Irradiation driven molecular dynamics simulation of the FEBID process for Pt(PF$_3$)$_4$

Abstract

This paper presents a detailed computational protocol for atomistic simulation of the formation and growth of metal-containing nanostructures during the Focused Electron Beam Induced Deposition (FEBID) process. The protocol is based upon the Irradiation-Driven Molecular Dynamics (IDMD) -a novel and general methodology for computer simulations of irradiation-driven transformations of complex molecular systems by means of the advanced software packages MBN Explorer and MBN Studio. Atomistic simulations performed following the formulated protocol provide valuable insights into the fundamental mechanisms of electron-induced precursor fragmentation and the related mechanism of nanostructure formation and growth using FEBID, which are essential for the further advancement of FEBID-based nanofabrication. The developed computational methodology is general and is applicable to different types of precursor molecules, substrate types, irradiation regimes, etc. In this work it is applied to the IDMD simulation of the FEBID of Pt(PF3)4 -a widely studied precursor molecule -on SiO2 surface. The simulations reveal the processes driving the initial phase of nanostructure formation during FEBID, including nucleation of Pt atoms, formation of small metal clusters on the surface followed by their aggregation and the formation of dendritic platinum nanostructures. The analysis of the simulation results provides space resolved relative metal content, height and the growth rate of the deposits which represent a valuable reference data for the experimental characterization of the nanostructures grown by FEBID.

Atomistic simulation of the FEBID-driven growth of iron-based nanostructures

“…The simulations [11,15] thus demonstrated a predictive power of the IDMD approach for simulating FEBID, yielding the compositions of fabricated nanostructures in good agreement with experimental data [20]. Our recent study [21] provided a detailed description of the IDMDbased computational methodology for modeling the formation and growth of metal-containing nanostructures during FEBID. Different computational aspects of the methodology and the key input parameters describing the precursor molecules, the substrate, and the irradiation and replenishment conditions have been systematically described.…”

“…The MBN Studio toolkit [19] has been utilized to create the systems, prepare all necessary input files and analyze simulation outputs. The step-by-step protocol of the multiscale IDMD-based simulation of the FEBID process [11,15] has been described in detail in the earlier study [21] and is therefore only briefly recapped below.…”

“…The formulated computational protocol has been applied to simulate the FEBID of Pt(PF 3 ) 4 precursor molecules on a fully hydroxylated SiO 2 (SiO 2 -H) surface. Particular focus has been made on the atomistic characterization of the initial stage of the FEBID process, including nucleation of platinum atoms, formation of small metal clusters on the surface followed by their aggregation, and, eventually, the formation of dendritic platinum nanostructures [21].…”

“…In our recent study [21] the morphology, size and metal content of a platinum-containing deposit have been quantitatively analyzed as functions of electron fluence and adsorbate concentration. Particular focus was made on analyzing the morphological transition from isolated metal-enriched islands formed on the substrate into a single metal nanostructure.…”

“…The analysis presented in Ref. [21] was made for a particular regime of precursor replenishment when the number of Pt(PF 3 ) 4 molecules added in the course of the FEBID process has been balanced with the number of fragmented molecules during each irradiation step. In general, the growth of metal nanostructures during the FEBID process is governed by the number of adsorbed precursor molecules and the electron beam parameters, namely the energy of the primary electron beam and the flux of primary and secondary electrons.…”