【摘要】 结合激光外差干涉法和透射式椭偏测量原理,研究了一种快速、高精度测量纳米厚度薄膜光学参数的方法.给出了光学系统设计和理论分析,使用两个声光调制器产生20 kH z的差频,直接比较平行分量和垂直分量外差信号的幅值和相位,得到所需要的椭偏参数.光束偏振态的椭圆化及偏振分光不完全所引起的非线性误差是影响纳米薄膜测量精度的主要因素,推导出椭偏参数非线性误差的近似解析表达式,计算结果表明由此导致的膜厚测量误差可达几个nm,相对而言,激光器和反射镜等器件产生的光束椭偏化是其主要原因.更多还原

【Abstract】 Based on the optical heterodyne interferometer and transmission ellipsometry, a new fast measurement technique of nanometer film was presented computational. the optical configuration was designed and theoretically analyzed, it adopted two acoustooptic modulators to generate a beat frequency of 20 kHz, and direct comparison method of the amplitudes and phases between -%p-%-polarized and -%s-%-polarized signals to obtain the ellipsometric parameters. The nonlinearity error mainly results from the elliptic polarization of the beam and the unsatisfied extinction rate of the polarized-beam-splitter. The approximate analytical form of the ellipsometric parameters’ nonlinearity error was deduced, the computational results show resulting error is of several nanometers in thickness measurement, and comparatively the elliptic polarization of the beam produced from laser, mirrors and other optical elements is mainly responsible for the error.更多还原