Assessing the impact of intrinsic birefringence on 157nm lithography

Birefringence can be represented using the matrix generated by multiplying together Jones matrices for the separate lens elements. Conventional vector imaging methods, which use orthogonal electric field components in resist combined to yield the intensity, can be extended to handle this matrix representation of the optical pupil. The mean amplitude ratio of the off-diagonal elements in the matrix pupil is shown to correspond quite well to the birefringence-induced CD error.