Role of Hydrogen in Radiation Response of Lateral PNP Bipolar Transistors

1. Role of Hydrogen in Radiation Response of Lateral PNP Bipolar Transistors I.G.Batyrev1, R. Durand2, D.R.Hughart2, D.M.Fleetwood2,1, R.D.Schrimpf2 ,M.Law3 and S.T.Pantelides1 1Department of Physics and Astronomy 2Electrical Engineering and Computer Science Department Vanderbilt University, Nashville, TN 3Department of Electrical and Computer Eng., University of Florida Supported by AFOSR and US Navy

2. Outline • Experimental results on H2 diffusion from NAVSEA Crane • Strong effect of H2 exposure on BJT rad response • Multilevel modeling approach • Hydrogen molecule diffusion, FLOOPS/FLOODS • First principles calculations • Interactions of H2 with holes and defects • H+ with defects near interface • I(V) curves , ISE TCAD

3. H2 exposures at Crane (G. Dunham) • Devices were sealed in 100% H2 atmosphere for various times at room temperature • Apparatus used low H2 permeability tubing with vacuum grease at all seals. • During H2 soak and irradiation, all pins were tied together. • System volume is ~0.45 liters. The system was purged with at least 2 liters of 100% H2 prior to sealing the system. For long soaks, H2 was added every 6 to 12 hours. • Devices were irradiated to 10 krad(SiO2) at 40 rad(SiO2)/s at room temperature • Devices were tested no later than 2 minutes after completion of irradiation.

4. Very strong effect of H2 exposure on TID response H2 exposure makes these bipolar transistors much softer All parts were irradiated to the sameTID 10 krad(SiO2)

5. Florida Object Oriented Process Simulator FLOOPS • Object oriented • Multi-dimensional • Complex shapes and edges • Meshing of oxide and over layers • TR-BDF time discretization operator for PDE • Different boundary conditions for different • interfaces of device with packaging

6. 100 % H2 μm 7*1017 cm-3 PSG 1.5 PSG 3*1017 cm-3 Al Al 1.0 6*1015 cm-3 SiO2 0.5 Al 3*1015 cm-3 SiO2 μm 10 -10 C B E

7. H2 concentration in base oxide, calculated with FLOOPS Rapid increase of hydrogen in gate region of bipolar device due to H2 soak Qualitatively similar to rad response (Hr) H2 Soak Time (Hr) a 7

8. Experimental Ic & Ib(Vbe) curves Ic, 48 hours H2 soak Ib, 48 hours H2 soak, postrad Ib, 1 hour H2 soak, postrad Ib, 48 hours H2 soak, prerad Data from NSWC Crane

9. First principles calculations • Activation energies • Cross-sections and rates of reactions • - generation of protons • - depassivation of Si-H bonds near interface • Discretization of the rate equations in a particular device geometry • p(x,t), n(x,t), CH+ (x,t), ΔNit(x,t)

10. Simulation of effect of interface trap density ΔNit on Ic & Ib(Vbe) curves Ic Ib, ΔNit ~ 1011 cm-2 Ib, ΔNit ~1010 cm-2 Ib, ΔNit< 109 cm-2

11. Conclusions Exposure to H2 dramatically affects radiation response Overlayers affect H2 transport H2 diffuses through oxides and reacts to form interface traps Multi-scale simulation approach developed H2 transport Charge transport and trapping Interface-trap formation Transistor-level degradation Data base of hydrogen properties in microelectronic materials produced Diffusivities Activation energies