Microdisplay device and method of fabrication

Abstract

The present application relates to a kind of micro display devices and preparation method.The micro display device includes driving backplate, first layer and second layer pixel layer;Parent pixel includes multiple subpixels, and the top end of each subpixel is respectively electrically connected to corresponding second electrode contact through top conductive layer, and the bottom end of multiple subpixels is interconnected to form bottom common electrode structure through bottom conductive layer;Gap region is formed between two adjacent subpixels in first layer pixel layer, and common electrode conductor is passed through inside the gap region;The light emitted by any one of the two adjacent subpixels forming gap region at least partially emits via the peripheral of the upper subpixel that common electrode conductor is electrically connected in the gap region inside.The present application also discloses a kind of preparation method.The present application can effectively improve the light efficiency and reliability of micro display device.

Description

Microdisplay devices and their fabrication methods Technical Field

[0001] This invention relates to the field of semiconductor technology, and in particular to a microdisplay device and its fabrication method. Background Technology

[0002] Microdisplay devices, characterized by their small size, high resolution, and high brightness, can be applied in numerous fields such as AR / VR devices, automotive displays, medical detection, and smart wearables. Micro-LED and Micro-OLED technologies, in particular, have seen widespread development in recent years. Micro-LED technology, with its advantages of high efficiency, low power consumption, high density, and high stability, is considered one of the most promising next-generation display and light-emitting devices. In the field of microdisplays, to further ensure pixel size and density, multi-color stacking integration is required for color displays. Multi-layer stacked LED devices typically have a driving backplane (with driving circuitry) and multiple layers above it. Pixels are arranged in each layer, and each pixel needs to be electrically connected to the driving backplane. This results in a complex overall structure, significant loss of light-emitting area for each pixel, hindering optimal light distribution, and increasing overall power consumption, which is detrimental to the reliability and stability of LED display devices. Summary of the Invention

[0003] Therefore, the technical problem to be solved by the present invention is to improve the light efficiency and reliability of micro-display devices in the prior art.

[0004] To address the aforementioned technical problems, the present invention provides a microdisplay device, comprising,

[0005] A drive backplate, wherein a second type of electrode contact is provided on the drive backplate;

[0006] The first pixel layer is stacked on top of the driving backplane;

[0007] The second pixel layer is stacked on top of the first pixel layer;

[0008] A mother pixel, which includes multiple sub-pixels, wherein some of the sub-pixels are located in the first pixel layer and the remaining sub-pixels are located in the second pixel layer;

[0009] The top of each of the plurality of sub-pixels is electrically connected to the corresponding second type of electrode contact through a top conductive layer, and the bottom ends of the plurality of sub-pixels are interconnected through a bottom conductive layer to form a bottom common electrode structure.

[0010] In the first pixel layer, a gap region is formed between two adjacent sub-pixels. A common electrode conductor passes through the gap region. The bottom conductive layers at the bottom ends of the two adjacent sub-pixels forming the gap region are electrically interconnected. The bottom end of the common electrode conductor inside the gap region is electrically connected to the bottom conductive layer at the bottom end of either of the two adjacent sub-pixels forming the gap region, and the top end is electrically connected to the bottom conductive layer of the other sub-pixel in the second pixel layer. Light emitted by either of the two adjacent sub-pixels forming the gap region is emitted at least partially through the periphery of the upper sub-pixel electrically connected to the common electrode conductor inside the gap region.

[0011] In one embodiment of the present invention, a color conversion layer is further disposed above the first pixel layer, and the color conversion layer is located on the light emission path of the corresponding sub-pixel in the first pixel layer.

[0012] In one embodiment of the present invention, the color conversion layer is provided on the light-emitting path of one of the two adjacent sub-pixels forming the gap region, while the color conversion layer is not provided on the light-emitting path of the other.

[0013] In one embodiment of the invention, the projection area of ​​the upper sub-pixel electrically connected to the common conductive element inside the gap region on the driving backplate is at least partially located inside the projection area of ​​the gap region on the driving backplate.

[0014] In one embodiment of the present invention, the projection area of ​​the upper sub-pixel electrically connected to the common conductive element inside the gap region on the driving back plate is completely located inside the projection area of ​​the gap region on the driving back plate.

[0015] In one embodiment of the present invention, the microdisplay device further includes a first type of electrode contact, the first type of electrode contact and the second type of electrode contact having opposite polarities, and the bottom conductive layer at the bottom end of any one of two adjacent sub-pixels forming the gap region is electrically connected to at least one of the first type of electrode contacts.

[0016] In one embodiment of the present invention, the bottom ends of two adjacent sub-pixels forming the gap region share a bottom conductive layer, the bottom surface of the shared bottom conductive layer is electrically connected to the corresponding first type of electrode contact, and the top surface is electrically connected to the common electrode conductive element inside the gap region.

[0017] In one embodiment of the present invention, a bottom ohmic contact layer is further provided between the bottom ends of two adjacent sub-pixels forming the gap region and the shared bottom conductive layer, and the bottom ohmic contact layer is penetrated by the common conductive element inside the gap region.

[0018] In one embodiment of the present invention, the bottom end of the common electrode conductive element inside the gap region is in contact with the corresponding first type of electrode contact to achieve electrical connection, and the bottom conductive layer of the bottom end of the two adjacent sub-pixels forming the gap region is electrically connected to the first type of electrode contact at the bottom end of the common electrode conductive element.

[0019] In one embodiment of the present invention, the top conductive layer of each sub-pixel is electrically connected to the corresponding second type of electrode contact via a non-common conductive element.

[0020] In one embodiment of the present invention, the bottom end of the non-common conductive element is in direct contact with the corresponding second type of electrode contact.

[0021] In one embodiment of the present invention, the gap region includes an annular region, in which the common conductive element is disposed, and each of the sidewalls of two adjacent sub-pixels forming the gap region has a groove, and the grooves of the two adjacent sub-pixels enclose the annular region.

[0022] In one embodiment of the present invention, the bottom conductive layer is a metal bonding layer.

[0023] In one embodiment of the invention, at least one of the sub-pixels is surrounded by a first peripheral metal fence, and the first peripheral metal fence and the sidewall of the surrounded sub-pixel are insulated and isolated by a first insulating layer.

[0024] In one embodiment of the present invention, the bottom ends of two adjacent sub-pixels forming the gap region share a bottom conductive layer, and a first peripheral metal fence is formed on the upper part of the shared bottom conductive layer, and the two adjacent sub-pixels forming the gap region are surrounded by a first peripheral metal fence.

[0025] In one embodiment of the present invention, a first insulating filling area is provided inside the gap region, and the common electrode conductive element inside the gap region directly passes through the first insulating filling area.

[0026] In one embodiment of the present invention, the driving backplate is divided into a display area, all the mother pixels constitute a pixel array, the projection of the pixel array on the driving backplate is located inside the display area, a first type of electrode contact is provided inside the display area, and / or a first type of electrode contact is provided outside the display area.

[0027] In one embodiment of the present invention, the top of each of the sub-pixels located in the first pixel layer and the second pixel layer of the mother pixel is separately provided with the top conductive layer, and the top conductive layer in the first pixel layer is located above the electrically connected sub-pixel, and the top conductive layer in the second pixel layer is located above the electrically connected sub-pixel.

[0028] In one embodiment of the invention, at least one of the top conductive layers is electrically connected to a metal reinforcement.

[0029] In one embodiment of the present invention, the top of each of the sub-pixels located in the first pixel layer and the second pixel layer of the mother pixel is separately provided with the top conductive layer, and the top conductive layer in the first pixel layer is completely located above the electrically connected sub-pixels, and the top conductive layer in the second pixel layer is completely located above the electrically connected sub-pixels.

[0030] In one embodiment of the present invention, at least two of the sub-pixels emit different colors, one of the sub-pixels is located in the first pixel layer, and the other sub-pixel is located in the second pixel layer.

[0031] This invention also discloses a method for fabricating a microdisplay device, comprising,

[0032] A drive backplane is provided, wherein a second type of electrode contact is provided on the drive backplane;

[0033] Two pixel layers are stacked sequentially from bottom to top above the driving backplane. When stacking each pixel layer, the pixel layer is etched to obtain sub-pixels. The two pixel layers are the first pixel layer and the second pixel layer, respectively. Both the first pixel layer and the second pixel layer are compound semiconductor layers, so that each parent pixel includes multiple sub-pixels. Some of the sub-pixels are located in the first pixel layer, and the remaining sub-pixels are located in the second pixel layer.

