| AVS 56th International Symposium & Exhibition | |
| Plasma Science and Technology | Tuesday Sessions |
| Session PS-TuP |
| Session: | Plasma Science and Technology Poster Session |
| Presenter: | H. Yamamoto, Nagoya University, Japan |
| Authors: | H. Yamamoto, Nagoya University, Japan K. Takeda, Nagoya University, Japan M. Sekine, Nagoya University, Japan M. Hori, Nagoya University, Japan T. Kaminatsui, Toshiba Corporation Semiconductor Company, Japan K. Yamamoto, Toshiba Corporation Semiconductor Company, Japan H. Hayashi, Toshiba Corporation Semiconductor Company, Japan I. Sakai, Toshiba Corporation Semiconductor Company, Japan T. Ohiwa, Toshiba Corporation Semiconductor Company, Japan |
| Correspondent: | Click to Email |
Low dielectric constant (low-k) materials for interlayer dielectric are important for the improvement of ULSI devices performance. The low-k films tend to be damaged during plasma processes. The damage free plasma processes are strongly required. Although many researchers have been studying on the plasma damage on the low-k films, there has been little in-situ evaluation of plasma damages. The in-situ evaluation is crucial for the clarification of damage generation mechanism because the damaged low-k films are modified after exposing to atmosphere. This work investigated the mechanism of plasma ashing damage on the porous SiOCH films by in-situ evaluation. We examined the effect of ions, radicals, and radiation using PAPE technique. The thickness and refractive index of porous SiOCH films were measured using in-situ spectroscopic ellipsometry. Si-CH3 bond absorption was measured using in-situ FT-IR.
The ashing plasma was exited in a 100 MHz CCP etcher. We adopted porous SiOCH films (k = 2.3) as low-k films in this study. The ashing process condition was total gas pressure of 2.0 Pa, 100 MHz source power of 450 W, substrate temperature of 20 °C. In the evaluation, a Si plate or a MgF2 window which transmits the radiation (greater than 115 nm in wavelength) were placed at 1 mm above or just on the low-k film during the ashing. We carried out 4 kinds of experiments : (a) nothing for evaluating of the interaction of ions, radicals, and radiation, (b) Si plate for evaluating of the effect of radicals, (c) MgF2 window for the interaction of VUV radiation with radicals, (d) MgF2 window with no space for the effect of VUV radiation.
In the case of H2 plasma ashing, we confirmed that the interaction of ions, radicals, and radiation or that of radicals and radiation decreased the thickness of the porous SiOCH film. The interaction of radicals and radiation caused the increase of the refractive index. The interaction of ions, radicals, and radiation or that of radicals and radiation caused the decrease of Si-CH3 bond absorption.
The experimental results showed that H radicals extracted Si-CH3 bond and that effect was drastically promoted by radiation and ions. The decrease of Si-CH3 bond caused the decrease of polarizability and density of the film. However, ions made the film contract. Then, the refractive index of the films exposed to ions, radicals and radiation drastically increased. From these results, we proposed a mechanism of the plasma damages on porous SiOCH films.