Impurity and clustering effects on defect evolution in ion-implanted Si

A detailed investigation of the damage formation and evolution in ion-implanted crystalline Si is presented. Deep-level transient spectroscopy has been used to monitor room temperature migration of point defects (interstitials and vacancies), formation of room temperature stable defect complexes and evolution from simple point-like defect complexes to defect clusters and even extended defects. Si samples were implanted with Si or He ions with energies of 145 keV-3 MeV, to fluences in the range 5 x 10(8)-5 x 10(13) cm(-2). The effects of thermal annealing, in the range 100-680 degrees C and 10 min-15 h, were also explored. A systematic comparison of defect complexes formation and evolution in ion-implanted or electron-it radiated Si samples with a different impurity content were used to assess the role of impurities (C and O), extra implanted ion and defect clustering on the nature and ther mal stability of residual damage. In particular, an interstitial excess directly resulting from the extra implanted ion is shown to dominate the residual damage. These interstitials can aggregate into interstitial clusters above a critical fluence and annealing temperature. Fm ther increase in the ion fluence produces the formation of extended defects such as {311} stacking faults that compete with defect clusters in storing the interstitial excess. The implication of these results on our current understanding of damage evolution in ion-implanted Si and defect-related processes such as transient enhanced diffusion is discussed.