Production of the ATLAS Pixel Detector Modules
Vertex2004, Como, September 15th 2004
Claudia Gemme INFN and University of Genova
on behalf of the ATLAS Pixel Collaboration
Production of the ATLAS Pixel Detector Modules
Vertex2004, Como, September 15th 2004
Claudia Gemme INFN and University of Genova
on behalf of the ATLAS Pixel Collaboration
22C.Gemme - ATLAS Pixel Modules production
The ATLAS Pixel Detector The ATLAS Pixel Detector It is the innermost part of the
silicon vertex tracker .
It consists of two parts:
Barrel: 3 layers (12 cm, 10 cm and 5 cm radii);
End-cap: 3+3 forward-backward disks.
Only the ‘reduced’ layout is approved (2 layers +2+2 disks), due to budget reason: the 3-layer system may be approved soon.
Going from 3 to 2-layer system means a reduction of 30%.
~1.7 m2 of sensitive area with 67M (barrel) + 13M (disks) channels.
Total dose 50 Mrad on the middle layer in 10 years of LHC.
Installation foreseen mid-2006~1850 mm~1850 mm
~380 mm~380 mm
33C.Gemme - ATLAS Pixel Modules production
Pixel ModulesPixel Modules• Modules are the basic building elements of the detector (1456 in the barrel, 288 in the end-caps).
• Each module has an active area of 16.4 mm x 60.8 mm.
•The sensitive area is read out by 16 FE chips which are controlled by a Module Controller Chip (MCC). Each FE read-outs 2880 channels organized in a matrix of 18x160 channels. Each pixel has a 400m x 50m area.
•A Flex-Hybrid circuit glued on the sensor backside provides the signal/power routing. the signal routing between the 16 FE chips and the MCC.
•A pigtail (only for barrel modules) + Al/Cu wire bundle connect flex hybrid to patch panels at either end of pixel detector. Pigtail is the only difference between barrel and disks modules.Schematic cross
section (through here)
sensor
Flex HybridMCC
FE chipFE chip
Wirebondings
bumps
44C.Gemme - ATLAS Pixel Modules production
Work packages (PPT) da sostitire con una frase o schema piu’
semplice ( e in inglese) Work packages (PPT) da sostitire con una frase o schema piu’
semplice ( e in inglese) Operazione Quantità Stato Deadline Tempo rimanente
Bump bonding: 2005/09/29 72 sett
AMS 1500 66 ~20/sett
IZM 600 33
Bare module test: 2005/10/15 74 sett
Milano 1100 57 ~15/sett
NRW 1000 37
Assembly: 2005/10/15 74 sett
Genova 800 36 ~10/sett
LBL 400
NRW 800
Flex module test: 2005/10/30 76 sett.
CPPM 100 0
Genova 600 36 ~8 sett.
LBL 400 16
NRW 900 24
Fornituradi chip da LBL
Target 20/sett.
Target >10/sett.
55C.Gemme - ATLAS Pixel Modules production
Production Status of basic components:Sensors
Electronics
Flex Hybrids
66C.Gemme - ATLAS Pixel Modules production
Sensors (necessary? Ci passi veloce…5”)
Sensors (necessary? Ci passi veloce…5”)
Baseline design:n+ pixel in n-bulk
material:Moderated p-spray
isolation.Bias grid to allow testing
before module assembly.Oxygenated silicon to
improve radiation resistance and increase allowable time to room temperature (for repair/upgrades).
Two vendors: Cis and Tesla
3 tiles wafer, n side
Charge collection efficiency (meas) n+ implants and bias grid
77C.Gemme - ATLAS Pixel Modules production
Sensors ProductionSensors Production• Two vendors have produced the sensor tiles:
• CiS delivered 1121 good tiles during 2002/03. All of them have been tested and 1094 are fine. A replacement of 55 tiles is on-going.
• Tesla (now ON Semiconductor) began its deliveries in April 04. After an initial yield problem, now it is ending its 900 tiles contract. The only problem for us is the lower fraction of wafers with 3 good tiles (24% ON).
Rifare il totale?Rifare il totale?
88C.Gemme - ATLAS Pixel Modules production
Sensors ProductionSensors Production• Performances are very similar between ON and CIS.
• We have the possibility (option expiring Feb05) to order other tiles if the 3-layers project will be definitevely approved.
• Testing is done in 4 labs and 100 tiles/months could be easily achieved thus ending the test of the delivered tiles in ~6 months time.
99C.Gemme - ATLAS Pixel Modules production
On-detector ElectronicsOn-detector Electronics
On-detector chips are fabricated in 0.25m DSM by IBM. Used circuit library with special layout rules for radiation tolerance.
