CN115000279A - Quantum dot color conversion layer microarray and preparation method and application thereof - Google Patents

Abstract

The quantum dot color conversion layer microarray and its preparation method and application disclosed in the present invention can make the quantum dots uniformly dispersed by preparing the nanopore structure as the quantum dot bearing layer and filling the light blocking material in the pixel channel, and effectively improve the light intensity and light intensity. Purity; the preparation method of the present invention has simple process flow, high operability and wide application range; a full-color display prepared by combining the quantum dot color conversion layer microarray prepared by the present invention and the GaN-based blue light Micro-LED microarray The device avoids the technical bottleneck of the mass transfer of red and green, reduces the production cost and improves the production efficiency.

Description

Quantum dot color conversion layer microarray and preparation method and application thereof

technical field

The invention belongs to the technical field of Micro LED display, and in particular relates to a quantum dot color conversion layer microarray. The invention also relates to a preparation method of a quantum dot color conversion layer microarray. The invention further relates to the application of a quantum dot color conversion layer microarray.

Background technique

Micro LED is regarded as the next generation display technology to replace LCD and OLED display. Based on the high efficiency of LED, Micro LED has the advantages of high pixel, high contrast, self-illumination, low energy consumption and long life. However, the huge challenge in the manufacturing of Micro LED display technology is still the massive transfer process, how to prepare tiny red, green and blue Micro LED chips, and how to quickly and accurately place the three-color chips on the driver panel It restricts the mass production of Micro LED. In order to avoid the process bottleneck of mass transfer, many research reports currently focus on the use of quantum dot materials to prepare color conversion layers to achieve full-color display of Micro LEDs, such as deposition of quantum dot films, quantum dot photoresist and other schemes, but all There are problems such as poor dispersion uniformity of quantum dots and low purity and intensity of red and green light.

SUMMARY OF THE INVENTION

The purpose of the present invention is to provide a quantum dot color conversion layer microarray, which solves the problems of poor dispersion uniformity of quantum dots and low purity and intensity of red and green light in the existing solution.

Another object of the present invention is to provide a method for preparing a quantum dot color conversion layer microarray, which has a simple process flow, high operability, and is applicable to the preparation of devices of various sizes.

Another object of the present invention is to provide an application of a quantum dot color conversion layer microarray, which is used in a full-color Micro LED device, and has broad application prospects.

The first technical solution adopted in the present invention is: a quantum dot color conversion layer microarray, including a GaN epitaxial layer, a grid-shaped channel is opened on the GaN epitaxial layer, and a single GaN epitaxial layer pixel formed by the grid-shaped channel is separated Nano-hole structures are opened in the dot regions, and red quantum dots and green quantum dots are respectively injected into the nano-hole structures in two adjacent three GaN epitaxial layer pixel dot regions.

The first technical solution of the present invention is also characterized in that,

The nano-hole structure is a plurality of elongated holes vertically opened in the pixel area of a single GaN epitaxial layer.

The grid-shaped channel is filled with black epoxy resin to prevent optical crosstalk between GaN pixels.

A water-oxygen barrier layer is arranged above the GaN epitaxial layer to protect the stability of the quantum dot material in the nanopore structure.

The GaN epitaxial layer is grown on a Si or sapphire substrate. The bottom-up structure of the GaN epitaxial layer is a buffer layer, an intrinsic GaN layer, a first N-type GaN layer, and a second N-type GaN layer. The bottom end of the channel is opened To the first N-type GaN layer, the opening depth of the channel cannot exceed the depth of the first N-type GaN layer, and a thin first N-type GaN layer needs to be reserved as the current conduction layer of the electrochemical etching process.

