Enkris Semiconductor in China has demonstrated 300mm GaN-on-Si epiwafers for 200V, 650V and 1200V power applications.

The GaN wafer epi-foundry based at Suzhou Industrial Park, China, says this paves the way for HEMT transistor processing on mainstream 300mm CMOS-compatible lines.

Commercial GaN power devices based on GaN-on-Si HEMT technology are gaining in popularity for a wide range of applications such as consumer electronics, industrial electronics and data centres, and in the energy, automotive and mobility sectors. The move to 300mm is driven by cost reduction and demand for more sophisticated integrated circuit design.

The company launched commercial 200mm GaN-on-Si HV HEMT epiwafers in 2014 and has now moved its AlGaN/GaN HEMT epitaxy process to 300mm Si substrates, while maintaining the excellent thickness uniformity and low wafer bow within 50µm. 

The vertical voltage breakdown measurements suggest the wafers are suitable for 200V, 650V and 1200V power applications, substantially above today’s highest voltages for GaN. The move to 300mm also provides more oportunity for integrating logic on the chip. 

The 300mm GaN-on-Si HEMT epitaxial layer structure uses an AlN nucleation layer, followed by a strain relief stack, GaN channel, AlGaN barrier and GaN cap. The narrow XRD AlN(002) peak and a good uniformity of FWHM indicate a high crystalline quality across the whole 300mm wafer.  

The Al composition in the AlGaN barrier and the 2DEG carrier concentration measured at nine positions from wafer centre to wafer edge.  The measurements give an average value of 19.9 percent and a deviation of 0.68 percent of Al composition in the AlGaN barrier, suggesting a uniform 2DEG electrical characteristics. This has been confirmed by the CV measurements, revealing an average electron concentration of 7.2E12 cm-2 with a deviation of less than 2 percent.

“Thanks to our optimised AlN nucleation layer, we are able to produce crack-free GaN-based HEMT epiwafers that meet the leakage current requirements on large size Si substrates up to 300mm,” said Dr Kai Cheng, CEO of Enkris. “Despite the challenges in the epitaxy process, strain management and defect control when moving to 300mm wafer size, we have achieved excellent structural quality and electrical properties in the AlGaN/GaN HEMT structures. This will certainly encourage the development of high-power integrated circuits to yield system-on-chip and further reduce the cost of GaN power devices.”