Extraction of the oxide thickness using a MOS structure quantum model for SiO2 oxide <5 nm thick films

In this paper, we present a full quantum model of metal oxide semiconductor capacitance based on a self-consistent resolution of Schrödinger and Poisson equations. The model is used in accumulation to extract the oxide thickness of N+ polycrystalline silicon–SiO2–P silicon capacitors in the range 2–5 nm. The extraction results are in agreement with reference ellipsometric measurements to <±4%. We also show the necessity of a quantum computation of the gate capacitance for high substrate doping and low oxide thickness. The influence of the tunneling current is also discussed.