(Invited) Negatively Charged Defects Generated by Rare-Earth Materials Incorporation into HfO2 and the Impact on the Gate Dielectrics Reliability

We studied the impact of Yttrium and Lanthanum incorporation into HfO2 on reliability (TDDB, PBTI and 1/f noise). They introduce smaller Weibull β values and early failure in TDDB, with negative shift in PBTI. They are caused by the negatively charged interstitial oxygen defect generated by Yttrium and Lanthanum incorporation. The effect of Lanthanum is larger than that of Yttrium. It can be explained by the larger ion radius and molecular volume of La2O3 than Y2O3. On the other hand, they are effective in noise reduction, as an effect of interface state density reduction. The key point in fabricating low Vth and highly reliable MOSFETs is the technology for suppression of this interstitial oxygen defect generation.