Display panel system with integrated microlens array and method of manufacturing same

Abstract

Various embodiments include a display panel having an integrated microlens array. The display panel generally includes a mesa array that includes an array of pixel light sources (e.g., LEDs) electrically coupled to corresponding pixel drive circuits (e.g., FETs). The microlens array is aligned with a mesa that includes the pixel light source and is positioned to reduce divergence of light generated by the pixel light source. In some embodiments, an array of microlenses formed from a layer of microlens material is formed directly on top of the mesa. The display panel may also include an integrated optical spacer formed of the same layer of microlens material to maintain positioning between the microlenses and the pixel driving circuitry.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority to U.S. Provisional Patent Application No. 62 / 909,205, filed on October 1, 2019, entitled “Systems and Fabrication Methods for Display Panels with Integrated Micro-Lens Array,” which is incorporated herein by reference. Technical Field

[0003] The present disclosure relates generally to display devices, and more particularly, to a display panel system with an integrated microlens array and a method of manufacturing the same. Background Art

[0004] Display technology is becoming increasingly popular in today's commercial electronic devices. These display panels are widely used in fixed large screens such as liquid crystal display televisions (LCD TVs) and organic light emitting diode televisions (OLED TVs) as well as portable electronic devices such as personal notebook computers, smart phones, tablet computers and wearable electronic devices. The development direction of fixed large screen technology is to achieve a large viewing angle to accommodate and enable multiple viewers to see the screen from a variety of angles. For example, various liquid crystal materials such as super twisted nematic (STN) and thin film compensated super twisted nematic (FSTN) have been developed to achieve a large viewing angle for all pixel light sources in the display panel.

[0005] However, most portable electronic devices are designed primarily for a single user, and the screen orientation of these portable devices should be adjusted to the best viewing angle for the corresponding user rather than a wide viewing angle that accommodates multiple viewers. For example, a suitable viewing angle for a user may be perpendicular to the screen surface. In this case, the light emitted at a wide viewing angle is mostly wasted compared to a fixed large screen. In addition, a wide viewing angle may cause privacy issues when using portable electronic devices in public areas.

[0006] In addition, in conventional projection systems based on passive imaging devices such as liquid crystal displays (LCDs), digital mirror devices (DMDs), and liquid crystal on silicon (LCOS), the passive imaging devices themselves do not emit light. Specifically, conventional projection systems are able to project images by optically modulating parallel light emitted from a light source, for example, a portion of the light emitted at the pixel level by an LCD panel or reflected at the pixel level by a DMD panel. However, the portion of light that is not emitted or reflected is lost, which reduces the efficiency of the projection system. In addition, in order to provide parallel light, complex illumination optical components are required to collect the divergent light emitted by the light source. The illumination optical components not only make the system bulky, but also introduce additional light losses into the system, which further affects the performance of the system. In conventional projection systems, typically less than 10% of the illumination light generated by the light source is used to form a projected image.

[0007] Light emitting diodes (LEDs) made of semiconductor materials can be used in monochrome or full-color displays. In current displays using LEDs, LEDs are usually used as light sources to provide light that is optically modulated by, for example, an LCD or DMD panel. That is, the light emitted by the LED does not form an image itself. LED displays that include LED panels with multiple LED dies as imaging devices have also been studied. In such LED displays, the LED panel is a self-emitting imaging device, in which each pixel can include one LED die (monochrome display) or multiple LED dies, each die representing a primary color (full-color display). However, the light emitted by the LED die is generated from spontaneous emission and is therefore non-directional, resulting in a large divergence angle. A large divergence angle can cause various problems for LED displays. For example, due to the large divergence angle, the light emitted by the LED die can be more easily diffused and / or reflected into the LED display. The diffused / reflected light can illuminate other pixels, thereby causing light crosstalk, loss of clarity, and loss of contrast between pixels. Summary of the invention

[0008] Improved display designs are needed that improve and help address the shortcomings of conventional display systems such as those described above. In particular, a display panel is needed that reduces viewing angles to better protect user privacy, or / and reduces light waste to reduce power consumption, and reduces light interference between pixels to provide a better image.

[0009] Various embodiments include a display panel with an integrated microlens array. The display panel typically includes an array of pixel light sources (e.g., LEDs, OLEDs) electrically coupled to corresponding pixel drive circuits (e.g., FETs). The microlens array is aligned with the pixel light sources and reduces the divergence of light generated by the pixel light sources. The display panel may also include an integrated optical spacer to maintain a gap between the microlenses and the pixel drive circuit.

[0010] The microlens array reduces the divergence angle of the light generated by the pixel light source and the available viewing angle of the display panel. This in turn reduces power waste, increases brightness and / or better protects user privacy in public areas.

[0011] Display panels with integrated microlens arrays can be manufactured using a variety of production methods, resulting in a variety of device designs. In one aspect, the microlens array is directly manufactured as a mesa or protrusion of a substrate with a pixel light source. In some aspects, techniques such as self-assembly, high temperature reflow, grayscale mask lithography, molding / imprinting / stamping, and dry etching pattern transfer can be used to manufacture the microlens array.

[0012] Other aspects include components, devices, systems, improvements, methods and processes including methods of production, applications, and other technologies related to any of the above.

[0013] In one aspect, a light-emitting pixel unit includes: at least one mesa formed on a substrate. The light-emitting pixel unit also includes a microlens formed by a microlens layer covering at least the top of the at least one mesa. In some embodiments, the material of the microlens layer is different from the material of the at least one mesa, and the microlens layer is in direct physical contact with the at least one mesa.

[0014] In some embodiments of the light-emitting pixel unit, a microlens is independently formed around a top portion of the at least one mesa.

[0015] In some embodiments of the light-emitting pixel unit, a spacer is formed between the at least one mesa and the microlens by the same microlens layer.

[0016] In some embodiments of the light-emitting pixel unit, the thickness of the spacer is no greater than 1 micrometer.

[0017] In some embodiments of the light-emitting pixel unit, the material of the spacer is the same as that of the microlens.

[0018] In some embodiments of the light-emitting pixel unit, the microlens is made of a dielectric material.

