Variable thickness single mask etch process

Abstract

The present invention relates to a method of performing a variable film etch using a variable thickness photomask material. Essentially, a thickness of an adjustable film layer is measured and converted into a contour map of film thickness over a region of a semiconductor body (e.g., wafer). An etch mask layer (e.g., photoresist) is then formed above the adjustable film layer and is selectively patterned by a reticleless exposure system (e.g., DMD exposure system). The selective patterning subjects different regions of the etch mask layer to varying exposure times dependent upon the thickness of the underlying adjustable film. The more etching needed to provide the underlying film to a nominal thickness, the longer the exposure of the etch mask. Therefore, the resultant etch mask, after exposure, comprises a topology allowing for various degrees of selective etching of the underlying film resulting in a uniform film.