基于偏振光反射多点法测量薄膜参数

Thin Film Parameters Based on Polarized Light Reflected from the Multi-Point Measurement

依据偏振光反射原理和多角度测量的多点拟合算法,实现了对薄膜材料折射率和厚度的精确测量。将高准直半导体激光入射到薄膜样品与空气分界面上,逐步旋转样品或改变样品表面的入射角,得到待测样品的反射率随入射角变化曲线。在曲线上取不同入射角处所对应的反射率,根据计算公式求解出多组薄膜厚度和折射率。利用已测量的多组反射率与求解出的薄膜参数相应反射率拟合后可确定出薄膜参数最优解。在求出的薄膜参数附近拓展一定范围再次拟合,可求出更精确的薄膜参数。基于此方法测量了SiO2薄膜的折射率和厚度,测量折射率误差不超过0.3%,厚度误差不超过0.07%。

Based on the reflection principle of polarized light and measurement of multi-angle multi-fitting algorithm, the accurate measurements of the refractive indexes and thicknesses for the film materials are achieved, When highly collimated diode laser incidents on the interface between thin films and air, the curve of reflectivity varying with the incident angle is obtained by gradually rotating the sample or changing the incident angle of the sample surface. Multiple solutions of film thicknesses and refractive indexes can be solved by using reflectivities from the different angles in this curve based on calculation formula. Its optimal solution can be determined by fitting measuring and corresponding computational reflectivities. By multiple expanding the scope of the film parameters and then fitting them, more accurate film parameters can be found out, The refractive index and thickness of the SiO2 film are measured using this method, of which error of refractive index is less than 0.3 % and thickness error is less than 0.07 %.