1 Introduction At present, the world has entered the "energy-saving era", and countries are actively looking for energy-saving and environmentally-friendly emerging industries. The energy consumed by lighting accounts for more than 20% of total energy consumption. Therefore, reducing lighting power is an important way to save electricity. LED energy-saving lamp is a new generation of solid cold light source. It has the characteristics of low energy consumption, long life, easy control, safety and environmental protection. It is an ideal energy-saving and environmentally friendly product, suitable for various lighting places. However, at present, LED has not entered large-scale general lighting, one of the main reasons is that because the cost performance (lm/$) of LED is too low, the market needs to quickly improve the cost performance of LED. There are two main ways to improve the cost performance of LEDs. One is to improve the luminous efficiency of LEDs, and the other is to reduce the production cost of LEDs. However, the increase in efficiency and the speed of cost reduction still fall short of the market's expectation of LED cost performance. However, the vertical structure LED can ensure that a large current is used for driving under the premise of a certain luminous efficiency, such a vertical structure LED chip can be equivalent to several positive-fit structure chips, which can be folded into a fraction of the formal structure. Therefore, the vertical structure LED will inevitably accelerate the process of LED application in the general lighting field, which is the direction of the market and is an inevitable trend in the development of semiconductor lighting . 2, the advantages of GaN-based vertical structure LED From the structure of the LED, the GaN-based LED can be divided into a formal structure, a flip-chip structure, and a vertical structure. At present, the more mature Group III nitrides mostly use sapphire materials as the substrate. Due to the insulation of the sapphire substrate, the ordinary GaN-based LEDs adopt a formal structure. The schematic diagram of the formal structure is shown in Fig. 1. The light emitted from the active region is emitted through the P-type GaN region and the transparent electrode. The structure is simple and the production process is relatively mature. However, the LED of the formal structure has two obvious disadvantages. First, the LEDs of the positive-fit structure are placed on the same side of the LED. The current must flow laterally through the n-GaN layer, causing current crowding and high local heat generation, which limits the driving current. Due to the poor thermal conductivity of the sapphire substrate (35W/(m?K)), the heat loss is seriously hindered. In order to solve the heat dissipation problem, Lumileds Lighting Company of the United States invented Flipchip technology. A schematic diagram of the structure is shown in FIG. 2. This method firstly prepares a large-sized LED chip suitable for eutectic soldering, simultaneously prepares a silicon substrate of a corresponding size, and fabricates a gold conductive layer and a conductive layer of the eutectic soldering electrode thereon. (Ultrasonic gold wire solder joint). Then, a large-sized LED chip is soldered to the silicon substrate using a eutectic soldering apparatus. The structure of the package has been greatly improved in heat dissipation, but the usual GaN-based structure-mounted LED is still a lateral structure, and current crowding still exists, which still limits the further improvement of the drive current. The vertical structure can effectively solve the two problems of the LED of the formal structure. The vertical structure GaN-based LED replaces the sapphire substrate with a substrate with high thermal conductivity (substrate such as Si, Ge and Cu), which greatly improves the heat dissipation efficiency; The two electrodes of the vertically-structured LED chip are respectively on both sides of the epitaxial layer of the LED, and through the patterned n-electrode, the current flows almost entirely vertically through the epitaxial layer of the LED, and the current flowing in the lateral direction is extremely small, thereby avoiding current crowding of the formal structure. The problem is to improve the luminous efficiency, and also solve the problem of shading of the P pole and improve the luminous area of ​​the LED. 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September 07, 2019