Study of ultra-low specific on-resistance and high breakdown voltage SOI LDMOS based on electron accumulation effect

Abstract

A novel stepped L-shaped trench gate silicon-on-insulator (SOI) lateral double-diffused metal oxide semiconductor field-effect transistor (LDMOS) with N-pillar (SLTGN-LDMOS) is proposed. SLTGN-LDMOS contains a highly doped N-pillar, assisting in reducing the specific on-resistance (R on,sp). The stepped L-shaped trench gate (SLTG) attracts electrons to attach to the edge of the trench, thus directing more current to flow along the edge, which decreases R on,sp effectively. Furthermore, new electric field peaks are generated on the surface of the drift region, thus increasing the breakdown voltage (BV). As a result, compared with the conventional structure (C-LDMOS), the BV of SLTGN-LDMOS increases from 63 V to 162.7 V, and the R on,sp decreases from 1.85 mΩ·cm2 to 1.46 mΩ·cm2. Then, the figure of merit (FOM1, BV2 /R on.sp) increases remarkably from 2.15 MW·cm−2 to 18.13 MW·cm−2. In addition, the maximum surface temperature of SLTGN-LDMOS is 395.3 K, slightly lower than the 398.7 K of C-LDMOS.