Effects of Negative-Bias-Temperature-Instability on Low-Frequency Noise in SiGe ${p}$ MOSFETs

We have measured the low-frequency 1/ ${f}$ noise of Si 0.55 Ge 0.45 ${p}$ MOSFETs with a Si capping layer and SiO 2 /HfO 2 /TiN gate stack as a function of frequency, gate voltage, and temperature (100–440 K). The magnitude of the excess drain voltage noise power spectral density ( $\textit{S}_{ {vd}}$ ) is unaffected by negative-bias-temperature stress (NBTS) for temperatures below ~250 K, but increases significantly at higher temperatures. The noise is described well by the Dutta-Horn model before and after NBTS. The noise at higher measuring temperatures is attributed primarily to oxygen-vacancy and hydrogen-related defects in the SiO 2 and HfO 2 layers. At lower measuring temperatures, the noise also appears to be affected strongly by hydrogen-dopant interactions in the SiGe layer of the device.