Super Junction Lateral Double-Diffused MOSFET with Ultra-low Specific on-Resistance Completely Eliminating Substrate Assisted Depletion Effect

In this paper, a novel Super Junction (SJ) Lateral Double-diffused MOSFET (LDMOS) is proposed. The two sides of the device substrate are connected with source-drain electrodes through ohmic contacts, so that the lateral voltage of the substrate is the same as the SJ layer, and they are independently depleted, therefore the SJ layer forms a more ideal rectangular electric field distribution. The surface of the substrate is completely depleted by the extended P-well and N buffer layer, forming an electric field distribution similar to the SJ layer, making the upper and lower potentials of the substrate surface equal. After the two layers are in contact, the electric field distribution of SJ layer will not be changed by the substrate, and finally the SAD effect can be completely eliminated. Simulation results show that the breakdown voltage ( BV ) of the conventional SJ-LDMOS device with N -type buffer layer is 362.5 V when the drift region length is 20 μm, and the specific on-resistance ( R on,sp ) is 29.04 mΩ·cm 2 . Under the same drift region length, the new SJ-LDMOS has a BV of 470.7 V and a R on,sp of 11.28 mΩ·cm 2 . The new device can reduce the R on,sp by 61.16% while increasing the BV of 108.2 V. Finally, the figure of merit ( FOM ) value was increased by 339%. The fabrication process of the proposed device is compatible with the current mainstream silicon-based processes with relatively low-cost process difficulty, which is more conducive to high power electron applications and productions.