Effect of Acid Diffusion on Resolution of a Chemically Amplified Resist in X-Ray Lithography

Abstract

The diffusion range of acids in a chemically amplified positive resist (EXP) was quantitatively evaluated using a contact replication method. The acid diffusion range reached a maximum depth of 0.4 µm. The acid diffusion range was diminished, as the temperature of prebaking was raised or the temperature of post-exposure baking (PEB) was reduced. The acid diffusion range also exerted a great influence on changing the replicated pattern width dependence on exposure dose. To clarify the effect of the acid diffusion on the characteristics of the resist, the distribution of the acid-catalyzed reaction in the resist and the acid diffusion range were calculated using the diffusion coefficient of the acid and the acid-catalyzed reaction rate constant determined by experiments. The calculated acid diffusion range coincided rather well with that obtained by the contact replication method.