3D profiling of a transparent film using white-light interferometry

In the vertical scanning white-light interferometry, two peaks appear in the interference waveform if a transparent film exists on the surface to be measured. An algorithm has been developed that can detect the position of those peaks quickly and accurately, and a "film profiler" has been put into practical use, which is able to measure both the profiles of front and back surfaces and the thickness distribution of a transparent film simultaneously. This technique is applicable to transparent films with the optical thickness of approximately 1 /spl mu/m or greater, and it is used effectively in semiconductor and LCD manufacturing processes.