A micro light emitting diode display module and a method for preparing the same

Abstract

The present application provides a micro light emitting diode display module and a preparation method thereof, wherein the micro light emitting diode display module includes a driving substrate and a plurality of light emitting structures, wherein the plurality of light emitting structures are arranged on one side of the driving substrate and are electrically connected to the driving substrate, wherein each light emitting structure includes a P-type semiconductor layer, a quantum well light emitting layer, and an N-type semiconductor layer which are sequentially stacked in a direction away from the driving substrate; wherein the cross-sectional lengths of the P-type semiconductor layer, the quantum well light emitting layer, and the N-type semiconductor layer in each light emitting structure decrease in sequence, and the plurality of N-type semiconductor layers in the plurality of light emitting structures are spaced apart from each other. In the micro light emitting diode display module provided by the present application, the light emitting structure has a high light emitting brightness, which can improve the problem of low brightness of LED chips existing in the related art, and the plurality of N-type semiconductor layers in the plurality of light emitting structures are spaced apart from each other, which can improve the problem of light crosstalk between adjacent plurality of LED chips.

Description

Technical Field

[0001] The present application relates to the field of semiconductor technology, and in particular to a micro light emitting diode display module and a method for preparing the same. Background Art

[0002] Light Emitting Diode (LED) is an electroluminescent semiconductor light-emitting device. It has been widely used in lighting, display, medical treatment, optical communication and other fields due to its advantages of low energy consumption, small size, long life, good stability, fast response and stable luminous wavelength.

[0003] At present, the development trend in the LED field is to miniaturize LED chips, for example, to reduce them to micron size, so as to use micro LED chips directly as display pixels to form micro LED display screens, in order to replace the liquid crystal display screens (English full name: Liquid Crystal Display, abbreviated as: LCD) and organic light-emitting diode display screens (English full name: Organic Light Emitting Diode, abbreviated as: OLED) widely used in small and medium-sized display application scenarios such as indoor TVs, mobile phone displays, wearable devices, and virtual reality display devices.

[0004] The preparation of micro-LED display modules requires the precise transfer and bonding of a large number of micron-sized LED chips to the drive substrate. In the related art, the brightness of each LED chip on the drive substrate is low, and the semiconductor layer close to the light-emitting side of each LED chip is often completely connected, resulting in optical crosstalk between adjacent LED chips. The above problems need to be solved urgently. Summary of the invention

[0005] The present application provides a micro light emitting diode display module and a preparation method thereof, which can effectively solve the problems of low brightness of LED chips and optical crosstalk between adjacent multiple LED chips existing in the micro light emitting diode display module in the related art.

[0006] In a first aspect, the present application provides a micro-light emitting diode display module, which includes: a driving substrate; a plurality of light-emitting structures, which are arranged on one side of the driving substrate and electrically connected to the driving substrate, each of the light-emitting structures including a P-type semiconductor layer, a quantum well light-emitting layer, and an N-type semiconductor layer stacked in sequence in a direction away from the driving substrate; wherein the cross-sectional lengths of the P-type semiconductor layer, the quantum well light-emitting layer, and the N-type semiconductor layer in each of the light-emitting structures decrease in sequence, and the plurality of N-type semiconductor layers in the plurality of light-emitting structures are spaced apart from each other.

[0007] Optionally, the micro light emitting diode display module further includes: a passivation layer, arranged on a side of the plurality of light emitting structures away from the driving substrate, wherein the passivation layer includes a plurality of through holes, the through holes are arranged in a one-to-one correspondence with the light emitting structures, and the through holes expose at least a portion of the side wall of the N-type semiconductor layer in the corresponding light emitting structure; an electrode layer, arranged on a side of the plurality of light emitting structures away from the driving substrate and electrically connected to the driving substrate, wherein the electrode layer includes a plurality of electrode portions connected in series, each of the electrode portions is correspondingly arranged in one of the through holes and in contact with the side wall of the N-type semiconductor layer in the corresponding light emitting structure.

[0008] Optionally, in a direction perpendicular to the driving substrate, the electrode layer does not overlap with a surface of the light emitting structure on a side facing away from the driving substrate.

[0009] Optionally, each of the light-emitting structures further includes a buffer layer, which is arranged on a side of the N-type semiconductor layer away from the quantum well light-emitting layer; wherein, in each of the light-emitting structures, the cross-sectional lengths of the P-type semiconductor layer, the quantum well light-emitting layer, the N-type semiconductor layer, and the buffer layer decrease successively, and the multiple buffer layers in the multiple light-emitting structures are arranged at intervals from each other.

[0010] Optionally, the passivation layer covers the surface of the buffer layer in each of the light-emitting structures on a side facing away from the N-type semiconductor layer, and each of the through holes exposes at least a portion of the side wall of the N-type semiconductor layer and at least a portion of the side wall of the buffer layer in the corresponding light-emitting structure.

[0011] Optionally, the thickness of the buffer layer is greater than the thickness of the N-type semiconductor layer.

[0012] Optionally, the micro-light-emitting diode display module also includes a bonding metal layer, which is arranged between the driving substrate and the plurality of the light-emitting structures, and the bonding metal layer includes a plurality of bonding metal parts, and the light-emitting structures are fixed and electrically connected to the driving substrate through the bonding metal parts, wherein the passivation layer covers the side walls of the bonding metal parts, the side walls of the P-type semiconductor layer, the side walls of the quantum well light-emitting layer, and part of the side walls of the N-type semiconductor layer.

[0013] Optionally, the driving substrate has a first area, in which a plurality of P-type contacts are arranged in an array, wherein a plurality of the light-emitting structures and a plurality of the bonding metal parts are located in the first area, and the P-type semiconductor layer in each of the light-emitting structures is electrically connected to a P-type contact through a bonding metal part.

[0014] Optionally, the driving substrate also has a second area, the second area surrounds the first area, and a plurality of N-type contacts are arranged in the second area, wherein the micro light emitting diode display module also includes a plurality of dummy structures, the plurality of the dummy structures and the plurality of the bonding metal parts are located in the second area, and each of the dummy structures is electrically connected to one of the N-type contacts through one of the bonding metal parts; wherein the electrode layer covers the plurality of the dummy structures, and is electrically connected to the N-type semiconductor layer in each of the light emitting structures through the plurality of the dummy structures; wherein the film layer structure, shape and size of the dummy structure and the light emitting structure are the same.