[0034] This ensures that the top of each sub-pixel in the mother pixel is electrically connected to the corresponding second type of electrode contact through the top conductive layer, and the bottom ends of the multiple sub-pixels are interconnected through the bottom conductive layer to form a bottom common electrode structure.

[0035] In the first pixel layer, a gap region is formed between two adjacent sub-pixels. A common electrode conductor passes through the gap region. The bottom conductive layers at the bottom ends of the two adjacent sub-pixels forming the gap region are electrically interconnected. The bottom end of the common electrode conductor inside the gap region is electrically connected to the bottom conductive layer at the bottom end of either of the two adjacent sub-pixels forming the gap region, and the top end is electrically connected to the bottom conductive layer of the other sub-pixel in the second pixel layer. Light emitted by either of the two adjacent sub-pixels forming the gap region is emitted at least partially through the periphery of the upper sub-pixel electrically connected to the common electrode conductor inside the gap region.

[0036] The technical solution of the present invention has the following advantages compared with the prior art:

[0037] The micro-display device described in this invention can effectively reduce the obstruction of the light-emitting surface of the lower sub-pixel, ensure the effective light-emitting area of ​​the lower sub-pixel, reduce energy waste, and improve the light distribution effect. At the same time, the color conversion layer is used to realize the conversion of the light-emitting color of the sub-pixel, which is more conducive to achieving the best color display effect and can effectively improve the light efficiency and reliability of the display device. Attached Figure Description

[0038] To make the content of this invention easier to understand, the invention will be further described in detail below with reference to specific embodiments and accompanying drawings.

[0039] Figure 1 is a schematic diagram of the structure of the first micro-display device of the present invention;

[0040] Figure 2 is a schematic diagram of the arrangement of each sub-pixel in Figure 1 (top view);

[0041] Figure 3 is a schematic diagram (top view) of the arrangement of the top electrode layer of each sub-pixel in Figure 1.

[0042] Figure 4 is a schematic diagram of the bonding between the driving backplate and the first pixel layer in this invention.

[0043] Figure 5 is a flowchart of the fabrication process of the microdisplay device shown in Figure 1;

[0044] Figure 6 is a schematic diagram of the structure of the second type of microdisplay device of the present invention;

[0045] Figure 7 is a schematic diagram (top view) of the distribution of the display area in this invention;

[0046] Figure 8 is a schematic diagram (top view) of the connection between the peripheral electrode contact area and the interface in this invention.

[0047] Figure 9 is a schematic diagram of the structure of the third type of micro-display device of the present invention;

[0048] Explanation of reference numerals in the instruction manual:

[0049] 10. Drive backplane; 101. First type of electrode contact; 102. Second type of electrode contact; 103. Display area; 104. Peripheral electrode contact area; 105. Interface;

[0050] 20. First pixel layer;

[0051] 30. Second pixel layer;

[0052] 40. Color transfer layer;

[0053] 50. Subpixel;

[0054] 60. Top conductive layer;

[0055] 70. Bottom conductive layer;

[0056] 80. Non-common conductive components;

[0057] 90. Common electrode conductive component;

[0058] 100. First insulation filling area;

[0059] 140. First outer metal fence; 150. First insulation layer; 160. Second insulation layer; 180. Bottom ohmic contact layer; 190. Metal reinforcement; 230. Etching barrier layer; 300. Gap area; 3001. Annular area; 3002. Groove portion; Detailed Implementation

[0060] The present invention will be further described below with reference to the accompanying drawings and specific embodiments, so that those skilled in the art can better understand and implement the present invention. However, the embodiments described are not intended to limit the present invention. Obviously, the described embodiments are only some embodiments of this disclosure, and not all embodiments. The following description of at least one exemplary embodiment is merely illustrative and is in no way intended to limit the present disclosure or its application or use.

[0061] In the description of this invention, it should be understood that the terms "vertical," "upper," "lower," "top," "side," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing the invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the invention. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this invention, unless otherwise stated, "a plurality of" means two or more.

[0062] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0063] Traditional LED devices using multi-layer stacking have complex overall structures, resulting in significant loss of light-emitting area for each pixel, which prevents the achievement of optimal light distribution and leads to higher power consumption, thus compromising the reliability and stability of LED display devices. In view of this, this application provides a micro-display device to improve the above-mentioned problems, thereby better ensuring the photoelectric performance and reliability of LED display devices.

[0064] It should be noted that, in this application, the compound semiconductor layer refers to a layer structure with a certain thickness prepared from compound semiconductor materials. Compound semiconductors generally refer to compounds formed from two or more elements, including crystalline inorganic compounds (such as III-V and II-VI compound semiconductors) and oxide semiconductors. The compound semiconductors involved in this application are mainly epitaxial materials for light-emitting diodes, such as InGaN ternary material systems or AlGaInP quaternary material systems, whose emission wavelengths can cover the entire spectrum from ultraviolet, visible, and infrared light. Their substrate materials can be GaN, Si, SiC, Sapphire, GaAs, InP, etc.

[0065] Taking the Micro-LED field as an example, some compound semiconductor materials involved in this application are shown in Table 1. In some practical applications, the film layers of compound semiconductors are more complex, or there are cases where materials are used interchangeably. Typical compound semiconductors mainly include P-type semiconductor materials, N-type semiconductor materials, and MQW active quantum wells and other functional layers (barrier layers, confinement layers, waveguide layers, buffer layers, etc.) sandwiched between the two:

[0066] Table 1. Material Table of Film Layers for Compound Semiconductors

[0067]

[0068] The structure of the microdisplay device of this application will be further described below with reference to the following specific embodiments.

[0069] Example 1

[0070] Referring to Figure 1, this embodiment discloses a multi-layer stacked micro-display device, including at least one mother pixel, each mother pixel having multiple (two or more) sub-pixels. The structure of the above-mentioned micro-display device is specifically described below using a mother pixel with two sub-pixels as an example. The structure shown in the figure only shows the case of one mother pixel. When there are multiple mother pixels, the internal structure of each mother pixel is basically the same.

[0071] In this application, the micro-display device has a Z-direction, an X-direction, and a Y-direction, which are perpendicular to each other. The Z-direction is the stacking direction of each layer of sub-pixels, that is, the up and down direction, which can also be understood as the direction away from / closer to the driving backplate. Here, "height" or "up and down" or "top and bottom" are all in the Z-direction.

[0072] In this invention, "bottom end of sub-pixel" refers to the end of the sub-pixel that is close to the driving backplate, and "top end of sub-pixel" refers to the end of the sub-pixel that is away from (away from) the driving backplate.

[0073] It should be noted that the cross-sectional views in the XZ plane in the accompanying drawings of this invention can be schematic diagrams after cutting a single cross section or schematic diagrams after cutting multiple cross sections together, in order to show the connection situation of different electrode contacts.

[0074] The LED display device in this embodiment includes a driving backplate 10 and a mother pixel, the mother pixel including a plurality of sub-pixels 50.

[0075] The driving backplate 10 is a component with a driving circuit. The first type of electrode contact 101 and the second type of electrode contact 102 are the lead-out terminals of the driving circuit, used to electrically connect the driving circuit and the sub-pixel 50. The sub-pixel 50 is a light-emitting element. Through the electrical connection between the driving backplate 10 and the sub-pixel 50, the connection between the sub-pixel 50 and the driving circuit is realized, thereby driving the sub-pixel 50 to emit light. This allows each sub-pixel 50 to be driven individually and emit light independently.

[0076] The aforementioned driving backplane 10 includes, but is not limited to, a CMOS (Complementary Metal Oxide Semiconductor) driving backplane.

[0077] The driving backplate 10 may be provided with a first type of electrode contact 101 and a second type of electrode contact 102. The polarities of the first type of electrode contact 101 and the second type of electrode contact 102 are opposite, with one being the anode and the other the cathode. Understandably, in order to prevent short circuits, the first type of electrode contact 101 and the second type of electrode contact 102 need to be insulated from each other. Through the provision of the first type of electrode contact 101 and the second type of electrode contact 102, the driving backplate 10 can be electrically connected to the sub-pixel 50, thereby controlling the light emission of each sub-pixel 50 using the driving backplate 10.

