Dose and energy dependence of mechanical properties of focused electron beam induced pillar deposits from Cu(C5HF6O2)2

TL;DR

This study investigates how the mechanical properties of copper-based deposits created by focused electron-beam induced deposition vary with electron energy and dose, revealing dependencies in Young's modulus, density, and quality factors.

Contribution

It provides the first detailed analysis of how electron energy and dose influence the mechanical properties of FEB deposits from Cu(C5HF6O2)2, combining experimental and finite element methods.

Findings

Young's modulus increases with electron dose from 17 to 25 GPa.

Material density depends on primary electron energy, from 1.2 to 2.2 g/cm³.

Quality factors range from 150 to 600, correlating with irradiation energy.

Abstract

Bending and vibration tests performed inside the scanning electron microscope were used to mechanically characterize high-aspect pillars grown by focused electron-beam (FEB) induced deposition from the precursor Cu(C5HF6O2)2. Supported by finite element (FE) analysis the Young's modulus was determined from load-deflection measurements using cantilever-based force sensing and the material density from additional resonance vibration analysis. The pillar material consisted of a carbonaceous (C, O, F, H containing) matrix which embeds 5...10 at. % Cu deposited at 5 keV and 20 keV primary electron energy and 100 pA beam current, depending on primary electron energy. Young's moduli of the FEB deposits increased from 17+/-6 GPa to 25+/-8 GPa with increasing electron dose. The density of the carbonaceous matrix shows a dependence on the primary electron energy: 1.2+/-0.3 g cm-3 (5 keV) and 2.2+/-0.5 g cm-3 (20 keV). At a given primary energy a correlation with the irradiation dose is found. Quality factors determined from the phase relation at resonance of the fundamental pillar vibration mode were in the range of 150 to 600 and correlated to the deposited irradiation energy.