Sputtering of amorphous SiN induced by 540 keV C irradiation

540 keV C照射によって誘起された非晶質SiNのスパッタリング

北山 巧*; 森田 陽亮*; 中嶋 薫*; 鈴木 基史*; 鳴海 一雅; 齋藤 勇一; 松田 誠  ; 左高 正雄*; 辻本 将彦*; 磯田 正二*; 木村 健二*

Kitayama, Takumi*; Morita, Yosuke*; Nakajima, Kaoru*; Suzuki, Motofumi*; Narumi, Kazumasa; Saito, Yuichi; Matsuda, Makoto; Sataka, Masao*; Tsujimoto, Masahiko*; Isoda, Shoji*; Kimura, Kenji*

Our previous observation of an ion track by sub-MeV C-ion bombardment of a thin amorphous silicon nitride (a-SiN) film with transmission-electron microscopy has shown a large density reduction in the core region, and it suggests emission of thousands of atoms from the cylindrical region. Sputtering yields of a-SiN films by C ions were evaluated in order to confirm this suggestion. A-SiN films deposited on Si(001) were irradiated with 540-keV C ions at fluences up to 110 ions/cm. The sputtering yields were estimated to be 3900500 N atoms/ion and 15001000 Si atoms/ion from the compositional depth profiles measured with high-resolution Rutherford-backscattering spectroscopy. The sputtering yield of N was two orders of magnitude larger than the elastic sputtering yield by the SRIM code, indicating that the observed sputtering yield cannot be explained by elastic collisions. The sputtering yield of an a-SiN film by 100-MeV Xe ions was also measured in order to confirm a possibility of electronic sputtering. Although the electronic stopping power for 100-MeV Xe is more than twice larger than that for 540-keV C, the observed sputtering yield was only 500200 atoms/ion. This indicates that the huge sputtering yield for the impact of C cannot be explained by the simple electronic sputtering, either. A possible explanation might be a synergistic effect of the nuclear and electronic stopping powers.