Simulating the effects of surface diffusion on electron beam induced deposition via athree-dimensional Monte Carlo simulation

Abstract

The effects that adsorbed precursor surface diffusion has on electron beaminduced deposition are explored via a three-dimensional Monte Carlo simulation.Initially the growth rate and resolution are compared for a common set ofdeposition conditions with a variable surface diffusion coefficient ranging from 0 to1 × 10−8 cm2 s−1. The growth rate and resolution are shown to both be enhanced as the growthchanges from a mass transport limited regime to a reaction rate limited regime. Thecomplex interplay between the vertical growth rate, the lateral growth rate, theinteraction volume and the adsorbed and diffused precursor species are discussed.A second scenario is also simulated in which only gas diffused from a constantsource at the perimeter of the simulation boundary is assumed (no gas phaseadsorption). At low diffusion coefficients, the diffusing gas is consumed by secondary andbackscattered electrons and experimentally observed ring-like structures are generated. Athigher diffusion coefficients, the diffusion length is sufficient for the precursoratoms to diffuse to the center (and up the pillar sidewalls) to generate nanowires.