A novel substrate-assisted RESURF technology for small curvature radius junction

A novel substrate-assisted (SA) RESURF technology aiming at improving off-state breakdown voltage (BV) of PN junction with small curvature radius is proposed and experimentally demonstrated in this paper. The SA RESURF technology not only realizes small curvature radius in the fingertip region, but also reduces electric field concentration in the curved metallurgical junction. Low-doped P-substrate, which increases depletion of the small curvature radius junction and reduces electric field concentration in the curved metallurgical junction, is adopted in the source fingertip region. Owing to the existence of low-doped P-substrate, the abrupt PN junction with small curvature radius is adjusted to low-doped PN junction with large curvature radius. The SA RESURF technology can be widely applied to lateral high voltage devices with small curved junction, especially to lateral super junction devices. A CBSLOP-LDMOS with the proposed SA RESURF technology has been developed. The experimental results show that the CBSLOP-LDMOS exhibits off-state BV of 700 V and specific on-resistance (R_{on, sp}) of 142 mΩ·cm².