  In this work, a single crystal CVD diamond film with a novel
three-dimensional (3D) interdigitated electrode geometry has been fabricated
with the Reactive Ion Etching (RIE) technique in order to increase the charge
collection efficiency (CCE) with respect to that obtained by standard
superficial electrodes. The geometrical arrangement of the electric field lines
due to the 3D patterning of the electrodes results in a shorter travel path for
the excess charge carriers, thus contributing to a more efficient charge
collection mech-anism. The CCE of the device was mapped by means of the Ion
Beam Induced Charge (IBIC) technique. A 1 MeV proton micro-beam was raster
scanned over the active area of the diamond detector under different bias
voltage conditions, enabling to probe the charge transport properties of the
detector up to a depth of 8 {\mu}m below the sample surface. The experimental
results, supported by the numerical simulations, show a significant improvement
in the 3D-detector performance (i.e. CCE, energy resolution, extension of the
active area) if compared with the results obtained by standard surface metallic
electrodes.
