Patent ID: 6451513
Filing Date: 2002-09-17
Classification: G03F

Abstract:
A method of fabricating a periodic structure in a substrate having a substantially planar surface, comprising:forming a protective layer overlying the substrate; positioning a mask proximate the substrate, the mask comprising a transparent field portion adapted to transmit light and to provide a first optical path length, and a transparent pattern portion adapted to transmit light and to provide a second optical path length, the field and pattern portions being first and second single layers of transparent material and wherein the second optical path length differs from the first optical path length by an odd integer multiple of one-half a wavelength of the light, the pattern portion including a plurality of pattern elements, each comprising a thickness of a second transparent material and being substantially laterally surrounded by the field portion and having substantially equal spatial extent along first and second lateral directions, the first direction being substantially perpendicular to the second direction; directing light through the mask and onto the protective layer to expose the protective layer to light for no more than a single exposure time interval, the light passing through the transparent field and pattern portions of the mask and undergoing destructive interference at a plurality of interference regions of the protective layer, the interference regions not being created by any opaque portions of the mask; removing portions of the protective layer and exposing underlying portions of the substrate; and removing portions of the exposed substrate.