Design of a 200V super junction MOSFET with n-buffer regions and its fabrication by trench filling

A new super junction trench MOSFET, which has n-buffer regions between trench gates and n columns, was designed and demonstrated. In this structure, the specific on-resistance (R_ON) does not increase as long as the trench gate bottom is covered with the n buffer, even though the gate position shifts from the designed one. The drift region, consisting of p/n columns in the structure, were formed by a trench filling epitaxial method. The fabricated SJ-MOSFET with a fine cell pitch of 4 μm showed an RON of 2.3 nΩ.cm² at a breakdown voltage (V_BR) of 203 V. The R_on is 35% lower than that of the silicon limit.