薄膜光学常数和厚度的测量方法及技术研究

Research on Measurement Methods and Techniques for Optical Constants and Thickness of Thin Films

详细介绍了基于光谱拟合反演薄膜参数的方法,得到了简化后的薄膜-基底光学系统的透射率公式,借助Cauchy模型,建立了光谱拟合评价函数。采用改进型遗传算法得到Si薄膜在500~800nm波长范围内的光学常数和厚度,结果表明,薄膜折射率和厚度的计算精度较高,平均误差仅为0.1%和0.2%,而消光系数的误差也能控制在10%左右。该方法具有操作简单、计算速度快、结果精确等特点。

This article provides a detailed introduction to the method of inversion of thin film parameters based on spectral fitting,obtaining a simplified transmittance formula for the thin film substrate optical system.With the help of the Cauchy model,a spectral fitting evaluation function is established.The simplified transmittance formula of the thin film substrate optical system is obtained,and a spectral fitting evaluation function is established using the Cauchy model.The improved genetic algorithm was used to obtain the optical constants and thickness of Si thin films in the wavelength range of 500~800 nm.The results showed that the calculation accuracy of the refractive index and thickness of the films was high,with average errors of only 0.1%and 0.2%,and the error of extinction coefficient could also be controlled around 10%.This method has the characteristics of simple operation,fast calculation speed,and accurate results.