A numerical study of scaling issues for trench power MOSFETs

The effect of the scaling down on the electrical performance of trench power MOSFET structures is investigated in this work by means of numerical simulation tools. Layout dimensions of trench power MOSFETs have been continuously reduced in order to decrease the specific on-resistance, maintaining equal vertical dimensions. Nowadays, the last scaling efforts provide trench width and distance between two consecutive trenches in the submicron range. The resultant short distance between gates is expected to induce significant modifications in the device electrical performances, since the fully depletion condition will be feasible in the body region. Hence, the influence of the fully depleted body on the on-state resistance, threshold voltage, breakdown voltage, parasitic bipolar transistor and internal capacitances are features of particular interest. Furthermore, device reliability aspects, such as hot-carrier and self-heating effects, are evaluated by numerical simulation in trench power MOSFETs for the first time.