1. A method, comprising: forming an integrated circuit structure comprising: a substrate; a first photoresist pattern disposed on at least a portion of the substrate; a chemically inert barrier layer disposed on at least a portion of the first photoresist pattern, chemically inert the barrier layer comprising an inorganic material comprising an oxide, nitride, or carbide; and a second photoresist pattern disposed on at least a portion of the chemically inert barrier layer; and etching the structure to define a feature in the substrate, wherein the effective etch rate of the combined first photoresist pattern and the chemically inert barrier layer is different from the effective etch rate of the second photoresist pattern.