[0019] In some embodiments of the light-emitting pixel unit, the dielectric material includes silicon oxide.

[0020] In some embodiments of the light-emitting pixel unit, the material of the microlens is photoresist.

[0021] In some embodiments of the light-emitting pixel unit, the height of the microlens is no greater than 2 micrometers.

[0022] In some embodiments of the light-emitting pixel unit, the width of the microlens is no greater than 4 micrometers.

[0023] In some embodiments of the light-emitting pixel unit, on the substrate, the at least one mesa is located in a mesa array matrix, and the microlens is located in a microlens array matrix placed according to the placement of the mesa array.

[0024] In some embodiments of the light-emitting pixel unit, the top of the at least one mesa is flat, and the shape of the microlens is hemispherical.

[0025] In some embodiments of the light-emitting pixel unit, the at least one mesa comprises at least one light-emitting device.

[0026] In some embodiments of the light-emitting pixel unit, the light-emitting device includes a PN junction.

[0027] In another aspect, a method for manufacturing a light-emitting pixel unit includes: providing a substrate; forming the at least one mesa on the substrate; and directly depositing a microlens material layer on at least the top of the at least one mesa. In some embodiments, the microlens material layer conforms to the shape of the at least one mesa and has a hemispherical shape on the at least one mesa.

[0028] In some embodiments of the method for manufacturing a light-emitting pixel unit, the microlens material layer is deposited using a chemical vapor deposition technique.

[0029] In some embodiments of the method for manufacturing a light-emitting pixel unit, parameters of the chemical vapor deposition technology used to deposit the microlens material layer include: power of 0 W to 1000 W, pressure of 100 mTorr to 2000 mTorr, temperature of 23° C. to 500° C., gas flow rate of 0 sccm to 3000 sccm, and time of 1 hour to 3 hours.

[0030] In some embodiments of the method for manufacturing a light-emitting pixel unit, the microlens material layer is made of a dielectric material.

[0031] In some embodiments, the method for manufacturing a light-emitting pixel unit further includes: patterning the microlens material layer to expose an electrode region of the substrate.

[0032] In some embodiments of the method for manufacturing a light-emitting pixel unit, the patterning step further includes: forming a mask on the surface of the microlens material; patterning the mask by a photolithography process to form an opening in the mask and expose the microlens material layer above the electrode region of the at least one mesa; and etching the portion of the microlens material layer exposed by the opening with the mask protected in place.

[0033] In some embodiments of the method for manufacturing a light-emitting pixel unit, etching is a wet etching method.

[0034] In another aspect, a method for manufacturing a light-emitting pixel unit includes: providing a substrate; forming at least one mesa on the substrate; and directly depositing a microlens material layer on at least the top of the at least one mesa. In some embodiments, the microlens material layer covers the top of the at least one mesa, and the top surface of the microlens material is flat. In some embodiments, the method for manufacturing a light-emitting pixel unit also includes patterning the microlens material layer from top to bottom, thereby forming at least one hemisphere in the microlens material layer without penetrating the microlens material layer. In some embodiments, the hemisphere is located above the at least one mesa.

[0035] In some embodiments, the method for manufacturing a light-emitting pixel unit further includes: depositing a mask layer on the surface of the microlens material layer; patterning the mask layer to form a hemispherical pattern in the mask layer; and etching the microlens material layer using the hemispherical pattern as a mask to form a hemisphere in the microlens material layer.

[0036] In some embodiments of the method for manufacturing a light-emitting pixel unit, after the microlens material layer is etched, the microlens material layer is not etched through to expose a top surface of the at least one mesa, thereby forming a spacer on top of the at least one mesa.

[0037] In some embodiments of the method for manufacturing a light-emitting pixel unit, the microlens material layer is deposited by spin coating.

[0038] In some embodiments of the method for manufacturing a light-emitting pixel unit, the mask layer is first patterned by a photolithography process and then patterned by a reflow process.

[0039] In some embodiments of the method for manufacturing a light-emitting pixel unit, etching the microlens material layer is performed by a photolithography process.

[0040] In some embodiments, the method for manufacturing a light-emitting pixel unit further includes: after forming the at least one mesa and before depositing the microlens material layer, forming a mark layer having a mark for aligning with the microlens material layer in a patterning process.

[0041] In some embodiments, the method for manufacturing a light-emitting pixel unit further includes: after patterning the microlens material layer, patterning the microlens material layer to expose an electrode region of the substrate.

[0042] The design of the display device and system disclosed herein forms microlenses directly on top of the table on the substrate by utilizing the consistency of the shape of the microlens material with the shape of the table, thereby greatly reducing the steps of microlens manufacturing and improving the efficiency of display panel structure formation. In addition, the manufacture of the display system can reliably and effectively form a microlens structure pattern without using or retaining an additional substrate. Reducing the viewing angle and reducing light interference improves the luminous efficiency, resolution and overall performance of the display system. Therefore, the implementation of a display system with a microlens array can better meet the display requirements for augmented reality (AR) and virtual reality (VR), head-up displays (HUD), displays for mobile devices, displays for wearable devices, high-definition projectors and automotive displays compared to using conventional displays.

[0043] It should be noted that the various embodiments described above may be combined with any other embodiments described herein. The features and advantages described in the specification are not all-inclusive, and in particular, many additional features and advantages will be apparent to those of ordinary skill in the art from the drawings, the specification, and the claims. Furthermore, it should be noted that the language used in the specification is selected primarily for readability and instructional purposes, and is not selected to delineate or limit the subject matter of the invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] In order that the present disclosure can be understood in more detail, the present disclosure may be described in more detail by referring to the features of various embodiments, some of which are shown in the accompanying drawings. However, these drawings only illustrate the relevant features of the present disclosure and are therefore not to be considered restrictive, as the description may allow for other effective features.

[0045] Figure 1 is a cross-sectional view of an example display panel integrated with a microlens array according to some embodiments.

[0046] Figure 2A is a top view of an example monochrome display panel having a square array layout of pixels according to some embodiments.

[0047] Figure 2B is a top view of an example monochrome display panel showing triangle and polygon array layouts of pixels according to one embodiment.

