Micro LED light isolation structure, preparation method thereof and Micro LED full-color conversion film

Abstract

The invention relates to the technical field of semiconductor display, in particular to a Micro LED light isolation structure, a preparation method of the Micro LED light isolation structure and a Micro LED full-color conversion film. The preparation method of the Micro LED light isolation structure comprises the following steps: performing deposition treatment on a target substrate through a preset physical vapor deposition process to obtain a seed layer with a first thickness; photoresist is spin-coated to the seed layer, and a target pattern formed by the photoresist is obtained through photolithography process processing; processing the seed layer and the target pattern through an electrochemical deposition process, and forming a first metal coating with a second thickness on the seed layer; and stripping the photoresist on the target substrate to obtain a target optical isolation structure. According to the target light isolation structure, the problem of light crosstalk between Micro LED pixel points is effectively reduced, light rays can be reflected on the side wall of the metal grating and then emitted out through the characteristic that the side wall of the metal grating absorbs little visible light, and then the light emitting efficiency of the pixel points is improved.

Description

Technical Field

[0001] The present application relates to the field of semiconductor display technology, and in particular to a Micro LED light isolation structure and a preparation method thereof, and a Micro LED full-color conversion film. Background Art

[0002] Micro LED (Micro Light Emitting Eiode) is an emerging solid-state light-emitting and display technology, that is, a micro-light-emitting diode, which makes the traditional light-emitting diode as small as tens of microns or even a few microns. It also has the advantages of high brightness, high contrast, low power consumption and high response speed. It is the best technical solution for realizing ultra-high-resolution full-color display screens. In actual application, Micro LED needs to further solve the full-color display problem (that is, full-color display capability) before it can be more widely used. The traditional technical solution to solve the full-color display problem of Micro LED is to use three-primary color Micro LED chip transfer assembly, or use blue light Micro LED to excite quantum dot materials. However, the mass transfer technology of Micro LED still needs to overcome many problems such as transfer efficiency and yield, which also makes the use of monochrome Micro LED backlight, plus red and green color conversion film, become an optional Micro LED full-color solution. However, with the improvement of display requirements, the resolution requirements of Micro LED display panels are getting higher and higher. The pixel size and spacing of Micro LED are gradually shrinking to hundreds of microns, tens of microns, or even below 5 microns, making the optical crosstalk between pixels more serious. Each Micro LED light source will diffuse to adjacent pixels, causing other pixels to emit light. In addition, there is also a problem of lateral optical crosstalk between the pixels of the color conversion film. The optical crosstalk will lead to a series of problems such as reduced color purity and contrast of the display panel.

[0003] The current traditional technology to solve the optical crosstalk problem of Micro LED is to use black photoresist as an optical blocking layer between pixels. However, the defect is that most black photoresists are not thick enough to match the thickness of the color conversion film pixels, and thus cannot effectively fill the blank areas between pixels. Although a few black photoresists can achieve a larger thickness, the spacing between pixels is compressed to 5 microns or even less than 5 microns, making it impossible for existing black photoresists to completely block the optical crosstalk between pixels. Summary of the invention

[0004] The main technical problem solved by the implementation methods of the present application is that the optical crosstalk between Micro LED pixels causes the full-color capability of the display panel to be reduced.

[0005] In order to solve the above technical problems, a technical solution adopted in the implementation mode of the present application is: to provide a method for preparing a MicroLED light isolation structure, comprising: performing a deposition process on a target substrate through a preset physical vapor deposition process to obtain a seed layer of a first thickness; spin-coating photoresist to the seed layer, and obtaining a target pattern formed by the photoresist through a photolithography process; processing the seed layer and the target pattern through an electrochemical deposition process to form a first metal coating of a second thickness on the seed layer; and stripping the photoresist on the target substrate to obtain a target light isolation structure.

[0006] Optionally, the physical vapor deposition process is magnetron sputtering.

[0007] Optionally, the step of performing a deposition process on the target substrate through a preset physical vapor deposition process to obtain a seed layer of a first thickness includes: depositing a second metal of a third thickness as a first metal layer on the target substrate through a preset physical vapor deposition process; and depositing a first metal of a fourth thickness on the first metal layer through a preset physical vapor deposition process to obtain a seed layer consisting of the first metal layer and the second metal layer.

[0008] Optionally, the second metal is titanium, and the third thickness of the first metal layer is 30 to 70 nanometers.

[0009] Optionally, the second metal layer of the seed layer has a thickness of 800 to 1500 nanometers.

[0010] Optionally, the second thickness of the first metal coating formed on the seed layer is 8 to 20 micrometers.