MCC: decode data/cmd signals, generate control signal for 16 FEs, collect data from FEs and accumulate in FIFOs, check event consistency, build module event and sends to DAQ, handle errors.
FE chip: control 18x160 pixels. Amplify sensor signal, on-chip data buffering in EOC FIFOs until trigger signal arrives, send data on serial link to MCC.
FE chip
senso
r
FE chip MCC
Optical Driver (VDC)
OpticalReceiver (DORIC)
power
HV bias
1m100m
LVDS controlLVDS data out bump bonds
optical
……....
1010C.Gemme - ATLAS Pixel Modules production
MCC-I2.1MCC-I2.1• After one year of experience with modules of first generation DSM, we
have received back in May03 the second generation of chips (MCCI2).
• Some problems have been easily fixed and respin of wafers not completely processed has produced chips good for production (MCCI2.1) .
• Out of 6 wafers we have obtained 2666 good MCC-I2 with a yield of 83% (1744 needed in the 3-layers detector).
1133
44 22
55667788
1111C.Gemme - ATLAS Pixel Modules production
FEI3: Wafer statusFEI3: Wafer status The first engeneering run (6 wafers) was delivered in Dic 03. After that, we received three production runs (48 wafers each). Another
two are expected in the next months, before the end of the year. A complete test on each chip is performed at the wafer level (LBL and
Bonn). Testing speed is coping well with deliveries. The mean yield on wafer is 79% (but varies from 60 to 92%,sembra migliorare ultimamente )
1212C.Gemme - ATLAS Pixel Modules production
FEI3: Good dies statusFEI3: Good dies status An electric test and a visual inspection are performed after wafer
bumping deposition, thinning and dicing on the singled dies. Yield of electric test is very high: 99.4% (however on modules would
mean 90% yield);Yield of visual inspection is 88% (mainly damaged bumps); this step is
critical as debris can damage the chip or the sensor after flip-chipping. Considering a yield
of 79% at wafer level and ~ 85% at chip level, having 288 chips on each wafer, we get 11-12 modules/wafer.
IBM will deliverd a total of 246 wafers thus sufficient for more than 2700 modules,i.e enough for the 3-layers detector.
1313C.Gemme - ATLAS Pixel Modules production
Flex HybridFlex Hybrid
2000 delivered and tested. 1000 more delivery foreseen
Oct 1st. SMD are mounted on the kapton,
then the Flex is glued on a frame that will be used for further tests. This frame makes easy the module handling until it is cut to be loaded on its final support.
1414C.Gemme - ATLAS Pixel Modules production
Having parts, how we build and qualify a ‘good’ module?
1515C.Gemme - ATLAS Pixel Modules production
Module Assembly and Testing (da animare)
Module Assembly and Testing (da animare)
Flex+MCCGenova/Bonn/LBL
Bare moduleAMS/IZM
PigtailBonn
MCC operation+ connectivity
Flex+MCC+Pigtailgluing PT
wire bonding
Elco connectivity
HV+voltage drop+peel test
Bare module test
Flex modulegluing
wire bonding/ pullpotting
Assemblytest
Burn-inPost burn-in
test
Cold full characterization
Sorting for loading
16 FEs SensorON/Cis
1122
33
44
1616C.Gemme - ATLAS Pixel Modules production
IZM – PbSnAMS - In
• Hybridization is done by AMS and IZM. It consists of bump deposition on wafer, thinning and cutting FE-wafers (in US), cutting of sensor tiles and flip-chip of 1 tile with 16 FEs.•Techniques are different but electrical results and yield are comparable.•Tests on the bare module before further assembling are:
A X-rays scan to verify the quality of bumps;A visual inspection and IV curve;An electrical test contacting each chip individually. In case of failure, a chip reworking can be tried (i.e. chip substitution).
•Total test time: 2h/module.
Bare Modules (si deve capire che e’ lo step 1)Bare Modules (si deve capire che e’ lo step 1)
16 thinned FEs, ~50k bumps
Sensor
60.8mm
16.4
mm
1717C.Gemme - ATLAS Pixel Modules production
QA check using X-raysQA check using X-rays Yield on x-ray is very high.
Few chips (HOW?) not attached and one rotated in AMS.
