Display module, manufacturing method thereof and display device

Abstract

The invention relates to a display module, a manufacturing method thereof and a display device. The display module comprises a substrate; the light-emitting units are arranged on the substrate, and each light-emitting unit comprises an epitaxial structure and an ohmic contact layer arranged on the epitaxial structure; wherein the ohmic contact resistance of the ohmic contact layers of at least part of the light-emitting units is different from the ohmic contact resistance of the ohmic contact layers of the other light-emitting units, and the epitaxial structure is configured to have a wavelength shift of more than 60 nm under different currents, at least part of the light-emitting units have light-emitting wavelengths different from those of other light-emitting units under the same driving voltage; and the color conversion layer is arranged in the light emitting direction of part of the light emitting units and is configured to convert light emitted by the light emitting units into light with another wavelength, so that the display module presents colors with at least three wavelengths. The manufacturing efficiency is improved, and the stability influence caused by multiple times of processing when at least two color conversion layers are manufactured is also avoided.

Description

Technical Field

[0001] The present application relates to the field of display technologies, and particularly to a display module, a manufacturing method thereof, and a display device. Background Art

[0002] At present, in the field of near-eye displays such as VR (Virtual Reality) and AR (Augmented Reality), there is an urgent need for the pixel density and brightness of display modules. Generally, a display module with a pixel density exceeding 2000 PPI (Pixels Per Inch, a unit of pixel density - indicating the number of pixels per inch) and a brightness exceeding several hundred thousand nits is required. However, existing LCD (Liquid Crystal Display) and OLED (Organic Light-Emitting Diode) cannot meet this requirement simultaneously. Micro LED (Micro Light Emitting Diode) is expected to be widely used in this field. In some related technologies, a full-color display solution can be achieved by combining monochromatic light-emitting chips with quantum dots. However, quantum dots of different colors need to be fabricated separately, and the processing of multiple quantum dots results in some quantum dots experiencing multiple chemical solution contacts and thermal contacts, affecting their stability. Therefore, currently, full-color Micro-LEDs are limited by problems such as the accuracy and efficiency of mass transfer or the stability of quantum dots, and the manufacturing process is difficult and inefficient.

[0003] Therefore, how to efficiently and simply achieve full-color display is an urgent problem to be solved. Summary of the Invention

[0004] In view of the deficiencies of the above-mentioned related technologies, the purpose of the present application is to provide a display module, a manufacturing method thereof, and a display device, aiming to solve the problems of low production efficiency and poor stability of dual-color display products.

[0005] A display module includes:

[0006] A substrate;

[0007] A plurality of light-emitting units disposed on the substrate, the light-emitting units including an epitaxial structure and an ohmic contact layer disposed on the epitaxial structure; wherein, the ohmic contact resistance of the ohmic contact layer of at least some of the light-emitting units is different from that of the ohmic contact layer of other light-emitting units, and the epitaxial structure is configured to have a wavelength shift of more than 60 nm under different currents, so that the at least some of the light-emitting units have a different emission wavelength from other light-emitting units under the same driving voltage;

[0008] A color conversion layer is disposed in the light-emitting direction of some light-emitting units, and the color conversion layer is configured to convert the light emitted by the light-emitting units into light of another wavelength, so that the display module presents colors of at least three wavelengths.

[0009] The epitaxial structure of the light-emitting units used in the above display module is configured to have a wavelength shift of more than 60 nm under different currents, which enables each light-emitting unit to adopt the same epitaxial part. These epitaxial structures or each light-emitting unit can be fabricated and transferred together, reducing the number of transfers. This makes it easier to integrate light-emitting units of two emission colors on a single substrate, improving the manufacturing efficiency, and the yield is easier to control. Moreover, the above display module can achieve three-color full-color display with only one color conversion, reducing the number of settings of the color conversion layer, simplifying the fabrication of the color conversion layer, and avoiding the stability impact caused by multiple processing when fabricating at least two color conversion layers.

[0010] Optionally, the light-emitting unit further includes a metal electrode disposed on the opposite side of the light-emitting direction. The metal electrode connects the epitaxial structure to the substrate and protrudes away from the substrate around the epitaxial structure to form a light barrier for blocking the lateral light of the light-emitting unit.

[0011] The light barrier can block the lateral light of the light-emitting unit to a certain extent, thereby weakening the light crosstalk between the light-emitting units.

[0012] Based on the same inventive concept, the present application also provides a method for manufacturing a display module, including:

[0013] Providing a substrate;

[0014] Setting a plurality of light-emitting units on the substrate, the light-emitting units including an epitaxial structure and an ohmic contact layer disposed on the epitaxial structure; wherein, the ohmic contact resistance of the ohmic contact layer of at least some light-emitting units is different from that of the ohmic contact layer of other light-emitting units, and the epitaxial structure is configured to have a wavelength shift of more than 60 nm under different currents, so that the at least some light-emitting units have a different emission wavelength from other light-emitting units under the same driving voltage;

[0015] Setting a color conversion layer in the light-emitting direction of some light-emitting units, the color conversion layer is configured to convert the light emitted by the light-emitting units into light of another wavelength, so that the display module presents colors of at least three wavelengths.

[0016] The manufacturing method of the above display module can more easily integrate light-emitting units of two light-emitting colors on a single substrate, greatly improving the manufacturing efficiency. Moreover, three-color full-color display can be achieved with only one color conversion, reducing the number of settings of the color conversion layer, simplifying the manufacturing of the color conversion layer, and avoiding the stability impact caused by multiple processing when manufacturing at least two color conversion layers.

[0017] Based on the same inventive concept, the present application also provides a display device, including a frame and the display module as described above provided on the frame.

[0018] The above display device can more easily integrate light-emitting units of two light-emitting colors on a single substrate, greatly improving the manufacturing efficiency; and three-color full-color display can be achieved with only one color conversion, reducing the number of settings of the color conversion layer, simplifying the manufacturing of the color conversion layer, and avoiding the stability impact caused by multiple processing when manufacturing at least two color conversion layers; in addition, only a unified driving voltage needs to be provided, without increasing additional control costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is a schematic diagram of the basic structure of the epitaxial structure provided by an embodiment of the present application;

[0020] Figure 2 It is a schematic diagram of the array of light-emitting units provided by an embodiment of the present application;

[0021] Figure 3 It is a schematic diagram of the structure of the light-emitting unit provided by an embodiment of the present application;

[0022] Figure 4 It is another schematic diagram of the structure of the light-emitting unit provided by an embodiment of the present application;

[0023] Figure 5 It is a schematic flowchart of the manufacturing method of the display module provided by an embodiment of the present application;

[0024] Figure 6 It is a detailed flowchart of the manufacturing method of the display module provided by an embodiment of the present application Figure 1 ;

[0025] Figure 7 It is a schematic diagram of the manufacturing process of a display module provided by an embodiment of the present application;

[0026] Figure 8 It is a detailed flowchart of the manufacturing method of the display module provided by an embodiment of the present application Figure 2 ;

[0027] Figure 9 It is a schematic diagram of forming a mask pattern with an insulating material provided by an embodiment of the present application;

[0028] Figure 10 Schematic diagram of etching a metal layer through a mask pattern provided by an embodiment of the present application;

[0029] Figure 11 Schematic diagram of the manufacturing process of a display module provided by another alternative embodiment of the present application Figure 1 ;

[0030] Figure 12 Schematic diagram of an exemplary epitaxial structure provided by another alternative embodiment of the present application;

[0031] Figure 13 Schematic diagram of the manufacturing process of a display module provided by another alternative embodiment of the present application Figure 2 ;

[0032] Figure 14 Schematic diagram of the manufacturing process of a display module provided by another alternative embodiment of the present application Figure 3 ;

