| MEMS applications require that large area of uniform SiC films is formed on insulating substrates or sacrificial layers. For electrically controlled MEMS devices, in-situ N2-doped 3C-SiC thin-films have been grown by low-pressure chemical vapor deposition (LPCVD) on low-stress, amorphous Si3N4/p-Si(111) substrate using the single organosilane precursor trimethylsilane [(CH3)3SiH]. The effects of N2 flow rate and growth temperature on the electrical properties of SiC films were investigated by Hall Effect measurements. The electron carrier concentration is between 1017∼10 18/cm3. The lowest resistivities at 400 K and 300 K are 1.12 × 10−2 and 1.18 × 10−1 Ω·cm, respectively. The corresponding sheet resistances are 75.02 and 790.36 Ω/□. The SiC film structure was studied by X-ray diffraction (XRD). The 3C-SiC films oriented in the <111> direction with a 2&thetas; peak at 35.5° and line widths between 0.18°∼0.25° were obtained. The SiC-Si3N4 interface is very smooth and free of voids. To pattern the SiC films into the desired structural shapes, selective etching is required. The inductively coupled plasma (ICP) etching of 3C-SiC films was then examined in both NF3/Ar and Cl2/Ar mixtures. Two different mask materials (ITO and Shipley 1818 photo-resist) were compared. The effects of RF power, DC bias, ICP power and gas flow ratio on etch rates have been discussed.; Furthermore, a novel fiber-optic temperature sensor, which is rugged, compact, stable, and can be easily fabricated, has been developed by using the SiC thin-film grown on sapphire substrate. The film thickness was optimized to 2∼3 μm, while the optimal 3MS flow rate ranged from 35∼40 sccm to produce an optically flat SiC film. The sensors were operated at temperature from 22°C to 540°C. The shifts in resonance minima versus temperature from the reflection spectra fit a linear function, giving a relative temperature sensitivity of 1.9 × 10−5/°C. The capability of providing a ±3°C accuracy was discovered at 532°C in a wide-open ambient, through a 14-days operating life. |
