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 bottom end of each subpixel is electrically connected to the corresponding first electrode contact by bottom conductive layer respectively, and the top end of multiple subpixels is interconnected by top conductive layer and forms top common electrode structure;Gap region is formed between two adjacent subpixels in first layer pixel layer, and non-common electrode conductor is passed through inside gap region, and the light emitted by any one of the two adjacent subpixels forming gap region at least partially emits via the periphery of the upper subpixel that non-common electrode conductor is electrically connected in inside gap region.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 first 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 bottom of each of the plurality of sub-pixels is electrically connected to the corresponding first type of electrode contact through a bottom conductive layer, and the tops of the plurality of sub-pixels are interconnected through a top conductive layer to form a top common electrode structure.

[0010] In the first pixel layer, a gap region is formed between two adjacent sub-pixels. A non-common conductive element passes through the gap region. The top end of the non-common conductive element inside the gap region is electrically connected to the bottom conductive layer of another sub-pixel in the second pixel layer, and the bottom end is electrically connected to the corresponding first type of electrode contact. 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 non-common conductive element 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 top of each of the sub-pixels located in the first pixel layer and the second pixel layer of the mother pixel is provided with a separate top conductive layer and they are not shared. The top conductive layer in the first pixel layer is located above the electrically connected sub-pixels, and the top conductive layer in the second pixel layer is located above the electrically connected sub-pixels.

[0013] In one embodiment of the present invention, the sub-pixels located in the first pixel layer and the second pixel layer of the mother pixel share a top conductive layer.

[0014] In one embodiment of the invention, the color-shifting layer is disposed on the upper surface of the shared top conductive layer.

[0015] 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.

[0016] In one embodiment of the invention, the projection area of ​​the upper sub-pixel electrically connected to the non-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.

[0017] In one embodiment of the present invention, the projection area of ​​the upper sub-pixel electrically connected to the non-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.

[0018] In one embodiment of the present invention, a first insulating filling area is provided inside the gap area, and the non-common conductive element passes directly through the first insulating filling area.

[0019] In one embodiment of the present invention, the gap region includes an annular region, in which the non-common conductive element is disposed, and the sidewalls of two adjacent sub-pixels forming the gap region each have a groove, and the grooves of the two adjacent sub-pixels enclose the annular region.

[0020] In one embodiment of the present invention, the bottom conductive layer is a metal bonding layer.

[0021] In one embodiment of the present invention, a first peripheral metal fence surrounds the periphery of either of the two adjacent sub-pixels forming the gap region. The first peripheral metal fence and the sidewall of the surrounded sub-pixel are insulated and isolated by a first insulating layer. The non-common conductive element is disposed between the first peripheral metal fences of the two adjacent sub-pixels forming the gap region.

[0022] In one embodiment of the invention, the top of the sub-pixel is in contact with an electrically connected top conductive layer, or the top of the sub-pixel and at least a portion of its sidewalls are in contact with an electrically connected top conductive layer.

[0023] In one embodiment of the invention, a metal reinforcement is further included, and at least one of the top conductive layers is electrically connected to the metal reinforcement.

[0024] In one embodiment of the invention, the metal reinforcement is located above the electrically connected top conductive layer.

[0025] In one embodiment of the invention, the metal reinforcement is located below the electrically connected top conductive layer.

[0026] In one embodiment of the invention, the metal reinforcement is located below the electrically connected top conductive layer and surrounds the periphery of the entirety formed by two adjacent sub-pixels that form the gap region below.

[0027] 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 second type of electrode contact is provided inside the display area, and / or a second type of electrode contact is provided outside the display area;

[0028] In this configuration, the polarity of the second type of electrode contact is opposite to that of the first type of electrode contact, and the tops of multiple sub-pixels in the mother pixel are all connected to the second type of electrode contact through a top conductive layer to form a top common electrode structure.

[0029] In one embodiment of the invention, a common electrode contact is further included, wherein the second type of electrode contact is electrically connected to the top conductive layer at the top of the plurality of sub-pixels via the common electrode contact.

[0030] In one embodiment of the present invention, the sub-pixels located in the first pixel layer and the second pixel layer of the mother pixel share a top conductive layer, and the common electrode conductive member is in direct contact with the shared top conductive layer to achieve electrical connection; or, the common electrode conductive member is electrically connected to the shared top conductive layer through a transition conductive member.

[0031] In one embodiment of the present invention, the top of each of the sub-pixels located in the first and second pixel layers of the mother pixel is provided with a separate top conductive layer instead of sharing one. The common electrode conductive member includes interconnecting conductive portions, and adjacent top conductive layers are interconnected through the interconnecting conductive portions to achieve electrical connection. At least one top conductive layer is in direct contact with the electrically connected interconnecting conductive portion to achieve electrical connection; or, at least one top conductive layer is electrically connected to the electrically connected interconnecting conductive portion through a metal reinforcement member.

[0032] In one embodiment of the present invention, the bottom end of the common electrode is in direct contact with the corresponding second type of electrode contact.

[0033] 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.

