A metrology system and method for measuring the thickness of thin-films of semiconductor wafer. This system and method analyze x-ray reflectivity data to determine transmission characteristics of thin-film layers. Based on these transmission characteristics the thickness of the thin-layer can be determined. Unlike some prior systems and methods, the system and method herein does not determine the thickness of the thin-film layer based on a fringe pattern in reflectivity for the thin-film layer. The fact that the system and method herein does not rely the fringe pattern is particularly advantageous in situations where the thin-film layer is of thickness which makes it very difficult to resolve the fringe pattern in the reflectivity data.