Effect of Annealing Process on Trap Properties in High-k/Metal Gate n-Channel Metal--Oxide--Semiconductor Field-Effect Transistors through Low-Frequency Noise and Random Telegraph Noise Characterization

In this research, trap properties in n-channel metal-oxide-semiconductor field-effect transistors (MOSFETs) with different annealing sequences have been studied on the basis of low-frequency (1/f) noise and random telegraph noise (RTN) analyses. The 1/f noise results indicate that the source of the drain current fluctuation is electron trapping. The higher trap density in the devices annealed before the TaN layer causes serious noise and lower trap energy in RTN results. The substitution mechanism explains that the increment of defects is due to the additional nitrogen atoms in HfO2. On the contrary, fewer defects in the devices annealed after the TaN layer are due to the effect of passivation in the TiN layer. The defect in HfO2 is the source of trapping/detrapping; thus, fewer defects cause the decrement of the fluctuation and the increment of the drain current. We believe that this process has a potential to remove defects in advanced MOSFETs. (C) 2013 The Japan Society of Applied Physics