Capacitance and current–voltage simulation of EEPROM technology highly doped MOS structures

Abstract

In this work, experimental capacitance (C–V) and current–voltage (I–V) data of electrically erasable programmable read-only memories (EEPROM) technology MOS structures were simulated. A specific test structure called a double-poly MOS capacitor reproducing the different stacked layers of an EEPROM cell state transistor has been used (7.2 nm SiO₂ oxide, highly doped n⁺ substrate). Our aim was to research the most relevant model that allows a reliable extraction of electrical parameters and that could be easily introduced in industrial EEPROM devices simulators. To simulate C–V data, different classical and quantum models for the estimation of the semiconductor charge have been considered. Due to the substrate high-doping level and to the occurrence of Fowler–Nordheim (FN) injection, the available voltage domain for C–V recordings is reduced, which does not allow to distinguish between the different theoretical models predictions. I–V data were simulated using the classical FN model in which the oxide electric field–gate voltage relationship was extracted from the different C–V models mentioned above. Moreover, an iterative procedure we have proposed in a previous study has also been considered. It is shown that all the models lead to very comparable I–V simulations. These results let us conclude that the very time-consuming resolution of Schrödinger–Poisson coupled equations in a complete quantum approach is not necessary and that classical models remain sufficiently precise and reliable.