Mechanical qualification of RF-filters for space applications

Micromachined RF-filters for Millimeter wave communications are expected to replace the actual bulky off-chip filters since they offer high performances at low cost. Nevertheless, their large aspect ratio between area (several mm²) and their thickness (a few microns) may make them sensitive to mechanical stress such as vibrations or shocks. In this paper, we focus on their mechanical characteristics. The studied filters are built on a thin SiO₂/Si_xN_y dielectric membrane and the signal lines are in gold. This composition of material makes the analytical approach rapidly complex. So, in counterparts, we ran FEM simulations to study the influence of process parameters such as stress on flexion modes. Then, we measured by vibrometry the natural resonant frequency of several filter sizes (from 1 mm² up to 70 mm²) and compared results with previous simulations. Finally, we applied at die level, standard procedures of shock and vibration used for space qualification. All the membranes withstood the tests without structural damage.