| AVS 57th International Symposium & Exhibition | |
| Plasma Science and Technology | Wednesday Sessions |
| Session PS2-WeA |
| Session: | Neutral Beam Processing |
| Presenter: | A. Wada, Tohoku University, Japan |
| Authors: | A. Wada, Tohoku University, Japan K. Endo, National Institute of Advanced Industrial Science and Technology (AIST), Japan M. Masahara, National Institute of Advanced Industrial Science and Technology (AIST), Japan S. Yamasaki, National Institute of Advanced Industrial Science and Technology (AIST), Japan S. Samukawa, Tohoku University, Japan |
| Correspondent: | Click to Email |
To fabricate a metal-oxide-semiconductor field-effect transistor (MOSFET) with a three-dimensional (3D) structure several problems arise in the conventional thermal oxidation process, such as high temperature, the dependence of the oxidation rate on the lattice plane of silicon (Si) and non-oriented oxidation process. After high temperature processing, compression stress remains in the SiO2 film due to the difference in thermal expansion coefficient between the Si substrate and SiO2 film. The compression results in defects in the SiO2 film, which leads to increased leakage current. Furthermore, in the case of gate oxidation in the fabrication of 3D MOSFETs, the oxide film on a 3D structure and substrate is not consistent due to the different oxidation rates resulting from different lattice planes between them, which cause a concentration of the electric field and dielectric breakdown. Moreover, conventional thermal oxidation (TO) process is non-oriented oxidation process which forms oxide film on whole Si surface, and hence, it is difficult to independently control the thickness of the dual-gate dielectric film such as a four-terminal FinFET. To overcome these problems, we propose low-temperature (< 300ºC) damage-free neutral beam oxidation (NBO) as an alternative oxidation process. We found that oxide film grown by NBO (NBO film) even at a low substrate temperature (300 ºC) exhibits performance characteristics of a gate dielectric film that are as high as that of thermal oxide film in terms of the relationship between equivalent oxide thickness (EOT) and leakage current. This is because beam-induced oxidation plays a dominant role in the formation of NBO films by bombardment with an oxygen neutral beam. Also, the oxidation rate of NBO is independent of the lattice plane of silicon, and the oxidation is anisotropic. Therefore, oxide film grown by NBO is advantageous in that it can be applied to a gate dielectric film for a 3D fin structure of MOSFET.