Effects of process parameters on the properties of fluorinated amorphous carbon films prepared by plasma enhanced chemical vapor deposition

• Main Authors: Sheng-Che Chiou, 邱聖哲
• Other Authors: Sham-Tsong Shiue
• Format: Others
• Language: zh-TW
• Published: 2011
• Online Access: http://ndltd.ncl.edu.tw/handle/90252475393777667086

碩士 === 國立中興大學 === 材料科學與工程學系所 === 99 === The properties of fluorinated amorphous carbon (a-C:F) films prepared by plasma enhanced chemical vapor deposition (PECVD) method are investigated. Hexafluorethane (C2F6), acetylene (C2H2), and argon (Ar) were used as the precursor gases. The mass flow rate of C2H2 and (C2F6+Ar) are fixed at 10 and 10 sccm, respectively. Additionally, the working pressure, substrate temperature, and radio-frequency power were 33.3 Pa, 293 K, and 100 W, respectively. Six kinds of (a-C:F) films were prepared with the C2F6/(C2F6+Ar) ratio of 0, 20, 40, 60, 80, and 100 %. Experimental results show that the deposition rate of a-C:F films increases from 111 to 215 nm/min as the C2F6/(C2F6+Ar) ratio increases from 0 to 100 %. When the C2F6/(C2F6+Ar) ratio increases from 0 to 20 %, the C-C and C-Hx bonds are mainly changed to the C-F bonds. Nevertheless, when the C2F6/(C2F6+Ar) ratio increases from 20 to 100 %, the C-F bonds are changed to the C-F2 and C-F3 bonds. When the C2F6/(C2F6+Ar) ratio increases from 0 to 100 %, the optical band gap increases from 0.84 to 2.39 eV and the water contact angle increases from 61 to 90 degrees, but the surface free energy reduces from 45.0 to 20.6 mN/m. This result indicates that as C2F6 is added in C2H2, a-C:F films are shifting to polymer-like and become hydrophobic. As the C2F6/(C2F6+Ar) ratio is 100 %, the radio-frequency power increases from 50 to 150 W, the deposition rate of carbon films increases from 159 to 230 nm/min; the C-Fx bonds in the carbon films increase, and the energy band gap increases from 2.25 to 2.56 eV. Alternatively, as the radio-frequency power increases from 150 to 250 W, the deposition rate of carbon films decreases from 230 to 90 nm/min; the C-Fx bonds in the carbon films decrease, while the F2C=C bonds increase. The e energy band gap decreases from 2.56 to 2.00 eV, and the carbon films structure shifts to graphite-like. As the C2F6/(C2F6+Ar) ratio is 100 %, the working pressure increases from 33.3 to 66.7 Pa, the free path of plasmas gas decreases, and thus, the ordered degree of carbon films structure decreases. When the working pressure is 66.7 Pa, the carbon film has a maximum water contact angle of 102.3 degree, and thus the carbon film become hydrophobic.