AVS 47th International Symposium
    Plasma Science and Technology Tuesday Sessions
       Session PS2-TuA

Paper PS2-TuA10
Electron Energy Control in Large-Diameter Inductively Coupled Plasma for High Performance of Etching

Tuesday, October 3, 2000, 5:00 pm, Room 311

Session: Plasma Diagnostics I
Presenter: T. Urayama, Tokai University, Japan
Authors: T. Urayama, Tokai University, Japan
T. Tsurumi, Tokai University, Japan
Y. Horiike, The University of Tokyo, Japan
S. Fujii, ADTEC Co., Ltd., Japan
H. Shindo, Tokai University, Japan
Correspondent: Click to Email
A method of electron energy control was studied in an inductively coupled plasma of a large diameter employing the multimode antenna, for high performance in device fabrication etching plasma processes. In etching plasmas, the electrons are prone to be excessively energetic in high density plasmas generated at low pressures. In SiO2/Si selective etching, for example, the high etching selectivity has been hardly realized under high etch rate, and this is understood as the radical density is too much low compared with the ion density. This happens eventually because the electron energy becomes too high at low pressures. The experiment was carried out in an inductively coupled plasma which was produced in a stainless-steel chamber of 350 mm in diameter by supplying the RF power of 13.56 MHz through the quartz window at one end. The electron energy could be reduced by changing the azimuthal mode of one-turn antenna from m=0 to m=2 with no notable change in electron density. The electron energy reduction was found higher in the higher mode and essential at low pressures by Langmuir probe measurement. These behaviors were also confirmed by optical emission spectroscopy. The method was extended to two-loop antenna with different diameters which enabled us to make the radial mode as well as the azimuthal mode. It was verified that these two-loop antenna with the modes could imporove the radial uniformity as well as the electron energy reduction, and a physical sputter etch rate of Si showed 5% radial uniformity in 12 ich area. It was concluded that the electron free path divided by the induction field reverse distance was the essential parameter in electron energy control.