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

In this paper, we have measured the low-frequency 1/f noise of Si_0.55Ge_0.45 pMOSFETs with a Si capping layer and SiO₂/HfO₂/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 (Svd) 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 SiO₂ and HfO₂ layers. Finally, at lower measuring temperatures, the noise also appears to be affected strongly by hydrogen-dopant interactions in the SiGe layer of the device.