[0033] Figure 15 Schematic diagram of the manufacturing process of a display module provided by another alternative embodiment of the present application Figure 4 ;

[0034] Description of reference numerals:

[0035] 101 - First-type semiconductor layer; 102 - Active layer; 103 - Second-type semiconductor layer; 104 - Ohmic contact layer; 1041 - First ohmic contact layer; 1042 - Second ohmic contact layer; 105 - Contact barrier layer; 106 - Current spreading layer; 107 - First bonding metal layer; 108 - Etching mask; 109 - Insulating protective layer; 1001 - u-GaN layer; 1002 - N-GaN layer; 1003 - Electron deceleration layer; 1004 - Low-doped gallium nitride layer; 1005 - Stress release layer; 1006 - Hole accumulation layer; 1007 - p-GaN layer; 201 - First light-emitting unit; 202 - Second light-emitting unit; 203 - First epitaxial structure; 204 - Second epitaxial structure; 301 - Substrate; 302 - Contact; 303 - Bonding layer; 304 - Insulating material; 305 - Common electrode; 306 - Barrier wall; 307 - Growth substrate; 308 - Sacrificial layer; 309 - Second bonding metal layer; 310 - Light-blocking layer; 311 - Color conversion layer; 312 - First color purification layer; 313 - Second color purification layer; 314 - Reflective layer; 315 - Light type adjustment structure. Detailed implementation manners

[0036] To facilitate the understanding of the present application, the present application will be described more comprehensively below with reference to the relevant drawings. Preferred embodiments of the present application are shown in the drawings. However, the present application can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, these embodiments are provided to make the disclosure of the present application more thorough and comprehensive.

[0037] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the technical field to which this application belongs. The terms used in the description of this application herein are for the purpose of describing specific embodiments only and are not intended to limit this application.

[0038] In the related art, the preparation of dual-color display products is difficult; based on this, the present application hopes to provide a solution that can solve the above technical problems, and its detailed content will be elaborated in the subsequent embodiments.

[0039] Embodiment:

[0040] This embodiment provides a display module, which includes but is not limited to a substrate 301, a plurality of light-emitting units disposed on the substrate 301, and a color conversion layer 311. Among them, at least some of the light-emitting units can have a different emission wavelength from other light-emitting units under the same driving voltage. For the convenience of description, these light-emitting units will also be referred to as the first light-emitting units 201 and the second light-emitting units 202 in this application. The first light-emitting units 201 have the same emission wavelength, and the second light-emitting units 202 have the same emission wavelength, but the emission wavelengths of the first light-emitting units 201 and the second light-emitting units 202 are different.

[0041] The light-emitting unit includes an epitaxial structure and an ohmic contact layer 104 disposed on the epitaxial structure. It should be noted that the light-emitting unit in this embodiment is a light-emitting device, which includes an epitaxial structure and associated electrode structures, etc., and the epitaxial structure refers to the semiconductor material part thereof. The light-emitting unit can be a Micro LED chip or other light-emitting chips. In this embodiment, the epitaxial structure is configured to have a wavelength shift of more than 60 nm under different currents, that is, under different currents, the emission wavelength of the epitaxial structure is different, and the maximum wavelength difference exceeds 60 nm. This enables the emission color of the epitaxial structure to be different under different currents, so that the emission effects of different colors can be satisfied by using at least one epitaxial structure. Therefore, in this embodiment, the epitaxial structures on the display module can be the same, which enables these epitaxial structures or each light-emitting unit to be fabricated and transferred together, reducing the number of transfers, making it easier to integrate the light-emitting units of two emission colors on a single substrate 301, greatly improving the production efficiency, and making the yield easier to control.

[0042] Exemplarily, the emission wavelength range of the epitaxial structure can cover both blue light and green light simultaneously, so as to achieve blue light and green light respectively under different currents; in some other examples, the emission wavelength range of the epitaxial structure can cover green light and red light simultaneously, so as to achieve green light and red light respectively under different currents; moreover, in some examples, the wavelength shift range of the epitaxial structure under different currents is configured to be wider, so as to cover blue light, green light and red light simultaneously.

[0043] See Figure 1 , the epitaxial structure may include, but is not limited to, a first-type semiconductor layer 101, an active layer 102 and a second-type semiconductor layer 103 which are stacked in sequence, wherein the first-type semiconductor layer 101 may be an N-type doped semiconductor layer or a p-type doped semiconductor layer, and the second-type semiconductor layer 103 is the other type opposite to the first-type semiconductor layer 101.

[0044] In practical applications, the light-emitting unit can be formed into a front-mounted or flip-chip structure, or can also be formed into a vertical structure. Except for the part related to the ohmic contact layer 104, the structures of the light-emitting units can be the same or different. For example, the epitaxial structures of the light-emitting units are not only the same in composition, but also can be the same in terms of structural form and the like.

[0045] In this embodiment, the ohmic contact resistance of the ohmic contact layer 104 of at least some of the light-emitting units is different from that of the ohmic contact layer 104 of other light-emitting units. The different ohmic contact resistances cause different currents to be formed in the light-emitting units under the same driving voltage. When performing display control, only a unified driving voltage needs to be provided, so that different currents are applied to some of the light-emitting units and other light-emitting units in the display module. Due to the wavelength shift of the epitaxial structure under different currents, some of the light-emitting units have different emission wavelengths from other light-emitting units. It can be seen that in some implementation processes, the display module of this embodiment does not need to perform additional design on the display control means, has high stability and applicability during the control process, and does not increase the control cost.

[0046] The ohmic contact layer 104 may include a transparent conductive material such as indium tin oxide (abbreviated as ITO) that can form an ohmic contact with the corresponding semiconductor material, and also for example: graphene, indium zinc oxide (abbreviated as IZO), a thin metal film layer, etc. In practical applications, the ohmic contact layers 104 of the light-emitting units can be made of the same material or different materials.

[0047] The color conversion layer 311 of this embodiment may be a color conversion layer 311 made of quantum dot materials or other materials. The color conversion layer 311 is disposed in the light-emitting direction of some light-emitting units, and is configured to convert the light emitted by the light-emitting unit into light of another wavelength, so that the display module presents colors of at least three wavelengths. The color conversion layer 311 enables the display module of this embodiment to present at least three different colors, thereby realizing full-color display in some implementation processes. Exemplarily, the color of the light-emitting wavelength of some light-emitting units can be configured to be blue, and the light-emitting wavelength of the remaining light-emitting units can be configured to be green. The color conversion layer 311 can be configured to convert blue or green into red, thereby forming an RGB full color. Based on the light-emitting units that can respectively display two colors, the display module of this embodiment only needs to set one color conversion layer 311 to achieve three-color display, reducing the number of times of setting the color conversion layer 311, simplifying the manufacture of the color conversion layer 311, and avoiding the influence on stability caused by multiple processing when manufacturing at least two color conversion layers 311.

[0048] In some embodiments, the light-emitting unit includes metal electrodes disposed on opposite sides of the light-emitting direction. The metal electrodes connect the epitaxial structure and the substrate 301. The metal electrodes can correspond to the light-emitting units one by one. The metal electrodes protrude away from the substrate 301 around the epitaxial structure to form a barrier wall 306 to block the lateral light emission of the corresponding light-emitting units. The barrier wall 306 formed by the metal electrodes blocks the lateral light of the light-emitting units to a certain extent, thereby reducing the light crosstalk between the light-emitting units. In some examples, the height of the barrier wall 306 is higher than or equal to the thickness of the epitaxial structure to achieve a better crosstalk suppression effect. The substrate 301 of this embodiment may be a CMOS (Complementary Metal Oxide Semiconductor) driving backplane, and the TFT (Thin Film Transistor) driving backplane may also be an LTpS (Low Temperature poly-Silicon). The substrate 301 may include a circuit layer for driving and controlling the light-emitting units. In actual applications, the light-emitting unit may be formed into a front-mounted or flip-chip structure, or may also be formed into a vertical structure.

