Continuous growth of heavily doped p+-n+ Si epitaxial layer using low-temperature photoepitaxy

Abstract
Heavily doped p+ and n+ silicon epitaxial layers were continuously grown at 600 °C using photoenhanced epitaxy. The heavily phosphorus‐doped photoepitaxial layer with a carrier concentration above 1×1017 cm3 grown on the p substrate shows very high density surface pits due to phosphorus precipitation, suggesting poor crystal quality. Unexpectedly, when this n+ photoepitaxial layer is continuously grown on a heavily boron‐doped p+ photoepitaxial layer at a boron concentration above 1×1019 cm3, surface pits completely disappear and crystal quality is greatly improved. The very low growth temperature enabled an extremely abrupt impurity profile to be achieved for the p+n+ layer.