[0048] Figure 3A is a top view of an example multi-color display panel having a square array layout of pixels according to some embodiments.

[0049] Figure 3B is a top view of an example multi-color display panel having a triangle array layout of pixels according to some embodiments.

[0050] Figure 4 A flow chart of a manufacturing method for forming a light-emitting pixel unit on a display panel integrated with a microlens array according to some embodiments is shown.

[0051] Figure 5 A flow chart of a manufacturing method for forming a light-emitting pixel unit on a display panel integrated with a microlens array according to some embodiments is shown.

[0052] Fig. 6A A method of manufacturing a display panel integrated with a microlens array using top-down pattern transfer according to some embodiments is shown.

[0053] Figure 6B A method of manufacturing a display panel integrated with a microlens array using top-down pattern transfer according to some embodiments is shown.

[0054] Figure 7 is a top view of a micro LED display panel according to some embodiments.

[0055] According to common practice, the various features illustrated in the drawings may not be drawn to scale. Therefore, for clarity, the sizes of various features may be arbitrarily expanded or reduced. In addition, some drawings may not depict all components of a given system, method, or device. Finally, the same reference numerals may be used to represent similar features throughout the specification and drawings. DETAILED DESCRIPTION

[0056] Numerous details are described herein in order to provide a thorough understanding of the example embodiments shown in the accompanying drawings. However, some embodiments may be practiced without many of the specific details, and the scope of the claims is limited only by those features and aspects specifically detailed in the claims. In addition, well-known methods, components, and materials are not described in detail so as not to unnecessarily obscure the relevant aspects of the embodiments described herein.

[0057] As described above, in some examples, the LED die has a large divergence angle, which may lead to various problems, such as those discussed in the background technology section. In addition, in a projection system that uses an LED array with multiple LED dies as a self-luminous imaging device, a projection lens or a projection lens group is required to project the image generated by the LED array, and the projection lens may have a limited numerical aperture. Therefore, due to the large divergence angle of the LED die, only a portion of the light emitted by the LED die can be collected by the projection lens. This reduces the brightness of the LED-based projection system and / or increases power consumption.

[0058] Embodiments consistent with the present disclosure include an integrated display panel as a self-luminous imager device, the integrated display panel including a substrate having a pixel driving circuit array, a table array formed on the substrate, which may include, for example, LED dies, and a microlens array formed above the table array, and a method of manufacturing the display panel. The display panel and the projection system based on the display panel combine the light source, imaging function and beam collimation function in a single monolithic device, which can overcome the shortcomings of traditional projection systems.

[0059] Figure 1 is a cross-sectional view of an example display panel 100 integrated with a microlens array 120 according to some embodiments. Figure 1 In the embodiment of the present invention, the completed display panel 100 includes a lens-free display panel 110 (i.e., without a microlens array) and a microlens array 120. The display panel 100 includes an array 102 of independent mesas, such as in each individual pixel shown as pixel 112P. In some embodiments, the mesa array 102 is formed on a substrate 130. In some embodiments, the substrate is a semiconductor substrate. In some embodiments, each pixel 112P also includes a pixel driving circuit ( Figure 1 102M). The microlenses 122M in the microlens array 120 cover at least the top of the mesa 102M. In some embodiments, the microlenses 122M directly cover and contact the mesa 102M. In some embodiments, the microlenses 122M conform to the shape of the mesa 102M and form a hemisphere on the mesa 102M. For example, the microlenses are formed on the top and outside of the mesa 102M. In some embodiments, the components of the microlens array 120 are different from the components of the mesa 102M. In some embodiments, the top of the mesa 102M is generally flat and the shape of the microlenses 122M is generally hemispherical. In some embodiments, the mesa 102M is a circular platform. In some embodiments, the microlenses 122M do not touch after they are formed on the top of the mesa 102M.

[0060] In some embodiments, the microlens array 120 is made of a dielectric material such as silicon oxide. In some embodiments, the dielectric material is a transparent oxide such as silicon nitride, silicon carbide, aluminum oxide, etc. In some embodiments, the microlens array 120 is made of photoresist. In some embodiments, the height of the microlens 122M is not greater than 2 microns. In some embodiments, the height of the microlens 122M is not greater than 1 micron. In some embodiments, the height of the microlens 122M is not greater than 0.5 microns. In some embodiments, the width of the microlens 122M is not greater than 4 microns. In some embodiments, the width of the microlens 122M is not greater than 3 microns. In some embodiments, the width of the microlens 122M is not greater than 2 microns. In some embodiments, the width of the microlens 122M is not greater than 1 micron. In some embodiments, the aspect ratio of the microlens 122M is greater than 2.

[0061] Each pixel light source 112S is electrically coupled to and driven by a pixel driving circuit. The pixel light sources 112S are independently controllable. A microlens array 120 is formed above the lensless display panel 110, wherein the microlenses 122M are aligned with corresponding mesas 102 including the pixel light sources 112S ( Figure 1 For the purposes of this disclosure, terms such as "above" and "top" refer to the direction of light propagating away from the pixel light source 112A and toward the observer. The mesa array 102 including the pixel light sources 112S, the pixel driving circuit array (not shown), and the microlens array are all integrated on a common substrate 130. In some embodiments, each pixel light source 112S includes a PN junction.

[0062] For the sake of clarity, Figure 1 Only three independent pixels 112P are shown in the display panel 100, each of which includes a pixel light source 112S corresponding to a single microlens 122M. It should be understood that a complete display panel 100 will include an array of many independent pixels 112P and many microlenses 122M. In addition, a one-to-one correspondence between the microlenses 122M and the table 102M including the pixel light source 112S is not necessary, nor is a one-to-one correspondence between the pixel driving circuit (not shown) and the pixel light source. The pixel light source can also be made of multiple independent optical elements, for example, multiple LEDs connected in parallel. In some embodiments, one microlens 122M can cover multiple table 102M.

