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

Abstract

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 ΔC–V curves. The results of the experimental campaign are collected to infer the stochastic property of the strength of polycrystalline, columnar silicon films.

Keywords

• polysilicon tensile strength
• polysilicon thin films
• on-chip mechanical testing