[0015] In a second aspect, the present application provides a method for preparing a micro light emitting diode display module, the method for preparing a micro light emitting diode display module comprising the following steps:

[0016] Providing a growth substrate, forming an inverted light-emitting structure layer on the growth substrate, wherein the inverted light-emitting structure layer comprises an N-type semiconductor complete layer, a quantum well light-emitting complete layer and a P-type semiconductor complete layer stacked in sequence on the growth substrate;

[0017] Etching the inverted light-emitting structure layer to a depth equal to the thickness of the light-emitting structure layer, so as to form a plurality of inverted light-emitting structures spaced apart from each other on the growth substrate, wherein the cross-sectional shape of each inverted light-emitting structure is an inverted trapezoid, so that the cross-sectional lengths of the P-type semiconductor layer, the quantum well light-emitting layer, and the N-type semiconductor layer in each inverted light-emitting structure decrease in sequence;

[0018] Forming a first bonding layer on the growth substrate, wherein the first bonding layer comprises a plurality of first bonding portions and a plurality of first peeling portions, the first bonding portions are located on the inverted light emitting structure, the first peeling portions are located on the growth substrate, and the first bonding portions are not connected to the first peeling portions;

[0019] Providing a driving substrate, forming a patterned second bonding layer on the driving substrate, wherein the patterned second bonding layer includes a plurality of second bonding portions;

[0020] Flip-chip bonding the first bonding portion on the inverted light emitting structure to the second bonding portion on the driving substrate, so that the light emitting structure is disposed on the driving substrate and is electrically connected to the driving substrate;

[0021] The growth substrate is removed by lift-off.

[0022] Beneficial effects of this application:

[0023] The present application provides a micro light emitting diode display module and a preparation method thereof, wherein the micro light emitting diode display module comprises a driving substrate and a plurality of light emitting structures, wherein the plurality of light emitting structures are arranged on one side of the driving substrate and are electrically connected to the driving substrate, wherein each of the light emitting structures comprises a P-type semiconductor layer, a quantum well light emitting layer, and an N-type semiconductor layer stacked in sequence in a direction away from the driving substrate; wherein the cross-sectional lengths of the P-type semiconductor layer, the quantum well light emitting layer, and the N-type semiconductor layer in each of the light emitting structures decrease in sequence, and the plurality of N-type semiconductor layers in the plurality of light emitting structures are spaced apart from each other. In the micro-LED display module provided by the present application, since the cross-sectional lengths of the P-type semiconductor layer, the quantum well light-emitting layer, and the N-type semiconductor layer in each of the light-emitting structures are reduced in sequence, the cross-sectional length of the P-type semiconductor layer can be made larger, thereby increasing the luminous brightness of the light-emitting structure, improving the problem of low brightness of the LED chip in the micro-LED display module, and improving the display brightness and contrast of the micro-LED display module; and, since the multiple N-type semiconductor layers in the multiple light-emitting structures are arranged at intervals from each other, it is possible to prevent the light incident into the N-type semiconductor layer from being laterally propagated to the adjacent light-emitting structure with the N-type semiconductor layer as the propagation medium, thereby improving the problem of light crosstalk between multiple adjacent LED chips. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For those skilled in the art, other drawings can be obtained based on these drawings without creative work.

[0025] Figure 1 A cross-sectional schematic diagram of a micro light emitting diode display module provided in an embodiment of the present application.

[0026] Figures 2 to 10 Schematic cross-sectional view corresponding to each step in the method for preparing a micro light emitting diode display module provided in an embodiment of the present application.

[0027] Description of reference numerals:

[0028] Driving substrate 10; first region 101; second region 102; P-type contact 11; N-type contact 12; light emitting structure 20; P-type semiconductor layer 21; side wall 211 of P-type semiconductor layer; quantum well light emitting layer 22; side wall 221 of quantum well light emitting layer; N-type semiconductor layer 23; side wall 231 of N-type semiconductor layer; buffer layer 24; side wall 241 of buffer layer; passivation layer 30; through hole 31; electrode layer 40; electrode part 41; bonding metal layer 50; bonding metal part 51; side wall 511 of bonding metal part; dummy structure 60; growth substrate 100; light emitting structure layer 200; buffer complete layer 204; N-type semiconductor complete layer 203; quantum well light emitting complete layer 202; P-type semiconductor complete layer 201; first bonding layer 300; first bonding part 301; first peeling part 302; second bonding layer 400; second bonding part 401; passivation complete layer 500; DETAILED DESCRIPTION

[0029] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present application. In addition, it should be understood that the specific implementation methods described herein are only used to illustrate and explain the present application, and are not used to limit the present application. In the present application, unless otherwise stated, the directional words such as "upper" and "lower" used generally refer to the upper and lower parts of the device in actual use or working state, specifically the drawing direction in the accompanying drawings; while "inside" and "outside" refer to the outline of the device.

[0030] The disclosure below provides many different embodiments or examples to realize the different structures of the present application. In order to simplify the disclosure of the present application, the parts and settings of specific examples are described below. Of course, they are only examples, and the purpose is not to limit the present application. In addition, the present application can repeat reference numbers and / or reference letters in different examples, and this repetition is for the purpose of simplification and clarity, and does not indicate the relationship between the various embodiments and / or settings discussed in itself. In addition, the present application provides various specific examples of processes and materials, but those of ordinary skill in the art can be aware of the application of other processes and / or the use of other materials. The following is described in detail respectively, and it should be noted that the description order of the following embodiments is not used as a limitation to the preferred order of the embodiments.

