A simultaneous volumetric thickness-profile measurement method based on an acousto-optic tunable filter for transparent film deposited upon pattern structures is described. The nondestructive thickness profilometer prevents the destruction of samples such as one encounters in using a scanning-electron microscope and provides good accuracy. The information on the volumetric thickness profile is obtained through least-squares fitting with a phase model, , which has three unknowns: surface profile , thickness , and an indeterminate initial phase offset. Accurate phase information in the spectral domain can be obtained by introduction of the concept of spectral carrier frequency. Experimental results for a metal patterned sample show that the volumetric thickness profile can be determined within an error range of .
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