Depassivation of Si-SiO₂interface following rapid thermal annealing

The thermal stability of the Si-SiO₂ interface of thermally oxidised silicon wafers is investigated using the Quasi-steady state photoconductivity decay (QSS-PCD) method. Planar silicon (100) and (111), as well as textured (100) wafers with various surface orientations were subjected to Rapid Thermal Annealing. Wafers textured with inverted pyramids displayed the most rapid depassivation rate, while (100) planar wafers showed the slowest depassivation rate. The depassivation rate of wafers which had been textured with inverted pyramids and subsequently rounded by acid etching was between that of (100) planar and wafers textured with inverted pyramids. The results suggest that the Si-SiO2 interface on planar (100) surfaces is particularly thermally stable, and that the stability gradually decreases as one moves from from a (100) to a (111) surface orientation. The results also suggest that textured surfaces have a lower thermal stability, and a higher recombination rate, that planar surfaces of the same area and surface orientation.