Nondestructive x-ray reflectivity analysis of Al distributions of ultraviolet-cured spin-coated resist films hybridized with trimethylaluminum

Abstract

Ultraviolet (UV)-cured spin-coated resist films of 100 nm and thinner thicknesses made with bisphenol A-based dimethacrylate monomers on silicon substrates were hybridized by multiple-pulsed vapor infiltration of sequential trimethylaluminum (TMA) doses and a final H2O dose. Nondestructive x-ray reflectivity measurements without film shrinkage enabled characterization of the internal layer structures of the UV-cured films unmodified before hybridization and hybridized by TMA infiltration and chemical fixing. It was possible to determine the thickness, density, and interface roughness of each layer in the unmodified and hybridized UV-cured films. The TMA infiltration and chemical fixing resulted in the formation of the highest-density Al-rich layer near the film surface. The presence of the highest-density layer arising from the most abundant component, Al, was confirmed through energy-dispersive x-ray spectroscopy and time-of-flight secondary ion mass spectrometry. The increase in the cycle number of TMA dose from 100 to 150 and 200 cycles had little effect on organic–inorganic hybridization of the 100 nm-thick UV-cured films. The thickness of the outermost Al-rich layer near the film surface was approximately 30 nm, which was unchanged when the film thicknesses of 100, 75, and 50 nm were changed. The outermost skin layer suppressed the infiltration of TMA into the UV-cured films. The infiltration of TMA into the UV-cured films progressed as the film thicknesses decreased.