Optimization and Elimination of Parasitic Latchup in Advanced Smart-Power Technologies

This paper examines CMOS latchup immunity for a wide range of structures in a 0.25 mum smart-power technology. The impact of logic ground isolation from the substrate and the presence p
⁺
and n
⁺
buried layers below the logic wells is quantified. Four different types of structures have been studied and it is demonstrated that certain ion-implantation layers that are inherently available in a standard deep submicron smart-power process due to medium and high-voltage requirements can be effectively utilized to optimize and improve the latchup performance of standard CMOS.