Due to its ultra-high resolution, high color saturation, nanosecond response time, and low power consumption, Micro LED has become a new generation display technology that international giants such as Apple, Sony, Facebook, Samsung, LG, Osram, and Nichia are vying to layout.

As a global leader in GaN based LED technology on silicon substrates, LatticePower has recently turned its attention to Micro LEDs.

The selection of Micro LED chip routes must consider cost, yield, and compatibility with transfer/bonding processes. The larger the size of the epitaxial wafer, not only can it reduce chip costs and improve epitaxial area utilization, but it is also easier to be compatible with IC processes to improve Micro LED production efficiency and yield.

Dr. Fu, Vice President of LatticePower, stated that currently, only silicon based GaN based LEDs have achieved 8-inch mass production and achieved excellent uniformity with wavelength dispersion less than 1nm in 8-inch epitaxial wafers in a single MOCVD cavity, which is crucial for Micro LEDs. Commercial silicon wafers of 12 inches and above have fully matured. With the introduction of high uniformity MOCVD epitaxial large cavities, there is no inherent difficulty in upgrading silicon based LED epitaxial to larger wafer sizes.

Dr. Fu introduced that GaN based LEDs on silicon substrates use a chemical wet substrate removal process to obtain LED thin film chips. This wet stripping avoids damage to the LED epitaxial layer and is crucial for ensuring the light efficiency and yield of Micro LEDs driven by small currents.

As a comparison, it is difficult to avoid the damage to the GaN epitaxial layer caused by laser peeling of sapphire substrates, and it can be foreseen that the challenge of laser peeling substrate yield will become greater when the sapphire substrate can be upgraded to a larger size. In the process of thin film chip manufacturing, although SiC and GaN substrate LEDs do not require laser peeling, the high prices of these two substrates (especially large-sized substrates) will increase the difficulty of market competition between Micro LEDs and OLEDs.

He pointed out that the current structural design of Micro LED thin film chips can be divided into two types: inverted (dual electrode on the same side) and vertical (upper and lower electrodes). For typical size Micro LEDs (chip side length not exceeding 10 μ m) If the same side dual electrode structure is used and the control backplane is bonded in one go, the positive and negative electrode connection can be completed. However, during the bonding process, there is a risk of short circuits between the positive and negative electrodes, which also poses a great challenge to the bonding accuracy. Compared to this, the thin film vertical Micro LED with upper and lower electrodes is more conducive to bonding yield, but an additional layer of co negative (or co positive) transparent electrodes is required.

In summary, regardless of whether the backend process requires a dual electrode structure on the same side or an upper and lower electrode structure, the large-sized silicon substrate LED thin film chip process can correspondingly prepare low-cost and high yield Micro LED chips.

He believes that the low-cost, large-sized, and non-destructive silicon substrate thin film LED process will strongly promote the development and industrialization of Micro LEDs.

Regarding the addition of Crystal Energy Optoelectronics to the research camp of Micro LED, Dr. Liu Guoxu, CTO of Yimeixin Optoelectronics, commented: "The characteristics of silicon substrate GaN based technology are a natural choice for manufacturing Micro LED chips. Crystal Energy Optoelectronics has accumulated more than ten years of technology and mass production experience in the field of silicon substrate GaN based LED. 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 Crystal Energy Optoelectronics!