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Robert Szczygieł IFJ PANSPIE 2005
Radiation hardness of the mixed-mode ASIC’s dedicated for the future high energy physics
experiments
Introduction
Radiation hardness of ABCD - the readout chip
for silicon strip detectors
Radiation hardness of DTMROC - the readout chip
for straw tube detectors
Conclusions
Robert Szczygieł IFJ PANSPIE 2005
Introduction
High Energy Physics experiments require radiation hard mixed-mode and digital ASICs for fast detector data processing.
ATLAS detector – 150 mln sensors to be read out every 25 ns.
Robert Szczygieł IFJ PANSPIE 2005
ATLAS – one of the experiments build on LHC.
Introduction
Pixel sensors:- 140 mln
Silicon strips:- 6.4 mln
Straw sensors:- 0.37 mln
Radiation up to 134 Mrad and 2.3·1015 neq
/cm2 for 10 years of operation
Robert Szczygieł IFJ PANSPIE 2005
Introduction
Radiation effects in semiconductor devices - TID
Total irradiation dose (TID) effects – charge accumulation
in SiO2 and at the Si/SiO
2 interface, new interface states,
new recombination centers
MOS threshold voltage shift carrier mobility degradation leakage currents - device and chip level bipolar transistor ϐ degradation transistor noise increase increased parameters' spread (important in multichannel
ASIC's)
At the circuit level: analogue parameters (gain, BW, offset, etc.) are modified, reduced digital logic speed, changed power consumption.
Robert Szczygieł IFJ PANSPIE 2005
Introduction
Radiation effects in semiconductor devices - SEE
Single event effects (SEE) – charge generated by single particle
single event transients (SET) in combinational logic single event upset (SEU) in memory elements single event gate rupture (SEGR) single event burnout (SEBO)
The SEE lead to functional errors or device destruction.
Radiation effects depend on: technology type of radiation device biasing temperature
Robert Szczygieł IFJ PANSPIE 2005
Introduction
Submicron technologies.
MOS transistors' Vth
shift
negligible due to the charge removal from the gate oxide (tunneling effect).
Leakage currents in NMOS transistors still important.
Leakage currents can be eliminated by using enclosed layout transistors.
Drawbacks: increased size, limited W/L ratio
Robert Szczygieł IFJ PANSPIE 2005
Introduction
Requirements for readout ASIC's in the ATLAS
Radiation hard – should work reliably for 10 years in highly radioactive environment (10-100 times higher than for space)
Low power – cooling systems introduced in the detector volume disturb the particle traces
Minimal area – granularity of the sensors in the tracking detectors is very high
Multichannel – providing data processing for a number of sensors
Functionality – should provide data compression via trigger system (store all the data from the sensor until the validating “trigger” signal arrives)
Robert Szczygieł IFJ PANSPIE 2005
ABCD chip
ABCD – silicon strip detectors readout
Fast front-end: 20 ns peaking timeLow noise: 1500 el @ 20 pF CLClock: 40 MHzData retention: 3.2 µs
6.4 mln channels in the system.
Power: < 0.5 WArea: 51 mm2
Transistors: 250 000TID: 10 Mrad
2·1014 neq
/cm2
Robert Szczygieł IFJ PANSPIE 2005
ABCD chipABCD Radiation hardness
radiation hardened 0.8 µm BiCMOS SOI technology; ELTs not necessary, low number of SEE
programmable biasing for analogue channels and internal calibration
DACs for discriminator threshold correction in all 128 analogue channels
speed margins for digital logic (expected 100 % slow down after irradiation)
precise internal synchronization byanalogue simulations
redundant clock and data inputs
bypassing scheme
Robert Szczygieł IFJ PANSPIE 2005
ABCD chip
Bypassing scheme
Any damaged chip in the module can be bypassed.
Robert Szczygieł IFJ PANSPIE 2005
ABCD chip
Two different types of memories used (result of power/area optimization)-> impossible to balance the clock tree on the chip level-> analogue simulations for all the corners (10 sets of irradiation
models)
ABCD internal synchronization
Robert Szczygieł IFJ PANSPIE 2005
ABCD chip
ABCD irradiation tests
24 GeV proton beam, CERN PS 200 MeV pions, PSI Villingen neutrons, nuclear reactor at Ljubljana 10 keV X-rays, CERN
Test results
no catastrophic failures analogue channels biased properly increased noise in the analogue channels increased channel threshold spread, corrected with DACs digital logic working at speed > 40 MHz logic speed down by a factor of ~2 SEU rate negligible comparing to noise
ABCD fulfills the ATLAS Semiconductor Tracker specification.
Robert Szczygieł IFJ PANSPIE 2005
DTMROC chip
DTMROC – straw tube detectors readout
Clock: 40 MHzTID: 7 Mrad
3.5·1014 neq
/cm2
370 000 channels in the system.
Area: 26 mm2
Data retention: 6.4 µsTransistors: 500 000
Robert Szczygieł IFJ PANSPIE 2005
DTMROC chipDTMROC Radiation hardness
submicron 0.25 µm CMOS technology; negligible MOS Vth
shift (15 mV NMOS, -30 mV PMOS @ 10 Mrad)
enclosed layout transistors (ELT) in analogue and digital part (dedicated standard cell library)
triplicated control logic and registers with SEU counter
parity checking for all the registers
watchdog circuits
DLL monitoring
command decoder designed to accept any input data; it rejects any invalid input data and recovers after predefined time to minimize the probability of loosing the synchronization with the rest of the system
Robert Szczygieł IFJ PANSPIE 2005
DTMROC chip
SEU protection areas in DTMROC
Only the parts of the logic necessary for keeping the data processing efficiency within the experiment specification are protected.
Robert Szczygieł IFJ PANSPIE 2005
DTMROC chip
Triplicated 1-bit register with self-recovery and SEU output
V. Ryjov
Robert Szczygieł IFJ PANSPIE 2005
ABCD chip
DTMROC irradiation tests
1.33 MeV gamma (Co-60), Saclay 24 GeV protons, CERN PS neutrons, reactor in Ljubljana 60 keV X-ray, CERN
Test results
10 % DAC range increased, no linearity degradation no speed degradation power consumption not modified SEU in critical parts eliminated by redundancy SEU crossection in the registers 0.8-1.2·1014 cm2
DTMROC fulfills the ATLAS Transition Radiation Tracker specification.
Robert Szczygieł IFJ PANSPIE 2005
Conclusions
Conclusions
1. ASIC's dedicated to the readout of the tracking detectors in future HEP experiments have to be characterized by low power, fast data processing and very high radiation hardness.
2. The radiation hardness of the ASIC's is achieved by using the radhard or submicron technology and dedicated design elements.
3. Radhard design has been demonstrated on the examples of two chips, ABCD and DTMROC.
4. Both ASIC's fulfill the specifications. They have been produced, and are being installed in the ATLAS experiment.
Robert Szczygieł IFJ PANSPIE 2005
Conclusions
Francis AnghinolfiGerit MeddelerDaniel LamarraWładysław DąbrowskiJan KapłonVladimir RyjovMitch NewcomerNandor DressnandtRick Van BergPaul KeenerHenry WilliamsTor Ekenberg
Thanks to ABCD and DTMROC design teams: