Because of its ultra-high resolution, high color saturation, nanosecond response time, and low power consumption, Micro LED has become a new generation of international manufacturers such as Apple, Sony, Facebook, Samsung, LG, Osram, and Nichia. Display technology.
As a global leader in GaN-based LED technology on silicon substrates, Jingneng Optoelectronics recently set its sights on Micro LED.
The choice of Micro LED chip route must take into account cost, yield, and compatibility with transfer / bonding processes. The larger the size of the epitaxial wafer, not only can reduce the chip cost and improve the utilization of the epitaxial area, but it is also easier to be compatible with the IC process to improve the production efficiency and yield of Micro LED.
Fu Jing, vice president of Jingneng Optoelectronics, said that currently only 8-inch mass production of silicon-based GaN-based LEDs has been achieved, and excellent uniformity of wavelength dispersion in the 8-inch epitaxial wafer is less than 1 nm in a single MOCVD cavity. It is crucial for Micro LED. Commercial 12-inch and larger silicon wafers are fully mature. With the introduction of high uniformity MOCVD epitaxial large cavities, there is no essential difficulty in upgrading silicon substrate LED epitaxy to larger wafer sizes.
Fu Zheng introduced that silicon-based GaN-based LEDs use a chemical wet-removal substrate process to obtain LED thin-film chips. This wet stripping avoids damage to the LED epitaxial layer and guarantees the light efficiency of Micro LEDs driven by small currents. And yield is critical.
As a comparison, the damage of GaN epitaxial layer by laser peeling of sapphire substrate is unavoidable, and it can be predicted that when the sapphire substrate can be upgraded to a larger size, the challenge of laser peeling substrate yield will become more and more serious. In the thin film chip manufacturing process, although SiC and GaN substrate LEDs do not require laser stripping, the extremely high prices of these two substrates (especially large-size substrates) will increase the difficulty of market competition for Micro LED and OLED.
He pointed out that the current structural design of the Micro LED thin film chip is divided into two types: flip-chip (two electrodes on the same side) and vertical (upper and lower electrodes). For a typical size of Micro LED (with the chip side length not exceeding 10μm), if the same-side two-electrode structure is used, the positive and negative connection can be completed with a single bond with the control backplane, but positive and negative electrodes are prone to occur during the bonding Short-circuit, but also a great challenge to the accuracy of bonding. In contrast, thin film vertical Micro LEDs with upper and lower electrodes are more conducive to bonding yield, but need to add a layer of common anode (or common anode) transparent electrodes.
In short, regardless of whether the back-end process requires the same-side two-electrode structure or the upper and lower electrode structure, the large-size silicon substrate LED thin film chip manufacturing process can correspondingly produce low-cost, high-yield Micro LED chips.
Fu Yan believes that the low-cost, large-size, non-destructive silicon substrate thin-film LED process will strongly promote the development and industrialization of Micro LED.
Regarding Jingneng Optoelectronics ’participation in the Micro LED research camp, Dr. Liu Guoxu, CTO of Yimeixinguang commented:“ The characteristics of silicon-based GaN-based technology is a natural choice for manufacturing Micro LED chips. With more than ten years of technology and mass production experience, if it can be transferred to Micro LED, the application of Micro LED will take a big step forward. "
Perhaps as Liu Guoxu said: Micro LED may be another major application opportunity for Jingneng Optoelectronics!