Comparison of scalar and vector modeling of image formation in photoresist

A comparison is made between several scalar models for the formation of an image in a photoresist film with differing approximations and a vector model. It was found that up to a numerical apertures of 0.7, a full scalar model showed no appreciable deviation from the vector mode. However, when several common assumptions were made to simplify the scalar model, significant errors resulted at a higher numerical apertures.