Jie Chen, David Wright, and Hugh Barnaby Electrical Engineering, ASU, Tempe, Az

1. Studying the Effect of Molecular Hydrogen on Silicon Device Radiation Response Using Gated Bipolar Transistors Jie Chen, David Wright, and Hugh Barnaby Electrical Engineering, ASU, Tempe, Az Hydrogen 2007

2. Topics of Discussion • Motivation for the study • Background • Initial experimental results • Modeling the effect of molecular hydrogen • Recent experimental results • Experimental data vs. model • Summary Hydrogen 2007

3. Motivation of Study Sealed package Previous experiments showed 3x increase in Nit in devices in sealedpackages compared toun-sealed ones. Unsealed package Hydrogen 2007

4. Post-irradiation annealing in H2 • MOSFETS exposed to 10Mrad and 1Mrad 10KeV x-rays. • Post-irradiation annealing in 100%, 10%, and 1% H2 environment. • Results show increase in Nit after annealing in H2. Increase in Nit Increase in Nit After Mrstik & Rendell, IEEE Trans. Nucl. Sci., 1991 Hydrogen 2007

5. Increase in Nit Earlier Experiments NAVSEA Crane performed HDR testing performed at NAVSEA on devices in 100% H2 Hydrogen 2007

6. Si-SiO2interface DH volume Ionizing radiation H H+ + + + H H+ + - fp - H fH - - xd tox Interface Trap Formation:2 stage model - hydrogen defect (D’H) - protons H+ - Si-H (NSiH) H - dangling bond (Nit) - proton flux fH H+ After Mclean TNS 1980Rashkeev et al. TNS 2002 Hydrogen 2007

7. H H H H H H H H Model:Impact of Molecular H2 H2 molecules Empty D centers Rad-inducedholes H2 transportinto material H DH centers Molecular hydrogen reacts with empty D centers to generate more DH centers Hydrogen 2007

8. 1D Analytical Model Steady state hole transport Equil. H2 - DH model (fp > 0 for all x) Proton continuity Trap continuity Final Model * Note: final 1D model assumes steady state, no Nit saturation or annealing Hydrogen 2007

9. Latest Experiments • 10%, 0.1%, 0.01%, 50% H2 ambient concentrations, as well as re-examination of 1% and 100% data points • GLPNP devices used are designed by NAVSEA Crane and fabricated using National’s standard linear bipolar IC process • Using only devices with no-passivation (Wafer #4) for simplicity (one less parameter in modeling) GLPNP with no passivation Hydrogen 2007

10. Experimental Details • 4 device samples for each H2 concentration • De-seal lids at least 3 days prior to soaking • 10-5 torr vacuum before filling of H2 • >48hrs soaking before irradiation • Gamma HDR test to 30Krad at 18 rad/s • Pb shield used during irradiation • Devices grounded during irradiation • Soaking temperature: 72 deg F • Irradiation temperature: 72 deg F H2 Chamber (Soaking & Irradiation) Hydrogen 2007

11. Latest Experimental Results • Characterization performed using Agilent 4156 SPA. Gate Sweep (GS), Subthreshold Sweep (SS), and Gummel are performed. • Gate Sweep: VG = 80V to -100V, VBE = 0.5V, VC = 0V Hydrogen 2007

12. Latest Experimental Results • Subthreshold Sweep: Vg = 10V to -100V, VE = -0.1V as the drain of the pMOSFET, VC = 0V, VB = 0V. Hydrogen 2007

13. 1D model fit to data • ASU results indicated monotonic increase of Nit vs ambient H2 concentration, agrees with the predictions of the model. • Saturation at high H2 and low H2 concentration agrees with the predictions of the model, • Crane’s 100% data is different than ASU’s 100% data. The difference may be due to differences in dose, dose rate, environmental factors, etc. Re-fit of the data with the analytical model Hydrogen 2007

14. Continuing work • Post-irradiation annealing studies • Effect of high pressure H2 environment • Model refinement • Relate dose-rate effects to the reaction processes of hydrogen species in SiO2 • Effect of H2 under low temperature exposure Hydrogen 2007