On-Chip Tests for the Characterization of the Mechanical Strength of Polysilicon †

Microelectromechanical systems (MEMS) are nowadays widespread in the sensor market, with several different applications. New production techniques and ever smaller device geometries require a continuous investigation of potential failure mechanisms in such devices. This work presents an experimental on-chip setup to assess the geometry- and material-dependent strength of stoppers adopted to limit the deformation of movable parts, using an electrostatically actuated device. A series of comb-finger and parallel plate capacitors are used to provide a rather large stroke to a shuttle, connected to the anchors through flexible springs. Upon application of a varying voltage, failure of stoppers of variable size is observed and confirmed by post-mortem DC–V curves. The results of the experimental campaign are collected to infer the stochastic property of the strength of polycrystalline, columnar silicon films

Mems gyroscope with improved rejection of a quadrature error

A MEMS gyroscope is equipped with: at least a first mobile mass suspended from the top of a substrate by means of elastic suspension elements coupled to anchor points rigidly fixed to the substrate, in such a manner as to be actuated in an actuating movement along a first axis of a horizontal plane and to carry out a measurement movement along a vertical axis, transverse to the horizontal plane, in response to a first angular velocity acting about a second axis of the horizontal plane, transverse to the first axis. The elastic suspension elements are configured in such a manner as to internally compensate unwanted displacements out of the horizontal plane along the vertical axis originating from the actuating movement, such that the mobile mass remains in the horizontal plane during the actuating movement

A comprehensive model of beams' anisoelasticity in MEMS gyroscopes, with focus on the effect of axial non-vertical etching

This paper describes a comprehensive approach to model and efficiently simulate the behavior of MEMS gyroscopes in presence of beams' anisoelasticity, that causes out-of-plane mechanical quadrature. Special focus is given to the effects of non-vertical etching along the axial direction of flexural beams, which have been poorly investigated in the literature. A device-level numerical simulation tool to evaluate the effects of beams' anisoelasticity on quadrature is developed and validated through the comparison with 3D FEM simulations