CN115148867A

CN115148867A - Flexible Micro-LED, preparation method thereof and display device

Info

Publication number: CN115148867A
Application number: CN202210786110.XA
Authority: CN
Inventors: 邱成峰; 陈家华
Original assignee: Shenzhen Stan Technology Co Ltd
Current assignee: Shenzhen Stan Technology Co Ltd
Priority date: 2022-07-04
Filing date: 2022-07-04
Publication date: 2022-10-04

Abstract

The invention provides a flexible Micro-LED, a preparation method thereof and a display device, and belongs to the field of LED display. The preparation method of the flexible Micro-LED comprises the steps of obtaining an epitaxial wafer and a flexible substrate; etching one side of the epitaxial wafer far away from the substrate to form a plurality of spaced PN junctions; spraying a first conductive layer on one side of each PN junction, which is far away from the substrate; each PN junction is bonded with one first conductive part in an alignment way; coating the fifth photoresist on one side, far away from the substrate, of the first CPI film, etching a plurality of spaced photoetching grooves on the fifth photoresist, and filling each photoetching groove with one quantum dot; attaching a plurality of spaced color filters to a side of the second CPI film remote from the substrate; each color filter is bonded to a photolithographic trench in alignment and the substrate is stripped to form the flexible Micro-LED. The thickness of the Micro-LED is reduced by peeling off the substrate and replacing the CPI film, and the flexible Micro-LED is formed by bonding a flexible substrate with flexible materials such as the flexible CPI film, the silver nanowire conducting layer, the flexible photoresist and the like through selection and processing.

Description

Flexible Micro-LED, preparation method thereof and display device

Technical Field

The invention relates to the field of LED display, in particular to a flexible Micro-LED, a preparation method thereof and a display device.

Background

The Micro-LED display technology is a display technology in which a light-emitting Micro-scale LED (light-emitting diode) is used as a light-emitting pixel unit, and the light-emitting Micro-LED is assembled on a driving panel to form a high-density LED array. Due to the characteristics of small size, high integration level, self-luminescence and the like of the Micro-LED chip, compared with an LCD (Liquid Crystal Display) and an OLED (organic light-emitting diode), the Micro-LED chip has the advantages of brightness, resolution, contrast, energy consumption, service life, response speed, thermal stability and the like in the aspect of Display.

The existing flexible Micro-LED is supported by the glass substrate in the production process, so that the Micro-LED has poor flexibility and ductility.

Disclosure of Invention

In view of this, the invention aims to overcome the defects in the prior art and provide a flexible Micro-LED, a preparation method thereof and a display device.

The invention provides the following technical scheme: a preparation method of a flexible Micro-LED comprises the following steps:

s1, obtaining an epitaxial wafer and a flexible substrate;

s2, etching one side of the epitaxial wafer, which is far away from the substrate, to form a plurality of PN junctions which are spaced;

s3, spraying a first conducting layer on one side, away from the substrate, of each PN junction;

s4, arranging a plurality of spaced first conductive parts and a plurality of spaced second conductive parts on the flexible substrate, bonding each PN junction and one first conductive part in an alignment mode, and stripping the substrate;

s5, depositing a passivation layer on one side of the flexible substrate to cover each PN junction;

s6, etching guide holes in the passivation layer to leak each second conductive part and each N semiconductor layer, spraying a second conductive layer on the passivation layer, and filling the guide holes to realize PN junction conduction;

s7, laminating a first CPI film on one side, far away from the substrate, of the second conducting layer, coating a fifth photoresist on one side, far away from the substrate, of the first CPI film, etching a plurality of spaced photoetching grooves on the fifth photoresist, and filling one part of the photoetching grooves with one quantum dot;

s8, obtaining a substrate, laminating a second CPI film on the substrate, and attaching a plurality of spaced color filters on one side, far away from the substrate, of the second CPI film;

and S9, attaching the second CPI film to a fifth photoresist so as to bond each color filter and one quantum dot in an aligned mode and bond each color filter and one photoetching groove in an aligned mode, and finally peeling off the substrate to form the flexible Micro-LED.

In some embodiments of the present invention, in step S1, the epitaxial wafer includes the substrate, an N semiconductor layer, a quantum well, and a P semiconductor layer.

