Feasibility study of a junction termination using deep trench isolation technique for the realization of DT-SJMOSFETs

In this work, a new design of high voltage (1200 Volts range) power superjunction MOSFET (SJMOSFET) is presented: the deep trench SJMOSFET (DT-SJMOSFET). Besides, a new junction termination, consisting in a 70 mum width and 100 mum depth trench filled by a dielectric, is proposed. Simulation results show that this junction termination exhibits the same blocking voltage capability as the base cell (central cell). In addition, the termination breakdown voltage dependence on the dielectric critical electric field (E Cd ) and its permittivity (epsiv rd ) is studied. Finally, the possibility of filling the trench termination using low dielectric polyimide such as BenzoCycloButene (BCB) is successfully approved and the Chemical Mechanical Polishing of BCB is also discussed. These experimental results represent the key steps for a future complete fabrication process of DT-SJMOSFET.