Substrate bias effect on amorphous diamond-like carbon films deposited by filtered cathodic arc system

• Main Authors: Yew-Bin Shue, 徐耀斌
• Other Authors: Chia-Fu Chen
• Format: Others
• Language: en_US
• Published: 2000
• Online Access: http://ndltd.ncl.edu.tw/handle/64630020977513269711

碩士 === 國立交通大學 === 材料科學與工程系 === 88 === Substrate bias effect on amorphous diamond-like carbon films deposited by filtered cathodic arc system Student : Yew-Bin Shue Advisor : Dr. Chia-Fu Chen Institute of Materials Science and Engineering National Chiao Tung University Abstract In the field of the magnetic recording technology, there is a strong focus on increasing the storage capacity in computer disk drives. The areal density is predicted to reach 10 Gbit/in2 in the next few years. In order to reach this goal the spacing between the magnetic head (read/write transducer) and the magnetic media must reduced without the slider to actually come in to contact with the disk. One obvious way to reduce the magnetic spacing is to reduce the thickness of the protective overcoats. For example, an areal density of 3 Gbit/in2 needs no more than 50 nm magnetic spacing and 10 nm diamond like carbon (DLC) overcoat on both disk and slider, whereas for 10-15 Gbit/in2 recording density, magnetic spacing must be reduce to 25 nm, and overcoats no more than 5 nm. Present choice of carbon overcoat in the magnetic storage hard disk drive industry is sputter deposited. As overcoats get thinner, the performance/reliability of the sputtered carbon films becomes critical, In order to sustain the phenomenal growth rate in areal density, efforts are under way to develop alternative technology. Ion beam CVD, and electron-cyclotron-resonance chemical vapor deposition (ECR-CVD) are adopted to make 5-10 nm thick DLC films. As overcoat thickness reach 5-7 nm, the mechanical properties and corrosion protection become major challenge for DLC process development. Hydrogenated DLC films produced by Ion Beam CVD or ECR-CVD processes have 20-50 % hydrogen by atomic weight and 40-70 % of sp3 content. The films made by these processes may not meet film continuity, mechanical and corrosion requirements at the ultra-thin level (<10 nm). This motivated researchers to develop a new process to produce hydrogen-free, tetrahedral bonding dominated amorphous carbon films by cathodic arc deposition. In the present study, we briefly describe the 45-degree angle magnetic filter cathodic arc deposition process and investigate the influence of substrate bias on hardness of amorphous diamond-like carbon films. And try to correlate the microstructure, chemical composition, and chemical bonding states with hardness of the corresponding films. After deposition, the film properties were analyzed by Raman spectroscopy, Auger Electron Spectroscopy (AES), Fourier transform infrared spectroscopy (FTIR), Nanoindentation system (NIS). Film surface was examined Atomic force microscope (AFM). It was found that DLC films have highest hardness with substrate bias between —50 V to —100 V and the hardness doesn’t seems to have good correlation with Raman I (D)/I (G) ratio. Films have higher hardness when they have higher fraction of sp3 content. It was also found that nitrogen content increase with increasing substrate bias on nitrogen-doped amorphous carbon films and hydrogen content decrease with increasing substrate bias on hydrogen-doped amorphous carbon films. Nitrogen and hydrogen both has effect on the small graphitic crystalline grows. With examination by AFM, it was found that higher substrate bias and high hydrogen gas flow rate could produce smoother film.