Design and High Breakdown Voltage Realization of SOI-LDMOS Devices with Inclined Buried Oxide Layer Structure

This paper proposes a novel SOI-LDMOS device design based on a double-beveled triangular buried oxide (BOX) structure to achieve synergistic optimization of high breakdown voltage (BV) and low on-resistance (Ron). By introducing two axisymmetric right-angled triangular BOX structures beneath the active layer, the lateral electric field distribution is homogenized, effectively enhancing the breakdown voltage. The study demonstrates that this design exhibits significant advantages in modulating the surface electric field of semiconductor devices. Furthermore, the incorporation of high- density charge at the trench interface of the beveled triangular BOX substantially strengthens the electric field within the buried oxide layer. Simulation results indicate that the optimized device achieves a breakdown voltage exceeding 500 V, accompanied by a remarkable improvement in the figure of merit.