Synergistic Effects Of Softbake And Hardbake On Thermal Softening Using Statistically Designed Experiments

The purpose of this paper is to present a statistically designed approach to identify and characterize the observed interactions between hardbake and softbake on thermal softening and the ensuing post-hardbake feature deformities. A statistically designed experiment (SDE) was employed for the simplicity of experimentation and maximal results obtained with such an approach. The processing parameters evaluated and optimized in this SDE included softbake temperature (Ts), softbake time (ts), and hardbake temperature, (Th). The magnitude of the interaction between softbake and hardbake processing parameters was calculated according to a quadratic fit of the primary response attribute. Softbake and hardbake process steps were characterized and found to be synergistic with respect to their effects on the resulting post-hardbake microlithographic feature shape.