Further, step S2 further includes S201, stacking a protective layer on a side of the epitaxial wafer away from the substrate;

s202, spraying or spin-coating a second photoresist layer on one side, far away from the substrate, of the protective layer, and etching or developing the second photoresist layer to form a plurality of spaced photoresist segments;

s203, etching the protective layer to enable the orthographic projection of the protective layer on the plane where the second photoresist layer is located to be completely overlapped with the photoresist segment;

s204, removing the remaining second photoresist layer;

s205, etching is carried out on the N semiconductor layer, the quantum well and the P semiconductor layer to form a plurality of spaced PN junctions, and the orthographic projection of each PN junction on the plane of the protective layer is superposed with the protective layer etched in the step S203;

and S206, removing the protective layer.

Further, step S3 further includes step S301, filling a third photoresist in a gap between any two adjacent PN junctions, and performing third photolithography on the third photoresist to form a plurality of spaced photoresist columns;

s302, spraying the first conducting layer on one side, far away from the substrate, of the PN junction;

and S303, removing the photoresist columns to stack a first conductive segment on one side of each PN junction far away from the substrate.

Further, in step S4, the number of the PN junctions is equal to the number of the first conductive parts, and an orthogonal projection of each PN junction on a plane where the first conductive part is located coincides with one of the first conductive parts.

Further, step S6 further includes S601, depositing a fourth photoresist layer on a side of the passivation layer away from the flexible substrate;

s602, etching a fourth photoresist layer to form a plurality of through holes, so that the orthographic projection of each first conductive part and each second conductive part on the plane of the fourth photoresist layer covers one through hole;

s603, etching a plurality of spaced guide holes on the passivation layer through the through holes;

and S604, removing the fourth photoresist layer, arranging the second conducting layer on one side of the passivation layer away from the flexible substrate, and filling the second conducting layer in each guiding hole so as to communicate the second conducting part with each N semiconductor layer.

Further, in step S7, an orthogonal projection of each PN junction on the plane where the fifth photoresist is located at least partially covers one of the etching grooves.

Further, in step S7, the quantum dots are any one of red quantum dots and green quantum dots;

the colors of any two adjacent quantum dots are different.

Further, the color filter is any one of a red color filter, a green color filter and a blue color filter, and the color between any two adjacent color filters is different.

Further, in step S8, the color filter is any one of a red color filter, a green color filter and a blue color filter, and the color of any two adjacent color filters is different.

Further, in step S9, the red color filter is bonded to the red quantum dots, the green color filter is bonded to the green quantum dots, and the blue color filter is bonded to the empty photo-etched trench.

Furthermore, the orthographic projection of the quantum dots on the plane of the substrate is circular or regular polygon.

Furthermore, the orthographic projection of the quantum dots on the plane of the substrate is a regular hexagon.

Some embodiments of the invention also provide a flexible Micro-LED and a preparation method using the flexible Micro-LED.

Some embodiments of the invention also provide a display device comprising the flexible Micro-LED.

The embodiment of the invention has the following advantages: the substrate is stripped, the second CPI film replaces the substrate, the thickness of the Micro-LED is reduced, the flexibility of the Micro-LED is improved, and the flexible CPI film, the silver nanowire conducting layer, the flexible photoresist and other flexible materials are selected and processed to be bonded with the flexible substrate to form the flexible Micro-LED.

In order to make the aforementioned objects, features and advantages of the present invention more comprehensible and comprehensible, preferred embodiments accompanied with figures are described in detail below.

Drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required in the embodiments will be briefly described below, it should be understood that the following drawings only illustrate some embodiments of the present invention and therefore should not be considered as limiting the scope, and those skilled in the art can also obtain other related drawings based on the drawings without inventive efforts.

Fig. 1 shows a flow chart of a method for manufacturing a flexible Micro-LED according to some embodiments of the present invention;

FIG. 2 illustrates a flow chart of etching PN junction in a method for fabricating a flexible Micro-LED according to some embodiments of the present invention;

FIG. 3 illustrates a flow chart of spraying a first conductive layer in a method of fabricating a flexible Micro-LED according to some embodiments of the present invention;

FIG. 4 illustrates a flow chart for etching a passivation layer in a method for fabricating a flexible Micro-LED according to some embodiments of the present invention;

FIG. 5 is a schematic view of a view angle structure of an epitaxial wafer in a flexible Micro-LED according to some embodiments of the present invention;

FIG. 6 is a schematic diagram illustrating a view angle of an etching protection layer on an epitaxial wafer in a flexible Micro-LED according to some embodiments of the present invention;

FIG. 7 is a schematic diagram illustrating a view angle of etching an epitaxial wafer to form a PN junction in a flexible Micro-LED according to some embodiments of the present invention;

FIG. 8 is a schematic structural diagram illustrating a viewing angle of a first conductive layer sprayed on an epitaxial wafer in a flexible Micro-LED according to some embodiments of the present invention;

