Crystalline SiC thin films deposited at room temperature using pulsed laser ablation of graphite and magnetron sputtering of silicon

Abstract

Crystalline SiC films are typically deposited on substrates at elevated temperatures by sputtering, pulsed laser ablation, thermal chemical vapor deposition (CVD) and CVD plasma assisted. However, high temperature may adversely affect the substrate, especially when metal alloys are used. To maintain substrate properties (temper, dimensional tolerance, etc.), a low deposition temperature is required. In this work, silicon carbide is formed from simultaneous sputtering of silicon and laser ablation of graphite onto suitably biased substrates at room temperature. The advantage of this method lies in the independent selection of plasma characteristics of both magnetron sputtering and laser ablation to achieve the required stoichiometry and species energetics. Desirable film properties such as good adhesion and crystallinity normally requiring elevated substrate temperatures are obtained via the energetic bombardment of the growing film. In this study, films are grown on M50 steel substrates at biasing varied from 0 to −300 V permitting control over crystallinity, chemistry, and stoichiometry. X-ray photoelectron spectroscopy (XPS) analysis shows the existence of silicon carbide bonds and x-ray diffraction analysis demonstrated the growth of crystalline (prominently alpha polytypes (4H–SiC, 6H–SiC) films at room temperature. In addition, XPS is used to find percentage of SiC bonds in the films. The optimum bias −100 V was found to favor crystalline growth in these films. Special emphasis is given to control of film stoichiometry as it relates to mechanical properties.