Patent ID: 7898661

Claim:
A scatterometer for measuring one or more parameters of a periodic diffracting structure of a sample, said one or more parameters comprising shape of lines, linewidth, pitch, height and/or side wall angle of the periodic diffracting structure, said scatterometer comprising: a reference database that includes a plurality of ellipsometric functions, each ellipsometric function corresponding to a set of values of said one or more parameters, said values including at least values of line width, height and side wall angle of periodic diffracting structures; a source which emits broadband radiation; a polarizer that polarizes the broadband radiation to produce a sampling beam sampling the periodic diffracting structure; a detector detecting ellipsometric parameters of a diffraction from the periodic diffracting structure of said broadband radiation over a range of wavelengths; a processor comparing said detected ellipsometric parameters to said plurality of ellipsometric functions in said database to determine said shape of lines, linewidth, pitch, height and/or side wall angle of the periodic diffracting structure, wherein said processor determines at least the line width, height and side wall angle of the periodic diffracting structure; and a device measuring data related to at least an index of refraction of a structure adjacent to the periodic diffracting structure; said periodic diffracting structure located on a surface of a sample, wherein said adjacent structure is away from said periodic diffracting structure so that said data related to at least said index of refraction of the adjacent structure is measured without measuring said periodic diffracting structure, and the processor uses said data related to at least the index of refraction of the adjacent structure to reduce number of parameters of the database and processing time for determining said parameters of the periodic diffracting structure.