Avalanche Characteristic of Vertical Impact Ionization MOSFET (IMOS) Equivalent Circuit Model

Snapback breakdown is the second order effect of avalanche breakdown in a device. Snapback occur when the excess supply voltage and high currents created flow through the device and become unstable. These two breakdowns are used to explain the concept of Vertical Impact Ionization MOSFET (IMOS) in its Equivalent Circuit Model. The equivalent circuit model design consists of MOS transistors that represent the avalanche characteristic, while the Bipolar Junction Transistor represents the snapback characteristics with a generated-hole-dependent base resistance. The part models for parasitic bipolar or BJT is combined with a MOS transistor model to represent the both avalanche and snapback breakdown. The results show that 90% of the analysis of the subthreshold slope value of the circuit simulations is similar to the reference experimental value. Therefore, the equivalent circuit model can be used to represents the behavior of vertical IMOS in circuit environment in terms of simulations. Keywords—Impact Ionization, Vertical IMOS, Planar IMOS, Equivalent Circuit Model, Snapback, Avalanche Characteristic