Mauro Citterio ICATPP Como – 10/4/2011 1

Energy Distribution in Hostile Environment:

Power Converters and Devices

Mauro Citterioon behalf of the INFN-APOLLO project

Mauro Citterio ICATPP Como – 10/4/2011 2

INDEX

• The ATLAS LAr Calorimeter System …. a test case

• The Proposed Power Distribution for an Upgraded LAr System

• Characteristics of Power MOSFETs under irradiation

• - exposed to ionizing radiation (gamma 60Co)

• - exposed to heavy ions (75Br at 155 MeV)

• - exposed to protons (216 MeV)

• Conclusions

Mauro Citterio ICATPP Como – 10/4/2011 3

The ATLAS experiment

LAr barrel calorimeter

The power distribution and conversion scheme in the detector area

Mauro Citterio ICATPP Como – 10/4/2011 4

The required qualification doses for this application are:

4.5 x 104 rad and 2 x 1012 particles/cm2 (> 20 MeV)

Ten times higher for Hi-LHC scenario (70 safety factor)!!!

ATLAS Experiment: Lar Barrel CalorimeterDetails of the Front End Electronics and Main Power Converter

Mauro Citterio ICATPP Como – 10/4/2011 5

ATLAS Experiment: Present StatusLAr Calorimeter Front-End Board (FEB) Power Distribution

19 LDO regulators/FEB

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CRATE

280 Vdc

MainDC/DC

Converter

Card #3

POLLDO Converter

POLLDO Converter

POLLDO Converter

Card #2

POLLDO Converter

POLLDO Converter

POLLDO Converter

Card #1

POLniPOL Converter

POLniPOL Converter

POLniPOL Converter

Regulated DC bus

POL Converter with high step-down ratioCharacteristics:• Main isolated converter with N+1 redundancy• High DC bus voltage (12V or other)• Distributed Non-Isolated Point of Load Converters (niPOL) with high step-down ratio

Proposed Power Supply Distribution Scheme for a LAr Upgrade

MORE INFO TAKE A LOOKAT THE DEDICATED POSTER !!!

Mauro Citterio ICATPP Como – 10/4/2011 7

The Main Converter

Q1

Q2

Q3

Q4

T1 C

o

C4

L

Vi

n

Vou

t

+-C

3

C2

C1

T2

T3

iT

2

iL

T4

+

+

+

+Vout = 12V

Switched In Line Converter SILC- Required Mosfet Voltage

Breakdown: ~ 200 Volt or higher- Mosfets, diodes and controller must

be qualified against radiation

The Point of Load

S1

S2

S3

S4

L1

Co

RC1

L2

Uin Uo

+

-UC

1

+

-

D<50% Uo = UinD/2

POL Specifications:Input voltage: Ug = 12 VOutput voltage: Uo = 2.5 VOutput current: Io = 3AOperating frequency: fs = 1 MHz

350 nH air core inductors

Critical Elements for a LAr Upgrades

Mauro Citterio ICATPP Como – 10/4/2011 8

Power Mosfets exposed to gamma rays

Devices under test:

30V STP80NF03L-04

30V LR7843

200V IRF630

Used doses:

I 1600 Gray

II 3200 Gray

III 5890 Gray

IV 9600 Gray

Measurements :

Breakdown Voltage @ VGS=-10V

Threshold Voltage @ VDS=5V

ON Characteristic @ VGS=10V

Gate Leakage @ VDS=10V

For each type of device 20 samples were tested, 5 for each dose value(tested at the ENEA Calliope Test

Facility)

Mauro Citterio ICATPP Como – 10/4/2011 9

30 V Mosfet: STP80NF03L-04

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30 V Mosfet: LR7843

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200 V Mosfet: IRF630

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Mosfet Exposed to Heavy Ions.The SEE framework

N+

Drain

P +

N +

P _

GateSource

N_

Body

N+ N+

Drain

P +

N +

P _

GateSource

N_

Body

N+

Destructive Single Event Effects in Power MOSFETS (tested at INFN Catania)

Single Event Burnout Single Event Gate Rupture

Mauro Citterio ICATPP Como – 10/4/2011 13

The SEE experimental set-up

Fast Sampling Oscilloscope

Parameter Analyzer

N+

Drain

P +

N +

P _

GateSource

N_

Body

N+

Cg

Cd

50 W

50 W

1 MW1 MW

Vgs

Impacting Ion DUT

Vds

0 500 1000 1500 2000-2.0

-1.5

-1.0

-0.5

0

Time [s]

Gat

e Le

akag

e C

urre

nt [

A ]

20 40 60 80 100 120

0

5

1

15

Time [ns]

Cur

rent

[mA

]

The current pulses

The IGSS evolution during irradiation

Mauro Citterio ICATPP Como – 10/4/2011 14

0 10 30 400

0.5

1

1.5

2

2.5

x 1011

Charge [pC]

50 100 1508

10

12

14

16

Vds [V]

Cha

rge

[pC

]

Vds

20 40 60 80 100 120

0

0.5

1

1.5

0

0.5

1

1.5

0

Time [ns]

Cur

rent

[mA

]

