Ping-Yen Hsieh, Tzu-Chun Lin, Ying-Hung Chen, Ju-Liang He, Feng Chia University, Taiwan
Yttrium oxyfluoride (YOF) materials are emerging as promising candidates for semiconductor processing components due to their high plasma etching durability. By taking advantage of high plasma density and high deposition rate, our early study successfully prepared yttrium-based coatings on silicon substrates by using gas flow sputter (GFS) technique. In an oxygen-rich atmosphere, a crystalline, dense columnar structure with a (111) preferred orientation was achieved for the Y2O3 coating, without the need for additional heating. The introduction of CF4 gas during deposition resulted in the formation of yttrium oxyfluoride, comprising YOF and Y5O4F7 phases. To comprehensively assess plasma etching resistance, this study investigates the plasma exposure of these yttrium-based coatings under different gas mixtures, namely CF4/O2, CF4/H2, and C4F8/O2. The findings reveal that the GFS prepared yttrium-based coatings exhibit a far lower plasma etching rate and smooth surface topography compared to bare silicon wafers. Notably, the yttrium oxyfluoride coating demonstrates superior resistance characteristics against various plasma atmospheres. The influence of the Y-F and Y-O bonding structure on yttrium-based coating after exposure to different kinds of fluorine plasma atmospheres by using X-ray photoelectron spectrum (XPS) was discussed in this study. It is concluded that the fluorination in the yttrium-based coating is pivotal for achieving excellent plasma resistance performance. As a result, GFS prepared fluorinated yttrium-based coatings, which display high etching resistance, are highly recommended for use in semiconductor process components.