Dependence of optical constants of AZ(R)BARLi(TM) bottom coating on bake conditions

The optical constants of AZ(R)BARLi(TM) bottom coat have been determined by spectroscopic ellipsometry as a function of bake conditions. Cauchy parameters are reported as a function of bake conditions for three film thicknesses, corresponding to the first three minima of the reflectivity vs. AZ(R)BARLi(TM) film thickness curve. Full dispersion curves were obtained for constant spin speed and constant thickness conditions. It is found that the k dispersion curves show a slope change at 160 - 170 degrees C bake temperature which is tentatively attributed to dye depletion and the formation of a graded layer in the bottom coat.