1 The effects of energy non-monochromaticity of B11 ion beams on B11 diffusion

We have shown that energy contamination introduced by ion beam deceleration technology that is used to increase the beam currents available for low energy boron implants, can affect fabricated junctions adversely. A 4 keV B11 beam is extracted and retarded by a potential of-3.5 keV for 0.5 keV B11 implantation, or by a potential of-3.8 keV for 0.2 keV B11 implantation. Intentional energy contamination was introduced by turning off the retarding potential to allow the 4 keV B11 ions to irradiate Si wafers directly. The energy contamination levels of 0.1, 0.2, and 0.3 % were introduced. Rapid thermal annealing of all the implanted samples was performed under N2 ambient at 1050ºC for 1s. The dopant tail profiles themselves are not significant if the contamination levels are low. However, the much higher damage level coming from high energy contamination increases the transient enhanced diffusion of B11 more than proportionately, resulting in considerable boron diffusion. Energy contamination at a level of 0.1 % can extend the profile of 0.5 keV B11 implants 10 nm deeper after a 1050°C spike annealing. The study shows a highly monoenergetic beam with energy contamination less than 0.1 % is required for sub-micron devices