Comprehensive study on low-frequency noise and mobility in Si and SiGe pMOSFETs with high-κ gate dielectrics and TiN gate

Low-frequency noise and hole mobility are studied in Si and SiGe surface channel pMOSFETs with various types of high-κ dielectric stacks (Al₂O₃, Al₂O₃/HfAlO_x/Al₂O₃ and Al₂O₃/HfO₂/Al₂O₃) and TiN as gate electrode material. Comparisons are made with poly-SiGe-gated pMOSFETs as well as poly-Si/SiO₂/Si references. The choice of channel material (strained SiGe or Si), gate material (TiN or poly-SiGe), and high-κ material (Al₂O₃, HfO₂, HfAlO_x) is discussed in terms of mobility and low-frequency noise. A TiN gate in combination with a surface SiGe channel is advantageous both for enhanced mobility and low 1/f noise. The dominant sources of carrier scattering are identified by analyzing the mobility measured at elevated temperatures. The 1/f noise is studied from subthreshold to strong inversion conditions and at different substrate biases. The mobility fluctuation noise model and the number fluctuation noise model are both used to investigate the 1/f-noise origin.