Development and evaluation of a prototypic automated high precision assembly of ultra-thin miniaturized silicon wafers

The trend towards thinner wafers is pushing conventional processes, automation systems and components for handling such wafers to their limit. Ultra-thin wafers (<75 µm) are no longer mechanically stable and thus require new processing and handling methods. The use of a carrier would prevent substrates from becoming damaged. In the EU-founded project SUGAR (Silicon sUbstrates from an inteGrated Automated Process), ultra-thin wafers are accurately assembled on a glass carrier to reduce wafer stress caused by subsequent processing and automation steps (module level processing). To enable the high precision gentle assembly of ultra-thin wafers researchers at Fraunhofer IPA have developed a dedicated handling process using special carriers for miniaturized (30x50 mm) ultra-thin wafers (50-75 µm thick). This paper describes the basic tests, experiments and results, and also discusses the various assembly components necessary for the development. Additionally, based on the results obtained from the experiments, the development and design of special tools and components for handling individual wafers and the carriers is explained.