IN-SITU TENSILE-STRENGTH MEASUREMENT AND WEIBULL ANALYSIS OF THICK-FILM AND THIN-FILM MICROMACHINED POLYSILICON STRUCTURES

A method is introduced in which tensile tests can be performed in situ on micromachined structures. The testing equipment consists of a test ing unit mounted on a micromanipulator in a scanning electron microsco pe. The fracture loads of micromachined beam structures made from thic k and thin film polysilicon were measured, and the fracture strengths were then calculated via measurements of the fracture surface areas. C haracterization of the film materials was also performed with transmis sion electron microscopy, atomic force microscopy and scanning electro n microscopy to locate the critical defects in the materials. The stat istical scatter of the fracture strength values was evaluated using We ibull statistics, which yielded the mean fracture strength and the Wei bull modulus-a measure of the amount of scattering In this study, for the first time, Weibull theory was also applied to a real micromechani cal structure, i.e. standard test results were transformed into expect ed strength limits of a more complex structure.