[0078] Understandably, the two ends of sub-pixel 50 along the Z direction are the bottom and the top, respectively; the bottom and top of sub-pixel 50 are the two ends with opposite polarities. Sub-pixel 50 includes a P-type semiconductor layer, an active layer and an N-type semiconductor layer arranged sequentially along the Z direction. The active layer is used to emit light. The top of sub-pixel 50 is the end where the N-type semiconductor layer is located (or the end where the P-type semiconductor layer is located - anode), and the bottom is the end where the P-type semiconductor layer is located (or the end where the N-type semiconductor layer is located - cathode), which need to be connected to electrode contacts of different polarities respectively.

[0079] Referring to Figure 1, this embodiment discloses a microdisplay device, including a driving backplane 10 and a mother pixel;

[0080] The drive backplate 10 is provided with a second type of electrode contact 102;

[0081] At least two pixel layers are stacked sequentially on top of the driving backplate 10, namely the first pixel layer 20 and the second pixel layer 30.

[0082] The first pixel layer 20 is stacked on top of the driving backplane 10;

[0083] The second pixel layer 30 is stacked on top of the first pixel layer 20;

[0084] The mother pixel includes multiple sub-pixels 50. Some of the sub-pixels 50 are located in the first pixel layer 20, and the remaining sub-pixels are located in the second pixel layer 30.

[0085] In the mother pixel: the top of each of the multiple sub-pixels 50 is electrically connected to the corresponding second type electrode contact 102 through the top conductive layer 60, and the bottom ends of the multiple sub-pixels 50 are interconnected through the bottom conductive layer 70 to form a bottom common pole structure; that is, the bottom conductive layers 70 of each sub-pixel 50 in the bottom common pole structure are electrically connected together and conduct electricity to each other.

[0086] Furthermore, a gap region 300 is formed between two adjacent sub-pixels 50 in the first pixel layer 20. A common-electrode conductor 90 passes through the gap region 300. The bottom conductive layers 70 at the bottom of the two adjacent sub-pixels 50 forming the gap region 300 are electrically interconnected. The bottom end of the common-electrode conductor 90 inside the gap region 300 is electrically connected to the bottom conductive layer 70 at the bottom of either of the two adjacent sub-pixels 50 forming the gap region 300, and the top end is electrically connected to the bottom conductive layer 70 of the other sub-pixel 50 in the second pixel layer 30. Light emitted from either of the two adjacent sub-pixels 50 forming the gap region 300 is at least partially emitted through the periphery of the upper sub-pixel 50 electrically connected to the common-electrode conductor 90 inside the gap region 300, without being blocked by the upper sub-pixel 50. This effectively reduces the obstruction of the light-emitting surface of the lower sub-pixels, increases the effective light-emitting area of ​​the lower sub-pixels, and facilitates optimal light distribution. As shown in Figure 1, the direction of the dashed arrow in the figure indicates the light-emitting direction of the first layer of sub-pixels.

[0087] A color conversion layer 40 can also be set above the first pixel layer 20. The color conversion layer 40 is located on the light path of the corresponding sub-pixel 50 in the first pixel layer 20 to realize the conversion of the light color emitted by the sub-pixel.

[0088] The color conversion layer 40 can be used to change the color of emitted light. For example, the emitted light color of a sub-pixel 50 is blue - a blue sub-pixel. A color conversion layer is set on the light emission path of the blue sub-pixel. When the light emitted by the blue sub-pixel hits the color conversion layer, the color conversion layer will be excited and emit another color of light. For example, the blue light emitted by the blue sub-pixel may appear red after being converted and emitted by the color conversion layer.

[0089] The color-transfer layer 40 can be made of quantum dot material or phosphor material, so that it can be excited by external light to undergo color transfer and emit light of a specific color.

[0090] It should be noted that shorter wavelength light is generally used to excite the color transfer layer to undergo color transfer and emit longer wavelength light. For example, blue light can be used to excite the color transfer layer to eventually emit red light.

[0091] By setting a color conversion layer, the color of light emitted from certain sub-pixels at the bottom layer can be changed, thereby enabling the display device to present a color display effect. It can also make the overall structure of the device simpler and easier to process.

[0092] For example, referring to Figures 1 and 2, Figure 1 can be a rotated cross-sectional view of the structure in Figure 2 along point AA; the first pixel layer 20 has two sub-pixels 50, and the gap area 300 formed between the two sub-pixels 50; the second pixel layer 30 has one sub-pixel 50. It should be noted that in Figure 2, the sub-pixel 50 located in the first pixel layer 20 is denoted as i1, and the second type electrode contact 102 connected to it is denoted as k1; the sub-pixel 50 located in the second pixel layer 30 is denoted as i2, and the second type electrode contact 102 connected to it is denoted as k2.

[0093] It should be noted that the first pixel layer in Figure 1 has two sub-pixels 50, and the second pixel layer 30 has one sub-pixel 50. Each of these three sub-pixels is connected to a top conductive layer 60. For example, referring to Figure 3, the sub-pixel 50 located in the first pixel layer 20 is denoted as i1, and the second type electrode contact 102 connected to it is denoted as k1. The sub-pixel 50 located in the second pixel layer 30 is denoted as i2, and the second type electrode contact 102 connected to it is denoted as k2. Each sub-pixel is electrically connected to its respective top conductive layer 60.

[0094] In the structure described above, a common electrode conductive element 90 is inserted inside the gap region 300 formed between two independent adjacent sub-pixels 50 in the first pixel layer 20. This allows the upper sub-pixel electrically connected to the common electrode conductive element 90 to be located above the gap region 300, effectively reducing the obstruction of the light-emitting surface of the lower sub-pixel and increasing the effective light-emitting area of ​​the lower sub-pixel, which is beneficial for achieving the best light distribution effect. At the same time, it also reduces the problem of light blocking and light absorption of the lower sub-pixel when the metal bonding layer is set at the bottom of the upper sub-pixel, thereby reducing the energy waste of the lower sub-pixel and reducing the phenomenon of the device temperature being too high due to energy loss being converted into heat. This effectively increases the light efficiency and reliability of the display device.

[0095] In addition, the sub-pixel distribution structure described above can flexibly adjust the effective light-emitting area of ​​the sub-pixels surrounding the gap area by adjusting the size of the gap area, so as to make up for the shortcomings of the light intensity of a certain sub-pixel being too bright or too dark, thereby controlling the light pattern of the multi-color stacked device to meet the different needs of XR (extended reality) applications.

[0096] As is understood, in this invention, "upper pixel layer" refers to all pixel layers located above the lowermost pixel layer, while "lower pixel layer" is the pixel layer located below the upper pixel layer. Similarly, "upper sub-pixel" refers to all sub-pixels located above the lowermost sub-pixel, while "lower sub-pixel" is the sub-pixel located below the upper sub-pixel.

[0097] Furthermore, the top conductive layer 60 of each sub-pixel is a transparent conductive layer to facilitate light transmission, allowing light emitted from the lower sub-pixel to pass through the top conductive layer 60 and shine upwards.

[0098] For example, the top conductive layer 60 is a transparent conductive layer, which may be one or more combinations of indium tin oxide (ITO), indium zinc oxide (IZO), aluminum-doped zinc oxide (AZO), Al-doped indium tin oxide, Ag-doped indium tin oxide, and Au-doped indium tin oxide.

[0099] In some implementations, referring to FIG1, in two adjacent sub-pixels 50 forming the gap region 300, a color conversion layer 40 is provided on the light-emitting path of one sub-pixel 50, while no color conversion layer is provided on the light-emitting path of the other sub-pixel 50, so that the final emitted light colors of the two are different, realizing multi-color configuration, and also making the overall structure more compact, which is conducive to improving pixel density.

[0100] For example, a subpixel that emits blue light is called a blue subpixel. A blue subpixel is set in the first pixel layer 20. A gap area 300 is formed between two adjacent blue subpixels. A red light conversion layer covers the top of a blue subpixel. The blue light emitted by the subpixel is converted into red light after being converted by the red light conversion layer. The other blue subpixel does not have a color conversion layer on top and still emits blue light.

[0101] Understandably, in this embodiment, the two adjacent sub-pixels 50 forming the gap region 300 and the upper sub-pixel 50 electrically connected to the common conductive element 90 inside the gap region 300 are arranged on opposite axes.

[0102] The shape of each sub-pixel 50 is not limited; it can be a circle, ellipse, polygon (triangle, trapezoid, rectangle, etc.) or other shapes.