[0063] The pixel light sources 112S generate light for the display panel 100. Different types of pixel light sources 112S may be used, for example, a micro LED array including an independent micro LED array, a micro OLED array including an independent micro OLED array, or a micro LCD array including an independent micro LCD array. Note that in an LCD array, the "pixel light source" actually modulates light generated from a backlight or elsewhere, rather than generating light electrically, but is still referred to herein as a pixel light source unless otherwise noted. In one embodiment, each independent pixel light source 112S includes a single light element. In another embodiment, each independent pixel light source 112S includes multiple light elements, such as multiple LEDs coupled in parallel.

[0064] exist Figure 1 In the embodiment, the microlens array 120 includes an array of independent microlenses 122M, each microlens is aligned with a corresponding pixel light source 112S. Each microlens 122M has positive optical power and is configured to reduce the light emitted by the corresponding pixel light source 112S. Figure 1 116-118. The divergence or viewing angle of the light shown in the microlens array 120 is shown in FIG. 116. The light ray 116 represents the edge of the light beam emitted from the pixel light source 112S, which has a relatively wide original divergence angle 126. In one embodiment, the original angle 126 is greater than 60 degrees. The light is bent by the microlens 122M so that the new edge light ray 118 now has a reduced divergence angle 128. In one embodiment, the reduced angle 128 is less than 30 degrees. The microlenses 122M in the microlens array 120 are generally identical. Examples of microlenses include spherical microlenses, aspherical microlenses, Fresnel microlenses, and cylindrical microlenses.

[0065] The microlens array 120 generally has a planar side and a curved side. Figure 1 In the embodiment, the bottom of the microlens 122M is a flat side, and the top of the microlens 122M is a curved side. Typical shapes of the base of each microlens 122M include circular, square, rectangular, and hexagonal. The individual microlenses 122M may be the same or different in shape, curvature, optical power, size, base, spacing, etc. Figure 1 In the example of , the circular base of microlens 122M has the same width as independent pixel 112P, but a smaller area because the microlens base is circular and independent pixel 112P is square. In some embodiments, the microlens base area is larger than the area of ​​pixel light source 112S.

[0066] In some embodiments, an optical spacer 140 is formed between the lensless display panel 110 and the microlens array 120. In some embodiments, an optical spacer 140 is formed between the mesa array 102 and the microlens array 120.

[0067] The optical spacer 140 is an optically transparent layer formed to maintain the position of the microlens array 120 relative to the pixel light source array 112S. The optical spacer 140 can be made of a variety of materials that are transparent to the light of each wavelength emitted by the pixel light source 112. Example transparent materials for the optical spacer 140 include polymers, dielectrics, and semiconductors. The material used to make the optical spacer 140 can be the same or different from the material used to make the microlens array 120. In some embodiments, when the microlens 122M is formed to conform to the shape of the mesa 102M, the optical spacer layer 140 can be formed with the microlens 122M in the same process and the same material. In some embodiments, the optical spacer layer 140 can be formed below the microlens 122M in the same process and the same material as the microlens 122M. In some embodiments, the height of the mesa 102M measured from the bottom of the substrate 130 is greater than, equal to, or less than the thickness of the optical spacer 140.

[0068] The thickness of the optical spacer 140 is designed to maintain an appropriate spacing between the microlens array 120 and the pixel light source array 112S. As an example, for an optical spacer that maintains an optical spacing between the pixel light source and the microlens greater than the focal length of the microlens, an image of a single pixel is formed at a certain distance. As another example, for an optical spacer that maintains an optical spacing between the pixel light source and the microlens less than the focal length of the microlens, a reduced divergence / viewing angle is achieved. The amount of reduction in divergence / viewing angle also depends in part on the thickness of the optical spacer 140 measured from the top surface of the mesa 102M. In some embodiments, the thickness of the spacer 140 measured from the top surface of the mesa 102M is no more than 1 micron. In some embodiments, the thickness of the optical spacer 140 measured from the top surface of the mesa 102M is no more than 0.5 microns. In some embodiments, the thickness of the optical spacer 140 measured from the top surface of the mesa 102M is no more than 0.2 microns. In some embodiments, the thickness of the optical spacer 140 measured from the top surface of the mesa 102M is approximately 1 micron. In some embodiments, the material of the optical spacer 140 is the same as that of the microlens array 120 .

[0069] In some embodiments, a brightness enhancement effect is achieved by integrating a microlens array onto a display panel. In some examples, due to the light-gathering effect of the microlenses, the brightness with the microlens array is 4 times the brightness without the microlens array in a direction perpendicular to the display surface. In alternative embodiments, the brightness enhancement factor can vary depending on the design of the microlens array and the optical spacer. For example, a factor greater than 8 can be achieved.

[0070] Figure 2A-2B is a top view of an example monochrome display panel integrated with a spherical microlens array according to some embodiments. More specifically, Figure 2Ais a top view of an example monochrome display panel 200 having a square array layout of pixels, Figure 2B 2 is a top view of an example monochrome display panel 250 showing pixel triangular and hexagonal array layouts. As an example, an embodiment of a triangular array layout 230 and an implementation of a hexagonal array layout 235 are shown. Figure 2B As shown. The two display panels 200, 250 include arrays of microlenses 210, 260, table arrays including pixel light sources 220, 270 located below the microlenses 210, and optional optical spacers 240, 290 formed between the microlens array and the table array. Each independent microlens is aligned with the table including an independent pixel light source. In more detail, the display panel 200 with a square matrix layout includes: an array of independent microlenses 210, a corresponding table array including pixel light sources 220, and an optional optical spacer 240 between the microlens array and the table array, and the display panel 250 with a triangular matrix or hexagonal layout includes: an array of independent microlenses 260, a corresponding table array including pixel light sources 270, and an optional optical spacer 290 between the microlens array and the table array. In the two display panels 200, 250, the pixel light sources are all monochrome pixel light sources that produce light of the same color, such as monochrome LEDs, and the monochrome pixel light sources form a monochrome display panel.

[0071] exist Figure 2A-2B In the embodiment, each microlens 210, 260 of the corresponding display panel 200, 250 is a spherical microlens arranged in a square, triangular or hexagonal matrix. In an alternative embodiment, the microlens may have an aspherical shape. The microlenses may also be arranged in other matrix layouts, such as a rectangular matrix layout, an octagonal matrix layout, or a combination of geometric matrix layouts.

