Monolayer doping and other strategies in high surface-to-volume ratio silicon devices

To maintain electron device scaling, in recent years the semiconductor industry has been forced to move from planar to non-planar thin-body electron device architectures. This alone has created the need to develop a radically new, non-destructive, conformal method for doping. Doping alters the electrical properties of a semiconductor, related to the access resistance. Monolayer doping (MLD) is a promising surface-based technique, whereby organic molecules are covalently bound to the semiconductor surface at relatively low processing temperatures (room temperature - 160 °C). A thermal treatment is then applied which both frees the dopant atoms from the organic molecules, and provides the energy for diffusion into the semiconductor substrate and subsequent activation. Very promising results have been achieved, but mostly on planar unpatterned substrates. There is now a need to assess the suitability of MLD for thin-body semiconductor features with high surface-to-volume ratios and densely packed structures. It is the aim of this review paper to consider MLD from this perspective.