Elastic Double Structure of Amorphous Carbon Pillar Grown by Focused-Ion-Beam Chemical Vapor Deposition

Abstract

Amorphous carbon pillars grown by focused ion beam induced chemical vapor deposition (FIB-CVD) had been considered to form in a cylindrical double structure. In this structure, the core containing Ga originating from the primary ion is surrounded by an amorphous carbon shell grown by the secondary electrons that were emitted during the inelastic scattering process of the primary ions penetration. We measured the Young's modulus in a series of inclined pillars; the thickness of the pillars was reduced with the inclination. However, the Young's modulus of the inclined pillars of thinner diameter increased. Here, we found that such FIB-CVD pillars had an elastic double structure that is comprised of a very stiffened core with 300 GPa of Young's modulus, and an extremely soft shell having 30 GPa of Young's modulus. We also confirmed that the oxygen plasma thinning of the perpendicular pillars considerably increased the Young's modulus of the FIB-CVD pillars.