DOPANT ACTIVATION, CARRIER MOBILITY, AND TEM STUDIES IN POLYCRYSTALLINE SILICON FILMS

Polycrystalline silicon films, deposited by low-pressure chemical vapor deposition at 570° and 620°C, and doped withphosphorus by ion implantation, have been studied in terms of: dopant activation, carrier Hall mobility, and microstructure,as a function of the annealing temperature. Higher activation and carrier mobility were obtained on samples depositedat lower temperature, which were amorphous [by x-ray diffraction and transmission electron microscopy (TEM)] afterthe deposition step, in contrast with those deposited at higher temperature, which were polycrystalline. Transmissionelectron microscopy observations on a cross section showed a better recrystallization of the amorphous films during ahigh-temperature step, and mean grain size values which agree qualitatively with those calculated from grain boundarymobilities.