Improvement in High-$k$$(hboxHfO_2/hboxSiO_2)$Reliability by Incorporation of Fluorine

In this letter, we demonstrate that negative bias temperature instability of high-k (HfO
₂
/SiO
₂
) gate dielectric stacks can be greatly improved by incorporating fluorine and engineering its concentration depth profile with respect to HfO
₂
/SiO
₂
interface. It was found that fluorine is easily incorporated in HfO
₂
/SiO
₂
at low temperatures (les400degC) by F
₂
anneal in the presence of UV radiation. Fluorine tends to segregate at the HfO
₂
/SiO
₂
interface and, to a lesser extent, diffuses into the underlying SiO
₂
/Si interface. The HfO
₂
/SiO
₂
stacks with F addition show significantly reduced (<50%) positive charge trapping and interface states generation compared to control samples without F