1. Cinzia Da Via' - Brunel University UK 10 16 1 ADVANCES IN SEMICONDUCTOR DETECTORS FOR PARTICLE TRACKING IN EXTREME RADIATION ENVIRONMENTS. Cinzia Da Via’, University, UK ADVANCES IN SEMICONDUCTOR DETECTORS FOR PARTICLE TRACKING IN EXTREME RADIATION ENVIRONMENTS. Cinzia Da Via’, Brunel University, UK OUTLINE 1-INTRODUCTION 2-PRESENT STATUS OF RADIATION HARD SILICON DETECTORS UP TO 10 15 n eq /cm 2 3-STRATEGIES FOR SURVIVAL BEYOND 10 15 n eq /cm 2 : aDEVICE GEOMETRY : short collection distance -3D,thin bTEMPERATURE and FORWARD BIAS OPERATION cDEFECT ENGINEERING :O and O 2 4-CONCLUSIONS

2. Cinzia Da Via' - Brunel University UK 10 16 2 INTRODUCTION 27 Km LARGE HADRON COLLIDER CERN - GENEVA Luminosity [cm -2 s -1 ] pp [collisions/s] Bunch Spacing [ns] LHC 2007 10 34 8x10 8 ~25 SLHC ~2015 10 35 10 11 ~12 new physics expected!! new physics expected!! BUT NEED HIGH STATISTICS s 14TeV ~6000 tracks per bunch crossing!!

3. Cinzia Da Via' - Brunel University UK 10 16 3 p p b b H Most probable Higgs channel MOMENTUM RESOLUTION TRACK RECONSTRUCTION b-TAGGING EFFICIENCY PHYSICS REQUIREMENTS ACCURACY OF STANDARD MODEL PARAMETERS ACCURACY OF NEW PHYSICS PARAMETERS SUPERSYMMETRIC PARTICLES EXTRA DIMENSIONS RARE PROCESSES (TOP DECAYS, HIGGS PAIRS ETC) PRECISE MEASUREMENTS OF ~10 SMALLER PITCH SILICON DETECTORS CAN DO IT!!! HIGHER STATISTICS NEEDED FOR GOOD TRACKER ESSENTIAL! Aleph Was it there already??

4. Cinzia Da Via' - Brunel University UK 10 16 4 n  other charged hadrons total RADIATION ENVIRONMENT AT LHC AND SLHC SLHC 210 m 2 of microstrips silicon detectors 1.6x10 16 >85% Ch hadrons Data from CERN-TH/2002-078 Multiple particle environment: NIEL scaling 1 MeV n equivalent Violation observed for oxygen rich materials ~5x10 15 B-LAYER ~4cm ATLAS ~5x10 14

5. Cinzia Da Via' - Brunel University UK 10 16 5 SILICON DETECTORS "NORMALLY " USED IN PARTICLE PHYSICS +V Substrate normally: n-type 4 k  -cm FZ Doping of ~10 12 cm -3 [O] ~10 15 cm -3 [C] ~10 15 cm -3 300  m thick Orientation Incident particle n-type substrate metallised strips oxide W 300  m - - - - - - + + + + + + p-type junctions

6. Cinzia Da Via' - Brunel University UK 10 16 6 RADIATION INDUCED BULK DAMAGE in Si Van Lint 1980 Primary Knock on Atom Displacement threshold in Si: Frenkel pair E~25eV Clusters E~5keV Vacancy Interstitial

7. Cinzia Da Via' - Brunel University UK 10 16 7 EcEc EvEv EiEi V2 (-/0) +Vn E c -0.40eV V2 (=/-) +Vn E c -0.22eV VO - E c - 0.17eV V6V6 C I O I (0/+) E V +0.36eV V2OV2O DLTS spectrum From Cern ROSE RD48 RADIATION INDUCED STABLE DEFECTS IN SILICON Neutron irradiated V,I +  CHARGED DEFECTS ==>N EFF, V BIAS  DEEP TRAPS, RECOMBINATION CENTERS ==>CHARGE LOSS  GENERATION CENTERS==>LEAKAGE CURRENT  VO  VO effective e and h trap  V 2 V 2 O  V 2 and V 2 O deep acceptors contribute to N eff DEFECT KINETICS ( 300K ): IMPURITIES DOPANTS

