Patent ID: 7466428
Filing Date: 2008-12-16
Classification: G01B,G01N

Abstract:
1. A method of measuring a thickness of a target thin layer formed on a substrate, the method comprising: generating a reference skew signal spectrum by performing a regression fitting process on data produced with respect to a reference thin layer formed on a reference layer; generating a reference index by processing the reference skew signal spectrum; generating a measured signal spectrum by irradiating a first light off of the target thin layer to produce a first reflected light, and then analyzing the first reflected light; generating a theoretical signal spectrum based on a putative thickness of the target thin layer and physical properties of the target thin layer; generating a target skew signal spectrum as a difference between the measured signal spectrum and the theoretical signal spectrum; computing a reliability index based on the reference index and the target skew signal spectrum; determining whether the reliability index is within a predetermined first desired range; and, selecting the putative thickness of the target thin layer as an actual thickness of the target thin layer if the reliability index is within the first desired range.