[0049] In some embodiments, the light-emitting unit has a vertical structure, and the epitaxial structure is bonded to the substrate 301 and connected to the circuit layer of the substrate 301. An electrode may be correspondingly formed on one side of the epitaxial structure close to the substrate 301, such as the metal electrode having the barrier wall 306 in the foregoing example. The electrode of the epitaxial structure may be connected to the circuit layer of the substrate 301 through the contact 302, and the contact 302 is equivalent to the electrode of the circuit layer. In the display module, a common electrode 305 is further included on one side of the epitaxial structure away from the substrate 301, and the common electrode 305 is connected to a plurality of ohmic contact layers 104. In some embodiments, an insulating protection layer 109 is filled between the light-emitting units, and the common electrode 305 may be connected to the circuit layer of the substrate 301 through a through hole in the insulating protection layer 109 or from the edge of the insulating protection layer 109.

[0050] In this embodiment, several light-emitting units include light-emitting units having two emission wavelengths and a quantity ratio of 2:1. The color conversion layer 311 is disposed in the light-emitting direction of the light-emitting units with a larger quantity among them, so that the display module presents colors of three wavelengths arranged in pixels. Refer to Figure 2 As shown, the first light-emitting units 201 and the second light-emitting units 202 having different emission wavelengths may be laid on the substrate 301 in an array manner. The first light-emitting units 201 and the second light-emitting units 202 are alternately arranged in columns. Among them, one column of the second light-emitting units 202 is arranged every two columns of the first light-emitting units 201. Correspondingly, among every two adjacent columns of the first light-emitting units 201, a color conversion layer 311 is correspondingly provided on one column. In this example, the three adjacent light-emitting units in each row can emit light of different wavelengths in sequence and can be used as a pixel for display. In other examples, the arrangement rules of the first light-emitting units 201 and the second light-emitting units 202, and the setting rules of the color conversion layer 311 may also be other forms. In fact, the light-emitting units may also be arranged in other ways to achieve the purpose of display, and this application will not elaborate on this. In addition, for ease of understanding, this embodiment takes two light-emitting units having different wavelengths as an example. However, in actual applications, the types of light-emitting units in the display module may be more than two, that is, the display module may also have light-emitting units having more than two different emission wavelengths. The projected shape of the light-emitting unit is exemplified as a rectangle. In actual applications, it may also be a triangle, a circle or other polygonal shapes, etc. This application does not limit this, and the specific number of arrays and the setting pitch can also be set according to actual needs.

[0051] In some embodiments, the ohmic contact resistance of the ohmic contact layer 104 of some light-emitting units is less than that of the ohmic contact layer 104 of other light-emitting units, so that some light-emitting units have a larger current under the same driving voltage. Exemplarily, when the epitaxial structure operates at a larger current, it emits blue light, and when it operates at a smaller current, it emits green light. By converting the blue or green light emitted by the epitaxial structure into red light through the color conversion layer 311, full-color display can be achieved. Exemplarily, the color conversion layer 311 can be disposed on the light-emitting units with a larger current. For example, in the above example, the light-emitting units that emit blue light have a larger current and thus usually have a higher luminous intensity; at the same conversion efficiency, light of another wavelength with a higher intensity can be obtained, which is beneficial to improving the display effect in some implementation processes.

[0052] In order to form different ohmic contact resistances for the ohmic contact layer 104 of some light-emitting units, the ohmic contact layer 104 of several light-emitting units satisfies at least one of the following conditions:

[0053] The ohmic contact area of the ohmic contact layer 104 of at least some light-emitting units is different from that of the ohmic contact layer 104 of other light-emitting units;

[0054] The material of the ohmic contact layer 104 of at least some light-emitting units is different from that of the ohmic contact layer 104 of other light-emitting units;

[0055] The diffusion depth of the ohmic contact layer 104 of at least some light-emitting units into the epitaxial structure is different from that of the ohmic contact layer 104 of other light-emitting units into the epitaxial structure.

[0056] Exemplarily, a contact barrier layer 105 can be disposed between the ohmic contact layer 104 and the epitaxial structure. The contact barrier layer 105 prevents the direct contact between the ohmic contact layer 104 and the epitaxial structure. By controlling the size of the contact barrier layer 105, the control of the ohmic contact area can be achieved. Refer to Figure 3 As shown, between the epitaxial structure and the ohmic contact layer 104, there is a contact barrier layer 105. The size of the contact barrier layer 105 is smaller than the area of the side of the epitaxial structure close to the ohmic contact layer 104, and the direct contact between the epitaxial structure and the ohmic contact layer 104 is blocked in some areas. Due to the existence of the contact barrier layer 105, an additional insertion structure exists between the epitaxial structure and the ohmic contact layer 104, and the ohmic contact layer 104 cannot be in direct contact with the epitaxial structure completely, and its ohmic contact area is reduced compared with the state without the contact barrier layer 105.

[0057] Of course, different contact barrier layers 105 can also have different degrees of influence. In practical applications, the contact barrier layer 105 between the epitaxial structure and the ohmic contact layer 104 can be configured according to the current conditions required for the work. In this embodiment, a contact barrier layer 105 can be provided between the ohmic contact layer 104 and the epitaxial structure of all the light-emitting units, but the coverage area of the contact barrier layer 105 in some light-emitting units is different from that of the contact barrier layer 105 in other light-emitting units, so the influence degree on the ohmic contact area is different. In practical applications, for higher luminous efficiency, it is also possible to choose not to provide a contact barrier layer 105 in some light-emitting units. It can be understood that the ohmic contact area of the ohmic contact layer 104 in the remaining light-emitting units provided with the contact barrier layer 105 will be relatively small.

[0058] The contact barrier layer 105 can be made of an insulating material. In some examples, the material used can be retained during the processing of the mask or the protective layer and directly used as the contact barrier layer 105 to simplify the process and save materials.

[0059] Exemplarily, as Figure 3 shown, the contact barrier layer 105 can be provided in the middle of the side of the epitaxial structure close to the ohmic contact layer 104. The ohmic contact layer 104 is in direct contact with the epitaxial structure around the contact barrier layer 105, which makes the current distribution relatively uniform and has a good display light effect. Of course, the contact barrier layer 105 can also be provided in other forms. For example, Figure 4 in the example of

[0060] In some embodiments, the light-emitting unit further includes at least one of the following structures:

[0061] A color purification layer, provided in the light-emitting direction of the light-emitting unit, configured to selectively block light, and the wavelength range that can pass through it is related to the emission wavelength of the corresponding light-emitting unit; the color purification layer can be a DBR (distributed Bragg reflector), a filter film, etc. Its function is to realize the band-pass filtering of the light wavelength. By setting it in the light-emitting direction of the light-emitting unit, the irrelevant stray light emitted can be reduced, thereby improving the color purity of the light output.

[0062] A light pattern adjustment structure 315, provided in the light-emitting direction of the light-emitting unit, configured to adjust the light-emitting pattern of the light-emitting unit; it includes but is not limited to multiple microstructures prepared by means such as nanoimprinting, microlens array transfer, or hot-melt photoresist etching of oxides.

[0063] The current spreading layer 106 is disposed on the epitaxial structure and on the opposite side of the ohmic contact layer 104. Exemplarily, the current can be a metal or a transparent conductive material, such as indium tin oxide. Disposing the ohmic contact layer 104 and the current spreading layer 106 on the epitaxial structure can make the current distribution in the epitaxial structure relatively uniform and improve the light emitting efficiency.

