Next, a method for transferring passive optical nanostructures using a transfer substrate will be further described.

[0159] Figures 20A - 20C show cross-sectional views of a further method for transferring passive optical nanostructure 938 to respective light-emitting elements 110.

[0160] First, as shown in FIG. 20A, a growth substrate 900 having a monolithic array of passive optical nanostructures 938 thereon is placed on a receiver substrate 975. Next, the region 912 corresponding to the selected passive optical nanostructure 938 is irradiated with light 910, such as UV light, that at least partially separates the selected passive optical nanostructure 938 from the growth substrate 900.

[0161] As shown in FIG. 20B, next, the selected passive optical nanostructure 938 corresponding to the irradiated region 912 is separated from the growth substrate 900 and adhered to the receiver substrate. The receiver substrate 975 can be an adhesive such that the selected passive optical nanostructure 938 adheres thereto when it contacts the receiver substrate 975.

[0162] Next, as shown in FIG. 20C, the receiver substrate 975 having the selected passive optical nanostructure thereon is placed on a support substrate 200 having a light-emitting element 110 thereon, such that each selected passive optical nanostructure 938 is aligned with a respective light-emitting element 110.

[0163] In this embodiment, each light-emitting element 110 also has a respective different type of passive optical nanostructure 1000 stacked thereon. Next, the selected passive optical nanostructure 938 on the receiver substrate 975 is transferred to the respective light-emitting elements 110 from the receiver substrate 975 such that the selected passive optical nanostructures 938 are each attached to the top of the stack.

[0164] Advantageously, the receiver substrate 975 can be a transfer substrate having material properties different from those of the support substrate 200. For example, the receiver substrate 975 can be a flexible material to assist in aligning the array 1000 of passive optical nanostructures with the z-direction light-emitting element 110. Further, a plurality of receiver substrates 975 can be used from each monolithic wafer 900, advantageously increasing throughput and reducing particle contamination from the monolithic wafer to the support substrate 200. Yield can be improved and costs can be reduced.

[0165] It may be desirable to assemble the stack of passive optical nanostructures before transferring them to the support substrate.

[0166] Figures 21A - 21D show cross-sectional views of a further method of transferring the passive optical nanostructures 938 to their respective light-emitting elements 110. The method is similar to the method shown in Figures 20A - 20C, but in this method, as shown in Figures 21A and 21B, after being transferred to the receiver substrate 975, the selected passive optical nanostructures 938 are transferred onto another stack of passive optical nanostructures 1000 already constructed on another receiver substrate 977. Next, as shown in Figures 21C and 21D, the entire stack including the selected passive optical nanostructures 938 is aligned with and transferred onto their respective light-emitting elements 110.

[0167] The stack of passive optical nanostructures 1000 can provide high uniformity over a wide area to advantageously achieve improved yield and uniformity compared to the arrangement of Figures 20A - 20C without degrading the substrate 200 including the light-emitting elements 110.

[0168] The features of the embodiments of Figures 20A - 20C and Figures 21A - 21D, not discussed in further detail, can be assumed to correspond to the features with the same reference numbers discussed above, including potential variations of the features.

[0169] As used herein, the terms "substantially" and "about" provide industry-recognized tolerances with respect to the relativity between corresponding terms and / or items. Such industry-recognized tolerances are in the range of 0 percent to 10 percent and correspond to, but are not limited to, component values, angles, etc. Such relativity between items is in the range of about 0 percent to 10 percent.

[0170] Although various embodiments in accordance with the principles disclosed herein have been described above, it should be understood that they are presented by way of example only and not by way of limitation. Thus, the breadth and scope of the present disclosure should not be limited by any of the above-described exemplary embodiments, but should be defined only in accordance with the claims issued from the present disclosure and their equivalents. Further, the above advantages and features are provided in the described embodiments, but the application of such issued claims to processes and structures achieving any or all of the above advantages should not be limited.

[0171] In addition, the section headings of this document are provided to maintain consistency with proposals under 37 CFR 1.77 or to provide organizational cues. These headings should not limit or characterize the embodiments described in the claims that may issue from this disclosure. Specifically, by way of example, the heading refers to the "Technical Field," but the claims should not be limited by the selected language under this heading in order to describe the so-called field. Further, the description of the technology in the "Background" should not be construed as an admission that a particular technology is prior art to any embodiment in this disclosure. Also, the "Summary" should not be regarded as characterizing the features of the embodiments described in the issued claims. Further, the reference to the singular "invention" in this disclosure should not be used to assert that there is only a single point of novelty in this disclosure. Multiple embodiments can be described in accordance with the limitations of the multiple claims that may issue from this disclosure, and thus such claims define the embodiments protected thereby and their equivalents. In all cases, the scope of such claims should be considered on its own merits in light of this disclosure and should not be constrained by the headings set forth in this document.

Claims

1. an array of light emitting elements; an array of first passive optical nanostructures; and Equipped with each of the first passive optical nanostructures of the array of first passive optical nanostructures is aligned with a respective light emitting element of the array of light emitting elements; the array of first passive optical nanostructures comprising a plurality of first passive optical nanostructures arranged in relative spatial positions corresponding to positions of a plurality of first passive optical nanostructures previously present in the first monolithic array of first passive optical nanostructures; in at least one direction, for at least one pair of first passive optical nanostructures in the array of first passive optical nanostructures, there is, for each pair, at least one unoccupied spatial location that is not selected from the first monolithic array and that corresponds to a location of a respective first passive optical nanostructure that was between the respective pair of first passive optical nanostructures when disposed in the first monolithic array; the spatial arrangement of the array of first passive optical nanostructures reflects a selection based on properties of the first passive optical nanostructures that meet a predetermined measurement threshold for an optical or electrical property; The relative spatial positions of the first passive optical nanostructures in the array are maintained from their positions in the first monolithic array. Lighting equipment.

