Electrical characterisation of crystalline praseodymium oxide high-k gate dielectric MOSFETs

We have successfully completed the process integration of crystalline praseodymium oxide (Pr/sub 2/O/sub 3/) high-k gate dielectric in order to fabricate fully functional Pr/sub 2/O/sub 3/ MOSFETs with gate leakages <10/sup -6/ A/cm/sup 2/. Gate leakage is found to be size dependent and may be related to defects at Pr/sub 2/O/sub 3/ grain boundaries. Although fully functional, Pr/sub 2/O/sub 3/ NMOS transistors showed a lower performance when compared to conventional SiO/sub 2/ MOSFETs with the same EOT. The performance degradation is attributed to mobility reduction due to large amounts of trapped charges. In addition, a reversible Vt-instability is observed, even at operating conditions. These results suggest that charging/discharging of defects via tunneling within Pr/sub 2/O/sub 3/ and near the interfaces is a likely mechanism.