[0031] Figure 1 This is a cross-sectional schematic diagram of a micro-LED display module provided in an embodiment of the present application. Figure 1As shown, an embodiment of the present application provides a micro light emitting diode display module, which includes a driving substrate 10 and a plurality of light emitting structures 20, wherein the plurality of light emitting structures 20 are arranged on one side of the driving substrate 10 and are electrically connected to the driving substrate 10, and each of the light emitting structures 20 includes a P-type semiconductor layer 21, a quantum well light emitting layer 22, and an N-type semiconductor layer 23 which are sequentially stacked in a direction away from the driving substrate 10; wherein the cross-sectional lengths of the P-type semiconductor layer 21, the quantum well light emitting layer 22, and the N-type semiconductor layer 23 in each of the light emitting structures 20 decrease sequentially, and the plurality of N-type semiconductor layers 23 in the plurality of light emitting structures 20 are spaced apart from each other.

[0032] In the micro-light emitting diode display module provided in the embodiment of the present application, the light emitting structure 20 can be understood as the light emitting part in the LED chip, and its structural design will have an important impact on the actual light emitting brightness of the LED chip. The driving substrate 10 is used to drive the multiple light emitting structures 20 to emit light. In the process of the driving substrate 10 driving the light emitting structure 20 to emit light, compared with the N-type semiconductor layer 23, the recombination area of ​​holes and electrons and the light generation area are closer to the P-type semiconductor layer 21, that is, when the cross-sectional length of the P-type semiconductor layer 21 is larger, it is more conducive to the light emitting structure 20 to generate more outgoing light, thereby improving the light emitting brightness of the light emitting structure 20. However, due to the limitations of the process, in the prepared light emitting structure 20, there will be differences in the cross-sectional lengths of the P-type semiconductor layer 21, the quantum well light emitting layer 22, and the N-type semiconductor layer 23. On this basis, the present application reduces the cross-sectional lengths of the P-type semiconductor layer 21, the quantum well light-emitting layer 22, and the N-type semiconductor layer 23 in each of the light-emitting structures 20 in sequence, thereby making the cross-sectional length of the P-type semiconductor layer 21 larger, thereby improving the luminous brightness of the light-emitting structure 20, improving the problem of low brightness of the LED chip in the micro light-emitting diode display module, and improving the display brightness and contrast of the micro light-emitting diode display module.

[0033] In addition, in the micro-LED display module provided in the embodiment of the present application, the light emitting direction of the light emitting structure 20 is the direction in which the N-type semiconductor layer 23 is away from the P-type semiconductor layer 21, that is, the light generated in the quantum well light emitting layer 22 needs to pass through the N-type semiconductor layer 23, emit to the outside of the micro-LED display module, and be perceived by the user or received by the device. Since the multiple N-type semiconductor layers 23 in the multiple light emitting structures 20 are arranged at intervals from each other, it is possible to prevent the light incident into the N-type semiconductor layer 23 from being laterally propagated to the adjacent light emitting structure 20 with the N-type semiconductor layer 23 as the propagation medium, thereby improving the problem of light crosstalk between adjacent multiple LED chips.

[0034] In some embodiments of the present application, the size of the LED chip is in the micron level. For example, the long side size of the LED chip is between 100um and 300um. In this case, the micro light emitting diode in the micro light emitting diode display module is defined as Mini-LED. For another example, the long side size of the LED chip is less than or equal to 100um. In this case, the micro light emitting diode in the micro light emitting diode display module is defined as Micro-LED.

[0035] Continue to refer to Figure 1 In some embodiments of the present application, the micro-LED display module further includes a passivation layer 30 and an electrode layer 40, wherein the passivation layer 30 is arranged on a side of the plurality of light-emitting structures 20 away from the driving substrate 10, wherein the passivation layer 30 includes a plurality of through holes 31, and the through holes 31 are arranged one-to-one with the light-emitting structures 20, and the through holes 31 expose at least a portion of the side wall 231 of the N-type semiconductor layer 23 in the corresponding light-emitting structure 20; the electrode layer 40 is arranged on a side of the plurality of light-emitting structures 20 away from the driving substrate 10, and is electrically connected to the driving substrate 10, wherein the electrode layer 40 includes a plurality of electrode portions 41 connected in series with each other, each of the electrode portions 41 is correspondingly arranged in one of the through holes 31, and contacts with the side wall 231 of the N-type semiconductor layer 23 in the corresponding light-emitting structure 20.

[0036] In the micro-LED display module provided in the embodiment of the present application, the passivation layer 30 has good chemical inertness and insulation performance, and can protect at least part of the film layer in the light-emitting structure 20, prevent short circuits between two adjacent light-emitting structures 20, and improve the stability and reliability of the micro-LED display module. On this basis, the present application performs a specific patterning process on the passivation layer 30, so that the passivation layer 30 includes a plurality of through holes 31, and each through hole 31 exposes at least part of the side wall 231 of the N-type semiconductor layer 23 in the light-emitting structure 20, so that at least part of the side wall 231 of the N-type semiconductor layer 23 in each light-emitting structure 20 is exposed, so that each light-emitting structure 20 can directly use the side wall 231 of the N-type semiconductor layer 23 as an electrical connection point, contact and electrically connect with each electrode portion 41 in the electrode layer 40 having a common potential, and then form an independent closed loop with the driving substrate 10 through the electrode layer 40. The micro-LED display module provided in the embodiment of the present application enables each of the light-emitting structures 20 to realize an independent light-emitting function, while fully utilizing the side wall 231 of the N-type semiconductor layer 23, thereby eliminating the need to form an additional step structure in the light-emitting structure 20 as an electrical connection contact. This not only simplifies the process steps, but also can further reduce the size of the light-emitting structure 20, which is conducive to the miniaturization of LED chips, improves the space utilization of the micro-LED display module, and can achieve a display effect with higher resolution and high display quality with higher pixel integration.

[0037] In some embodiments of the present application, in a direction perpendicular to the driving substrate 10 , the electrode layer 40 does not overlap with a surface of the light emitting structure 20 on a side facing away from the driving substrate 10 .

[0038] In the micro-LED display module provided in the embodiment of the present application, the surface of the light-emitting structure 20 on the side away from the driving substrate 10 is the light-emitting surface of the light-emitting structure 20. Since the electrode layer 40 does not overlap with the surface of the light-emitting structure 20 on the side away from the driving substrate 10, the electrode layer 40 can achieve electrical connection with the N-type semiconductor layer 23 in each of the light-emitting structures 20 while avoiding the problem of blocking or weakening the emitted light of the light-emitting structure 20, thereby improving the display brightness of the micro-LED display module.

