Study On Preparation Of Silicon Carbonitride Films By Plasma Technique

SiCN thin films is a new ternary elements films, it has many good properties, such as high hardness, wide optical band gap, anti-oxidation at high temperature and anti-erosion, and so on. It has wide applications to micro-electron semiconductor, super large-scale integration and computer industry. In this paper, we prepare the SiCN thin films by twined charge chamber microwave ECR plasma enhanced unbalanced magnetron sputtering system, and study the bonds structure and properties of the film.High pure graphite(99.99%) and silicon(99.99%) were used as targets, high pure argon(99.99%) was used as sputtered gas, high pure nitrogen (99.99%) was used as both sputtered and reacted gas. The SiCN films grew on the silicon(100) and quartz were obtained through changing the experiment conditions, such as graphite target bias voltage, silicon target power and the flow ratio of N₂/Ar. The structure and properties of SiCN films were measured by FT-IR, Raman, XPS, Nanoindenter, UV spectrophotometer.The results showed that the processing parameters were very important effects on the films chemical structure, mechanical and optical properties. The carbon content in the films was controlled by changing the graphite target bias voltage. When the voltage was increased from -450V to -650V, the carbon content increased from 19% to 27.1%. But, if the carbon content were too more, the carbon would be exist as graphite phase. Although the C-N bonds were difficult to obtain, the increasing flow ratio of N₂ to Ar led to obtain more sp²C=N and sp¹C ≡N bonds because it increased the collision probabilities between carbon and nitrogen particles. The hardness tests showed that the sp³C-N content was a key factor to the films hardness. The more content of sp³C-N in the films, the higher hardness achieved. The maximum hardness was 25.4GPa. The disorder degree and Si-N content were osculating related to the optical properties of the films. The content of more Si-N structure and the lower disorder degree in the films, the wider optical band gap would be. The maximum optical band gap was 3.2eV. The high energy bombardment was very important to obtain high quality films. This was because that the high energy bombardment increased the films compactability, and then enhanced the mechanical properties.