The scatterometric and electromagnetic signatures of a pattern are computed with the perturbation method combined with the Fourier modal method in order to reduce computational time. From an electromagnetic point of view, the grating is characterized by its scattering matrix, which allows the computation of the reflection and transmission coefficients. A slight variation of profile parameters or electrical ones provides a small fluctuation of the scattering matrix; consequently, an analytical expression of the local behavior of its eigenvectors and eigenvalues can be obtained by using a perturbation method.
© 2011 Optical Society of America