Liquid polycarbosilane derived SiC coating on silicon (111) wafer for enhanced mechanical properties

摘要

Silicon carbide coating on silicon (111) wafer was deposited by modified chemical vapor deposition (CVD) method using liquid polycarbosilane (LPCS) as precursor at three different moderately high temperatures in presence of Argon gas. Glancing angle X-ray diffractometer and Fourier Transform Infrared Spectroscopy reveals smooth β-SiC coating and its subsequent transformation into α-SiC on silicon substrate. In all the temperature the film was found to be uniform with a thickness ranging from 0.6-1.2 μm. The average particle size as can be seen from FESEM ranges from 7 to 385 nm approximately, the lowest range being (7-20 nm) which hitherto has not yet been reported using LPCS as precursor for SiC. Moreover the coated samples show substantial increment of hardness (~18.8 GPa) and toughness (~1.51 MPa m~(1/2)), both of which increases with increase in deposition temperature. The smooth and thin SiC coating on silicon formed in three different moderate temperatures compared to very high temperature for other CVD assisted coating along with enhanced hardness and toughness makes this a promising material in critically harsh environment required for microelectromechanical systems (MEMS) application.