Electrical activation of arsenic implanted in silicon on insulator (SOI)

Electrical activation of arsenic implanted in silicon on insulator (SOI) was studied. Two SOI structures with different Si overlayers and buried oxide thicknesses were used in this work. The As+ implantations were performed with a single energy of 20 keV to doses of 5 × 1014 cm−2 or 2 × 1015 cm−2 in both substrates. A plateau-like profile was achieved in an additional set of SOI samples by triple energy implantation. Rapid thermal and conventional furnace annealing were applied for dopant activation. Rutherford backscattering and Hall effect electrical measurements were done as well. The results are discussed, concerning electrical activation of As, considering the amorphization depth reached by dopant implantation and the crystal recovery process via thermal treatment. The completely amorphized samples presented higher values of sheet resistance and lower electrical activation percentage compared with the samples that did not have the complete top Si film amorphized. These results clearly show the need for avoiding total amorphization of the Si film during ion implantation in SOI, so that it is possible to achieve good crystal and electrical characteristics after thermal processing.