Atomic structure of ion implantation damage and process of amorphization in semiconductors

Abstract

Atomic structure of ion implantation damage and the process of amorphization in silicon have been investigated using high-resolution electron microscopy techniques. The specific damage energy density for crystalline to amorphous transition has been determined to be 6.0×1023 eV/cm3 or 12 eV/atom at 4 K with no annealing. The amorphous regions are produced when the damage energy deposited by the ions exceeds this critical value. Since the damage energy deposited by the ions is a strong function of ion implantation and substrate variables, the formation of amorphous regions and the process of amorphization are strong functions of these variables. The details of atomic structures of amorphous silicon containing microcrystallites and that of amorphous-crystalline interfaces are presented. The calculations of the mean-free path between collisions and the energy deposited per atom are found to be consistent with experimental observations on amorphization of silicon. Some results on the projected ranges of low-energy recoils, which are primarily responsible for the production of amorphous cascades, are presented. The solid-phase crystallization phenomena and the role of microcrystallites during the crystallization process are discussed.