Toshikuni Shinohara

ION ENERGY, ION FLUX, AND ION SPECIES EFFECTS ON CRYSTALLOGRAPHIC AND ELECTRICAL PROPERTIES OF SPUTTER-DEPOSITED TA THIN FILMS

The effects of ion bombardment conditions on the crystallographic and electrical properties of tantalum thin films grown on SiO2 and Si have been systematically investigated in Ta thin film formation process employing low-energy (<100 eV) inert-gas ion bombardment on a growing film surface. It is demonstrated that the properties of Ta films are strongly dependent upon ion energy and ion flux as well as substrate materials. The bcc-Ta can be formed on SiO2 by controlling impinging ion energy and normalized ion flux defined as the ratio of ion flux to Ta flux ranging lower than 20 eV and higher than 13, respectively, for Ar plasma. Based on these results, low-resistivity bcc-Ta thin films (14.8 μΩ cm at 300 K) have been successfully formed. It is also experimentally shown that the irradiation by ions with different mass numbers has different effects on growing film properties, even if the energy or momentum of the ions is the same. When normalized ion flux is 26, bcc-Ta films can be grown on Si at ion energ...

Gate oxide reliability concerns in gate-metal sputtering deposition process: an effect of low-energy large-mass ion bombardment

Abstract The effects of ion species/ion bombardment energy in sputtering deposition process on gate oxide reliability have been experimentally investigated. The use of xenon (Xe) plasma instead of argon (Ar) plasma in tantalum (Ta) film sputtering deposition for gate electrode formation makes it possible to minimize the plasma-induced gate oxide damage. The Xe plasma process exhibits 1.5 times higher breakdown field and five times higher 50%-charge-to-breakdown ( Q BD ). In the gate-metal sputtering deposition process, the physical bombardment of energetic ion causes to generate hole traps in gate oxide, resulting in the lower gate oxide reliability. The simplified model providing a better understanding of the empirical relation between the gate oxide damage and the ion-bombardment energy to gate oxide in gate-metal sputtering deposition process is also presented.

Improvement of gate oxide reliability for tantalum-gate MOS devices using xenon plasma sputtering technology

The effects of ion species in the sputtering deposition process on gate oxide reliability have been experimentally investigated. The use of xenon (Xe) plasma instead of argon (Ar) plasma in tantalum (Ta) film sputtering deposition for gate electrode formation makes it possible to improve the gate oxide reliability. The Xe plasma process exhibits 1.5 times higher breakdown field and five times higher 50%-charge-to-breakdown (Q/sub BD/). In the Ta sputtering deposition process on gate oxide, the physical bombardment of energetic inert-gas ion causes the generation of hole trap sites in gate oxide, resulting in the lower gate oxide reliability. A simplified model providing a better understanding of the empirical relation between the gate oxide damage and the inert-gas ion bombardment energy in the gate-Ta sputtering deposition process is also presented.