| AVS 55th International Symposium & Exhibition | |
| Plasma Science and Technology | Thursday Sessions |
| Session PS2-ThM |
| Session: | Plasma Modeling |
| Presenter: | F. Hamaoka, Keio University, Japan |
| Authors: | F. Hamaoka, Keio University, Japan T. Yagisawa, Keio University, Japan T. Makabe, Keio University, Japan |
| Correspondent: | Click to Email |
Reactive ion etching (RIE) used for fabricating a nanometer-scale element of the semiconductor device has been applied to the process of a micro-scale etching in micro-electro-mechanical system (MEMS). Plasma molding is one of the important issues in micro-scale etching with several tens or hundreds of micrometers in width and depth.1 In our previous study, the influence of the ion transport under the distorted sheath potential, i.e., plasma molding, on the anisotropic Si etching was numerically investigated without considering the neutral reaction.2 In addition to the effect of ions, we developed the gas-phase and surface model for Deep-RIE of Si in a 2f-CCP in SF6/O2 under competition between Si etching and passivation layer formation, including the effect of plasma molding.3 These investigations imply that the ions incident on the wafer under the distorted sheath potential by plasma molding remove the passivation (SiOxFy) layer on the sidewall and bottom corner, suppressing etch anisotropy. In this study, we numerically investigate the feature profile evolution of Deep Si etching under the presence of the plasma molding in 2f-CCP in SF6/O2 as functions of gas mixture and pressure with different widths of micro-scale pattern. The sidewall etching is suppressed drastically with increasing the oxygen mixture ratio due to forming the passivation layer by oxygen radicals on the Si surface. In SF6/O2(50%) at 300 mTorr, the etching profile of 250μm-wide-pattern is distorted especially at the bottom corner because of the excess ions with radially distorted angular distribution by plasma molding. On the other hand, at 100 mTorr, the etching profile at the bottom is flattened by chemical effect at the center due to the smaller flux of O(3P) than that at 300 mTorr; however, the sidewall etching occurs slightly. We will also discuss the etching profile with different pattern widths under plasma molding in 2f-CCP in SF6/O2.
1 D. Kim and D. J. Economou, IEEE. Trans. Plasma Sci., vol. 30, no. 5, pp. 2048–2058, 2002.
2 F. Hamaoka, T. Yagisawa, and T. Makabe, Jpn. J. Appl. Phys., vol. 46, no. 5A, pp. 3059-3065, 2007.
3 F. Hamaoka, T. Yagisawa, and T. Makabe, IEEE Trans. Plasma Sci., vol. 35, no. 5, pp. 1350-1358, 2007.