Fast surface profiling by spectral analysis of white-light interferograms with fourier transform spectroscopy

We present a fast white-light interference method for measuring surface depth profiles at nanometer scales. Previously reported white-light profilers have relied either on path difference scanning or on spectral analysis of the reflection from a fixed interferometer. We show that by performing this spectral analysis with an imaging Fourier transform spectrometer, the high speed of spectral techniques may be combined with the simple data interpretation characteristic of the scanning method. Giving experimental results from a profiler based on this principle, we show that real-time visualization of surface profiles is possible and we report measurements with a repeatability of approximately 5 nm rms. We also demonstrate good agreement with stylus profiler measurements.