FIG. 9 illustrates a flexible Micro-a structure schematic diagram of a viewing angle of the epitaxial wafer in the LED with the third photoresist removed;

FIG. 10 is a schematic view of a view angle of flip-chip mounting of an epitaxial wafer on a substrate in a flexible Micro-LED according to some embodiments of the present invention;

FIG. 11 is a schematic view of the structure of FIG. 10 from a perspective where the substrate is removed;

FIG. 12 is a schematic diagram illustrating a viewing angle of an etched passivation layer on a flexible substrate in a flexible Micro-LED according to some embodiments of the present invention;

fig. 13 is a schematic diagram illustrating a viewing angle of a fifth photoresist etched on a flexible substrate in a flexible Micro-LED according to some embodiments of the present invention;

FIG. 14 is a schematic view diagram illustrating a viewing angle of a partially filled pixel in a flexible Micro-LED according to some embodiments of the present invention;

fig. 15 is a schematic diagram illustrating a viewing angle of a substrate bonded to a flexible substrate in a flexible Micro-LED according to some embodiments of the present invention;

FIG. 16 shows a schematic view of the structure of FIG. 15 from a perspective after the substrate has been peeled;

fig. 17 is a schematic diagram illustrating a viewing angle of a color filter on a substrate in a flexible Micro-LED according to some embodiments of the present invention.

Description of the main element symbols:

100-an epitaxial wafer; 200-a flexible substrate; 110-a substrate; 300-PN junction; 400-a first conductive layer; 210-a first conductive portion; 220-a second conductive portion; 500-a passivation layer; 600-a second conductive layer; 700-fifth photoresist; 800-quantum dots; 900-a substrate; 910-second CPI film; 920-color filters; a 120-N semiconductor layer; 130-quantum well; 140-P semiconductor layer; 150-a protective layer; 160-a second photoresist layer; 1000-third photoresist; 1200-a fourth photoresist layer; 1100 — first CPI film; 800 a-red quantum dots; 800 b-green quantum dots; 920 a-red color filter; 920 b-green color filter; 920 c-blue color filter.

Detailed Description

Reference will now be made in detail to embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein like or similar reference numerals refer to the same or similar elements or elements having the same or similar function throughout. The embodiments described below with reference to the accompanying drawings are illustrative only for the purpose of explaining the present invention, and are not to be construed as limiting the present invention.

It will be understood that when an element is referred to as being "secured to" another element, it can be directly on the other element or intervening elements may also be present. When an element is referred to as being "connected" to another element, it can be directly connected to the other element or intervening elements may also be present. In contrast, when an element is referred to as being "directly on" another element, there are no intervening elements present. The terms "vertical," "horizontal," "left," "right," and the like are used herein for purposes of illustration only.

In the present invention, unless otherwise explicitly stated or limited, the terms "mounted," "connected," "fixed," and the like are to be construed broadly, e.g., as being permanently connected, detachably connected, or integral; can be mechanically or electrically connected; either directly or indirectly through intervening media, either internally or in any other relationship. The specific meanings of the above terms in the present invention can be understood according to specific situations by those of ordinary skill in the art.

Furthermore, the terms "first", "second" and "first" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of the present invention, "a plurality" means two or more unless specifically defined otherwise.

Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used in the description of the templates herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used herein, the term "and/or" includes any and all combinations of one or more of the associated listed items.

As shown in fig. 1 to 17, some embodiments of the present invention provide a method for manufacturing a flexible Micro-LED, which is mainly applied to LED displays, such as LED displays. The preparation method of the flexible Micro-LED comprises the following steps:

s1, obtaining an epitaxial wafer and a flexible substrate.

The epitaxial wafer 100 includes a substrate 110, an N semiconductor layer 120, a quantum well 130, and a P semiconductor layer 140, which are sequentially stacked.

Specifically, the substrate 110 includes a buffer layer and a U-GaN layer stacked in this order, and the N semiconductor layer 120 is stacked on one side of the U-GaN layer.

In addition, in the present embodiment, the flexible substrate 200 is a CMOS flexible polymer substrate.

Note that CMOS is an abbreviation for (Complementary Metal Oxide Semiconductor). It is a technology for manufacturing large scale integrated circuit chip or a chip manufactured by the technology, and is a RAM chip which can be read and written on the computer mainboard.

And S2, etching the side of the epitaxial wafer far away from the substrate to form a plurality of spaced PN junctions.

Specifically, a plurality of spaced PN junctions are formed on the side of the epitaxial wafer away from the substrate by the second photolithography, the shape of the PN junction 300 may be a cylinder, a regular prism, or a regular polygon, and the distances between any two adjacent PN junctions 300 are equal.

It is noted that in some embodiments of the present invention, the PN junction 300 has a regular hexagonal prism shape.

Note that a plurality of spaced PN junctions 300 are simultaneously etched on the N semiconductor layer 120, the quantum well 130, and the P semiconductor layer 140. The etching mode is chemical and physical vapor deposition, photoetching, etching and other technologies to form a plurality of PN junctions of regular hexagonal prisms with equal intervals.

In addition, the etching mode can also be wet etching, the wet etching is a technology for soaking an etching material in corrosive liquid for corrosion, the etching method is pure chemical etching and has excellent selectivity, when the current thin film layer is etched, the etching can be stopped, the thin film of the other material below the etching can not be damaged, and therefore the etching precision is improved.

And S3, spraying a first conductive layer on one side of each PN junction, which is far away from the substrate.

The first conductive layer 400 is a metal nano-layer, and may be any one of a nickel nano-layer, a platinum nano-layer, or a silver nano-layer, which may be specifically set according to actual conditions.

Specifically, in the present embodiment, the first conductive layer 400 is a silver nano-layer. Wherein the nanolayer is a nanoscale layer.

In addition, the first conductive layer 400 is a silver nano-layer formed by silver nanowire connection to form electrical connection with the PN junction 300 through the first conductive layer 400.

It should be noted that an orthographic projection of each first conductive layer 400 on a plane where a side of the PN junction 300 far from the substrate 110 is located coincides with the PN junction 300.

And S4, arranging a plurality of spaced first conductive parts and a plurality of spaced second conductive parts on the flexible substrate, bonding each PN junction and one first conductive part in an alignment manner, and stripping the substrate.

The number of the first conductive portions 210 is equal to the number of the PN junctions 300, and the first conductive portions 210 and the second conductive portions 220 are layered structures, respectively.

In addition, an orthographic projection of each PN junction 300 on the plane of the first conductive parts 210 coincides with one first conductive part 210, that is, the distance between any two adjacent first conductive parts 210 is equal.

The second conductive part 220 is disposed at an edge of the flexible substrate 200 close to the first conductive part 210, and a gap is formed between the first conductive part 210 and the second conductive part 220.

It is understood that one first conductive portion 210 is bonded to one PN junction 300.

It should be noted that, based on the step S3, the first conductive layer 400 is sprayed on one side of the PN junctions 300, and it can be understood that, when the PN junctions 300 are bonded to the first conductive parts 210 disposed on the flexible substrate 200, the first conductive layer 400 coated on each PN junction 300 is bonded to one of the first conductive parts 210, so as to flip-chip the PN junctions 300 onto the flexible substrate 200, so as to form the connection between the flexible substrate 200 and the PN junctions 300.

And S5, depositing a passivation layer on one side of the flexible substrate to cover each PN junction.

In this embodiment, the deposition method is a chemical vapor deposition method. Chemical vapor deposition is a chemical technology, and the technology is mainly a method for generating a film by performing a chemical reaction on the surface of a substrate 110 by using one or more gas-phase compounds or simple substances containing film elements.

Wherein, the passivation layer 500 is an insulating passivation layer 500.

Specifically, a passivation layer 500 is deposited on one side of the flexible substrate 200 close to the PN junctions 300, so that each PN junction 300 is wrapped by the passivation layer 500 and the flexible substrate 200 to form supporting, fixing, sealing and protecting functions for the PN junctions 300.

And S6, etching guide holes in the passivation layer to leak each second conductive part and each N semiconductor layer, spraying a second conductive layer on the passivation layer, and filling the guide holes to realize PN junction conduction.

The second conductive layer 600 is sprayed on the passivation layer 500, and the guiding hole is filled with the second conductive layer 600, so that the second conductive part 220 is electrically connected with the N semiconductor layer through the second conductive layer 600, and PN junction conduction is realized.

Specifically, a plurality of spaced guide holes are formed in the passivation layer 500 by dry etching. Among them, dry etching is a technique of performing thin film etching using plasma.

Wherein the sum of the number of the first conductive parts 210 and the number of the second conductive parts 220 is not more than the number of the guide holes. Specifically, one guide Kong Lianyu is located in one second conductive part 220, and in this case, an orthogonal projection of each guide hole on the plane of flexible substrate 200 is located in one first conductive part 210 or one second conductive part 220.

