AVS 59th Annual International Symposium and Exhibition
    Plasma Science and Technology Thursday Sessions
       Session PS-ThP

Paper PS-ThP22
Diagnostic Studies of Ar/c-C4F8 Plasmas: The Effect of N2-addition on Gas Phase and Surface Kinetics

Thursday, November 1, 2012, 6:00 pm, Room Central Hall

Session: Plasma Science and Technology Poster Session
Presenter: P.K. Kao, National Taiwan University, Taiwan, Republic of China
Authors: P.K. Kao, National Taiwan University, Taiwan, Republic of China
Y.J. Yang, National Taiwan University, Taiwan, Republic of China
P.W. Chiou, Tokyo Electron Taiwan Limited, Taiwan, Republic of China
C.C. Chou, Tokyo Electron Taiwan Limited, Taiwan, Republic of China
C.C. Hsu, National Taiwan University, Taiwan, Republic of China
Correspondent: Click to Email
The effects of N2 addition on gas phase and surface kinetics in c-C4F8 and Ar-containing capacitively coupled plasmas are studied. The plasma is sustained using a 13.56-MHz rf power supply with an L-type matching network. Two systems with different geometries are utilized in this study. The first system consists of a cylindrical glass chamber with an annular ring-shaped powered electrode and a planar sample stage that serves as the grounding electrode. The second system is a parallel-plate discharge chamber with the electrode diameter 25.4 cm and the gap distance 60 mm. Optical emission spectroscopy is used to identify key species and to quantify gas temperature. The surface deposition is analyzed using XPS, FTIR, and SEM. Various solvents are used to test the chemical resistance of the deposited fluorocarbon film. Preliminary optical emission spectroscopic studies identified CN emission, which strongly suggests nitrogen incorporation into the gas phase reaction. The gas temperature is found to be between 1200 and 1350 K under 97 mT with 50 W power, and is found to be insensitive to N2 addition. XPS analysis clearly shows the existence of the N peak, which clearly shows that nitrogen is involved in the surface kinetics. FTIR clearly shows the existence of stretching vibrations of CF2 bond. Under 57 mT and 50 W power with Ar:C4F8=12:4 sccm, the surface fluorocarbon film deposition rate is approximately 25 nm/min. No major effect in this deposition rate is seen with up to 4 sccm of N2 addition. The chemical resistance test shows that this deposited film is not resistant to acetone. This clearly demonstrates that the film is rather different from polytetrafluoroethylene film, which is resistant to various solvents including acetone. Finally, the implication of N2 addition on the etching processes will be discussed.