8. Cinzia Da Via' - Brunel University UK 10 16 8 STANDARD 300  m n-type SILICON at 10 15 n/cm 2 10 years of operation at L=10 34 cm -2 s -1 at R=4 cm EFFECTIVE DRIFT LENGTH Due to charge trapping ~150  m e - ~50  m h SPACE CHARGE-ve N eff (10 13 /cm 3) ~ V FD (5000V)~  TYPE INVERSIONdepletion from n-contact (e-field)  REVERSE ANNEALINGINCREASE OF -ve N eff temp. dep LEACKAGE CURRENTprop to  (I/V ~5x10 -17  PRESENT RESEARCH FOCUSES AT FLUENCES UP TO 1x10 15 n/cm 2  Signal formation  Charge sharing  Speed  Double junction  Charge diffusion  Noise  Thermal runaway Time [y]  Maintenance

9. Cinzia Da Via' - Brunel University UK 10 16 9 MAIN DETECTOR STRATEGIES PROPOSED FOR LIFE ABOVE 10 15 n/cm 2 MORE TO GAIN BY COMBINING TECHNIQUES!  COLLECTION DISTANCE  CCE (trapping)  SPEED  SPACE CHARGE  REVERSE ANNEALLING  CCE (undepletion)  CHARGE SHARING  LEAKAGE CURRENT  DEVICE GEOMETRY 3D, THIN  DEFECT ENGINEERING O, P-TYPE SUBSTRATE  MODE OF OPERATION Temperature, Forward bias OPTIMIZATION OF: STRATEGIES:

10. Cinzia Da Via' - Brunel University UK 10 16 10 EFFECTIVE DRIFT LENGTH L eff =  t x V drift Simulation by S. Watts/Brunel Accepted for publication on NIM Data avalable for neutron andprotons for effective trapping time 220K-300K from Kramberger et al Measured values V L eff at 10 16 proton/cm 2 ~ 20  m electrons ~ 10  m holes 

11. Cinzia Da Via' - Brunel University UK 10 16 11 SIGNAL FORMATION AFTER IRRADIATION Signal ~ q(V x w -V 0 w ) e -th/  h + (V c w -V x w ) e -te/  e ) Simulation by S. Watts Accepted for publication On NIMA e-e-e-e- h+h+h+h+ HOLES DON' T CONTRIBUTE RAMO's THEOREM 0 c x W. Shockley, Jour. Appl.Phys. 9,635 (1938) S. Ramo, Proc. of I.R.E. 27, 584 (1939) Gatti and coworkers Depends on carriers drift length Waiting potential is steeper if contact small compared with detector thickness moreover minimize charge sharing with neighbours due to charge trapping collecting 0.16 A/x Trapping Shaping time  Small contact area  Thin substrate  High e-field Planar device

12. Cinzia Da Via' - Brunel University UK 10 16 12 SHORT COLLECTION DISTANCE: 3D DETECTOR n+n+ p+p+ depletion 50  m + - p n p n  SHORT COLLECTION PATHS 50  m (300  m)  LOW DEPLETION VOLTAGES <10V (60V)  RAPID CHARGE COLLECTION 1-2n(25 ns)  EDGELESS CAPABILITY active edges  LARGE AREA COVERAGE active edges  SUBSTRATE THICKNESS INDEPENDENT :  BIG SIGNALS  X-RAY DETECTION EFFICIENCY for low Z materials IEEE vol46 N4 Aug. 99 S. Parker, C. Kenney 1995 depletion Same Generated Charge!!! + - p+p+ 300  m C=0.2pF n+n+

13. Cinzia Da Via' - Brunel University UK 10 16 13 DEEP REACTIVE ION ETCHING ETCHING TECHNIQUES ELECTROCHEMICAL ETCHING NIMA 487 (2002) 19 ASPECT RATIO = 11:1, 19:1 20:1< ELECTRODE FILLED WITH POLYSILICON fs pulses is cleaner, any substrate Fast, high aspect ratio LASER ABLATION

14. Cinzia Da Via' - Brunel University UK 10 16 14 DETECTOR THICKNESS 121  m 282e noise PREAMP - SHAPING TIME 1  s 200  m PITCH  STRIP TYPE DETECTOR SPEED 1.5ns rise AT 130K 3.5ns rise AT 300K 3D DETECTOR RESULTS before irradiation GAUSSIAN RESPONSE 350 e rms, fast electronic designed at CERN- microelectronics group 200  m pitch detector TO BE PUBLISHED

15. Cinzia Da Via' - Brunel University UK 10 16 15 joined work Brunel, Cern, Hawaii To be published 1x10 15 p/cm 2 (5x10 14 n/cm 2 ) 3D RADIATION RESULTS AT 300K After irradiation FULL DEPLETION BIAS = 105 V AFTER 2x10 15 n/cm 2 SPEED 3.5 ns rise time 40V bias, 300K IEEE Trans on Nucl Sci 48 (2001) 1629 100  m pitch detector NON OXYGENATED

