Anti-crosstalk micro-display light-emitting pixel and manufacturing method therefor

Abstract

The present invention relates to the technical field of semiconductors. Disclosed are an anti-crosstalk micro-display light-emitting pixel and a manufacturing method therefor. The micro-display light-emitting pixel comprises: a driving backplate; and a display module, wherein the display module is provided on the driving backplate, the display module comprises a light-emitting unit and a trench structure, the light-emitting unit is connected to an anode contact in the driving backplate, the trench structure surrounds the periphery of the light-emitting unit and runs through a vertical area where the display module is located, the trench structure is filled with a metal material, and the light-emitting unit is an inorganic compound semiconductor. On the basis of the technical solution provided by the present invention, light-emitting confinement can be realized by means of the through trench structure, thereby realizing better optical crosstalk isolation.

Description

Crosstalk-proof micro-display luminous pixel and manufacturing method thereof

[0001] This application claims priority to the following patent applications: Chinese patent application No. 202311840767.0 filed on December 29, 2023, entitled “Microdisplay luminescent pixel with anti-crosstalk, method for manufacturing the same, and microdisplay screen”; Chinese patent application No. 2024115515216 filed on November 1, 2024, entitled “Microdisplay luminescent pixel with anti-crosstalk, method for manufacturing the same”; Chinese patent application No. 2024115515216 filed on November 1, 2024, entitled “Microdisplay luminescent pixel with anti-crosstalk, method for manufacturing the same”; 24226685771, and the application name is “Micro-display luminescent pixel with anti-crosstalk”; the Chinese patent application with application number 2024226680301 filed on November 1, 2024, and the application name is “Micro-display luminescent pixel with anti-crosstalk”; the Chinese patent application with application number 2024226685729 filed on November 1, 2024, and the application name is “Micro-display luminescent pixel with anti-crosstalk”, all of which are incorporated by reference into this application. Technical Field

[0002] The present invention relates to the field of semiconductor technology, and in particular to a crosstalk-proof micro-display luminous pixel and a manufacturing method thereof. Background Art

[0003] In the field of semiconductor technology, crosstalk and light distribution between micro-display pixels have a significant impact on display quality and the efficiency of coupling into optical waveguides. For example, the emission angle of a normal vertically structured light emitting diode (LED) chip is around ±55°.

[0004] In the related art, the technical solutions of black matrix (BM) between pixels or making micro lenses (Micro Lens) are mostly used to achieve the constraints of crosstalk and luminous distribution between micro-display luminous pixels. In the black matrix solution, the black matrix is ​​an organic material system, which has insufficient temperature resistance and mechanical strength, and has reliability defects. In addition, the black matrix absorbs light, which will lead to overall brightness loss. In the micro lens solution, the prepared micro lens belongs to the organic material system, which has insufficient temperature resistance and mechanical strength, and has reliability defects. In addition, complete optical isolation cannot be achieved between pixels. When the pixel size continues to shrink, the luminous angle of ±55° will appear before entering the micro lens, that is, the problem of crosstalk between adjacent pixels will occur.

[0005] Therefore, there is an urgent need to provide a new solution for preparing micro-display luminescent pixels that can avoid the above-mentioned defects. Summary of the Invention

[0006] The object of the present invention is to provide a crosstalk-proof micro-display luminescent pixel and a manufacturing method thereof, which can achieve better optical crosstalk isolation by performing luminescence confinement through a through-type groove structure.

[0007] In order to achieve the above-mentioned object of the invention, the present invention proposes the following technical solutions:

[0008] In one aspect, a crosstalk-proof micro-display luminescent pixel is provided, wherein the size of the micro-display luminescent pixel is within the range of 0.5 μm to 50 μm, and the micro-display luminescent pixel comprises:

[0009] Driver backplane;

[0010] A display module is provided on the driving backplane, and the display module includes a light-emitting unit and a groove structure. The light-emitting unit is conductively connected to the anode contact in the driving backplane. The groove structure surrounds the light-emitting unit and passes through the vertical area where the display module is located. The groove structure is filled with metal material, and the light-emitting unit is an inorganic compound semiconductor.

[0011] In an optional embodiment, the display module at least includes: a first display device layer; the first display device layer includes:

[0012] a first light-emitting unit, wherein the first P-type ohmic contact layer in the first light-emitting unit is connected to a through-hole, and the first light-emitting unit is electrically connected to the anode contact in the driving backplane through the through-hole filled with a metal material;

[0013] a first insulating layer, the first insulating layer being filled and formed outside the first light-emitting unit;

[0014] A first groove structure, wherein the first groove structure runs through the first insulating layer, one end of the first groove structure is connected to the first N-type ohmic contact layer in the first light-emitting unit, and the other end is connected to the upper surface of the driving backplane.

[0015] In a possible implementation, a surface size of the through hole is smaller than a surface size of the first P-type ohmic contact layer.

[0016] In a possible implementation, the surface size of the through hole is larger than the surface size of the anode contact in the driving backplate.

[0017] In an optional embodiment, the display module further includes: a second display device layer disposed above the first display device layer; the second display device layer includes:

[0018] a second insulating layer, the second insulating layer being filled and formed on a side of the first display device layer away from the driving backplane;

[0019] A second trench structure is provided, wherein the second trench structure penetrates the second insulating layer and the first N-type ohmic contact layer, and one end of the second trench structure is connected to the first trench structure.

[0020] In an optional embodiment, the width of the second trench structure is smaller than the width of the first trench structure.

[0021] In an optional embodiment, the first N-type ohmic contact layer includes a first part and a second part stacked in a direction away from the driving backplane, the surface size of the second part is larger than the surface size of the first part, and one end of the first groove structure is connected to the second part.

[0022] In an optional embodiment, a second groove structure is connected to the first groove structure, and the bottom of the second groove structure passes through the second portion so that the second groove structure is connected to the first groove structure.

[0023] In an optional embodiment, the display module at least includes: a third display device layer; the third display device layer includes:

[0024] a second light-emitting unit, wherein a bonding layer is provided between the second P-type ohmic contact layer in the second light-emitting unit and the driving backplane, the second light-emitting unit is electrically connected to the anode contact in the driving backplane through the bonding layer, and a surface of the second N-type ohmic contact layer in the second light-emitting unit is partially covered with a cathode layer;

[0025] a third insulating layer, the third insulating layer being formed and filled outside the second light emitting unit;

[0026] A third trench structure is provided, wherein the third trench structure penetrates the third insulating layer, and one end of the third trench structure is connected to the cathode layer.

[0027] In an optional embodiment, the cathode layer includes: a middle cathode layer and side cathode layers on both sides, and the middle cathode layer is covered on the surface of the second N-type ohmic contact layer;

[0028] The sidewalls of the second light-emitting unit and the surface of the driving backplane are covered with a passivation layer, and the side cathode layer is covered on the surface of the passivation layer;

[0029] or,

[0030] The side cathode layer is covered on a surface of the third insulating layer that is away from the driving back plate.

[0031] In an optional embodiment, when the side cathode layer is covered on a surface of the third insulating layer away from the driving backplane, the sidewall of the second light-emitting unit and the surface of the driving backplane are further covered with a passivation layer.

[0032] In an optional embodiment, the groove structure is located inside the display module;

[0033] or,

[0034] The groove structure is located on the outer periphery of the display module.

[0035] In an optional embodiment, the groove pattern corresponding to the groove structure in a top view includes:

[0036] One of circle, rectangle, hexagon and octagon.

[0037] In an optional embodiment, the display module further includes: a micro lens;

[0038] The microlens is arranged on the light emitting unit and the groove structure.

[0039] In an optional embodiment, the metal material filled in the trench structure includes:

[0040] Aluminum, nickel, vanadium, and copper are deposited vertically in sequence;

[0041] or, deposited aluminum;

[0042] or, deposited tungsten.

[0043] In a possible implementation, the overall depth of the groove structure is not less than the overall depth of the light-emitting unit.

[0044] In a possible implementation, the width of the trench structure is in the range of 90 nm to 5 um.

[0045] In a possible implementation, the depth of the groove structure is in the range of 0.4 um to 5 um.

[0046] In a possible implementation, the angle of the groove structure gradually increases in a direction away from the driving backplate.

