AVS 51st International Symposium
    Plasma Science and Technology Monday Sessions
       Session PS1-MoA

Paper PS1-MoA6
Etching of Passivated SiO@sub 2@ Film by Fluorocarbon Ions: A Molecular Dynamics Study

Monday, November 15, 2004, 3:40 pm, Room 213A

Session: Plasma Surface Interactions in Etching
Presenter: V. Pavlovsky, Sarov Labs., Russia
Authors: V. Smirnov, Sarov Labs., Russia
A. Stengatch, Sarov Labs., Russia
V. Pavlovsky, Sarov Labs., Russia
S. Rauf, Freescale Semiconductor
P. Stout, Freescale Semiconductor
P.L.G. Ventzek, Freescale Semiconductor
Correspondent: Click to Email
Fluorocarbon plasmas are widely used for etching of dielectric thin films in the microelectronics industry. Fluorocarbon radicals and ions are known to produce a thin passivation layer (~ 2 nm) on the dielectric surface, whereupon energetic ion bombardment leads to dielectric material etching. As the passivation films are extremely thin and in-situ monitoring is difficult during etching, very few experimental studies have been able to probe into the fundamental nature of fluorocarbon based dielectric etching. Computational molecular dynamics (MD) is one technique that has proven useful for such studies. This paper reports about a MD based investigation of fluorocarbon passivated SiO@sub 2@ film etching by CF@sub x@ (x=1, 2, 3) ions. Our MD code is 3-dimensional and uses the velocity-Verlet method for particle acceleration. Psuodo-potentials for two and three body interactions of Si, O, C, and F have been assembled either using Gaussian based quantum chemistry computations or data available in literature. A variety of fluorocarbon passivation films (with varying thickness and F/C ratio) are prepared by bombarding low to medium energy fluorocarbon ions on SiO@sub 2@. Impact of energetic (50-1000 eV) CF@sub x@ ions on these passivation films is then investigated, and modeling results are used to determine ion etch yield, nature of sputtered clusters, and their energy and angular distributions. Modeling results clearly demonstrate that presence of a fluorocarbon passivation film enhances etch yield compared to a similar but otherwise unpassivated SiO@sub 2@ film. Etch yields peak at an off-normal angle, and SiO@sub x@F@sub y@ constitute the bulk of Si containing sputtered clusters.