Deep-level transient spectroscopic methods were used to characterize the properties of interstitial clusters in ion-implanted material. Both n-type and p-type samples were implanted with 145keV to 1.2MeV Si ions to doses of between 1010 and 5 x 1013/cm2, and then annealed at 450 to 750C. In samples which were annealed above 550C, the residual damage was dominated by 2 hole traps in p-type samples and by 5 electron traps in n-type samples. Analysis of the spectra and defect depth profiles revealed that these signatures were related to Si self-interstitial clusters. Experiments confirmed that these clusters did not comprise large numbers of impurities such as C, O, B or P. Four deep-level signatures exhibited a similar annealing behavior; thus suggesting that they arose from the same defect structure. On the other hand, the remaining signatures exhibited different annealing behaviors and were tentatively attributed to different cluster configurations. It was found that the thermal stability of the clusters was enhanced by increasing the Si dose or by reducing the impurity content of the substrate. It was proposed that bigger and more stable clusters were formed when the concentration of free interstitials that was available for clustering was increased, and competing interstitial trapping at impurities was inhibited. In samples which were implanted to doses of more than 1013/cm2, most of the deep-level transient spectroscopy signals exhibited a complex and non-monotonic annealing behavior; this suggesting that the clusters could transform between electronic configurations.

Electrical signatures and thermal stability of interstitial clusters in ion implanted Si J.L.Benton, K.Halliburton, S.Libertino, D.J.Eaglesham, S.Coffa: Journal of Applied Physics, 1998, 84[9], 4749-56