Elevated n+/p junctions by implant into CoSi2 formed on selective epitaxy for deep submicron MOSFETs

Very shallow elevated n⁺/p junctions formed by arsenic implant into or through cobalt silicide (CoSi₂) formed on selective epitaxial layers and their application to deep submicron n-channel MOSFETs were studied for the first time. PREDICT 1.6 simulation program was employed to choose the desired implant energies and annealing thermal cycle based on theoretically predicted silicide thickness. The implanted CoSi₂ elevated junctions had low reverse current and no bias voltage dependence up to 5 V. Diffusion current dominated the junction forward current, and good ideality factors close to 1 were obtained. A nearly abrupt junction doping profile was achieved. Deep submicron n-channel MOSFETs incorporating implanted CoSi₂ elevated junctions were demonstrated. Sharp turn-off and reasonably large drain currents were achieved