 A typical test of a semiconductor wafer would entail the acquisition of spectra from many points on a patterned or unpatterned wafer.The thickness of the deposited films may be calculated from the interference pattern of the spectra.In addition, ultraviolet–visible spectrophotometry can be used to determine the thickness, along with the refractive index and extinction coefficient of thin films as described in Refractive index and extinction coefficient of thin film materials.