Patent ID: 6734982
Filing Date: 2004-05-11
Classification: G01B

Abstract:
A method for measuring a thickness of a structure, the structure comprising an overlying film and an underlying film, positioned on a substrate, where a thickness of the overlying film decreases until a section of the underlying film is exposed, comprising of:exciting an acoustic component corresponding to the overlying film in a first portion of the region using at least one excitation laser beam; detecting the acoustic component with a device that irradiates the region with a probe to generate a signal beam; analyzing a time-dependent feature of the signal beam corresponding to the acoustic component, to determine a thickness of the overlying film in the first portion of the region; translating the structure or the excitation and probe beams; and repeating the exciting, detecting, and analyzing steps to determine a thickness of the overlying film in a second portion of the region; wherein the exciting, detecting, analyzing and translating are repeated until the thickness of the overlying film is measured from where the underlying film is exposed.