Silicon carbide (SiC) is recognized as an excellent material for microelectromechanical systems (MEMS), especially those operating in challenging environments, such as high temperature, high radiation, and corrosive environments. However, SiC bulk micromachining is still a challenge, which hinders the development of complex SiC MEMS. To address this problem, we present the use of a carbon nanotube (CNT) array coated with amorphous SiC (a-SiC) as an alternative composite material to enable high aspect ratio (HAR) surface micromachining. By using a prepatterned catalyst layer, a HAR CNT array can be grown as a structural template and then densified by uniformly filling the CNT bundle with LPCVD a-SiC. The electrical properties of the resulting SiC-CNT composite were characterized, and the results indicated that the electrical resistivity was dominated by the CNTs. To demonstrate the use of this composite in MEMS applications, a capacitive accelerometer was designed, fabricated, and measured. The fabrication results showed that the composite is fully compatible with the manufacturing of surface micromachining devices. The Young’s modulus of the composite was extracted from the measured spring constant, and the results show a great improvement in the mechanical properties of the CNTs after coating with a-SiC. The accelerometer was electrically characterized, and its functionality was confirmed using a mechanical shaker. (Figure presented.)

Fabricating high-aspect-ratio (HAR) structures with silicon carbide (SiC) is a challenging task. This paper presents a silicon carbide (SiC) reinforced vertically aligned carbon nanotubes (VACNT) composite as a promising candidate to fabricate HAR MEMS devices for harsh environment applications. The use of a VACNT array allows the fast realization of HAR structures as a template for MEMS fabrication. The template can later be easily filled by amorphous-SiC due to the porous nature of the VACNT forest. The SiC-CNT nanocomposite has electrical properties dominated by VACNT arrays and mechanical stability dominated by the a-SiC. Based on this concept, a thermal actuator is fabricated and proven to function up to 450°C for the first time.