Latchup is caused by parasitic npnp structures. It happens for both polarities if the respective junctions are present, probably with different thresholds.
Hi @FvM ,
Shouldn't it be primarily from majority carrier injection? For e.g., in the case of powerfets in powerconverter chips, high side powerfet injects holes into the p-substrate which are majority carriers in psub. Likewise, low side powerfet injects electrons into the nwell.