AVS 45th International Symposium
    Plasma Science and Technology Division Friday Sessions
       Session PS-FrM

Paper PS-FrM8
Surface Chemistry Mechanism of Oxide Etching by High Density C@sub 2@F@sub 6@ Plasma

Friday, November 6, 1998, 10:40 am, Room 318/319/320

Session: Plasma-Surface Interactions - II
Presenter: D.J. Economou, University of Houston
Authors: J. Feldsien, University of Houston
T. Panagopoulos, University of Houston
D.J. Economou, University of Houston
Correspondent: Click to Email
Fluorocarbon plasmas have been studied extensively because of their use in selectively etching oxide over silicon. It is widely known that these plasmas produce unsaturated fluorocarbon radicals that may polymerize on surfaces in contact with the plasma. Oxide surfaces exposed to intense ion bombardment, on the other hand, are etching. More work remains to be done to understand the mechanisms that produce the observed behavior. In this work, a comprehensive surface chemistry model was developed to understand the mechanism of etching or deposition on oxide surfaces exposed to a high density C@sub 2@F@sub 6@ plasma. The surface chemistry model in combination with a gas phase plasma chemistry model developed by E. Meeks and J. Johannes of Sandia National Labs was implemented in the Modular Plasma Reactor Simulator (MPRES) to study oxide etching and uniformity under typical processing conditions. Simulation results on etch rate and uniformity as a function of source power, bias power, and pressure were consistent with experimental data. The transition from polymerization to etching as the ion bombardment energy (bias power) was increased was also captured by the simulation. Under low pressure conditions (several mtorr) the ion flux peaked at the wafer center while the neutral flux peaked at the wafer edge. Under such conditions, the oxide etch rate was edge fast. This supports the important conclusion that oxide etching is ion driven but neutral dominated. Surface coverages by important species and their interrelation to etch or deposition rate will also be discussed. This work was supported by Sandia National Laboratories/SEMATECH.