Low Cost and High-Aspect Ratio Micro/Nano Device Fabrication by Using Innovative Metal-Assisted Chemical Etching Method

In this paper, the metal-assisted chemical etching (MACE) method is presented along with the advantages of using this method. Large areas and a combination of large and narrow patterning areas are successfully produced by using metal meshes for MACE. Moreover, in order to exemplify this microfabrication technique, the authors demonstrate the fabrications of different microelectromechanical systems (MEMS) devices; from simple structure (micro-cantilever) to a complex structure (capacitive silicon resonator). Micro-cantilever beam with resonant frequency of 262 kHz and quality factor of 8100 is successfully fabricated using this technique. Narrow capacitive gap width together with silicon resonator structure is also microprocessed by MACE technique. For the capacitive resonator, nano gaps with 250 nm-width and 7 μm-height is successfully micro-fabricated using MACE process on a silicon on insulator (SOI) wafer. The resonant peak of the fabricated device is found at 81.4 MHz with quality factor of 4000 and motional resistance of 89 kΩ. The MACE process is performed in the wet etching solution that enables the fabrication of anisotropic silicon structures. This paper demonstrates that MACE method could potentially replace dry etching technique currently used for the fabrication of various electronics and photonics devices and energy applications. Due to the ease of implementation and possibility of batch fabrication, MACE method is a promising technique for the manufacturing of a broad range of high-quality Si-based devices at low cost.