The quasi-punch-through structure for power semiconductor devices

A new concept named quasi-punch-through (QPT) structure is proposed for power semiconductor devices in this paper and is found to possess the advantages of both PT and NPT structures. The structure utilizes closely located trenches at the anode end of the base to act as an electric-field shielding layer. With this structure, the highly doped N buffer layer can be avoided and the base thickness is kept low for a superior trade-off between the on-state voltage and turn-off loss. It is also found that, like NPT power devices, such devices have temperature insensitive turn-off losses and hence are able to be used at higher junction temperatures under high-frequency operating conditions