Drift Layer Design utilizing Intermediate Boron Ion-implantation for 100-V-class Two-step-oxide Field-Plate Trench MOSFET to Improve Switching Loss

We studied an advanced drift layer design which has an intermediate layer in mesa region for two-step-oxide field-plate MOSFET. The intermediate layer is formed by a high energy ion-implantation via source contact window. By TCAD simulation, it was confirmed the intermediate layer can decrease depletion layer capacitance in lower drain voltage. There was no change of breakdown voltage, and on-resistance (R ON A) increased slightly with increasing the implantation energy. An attractive effectiveness was obtained as gate-drain charge (Q GD ) decrease, and output charge and reverse recovery charge were slightly decreased. Evaluated performances showed that the Q GD and R ON Q GD were reduced by 14.1% and 10%, respectively. In power loss estimation of an assumed circuit, it was observed the newly designed FP-MOSFET can improve total power loss, especially in high-speed switching.