A novel fabrication of TDMOSFETs using two-step trench etching and twice self-alignment technique

A new fabrication method employing two-step trench etching and twice self-alignment technique was developed to obtain high cell density trench power MOSFETs by using only three mask steps. This method was implemented to increase cell density, to decrease on-resistance and to improve leakage current characteristics. The trench DMOSFETs with 1.6 μm cell pitch and 140 Mcell/in² cell density were fabricated. The specific on-resistance of the device is about 0.48 mΩ˖cm² with the breakdown voltage of 43 V.