AVS 52nd International Symposium
    Plasma Science and Technology Tuesday Sessions
       Session PS-TuM

Paper PS-TuM1
Investigation of Plasma-Surface Interaction by Sheath-Lens Focusing Effects

Tuesday, November 1, 2005, 8:20 am, Room 304

Session: Plasma Surface Interactions I
Presenter: E. Stamate, Nagoya University, Japan
Authors: E. Stamate, Nagoya University, Japan
H. Sugai, Nagoya University, Japan
Correspondent: Click to Email
Present trends in nano-technologies involve reactive plasmas of complex chemistry that makes it difficult to evaluate and control all surface reactions. Recently we discovered that the sheath forming to a biased target interfacing an insulator acts as an electrostatic lens that exhibits two focusing effects.@footnote 1@ The discrete-focusing leaded to the formation of a passive surface of no charge impact, near the target edge, and the modal-focusing resulted in the formation of certain modal-spots and/or modal-lines on the active surface. So far, several applications to plasma diagnostics (negative ion detection, sheath thickness measurements) and ion flux control in plasma immersed ion implantation have been reported. In this work we are demonstrating by simulations and experiments the possibility to use the focusing effects to investigate the surface reactions induced by beams of focused positive and negative ions and/or dusty particles. Measurements are done in DC and ICP discharges using Ar/SF6, O2 and CF4 gases. Sheath accelerated ion beams with energy ranging from 50 to 500 eV are directed by focusing effect to samples of various geometries (disk, square and complex three-dimensional shapes) made of different materials (metals or semiconductors). Surface investigation by AFM and SEM shows the influence of the ion dose and incidence angle to the sputtered profile. Depending on the competition between sputtering and deposition of by products the formation of cluster like structures is also observed. Simulations of the sheath potential structure and ion and dust kinetics are done in three dimension. The ion and dust flux on target surface is found in an excellent agreement with experiments. This work was partialy supported by the 21st Century COE Program of MEXT, Japan. @FootnoteText@@footnote 1@ E. Stamate and H. Sugai, Phys. Rev. Lett. 94, 125004 (2005).