THICKNESS AND DIELECTRIC-CONSTANT DETERMINATION OF THIN DIELECTRIC LAYERS

We derive a method for the determination of the dielectric constant and thickness of a thin dielectric layer, deposited on top of a thick dielectric layer which is in turn present on a metal film. Reflection of p- and s-polarized light from the metal layer yields minima for certain angles of incidence where the light is absorbed by the metal. The thin dielectric layer causes shifts in the angles at which the minima occur, from which the thickness and dielectric constant can be obtained. The model is tested for 3.5 and 14 nm thick photoresist gratings.