11th Workshop on Electronics for LHC and future Experiments, 12- 16 Sept. 2005
Heidelberg, Germany
Pixel Detectors
for Tracking and their Spin-off in
Imaging Applications
Norbert Wermes
Bonn University
LECC, 15.09.2005
Outline
chip
1. Hybrid Pixels
sensor
„state of the art“ technology
Æ tracking @ LHC
Æ spin offs
Æ SLHC Æ new ideas !?
2. (Semi) Monolithic Pixels
the „future“
ÆILC driven
Æspin-offs
CMOS Active Pixels
a-Si:H
DEPFET Pixels
SOI Pixels
Bonn, Sept.5.-8.
not covered: CCD development for ILC
LECC-Heidelberg, 15.06.2004
Norbert Wermes, Bonn
1
State of the art …
10 yrs R&D Æ full detector
Hybrid Pixel Detectors
Bump & Flip-Chip Technology
semiconductor pixel detector
pixel contact
ohmic contact
detector substrates
- Si
Æ HEP
- (diamond)
- (GaAs)
- CdTe Æ Imaging
- CZT
ATLAS (1.8 m2) my bias
CMS (1 m2)
ALICE (0.24 m2)
(LHCb for RICH)
flip-chip
bump bonding
pixel readout chip
large (~m2) detectors are being built
LECC-Heidelberg, 15.06.2004
NA60 (0.017 m2, running)
Norbert Wermes, Bonn
2
Hybrid Pixels / LHC environment
…. with particle fluence:
3
10
5000
1000
500
type inversion
100
50
10
5
102
≈ 600 V
101
1014cm-2
"p-type"
n-type
1
10-1
100
[M.Moll: Data: R. Wunstorf, PhD thesis 1992, Uni Hamburg]
0
10
1
10
2
10
Φeq [ 10 cm ]
12
-2
3
10
| Neff | [ 1011 cm-3 ]
Udep [V] (d = 300μm)
Change of Depletion Voltage Vdep
(Neff)
10-1
2
1
• “Type inversion”: Neff changes from positive to
negative (Space Charge Sign Inversion)
before inversion
p+ n n+
p+ p n+
1
2
3
NIEL >1015 neq/cm2
dose > 500 kGy
SLHC = LHC x 10
from M. Moll
after inversion
LECC-Heidelberg, 15.06.2004
Norbert Wermes, Bonn
3
Hybrid Pixels / Sensors
ƒ pixel geometry
ALICE
Æ 50 µm x 400/425 µm (ATLAS, ALICE,NA60)
Æ 100 µm x 150 µm (CMS)
Æ thickness: 250 - 300 µm, ALICE: 200 µm
ƒ
CMS
n+ pixels on n- oxygenated Si
Æ after type inversion can operate
partially depleted
Æ bias grid to be able to test detectors
before assembly
Æ homogeneous charge collection
2
1
ATLAS
charge collection eff.
LECC-Heidelberg, 15.06.2004
bias grid
Norbert Wermes, Bonn
4
Hybrid Pixels / FE-electronics
Front End Chips
• operation @ 40 MHz
• zero suppression in every pixel
• data buffering until trigger (µs later)
7.4 mm
• low power (~ 28-90 µW / pixel)
• e.g. ATLAS: amplitude via pulse width (ToT)
• time walk for small signals
• noise ~160e- (on module)
• thres. dispersion ~600e (< 100e after tuning)
• x-talk < 1%
• thinned to 150 µm – 200 µm
ATLAS
11
mm
linear discharge
⇒ good columnar
ToT
architecture
1 mip
threshold
poor man’s
analog R/O
different injected charges
ATLAS
• several chip generations (1996-2003)
radsoft: CMOS, BiCMOS (3-4 prototypes)
radhard @ 1015neq /cm2 , SEU tolerant design
• DMILL (yield too low), several iterations
• 0.25 µm technology, several iterations
• production finished (ATLAS: 250 wafers = 72000 IC)
• chip yield on wafer ~ 50% - 85%
LECC-Heidelberg, 15.06.2004
Norbert Wermes, Bonn
5
FE-chip wafer yields (0.25 µm CMOS)
ATLAS (FE-I3)
yields
before
thinning
82%
11 x 7.4 mm2
180µm thick
LECC-Heidelberg, 15.06.2004
CMS (ROC)
> 80%
7.9 x 9.8 mm2
200µm thick
ALICE (SPD-RO)
51%
13.5 x 15.8 mm2
150µm thick
Norbert Wermes, Bonn
6
ATLAS FE-I3: Pixel-Layout (Analogue Part)
400 μm
7-bit tune-DAC for local
threshold adjustment
Bonding-pad
SEU-tolerant RAM cells
for pixel configuration
bits
50 μm
Active voltage drop
compensation
Preamplifier
5-bit DAC – global
threshold
whole chip: 3.5 M transistors
LECC-Heidelberg, 15.06.2004
RAM write/read
control
Auto-tune
from I. Peric
Norbert Wermes, Bonn
7
Important / in-time threshold & efficiency
set threshold e.g. to 4000 ± 200 e(lowest possible ~1500 e-)
In-time threshold (Δt<20ns): 5200 ± 200 e⇒ overdrive = 1200 ± 200 e-
(achieved in irradiated assemblies)
zero time walk line
for large signals
timewalk
Î in-time efficiency ~99% wanted and achieved !
