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

Abstract

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

Monolithic Integration of a Wafer-Level Thin-Film Encapsulated mm-Wave RF-MEMS Switch in BEOL of a 130-nm SiGe BiCMOS Technology

“…In addition, RF-MEMS devices require specific environmental conditions in the packaged cavity for a reliable and stable lifetime operation. Although many different integration techniques have been developed and used to package the RF-MEMS devices [23], the method of wafer-level encapsulation seems to be one of the most promising methods, providing high performance, easy integration to the semiconductor foundry, and lower cost [15]- [17]. In such encapsulation processes, small holes above or around the RF-MEMS device are used to release it.…”