AVS 51st International Symposium
    Thin Films Tuesday Sessions
       Session TF+NS-TuA

Paper TF+NS-TuA8
A Three - Dimensional Computer Simulation of Electron - Beam Induced Deposition (EBID)

Tuesday, November 16, 2004, 3:40 pm, Room 303C

Session: Focused Beam Processing & Fabrication
Presenter: J.D. Fowlkes, University of Tennessee, Knoxville
Authors: J.D. Fowlkes, University of Tennessee, Knoxville
P.D. Rack, University of Tennessee, Knoxville
S. Randolph, University of Tennessee, Knoxville
Correspondent: Click to Email
A simulation will be presented of the electron - beam induced deposition (EBID) process that was coded using the Matlab(R) program. The simulation has a Monte Carlo component to predict electron trajectories as well as elastic and inelastic electron â?" substrate interactons. A discretization scheme projects each electron scattering event onto a three dimensional matrix to provide a reference point to test for a host of possible events per matrix node including secondary electron generation and/or EBID. Three phases coexist in the matrix including the precursor gas, the deposited phase and the substrate phase. A dynamic model tracks the gas - surface interaction including precursor adsorption, deposition and desorption under thecontext of a Langmuir type surface coverage. Primary, backscattered, and secondary electrons that escape the gas - pillar and gas - substrate interface may induce deposition based on their trajectory, energy and precursor surface coverage. The probability of EBID is based on a "shifted and scaled" ionization cross-section for the precursor gas molecule to be roughly applied as a dissociation cross - section. Primary (PE) and secondary electrons (SE) contribute most signficantly to the EBID growth of high-aspect ratio nanopillars while backscattered electrons (BSE) play more of a feature coarsening role. Two regimes of pillar growth are observed; a region characterized by linear a growth rate where the electron interaction volume interacts with both the growing pillar and the substrate and a second regime, again linear in growth rate, whereby the penetrating electrons interact solely with the high aspect pillar.