[0034] This invention also discloses a method for fabricating a microdisplay device, comprising,

[0035] A drive backplane is provided, wherein a first type of electrode contact is provided on the drive backplane;

[0036] 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.

[0037] This ensures that the bottom of each sub-pixel in the mother pixel is electrically connected to the corresponding first type of electrode contact through the bottom conductive layer, and the tops of multiple sub-pixels are interconnected through the top conductive layer to form a top common electrode structure.

[0038] In this configuration, a gap region is formed between two adjacent sub-pixels in the first pixel layer. A non-common conductive element passes through the gap region. The top end of the non-common conductive element inside the gap region is electrically connected to the bottom conductive layer of another sub-pixel in the second pixel layer, and the bottom end is electrically connected to the corresponding first type of electrode contact. 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 non-common conductive element inside the gap region.

[0039] The technical solution of the present invention has the following advantages compared with the prior art:

[0040] The microdisplay device of this invention allows sub-pixels of different layers to share a single top conductive layer, simplifying the electrical connection structure and facilitating fabrication. Simultaneously, it allows the common conductive element of the upper sub-pixel to pass through the gap between two adjacent lower sub-pixels, effectively reducing shading of the lower sub-pixel's light-emitting surface, ensuring the effective light-emitting area of ​​the lower sub-pixel, reducing energy waste, and improving light distribution. Furthermore, the use of a color conversion layer to achieve sub-pixel color conversion further facilitates optimal color display, effectively improving the luminous efficiency and reliability of the display device. Attached Figure Description

[0041] 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.

[0042] Figure 1 is a schematic diagram of the structure of the first micro-display device of the present invention;

[0043] Figure 2 is a schematic diagram (top view) of the arrangement of sub-pixels in a micro-display device according to the present invention.

[0044] Figure 3 is a schematic diagram of the bonding between the driving backplate and the first pixel layer in this invention;

[0045] Figure 4 is a flowchart of the fabrication process of the microdisplay device shown in Figure 1;

[0046] Figure 5 is a schematic diagram of the structure of the second type of microdisplay device of the present invention (with metal reinforcement).

[0047] Figure 6 is a structural schematic diagram of the third type of microdisplay device of the present invention (with metal reinforcement).

[0048] Figure 7 is a schematic diagram of the structure of the fourth micro-display device of the present invention;

[0049] Figure 8 is a schematic diagram of the structure of the fifth micro-display device of the present invention;

[0050] Figure 9 is a schematic diagram (top view) of the distribution of the display area in this invention.

[0051] Figure 10 is a schematic diagram (top view) of the connection between the peripheral electrode contact area and the interface in this invention.

[0052] Figure 11 is a schematic diagram of the sixth type of micro-display device of the present invention;

[0053] Figure 12 is a schematic diagram of the structure of the seventh micro-display device of the present invention;

[0054] Figure 13 is a magnified view of a portion of M3 in Figure 12;

[0055] Figure 14 is a schematic diagram of a structure in which the top conductive layer is set independently in the first pixel layer;

[0056] Figure 15 is a schematic diagram of a structural form after adding metal reinforcement to the structure shown in Figure 14.

[0057] Figure 16 is a schematic diagram of the structure shown in Figure 14 after the interconnecting conductive parts are connected;

[0058] Figure 17 is a schematic diagram of the structure shown in Figure 16 after the addition of metal reinforcement.

[0059] Figure 18 is a schematic diagram of another form of the structure shown in Figure 14 after adding metal reinforcement.

[0060] Figure 19 is a schematic diagram of the connection between the top conductive layer and the second type of electrode contact in the structure shown in Figure 14.

[0061] Figure 20 is a schematic diagram of the microdisplay device when each pixel layer of the present invention has an independently provided top conductive layer at its top;

[0062] Explanation of reference numerals in the instruction manual:

[0063] 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;

[0064] 20. First pixel layer;

[0065] 30. Second pixel layer;

[0066] 40. Color transfer layer;

[0067] 50. Subpixel;

[0068] 60. Top conductive layer;

[0069] 70. Bottom conductive layer;

[0070] 80. Non-common conductive components;

[0071] 90. Common conductor; 901. Interconnecting conductor;

[0072] 100. First insulation filling area;

[0073] 140. First outer metal fence; 150. First insulating layer; 160. Second insulating layer; 180. Bottom ohmic contact layer; 190. Metal reinforcement; 200. Transition conductive element; 230. Etching barrier layer; 300. Gap region; 3001. Annular region; 3002. Groove portion; Detailed Implementation

[0074] 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.

[0075] 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.

[0076] 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.

[0077] 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.

[0078] 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.

[0079] 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:

[0080] Table 1. Material Table of Film Layers for Compound Semiconductors

[0081]

[0082] The structure of the microdisplay device of this application will be further described below with reference to the following specific embodiments.

[0083] Example 1

[0084] Referring to Figure 1, this embodiment discloses a multi-layer stacked microdisplay device, including at least one mother pixel, each mother pixel having multiple (two or more) sub-pixels, and sub-pixels of different emission colors in the mother pixel being located in different pixel layers. The structure of the above microdisplay device is described in detail below with a structure having two pixel layers 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.

