Heavily Phosphorus Doped Silicon Junctions for nMOS Applications

Epitaxially grown Silicon Carbon (Si:C) in recessed junction regions has been shown to induce tensile stress in the nMOS channel and thereby enhance the transistor performance. In addition to the stress induced in the channel, this technology also needs to achieve low resistivity junctions for widespread use. This work discusses epitaxially grown heavily doped Si/ Si:C layers which can be used in nMOS junctions and can address both these requirements. Si:C epitaxial layers are shown to have phosphorus concentrations as high as 1.25 X 10^21 cm^-3 with resistivities as low as 0.3 mOhm.cm. Applications of these layers can range from Si:P cap layers for low series resistance to Si:PC layers for inducing stress in the nMOS channel.