[0064] During the fabrication process of the ohmic contact layer 104, annealing treatment is usually included. In another example, ohmic contact layers 104 with different ohmic contact resistances are fabricated separately, and certain annealing conditions of the ohmic contact layer 104 are different, which can cause differences in the diffusion depth of the ohmic contact layer 104 into the corresponding epitaxial structure. Exemplarily, the annealing conditions include but are not limited to the temperature during the annealing process, the temperature change rate, the holding time at each temperature, the composition of the gas introduced, etc. In this example, at least one annealing condition can be changed, and the change in this annealing condition will result in different performances of some ohmic contact layers 104 compared to other ohmic contact layers 104, such that their specific contact resistivities are different and thus have different ohmic contact resistances. It should be noted that the other ohmic contact layers 104 referred to in this application are the ohmic contact layers 104 on other light emitting units. In some implementation processes, the influence brought by the annealing conditions can be multi-faceted. On the basis of making the ohmic contact resistance of some ohmic contact layers 104 different from that of other ohmic contact layers 104, the specific annealing conditions can be set according to requirements, and this embodiment does not limit.

[0065] This embodiment also provides a method for manufacturing a display module. Refer to Figure 5 , the method for manufacturing a display module includes but is not limited to the steps:

[0066] S101. Provide a substrate;

[0067] S102. Dispose a plurality of light emitting units on the substrate. The light emitting units include an epitaxial structure and an ohmic contact layer disposed on the epitaxial structure. The ohmic contact resistance of the ohmic contact layer of at least some of the light emitting units is different from that of the ohmic contact layer of other light emitting units, and the epitaxial structure is configured to have a wavelength shift of more than 60 nm under different currents, so that at least some of the light emitting units have a different emission wavelength from other light emitting units under the same driving voltage;

[0068] S103. Dispose a color conversion layer in the light emitting direction of some of the light emitting units;

[0069] The color conversion layer 311 is configured to convert the light emitted by the light emitting unit into light of another wavelength, so that the display module presents colors of at least three wavelengths.

[0070] It can be understood that the display module fabricated by the method for fabricating a display module according to this embodiment may include the display module of the foregoing example. To achieve displays of different colors, during the process of fabricating the light-emitting units, it is necessary to make the ohmic contact layer 104 of some light-emitting units have an ohmic contact resistance different from that of the ohmic contact layer 104 of other light-emitting units. Exemplarily, at least some of the ohmic contact layers 104 of the light-emitting units and other ohmic contact layers 104 may adopt different materials, have different ohmic contact areas configured, or may be fabricated under different processing conditions to have different ohmic contact resistances.

[0071] Exemplarily, the light-emitting units may be fabricated on the substrate 301, or may be fabricated elsewhere and then transferred to the substrate 301. During the process of fabricating the light-emitting units, there is usually a process of setting the insulating material 304. In some implementation processes, the insulating material 304 covers the epitaxial structure. The set insulating material 304 may be used to form a mask or remain as a protective layer of the light-emitting units in some regions of the light-emitting units. Exemplarily, the insulating material 304 includes, but is not limited to, aluminum oxide, silicon dioxide, etc.

[0072] In some implementation manners, as Figure 6 shown, the steps of setting a plurality of light-emitting units on the substrate 301 include:

[0073] S201. Set the epitaxial structure on the substrate;

[0074] In this step S201, the epitaxial structure may be fabricated on the substrate 301. For example, a whole epitaxial layer is grown on the growth substrate 307. Since the light-emitting units in the display module of this embodiment can adopt a unified epitaxial structure, the epitaxial layer can be integrally transferred to the substrate 301, and a plurality of epitaxial structures are fabricated from the epitaxial layer by means such as etching. The structural forms of the respective epitaxial structures may be fabricated to be the same, simplifying the fabrication process. The manner of forming the epitaxial layer into the required epitaxial structural form may refer to existing manners and will not be elaborated here.

[0075] The respective epitaxial structures may also be set on the substrate 301 by means of transfer after fabrication. Exemplarily, a plurality of epitaxial structures are fabricated from the epitaxial layer on a single growth substrate 307, and then the respective epitaxial structures are transferred to the substrate 301 by means such as mass transfer.

[0076] S202. Set an insulating material on the epitaxial structure, and the insulating material covers the surface of the epitaxial structure;

[0077] S203. Remove the insulating material on the side of some of the epitaxial structures away from the substrate to expose that part of the epitaxial structure;

[0078] Exemplarily, the insulating material 304 on one side of a part of the epitaxial structure away from the substrate 301 is removed, so as to expose the surface of these epitaxial structures on the side away from the substrate 301. These epitaxial structures can be completely exposed, that is, the insulating material 304 in the corresponding area is completely removed. In some embodiments, the insulating material 304 in the corresponding area may not be completely removed, so that the epitaxial structure is partially exposed; wherein, a part of the insulating material 304 is retained, and the retained insulating material 304 can be used as a contact barrier layer 105 to control the contact area between the epitaxial structure and the ohmic contact layer 104.

[0079] S204. Provide an ohmic contact layer on a part of the epitaxial structure;

[0080] The part of the epitaxial structure is the epitaxial structure exposed in step S203.

[0081] S205. Remove the insulating material on the side of the remaining epitaxial structure away from the substrate to expose the remaining epitaxial structure;

[0082] Continuing with the above example, in step S203, a part of the epitaxial structure is processed, and in this step S205, the insulating material 304 on the remaining epitaxial structure is removed. In fact, these epitaxial structures processed in step S205 can also be completely exposed, that is, the insulating material 304 in the corresponding area is completely removed. In some embodiments, these epitaxial structures may also be partially exposed, that is, the insulating material 304 in the corresponding area is not completely removed, and a part of the insulating material 304 is retained. The retained insulating material 304 can be used as a contact barrier layer 105 to control the contact area between the epitaxial structure and the ohmic contact layer 104. The removal degree of the insulating material 304 on the epitaxial structure in steps S203 and S205 can be the same, and different ohmic contact resistances can be achieved by controlling the specific contact resistivity of the ohmic contact layer 104. If the removal degree of the insulating material 304 on the epitaxial structure in steps S203 and S205 is different, the ohmic contact layer 104 can be configured to have different ohmic contact areas, so as to have different ohmic contact resistances in some implementation processes.

[0083] S206. Provide an ohmic contact layer on the remaining epitaxial structure, which has a different ohmic contact resistance from the ohmic contact layer on the part of the epitaxial structure;

[0084] The method for making the ohmic contact resistances of the ohmic contact layers 104 set in steps S204 and S206 different is as described above, but not limited thereto. For example, the removal degree of the insulating material 304 on some epitaxial structures is different from that on other epitaxial structures. Under the same preparation and annealing conditions of the ohmic contact layer 104, the ohmic contact layers 104 set on these epitaxial structures have different ohmic contact areas. Further, under the same driving voltage, the current of a part of the light-emitting units will be greater than that of the rest of the light-emitting units, thus having different emission wavelengths.

[0085] As an example, referring to Figure 7 S301 of, the light-emitting unit can be designed as a vertical structure, that is, electrically connected on opposite sides. For the sake of illustration, Figure 8 only two light-emitting units are exemplified in. Contacts 302 for separately connecting with the epitaxial structures can be provided on the substrate 301, and the epitaxial structures are bonded to the substrate 301 through a bonding layer 303. The bonding layer 303 can be formed by combining the bonding metal provided on the epitaxial structure and the bonding metal provided on the substrate 301. The bonding metal can be an alloy formed by one or more of conductive metal materials such as Ti / Al / Ti / Au / Cr / pt / In / Sn / Ag, etc. For the sake of understanding, in this example, it is assumed that there are two different ohmic contact resistances in the ohmic contact layer 104 of the light-emitting units in the display module. In this application, the two ohmic contact layers 104 with different ohmic contact areas are also respectively referred to as the first ohmic contact layer 1041 and the second ohmic contact layer 1042. To distinguish the epitaxial structures and light-emitting units corresponding to these ohmic contact layers 104, the corresponding epitaxial structures can be respectively referred to as the first epitaxial structure 203 and the second epitaxial structure 204, and the corresponding light-emitting units are the first light-emitting unit 201 and the second light-emitting unit 202.

