Measuring system for diffusion length of photoactive compound in post‐exposure bake process

Abstract

AbstractThe post‐exposure bake (PEB) characteristics of a photoresist can be examined with a method that estimates the diffusion length of a photoactive compound (PAC) in the photoresist PEB process. Diffusion lengths are estimated with development rate measurement equipment using PEB conditions at temperatures of 50°C, 100°C, 110°C, and 120°. An ultrahigh‐resolution i‐line photoresist THMR‐iP3000 is used in the research. The obtained values are input into a photolithography simulator PROLITH/2 to calculate photoresist profiles. Using a 365‐nm wavelength, 0.5 NA, and 0.6‐coherence factor conditions, resist profiles for a 0.4‐μm line space feature are calculated with varied focus. The simulated results are compared with SEM observations to evaluate the validity of the estimation method; they are found to be substantially consistent with experimental results, thus confirming the validity of the method.