[0039] In some embodiments of the present application, an angle between the sidewall 231 of the N-type semiconductor layer 23 and an orthographic projection of the sidewall 231 of the N-type semiconductor layer 23 on the driving substrate 10 is a first angle, and the first angle is an acute angle.

[0040] In the micro-light emitting diode display module provided in the embodiment of the present application, since the first angle is an acute angle, that is, the side wall 231 of the N-type semiconductor layer 23 is a slope, the area of ​​the side wall 231 of the N-type semiconductor layer 23 can be increased, so that the contact area between the electrode portion 41 in the through hole 31 and the side wall 231 of the N-type semiconductor layer 23 is increased, the stability is improved, and the electrical signal transmission effect is better.

[0041] In some embodiments of the present application, the first angle is between 60° and 80°.

[0042] In the micro-LED display module provided by the embodiment of the present application, when the thickness of the N-type semiconductor layer 23 remains unchanged, when the first angle is closer to 90°, the greater the inclination of the side wall 231 of the N-type semiconductor layer 23 relative to the driving substrate 10, the smaller the contact area of ​​the side wall 231 of the N-type semiconductor layer 23; when the first angle is closer to 0°, the smaller the inclination of the side wall 231 of the N-type semiconductor layer 23 relative to the driving substrate 10, the smaller the light emitting area of ​​the light emitting structure 20. The present application controls the first angle between 60° and 80°, thereby controlling the inclination of the side wall 231 of the N-type semiconductor layer 23 relative to the driving substrate 10, controlling the area of ​​the side wall 231 of the N-type semiconductor layer 23 at a higher level, ensuring the light emitting area of ​​the light emitting structure 20, improving the production yield, and reducing the process difficulty and production cost. Optionally, the first angle is 80°, 77°, 75°, 72°, 70°, 68°, 65°, 62°, 60°, etc. Of course, the present application does not limit the specific degree of the first angle, and in other embodiments of the present application, the first angle may also be greater than 75°.

[0043] In some embodiments of the present application, each of the light-emitting structures 20 further includes a buffer layer 24, and the buffer layer 24 is arranged on a side of the N-type semiconductor layer 23 away from the quantum well light-emitting layer 22; wherein, in each of the light-emitting structures 20, the cross-sectional lengths of the P-type semiconductor layer 21, the quantum well light-emitting layer 22, the N-type semiconductor layer 23, and the buffer layer 24 decrease successively, and the multiple buffer layers 24 in the multiple light-emitting structures 20 are arranged at intervals from each other.

[0044] In the micro-LED display module provided in the embodiment of the present application, the light emitting direction of the light emitting structure 20 is the direction in which the N-type semiconductor layer 23 is away from the P-type semiconductor layer 21, that is, the light generated in the quantum well light emitting layer 22 needs to pass through the buffer layer 24, be emitted to the outside of the micro-LED display module, and be perceived by the user or received by the device. Since the multiple buffer layers 24 in the multiple light emitting structures 20 are arranged at intervals from each other, it is possible to prevent the light incident into the buffer layer 24 from being propagated laterally to the adjacent light emitting structure 20 with the buffer layer 24 as the propagation medium, thereby improving the problem of light crosstalk between adjacent multiple LED chips.

[0045] In some embodiments of the present application, the passivation layer 30 covers the surface of the buffer layer 24 on the side facing away from the N-type semiconductor layer 23 in each of the light-emitting structures 20, and each of the through holes 31 exposes at least a portion of the side wall 231 of the N-type semiconductor layer 23 and at least a portion of the side wall 241 of the buffer layer 24 in the corresponding light-emitting structure 20.

[0046] In the micro-LED display module provided in the embodiment of the present application, the passivation layer 30 covers the surface of the buffer layer 24 in each of the light-emitting structures 20 that is away from the N-type semiconductor layer 23, thereby being able to better protect the light-emitting structure 20 and improve the stability of the light-emitting structure 20; in addition, since each of the through holes 31 exposes at least a portion of the side wall 231 of the N-type semiconductor layer 23 and at least a portion of the side wall 241 of the buffer layer 24 in the corresponding light-emitting structure 20, the area of ​​the through hole 31 can be increased, the difficulty of forming the through hole 31 can be reduced, and the production cost can be reduced.

[0047] In some embodiments of the present application, the thickness of the buffer layer 24 is greater than the thickness of the N-type semiconductor layer 23 .

[0048] In the micro-LED display module provided in the embodiment of the present application, since the thickness of the buffer layer 24 is greater than the thickness of the N-type semiconductor layer 23, the area of ​​the side wall 241 of the buffer layer 24 can be increased, thereby increasing the area of ​​the through hole 31 and increasing the attachment area of ​​the electrode portion 41 on the side wall of the light-emitting structure 20, thereby improving the structural stability and extending the service life of the micro-LED display module.

[0049] In some embodiments of the present application, an angle between a side wall 241 of the buffer layer 24 and an orthographic projection of the side wall 241 of the buffer layer 24 on the driving substrate 10 is a second angle, wherein the second angle is equal to the first angle.

[0050] In the micro-LED display module provided in the embodiment of the present application, since the first angle is equal to the second angle, that is, the inclination degree of the side wall 241 of the buffer layer 24 relative to the driving substrate 10 is the same as the inclination degree of the side wall 231 of the N-type semiconductor layer 23 relative to the driving substrate 10, thereby improving the adhesion stability of the electrode portion 41 on the side wall of the light-emitting structure 20, further improving the structural stability, and extending the service life of the micro-LED display module.

[0051] In some embodiments of the present application, the micro-light-emitting diode display module also includes a bonding metal layer 50, which is arranged between the driving substrate 10 and the multiple light-emitting structures 20, and the bonding metal layer 50 includes multiple bonding metal parts 51, and the light-emitting structure 20 is fixed and electrically connected to the driving substrate 10 through the bonding metal parts 51, wherein the passivation layer 30 covers the side walls 511 of the bonding metal parts 51, the side walls 211 of the P-type semiconductor layer 21, the side walls 221 of the quantum well light-emitting layer 22 and part of the side walls 231 of the N-type semiconductor layer 23.

