The PSM-X2 technology platform uses a low-stress, 10-30 µm thick polysilicon layer to generate static and moving sensor structures. By using high-resolution lithography, minimum structure widths down to 0.5 µm can be realized.
For capacitive detection of movements perpendicular to the plane, additional counter electrodes are implemented. This gives the possibility to excite and detect also so-called out-of-plane motions. Additive, functional layers increase the reliability and robustness of the MEMS element (e.g. anti-stiction, shock resistance).
Wafer-level encapsulation of the device elements is integrated into the process. The tight bond between sensor and lid wafer, the so-called wafer-level packaging, is created here by a gold-silicon eutectic at about 400°C. The metallic bond frame ensures a hermetic seal so that the pressure set during the bonding process is maintained over the entire service life.
By integrating a getter layer, an internal pressure of up to 10-6 bar can be achieved. The use of the novel Multi Pressure WLP Technology allows the setting of different cavity internal pressures on wafer level. The PSM-X2 platform is currently used in the field of inertial sensors, micromirrors and electron-optical deflection units.
Fraunhofer ISIT has developed an innovative manufacturing technology for the production of high-performance MEMS scanners, the so-called "two-layer epi-polysilicon process". Following the PSM-X2 fabrication technology for inertial sensors, which is already well established at ISIT, the scanners are structured from two 30 µm thick epipoly silicon layers. In this way, height-shifted finger electrodes can be realized, which can be used both for electrostatic drive of the scanners and for capacitive position detection of the mirror position.