1. MURI kick-off: 5/10/05 Total-Dose Response and Negative-Bias Temperature Instability (NBTI) D. M. Fleetwood Professor and Chair, EECS Dept. Vanderbilt University Nashville, TN 37235 USA dan.fleetwood@vanderbilt.edu (615) 322-2498 A collaboration between VU EECS and Physics

2. MURI kick-off: 5/10/05 Assistant Professors Recently Hired in EE William Robinson PhD, Georgia Tech, 2003 computer architecture/VLSI design mixed-signal integration for focal plane processing integrated sensor technology system-on-a-chip multimedia processing william.h.robinson@vanderbilt.edu Sharon Weiss PhD, Institute of Optics, Univ. Rochester, 2005 optical properties of nanostructures porous silicon; photonic bandgap structures optical characterization techniques surface characterization methods sweiss@optics.rochester.edu

3. MURI kick-off: 5/10/05 Outline Total Dose –Oxide and interface traps –Leakage in thin SiO 2 –SOI/double gate –High K NBTI –Experimental data –Theory based on DFT calculations

4. MURI kick-off: 5/10/05 Traditional MOS Basic Mechanisms After F. B. McLean and T. R. Oldham, HDL Report HDL-TR-2129 (1987)

5. MURI kick-off: 5/10/05 Progress in physical models of interface-trap charge via DFT calculations H+H+ H O Si O H H2H2 O + SiH + H + → H 2 + D + S. N. Rashkeev et al., Phys. Rev. Lett. 87, 165506-1 to 165506-4 (2001)

6. MURI kick-off: 5/10/05 Threshold voltage shifts less important in modern gate oxides Doped Poly-Si Gate Device Si SiO 2 After N. S. Saks et al, IEEE Trans. Nucl. Sci. 33, 1185 (1986)

7. MURI kick-off: 5/10/05 Ultrathin SiO 2 : the main issue is leakage! J. Suñé et al., Semicond. Sci. Technol., 15, 2000. RILC M. Ceschia et al., IEEE Trans. Nucl. Sci. 45, 2375 (1998)

8. MURI kick-off: 5/10/05 Improved performance and radiation response possible for FD SOI devices operated in double-gate mode B. Jun et al., IEEE Trans. Nucl. Sci. 51, 3767-3772 (2004). Front-back coupling Volume inversion

9. MURI kick-off: 5/10/05 Alternative Dielectrics to SiO 2 More defects: greater charge trapping than thermal SiO 2 J. A. Felix et al., IEEE Trans. Nucl. Sci. 49, 3191 (2002) Alumina (EOT 8 nm) EOT 4.5 nm J. A. Felix et al., IEEE Trans. Nucl. Sci. 50, 1910 (2003)

10. MURI kick-off: 5/10/05 Temperature dependence: SiO 2 & HfO 2 SiO 2 ----E a (for N ot )=0.27  0.03eV HfO 2 ---E a (for N ot )=0.35  0.04eV ---- E a (for N it )=0.31  0.04eV ---E a (for N it )=0.22  0.03eV X. J. Zhou et al., Appl. Phys. Lett. 84, 4394 (2004) Why so low ?? (APL 2005) – summarized here Effects of rad (NSREC 2005)

11. MURI kick-off: 5/10/05 Theory: Methodology  First-principles (density-functional) calculations  Pseudopotentials, plane-wave basis, supercells A B EaEa EE For hydrogen … Reactions: A → B  E : Reaction Energy E a : Reaction Barrier Barriers ↔ Activation Energy L. Tsetseris, X. J. Zhou, D. M. Fleetwood, R. D. Schrimpf, and S. T. Pantelides, “Physical mechanisms of negative-bias temperature instability,” Appl. Phys. Lett. 86, 142103-1 to 142103-3 (2005).

12. MURI kick-off: 5/10/05 Interface traps: Si dangling bond (D) Hydrogen Passivates- Depassivates: Si-H + H ↔ D + H 2 [Or: Si-H + H + ↔ D + + H 2 *] D + H ↔ Si-H = H = Si = O * S. N. Rashkeev, D. M. Fleetwood, R. D. Schrimpf, and S. T. Pantelides, “Defect Generation by Hydrogen at the Si-SiO 2 Interface,” Phys. Rev. Lett. 87, 165506-1 to 165506-4 (2001).

13. MURI kick-off: 5/10/05 Simple Si-H Dissociation 1.9 eV No holes With holes 1.6 eV A B A B

14. MURI kick-off: 5/10/05 REACTION (depassivation) = H = Si = O  E ~ 0.5 eV E a ~ 1 eV

15. MURI kick-off: 5/10/05 MIGRATION H + in SiO 2 :  D ~ 0.8 eV H 2 in SiO 2 :  D ~ 0.45 eV Si-H + H + ↔ D + H 2 : H 2 diffusion controlling factor SiSiO 2 = H = Si = O

16. MURI kick-off: 5/10/05 REACTION-DIFFUSION MODEL (Jeppson & Svensson (1977), Ogawa & Shiono (1995)) Defect (N D ) + A  Interface trap (N it ) + B Reaction in quasi-equilibrium: N it (t) C X (t) ~ G/S N D Asymptotic Limit: N it (t) ~ (D X t) 1/4 (G/S N D ) 1/2

17. MURI kick-off: 5/10/05 NBTI ACTIVATION ENERGY So, E a NBTI ~ 0.35 eV E a = ½  E + ¼  D  E = 0.5 eV,  D = 0.45 eV L. Tsetseris, X. J. Zhou, D. M. Fleetwood, R. D. Schrimpf, and S. T. Pantelides, “Physical mechanisms of negative-bias temperature instability,” Appl. Phys. Lett. 86, 142103-1 to 142103-3 (2005).

18. MURI kick-off: 5/10/05 SOURCE (of Hydrogen) for pMOS Dissociation of P-H complexesA B  E ≈ 0.2 eV A B E a ≈ 0.35 eV With holes  E ≈ 0.6 eV A B E a ≈ 1.2 eV No holes Confirm experiments (Herring & Johnson, 1992, and others)

19. MURI kick-off: 5/10/05 OXIDE TRAPPED CHARGE H + in SiO 2 :  D ~ 0.8 eV H + from Si to SiO 2 :  ~ 0.2 eV SiSiO 2 = H = Si = O E a = ½  E + ¼  D E a ~ 0.3 eV

20. MURI kick-off: 5/10/05 Future Work Radiation + NBTI High-K dielectrics: experiment and theory Metal gates Strained substrates & SOI Aging and temperature response Much to do!!