Thermal chemical vapor deposition of silicon carbide films as protective coatings for microfluidic structures

Amorphous silicon carbide (SiC) films were deposited on silicon substrates by thermal chemical vapor deposition (TCVD) technique, at substrate temperatures ranging from 620 degreesC - 850 degreesC. A novel, single-source halide free precursor, SP-4000, belonging to the family of polysilenemethylenes (PSM) (nominal structure [-SiH2-CH2-](n), n = 2-8 including branched and cyclic isomers) was used as source. Argon was used, as both the precursor carrier gas and the dilution gas. Other reactants, such as hydrogen or hydrocarbons, were not used. The deposition yielded films with Si/C ratio of 1 +/- 0.2. The highest achieved growth rate was 83 nm/min. The modulus of elasticity and the nanohardness of the SiC films were measured with the aid of a nanoindenter at various depths, which did not exceed 25% of the film thickness. The average nanohardness at indentation depths of approximately 10% of the film thickness Was measured up to 13 +/- 4 GPa. The results of the nanoindentation will be discussed in conjunction with the microstructural analysis of the films. In addition, the development of a viable TCVD SiC process presents significant opportunities in the nano/micro systems field. In particular, the ability to custom tailor the surfaces of microfluidic structures allows for the development of valves, pumps and channels for use in corrosive or high temperature environments. Initial results from the deposition of SiC films on prototype microfluidic components will be presented.