Photolithography on three-dimensional structures using spray coated negative and positive photoresists

Fabricating microelectromechanical systems (MEMS) structures poses many processing challenges. This paper describes photolithography on high aspect ratio microstructures. Transferred pattern depends on a deposited resist film quality. Spin coating cannot be used for preparing the quality resist film on the deep structures. We have developed spray coating technique using a negative photoresist. Lessons learned from spray conditions of the negative resist are applied to the positive resist, which requires higher technical level.