[0086] Referring to Figure 7 S302 of, in order to form the insulating protection layer 109, an insulating material 304 is provided on the epitaxial structure, and the insulating material 304 can completely cover the epitaxial structure and the side surface of the bonding layer 303. The insulating material 304 can be set to be relatively thick. For example, its thickness can exceed the thickness of the epitaxial structure. In some examples, the insulating material 304 can also be set to be relatively thin, and this example is not limited. Exemplarily, the insulating material 304 includes but is not limited to aluminum oxide, silicon dioxide, etc., and can be set through processes including but not limited to ALD (Atomic Layer Deposition), PECVD (plasma enhanced chemical vapor deposition), etc.

[0087] Referring to Figure 7In S303, the insulating material 304 on the first epitaxial structure 203 and the second epitaxial structure 204 is removed to varying degrees. The removal process can be a single process; it can also be divided into two processes, that is, the insulating material 304 on one of the first epitaxial structure 203 and the second epitaxial structure 204 is removed each time. Among them, the insulating material 304 on the side of the first epitaxial structure 203 away from the substrate 301 is completely removed, and the surface of the first epitaxial structure 203 on the side away from the substrate 301 is completely exposed; only part of the insulating material 304 on the side of the second epitaxial structure 204 away from the substrate 301 is removed, and the remaining insulating material 304 on the surface of the second epitaxial structure 204 on the side away from the substrate 301 serves as the contact barrier layer 105, and part of the area of the second epitaxial structure 204 on the side away from the substrate 301 is exposed. In this example, the surrounding insulating material 304 that is not removed remains on the surfaces of the first epitaxial structure 203 and the second epitaxial structure 204 as the insulating protection layer 109, and the side surface of the bonding layer 303 can also be covered and protected by the insulating protection layer 109.

[0088] See Figure 7 In S304, the first ohmic contact layer 1041 and the second ohmic contact layer 1042 are respectively provided on the surfaces of the first epitaxial structure 203 and the second epitaxial structure 204 on the side away from the substrate 301 under the same conditions. In this example, the insulating material 304 can be set to be relatively thick. After the insulating material 304 is removed, grooves are formed on the first epitaxial structure 203 and the second epitaxial structure 204. Among them, a part of the insulating material 304 remains at the bottom of the groove corresponding to the second epitaxial structure 204 as the contact barrier layer 105. To facilitate the fabrication of the second ohmic contact layer 1042, the thickness of the insulating material 304 remaining on the second epitaxial structure 204 is reduced. In this example, the first ohmic contact layer 1041 and the second ohmic contact layer 1042 can be disposed in the grooves, so that the insulating material 304 can also form insulating protection on the side surfaces of the first ohmic contact layer 1041 and the second ohmic contact layer 1042.

[0089] See Figure 7 In S305, a common electrode 305 is provided on one side of the first ohmic contact layer 1041 and the second ohmic contact layer 1042, and the lines connected to the contacts 302 on the substrate 301 can be controlled separately, so as to control the operation of each light-emitting unit separately. The common electrode 305 can be shared by a plurality of first light-emitting units 201 and second light-emitting units 202, and can be connected to the lines on the substrate 301 through the contacts 302.

[0090] For the display module fabricated above, a color conversion layer 311 is provided in the light-emitting direction of one of the first light-emitting units 201, and full-color display of three colors can be achieved. It can be understood that in some embodiments, the contact barrier layer 105 may not be provided, and the manufacturing process is the same as that described above Figure 8The examples are similar, but the insulating material 304 that serves as the contact barrier layer 105 is not retained. For these embodiments, during the formation of the ohmic contact layer 104, the difference in ohmic contact resistance is achieved by other means.

[0091] In some embodiments, the substrate 301 includes a circuit layer and a bonding layer disposed on the circuit layer. The bonding layer is connected to the circuit layer. The method for manufacturing the display module further includes: dividing the bonding layer into metal electrodes corresponding to respective light-emitting units by etching, and during the etching of the bonding layer, causing the bonding layer to re-deposit in the etched area to form a barrier wall protruding away from the substrate 301.

[0092] Exemplarily, refer to Figure 8 , in some embodiments, disposing a plurality of light-emitting units on the substrate 301 includes:

[0093] S401. Disposing an epitaxial structure on the substrate, and the epitaxial structure is bonded to the substrate through a bonding layer;

[0094] As an example, refer to Figure 9 , the substrate 301 includes a circuit layer and a bonding layer 303 disposed on the circuit layer. The bonding layer 303 is connected to the contact 302 of the circuit layer. Among them, the bonding layer 303 can be a whole layer of metal or a pattern of integral interconnection. A plurality of epitaxial structures are disposed on the bonding layer 303, and at this time, independent light-emitting units have not been formed yet.

[0095] S402. Dividing the bonding layer into metal electrodes corresponding to respective light-emitting units by etching, and during the etching of the bonding layer, causing the bonding layer to re-deposit in the etched area to form a barrier wall protruding away from the substrate;

[0096] When dividing the bonding layer 303 into metal electrodes corresponding to respective light-emitting units, an insulating material 304 can be provided as a mask. As an example, after the insulating material 304 is provided, all exposed surfaces on this side of the main body of the substrate 301 are covered by the insulating material 304. Refer to Figure 10, the provided insulating material 304 serves as a mask for etching the bonding layer 303 after being patterned. The insulating material 304 after being patterned to form a mask pattern covers the surfaces of the first epitaxial structure 203 and the second epitaxial structure 204, but is removed in the regions corresponding to between each light-emitting unit. The bonding layer 303 is etched through the mask pattern, such that the bonding layer 303 between the light-emitting units is etched, thereby disconnecting the interconnection of the bonding layer 303 between the light-emitting units, and the bonding layer 303 forms metal electrodes corresponding to each light-emitting unit. In this embodiment, the process parameters of the etching are controlled such that a redeposition phenomenon occurs during the etching process, which can cause the metal of the bonding layer 303 to accumulate in the edge region of the etching, thereby forming a barrier wall 306 protruding in a direction away from the substrate 301. The barrier wall 306 can, to a certain extent, block the lateral light of the light-emitting units, thereby reducing the light crosstalk between the light-emitting units. In some examples, the height of the barrier wall 306 can be controlled to be higher than or equal to the thickness of the epitaxial structure to achieve a better crosstalk suppression effect.

[0097] In addition, this embodiment also provides a display device, which includes a frame body and a display module disposed on the frame body. The display module adopted by the display device includes the display module in the above example. Since the epitaxial structure of the light-emitting unit is configured to have a wavelength shift of more than 60 nm under different currents, by making the ohmic contact resistance of the ohmic contact layer 104 of at least some light-emitting units different from the ohmic contact resistance of the ohmic contact layer 104 of other light-emitting units, the light-emitting units in the display module have different currents at the same driving voltage and thus emit different colors of light, and it is easier to integrate light-emitting units of two emission colors on a single substrate 301, greatly improving the manufacturing efficiency; on this basis, only one color conversion layer 311 needs to be provided to achieve a three-color display, reducing the number of times of setting the color conversion layer 311, simplifying the manufacturing of the color conversion layer 311, and avoiding the influence on stability caused by multiple processing when manufacturing at least two color conversion layers 311. In addition, the display device of this embodiment only needs to provide a unified driving voltage without increasing additional control costs.

