Goodman A M
Appl Opt. 1978 Sep 1;17(17):2779-87. doi: 10.1364/AO.17.002779.
Optical interference fringe measurements of the thickness of transparent layers can be rapid, accurate, and nondestructive. If the refractive index n of the layer being measured is known, it may be combined directly with interference fringe information to yield the layer thickness t. If, however, n is unknown, the measurement procedure necessarily becomes more complicated. In this paper, a new and simpler optical interference method is presented for the approximate determination of both n and t of a transparent layer on a transparent substrate. The required experimental information is obtained from a single spectrophotometric recording of either the reflectance or transmittance of the layer and its substrate. The theory of the method is presented, and an application of the method to measurements of layers of SIPOS (Semi-Insulating POlycrystalline Silicon) is described. The method requires that the layer being measured must be uniformly deposited on a flat substrate, and it must neither absorb nor scatter the light passing through it. The major approximation inherent in the method is that both the layer and the substrate are assumed to be nondispersive over the wavelength region of interest.
对透明层厚度进行光学干涉条纹测量可以快速、准确且无损。如果被测层的折射率n已知，它可以直接与干涉条纹信息相结合以得出层厚度t。然而，如果n未知，测量过程必然会变得更加复杂。本文提出了一种新的、更简单的光学干涉方法，用于近似确定透明衬底上透明层的n和t。所需的实验信息是通过对该层及其衬底的反射率或透射率进行单次分光光度记录获得的。阐述了该方法的理论，并描述了该方法在测量半绝缘多晶硅（SIPOS）层中的应用。该方法要求被测层必须均匀地沉积在平坦的衬底上，并且它既不能吸收也不能散射穿过它的光。该方法固有的主要近似是假定该层和衬底在感兴趣的波长区域内都是非色散的。
