Multilayer Measuring Using Effective Media Approximation

摘要

The metrology system includes a controller coupled to the detector to generate a detection signal based on reflection of the illumination beam from the multilayer film stack. The multilayer stack may include one or more zones having a repeating pattern of two or more materials. The controller models the reflection of the illumination beam by modeling the zones as thick films with zone thicknesses and effective permittivity values using an effective medium model that relates the effective permittivity values of the zones to the volume fractions and permittivity values of the constituent materials. can create The controller also determines values of zone thicknesses and volume fractions using regression of the detection signal based on the effective medium model, and also based on the number of films, zone thicknesses, volume fractions, and effective permittivity values. It is possible to determine average thickness values of the constituent materials.