[0103] In some embodiments, the common electrode conductive element 90 may be made of metals such as aluminum (Al), copper (Cu), and tungsten (W) and their corresponding adhesive or barrier layers, such as titanium (Ti), titanium nitride (TiN), tantalum nitride / copper (Ti / Cu), tantalum nitride / copper (TaN / Cu), etc.

[0104] In some embodiments, the projection area of ​​the upper sub-pixel 50 electrically connected to the common conductor 90 inside the gap region 300 on the driving back plate 10 is at least partially located inside the projection area of ​​the gap region 300 on the driving back plate 10. This allows light emitted from the lower sub-pixel to be emitted directly through the periphery of the upper sub-pixel without being blocked, effectively reducing the obstruction of the lower sub-pixel's light-emitting surface, increasing the effective light-emitting area of ​​the lower sub-pixel, and facilitating the achievement of optimal light distribution.

[0105] Understandably, the projection of sub-pixel 50 onto the driving backplate 10 refers to the entire area enclosed by the outer edge of the projection.

[0106] Furthermore, as shown in Figure 2, the projection area of ​​the upper sub-pixel 50 electrically connected to the common conductive element 90 inside the gap region 300 on the driving backplate 10 is completely located within the projection area of ​​the gap region 300 on the driving backplate 10. This allows the light emitted by the sub-pixels outside the gap region to be emitted entirely through the periphery of the upper sub-pixels without being blocked, minimizing the obstruction of the light-emitting surface of the lower sub-pixels, maximizing the effective light-emitting area of ​​the lower sub-pixels, and further improving the light distribution effect. It also prevents the light emitted by the lower sub-pixels from being absorbed by the opaque bonding layer of the upper sub-pixels, thus preventing energy loss.

[0107] In some embodiments, as shown in FIG1, the microdisplay device further includes a first type of electrode contact 101, the first type of electrode contact 101 and the second type of electrode contact 102 having opposite polarities, and the bottom conductive layer 70 at the bottom end of any one of two adjacent sub-pixels 50 forming the gap region 300 is electrically connected to at least one first type of electrode contact 101.

[0108] Furthermore, the bottom ends of two adjacent sub-pixels 50 forming the gap region 300 share a bottom conductive layer 70. The bottom surface of the shared bottom conductive layer 70 is electrically connected to the corresponding first type electrode contact 101, and the top surface is electrically connected to the common electrode conductive member 90 inside the gap region 300.

[0109] In a specific configuration, the common conductive element 90 inside the gap region 300 can be made to contact the aforementioned shared bottom conductive layer 70 at the bottom ends of the two adjacent sub-pixels 50 forming the gap region 300 to form an electrical connection.

[0110] In some implementations, the top conductive layer 60 of each sub-pixel 50 is electrically connected to the corresponding second type electrode contact 102 via a non-common conductive element 80.

[0111] Furthermore, the bottom end of the non-common conductive element 80 is in direct contact with the corresponding second type electrode contact 102.

[0112] The material of the non-common conductive component 80 can be the same as that of the common conductive component 90.

[0113] Furthermore, if the overall structure formed by two adjacent sub-pixels 50 forming the gap region 300 is called the first structure, the non-common conductive element 80 connected to the top conductive layer 60 of the upper sub-pixel 50 electrically connected to the common conductive element 90 inside the gap region 300 is located on the periphery of the first structure, and the non-common conductive element 80 connected to the top conductive layer 60 of any one of the two adjacent sub-pixels 50 forming the gap region 300 is also located on the periphery of the first structure.

[0114] The second type of electrode contact 102, which is electrically connected to the upper sub-pixel 50 of the common conductive element 90 inside the gap region 300 and to any one of the two adjacent sub-pixels 50 forming the gap region 300, is also located on the periphery of the first structure. It can be understood that the second type of electrode contact 102 is also located outside the gap region 300 at this time.

[0115] Furthermore, the non-common conductive element 80 corresponding to each sub-pixel 50 passes through the first pixel layer 20 and is electrically connected to the corresponding second type electrode contact 102. Each non-common conductive element 80 in the first pixel layer 20 is surrounded by an insulating medium to insulate and isolate it from the sidewalls of the adjacent sub-pixel 50, so as to avoid short circuits in the adjacent sub-pixels themselves.

[0116] In some embodiments, referring to FIG2, the gap region 300 includes an annular region 3001, within which a common-polarity conductive element 90 is disposed. Each adjacent sub-pixel 50 forming the gap region 300 has a groove 3002 on its sidewall, and the grooves 3002 of adjacent sub-pixels 50 together form the annular region 3001. This method is more conducive to ensuring the placement of the non-common-polarity conductive element 80, while also making the overall structure more compact and improving pixel density.

[0117] Furthermore, the aforementioned groove portion 3002 is arc-shaped, but other shapes may also be used.

[0118] In some implementations, the bottom conductive layer 70 at the bottom of the sub-pixel 50 may be a non-metallic conductive layer.

[0119] In some implementations, the bottom conductive layer 70 at the bottom of the sub-pixel 50 may be a metal bonding layer.

[0120] Furthermore, a metal fence may be installed on the upper part of the metal bonding layer, or no metal fence may be installed.

[0121] When a metal fence is available, the following methods can be used:

[0122] At least one sub-pixel 50 is surrounded by a first peripheral metal fence 140, and the first peripheral metal fence 140 and the sidewalls of the surrounded sub-pixel 50 are insulated and isolated by a first insulating layer 150 to avoid short circuits inside the sub-pixel.

[0123] For example, the first insulating layer 150 may be made of one or more materials selected from silicon oxide, aluminum oxide, silicon nitride, titanium oxide, hafnium oxide, tantalum oxide, niobium oxide, aluminum nitride, or gallium nitride;

[0124] In some designs, the thickness of the first insulating layer 150 can be 5 nm to 2 μm.

[0125] In this design, the metal bonding layer at the bottom of the sub-pixel 50 and the first peripheral metal fence 140 are integrally formed. The metal bonding layer will sputter to form the metal fence during the etching process, thereby achieving integral forming; or, the metal bonding layer at the bottom of the sub-pixel 50 and the first peripheral metal fence 140 are separately set.

[0126] In some implementations, as shown in FIG1, the bottom ends of two adjacent sub-pixels 50 forming the gap region 300 share a bottom conductive layer 70, and a first peripheral metal fence 140 is formed on the upper part of the shared bottom conductive layer 70, and the two adjacent sub-pixels 50 forming the gap region 300 are surrounded by a first peripheral metal fence 140.

[0127] Furthermore, the top of the common conductive element 90 inside the gap region 300 is electrically connected to the upper sub-pixel 50, which is also surrounded by a first peripheral metal fence 140.

[0128] To achieve insulation between the first outer metal fence 140 of the upper sub-pixel 50 and the top conductive layer 60 of the sub-pixel, the top conductive layer 60 of the upper sub-pixel and the first outer metal fence 140 of the sub-pixel, which are electrically connected to the top of the common conductive member 90 inside the gap region 300, are insulated from each other by a second insulating layer 160.

[0129] The material of the second insulating layer 160 can be the same as that of the first insulating layer 150.

[0130] In some implementations, the first peripheral metal fence 140 may be provided even when there is no metal bonding layer at the bottom of the sub-pixel.

[0131] In some embodiments, a first insulating filling area 100 is provided inside the gap region 300, and the common electrode conductive element 90 inside the gap region 300 directly passes through the first insulating filling area 100 and is electrically connected to the first type of electrode contact 101.

[0132] When the first structure described above is prepared, the following preparation method can be used: fill the gap region 300 with insulating material to form a first insulating filling region 100, so that the common electrode conductive element 90 directly passes through the first insulating filling region 100 and is electrically connected to the first type of electrode contact 101.

[0133] For example, the filling material used in the first insulating filling region 100 may be one or more of silicon oxide, silicon nitride, silicon carbide (SiC), silicon carbon nitride (SiCN), silicon phosphosilicate glass (PSG), borosilicate glass (BPSG), or polyimide.

[0134] Furthermore, the first insulating filling area 100 may be made of a transparent filling material.

[0135] In the bottom common-polarity structure, each sub-pixel in the mother pixel located in a different pixel layer has a separate top conductive layer. The specific configuration can be as follows:

[0136] In some configurations, the top conductive layer of a sub-pixel can be located on the side of the sub-pixel, as shown in the configuration of the top conductive layer 60 of the sub-pixel in the second pixel layer 30 of Figure 1.