[0098] Another alternative embodiment

[0099] For a better understanding of the present application, this embodiment further describes the display module and its manufacturing method of the present application in combination with a specific display module manufacturing process. For ease of understanding, in this embodiment, the light-emitting units with different emission wavelengths, their epitaxial structures, and the ohmic contact layer 104 are distinguished in terms of expression.

[0100] Such as Figure 11In S501, a sacrificial layer 308 is prepared on a growth substrate 307. In this example, the prepared display module is a blue-green dual-color display module, and the main epitaxial material includes gallium nitride. The growth substrate 307 can be a sapphire substrate. In other examples, the growth substrate 307 can be other materials capable of growing semiconductor materials, which can be selected according to the grown epitaxial material. The sacrificial layer 308 is made with holes, and then an epitaxial material is grown on the growth substrate 307. The epitaxial material grows in the holes formed by the sacrificial layer 308. Exemplarily, the sacrificial layer 308 can be oxide materials such as silicon dioxide and silicon nitride, or high-temperature-resistant polymers or compounds such as aluminum arsenide, etc. This example is not limited. The holes of the sacrificial layer 308 have an upper bottom (the side away from the growth substrate 307) and a lower bottom (the side close to the growth substrate 307). The size of its upper bottom is equivalent to that of the contact 302 on the subsequent substrate 301, and the size of the lower bottom is slightly smaller than that of the upper bottom. The depth of the hole is the same as the height to which the epitaxial layer is to grow. The epitaxial layer grown in this example at least includes a first-type semiconductor layer 101, an active layer 102, and a second-type semiconductor layer 103. It can be selected that the side close to the growth substrate 307 is N-type doped. For the convenience of explaining this embodiment, only the example of N-type doping on the side close to the growth substrate 307 is taken. In fact, when the side close to the growth substrate 307 is a p-doped semiconductor, the steps are the same, and only the positive and negative electricities of the circuit on the substrate 301 need to be changed.

[0101] In this example, an epitaxial layer is grown in the holes, and an epitaxial structure is formed in each hole. For the convenience of explanation, this example takes three holes as an example. The epitaxial structures in two of the holes are the first epitaxial structure 203, and the epitaxial structure formed in the other hole is the second epitaxial structure 204. In fact, a large number of holes can be formed on the same growth substrate 307, and a plurality of first epitaxial structures 203 and a plurality of second epitaxial structures 204 can be obtained. It can be understood that since the first epitaxial structure 203 and the second epitaxial structure 204 can be formed together on the same growth substrate 307, their components are the same, and the structures can also be the same. In this example, the epitaxial structure is obtained through the holes formed by the sacrificial layer 308, without etching the epitaxial material, avoiding the damage caused by etching, and can improve the radiation efficiency in some implementation processes.

[0102] See Figure 12 , which is a specific example of an epitaxial structure. The epitaxial structure in this example sequentially includes a u-GaN layer 1001, an N-GaN layer 1002, an electron deceleration layer 1003, a low-doped gallium nitride layer 1004, a stress release layer 1005, an active layer 102, a hole accumulation layer 1006, and a p-GaN layer 1007 on the growth substrate 307. Exemplarily, the thickness of the u-GaN layer 1001 is 2.5 μm, and the thickness of the N-GaN layer 1002 is 1.3 μm. Silicon doping can be used, and the doping concentration is 1×101 9 cm-3 ; The thickness of the electron deceleration layer 1003 is 90 nm, and it is composed of 15 pairs of superlattices formed by n-GaN / n-AlGaN; the stress release layer 1005 is a 6-pair superlattice structure formed by In 0.05 Ga 0.95 N with a thickness of 3 nm and GaN with a thickness of 5 nm; the active layer 102 is composed of 15 pairs of quantum well layers formed by In 0.12 Ga 0.88 N with a thickness of 2.5 nm and GaN with a thickness of 7 nm; the hole accumulation layer 1006 is composed of GaN with a p-doping concentration greater than 101 9 cm -3 , and its thickness is 60 nm - 80 nm; the p-GaN layer 1007 is composed of a GaN layer doped with Mg with a thickness of 120 nm.

[0103] Continuing Figure 12 from the example, the total thickness of the entire epitaxial wafer can be obtained as 3.8 μm ± 0.5 μm. The thickness of the epitaxial structure in this example is very thin, and combined with the electron deceleration layer 1003, the low-doped gallium nitride layer 1004, and the stress release layer 1005, there is a strong quantum-confined Stark effect in the epitaxial wafer, thereby realizing green light at low current and blue light at high current, enabling two colors, blue and green, to be achieved on the same epitaxial wafer.

[0104] Such as Figure 11 S502 in, a current spreading layer 106 and a first bonding metal layer 107 are prepared on the surface of the epitaxial wafer after selective growth. The current spreading layer 106 and the first bonding metal layer 107 are disposed entirely on the surface of the epitaxial wafer and are in contact with the epitaxial layer. Among them, the current spreading layer 106 is close to the epitaxial layer, and the first bonding metal layer 107 is disposed on the current spreading layer 106. The first bonding metal layer 107 can be an alloy formed by one or more of metal materials such as Ti / Al / Ti / Au / Cr / pt / In / Sn / Ag, and the current spreading layer 106 can be a metal or a transparent conductive material and form an ohmic contact with gallium nitride. In this example, the specific contact resistivity is controlled to be less than 10 -5 Ω·cm 2 , for the convenience of description, in this example, the current spreading layer 106 is only taken as indium tin oxide as an example, and its material is not actually limited. In addition, the thickness of the first bonding metal layer 107 can be between 50 - 1000 μm, and the specific thickness is not limited.

[0105] Such as Figure 11In S503, a second bonding metal layer 309 is prepared on the substrate 301. The second bonding metal layer 309 can be an alloy formed by one or more of metal materials such as Ti / Al / Au / Cr / pt / In / Sn / Ag / Cu, etc. Subsequently, the substrate 301 and the epitaxial wafer obtained in step S502 are bonded and integrated through the bonding metal layer, and the first bonding metal layer 107 and the second bonding metal layer 309 are combined to form a bonding layer 303. The bonding effect can be achieved by applying pressure and heating. The substrate 301 in this example can be a CMOS (Complementary Metal Oxide Semiconductor) driving backplane, and the TFT (Thin Film Transistor) driving backplane can also be LTpS (Low Temperature poly-Silicon). There should be multiple contacts 302 on it, and the center pitch of the contacts 302 should be consistent with the pixel size of the display module to be made. For the convenience of description, only the CMOS backplane is taken as an example in this disclosure, and only some of the contacts 302 are shown schematically. As Figure 12 Taking S503 as an example, for the convenience of description, the leftmost contact 302 in the figure is the N pole, and the remaining contacts 302 in the figure are the p poles. The actual number of specific contacts 302 and their positive and negative polarities are not limited.

[0106] See Figure 11 In S504, the growth substrate 307 is removed. The growth substrate 307 in this example is a sapphire substrate, which can be removed by laser lift-off. The laser for laser lift-off can use a solid-state laser. After the laser lift-off is completed, the removal of gallium metal needs to be synchronized. It should be noted that in some implementation processes, in order to match the epitaxial characteristics, after the growth substrate 307 is removed, the sputter AlN (aluminum nitride thin film buffer layer) and unintentionally doped gallium nitride layer and other buffer layers of the gallium nitride material are also etched away to expose the N-type doped gallium nitride, and then the subsequent chip manufacturing process is carried out. For the convenience of description, some steps are omitted in the illustration of this example. The structural schematic diagram after the laser lift-off and the removal of the buffer layer is as shown in Figure 12 S504 shown.