[0047] In another aspect, a method for preparing a micro-display luminescent pixel is provided. The method is used to prepare the micro-display luminescent pixel according to the above aspect, and the method comprises:

[0048] Prepare a driver backplane;

[0049] A display module combined with the driving backplane is prepared, wherein the display module includes a light-emitting unit and a groove structure, wherein the light-emitting unit is connected to the anode contact in the driving backplane, the groove structure surrounds the light-emitting unit and passes through the vertical area where the display module is located, the groove structure is filled with metal material, and the light-emitting unit is an inorganic compound semiconductor.

[0050] In an optional embodiment, the step of preparing a display module coupled to the driving backplane includes:

[0051] performing step etching on the inorganic compound semiconductor to prepare a first light-emitting unit;

[0052] Performing step-filling on the first light-emitting unit using an insulating material to form a first insulating layer;

[0053] Etching the first insulating layer to form a through hole connected to the first P-type ohmic contact layer in the first light-emitting unit and a first trench structure surrounding the first light-emitting unit;

[0054] Filling the through hole and the first trench structure with metal material, and combining the first light-emitting unit, the first insulating layer, and the first trench structure into a first display device layer;

[0055] The first display device layer is combined with the driving backplane through a hybrid bonding process. During the combination, the first light-emitting unit is connected to the anode contact in the driving backplane through the through hole filled with metal material.

[0056] In an optional embodiment, after combining the first display device layer with the driving backplane, the method further includes:

[0057] removing the compound substrate in the first light-emitting unit;

[0058] The surface of the first light-emitting unit is roughened after the substrate is removed.

[0059] In an optional embodiment, after forming the first display device layer, the method further includes:

[0060] Filling the first display device layer with an insulating material to form a second insulating layer;

[0061] Etching the second insulating layer to form a second trench structure having one end connected to the first trench structure;

[0062] The second trench structure is filled with metal material, and the second insulating layer and the second trench structure are combined to form a second display device layer.

[0063] In an optional embodiment, the step of preparing a display module coupled to the driving backplane includes:

[0064] The inorganic compound semiconductor with a bonding layer and the driving backplane with a bonding layer are bonded together by a hybrid bonding process, wherein the inorganic compound semiconductor is electrically connected to the anode contact in the driving backplane through the bonding layer during bonding;

[0065] performing step etching on the inorganic compound semiconductor and the bonding layer to prepare a second light-emitting unit;

[0066] The second light-emitting unit is step-filled with an insulating material to form a third insulating layer; the third insulating layer is etched to form a third trench structure surrounding the second light-emitting unit; the third trench structure is filled with a metal material; a portion of the third insulating layer on the top surface of the second light-emitting unit is removed using a patterning process to expose the second N-type ohmic contact layer in the second light-emitting unit; and a cathode layer is provided on a surface of the second N-type ohmic contact layer and on a side of the third insulating layer away from the driver backplane;

[0067] or,

[0068] A passivation layer is covered on the surface of the second light-emitting unit and the surface of the driving backplane; a patterning process is used to remove a portion of the passivation layer on the top surface of the second light-emitting unit to expose the second N-type ohmic contact layer in the second light-emitting unit; a cathode layer is covered on the surface of the second N-type ohmic contact layer and the surface of the passivation layer; the second light-emitting unit is step-filled with an insulating material to form a third insulating layer; the third insulating layer is etched to form a third trench structure surrounding the second light-emitting unit; and the third trench structure is filled with metal material.

[0069] In an optional embodiment, in a method corresponding to covering a cathode layer on a surface of the second N-type ohmic contact layer and a surface of the third insulating layer away from the driving backplane, before step-filling the second light-emitting unit with an insulating material to form the third insulating layer, the method further includes:

[0070] A passivation layer is provided on the surface of the second light emitting unit and the surface of the driving backplane.

[0071] In an optional embodiment, after preparing the display module coupled to the driving backplane, the method further includes:

[0072] A microlens is prepared on the light-emitting unit and the groove structure.

[0073] Compared with the prior art, the present invention has the following beneficial effects:

[0074] By etching a groove structure in the display module of the micro-display luminous pixel and filling the groove structure with metal material, better optical crosstalk isolation can be achieved through the through-type groove structure. The luminous angle can be customized by the depth of the groove structure. The design process of the groove structure is relatively mature, and mass production and yield are guaranteed.

[0075] Furthermore, the light-emitting unit and groove structure in the display module belong to an inorganic material system, which has good temperature resistance and mechanical strength, and its reliability is guaranteed.

[0076] Furthermore, the invention provides a back side groove structure design idea, a back side groove structure design idea, and a front and back side groove structure combined design idea, and different schemes can be freely selected according to needs. BRIEF DESCRIPTION OF THE DRAWINGS

[0077] FIG1 is a schematic diagram of an optical crosstalk phenomenon corresponding to the related art;

[0078] FIG2 is a schematic diagram of the structure of a micro-display luminescent pixel provided in an embodiment of the present application;

[0079] FIG3 is a circuit diagram of a driving circuit provided in an embodiment of the present application;

[0080] FIG4 is a schematic diagram of an optical crosstalk phenomenon corresponding to an embodiment of the present application;

[0081] FIG5 is a schematic diagram of the structure of a micro-display luminescent pixel provided in an embodiment of the present application;

[0082] FIG6 is a schematic diagram of a groove pattern provided in an embodiment of the present application;

[0083] FIG7 is a schematic diagram of the structure of a micro-display luminous pixel under a front groove structure design concept provided in an embodiment of the present application;

[0084] FIG8 is a schematic structural diagram of a micro-display luminous pixel with a micro-lens provided in an embodiment of the present application;

[0085] FIG9 is a schematic structural diagram of a micro-display luminous pixel with a micro-lens provided in an embodiment of the present application;

[0086] FIG10 is a schematic structural diagram of a micro-display luminous pixel under a back-surface groove structure design concept provided in an embodiment of the present application;

[0087] FIG11 is a schematic structural diagram of a micro-display luminous pixel according to a back-surface groove structure design concept provided in an embodiment of the present application;

[0088] FIG12 is a schematic structural diagram of a micro-display luminous pixel according to a back-surface groove structure design concept provided in an embodiment of the present application;

[0089] FIG13 is a schematic structural diagram of a micro-display luminous pixel according to a back-surface groove structure design concept provided in an embodiment of the present application;

[0090] FIG14 is a schematic diagram of a light emission constraint provided in an embodiment of the present application;

[0091] FIG15 is a schematic diagram of a light emission constraint provided in an embodiment of the present application;

[0092] FIG16 is a schematic structural diagram of a micro-display luminous pixel with a micro-lens provided in an embodiment of the present application;

[0093] FIG17 is a schematic structural diagram of a micro-display luminous pixel with a micro-lens provided in an embodiment of the present application;

[0094] FIG18 is a schematic structural diagram of a micro-display luminous pixel incorporating a front- and back-side groove structure design concept provided in an embodiment of the present application;

[0095] FIG19 is a schematic structural diagram of a micro-display luminous pixel with a micro-lens provided in an embodiment of the present application;

[0096] FIG20 is a flow chart of a method for preparing a micro-display luminescent pixel provided in an embodiment of the present application;

[0097] FIG21 is a schematic structural diagram of a driving backplane provided in an embodiment of the present application;

[0098] FIG22 is a schematic structural diagram of an inorganic compound semiconductor provided in an embodiment of the present application;

[0099] FIG23 is a schematic diagram of the structure of an inorganic compound semiconductor after step etching provided in an embodiment of the present application;

[0100] FIG24 is a schematic structural diagram of an inorganic compound semiconductor after a trench structure is prepared according to an embodiment of the present application;

[0101] FIG25 is a schematic structural diagram of a metal-filled inorganic compound semiconductor provided in an embodiment of the present application;

[0102] FIG26 is a schematic structural diagram of an inorganic compound semiconductor and a driving backplane provided in an embodiment of the present application;

[0103] FIG27 is a schematic structural diagram of a micro-display luminescent pixel after surface roughening provided in an embodiment of the present application;

[0104] FIG28 is a schematic structural diagram of an inorganic compound semiconductor after step etching provided in an embodiment of the present application;

[0105] FIG29 is a schematic structural diagram of an inorganic compound semiconductor with a bonding layer provided in an embodiment of the present application;

[0106] FIG30 is a schematic structural diagram of a driving backplane provided with a bonding layer in an embodiment of the present application;

[0107] FIG31 is a schematic structural diagram of an inorganic compound semiconductor and a driving backplane provided in an embodiment of the present application;

[0108] FIG32 is a schematic diagram of a structure after step etching of a bonding structure provided in an embodiment of the present application;

[0109] FIG33 is a schematic diagram of a structure in which a passivation layer and a cathode layer are covered on a second light-emitting unit according to an embodiment of the present application;

[0110] FIG34 is a schematic structural diagram of a bonding structure after step filling provided in an embodiment of the present application;

[0111] FIG35 is a schematic diagram of a bonding structure after a groove structure is prepared according to an embodiment of the present application;

[0112] FIG36 is a schematic structural diagram of a bonding structure after step filling provided in an embodiment of the present application;

[0113] Figure 37 is a structural schematic diagram of a bonding structure after a groove structure is prepared provided in an embodiment of the present application.