10 20 30 40 10 20 30 40

0.5

1

1.5

2

2.5

3

3.5

4

4.5

5x 1010

Charge [pC]

The SEE analysisTIME DOMAIN WAVEFORMS SCATTER PLOT

NUMERICAL INTEGRATION

Γ-LIKE DISTRIBUTION

FUNCTION PARAMETERS EXTRACTION

MEAN CHARGE vs BIAS VOLTAGE Γ-LIKE DISTRIBUTION FUNCTION

Mauro Citterio ICATPP Como – 10/4/2011 15

The SEE experimental results

Devise TID Bias Conditions during Irradiation

Drain Damage Gate Damage

D21 0Gy Vds=20V-110V vgs=-2V Vds=100V-110V Vds=100V-110VD22 0Gy Vds=20V-120V vgs=-6V Vds=110V-120V Vds=100V-110VD06 1600Gy Vds=20V-70V vgs=-2V Vds=60V-70V Vds=60V-70VD10 3200Gy Vds=20V-50V vgs=-6V Vds=40V-50V Vds=40V-50VD14 5600Gy Vds=20V-55V vgs=-6V Vds=50V-55V Vds=40V-50VD16 5600Gy Vds=20V-50V vgs=-6V Vds=45V-50V Vds=40V-45VD17 9600Gy Vds=20V-45V vgs=-6V Vds=40V-45V Vds=40V-45V

The increase of the ϒ-dose causes a reduction of the critical bias condition at which drain and gate damages

appear

200 V Mosfet: IRF630

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0 20 40 60 80 100 120 140 160 180 200

0

0.05

0.1

0.15

0.2

0.25

0.3

0.35

0.4

Time [ns]

Cur

rent

[mA

]

0 20 40 60 80 100 120 140 160 180 200

0

5

10

15

20

25

30

35

Time [ns]

Cur

rent

[mA

]

The SEE experimental results

Two different sensitive areas

The SEB current pulse

D21 0Gy Vds=110V Vgs=-2V

D21 0Gy Vds=110V Vgs=-2V

20 30 40 50 60 70 80 90 100

1.4

1.6

1.8

2.0

2.2

2.4

2.6

2.8

Vds [V]

Cha

rge

[pC

]

Mean charge vs Vds

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0 20 40 60 80 100 120 140 160 180 200-20

0

20

40

60

80

100

120

Time [ns]

Cur

rent

[A

]

D21 0GyD10 3200GyD14 5600GyD17 9600Gy

The SEE experimental resultsScatter-plot Vds=50V

The increase of the ϒ-dose causes a widening of the current pulses

Mauro Citterio ICATPP Como – 10/4/2011 18

Characterization requires that an SEB circumvention method be utilized

SEB characterization produces a cross-sectional area curve as a function of LET for a fixed VDS and VGS. Generally SEB is not sensitive to changes in the gate bias, VGS. However, the VGS bias shall be sufficient to bias the DUT in an “off” state (a few volts below

VTH), allowing for total dose effects that may reduce the VTH.

Mosfet Exposed to ProtonsSEB characterization

The only difference in the test set-up was that the current probe

was on the Mosfet Source

Mauro Citterio ICATPP Como – 10/4/2011 19

Mosfet Exposed to ProtonsThe results are still preliminary. Only the 200V Mosfets (IRF 630, samples from two different manufacturers) were exposed

Proton energy: 216 MeV (facility at Massachusetts General Hospital, Boston)Ionizing Dose: < 30 Krads

An “absolute” cross section will require the knowldege of the area of the Mosfet die which is unknown.

10-12

10-11

10-10

10-9

10-8

10-7

182 184 186 188 190 192 194 196

IRF630 - ST

Cro

ss S

ectio

n [c

m-2

]

VDS [Volt]

10-12

10-11

10-10

10-9

10-8

10-7

175 180 185 190 190 195

IRF630 - International Rectifier

Cro

ss S

ectio

n [c

m-2

]

VDS [Volt]

Mauro Citterio ICATPP Como – 10/4/2011 20

The number of SEB events recorded at each VDS was small less then 30 events for the ST

less than 150 events for the IR devices

Large statistical errors affect the measurements The cross section at VDS = 150 V (“de-rated” operating voltage)

can not be properly estimated Dependence from manufacturer

“Knee” not well defined

To effectively qualify the devices for 10 years of operation at Hi-LHC, the cross section has to be of the order of 10-17/ cm2, which puts the

failure rate at <1 for 10 years of operation

Proton irradiation campaigns with increased fluences and more samples are planned.

Work still in progress ……………..

Mosfet Exposed to Protons

Mauro Citterio ICATPP Como – 10/4/2011 21

Distributed Power Architecture has been proposed Main converter (SILC topology)

Point of load converter (IBDV topology)

Critical selcction of components to proper withstand radiation Controller, Driver and Isolator FPGA for overall monitoring

MOSFETS

MOSFETS, both for main converter and POL have been selected and tested

Gamma ray Heavy ions

Protons

Some results are encouraging, however more systematic validation is on-going

Novel devices based on SiC and GaN, are also under investigation

Conclusions