2. The lighting device of claim 1 , wherein the array of light-emitting elements is formed on a supporting substrate.

3. 3. The lighting device of claim 2, wherein the array of light-emitting elements and the array of first passive optical nanostructures are sandwiched between the support substrate and another substrate opposite the support substrate, and each first passive optical nanostructure is aligned with a respective light-emitting element.

4. The illumination device of claim 1 , wherein each of the first passive optical nanostructures of the array of passive optical nanostructures is stacked on a respective light emitting element of the array of light emitting elements.

5. 10. The lighting device of claim 1, wherein each of the light emitting elements is a micro LED comprising a maximum dimension of at most 300 micrometers.

6. The illumination device of claim 1 , wherein each of the first passive optical nanostructures has a maximum dimension of at most 400 micrometers.

7. 10. The lighting device of claim 1, wherein a maximum dimension of each of the first passive optical nanostructures is greater than or equal to a maximum dimension of a light emitting area of ​​a light emitting element aligned with that first passive optical nanostructure.

8. The illumination device of claim 1 , wherein the first passive optical nanostructure includes one or more subfeatures having a maximum dimension of at most 5 micrometers.

9. The first passive optical nanostructure comprises: wire grid polarizers, form birefringent retarders, Quantum dot or quantum rod color conversion structures, distributed Bragg reflector, metamaterials, Fabry-Perot cavity structure, Dichroic stack, hologram, Moth-eye structure, Nano black material, nanocollimator, an air gap surrounding the nanocolumn; Photonic crystals, 10. The lighting device of claim 1, comprising any one of the following types:

10. The illumination device of claim 1 , wherein the first passive optical nanostructure is a wire grid polarizer.

11. 11. The lighting device of claim 10, wherein at least one of the wire grid polarizers is aligned with a respective light-emitting element in a first orientation and at least one other wire grid polarizer is aligned with a respective light-emitting element in a second orientation, the second orientation being orthogonal to the first orientation.

12. The illumination device of claim 1 , wherein the first passive optical nanostructure is a quantum dot or quantum rod color conversion structure.

13. a second array of second passive optical nanostructures; each of the second passive optical nanostructures of the second array of second passive optical nanostructures is aligned with a respective light emitting element of the array of light emitting elements; the array of second passive optical nanostructures comprising a plurality of second passive optical nanostructures arranged in relative spatial positions corresponding to positions of a plurality of second passive optical nanostructures previously present in the second monolithic array of second passive optical nanostructures; in at least one direction, for at least one pair of second passive optical nanostructures in the array of second passive optical nanostructures, there is, for each pair, at least one unoccupied spatial location that is not selected from the second monolithic array and that corresponds to a location of each second passive optical nanostructure that was between the respective pair of second passive optical nanostructures when disposed in the second monolithic array; The illumination device of claim 1 , wherein the relative spatial positions of the second passive optical nanostructures in the array are maintained from their positions in the second monolithic array.

14. The illumination device of claim 13 , wherein the first passive optical nanostructure is a different type of passive optical nanostructure than the second passive optical nanostructure.

15. 14. The illumination device of claim 13, wherein each second passive optical nanostructure of the second array of passive optical nanostructures is stacked on either a respective light emitting element or a respective first passive optical nanostructure.

16. At least one of the light emitting elements having a first passive optical nanostructure aligned thereto does not have a second passive optical nanostructure aligned thereto; or 14. The lighting device of claim 13, wherein at least one of the light emitting elements having a second passive optical nanostructure aligned thereto does not have a first passive optical nanostructure aligned thereto.

17. the array of light emitting elements comprises a plurality of light emitting elements arranged in relative spatial positions corresponding to the positions of a plurality of light emitting elements previously present in the monolithic array of light emitting elements; in at least one direction, for at least one pair of light emitting elements in the array of light emitting elements, there is, for each pair, at least one unoccupied spatial location that is not selected from the monolithic array of light emitting elements and corresponds to a location of a respective light emitting element that was between the respective pair of light emitting elements when disposed in the monolithic array of light emitting elements; 10. The lighting device of claim 1, wherein the relative spatial positions of the light emitting elements in the array are maintained from their positions in the monolithic array of light emitting elements.

18. An irradiation device, comprising: an array of light emitting elements; Non-monolithic arrays of passive optical nanostructures formed from monolithic arrays of passive optical nanostructures; Equipped with each of the passive optical nanostructures is aligned with a respective light emitting element of the array of light emitting elements; the passive optical nanostructures of the non-monolithic array of passive optical nanostructures are arranged such that their original positions are maintained relative to one another within the monolithic array; An illumination device wherein, for at least one pair of passive optical nanostructures in the non-monolithic array in at least one direction, for each pair, there was at least one respective passive optical nanostructure in the monolithic array of passive optical nanostructures that was located in the monolithic array of passive optical nanostructures between the at least pair of passive optical nanostructures in the at least one direction and that was not located between them in the non-monolithic array of passive optical nanostructures, each of the first passive optical nanostructures modulating the polarization of light emitted by the respective light-emitting element.

19. 20. The illumination device of claim 18, wherein at least one of the passive optical nanostructures has a side length or diameter of less than 250 micrometers.

20. A display device comprising the illumination device according to claim 1.

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