Simultaneous measurement of refractive index and thickness of thin film by polarized reflectances

Abstract

For the design and fabrication oioptical and semiconductor devices, an accurate and simple measurement of the refractive index and the thickness of a thin film is important. Ellipsometry is an accurate and popular technique, but for thick films, the order of thickness periodicity has to be known to obtain the ext value'. This limitation can be overcome by multi-angle of incidence ellipsometry2, but it needs more complicated apparatus and more involved data analysis than fixed angle ellipsometry. In this paper, we propose a new technique to determine the refractive index and the thickness of a thin film simultaneously by using the polarized reflectances which are measured at oblique incident angles, which we call PRETTI method (Polarized REflectances measurement Technique for Thickness and Index). First,we explain the new algorithm to determine the refractive index and the thickness of a thin film,and then the measurement results on a single layer film and a double layer film are mentioned.