Confronting the Diffraction Limit

doi:10.1117/3.2525393.ch8

Book: Principles of Lithography, Fourth Edition

Author(s): Harry J. Levinson

Published: 2019

https://doi.org/10.1117/3.2525393.ch8

Abstract

Some of the effects seen in patterns generated with low-k₁ processes are discussed in this chapter. Several techniques that are also described—such as off-axis illumination and phase-shifting masks—have been developed to address the shortcomings of optical imaging as feature sizes become smaller than the wavelength of light. Methods to improve image contrast that involve modification of the mask or illumination are referred to collectively as resolution-enhancement techniques (RET) and are discussed in this chapter.