Femtosecond pulsed laser microfabrication of SiC MEMS microgripper

Abstract

We report the capability of an ultrafast laser to pattern an electrostatic-comb-drive microgripper in the chemically difficult-to-etch 3C-SiC thin films. A microgripper with overall dimensions 1.2 mm×0.35 mm and a gap of 20 μm was designed and fabricated for the purpose of grasping and transporting microscale objects in hostile and harsh environments. Atmospheric pressure chemical vapor deposition was used to deposit thin films (∼2 μm) of 3C-SiC on 〈100〉 silicon substrates. A Ti:sapphire laser with 120 fs pulse width, 800 nm wavelength, and 1 kHz repetition rate was then used to perform “nonthermal” micromachining of thin films. Subsequent KOH anisotropic etching was used to dissolve the silicon substrate and release the gripper structures. The influence of laser pulse energy on the etch rate and quality of microfabricated grippers was examined and illustrated.

A Review of Femtosecond Laser Processing of Silicon Carbide

“…SiC is highly suitable for applications in microelectromechanical systems due to its high mechanical strength, chemical inertness, and electrical stability. It finds uses in actuators, pressure sensors, temperature sensors, transverse resonance devices, optoelectronics, and sensors [147,148]. For large-sized manufactured SiC structures, many scholars are currently committed to applying this structure to sensors.…”

Design and Fabrication of Bulk Micromachined 4H-SiC Piezoresistive Pressure Chips Based on Femtosecond Laser Technology

“…Some progresses in bulk micromachining SiC using non-standard techniques, such as ultrasonic vibration mill-grinding technique [ 25 ], mechanical milling [ 18 ] and laser ablation [ 26 , 27 ], have been demonstrated. The emergence of ultrafast lasers (the pulse width is in the range of 10 −15 to 10 −12 s, and the energy intensity ranges from 10 13 to 10 21 W cm −2 ) overcome the inherent shortcomings of long-pulse lasers, such as rough processing effects and hard-to-eliminate thermal effects, and have gradually become an effective tool for microscale even nanoscale processing of materials such as semiconductors, ceramics and metals [ 28 , 29 , 30 , 31 ]. Femtosecond laser has been proved to be an effective method for SiC pressure sensor diaphragm fabrication among them [ 32 , 33 , 34 ].…”