Development of Mechanical Testing Machine for Microelements and Fracture Strength Evaluation of Single-Crystalline Silicon Microelements.

Abstract

Quasi-static bending tests of single-crystalline silicon microelements fabricated by dicing and photoetching were performed. The microelements fabricated by photoetching (specimen width : 65-200 μm, thickness : 45-60μm) were subjected to three-point bending, with two-support roll length of l.5 mm. For this purpose, the authors have developed a specially designed testing machine (load range : 0.1 mN-5 N, accuracy : 0.02 mN), which enables mechanical testing including fatigue of microelements. Loads were applied to a specimen by means of an electromagnetic actuator, and the displacement was measured with a differential transformer (measuring accuracy : 0.1 μm) . Mechanical testing of microelements could be thereby performed with sufficient precision. Single-crystalline silicon microelements deformed elastically until final catastrophic failure, showing a brittle nature. The influences of the fabrication process and specimen width on fracture strength were investigated, and the dominating factor on the strength was discussed.