Environmental Stability of 193 nm Single Layer Chemically Amplified Resists

Chemical Amplification (CA) principle has been introduced to develop fast and high resolution resist materials, primarily for deep-UV lithography. Excellent sensitivity in CA resists emanates from the utilization of a photogenerated species, typically an acid, to cause several catalytic crosslinking or deblocking events during a post-exposure bake (PEB) reaction. Deactivation of photoacid by airborne basic contaminants or other pathways typically change feature width and/or profile as a function of the delay between exposure and PEB. Decreasing the photoacid strength, use of low activation energy protecting groups, decrease in catalytic turnover rates or a combination of these have helped alleviate this issue. Today, deep-UV resists that show several hours of post-exposure stability are available.