Spray coating of PMMA for pattern transfer via electron beam lithography on surfaces with high topography

Abstract

Spray coating of polymethylmethacrylate (PMMA) as electron beam resist on non planar surfaces is presented as a reliable technique for deposition of uniform resist layers with adjustable thickness at wafer scale. In the experiments a commercial spray coating system with an ultrasonic spray nozzle was used. Parameters which influence the quality of the resist layer with respect to uniformity across a 4in Si wafer, such as ultrasonic power and dispensed volume, were evaluated. The suitability of spray coated PMMA for the pattern transfer on surfaces with high topography was proven by PMMA spray coating of 8μm deep trenches etched into Si wafers. The PMMA was then electron beam exposed and chromium line patterns were transferred on the Si surface via a lift-off process.