Capping technologies for wafer level MEMS packaging based on permanent and temporary wafer bonding

This paper describes techniques for the miniaturized, low-cost wafer level chip-scale packaging of MEMS based system in packages (SiPs). The approaches comprise permanent bonding of cap structures using adhesives or solder onto a passive or active silicon wafer which is populated with MEMS components or which is itself a MEMS wafer. The paper addresses different options for manufacturing of lid or cap structures and their subsequent bonding to the partner wafer. Different technologies like bonding of full area cap wafers as well as partial capping approaches based on reconfigured cap structures on a help wafer or cap structures created on a compound wafer are presented. Examples like the selective capping process for RF-MEMS switches are discussed in detail. All processes were performed at 200 mm wafer scale.