Investigation of Low Temperature Epitaxial SiGe:P in View of Source/Drain Application for 5nm Technology Node and Below

Properties of SiGe:P deposited with high order Si and Ge precursors at low temperature of 400 o C, suitable for 5 nm and below technological nodes have been studied. An optimal PH 3 flow leading to a maximal active P concentration was demonstrated for each studied Ge concentration (40-75%). The highest active P concentration of ~1 10 20 cm -3 was obtained for SiGe:P layers with Ge content of 40% and below. Increase of Ge concentration above 40% caused gradual reduction of the maximal active P concentration down to the values reported for Ge:P deposited with digermane at temperatures close to investigated here. Higher than optimum PH 3 flows lead to a significant reduction of active P concentration despite very high total P concentrations (up to ~1 10 21 cm -3 ). Thermal annealing does not change properties of SiGe:P layers with low or optimal P concentrations. P activation of the layers deposited with the higher than optimum PH 3 flows improves upon annealing, nevertheless it is never better than the maximum value obtained with the optimal flows. Such samples also showed a strong P accumulation at SiGe:P layer interfaces in the case of laser annealing and additional P and Ge diffusion after spike anneal. Finally, an optimized selective SiGe:P process was developed and demonstrated for the case of Ge fin FET devices.