Random Telegraph Noise as A New Measure of Plasma-Induced Charging Damage in MOSFETs

Random telegraph noise (RTN) has been recently of great importance in designing ultimately scaled MOSFETs. We address in this paper how RTN characteristics are altered by plasma process-induced charging damage (PCD). MOSFETs with SiO2 and high-k gate dielectric were prepared and exposed to an inductively coupled plasma (ICP) with Ar gas. From the time evolution of I-ds fluctuation defined as I-ds/mu(Ids) where mu(Ids) is the mean I-ds, we comprehensively investigated the details of RTN features such as the statistical distribution of I-ds/mu(Ids), power spectral density, and the time constants for carrier capture and emission. It was found that the statistical distribution width of I-ds/mu(Ids), delta(I-ds/mu(Ids)), increased by PCD for both MOSFETs with the SiO2 and high-k gate dielectrics, suggesting that RTN characteristics can be used as a potential measure of PCD. These features were consistent with Delta V-th results. However, the slope in power spectral density and the time constants exhibited complicated behaviors owing to the nature of created traps by PCD. It is confirmed that PCD alters RTN characteristics, and that, in evaluating the amount of PCD, delta(I-ds/mu(Ids)) should be used as a straightforward measure.