CCT radiation Assurance radiation dans un projet : Effets de dose ionisante (TID)

Transcription

1 CCT radiation Assurance radiation dans un projet : Effets de dose ionisante (TID) Renaud Mangeret EADS ASTRIUM SAS Toulouse 27 Mars 2006 Page 1 CCT Radiation & composants - 27 Mars 2006

2 Radiation : why do we care? customer Radiation expert customer Program manager Program manager Page 2 CCT Radiation & composants - 27 Mars 2006

3 Short Course Out line Introduction Basic concepts Constraint linked to space radiation environment Total ionising Dose Level (TDL) calculation TID degradation mechanisms Device Total ionising Dose Sensitivity (TDS) determination TID and Radiation Hardness Assurance (RHA) Conclusion Page 3 CCT Radiation & composants - 27 Mars 2006

4 Introduction Underestimation of radiation induced degradation may endanger any space mission Among all radiation induced degradations, Total Ionising Dose (TID) has to be considered TID may degrade electronics and materials performances TID Radiation Hardness Assurance (RHA) process has to be implemented Page 4 CCT Radiation & composants - 27 Mars 2006

5 Introduction RHA consists of all activities undertaken to ensure that the electronics and materials of a space system perform to their design specifications after exposure to the space radiation environment TID Radiation Hardness Assurance (RHA) process is based on the comparison between calculated in flight TID level (TDL) and, TID sensitivity (TDS) of the element under study. Radiation Hardness Assurance goes beyond the piece part level Page 5 CCT Radiation & composants - 27 Mars 2006

6 Short Course Out line Introduction Basic concepts Constraint linked to space radiation environment Total ionising Dose Level (TDL) calculation TID degradation mechanisms Device Total ionising Dose Sensitivity (TDS) determination TID and Radiation Hardness Assurance (RHA) Conclusion Page 6 CCT Radiation & composants - 27 Mars 2006

7 Definition and units Basic concepts TID is the measure for the quantity of radiation deposited through ionisation mechanism at a specific location, in a specific material "Standard" unit is the rad(material) regardless that SI unit is the Gray(material) Rad = Radiation Absorbed Dose Gray (Gy) = J/ kg (S.I.), 1 Gy = 100 Rad The dose rate is the amount of TID deposited per unit of time example : rad(si)/s or rad(si)/hour Page 7 CCT Radiation & composants - 27 Mars 2006

8 Short Course Out line Introduction Basic concepts Constraint linked to space radiation environment Total ionising Dose Level (TDL) calculation TID degradation mechanisms Device Total ionising Dose Sensitivity (TDS) determination TID and Radiation Hardness Assurance (RHA) Conclusion Page 8 CCT Radiation & composants - 27 Mars 2006

9 Space radiation environment Space radiation environment of concern has to be defined in the earliest phase of the program Particles of concern for TID are protons and electrons They may transit through the solar system or be trapped by the Earth magnetic field These create the radiation belts Page 9 CCT Radiation & composants - 27 Mars 2006

10 Radiation environment : mission related requirements Different types of space mission in terms of orbit and duration Major risks not associated to the same constituent of the radiation environment, then, not to the same effect Required confidence level may vary with the mission type Identification of the different mission Launcher : no concern related to TID Telecommunication Earth observation / Constellation / Space station Scientific mission (interplanetary) Page 10 CCT Radiation & composants - 27 Mars 2006

11 Radiation environment : system related requirements Different elements of a space system may be radiation sensitive Electronics Ionising and Non Ionising Dose (displacement damage), Single Event Effects (SEE) Materials, optics Ionising and Non Ionising Dose Solar generator mainly Non Ionising Dose Detectors Ionising and Non Ionising Dose (displacement damage), Single Event Effects Page 11 CCT Radiation & composants - 27 Mars 2006

12 Short Course Out line Introduction Basic concepts Constraint linked to space radiation environment Total ionising Dose Level (TDL) calculation TID degradation mechanisms Device Total ionising Dose Sensitivity (TDS) determination TID and Radiation Hardness Assurance (RHA) Conclusion Page 12 CCT Radiation & composants - 27 Mars 2006

13 Total ionising Dose Level (TDL) calculation Robustness of a device/subsystem/system evidenced thanks to comparison between expected in flight level (TDL) and TID Sensitivity (TDS) of the concerned device TDL may be estimated by Monte Carlo technique (NOVICE, GEANT4 ) - Accurate but time consuming by Ray Tracing technique (NOVICE, SYSTEMA/DOSRAD ) - Less accurate but more "industrial" Ray tracing technique needs as inputs spacecraft/equipment/device geometry TID dose-depth curve Page 13 CCT Radiation & composants - 27 Mars 2006

14 Total ionising Dose Level (TDL) calculation Dose-depth curve definition Should be preferentially usable by any sub-contractor (e.g. compatible with their tools) Should be adapted to orbit type Electron rich orbit vs proton rich orbit Should be provided as a standard for Silicon target with Aluminium shielding shape for electronics May be provided for particular cases with Other target/shielding shape materials Specific thickness range Page 14 CCT Radiation & composants - 27 Mars 2006

