AVS 49th International Symposium
    Plasma Science Wednesday Sessions
       Session PS+MM-WeA

Paper PS+MM-WeA1
Plasma Molding Over Trenches and Resulting Ion/Fast-neutral Distribution Functions

Wednesday, November 6, 2002, 2:00 pm, Room C-105

Session: Feature Profile Evolution /Plasma Processing for MEMS
Presenter: D. Economou, University of Houston
Authors: D. Economou, University of Houston
D. Kim, University of Houston
Correspondent: Click to Email
Plasma molding over surface topography finds applications in MEMS microfabrication, neutral beam sources, plasma extraction through grids, and plasma contact with internal reactor parts (e.g., wafer chuck edge). The flux, energy and angular distributions of ions incident on the substrate are of primary importance in these applications. These quantities depend critically on the shape of the meniscus (plasma-sheath boundary) formed over the surface topography. When the sheath thickness is comparable to or smaller than the feature size, the sheath tends to "mold" over the surface topography. A two-dimensional fluid/Monte Carlo simulation model was developed to study plasma "molding" over surface topography. The radio frequency (RF) sheath potential evolution, and ion density and flux profiles over the surface were predicted with a self consistent fluid simulation. The trajectories of ions and energetic neutrals (resulting by ion neutralization on surfaces or charge exchange collisions in the gas phase) were then followed with a Monte Carlo simulation. Ion flow and energy and angular distributions of ions and energetic neutrals bombarding the walls of a trench will be reported. Emphasis will be placed on high aspect ratio features of interest to MEMS and neutral beam sources. Simulation results will be compared with experimental data, taken at Sandia National Labs, on ion flux and ion energy and angular distributions at the bottom of trenches. Work supported by the National Science Foundation and Sandia National Laboratories.