Chemical amplification resists: Inception, implementation in device manufacture, and new developments

The chemical amplification concept aimed at dramatically boosting the resist sensitivity was invented at IBM Research in San Jose, CA, in 1980. The sensitivity enhancement is achieved by generating acid by irradiation, which induces a cascade of chemical transformations in a resist film. A chemically amplified resist based on acid-catalyzed deprotection was quickly employed in the mid-80s in manufacture of 1 megabit (Mbit) dynamic random access memory (DRAM) devices by deep ultraviolet (UV) (∼ 250 nm) lithography in IBM. The unexpectedly high-resolution capability of chemical amplification resists promoted their acceptance in the resist community and the microelectronics industry. All the advanced lithographic technologies (current workhorse 248 nm, maturing 193 nm, and emerging 157 nm, extreme UV, and projection electron beam) depend on chemical amplification resists. This article describes the invention, implementation in device manufacturing, current status, and future perspective of chemical amplification resists.