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
DESCRIPTION
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 - PowerPoint PPT PresentationTRANSCRIPT
June 13 2006 MURI Review 1
Total Dose Response of HfO2/Dy2O3 on Ge and Hf0.6Si0.2
ON0.2 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 13 2006 MURI Review 2
• Limitations of ultrathin SiO2 gate dielectric microelectronic devices: high gate leakage current, reduced current drive, and reliability concerns
• Leakage current unmanageable for tox 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
• HfO2 (K~25) and HfxSiyONz (K~15)
Motivation
M.L. Green, JAP 2001 (90) 5
1.2 nm
1.9 nm
June 13 2006 MURI Review 3
• HfO2/Dy2O3
• No measurable change in C-V characteristics after TID
• Large hysteresis and leakage current
• Hf0.6Si0.2ON0.2
• Significant electron trapping after TID
• Conclusions and future plans
Outline
June 13 2006 MURI Review 4
10nm or 5nm HfO2
1nm Dy2O3
Pt gate
n-type Ge
10nm or 5nm HfO2
1nm Dy2O3
Pt gate
n-type Ge
E0
5.65 eV
4.0 eV2.5 eV
1.5 eV
2.74 eV
0.8 eV
Ec
Ev
EF
HfO2 Dy2O3Pt Ge
EFM
E0
5.65 eV
4.0 eV2.5 eV
1.5 eV
2.74 eV
0.8 eV
Ec
Ev
EF
HfO2 Dy2O3Pt Ge
EFM
HfO2/Dy2O3 on Ge
Eg ~ 5.7 eV (HfO2)
June 13 2006 MURI Review 5
• Hysteresis ~ 800 mV for 10 nm HfO2, ~ 150 mV for 5 nm HfO2.
• No measurable change in C-V characteristics after total dose irradiation to 30 Mrad(SiO2) for 10 nm HfO2 and 10 Mrad(SiO2) for 5 nm HfO2
• Equal electron and hole trapping in HfO2 and/or large leakage currents neutralize radiation-induced oxide traps
C-V Characteristics
EOT= 1.9 nm EOT= 1.1 nm
June 13 2006 MURI Review 6
• Leakage current density @ 1 MV/cm: 30 nA/cm2 (EOT=1.9nm) and 35 nA/cm2 (EOT=1.1nm)
• Large leakage current reflects the interface quality of dysprosium oxide/germanium
Gate Current Densities
EOT= 1.1 nmEOT= 1.9 nm
June 13 2006 MURI Review 7
• HfO2/Dy2O3
• No measurable change in C-V characteristics after TID
• Large hysteresis and leakage current
• Hf0.6Si0.2ON0.2
• Significant electron trapping after TID
• Conclusions
• Future plan
Outline
June 13 2006 MURI Review 8
Hf0.6Si0.2ON0.2 on Si
Hf0.6Si0.2ON0.215 nm(EOT = 4 nm)
Al gate
n-type Si
Hf0.6Si0.2ON0.215 nm(EOT = 4 nm)
Al gate
n-type Si
2.4 eV
3.7 eV
7.2 eV
HfxSiyONz Si
June 13 2006 MURI Review 9
C-V Characteristics
• Hysteresis ~ 15 mV
• Jg ~ 2 nA/cm2 @ VG = 0.4 V
June 13 2006 MURI Review 10
Charge trapping in Hf0.6Si0.2ON0.2 on Si
• Correlation between crystallization and ∆VTH
• Trap density increases with crystallization
• Crystallization increases with increasing thickness
Dit ~ 2 x 1011 cm-2 eV-1 pre-irradiation ∆NOT = 6.27 x 1012 cm2 after 500 krad
Predominantly electron traps
G. Pant, APL 2006 (88) 032901
June 13 2006 MURI Review 11
Plan for future experiments
• Obtain new HfO2/Dy2O3 films of various thicknesses – check hysteresis, leakage, rad response
• Determine the structure and composition of the Hf0.6Si
0.2ON0.2 films – irradiate under negative and zero bias to obtain additional trapping information
• Perform Bias Temperature Instability (BTI) tests to further investigate properties of Hf0.6Si0.2ON0.2 films
June 13 2006 MURI Review 12
• HfO2/Dy2O3 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 HfO2/Dy2O3 and Ge
• Future work will concentrate on films with low leakage and hysteresis
• Hf0.6Si0.2ON0.2 on Si
• Low hysteresis
• Significant electron trapping due to film composition
Conclusions