Electrical properties of low-temperature epitaxial doped Si thin films fabricated by using a sputtering-type electron cyclotron resonance plasma

The electrical properties of Sb-doped n(+) epitaxial Si films have been inv estigated. These films were fabricated at low temperatures of below 515 deg reesC and at a conventional base pressure of 5 x 10(-7) Ton: using a sputte ring-type electron cyclotron resonance plasma. It was found that the Sb dop ants in the target were almost wholly incorporated into lattice sites of ep ilayers and the Hall mobility of the epilayers grown at 515 degreesC was co mparable to that of the bulk Si. A reverse current density as low as 1 x 10 (-8) A cm(-2) was obtained by a direct deposition of an nf epilayer on a p- type substrate, which suggests the formation of a high-quality interface be tween the epilayer and the substrate. The precise control of the deposition gas pressure, substrate potential and substrate temperature was found to b e very important for the fabrication of high-quality epilayers. Heavily B-d oped p(+) epilayers were also fabricated at a substrate temperature of 515 degreesC. The B dopant was wholly incorporated into the epitaxial layers, b ut annealing at temperatures of more than 700 degreesC was required to elec trically activate the B dopant. The electrical activation mechanism has bee n discussed and it has been inferred that the B dopant occupied interstitia l sites in the as-grown epilayers.