溅射法制备多层膜沉积速率的标定

Calibration of deposition rates of multilayer coatings by sputtering depositions

为消除溅射沉积多层膜过程中产生的膜厚随机误差,实现多层膜膜厚的精确控制,提出了一种精确标定薄膜沉积速率的方法。该方法通过对多次实验结果进行最小二乘拟合得到薄膜沉积速率。对随机误差基本特性的分析表明,随着实验次数的增加,沉积速率将逐渐逼近真值。基于这一原理,可以对薄膜的沉积速率进行精确标定,同时提取出膜厚随机误差,进而确定镀膜机的膜厚控制精度,获得精确控制多层膜膜厚所需要的完整信息。选用两种精度不同的沉积设备,采用提出的方法对所制备的多层膜进行了测试。结果表明,多层膜的膜厚控制精度随沉积设备而异:其中低成本的普通镀膜机只能实现0.1 nm的膜厚控制精度;而另一台性能较高的镀膜机的膜厚控制精度优于0.01 nm。

A calibration method for deposition rates of multilayer coatings by sputtering depositions was proposed to eliminate the random thickness errors and to realize the accurate control of film thicknesses.In this method,the deposition rates were acquired by the least square fitting for results of different deposition experiments.An analysis on the basic properties of random variables shows that deposition rates can be converged to the true values in a case that the number of depositions is large enough.On the basis of above principle,accurate deposition rates can be acquired,random thickness errors can be extracted,and the thickness control accuracy of the coating machine can be determined as well.Furthermore,the complete information to realize the accurate control of film thicknesses can be also obtained.Experiments based on this calibration method were carried out by using two deposition systems.Results indicate that control accuracies are different for different deposition systems.The low cost deposition system shows a relative low thickness control accuracy in 0.1 nm,and the other one with high deposition performance could realize the thickness control accuracy in 0.01 nm.