Kimimori Hamada received his M.E. degree in Electrical Engineering from Osaka Prefecture University, Japan in 1985. He joined Toyota Motor Corporation in 1985. He was involved in the in-house semiconductor project in TMC as one of the starting members in 1987. He was mainly in charge of device developments of Power MOSFET, BiCDMOS, IGBT and SiC MOSFET. He developed all IGBT devices for Toyota Prius HEVs. He received his Ph.D in Engineering from University of Tsukuba, Japan in 2017. He currently works as a power semiconductor consultant and is a president of PDPlus LLC. He is a member of the Institute of Electrical Engineers of Japan (IEEJ), the Society of Automotive Engineers of Japan (JSAE) and IEEE. He won Best Paper Award of ISPSD2005. He will serve as a General Chair of ISPSD2021 Nagoya.
Topic: The 4H-SiC MOSFET new challenging structures of “Ultra-Narrow-Body (UNB) MOSFET” and “Grounded Narrow and Deep p (GND) MOSFET”
Abstract: UNB MOSFET: A lateral trench SiC MOSFET with lateral conduction on the side walls was designed using an ultra-narrow body (UNB) sandwiched by the trench walls. The p-body is designed to be very narrow in order to avoid any depletion region formed in its body. The structure is similar to FinFET structure and is applied to 4H-SiC MOSFET. The body width in the channel region of the fabricated UNB MOSFET was 55 nm. The UNB structure presented a significant increase in the mobility, reaching values of over 200 cm2/Vs. The result indicated a very prominent FinFET effect, resulting in very high mobility and hence very significant improvement in the channel resistance of SiC MOSFETs.
GND MOSFET: High breakdown voltage, low on-resistance and low DS leakage current were realized by 4H-SiC trench MOSFET with narrow and deep grounded p layers formed under trenches by trench gate self-alignment technique. The BVdss of this MOSFET is 1080 V, the Ron,sp is 1.19 mΩcm2 at 25 °C and 2.04 mΩcm2 at 175°C, the Vth is 4.0 V, and the Idss is 50 nA at 900 V (□9.6 mm). By clarifying the effect of implantation defects on leakage current, this structure was achieved by a simple process that adopts low temperature implantation for all implantation steps.