[0011] Optionally, the electrochemical deposition process is an electroplating process.

[0012] Optionally, the first metal is copper, and the first metal coating is a copper coating processed by an electroplating process.

[0013] In order to solve the above technical problems, another technical solution adopted in the embodiment of the present application is: to provide a Micro LED light isolation structure, and the Micro LED light isolation structure is prepared by the Micro LED light isolation structure preparation method as described above.

[0014] In order to solve the above technical problems, another technical solution adopted in the implementation mode of the present application is: to provide a MicroLED full-color conversion film, wherein the Micro LED full-color conversion film is obtained by a MicroLED light isolation structure filled with color conversion material and filter material, and the Micro LED light isolation structure is the Micro LED light isolation structure as described above.

[0015] Different from the related art, the present application performs deposition processing on a target substrate through a preset physical vapor deposition process to obtain a seed layer of a first thickness; spin-coats photoresist to the seed layer, and obtains a target pattern formed by the photoresist through a photolithography process; processes the seed layer and the target pattern through an electrochemical deposition process to form a first metal coating of a second thickness on the seed layer; strips off the photoresist on the target substrate to obtain a target light isolation structure, which not only effectively reduces the optical crosstalk problem between Micro LED pixels, but also allows the light to be emitted after being reflected on the side walls of the metal grid through the characteristic that the metal grid side walls absorb less visible light, thereby improving the light output efficiency of the pixel points. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] One or more embodiments are exemplarily described by corresponding drawings, which do not constitute limitations on the embodiments. Elements with the same reference numerals in the drawings represent similar elements, and the figures in the drawings do not constitute proportional limitations unless otherwise stated.

[0017] Figure 1 It is a schematic diagram of the process of preparing a Micro LED light isolation structure provided in an embodiment of the present application;

[0018] Figure 2 Schematic diagram of the sputtering process of the method for preparing the Micro LED light isolation structure provided in an embodiment of the present application;

[0019] Figure 3 It is a schematic diagram of the photolithography process of the method for preparing the Micro LED light isolation structure provided in an embodiment of the present application;

[0020] Figure 4 Schematic diagram of the electroplating process of the method for preparing the Micro LED light isolation structure provided in an embodiment of the present application;

[0021] Figure 5 Schematic diagram of the degumming process of the method for preparing the Micro LED light isolation structure provided in an embodiment of the present application;

[0022] Figure 6 is a top view of the Micro LED light isolation structure provided in an embodiment of the present application;

[0023] Figure 7 This is a three-dimensional view of the Micro LED light isolation structure provided in an embodiment of the present application. DETAILED DESCRIPTION

[0024] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0025] Reference to "embodiments" herein means that a particular feature, structure, or characteristic described in conjunction with the embodiments may be included in at least one embodiment of the present invention. The appearance of the phrase in various places in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment that is mutually exclusive with other embodiments. It is explicitly and implicitly understood by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0026] The experimental methods in the following examples are conventional methods unless otherwise specified, and the materials and reagents used are all commercially available unless otherwise specified.

[0027] Micro LED (Micro Light Emitting Diode) is an emerging solid-state lighting and display technology, and is regarded as a new generation of display technology after LCD and OLED. Unlike traditional LED technology, Micro LED is composed of a large number of micro LED chip arrays. The size of each LED chip can be tens of microns, several microns or even nanometers. Each micro LED chip can emit red, green and blue primary colors of light separately, and can be mixed into any color by color mixing, making Micro LED have the advantages of high brightness, high contrast, low power consumption and high response speed. It can be used in large-size display screens, virtual reality and augmented reality devices, smart watches, smart phones and car displays to provide a better visual experience. Just as Micro LED display panels need to be composed of red, green and blue primary color Micro LED chip arrays, any desired color can be mixed by precisely controlling the brightness and ratio of each Micro LED, which puts extremely high demands on the full color of Micro LED.

[0028] The traditional mainstream technical solution of Micro LED is to use three-primary color Micro LED chip transfer and assembly and use blue light Micro LED to excite quantum dot materials. The technical solution of using three-primary color Micro LED chip transfer and splicing involves the mass transfer technology of Micro LED. With the help of a special flexible mold, thousands or even millions of Micro LED chips are kept in an orderly arrangement from the substrate wafer and collectively transferred to the target substrate at one time. However, the MicroLED mass transfer technology still needs to overcome many problems such as transfer efficiency, yield and reliability. Therefore, the use of monochrome MicroLED backlight plus red and green color conversion film has become an optional full-color solution. At present, with the increase in display demand, the resolution of Micro LED display panels needs to be higher and higher. The pixel size and spacing of Micro LED chips are gradually shrinking to tens of microns, or even below 5 microns, making the optical crosstalk between pixels more serious.

