Boron Doping Profiles and Annealing Behavior of Amorphous Implanted Silicon Layers

Abstract

Different possibilities for amorphization of silicon in connection with boron implantation have been compared. The methods described are silicon and neon predamage implants, implantation of BF₂ molecules, and implantation of boron at 77K. All implantations show a typical amorphous annealing behavior with a steep increase in activation around 500-650°C without reverse annealing. Depending on annealing temperature and time, doping and mobility profiles were measured. For annealing temperatures below 900°C damage dependent electrical activation occurs with complete activation above 650°C in the recrystallized amorphous layer. All four methods are useful for doping, but mobility after annealing only for cold boron and neon predamage implants approach values corresponding to bulk data. Only in the case of neon predamage implantations the whole doping profile can be placed into the amorphous layer in order to achieve low annealing temperatures.

Work sponsored by “Deutsche Forschungsgemeinschaft”.