Fracture of polycrystalline 3C-SiC films in microelectromechanical systems

• Published in: Journal of microelectromechanical systems Vol. 13; no. 6; pp. 972 - 976
• Main Authors: Di Gao, Carraro, C., Radmilovic, V., Howe, R.T., Maboudian, R.
• Format: Journal Article
• Language: English
• Published: New York IEEE 01-12-2004; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Acoustic beams; Bending; Cantilever beams; Capacitive sensors; Crack propagation; Fracture; Fracture mechanics; Mathematical analysis; Microelectromechanical systems; microelectromechanical systems (MEMS); Micromachining; Micromechanical devices; Semiconductor films; Silicon carbide; Structural beams; Temperature sensors; Testing; thin films
• ISSN: 1057-7157; 1941-0158
• DOI: 10.1109/JMEMS.2004.838372

The fracture of polycrystalline SiC films is investigated using a micrometer-sized fracture tester fabricated by micromachining techniques. A series of SiC cantilever beams varying in length are carried by a moving shuttle tethered to the substrate, and are bent in plane until fracture. The fracture strain of SiC films is calculated from the deflection of bending beams using nonlinear beam theory and determined to be 3.3%/spl plusmn/0.2%, which corresponds to a fracture stress of 23.4/spl plusmn/1.4 GPa. These values are significantly higher than those for polycrystalline silicon. In addition, the crack propagation in the polycrystalline SiC films is observed to be transgranular.