15 Total ionising Dose Level (TDL) calculation Dose [krad(si)] 1,E+05 1,E+04 1,E+03 1,E+02 1,E+01 1,E+00 1,E-01 1,0E+09 1,0E+08 1,0E+07 1,0E+06 1,0E+05 1,0E+04 1,0E+03 1,0E+02 1,0E+01 Solid Sphere dose-depth curve, GEO orbit LEO solid sphere Dose-depth Curve Dose [rad(si)] electrons trapped protons flare protons total Solid sphere Al. thickness (g/cm 2 ) Solid sphere Al. thickness (mm) protons bremsstrahlung électrons total Page 15 CCT Radiation & composants - 27 Mars 2006

16 Total ionising Dose Level (TDL) calculation Shielding shape used as a standard is a sphere Solid sphere or shell sphere Such shielding shape as to be used in conjunction with the adapted ray tracing method So called NORM or SLANT method r r r r α Page 16 CCT Radiation & composants - 27 Mars 2006

17 Total ionising Dose Level (TDL) calculation Ray tracing vs reverse Monte Carlo calculation ["Comparaison des méthodologies de détermination de dose déposée sur HOTBIRD", T. Carrière, EADS ASTRIUM internal report, ] ["Impact of material properties and shielding structures on dose level calculation", R. Mangeret, CNES funded study, internal ASTRIUM SAS report, 2001.] Total ionising dose calculation on electronics dies Inside different packages For given equipment/satellite geometries For various radiation environment Page 17 CCT Radiation & composants - 27 Mars 2006

18 Total ionising Dose Level (TDL) calculation TID Ray Tracing / MonteCarlo [%] Solid Sphere (slant) Shell Sphere (slant) Parts Shell Sphere (norm) Device package + equip t + satellite SC-N SP-SL Monte Carlo Pack. ratio TID ratio TID TID (SC-N) / (MC) [krad(si)] (SP-SL) / (MC) [krad(si)] [krad(si)] GEO ORBIT P1 P2 P3 1,549 1,251 1,231 26,1 15,1 28,5 1,263 0,965 0,811 21,5 11,6 18,6 16,7 11,9 24,0 P4 1,514 3,5 1,470 3,4 2,3 GEO orbit, device package + Equipment, satellite is a box GTO ORBIT P1 P2 P3 1,435 1,172 1, ,0 100,0 168,0 1,180 0,986 0, ,0 122,0 112,0 84,9 128,0 P4 0,937 30,4 0,937 30,4 32,5 Page 18 CCT Radiation & composants - 27 Mars 2006

19 Total ionising Dose Level (TDL) calculation No problem for proton rich orbits (LEO, scientific) Solid sphere to be used for ray tracing For electron rich orbit (ex : GEO, GALILEO) comparison with NOVICE Monte carlo calculation Solid Sphere + SLANT, slight underestimation possible Shell Sphere + NORM, overestimates generally the total dose level as calculated by MC technique Both give a realistic estimation of received TID Shell Sphere + SLANT : catastrophic underestimation Page 19 CCT Radiation & composants - 27 Mars 2006

20 Total ionising Dose Level (TDL) calculation Impact of the tool on dose-depth curve GEOSYNCHRONOUS ORBIT, SOLID SPHERE 1,E+06 Shieldose TID [rad(si)] 1,E+05 1,E+04 NOVICE 1D NOVICE 3D Shieldose2 1,E SP Al (mm) Page 20 CCT Radiation & composants - 27 Mars 2006

21 Short course Out line Introduction Basic concepts Constraint linked to space radiation environment Total ionising Dose Level (TDL) calculation TID degradation mechanisms Device Total ionising Dose Sensitivity (TDS) determination TID and Radiation Hardness Assurance (RHA) Conclusion Page 21 CCT Radiation & composants - 27 Mars 2006

22 TID degradation mechanisms TID effects on electronic devices TID response on bipolar microcircuits Main effect at transistor level : reduction of gain Δ(1/β)=K.D N with N#1at a low level of dose. Degradations of PNP transistors are generally more serious (low initial gain), "lateral" PNP being the most critical case. Integrated circuit degradation may be complex due to interaction between individual transistors degradation (increase of bias & offset currents, increase of offset voltages ) Page 22 CCT Radiation & composants - 27 Mars 2006

23 TID degradation mechanisms TID response of bipolar devices Enhanced Low Dose Rate Sensitivity (ELDRS) Enhanced degradation at a given TID level when device irradiated at low dose rate Evidenced on bipolar based integrated circuit, strongly suggested for discrete transistors Page 23 CCT Radiation & composants - 27 Mars 2006

24 TID degradation mechanisms Device type is 2N5551 transistor (STM), single lot 1,2E-02 1,0E-02 Delta (1/hfe) 8,0E-03 6,0E-03 4,0E-03 2,0E-03 HDR LDR linear (LDR) linear (HDR) 0,0E Dose [Krad(Si)] Page 24 CCT Radiation & composants - 27 Mars 2006