The second technical solution adopted by the present invention is: a preparation method of a quantum dot color conversion layer microarray, comprising the following steps:

Step 1. A silicon film layer is grown on the GaN epitaxial layer of the Si or sapphire substrate by plasma enhanced chemical vapor deposition (PECVD). The GaN epitaxial layer is prepared by metal organic compound chemical vapor deposition (MOCVD). The bottom-up structure of the GaN epitaxial layer is a buffer layer, an intrinsic GaN layer, a first N-type GaN layer, and a second N-type GaN layer. The thickness of the structural layer is determined according to the specific process design;

Step 2. Spin-coat negative photoresist on the silicon film layer of step 1, the photomask pattern is a pixel point microarray pattern, and the pixel point size and spacing can be designed according to the matching Micro LED microarray pixel point size, A photoresist microarray is obtained after exposure and development using an ultraviolet contact exposure machine;

Step 3. Use vacuum electron beam evaporation equipment (Ebeam) to evaporate a metal Cr film as a hard mask on the photoresist microarray in step 2, and the thickness of the metal Cr film is set according to the depth of etching GaN; After the metal Cr film layer is plated, a negative metal stripping process is performed, and the Cr metal in the pixel spacing is stripped and removed, and a metal Cr microarray is formed after stripping;

Step 4, using the metal Cr microarray in step 3 as a hard mask, using inductively coupled plasma etching (ICP) to etch the silicon film layer to form a metal Cr and silicon composite microarray;

Step 5. Using the metal Cr and silicon composite microarray of step 4 as a hard mask, ICP is used to etch the GaN epitaxial layer, and the etching depth runs through the entire second N-type GaN layer from top to bottom in sequence, and etch to the first N-type GaN layer. stop at the N-type GaN layer to form a GaN microarray; here the first N-type GaN layer has a thin layer thickness remaining, which is used as a current conduction layer for the subsequent electrochemical etching process;

Step 6. Spin-coat black epoxy resin glue in the GaN microarray in Step 5 to ensure that the black epoxy resin glue can completely infiltrate into the channel of the GaN microarray, and cure the black epoxy resin glue;

Step 7, using chemical mechanical polishing (CMP) to perform a thinning and polishing process of black epoxy resin glue on the GaN microarray in step 6, polishing until the metal Cr film layer and the silicon film layer are completely removed and the second N-type GaN layer is exposed;

Step 8. Use an anodizing machine to perform electrochemical corrosion on the GaN microarray in step 7. The corrosion solution can be selected from oxalic acid solution, the oxalic acid concentration can be selected from 10% to 80%, and the corrosion voltage can be selected from 1 to 50V. According to the concentration of the corrosion solution, Parameters such as corrosion voltage and corrosion time determine the corrosion depth of the GaN nanopore structure, and an approximately vertical GaN nanopore structure microarray is obtained after etching;

Step 9. Spin-coat positive photoresist on the surface of the GaN nanoporous structure microarray, use ultraviolet lithography to first define the red color conversion area on the GaN nanoporous structure microarray, and use spraying equipment to inject red quantum dots into the red color conversion area. In the nanopore structure, the green color conversion area is defined and green quantum dots are injected, finally forming an RGB array;

Step 10, use magnetron sputtering (Sputter) to sputter and deposit a water-oxygen barrier layer on the RGB array in step 9 to protect the stability of the quantum dot material in the nanoporous structure, and the thickness of the water-oxygen barrier layer is determined according to the protection effect.

The second technical solution of the present invention is also characterized in that:

In step 6, vacuum infiltration and curing are as follows: vacuumize the spin-coated GaN microarray in a vacuum device for 10-20 minutes, and the vacuum degree can be selected in the range of 0.01-0.1Pa to ensure that the black epoxy resin can better infiltrate into the channel of the GaN microarray, and then cured at a temperature of 100° to 130° for 1 to 2 hours.

The thinning and polishing in step 7 is divided into two stages. In the first stage, the silicon film layer is used as the first stop layer for the chemical mechanical polishing of the black epoxy resin glue, and the black epoxy resin glue is polished to the stop of the silicon film layer; In the second stage, the second N-type GaN layer is used as the second stop layer of the black epoxy resin glue chemical mechanical polishing, and the black epoxy resin glue is polished until the silicon film layer is completely removed, and the second N-type GaN layer is exposed;

The silicon film layer is a silicon oxide film layer or a silicon nitride film layer, which is used as a hard mask for etching gallium nitride materials; the water and oxygen barrier layer is a silicon nitride film layer or other dense dielectric materials to protect the life of the quantum dots.

The third technical solution adopted in the present invention is: the application of the quantum dot color conversion layer microarray, the quantum dot color conversion layer microarray is aligned with the matching GaN-based Micro LED microarray device to form a full-color MicroLED devices.

