A Novel Process for Fabricating High Density Trench MOSFETs for DC‐DC Converters

We propose a new process technique for fabricating very high‐density trench MOSFETs using 3 mask layers with oxide spacers and a self‐aligned technique. This technique reduces the device size in trench width, source, and p‐body region with a resulting increase in cell density and current driving capability as well as cost‐effective production capability. We were able to obtain a higher breakdown voltage with uniform oxide grown along the trench surface. The channel density of the trench DMOSFET with a cell pitch of 2.3‐2.4 µm was 100 Mcell/in2 and a specific on‐resistance of 0.41 mΩ·cm2 was obtained under a blocking voltage of 43 V.