Micro-LED device pixel array preparation method

Abstract

The invention relates to the technical field of semiconductor preparation, in particular to a Micro-LED device pixel array preparation method, which comprises the following steps of: sequentially manufacturing an n-GaN layer common cathode, manufacturing a cathode table of an n-GaN layer, and evaporating metal on the cathode table of the n-GaN layer and a p-GaN layer through photoresist; then, SiO2 passivation layers are evaporated on the metal electrode of the n-GaN layer, the metal array electrode of the p-GaN layer, the metal electrode of the n-GaN layer and the metal array electrode of the p-GaN layer, and ohmic holes are prepared; and finally, after annealing, connecting the prepared n-GaN layer metal electrode and the p-GaN layer metal array electrode of the epitaxial wafer with an IC (Integrated Circuit) driving circuit to form a complete Micro-LED device. According to the method, the anode metal array electrode is prepared on the p-GaN layer and is directly connected with the IC driving circuit, and the yield is improved by forming the pixel array through the CMOS IC driving circuit.

Description

Technical Field

[0001] The present invention relates to the field of semiconductor manufacturing technology, and specifically to a method for manufacturing a pixel array of a Micro-LED device. Background Art

[0002] At present, the preparation methods of Micro-LED devices mainly consist of three methods: flip-chip, face-mounted and vertical. The pixel arrays involved in the pixel preparation of these methods are inseparable from the key step of etching. However, there are some problems with the current etching technology: first, the etching process may cause damage to the surface, which will cause a significant decrease in the efficiency of Micro-LED; second, the sidewall effect during the etching process is also a problem. The defects caused by etching will lead to pixel loss, resulting in performance problems such as device luminous efficiency and luminous uniformity, which will greatly hinder the commercialization of Micro-LED.

[0003] Epitaxial wafers are mainly composed of buffer layers, n-GaN layers, multi-quantum well layers, electron blocking layers, and p-GaN layers. The pixel array of Micro-LED needs to be made by etching epitaxial wafers. However, there are some problems with the current etching technology: first, the etching process will cause damage to the pixel sidewalls, resulting in low luminous efficiency and poor luminous uniformity of the device; second, the etching process will damage the multi-quantum well layer and the electron blocking layer, causing the electrons in the multi-quantum well layer to escape from the damaged part and directly undergo non-radiative recombination with the holes in the p-GaN layer, greatly affecting the current efficiency of the device. In addition, the pixel pitch of Micro-LED is at the micron level. For Micro-LED devices, the pixel damage caused by etching has a large pixel damage duty cycle, and the pixels are difficult to repair. Therefore, there is great resistance to the commercialization of Micro-LED devices. Summary of the invention

[0004] In view of the problems existing in preparing a Micro-LED device pixel array by an etching process, the present invention proposes a method for preparing a Micro-LED device pixel array.

[0005] The Micro-LED device of the present invention realizes image display by generating electrical signals representing corresponding images simultaneously or sequentially through a pixel array, and the preparation steps of the pixel array are as follows: Step 1: Surface cleaning to remove impurities on the surface of the epitaxial wafer; Step 2: Evaporation of ITO film; Step 3: Make a photolithography mask and etch the n-GaN layer through photoresist to prepare a common cathode; Step 4: Remove the photoresist to form the cathode mesa of the n-GaN layer; Step 5: Make a photolithography mask and evaporate metal on the cathode table of the n-GaN layer and the p-GaN layer through the photoresist; Step 6: Remove the photoresist to form a metal electrode of the n-GaN layer and a metal array electrode of the p-GaN layer; Step 7: Make a photolithography mask and evaporate a SiO2 passivation layer on the n-GaN layer metal electrode and the p-GaN layer metal array electrode to prevent leakage; Step 8: Make a photolithography mask to prepare an ohmic hole, and etch the SiO2 passivation layer on the metal electrode of the n-GaN layer and the metal array electrode of the p-GaN layer to make the metal conductive; Step 9: Annealing to promote ohmic contact between the n-GaN layer metal electrode and the p-GaN layer metal array electrode; Step 10: Connect the prepared epitaxial wafer n-GaN layer metal electrode and p-GaN layer metal array electrode to the CMOS IC drive circuit to form a complete Micro-LED device. The Micro-LED device can be lit up by powering it through the CMOS IC drive circuit.

[0006] Compared with the traditional method, the pixel array of the p-GaN layer needs to be etched into an array of μm or even sub-μm size through an etching process, and then a metal electrode is prepared on the pixel array of the p-GaN layer. The entire preparation process is complicated and the yield is extremely low, which greatly affects the photoelectric performance of the device. The method of the present invention only needs to prepare an anode metal array electrode on the p-GaN layer and directly connect it to the IC drive circuit to form a pixel array through the CMOS IC drive circuit. BRIEF DESCRIPTION OF THE DRAWINGS

[0007] Figure 1 This is a comparison diagram of the pixel design of the Micro-LED device of the present invention and the traditional chip Micro-LED device.

