Control systems for the nanolithography process

The lithography process is the critical step in the fabrication of nanostructures for integrated circuit manufacturing. In this paper, a summary is presented of several projects applying control and signal processing techniques to lithography. We begin with a discussion of areas in the optical exposure process where systems techniques make a significant difference. These areas include the optical mask preparation step where fast simulation methods and computational algorithms are used for mask design. Critical systems areas for next generation lithography are noted including nanopositioning by precision control of flexure systems and alignment by signal processing of laser interferometry strategies. A case study is then presented of temperature control for the postexposure bake step of sensitive chemically amplified photoresists used in deep-UV lithography.