This paper reports the nitridation effects on 1/f noise in n-MOSFETs with MOCVD HfO2 as gate dielectric. Nitridation of the gate oxides was carried out by using a post-deposition anneal (PDA) process in a N2 or NH3 ambient. Predominantly 1/f type noise is observed, with γ∼1. For non-nitrided interfaces, significant variation in noise was observed when different PDAs are employed. Among the studied PDAs, devices annealed with N2 show the lowest input referred noise, close to ITRS specifications when compared to O2 and NH3 anneals. Decoupled plasma nitridation (DPN) with 7-9% N2 content was employed for devices involving nitrided interfaces. Post-deposition anneals on such devices showed a suppressed effect as the input-referred noise was found to have similar values for the different conditions. The noise mechanism is also found to vary in devices with nitrided interface and no-PDA. A significant change in trap profile is noticed between nitrided and non-nitrided interfaces, which may be one of the causes for the differences observed. Lower trap densities are obtained from the trap profile for the non-nitrided no-anneal condition. Volume and interface trap densities, extracted from input-referred noise values, showed lowest values for a N2 PDA anneal, while an O2 anneal showed the highest values for non-nitrided devices. Devices with nitrided interfaces show similar value for all PDAs, with the values in-between the N2 and the O2 non-nitrided PDA. copyright The Electrochemical Society.