jie chen, david wright, and hugh barnaby electrical engineering, asu, tempe, az
DESCRIPTION
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. Topics of Discussion. Motivation for the study Background Initial experimental results - PowerPoint PPT PresentationTRANSCRIPT
Hydrogen 2007 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
1.E-09
1.E-08
1.E-07
1.E-06
-100 -80 -60 -40 -20 0
Vg (V)
Ib (
A)
sealed @ 30krad
unsealed @ 30Krad after 8 days
Previous experiments showed 3x increase in Nit in devices in sealedpackages compared toun-sealed ones.
ΔNot (cm-2) ΔNit (cm-2)
Unsealed ~1.7x1011 ~0.8x1011 0.00005% H2
Sealed ~1.4x1011 ~2.5x1011 1.3% H2
Sealed package
Unsealed package
Hydrogen 2007 4
Post-irradiation annealing in H2
After Mrstik & Rendell, IEEE Trans. Nucl. Sci., 1991
• 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
Hydrogen 2007 5
Earlier Experiments
NAVSEA Crane performed HDR testing performed at NAVSEA on devices in 100% H2
1.E-09
1.E-08
1.E-07
1.E-06
-100 -80 -60 -40 -20 0Vg (V)
Ib (A
)
preradIrrad in airIrrad in 1.3% H2Irrad in 100% H2
0
5E+10
1E+11
1.5E+11
2E+11
2.5E+11
0 10000 20000 30000 40000
Total Dose (rad)
del N
it (c
m^-
2)
Air (unsealed)
1.3% H2 (sealed)
100% H2 (unsealed)
Increase in Nit
Hydrogen 2007 6
Interface Trap Formation:2 stage model
Si-SiO2
interface
-+
-
+
-
+
H
-
+fH
tox
Ionizing radiation
H
xd
H
DH volume
fp
H+
H+
- protons
- Si-H (NSiH)
- dangling bond (Nit)
H
H+
fH- proton flux
- hydrogen defect (D’H)
H+
HDH DH p
f HN f
x t
it itSiH it it H
it
N N (t)N N (t) σ f
t
After Mclean TNS 1980Rashkeev et al. TNS 2002
Hydrogen 2007 7
Model:Impact of Molecular H2
Si-SiO2
interface
-+
-
+
-
+
H
-
+fH
tox
Ionizing radiation
H
xd
H
D’H volume
fp
H+
H+
H+
Si-SiO2
interface
-+
-
+
-
+
H
-
+fH
tox
Ionizing radiation
H
xd
H
D’H volume
fp
H+
H+
H+
Empty D centers
HH
HH
H2 molecules
Molecular hydrogen reacts with empty D centers to generate more DH centers
2DH2DH2
HH
DHcenters
H
H
H
H2 transportinto material
21
H2
21H1
DH
2
2
Nk1
Nk N
Rad-inducedholes
Hydrogen 2007 8
1D Analytical Model
2
2
1
21 2
1
22
2
1oDH DH SiH it g y o
Hit
H
x
k ( )N ( N Dk f t t )
NN
N
/
k ( )
Note: final 1D model assumes steady state, no Nit saturation or annealing
21
H2
21H1
DH
2
2
Nk1
Nk N
Equil. H2 - DH model Steady state hole transport
oxygp tfkDf (fp > 0 for all x)
HDH DH p
f HN f
x t
Proton continuity
it itSiH it it H
it
N N (t)N N (t) σ f
t
Trap continuity
Final Model
*
Hydrogen 2007 9
Latest Experiments
• 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)
• 10%, 0.1%, 0.01%, 50% H2 ambient concentrations, as well as re-examination of 1% and 100% data points
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