Research

Plasma treatment with various gases can modify thin film properties such as work function, band gap, crystal defects, and doping density. For example, plasma treatment can modify the work function of a thin film by changing the material composition on the surface, which can affect the threshold voltage of the thin-film transistor and the contact resistance of the metal-semiconductor junction. Plasma treatment can have a complex effect on the material properties of thin films, and the specific changes that occur depend on treatment parameters such as injected gas, pressure, and power for plasma generation and ion control. In particular, the density of plasma can be controlled by the upper RF power, and the bias voltage of the substrate can be controlled by the bottom RF power in the high-density plasma system. The density of the plasma affects the temperature inside the chamber and the substrate, and the bias voltage of the substrate determines the movement of ions in the plasma.

 In our laboratory, we are observing changes in the properties of thin films due to plasma treatment and exploring ways to improve the performance of semiconductor devices through the plasma process.