Influence of chlorine on the memory characteristics of MONOS device with Plasma-Enhanced atomic layer deposited Si3N4 charge trap layer

Abstract

For improving the performance of flash memory, the vertical and lateral scaling of the device structure is needed. Particularly, the effective scaling down of metal-oxide-nitride-oxide-semiconductor (MONOS) devices, the cell component, requires development of a deposition strategy for the charge trapping layer (CTL) and an understanding of charge loss mechanisms and data retention features. In this study, we have investigated the influence of chlorine (Cl) in MONOS devices, including plasma-enhanced atomic layer deposition (PEALD) Si3N4 films as CTL. To assess the influence of Cl on the CTL, we fabricated the memory device with varying amounts of Cl introduced, comparing the experimental conditions and analyzed the memory characteristics in samples. Quantitative analysis was extracted to investigate causes of Cl within CTL. Additionally, memory characteristics were secured through electrical analysis methods such as capacitance - voltage (C-V) and leakage current voltage (I-V) methods. We have confirmed that Cl-related traps have shallow trap levels, resulting in the passivation of Si dangling bonds and suppressing the trapping of electrons. Hence, we propose process improvements to establish superior trap layer properties through the suppression of Cl generation.