16. Cinzia Da Via' - Brunel University UK 10 16 16 3D CHARGE COLLECTION EFFICINECY After irradiation CCE =61% USING THE INTEGRATED 22-25 KeV X- RAY PULSES FROM A 109 Cd SOURCE COLLECTION FROM p-ELECTRODE 200  m V bias V sig 100  m p n n 134  m V bias V sig n n p 100  m Brunel, CERN, Hawaii to be published Non-Irradiated, 300 K 1 x 10 15 p/cm 2, 300 K No Oxygen Diffusion Reverse Annealed = 40V More on 3D later this morning (P. Roy, 11:30)

17. Cinzia Da Via' - Brunel University UK 10 16 17 MAIN DETECTOR STRATEGIES PROPOSED FOR LIFE ABOVE 10 15 n/cm 2 MORE TO GAIN BY COMBINING TECHNIQUES! COLLECTION DISTANCE CCE (trapping) SPEED SPACE CHARGE REVERSE ANNEALLING CCE (undepletion) CHARGE SHARING DEVICE GEOMETRY 3D, THIN DEFECT ENGINEERING O 2, P-TYPE SUBSTRATE MODE OF OPERATION Temperature, Forward bias OPTIMIZATION OF: STRATEGIES:

18. Cinzia Da Via' - Brunel University UK 10 16 18 At 300K SPACE CHARGE after Irradiation – type inversion AFTER TYPE INVERSION DEPLETION STARTS FROM n + CONTACT - - - - - - - - - - Active volume before irradiation d W Active volume after irradiation p+p+ n+n+n+n+ High field Introduction of radiation induced Deep acceptors Type inversion

19. Cinzia Da Via' - Brunel University UK 10 16 19 THE OXYGEN MIRACLE : ROSE/RD48 REDUCED V FD V FD 3 times 3 times Nucl. Instr. Meth. A 466 (2001) 308 ReducedReverseAnnealingSaturation (2 times)

20. Cinzia Da Via' - Brunel University UK 10 16 20 NEUTRON PROTON PUZZLE COMPETING MECHANISM DUE TO COULOMB INTERACTION MORE POINT DEFECTS WHEN CHARGED PARTICLE IRRADIATION V 2 +0 = V 2 O CONTRIBUTES TO N EFF V+O = VO DOES NOT CONTRINUTE TO N EFF

21. Cinzia Da Via' - Brunel University UK 10 16 21 CHARGE COLLECTION EFFICIENCY AFTER IRRADIATION p-type bulk n on p 0 100 200 300 400 500 600 NIMA 487 (2002) 465-470 25ns electronics 3x10 14 n/cm 2 T=-17 0 C 1 – 3 x 10 14 n/cm 2 V bias NIM A 412 (1998) 238 Q coll = q * d/W  V bias - - - - - d W p+p+ n+n+n+n+ High field UNDEPLETED REGION TRAPPING OXYGEN ONLY DOES NOT HELP! Standard p on n Oxygenated p on n

22. Cinzia Da Via' - Brunel University UK 10 16 22 13  m Spatial resolution CCE   V 250  m Time=10ns ATLAS PIXELS AFTER 10 15 n/cm 2 Nucl Inst Meth A 456 (2001) 217-232 These data curtesy from L. Rossi, unpublished  n + on n  oxygenated  250  m  Multi guard - p-spray COMBINED STRATEGIES!!

23. Cinzia Da Via' - Brunel University UK 10 16 23 Efficiency V bias NIM A 450 (2000) 297 NIM A 440 (2000) 17 LHCb ATLAS n sidep side Resolution [mm] V bias 1-5 x 10 14 n/cm 2 >10 15 n/cm 2 Diffusion due to low field region after type inversion EFFECT ON CHARGE SHARING p+p+ V bias n+n+ p+p+ 3.10 14 n/cm 2 NIMA 426 (1999) 140 SIMULATION S WATTS UNPUBLISHED Double sided strips

24. Cinzia Da Via' - Brunel University UK 10 16 24 SPACE CHARGE Below 200 K N EFF DECREASE WITH T!! Phosphorus doping level energy level occupancy ~ e - E/kT T [K] N eff [cm -3 ] 1x10 14 n/cm 2 > type inverted : -ve SC C Da Via To be published +ve SC N EFF TRAPPING NIM..  CCE INCREASES!  Low leakage current LAZARUS effect  No reverse annealing  High carriers mobility Nucl Inst Meth A 413 (1998) 475 Nucl Inst Meth A 440 (2000) 5

