  We report on mask-less, high resolution etching of diamond surfaces,
featuring sizes down to 10 nm. We use a scanning electron microscope (SEM)
together with water vapor, which was injected by a needle directly onto the
sample surface. Using this versatile and low-damage technique, trenches with
different depths were etched. Cross sections of each trench were obtained by
focused ion beam milling and used to calculate the achieved aspect ratios. The
developed technique opens up the possibility of mask- and resist-less
patterning of diamond for nano-optical and electronic applications.
