GaN based high electron mobility transistors (HEMT) are becoming more dominant in the power switching and RF wireless markets and substantial growth of GaN technology is expected over the coming decade. In contrast to the Silicon transistors that have traditionally been employed for such applications, these GaN devices come with a new set of challenges and requirements. Effective mitigation of PVD induced damage in the GaN or AlGaN crystal structure – essential to uphold the promise of high efficiency in switching and amplification – requires specifically dedicated process technology. In addition, the electrical properties of gate and source/drain metallization need to be carefully tuned to form effective Schottky or Ohmic contacts while barrier properties are usually required in the same thin film layers to inhibit metal diffusion. We will discuss how a combination of specialised PVD technology and the appropriate characterization methods must be employed to control all these aspects, so that the relevant film material properties are optimized, and plasma damage is minimized.
Dr. Clemens Nyffeler is currently a scientist at Evatec's R&D department, contributing to technology development in the area of GaN applications for the power and wireless markets. He was previously a process engineer in the Semiconductor business unit, developing various PVD processes including reactive sputter deposition of conductive metal nitrides for transistor metallization. Prior to joining Evatec in 2018, Clemens gained both his Bachelor and Masters degrees at EPFL in electrical engineering (2008) and micro- nanotechnology (2011) respectively before going on to complete his PhD in 2016, also at EPFL . His work there was focused on areas including graphene field effect devices and piezoelectric AlScN thin film characterization.