[0114] Figure 1: 10-driving backplane, 11-anode contact, 20-display module, 21-first display device layer, 22-second display device layer, 23-third display device layer, 30-light-emitting unit, 31-first light-emitting unit, 311-first P-type ohmic contact layer, 312-through hole, 313-first N-type ohmic contact layer, 316-first substrate, 317-first active quantum well layer, 32-second light-emitting unit, 321-second P-type ohmic contact layer Contact layer, 322-bonding layer, 323-second N-type ohmic contact layer, 324-second substrate, 325-second active quantum well layer, 40-trench structure, 41-first trench structure, 42-second trench structure, 43-third trench structure, 50-microlens, 61-first insulating layer, 62-second insulating layer, 63-third insulating layer, 70-cathode layer, 71-middle cathode layer, 72-side cathode layer, 80-passivation layer. DETAILED DESCRIPTION

[0115] To make the objectives, technical solutions, and advantages of the present invention more clear, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts shall fall within the scope of protection of the present invention.

[0116] In the description of the present invention, it should be understood that the orientations or positional relationships indicated by terms such as "vertical", "upper", "lower", "top", "side", "inside", and "outside" are based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first" and "second" are used for descriptive purposes only, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, unless otherwise specified, "multiple" means two or more.

[0117] In the description of the present invention, it should be noted that, unless otherwise expressly specified or limited, the terms "mounted," "connected," and "connected" should be understood in a broad sense. For example, they may refer to fixed, detachable, or integral connections; mechanical or electrical connections; direct or indirect connections through an intermediate medium; and internal communication between two components. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on specific circumstances.

[0118] Traditional anti-crosstalk designs for micro-display luminous pixels have many drawbacks, such as:

[0119] Regarding the crosstalk prevention design for fabricating microlenses, the microlenses fabricated using this solution are made of organic materials, which have limited temperature resistance and mechanical strength, reliability issues, and incomplete optical isolation between pixels. As pixel size continues to shrink, crosstalk between adjacent pixels can occur before entering the microlens at an emission angle of ±55°. For example, Figure 1 illustrates this issue. A vertical GaN Micro LED device with a 4µm pixel size and a 2µm light-emitting unit exhibits the smallest emission angle of ±55° compared to conventional LED devices, lower than the ±60-70° emission angles of horizontal and flip-chip LED devices. At an emission angle of ±55°, optical crosstalk between adjacent pixels cannot be completely isolated because light emitted from the active light-emitting area travels through the entire light-emitting unit and exits at multiple angles. The actual light angles are more complex than those shown in Figure 1 due to multiple refractions and reflections within the light-emitting unit, exacerbating the optical crosstalk between pixels.

[0120] Regarding the anti-crosstalk design scheme using a black matrix, the black matrix uses the light absorption properties of the black matrix material to block light and achieve optical crosstalk isolation between pixels. The black matrix is ​​an organic material system, which has insufficient temperature resistance and mechanical strength, and has reliability defects. In addition, the black matrix absorbs light, which will lead to overall brightness loss. In some schemes, a trapezoidal structure similar to the black matrix is ​​formed by metal patterning deposition and tearing gold to circumvent reliability issues. However, neither the black matrix nor the metal patterning tearing gold scheme can adapt to extremely small pixel sizes. For example, when the pixel size dives below 5um, the resolution of the black matrix and the problem of photoresist mask delamination of the metal patterning tearing gold pose challenges to yield and mass production capabilities.

[0121] In order to avoid the above problems, in an embodiment of the present application, a technical solution is proposed to achieve better optical crosstalk isolation by performing light confinement through a through-type groove structure.

[0122] It can be understood that the groove structure in the embodiment of the present application is a technology applied in the field of micro-display (Micro-LED). The groove structure is prepared using metal materials and has the characteristics of optical crosstalk optimization, luminous angle convergence, enhanced electrical transmission function, high temperature resistance and other harsh environments. It is quite different from similar structures in traditional large-panel displays.

[0123] On the one hand, similar structures in traditional large-panel displays cannot be directly applied to the field of micro-displays. For traditional large-panel displays, such as CN110969952A, which is a typical traditional large-panel display structure, LED is used as the backlight source. However, due to the large spacing between the LED lamp beads, the image display has a strong sense of graininess, and the brightness distribution is extremely uneven, which makes the audience feel glaring. Therefore, a hollow grid structure prepared by methods such as compression molding, printing, and spraying is generally used. This hollow grid structure is placed around the LED to constrain the luminous range, and after the light is irradiated to the diffusion film, the light is evenly distributed through the diffusion film to achieve a relatively uniform display effect. The function of the hollow grid structure of this scheme can be used as a common pixel crosstalk isolation method, but after entering the micro-display field, the preparation of the hollow grid and the alignment accuracy with the LED light source cannot be achieved, so other solutions are needed in the micro-display field to achieve similar functions.

[0124] On the other hand, the typical traditional large-panel display structure shown in CN110969952A, in which the light shielding frame can also play a role in optimizing optical crosstalk, has the following differences compared with the groove structure in this patent application:

[0125] (1) The pixel pitch and pixel size in CN110969952A are generally large, basically in the order of hundreds of microns or even several millimeters. The line width requirement for the light shielding frame between pixels is not high. The light shielding frame is mostly made of organic materials, such as vinyl, and its temperature resistance is generally around 200°C or below. The groove structure in this application is used in the field of micro-display. The pixel pitch and pixel size are generally in the order of microns to tens of microns. The groove structure is made of metal material, which has very high temperature resistance.

[0126] (2) Due to the difference in the implementation materials, the light shielding frame in CN110969952A only has an optical function, while the groove structure in the present application also plays a role in enhancing the electrical transmission function and better expanding the current distribution. Its connection with the cathode or cathode-related connection of the light-emitting unit should form good contact and uniformly distribute the current.

[0127] Next, the specific structure of the micro-display luminescent pixel proposed in this application is described.

[0128] The present invention provides a crosstalk-proof micro-display luminescent pixel (hereinafter referred to as a micro-display luminescent pixel). The micro-display luminescent pixel has a size ranging from 0.5 μm to 50 μm. As shown in FIG2 , the micro-display luminescent pixel includes:

[0129] A driving backplane 10; a display module 20, wherein the display module 20 is disposed on the driving backplane 10, and the display module 20 includes a light-emitting unit 30 and a groove structure 40, wherein the light-emitting unit 30 is electrically connected to the anode contact in the driving backplane 10, and the groove structure 40 surrounds the light-emitting unit 30 and penetrates the vertical area where the display module 20 is located, and the groove structure 40 is filled with metal material, and the light-emitting unit 30 is an inorganic compound semiconductor.

[0130] Among them, the driving backplane 10 is an active driving backplane that is a combination of one or more thin film transistors (TFT), low temperature polycrystalline silicon (LTPS), CMOS integrated circuits, high mobility transistors (HEMT), etc. Specifically, the driving backplane 10 is provided with a driving circuit, and the driving circuit is provided with at least one anode contact 11. Exemplarily, the circuit structure of the driving circuit is shown in Figure 3. It should be noted that the driving circuit in this embodiment is an active drive, and the circuit diagram shown in this embodiment is only a simple schematic diagram. The driving circuit may include an active, passive or semi-passive control circuit. All anodes included in the driving circuit can be arranged linearly or in an array, and any anode contact 11 is located in the middle or at the edge of the driving backplane 10. This embodiment does not limit this.

