Environmental stability of 193 nm single layer chemically amplified resists

The principle of chemical amplification was introduced to develop fast and high resolution resist materials, primarily for deep-ultraviolet (UV) litho graphy. Excellent sensitivity in CA resists emanates from the utilization o f a photogenerated species, typically an acid, to cause several catalytic c rosslinking or deblocking events' during a postexposure bake (PEB) reaction . Deactivation of the photoacid by airborne basic contaminants or other pat hways typically changed the feature width and/or the profile as a function of the delay between exposure and the PEB. Decreasing the photoacid strengt h, use of low activation energy protecting groups, a decrease in the cataly tic turnover rates or a combination of these has helped alleviate this. Tod ay, deep-UV resists that show several hours of postexposure stability are a vailable. We have examined the postexposure delay stability of several 193 nm resists that varied in matrix polymer, photoacid generator, and protecti ng group chemistry as a function of different concentrations of ammonia and N-methyl pyrrolidone (NMP) at three different relative humidity conditions . In this article we will discuss the experimental setup and describe the e nvironmental contamination stability of these different resists as well as describe in detail the design methodology employed in formulating the resis t that showed no significant variation in its linewidth of 0.16 mu m line/s pace pairs with 13 ppb of ammonia or 14 ppb of NMP. (C) 1999 American Vacuu m Society. [S0734-211X(99)04201-8].