A novel super-junction trench gate MOSFET fabricated using high aspect-ratio trench etching and boron lateral diffusion technologies

We propose a super-junction trench gate MOSFET (SJ TGMOSFET) which is fabricated with a simple p-pillar forming process using deep trench and boron silicate glass (BSG) doping process technologies to reduce the process complexity. The p-pillar region is formed through lateral boron diffusion from BSG film and annealing process after the silicon deep etching. For the SJ TGMOSFET fabricated with BSG lateral diffusion, the controls of the boron concentration and the profile are important to achieve the charge balance between p-and n-pillars. Throughout the various boron doping experiments as well as process simulation, we optimize process conditions related with p-pillar depth, BSG doping concentration and diffusion temperature. Due to the trenched p-pillar, the potential of the SJ TGMOSFET more uniformly distributes and widely spreads into the bulk region of the n-drift layer comparing to the conventional TGMOSFET. The measured breakdown voltage of SJ TGMOSFET increases at least 28% than that of the conventional TGMOSFET.