A dual-trench silicon on insulator high voltage device with an L-shaped source field plate

To improve the breakdown voltage and reduce the specific on-resistance of a small size silicon on insulator (SOI) device, a dual-trench SOI high voltage device with an L-shaped source field plate is proposed. The device has the features as follows: first, a trench gate is adopted. The trench gate widens the current conduction area and makes the current conduction path shorter, thus lowering the specific on-resistance. Second, a SiO2 dielectric layer is introduced into the drift region. This dielectric layer can hold a high electric field, which makes the breakdown voltage greatly increased. Third, an L-shaped source field plate is introduced. This field plate modulates the electric field in the drift region, so increases the optimized doping concentration of the drift region significantly and reduces the specific on-resistance. The results from the two-dimensional semiconductor simulator show that as compared with a conventional SOI device at the same cell pitch, the breakdown voltage is increased by 151%, and the specific on-resistance is reduced by 20%. The specific on-resistance is reduced by 80% at the same breakdown voltage. Compared with a dual-trench SOI device with the same cell pitch, the proposed device maintains the same high breakdown voltage as the dual- trench SOI device, and at the same time, the specific on-resistance is decreased by 26%.