Advanced Dram Cell Dielectric Films using Rapid Thermal Processing

Abstract

ABSTRACTThe reliable operation of a dynamic random access memory (DRAM) device requires a minimum level of charge to be stored in the capacitor. The nonlinear dependence between the scaling of the minimum charge and the cell area for higher DRAM densities is the driving force in the development of exotic capacitor structures and advanced cell dielectric materials. The conventional option of reducing the thickness of the silicon nitride dielectric films for high density DRAM applications will eventually be constrained by the increase in the leakage current due to direct carrier tunneling or by the decrease in the oxidation resistance of the films.In this paper we discuss the use of rapid thermal processing to modify the interface between the polysilicon storage node of the capacitor and the silicon nitride to improve the electrical and structural characteristics without any loss in capacitance. The influence of electrode roughness on the electrical behavior will also be discussed for the various dielectric stack combinations.