[0131] The display module 20 is designed with a through-groove structure 40. This groove structure 40 surrounds the light-emitting unit 30 in the display module 20 and is filled with a metal material. The light-emitting unit 30 is an inorganic compound semiconductor. The entire display module 20 is a purely inorganic structure with high reliability. For example, as shown in Figure 4, the design of the groove structure 40 (i.e., the TI structure in the figure) can constrain the light emission angle, thereby preventing optical crosstalk between adjacent micro-display light-emitting pixels.

[0132] Furthermore, as shown in Figure 5, the display module 20 also includes a microlens 50, which is disposed above the light-emitting unit 30 and the groove structure 40. The microlens 50 can be disposed on top of the display module 20, providing basic light confinement through the groove structure 40 and further isolating the light emitted by the light-emitting unit 30 from optical crosstalk. The material of the microlens 50 can be a compound semiconductor or a subsequently deposited dielectric material such as silicon oxide or silicon nitride.

[0133] Furthermore, the light-emitting unit 30 in the display module 20 is an inorganic compound semiconductor, usually a wafer or a suitable size area cut from a wafer. Taking a wafer as an example, the wafer refers to a compound formed by two or more elements with a certain atomic ratio, and has a certain semiconductor properties such as a band gap and a band structure. It can be a crystalline inorganic compound (such as a III-V group or a II-VI group compound semiconductor), and then a layer for forming an electrical contact is prepared on the surface of the compound, and when the compound is subsequently stacked, it can be arbitrarily combined. In this embodiment, the light-emitting unit 30 involves ultraviolet light, green light, blue light AlGaN, InGaN ternary material system, and its substrate material can be GaN, Si, SiC, Sapphire, etc., as well as long waves such as red light and infrared, among which the red light can be an InGaN ternary material system or a quaternary AlGaInP red light compound LED epitaxial on a GaAs substrate, and the infrared mainly includes compound epitaxy of material systems such as InP, GaAs, and AlGaAs. In addition, this embodiment does not limit the shape of the light emitting unit 30 in a top view, and can be a circle or other polygons, such as a rectangle, hexagon, octagon, etc. In addition, the etching depth of the light emitting unit 30 can be in the range of 0.3um to 3um.

[0134] In one embodiment, when the light-emitting unit 30 includes a red-light compound epitaxy, the red-light compound epitaxy may be a quaternary AlGaInP or a ternary InGaN material, and may be based on a substrate such as GaAs, Si, Sapphire, or Ga2O3. The following Table 1 is a simplified structural example, where P-GaAs may be replaced by P-GaP and P-AlGaAs:

[0135] Table 1

[0136] In one embodiment, when the light emitting unit 30 includes a blue light or green light compound semiconductor, the blue light or green light compound semiconductor is an InGaN ternary compound and can be based on a substrate such as Si, Sapphire, or Ga2O3. An example of its structure is shown in Table 2 below:

[0137] Table 2

[0138] In one embodiment, when the light emitting unit 30 includes an ultraviolet compound semiconductor, the ultraviolet compound semiconductor is an AlGaN ternary compound and can be based on a substrate such as Si, Sapphire, or SiC. An example of its structure is shown in Table 3 below:

[0139] Table 3

[0140] In one embodiment, when the light emitting unit 30 includes an infrared compound semiconductor, the infrared compound semiconductor is an AlGaAs ternary compound and can be based on a substrate such as GaAs or InP. An example of its structure is shown in Table 4 below:

[0141] Table 4

[0142] As shown in Tables 1 to 4 above, by selecting different compound materials to prepare devices, light-emitting components with different wavelengths can be obtained. Different materials are selected as P-type and N-type ohmic contact layer materials according to the characteristics of different compounds. For example, the P-type ohmic contact layer uses ITO transparent conductive film, and the N-type ohmic contact layer uses metal In+ITO transparent conductive film, which can be used as universal ohmic contact materials. In particular, the P-type ohmic contact layer of GaN can be a single layer or a stack of metals such as Ni, Au, Ag, and Al, and the N-type ohmic contact layer can be a single layer or a stack of metals such as Ti, Cr, Ni, and Al. The P-type ohmic contact layer of GaAs can be a single layer, an alloy, or a stack of metals such as Au, Be, and Zn, and the N-type ohmic contact layer can be a single layer, an alloy, or a stack of metals such as Au, Ge, Ni, Pt, and In.

[0143] Furthermore, the metal materials filled in the trench structure 40 include: aluminum (Al), nickel vanadium (NiV), and copper (Cu) deposited vertically in sequence; or, deposited aluminum; or, deposited tungsten (W). In the trench structure 40, the metal material filled can be Cu electroplated after plasma vapor deposition of seed layers Al and NiV, wherein Al can be used as a reflective metal to increase brightness, and Al can also be used as a step to etch the N-type ohmic contact metal of the N-type ohmic contact layer to achieve N connection, NiV as an adhesion layer and barrier layer for adhering Al, Cu and blocking the migration of Al, and Cu is used for electroplating. Further, NiV can be replaced by any one of Ni, Ti, and TiN; the metal material can also be a metal directly plasma vapor deposited at room temperature or thermally deposited, such as metal Al or metal W. Further, TIN metal deposition can be performed before Al or W deposition. It is understood that, in addition to the above-mentioned types of metal materials, the seed layer in the groove structure 40 can also be composed of a single layer or multiple layers of metals such as Ti, Ni, Cr, Au, Ge, Al, Pt, Ta, W, or their nitrides, and this application does not specifically limit this. Furthermore, the corresponding groove pattern of the groove structure 40 when viewed from above includes: one of: a circle, a rectangle, a hexagon, and an octagon. When looking down at the micro-display light-emitting pixel, the groove pattern surrounding the light-emitting unit can be a circle, a rectangle, a hexagon, an octagon, etc., and this embodiment does not limit this.

[0144] Furthermore, the groove structures 40 corresponding to adjacent light-emitting units are interconnected; or, the groove structures 40 corresponding to adjacent light-emitting units are isolated from each other by an insulating medium. The groove structures 40 can be implemented as shown in FIG6 to connect pixels, or as shown in FIG6 to connect pixels within pixels. FIG6 only uses circular and rectangular groove patterns as examples for illustrative purposes.

[0145] Furthermore, the overall depth of the trench structure 40 is no less than the overall depth of the light-emitting unit 30. When etching the trench structure, the corresponding etching depth of the trench structure 40 is greater than or equal to the corresponding etching depth of the light-emitting unit 30, thereby ensuring that the trench structure 40 has sufficient depth to constrain the emission angle of the light-emitting unit 30. Furthermore, the depth of the trench structure is within the range of 0.4 μm to 5 μm.

[0146] Furthermore, the width of the trench structure 40 is within the range of 90 nm to 5 μm. By designing the width of the trench structure 40 within a certain range, the trench structure 40 is prevented from occupying too much horizontal space of the pixel while ensuring sufficient thickness to prevent crosstalk.

[0147] Furthermore, the angle of the groove structure 40 gradually increases in the direction away from the driving backplane 10. The groove structure 40 formed can be realized through multiple angles from bottom to top, such as through multiple angles that gradually increase in the direction away from the driving backplane 10, so as to first strictly constrain the luminous angle from the bottom, and then evenly emit light through the top. In addition, the groove structure 40 can also be realized from bottom to top at an angle. In addition, the above-mentioned angle can be in the range of 90°±30°, with 90°±10° being optimal. In the present application, based on the differences in the order of the groove preparation process, three different specific structural design ideas for micro-display luminous pixels are provided.

[0148] (1) The micro-display luminous pixel adopts a front groove structure design concept. In the preparation process corresponding to this structural design, the groove structure 40 is first prepared in the display module 20, and then the display module 20 is combined with the driving backplane 10.

[0149] Specifically, as shown in FIG7 , the display module 20 includes at least: a first display device layer 21; the first display device layer 21 includes: a first light-emitting unit 31, wherein a first P-type ohmic contact layer 311 in the first light-emitting unit 31 is connected to a through-hole 312, and the first light-emitting unit 31 is electrically connected to the anode contact in the driver backplane 10 via the through-hole 312 filled with a metal material; a first insulating layer 61, wherein the first insulating layer 61 is formed outside the first light-emitting unit 31; and a first trench structure 41, wherein the first trench structure 41 extends through the first insulating layer 61, one end of the first trench structure 41 is connected to the first N-type ohmic contact layer 313 in the first light-emitting unit 31, and the other end is connected to the upper surface of the driver backplane 10, extending from the plane to the periphery of the display area and connecting to the outer common cathode of the driver backplane 10. The metal material filled in the through-hole 312 can be the same as or different from the metal material filled in the first trench structure 41, such as using the same deposited Al, NiV, or Cu. The first insulating layer 61 can be a single layer or a stack of dielectric layers such as silicon oxide, silicon nitride, SiC, SICN, Ti3O5, or Ni2O5. The thickness of the first insulating layer 61 and the depth of the first trench structure 41 are generally substantially equal to the thickness of the first light-emitting unit 31, and the depth of the first trench structure 41 is limited by the thickness of the first light-emitting unit 31.

