The synthesis of SiCx films by dual-source sputter deposition

Beta-silicon carbide has been synthesized by sputter deposition from separate elemental silicon and carbon targets onto substrates above 700 °C. Deposited samples had a range of compositions continuously varying from carbon-rich to silicon-rich. Sample thickness and composition were correlated by means of thickness profiles that were compared to models based on ideal atomic volumes in the phases observed. This correlation, in conjunction with analyses of crystalline phases and microstructure, indicated that carbon-rich samples were a combination of beta-SiC and amorphous carbon, and silicon-rich samples consisted of small beta-SiC particles in a silicon matrix that had a layered microstructure. Beta-SiC with (111) preferred orientation was formed at the 1:1 Si:C location. This material had a columnar microstructure with lateral grain size of ∼50 Å and through-film grain size of ∼500 Å. The refractive index of the beta-SiC was comparable to published values and films deposited on sapphire were p-type with sheet resistivity around 2 Ω cm.