A novel buffer structure and lifetime control technique with Poly-Si for thin wafer diode

A novel buffer structure for improving the trade-off between forward voltage and reverse recovery loss across the whole range of current density and realizing the softness during reverse recovery was developed. The structure named a ldquoBroad Buffers from Double Sides structurerdquo (BBDS) is composed a broad p- anode layer and a broad n- buffer layer. A novel technique called ldquoLocal Lifetime control technique with Poly-Si layerrdquo (LLP) was also developed. LLP controls the conductivity modulation level without introducing recombination centers in the n-layer. Combining these new techniques, namely, BBDS and LLP, made it possible, for the first time, to create a fast-recovery diode without the need to use conventional heavy-metal diffusion or irradiation methods.