The beneficial effects of the present invention are as follows: the quantum dot color conversion layer microarray and the preparation method thereof of the present invention can make the quantum dots uniformly dispersed and effectively improve the The light intensity and light purity are improved; the preparation method of the present invention has simple process flow, high operability and wide application range; the quantum dot color conversion layer microarray prepared by the present invention is combined with the GaN-based blue light Micro-LED microarray. The full-color display device avoids the technical bottleneck of red and green mass transfer, reduces production costs and improves production efficiency.

Description of drawings

Fig. 1 is the flow chart of the preparation method of the quantum dot color conversion layer microarray of the present invention;

2 is a schematic structural diagram obtained in step 1 in the preparation method of the quantum dot color conversion layer microarray of the present invention;

3 is a schematic view of the structure obtained in step 2 in the preparation method of the quantum dot color conversion layer microarray of the present invention;

4 is a schematic view of the structure obtained in step 3 in the preparation method of the quantum dot color conversion layer microarray of the present invention;

5 is a schematic view of the structure obtained in step 4 in the preparation method of the quantum dot color conversion layer microarray of the present invention;

6 is a schematic view of the structure obtained in step 5 in the preparation method of the quantum dot color conversion layer microarray of the present invention;

7 is a schematic diagram of the structure obtained in step 6 in the preparation method of the quantum dot color conversion layer microarray of the present invention;

8 is a schematic diagram of the structure obtained in step 7 in the preparation method of the quantum dot color conversion layer microarray of the present invention;

9 is a schematic view of the structure obtained in step 8 in the preparation method of the quantum dot color conversion layer microarray of the present invention;

10 is a schematic view of the structure obtained in step 9 in the preparation method of the quantum dot color conversion layer microarray of the present invention;

11 is a schematic structural diagram of a quantum dot color conversion layer microarray obtained by the preparation method of the present invention;

FIG. 12 is a spectrogram of the quantum dot color conversion layer microarray of the present invention excited by blue light.

In the figure, 101. Substrate, 102. GaN epitaxial layer, 103. Silicon film layer, 104. Photoresist microarray, 105. Metal Cr microarray, 106. Black epoxy resin, 107. Red quantum dots, 108 . Green quantum dots, 109. Water and oxygen barrier.

Detailed ways

The present invention will be described in detail below with reference to the accompanying drawings and specific embodiments.

The present invention provides a quantum dot color conversion layer microarray and a preparation method thereof. The pixel points of the conversion layer microarray are 8um*8um, and the pixel point spacing is 4um. As shown in FIG. 1, the specific implementation steps are as follows:

(1) A silicon oxide film layer 103 with a thickness of 1 μm is grown on the GaN epitaxial layer 102 of the Si or sapphire substrate 101 by PECVD. The GaN epitaxial layer 102 involved is prepared by MOCVD, and the bottom-up structure and thickness of the GaN epitaxial layer 102 are the buffer layer 0.5um, the intrinsic GaN layer 1.5um, the first N-type GaN layer 5um, and the second N-type GaN layer. The GaN layer is 2um, and the total thickness of the epitaxial layer is 9um (Figure 2);

(2) Negative photoresist is spin-coated on the silicon film layer 103, the photomask pattern is a pixel point microarray pattern, the pixel point size is 8um*8um, and the pixel point spacing is 4um, and the crystal is exposed by an ultraviolet contact exposure machine. circle, the photoresist microarray 104 with the opposite polarity to that of the photomask pattern is obtained after development (FIG. 3);

(3) Ebeam is used to vapor-deposit a 200nm-thick metal Cr film as a hard mask for etching GaN; after the metal Cr film is vapor-deposited, the negative glue metal is stripped, and the Cr metal in the pixel spacing is stripped and removed, and finally a metal is formed. Cr microarray 105 (Figure 4);

(4) Using metal Cr as a hard mask, the silicon film layer 103 of 1um is etched by ICP. In order to ensure that the silicon film layer 103 is completely etched, an over-etching method can be adopted (Fig. 5);

(5) Using the metal Cr and silicon composite microarray as the composite hard mask, the GaN epitaxial layer 102 is etched by ICP to ensure that the first N-type GaN layer is etched to a thin layer thickness, and the remaining N-type GaN layer is etched here. The thin layer is used as the current conduction layer of the subsequent electrochemical etching process, and the GaN microarray is formed after the etching is completed (Figure 6);

