An examination of athermal photonic effects on boron diffusion and activation during microwave rapid thermal processing.

This work examines the role of 672 nm optical illumination on the diffusion and activation of B in Si as a function of various factors. The factors studied include length of anneal, maximum temperature of anneal, type of co-implanted and pre-amorphizing species and ambient oxygen concentration. The anneal conditions fell into one of three categories: (1) high-temperature (> 900 degrees C) spike and 10-second anneals; (2) low temperature (550 degrees C) 30-minute anneals; and (3) room-temperature long-term "anneals". Implanted species included BF2 implants, pre-amorphized B-only implants, and pre-amorphized BF2 implants. Finally, the ambient oxygen concentration was varied from atmospheric pressure to 100 ppm. The results show that illumination: (1) affects the diffusion of B on spike anneal time frames; (2) has limited effect on diffusion over 10-second time frames; and (3) fails to enhance the activation of B during low-temperature solid phase epitaxy and at room temperature. Additionally, illumination has no effect on B-diffusion when oxygen is present in ambient concentrations but does show an effect when the presence of oxygen is restricted. Finally, the presence of F affects both the net diffusion of B in Si and the relative effect of illumination on the diffusion of B.