A New Silicon Accumulation-Mode Trench Bidirectional Switch

Abstract

The bidirectional switch, or bidiswitch, is a key component widely used for battery protection. During charging and discharging of the battery, the bidiswitch should be able to handle sufficient current and to block high voltages all in both the directions. In this work, we propose a new type of silicon bidiswitch: the accumulation-mode trench bidiswitch (AM bidiswitch). Due to aggressive cell dimensions ( $\leq 0.6 \; \mu $ m), both the accumulation-mode field effect and the reduced surface field (RESURF) effect can be adopted, so that no separate p-body connection is required, and consequently, minimal specific on-resistances ( ${R}_{\text {on,sp}}$ ) and even minimal leakage currents ( ${I}_{\text {rev}}$ ) can be obtained. Based on a theoretical framework, an optimization guideline is presented using TCAD simulations. The results show ${R}_{\text {on,sp}}$ values ranging from 3.5 to 10.8 m $\Omega \cdot $ mm2 for stripe (or 2-D) structures and 6.5 to 45.6 m $\Omega \cdot $ mm2 for gate-all-around (GAA) structures, with breakdown voltages (BVs) ranging from 25 to 75 V. For high temperatures ( ${T} = {425} \; \text {K}$ ), the obtained minimal ${I}_{\text {rev}}$ ranges from 0.75 to over 5 mA for the stripe structures and from 0.1 to 0.4 mA for the GAA structures both for an active device area of $1 \; \text {mm}^{{2}}$ .