(6) Spin-coat black epoxy resin glue 106 in the channel of the GaN microarray, and vacuum the glued wafer in a vacuum equipment of 0.01~0.1Pa for 10~20min to ensure that the black epoxy resin glue 106 can be better Infiltrate into the channel, and then cure the black epoxy resin glue 106 according to the curing conditions of the glue. Here, the parameters of curing at 100~130 degrees for 1~2 hours are used; the coating thickness of the black epoxy resin glue 106 is to adjust the depth of the channel. It is best to fill it completely, to avoid the black epoxy resin glue 106 above the GaN microarray being too thick, which will affect the efficiency of subsequent thinning and polishing of the glue layer (Figure 7);

(7) The wafer coated with black epoxy resin glue 106 is thinned and polished by CMP; polishing is divided into two stages. In the first stage, the silicon film layer 103 is used as the stop layer, and the black epoxy resin glue 106 Polishing until the silicon film layer 103 stops; in the second stage, the second N-type GaN layer is used as the polishing stop layer, and the black epoxy resin glue 106 is polished until the silicon film layer 103 is completely removed and the second N-type GaN layer is exposed; this It is necessary to ensure that the silicon film layer 103 is removed cleanly, and a polishing procedure can be set to overpolish the 0.5um second N-type GaN layer or use the BOE solution to soak the wafer to wet remove the silicon film layer 103 (Fig. 8);

(8) The GaN microarray is electrochemically etched with an anodizing machine to obtain an approximately vertical GaN nanoporous structure microarray with an etching depth of about 5um (Fig. 9);

(9) Spin-coat positive photoresist on the wafer surface, first define the red color conversion area on the GaN nanopore structure microarray using ultraviolet lithography, and inject red quantum dots 107 into the nanoholes in the red color conversion area by spraying equipment In the structure, the green color conversion area is then defined and green quantum dots 108 are injected to finally form an RGB array (Fig. 10);

(10) Use Sputter to deposit a film such as silicon nitride or other dielectric materials on the wafer that has been implanted with red and green quantum dots as a water-oxygen barrier layer 109 to protect the stability of the quantum dot material in the nanopore structure (Figure 11).

After completing the above steps, use a high-precision alignment bonding machine to perform alignment bonding between the quantum dot color conversion layer microarray and the matching GaN-based Micro LED microarray device. Here, the size of the Micro LED microarray pixel point can be selected as 3~5um, and finally form a full-color Micro LED device.

In the quantum dot color conversion layer microarray prepared by the above method, by using the nanopore structure as the quantum dot carrier layer, the quantum dots are uniformly dispersed, avoiding the problem of uneven distribution of quantum dots in the quantum dot film, and using the nanopore structure at the same time. The scattering of light effectively improves the light intensity; the light-blocking material is filled in the pixel channel to solve the problem of light crosstalk between pixels, thereby improving the purity of red and green light. In addition, the above-mentioned process is simple, high in operability, and has a wide range of applications, which can be applied to the preparation of devices of various sizes. In the preparation of full-color display devices, the quantum dot color conversion technology has high color gamut and high color purity, and at the same time, only blue LED chips are needed as the excitation light source, which avoids the technical bottleneck of red and green mass transfer and reduces costs. The production efficiency is improved; and the combination of Micro LED devices and quantum dot color conversion technology has broad application prospects in new micro display devices, AR/VR and other fields.

12 is a spectrum test chart of the quantum dot color conversion layer microarray of the present invention after excitation by blue light, it can be seen from the figure that under the same test conditions, the spectrogram of the quantum dot film structure shows a weak blue light peak position, and this There is no blue light peak in the spectrum of the inventive structure, which means that the purity of the red light excited by the blue light of the present invention is obviously better than that of the quantum dot film structure, and the red light intensity of the present invention is about 20% higher than that of the quantum dot film structure. .

