Microsystems Technology

PSM-X2 Process Platform

PSM 1

Surface micro machined sensor structure in 10-30 µm thick polysilicon

PSM 2

Principle cross section of a PSM-X2 inertial combi sensor. The two neighbored cavities contain movable polysilicon structures.

The technology platform PSM-X2 features a low stress 10-30 µm thick poly silicon layer for the realisation of mechanical active and passive MEMS structures (Fig. 1). The use of high resolution lithography allows minimal structure dimension down to 0.5µm. An additional electrode layer beneath the active polysilicon layer is implemented. This gives the opportunity for out-of-plane signal detection or sensor stimulation. Additive functional layers enhance reliability and robustness of the MEMS devices (anti stiction, high-g shock).

For the wafer scale bonding of the sensor device and the protective encapsulation a dedicated multi pressure wafer level packaging process is applied using a gold silicon eutectic process at about 400°C. The metallic bond frame induces a hermetic encapsulation of the cavity and the pressure applied during the bond process will persist. Integrated getter films allow cavity pressure levels down to 10-6 bar and a pressure ratio within adjacent cavities of up to 1:400. The application range of PSM-X2 platform includes e.g. inertial sensors, micro mirrors or electro-optic deflection devices.