In addition, a plurality of second guides Kong Lianyu may be located in the same second conductive part 220, where an orthogonal projection of each guide hole on the plane of the flexible substrate 200 is located in one first conductive part 210 or an orthogonal projection of a plurality of guide holes on the plane of the flexible substrate 200 is located in the same second conductive part 220.

It can be understood that an orthographic projection of the passivation layer 500 on the side away from the flexible substrate 200 of the first conductive part 210 covers one guiding hole, and an orthographic projection of the passivation layer 500 on the side away from the flexible substrate 200 of the second conductive part 220 covers at least one guiding hole.

Note that the purpose of etching the guide holes in the passivation layer 500 is to expose the side of the second conductive part 220 away from the flexible substrate 200 and the side of the PN junction 300 away from the flexible substrate 200, and spray the second conductive layer 600 on the side of the passivation layer 500 away from the flexible substrate 200, so that the second conductive layer 600 fills each guide hole and electrically connects the second conductive part 220 and the side of the PN junction 300 away from the flexible substrate 200 through the second conductive layer 600.

In this embodiment, the second conductive layer 600 is a silver nano-layer, and the nano-layer is applied by inkjet printing to reduce the thickness of the second conductive layer 600.

And S7, a first CPI film is laminated on one side, away from the flexible substrate, of the second conducting layer, a fifth photoresist 700 is coated on one side, away from the flexible substrate, of the first CPI film, a plurality of spaced photoresist grooves are formed in the fifth photoresist 700, and one part of the photoresist grooves is filled with one quantum dot.

Specifically, the first CPI film 1100 is laminated on the second conductive layer 600 by means of a nano-spray treatment. The first CPI film 1100 covers the second conductive layer 600 on the side away from the flexible substrate 200.

Of these, the second CPI film 910 and the first CPI film 1100 are both polyimide transparent films.

The polyimide has excellent thermal stability, higher tensile strength, outstanding high temperature resistance, radiation resistance, chemical corrosion resistance and electrical insulation performance, and stable chemical properties, and is particularly suitable for being used as a base material of a flexible printed circuit board and an insulation material of various high-temperature resistant motors and electrical appliances.

In addition, the fifth photoresist 700 completely covers the side of the first CPI film 1100 away from the flexible substrate 200.

Meanwhile, through exposure and development, a plurality of through holes are etched in the fifth photoresist 700, and a visible photoresist pattern is formed at the same time, and the position of each through hole is determined, so that quantum dots can be filled into the through holes.

In this embodiment, the fifth photoresist 700 is a flexible photoresist, a fifth photoresist 700 layer is formed on the second conductive layer 600 at a side away from the flexible substrate 200, and a plurality of spaced photoresist grooves are formed on the fifth photoresist 700 by exposing and developing.

Wherein, the developing is a lithography technique in which the photoresist in the exposed region of the positive photoresist and the non-exposed region of the negative photoresist is dissolved in a developing solution to form a three-dimensional pattern on the photoresist.

It should be noted that the number of the photo-etched grooves is equal to the number of the PN junctions 300, and each photo-etched groove faces one PN junction 300, and a part of the photo-etched grooves are filled with quantum dots. In addition, the number of the photoetching grooves is multiple, the number of the photoetching grooves can be specifically set according to actual conditions, and the photoetching grooves are arranged at intervals.

Specifically, the quantum dots are printed into the photoetching grooves in an ink-jet printing mode.

In this embodiment, the number of the photo-etched grooves is 1.5 times the number of the quantum dots. It will be appreciated that one third of the lithographic grooves are not filled with quantum dots, and that part of the lithographic grooves are empty.

The shape of the etched groove is a regular hexagon.

And S8, obtaining the substrate, laminating a second CPI film on the substrate, and attaching a plurality of spaced color filters on the side, far away from the substrate, of the second CPI film.

Specifically, a plurality of spaced color filters are formed on the side of the second CPI film away from the substrate by a first photolithography. In the present embodiment, the substrate 900 is transparent glass, and the second CPI film 910 is formed by nano-spraying on one side in the thickness direction of the substrate 900.

The nano-spraying is to spray a nano-material with high hardness and high corrosion resistance on the surfaces of a PCB and a component by using a nano-technology, and quickly form a light and thin transparent protective film (11-12 mN/m) on the surface of a workpiece to form a compact nano-coating. The nano coating does not sacrifice protection, can prevent raw material erosion caused by surface scratches, and simultaneously can prevent water, moisture, dust, oil and chemical corrosion; the nano spraying construction process is simple, has no odor, and is an environment-friendly coating with wide applicability and no environmental pollution.

