Single%20Event%20Effects%20in%20microelectronic%20circuits

1
Single Event Effects in microelectronic circuits

• Author Klemen Koselj
• Advisor Prof. Dr. Peter Križan

2
Agenda

• Introduction what are Single Event Effects
  (SEE) and their classification.
• Ionizing radiation environment and SEE's.
• How SEE testing is done?
• SEE testing with radiation method
• SEE testing with pulsed laser method
• Conclusion

3
Microelectronic circuits in radiation environment

• The effects resulting from the interaction of
  high-energy ionizing radiation with semiconductor
  material can have a major impact on the
  performance of space-based and accelerator-based
  microelectronic circuitry. Two categories
• Total ionizing dose effects.
• Single Event Effects (SEE).

4
What is a SEE?

• Electrical disturbance in a microelectronic
  circuit caused by the passage of a single
  ionizing particle through semiconductor material.
• As a single high-energy particle penetrates a
  circuit, it leaves behind a dense plasma track in
  the form of electron-hole pairs. A circuit
  functional error, or even a circuit failure, will
  occur if sufficient charge from the plasma track
  is collected at a sensitive circuit node.

5
Types of SEE

• Single-event upset (SEU) is a change of state or
  transient induced by an ionizing particle such as
  a cosmic ray or proton in a device.
• Single-event latch up (SEL) is a potentially
  destructive condition involving parasitic circuit
  elements.
• Other types (Single event burnout (SEB)
  destructive form of SEL, ...)

6
Types of SEE - again

• Categorization of SEE's is also possible in terms
  of whether they are soft or hard errors regarding
  the amount and permanency of damage made to the
  device.
• Soft errors are nondestructive. They may appear
  as a bit flip in a memory cell or as transients
  occurring on the output of an I/O, logic, or
  other support circuit. SEU is a soft error.
• Hard errors may be (but are not necessarily)
  physically destructive and are permanent
  functional effects. SEL and SEB are hard errors.

7
Ionizing radiation environment and SEEs

• Most problems in microelectronic circuits by
  present date were observed in space-based
  electronics.
• Problems in operating due to SEEs were also
  observed in avionics electronics.
• Read-out electronics in accelerator environment
  is affected by high-energy ionizing radiation.
• SEEs were observed and are significant in a
  population of humans with implantable
  cardioverter defibrillators. SEEs in this case
  are caused by secondary cosmic ray neutron flux.

8
SEE errors from the UoSAT-3 spacecraft in polar
orbit

• Most SEE errors occur in the so-called South
  Atlantic Anomaly
• Errors occur because of protons with broad energy
  spectrum (energies from keV to several hundreds
  of MeV) are trapped in the so-called Van Allen
  belt.
• Significant number of errors occur at high
  latitudes due to galactic cosmic rays.

9
How does a SEE appear?

• Caused by a deposition of a large amount of
  energy in a small sensitive volume, typically 10
  MeV energy deposition over 1 ?m particle path
  length.
• Following Bethe and Bloch the average energy loss
  dE per length dx is given by

10
Energy deposition

• For highly relativistic Z 1 particles with ?
  1, dE/dx4.6 MeV/cm in silicon. Not enough for
  SEE.
• For a SEE to occur slow particles (? 10-2) or
  particles with high Z (or a combination of both
  parameters) are needed in order to produce 10 MeV
  energy deposition over 1 ?m which is needed to
  produce enough charge for SEE.
• Protons can not cause SEE directly. Electrons
  either.

11
Electron-hole pair creation
12
Where do particles with proper energy deposition
come from?

• Spallation reactions of neutrons and protons with
  silicon 28Si(n,?)25Mg, 28Si(n,p)28Al, and
  28Si(p,2p)28Al all produces recoilling heavy
  nuclei.
• Production of silicon recoil nuclei through
  electromagnetic interaction.
• 10B(n,?)7Li produces an alpha particle and the
  residual 7Li. (Boron is often used for doping in
  semiconductor industry.)

13
Electron hole-pair distribution

• The electron-hole pair distribution depends on
  radial distance from the center of the track.
• Once the electron-hole pairs are established in
  the track, the carriers can be collected at
  junctions in the structure.
• Complicated drift, diffusion and recombination
  processes are responsible for generated charge
  transport.

Initial electron-hole density as a function of
radius from the center of ion track for various
depths for (a) 70 MeV and 250 MeV Cu ions
14
Calculating SEE's error rates

• In the burst generation rate (BGR) model a SEE
  may occur when a high-energy particle strikes the
  reversed biased pn junction of a memory cell and
  deposits sufficient (critical) charge in small
  enough (sensitive) volume to cause a change in
  memory state.
• The soft error rate (SER) is given by

15
Burst generation rate method

• To obtain quantitative measure for soft error
  rate we need to identify all important
  interactions of ionizing radiation for a given
  environment.
• Then Qc has to be estimated. In memory cells,
  where charge is used to store information (DRAM's
  and CCD's), it is assumed that a sudden
  spontaneous 20 percent variation in charge may
  cause the device to invert (from strored '1' to
  '0').
• Finally we have to measure the fluxes and spectra
  of radiation in environments where soft error
  rate is of interest, and together with measured
  or calculated burst generation rate calculate
  particle-induced error for each of the important
  interactions.

16
Chip errors induced by sea-level cosmic rays
obtained with BGR
SEE rates in implantable cardioverter
defibrillators were also estimated using BGR as
4.5?10-12 upset/bit-hr which is well in
accordance with observations in the field.
17
Single event effects testing

• There are two important SEE testing techniques
  nowadays
• The tests are traditionally performed using
  energetic particles produced at accelerators to
  simulate the radiation environment in which
  device under test will operate.
• Recently laser pulses have been used to induce
  SEE's.

18
SEE testing with the radiation method

• Particle accelerator testing is the standard
  method used to characterize the sensitivity of
  microelectronic circuitry to SEE.
• The goal of SEE testing with radiation method is
  to determine the cross section vs. the deposited
  energy (known as Linear Energy Transfer (LET))

19
Single event effects testing with pulsed laser
method

• Pulsed laser method is based on the ability of
  laser pulses to provide a reasonable
  approximation of the interaction between a
  high-energy particle and a semiconductor.
• It provides complementary information and some
  unique characteristics and capabilities that are
  particularly useful for SEE studies spatial
  distribution.

20
Benefits of pulsed laser method

• The laser can be focused down and imaged to a
  small spot (? 1 ?m). Therefore sensitivity of
  individual circuit elements can be measured. This
  is not easily accomplished with radiation method.
  
• As long as the laser intensity is below the
  threshold for melting in the semiconductor, there
  is no permanent damage to the material.
• There is no ionizing radiation threat, no vacuum
  is required and laser tests are relatively
  inexpensive compared to radiation tests.

21
Conclusion

• Interaction of high-energy ionizing radiation
  with semiconductor material impacts the
  performance of microelectronic circuitry
  operating in space or accelerator environment.
• Effects of interactions with single high-energy
  ionizing particles causes errors in circuit
  operation called Single Event Effects - SEE.
  These errors can cause temporal or permanent
  damage to microelectronic circuits.
• Two techniques were presented, pulsed laser and
  radiation method, both intended to explore and
  characterize the SEE behavior in microelectronics
  circuits.

22
(No Transcript)
23
(No Transcript)
24
(No Transcript)
25
(No Transcript)