Mechanisms for single-particle latchup in CMOS structures

Mechanisms for single-particle latchup are investigated for several different CMOS processes, placing particular emphasis on factors that affect latchup triggering. The results show that the spacing between the well and substrate is less important than the geometry of well contacts in determining latchup susceptibility. Substrate characteristics also play an important role. A bulk p-well process was found to be far more resistant to latchup than a comparable bulk n-well process because of lower charge collection efficiency and higher doping concentration in the p-well