Single-Step, Spin-on Process for High Fidelity and Selective Deposition

Abstract

Processes that enable selective deposition in thin films are desired for advanced patterning applications to reduce overlay demands, but conventional techniques are slow and limited in material scope. Here, we report a method that selectively deposits polymeric coatings on heterogeneous substrates (Cu/SiO2) using spin coating. Unlike traditional approaches that rely on surface pretreatments, herein, selectivity is induced by polymer design that promotes preferential dewetting from one substrate material and uniform wetting on the other. As evidenced by studies with homogeneous surfaces, poly(acrylates) containing semifluorinated pendant groups satisfy this criterion and spontaneously dewet from SiO2 but form continuous films on Cu. When spin coated onto Cu/SiO2 line-space patterns, these semifluorinated polymers selectively coat only the Cu lines without any pre- or postprocessing. Rational design rules have been elucidated that anticipate regimes of selective deposition by correlating the droplet size of dewetted features on homogeneous SiO2 with the dimensions of heterogeneous Cu/SiO2 patterns. The universality of this unique strategy is demonstrated across a library of polymers with varying molecular weights and monomer structures, providing significant advances arising from the simplicity and rapidity of spin coating. For 10-40 μm full pitch features, the entire deposition procedure involves a single step and is complete in under 1 min.