[0072] Figure 3A-3B is a top view of an example multi-color display panel integrated with a spherical microlens array according to some embodiments. More specifically, Figure 3A is a top view of an example multi-color display panel 300 having a square array layout of pixels, and Figure 3B 3 is a top view of an example multi-color display panel 350 having a pixel triangle array layout. The two display panels 300, 350 include: an array of microlenses 310, 360, an array of mesas containing pixel light sources 320, 370, and optional optical spacers 340, 390 formed between the array of microlenses and the array of pixel light sources, each microlens is aligned with a corresponding mesa containing an independent pixel light source.

[0073] In more detail, the display panel 300 having a square matrix layout includes: an array of independent microlenses 310, a corresponding array of mesas containing pixel light sources 320, and an optional optical spacer 340 between the two arrays. Figure 2A-2B In the monochrome display panels 200 and 250 shown, the pixel light source array in the display panel 300 includes pixel light sources associated with different emission wavelengths, thereby producing a multi-color display panel. For example, the pixel light source 320R produces red light, and the corresponding microlens 310R is aligned with the red pixel light source, the pixel light source 320G produces green light, and the corresponding microlens 310G is aligned with the green pixel light source, and the pixel light source 320B produces blue light, and the corresponding microlens 310B is aligned with the blue pixel light source. In one embodiment, a plurality of pixel light sources 320 with different colors are combined together in a certain ratio to form an RGB full-color pixel. For example, several pixel light sources 320 with different colors are combined together in a triangular, rectangular or hexagonal matrix layout. For example, in a common design, the red pixel light source 320R, the green pixel light source 320G and the blue pixel light source 320B are combined in a ratio of 1:2:1 to form a single full-color pixel 330 with a 2×2 square layout light source.

[0074] exist Figure 3A-3B In the embodiment, each microlens 310, 360 of the corresponding display panel 300, 350 is a spherical microlens. In an alternative embodiment, the microlens may have an aspherical shape. The microlenses may also be arranged in other matrix layouts, such as a rectangular matrix layout or a hexagonal matrix layout.

[0075] The display panel 350 having a triangular matrix layout also includes an array of independent microlenses 360, a corresponding table array containing pixel light sources 370, and an optical spacer 390 located between the two arrays, and the pixel light sources 370 are also associated with different emission wavelengths to provide light of different colors. For example, the pixel light source 370R emits red light, and the corresponding microlens 360R is aligned with the red pixel light source, the pixel light source 370G emits green light, and the corresponding microlens 360G is aligned with the green pixel light source, and the pixel light source 370B emits blue light, and the corresponding microlens 360B is aligned with the blue pixel light source. In this example, the red pixel light source 320R, the green pixel light source 320G, and the blue pixel light source 320B are combined in a ratio of 1:1:1 to form a single full-color pixel 380 with a triangular layout of light sources. In some embodiments, a cylindrical microlens array can be formed on top of each table.

[0076] Figure 4-5 Examples of different manufacturing methods of forming a display panel integrated with a microlens array according to various embodiments are shown.

[0077] Figure 4A flowchart of a method for manufacturing a light-emitting pixel unit on a display panel integrated with a microlens array according to some embodiments is shown. The operations (eg, steps) of method 400 may correspond to Figure 1 The embodiments described in are implemented.

[0078] The method 400 includes step 402, providing a substrate. For example, Figure 1 A cross-sectional view of substrate 130 is shown. In some embodiments, substrate 130 is a semiconductor substrate such as silicon. In some embodiments, the material of substrate 130 is from II-III group compounds, sapphire, aluminum oxide, gallium nitride, etc.

[0079] Method 400 also includes step 404 of forming at least one mesa on the substrate. In some embodiments, the mesa is a flat-topped protrusion protruding from the substrate, having steep sides, and is formed by existing semiconductor manufacturing methods such as deposition, photolithography, and etching. In some embodiments, the shape of the mesa can be rectangular, square, triangular, trapezoidal, polygonal, etc. In some embodiments, the mesa includes at least one PN junction. For example, Figure 1 A cross-sectional view of the mesa 102M is shown. The substrate 130 has included an integrated array of independent pixels 112P, each pixel 112P having a corresponding pixel light source 112S located within the mesa 102M. In one embodiment, the substrate 130 also has an array of pixel driving circuits (not shown) integrated thereon that control the corresponding array of pixel light sources. Figure 4 The embodiments in the present invention take this structure as a starting point, and this structure is called a lens-free display panel 110. Figure 1 shown.

[0080] Method 400 also includes step 406 of depositing a layer of microlens material directly on top of at least one mesa and placing the layer of microlens material in direct physical contact with the mesa. Figure 1 As shown in , the shape of the microlens material layer conforms to the shape of the mesa 102M and forms a hemisphere on the mesa. In some embodiments, the top of the mesa 102M is approximately flat, and the shape of the formed microlens 122M is approximately hemispherical. In some embodiments, the microlens material layer is directly deposited on the substrate by chemical vapor deposition (CVD) technology. In some embodiments, the deposition parameters for the CVD process are: power of about 0W to 1000W, pressure of about 100 mTorr to 2000 mTorr, temperature of about 23°C to 500°C, gas flow of about 0 to 3000 sccm (standard cubic centimeters per minute), and time of about 1 hour to 3 hours. In some embodiments, the material of the microlens material layer is a dielectric material such as silicon dioxide.

[0081] The method 400 further includes step 408 of patterning the microlens material layer to expose the electrode region ( Figure 1 ). In some embodiments, patterning the microlens material layer in step 408 includes an etching step. In some embodiments, the etching step includes the step of forming a mask on the surface of the microlens material. The etching step also includes patterning the mask by a photolithography process to form an opening in the mask and expose the microlens material layer above the electrode region of the mesa. The etching step also includes the step of etching the portion of the microlens material layer exposed by the opening with the mask in place for protection. In some embodiments, the exposed microlens material layer is etched by a wet etching method.

