| AVS 59th Annual International Symposium and Exhibition | |
| Plasma Science and Technology | Monday Sessions |
| Session PS2-MoA |
| Session: | Plasma Modeling |
| Presenter: | Y. Kondo, Nagoya University, Japan |
| Authors: | Y. Kondo, Nagoya University, Japan Y. Miyawaki, Nagoya University, Japan K. Takeda, Nagoya University, Japan H. Kondo, Nagoya University, Japan K. Ishikawa, Nagoya University, Japan T. Hayashi, Nagoya University, Japan M. Sekine, Nagoya University, Japan M. Hori, Nagoya University, Japan |
| Correspondent: | Click to Email |
Excellent etch properties such as high etch rate, high selectivity, fine profile, are required for interlayer dielectric film processing for ULSI circuits to achieve high device performances. The etch properties depend on the composition and amount of active species, i.e. ions and radicals which are strongly correlated with the molecular structure of feedstock gas. To choose the most appropriate feedstock gas for designing a specific etch process, it is favorable to understand the detailed relationship among gas molecule structure, active species and etch performance. It may also lead to suggest a new gas with extreme high performance.
In previous study, we have developed a SiO2 etch process using CF3OCFCF2 (C3F6O). C3F6O has characteristic molecular structures such as an ether bond, a CF3 group and a double bond. Relatively high etch rate for SiO2 is expected for the C3F6O plasma chemistry since the major fragment ion of C3F6O is CF3+ that is known to show high etch yield for SiO2[1]. Detailed relationship among the gas molecule structure, etch species and etch performance, however, has not clarified so far.
In this study, we have developed a chemical model of reactions in C3F6O/Ar plasma and simulated it using chemical kinetics simulation software, CHEMKIN. The experimental results were compared with the results obtained by the model. Then, we clarified the generation pathway of ions and radicals, and evaluated effects of the difference of these pathways on the composition of active species. Then we considered the relationship between molecule structure and the generation of active species.
Electron induced dissociation channels of C3F6O were evaluated by analysis of cracking patterns measured using a quadruple mass spectrometer. Cross-section for ionizing dissociation of C3F6O was estimated through a range between a few to 50 eV for electron energy [2]. Reaction constants for this dissociative ionization were calculated by integrating over whole electron energy range assuming the electron temperature as 3 eV. Using these constants and constants on previous model for CF4, C2F6, and C4F8 chemistry [3, 4], the chemical model of gas phase reactions in the C3F6O/Ar plasma was constructed, and enabled us to estimate the concentrations for gas phase species. We also evaluated the dependence of the concentrations on electron density, partial pressure of feedstock C3F6O gas and residence time.
[1] K. Karahashi, et al. : J. Vac. Sci. Technol. A 22, 1166 (2004).
[2] H. Toyoda, et al. : Jpn. J. Appl. Phys. 36, 3730 (1997).
[3] G. I. Font et al., J. Appl. Phys. 91 (2001) 6.
[4] A. V. Vasenkov et al., J. Vac. Sci. Technol. A 22 (2004) 3.