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

Abstract

Properties of SiGe:P deposited with high order Si and Ge precursors at low temperature of 400oC, suitable for 5 nm and below technological nodes have been studied. An optimal PH3 flow leading to a maximal active P concentration was demonstrated for each studied Ge concentration (40-75%). The highest active P concentration of ~1 1020 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 PH3 flows lead to a significant reduction of active P concentration despite very high total P concentrations (up to ~1 1021 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 PH3 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.