Numerical modelling of mechanisms involved in latchup triggering by a laser beam

The use of a laser beam is a well-known technique to trigger latchup parasitic structures in ICs. Numerical analyses of this phenomenon are brought into play to study its sensitivity when a continuous wave laser as well as pulsed lasers are used. The impact location is also studied to demonstrate that different mechanisms are involved in the triggering phase of latchup. The structure is more sensitive to blue light when it is directed over the well-substrate junction, while it is more sensitive to infrared light elsewhere. When using a CW laser, curves giving the power supply current versus the photo-induced current provide direct information on the parameters of the parasitic structure