[0029] The optical crosstalk phenomenon will cause the light emission of one pixel on the Micro LED chip to affect the light emission of multiple other pixels around it. Each Micro LED light source will spread to adjacent pixels, causing the light emission of other pixels, and there is also a lateral optical crosstalk problem between the color conversion film pixels. The optical crosstalk phenomenon will cause a series of problems such as reduced color purity and reduced contrast of the Micro LED display panel.

[0030] The traditional technical solution to the problem of optical crosstalk is to use black photoresist as an optical barrier between pixels, but the problem that still exists is that most black photoresists are not thick enough to match the thickness of the color conversion film pixels and cannot effectively fill the blank areas between pixels. Although there are a few black photoresists that can reach a larger thickness and match the thickness of the color conversion film pixels, the black photoresist cannot completely block the optical crosstalk phenomenon between pixels because the spacing between pixels is compressed to 5 microns or even less than 5 microns.

[0031] The defects existing in the above-mentioned solutions are the results obtained by the applicant after practice and careful research. Therefore, the discovery process of the above-mentioned problems and the solutions proposed by this application for the above-mentioned problems below should be the contributions made by the applicant to this application during the disclosure process of this application.

[0032] To facilitate understanding of this embodiment, a method for preparing a Micro LED light isolation structure disclosed in the embodiment of the present application is first described in detail. Figure 1 As shown, the method for preparing the Micro LED light isolation structure includes the following steps:

[0033] S101 , performing a deposition process on a target substrate through a preset physical vapor deposition process to obtain a seed layer of a first thickness.

[0034] Among them, physical vapor deposition (PVD) is an industrial manufacturing process, a type of coating technology, which mainly uses physical methods to heat or excite materials to deposit thin films. It is mostly used in the surface treatment of cutting tools and various molds, as well as the manufacturing process of semiconductor devices, including but not limited to: evaporation (Evaporative PVD), sputtering (Sputtering PVD) and ion plating (Ion Plating PAPVD). Evaporation includes: resistive evaporation (Resistive PVD), inductive evaporation (Inductive PVD), laser evaporation (Laser PVD), etc. Sputtering includes: bipolar sputtering, magnetron sputtering, ion beam sputtering, etc. Ion plating includes: radio frequency ion plating, pulsed plasma ion plating, etc.

[0035] As a preferred embodiment, the step of performing a deposition process on the target substrate by a preset physical vapor deposition process to obtain a seed layer of the first thickness specifically includes:

[0036] S1011 , depositing a second metal with a third thickness as a first metal layer on the target substrate through a preset physical vapor deposition process.

[0037] As a preferred implementation, the physical vapor deposition process may be specifically selected as a magnetron sputtering method.

[0038] As an example, the second metal may be titanium metal, and the third thickness of the sputtered first metal layer is in a range of 30 to 70 nanometers.

[0039] S1012: Deposit a first metal with a fourth thickness as a second metal layer on the first metal layer through a preset physical vapor deposition process to obtain a seed layer consisting of the first metal layer and the second metal layer.

[0040] As another example, the second metal layer sputtered on the seed layer may be copper, and the fourth thickness of the second metal layer sputtered is in a range of 800 to 1500 nanometers.

[0041] Furthermore, the applicant discovered through experiments that when a metal material is sputtered onto a substrate (generally a non-metallic material such as a silicon wafer) by magnetron sputtering, the metal material of the first metal layer contained in the seed layer (for example, titanium) can adhere well to the substrate, while another part of the metal material (for example, copper) will easily fall off the substrate. Therefore, the metal material of the first metal layer is first sputtered onto the substrate by magnetron sputtering, and then another metal material is sputtered onto the first metal layer, so that the first metal layer plays a "bonding" role between the substrate and the main metal material.

[0042] As a specific example, Figure 2 As shown, Figure 2 It is a schematic diagram of the sputtering process of the Micro LED light isolation structure preparation method provided in an embodiment of the present application. Through the above-mentioned magnetron sputtering process, a metal titanium layer 202 with a thickness of 30 to 70 nanometers is first sputtered on the substrate 10, and the metal titanium layer 202 constitutes the above-mentioned first metal layer. Then, a metal copper layer 201 with a thickness of 800 to 1500 nanometers is sputtered on the metal titanium layer 202 of the first metal layer. The metal titanium layer 202 and the metal copper layer 201 together constitute the above-mentioned seed layer.

