Paper PS-TuP8
Fluorocarbon Films Deposited by c-C₄F₈/N₂/Ar Plasmas: The Effect of N₂-addition on Gas Phase Kinetics and Surface Chemistry

Tuesday, October 29, 2013, 6:00 pm, Room Hall B

Fluorocarbon films deposited using c-C₄F₈/N₂/Ar capacitively coupled plasmas are studied with the goal of understanding the effects of N₂-addition on surface chemistry. The plasma system used is a parallel-plate discharge sustained by a 13.56 MHz power source with the electrode diameter 25.4 cm and a gap distance 6 cm . Quartz crystal microbalance (QCM), Fourier transform infrared spectroscopy (FTIR), x-ray photoelectron spectroscopy (XPS), and contact angle measurement are used to characterize the film properties. QCM measurements show a monotonically increase in the deposition rate with N₂ addition, suggesting that CN_xF_y deposition rate surpassed the rate of forming volatile species. FTIR spectra show an additional adsorption near 1350 cm^-1 for conditions with N₂ addition. This can be caused by either the incorporation of nitrogen into the polymer chain or by creation of additional disordered sp² carbon in the film. The XPS C_1s spectrum of the film shows four major peaks, assigned to CF_x (x= 1, 2, 3) and C-CFbonds. With N₂ admixture, CFN bonds appear in the C_1s spectrum, while the amount of CF₃ and CF₂ bonds only decrease slightly. In support of the XPS data, the water contact angle on FC films remains 100~110°and does not change noticeably with N₂-addition. At the end of the presentation, the process significance in N₂ addition into c-C₄F₈/Ar/N₂ plasmas will be discussed.