REALIGNMENT OF AS DOPED SILICON FILMS DEPOSITED ON (100) SILICON SUBSTRATES

The epitaxial realignment induced by high temperature rapid thermal annealing of ion implanted polycrystalline and amorphous layers deposited on to <100> oriented Si substrates has been studied. The As doses ranged form 2 x 10(15) to 2 x 10(16) cm-2 and the annealing temperature from 1000 to 1150-degrees-C for annealing times ranging from 5 to 100 s. The characterization of the processed layers has been performed by means of Rutherford backscattering and channelling spectroscopy, sheet resistance measurements and transmission electron microscopy. This study shows that in the temperature and time ranges used here, an As concentration larger than 1 x 10(20) cm-3 is necessary to induce the epitaxial realignment of the polycrystalline layer. However, for the amorphous layers a higher As concentration is needed. The difference is related to the way in which the As atoms redistribute in the two layers. It is found that the heavily doped amorphous layers can be realigned with limited As redistribution, thus giving them the potential of being used in the microelectronics technology for the formation of shallow junctions.