[0052] In the micro-LED display module provided in the embodiment of the present application, the bonding metal part 51 is used to stably bond the light-emitting structure 20 to the driving substrate 10, and electrically connect the light-emitting structure 20 to the driving substrate 10. The present application allows the passivation layer 30 to cover the side wall 511 of the bonding metal part 51, the side wall 211 of the P-type semiconductor layer 21, and the side wall 221 of the quantum well light-emitting layer 22, so that the passivation layer 30 can be used to electrically isolate the adjacent multiple light-emitting structures 20, thereby avoiding the problem of short circuit between the adjacent multiple light-emitting structures 20. In addition, the present application allows the passivation layer 30 to cover part of the side wall 231 of the N-type semiconductor layer 23, thereby avoiding the problem of reduced device performance of the light-emitting structure 20 caused by the contact between the quantum well light-emitting layer 22 and the electrode part 41.

[0053] Continue to refer to Figure 1 In some embodiments of the present application, the driving substrate 10 has a first area 101, and a plurality of P-type contacts 11 are arranged in an array in the first area 101, wherein the plurality of light-emitting structures 20 and the plurality of bonding metal parts 51 are located in the first area 101, and the P-type semiconductor layer 21 in each of the light-emitting structures 20 is electrically connected to one of the P-type contacts 11 through one of the bonding metal parts 51.

[0054] In the micro-LED display module provided in the embodiment of the present application, the first area 101 can be understood as a pixel setting area or a display area in the micro-LED display module. In order to ensure that the driving substrate 10 can independently drive each of the light-emitting structures 20, it is necessary to arrange a plurality of P-type contacts 11 in an array in the first area 101, and make the P-type semiconductor layer 21 in each of the light-emitting structures 20 electrically connected to one of the P-type contacts 11 through one of the bonding metal parts 51.

[0055] In some embodiments of the present application, the driving substrate 10 further has a second area 102, the second area 102 surrounds the first area 101, and a plurality of N-type contacts 12 are arranged in the second area 102, wherein the micro light emitting diode display module also includes a plurality of dummy structures 60, the plurality of the dummy structures 60 and the plurality of the bonding metal parts 51 are located in the second area 102, and each of the dummy structures 60 is electrically connected to one of the N-type contacts 12 through one of the bonding metal parts 51; wherein the electrode layer 40 covers the plurality of the dummy structures 60, and is electrically connected to the N-type semiconductor layer 23 in each of the light emitting structures 20 through the plurality of the dummy structures 60; wherein the film layer structure, shape, and size of the dummy structure 60 and the light emitting structure 20 are the same.

[0056] In the micro-LED display module provided in the embodiment of the present application, the second area 102 surrounds the first area 101, and the second area 102 can be understood as a virtual pixel setting area or a display area in the micro-LED display module. A dummy structure 60 having the same film structure, shape, and size as the light-emitting structure 20 is set in this area. On the one hand, it can facilitate the production and preparation of the micro-LED display module, improve the preparation yield of the light-emitting structure 20, and improve the specification adaptability of the light-emitting element; on the other hand, the electrode layer 40 can be used to cover a plurality of the dummy structures 60, so that the dummy structures 60 can be used as electrical connection carriers connecting the N-type semiconductor layer 23 in the light-emitting structure 20 and the N-type contacts 12 on the driving substrate 10, and the electrical connection stability can be greatly improved by fully covering.

[0057] In some embodiments of the present application, the electrode layer 40 further covers a bonding metal portion 51 disposed between the dummy structure 60 and the driving substrate 10 .

[0058] In the micro light emitting diode display module provided in the embodiment of the present application, since the electrode layer 40 also covers the bonding metal part 51 arranged between the dummy structure 60 and the driving substrate 10, the conduction path between the electrode layer 40 and the N-type contact 12 on the driving substrate 10 is further increased, and the electrical connection stability between the N-type semiconductor layer 23 in the light emitting structure 20 and the N-type contact 12 on the driving substrate 10 is improved.

[0059] In a second aspect, the present invention also provides a method for preparing a micro-LED display module. The method for preparing a micro-LED display module provided in the present invention includes steps S01, S02, S03, S04, S05, and S06.

[0060] Figure 2 The cross-sectional diagram corresponding to step S01 in the method for preparing a micro-LED display module provided in the embodiment of the present application is combined with Figure 1 to Figure 2 As shown, step S01 includes: providing a growth substrate 100, forming an inverted light-emitting structure layer 200 on the growth substrate 100, wherein the inverted light-emitting structure layer 200 includes an N-type semiconductor complete layer 203, a quantum well light-emitting complete layer 202 and a P-type semiconductor complete layer 201 which are sequentially stacked on the growth substrate 100.

[0061] In some embodiments of the present application, in step S01 , the inverted light emitting structure layer 200 includes a buffer complete layer 204 , an N-type semiconductor complete layer 203 , a quantum well light emitting complete layer 202 and a P-type semiconductor complete layer 201 sequentially stacked on the growth substrate 100 .

[0062] In some embodiments of the present application, in step S01, the growth substrate 100 is a sapphire substrate or a silicon carbide substrate, the buffer complete layer 204 is a U-type gallium nitride layer, the N-type semiconductor complete layer 203 is an N-type gallium nitride layer, and the P-type semiconductor complete layer 201 is a P-type silicon nitride layer.

[0063] Figure 3 The cross-sectional diagram corresponding to step S02 in the method for preparing a micro-LED display module provided in the embodiment of the present application is combined with Figures 1 to 3 As shown, step S02 includes: etching the inverted light-emitting structure layer 200, wherein the etching depth is the same as the thickness of the light-emitting structure layer 200, so as to form a plurality of inverted light-emitting structures 20 spaced apart on the growth substrate 100, wherein the cross-sectional shape of each inverted light-emitting structure 20 is an inverted trapezoid, so that the cross-sectional lengths of the P-type semiconductor layer 21, the quantum well light-emitting layer 22, and the N-type semiconductor layer 23 in each inverted light-emitting structure 20 are reduced successively.

