Cluster-ion implantation: An approach to fabricate ultrashallow junctions in silicon

Abstract

Cluster-ion implantation in combination with two-step annealing is effective in making ultrashallow junctions. We have demonstrated the use of heavy atom–boron cluster ions to effectively reduce the boron energy for shallow-junction formation. SiB, SiB2, and GeB cluster ions have been used to produce 2 keV boron for low-energy ion implantation. We have generated the SiB, SiB2, and GeB cluster ions using the source of negative ions by cesium sputtering ion source. Shallow junctions have been made by SiB, SiB2, and GeB cluster ions implanted into Si substrates at 1×1015/cm2 with energies at 6.88, 8.82, and 15 keV, respectively. We also discussed the benefit of a 550 °C preannealing before a 1000 °C, 10 s rapid thermal annealing.