[0085] 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.

[0086] 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.

[0087] 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.

[0088] 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.

[0089] 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.

[0090] The aforementioned driving backplane 10 includes, but is not limited to, a CMOS (Complementary Metal Oxide Semiconductor) driving backplane.

[0091] 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.

[0092] 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.

[0093] Referring to Figure 1, this embodiment discloses a microdisplay device, including a driving backplane 10 and a mother pixel;

[0094] The drive backplate 10 is provided with a first type of electrode contact 101;

[0095] 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.

[0096] The first pixel layer 20 is stacked on top of the driving backplane 10, and the second pixel layer 30 is stacked on top of the first pixel layer 20.

[0097] 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 50 are located in the second pixel layer 30.

[0098] In the mother pixel: the bottom of each of the multiple sub-pixels 50 is electrically connected to the corresponding first type of electrode contact 101 through the bottom conductive layer 70, and the tops of the multiple sub-pixels are interconnected through the top conductive layer 60 to form a top common pole structure; that is, the top conductive layers 60 of each sub-pixel 50 in the top common pole structure are electrically connected together and conduct electricity to each other.

[0099] Furthermore, a gap region 300 is formed between two adjacent sub-pixels 50 in the first pixel layer 20. A non-common conductive element 80 passes through the gap region 300. The top end of the non-common conductive element 80 inside the gap region 300 is electrically connected to the bottom conductive layer 70 of another sub-pixel 50 in the second pixel layer 30, and the bottom end is electrically connected to the corresponding first-type electrode contact 101. Light emitted by 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 electrically connected to the non-common conductive element 80 inside the gap region 300 without being blocked by that upper sub-pixel. This effectively 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 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 sub-pixel 50.

[0100] A color conversion layer 40 is also provided 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.

[0101] The color conversion layer 40 can be used to change the color of emitted light. For example, if the emitted light color of a sub-pixel 50 is blue, a color conversion layer 40 is provided on the light path of the blue sub-pixel. When the light emitted by the blue sub-pixel hits the color conversion layer 40, the color conversion layer 40 will be excited and emit light of another color. For example, the blue light emitted by the blue sub-pixel may appear red after being converted and emitted by the color conversion layer 40.

[0102] 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.

[0103] 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.

[0104] 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.

[0105] For example, referring to Figures 1 and 2, Figure 1 can be a cross-sectional view of the structure in Figure 2 along BB; 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 first type of electrode contact 101 connected to it is denoted as c1; the sub-pixel 50 located in the second pixel layer 30 is denoted as i2, and the first type of electrode contact 101 connected to it is denoted as c2.

[0106] In the structure described above, a non-common conductive element 80 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 non-common conductive element 80 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 50 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.

[0107] 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.

[0108] 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. In some embodiments, sub-pixels 50 located in the first pixel layer 20 and the second pixel layer 30 of the mother pixel share a top conductive layer 60; this method allows sub-pixels located in different layers to share a top conductive layer, simplifying the electrical connection structure, facilitating fabrication, and reducing light loss from lower sub-pixels, thereby ensuring the overall light efficiency of the device.

[0109] In some embodiments, referring to FIG1, a color transfer layer 40 is provided on the upper surface of the common top conductive layer 60, such that the color transfer layer 40 is located on the light emission path of a certain sub-pixel in the first pixel layer 20.

[0110] 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.

[0111] 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.

[0112] In some implementations, a color conversion layer 40 is provided on the light-emitting path of one of the two adjacent sub-pixels 50 forming the gap region 300, while no color conversion layer is provided on the light-emitting path of the other, so that the two emit different colors in the end, realizing multi-color configuration, and also making the overall structure more compact, which is conducive to improving pixel density.

[0113] 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.

[0114] 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 non-common conductive element 80 inside the gap region 300 are arranged on opposite axes.

[0115] The shape of each sub-pixel 50 is not limited; it can be a circle, ellipse, polygon (triangle, trapezoid, rectangle, etc.) or other shapes.

[0116] In some embodiments, the material of the aforementioned non-common conductive component 80 may be metals such as aluminum (Al), copper (Cu), 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.

[0117] In some embodiments, the projection area of ​​the upper sub-pixel 50 electrically connected to the non-common conductive element 80 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.

[0118] 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.

[0119] Furthermore, referring to Figure 2, the projection area of ​​the upper sub-pixel 50 electrically connected to the non-common conductive element 80 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 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 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.

[0120] In some embodiments, a first insulating filling area 100 is provided inside the gap region 300, and the non-common conductive element 80 passes directly through the first insulating filling area 100 and is electrically connected to the first type of electrode contact 101.

[0121] 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 non-common conductive element 80 directly passes through the first insulating filling region 100 and is electrically connected to the first type of electrode contact 101.

[0122] 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.

[0123] Furthermore, the first insulating filling area 100 may be made of a transparent filling material.

