Reverse annealing effects in heavy ion implanted silicon

Silicon samples of both n- and p-type have been implanted with low doses of In and I ions using energies between 15 and 30 MeV. The resulting electrically active defects were characterized by deep level transient spectroscopy (DLTS), The well-known vacancy-oxygen (VO) center is observed to show a reverse annealing. For annealing temperatures between 150 degrees C and 250 degrees C the concentration of VO is increased by about 40%, while the concentration of deep levels about 0.43 eV below the conduction band edge (divacancy defect, phosphorus-vacancy pair (PV) and others) is reduced by more than 40%. The growth of VO can to a large extent be explained by a release of vacancies during annealing from defect-rich zones generated by the heavy ions, although a part of the increase is also caused by vacancies originating from dissociation of PV centers. It has previously been shown that the interstitial carbon-interstitial oxygen (C1O1) complex is formed at room temperature by pairing of slowly diffusing interstitial carbon, released by the self-interstitials from the collision cascades. and oxygen. An increase by more than 15% of the initial concentration of the C1O1 center is observed upon annealing between 75 degrees C and 200 degrees C in n-type material. The effect can be explained by a release of interstitials from the defect-rich zones during annealing at moderate temperatures. The increase is not observed in p-type material, which might be explained by a more effective trapping of the interstitials. released during annealing, by substitutional boron rather than substitutional carbon. (C) 1999 Elsevier Science B.V. All rights reserved.