Hot embossing for MEMS using silicon tools

The paper deals with the development of silicon tools and an appropriate hot embossing technology for polymers. With this technology, high quality embossing of optical or fluidic structure for high precision requirements in a batch process is possible thereby reducing system costs. Possible usage is the production of Micro Electro Mechanical Systems (MEMS) for optical or fluidic applications. This could be sensors for chemical analysis of liquids or BioMEMS. Further promising applications are multifunctional printed circuit boards (PCB) or micro cooler. Up to now for coarser dimensions the use of conventional made (e.g. miling) steel tools is common. For forming of smallest structures down to the sub-micrometer range with excellent surface roughness LIGA technology is applied. However, in order to reduce the system costs LIGA tools shall be substituted by silicon tools. Deep reactive ion etching (DRIE) is used to fabricate such an embossing tools allowing complex geometrical figures. For fluidics or optical applications the tool structures have to show a tapered (positive) profile and sufficient low roughness. Roughness can be minimised by further oxidation and etch steps. The hot embossing experiments which will be presented show the capability of the optimised DRIE technology for the aimed application field.