Thin Filmencapsulation of microstructures using Sacrificial CF-Polymer

This paper reports on a new method for thin film encapsulation of microelectromechanical systems (MEMS) using plasma enhanced chemical vapor deposited (PECVD) fluorocarbon polymer as sacrificial material and a stress optimized SiO/SiN capping layer. This technique is applicable for a wide range of MEMS technologies - high aspect ratio as well as surface microstructures - it saves die area and enables standard packaging processes such as dicing and pick and place. Beside of the fabrication technology, this paper presents results of a finite element analysis (FEA) regarding the deflection and mechanical stress due to a pressure difference between the cavity and the ambient. The results of the FEA were verified by interferometric measurements on fabricated test structures.