Evaluation of a Procedure for the Measurement of Thin Film Thickness by X-ray Reflectivity

摘要

This paper describes an x-ray reflectivity (XRR) procedure for the measurement of the thickness of thin films which was developed using a conventional x-ray powder diffractometer with a solid state detector and the same deconvolution programs used for powder XRD. The standards used in the development and the determination of the precision and reproducibility of the method consisted of three SiO2 standard thin films (200-500 angstroms). The thickness of two of the films were measured by Rutherford backscattering spectroscopy (RBS), variable angle spectroscopic ellipsometry (VASE) and by transmission electron microscopy (TEM). The third standard was analyzed by VASE and conventional ellipsometry. The measurements using other techniques were made in order to compare and obtain an estimate of the accuracy. The results showed that the method is very precise (0.5% standard error), and good accuracy is indicated by the closeness of the values for the thickness as compared to the values obtained by the other techniques. The advantages and disadvantages of the different techniques as compared to XRR are discussed.