Development behaviour of irradiated microstructures

Abstract In the first step of the LIGA process a resist layer typically PMMA (polymethylmethacrylate), is patterned by deep X-ray lithography. The exposed parts are subsequently dissolved by an organic developer. The quality and the achievable height of the microstructure is decisively determined by the development process. In order to increase the aspect ratio and maintain the quality characteristics of the microstructures the parameters influencing the development process were investigated. In case of dip development, in contrary to ultrasound supported development, no dependency on the geometry or lateral dimension of the microstructure down to 80 μm has been observed. In both cases a strong dependency of the development rate on the dose value and depth of deposition has been noticed. The development rate increases with increasing dose value and decreases with increasing depth of deposition. In case of dip development the development course can be described with an phenomenological equation which considers both dose value and depth of deposition.