The Minimum Specific On-Resistance of 4H-SiC Superjunction Devices

This brief presents the minimum specific on-resistance
${R}_{\min ,\text {SiC}}$
of balanced symmetric 4H-silicon carbide superjunction (4H-SiC SJ) devices based on the resistance well (
R
-well) model. The
R
-well of 4H-SiC SJ is modified by considering both the anisotropy of impact ionization in the off-state and carrier incomplete ionization and JFET effect under the on-state conditions. Compared with the conventional model that only considers the breakdown voltage
${V}_{\text {B}}$
design In the
off
-state,
${R}_{\min ,\text {SiC}}$
optimization achieves the minimum specific on-resistance
${R}_{\text {on},\text {sp}}$
in shorter SJ length and lower SJ doping concentration, resulting in reduced process complexity and wider process tolerance. Based on this study, a new
${R}_{\text {on},\text {sp}}~\propto ~{V}_{\text {B}}$
relationship and corresponding design formula are obtained for 4H-SiC SJ. It is shown that
${R}_{\min ,\text {SiC}}$
optimization has the potential to significantly improve the reported
${R}_{\text {on},\text {sp}}$
characteristics by 77%–92% at the same
${V}_{\text {B}}$
, providing a significant margin for further optimization.