[0124] In some embodiments, referring to FIG2, the gap region 300 includes an annular region 3001, within which a non-common conductive element 80 is disposed. Each adjacent sub-pixel 50 forming the gap region 300 has a groove 3002 on its sidewall, and the grooves 3002 of the two adjacent sub-pixels 50 together form the annular region 3001. This method is more conducive to ensuring the placement of the non-common conductive element, and also makes the overall structure more compact, which is beneficial for increasing pixel density.

[0125] Furthermore, the aforementioned groove portion 3002 is arc-shaped, but other shapes may also be used.

[0126] In some implementations, the bottom conductive layer 70 at the bottom of the sub-pixel 50 may be a non-metallic conductive layer.

[0127] In some implementations, the bottom conductive layer 70 at the bottom of the sub-pixel 50 may be a metal bonding layer.

[0128] Furthermore, a metal fence may be installed on the upper part of the metal bonding layer, or no metal fence may be installed.

[0129] When a metal fence is available, the following methods can be used:

[0130] In some embodiments: Referring to Figure 1, the periphery of either of the two adjacent sub-pixels 50 forming the gap region 300 is surrounded by a first peripheral metal fence 140. The first peripheral metal fence 140 and the sidewall of the surrounded sub-pixel 50 are insulated and isolated by a first insulating layer 150 to avoid short circuits inside the sub-pixel. A non-common conductive element 80 is provided between the first peripheral metal fences 140 of the two adjacent sub-pixels 50 forming the gap region 300.

[0131] Furthermore, the outer periphery of the upper sub-pixel 50, which is electrically connected to the non-common conductive element 80 inside the gap region 300, is also surrounded by a first peripheral metal fence 140, and the first peripheral metal fence 140 and the sidewall of the surrounded sub-pixel 50 are insulated and isolated by a first insulating layer 150.

[0132] When the upper sub-pixel and the adjacent lower sub-pixel share a top conductive layer 60, referring to Figure 1, in order to achieve insulation isolation between the first outer metal fence 140 of the upper sub-pixel and the top conductive layer 60, a second insulating layer 160 can also be provided between the first outer 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.

[0133] 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;

[0134] In some designs, the thickness of the first insulating layer 150 can be 5 nm to 2 μm.

[0135] Furthermore, 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.

[0136] 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.

[0137] In some methods, at least two sub-pixels emit different colors, with one sub-pixel located in the first pixel layer 20 and the other sub-pixel located in the second pixel layer 30.

[0138] In some implementations, the sub-pixels 50 in the first pixel layer 20 and the second pixel layer 30 emit different colors.

[0139] 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 40. Then, the light emitted after color conversion by the color conversion layer 40 is red light. The blue sub-pixel without a color conversion layer 40 above it still emits blue light after passing through the second pixel layer 30. So, the light emitted by the second pixel layer 30 is green light, blue light, and red light, thus achieving a three-color configuration.

[0140] 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.

[0141] The fabrication method of the microdisplay device shown in Figure 1 is described in detail below, and the method includes the following steps:

[0142] Step S1: Provide a drive backplate 10, on which first type of electrode contacts 101 are provided;

[0143] 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.

[0144] Step S2: Two pixel layers are stacked sequentially from bottom to top above 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 parent pixel includes multiple sub-pixels 50. Some of the sub-pixels 50 are located in the first pixel layer 20, and the rest are located in the second pixel layer 30.

[0145] 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.

[0146] And the bottom of each sub-pixel 50 in the mother pixel is electrically connected to the corresponding first type electrode contact 101 through the bottom conductive layer 70, and the tops of multiple sub-pixels 50 are interconnected through the top conductive layer 60 to form a top common electrode structure.

[0147] This allows the sub-pixels 50 located in the first pixel layer 20 and the second pixel layer 30 of the mother pixel to share a top conductive layer 60;

[0148] In the first pixel layer 20, a gap region 300 is formed between two adjacent sub-pixels 50. A non-common conductive element 80 passes through the gap region 300. The top end of the non-common conductive element 80 inside the gap region 300 is electrically connected to the bottom conductive layer 70 of another sub-pixel 50 in the second pixel layer 30, and the bottom end is electrically connected to the corresponding first type electrode contact 101. 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 50 electrically connected to the non-common conductive element 80 inside the gap region 300.

[0149] A color conversion layer 40 is prepared above the first pixel layer 20, such that 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.

[0150] In some embodiments, when the color transfer layer 40 is prepared above the first pixel layer 20, a color transfer material is coated on the upper surface of the common top conductive layer 60, 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-emitting path of the corresponding sub-pixel 50 in the first pixel layer 20.

[0151] Step S2, which involves stacking two pixel layers sequentially from bottom to top above the driving backplane 10, may specifically include the following steps:

[0152] Step S201: Referring to Figure 3, stack the first pixel layer 20 along the Z direction on the driving backplate 10;

[0153] The first pixel layer 20 has a bottom conductive layer 70 at its bottom. This bottom conductive layer 70 is a metal bonding layer. The first pixel layer 20 and the driving backplate 10 are stacked by bonding through the bottom conductive layer 70. The bonding method can be thermo-press bonding.

[0154] 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.

[0155] 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.

[0156] In some designs, a bottom ohmic contact layer 180 is also provided at the bottom of the first pixel layer, which is made of a conductive material.

