We develop a super-saturation technique to extend the previously established doping density limit for ultra-high vacuum monolayer doping of silicon with phosphorus. Through an optimized sequence of PH3 dosing and annealing of the silicon surface, we demonstrate a 2D free carrier density of ns = (3.6 ± 0.1) × 1014 cm−2, ∼50% higher than previously reported values. We perform extensive characterization of the dopant layer resistivity, including room temperature depth-dependent in situ four point probe measurements. The dopant layers remain conductive at less than 1 nm from the sample surface and importantly, surpass the semiconductor industry target for ultra-shallow junction scaling of at a depth of 7 nm.
Low resistivity, super-saturation phosphorus-in-silicon monolayer doping
S. R. McKibbin, C. M. Polley, G. Scappucci, J. G. Keizer, M. Y. Simmons; Low resistivity, super-saturation phosphorus-in-silicon monolayer doping. Appl. Phys. Lett. 24 March 2014; 104 (12): 123502. https://doi.org/10.1063/1.4869111
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