Chia-Ying Liou¹, Ping-Yen Hsieh¹, Shih-Nan Hsiao², Ying-Hung Chen¹, and Ju-Liang He^1
1Feng Chia University, Taiwan
²Nagoya University, Japan
Recently, as a realization of the ultrafine circuit wafer process in the semiconductor industry, highly plasma etching resistant materials have been continuously required for its severe etching process. Among the plasma etching resistant materials, silicon carbide is drawing significant interest due to its strong bonding structure, high chemical stability, and passive to halogen plasma under extreme etching conditions. Most importantly, SiC consists only of silicon and carbon and, thus, is free from metal-contamination issues during silicon wafer processing. By taking advantage of high plasma density, free from target poisoning and high deposition rate, a gas flow sputtering (GFS) technique was used for reactive deposition in this study to obtain SiC coating on silicon wafer for anti-plasma etching purposes. The effects of process parameters on the film microstructure are extensively investigated. The dielectric breakdown strength and anti-plasma etching ability of the obtained GFS-SiC coating are also evaluated.
The results show that the obtained GFS-SiC coating exhibits a dense columnar structure, and the deposition rate can reach over 5 μm/h, which is substantially higher than those of many PVD and CVD processes. Under high-resolution transmission electron microscopic examination, nanocrystalline features can be observed in the GFS-SiC coating at a deposition temperature of 750°C. Furthermore, based on the high-resolution X-ray photoelectron spectroscopy (XPS) results, an increase in acetylene flow rate leads to an increase in C-C bonds, whereas a significant increase in C-Si bonds with the increasing deposition temperature. The dielectric breakdown strength value for GFS-SiC coating is as high as 300 kV/mm. In addition, the plasma etching rate of GFS-SiC coating is at least five times less than that of bare Si wafers when exposure to fluorocarbon plasma. These results indicate that GFS-SiC coating has excellent resistance to plasma etching and holds significant potential for applications in plasma etching equipment, related components, and masks for etching.