AVS 59th Annual International Symposium and Exhibition
    Plasma Science and Technology Tuesday Sessions
       Session PS2-TuA

Paper PS2-TuA2
Reactive Etching or Deposition Properties of Silicon Halide Ions in Gate Etching Processes

Tuesday, October 30, 2012, 2:20 pm, Room 25

Session: Plasma Surface Interaction during Plasma Etching
Presenter: T. Ito, Osaka University, Japan
Authors: T. Ito, Osaka University, Japan
K. Karahashi, Osaka University, Japan
S. Hamaguchi, Osaka University, Japan
Correspondent: Click to Email
As semiconductor devices continue to miniaturize, a better understanding of basic reactions of etching and/or deposition processes on substrate surfaces has become more importantthan before for finer controls of device structures in the manufacturing processes. In typical gate etching processes by halogen plasmas (such as HBr plasmas), Si atoms that are desorbed from the substrate surface and enter the plasma may form silicon halide ions (such as SiBr+) or charge neutral radicals (such as SiBr) and serve as additional etchants. For example, silicon halide ions in the plasma may also be accelerated by the sheath voltage and re-enter the substrate surface. They also may interact with the sidewalls and deposit Si there. Therefore Si containing ions and charge-neutral species may affect etching yields and etched profiles.To clarify the roles of such species in gate etching processes, we have examined sputtering or deposition reactions of Si, Si3N4, and SiO2 substrateswith silicon halide ions, using a mass-analyzed ion beam system. The ion beam system allows one to irradiate a sample surfacewith a specific ionic species at a given incident energy under ultra-high vacuum conditions and evaluate the etching yields and surface chemical reactions. The surface chemistry can be examined by in situ X-ray photoelectronspectroscopy (XPS) and desorbed species by the etching reactions can be detected by a quadrupole mass spectrometer (QMS) installed in the vacuum chamber. In this study, etching yields of silicon bySiClx + orSiFx + ion beams were evaluated with incident energies of 500 – 1000 eV. It has been found that, depending on the incident energy, these species tend to deposit Si on the surface although they also simultaneously etch the substrate. Some properties of such etching/deposition processes may be understood from elementary reaction processes of Si deposition and halogen etching.