[0082] Figure 5 A flowchart of a method for manufacturing a light-emitting pixel unit on a display panel integrated with a microlens array according to some embodiments is shown. The operations (eg, steps) of method 500 may correspond to Figure 1 The embodiments described in are implemented.

[0083] The method 500 includes step 502, providing a substrate. For example, Figure 1 A cross-sectional view of substrate 130 is shown. In some embodiments, substrate 130 is a semiconductor substrate such as silicon.

[0084] Method 500 also includes step 504 of forming at least one mesa on the substrate. In some embodiments, the mesa is a flat-topped protrusion protruding from the substrate, having steep sides, and is formed by existing semiconductor manufacturing methods such as deposition, photolithography, and etching. In some embodiments, the shape of the mesa can be rectangular, square, triangular, trapezoidal, polygonal, etc. In some embodiments, the mesa includes at least one PN junction. For example, Figure 1 A cross-sectional view of the mesa 102M is shown. The substrate 130 already includes an integrated array of independent pixels 112P, each pixel 112P having a corresponding pixel light source 112S located within the mesa 102M. In one embodiment, the substrate 130 also has an array of pixel driving circuits (not shown) integrated thereon that control the corresponding array of pixel light sources. Figure 5 The embodiments in the present invention are based on this structure, which is called a lens-free display panel 110. Figure 1 shown.

[0085] In some embodiments, method 500 further includes an optional step 506 of forming a marking layer having a mark for alignment with a deposited microlens material layer in a subsequent step. For example, the marking layer is formed to align the light-emitting pixel unit with the microlens material layer so as to form a microlens at the center of the light-emitting pixel. In some embodiments, the marking layer is formed to align the mesa with the layer above it, especially the microlens material layer, so as to form a microlens on the top of the mesa.

[0086] The method 500 also includes step 508 of depositing a layer of microlens material directly on top of the at least one mesa. Figure 6A-6B Further shown is a method for manufacturing a display panel integrated with a microlens array using top-down pattern transfer according to some embodiments. Fig. 6A As shown, the microlens material layer 645 covers the top of the mesa 602M, and the top surface of the microlens material layer 645 is flat. In some embodiments, the microlens material layer 645 is deposited on the top of the mesa array 602 by spin coating. In some embodiments, the material of the microlens material layer 645 is photoresist. In some embodiments, the material of the microlens material layer 645 is a dielectric material such as silicon oxide.

[0087] The method 500 further includes step 510 of patterning the microlens material layer from top to bottom to form at least one hemisphere in the microlens material layer, such as Figure 6A-6B In some embodiments, the patterning step does not need to penetrate or etch to the bottom of the microlens material layer 645. In some embodiments, the hemisphere of the microlens 620 is disposed above the at least one mesa 602M.

[0088] In some embodiments, step 510 further includes a first step of depositing a mask layer 630 on the surface of the microlens material layer 645, such as Fig. 6A as shown in .

[0089] Step 510 also includes a second step of patterning the mask layer 630 to form a hemispherical pattern in the mask layer 630. In some examples, the mask layer 630 is first patterned by a photolithography process and then by a reflow process. In some embodiments, the photosensitive polymer mask layer 630 is patterned into separate units 640, such as in Fig. 6A As shown in the dotted rectangular unit, preparation is made for the formation of a hemispherical pattern. As an example, the separation unit 640 is patterned and formed by a photolithography process. The patterned photosensitive polymer mask layer 650 having the separation unit 640 is then subjected to a high temperature reflow process to form a hemispherical pattern 660. In one method, the separation unit 640 is subjected to a high temperature reflow process to form a separated hemispherical pattern 660. In some embodiments, the hemispherical pattern 660 separated by one pixel is not in direct physical contact with the hemispherical pattern of an adjacent pixel. In some embodiments, the hemispherical pattern 660 of one pixel is only in contact with the hemispherical pattern of an adjacent pixel at the bottom of the hemispherical pattern 660. The patterned photosensitive polymer mask layer 650 is heated to a temperature above the melting point of the polymer material for a certain time. After the polymer material melts to a liquefied state, the surface tension of the liquefied material causes it to become a shape with a smooth curvature surface. For a unit with a circular base radius R, when the height of the unit is 2R / 3, a hemispherical shape / pattern will be formed after the reflow process. Fig. 6AA display panel with an array of hemispherical patterns 660 integrated therein after the high temperature reflow process is completed is shown. In some embodiments, the hemispherical patterns in the mask layer can be formed by other manufacturing methods, including the manufacturing method of the microlens described in method 400. In some other embodiments, the hemispherical patterns in the mask layer can be formed using grayscale mask lithography exposure. In some other embodiments, the hemispherical patterns in the mask layer can be formed via a molding / imprinting process.

[0090] Step 510 also includes a third step of etching the microlens material layer 645 using the hemisphere pattern 660 as a mask to form a hemisphere in the microlens material layer 645. In some examples, etching the microlens material layer 645 is performed by a photolithography process. In some examples, etching the microlens material layer 645 is performed by dry etching such as a plasma etching process 635, such as Fig. 6A In some embodiments, after the microlens material layer 645 is etched, the microlens material layer 645 is not etched through to expose the top surface of the mesa 602M, as shown in FIG. Figure 6A-6B As shown, the spacer 670 is formed on the top of the mesa 602M or covers the top of the mesa 602M, as shown in FIG. Figure 6B shown.

[0091] The method 500 further includes step 512 of patterning the microlens material layer to expose the electrode region of the substrate (at Figure 6B ). In some embodiments, the patterning of the microlens material layer in step 512 includes an etching step. In some embodiments, the etching step includes the step of forming a mask on the surface of the microlens material. The etching step also includes the step of patterning the mask by a photolithography process to form an opening in the mask and exposing the microlens material layer above the electrode region of the mesa. The etching step further includes the step of etching the exposed microlens material layer under the protection of the mask. In some embodiments, the exposed microlens material layer is etched by a wet etching method. In some embodiments, the opening of the electrode is provided outside the display array region.

[0092] As mentioned above, Figure 1 , 4 , 5, 6A and 6B show various manufacturing methods to form a display panel integrated with a microlens array. It should be understood that these are only examples and other manufacturing techniques may also be used.