[0157] Step S202: Referring to stage b1 in Figure 4, 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;

[0158] 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.

[0159] 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.

[0160] Understandably, a gap region 300 will be formed between two adjacent sub-pixels 50 obtained by etching;

[0161] 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.

[0162] Step S203: Referring to stage b2 in Figure 4, 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, etching is performed on the periphery of the sub-pixel 50 until the lower surface of the metal bonding layer is reached.

[0163] 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;

[0164] In some designs, the thickness of the first insulating layer 150 can be 5 nm to 2 μm.

[0165] During the etching process of the metal bonding layer, a metal fence is sputtered on the upper part of the metal bonding layer, and at this time the metal fence and the metal bonding layer are integrally formed.

[0166] 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.

[0167] 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.

[0168] Then, the non-common conductive element 80 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 non-common conductive element 80, so that the non-common conductive element 80 directly passes through the first insulating filling area 100 and is electrically connected to the first type of electrode contact 101.

[0169] Step S205: Referring to stage b3 in Figure 4, stack the second pixel layer 30 on top of the first pixel layer 20;

[0170] First, repeat steps S202-S203 to complete the fabrication of sub-pixel 50 and the deposition of the first insulating layer. Then, the electrode connection at the top of sub-pixel 50 can be performed: referring to stage b4 in Figure 4, the tops of sub-pixels in the second pixel layer 30 and the first pixel layer 20 are exposed. Then, a top conductive layer 60 is deposited or plated so that the tops of sub-pixels 50 in the second pixel layer 30 and the first pixel layer 20 are in contact with the top conductive layer 60 to achieve electrical connection. In the structure prepared at this time, sub-pixels 50 in the second pixel layer 30 and sub-pixels 50 in the first pixel layer 20 share a top conductive layer 60.

[0171] 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.

[0172] 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.

[0173] 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.

[0174] 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 first peripheral metal fence 140 and the sidewall of 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.

[0175] In some embodiments, the thickness of the second insulating layer 160 is 5 nm to 2 μm.

[0176] Step S206: Referring to stage b5 in Figure 4, prepare the color transfer layer 40. During preparation, apply a color transfer material to the upper surface of the top conductive layer 60 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.

[0177] After completing step S206, the lens can be fabricated.

[0178] 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.).

[0179] 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.

[0180] 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.

[0181] 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.

[0182] Example 2

[0183] Referring to Figure 20, the main difference between this embodiment and Embodiment 1 is that the top of the sub-pixels located in different pixel layers in the mother pixel can be set with a top conductive layer 60 separately without sharing (the pixel layer structure with a separate top conductive layer 60 is shown in Figures 14-20), and the top conductive layers 60 of each layer are interconnected to achieve a common top electrode.

[0184] 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, "above" means essentially 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, "above" can be understood as ensuring that the lowest point of the top conductive layer is higher than the upper surface of the active layer in the sub-pixel. For example, referring to Figure 14, 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 essentially located above the sub-pixel 50, with only a portion slightly lower than the top surface of the sub-pixel.

[0185] For example, in the two-layer structure shown in Figure 20, a separate top conductive layer 60 is provided on the top of sub-pixel 50 in the first pixel layer 20, and a separate top conductive layer 60 is also provided on the top of sub-pixel 50 in the second pixel layer 30. The top conductive layers of the two layers are not shared, and they are interconnected via an interconnecting conductive portion 901. This interconnecting conductive portion 901 is part of a common-polarity conductive member 90. Furthermore, the top conductive layer 60 of each sub-pixel in the first pixel layer 20 is completely located above the sub-pixel, and the top conductive layer 60 of each sub-pixel in the second pixel layer 30 is also completely located above the sub-pixel.

[0186] The method for fabricating a separate top conductive layer 60 at the top of sub-pixels 50 in the first pixel layer 20 includes: etching sub-pixels 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-pixels, 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 top of the pixel layer and planarized again, and then the second pixel layer 30 is stacked. The second pixel layer 30 can also be fabricated with a separate top conductive layer in the same way, that is, after etching sub-pixels, insulating medium is backfilled, and after backfilling, planarization is performed on the top of the pixel layer to expose the top of the sub-pixels, and then the top conductive layer 60 is deposited to achieve electrical connection. In this process, the insulating medium is always transparent.

[0187] The above method also ensures that in a sub-pixel with a separate top conductive layer, the top conductive layer of the sub-pixel is completely located on the upper part of the sub-pixel.

[0188] In some embodiments, referring to FIG19, the second type of electrode contacts are electrically connected to the top conductive layer 60 at the top of multiple sub-pixels via a common electrode 90. Furthermore, the bottom end of the common electrode 90 and the corresponding second type of electrode contact 102 can directly contact each other to achieve electrical connection.

[0189] Each sub-pixel in the mother pixel located in different pixel layers has its own top conductive layer 60, which is not shared. Specifically, as shown in Figure 20, each sub-pixel in the mother pixel located in the first pixel layer 20 and the second pixel layer 30 has its own top conductive layer 60, which is not shared. The common conductive component 90 includes an interconnecting conductive part 901, and two adjacent top conductive layers 60 in the upper and lower layers are interconnected through the interconnecting conductive part 901 to achieve electrical connection.

