Investigation of the Shadow Effect in Focused Ion Beam Induced Deposition.

Chen Fang,Yan Xing

doi:10.3390/nano12060905

Abstract

Due to the precursor gas flow in the focused ion beam induced deposition process, a shadow effect appears behind the shading structures. This article carries out experiments with phenanthrene as the precursor gas and establishes a numerical model to define the shadow area and estimate the intensity of the shadow effect, considering the morphology of shading structure, the beam shift, and the nozzle parameters. Within the shadow area, the precursor molecule adsorption contribution is estimated by calculating the fraction of precursor gas flow in a specific direction. Finally, the number of precursor molecules within the beam impact area influenced by the shadow effect is obtained, emphasizing the important role of gas surface diffusion. The adsorption contribution within the shadow area differs a lot while deposited structures are similar in height. The error between the simulation and the experimental results is about 5%, verifying the accuracy of the proposed model.

Highlights

IntroductionFocused ion beam induced deposition (FIBID) and focused electron beam induced deposition (FEBID) are mature, direct-writing additive technologies at micro/nano scale [1–3]
Focused ion beam induced deposition (FIBID) and focused electron beam induced deposition (FEBID) are mature, direct-writing additive technologies at micro/nano scale [1–3].Due to their high resolution, strong local fabrication capability and convenience, they have been widely used in the rapid prototyping of complex structures [4–6], the manufacture of functional devices [7–9], and the creation of metamaterials [10–12]
The numerical model consists of four parts, the shadow area defining model (SADM), the precursor gas flow model (PGFM), the extended precursor molecules diffusion model (EPMDM), and the continuous cellular automata (CCA)

Summary

Introduction

Focused ion beam induced deposition (FIBID) and focused electron beam induced deposition (FEBID) are mature, direct-writing additive technologies at micro/nano scale [1–3]. Due to their high resolution, strong local fabrication capability and convenience, they have been widely used in the rapid prototyping of complex structures [4–6], the manufacture of functional devices [7–9], and the creation of metamaterials [10–12]. The dissociation of precursor molecules in FIBID and FEBID process is mainly caused by the secondary electrons [13–15]. The growth rate of deposition structure relies on the flux of precursor gas and incident ions or electrons. The flux of incident ions or electrons is controlled by current, voltage and optical lens equipment [16,17]. From the perspective of the dynamic motion of precursor molecules, the precursor gas flux is determined by four items: adsorption, surface diffusion, decomposition, and desorption

Methods

Results

Conclusion