[0150] Furthermore, the surface size of the through hole 312 is smaller than the surface size of the first P-type ohmic contact layer 311. Furthermore, the surface size of the through hole 312 is larger than the surface size of the anode contact in the driver backplane 10. Since the through hole 312 in the display device layer needs to be aligned with the anode contact in the driver backplane 10 for bonding, the above-mentioned size design can reduce the difficulty of bonding and facilitate process preparation.

[0151] Furthermore, as shown in FIG7 , the first N-type ohmic contact layer 313 includes a first portion and a second portion stacked in a direction away from the driver backplane 10 , wherein the surface size of the second portion is larger than the surface size of the first portion, and one end of the first trench structure 41 is connected to the second portion. The cathode electrical structure is prepared by thinning the second portion.

[0152] Furthermore, as shown in Figures 8 and 9, a microlens 50 can be disposed on the first display device layer 21. In accordance with the front-side groove structure design, in one embodiment, as shown in Figure 8, the microlens 50 does not interrupt the first N-type ohmic contact layer 313 during etching. In another embodiment, as shown in Figure 9, the microlens 50 partially interrupts the first N-type ohmic contact layer 313 during etching, achieving N-type contact to the cathode in some areas while completely isolating the micro-display pixels.

[0153] (2) The micro-display luminous pixel adopts a back-side groove structure design concept. In the preparation process corresponding to this structural design, the display module 20 is first combined with the driving backplane 10, and then the groove structure 40 is prepared in the display module 20.

[0154] Specifically, as shown in Figures 10 to 13, the display module 20 includes at least: a third display device layer 23; the third display device layer 23 includes: a second light-emitting unit 32, wherein a bonding layer 322 is provided between the second P-type ohmic contact layer 321 in the second light-emitting unit 32 and the driving backplane 10, and the second light-emitting unit 32 is electrically connected to the anode contact in the driving backplane 10 via the bonding layer 322; and a surface of the second N-type ohmic contact layer 323 in the second light-emitting unit 32 is partially covered with a cathode layer 70; a third insulating layer 63, wherein the third insulating layer 63 is formed to fill the exterior of the second light-emitting unit 32; and a third trench structure 43, wherein the third trench structure 43 extends through the third insulating layer 63, and one end of the third trench structure 43 is connected to the cathode layer 70. The bonding layer 322 can be an opaque metal material, such as a single layer or multiple layers of a metal such as Au, Sn, Al, Cu, or W, or a transparent metal oxide material, such as a transparent conductive film such as ITO or ZnO. The third insulating layer 63 can be a single layer or a stack of dielectric layers such as silicon oxide, silicon nitride, SIC, SICN, Ti3O5, or Ni2O5. The thickness of the third insulating layer 63 and the depth of the third trench structure 43 are greater than or equal to the thickness of the second light-emitting unit 32. The depth of the third trench structure 43 can be set to any value greater than or equal to the thickness of the second light-emitting unit 32. For example, based on the structure shown in FIG10 , when the depth of the third trench structure 43 is equal to the height of the second light-emitting unit 32, as shown in FIG14 , the luminous angle is reduced from the initial ±55° to ±45°; based on the structure shown in FIG11 , when the depth of the third trench structure 43 is more than twice the height of the second light-emitting unit 32, as shown in FIG15 , the luminous angle is reduced from the initial ±55° to ±17°.

[0155] Furthermore, the cathode layer 70 includes a middle cathode layer 71 and side cathode layers 72 on both sides. The middle cathode layer 71 covers the surface of the second N-type ohmic contact layer 323 .

[0156] In one possible design, as shown in Figures 10 and 11, the side walls of the second light-emitting unit 32 and the surface of the driving backplane 10 are covered with a passivation layer 80, and the side cathode layer 72 is covered on the surface of the passivation layer 80. The passivation layer 80 can be a single layer or a stack of dielectric layers such as Al2O3, SiO2, or Si3N4. The second light-emitting unit 32 and the driving backplane 10 are insulated and protected by the passivation layer 80, and a common cathode connection is achieved through the side cathode layer 72 covered on the surface of the passivation layer 80 and the intermediate cathode layer 71 covered on the surface of the second N-type ohmic contact layer 323.

[0157] In another possible design, as shown in FIG12 , a side cathode layer 72 is provided on a surface of the third insulating layer 63 away from the driving backplane 10. A common cathode connection is achieved through the side cathode layer 72 provided on the surface of the third insulating layer 63 and the middle cathode layer 71 provided on the surface of the second N-type ohmic contact layer 323.

[0158] Furthermore, as shown in FIG13 , when the side cathode layer 72 is covered on the side surface of the third insulating layer 63 away from the driving backplane 10, the side wall of the second light-emitting unit 32 and the surface of the driving backplane 10 are also covered with a passivation layer 80. The passivation layer 80 can be a single layer or a stack of dielectric layers such as Al2O3, SiO2, or Si3N4. That is, the third insulating layer 63 can be directly connected to the surface of the driving backplane 10 as shown in FIG12 , without providing the passivation layer 80 between the third insulating layer 63 and the driving backplane 10, and the dielectric layer on the driving backplane 10 is used to withstand the etching; or, as shown in FIG13 , a passivation layer 80 can be provided between the third insulating layer 63 and the driving backplane 10, and the passivation layer 80 is used as an etching stop layer, and the second light-emitting unit 32 and the driving backplane 10 are insulated and protected by the passivation layer 80.

[0159] Furthermore, a microlens 50 may be provided on the third display device layer 23. For example, the structure shown in FIG16 corresponds to the structure of FIG11 with a microlens 50 added thereto, and the structure shown in FIG17 corresponds to the structure of FIG13 with a microlens 50 added thereto.

[0160] (3) The micro-display luminous pixel adopts a design concept of combining front and back groove structures. In the preparation process corresponding to this structural design, the front groove structure design concept is first adopted to prepare a group of groove structures 40 in a display device layer in the display module 20, and then the display module 20 is combined with the driving backplane 10. Subsequently, the back groove structure design concept is further adopted. For the combined device, another display device layer is added to the display module 20 to prepare another group of groove structures 40.

[0161] Specifically, as shown in FIG18 , based on the first display device layer 21 , the display module 20 further includes: a second display device layer 22 disposed on the first display device layer 21 ; the second display device layer 22 includes: a second insulating layer 62 , the second insulating layer 62 being formed to fill the side of the first display device layer 21 away from the driver backplane 10 ; and a second groove structure 42 , the second groove structure 42 extending through the second insulating layer 62 and the first N-type ohmic contact layer 313 , with one end of the second groove structure 42 connected to the first groove structure 41 . The second insulating layer 62 may be a single layer or a stack of dielectric layers such as silicon oxide, silicon nitride, SIC, SICN, Ti3O5, or Ni2O5 . The thickness of the second insulating layer 62 and the depth of the second groove structure 42 are not related to the thickness of the first light-emitting unit 31 , and the depth of the second groove structure 42 can be freely set.

[0162] Furthermore, the width of the second trench structure 42 is smaller than that of the first trench structure 41. This not only reduces photolithography alignment deviation and reduces process difficulty, but also ensures that the first trench structure 41 is connected to the first N-type ohmic contact layer 313 to achieve cathode connectivity. Typically, the second trench structure 42 on the back side is 50% the size of the first trench structure 41 on the front side.

[0163] Furthermore, as shown in FIG18 , the first N-type ohmic contact layer 313 includes a first portion and a second portion stacked in a direction away from the driver backplane 10 . The surface size of the second portion is larger than the surface size of the first portion. One end of the first trench structure 41 is connected to the second portion. The cathode electrical structure is prepared by thinning the second portion.

[0164] Furthermore, a second trench structure 42 is connected to the first trench structure 41 , and a bottom of the second trench structure 42 passes through the second portion so that the second trench structure 42 is connected to the first trench structure 41 .

