Enabling Large-Area Selective Deposition on Metal-Dielectric Patterns using Polymer Brush Deactivation

Abstract

Area-selective deposition could be an important self-aligning material-deposition technique to enable future nanoelectronics by accurately placing active materials at previously defined substrate patterns. We describe a robust self-aligning strategy to pattern uniform gold (Au) thin films on only the dielectric areas of prepatterned copper/silicon dioxide (Cu/SiO2) substrates. The use of an amine-terminated polystyrene polymer brush (i.e., PS-NH2) to selectively block micrometer Cu regions of patterned Cu/SiO2 substrates is demonstrated. Following thermal evaporation of ∼35 nm thick Au films on PS-NH2 modified Cu/SiO2 surfaces and subsequent acetic acid etching, large-area selective patterning of Au films on SiO2 regions was achieved. We evaluated the influence of the initial PS-NH2 polymer brush film concentration and etching conditions to optimize the process window for the demonstration of highly successful area-selective deposition on SiO2 surface regions. X-ray photoelectron spectroscopy and scanning electron microscopy analysis show the high selectivity of the initial polymer brush deposition process. Auger electron spectroscopy and transmission electron microscopy data reveal the distinct interfaces at the substrate surface after Au area-selective deposition. The technique is highly reproducible with no discernible deposition of Au on Cu over macroscale areas after etching. The process involves relatively short and inexpensive processing steps compared to previously reported methods. The accuracy and precision exemplified in this work to dictate metal deposition at desired substrate areas make the process appealing for future semiconductor practices.