AVS 47th International Symposium
    Plasma Science and Technology Tuesday Sessions
       Session PS-TuP

Paper PS-TuP21
Transmission Line Effects and Chlorine Plasma Characterization in an Inductively Coupled Plasma Etch Reactor

Tuesday, October 3, 2000, 5:30 pm, Room Exhibit Hall C & D

Session: Poster Session
Presenter: M.H. Khater, University of Texas at Dallas
Authors: M.H. Khater, University of Texas at Dallas
L.J. Overzet, University of Texas at Dallas
Correspondent: Click to Email
Transmission line (i.e. standing wave) effects in inductively coupled plasma sources impact the plasma and processing uniformity. In this work we show standing wave effects on the symmetry and uniformity of power deposition, plasma parameters, and polysilicon etch in chlorine plasma. A new ICP source design, which allows better control of field profiles azimuthal symmetry, is compared to a standard spiral planar coil on an industrial plasma etch reactor. B-dot probe measurements of the free space electromagnetic fields in (r,@theta@) plane for both sources showed improved azimuthal symmetry for the new source. The planar coil generated an azimuthal electric field, E@sub theta@, with a local maxima near the grounded (i.e. high current) lead and a significant azimuthal variations. A three-dimensional electromagnetic field model that includes standing wave effects was developed for both sources. The sources were modeled as uniform transmission lines and the current variation along their lengths was estimated from standard transmission line theory. The model showed good agreement with the measured field profiles. Langmuir probe measurements of chlorine plasma parameters spatial profiles near the dielectric window also showed improved azimuthal symmetry of power deposition with the new source. Parametric characterization of chlorine plasma parameters and their spatial profiles generated with the new source will also be shown. Plasma parameters and their spatial profiles exhibited different scaling behaviors with power and pressure in the power deposition region and the wafer plane. Polysilicon etch rate profiles on 150 mm wafers showed improved azimuthal symmetry and uniformity with the new source.