[0107] See Figure 11 In S505, the sacrificial layer 308 is removed. The preparation method of the sacrificial layer 308 can be selected according to the material of the sacrificial layer 308 used. Exemplarily, wet etching can be used for removal. The first epitaxial structure 203 and the second epitaxial structure 204 after the removal of the sacrificial layer 308 are used for the fabrication of light-emitting units in the subsequent manufacturing process.

[0108] Continuing with the above example, see Figure 13For S506, a first insulating material 304 is disposed on the first epitaxial structure 203 and the second epitaxial structure 204 to form an etching mask 108, and the etching mask 108 can be selected according to the thickness of the bonding layer 303. The first insulating material 304 includes, but is not limited to, insulating materials such as silicon dioxide and aluminum oxide. After the etching mask 108 is prepared, a patterning etching process is performed to expose the bonding layer 303 that needs to be etched. The structure after the etching mask 108 is prepared is as shown in Figure 13 of S506.

[0109] See Figure 13 For S507, after the preparation of the etching mask 108 is completed, the bonding layer 303 is etched. The purpose of etching the bonding layer 303 is to disconnect adjacent light-emitting units, thereby obtaining a plurality of independent light-emitting units. Among them, the etching method includes, but is not limited to, ICp (Inductively Coupled plasma) etching or IBE (Ion Beam Etching). In this example, after etching, the metal in the bonding layer 303 will redeposit on the sidewalls, which can be achieved by setting reasonable power and etching processes. The redeposited metal forms a barrier wall 306 around it, and the height of the barrier wall 306 can be slightly greater than or equal to the epitaxial structure, thereby using the barrier wall 306 to suppress the optical crosstalk between adjacent light-emitting units.

[0110] See Figure 13 For S508, after the metal etching is completed, an insulating protection layer 109 is fabricated. The insulating protection layer 109 includes, but is not limited to, aluminum oxide, silicon dioxide, etc. It can be the same as or different from the material of the etching mask 108. The insulating protection layer 109 can be disposed by processes including, but not limited to, ALD, pECVD, etc. The insulating protection layer 109 can passivate and insulate the bonding layer 303 and its barrier wall 306 portions. The thickness of the insulating protection layer 109 fabricated in this step S508 can be more than twice the depth of the isolation trench between the light-emitting units, thereby ensuring that the material of the insulating protection layer 109 fills the entire isolation trench well.

[0111] Continuing the above example, see Figure 14For S509, the etch mask 108 is etched to remove the etch mask 108 and the insulating protective layer 109 on the side of the first epitaxial structure 203 away from the substrate 301. The etching of the etch mask 108 and the insulating protective layer 109 can adopt a photolithography process. A photoresist is set on the side away from the substrate 301, and the photoresist directly above the first epitaxial structure 203 is removed through processes such as exposure and development. After the etch mask 108 and the insulating protective layer 109 are removed, a groove is formed in the corresponding area, and the bottom of the groove exposes the first epitaxial structure 203. The size of the groove can be slightly larger than the area of the first epitaxial structure 203 on this side to ensure that the surface of the first epitaxial structure 203 on this side is completely exposed, providing sufficient area for ohmic contact. In some examples, the entire insulating protective layer 109 can also be etched first to expose the etch mask 108 prepared in step S506, and then in step S509, only the exposed etch mask 108 is etched and removed; the specific etching method for the entire layer etching of the insulating protective layer 109 is not limited, and it can be wet etching or dry etching.

[0112] See Figure 14 For S510, the first ohmic contact layer 1041 is fabricated. The specific preparation method can be electron beam evaporation or magnetron sputtering, etc. The thickness of the first ohmic contact layer 1041 can be to fill the groove formed by the etch mask 108 and the insulating protective layer 109 in step S509. The preparation method of the first ohmic contact layer 1041 is not limited. It can be prepared as a whole layer and then the ohmic contact layer 104 material in the area outside the first epitaxial structure 203 is removed by etching, or a glue material can be fabricated first and then the lift-off (peeling process) method is used to leave the ohmic contact layer 104 material on the first epitaxial structure 203. After the preparation of the first ohmic contact layer 1041 is completed, rapid annealing is performed, and the annealing temperature needs to be less than the melting point of the bonding layer 303. In this example, the first ohmic contact layer 1041 achieves a specific contact resistivity ≤ 10 -2 Ω·cm 2 . In this example, the material of the first ohmic contact layer 1041 can be indium tin oxide, but it is not limited thereto. For example, other materials with transparent conductivity and capable of forming an ohmic contact difference with gallium nitride can also be used, such as graphene, indium zinc oxide, thin metal film layers, etc.

[0113] See Figure 14For S511, the second ohmic contact layer 1042 is fabricated. When setting the second ohmic contact layer 1042, the etching mask 108 and the insulating protective layer 109 on the side of the second epitaxial structure 204 away from the substrate 301 can be removed in the same manner as in S509. The specific preparation method of the second ohmic contact layer 1042 can be electron beam evaporation or magnetron sputtering, etc. The thickness of the second ohmic contact layer 1042 can be to fill the grooves formed by the etching mask 108 and the insulating protective layer 109. The preparation method of the second ohmic contact layer 1042 is not limited. The ohmic contact layer 104 material outside the second epitaxial structure 204 can be removed by etching after the whole layer is prepared, or the material of the ohmic contact layer 104 on the second epitaxial structure 204 can be left by using the lift-off method after the glue material is first made. Of course, the first ohmic contact layer 1041 that has been fabricated is not affected during this process. After the preparation of the second ohmic contact layer 1042 is completed, rapid annealing is performed under annealing conditions different from those during the annealing of the first ohmic contact layer 1041, and the annealing temperature needs to be less than the melting point of the bonding layer 303. In this example, the specific contact resistivity of the second ohmic contact layer 1042 is ≤10 -2 Ω·cm 2 and the specific contact resistivity B of the second ohmic contact layer 1042 is not less than five times the specific contact resistivity A of the first ohmic contact layer 1041. In this example, the material of the second ohmic contact layer 1042 can also be indium tin oxide, but it is not limited thereto. For example, other materials with transparent conductivity and capable of forming an ohmic contact difference with gallium nitride can also be used, such as graphene, indium zinc oxide, thin metal film layers, etc.

[0114] The first ohmic contact layer 1041 and the second ohmic contact layer 1042 fabricated through the above steps, wherein the ohmic contact effect between the first ohmic contact layer 1041 and the first epitaxial structure 203 is better than the ohmic contact effect between the second ohmic contact layer 1042 and the second epitaxial structure 204. Furthermore, under the same driving voltage, the current on the first epitaxial structure 203 is greater than the current on the second epitaxial structure 204. In this example, on the basis that the first epitaxial structure 203 and the second epitaxial structure 204 are configured to emit light of different wavelengths according to different currents, the larger current of the first epitaxial structure 203 will cause it to emit blue light; the smaller current of the second epitaxial structure 204 will cause it to emit green light, thereby obtaining a monolithic integrated blue-green dual-color display module.

[0115] See Figure 14For S512, the common electrode 305 is fabricated. The common electrode 305 has openings above the first ohmic contact layer 1041 and the second ohmic contact layer 1042, and is connected to the first ohmic contact layer 1041 and the second ohmic contact layer 1042 to connect the same poles of adjacent light-emitting units. For the convenience of description, in this embodiment, the common electrode 305 is the N pole, and the common electrode 305 is connected to the contact 302 on the leftmost side (in the illustrated direction) of the substrate 301 through a via hole or wire bonding. The material and thickness of the common electrode 305 are not limited in this example.

[0116] Continuing from the foregoing example, continue to refer to Figure 15 For S513, the light-blocking layer 310 is fabricated. The light-blocking layer 310 can be a black adhesive material, such as black photoresist, and its thickness is not limited. The light-blocking layer 310 is disposed in the light-emitting direction and is provided with an opening for light to exit.