Claims (10)

1. A quantum dot color conversion layer microarray, characterized in that it comprises a GaN epitaxial layer (102), a grid-shaped channel is formed on the GaN epitaxial layer (102), and a single GaN epitaxial layer pixel formed by the grid-shaped channel is separated Nano-hole structures are opened in the dot regions, and red quantum dots and green quantum dots are respectively injected into the nano-hole structures in two adjacent three GaN epitaxial layer pixel dot regions. 2 . The quantum dot color conversion layer microarray according to claim 1 , wherein the nanohole structure is a plurality of elongated holes and is vertically opened in the pixel region of a single GaN epitaxial layer. 3 . 3 . The quantum dot color conversion layer microarray of claim 1 , wherein the grid-shaped channels are filled with black epoxy resin glue. 4 . 4. The quantum dot color conversion layer microarray according to claim 1, wherein a water-oxygen barrier layer (109) is provided above the GaN epitaxial layer (102). 5. The quantum dot color conversion layer microarray according to claim 1, wherein the GaN epitaxial layer (102) is grown on a Si or sapphire substrate (101), and the GaN epitaxial layer (102) is grown from bottom to top The upper structure is a buffer layer, an intrinsic GaN layer, a first N-type GaN layer, and a second N-type GaN layer in sequence, and the bottom end of the channel is opened to the first N-type GaN layer. 6. The preparation method of quantum dot color conversion layer microarray, is characterized in that, comprises the following steps: Step 1. A buffer layer, an intrinsic GaN layer, a first N-type GaN layer and a second N-type GaN layer are sequentially grown on the substrate (101) as a GaN epitaxial layer (102), and grown on the second N-type GaN layer a silicon film layer (103); Step 2, spin-coating negative photoresist on the silicon film layer (103) obtained in step 1, the photomask pattern is a pixel point microarray pattern, and is exposed and developed by an ultraviolet contact exposure machine to obtain a photoresist microarray (104); Step 3, vapor-depositing a metal Cr film layer on the photoresist microarray (104) obtained in step 2, and after the metal Cr film layer is vapor-deposited, peel off and remove the Cr metal between the pixel points to form a metal Cr microarray (105); Step 4, using the metal Cr microarray (105) obtained in step 3 as a hard mask to etch the silicon film layer (103) to form a metal Cr and silicon composite microarray; Step 5, using the metal Cr and silicon composite microarray obtained in step 4 as a hard mask to etch the GaN epitaxial layer (102), etch to the bottom of the first N-type GaN layer, and form a GaN microarray after the etching is completed; Step 6. Spin-coat black epoxy resin glue (106) in the GaN microarray obtained in step 5, vacuum infiltrate and cure after spin-coating; Step 7, thinning and polishing the GaN microarray obtained in step 6, and polishing until the metal Cr film layer and the silicon film layer (103) are completely removed and the second N-type GaN layer is exposed; Step 8, performing electrochemical etching on the GaN microarray obtained in step 7 to obtain a GaN nanopore structure microarray; Step 9. Spin-coat positive photoresist on the surface of the GaN nanopore structure microarray obtained in Step 8, define a red color conversion area and a green color conversion area by ultraviolet lithography, and inject red quantum dots (107) into the red color conversion area. In the nanopore structure of the green color conversion region, green quantum dots (108) are injected into the nanopore structure of the green color conversion region to obtain an RGB array; In step 10, a water and oxygen barrier layer (109) is deposited on the RGB array obtained in step 9. 7. The method for preparing a quantum dot color conversion layer microarray according to claim 6, wherein in the step 6, vacuum infiltration and curing are specifically: pumping the spin-coated GaN microarray in a vacuum device Vacuum for 10~20min, vacuum degree range is 0.01~0.1Pa, and then cure at 100°~130° for 1~2h. 8. The method for preparing a quantum dot color conversion layer microarray according to claim 6, wherein the thinning and polishing in step 7 includes two stages, and the first stage uses the silicon film layer (103) as the The stop layer is polished until the silicon film layer (103) stops; in the second stage, the second N-type GaN layer is used as the stop layer, and the silicon film layer (103) is completely removed until the second N-type GaN layer is exposed. 9. The method for preparing a quantum dot color conversion layer microarray according to claim 6, wherein the silicon film layer (103) is a silicon oxide film layer or a silicon nitride film layer, and the water-oxygen barrier layer (109) ) is the silicon nitride film. 10. The application of the quantum dot color conversion layer microarray, characterized in that, the quantum dot color conversion layer microarray according to claim 1 is aligned with a matching GaN-based Micro LED microarray device to form a full-color Micro LED devices.

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