Accelerating the commercialization of Micro LEDs, MOCVD plays an important role
2019-09-03 16:31
From the perspective of product development progress, Micro LED is close at hand, but from the perspective of commercialization time, Micro LED is far away. From the initial budding period to the present stage, Micro LED technology has made great progress, and related products on the market have also surfaced. However, due to technical bottlenecks and cost issues, Micro LED has been widely used for a long time.
According to LEDinside's latest research report "2019 Micro LED Next Generation Display Key Technology Report", Micro LED technology faces many challenges, but compared with two years ago, the current technological progress has been much improved. The early patented technology already has a physical sample display machine. Appearance. With the maturity of Micro LED technology, the commercialization of Micro LED will gradually accelerate. In addition, the manufacturing process of Micro LED is cumbersome and demanding. The raw materials, process consumables, production equipment, testing instruments and auxiliary fixtures used in the process are required to be rigorous in specifications and relatively precise in precision.
The commercialization of Micro LEDs is important for every aspect of the process, such as MOCVD, a key core device for LED epitaxial wafer fabrication. Austin, a German-based MOCVD equipment supplier, has been working on the development of epitaxial wafers to promote the mass production of Micro LEDs and accelerate the introduction of Micro LED products into the market.
Regarding the application of Micro LED, Ai Siqiang believes that the TV display panel will be the first commercial product to open the market. Secondly, the vehicle display is also a relatively large application market for future Micro LEDs. With the increase in customer requirements, the demand for upgrading the display of the car has gradually increased, such as the dynamic display of information inside and outside the car and the creation of atmosphere to increase interaction between people and vehicles. Other application markets include smart phones, AR/VR, wearable devices and more.
Yield and cost are two factors that hinder mass production of Micro LEDs
Ai Siqiang said that at this stage, compared with LCD and OLED, Micro LED does not have a cost advantage. Cost reduction involves many factors, such as defect rate and yield. Due to the ultra-small size of the Micro LED chip, the technical difficulty is difficult, and the yield is difficult to guarantee, so the cost is high. In particular, the processing of red light is limited by materials and characteristics, and the red light yield is low and the reliability is not high, so the cost is extremely high.
As a key core device for the manufacture of LED epitaxial wafers, MOCVD epitaxial wafer production yields include wavelength uniformity, Bow Management, and Defects Density.
Taking the traditional display LED chip as an example, the proportion of the cost of the sorting link is large. If this link is removed, the cost will drop a lot. As for the Micro LED, due to the production process and cost, it is impossible to have a sorting step, which indicates that the wavelength uniformity is very high. In order to achieve mass production of Micro LEDs, all epitaxial wafers produced by MOCVD equipment must have a wavelength range of 4 nm or less.
In terms of warpage management, Ai Siqiang believes that Micro LED will develop in more than 6 inches, and the 6-inch warpage management is very different from 4 inches. Whether it is a germanium substrate or a sapphire substrate, a special epitaxial process is required to achieve stable warpage performance.
If the wavelength uniformity is maintained in the range of 4 nm, the warpage management is less than 50 μm, and the defect density is controlled within 0.15/cm 2 , the production yield can be ensured.
MOCVD's C2C and In-Situ Cleaning technologies help commercialize Micro LEDs
In terms of high throughput and low cost, Axon's automatic cassette (C2C) wafer transfer module technology enables automatic 8x6 inch or 5x8 inch GaN-on-Si wafers in a closed cassette environment. Loading and removing, increasing the yield while ensuring the particle density of the epitaxial wafer.
Figure 1: G5+C C2C Transmission Module
In addition, AiShen MOCVD equipment features In-Situ Cleaning technology, which ensures that the equipment is cleaned every time it runs, ensuring low defect density of the epitaxial wafer and significantly reducing downtime , to ensure high yield, thereby reducing production costs.
According to reports, automatic in-situ cleaning technology is a standard technology in the semiconductor industry, but in the MOCVD equipment circle, this technology has not been popularized for the following reasons: the decomposition temperature of gallium nitride is very high, reaching 1400-1500 degrees Celsius. If it is in the case of chlorine, the temperature will be relatively low, up to 900 degrees Celsius, including the surface and all the faces of the cavity need to be lowered to this temperature, which is very challenging for MOCVD equipment manufacturers. At present, many MOCVD equipments use a stainless steel structure, and stainless steel needs to be cooled by water, which is inconsistent with 900 degrees Celsius. Ai Siqiang's MOCVD equipment uses a full graphite cavity to ensure stable surface deposition and to ensure that graphite can be heated above 900 degrees Celsius.
Ai Siqiang said that these two technologies of MOCVD equipment are the key technologies to achieve high yield and low cost of Micro LED. Traditional LED production needs to shift to a more automated production model to ensure high yields, reduce costs, and accelerate mass production of Micro LEDs.
Figure 2: AIX G5+C Planetary Reactor
It is understood that Ai Siqiang's planetary reactor platform equipped with automatic cassette (C2C) and automatic in-situ cleaning technology has received orders from many customers, which greatly optimizes the yield of epitaxial wafers and the level of production automation.
In the future, Ai Siqiang will continue to invest in technology research and development to help commercialize Micro LED. (Text: LEDinside Janice) |
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