YFET - Trench superjunction process window extended

The drift zone of superjunction devices consists of compensated n- and p-columns. The manufacturability of such devices is based on the thorough control of acceptors and donator concentrations. Shrinking the cell pitch to a few micrometers requires considerably better compensation control compared to 10 mum pitch devices. A new concept that applies a stack of Y-shaped field plates to a charge compensated device is investigated by numerical simulation. The YFET concept provides a 7 times larger compensation process window compared to a device with oxide filled trenches, allowing much higher doping concentrations. A specific on-resistance of 0.65 Omegamm
²
at a breakdown voltage of 680 V can be achieved at a cell pitch of about 4.6 mum.