[0008] Figure 2 This is a photo of the Micro-LED device of the present invention being lit.

[0009] Figure 3 This is the BV test diagram of the Micro-LED device of the present invention.

[0010] Figure 4 This is a current efficiency diagram of the Micro-LED device of the present invention.

[0011] Figure 5 EL diagrams of the Micro-LED device of the present invention at different current densities.

[0012] Figure 6 The present invention is an external quantum efficiency diagram of a Micro-LED device. DETAILED DESCRIPTION

[0013] Embodiment 1: A method for preparing a pixel array of a Micro-LED device, the specific steps are as follows: Step 1: Surface cleaning to remove impurities on the surface of the epitaxial wafer; Step 2: Evaporation of ITO film; Step 3: Make a photolithography mask and etch the n-GaN layer through photoresist to prepare a common cathode; Step 4: Remove the photoresist to form the cathode mesa of the n-GaN layer; Step 5: Make a photolithography mask and evaporate metal on the cathode table of the n-GaN layer and the p-GaN layer through the photoresist; Step 6: Remove the photoresist to form a metal electrode of the n-GaN layer and a metal array electrode of the p-GaN layer; Step 7: Make a photolithography mask and evaporate a SiO2 passivation layer on the n-GaN layer metal electrode and the p-GaN layer metal array electrode to prevent leakage; Step 8: Make a photolithography mask to prepare an ohmic hole, and etch the SiO2 passivation layer on the metal electrode of the n-GaN layer and the metal array electrode of the p-GaN layer to make the metal conductive; Step 9: Annealing to promote ohmic contact between the n-GaN layer metal electrode and the p-GaN layer metal array electrode; Step 10: Connect the prepared epitaxial wafer n-GaN layer metal electrodes and p-GaN layer metal array electrodes to the IC driving circuit to form a complete Micro-LED device. The Micro-LED device can be lit up by powering it through the CMOS IC driving circuit.

[0014] like Figure 1 As shown, (a) is a schematic diagram of a conventional device pixel design. The pixel array produced by this method is severely damaged and will cause various non-radiative recombination; (b) is a schematic diagram of the anode pixel array design of the present invention; (c) is a schematic diagram of the complete device structure of the present invention.

[0015] like Figure 2 As shown, this is a real picture of the device when it is lit. The picture shows that the brightness of the device is uniform and the integrity is good.

[0016] like Figure 3 As shown in the figure, the device is tested for brightness at different voltages. The maximum brightness of the device reaches 1.6 million / cd, indicating that the device has good photoelectric performance.

[0017] like Figure 4 As shown, the current efficiency of the device is obtained based on the brightness. The current efficiency of the device is 102%, indicating that the device performance is very good.

[0018] like Figure 5 As shown in the figure, the light-to-luminescence spectrum (EL) of the device at different current densities. Through EL, it is found that the device does not shift at different current densities, indicating that the device has good stability.

[0019] like Figure 6 As shown, the external quantum efficiency of the device is 16.5%. There is no obvious green droop phenomenon, indicating that the performance of the device is very good.

Claims

1. A method for preparing a pixel array of a Micro-LED device, characterized in that The specific steps are as follows: Step 1: Evaporation of ITO film; Step 2: Make a photolithography mask and etch the n-GaN layer through photoresist to prepare a common cathode; Step 3: Remove the photoresist to form the cathode mesa of the n-GaN layer; Step 4: Make a photolithography mask and evaporate metal on the cathode table of the n-GaN layer and the p-GaN layer through the photoresist; Step 5: Remove the photoresist to form a metal electrode of the n-GaN layer and a metal array electrode of the p-GaN layer; Step 6: Make a photolithography mask and evaporate a SiO2 passivation layer on the n-GaN layer metal electrode and the p-GaN layer metal array electrode to prevent leakage; Step 7: Make a photolithography mask to prepare an ohmic hole, and etch the SiO2 passivation layer on the metal electrode of the n-GaN layer and the metal array electrode of the p-GaN layer to make the metal conductive; Step 8: Annealing to promote ohmic contact between the n-GaN layer metal electrode and the p-GaN layer metal array electrode; Step 9: Connect the prepared epitaxial wafer n-GaN layer metal electrode and p-GaN layer metal array electrode to the CMOS IC driving circuit to form a complete Micro-LED device.

2. The method for preparing a Micro-LED device pixel array according to claim 1, characterized in that The first step is to clean and remove impurities on the surface of the epitaxial wafer before evaporating the ITO film.

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