Shape evolution of oxidized silicon V-grooves during high dose ion implantation

The evolution of the shape of oxidized V-grooves on (001) Si under high-dose
Ge+ ion irradiation has been studied experimentally as well as
theoretically. The shape of the V-grooves changes due to sputtering,
re-deposition and swelling. An integro-differential equation has been
derived which takes into account these 3 effects. The equation where solved
numerically for the experimental conditions. Experimentally, V-grooves where
formed by anisotropic etching and dry oxidation. XTEM images of as-oxidized
and as-implanted V-grooves where compared. The theoretically predicted SiO2
layer thickness reduction as well as the predicted surface shape change
agree nicely with XTEM images. It is shown that sputtered material
accumulates at the bottom of the V-grooves. At the same time implanted
species accumulate in the bottom region of V-grooves, which can result in
the formation of a very thin wire during subsequent annealing.