Partial-SOI high voltage laterally double-diffused MOS with a partially buried n⁺-layer

A novel partial silicon-on-insulator laterally double-diffused metal-oxide-semiconductor transistor (PSOI LDMOS) with a thin buried oxide layer is proposed in this paper. The key structure feature of the device is an n⁺-layer, which is partially buried on the bottom interface of the top silicon layer (PBNL PSOI LDMOS). The undepleted interface n⁺-layer leads to plenty of positive charges accumulated on the interface, which will modulate the distributions of the lateral and vertical electric fields for the device, resulting in a high breakdown voltage (BV). With the same thickness values of the top silicon layer (10 μm) and buried oxide layer (0.375 μm), the BV of the PBNL PSOI LDMOS increases to 432 V from 285 V of the conventional PSOI LDMOS, which is improved by 51.6%.