[0043] Furthermore, the titanium metal material can not only produce good adhesion to the substrate, but also the work function of the copper metal material and the titanium metal material is relatively similar, so the copper metal material and the titanium metal material can also produce a better adsorption effect.

[0044] The work function of a metal refers to the minimum energy barrier that a free electron needs to overcome to escape from the inside of the metal into the vacuum. It is an important physical parameter that describes the electron escape characteristics of the metal surface. Since the free electrons in the metal are spread throughout the metal crystal, an electron gas similar to the Fermi gas is formed. However, due to the electrostatic force, there is a barrier on the metal surface that prevents the electrons from escaping from the vacuum. The work function refers to the minimum energy required to overcome this barrier. The value of the work function is equal to the difference between the Fermi level inside the metal and the vacuum level. The unit is electron volt (eV). The size of the metal work function not only affects the metal's electron emission performance, but also is related to the adsorption, corrosion and chemical reactivity of the metal surface. The work functions of titanium and copper are relatively close, and the surfaces between the two can produce better adsorption. Therefore, titanium metal material is used as the above-mentioned first metal layer, and then copper metal material is sputtered on titanium metal by magnetron sputtering.

[0045] S102, spin-coating photoresist onto the seed layer, and performing photolithography to obtain a target pattern formed by the photoresist.

[0046] Specifically, a pre-prepared photoresist is first coated on the seed layer of the pre-processed substrate, and then alignment, exposure, photolithography, development and other steps are performed through a pre-selected photolithography process to finally obtain a target pattern consistent with the designed pattern. The specific photolithography process details are not repeated here.

[0047] As a specific example, Figure 3 As shown, Figure 3 Schematic diagram of the photolithography process of the method for preparing the Micro LED light isolation structure provided in an embodiment of the present application, wherein a preset target pattern 30 is formed on the seed layer (composed of a metal titanium layer 202 and a metal copper layer 201) on the target substrate 10 through a photolithography process.

[0048] S103 , processing the seed layer and the target pattern through an electrochemical deposition process to form a first metal coating with a second thickness on the seed layer.

[0049] Among them, the electrochemical deposition process is a process that uses electrochemical methods to deposit metals or alloys on the electrode surface. It uses the metal ions in the electrolyte solution to undergo a reduction reaction on the electrode surface, reducing the metal ions to metal atoms and depositing them on the electrode surface. It is an important surface treatment technology and is widely used in technical fields such as electronic device manufacturing, thin film coating and material modification.

[0050] As a preferred embodiment, the seed layer may be treated by electrochemical deposition through an electroplating process. Compared with the magnetron sputtering process, the electroplating process can further improve the processing speed, and the electroplating process can further reduce the cost compared with the magnetron sputtering process.

[0051] As another preferred implementation, copper metal material is selected as the first metal, and the first metal coating is a copper coating treated by an electroplating process. Meanwhile, copper is also a relatively mature raw material for electroplating process.

[0052] As another preferred embodiment, the second thickness of the copper metal material electroplated onto the seed layer by the electroplating process is 8 to 20 micrometers.

[0053] As a specific example, Figure 4 As shown, Figure 4 It is a schematic diagram of the electroplating process of the Micro LED light isolation structure preparation method provided in an embodiment of the present application. After obtaining the target pattern 30, metal copper is electroplated onto the metal copper layer 201 of the above-mentioned seed layer through an electroplating process. The thickness of the metal copper layer 40 on the metal copper layer 201 is 8 to 20 microns.

[0054] S104, stripping the photoresist on the target substrate to obtain a target light isolation structure.

[0055] Among them, lift off refers to peeling off the photoresist together with the excess metal material deposited thereon from the substrate (in the present embodiment of the application, from the conductive layer on the substrate), leaving only the desired metal pattern (in the present embodiment of the application, the target light isolation structure).

[0056] As a specific example, Figure 5 As shown, Figure 5 1 is a schematic diagram of the degumming process of the Micro LED optical isolation structure preparation method provided in an embodiment of the present application, that is, the process of stripping the target pattern 30 formed by the photoresist on the metal copper layer 201 of the conductive layer, that is, the target grating isolation structure finally obtained only has the conductive layer composed of the substrate 10, the sputtered titanium metal seed layer 202 and the sputtered metal copper layer 201, and the metal copper layer 40 electroplated on the conductive layer.

