New Superjunction LDMOS With $N$-Type Charges' Compensation Layer

Abstract

A new superjunction lateral double diffused MOSFET (LDMOST) is designed with an <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">N</i> -type buried layer in the <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">P</i> -substrate near the drain to suppress the effect of substrate-assisted depletion resulting from <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">N</i> -type charges' compensating charges' imbalance between the pillars of the superjunction layer. By the effect of the electric field modulation, a more uniform surface electric field is obtained by the new high electric field peak introduced by the p-n junction of the <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">P</i> -substrate and <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">N</i> -type charges' compensation layer. The new effect of reduced bulk field is introduced to improve the vertical breakdown voltage (BV) by reducing the high bulk electric field around the drain. Fabricated <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">N</i> -buried SJ LDMOST with a drift region length of 35 mum and a pillar width of 4.0 mum exhibits a specific on resistance of 98 mOmegamiddotcm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> and a BV of 410 V.