Semiconductor device models including re-usable sub-structures

Methods and tools for generating measurement models of complex device structures based on re-useable, parametric models are presented. Metrology systems employing these models are configured to measure structural and material characteristics associated with different semiconductor fabrication processes. The re-useable, parametric sub-structure model is fully defined by a set of independent parameters entered by a user of the model building tool. All other variables associated with the model shape and internal constraints among constituent geometric elements are pre-defined within the model. In some embodiments, one or more re-useable, parametric models are integrated into a measurement model of a complex semiconductor device. In another aspect, a model building tool generates a re-useable, parametric sub-structure model based on input from a user. The resulting models can be exported to a file that can be used by others and may include security features to control the sharing of sensitive intellectual propert