We investigated the characteristics of silicon nitride (SiNx) thin films deposited by remote plasma atomic layer deposition (RPALD) using trisilyamine (TSA) and ammonia (NH3) plasma at low temperatures. Although the process window of SiNx thin films is 150–350 °C, considering the refractive index (RI), SiNx thin films deposited at 250–350 °C were focused on for analyses. All of the SiNx films were nearly stoichiometric, regardless of the deposition temperature. As the deposition temperature increased, the RI increased, while the hydrogen content decreased. The defect density also changed at higher deposition temperatures; as the deposition temperature increased, all of the trap densities increased because of the low-hydrogen content in the SiNx thin films. The characteristics of the SiNx thin film deposited by RPALD could be controlled to adjust the defect density for charge trap flash memory applications by changing the deposition temperature.