1818C.Gemme - ATLAS Pixel Modules production
Yield bare modules Yield bare modules
Yield is (90+21)/134=83% and (71+10)/87=93% (IZM)Losses in reworking is 7/28 (AMS) and 2/12 (IZM)(There are a few accepted re-worked bare modules that failed later. some bare module rejection after rework will be needed. Should be order 2%)
Main problems in the table
Bare modules - FE-I3 delivered
0
200
400
600
800
1000
1200
1400
1600
1800
Aug-03 Dec-03 Apr-04 Aug-04 Dec-04 Apr-05 Aug-05 Dec-05 Apr-06
time
nu
mb
er
of
mo
du
les
IZM-FEI3
AMS_FEI3Total FE-I3
2-layer3-layer
bare modules tested
0
200
400
600
800
1000
1200
1400
1600
1800
2000
2200
Aug-03 Dec-03 Apr-04 Aug-04 Dec-04 Apr-05 Aug-05 Dec-05 Apr-06
time
num
ber o
f mod
ules
virgin accepted
total acceptedtrashed
2-layer3-layer
Delivered bare modules 122 74Bump problems 1 5VDDA short 24 3VDD short 3 3bad sensor 5damaged during probing 1No answer to analog injection 0Others 0bad 34 31! 12REPAIRED 22 7Total good bare modules 110 69
AMS IZM
Rifare I Rifare I grafici piu’ chiarigrafici piu’ chiariEventualmente Eventualmente Aggiungere la Aggiungere la frazione di AVDDfrazione di AVDDRispetto alle Rispetto alle failure totalifailure totaliCome nella slide Come nella slide 3232
1919C.Gemme - ATLAS Pixel Modules production
DVDD/AVDD shortsDVDD/AVDD shorts• VDDA/DVDD shorts represents the first cause of failure (80%??).• VDDA/DVDD shorts show up as about 300 mA current at power up (instead of
few mA) on the analog (mainly) or digital supply.• They are due to silicon fragments which get trapped between the bumps and
damage the electronics when pressure is applied during the flip-chipping.• These fragments are due to back-side chipping during dicing.• These particles are hard to be recognized during the visual inspection and
moreover they could reach the bumps even during the shipments/handling. • Some attempts to reduce the problem have been tested (changing dicing
parameters and/or polishing wafers, improving cleaning before flip-chipping), but for the time being we should live with this problem (i.e. rework).
Fragment onthe electronic chip (reworking possible)
or on the sensor (reworking not possible).
2020C.Gemme - ATLAS Pixel Modules production
Flex Hybrid Assembling (si deve capire che e’ lo step 2)
Flex Hybrid Assembling (si deve capire che e’ lo step 2)
Step Time
Gluing, bonding, pull test MCC 60’/flex
Test Flex+MCC 45’/flex
Gluing pigtail 90’/flex
Bonding pigtail 30’/flex
Test Flex+MCC+pigtail 30’/flex
Critical point is the MCC bonding as, due to the geometrical limitations, the bonding loop can not be standard.
Using an Al 25um wire we get a large fraction of peel off or lift (63%) even if obtained with a sufficiently high mean force (12g).
Alternative solutions are under study:2 bondings, 17 um each per pad;Gold ball bonding (not much experience)…
2121C.Gemme - ATLAS Pixel Modules production
Module Assembling (si deve capire che e’ lo step 3)Module Assembling (si deve capire che e’ lo step 3)
Step TimeGluing Flex Hybrid on module
1 day/4 modules
Bow 15’/module
Wire-bonding FE/ pull test 60’/module
Potting 60’/module
Assembling modules is a complex operation but we have a large experience so that in each lab 10-15 modules can be assembled per week (expected rate from bump-bonding firm is 30 modules/week).
For each module a pull- test is done: 20 bondings are pulled in order to qualify the quality. We still have some not-stick bondings when cleaning is not perfect.
Inserire un plot con DGRID forceInserire un plot con DGRID force
2222C.Gemme - ATLAS Pixel Modules production
PottingPotting Potting e’ fatto sui bonding del pigtail,
MCC, HV e dei FE. Reworking di questo potting e’
possibile.
Aggiungere test di risonanaza e perche’ abbiamo deciso di pottare solo I piedi (vedi articolo Amanda)
2323C.Gemme - ATLAS Pixel Modules production
Test Flex Modules (si deve capire che e’ lo step 4)Test Flex Modules (si deve capire che e’ lo step 4)
Step Time Comments
Electrical test after assembling 180’/module If the test is passed, bondings are potted
Burn-in 2 gg/group of modules
8 thermal cycles (-30C,30C) in environmental chamber + power cycles
Electrical test after burn-in 120’/module
Final characterization at operational temperature (-10C)
8-12h/module This test will produce final data for ranking
Up to now module testing is the longest operation: even if all the tests are completely automatized, ~10 modules/week/lab is the maximum speed (this means ~40-50 modules/week in the collaboration).
2424C.Gemme - ATLAS Pixel Modules production
FEI3 modules yieldFEI3 modules yield
Yield of Flex module assembling/burn-in and testing is ~95%.
