A lateral DMOS with partial buried-oxide layer to achieve better RESURF effect

A novel lateral double diffused MOSFET (LDMOS) structure with partial buried-oxide layer under the n-drift region, which is suitable for the bulk silicon epitaxial process, is proposed. The introduction of the buried-oxide layer produces an inversion layer at buried-oxide/p-sub interface and achieves better reduced surface field (RESURF) effect comparing with the conventional device with buried-pwell. Moreover, the buried-oxide can prevent the impurity diffusion and improve the doping concentration of the ndrift region. As a result, the proposed structure improves the breakdown voltage about 12% and increases the current capability over 30% at the same time.