Interaction of work function tuning and negative bias temperature instability for future nodes

Next generation finfet technology nodes will increasingly rely on the effective workfunction tuning to achieve the desired transistor VT as finfet doping is increasingly ineffective as a mean to tune VT. This work deals with metal gate workfunction engineering impact on bias temperature instability toward VT control in future nodes and its correlation with gate stack parameters. This work is divided in two parts. In the first part, the EWF extraction technique and its link to actual VT is investigated using a unique combination of CV/IV techniques. Using controlled experiments, a 400meV EWF modulation modulates NBTI significantly. The impact of bulk defects due to this modulation is also discussed. Display Omitted An original technique to extract PFET band alignment using valence band electron tunneling is demonstrated for next FinFET technology nodeThe first part of the paper deals with the EWF extraction technique and its link to actual VT / VfbThe ~400meV band alignment change occurs without an appreciable change in interfacial layer quality, thickness nor NitsSuch a large EWF modulation however impacts the NBTI significantly and scales roughly with the change in band alignmentCharge recovery experiments show that bulk defects contribute roughly 20% to the total NBTI contribution