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.