ABSTRACT
This chapter focuses on resolution enhancement techniques that push photolithography at constant wavelength to its limits, without necessarily varying or improving on the physical light source. Photolithography is the most expensive manufacturing process step, accounting for up to 35% of the total processing cost. Increased wafer throughput and resolution enhancements are e among the most commonly implemented techniques to recover some of the cost involved in photolithography. The resolution and feature density of photolithography are both limited by diffraction as light passes through the photomask and travels toward the wafer. Directed self-assembly is a hybrid patterning technique in which photolithography is used to outline guiding patterns that direct the morphology of block-copolymer chains during thermally assisted self-assembly. Essentially, these modifications are classified into two categories: distortion corrections and reticle enhancement. Reticle enhancements are alterations to improve the manufacturability or resolution of the process, with techniques such as phase-shifted masks and multiple patterning.
