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

This brief presents the minimum specific on-resistance <inline-formula> <tex-math notation="LaTeX">${R}_{\min ,\text {SiC}}$ </tex-math></inline-formula> 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 <inline-formula> <tex-math notation="LaTeX">${V}_{\text {B}}$ </tex-math></inline-formula> design In the<sc>off</sc>-state, <inline-formula> <tex-math notation="LaTeX">${R}_{\min ,\text {SiC}}$ </tex-math></inline-formula> optimization achieves the minimum specific on-resistance <inline-formula> <tex-math notation="LaTeX">${R}_{\text {on},\text {sp}}$ </tex-math></inline-formula> in shorter SJ length and lower SJ doping concentration, resulting in reduced process complexity and wider process tolerance. Based on this study, a new <inline-formula> <tex-math notation="LaTeX">${R}_{\text {on},\text {sp}}~\propto ~{V}_{\text {B}}$ </tex-math></inline-formula> relationship and corresponding design formula are obtained for 4H-SiC SJ. It is shown that <inline-formula> <tex-math notation="LaTeX">${R}_{\min ,\text {SiC}}$ </tex-math></inline-formula> optimization has the potential to significantly improve the reported <inline-formula> <tex-math notation="LaTeX">${R}_{\text {on},\text {sp}}$ </tex-math></inline-formula> characteristics by 77%–92% at the same <inline-formula> <tex-math notation="LaTeX">${V}_{\text {B}}$ </tex-math></inline-formula>, providing a significant margin for further optimization.