Role of Hydrogen in Radiation Response of Lateral PNP Bipolar Transistors I.G.Batyrev 1, R. Durand 2, D.R.Hughart 2, D.M.Fleetwood 2,1, R.D.Schrimpf 2,M.Law 3 and S.T.Pantelides 1 1 Department of Physics and Astronomy 2 Electrical Engineering and Computer Science Department Vanderbilt University, Nashville, TN 3 Department of Electrical and Computer Eng., University of Florida Supported by AFOSR and US Navy

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

H 2 exposures at Crane (G. Dunham) Devices were sealed in 100% H 2 atmosphere for various times at room temperature –Apparatus used low H 2 permeability tubing with vacuum grease at all seals. –During H 2 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% H 2 prior to sealing the system. For long soaks, H 2 was added every 6 to 12 hours. Devices were irradiated to 10 krad(SiO 2 ) at 40 rad(SiO 2 )/s at room temperature –Devices were tested no later than 2 minutes after completion of irradiation.

Very strong effect of H 2 exposure on TID response H 2 exposure makes these bipolar transistors much softer All parts were irradiated to the same TID 10 krad(SiO 2 )

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

PSG Al 7*10 17 cm -3 3*10 17 cm -3 6*10 15 cm -3 3*10 15 cm -3 SiO % H 2 CBE μmμm μmμm

7 Rapid increase of hydrogen in gate region of bipolar device due to H 2 soak Qualitatively similar to rad response a H 2 concentration in base oxide, calculated with FLOOPS H 2 Soak Time (Hr) (Hr)

Experimental I c & I b (V be ) curves I c, 48 hours H 2 soak I b, 48 hours H 2 soak, prerad I b, 1 hour H 2 soak, postrad I b, 48 hours H 2 soak, postrad Data from NSWC Crane

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), C H + (x,t), ΔN it (x,t) First principles calculations

Simulation of effect of interface trap density ΔN it on I c & I b (V be ) curves IcIc I b, ΔN it < 10 9 cm -2 I b, ΔN it ~10 10 cm -2 I b, ΔN it ~ cm -2

Conclusions Exposure to H 2 dramatically affects radiation response –Overlayers affect H 2 transport –H 2 diffuses through oxides and reacts to form interface traps Multi-scale simulation approach developed –H 2 transport –Charge transport and trapping –Interface-trap formation –Transistor-level degradation Data base of hydrogen properties in microelectronic materials produced –Diffusivities –Activation energies