Characteristics of Silicon Nitride Deposited by Very High Frequency (162 MHz)-Plasma Enhanced Atomic Layer Deposition using Bis(diethylamino)silane.

Silicon nitrides deposited by capacitively coupled plasma (CCP)-type plasma enhanced atomic layer deposition (PEALD) are currently applied to nanoscale semiconductor devices and are investigated for potential applications to flexible displays, etc. and, during PEALD, 13.56MHz rf power is generally employed for the reactive gas plasma generation. In this study, the effects of a higher plasma generation frequency of 162 MHz on the plasma characteristics and silicon nitride film characteristics were investigated for the silicon nitride PEALD using bis(diethylamino)silane (BDEAS) as the silicon precursor and N2plasma as the reactant gas. The PEALD silicon nitride film deposited using the 162 MHz CCP showed better film characteristics such as lower surface roughness, lower carbon percentage, higher N/Si ratio, lower wet etch rate in a diluted HF solution, lower leakage current and higher electric breakdown field, more uniform step coverage of the silicon nitride film deposited in a high aspect ratio trench, etc. compared to the PEALD silicon nitride deposited using the 13.56 MHz CCP. The improved PEALD silicon nitride film characteristics are believed to be related to the higher ion density, higher reactive gas dissociation, and lower ion bombardment energy to the substrate for the N2plasma observed with the 162 MHz CCP compared to that observed with the 13.56 MHz CCP.