INDUCED DAMAGES IN POWER MOSFETS AFTER HEAVY IONS IRRADIATION

1
University of Cassino DAEIMI Department of
Automation, Electromagnetism, Information
Engineering and Industrial Mathematics
STMicroelectronics Rad-Hard Power MOS Reliability
Group
INDUCED DAMAGES IN POWER MOSFETS AFTER HEAVY
IONS IRRADIATION
G. Busatto, F. Iannuzzo, A. Porzio, A.
Sanseverino, F. Velardi DAEIMI University of
Cassino Via G. Di Biasio, 43 03043 CASSINO
(FR) 39 0776.299.4370 a.porzio_at_unicas.it
G.Currò, STMicroelectronics Stradale
Primosole, 50 CATANIA ITALY 39
095.740.9643 giuseppe.curro_at_st.com
11th ICATPP Conference on Astroparticle,
Particle, Space Physics, Detectors and Medical
Physics Applications Villa Olmo, Como 5-9
October 2009
2
INTRODUCTION
Altitude Flux Factor gt10MeV flux (cm-2h-1)
Sea level 1 20
1500 m(Denver) 3-4 70
3000 m(Leadville) 10-15 250
12000 m 200-300 4000-6000
J.F. Ziegler Terrestrial cosmic rays IBM J.
RES. DEVELOP. VOL. 40 NO. 1 JANUARY 1996
3
INTRODUCTION
4
THE UTILIZED FACILITIES
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THE UTILIZED IONS
a)
c)
Ion type used and its Energy Longitudinal range mm in silicon Longitudinal range mm in metal silicon nitride lopysilicon silicon dioxide silicon Energy Loss eV/Å in the oxide layer
a) 197Au79, 246 MeV 23.9 24.5 1480
b) 79Br35, 223 MeV 30.6 32.1 976
c) 84Kr36, 756 MeV 92.4 93.1 771
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THE EXPERIMENTAL SETUP
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SINGLE EVENT GATE RUPTURE
SEGR
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THE TESTED DEVICES
MOSFET Type Epitaxial Thickness Gate Oxide Thickness Inter-Cell Spacing Body Profile
A high buffer single standard standard
B high buffer double standard standard
C high buffer single 20 reduced standard
D high buffer single 40 reduced standard
E high buffer single standard single implant
F high buffer single standard double implant
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THE TESTED DEVICES
MOSFET TYPE BODY PROFILE VDS Gate Damage
A STANDARD 70V
E SINGLE IMPLANT 70V
MOSFET TYPE BODY PROFILE
A STANDARD
E SINGLE IMPLANT
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THE TESTED DEVICES
MOSFET TYPE BODY PROFILE
E SINGLE IMPLANT
F DOUBLE IMPLANT
MOSFET TYPE BODY PROFILE VDS Gate Damage
E SINGLE IMPLANT 70V
F DOUBLE IMPLANT 70V
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THE TESTED DEVICES
VGS0
MOSFET Type Inter-Cell Spacing
A STANDARD
C 20 REDUCED
D 40 REDUCED
MOSFET Type Inter-Cell Spacing VDS Gate Damage
A STANDARD 70V
C 20 REDUCED 120V
D 40 REDUCED 150V
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THE TESTED DEVICES
VGS0
MOSFET Type Gate Oxide Thickness
A single
B double
MOSFET Type Gate Oxide Thickness VDS Gate Damage
A single 70V
B double 150V
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THE SEGR INTERPRETATION

• The SEGR model has been obtained by assuming
  that the electric field in the dioxide layer is
  simply offered by combining
• the electric field E1, numerically achieved by 3D
  simulation, due to the silicon internally charge
  generation mechanism after ion impact
• the electric field E2, numerically achieved by a
  physical model, due to the survived holes
  generated in the dioxide layer after ion impact.

