Identification and suppression of defects responsible for electrical hysteresis in metal-nitride-silicon capacitors

Abstract

An attempt was made to correlate the hysteresis in high frequency capacitance-voltage (C-V) measurements on metal-nitride-silicon (MNS) capacitors and spin density measured by electron spin resonance (ESR) spectrometry on a series of silicon-rich and nitrogen-rich silicon nitride films deposited by plasma enhanced chemical vapor deposition (PECVD). We found that the hysteresis ΔVH in the C-V characteristics can be divided into ΔV+, which corresponds to negative charge trapping, and ΔV-, which corresponds to positive charge trapping. A one-to-one correlation was found between ΔV+ and the spin density attributed to the silicon dangling bond. The observations support the hypothesis that besides the silicon dangling bond, which can be suppressed by using nitrogen-rich films instead of silicon-rich films, there is another important type of defect probably at the nitride-silicon interface, which can be suppressed by an appropriate ammonia plasma treatment.