[0190] Referring to Figure 16, a top conductive layer 60 is in direct contact with the electrically connected interconnect conductive part 901 to achieve electrical connection;

[0191] Alternatively, to enhance current conduction capability, referring to FIG15, a top conductive layer 60 is electrically connected to a metal reinforcement; further, referring to FIG17, a top conductive layer 60 and an electrically connected interconnecting conductive portion 901 are electrically connected through a metal reinforcement 190.

[0192] In other embodiments, the metal reinforcement 190 is located above (see Figure 15) or below (see Figure 18) the electrically connected top conductive layer 60.

[0193] When setting up the color transfer layer, it can be positioned above the top conductive layer.

[0194] In this embodiment, the structure and arrangement of each sub-pixel can adopt the corresponding form in Embodiment 1, which will not be repeated here.

[0195] Example 3

[0196] In this embodiment, the microdisplay device also includes a metal reinforcement 190, and the top conductive layer 60 is electrically connected to the metal reinforcement 190 to increase the current spreading capability through the metal reinforcement.

[0197] In some implementations, the sub-pixels 50 located in the first pixel layer 20 and the second pixel layer 30 of the mother pixel share a top conductive layer 60;

[0198] As shown in Figures 5 and 6, the shared top conductive layer 60 is electrically connected to the metal reinforcement 190.

[0199] In some designs, as shown in Figure 5, the metal reinforcement 190 is located above the common top conductive layer 60.

[0200] In other designs, the metal reinforcement 190 is located below and surrounds the common top conductive layer 60.

[0201] Furthermore, the metal reinforcement 190 surrounds the periphery of a sub-pixel 50 below the shared top conductive layer 60.

[0202] Furthermore, the bottom of the metal reinforcement 190 is not lower than the top of the surrounding sub-pixel 50.

[0203] In some embodiments, as shown in FIG6, the metal reinforcement 190 is located below a common top conductive layer 60 and surrounds the periphery of the entire assembly consisting of two adjacent sub-pixels 50 forming a gap region 300 below. For example, the first pixel layer 20 has two sub-pixels 50 with a gap region 300 between them, and the two sub-pixels 50 are internally surrounded by the same metal reinforcement 190.

[0204] In the specific fabrication process, when the metal reinforcement 190 is located below the common top conductive layer 60, the metal reinforcement can be inserted into the insulating fill area around the lower sub-pixel.

[0205] In some implementations, the metal reinforcement 190 in different mother pixels can be shared or used independently by their respective mother pixels.

[0206] In other embodiments, the top of a sub-pixel in at least one pixel layer of the mother pixel is provided with a separate top conductive layer, which is not shared with the sub-pixels of other pixel layers. In this case, for the sub-pixel with a separate top conductive layer, a metal reinforcement 190 can also be electrically connected to its top conductive layer 60.

[0207] For example, each sub-pixel located in the first pixel layer 20 and the second pixel layer 30 of the parent pixel can have its own separate top conductive layer 60 instead of sharing one. In this case, for the sub-pixel with its own top conductive layer, a metal reinforcement 190 can also be electrically connected to its top conductive layer 60.

[0208] For example, in some embodiments, as shown in FIG15, the metal reinforcement 190 is located above a top conductive layer 60.

[0209] In other embodiments, as shown in Figure 18, the metal reinforcement 190 is located below a top conductive layer 60.

[0210] In some designs, as shown in Figure 19, the bottom end of the common electrode 90 is in direct contact with the corresponding second-type electrode contact.

[0211] Example 4

[0212] In this embodiment, 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, which means that the display area 103 is the area where the pixel array projection is located.

[0213] In some embodiments, as shown in Figures 7-8, a second type of electrode contact 102 may also be provided on the drive back plate 10, wherein the polarities of the first type of electrode contact 101 and the second type of electrode contact 102 are opposite.

[0214] In the mother pixel: the bottom of each of the multiple sub-pixels 50 is electrically connected to the corresponding first type electrode contact 101 through the bottom conductive layer 70, and the top of the multiple sub-pixels 50 is electrically connected to the second type electrode contact 102 through the top conductive layer 60 to form a top common electrode structure.

[0215] The second type of electrode contact 102 can be configured in the following ways:

[0216] The first method is to set the second type of electrode contact 102 only inside the display area 103. For example, the second type of electrode contact 102 can be set in the local display area where each mother pixel is projected.

[0217] The second method involves providing the second type of electrode contact 102 only on the periphery of the display area 103. For example, as shown in FIG9, a peripheral electrode contact area 104 is provided on the periphery of the display area 103, and the second type of electrode contact 102 can be disposed within the peripheral electrode contact area 104; as shown in FIG10, an interface 105 is also provided on the periphery of the display area 103, and the peripheral electrode contact area 104 can be electrically connected to the interface 105.

[0218] The third type: both the exterior and interior of the display area 103 are provided with second-type electrode contacts 102.

