Low Capacitance Gate Process for E-Band GaN HEMTs

摘要

Gallium Nitride (GaN) is superior in breakdown voltage and RF performance and is suitable for high electron mobility transistors (HEMTs). Since wireless communication using millimeter-wave E-band (70–80 GHz) features wide bandwidth and large capacity, this system has been expected to function as backhaul communication. Therefore, we decided to develop E-band GaN HEMTs. The HEMT we aimed to develop required exclusive high frequency compared to that of current products that use mainly micrometer-waves (up to 16 GHz). So we had to remarkably improve RF performance. We chose InAlN as a barrier of GaN HEMTs for high transconductance and developed low capacitance gate process, a key technology of RF performance improvement. To reduce gate capacitance (Cgs), Y-shaped gate process with short gate length of 100 nm was developed. With this process, we have obtained extremely low Cgs of 0.58 pF/mm and the current gain cutoff frequency of 110 GHz and realized high RF performance E-band GaN HEMTs.