利用椭圆偏振光谱进行薄膜样品的测量数据分析拟合时, 薄膜厚度与介电常数通常具有一定的关联性。不同色散模型的选取也会对拟合结果产生明显的影响, 引起较大误差。介绍了唯一性检测在椭偏拟合中的实现方法。并以二氧化钛样品为例, 利用唯一性检测对比了不同色散模型、不同厚度、不同测量波段、不同入射角度时的唯一性检测结果。结果表明, 唯一性检测能够有效标定出椭偏测量和拟合过程中所产生的误差, 同时能够对不同色散模型进行量化对比, 提升拟合精度。

The thickness and dielectric constants of thin films usually have certain correlation in the fitting procedure of spectroscopic ellipsometry (SE). The choice of different dispersion models may also influence the results and cause errors. As the fitting is influenced by the dispersion models adopted in the analysis, the uniqueness test has been introduced into SE fitting. The results of uniqueness test have been compared with different dispersion models, different film thicknesses, different wavelength ranges and different incident angles using titanium dioxide samples as an example. It is indicated that uniqueness test is efficient in evaluating the fitting for SE measurement. Uniqueness test can also provide quantitative comparison among different dispersion models and contribute to fitting precision.