[0137] In other configurations, the top conductive layer 60 of at least one pixel layer is completely above the corresponding sub-pixel in the electrically connected pixel layer, that is, the top conductive layer of the sub-pixel is completely above the sub-pixel.

[0138] Furthermore, the top conductive layer (the top conductive layer electrically connected to the sub-pixel in the same pixel layer) is located above the corresponding sub-pixel in the electrically connected pixel layer. Here, "upper part" means that it is basically located near the top of the sub-pixel. The sub-pixel includes a P-type semiconductor layer, an active layer, and an N-type semiconductor layer arranged sequentially along the Z direction. Therefore, "upper part" can be understood as making the lowest point of its top conductive layer higher than the upper surface of the active layer in the sub-pixel. For example, referring to Figure 9, the entire top conductive layer 60 of the sub-pixel in the first pixel layer is located above the sub-pixel 50, or the entire top conductive layer 60 of the sub-pixel in the first pixel layer is basically located above the sub-pixel 50, with only a part of it slightly lower than the top surface of the sub-pixel.

[0139] For example, a method for fabricating a top conductive layer 60 separately disposed at the top of a sub-pixel in the first pixel layer 20 includes: etching the sub-pixel in the first pixel layer 20, then backfilling the current pixel layer with an insulating medium, planarizing the top of the first pixel layer 20 after backfilling to expose the top of the sub-pixel in the pixel layer, and then depositing the top conductive layer 60 to make it contact the exposed area of ​​the sub-pixel top to achieve electrical connection. Then, an insulating medium can be deposited again on the pixel layer and planarized again, and then the upper pixel layer can be stacked. The upper pixel layer can also be fabricated with a top conductive layer 60 separately in the same way, that is, after etching the sub-pixel, an insulating medium is backfilled, and after backfilling, the top of the pixel layer is planarized to expose the top of the sub-pixel in the pixel layer, and then the top conductive layer 60 is deposited to achieve electrical connection. In this process, the insulating medium is always a transparent material.

[0140] The above-described fabrication method allows the top conductive layer of a sub-pixel to be located substantially at the top of the sub-pixel when the top conductive layer is set separately.

[0141] For example, referring to Figure 9, a separate top conductive layer 60 is provided at the top of the sub-pixel located in the first pixel layer 20 of the mother pixel, and the top conductive layer 60 in the first pixel layer 20 is completely above the corresponding sub-pixel 50 in the electrically connected first pixel layer; a separate top conductive layer 60 is provided at the top of the sub-pixel located in the second pixel layer 30, and the top conductive layer 60 in the second pixel layer 30 is completely above the corresponding sub-pixel 50 in the electrically connected second pixel layer. Furthermore, the top conductive layers 60 of the two sub-pixels in the first pixel layer 20 are electrically connected to the corresponding second-type electrode contact 102 through their respective corresponding non-common conductive elements 80, and the top conductive layer 60 of the sub-pixel in the second pixel layer 30 is electrically connected to another corresponding second-type electrode contact 102 through another non-common conductive element 80.

[0142] In some schemes, the color transfer layer 40 can be disposed above the top conductive layer 60 of the second layer and located on the light emission path of the corresponding sub-pixel in the first pixel layer to achieve color transfer of the emitted light color of the sub-pixel.

[0143] In some embodiments, referring to FIG9, to enhance current conduction capability, at least one metal reinforcement 190 may be provided on the top conductive layer 60.

[0144] The aforementioned metal reinforcement 190 can be located above or below the electrically connected top conductive layer 60. The metal reinforcements in different mother pixels can be shared or used independently by their respective mother pixels.

[0145] In some embodiments, the sub-pixel 50 is in contact with the electrically connected top conductive layer 60 only at its top tip, or the top tip and at least part of the sidewalls of the sub-pixel 50 are in contact with the electrically connected top conductive layer 60.

[0146] In some implementations, at least two sub-pixels emit different colors, with one sub-pixel 50 located in the first pixel layer 20 and the other sub-pixel 50 located in the second pixel layer 30.

[0147] Furthermore, the emission colors of sub-pixels 50 in the first pixel layer 20 and the second pixel layer 30 are different.

[0148] For example, a sub-pixel 50 with a blue emission color is called a blue sub-pixel, and a sub-pixel 50 with a green emission color is called a green sub-pixel. Sub-pixel 50 in the first pixel layer 20 is a blue sub-pixel, and sub-pixel 50 in the second pixel layer 30 is a green sub-pixel. A color conversion layer 40 is set above a certain blue sub-pixel in the first pixel layer 20. This color conversion layer 40 is a red light color conversion layer. So the light emitted after color conversion by the color conversion layer 40 is red light. The blue sub-pixel without a color conversion layer above it still emits blue light after being emitted by the second pixel layer 30. So the light emitted by the second pixel layer 30 is green light, blue light and red light, thus realizing a three-color configuration.

[0149] In some implementations, a lens may also be provided on the upper part of the second pixel layer 30, and the lens may cover at least one sub-pixel 50.

[0150] The fabrication method of the microdisplay device shown in Figure 1 is described in detail below, and the method includes the following steps:

[0151] Step S1: Provide a drive backplate 10, on which a second type of electrode contact 102 is provided;

[0152] And a compound semiconductor layer is selected as the pixel layer. The aforementioned compound semiconductor layer is a layer with a certain thickness prepared using compound semiconductor materials; for example, the compound semiconductor layer here includes an N-type semiconductor layer, an active layer and a P-type semiconductor layer arranged sequentially from top to bottom.

[0153] Step S2: Stack two pixel layers from bottom to top on the driving backplane 10. These two pixel layers are the first pixel layer 20 and the second pixel layer 30, respectively. When stacking each pixel layer, the pixel layer is etched to obtain sub-pixels 50. The first pixel layer 20 and the second pixel layer 30 are both compound semiconductor layers, so that each mother pixel includes multiple sub-pixels 50. Some of the sub-pixels 50 are located in the first pixel layer 20, and the remaining sub-pixels are located in the second pixel layer 30.

[0154] Understandably, each sub-pixel 50 obtained by etching includes an N-type semiconductor layer, an active layer, and a P-type semiconductor layer arranged sequentially from top to bottom.

[0155] And the top of each sub-pixel 50 in the mother pixel is electrically connected to the corresponding second type electrode contact 102 through the top conductive layer 60, and the bottom ends of multiple sub-pixels 50 are interconnected through the bottom conductive layer 70 to form a bottom common electrode structure.

[0156] In the first pixel layer 20, a gap region 300 is formed between two adjacent sub-pixels 50. A common conductive element 90 passes through the gap region 300. The bottom conductive layers 70 at the bottom of the two adjacent sub-pixels 50 forming the gap region 300 are electrically interconnected. The bottom end of the common conductive element 90 inside the gap region 300 is electrically connected to the bottom conductive layer 70 at the bottom end of either of the two adjacent sub-pixels 50 forming the gap region 300, and the top end is electrically connected to the bottom conductive layer 70 of the other sub-pixel 50 in the second pixel layer 30. Light emitted by either of the two adjacent sub-pixels 50 forming the gap region 300 is emitted at least partially through the periphery of the upper sub-pixel electrically connected to the common conductive element 90 inside the gap region 300.

[0157] In addition, a color conversion layer 40 is provided above the first pixel layer 20. The color conversion layer 40 is located on the light emission path of the corresponding sub-pixel 50 in the first pixel layer 20, so as to realize the conversion of the light emission color of the sub-pixel.

[0158] In some embodiments, when a color transfer layer 40 is prepared above the first pixel layer 20, a color transfer material is coated on the upper surface of the top conductive layer 60 at the top of the sub-pixel 50 to be color transferred, and the color transfer material is etched to obtain the color transfer layer 40. The obtained color transfer layer 40 is located on the light emission path of the corresponding sub-pixel 50 in the first pixel layer 20.

[0159] In some embodiments, the method of forming a gap region 300 between two adjacent sub-pixels 50 in the first pixel layer 20 and allowing the common electrode conductor 90 to pass through the gap region 300 includes: etching the first pixel layer 20 to obtain two independent sub-pixels 50, forming a gap region 300 between the two sub-pixels 50; during the etching process, the bottom conductive layer 70 at the bottom end of the gap region 300 is retained without being etched, so that the bottom ends of the two sub-pixels 50 share a common bottom conductive layer 70, the bottom surface of the common bottom conductive layer 70 is electrically connected to the corresponding first type electrode contact 101, and the top surface is used to electrically connect to the common electrode conductor 90 inside the gap region 300.

