Transmission electron microscopy study of SiF/BF2 implanted and annealed (100)Si: Amorphization and residual effects

Abstract

Formation of amorphous layers and residual defects in SiF+/BF2+ implanted and annealed (100)Si was investigated on an atomic level by using a high-resolution transmission electron microscope. Amorphous layers, of which depths were about 70% of those of amorphous layers formed by Si+ preamorphization at the same implantation energies, could be formed by SiF+ preamorphization. Two distinct layers of defects were formed in SiF+/BF2+ implanted wafers annealed at 600 °C for 1 h and then rapidly thermally annealed at 950 °C for 30 s. One layer, observed near the surface regions, consisted of intrinsic stacking faults bounded by 30° Shockley partial dislocations, twins, amorphous regions, and fine clusters. The other layer, observed near the original amorphous/crystalline interface, consisted of Frank partial dislocations of which Burgers vector is 1/3a〈111〉 and 60° perfect dislocations of which Burgers vector is 1/2a〈110〉. These defects were formed by retarding growth rate by fluorine atoms; outdiffusion of fluorine atoms; lattice misorientation between the substrate and crystalline pockets; and the introduction of an extra half- plane during the preamorphization process.