Abstract
Abstract Ti/Si and TiN/Ti/Si structures were annealed in vacuum to observe the reaction sequence. The stress of the film was determined in situ by measuring the curvature of the sample during the isochronal annealing process. The phases of the film after annealing process were identified using XRD, sheet resistance measurements, AES, and TEM. A clear correlation was found between the evolution of stress and the phase formation sequence. From the XRD data, we can find that the (002) peak of Ti shifts to low angle at 300~500℃ in the Ti/Si system. It is due to the oxygen-induced lattice expansion. The content of oxygen increases as the annealing temperatures increase, and this process let the sheet resistance increase and the stress become more compressive. For the TiN/Ti/Si systems, the TiN capped layer prevents the compressive stress developed at 300~500oC by retarding the oxygen incorporation into the Ti film. Samples with different TiN thickness were also compared after annealed to the same temperature. At low temperature, the diffusion of Si at the Ti-Si interface is easier in the system with thicker TiN capped layer. It might relate to the situation of oxygen incorporation into the Ti film or the stress state at the Ti/Si interface. However, the temperatures at which phases start to transform are affected slightly by the thickness of TiN capped layer.