[0160] Step S2, which involves stacking two pixel layers sequentially from bottom to top above the driving backplane 10, may specifically include the following steps:

[0161] Step S201: Referring to Figure 4, stack the first pixel layer 20 along the Z direction on the driving backplate 10;

[0162] The first pixel layer 20 has a bottom conductive layer 70 at its bottom. This bottom conductive layer is a metal bonding layer. The first pixel layer 20 and the driving backplate 10 are connected by bonding through the bottom conductive layer 70 to achieve stacking. The bonding method can be thermo-press bonding.

[0163] For example, the aforementioned metal bonding layer can be a combination of metal materials, such as nickel (Ni), tin (Sn), gold (Au), copper (Cu), aluminum (Al), indium tin oxide (ITO), etc. For example, the metal bonding layer can be one or more of the following combinations: Ni and Sn, Au and Sn, Cu and Sn, Au and In, Au and Au, Al and Al, Cu and Cu, or ITO and ITO. The metal bonding layer and the driving backplate 10 may also include an adhesive layer (made of Cr, Ti, Ni, etc.) and a depletion barrier layer (made of Ni, Pt, Cu, etc.). The metal bonding layer on the pixel layer and the driving backplate 10 can be symmetrical or asymmetrical.

[0164] In some preferred embodiments, the aforementioned metal bonding layer can be a multilayer structure stacked sequentially along the height direction, with the layers from bottom to top being a Cr layer (adhesion layer), a Pt layer (barrier depletion layer), an Au layer, a Sn layer, and an Au layer, with thicknesses of 10 nm, 50 nm, 100 nm, 150 nm, and 50 nm, respectively.

[0165] In some designs, a bottom ohmic contact layer 180 is also provided at the bottom of the first pixel layer 20, which is made of a conductive material.

[0166] For example, the bottom ohmic contact layer 180 can be one or more of transparent conductive films such as indium tin oxide (ITO), indium zinc oxide (IZO), indium gallium tin oxide (IGZO), and aluminum-doped zinc oxide (AZO), or one or more of conductive metal materials such as nickel (Ni), chromium (Cr), gold (Au), silver (Ag), zinc (Zn), rhodium (Rh), beryllium (Be), and aluminum (Al), or a composite structure composed of transparent metal oxides and metals; the thickness of the bottom ohmic contact layer 180 is in the range of 1 nm to 500 nm.

[0167] Step S202: Referring to stage b1 in Figure 5, the current pixel layer (compound semiconductor layer) is etched to obtain sub-pixel 50, so as to realize the independence of sub-pixel 50. It can be understood that the etched sub-pixel 50 includes an N-type semiconductor layer, an active layer and a P-type semiconductor layer arranged sequentially from top to bottom; the thickness of sub-pixel 50 (the distance between the upper surface of the N-type semiconductor layer and the lower surface of the P-type semiconductor layer) is 0.1um to 5um;

[0168] For example, the angle α of the etched sub-pixel 50 can be 90°±45°, and preferably, the angle α of the sub-pixel 50 can be 90°±20°. Wherein, the angle α of the sub-pixel 50 is the maximum angle between the sidewall of the sub-pixel 50 and the upper surface of the driving backplate 10.

[0169] The above etching process can be carried out using dry etching methods such as ICP and RIE, or wet etching methods such as KOH and HCl.

[0170] Understandably, a gap region 300 will be formed between two adjacent sub-pixels 50 obtained by etching;

[0171] In some embodiments, an etching barrier layer 230 is provided at the top of the pixel layer before etching, serving as an etching mask. The etching barrier layer 230 can be a transparent material. The etching barrier layer 230 can also be an insulating medium.

[0172] Step S203: Referring to stage b2 in Figure 5, a first insulating layer 150 is deposited on the surface of the current pixel layer, such that the first insulating layer 150 covers the top surface and sidewalls of the sub-pixel 50. Then, the overall structure formed by two adjacent sub-pixels is used as the first structure. Etching is performed on the periphery of the first structure until the lower surface of the metal bonding layer is exposed to expose the second type of electrode contact 102. Furthermore, the metal bonding layer at the bottom of the gap region 300 between two adjacent sub-pixels 50 can be retained, so that the bottom of the two sub-pixels share a metal bonding layer.

[0173] For example, the first insulating layer 150 may be made of one or more materials selected from silicon oxide, aluminum oxide, silicon nitride, titanium oxide, hafnium oxide, tantalum oxide, niobium oxide, aluminum nitride, or gallium nitride;

[0174] In some designs, the thickness of the first insulating layer 150 can be 5 nm to 2 μm.

[0175] During the etching process of the metal bonding layer, a metal fence is sputtered to form on the upper part of the metal bonding layer. At this time, the metal fence and the metal bonding layer are integrally formed (see Figure 1). The metal fence is the first peripheral metal fence 140. For example, the overall structure formed by two adjacent sub-pixels 50 is the first structure. The first peripheral metal fence 140 surrounds the periphery of the first structure. At this time, the two sub-pixels 50 in the first structure are surrounded by the same first peripheral metal fence 140.

[0176] At this time, the first outer metal fence 140 and the sidewalls of the surrounding sub-pixel 50 are insulated and isolated by the first insulating layer 150.

[0177] Step S204: The current pixel layer has at least two sub-pixels 50, and a gap region 300 is formed between two adjacent sub-pixels 50. An insulating material is filled around the sub-pixels 50, and the insulating material filled in the gap region 300 forms a first insulating filling region 100. At the same time, an insulating material is also filled above the second type of electrode contact 102.

[0178] For example, the filling material used in the first insulating filling region 100 may be one or more of silicon oxide, silicon nitride, silicon carbide (SiC), silicon carbon nitride (SiCN), silicon phosphosilicate glass (PSG), borosilicate glass (BPSG), or polyimide.

[0179] Then, the common electrode conductive element 90 is prepared: a hole is made in the first insulating filling area 100 inside the gap area 300 and backfilled with metal material to form the common electrode conductive element 90, so that the common electrode conductive element 90 directly passes through the first insulating filling area 100 and is electrically connected to the first type of electrode contact 101.

[0180] When the common electrode conductive element 90 is prepared, the non-common electrode conductive element 80 is also prepared. During preparation, holes are made in the insulating material area above the second type of electrode contact and backfilled with metal material to form the non-common electrode conductive element 80, so that the bottom end of the non-common electrode conductive element 80 is electrically connected to the corresponding second type of electrode contact 102.

[0181] Step S205: Referring to stage b3 in Figure 5, stack the second pixel layer 30 on top of the first pixel layer 20;

[0182] First, repeat steps S202-S203 to complete the preparation of sub-pixel 50 and the deposition of the first insulating layer 150, and make the bottom conductive layer 70 at the bottom of sub-pixel 50 in the second pixel layer 30 contact with the common electrode conductive component 90 below.

[0183] Then, electrode connections can be made at the top of the sub-pixels 50: Referring to stage b4 in Figure 5, the tops of the two sub-pixels 50 in the first pixel layer are exposed, and then a top conductive layer 60 is deposited or plated on each of them, so that the tops of the two sub-pixels 50 in the first pixel layer are in contact with the corresponding top conductive layer 60 to achieve electrical connection, and through the top conductive layer, they are electrically connected to the top of their respective non-common conductive components 80. The bottom of the non-common conductive component 80 is electrically connected to the corresponding second type electrode contact 102; and the tops of the sub-pixels 50 in the second pixel layer 30 are exposed, and a top conductive layer 60 is deposited or plated on them, so that the tops of the sub-pixels 50 in the second pixel layer are in contact with the corresponding top conductive layer 60 to achieve electrical connection, and through the top conductive layer, they are electrically connected to the top of the corresponding non-common conductive component 80. The bottom of the non-common conductive component 80 is electrically connected to the corresponding second type electrode contact 102.

[0184] Understandably, to expose the top of sub-pixel 50 in the second pixel layer 30 and the top of sub-pixel 50 in the first pixel layer 20, the excess material at the top of sub-pixel 50 can be removed by etching.

[0185] Through the above process, the top conductive layers of each sub-pixel in the second layer and the first layer are electrically connected to the corresponding second type electrode contact 102 through the corresponding non-common conductive element 80. At the same time, the bottom conductive layers 70 of the sub-pixels 50 in the second pixel layer 30 and the first pixel layer 20 are interconnected through the common conductive element 90 to form a bottom common structure.