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THE 3D SIMULATION
R 0.124mm
t0 4ps
tC 2ps
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THE SIMULATED ELECTRIC FIELD E1
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THE SEGR INTERPRETATION
Ion track
DIOXIDE LAYER
Ion energy loss

• Charge generated
• Initial electron-hole pair density

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THE SEGR INTERPRETATION
DIOXIDE LAYER
The electrons move at the saturated velocity (107
cm/s) and are swept out the oxide very
rapidly. In one picosecond the electrons are
completely removed from the oxide. This
recombination interval leads to a fractional
yield of 0.72.
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THE SEGR INTERPRETATION
DIOXIDE LAYER
Due to their very low diffusivity and mobility
the survived holes are relatively immobile for
the duration of the SEGR event. They remain
behind, near their point of generation, and cause
an additional electric field shift . This
additional electric field, at the
dioxide/polysilicon interface in the channel
region, has been estimated by considering the
almost uniform cylindrical distribution of the
survived holes.
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THE SIMULATED ELECTRIC FIELD E2
The computation leads to a value of 6.2MV/cm
(Br_at_223MeV).
N. Boruta, et al. A New Physics-Based Model for
Understanding Single-Event Gate Rupture in Linear
Devices IEEE T-NS, vol. 48, NO. 6, pp.
1917-1924, December 2001
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THE SEGR INTERPRETATION
DIOXIDE LAYER
By assuming that the electric field, at the
dioxide/polysilicon interface, is the simple
composition of the electric field due to the
silicon internally charge generation mechanism
and the electric field due to the survived holes
generated in the dioxide, we obtain E E1E2 gt
14MV/cm gt ESiO2crit
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GATE DAMAGES
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LATENT DAMAGE
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LATENT DAMAGE
Electric Stess on not-irradiated device
Corresponding Post Gate Electric Stess
IGSS during irradiation (30 ions)
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LATENT DAMAGE
b
c
The simulated Electric Field in the oxide
(EOX_SI) due to the generated charge in silicon
during irradiation
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LATENT DAMAGE
N. Boruta, et al. A New Physics-Based Model for
Understanding Single-Event Gate Rupture in Linear
Devices IEEE T-NS, vol. 48, NO. 6, pp.
1917-1924, December 2001
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LATENT DAMAGE
Au 246MeV Br 223MeV Kr 756MeV
Vds V Vgs V Igss nA _at_ Vgs 10V Igss nA _at_ Vgs10V Igss nA _at_ Vgs 10V
20 0 18.5 lt1 lt1
40 0 37 22 lt1
60 0 36.5 23 50
80 0 50 38 600
100 0 475 180 1000
The 100V MOSFET Leakage Current Igss measured
after each Irradiation
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CONCLUSIONS

• An interpretation of the evolution of the gate
  leakage current in a power MOSFET during heavy
  ion irradiation has been presented.
• The drain voltage at which latent damages start
  to appear seems to be more correlated to the
  charge generated at the surface than to the one
  generated in the silicon.
• The experimental results show that the formation
  of the latent damages is strictly related to the
  two components of the electric field across the
  oxide.

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University of Cassino DAEIMI Department of
Automation, Electromagnetism, Information
Engineering and Industrial Mathematics
STMicroelectronics Rad-Hard Power MOS Reliability
Group
INDUCED DAMAGES IN POWER MOSFETS AFTER HEAVY
IONS IRRADIATION
THANKS FOR YOUR ATTENTION
Antonino Porzio DAEIMI University of Cassino
Via G. Di Biasio, 43 03043 CASSINO (FR) 39
0776.299.4370 a.porzio_at_unicas.it
11th ICATPP Conference on Astroparticle,
Particle, Space Physics, Detectors and Medical
Physics Applications Villa Olmo, Como 5-9
October 2009
29
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INTRODUCTION

• An ionizing particle generates a dense track of
  electron-hole pairs in semiconductors (Silicon)
  and dielectrics (SiO2)
• The number of generated carriers is proportional
  to the particle Linear Energy Transfer (LET)
  coefficient (MeV cm2/mg), i.e., the ionizing
  energy loss/unit path length (Energy/e-h pair
  3.6 eV in Si, 17 eV in SiO2)

Ion track
31
INTRODUCTION

• Under an external electric field the two columns
  of carriers recombine and drift many electrons
  and holes survive in Si and in SiO2
• If (some of) the charge generated by a single
  high LET particle is collected by a sensitive
  region of the device/circuit, and this charge is
  larger than the critical charge required to start
  an anomalous behavior, an effect (Single Event
  Effect) may be seen, affecting the electrical
  performance of the device/circuit.

Electric Field
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SINGLE EVENT BURNOUT
PARASITIC BIPOLAR TRANSISTOR
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THE TESTED DEVICES
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THE TESTED DEVICES
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THE EXPERIMENTAL RESULTS
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THE EXPERIMENTAL RESULTS
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THE RESULT OF SEB SIMULATION
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THE DEVICE WITH NO SEB
MOSFET Type Epitaxial Thickness VDS Drain Damage
A Low 95V
D High Buffer Layer No Damage