G. Bose

Mechanical and structural properties of RF magnetron sputter-deposited silicon carbide films for MEMS applications

In the present work, we report preparation and characterization of silicon carbide (SiC) films obtained by RF magnetron sputtering using a SiC ceramic target. The films were deposited in Ar ambient without external substrate heating. The residual stress of the films was measured as a function of sputtering parameters. The stress of the as-deposited films was observed to be compressive for the entire range of sputtering parameters used in the present work. Postdeposition annealing at 400 ?C in N2?ambient was useful in reducing the stress in the films. On sequentially annealing the films at higher temperatures (600 and 800 ?C), the nature of the stress changed from low compressive to high tensile. A superhard SiC film with low residual compressive stress (58.7 MPa) was obtained with hardness and Youngs modulus values of 49.86 GPa and 363.75 GPa respectively. The x-ray diffraction pattern revealed that the films were either amorphous or nano-crystalline, depending on the deposition parameters and postdeposition annealing temperature. Atomic force microscopy roughness results confirmed good chemical stability of the films in potassium hydroxide and buffered hydrofluoric acid solutions. Several types of micro-structures were fabricated to demonstrate the feasibility and compatibility of these films in MEMS fabrication.

Synthesis of buried silicon nitride layers by rapid thermal annealing

Abstract Buried layers of silicon nitride (Si3N4) were synthesised by rapid thermal annealing (RTA) of high-dose (1018 ions cm−2) nitrogen implanted (at 150 keV) silicon. The influence of RTA temperature and time on the formation of buried layers of silicon nitride was studied by IR transmission and X-ray diffraction techniques. It is found that RTA at 1200 °C for 150 s or 1250 °C for 100 s results in buried polycrystalline silicon nitride layers. The results are compared with those obtained by traditional furnace annealing.