Photolithography method using castellation shaped assist features to form a line-and-space pattern and photomask containing the assist features

Abstract

A method of patterning a structure includes applying a photoresist layer over a material layer located over substrate, lithographically exposing the photoresist layer by passing an exposure radiation beam through a photomask, developing the exposed photoresist layer, and etching the material layer using the developed photoresist layer as a mask. The photomask contains a photomask pattern including a combination of a line-and-space pattern and a peripheral castellation pattern. The peripheral castellation pattern includes a combination of an end straight line dummy pattern and a plurality of hammerhead patterns attached to a lengthwise sidewall of the end straight line dummy pattern.

Dependencies are inferred from the claim text.