[0117] Refer to Figure 15 For S514, a color conversion layer 311 and a color purification layer are disposed in the opening of the light-blocking layer 310. Among the two first epitaxial structures 203, a red quantum dot material is disposed as the color conversion layer 311 in the opening corresponding to one of the first epitaxial structures 203. The display module can sequentially emit red light, blue light, and green light from left to right (in the illustrated direction) to achieve full-color display. The preparation method of the red quantum dots can be inkjet printing, microporous filling, or nanoimprinting, and the specific method is not limited. The red quantum dots can be perovskite materials, Cd-based materials, or Cd-free materials, and the specific type is not limited. A first color purification layer 312 is disposed above the other first epitaxial structure 203. The first color purification layer 312 transmits blue light and has a low transmittance to light of other wavelengths; a second color purification layer 313 is disposed above the second epitaxial structure 204. The second color purification layer 313 transmits green light and has a low transmittance to light of other wavelengths. In this example, the sizes of the first color purification layer 312 and the second color purification layer 313 are the same as the lower bases of the first epitaxial structure 203 and the second epitaxial structure 204 respectively to ensure the color filtering effect. The specific preparation method of the color purification layer can be inkjet printing, transfer printing, nanoimprinting, etc., and this embodiment is not limited.

[0118] Refer to Figure 15 For S515, to ensure the conversion efficiency of the color conversion layer 311, a reflective layer 314 is disposed on the color conversion layer 311. The reflective layer 314 reflects blue light and transmits red light, thereby improving the efficiency of converting blue light into red light. The reflective layer 314 can be a DBR (distributed Bragg reflection), and can be fabricated by alternately laminating high and low refractive index oxides or adhesive materials, and the specific material is not limited.

[0119] Refer toFigure 15 For the S516, in order to optimize the light pattern, a light pattern adjustment structure 315 is further provided in each light-emitting unit. In this example, the light pattern adjustment structure 315 is in the form of a convex lens and can be configured to suppress the light divergence angle of the light-emitting chip. In practical applications, the light pattern adjustment structure 315 can also be formed into other shapes. The light pattern adjustment structure 315 can form an array, and the preparation method of the light pattern adjustment structure 315 array is not limited, and can be nanoimprinting, micro-lens array transfer, or hot-melt photoresist etching oxide preparation, etc. The light pattern adjustment structure 315 array can use a material with a visible light band transmittance greater than 90% and a visible light band refractive index > 1.30.

[0120] The display module of the above example realizes blue and green dual-color emission based on the same epitaxial wafer structure, has high production efficiency, obtains red light through the color conversion layer 311, realizes full-color display, and only needs to set one color conversion layer 311 to achieve three-color display, reducing the setting times of the color conversion layer 311, simplifying the production of the color conversion layer 311, and avoiding the stability impact caused by multiple processing when at least two color conversion layers 311 are produced.

[0121] It should be understood that the application of this application is not limited to the above examples. For those of ordinary skill in the art, improvements or transformations can be made according to the above description, and all these improvements and transformations should fall within the protection scope of the appended claims of this application.

Claims

1. A display module, characterized in that, Comprising: A substrate; A plurality of light-emitting units disposed on the substrate, the light-emitting units including an epitaxial structure and an ohmic contact layer disposed on the epitaxial structure; wherein, the ohmic contact resistance of the ohmic contact layer of at least some of the light-emitting units is different from the ohmic contact resistance of the ohmic contact layer of other light-emitting units, and the epitaxial structure is configured to have a wavelength shift of more than 60 nm under different currents, so that the at least some of the light-emitting units have a different emission wavelength from other light-emitting units under the same driving voltage; A color conversion layer disposed in the light-emitting direction of some of the light-emitting units, the color conversion layer being configured to convert the light emitted by the light-emitting unit into light of another wavelength, so that the display module presents colors of at least three wavelengths.

2. The display module according to claim 1, wherein The light-emitting unit further includes a metal electrode disposed on the opposite side of the light-emitting direction, the metal electrode connecting the epitaxial structure and the substrate and protruding away from the substrate around the epitaxial structure to form a barrier wall for blocking the lateral light of the light-emitting unit.

3. The display module according to claim 1, wherein, The substrate includes a circuit layer, and the epitaxial structure is bonded to the substrate and connected to the circuit layer; The ohmic contact layer is located on the side of the epitaxial structure away from the substrate; The display module further includes a wiring layer on the side of the epitaxial structure away from the substrate, and the ohmic contact layer is connected to the circuit layer through the wiring layer.

4. The display module according to claim 1, wherein The plurality of light-emitting units include light-emitting units having two emission wavelengths and a quantity ratio of 2:1, and the color conversion layer is disposed in the light-emitting direction of the light-emitting units with a larger quantity among them, so that the display module presents colors of three wavelengths arranged in pixels.

5. The display module according to claim 1, wherein The ohmic contact resistance of the ohmic contact layer of the light-emitting unit provided with the color conversion layer is greater than or equal to the ohmic contact resistance of the ohmic contact layer on other light-emitting units.

6. The display module according to any one of claims 1-5, characterized in that The ohmic contact layers of the plurality of light-emitting units satisfy at least one of the following conditions: The ohmic contact area of the ohmic contact layer of at least some of the light-emitting units is different from the ohmic contact area of the ohmic contact layer of other light-emitting units; The material of the ohmic contact layer of at least some of the light-emitting units is different from the material of the ohmic contact layer of other light-emitting units; The diffusion depth of the ohmic contact layer of at least some of the light-emitting units into the epitaxial structure is different from the diffusion depth of the ohmic contact layer of other light-emitting units into the epitaxial structure.

7. A manufacturing method of a display module, characterized in that, Comprising: Providing a substrate; Setting a plurality of light-emitting units on the substrate, the light-emitting units including an epitaxial structure and an ohmic contact layer disposed on the epitaxial structure; wherein, the ohmic contact resistance of the ohmic contact layer of at least some of the light-emitting units is different from the ohmic contact resistance of the ohmic contact layer of other light-emitting units, and the epitaxial structure is configured to have a wavelength shift of more than 60 nm under different currents, so that the at least some of the light-emitting units have a different emission wavelength from other light-emitting units under the same driving voltage; Setting a color conversion layer in the light-emitting direction of some of the light-emitting units, the color conversion layer being configured to convert the light emitted by the light-emitting unit into light of another wavelength, so that the display module presents colors of at least three wavelengths.

8. The manufacturing method of the display module according to claim 7, wherein, The setting a plurality of light-emitting units on the substrate includes: Set the epitaxial structure on the substrate; Set an insulating material on the epitaxial structure, and the insulating material covers the surface of the epitaxial structure; Remove the insulating material on one side of the part of the epitaxial structure away from the substrate to expose the part of the epitaxial structure; Set an ohmic contact layer on the part of the epitaxial structure; Remove the insulating material on one side of the remaining epitaxial structure away from the substrate to expose the remaining epitaxial structure; Set an ohmic contact layer with an ohmic contact resistance different from that of the ohmic contact layer on the part of the epitaxial structure on the remaining epitaxial structure.

9. The manufacturing method of the display module according to claim 7, characterized in that The substrate includes a circuit layer and a bonding layer laid on the circuit layer, and the bonding layer is connected to the circuit layer. The manufacturing method of the display module further includes: dividing the bonding layer into metal electrodes corresponding to each light-emitting unit respectively by etching, and during the process of etching the bonding layer, making the bonding layer reattach in the etched area to form a retaining wall protruding away from the substrate.

10. A display device, characterized in that, It includes a frame body and the display module according to any one of claims 1-6 provided on the frame body.

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