[0057] The method for preparing a Micro LED light isolation structure proposed in the embodiment of the present application performs a deposition process on a target substrate through a preset physical vapor deposition process to obtain a seed layer of a first thickness; spin-coats a photoresist onto the seed layer, and obtains a target pattern formed by the photoresist through a photolithography process; processes the seed layer and the target pattern through an electrochemical deposition process to form a first metal coating of a second thickness on the seed layer; and strips off the photoresist on the target substrate to obtain a target light isolation structure, which not only effectively reduces the optical crosstalk problem between Micro LED pixels, but also allows light to be emitted after being reflected on the side walls of the metal grid through the characteristic that the side walls of the metal grid absorb less visible light, thereby improving the light output efficiency of the pixels.

[0058] The embodiment of the present application also provides a Micro LED light isolation structure, which is prepared by the aforementioned Micro LED light isolation structure preparation method.

[0059] As a concrete example, see Figure 6 and Figure 7 , Figure 6 is a top view of the MicroLED light isolation structure provided in an embodiment of the present application, Figure 7 3D is a three-dimensional view of the Micro LED light isolation structure provided in an embodiment of the present application. On the surface of the Micro LED is a metal copper layer 40 that is finally electroplated, and a metal grid 50 formed by the metal copper layer 40 and the metal copper layer 201. The metal grid 50 can be used to fill color conversion materials and / or filter materials.

[0060] The embodiment of the present application also provides a Micro LED full-color conversion film, which is obtained by the aforementioned Micro LED light isolation structure filled with color conversion material and filter material.

[0061] As a preferred implementation, after obtaining the aforementioned Micro LED light isolation structure, the color conversion material and the filter material are filled into the metal grid of the Micro LED light isolation structure using photolithography and inkjet printing technology to form the aforementioned Micro LED full-color conversion film.

[0062] The embodiment of the present application also provides a Micro LED display panel, which includes the aforementioned Micro LED full-color conversion film.

[0063] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them. Under the concept of the present application, the technical features in the above embodiments or different embodiments can also be combined, the steps can be implemented in any order, and there are many other changes in different aspects of the present application as described above, which are not provided in detail for the sake of simplicity. Although the present application has been described in detail with reference to the aforementioned embodiments, a person of ordinary skill in the art should understand that the technical solutions described in the aforementioned embodiments can still be modified, or some of the technical features can be replaced by equivalents. These modifications or replacements do not deviate the essence of the corresponding technical solutions from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A method for preparing a Micro LED light isolation structure, characterized in that: include: Performing a deposition process on a target substrate by a preset physical vapor deposition process to obtain a seed layer of a first thickness; Spin-coating a photoresist onto the seed layer, and obtaining a target pattern formed by the photoresist through a photolithography process; Processing the seed layer and the target pattern by an electrochemical deposition process to form a first metal coating of a second thickness on the seed layer; The photoresist on the target substrate is stripped off to obtain a target light isolation structure.

2. The method for preparing a Micro LED light isolation structure according to claim 1, characterized in that: The physical vapor deposition process is magnetron sputtering.

3. The method for preparing a Micro LED light isolation structure according to claim 1, characterized in that: The step of performing a deposition process on the target substrate by a preset physical vapor deposition process to obtain a seed layer of a first thickness comprises: Depositing a second metal with a third thickness as a first metal layer on the target substrate by a preset physical vapor deposition process; A first metal with a fourth thickness is deposited on the first metal layer as a second metal layer through a preset physical vapor deposition process to obtain a seed layer consisting of the first metal layer and the second metal layer.

4. The method for preparing a Micro LED light isolation structure according to claim 3, characterized in that: The second metal is titanium, and the third thickness of the first metal layer is 30 to 70 nanometers.

5. The method for preparing a Micro LED light isolation structure according to claim 3, characterized in that: The thickness of the second metal layer of the seed layer is 800 to 1500 nanometers.

6. The method for preparing a Micro LED light isolation structure according to claim 1, characterized in that: The second thickness of the first metal coating layer formed on the seed layer is 8 to 20 micrometers.

7. The method for preparing a Micro LED light isolation structure according to claim 1, characterized in that: The electrochemical deposition process is an electroplating process.

8. The method for preparing a Micro LED light isolation structure according to claim 1, characterized in that: The first metal is copper, and the first metal coating is a copper coating processed by an electroplating process.

9. A Micro LED light isolation structure, characterized in that: The Micro LED light isolation structure is prepared by the Micro LED light isolation structure preparation method according to any one of claims 1 to 8.

10. A Micro LED full-color conversion film, characterized in that: The Micro LED full-color conversion film is obtained by a Micro LED light isolation structure filled with color conversion material and filter material, and the Micro LED light isolation structure is the Micro LED light isolation structure according to claim 9.

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