Mechanical strain and damage in Si implanted with O and N ions at elevatedtemperatures: Evidence of ion beam induced annealing

The accumulation of damage and the development of mechanical strain in crys talline Si (c-Si) by O and N ion implantation to doses up to 4 x 10(17) cm( -2) at elevated temperatures have been studied using Rutherford backscatter ing spectrometry and high resolution x-ray diffraction. The implantation of O or N ions at high temperatures produces two distinct layers in the impla nted c-Si: (i) a practically damage-free layer extending from the surface u p to similar or equal to half of the depth of the mean projected range (R-p ) and presenting negative strain (of contraction); and (ii) a heavily damag ed layer located around and ahead of the R-p with no significant strain. Bo th the damage distribution and the magnitude of the strain were found to be dependent on the ion species implanted. We proposed that besides the spati al separation of Frenkel pair defects due to the mechanics of the collision processes and the intensive dynamic annealing, an ion beam induced anneali ng process also participate in the formation of the near-surface damage-fre e layer during high temperature implantation of c-Si. (C) 2001 American Ins titute of Physics.