Development of a compact spectral thickness measurement instrument for thin film
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摘要: 为了开发一种用于测量各向同性均匀薄膜介质厚度的紧凑型薄膜测厚仪,采用了共光路垂直入射设计,利用薄膜干涉原理,通过非线性优化算法对反射光谱进行了拟合,反演计算出了薄膜样品的厚度。采用该仪器测量部分SiO2/Si薄膜样件,测量结果与商业椭偏仪测量结果之间的相对偏差小于0.5%,而单次测量时间仅为70ms。结果表明,该薄膜测厚仪具有对测量距离不敏感、光路简洁、结构紧凑及重复性精度良好等优点,对实现在线实时测量功能具有积极意义。Abstract: In order to develop a compact instrument to measure the thickness of isotropic uniform thin films, applying a common normal incident path and thin-film interference principle, the film thickness was calculated inversely by fitting the measured reflectance spectrum with nonlinear optimization algorithm. The relative error between the thickness of a SiO2/Si thin film measured by the proposed instrument and that measured by the commercial ellipsometer was less than 0.5%, and the time for a single measurement was about 70ms. Experimental results show that the proposed instrument has advantages of insensitivity to measuring distance, concise light path, compact structure and excellent repeatability. The study has great significance for online measurement of thin film thickness.
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