[0219] In some embodiments, the microdisplay device further includes a common electrode 90, through which the second type of electrode contacts 102 are electrically connected to the top conductive layer 60 at the top of the plurality of sub-pixels 50 to achieve top common electrode.

[0220] The common electrode 90 is located approximately above the second type of electrode contact 102. The common electrode 90 and the second type of electrode contact 102 can be located together inside the display area 103 or together outside the display area 103.

[0221] In some configurations, referring to Figures 7, 8 and 19, the bottom end of the common electrode 90 is in direct contact with the corresponding second type electrode contact 102.

[0222] In a first optional embodiment, the sub-pixels located in the first pixel layer 20 and the second pixel layer 30 of the mother pixel share a top conductive layer 60, and the common electrode conductive element 90 is in direct contact with the shared top conductive layer 60 to achieve electrical connection; or, the common electrode conductive element 90 is electrically connected to the shared top conductive layer 60 through a transition conductive element 200.

[0223] For example, referring to FIG8, two sub-pixels 50 located in the first and second pixel layers respectively share a top conductive layer 60, and the shared top conductive layer 60 and the common electrode conductive member 90 below are in direct contact.

[0224] Alternatively, referring to Figure 7, two sub-pixels 50 located in the first and second pixel layers respectively share a top conductive layer 60, and the shared top conductive layer 60 and the common electrode conductor 90 below are connected by a transition conductive member 200.

[0225] In some embodiments, as shown in FIG8, a metal reinforcement 190 may be connected to the top conductive layer 60 to further enhance the current conduction capability.

[0226] In some implementations, multiple mother pixels can share a second type of electrode contact 102, or each mother pixel can independently use its own corresponding second type of electrode contact 102.

[0227] In a second alternative embodiment, the top of each sub-pixel located in the first pixel layer 20 and the second pixel layer 30 of the mother pixel is provided with a separate top conductive layer 60 without sharing it. The common conductive component 90 includes an interconnecting conductive portion 901, and two adjacent top conductive layers 60 are interconnected through the interconnecting conductive portion 901 to achieve electrical connection.

[0228] For example, referring to FIG20, in a two-layer structure with two pixel layers, a top conductive layer 60 can be separately provided at the top of the sub-pixel 50 in the first pixel layer 20, and a top conductive layer 60 can also be separately provided at the top of the sub-pixel 50 in the second pixel layer 30. The two top conductive layers 60 can be interconnected by an interconnecting conductive part 901.

[0229] In some embodiments, referring to Figure 16, a top conductive layer 60 is in direct contact with the electrically connected interconnect conductive portion 901 to achieve electrical connection;

[0230] Alternatively, referring to Figure 17, a top conductive layer 60 is electrically connected to the electrically connected interconnecting conductive portion 901 via a metal reinforcement 190.

[0231] In some embodiments, the metal reinforcement 190 may be located below (see Figure 18) or above (see Figure 15) the electrically connected top conductive layer 60.

[0232] Example 5

[0233] In this embodiment, the top of the sub-pixel 50 is in contact with the top conductive layer 60 to achieve electrical connection, which can take the following forms:

[0234] The first method is shown in Figure 1, where only the top of the sub-pixel 50 is in contact with the electrically connected top conductive layer 60. In this case, only a part or all of the top of the sub-pixel can be exposed, and the exposed area can be in contact with the corresponding top conductive layer 60 to achieve electrical connection.

[0235] The second method involves making the top edge and at least part of the sidewalls of the sub-pixel 50 contact the electrically connected top conductive layer 60. In this case, in addition to exposing the top edge of the sub-pixel 50, at least part of the sidewalls of the sub-pixel 50 are also exposed, thus forming an exposed area that contacts the corresponding top conductive layer 60 to achieve electrical connection. This method can increase the electrical contact area, which is more conducive to current expansion and enhances the current conduction capability.

[0236] Understandably, in specific settings, one sub-pixel in the mother pixel can use the first electrical connection method, while other sub-pixels use the second electrical connection method, or all sub-pixels can use the same electrical connection method. The specific choice can be made according to actual needs.

[0237] For example, in a two-layer structure, as shown in Figure 11, the upper sub-pixel 50 adopts the second electrical connection form, with its top and at least part of the sidewalls exposed and in contact with the common top conductive layer 60, while the lower sub-pixel 50 adopts the first electrical connection form, exposing only a portion of its top area and making that exposed area in contact with the common top conductive layer 60; in another configuration, as shown in Figures 12-13, the upper sub-pixel 50 adopts the second electrical connection form, with its top j1 and at least part of the sidewall j2 exposed and in contact with the common top conductive layer 60, while the lower sub-pixel 50 also adopts the second electrical connection form, exposing a portion of its top j1 and part of its sidewall j2 and making that exposed area in contact with the common top conductive layer 60.

[0238] 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.

[0239] 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.

