Modeling and characterization of deep trench isolation structures

In this paper, we present a simple equivalent electrical circuit model and sidewall interface characterization results for a deep trench isolation structure. The trench structures used in the study consisted of n-silicon/undoped trench/n-silicon. The trenches were filled with undoped polycrystalline silicon and the trench sidewall was lined with thermal oxide and a deposited silicon nitride. The capacitance-voltage characteristics across the trench were measured and compared against the model predictions. The circuit model includes the effect of the space-charge region and recombination-generation currents in the undoped polycrystalline silicon trench fill material. The Terman method was used to extract the silicon/oxide sidewall interface density and the mid gap value was found to be less than 10^-10 #/cm²-eV.