Correlation of UVIIHS resist chemistry to dissolution rate measurements

Abstract

This article describes the correlation of UVIIHS resist chemistry to dissolution rate measurements as a function of resist processing conditions. The acid generation efficiency, α, for the UVIIHS photoacid generator is high, 0.027 cm2/mJ. The dissolution rate versus exposure curves show the excellent developer selectivity of UVIIHS, with n values >8 for all processes. The rmax values for this resist are above 20 000 Å/s, which is higher than any positive resist previously reported. The extent conversion for deprotection is directly related to the dissolution rate changes; ∼30% deprotection correlates to the E0 dose for all process conditions evaluated. At 30%-40% acid produced all of the deprotection chemistry is essentially completed. The chemical contrast, as measured by extent conversion versus exposure dose, is strongly affected by the postexposure bake (PEB) temperature, with 140 °C PEB showing higher chemical and lithographic contrast than the 130 °C PEB. Mack's dissolution model has been shown to work for these data sets. © 1996 American Vacuum Society.