Patent ID: 8942842
Filing Date: 2015-01-27
Classification: B24B,G01N

Abstract:
1. A method of generating a library of reference spectra, comprising: storing an optical model for a layer stack having a plurality of layers, wherein the layer stack comprises a stack of P+1 layers, and wherein the stack includes a first layer, and with layer receiving user input identifying a set of one or more refractive index functions and a set of one or more extinction coefficient functions for the first layer from the plurality of layers, wherein the set of one or more refractive index functions includes a plurality of different refractive index functions or the set of one or more extinction coefficient functions includes a plurality of different extinction coefficient functions; and for each combination of a refractive index function from the set of refractive index functions and an extinction coefficient function from the set of extinction coefficient functions, calculating a reference spectrum using the optical model based on the refractive index function, the extinction coefficient function and a first thickness of the first layer, to generate a plurality of reference spectra, wherein calculating the reference spectrum comprises a transfer-matrix method and calculating a stack reflectance R where for each layer j>0, E where E