In addition, the number of color filters is equal to the number of PN junctions 300, and each color filter corresponds to one etched groove.

And S9, attaching the second CPI film to a fifth photoresist so as to ensure that each color filter is bonded with one quantum dot in a contraposition mode, and finally peeling off the substrate to form the flexible Micro-LED.

Specifically, the side of the substrate 900 close to the second CPI film 910 is attached to the side of the flexible photoresist far from the flexible substrate 200.

At this time, the orthographic projection of one color filter on the plane where the quantum dots are located coincides with one quantum dot, namely the sum of the thickness of the color filter and the thickness of the quantum dot is equal to the depth of the photoetching groove, and the depth of the photoetching groove is equal to the thickness of the flexible photoresist. Note that a part of the color filter is bonded to the quantum dots, and a part of the color filter is bonded to the empty photolithography grooves.

The substrate 900 is peeled off the second CPI film 910 by laser glass technology to form the flexible Micro-LED to achieve colorized display of the flexible Micro-LED vertical structure.

As shown in fig. 5, in some embodiments of the present invention, in step S1, the epitaxial wafer 100 includes the substrate 110, the N semiconductor layer 120, the quantum well 130, and the P semiconductor layer 140, which are sequentially stacked.

The orthographic projections of the N semiconductor layer 120, the quantum well 130 and the P semiconductor layer 140 on the plane of the substrate 110 are all coincident with the substrate 110.

As shown in fig. 6 and 7, in some embodiments of the present invention, the step S2 further includes S201, stacking a protective layer 150 on a side of the epitaxial wafer 100 away from the substrate 110.

In the present embodiment, the protective layer 150 is deposited on the P semiconductor layer 140 by vapor deposition.

The protective layer 150 is a silicon dioxide layer. It is understood that the protective layer 150 is stacked on the P semiconductor layer 140 on a side away from the substrate 110.

The orthographic projection of the protective layer 150 on the P-type semiconductor layer 140 coincides with the P-type semiconductor layer 140, so that the protective layer 150 can protect the P-type semiconductor layer 140.

S202, a second photoresist layer 160 is etched on a side of the protection layer 150 away from the substrate 110, and the second photoresist layer 160 is exposed, developed and etched to form a plurality of spaced photoresist segments.

Wherein, the orthographic projection of the second photoresist layer 160 on the protection layer 150 is overlapped with the protection layer 150, and the second photoresist layer 160 is etched by exposure and development, i.e. by exposure and development, to form a plurality of spaced photoresist segments.

Note that, a predetermined pattern is formed by etching on the second photoresist layer 160 through a predetermined etching pattern on the second photoresist layer 160 and through directional exposure and development.

S203, etching on the protection layer 150 to make the orthographic projection of the protection layer 150 on the plane where the second photoresist layer 160 is located completely coincide with the photoresist segment.

Specifically, the protective layer 150 is etched based on the pattern etched on the second photoresist, wherein the etching manner on the protective layer 150 is dry etching.

And S204, removing the residual second photoresist layer.

Specifically, after the etching on the protective layer 150 is completed, the remaining second photoresist layer 160 is removed by a plasma stripping method.

It should be noted that the dry photoresist removal is also called plasma photoresist removal, the principle of which is similar to that of ion cleaning, and the photoresist is removed mainly by the reaction of oxygen nuclei and the photoresist in a plasma environment, because the basic component of the photoresist is hydrocarbon organic matter, under the action of radio frequency or microwave, oxygen is ionized into oxygen atoms and chemically reacts with the photoresist to generate carbon monoxide, carbon dioxide, water and the like, which are then pumped away by a pump in vacuum to complete the removal of the photoresist, and nitrogen or hydrogen is added into the reaction gas to improve the photoresist removal performance and enhance the removal of residues.

S205, etching on the N semiconductor layer 120, the quantum well 130 and the P semiconductor layer 140 to form a plurality of spaced PN junctions 300, wherein an orthographic projection of each PN junction 300 on a plane where the protection layer 150 is located coincides with the protection layer 150 etched in the step S203.

In this embodiment, the etching manner is wet etching.

Note that, by wet etching to form a plurality of spaced PN junctions 300 having a pillar structure, the distance between any two adjacent PN junctions 300 is equal.

S206, removing the protective layer 150.

Specifically, the protective layer 150 is dissolved by BOE (Buffered Oxide Etch) etching, so that the protective layer 150 is removed from the PN junction 300.