[0165] Furthermore, as shown in FIG. 19 , a microlens 50 may be disposed on the second display device layer 22 .

[0166] In summary, the micro-display luminescent pixel provided in the embodiment of the present application achieves better optical crosstalk isolation by etching a groove structure in the display module of the micro-display luminescent pixel and filling the groove structure with metal material. The through-type groove structure can be used to customize the light-emitting angle through the depth of the groove structure. In addition, the design process of the groove structure is relatively mature, and mass production and yield are guaranteed.

[0167] Furthermore, the light-emitting unit and groove structure in the display module belong to an inorganic material system, which has good temperature resistance and mechanical strength, and its reliability is guaranteed.

[0168] Furthermore, the invention provides a back side groove structure design idea, a back side groove structure design idea, and a front and back side groove structure combined design idea, and different schemes can be freely selected according to needs.

[0169] Next, a method for preparing the micro-display luminescent pixel described in the above embodiment is described. The method is used to prepare the micro-display luminescent pixel described in the above embodiment. As shown in FIG20 , the method may include the following steps:

[0170] S1: Prepare the driver backplane.

[0171] Illustratively, the cross-sectional structure of a single pixel of the driving backplane is shown in FIG21 . The driving backplane 10 includes a penetrating anode contact 11 , and an insulating medium is provided around the anode contact 11 .

[0172] S2: Prepare a display module combined with a driving backplane, wherein the display module includes a light-emitting unit and a groove structure. The light-emitting unit is connected to the anode contact in the driving backplane. The groove structure surrounds the light-emitting unit and penetrates the vertical area where the display module is located. The groove structure is filled with metal material, and the light-emitting unit is an inorganic compound semiconductor.

[0173] Illustratively, the cross-sectional structure of the inorganic compound semiconductor is shown in FIG22 , and the inorganic compound semiconductor includes at least the following layers stacked in sequence from bottom to top: a first substrate 316 , a first N-type ohmic contact layer 313 , a first active quantum well layer 317 and a first P-type ohmic contact layer 311 .

[0174] In one possible embodiment, after S2, the following step is further included: forming a microlens on the light-emitting unit and the groove structure. The microlens can be formed by etching, and the microlens material can be a compound semiconductor or a subsequently deposited dielectric material such as silicon oxide or silicon nitride.

[0175] With respect to the front groove structure design concept in the above embodiment, S2 may specifically include the following steps:

[0176] S211: performing step etching on the inorganic compound semiconductor to prepare a first light-emitting unit.

[0177] Specifically, as shown in FIG23 , a patterned etching scheme such as plasma dry etching is used to perform step etching on the inorganic compound semiconductor until the first N-type ohmic contact layer 313 is etched to prepare the first light-emitting unit 31 , and the etching depth is in the range of 0.3 μm to 3 μm.

[0178] S212: performing step-filling on the first light-emitting unit using an insulating material to form a first insulating layer.

[0179] Specifically, a single layer or a stack of dielectric layers such as silicon oxide, silicon nitride, SIC, SICN, Ti3O5, or Ni2O5 is used to perform step filling on the first light-emitting unit to form a first insulating layer.

[0180] S213: Etching the first insulating layer to form a through hole connected to the first P-type ohmic contact layer in the first light-emitting unit and a first trench structure surrounding the first light-emitting unit.

[0181] Specifically, as shown in FIG24 , the first insulating layer 61 is etched using a patterned etching scheme such as plasma dry etching to form a through hole for the first P-type ohmic contact layer 311 and trench isolation around the first light-emitting unit 31. The thickness of the first insulating layer 61 and the depth of the first trench structure 41 are greater than or equal to the pixel etching depth, generally ranging from 0.4 μm to 5 μm. The width of the first trench structure 41 is between 90 nm and 5 μm. The angle of the first trench structure 41 is 90°±30°, with 90°±10° being optimal.

[0182] S214: filling the through hole and the first trench structure with metal material, and combining the first light-emitting unit, the first insulating layer, and the first trench structure into a first display device layer.

[0183] Specifically, as shown in Figure 25, the through hole 312 and the first trench structure 41 are filled with metal materials through a metal backfill process, for example: metal Al, NiV, and Cu are deposited in the through hole 312 and the first trench structure 41 in sequence; or, metal Al is deposited in the through hole 312 and the first trench structure 41; or, metal W is deposited in the through hole 312 and the first trench structure 41. This structure can simultaneously complete the optical pixel string isolation and the electrical connection of the cathode. The seed layer corresponding to the filled metal material can also be a single layer or multiple layers of metals such as Ti, Ni, Cr, Au, Ge, Al, Pt, Ta, W, or their nitrides. Furthermore, after the filling is completed, chemical mechanical planarization (CMP) can be used to remove excess metal from the surface of the filled metal material and perform a planarization process.

[0184] S215: combining the first display device layer with the driving backplane through a hybrid bonding process, wherein the first light-emitting unit is connected to the anode contact in the driving backplane through the through hole filled with metal material.

[0185] As shown in FIG26 , when combined, the metal through-hole area in the first display device layer 21 is connected to the anode contact 11 of the driving backplane, and the cathode of the first display device layer 21 is connected to the outer common cathode of the driving backplane 10 through the first groove structure 41 .

[0186] In one possible implementation, after S215, the following steps are further included: removing the compound substrate from the first light-emitting unit; and roughening the surface of the first light-emitting unit after the substrate is removed. The compound substrate is removed from the combined first light-emitting unit 31. By removing the substrate and thinning the compound, N-contact conduction is achieved while the cathode is thinned, reducing optical crosstalk between pixels, resulting in the structure shown in Figure 7. Furthermore, as shown in Figure 27, the surface of the first light-emitting unit 31 after the substrate is removed is roughened to enhance light extraction efficiency.

[0187] It is understandable that if the above-mentioned front groove structure design concept is adopted, the advantage is that an N-type ohmic contact can be directly formed with the first light-emitting unit; the disadvantage is that the pattern of the first light-emitting unit has been defined during bonding, and a certain precision is required to combine with the driving backplane. At the same time, it is limited by the thickness of the first light-emitting unit in the first display device layer, and the thickness of the first groove structure cannot be customized very flexibly.

[0188] It can be understood that in the above steps S211 to S215, subsequent preparation is carried out based on step etching to the first N-type ohmic contact layer. In another design, the step etching can completely etch through the inorganic compound semiconductor except the first substrate 316 as shown in Figure 28. Accordingly, a process step is added to extend the first N-type ohmic contact layer 311 to connect it to the first groove structure 41, so as to connect the cathode of the first display device layer 21 to the peripheral common cathode of the driving backplane 10 through the first groove structure 41.

[0189] In view of the front and back groove structures combined with the design ideas in the above embodiment, after S215, the following steps may be further included:

[0190] S216: Filling the first display device layer with an insulating material to form a second insulating layer.

[0191] Specifically, a single layer or a stack of dielectric layers such as silicon oxide, silicon nitride, SIC, SICN, Ti3O5, or Ni2O5 is used to fill the first display device layer to form the second insulating layer.

[0192] S217: Etching the second insulating layer to form a second trench structure having one end connected to the first trench structure.

[0193] Specifically, the second insulating layer is etched using a patterned etching scheme such as plasma dry etching to achieve trench isolation in the second insulating layer around the first light-emitting unit. This trench isolation is the second trench structure. The width of the second trench structure ranges from 90nm to 5um, and the angle of the second trench structure ranges from 90°±30°, with 90°±10° being optimal.

[0194] S218: filling the second trench structure with metal material, and combining the second insulating layer and the second trench structure into a second display device layer.

[0195] Specifically, the second trench structure is filled with metal materials through a metal backfill process, for example: metal Al, NiV, and Cu are sequentially deposited in the second trench structure; or, metal Al is deposited in the second trench structure; or, metal W is deposited in the second trench structure. This structure can simultaneously complete the optical pixel string isolation and the electrical connection of the cathode. The seed layer corresponding to the filled metal material can also be a single layer or multiple layers of metals such as Ti, Ni, Cr, Au, Ge, Al, Pt, Ta, W, or their nitrides. Furthermore, after the filling is completed, CMP can be used to remove excess metal from the surface of the filled metal material and perform a flattening process.

