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椭偏法测试薄膜不能直接得到薄膜的光学参数,需进行数值反演算法近似求解。采用遗传算法,借鉴竞争选择、小生境和适应值调节思想,对选择算子、变异算子、交叉算子三个重要算子进行了适当改进,改进后算法有效防止了“早熟”现象,并搜索到了全局最优,降低了操作者对拟合模型设定初值的要求。在实践上,通过3种拟合方式的结果对比,得到了可靠的某条件下制备的类金刚石薄膜的光学常数,验证了改进遗传算法在拟合薄膜光学常数中的有效性。
The ellipsometry test film can not directly obtain the optical parameters of the film, and the numerical inversion algorithm needs to be approximately solved. By using genetic algorithm, taking competitive options, niche and adjustment of adaptive value as reference, the three important operators of selection operator, mutation operator and crossover operator are improved properly. The improved algorithm can effectively prevent the phenomenon of “premature” , And searches for the global optimum, reducing the operator’s requirement for fitting the initial value of the model. In practice, the optical constants of the diamond-like carbon films prepared under certain conditions are obtained by comparing the results of the three fitting methods, and the effectiveness of the improved genetic algorithm in fitting the optical constants of the films is verified.