Gate electrode effects on low-frequency (1/f) noise in p-MOSFETs with high-κ dielectrics

The defects related to the gate-dielectric in high-κ-MOSFETs are studied using the 1/f noise technique. Three different types of gate electrodes were used for this purpose - poly-Si, metal (TiN/TaN) and fully Ni Silicided (FUSI) electrodes with Hf-based oxides as the gate dielectric layer. All the three types of devices show a specific behavior near the gate electrode-dielectric interface when the trap profiles are assessed using f × S_I spectra. The tunneling depths were calculated and it was found that the high-κ oxide (bulk) layers are being probed. From the drain current spectra S_I vs. drain current I_D of the various gate material devices at given depths, it may be inferred that the concentration of oxygen-vacancy-related defects can significantly influence the 1/f noise performance, which can explain the differences observed in noise between the gate electrodes. Comparison of FUSI gated devices, with various percentages of Hf in the dielectric layer, shows comparable noise levels (S_VG), indicating a minor dependence on Hf-content in the gate dielectric layer.