Residual defects following rapid thermal annealing of shallow boron and boron fluoride implants into preamorphized silicon

Abstract

Shallow BF2 and B implants (42 keV, 2×1015 cm−2) were conducted at either liquid nitrogen or room temperature into deeply preamorphized (100) Si. Cross-sectional transmission electron microscopy revealed that subsequent rapid thermal annealing (RTA) of the room-temperature implanted BF2 sample in the temperature range 950–1150 °C for 10 s created three classes of secondary defects at three different depth levels. The depths corresponded closely to the projected range of the BF2 implant, the deep amorphous/crystalline interface, and the region immediately below the interface. In contrast, RTA of preamorphized Si with or without the shallow B implant both resulted in a high perfection surface region with secondary defects only in the region below the deep amorphous/crystalline interface. A phenomenological model for nucleation of the separate layers of defects is presented.