An Improved Superjunction Structure With Variation Vertical Doping Profile

An analysis of an improved superjunction structure with variation vertical doping profile (VVD-SJ) is presented in this brief. It features a better tradeoff between breakdown voltage (BV) and specific ON-resistance (
$R_{\rm on}$
) than the prior art, due to a higher average doping concentration in columns. A simple 2-D electric field model of the VVD-SJ structure is derived based on charge superposition principle. Optimized results show that the specific ON-resistance of the VVD-SJ structure is reduced by
$\sim 10$
%, compared with the SJ one under the same BV and aspect ratio. The mainstream multiple epitaxial growth and implantation technology is suitable to fabricate the VVD-SJ power MOSFET without extra process cost.