Influences of Point and Extended Defects on As Diffusion in Si

Abstract

The influences of point and extended defects introduced by ion implantation on the transient enhanced diffusion (TED) of As have been examined. The implantation of a subamorphizing dose of Si into Si wafers with nearly uniform As background doping results in the slight segregation of As into {311} defects after annealing at 670°C, whereas an amorphizing dose of Si is found to induce significant segregation of As into end-of-range (EOR) dislocation loops after annealing at 820°C, regardless of the background As concentration. In the second experiment, As ions were implanted into Si wafers at 30 keV to low and medium doses. Some of the wafers were preannealed in order to recrystallize the amorphous layer and subsequently implanted with subamorphizing doses of Si at 50 keV. The resulting profiles reveal that the TED of As increases with Si implantation dose, indicating that transient As diffusion occurs via Si self-interstitials in the same way as for B and P. A suppression of the TED of As in the early stages of annealing at higher As and Si implantation doses is also observed. This is considered to originate from the formation of immobile arsenic-vacancy clusters.