As shown in fig. 8 and 9, in some embodiments of the present invention, step S3 further includes S301, filling a third photoresist 1000 in a gap between any two adjacent PN junctions 300, and performing a third photolithography on the third photoresist 1000 to form a plurality of spaced photoresist columns.

Specifically, the filled third photoresist 1000 is exposed and developed to form a visible photoresist pattern, and the position of the photoresist is determined to facilitate the subsequent removal of the third photoresist 1000.

It should be noted that the height of each photoresist column is equal, that is, the vertical distance from the side of each photoresist column far from the substrate 110 to the side of each photoresist column near the substrate 110 is equal, and the height of each photoresist column is greater than the height of the PN junction 300.

The height of the PN junction 300 refers to a vertical distance from a side of the PN junction 300 away from the substrate 110 to a side of the PN junction 300 close to the substrate 110.

And S302, spraying the first conductive layer 400 on the side of the PN junction 300 far away from the substrate 110.

Wherein the first conductive layer 400 is a silver nanolayer. Specifically, the spray method is ink-jet printing.

S303, the photoresist column is removed to stack a first conductive segment on a side of each PN junction 300 away from the substrate 110.

Specifically, the photoresist column is stripped from between the PN junctions 300 by means of dry etching.

In some embodiments of the present invention, in step S4, the number of the PN junctions 300 is equal to the number of the first conductive parts 210, and an orthogonal projection of each PN junction 300 on a plane where the first conductive part 210 is located coincides with one of the first conductive parts 210.

As shown in fig. 4 and 12, in some embodiments of the present invention, step S6 further includes S601, depositing a fourth photoresist layer 1200 on the side of the passivation layer 500 away from the flexible substrate 200.

Specifically, the fourth photoresist layer 1200 is formed on the passivation layer 500 by spraying, and the fourth photoresist layer 1200 completely covers a side of the passivation layer 500 away from the flexible substrate 200.

S602, a plurality of through holes are formed on the fourth photoresist layer 1200 by etching, so that the orthogonal projection of each first conductive portion 210 and each second conductive portion 220 on the plane of the fourth photoresist layer 1200 covers one through hole.

Specifically, a plurality of through holes are formed on the fourth photoresist by means of fourth photolithography through exposure and development.

Wherein the sum of the number of the first conductive parts 210 and the number of the second conductive parts 220 is not more than the number of the guide holes.

The first conductive portion 210 is a P-PAD, and the second conductive portion 220 is an N-PAD.

S603, etching a plurality of spaced guiding holes on the passivation layer 500 through the through holes.

Specifically, etching is performed on the passivation layer 500 by dry etching to form a plurality of spaced guide holes on the passivation layer 500.

S604, removing the fourth photoresist layer 1200, disposing the second conductive layer 600 on a side of the passivation layer 500 away from the flexible substrate 200, and filling the second conductive layer 600 in each of the guiding holes to connect the second conductive portion and each of the N semiconductor layers.

Specifically, the fourth photoresist is removed by a plasma method, the second conductive layer 600 is printed on the side of the passivation layer 500 away from the flexible substrate 200 by means of inkjet printing, and the second conductive layer 600 is filled in each of the guiding holes, so as to form the conductive pillars in the guiding holes.

The second conductive layer 600 is a silver nano-layer, and the second conductive part 220 is electrically connected to the PN junction 300 through the second conductive layer 600.

As shown in fig. 13 to 16, in some embodiments of the invention, in step S7, an orthogonal projection of each PN junction 300 on a plane where the fifth photoresist 700 is located at least partially covers one of the etched grooves.

It is understood that the orthographic projection of each PN junction 300 on the plane of the fifth photoresist 700 covers one of the etched grooves. Or the orthographic projection of each PN junction 300 on the plane where the fifth photoresist 700 is located covers one photoetching groove.

Optionally, an orthogonal projection of each PN junction 300 on a plane where the fifth photoresist 700 is located in one of the photolithography grooves. Can be specifically set according to actual conditions.

It should be noted that, in some embodiments of the present invention, the quantum dot is any one of a red quantum dot 800a and a green quantum dot 800b, and the color of any two adjacent quantum dots is different.

It should be noted that the number of the red quantum dots 800a is equal to the number of the green quantum dots 800 b.

As shown in fig. 15 to 17, in some embodiments of the present invention, in step S8, the color filter is any one of a red color filter 920a, a green color filter 920b, and a blue color filter 920c, and colors between any two adjacent color filters are different.

The number of the red color filters 920a is equal to the number of the red quantum dots, the number of the green color filters 920b is equal to the number of the green quantum dots, and the number of the blue color filters 920c is equal to the number of the blank photolithography grooves.

