采用乙烷气体辉光放电法在单晶Si衬底上制备了名义厚度分别为75,150和250 nm的类金刚石碳(DLC)薄膜,除沉积时间外其他工艺参数完全一致。使用可变入射角光谱型椭偏仪(VASE)测量了380-1700 nm波段的椭偏谱。该研究发现,对单一DLC样品的椭偏数据进行分析时,一定的范围内,假定不同的薄膜厚度均可以得到非常好的拟合结果。结果表明,采用单样品椭偏法拟合时,厚度与光学常数呈现出强烈的关联性,无法快速获得准确的结果。采用多样品椭偏法,对三个样品建立相同的物理模型,假定他们的光学常数相同,进行数据拟合。分析发现该方法可以快速、简便地获得精确的折射率、消光系数以及厚度值。经过检验,结果具有非常好的唯一性。

Using the glow discharge technology with acetylene reactive gas,the diamond-like carbon films with different nominal thicknesses are deposited on Si substrate with the identical process.Variable angle spectroscopic ellipsometry (VASE) is used to characterize the film optical constants at the wavelength range of 380-1700 nm.Given the various selected film thickness,the different optical constants of refractive index and extinction coefficient of sbsorbing films,showing good consistency between the calculated and experimental data,could be obtained based on single sample ellipsometric fitting method.This result indicates that it is generally rather difficult to determine the refractive index and extinction coefficient of absorbing films accurately and rapidly due to the strong correlations between thickness and optical constants.A new multiple sample analysis method is put forwarded to solve this problem.Assume that the optical properties are same for the used three samples of DLC films with various deposition time,the accurate optical constants and related thickness of each sample could be determined rapidly even without any predicted dispersion models.Meanwhile,this new method can be used both for the transparent substrate and non-transparent substrate with absorbing films.