[0064] In some embodiments of the present application, step S02 includes: etching the inverted light-emitting structure layer 200, wherein the etching depth is the same as the thickness of the light-emitting structure layer 200, so as to form a plurality of inverted light-emitting structures 20 and a plurality of inverted dummy structures 60 spaced apart on the growth substrate 100, wherein the dummy structures 60 have the same film structure, shape, and size as the light-emitting structures 20, that is, the dummy structures 60 also include a P-type semiconductor layer 21, a quantum well light-emitting layer 22, an N-type semiconductor layer 23, and a buffer layer 24, and the cross-sectional lengths of the P-type semiconductor layer 21, the quantum well light-emitting layer 22, and the N-type semiconductor layer 23 in each inverted dummy structure 60 decrease successively.

[0065] In some embodiments of the present application, the inverted multiple dummy structures 60 are arranged on the periphery of the inverted multiple light emitting structures 20. The arrangement of the dummy structures 60 can improve the degree of freedom in the specification design of the micro-LED display module, and can improve the etching yield, so that the formation quality of the inverted multiple light emitting structures 20 is improved. Of course, in other embodiments of the present application, the shape and size of the dummy structures 60 can also be different from the shape and size of the light emitting structure 20.

[0066] In some embodiments of the present application, in step S02, the inverted light emitting structure layer 200 is etched by dry etching to more accurately control the shape of the sidewall of the light emitting structure 20, thereby forming a plurality of light emitting structures 20 with an inverted trapezoidal cross-sectional shape.

[0067] Figure 4 The cross-sectional diagram corresponding to step S03 in the method for preparing a micro-LED display module provided in the embodiment of the present application is combined with Figures 1 to 4 As shown, step S03 includes: forming a first bonding layer 300 on the growth substrate 100, wherein the first bonding layer 300 includes a plurality of first bonding parts 301 and a plurality of first peeling parts 302, the first bonding parts 301 are located on the inverted light emitting structure 20, the first peeling parts 302 are located on the growth substrate 100, and the first bonding parts 301 are not connected to the first peeling parts 302.

[0068] In some embodiments of the present application, in step S03, a plurality of the first bonding portions 301 are correspondingly arranged on a plurality of the inverted light-emitting structures 20, and another plurality of the first bonding portions 301 are correspondingly arranged on a plurality of the inverted dummy structures 60, and the number of the plurality of the first bonding portions 301 is equal to the sum of the number of the plurality of the light-emitting structures 20 and the plurality of the dummy structures 60.

[0069] Figure 5 The cross-sectional diagram corresponding to step S04 in the method for preparing a micro-LED display module provided in the embodiment of the present application is combined with Figures 1 to 5 As shown, step S04 includes: providing a driving substrate 10 , and forming a patterned second bonding layer 400 on the driving substrate 10 , wherein the patterned second bonding layer 400 includes a plurality of second bonding portions 401 .

[0070] In some embodiments of the present application, in step S04, the driving substrate 10 also includes a plurality of N-type contacts 12 and a plurality of P-type contacts 11, the number of the plurality of N-type contacts 12 is the same as the number of the plurality of dummy structures 60, and the number of the plurality of P-type contacts 11 is the same as the number of the plurality of light-emitting structures 20, wherein the plurality of the second bonding portions 401 are electrically connected to the corresponding plurality of P-type contacts 11, respectively, and in addition, the plurality of the second bonding portions 401 are electrically connected to the corresponding plurality of N-type contacts 12, respectively, and the number of the plurality of the second bonding portions 401 is the same as the number of the plurality of the first bonding portions 301.

[0071] Figure 6 The cross-sectional diagram corresponding to step S05 in the method for preparing a micro-LED display module provided in the embodiment of the present application is combined with Figures 1 to 6 As shown, step S05 includes: flip-chip bonding the first bonding portion 301 on the inverted light emitting structure 20 to the second bonding portion 401 on the driving substrate 10 , so that the light emitting structure 20 is disposed on the driving substrate 10 and electrically connected to the driving substrate 10 .

[0072] In some embodiments of the present application, in step S05, during the process of flip-chip bonding the first bonding portion 301 on the inverted light-emitting structure 20 and the second bonding portion 401 on the driving substrate 10, the first bonding layer 300 and the second bonding layer 400 form a bonding metal layer 50 by metal bonding, and each first bonding portion 301 and one second bonding portion 401 form a bonding metal portion 51.

[0073] Figure 7 The cross-sectional diagram corresponding to step S06 in the method for preparing a micro-LED display module provided in the embodiment of the present application is combined with Figures 1 to 7 As shown, step S06 includes: stripping and removing the growth substrate 100 .

[0074] In some embodiments of the present application, in step S06, the plurality of first peeling portions 302 attached to the surface of the growth substrate 100 are removed together with the growth substrate 100, and the growth substrate 100 together with the first peeling portions 302 can be peeled off from the light-emitting structure 20 by physical or chemical means, utilizing the difference in bonding strength or property between the first peeling portions 302, the buffer layer 24, and the growth substrate 100.

[0075] In the micro-LED display module prepared by the preparation method of the micro-LED display module provided in the embodiment of the present application, since the cross-sectional lengths of the P-type semiconductor layer 21, the quantum well light-emitting layer 22, and the N-type semiconductor layer 23 in each inverted light-emitting structure 20 are successively reduced, the cross-sectional length of the P-type semiconductor layer 21 can be maximized, thereby improving the luminous brightness of the light-emitting structure 20, improving the problem of low brightness of the LED chip in the micro-LED display module, and improving the display brightness and contrast of the micro-LED display module. In addition, since the etching depth is the same as the thickness of the light-emitting structure layer 200, the multiple N-type semiconductor layers 23 can be arranged at intervals from each other, thereby preventing the light entering the N-type semiconductor layer 23 from being transmitted laterally to the adjacent light-emitting structure 20 with the N-type semiconductor layer 23 as the transmission medium, thereby improving the problem of light crosstalk between adjacent multiple LED chips.

