Cinzia Da Via' - Brunel University UK 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 n eq /cm 2 3-STRATEGIES FOR SURVIVAL BEYOND n eq /cm 2 : aDEVICE GEOMETRY : short collection distance -3D,thin bTEMPERATURE and FORWARD BIAS OPERATION cDEFECT ENGINEERING :O and O 2 4-CONCLUSIONS

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

Cinzia Da Via' - Brunel University UK 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??

Cinzia Da Via' - Brunel University UK 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/ Multiple particle environment: NIEL scaling 1 MeV n equivalent Violation observed for oxygen rich materials ~5x10 15 B-LAYER ~4cm ATLAS ~5x10 14

Cinzia Da Via' - Brunel University UK 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  m thick Orientation Incident particle n-type substrate metallised strips oxide W 300  m p-type junctions

Cinzia Da Via' - Brunel University UK 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

Cinzia Da Via' - Brunel University UK EcEc EvEv EiEi V2 (-/0) +Vn E c -0.40eV V2 (=/-) +Vn E c -0.22eV VO - E c eV 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

Cinzia Da Via' - Brunel University UK STANDARD 300  m n-type SILICON at 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 ~5x  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

Cinzia Da Via' - Brunel University UK MAIN DETECTOR STRATEGIES PROPOSED FOR LIFE ABOVE 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:

Cinzia Da Via' - Brunel University UK 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 proton/cm 2 ~ 20  m electrons ~ 10  m holes 

Cinzia Da Via' - Brunel University UK 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

Cinzia Da Via' - Brunel University UK 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+

Cinzia Da Via' - Brunel University UK 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

Cinzia Da Via' - Brunel University UK 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

Cinzia Da Via' - Brunel University UK 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)  m pitch detector NON OXYGENATED

Cinzia Da Via' - Brunel University UK D CHARGE COLLECTION EFFICINECY After irradiation CCE =61% USING THE INTEGRATED 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 p/cm 2, 300 K No Oxygen Diffusion Reverse Annealed = 40V More on 3D later this morning (P. Roy, 11:30)

Cinzia Da Via' - Brunel University UK MAIN DETECTOR STRATEGIES PROPOSED FOR LIFE ABOVE 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:

Cinzia Da Via' - Brunel University UK 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

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

Cinzia Da Via' - Brunel University UK 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

Cinzia Da Via' - Brunel University UK CHARGE COLLECTION EFFICIENCY AFTER IRRADIATION p-type bulk n on p NIMA 487 (2002) ns electronics 3x10 14 n/cm 2 T=-17 0 C 1 – 3 x 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

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

Cinzia Da Via' - Brunel University UK 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 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 n/cm 2 NIMA 426 (1999) 140 SIMULATION S WATTS UNPUBLISHED Double sided strips

Cinzia Da Via' - Brunel University UK 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

Cinzia Da Via' - Brunel University UK 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)  = n/cm 2 NIM A 439 (2000) 293. f = n/cm 2 T=130K "polarization effect" Higher CCE

Cinzia Da Via' - Brunel University UK 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) 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 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, ~ K in n-type

Cinzia Da Via' - Brunel University UK NEW DEFECT ENGINEERED MATERIAL: O-DIMER TO CONTROL CHARGE TRAPPING SiSi Si OiOiOiOi OiOiOiOi OXYGEN DIMER HIGH TEMPERATURE 60 Co g IRRADIATION AT T > 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

Cinzia Da Via' - Brunel University UK 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 :

Cinzia Da Via' - Brunel University UK 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 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.

Cinzia Da Via' - Brunel University UK 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

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