[0186] For example, the top conductive layer 60 is a transparent conductive layer to facilitate light transmission, allowing light emitted from the lower sub-pixel 50 to pass through the top conductive layer 60 and shine upwards. This transparent conductive layer can be one or more combinations of indium tin oxide (ITO), indium zinc oxide (IZO), aluminum-doped zinc oxide (AZO), Al-doped indium tin oxide, Ag-doped indium tin oxide, and Au-doped indium tin oxide.

[0187] Understandably, when preparing the sub-pixel 50, if an etch barrier layer 230 is provided at the top of the sub-pixel 50 and the etch barrier layer 230 is an insulating layer, then when making electrical connections, a notch needs to be provided on the etch barrier layer 230 so that the top of the sub-pixel 50 can be exposed, and the exposed area can contact the top conductive layer 60 to achieve electrical connection.

[0188] When fabricating sub-pixels 50 in the second pixel layer 30, referring to Figure 1, in order to achieve insulation isolation between the first peripheral metal fence 140 and the top conductive layer 60 of the sub-pixel 50 in the second pixel layer 30, a second insulating layer 160 can also be provided between the sidewall of the first peripheral metal fence 140 and the top conductive layer 60; the material of the second insulating layer 160 can be the same as that of the first insulating layer 150.

[0189] In some embodiments, the thickness of the second insulating layer 160 is 5 nm to 2 μm.

[0190] Step S206: Referring to stage b5 in Figure 5, prepare the color transfer layer 40. During preparation, apply a color transfer material to the upper surface of the top conductive layer 60 at the top of the sub-pixel 50 to be color transferred, and etch the color transfer material to obtain the color transfer layer 40. The prepared color transfer layer 40 is located on the light-emitting path of the corresponding sub-pixel 50 in the first pixel layer 20.

[0191] After completing step S206, the lens can be fabricated.

[0192] The aforementioned lens is made of insulating material and can be made of materials such as silicon oxide, silicon nitride, aluminum oxide, silicate glass, silicone, electron beam photoresist (PMMA, SU8, etc.).

[0193] During lens fabrication, an insulating dielectric layer can be backfilled on the upper part of the second pixel layer 30, and the backfilled dielectric layer can be patterned and etched to form a lens.

[0194] Alternatively, a lens can be fabricated by filling the lens with an insulating dielectric material, planarizing it (CMP process), and then patterning it with a coating.

[0195] The LED display device of this embodiment simplifies the electrical connection structure, making it easier to manufacture. It also reduces the obstruction of the light-emitting surface of the lower sub-pixel, increases the effective light-emitting area of ​​the lower sub-pixel, and helps to achieve the best light distribution effect, so that its light pattern meets the needs of different application scenarios. At the same time, it also effectively improves the luminous efficiency and reliability of the display device.

[0196] Example 2

[0197] In this embodiment, the microdisplay device further includes a first type of electrode contact 101, the first type of electrode contact 101 and the second type of electrode contact 102 having opposite polarities, and the bottom conductive layer 70 at the bottom end of any one of the two adjacent sub-pixels 50 forming the gap region 300 is electrically connected to at least one first type of electrode contact 101.

[0198] In the first pixel layer 20 of the microdisplay device, a gap region 300 is formed between two adjacent sub-pixels 50. The common conductive element 90 inside the gap region 300 can be configured in the following ways:

[0199] The first type:

[0200] As shown in Figure 1, the bottom ends of two adjacent sub-pixels 50 forming the gap region 300 share a bottom conductive layer 70. The bottom surface of the shared bottom conductive layer 70 is electrically connected to the corresponding first type electrode contact 101, and the top surface is electrically connected to the common electrode conductive member 90 inside the gap region 300.

[0201] Furthermore, the common conductive element 90 inside the gap region 300 comes into contact with the common bottom conductive layer 70 and is electrically connected.

[0202] In some embodiments, a bottom ohmic contact layer 180 is provided between the bottom ends of two adjacent sub-pixels 50 forming the gap region 300 and a common bottom conductive layer 70, and the bottom ohmic contact layer 180 is penetrated by a common conductive element 90 inside the gap region 300.

[0203] The aforementioned bottom contact layer is made of conductive material.

[0204] In the above structure, the method of forming a gap region 300 between two adjacent sub-pixels 50 in the first pixel layer 20 and allowing the common electrode conductor 90 to pass through the gap region 300 includes: etching the first pixel layer 20 to obtain two independent sub-pixels 50, and forming a gap region 300 between the two sub-pixels 50; during the etching process, the bottom conductive layer 70 at the bottom end of the gap region 300 is retained without being etched, so that the bottom ends of the two sub-pixels 50 share a bottom conductive layer 70, the bottom surface of the shared bottom conductive layer 70 is electrically connected to the corresponding first type electrode contact 101, and the top surface is used to electrically connect to the common electrode conductor 90 inside the gap region 300.

[0205] The second type:

[0206] As shown in Figure 6, the bottom end of the common electrode conductive element 90 inside the gap region 300 contacts the corresponding first type electrode contact 101 to achieve electrical connection. The bottom conductive layer 70 of the bottom ends of the two adjacent sub-pixels 50 of the gap region 300 are both electrically connected to the first type electrode contact 101 electrically connected to the bottom end of the common electrode conductive element 90.

[0207] Specifically, the bottom conductive layer 70 at the bottom of each of the two adjacent sub-pixels 50 forming the gap region 300 is electrically connected to the corresponding first-type electrode contact 101. The first-type electrode contact 101 electrically connected to the bottom of the two adjacent sub-pixels 50 forming the gap region 300 is electrically interconnected with the first-type electrode contact 101 electrically connected to the bottom of the common electrode 90. That is, the common electrode 90 is electrically connected to the bottom conductive layer 70 of the two sub-pixels forming the gap region 300 through the conductive interconnection between the various first-type electrode contacts 101.

[0208] In the above structure, the method of forming a gap region 300 between two adjacent sub-pixels 50 in the first pixel layer 20 and allowing the common electrode 90 to pass through the gap region 300 includes: etching the first pixel layer 20 to obtain two independent sub-pixels 50, forming a gap region 300 between the two sub-pixels 50; during the etching process, removing the bottom conductive layer 70 at the bottom end of the gap region 300 and exposing the first type of electrode contact 101 at the bottom end of the gap region 300, which is used to electrically connect with the common electrode 90, so that the bottom conductive layer 70 at the bottom end of the two sub-pixels 50 is electrically connected to the first type of electrode contact 101 at the bottom end of the common electrode 90. For example, the bottom conductive layer 70 at the bottom end of the two sub-pixels is electrically connected to the corresponding first type of electrode contact 101, and the first type of electrode contact 101 electrically connected to the bottom end of the two sub-pixels is electrically interconnected with the first type of electrode contact 101 electrically connected to the bottom end of the common electrode 90.

[0209] Example 3

[0210] In this embodiment, referring to FIG7, the driving backplate 10 is divided into a display area 103, and all the mother pixels constitute a pixel array. The projection of the pixel array on the driving backplate 10 is located inside the display area 103, that is, the display area 103 is the area where the pixel array projection is located.

[0211] In some embodiments, a first type of electrode contact 101 may also be provided on the drive backplate 10, wherein the polarity of the first type of electrode contact 101 and the second type of electrode contact 102 are opposite.

[0212] The top of each sub-pixel 50 in the mother pixel is electrically connected to the corresponding second type electrode contact 102 through the top conductive layer 60, and the bottom ends of multiple sub-pixels 50 are interconnected through the bottom conductive layer 70 and connected to the first type electrode contact 101 to form a bottom common electrode structure.

[0213] The first type of electrode contact 101 can be set in the following ways:

[0214] The first method: Referring to Figure 1, the first type of electrode contact is provided only inside the display area, and the first type of electrode contact 101 is provided only inside the display area 103. For example, the first type of electrode contact 101 can be provided in the local display area where each mother pixel is projected.

[0215] In some embodiments, referring to FIG6, a plurality of first-type electrode contacts 101 are disposed inside the display area 103. The plurality of first-type electrode contacts 101 are electrically interconnected, which allows the bottom conductive layer 70 at the bottom end of the two sub-pixels 50 forming the gap region 300 in the first pixel layer 20 to contact the corresponding first-type electrode contact 101, and the common conductive element 90 inside the gap region 300 to directly contact another first-type electrode contact 101, and the various first-type electrode contacts 101 are electrically interconnected.