[0076] In addition, since the cross-sectional shape of each inverted light-emitting structure 20 is an inverted trapezoid, there is no need to set up an additional mask plate, and in the process of forming the first bonding layer 300 on the growth substrate 100, the first bonding layer 300 will not adhere to the side wall of the inverted light-emitting structure 20, so that the first bonding part 301 and the first peeling part 302 are automatically disconnected, which facilitates the subsequent peeling operation of the first peeling part 302, simplifies the process steps, and reduces the production cost.

[0077] In some embodiments of the present application, the method for preparing a micro light emitting diode display module provided in the embodiments of the present application further includes step S07, step S08, and step S09.

[0078] Figure 8 The cross-sectional diagram corresponding to step S07 in the method for preparing a micro-LED display module provided in the embodiment of the present application is combined with Figures 1 to 8 As shown, step S07 includes: forming a passivation complete layer 500 on the plurality of light emitting structures 20 , wherein the passivation complete layer 500 covers the plurality of light emitting structures 20 and the plurality of dummy structures 60 .

[0079] Fig. 9The cross-sectional diagram corresponding to step S08 in the method for preparing a micro-LED display module provided in the embodiment of the present application is combined with Figures 1 to 9 As shown, step S08 includes: patterning the passivation complete layer 500 to remove the portion of the passivation complete layer 500 that covers the multiple dummy structures 60, and forming a plurality of through holes 31, wherein the through holes 31 expose at least a portion of the side wall 231 of the N-type semiconductor layer 23 in the corresponding light-emitting structure 20.

[0080] In some embodiments of the present application, in step S08 , the through hole 31 exposes at least a portion of the sidewall 231 of the N-type semiconductor layer 23 and at least a portion of the sidewall 241 of the buffer layer 24 in the corresponding light emitting structure 20 .

[0081] In some embodiments of the present application, in step S08 , the orthographic projection of the through hole 31 on the driving substrate 10 is in the shape of a closed ring structure, such as a circular ring or a rectangular ring or a ring of other shapes.

[0082] Fig.10 The cross-sectional diagram corresponding to step S09 in the method for preparing a micro-LED display module provided in the embodiment of the present application is combined with Figures 1 to 10 As shown, step S09 includes: forming a patterned electrode layer 40, wherein the electrode layer 40 covers a plurality of the dummy structures 60, and the electrode layer 40 also includes a plurality of electrode portions 41 connected in series with each other, each of the electrode portions 41 is correspondingly arranged in one of the through holes 31, and is in contact with the side wall 231 of the N-type semiconductor layer 23 in the corresponding light-emitting structure 20.

[0083] In the micro-LED display module prepared by the method for preparing the micro-LED display module provided in the embodiment of the present application, the passivation layer 30 has good chemical inertness and insulation performance, and can protect at least part of the film layer in the light-emitting structure 20, prevent short circuit between two adjacent light-emitting structures 20, and improve the stability and reliability of the micro-LED display module. On this basis, the present application performs a specific patterning process on the passivation layer 30, so that the passivation layer 30 includes a plurality of through holes 31, and each through hole 31 exposes at least part of the side wall 231 of the N-type semiconductor layer 23 in the light-emitting structure 20, so that at least part of the side wall 231 of the N-type semiconductor layer 23 in each light-emitting structure 20 is exposed, so that each light-emitting structure 20 can directly use the side wall 231 of the N-type semiconductor layer 23 as an electrical connection point, contact and electrically connect with each electrode portion 41 in the electrode layer 40 having a common potential, and then form an independent closed loop with the driving substrate 10 through the electrode layer 40. The micro-LED display module provided in the embodiment of the present application enables each of the light-emitting structures 20 to realize an independent light-emitting function, while fully utilizing the side wall 231 of the N-type semiconductor layer 23, thereby eliminating the need to form an additional step structure in the light-emitting structure 20 as an electrical connection contact. This not only simplifies the process steps, but also can further reduce the size of the light-emitting structure 20, which is conducive to the miniaturization of LED chips, improves the space utilization of the micro-LED display module, and can achieve a display effect with higher resolution and high display quality with higher pixel integration.

[0084] In summary, the present application provides a micro-light emitting diode display module and a preparation method thereof, wherein the micro-light emitting diode display module includes a driving substrate and a plurality of light emitting structures, wherein the plurality of light emitting structures are arranged on one side of the driving substrate and are electrically connected to the driving substrate, and each of the light emitting structures includes a P-type semiconductor layer, a quantum well light emitting layer, and an N-type semiconductor layer stacked in sequence in a direction away from the driving substrate; wherein the cross-sectional lengths of the P-type semiconductor layer, the quantum well light emitting layer, and the N-type semiconductor layer in each of the light emitting structures decrease in sequence, and the plurality of N-type semiconductor layers in the plurality of light emitting structures are spaced apart from each other. In the micro-LED display module provided by the present application, since the cross-sectional lengths of the P-type semiconductor layer, the quantum well light-emitting layer, and the N-type semiconductor layer in each of the light-emitting structures are reduced in sequence, the cross-sectional length of the P-type semiconductor layer can be made larger, thereby increasing the luminous brightness of the light-emitting structure, improving the problem of low brightness of the LED chip in the micro-LED display module, and improving the display brightness and contrast of the micro-LED display module; and, since the multiple N-type semiconductor layers in the multiple light-emitting structures are arranged at intervals from each other, it is possible to prevent the light incident into the N-type semiconductor layer from being laterally propagated to the adjacent light-emitting structure with the N-type semiconductor layer as the propagation medium, thereby improving the problem of light crosstalk between multiple adjacent LED chips.

[0085] The above is a detailed introduction to a micro-light emitting diode display module and a preparation method thereof provided in an embodiment of the present application. Specific examples are used herein to illustrate the principles and implementation methods of the present application. The description of the above embodiments is only used to help understand the method of the present application and its core idea. At the same time, for those skilled in the art, according to the idea of ​​the present application, there will be changes in the specific implementation methods and application scopes. In summary, the content of this specification should not be understood as a limitation on the present application.

