Highly reliable trench DMOSFET realized by using trench corner rounding

Using pull-back and hydrogen annealing processes, we have developed a new t rench corner rounding technique. This technique provides highly controllabl e trench corner rounding by microstructure transformation of the silicon at the corner of the trench, leading to a uniform gate oxide, a lower leakage current, and a higher breakdown voltage. The breakdown voltage of a trench DMOSFET fabricated using hydrogen annealing increases by 20 % compared wit h a conventional DMOSFET. The on-resistance of the trench DMOSFET fabricate d using the new technique is about 55 m Omega at a gate voltage of 10 V und er a drain current of 5 A.