Radiation tolerance of electronics

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        E             Department of Physics and Technology                                        University of Bergen




                                                Radiation tolerance of electronics


                                                                    • Radiation effects in semiconducter
                                                                      devices
                                                                    • FEE and radiation concerns
                                                                    • Irradiation tests and results
                                                                    • Conclusion & Outlook




                                                                 Ketil Røed
                                                             10th November 2004




Ketil Røed                                                                                                          1
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        E             Department of Physics and Technology                                                University of Bergen




                                    Radiation effects in semiconducter devices

          • When exposed to radiation Integrated circuits (ICs) can experience
            functional failure

          • A concern for space industry and aircraft instrumentation
             - Atmospheric high energetic neutrons and heavy ions
          • High effort on designing radiation tolerant electronics

          • Down scaling technology (submicron) → increasing problem at Sea level
          • Also a concern for electronics used in experimental high energy physics




Ketil Røed                                                   Radiation effects in semiconductor devices                     2
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        E             Department of Physics and Technology                                                                           University of Bergen




                                     Single Event upset & Nuclear interactions

SEU : Single Event Upsets are a radiation induced errors due to a single
charged particle depositing energy through ionisation of the material.



                                                                                                            Oxide                  Energetic
                  Neutrons & high energetic protons                                                       Insulation                 proton
                                                                                              Drain                        Gate
                  - nuclear interactions                                                                                            Source

                                                                                                                           -
                  - produces a heavy recoil-ion                                                               + -- Si
                                                                                                                       +
                                                                                                                           -
                                                                                                                             +

                                                                                                           - +- + +
                       short range (typ. E < 6 − 10 MeV )                                                        -+
                                                                                                           - +- +
                                                                                                               +
                                                                                                             -
                  - recoil-ion (Qdep > Qcrit ) → SEU
                                                                                                                           Mos Transistor




SRAM based memory circuits (FPGA) are particularly vulnerable
 - Heavy charged particles cause memory elements to change state (SEU)

Ketil Røed                                                   Radiation effects in semiconductor devices                                                3
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                                Front-End Electronics and radiation concerns




          • Challange: FEE 3-5 meters from the interaction point
            → exposed to the radiation created in the collisions

          • No Shielding - will create new unwanted particles (secondaries)


Ketil Røed                                                   Introduction - FEE                     4
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        E             Department of Physics and Technology                             University of Bergen




                                                     FEE and radiation concerns

          • FEE - SRAM based (FPGA) controller devices

          • Chosen over other more radiation hard devices (Flash-based,ASIC)

                      - Flexibillity of programmable SRAM devices (+)

                      - Cost (+)

                      - Known to be sensitive to radiation induced effects (SEU) (−)

Irradiation test are needed to qualify the electroncis for use in radiation
exposed environment
Knowledge of specific radiation environment is necessary


Ketil Røed                                                    Introduction - FEE                         5
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        E             Department of Physics and Technology                                                University of Bergen




                                           Radiation levels in the TPC detector




                                                              Simulated in FLUKA - G.Tsiledakis, GSI


          • Main particles of concern - high-energetic hadrons
                      (E>10-20 MeV, protons, neutrons, pions)→ Nuclear interactions

          • Neutrons of 2<E<20 MeV - contributes less 10% - SEU
          • Proton beams of 30-200 MeV for irradiation tests

Ketil Røed                                                   Radiation effects in semiconductor devices                     6
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        E             Department of Physics and Technology                           University of Bergen




                                                             Irradiation test
Irradiation test carried out at university facilities in Norway and Sweden

The Oslo Cyclotron (UiO)
 - 29 MeV external proton beam


The Svedberg Laboratory ,University of Uppsala
 - 38 & 180 MeV external proton beam



          • DUT
             1 ALTERA APEX 20K400E
             2 XILINX Virtex-II Pro XC2VP7



Ketil Røed                                                       Irradiation tests                     7
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        E             Department of Physics and Technology                                                       University of Bergen




                                                             TSL irradiation test setup
                                            3
                                                                 6        DUT

                                                                          2
                                                                                          4
                                                                                                  1. Experiment DAQ PC
                                                2                                                 2. RCU prototype II card and
                                                                                                     DUT
                                                                                                  3. Alignment laser
                                                                           4
                                                                                                  4. Graphite collimator
                                                                                                  5. Scintillation telescope
                                                                                                     (relative flux monitoring)
                                                                               8              7   6. TFBC for flux and beam
                                                                                                     profile measurement
                                                                                                  7. Beam exit point
                                                                                                  8. Beam line/path


                        1                                         5




Ketil Røed                                                            Irradiation tests                                            8
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        E             Department of Physics and Technology                                                                                                               University of Bergen




                                                             Irradiation test results
          • Device sensitivity characterized by its cross-section
          • Probability of SEUs (statistical of nature)
                                                                                                            -8        Cross-section vs energy for the configuration upsets in shiftregister design
                                                                                                          x10




                                                                             Cross-section [cm^2]
                                                                                                    0.9

                                                                                                    0.8
              No. of SEU No. of SEU
           σ=             =                                                                         0.7

              Flux · Time   Fluence                                                                 0.6

                                                                                                    0.5

                                                                                                    0.4
            Device                                   SEFI (σ) [ cm2 ]                               0.3

            Altera FPGA                     6.0 · 10−9 ± 1.1 · 10−9                                 0.2

                                                                                                    0.1
            Xilinx FPGA                     2.8 · 10−9 ± 0.8 · 10−9                                  0
                                                                                                      0          20       40       60      80     100      120     140     160 180 200
                                                                                                                                                                              Energy [MeV]



                                                                                                                               Altera APEX cross-section

          • Expected hadron flux: 100-400 hadrons/cm 2 s
          • Expected number of SEFI for the whole TPC detector: 3-4 per run

Ketil Røed                                                              Results                                                                                                                      9
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        E             Department of Physics and Technology                                 University of Bergen




                                                        Radiation tolerant design

          • Cross-section result at the limit of what can be tolerated

          • Radiation tolerant schemes are necessary
             - Active partial reconfiguration (prototype card in production)
             - Certain areas of the device can be reconfigured while other areas remain
                          operational and unaffected by the reprogramming
                        - Readout & compare of configuration memory → time tagging of errors
                        - Two scenarios: Continuous or interrupt driven reconfiguration
                        - Different coding techniques


          • Preliminary tests shows that this will reduce the SEU’s to a negliable
            problem



Ketil Røed                                                     Radiation tolerant design                    10
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        E             Department of Physics and Technology                               University of Bergen




                                                             Conclusion & Outlook

          • Radiation induced effects are a concern for the FEE in ALICE

          • But solutions to cope with this concern are being integrated
          • Final irradiation test of complete readout-chain under normal data taking
            conditions
             - Parasitic neutron beam at Uppsala


          • Installation of system and further development and upgrades of radiation
            tolerant firmware




Ketil Røed                                                        Conclusion & Outlook                    11
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        E             Department of Physics and Technology                          University of Bergen




Ketil Røed                                                   Conclusion & Outlook                    12

				
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