Effect of Polymer Protection and Film Thickness on Acid Generator Distribution in Chemically Amplified Resists

Films of chemically amplified resists with different polymer polarity and film thickness were prepared to investigate their effect on acid generator distribution within the film. Poly(4-hydroxystyrene) (PHS) was used as a polymer, and its polarity was changed by partially protecting its hydroxyl groups. Diphenyliodonium-triflate (DPI-tf) and triphenylsulfonium-antimonate (TPS-Sb) were chosen as an acid generator to enhance the density contrast within the film. Films with acid generator concentration of 10 and 30 wt% were prepared for the non-protected PHS resist film and also films with different thicknesses were prepared for 10 wt% concentration samples. For the partially protected PHS resist films, two films with different thicknesses were prepared for 30 wt% TPS-Sb and 10 wt% DPI-tf films. X-ray reflectivity measurements were performed against the films to investigate the depth density profile. The acid generator distribution was found to be inhomogeneous in most of the films, and the distribution showed film thickness and polarity dependences.