[0240] 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 first 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 on top of the first pixel layer; the mother pixel includes multiple sub-pixels, some of which are located in the first pixel layer and the rest are located in the second pixel layer; the bottom of each sub-pixel is electrically connected to a corresponding first type of electrode contact through a bottom conductive layer, and the tops of the sub-pixels are interconnected through a top conductive layer to form a top common electrode structure; a gap region is formed between two adjacent sub-pixels in the first pixel layer, and a non-common electrode conductive element passes through the gap region. The top of the non-common electrode conductive element inside the gap region is electrically connected to the bottom conductive layer of another sub-pixel in the second pixel layer, and the bottom is electrically connected to a corresponding first type of electrode contact; light emitted by either 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 non-common electrode 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: 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, and they do not share a common top conductive layer. The top conductive layer in the first pixel layer is located above the electrically connected sub-pixels, and the top conductive layer in the second pixel layer is located above the electrically connected sub-pixels.

4. The microdisplay device according to claim 2, characterized in that: The sub-pixels located in the first pixel layer and the second pixel layer of the mother pixel share a top conductive layer.

5. The microdisplay device according to claim 4, characterized in that: The color transfer layer is disposed on the upper surface of the shared top conductive layer.

6. 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.

7. The microdisplay device according to claim 1, characterized in that: The projection area of ​​the upper sub-pixel electrically connected to the non-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.

8. The microdisplay device according to claim 7, characterized in that: The projection area of ​​the upper sub-pixel electrically connected to the non-common conductive element inside the gap region on the driving backplate is completely located inside the projection area of ​​the gap region on the driving backplate.

9. The microdisplay device according to claim 1, characterized in that: The gap region is provided with a first insulating filling region, and the non-common conductive component passes directly through the first insulating filling region.

10. The microdisplay device according to claim 1, characterized in that: The gap region includes an annular region, in which the non-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.

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

12. The microdisplay device according to claim 1, characterized in that: The periphery of either of the two adjacent sub-pixels forming the gap region is surrounded by a first peripheral metal fence. The first peripheral metal fence and the sidewall of the surrounded sub-pixel are insulated and isolated by a first insulating layer. The non-common conductive element is disposed between the first peripheral metal fences of the two adjacent sub-pixels forming the gap region.

13. The microdisplay device according to claim 1, characterized in that: The top of the sub-pixel is in contact with the electrically connected top conductive layer, or the top of the sub-pixel and at least part of its sidewalls are in contact with the electrically connected top conductive layer.

14. The microdisplay device according to any one of claims 3 or 4, characterized in that: It also includes a metal reinforcement, at least one of the top conductive layers being electrically connected to the metal reinforcement.

15. The microdisplay device according to claim 14, characterized in that: The metal reinforcement is located above the electrically connected top conductive layer.

16. The microdisplay device according to claim 14, characterized in that: The metal reinforcement is located below the electrically connected top conductive layer.

17. The microdisplay device according to claim 16, characterized in that: The metal reinforcement is located below the electrically connected top conductive layer and surrounds the periphery of the entirety formed by the two adjacent sub-pixels that form the gap region below.

18. 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. A second type of electrode contact is provided inside the display area, and / or a second type of electrode contact is provided outside the display area. The polarity of the second type of electrode contact is opposite to that of the first type of electrode contact. The tops of multiple sub-pixels in the mother pixel are all connected to the second type of electrode contact through a top conductive layer to form a top common electrode structure.

19. The microdisplay device according to claim 18, characterized in that: It also includes a common electrode conductor, through which the second type of electrode contacts are electrically connected to the top conductive layer at the top of multiple sub-pixels.

20. The microdisplay device according to claim 19, characterized in that: The sub-pixels located in the first pixel layer and the second pixel layer of the mother pixel share a top conductive layer, and the common electrode conductive element is in direct contact with the shared top conductive layer to achieve electrical connection; or, the common electrode conductive element is electrically connected to the shared top conductive layer through a transition conductive element.

21. The microdisplay device according to claim 19, characterized in that: Each of the sub-pixels located in the first and second pixel layers of the mother pixel has a separate top conductive layer at its top and they do not share a common conductive layer. The common conductive element includes interconnecting conductive parts. Adjacent top conductive layers are interconnected through the interconnecting conductive parts to achieve electrical connection. At least one top conductive layer is in direct contact with the electrically connected interconnecting conductive part to achieve electrical connection; or, at least one top conductive layer is electrically connected to the electrically connected interconnecting conductive part through a metal reinforcement.

22. The microdisplay device according to claim 19, characterized in that: The bottom end of the common electrode is in direct contact with the corresponding second type of electrode contact.

23. 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.

24. A method for fabricating a microdisplay device, characterized in that: include, A driving backplane is provided, on which first-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 bottom of each sub-pixel in the parent pixel is electrically connected to a bottom conductive layer. The tops of multiple sub-pixels are interconnected through a top conductive layer to form a top common electrode structure, connected to the corresponding first type of electrode contact. A gap region is formed between two adjacent sub-pixels in the first pixel layer, and a non-common electrode conductive element passes through the gap region. The top of the non-common electrode conductive element inside the gap region is electrically connected to the bottom conductive layer of another sub-pixel in the second pixel layer, and the bottom is electrically connected to the corresponding first type of electrode contact. Light emitted by either 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 non-common electrode conductive element inside the gap region.

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