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Metallic impurity gettering to defects remaining in the Rp/2 region of MeV-ion-implanted and annealed silicon

Peeva, A.; Koegler, R.; Brauer, G.; Werner, P.; Skorupa, W.

Damage has been observed in MeV-ion-implanted Si away from the maximum of the nuclear energy deposition profile, mainly around the half of the projected ion range, Rp/2, after annealing at temperatures between 700°C ad 1000°C. This damage is primarily created by the implanted ions and consists of intrinsic defects remaining so small that they have not been observed by techniques sensitive to the lattice structure (RBS/C, TEM). The only way to detect this damage is to decorate it with metals and to measure the metal distribution. In this study the formation and disappearance of the Rp/2 damage has been investigated by Cu gettering in Si +-ion implanted Si versus temperature and time of the annealing cycle. The defects undergo a defect evolution during annealing which results in a decrease of the width of the damage layer with increasing temperature and prolonged time of the annealing. It is mostly believed that an excess of vacancies around Rp/2 getter metal impurities. Nevertheless, by means of positron annihilation spectroscopy no vacancy defects have been observed. In contrast in our XTEM investigation we found small (20-30nm) interstitial loops in the Rp/2 region. The creation of these loops is triggered by injected interstitials resulting from the ion milling procedure used during TEM specimen preparation. The ion bombardment of Si give rise to self-interstitials that diffuse extensively at room temperature and may modify the existing interstitial clusters to bigger agglomerates which can be observed by XTEM.

Keywords: ion implantation; gettering

  • Materials Science in Semiconductor Processing 3 (2000) 297-301

Publ.-Id: 3848