A new approach to wafer level thin-film encapsulation for RF-MEMS Switches

Abstract

The paper will discuss in detail a new fabrication process developed for the encapsulation of RF-MEMS switches. A shell covering the unreleased switch is created with two layers of PECVD silicon nitride patterned with holes and separated by an aluminum layer which is removed at the end of the shell fabrication sequence. The cavity beneath the shell is then made free burning by oxygen plasma the sacrificial photoresist spacer covering the switch. The mechanical design of the shell and the optimization of the film parameters are reported and discussed. The shell is then covered with a sealing polymer that should not penetrate into the holes. In order to achieve this result a special design for the hole pattern is presented