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2015
Conference Paper
Titel
Technologies for wafer level MEMS capping based on permanent and temporary wafer bonding
Abstract
Further cost reduction and miniaturization of electronic systems requires new concepts for highly efficient packaging of MEMS components like RF resonators or switches, quartz crystals, bolometers, BAWs etc. This paper describes suitable base technologies for the miniaturized, low-cost wafer level chip-scale packaging of such MEMS. The approaches are based on temporary handling and permanent bonding of cap structures using adhesives or solder onto passive or active silicon wafers which are populated with MEMS components or the MEMS wafer themselves. Firstly, an overview of the possible packaging configurations based on different types of MEMS is discussed where TSV based and non-TSV based packaging solutions are distinguished in general. The cap in a TSV based solution can have the same lateral size as the MEMS carrying substrate, since the electrical contacts for the MEMS can be routed either thought the cap or base substrate. Thus, full format cap wafers can be used i n a regular wafer to wafer bonding process to create the wafer level cavity packages. However, if no TSVs are present in the cap or base substrate, the caps need to be smaller than the base chips, so that electrical contacts outside the cap area can be accessed after the caps were bonded. Such a selective wafer level capping with caps smaller than the corresponding base chips can be obtained by transfer bonding of pre-arranged caps from a help or donor wafer. Two options to create such help wafers with pre-arranged caps will be discussed in detail here in this manuscript.