2525C.Gemme - ATLAS Pixel Modules production
Module problemsModule problems
Rate of low quality modules
-0,20
0,00
0,20
0,40
0,60
0,80
1,00
1,20
15/03
/04
29/03
/04
12/04
/04
26/04
/04
10/05
/04
24/05
/04
07/06
/04
21/06
/04
Time
Fra
ctio
n
Defects
Merged bumps
Defectivecolumn pairs
Unsuccessfulreworking
AMS IZMAssembled modules 76Damaged during assembly 1Increased leakage current 1Elco connector faults 2VDDA shorts 2ToT problems 3XCK/DVDD shorts 1MCC faults 1Flex faults 1REPAIRED 4
Problems mainly showed up in the very first electrical tests. No infant mortality has been observed so far after/during the burn-in. We have observed few modules in which the AVDD/DVDD shorts
appeared after few hours of electrical functioning. The main problems are (see table): AVDD/DVDD shorts not observed
at the bare module level, MCC faults, Elco connector faults. Some of these problems will be reduced as we have had more tests
on the components before module assembling; other are intrinsic and will not decrease.
2626C.Gemme - ATLAS Pixel Modules production
Merged bumps (questo forse e’ un po’ troppo specifico…)
Merged bumps (questo forse e’ un po’ troppo specifico…)
Sometimes merged bumps have been observed on the edge columns of AMS modules.
This kind of defect have been traced to an excessive depth of the shim in some Genova test boards.
Add a small picture with a Add a small picture with a threshold scan threshold scan for a channel to explain what for a channel to explain what the plot is.the plot is.
2727C.Gemme - ATLAS Pixel Modules production
Source scan (questa e la seguente si possono evitare)Source scan (questa e la seguente si possono evitare)
Source SCAN with source located on the module centre (distance source-module ~ 3cm, source: 241Am, 10 mCi).
If the source stays on the module centre, the scan takes 4hours/200kevs. If the source is moved on the scanned chip, it takes 2-3 min/200Kevs.
2828C.Gemme - ATLAS Pixel Modules production
Fe 6 Fe 7Fe 6 Fe 7
Fe 9 Fe 8Fe 9 Fe 8
2929C.Gemme - ATLAS Pixel Modules production
PDB & raw data server (Necessary?)PDB & raw data server (Necessary?) Penso sia necessario dire che e’ necessario e che lo abbiamo, niente
di piu’.
3030C.Gemme - ATLAS Pixel Modules production
ConclusionsConclusions Module Production has started: components are there
and assembling and testing are fine. We still have some critical step that we are better
investigating (MCC wire-bonding, dealing with dies back-side chipping to reduce reworking).
Data analysis for sorting is to be finalized soon. Emphasis is now moving on the next steps: loading on
local supports!
Sector front side: 3+3 modules
Stave: 13 modules
3131C.Gemme - ATLAS Pixel Modules production
FE-I3 Bare modulesFE-I3 Bare modules
0
20
40
60
80
100
120
140
Dec-03 Jan-04 Feb-04 Mar-04 Apr-04 May-04Month
Bar
e M
od
ule
s (c
um
ula
tive
)
All Reworked + bad bad FE-I3/16
3232C.Gemme - ATLAS Pixel Modules production
YieldsYields
AMS chip probing: Electrical: 99.4 +/- 0.1%, Visual: 86%
Bare Modules
AMS defect rate
-0,050,000,050,100,150,200,250,300,350,40
01/02
/04
15/02
/04
29/02
/04
14/03
/04
28/03
/04
11/04
/04
25/04
/04
09/05
/04
23/05
/04
06/06
/04
20/06
/04
Time
Rat
e VDDAshorts
Allfailures
3333C.Gemme - ATLAS Pixel Modules production
FE-I3 ModulesFE-I3 Modules
0
10
20
30
40
50
60
70
Feb-04 Mar-04 Apr-04 May-04
Month
FE
-I3
Fu
ll M
od
ule
s (
cu
mu
lati
ve
)All modules Used+Trashed Trashed
3434C.Gemme - ATLAS Pixel Modules production
Module qualityModule quality
Rate of low quality modules
-0,20
0,00
0,20
0,40
0,60
0,80
1,00
1,20
15/03
/04
29/03
/04
12/04
/04
26/04
/04
10/05
/04
24/05
/04
07/06
/04
21/06
/04
Time
Fra
ctio
n
Defects
Merged bumps
Defectivecolumn pairs
Unsuccessfulreworking
3535C.Gemme - ATLAS Pixel Modules production
510903: leakage current510903: leakage current