NEW DEVELOPMENT STRATEGIES FOR HIGH-ASPECT-RATIO MICROSTRUCTURES

In the first step of the LIGA process a resist layer, typically PMMA ( polymethylmethacrylate),is pattered by deep X-ray lithography. The exp osed parts are subsequently dissolved by an organic developer. The qua lity and the achievable height of the microstructure is decisively det ermined by the development process. In order to increase the aspect ra tio and maintain the quality of the microstructures the parameters inf luencing the development process were investigated. In the case of dip development and ultrasound development a strong dependency of the dev elopment rate on the temperature, dose value and depth of deposition h as been noticed. The development rate increases with increasing dose v alue and temperature and decreases with increasing depth of deposition . In case of dip development the development. course can be described by a phenomenological equation which considers the three mentioned par ameters. In the case of ultrasound further parameters have to be taken into account: the geometry and the dimensions of the structures.