[0216] The second method is to provide a first type of electrode contact 101 only on the outside of the display area 103. For example, as shown in Figure 7, a peripheral electrode contact area 104 is provided around the display area 103, and the first type of electrode contact 101 can be provided within the peripheral electrode contact area 104. As shown in Figure 8, an interface 105 is also provided around the display area 103, and the peripheral electrode contact area 104 can be electrically connected to the interface 105.

[0217] The third type: both the exterior and interior of the display area 103 are provided with first-type electrode contacts 101.

[0218] In some embodiments, the second type of electrode contact 102 is electrically connected to the top conductive layer 60 at the top of the corresponding sub-pixel 50 via a non-common conductive element 80, and the bottom end of the non-common conductive element 80 can directly contact the corresponding second type of electrode contact 102.

[0219] The microdisplay devices of the above embodiments simplify the electrical connection structure, are easier to fabricate, effectively increase the effective light-emitting area of ​​the lower sub-pixels, are more conducive to the best light distribution effect, reduce energy waste, and thus effectively improve the light efficiency and reliability of the display device.

[0220] All the above-mentioned optional technical solutions can be combined in any way to form optional embodiments of the present invention. That is, any number of embodiments can be combined to meet the needs of different application scenarios. All of these are within the protection scope of this application and will not be described in detail here.

[0221] It should be noted that the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art can make other variations or modifications based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. A microdisplay device, characterized in that: Includes a driving backplate, on which a second type of electrode contact is disposed; and a first pixel layer, which is stacked on top of the driving backplate. The second pixel layer is stacked above the first pixel layer. A mother pixel includes multiple sub-pixels, some of which are located in the first pixel layer, while the remaining sub-pixels are located in the second pixel layer. The top of each sub-pixel is electrically connected to a corresponding second-type electrode contact via a top conductive layer, and the bottom ends of the sub-pixels are interconnected via bottom conductive layers to form a bottom common-polarity structure. A gap region is formed between two adjacent sub-pixels in the first pixel layer, through which a common-polarity conductive element passes. The bottom conductive layers at the bottom ends of the two adjacent sub-pixels forming the gap region are electrically interconnected. The bottom end of the common-polarity conductive element inside the gap region is electrically connected to the bottom conductive layer at the bottom end of any one of the two adjacent sub-pixels forming the gap region, and its top end is electrically connected to the bottom conductive layer of the other sub-pixel in the second pixel layer. Light emitted from any one of the two adjacent sub-pixels forming the gap region is at least partially emitted through the periphery of the upper sub-pixel electrically connected to the common-polarity conductive element inside the gap region.

2. The microdisplay device according to claim 1, characterized in that: A color conversion layer is also provided above the first pixel layer, and the color conversion layer is located on the light emission path of the corresponding sub-pixel in the first pixel layer.

3. The microdisplay device according to claim 2, characterized in that: The color conversion layer is provided on the light-emitting path of one of the two adjacent sub-pixels forming the gap region, while the color conversion layer is not provided on the light-emitting path of the other.

4. The microdisplay device according to claim 1, characterized in that: The projection area of ​​the upper sub-pixel electrically connected to the common conductive element inside the gap region on the driving backplate is at least partially located inside the projection area of ​​the gap region on the driving backplate.

5. The microdisplay device according to claim 1, characterized in that: The projection area of ​​the upper sub-pixel electrically connected to the common conductive element inside the gap region on the driving back plate is completely located inside the projection area of ​​the gap region on the driving back plate.

6. The microdisplay device according to claim 1, characterized in that: It also includes a first type of electrode contact, the first type of electrode contact and the second type of electrode contact having opposite polarities, and the bottom conductive layer at the bottom end of any one of the two adjacent sub-pixels forming the gap region is electrically connected to at least one of the first type of electrode contacts.

7. The microdisplay device according to claim 6, characterized in that: The bottom ends of two adjacent sub-pixels forming the gap region share a bottom conductive layer. The bottom surface of the shared bottom conductive layer is electrically connected to the corresponding first type of electrode contact, and the top surface is electrically connected to the common electrode conductive element inside the gap region.

8. The microdisplay device according to claim 7, characterized in that: A bottom ohmic contact layer is also provided between the bottom ends of two adjacent sub-pixels forming the gap region and the shared bottom conductive layer, and the bottom ohmic contact layer is penetrated by the common conductive element inside the gap region.

9. The microdisplay device according to claim 6, characterized in that: The bottom end of the common electrode conductive element inside the gap region is in contact with the corresponding first type of electrode contact to achieve electrical connection, and the bottom conductive layer of the bottom end of the two adjacent sub-pixels forming the gap region is electrically connected to the first type of electrode contact electrically connected to the bottom end of the common electrode conductive element.

10. The microdisplay device according to claim 1, characterized in that: The top conductive layer of each sub-pixel is electrically connected to the corresponding second type of electrode contact via a non-common conductive element.

11. The microdisplay device according to claim 10, characterized in that: The bottom end of the non-common conductive element is in direct contact with the corresponding second type of electrode contact.

12. The microdisplay device according to claim 1, characterized in that: The gap region includes an annular region, in which the common conductive element is disposed. Each of the two adjacent sub-pixels forming the gap region has a groove on its sidewall, and the grooves of the two adjacent sub-pixels enclose the annular region.

13. The microdisplay device according to claim 1, characterized in that: The bottom conductive layer is a metal bonding layer.

14. The microdisplay device according to claim 1, characterized in that: At least one of the sub-pixels is surrounded by a first peripheral metal fence, and the first peripheral metal fence and the sidewall of the surrounded sub-pixel are insulated and isolated by a first insulating layer.

15. The microdisplay device according to claim 14, characterized in that: The bottom ends of two adjacent sub-pixels forming the gap region share a bottom conductive layer, and a first peripheral metal fence is formed on the upper part of the shared bottom conductive layer. The two adjacent sub-pixels forming the gap region are surrounded by a first peripheral metal fence.

16. The microdisplay device according to claim 1, characterized in that: The gap region is provided with a first insulating filling region, and the common electrode conductive element inside the gap region passes directly through the first insulating filling region.

17. The microdisplay device according to claim 1, characterized in that: The driving backplate is divided into display areas, and all the mother pixels constitute a pixel array. The projection of the pixel array onto the driving backplate is located inside the display area. The display area is provided with first-type electrode contacts inside and / or the display area is provided with first-type electrode contacts outside.

18. The microdisplay device according to claim 1, characterized in that: Each of the sub-pixels in the first and second pixel layers of the mother pixel has a separate top conductive layer at its top. The top conductive layer in the first pixel layer is located above the electrically connected sub-pixel, and the top conductive layer in the second pixel layer is located above the electrically connected sub-pixel.

19. The microdisplay device according to claim 1, characterized in that: At least one of the top conductive layers is electrically connected to the metal reinforcement.

20. The microdisplay device according to claim 1, characterized in that: At least two of the sub-pixels emit different colors, one of the sub-pixels is located in the first pixel layer, and the other sub-pixel is located in the second pixel layer.

21. A method for fabricating a microdisplay device, characterized in that: include, A driving backplane is provided, on which second-type electrode contacts are disposed. Two pixel layers are stacked sequentially from bottom to top above the driving backplane. During the stacking of each pixel layer, an etching process is performed on the pixel layer to obtain sub-pixels. The two pixel layers are a first pixel layer and a second pixel layer, both of which are compound semiconductor layers, such that each parent pixel includes multiple sub-pixels. Some of these sub-pixels are located in the first pixel layer, and the remaining sub-pixels are located in the second pixel layer. The top of each sub-pixel in the parent pixel is electrically connected to a corresponding second-type electrode contact through a top conductive layer. The bottom of the multiple sub-pixels... The ends are interconnected through a bottom conductive layer to form a bottom common electrode structure; wherein, a gap region is formed between two adjacent sub-pixels in the first pixel layer, and a common electrode conductive element passes through the gap region; the bottom conductive layers at the bottom ends of the two adjacent sub-pixels forming the gap region are electrically interconnected; the bottom end of the common electrode conductive element inside the gap region is electrically connected to the bottom conductive layer at the bottom end of either of the two adjacent sub-pixels forming the gap region, and the top end is electrically connected to the bottom conductive layer of the other sub-pixel in the second pixel layer; at least part of the light emitted by either of the two adjacent sub-pixels forming the gap region is emitted through the periphery of the upper sub-pixel electrically connected to the common electrode conductive element inside the gap region.

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