June MURI Review1 Total Dose Response of HfO 2 /Dy 2 O 3 on Ge and Hf 0.6 Si 0.2 ON 0.2 on Si MOS Capacitors D. K. Chen, R. D. Schrimpf, D. M. Fleetwood, K. F. Galloway, A. Canals Department of Electrical Engineering and Computer Science, S. T. Pantelides, Department of Physics Vanderbilt University, Nashville, TN A. Dimoulas, A. Sotiropoulos, and Y. Panayiotatos Institute of Materials Science, NCSR DEMOKRITOS Athens, Greece G. Lucovsky, S. Lee Dept of Physics and Material Science, North Carolina State University Bongim Jun Dept of Electrical Engineering, Georgia Institute of Technology

June MURI Review2 Limitations of ultrathin SiO 2 gate dielectric microelectronic devices: high gate leakage current, reduced current drive, and reliability concerns Leakage current unmanageable for t ox less than ~ 1.2 nm Germanium MOS devices Higher electron and hole mobility leads to higher drive current Unstable native oxide Dysprosium oxide on Ge HfO 2 (K~25) and Hf x Si y ON z (K~15) Motivation M.L. Green, JAP 2001 (90) nm 1.9 nm

June MURI Review3 HfO 2 /Dy 2 O 3 No measurable change in C-V characteristics after TID Large hysteresis and leakage current Hf 0.6 Si 0.2 ON 0.2 Significant electron trapping after TID Conclusions and future plans Outline

June MURI Review4 HfO 2 /Dy 2 O 3 on Ge E g ~ 5.7 eV (HfO 2 )

June MURI Review5 Hysteresis ~ 800 mV for 10 nm HfO 2, ~ 150 mV for 5 nm HfO 2. No measurable change in C-V characteristics after total dose irradiation to 30 Mrad(SiO 2 ) for 10 nm HfO 2 and 10 Mrad(SiO 2 ) for 5 nm HfO 2 Equal electron and hole trapping in HfO 2 and/or large leakage currents neutralize radiation-induced oxide traps C-V Characteristics EOT= 1.9 nmEOT= 1.1 nm

June MURI Review6 Leakage current 1 MV/cm: 30 nA/cm 2 (EOT=1.9nm) and 35 nA/cm 2 (EOT=1.1nm) Large leakage current reflects the interface quality of dysprosium oxide/germanium Gate Current Densities EOT= 1.1 nm EOT= 1.9 nm

June MURI Review7 HfO 2 /Dy 2 O 3 No measurable change in C-V characteristics after TID Large hysteresis and leakage current Hf 0.6 Si 0.2 ON 0.2 Significant electron trapping after TID Conclusions Future plan Outline

June MURI Review8 Hf 0.6 Si 0.2 ON 0.2 on Si 2.4 eV 3.7 eV 7.2 eV Hf x Si y ON z Si

June MURI Review9 C-V Characteristics Hysteresis ~ 15 mV J g ~ 2 nA/cm V G = 0.4 V

June MURI Review10 Charge trapping in Hf 0.6 Si 0.2 ON 0.2 on Si Correlation between crystallization and ∆V TH Trap density increases with crystallization Crystallization increases with increasing thickness D it ~ 2 x cm -2 eV -1 pre-irradiation ∆N OT = 6.27 x cm 2 after 500 krad Predominantly electron traps G. Pant, APL 2006 (88)

June MURI Review11 Plan for future experiments Obtain new HfO 2 /Dy 2 O 3 films of various thicknesses – check hysteresis, leakage, rad response Determine the structure and composition of the Hf 0.6 Si 0.2 ON 0.2 films – irradiate under negative and zero bias to obtain additional trapping information Perform Bias Temperature Instability (BTI) tests to further investigate properties of Hf 0.6 Si 0.2 ON 0.2 films

June MURI Review12 HfO 2 /Dy 2 O 3 on Ge Gate leakage current and/or equal electron hole charge trapping cause neutralization of radiation-induced oxide trap charges High border trap densities reflect the physical nature of interface of HfO 2 /Dy 2 O 3 and Ge Future work will concentrate on films with low leakage and hysteresis Hf 0.6 Si 0.2 ON 0.2 on Si Low hysteresis Significant electron trapping due to film composition Conclusions