氧分压影响中频磁控溅射沉积SiO_2薄膜光学性能研究

Study on impact of oxygen partial pressure on the optical properties of SiO_2 thin film deposited by medium frequency magnetron sputtering

采用中频反应磁控溅射沉积非晶二氧化硅(a_SiO2)薄膜,用X射线衍射、原子力显微镜、傅里叶红外光谱等方法研究氧分压影响退火前、后的两种SiO2薄膜样品的微观结构、折射率和消光系数等特性的变化规律。结果显示:室温下,沉积速率随氧分压的增大而减小,有利于提高薄膜的光滑性和致密度;在不同氧分压下沉积的SiO2薄膜均为非晶态结构;氧分压为25%时,薄膜表面具有均匀、光滑、致密的性能特征;折射率和消光系数都依赖于氧分压,氧分压大于15%时,薄膜在600 nm处的折射率n约为1.45～1.47,消光系数低于10-4。这表明适当提高氧分压有利于获得光学性能较好的SiO2薄膜。傅里叶红外吸收光谱测试表明,随着氧分压的升高,Si-O-Si伸缩振动峰向高波数方向移动,较高氧分压下沉积的SiO2薄膜具有较高的化学结合能,且结构和性能更稳定。

Medium frequency reactive magnetron sputtering was used to deposit amorphous silica （a_SiO2） film, X-ray diffraction methods, atomic force microscopy, Fourier transform infrared spectroscopy are applied to study the impact of oxygen partial pressure on the microstructure, refractive index and extinction coefficient of Si02 film sample before and after annealing. The results showed that： at room temperature, the deposition rate decreases with the increase of the oxygen partial pressure, which helps to improve the smoothness and the density of the film. Under different oxygen partial pressures, the deposited films are amorphous SiO2; at an oxygen partial pressure of 25%, the film surface has an uniform, smooth, dense performance characteristics. The refractive index and extinction coefficient are dependent on the oxygen partial pressure. When the oxygen partial pressure is greater than 15%, the film refractive index is in a range of about 1.45 to 1.47 at a 600-nm wavelength, the extinction coefficient is less than 10^-4. This suggests that an appropriate increase in oxygen partial pressure is conducive to get a better optical performance SiO2 film. Fourier transform infrared absorption spectra shows when the oxygen partial pressure increases, Si-O-Si stretching vibration is shifted to higher wave number. At higher oxygen partial pressure, SiO2 films is deposited with high chemical binding energy, and the structure and performance is more stable.