Novel lateral double-diffused MOSFET with folded silicon and high-permittivity dielectric breaking silicon limit

Abstract

A novel folded-accumulation LDMOS (FALDMOS) employing high-permittivity (HK) material as the partial field dielectric (HK-FALDMOS) is proposed and investigated by simulation. The device features the high-k dielectric partially replacing conventional SiO2 as the field oxide covering partial drift region and the gate electrode extending to the drain electrode. In the ON-state, the majority-carrier accumulation effect of HK-FALDMOS is more intense than that of FALDMOS, which is attributed to the larger capacitance of high-k film with the same dielectric thickness. Besides, a higher doping concentration in drift region I is obtained due to the electric field modulation effect resulting from the employed high-k film, which further reduces the specific on-resistance (Ron,sp) of the drift region I. The breakdown voltage (BV) declines slightly with the increase of permittivity of high-k film. Simulation results show that the proposed HK-FALDMOS has best-in-class Ron,sp-BV performance (9.9 mΩ mm2 with BV of 44.9 V when the relative permittivity of high-k is 8), which breaks the silicon limit of LDMOS.