Postexposure bake characterization and parameter extraction for positive deep-UV resists through broad-area exposure experiments

This paper presents a methodology for extracting post exposure bake reaction and diffusivity parameters through broad area exposures, without the need for FTIR measurements. The parameter estimates are obtained by varying processing conditions as to achieve the same dissolution rate, and hence the same level of deprotection. Experiments conducted with APEX-E resulted in the following reaction parameter estimates, K1 equals 2.31/sec, K2 equals 0.0038/sec and m equals 1.71, which are in close agreement with values obtained with FTIR data. To calibrate the acid diffusion, top-to-top contact diffusion experiments can be used. Results for APEX-E gave diffusivity estimates for an exponential diffusion model of Do equals 5.6e-6 and (omega) equals 5.8. An analysis of variance conducted on the data shows a constant diffusion model has considerable lack of fit.