An L-Shaped Trench SOI-LDMOS With Vertical and Lateral Dielectric Field Enhancement

Abstract

For the first time, we report a novel L-shaped trench LDMOS on silicon-on-insulator with double (lateral and vertical) enhanced dielectric field (ENDIF) (DENDIF) effect. This device features an L-shaped trench for accumulating charges (mainly, ionized charges) to enhance lateral breakdown voltage (BV). Then, the vertical ENDIF can be self-adaptive to the lateral ENDIF due to the lumped charges (mainly, inversion charges) at the interface of the buried oxide/silicon. The L-shaped trench makes the potential contours as tree roots, which can spread into the folded drift region to prevent premature breakdown in silicon. The simulated results of the DENDIF LDMOS show that the electric field in the dielectric layer is >; 200 V/μm, the gate-drain charge density (Q <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">gd</sub> ) is 0.39 nC/mm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> , and the Baliga's figure of merit [(FOM); FOM = BV <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> /R <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">ON,sp</sub> ] is 11.9 MW/cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> .