Chinese company, Enkris Semiconductor, Inc. has demonstrated the manufacturing of high voltage Gallium Nitride (GaN) HEMT (High Electron Mobility Transistor) structures on 200 mm Silicon substrates with an Aixtron tool. GaN layers grown on silicon tend to have defects that lead to high buffer leakage. Enkris says that the GaN HEMT materials have excellent uniformity and low buffer leakage. The thickness uniformity of the materials is below 0.5 percent without edge exclusion. The company contends that under special conditions the uniformity can be further improved.
“It has been well accepted that GaN on large size silicon substrates is the most cost-effective way to achieve high-volume production of GaN power devices. However, a large wafer bow combined with a high buffer leakage has hindered the further development of the GaN-on-Si technology so far,” said Dr. Cheng Kai, co-founder of Enkris. “Our process on 200 mm silicon substrates shows that high breakdown voltage (less than 1600 V) GaN power devices with low leakage currently can be achieved with relatively thin buffer layers of 4 µm. They simplify the growth process, minimize the wafer bow and reduce the epi-cost significantly. Based on our processes that were applied on an Aixtron system, GaN-on-Si power devices may reach even higher voltages in the near future,” Dr. Cheng Kai added.