Claims

1. A micro light emitting diode display module, characterized in that: The micro light emitting diode display module comprises: Driver substrate; A plurality of light-emitting structures are arranged on one side of the driving substrate and are electrically connected to the driving substrate, each of the light-emitting structures comprising a P-type semiconductor layer, a quantum well light-emitting layer, and an N-type semiconductor layer stacked in sequence in a direction away from the driving substrate; The cross-sectional lengths of the P-type semiconductor layer, the quantum well light-emitting layer, and the N-type semiconductor layer in each of the light-emitting structures decrease in sequence, the cross-sectional length of the P-type semiconductor layer in each of the light-emitting structures is greater than the cross-sectional length of the N-type semiconductor layer, and the multiple N-type semiconductor layers in the multiple light-emitting structures are arranged at intervals from each other; Wherein, the micro light emitting diode display module further comprises: A passivation layer is arranged on a side of the plurality of light-emitting structures away from the driving substrate, wherein the passivation layer comprises a plurality of through holes, the through holes are arranged in one-to-one correspondence with the light-emitting structures, and the through holes expose at least a portion of the side wall of the N-type semiconductor layer in the corresponding light-emitting structure.

2. The micro light emitting diode display module according to claim 1, characterized in that: The micro light emitting diode display module also includes: An electrode layer is arranged on a side of the plurality of light-emitting structures away from the driving substrate and is electrically connected to the driving substrate, wherein the electrode layer includes a plurality of electrode portions connected in series with each other, each of the electrode portions is correspondingly arranged in one of the through holes and contacts the side wall of the N-type semiconductor layer in the corresponding light-emitting structure.

3. The micro light emitting diode display module according to claim 2, characterized in that: In a direction perpendicular to the driving substrate, the electrode layer does not overlap with a surface of the light emitting structure on a side facing away from the driving substrate.

4. The micro light emitting diode display module according to claim 3, characterized in that: Each of the light-emitting structures further comprises a buffer layer, wherein the buffer layer is arranged on a side of the N-type semiconductor layer away from the quantum well light-emitting layer; Among them, in each of the light-emitting structures, the cross-sectional lengths of the P-type semiconductor layer, the quantum well light-emitting layer, the N-type semiconductor layer, and the buffer layer decrease in sequence, and the multiple buffer layers in the multiple light-emitting structures are arranged at intervals from each other.

5. The micro light emitting diode display module according to claim 4, characterized in that: The passivation layer covers the surface of the buffer layer in each of the light emitting structures on a side away from the N-type semiconductor layer, and each of the through holes exposes at least a portion of a side wall of the N-type semiconductor layer and at least a portion of a side wall of the buffer layer in the corresponding light emitting structure.

6. The micro light emitting diode display module according to claim 5, characterized in that: The thickness of the buffer layer is greater than the thickness of the N-type semiconductor layer.

7. The micro-light emitting diode display module according to claim 2, characterized in that: The micro-luminescent light-emitting diode display module also includes a bonding metal layer, which is arranged between the driving substrate and the multiple light-emitting structures. The bonding metal layer includes multiple bonding metal parts, and the light-emitting structure is fixed and electrically connected to the driving substrate through the bonding metal parts, wherein the passivation layer covers the side walls of the bonding metal parts, the side walls of the P-type semiconductor layer, the side walls of the quantum well light-emitting layer, and part of the side walls of the N-type semiconductor layer.

8. The micro light emitting diode display module according to claim 7, characterized in that: The driving substrate has a first area, in which a plurality of P-type contacts are arranged in an array, wherein a plurality of the light-emitting structures and a plurality of the bonding metal parts are located in the first area, and a P-type semiconductor layer in each of the light-emitting structures is electrically connected to a P-type contact via a bonding metal part.

9. The micro light emitting diode display module according to claim 8, characterized in that: The driving substrate further has a second area, the second area surrounds the first area, a plurality of N-type contacts are arranged in the second area, wherein the micro light emitting diode display module further comprises a plurality of dummy structures, the plurality of dummy structures and the plurality of bonding metal parts are located in the second area, and each of the dummy structures is electrically connected to one of the N-type contacts through one of the bonding metal parts; Wherein, the electrode layer covers the plurality of the dummy structures and is electrically connected to the N-type semiconductor layer in each of the light-emitting structures through the plurality of the dummy structures; The film structure, shape and size of the dummy structure and the light-emitting structure are the same.

10. A method for preparing a micro light emitting diode display module, characterized in that: The method for preparing the micro light emitting diode display module comprises the following steps: Providing a growth substrate, forming an inverted light-emitting structure layer on the growth substrate, wherein the inverted light-emitting structure layer comprises an N-type semiconductor complete layer, a quantum well light-emitting complete layer and a P-type semiconductor complete layer stacked in sequence on the growth substrate; Etching the inverted light-emitting structure layer to a depth equal to the thickness of the light-emitting structure layer, so as to form a plurality of inverted light-emitting structures spaced apart from each other on the growth substrate, wherein the cross-sectional shape of each of the inverted light-emitting structures is an inverted trapezoid, so that the cross-sectional lengths of the P-type semiconductor layer, the quantum well light-emitting layer, and the N-type semiconductor layer in each of the inverted light-emitting structures decrease in sequence, and the cross-sectional length of the P-type semiconductor layer in each of the inverted light-emitting structures is greater than the cross-sectional length of the N-type semiconductor layer; Forming a first bonding layer on the growth substrate, wherein the first bonding layer comprises a plurality of first bonding portions and a plurality of first peeling portions, the first bonding portions are located on the inverted light emitting structure, the first peeling portions are located on the growth substrate, and the first bonding portions are not connected to the first peeling portions; Providing a driving substrate, forming a patterned second bonding layer on the driving substrate, wherein the patterned second bonding layer includes a plurality of second bonding portions; Flip-chip bonding the first bonding portion on the inverted light emitting structure to the second bonding portion on the driving substrate, so that the light emitting structure is disposed on the driving substrate and is electrically connected to the driving substrate; removing the growth substrate by stripping; Forming a passivation complete layer on the plurality of light-emitting structures, wherein the passivation complete layer covers the plurality of light-emitting structures and the plurality of dummy structures; The passivation complete layer is patterned to remove the portion of the passivation complete layer covering the plurality of dummy structures, and to form a plurality of through holes, wherein the through holes expose at least a portion of the sidewall of the N-type semiconductor layer in the corresponding light emitting structure.

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