Formation of low-temperature Al/n-Si Schottky contacts using a partially ionized beam deposition technique

High quality Al/n-Si Schottky contacts have been fabricated using the partially ionized beam (PIB) deposition technique in a conventional vacuum condition without post heat treatment. The electrical characteristics of the diodes were extremely uniform across a 3 in. wafer and were stable with respect to a furnance annealing performed at 450 °C for 30 min. Scanning electron microscope examination revealed much shallower pit formation on the Si surface, as compared to that deposited by conventional means, following the heat treatment. A completely smooth Si surface was observed after a 10 s rapid thermal annealing at 450 °C. The observed behavior could be attributed to the creation of ‘‘contact openings’’ in the native oxide during deposition by ion bombardment, allowing Al to make an intimate contact to Si. This PIB deposition of metal-semiconductor contacts may be an important metallization scheme for the future low-temperature processing of shallow junctions for very high speed integrated circuits.