Enhanced boron activation in strained-Si/Si_1-xGe_x substrate using laser annealing

Strained-Si/SiGe substrate comprises a thermally less conductive SiGe layer, which deprives a good thermal dissipation pathway. This gives rise to a highly non-equilibrium laser process and can vary significantly to that in normal bulk silicon substrate. Our results show that the boron distribution in strained-Si/SiGe substrate is always deeper and more abrupt than that in bulk silicon substrate, signifying a substantial thermal confinement that leads to a greater melt extent and melting duration. It is found that a decrease of over 94% thermal transfer rate occurs in the strained-Si/SiGe substrate. Non-melt laser annealing, on the other hand, produces dopant profiles of negligible diffusion and improves activation in the strained-Si/SiGe substrates. No degradation in the strain in the strained-Si layer was induced after non-melt laser annealing. The study demonstrates that non-melt laser annealing in thermally less conductive semiconductor substrates is capable of enhancing dopant activation at low laser fluence. copyright The Electrochemical Society.