25. Cinzia Da Via' - Brunel University UK 10 16 25 FORWARD BIAS OPERATION AT LOW TEMPERATURE AT LOW TEMPERATURE d undepleted time x  d ~ e E/kT NIM A 440 (2000) 5 Reverse bias Forward bias 0 min 5 min 15 min 30 min V bias CCE % Reverse bias, 700 V Forward bias 90 V T=249K (-24C)  = 10 15 n/cm 2 NIM A 439 (2000) 293. f = 10 15 n/cm 2 T=130K "polarization effect" Higher CCE

26. Cinzia Da Via' - Brunel University UK 10 16 26 CCE % IF IRRADIATION AT 130K: different kinetics! different kinetics! voltage (G. Watkins.Mat. Sci. in Sem. Proc. 3 (2000) 227) Systematic study needed! After annealing at 200K better by 20% Irradiated at 300K For comparison NIM A 476 (2002) 583 1- formation of defects V, I, V n, I n, depending on particles 2- V + and V - observed already at 4.2K after e - irradiation 3- V present in 5 charge states V 2+, V +, V 0, V -, V 2-. 4- the V spectra disappear at : ~70K in n-type low res ~150K in p-type ~200K in high res. material 5- at 200K new spectra appears (V 2, VO) => V migrates!! 6- V migration also possible by ionisation = athermal process 7- I mobile at 4.2K in p-type, ~140-175K in n-type

27. Cinzia Da Via' - Brunel University UK 10 16 27 NEW DEFECT ENGINEERED MATERIAL: O-DIMER TO CONTROL CHARGE TRAPPING SiSi Si OiOiOiOi OiOiOiOi OXYGEN DIMER HIGH TEMPERATURE 60 Co g IRRADIATION AT T > 350 0 C OXYGEN ATOMS BECOMES MOBILE AND START TO CLUSTER QUASI CHEMICAL REACTIONS: V+O i => VO i VO i + O i => VO 2i I + VO 2i => O 2i Theory predicts VO 2 is NEUTRAL! NIM B 186 (2002) 111 SiSi OiOiOiOi OXYGEN INTERSTITIAL DLTS shows VO suppressed Less trapping! D= dimerized p=proton irradiated 1.1 x10 11 p/cm 2

28. Cinzia Da Via' - Brunel University UK 10 16 28 WE KNOW HOW TO: 1- HAVE A SHORT COLLECTION DISTANCE + COLLECTING e -  optimise signal formation  spatial resolution  speed 2- CONTROL THE SPACE CHARGE  power dissipation (noise)  CCE  spatial resolution 3- CONTROL CHARGE TRAPPING  CCE  spatial resolution SUMMARY device structure 3D – THIN (small pitch) Defect engineering operational mode Temperature, forward bias Defect engineering p-type operational mode MORE GAIN BY COMBINING TECHNIQUES!!! USING :

29. Cinzia Da Via' - Brunel University UK 10 16 29 CONCLUSIONS THE COMBINATION OF:  ENGINEERED SILICON (oxygen enriched), p-type substrate  INNOVATIVE SHORT DRIFT LENGTH GEOMETRIES (3D, thin)  OPERATIONAL CONDITION (temperature, forward bias) COULD PROVIDE THE RADIATION TOLERANCE OF SILICON NEEDED TO GUARANTEE THE OPERATION OF PARTICLE TRACKERS AT 10 16 n/cm 2  ELECTRONICS PLAYING A KEY ROLE!! Recently formed CERN R&D (RD50) will explore several of the proposed strategies Interest expressed by LHC elastic scattering, Luminosity monitor collaborations to use existing technologies like 3Dand cryogenic silicon.

30. Cinzia Da Via' - Brunel University UK 10 16 30 ACKNOWLEDGEMENTS Luca Casagrande/ Roma GianLuigi Casse/Liverpool Alex Chilingarov /Lancaster Paula Collins/Cern Leo Rossi /Atlas pixel Mahfuzur Rahman/Glasgow Angela Kok, Anna Karpenko,Gennaro Ruggiero/ Brunel Erik Heijne/Cern Sherwood Parker/Hawaii Steve Watts /Brunel

31. Cinzia Da Via' - Brunel University UK 10 16 31 “The most important thing in science is imagination” A. Einstein