Analyzing simulated and measured optical scatter for semiconductor process verification

We describe an experiment in which the etch depth of a diffraction grating is measured. A simulated experiment is used to develop and calibrate the measurement technique. A scatterometer was used to measure the diffraction patterns of a set of 5 wafers at 14 die locations. The estimator already developed is then used to find the etch depths at the 70 measured locations. Finally, a scanning force microscope is used as a reference method to validate the scatterometer measurements.