[0196] It can be understood that if the above-mentioned front and back groove structures are combined with the design concept, the advantage is that an N-type ohmic contact can be directly formed with the first light-emitting unit, and the depth of the second groove structure on the back can be customized very flexibly; the disadvantage is that the first light-emitting unit has a defined pattern during bonding, and a certain precision is required to combine with the driving backplane, which increases the process cost.

[0197] Regarding the backside trench structure design concept in the above embodiment, S2 may specifically include the following steps:

[0198] S221: combining an inorganic compound semiconductor with a bonding layer and a driving backplane with a bonding layer through a hybrid bonding process, wherein the inorganic compound semiconductor is electrically connected to the anode contact in the driving backplane through the bonding layer during the combination.

[0199] Specifically, as shown in Figures 29 and 30, a bonding layer 322 is prepared on an inorganic compound semiconductor, and a bonding layer 322 is also prepared on the wafer of the driving backplane 10. The combined structure is shown in Figure 31. The bonding layer 322 is conductive and can be an opaque metal material, such as a single layer or multiple layers of metals such as Au, Sn, Al, Cu, and W. The bonding layer 322 can also be a transparent metal oxide material, such as transparent conductive films such as ITO and ZnO.

[0200] Furthermore, a metal such as Cr, Ni, Ti, or TiN is provided as an adhesion layer between the inorganic compound semiconductor / driver backplane 10 and the bonding layer 322 to enhance adhesion between the two. Furthermore, as shown in FIG31 , after the compound wafer is integrated with the driver backplane 10 wafer through a bonding process, the inorganic compound semiconductor second substrate 324 can be removed for subsequent device fabrication.

[0201] S222: performing step etching on the inorganic compound semiconductor and the bonding layer to prepare a second light-emitting unit.

[0202] Specifically, as shown in FIG32 , step etching is performed using a patterned etching scheme such as plasma dry etching to complete the preparation of the second light-emitting unit 32 and the patterning of the bonding layer 322 . The etching depth corresponding to the second light-emitting unit 32 is in the range of 0.3 um to 3 um.

[0203] S223a: A passivation layer is provided on the surface of the second light-emitting unit and the surface of the driving backplane; a patterning process is used to remove part of the passivation layer on the top surface of the second light-emitting unit to expose the second N-type ohmic contact layer in the second light-emitting unit; a cathode layer is provided on the surface of the second N-type ohmic contact layer and the surface of the passivation layer; the second light-emitting unit is step-filled with an insulating material to form a third insulating layer; the third insulating layer is etched to form a third trench structure surrounding the second light-emitting unit; and the third trench structure is filled with metal material.

[0204] In step S223a, a common cathode connection is made before the trench process. The micro-display light-emitting pixel produced by this step is shown in Figures 10 and 11. Specifically, after passivation and patterned opening, the second N-type ohmic contact layer 323 in the second light-emitting unit 32 is exposed for contact preparation. Then, a cathode layer 70 is prepared. The structure of the completed cathode layer 70 is shown in Figure 33. This cathode layer 30 is connected to a transparent conductive film with a common cathode. The transparent conductive film can be a single layer or multiple layers of a transparent conductive film such as ITO or ZnO. In some embodiments, the resistance and transmittance of the transparent conductive film can be optimized by metal doping such as Au, Ag, and Al. Then, a dielectric layer is further grown, using a plasma deposition process such as silicon glass, to form a third insulating layer 63. After planarization, the third trench structure 43 is etched. The thickness of the third insulating layer 63 and the depth of the third trench structure 43 are greater than or equal to the pixel etching depth, generally ranging from 0.4 μm to 5 μm. The width of the third trench structure 43 is between 90 nm and 5 μm, and the angle of the third trench structure 43 is between 90°±30°, with 90°±10° being optimal. After etching, metal filling is performed, for example, sequentially depositing metals such as Al, NiV, and Cu in the third trench structure 43; or depositing metal Al in the third trench structure 43; or depositing metal W in the third trench structure 43. This structure can simultaneously achieve optical pixel string isolation and cathode electrical connection. The corresponding seed layer of the metal filling material can also be composed of a single layer or multiple layers of metals such as Ti, Ni, Cr, Au, Ge, Al, Pt, Ta, W, or their nitrides. Furthermore, after the filling is completed, CMP can be used to remove excess metal from the surface of the filled metal material and flatten it. Furthermore, when preparing the third trench structure 43, the IO and the peripheral common cathode can be filled with metal simultaneously to achieve functional improvement.

[0205] S223b: Use an insulating material to step-fill the second light-emitting unit to form a third insulating layer; etch the third insulating layer to form a third trench structure surrounding the second light-emitting unit; fill the third trench structure with metal material; use a graphical process to remove part of the third insulating layer on the top surface of the second light-emitting unit to expose the second N-type ohmic contact layer in the second light-emitting unit; cover the surface of the second N-type ohmic contact layer and the surface of the third insulating layer on the side away from the driving backplane with a cathode layer.

[0206] In step S223b, the trench process is performed before the common cathode connection. The resulting micro-display luminescent pixel is shown in FIG12 . Specifically, after the second light-emitting unit 32 is fabricated, a third insulating layer 63 is directly introduced. A dielectric layer is further grown, and a plasma deposition process, such as that on silicon glass, is used to form the third insulating layer 63. The structure after the introduction of the third insulating layer 63 is shown in FIG34 . The third insulating layer 63 is then planarized, and the third trench structure 43 is etched. The dielectric layer on the driver backplane 10 is then used to withstand the etching. After etching, metal filling is performed. For example, metals Al, NiV, and Cu are sequentially deposited in the third trench structure 43; or metal Al is deposited in the third trench structure 43; or metal W is deposited in the third trench structure 43. The structure after metal filling is shown in FIG35 . This structure can simultaneously achieve optical pixel string isolation and cathode electrical connection. The corresponding seed layer of the metal filling material can also be composed of a single layer or multiple layers of metals such as Ti, Ni, Cr, Au, Ge, Al, Pt, Ta, W, or their nitrides. Furthermore, after the filling is completed, CMP can be used to remove excess metal from the surface of the filled metal material and planarize the surface. Then, a patterned opening is performed to expose the second N-type ohmic contact layer 323 in the second light-emitting unit 32 for contact preparation, thereby connecting to the cathode layer 70.

[0207] In one possible implementation, in S223b, before step-filling the second light-emitting unit with an insulating material to form a third insulating layer, the following step is also included: a passivation layer is applied to the surface of the second light-emitting unit and the surface of the driver backplane. Specifically, the passivation layer 80 is used as an etching stop layer for the trenches. The structure after step-filling is shown in FIG36 , and the structure after trench etching and metal filling is shown in FIG37 . The micro-display light-emitting pixel produced by this step is shown in FIG13 .

[0208] It can be understood that if the above-mentioned back groove structure design idea is adopted, the advantage is that the pattern of the second light-emitting unit has not been defined during bonding, the precision requirement when combined with the driving backplane is very low, and the depth of the third groove structure can be flexibly customized by adjusting the thickness of the third insulating layer; the disadvantage is that the N-type ohmic contact corresponding to the second light-emitting unit needs to be prepared separately.

[0209] In summary, the preparation method of the micro-display luminous pixel provided in the embodiment of the present application achieves better optical crosstalk isolation by etching a groove structure in the display module of the micro-display luminous pixel and filling the groove structure with metal material. The through-type groove structure can be used to customize the light-emitting angle through the depth of the groove structure. In addition, the design process of the groove structure is relatively mature, and mass production and yield are guaranteed.

[0210] Furthermore, the preparation method adopts semiconductor technology, which is compatible with nanoscale operation and is more suitable for the preparation of micro-pixel sizes.

[0211] All of the above optional technical solutions can be combined in any way to form optional embodiments of the present invention, that is, any multiple embodiments can be combined to meet the needs of different application scenarios. They are all within the scope of protection of this application and will not be described in detail here.

[0212] It should be noted that the above is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A microdisplay light-emitting pixel for preventing crosstalk, characterized in that The size of the microdisplay light-emitting pixel is in the range of 0.5 um to 50 um, and the microdisplay light-emitting pixel includes: A driving backplane; A display module, which is disposed on the driving backplane. The display module includes a light-emitting unit and a trench structure. The light-emitting unit is electrically connected to the anode contact in the driving backplane. The trench structure surrounds the light-emitting unit and penetrates the vertical area where the display module is located. The trench structure is filled with a metal material, and the light-emitting unit is an inorganic compound semiconductor.

