Negative Bias Temperature Instability (NBTI) is a key reliability issue that is of immediate concern in p-channel MOS devices stressed with negative gate voltages. NBTI manifests as an increase in the threshold voltage and consequent decrease in drain current and Tran conductance. The degradation exhibits power law dependence with time.
In the sub-micrometer devices nitrogen is incorporated into the gate oxide to address the issues like higher leakage current and boron penetration. However, incorporating nitrogen enhances NBTI. It seems possible that nitrogen-based gate stacks would be used even for the 65 nm nodes. This is because the development of High-K gate stacks, which are widely believed to be the eventual alternatives, is taking longer than expected.
It is widely believed that NBTI degradation is due to generation of interface traps, which are unsaturated silicon dangling bonds. One of the most successful models that have been able to explain NBTI phenomenon is the reaction diffusion model. This model proposes that the generation of interface traps is because of a hole induced electro-chemical reaction at the Si-SiO2 interface. In the initial times the degradation is reaction rate controlled, however, with time the phenomenon becomes diffusion limited.
Recovery
The NBTI degradation recovers as soon as the stress is removed. The measurement technique used to measure NBTI has an impact on the amount of recovery seen. In order to overcome the recovery during the electrical characterization, the on-the-fly technique has been suggested. Anyway, the impact of measurement in the study of NBTI degradation is a matter of debate in the research community.
In the sub-micrometer devices nitrogen is incorporated into the gate oxide to address the issues like higher leakage current and boron penetration. However, incorporating nitrogen enhances NBTI. It seems possible that nitrogen-based gate stacks would be used even for the 65 nm nodes. This is because the development of High-K gate stacks, which are widely believed to be the eventual alternatives, is taking longer than expected.
It is widely believed that NBTI degradation is due to generation of interface traps, which are unsaturated silicon dangling bonds. One of the most successful models that have been able to explain NBTI phenomenon is the reaction diffusion model. This model proposes that the generation of interface traps is because of a hole induced electro-chemical reaction at the Si-SiO2 interface. In the initial times the degradation is reaction rate controlled, however, with time the phenomenon becomes diffusion limited.
Recovery
The NBTI degradation recovers as soon as the stress is removed. The measurement technique used to measure NBTI has an impact on the amount of recovery seen. In order to overcome the recovery during the electrical characterization, the on-the-fly technique has been suggested. Anyway, the impact of measurement in the study of NBTI degradation is a matter of debate in the research community.
1 comment:
hi sir
i am doing a lot of work on nbti
the current topic for discussion is how to control leakage as well as nbti,one method is generation of minimal leakage vectors by keeping nbti constant
2nd by internal node control techniche others.........
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