An examination of the effect of dose rate on ion implanted impurity profiles in silicon

The effect of dose rate on ion implanted impurity profiles in single-crystal silicon has been carefully and systematically examined. It is found that for both boron (light mass) and arsenic (heavy mass), the dose rate has a small but clearly observable effect on channeling tails with higher beam currents producing shallower profiles in the channeling tail. The effect is greater for on-axis (0 degree tilt/0 degree rotation) implantation than for off-axis (8 to 9 degree tilt/30 degree rotation) implantation, for which there is a clear indication of a dose rate effect for boron, but the effect is negligible for arsenic. Lower mass (boron) implants have a more significant dose rate effect than do higher mass (arsenic) implants. The possible mechanisms that result in this interesting dose rate effect are discussed