AVS 46th International Symposium
    Thin Films Division Monday Sessions
       Session TF-MoM

Paper TF-MoM11
Dielectric Properties of Silicon Nitride Deposited by High Density Plasma Enhanced Chemical Vapor Deposition@footnote 1@

Monday, October 25, 1999, 11:40 am, Room 615

Session: Fundamentals of PECVD
Presenter: J.B.O. Caughman, Oak Ridge National Laboratory
Authors: J.B.O. Caughman, Oak Ridge National Laboratory
D.B. Beach, Oak Ridge National Laboratory
G.E. Jellison, Oak Ridge National Laboratory
W.L. Gardner, Oak Ridge National Laboratory
Correspondent: Click to Email
The dielectric properties of silicon nitride films have been investigated. The films were deposited on silicon substrates at temperatures <400 degrees C by using a high density inductively coupled plasma source. The plasma source is operated at 13.56 MHz using a flat spiral coil. A nitrogen plasma is formed in the ionization region of the source and 100% silane is injected downstream. Properties of the films are determined by using 2-modulator generalized ellipsometry and FTIR. Growth rates vary from 20-45 nm/min, depending on the processing parameters. For nitrogen/silane gas flow ratios of 0.25 to 10.0, the refractive index of the films (at 350 nm) vary little and are around 1.82. The band gap ranges from 4.5 to 6.2 eV. The addition of hydrogen in the ionization region results in an increase in the refractive index and a reduction in the band gap. For nitrogen/silane ratios of 0.25 to 2.0, the refractive index varies from 2.18 to 1.95 and the band gap varies from 3.1 to 4.4 eV. In addition, the hydrogen content in the film actually decreases with the addition of the hydrogen in the ionization region. A mass spectrometer imbedded in the substrate is used to correlate film properties with processing parameters. It is believed that the addition of the hydrogen increases the reactivity of silane in the gas phase, and that the flux of atomic hydrogen at the surface helps to abstract hydrogen from the growing film. @FootnoteText@ @footnote 1@ORNL is managed by Lockheed Martin Energy Research Corp. for the U.S. Department of Energy under contract no. DE-AC05-96OR22464.