Noboru Matsuda

High density MOSBD (UMOS with built-in Trench Schottky Barrier Diode) for Synchronous Buck Converters

We proposed a new MOSBD, which integrates MOSFET and Schottky barrier diode (SBD) in a single chip. The features of the device are that the SBD are fabricated on fine mesa of less than 0.2mum, surrounded by trenches and optimally distributed inside the high density UMOS. We show that the distributed layout of the SBD inside the MOSFET cells is effective to reduce the reverse recovery charge (Qrr), output charge (QOSS(SBD)) and the forward voltage drop (VfSBD ). In addition, integrated high density UMOS realizes low on-resistance of 18mOmegamm2 at Vgs=4.5V. The developed MOSBD achieved 46% reduction of chip size, compared to conventional MOSBD and low leakage current even in 175deg C high temperature condition. The developed MOSBD successfully increases the conversion efficiency, compared to the discrete solution of MOSFET with external SBD