| AVS 57th International Symposium & Exhibition | |
| Plasma Science and Technology | Wednesday Sessions |
| Session PS1-WeA |
| Session: | Plasma Surface Interactions (Fundamentals & Applications) II |
| Presenter: | K. Ishikawa, Nagoya University, Japan |
| Authors: | K. Ishikawa, Nagoya University, Japan K. Takeda, Nagoya University, Japan H. Kondo, Nagoya University, Japan M. Sekine, Nagoya University, Japan M. Hori, Nagoya University, Japan |
| Correspondent: | Click to Email |
A comprehensive understanding of interaction between plasmas and nano-materials is essential for advanced plasma processing technology. By means of plasma-beams apparatus, complicated processes are expectedly convolved individual contributions such as ion, radical, and photons. The vibrational sum-frequency-generation (SFG) is a beneficial tool for addressing best sensitivity at surface and interface, breaking their centro-symmetry[1]. In this study, we have investigated polymer surfaces exposed to the plasma-beams by using SFG.
Samples used were spin-on methyl-siloxane polymer, which is able to used as low-dielectric-constants (Low-k) film for interconnects. Hydrophobic property exhibits since methyl end group, -CH3, is terminated at end on siloxane.
Plasma beams, which directly extracted from a argon plasma by acceleration between 100 and 400 eV, were irradiated.
The SFG spectroscopy setup consists of a 1064 nm Nd:YAG laser, and optical systems, which create both visible (532 nm) and tunable infrared (1000-4000 cm-1) radiations (Ekspla). The SFG spectra taken were decomposed into individually spectral features by fitting spectra calculated to that measured. Intensity of SFG signal emitted from the surface is phenomenogically expressed as the summation of non-resonant susceptibility and damped Lorentian oscillators, which are characterized by phases, strength, resonant, and damping wavenumber.[2]
Before plasma exposure, peaks at ~2930 and ~2970 cm-1 are arisen from C-H stretch of Si-CH3. This strength coincides with that for a peak at around 1275 cm-1 in infrared spectra. After plasma exposure, surface methyl group is disappeared. At the present, it was interpreted that at early stage under ion irradiation, hydrogen is released from the end-on methyl group to create surface radicals, namely rupture of chemical bonds to methyl group is essential for elimination from end-groups on the surface.[3] Further detailed considerations should be conducted.
The surface modifications of plasmas have been studied by using the plasma-beam apparatus and the SFG spectroscopy. The end-groups of the polymer surface were changed only physical ion bombardments. To understanding surface chemical reactions and physical properties, nano- and atom- scaled views of not only bulk materials but also surface end-groups are informative.
Acknowledgments
This study was partly supported by the Tokai region knowledge cluster, Aichi Science and Technology Foundation.
References
[1] M. Buck, et al., J. Vac. Sci. Technol. A 19, 2717 (2001).
[2] A. G. Lambert et al, Appl. Spectrosc. Rev. 40, 103 (2005).
[3] K. Ishikawa, et al., J. Appl. Phys. 99, 083305 (2006).