[0093] Although the detailed description contains many details, these should not be construed as limiting the scope of the invention, but merely as illustrating different examples and aspects of the invention. It should be understood that the scope of the invention includes other embodiments not discussed in detail above. For example, microlenses with bases of different shapes, such as square bases or other polygonal bases, may also be used. Various other modifications, changes and variations that are obvious to those skilled in the art may be made in the layout, operation and details of the methods and apparatus of the invention disclosed herein without departing from the spirit and scope of the invention as defined in the appended claims. Therefore, the scope of the invention shall be determined by the appended claims and their legal equivalents.

[0094] Other embodiments also include Figure 1 , 2A Various subsets of the above-described embodiments shown in , 2B, 3A, 3B, 4, 5, 6A, and 6B may be combined or otherwise rearranged in various other embodiments.

[0095] Figure 7 7 is a top view of a micro LED display panel 700 according to some embodiments. The display panel 700 includes a data interface 710, a control module 720, and a pixel area 750. The data interface 710 receives data that defines an image to be displayed. The source and format of this data will vary depending on the application. The control module 720 receives input data and converts it into a form suitable for driving pixels in the display panel. The control module 720 may include: digital logic and / or a state machine to convert from the received format to a format suitable for the pixel area 750; a shift register or other type of buffer and memory to store and transmit data; a digital-to-analog converter and a level converter; and a scan controller including a clock circuit.

[0096] The pixel region 750 includes a mesa array including pixels ( Figure 7 The pixel includes, for example, a micro-LED such as a single-color or multi-color LED 734 integrated with a pixel driver as described above. Figure 7 The LED 734 is not shown individually in the LED 734 in the example. In this example, the display panel 700 is a color RGB display panel. It includes red, green and blue pixels. In each pixel, the LED 734 is controlled by a pixel driver. According to the previously shown embodiment, the pixel is in contact with a power supply voltage (not shown), in contact with ground through a ground pad 736, and also in contact with a control signal. Although in Figure 7Not shown, the P electrode of LED 734 and the output of the driving transistor are electrically connected. The LED current drive signal connection (between the P electrode of the LED and the output of the pixel driver), the ground connection (between the n electrode and the system ground), the power supply voltage Vdd connection (between the source of the pixel driver and the system Vdd), and the control signal connection to the pixel driver gate are made according to various embodiments. Any microlens array disclosed herein can be implemented with the micro LED display panel 700.

[0097] Figure 7 The drawings are representative only. Other designs will be apparent. For example, the colors do not have to be red, green, and blue. Nor do they have to be arranged in rows or strips. As an example, Figure 7 In addition to the square matrix layout of pixels shown in , a hexagonal matrix layout of pixels may also be used to form the display panel 700.

[0098] In some applications, a fully programmable rectangular pixel array is not necessary. Other designs of display panels and displays with a variety of shapes can also be formed using the device structures described herein. One class of examples is professional applications, including signage and automotive. For example, multiple pixels can be laid out in a star or spiral shape to form a display panel, and different patterns on the display panel can be generated by turning LEDs on and off. Another professional example is automotive headlights and smart lighting, where certain pixels are grouped together to form various lighting shapes, and each group of LED pixels can be turned on or off or otherwise adjusted by individual pixel drivers.

[0099] Even the lateral layout of the devices within each pixel can vary. Figure 1 , 6A In 6B, the LEDs and pixel drivers are arranged vertically, i.e., each LED is located on top of the corresponding pixel driver circuit. Other layouts are also possible. For example, the pixel driver circuit can also be located "behind", "in front of" or "beside" the LED.

[0100] Different types of display panels can be manufactured. For example, the resolution of a display panel can typically range from 8×8 to 3840×2160. Common display resolutions include QVGA with a resolution of 320×240 and an aspect ratio of 4:3, XGA with a resolution of 1024×768 and an aspect ratio of 4:3, D with a resolution of 1280×720 and an aspect ratio of 16:9, FHD with a resolution of 1920×1080 and an aspect ratio of 16:9, UHD with a resolution of 3840×2160 and an aspect ratio of 16:9, and 4K with a resolution of 4096×2160. There can also be a wide variety of pixel sizes, ranging from sub-micron and below to 10mm and above. The size of the overall display area can also vary widely, ranging from as small as a few tens of microns or less on the diagonal to hundreds of inches or more.

[0101] Different applications will also have different requirements for optical brightness and viewing angle. Example applications include direct-view displays, light engines for home / office projectors and portable electronics such as smartphones, laptops, wearable electronics, AR and VR glasses, and retinal projection. Power consumption can range from as low as a few milliwatts for retinal projectors to as high as kilowatts for large-screen outdoor displays, projectors, and smart car headlights. In terms of frame rate, due to the fast response of inorganic LEDs (nanoseconds), the frame rate can be as high as KHz, or even MHz for small resolutions.

[0102] Other embodiments also include the following: Figure 1 , 2A , 2B, 3A, 3B, 4, 5, 6A, 6B and 7 are combined and otherwise rearranged in various other embodiments.

[0103] Although the specific description contains many details, these should not be construed as limiting the scope of the invention, but merely illustrating different examples and aspects of the invention. It should be understood that the scope of the invention includes other embodiments not discussed in detail above. For example, the above method can be applied to the integration of non-LED and OLED functional devices with non-pixel driver control circuits. Examples of non-LED devices include vertical cavity surface emitting lasers (VCSELs), photodetectors, micro-electromechanical systems (MEMS), silicon photonic devices, power electronic devices, and distributed feedback lasers (DFBs). Examples of other control circuits include current drivers, voltage drivers, transimpedance amplifiers, and logic circuits.

[0104] The foregoing description of the disclosed embodiments is provided to enable making or using the embodiments described herein and variations thereof. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein may be applied to other embodiments without departing from the spirit or scope of the subject matter disclosed herein. Therefore, the present disclosure is not intended to be limited to the embodiments shown herein, but will conform to the widest scope consistent with the following claims and the principles and novel features disclosed herein.

