Super-resolution optical measurement of nanoscale photoacid distribution in lithographic materials.

Berro, Adam J; Berglund, Andrew J; Carmichael, Peter T; Kim, Jong Seung; Liddle, J Alexander · ACS Nano · 2012

basic_science · Level V

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Abstract

We demonstrate a method using photoactivation localization microscopy (PALM) in a soft-material system, with a rhodamine-lactam dye that is activated by both ultraviolet light and protonation, to reveal the nanoscale photoacid distribution in a model photoresist. Chemically amplified resists are the principal lithographic materials used in the semiconductor industry. The photoacid distribution generated upon exposure and its subsequent evolution during post-exposure bake is a major limiting factor in determining the resolution and lithographic quality of the final developed resist image. Our PALM data sets resolve the acid distribution in a latent image with subdiffraction limit accuracy. Our overall accuracy is currently limited by residual mechanical drift.

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