Isolated Carbon Confinement Methodology for Ultrathin Boron Profiles with Enhanced Conductivity in Sub-50 nm Strained Layers of Silicon Germanium

摘要

This work reports on observations of enhanced carbon confinement of boron in strained silicon germanium. By locating carbon outside of the boron doped region during the pseudomorphic growth, less carbon is required to mitigate boron diffusion during subsequent thermal anneals, the film resistivity is reduced, and the film is more strained than the conventional method of placing carbon throughout. SIMS (secondary ion mass spectrometry) is utilized to verify O, C, B, and Ge concentrations in SiGeC layers following low temp growth by LPCVD (low pressure chemical vapor deposition) and a subsequent thermal annealing. Four-point probe is utilized for 49-point sheet resistance measurements and X-ray diffraction is used to confirm the effect of carbon placement on the SiGe lattice parameter.