[0105] Features of the present invention can be implemented by using a computer program product or with the help of a computer program product, such as a storage medium (multiple media) or a computer-readable storage medium (multiple media), wherein or thereon instructions are stored, and these instructions can be used to program a processing system to perform any features presented herein. Storage media can include, but are not limited to, high-speed random access memory, such as DRAM, SRAM, DDRRAM or other random access solid-state memory devices, and can include non-volatile memory, such as one or more magnetic disk storage devices, optical disk storage devices, flash memory devices or other non-volatile solid-state storage devices. Memory optionally includes one or more storage devices located away from the CPU. Memory or optionally non-volatile memory devices in memory include non-temporary computer-readable storage media.

[0106] Features of the present invention stored on any machine-readable medium(s) may be embodied in software and / or firmware for controlling the hardware of a processing system and for enabling the processing system to interact with other mechanisms utilizing the results of the present invention. Such software or firmware may include, but is not limited to, application code, device drivers, operating systems, and execution environments / containers.

[0107] It should be understood that although the terms "first", "second", etc. may be used herein to describe various elements or steps, these elements or steps should not be limited by these terms. These terms are only used to distinguish one element or step from another element or step.

[0108] The terms used herein are only used for the purpose of describing specific embodiments and are not intended to limit the claims. As used in the description of the embodiments and the appended claims, the singular forms "one", "an" and "the" are intended to also include multiple forms unless the context clearly indicates otherwise. It should also be understood that the term "and / or" as used herein refers to and includes any and all possible combinations of one or more related listed items. It should also be understood that the terms "including" and / or "comprising" when used in this specification specify the presence of said features, integers, steps, operations, elements and / or parts, but do not prevent the presence or addition of one or more other features, integers, steps, operations, elements, parts and / or groups.

[0109] As used herein, the term "if" may be interpreted to mean "under the circumstances," "when," or "in response to detecting," the stated antecedent is true, depending on the context. Similarly, the phrase "if it is determined that [that stated antecedent is true]" or "if [the stated antecedent is true]" or "when [the stated antecedent is true]" may be interpreted to mean "upon determination" or "in response to determination" or "upon determination" or "upon detection" or "in response to detection," the stated antecedent is true, depending on the context.

[0110] The foregoing description for purposes of illustration has been described with reference to specific embodiments. However, the above illustrative discussion is not intended to be exhaustive or to limit the claims to the precise forms disclosed. Many modifications and variations are possible in light of the above teachings. The embodiments are chosen and described in order to best explain the principles of practical application and operation to enable others skilled in the art to realize.

Claims

1. A method for manufacturing a light-emitting pixel unit, comprising: providing a substrate; forming at least one mesa on the substrate; as well as Depositing a microlens material layer directly on at least the top of the at least one mesa by a chemical vapor deposition process, during which the microlens material layer conforms to the shape of the at least one mesa to form at least one microlens having a hemispherical shape on the at least one mesa; in: The thickness of the microlens in the at least one microlens at the top of the center of the at least one mesa is thicker than the thickness of the microlens at the top of the edge of the mesa to reduce the divergence of the light generated by the mesa; as well as The hemispherical shape of the layer of microlens material, and the positioning of the hemispherical shape for reducing divergence of light generated by the at least one mesa, are formed during deposition by a chemical vapor deposition process.

2. The method for manufacturing a light-emitting pixel unit according to claim 1, wherein: The material of the microlens material layer is different from the material of the at least one mesa.

3. The method for manufacturing a light-emitting pixel unit according to claim 1, wherein: Microlenses are individually formed around the tops of the mesas during deposition by a chemical vapor deposition process.

4. The method for manufacturing a light-emitting pixel unit according to claim 1, wherein: A spacer is formed between the at least one mesa and the microlens by the same layer of microlens material.

5. The method for manufacturing a light-emitting pixel unit according to claim 4, wherein: The material of the spacer is the same as that of the microlens.

6. The method for manufacturing a light-emitting pixel unit according to claim 1, wherein: The microlenses are composed of dielectric materials.

7. The method for manufacturing a light-emitting pixel unit according to claim 1, wherein: The material of the microlens is photoresist.

8. The method for manufacturing a light-emitting pixel unit according to claim 1, wherein: The height of the microlenses does not exceed 1 micron.

9. The method for manufacturing a light-emitting pixel unit according to claim 1, wherein: The width of the microlens does not exceed 3 microns.

10. The method for manufacturing a light-emitting pixel unit according to claim 1, wherein: On the substrate, the mesas are in a matrix of mesa arrays, and the microlenses are in a matrix of microlens arrays, which are deposited according to the layout of the mesa arrays during a chemical vapor deposition process and formed into a hemispherical shape.

11. The method for manufacturing a light-emitting pixel unit according to claim 1, wherein: When the top of the mesa is flat, the shape of the microlens is hemispherical.

12. The method for manufacturing a light-emitting pixel unit according to claim 1, wherein: The at least one mesa includes at least one light emitting device.

13. The method for manufacturing a light-emitting pixel unit according to claim 1, wherein: The parameters of the chemical vapor deposition process for depositing the microlens material layer and forming a hemispherical shape on the at least one mesa include: power less than 1000 W, pressure between 100 mTorr and 2000 mTorr, temperature between 23° C. and 500° C., gas flow rate less than 3000 sccm, and time between 1 hour and 3 hours.

14. The method for manufacturing a light-emitting pixel unit according to claim 1, further comprising: The microlens material layer is patterned to expose the electrode region of the substrate.

15. The method for manufacturing a light-emitting pixel unit according to claim 14, wherein the patterning further comprises: forming a mask on a surface of the microlens material; patterning the mask by a photolithography process to form an opening in the mask and expose the microlens material layer above the electrode region of the at least one mesa; as well as Under the protection of the mask, the portion of the microlens material layer exposed by the opening is etched.

16. The method for manufacturing a light-emitting pixel unit according to claim 15, wherein: Etching is a wet etching method.

17. The method for manufacturing a light-emitting pixel unit according to claim 1, wherein: The height of the at least one microlens does not exceed 2 microns, and the width of the at least one microlens does not exceed 4 microns.

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