Mechanical test structures for the determination of normal stress in multilayer freestanding MEMS-membranes
Understanding the mechanical behavior of free standing membranes is a point of common interest for MEMS structures, where a certain distance or deflection of a cantilever or membrane refers directly to the detectors performance. A material system with different types of basic MEMS materials like doped silicon as well as a conducting and passivation layer was characterized. Mechanical stress was measured directly after deposition and at the freestanding membranes itself. It is found out, that the mechanical stress of the investigated material systems decreases up to two orders of magnitude due to relaxation between material deposition and releasing membranes from substrate.