25 TID degradation mechanisms TID response of MOS microcircuits charges trapped in the oxide (oxide traps) Charges trapped on the interface (interface traps) ΔVth = ΔVot + ΔVit - Positive charges: ΔVth < 0 - Negative charges: ΔVth > 0 At transistor level : V GSth drift At integrated circuit level, increased operating and stand by currents, degradation of input logic level - Rebound effect to be considered Page 25 CCT Radiation & composants - 27 Mars 2006

26 TID degradation mechanisms Dose rate effects in MOS devices 0 t irr ( 1 ) = D DR 1 t RTanneal = t irr ( 2 ) t irr ( 1 ) Time (Log t irr ( 2 ) = D DR 2 Space dose rate Lab dose rate i+ RT di ti t HT _ anneal Lab dose rate i+ High di ti Temp l Irradiation at Room temperature under bias Annealing at Room temperature under bias Annealing at High temperature under bias High dose rate generally worst case for MOS devices Page 26 CCT Radiation & composants - 27 Mars 2006

27 TID degradation mechanisms TID effects in materials Organic materials : chemical reactions initiated Cross-linking, chain scission, formation of gaseous byproducts Transparent materials (optics) Darkening (colour centres) Index of refraction changes Mechanical and structural changes For external materials, UV degradation (surface) has to be taken into account Page 27 CCT Radiation & composants - 27 Mars 2006

28 Short course Out line Introduction Basic concepts Constraint linked to space radiation environment Total ionising Dose Level (TDL) calculation TID degradation mechanisms Device Total ionising Dose Sensitivity (TDS) determination TID and Radiation Hardness Assurance (RHA) Conclusion Page 28 CCT Radiation & composants - 27 Mars 2006

29 Device TID Sensitivity (TDS) determination TID Device Sensitivity (TDS) is determined thanks to : Manufacturer guarantee (TID hardened devices) Technological assessment TID ground testing TDS validity is ensured by complying to TID Radiation Hardness Assurance (RHA) rules Manufacturer guarantee should rely on data set relevant for space application (ELDRS issue) Technological assessment to be based on degradation mechanisms already presented TID ground testing should be adapted to space issues Page 29 CCT Radiation & composants - 27 Mars 2006

30 Device TID Sensitivity (TDS) determination TID testing issue Objective is to forecast the behaviour of devices regarding TID flight constraint In most cases, simulating space radiation environment at ground level is not possible Testing should mimic or bound the flight usage TID testing likely to be implemented with 60 Co source Page 30 CCT Radiation & composants - 27 Mars 2006

31 Device TID Sensitivity (TDS) determination TID testing issue Existing specifications for electronics are ESA SCC issue 2 MIL STD 883D TM Both specification are (off course) significantly different Specification provides with guidelines to insure test conditions reproducibility and test results comparison Insure test adequacy regarding flight conditions, based on the technical state of the art. Material TID testing is particularly tough and is in most of the cases performed on case by case bases. Page 31 CCT Radiation & composants - 27 Mars 2006

32 Device TID Sensitivity (TDS) determination Two approaches may be used for TDS determination "worst case" approach : TID level at which the worst case device of the worst case tested lot exceeds its parametric or functional limits "Statistical" approach : "K factor" / 3-sigma Then, TDS may corresponds to the first parametric "out of specification" level or to application related Worst Case Analysis (WCA) Page 32 CCT Radiation & composants - 27 Mars 2006

33 Short course Out line Introduction Basic concepts Constraint linked to space radiation environment Total ionising Dose Level (TDL) calculation TID degradation mechanisms Device Total ionising Dose Sensitivity (TDS) determination TID and Radiation Hardness Assurance (RHA) Conclusion Page 33 CCT Radiation & composants - 27 Mars 2006

34 TID and RHA RHA methodologies for TID & electronics Main used method is to categorise devices regarding TID constraint Radiation Design Margin (RDM) is defined as being the ratio between TDS and TDL Several empirical methods exists for RDM determination - Design Margin Breakpoint - Part categorisation Criteria Page 34 CCT Radiation & composants - 27 Mars 2006

35 TID and RHA Examples of industrial RHA approaches regarding TID EADS ASTRIUM : DMBP related approach A major point is that for RDM value to be valid, both TDL and TDS have to be valid ALCATEL SPACE : "RADLAT" approach Page 35 CCT Radiation & composants - 27 Mars 2006

36 TID and RHA TID mitigation Some countermeasure may have to be implemented in the course of a space program Several possibilities exist for TID mitigation Shielding at device or equipment level To refine TDL with more accurate calculation (MC) Equipment / system re-design Replacement of concerned device by a radiation hardened product Cold redundancies Page 36 CCT Radiation & composants - 27 Mars 2006

37 Conclusion From ESA upcoming ECSS-E specification "There is no space system in which radiation effects can be neglected" TID is one of these radiation effects, then Degradation mechanisms at sensitive element level should be understood TDL has to be determined with an adequate degree of precision TDS has to be evaluated in accordance with state of the art radiation knowledge Risks have to be lowered as much as possible, in conformance with mission requirements, by help of a RHA process Page 37 CCT Radiation & composants - 27 Mars 2006