Double Polysilicon Capacitors in 1 μm Analogue CMOS Technology

In this paper we present a combined experimental and theoretical investigation of the capacitance-voltage behaviour of n⁺ polysilicon/oxide/n⁺ polysilicon (double polysilicon) capacitors. The theoretical models for the capacitance-voltage behaviour are compared to experimental results, and used to predict how the voltage coefficients of the double polysilicon capacitor are influenced by technological factors such as doping concentration and oxide thickness. For the first time the theoretical solution is derived using the complete Fermi-Dirac statistics to account for the degenerate doping levels present in the polysilicon films.