Bending and vibration tests performed inside a scanning electron microscope were used to mechanically characterize high aspect pillars grown by focused electron-beam- (FEB) induced deposition from the precursor Cu(C(5)HF(6)O(2))(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 and 20 keV primary electron energy and 100 pA beam current, depending on primary electron energy. The Young's moduli of the FEB deposits increased from 17 +/- 6 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 150-600 and correlated to the deposited irradiation energy.