M.Sc Thesis

M.Sc StudentHirshberg Arnon
SubjectNovel Test Devices for Measuring Mechanical Properties of
MEMS Structures
DepartmentDepartment of Mechanical Engineering
Supervisor PROF. David Elata


This study presents novel test devices for measuring the mechanical properties of Single Crystal Silicon (SCS). SCS is a prevalent structural material in Micro-Electro-Mechanical Systems (MEMS). Micro systems integrate a deformable mechanical part and the electronics that control it. Silicon is a semi conductor ceramic material, which is too fragile to be used for building structures in macro scale devices, but is an ideal strong material that can be efficiently used to build structures in the micro scale. Characterization of mechanical properties is crucial for proper design and for estimating the reliability of micro devices. The purpose of the novel test devices is to measure the strength and elastic moduli of micro-beams. These mechanical properties are affected by the properties of the structural material and by the surface texture that is produced in the fabrication process. One device measures the failure strength of brittle micro-beams. In contrast to prevalent devices, the novel test device does not require measurement of forces or of displacements. Besides reducing the testing cost, the device can be operated on pre-diced wafers and used to estimate reliability and fabrication repeatability. A different device is designed to measure the elastic moduli (Young modulus, shear modulus, and Poisson ratio) of SCS. This measurement is performed by applying different electrostatic forces on a single elastic structure and measuring the voltages in which the related electromechanical response becomes unstable. Several devices were fabricated. Their performance was measured and found to be in good agreement with model predictions and known values.