Mechanical characterization of low dimensional structures through on-chip tests

Abstract

Three different MEMS for on-chip testing are here discussed, which load up to rupture under bending thin (0,7 μm) or thick (15 μm) polysili-con specimens. The first one is based on a rotational electrostatic actuator which contains a series of interdigitated comb-fingers and loads a couple of thin polysilicon specimens in bending in the plane parallel to the sub-strate. The second one loads the couple of thin polysilicon specimens in the plane orthogonal to the substrate thanks to a parallel plate actuator which moves in the direction orthogonal to the substrate. The third device was conceived to cause initiation and propagation of a crack in a thick polysilicon specimen; it is based on a high number of comb finger electro-static actuators which load a notched specimen by means of a lever system. In the three cases discussed, the data reduction procedure is based on the measurement of the capacitance variation of a displacement sensor, it was then possible to obtain the value of the Young’s modulus of the vari-ous specimens and that of the maximum stress at rupture