Novel High-K SOI LDMOS with N+ Buried Layer

A novel high-K dielectric trench SOI LDMOS with an interface highly doped N buried layer (HKHN SOI LDMOS) is proposed. The devices are characterized with a high-K dielectric material (HK) introduced in the drift region and a high doping concentration of N existed below the HK trench (HKHN). First, the HK material causes assistant depletion in the N-drift region to increase doping concentration of the drift region (Nd) and further improve the electric field (E-field) distribution. Second, the highly doped N buried layer below the interface of the HK trench can provide a low on-resistance passage and shorten the ionization integral path to enhance bulk field (ENBULF). Both the high drift region doping concentration and low on-resistance passage can reduce the specific on-resistance (Ron,sp). Meanwhile, a higher breakdown voltage (BV) can be obtained by an optimized electric field distribution and a shortened ionization integration path. The new device can achieve high BV, low Ron,sp and excellent figure of merit (FOM = BV2/Ron,sp). The BV of the HKHN SOI LDMOS is 552 V with Ron,sp of 29.46 mΩ cm2 and FOM of 10.343 MW cm−2.