Circuit Dependent Plasma Charging Effect Robustness in 0.16 um BCD Technology Platform

BCD and High Voltage technologies are addressing an increasingly high number of disparate and peculiar applications. Although different applicative scopes, a very common circuit configuration requires a large device (power MOS) connected to a smaller one (sense-FET, copy MOS) acting as its sensor [1]. This configuration can be very “unbalanced” in terms of metal area and number of vias insisting on the power stage with respect to the sense-FET one. In this paper, the effect of different circuit topologies on n-channel HV MOSFET robustness against plasma charging is studied. Particular focus was given to the circuital block indicated above, showing that in this configuration the small HV MOS is the most critical element. By tuning the diffusion process and by using large antennas, plasma damage was amplified and its effect applied on a number of realistic circuits. These different blocks allowed us to identify the factors leading to plasma damage and to provide a qualitative model that explains the plasma-related damage propagation. Design rules created ad-hoc should be implemented to avoid the occurrence of this circuit-dependent plasma effect.