Highly electrical resistive SiTiNxheating layers and diffusion barriers for PCRAM

Highly electrical resistive amorphous SiTiN x films were explored as both heating layers and diffusion barriers for the cells of phase-change random-access memory (PCRAM). The measured electrical resistivity of SiTiN x films, determined by the nitrogen content x tunable up to 38.68%, is between 0.039–0.69 Ω cm which fulfils the requirements of a suitable heating layer suggested by simulations. SiTiN x films with a medium range of nitrogen content showed excellent thermal stability, very smooth surface and amorphous structure sustaining until at least 800 °C, thus suitable for application in PCRAM. However, SiTiN x films exhibit a high degree of temperature dependent resistivity, and show a different temperature coefficient of resistance with different N contents at the temperature range 400–500 °C. The chemical binding characteristics of SiTiN x films with such higher electrical resistivity were also investigated. The binding energy of Ti 2p spectra in SiTiN x films changes with nitrogen content and shifts to higher energies confirming their susceptibility to oxidation. Besides, interface analysis showed that these films perform excellently as a diffusion barrier between a W bottom electrode and the Ge 2 Sb 2 Te 5 phase-change layer after evaluation annealing at 600 °C for 30 min.