2. The microdisplay light-emitting pixel according to claim 1, wherein The display module at least includes: a first display device layer; the first display device layer includes: A first light-emitting unit, in which a first P-type ohmic contact layer of the first light-emitting unit is connected with a through hole. The first light-emitting unit is electrically connected to the anode contact in the driving backplane through the through hole filled with a metal material; A first insulating layer, which is filled and formed outside the first light-emitting unit; A first trench structure, which penetrates through the first insulating layer. One end of the first trench structure is connected to the first N-type ohmic contact layer in the first light-emitting unit, and the other end is connected to the upper surface of the driving backplane.

3. The microdisplay light-emitting pixel according to claim 2, wherein The surface size of the through hole is smaller than the surface size of the first P-type ohmic contact layer.

4. The microdisplay light-emitting pixel according to claim 3, wherein The surface size of the through hole is larger than the surface size of the anode contact in the driving backplane.

5. The microdisplay light-emitting pixel according to claim 2, characterized in that, The display module further includes: a second display device layer disposed on the first display device layer; the second display device layer includes: A second insulating layer, which is filled and formed on the side of the first display device layer away from the driving backplane; A second trench structure, which penetrates through the second insulating layer and the first N-type ohmic contact layer. One end of the second trench structure is connected to the first trench structure.

6. The microdisplay light-emitting pixel according to claim 5, wherein The width of the second trench structure is smaller than the width of the first trench structure.

7. The microdisplay light-emitting pixel according to claim 2, wherein The first N-type ohmic contact layer includes a first part and a second part stacked in a direction away from the driving backplane. The surface size of the second part is larger than the surface size of the first part, and one end of the first trench structure is connected to the second part.

8. The microdisplay light-emitting pixel according to claim 7, wherein A second trench structure is connected above the first trench structure, and the bottom of the second trench structure penetrates through the second part so that the second trench structure is connected to the first trench structure.

9. The microdisplay light-emitting pixel according to claim 1, wherein The display module at least includes: a third display device layer; the third display device layer includes: A second light-emitting unit, wherein there is a bonding layer between the second P-type ohmic contact layer in the second light-emitting unit and the driving backplane, the second light-emitting unit is electrically connected to the anode contact in the driving backplane through the bonding layer, and a part of the cathode layer is covered on the surface of the second N-type ohmic contact layer in the second light-emitting unit; A third insulating layer, which is filled and formed outside the second light-emitting unit; A third trench structure, which penetrates through the third insulating layer, and one end of the third trench structure is connected to the cathode layer.

10. The microdisplay light-emitting pixel according to claim 9, wherein, The cathode layer includes: a middle cathode layer and side cathode layers on both sides, and the middle cathode layer is covered on the surface of the second N-type ohmic contact layer; The side walls of the second light-emitting unit and the surface of the driving backplane are covered with a passivation layer, and the side cathode layers are covered on the surface of the passivation layer; Or, The side cathode layer is covered on the surface of the third insulating layer away from the driving backplane.

11. The microdisplay light-emitting pixel according to claim 10, wherein, When the side cathode layer is covered on the surface of the third insulating layer away from the driving backplane, the side walls of the second light-emitting unit and the surface of the driving backplane are also covered with a passivation layer.

12. The microdisplay light-emitting pixel according to claim 1, wherein, The trench structures corresponding to adjacent light-emitting units are interconnected; Or, The trench structures corresponding to adjacent light-emitting units are isolated from each other by an insulating medium.

13. The microdisplay light-emitting pixel according to claim 1, wherein The trench pattern corresponding to the trench structure after top view includes: One of a circle, a rectangle, a hexagon, and an octagon.

14. The microdisplay light-emitting pixel according to claim 1, wherein, The display module further includes: a microlens; The microlens is disposed above the light-emitting unit and the trench structure.

15. The microdisplay light-emitting pixel according to claim 1, wherein The metal material filled in the trench structure includes: Aluminum, nickel vanadium, and copper deposited vertically in sequence; Or, deposited aluminum; Or, deposited tungsten.

16. The microdisplay light-emitting pixel according to claim 1, wherein, The overall depth of the trench structure is not less than the overall depth of the light-emitting unit.

17. The microdisplay light-emitting pixel according to claim 1, wherein, The width of the trench structure is in the range of 90 nm to 5 μm.

18. The microdisplay light-emitting pixel according to claim 1, wherein, The depth of the trench structure is in the range of 0.4 μm to 5 μm.

19. The microdisplay light-emitting pixel according to claim 1, wherein, The angle of the trench structure gradually increases in the direction away from the driving backplane.

20. A method for preparing a microdisplay light-emitting pixel, characterized in that, The method is used to prepare the microdisplay light-emitting pixel according to any one of claims 1 to 19, and the method includes: Preparing a driving backplane; Preparing a display module combined on the driving backplane, the display module includes a light-emitting unit and a trench structure, the light-emitting unit is electrically connected to the anode contact in the driving backplane, the trench structure surrounds the light-emitting unit and penetrates the vertical area where the display module is located, the trench structure is filled with a metal material, and the light-emitting unit is an inorganic compound semiconductor.

21. The method according to claim 20, wherein The preparing the display module combined on the driving backplane includes: Perform step etching on an inorganic compound semiconductor to prepare a first light-emitting unit; Use an insulating material to perform step filling on the first light-emitting unit to form a first insulating layer; Etch the first insulating layer to form a through hole connected to a first P-type ohmic contact layer in the first light-emitting unit and a first trench structure surrounding the first light-emitting unit; Fill the through hole and the first trench structure with a metal material, and the first light-emitting unit, the first insulating layer, and the first trench structure are combined into a first display device layer; Through a hybrid bonding process, bond the first display device layer to the driving backplane. When bonding, the first light-emitting unit is electrically connected to an anode contact in the driving backplane through the through hole filled with the metal material.

22. The method according to claim 21, wherein After bonding the first display device layer to the driving backplane, the method further includes: Remove the compound substrate in the first light-emitting unit; Roughen the surface of the first light-emitting unit after removing the substrate.

23. The method according to claim 21, wherein After forming the first display device layer, the method further includes: Use an insulating material to fill the first display device layer to form a second insulating layer; Etch the second insulating layer to form a second trench structure with one end connected to the first trench structure; Fill the second trench structure with a metal material, and the second insulating layer and the second trench structure are combined into a second display device layer.

24. The method according to claim 20, wherein The preparation of the display module bonded on the driving backplane includes: Through a hybrid bonding process, bond the inorganic compound semiconductor with a bonding layer and the driving backplane with a bonding layer. When bonding, the inorganic compound semiconductor is electrically connected to an anode contact in the driving backplane through the bonding layer; Perform step etching on the inorganic compound semiconductor and the bonding layer to prepare a second light-emitting unit; Use an insulating material to perform step filling on the second light-emitting unit to form a third insulating layer; etch the third insulating layer to form a third trench structure surrounding the second light-emitting unit; fill the third trench structure with a metal material; use a patterning process to remove a part of the third insulating layer on the top surface of the second light-emitting unit to expose a second N-type ohmic contact layer in the second light-emitting unit; deposit a cathode layer on the surface of the second N-type ohmic contact layer and on the side surface of the third insulating layer away from the driving backplane; Or, Deposit a passivation layer on the surface of the second light-emitting unit and on the surface of the driving backplane; use a patterning process to remove a part of the passivation layer on the top surface of the second light-emitting unit to expose a second N-type ohmic contact layer in the second light-emitting unit; deposit a cathode layer on the surface of the second N-type ohmic contact layer and on the surface of the passivation layer; use an insulating material to perform step filling on the second light-emitting unit to form a third insulating layer; etch the third insulating layer to form a third trench structure surrounding the second light-emitting unit; fill the third trench structure with a metal material.

25. The method according to claim 24, wherein In the method of covering a cathode layer on the surface of the second N-type ohmic contact layer and on the surface of the third insulating layer away from the driving backplane, before using an insulating material to perform step filling on the second light-emitting unit to form the third insulating layer, the method further includes: Covering a passivation layer on the surface of the second light-emitting unit and on the surface of the driving backplane.

26. The method according to claim 20, wherein After preparing a display module bonded to the driving backplane, the method further includes: Preparing a microlens on the light-emitting unit and on the trench structure.

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