A review of silicon carbide development in MEMS applications

Abstract

Due to its desirable material properties, Silicon Carbide (SiC) has become an alternative material to replace Si for Microelectromechanical Systems (MEMS) applications in harsh environments. To promote SiC MEMS development towards future cost-effective products, main technology areas in material deposition and processes have attracted significant interest. The developments in these areas have contributed to the rapid emergence of SiC MEMS prototypes. In this paper, we give an overview of the important developments in SiC material formation and fabrication processes in recent years. Some of the most interesting state-of-the-art SiC MEMS devices are reviewed. This highlights the major progresses in SiC MEMS developed thus far. This paper also looks into the prospect of SiC MEMS drawing attention to potential issues.

Emerging materials for microelectromechanical systems at elevated temperatures

“…Several recent reviews have outlined progress in SiC MEMS, but considerable work remains necessary to realize a larger market share beyond current niche applications including high temperature micromechanical resonators in communication transceivers, pressure sensors in the oil industry, and accelerometers in airplane engines or spacecraft. 38,44,45 Many of these challenges revolve around improving fabrication routes. Chemical vapor deposition (CVD) is used almost exclusively for SiC thin film growth, although several variations exist that are specific to the polytype or application.…”

“…LPCVD results in a slower growth rate, but can more easily accommodate the thermal stresses in the thin films. 45 Growth of homoepitaxial 6H-SiC or 4H-SiC must be done at very high temperatures between 1500 and 1650°C, which limits integration into CMOS devices. 44 However, lower temperature (800-1000°C) LPCVD processes have been developed for polycrystalline 3C-SiC films.…”

“…Fluorine-based gas mixtures are key to the process, which can be slow and lead to anisotropic etch profiles. 45 Other processes such as photoelectrochemical etching 48 and DRIE have also been developed for improved dimensional control and greater aspect ratios. 49 The latter is more commonly applied to Si, which is used as a sacrificial mold for deposited poly-SiC.…”

PECVD silicon carbide surface micromachining technology and selected MEMS applications

“…Since the 1990's, silicon carbide (SiC) has gained considerable research and development attention, as an attractive alternative micromachining material to silicon, for realising various microelectromechanical systems (MEMS) sensors and actuators suitable for operation in harsh environments [1][2][3][4][5][6][7]. Thanks to its highly desired material properties such as high physicochemical stability, high hardness, good thermal conductivity, high-temperature operability, wear resistance and chemical inertness.…”

Effect of Transition Metal Compounds on Amorphous SiC Removal Rates

“…These characteristics make them suitable as etch masking layers during advanced semiconductor, solar cell and micro-electro mechanical system (MEMS) fabrication. [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16] Examples of these applications include deep etching of glass or silicon, protection of low-K dielectric films, as a stop layer in STI CMP, etc. 10,12,14 The planar surface necessary to use a-SiC as a hard mask in these applications can be potentially achieved using chemical mechanical planarization (CMP). 14 Since, the a-SiC hard mask layers typically protect an underlying dielectric material, generally SiO 2 , the CMP polish process must be selective to it.…”