Specifically, the red color filter 920a is bonded to the red quantum dot 800a, the green color filter 920b is bonded to the green quantum dot 800b, and the blue color filter 920c is bonded to the blank photo-etched trench.

In addition, the orthographic projections of the quantum dots and the color filter on the plane of the flexible substrate 200 are respectively circular or regular polygon, and can be specifically set according to actual conditions.

In some embodiments of the present invention, the orthographic projections of the quantum dots and the color filter on the plane of the flexible substrate 200 are both regular hexagons, that is, the PN junction 300 is regular hexagonal prism shaped.

Some embodiments of the invention also provide a flexible Micro-LED, which is manufactured by using the method for manufacturing the flexible Micro-LED according to any one of the embodiments.

Some embodiments of the present invention also provide a display device comprising at least the flexible Micro-LED as described in any one of the embodiments above.

In all examples shown and described herein, any particular value should be construed as merely exemplary, and not as a limitation, and thus other examples of example embodiments may have different values.

It should be noted that: like reference numbers and letters refer to like items in the following figures, and thus, once an item is defined in one figure, it need not be further defined and explained in subsequent figures.

The above-mentioned embodiments only express several embodiments of the present invention, and the description thereof is specific and detailed, but not to be construed as limiting the scope of the present invention. It should be noted that, for a person skilled in the art, several variations and modifications can be made without departing from the inventive concept, which falls within the scope of the present invention.

Claims

1. A preparation method of a flexible Micro-LED is characterized by comprising the following steps:

s1, obtaining an epitaxial wafer and a flexible substrate;

s3, spraying a first conductive layer on one side of each PN junction, which is far away from the substrate;

s7, laminating a first CPI film on one side, far away from the substrate, of the second conducting layer, coating a fifth photoresist on one side, far away from the substrate, of the first CPI film, etching a plurality of spaced photoetching grooves on the fifth photoresist, and filling quantum dots in one part of the photoetching grooves;

and S9, attaching the second CPI film to the fifth photoresist so that each color filter is in alignment bonding with one photoetching groove, and finally peeling off the substrate to form the flexible Micro-LED.

2. The method of claim 1, wherein in step S1, the epitaxial wafer includes the substrate, an N semiconductor layer, a quantum well, and a P semiconductor layer.

3. The method for preparing a flexible Micro-LED according to claim 2, wherein step S2 further comprises S201, laminating a protective layer on the side of the epitaxial wafer away from the substrate;

s204, removing the remaining second photoresist layer;

s206, removing the protective layer.

4. The method for preparing a flexible Micro-LED according to claim 1, wherein the step S3 further includes S301, filling a third photoresist in a gap between any two adjacent PN junctions, and performing a third photolithography on the third photoresist to form a plurality of spaced photoresist columns;

5. The method for preparing a flexible Micro-LED as claimed in claim 1, wherein in step S4, the number of said PN junctions is equal to the number of said first conductive portions, and the orthographic projection of each said PN junction on the plane of said first conductive portion coincides with one said first conductive portion.

6. The method for preparing a flexible Micro-LED according to claim 1, wherein step S6 further includes S601, depositing a fourth photoresist layer on a side of the passivation layer away from the flexible substrate;

s603, etching and forming a plurality of spaced guide holes on the passivation layer through the through holes;

7. The method as recited in claim 1, wherein in step S7, an orthographic projection of each PN junction on a plane of the fifth photoresist at least partially covers one of the etched grooves.

8. The method for preparing a flexible Micro-LED according to claim 1, wherein in step S7, the quantum dots are any one of red quantum dots and green quantum dots;

the colors of any two adjacent quantum dots are different.

9. The method for preparing a flexible Micro-LED according to claim 8, wherein in step S8, the color filter is any one of a red color filter, a green color filter and a blue color filter, and the color of any two adjacent color filters is different.

10. The method of claim 9, wherein in step S9, a red color filter is bonded to the red quantum dots, a green color filter is bonded to the green quantum dots, and a blue color filter is bonded to the empty photo-etched trench.

11. The method for preparing a flexible Micro-LED according to claim 1, wherein the orthographic projection of the quantum dots on the plane of the substrate is circular or regular polygon.

12. The method of claim 11, wherein an orthographic projection of the quantum dots on a plane of the substrate is a regular hexagon.

13. A flexible Micro-LED, characterized in that a method of manufacturing a flexible Micro-LED according to any one of claims 1 to 12 is used.

14. A display device comprising the flexible Micro-LED of claim 13.