Effect of 2 MHz frequency power applied to the substrate for low-temperature silicon nitride thin film deposition

Silicon nitride (SiNx) thin films were deposited at a low temperature of 80 degrees C using a dual-frequency plasma-enhanced chemical vapor deposition (PECVD) equipment. The density of the thin film was increased by 17% by increasing the low-frequency (LF) power of 2 MHz applied to the lower electrode to 100 W separately from the plasma generated by the 180 W power of 13.56 MHz applied to the upper electrode. The advantage of this dual-frequency PECVD process is that even if it is deposited at a low temperature, it shows similar effects to high-temperature deposition or post-deposition annealing process. Due to the LF power applied to the substrate, the hydrogen concentration in the deposited SiNx thin film decreases, which in turn leads to an increase in the film density. The increase in SiNx thin film density eventually results in a 21% increase in dielectric constant. It was shown that the use of SiNx thin films with improved properties as a dielectric layer of a thin film transistor can increase mobility and on-off ratio and reduce leakage current and subthreshold swing of the transistor.

Automated summary

Depositing silicon nitride (SiNx) thin films at low temperature using dual-frequency PECVD process can improve the film density and dielectric constant, thereby enhancing the performance of thin film transistors.