In this paper, three different types of spectral scatterometry hardware are compared using Timbre Technologies' Optical Digital Profiler (ODP) as a common software platform. The hardware under consideration includes a spectroscopic reflectometer (R), polarizing spectroscopic reflectometer (RP) and a spectroscopic ellipsometer (SE). Four advanced lithographic applications are evaluated-two from Spansion's 110-nm Flash memory technology line, and two from AMD's 90-nm logic process. ODP models are developed and optimized for each application and each type of hardware. Results include static and dynamic repeatability, throughput, correlation to incumbent metrology and correlation to cross-section. For each application, the authors also attempt to determine the level of model complexity supported by each hardware type, with special attention paid to the relative sensitivity of each system to changes in critical dimension (CD) and resist profile. The results generally indicate that the SE is the most sensitive hardware type while the R is the most stable. The RP occupies some form of middle ground on both counts. These generalizations are largely application dependent and clear differentiations do not always exist. Selecting the right spectral scatterometry hardware, therefore, is a function of one’s application complexity and control objectives.