LECC-Heidelberg, 15.06.2004
Norbert Wermes, Bonn
8
Chip Architecture (animated)
ƒ 40 MHz Gray coded clock
transmitted to all cells
ƒ Pixel circuit detects
sensor signal (analog)
and generates hit
information (digital)
ƒ Hit data with time
stamps are temporary
stored in end of column
buffers outside pixel
matrix
ƒ The buffers monitor the
age of each hit data and
delete hits when no
trigger coincidence
occurs
ƒ Hits having their time
stamps (“expire date”)
coincident with LV1
trigger are readout.
ƒ Analogue circuits
ƒ Digital readout
circuits
ƒ Registers used to
store configuration
bits
ƒ Time information
ƒ Trigger
from I. Peric
LECC-Heidelberg, 15.06.2004
Norbert Wermes, Bonn
9
Hybrid Pixels / hybridization
Solder
Indium
1. bumping
2. flip-chip
(wafer scale)
BARE module
LECC-Heidelberg, 15.06.2004
Norbert Wermes, Bonn
10
Hybrid Pixels / hybridization
bumping & flip chip of thinned bumped (!) chips (~ 180µm, 8“ wafers) 9
ATLAS (IZM) / ALICE (VTT)
ATLASIndium
(AMS) / CMS (PSI w. reflow) Solder (PbSn)
50 µm
In
reflow
50 µm
Indium (lift-off) photo AMS, Rome
photo AMS, Rome
• „lift off“ + thermo compression
• bumps „soft“ + „flat“ (~6 µm)
- module handling more „touchy“
+ can be done „in-house“
LECC-Heidelberg, 15.06.2004
50 µm
photo IZM, Berlin
• electroplating + reflow
• automated wafer scale process @ vendor
• bumps „strong“ and „taller“ (~25 µm)
• very high yield if process steps well controlled
Norbert Wermes, Bonn
11
Pixel Cross-Section
50 μm
Sensor
bumps
(PbSn)
6 metal
layers
FE Chip
ATLAS
courtesy IZM
LECC-Heidelberg, 15.06.2004
Norbert Wermes, Bonn
12
Hybrid Pixels / BARE module yield (ATLAS)
60% of produced @ IZM & AMS
- ~ 2x20 modules/week
- rework fraction : 10% - 15%
- rework efficiency:
solder ~100%, indium ~80%
- module reject fraction:
solder ~ 1%, indium ~14%
0.1%
total need (3 layers): 1744 + spares
total order @ bump vendors: ~2500
delivered (31.8.2005): 1500
fully assembled (today): ~1250
from J. Weingarten
LECC-Heidelberg, 15.06.2004
Norbert Wermes, Bonn
13
Hybrid Pixels / pixel module
MCC
flex-hybrid
sensor
FE-chip
pigtail
out to
opto interface
bare
d
e
l
b
m
e
s
as
LECC-Heidelberg, 15.06.2004
Norbert Wermes, Bonn
14
Hybrid Pixels / modules
ALICE
1 sensor, 5 chips
12.8 x 7.0 cm2
ATLAS
1 sensor
16 chips
6.4 x 2.1 cm2
6.4 x 2.0 cm2
CMS (1 sensor, 16 chips)
LECC-Heidelberg, 15.06.2004
Norbert Wermes, Bonn
15
Hybrid Pixels / module performance
Production Test Sequence
1. digital functionality
- injected vs. measured hits
- injected vs. measured ToT
- hits vs. column pair enable
2. analog functionality
- hits vs. charge: threshold, noise meas., threshold tuning, crosstalk, timewalk
- ToT vs. charge: ToT calibration & tuning
3. source test Am, 60 keV gamma
- bump quality
- dead channels
- test ToT calibration
4. thermal cycling and tests at -10°C (ATLAS operating conditions)
LECC-Heidelberg, 15.06.2004
Norbert Wermes, Bonn
16
Hybrid Pixels / threshold & noise
tuned thresholds,
dispersion < 100 e
σ =
60e-
noise ≈ 190 e
mean = 190eRMS = 28efrom J. Weingarten
LECC-Heidelberg, 15.06.2004
Norbert Wermes, Bonn
17
Hybrid Pixels / source scan (241Am)
passive components on FLEX
passive components on FLEX
module burn-in tests
241Am
γ - spectrum
(no clustering)
typically
high pixel efficiency
~ few dead / 46080
(open/short)
amplitude (via ToT)
LECC-Heidelberg, 15.06.2004
from J. Weingarten
Norbert Wermes, Bonn
18
Hybrid Pixels / module quality yield
Ranking levels:
b-layer, layer 1, layer 2
overall ranking
total: 1225
ranking based on:
- inefficient pixel
- sensor quality
- noise performance
- threshold tuning
- rebonding
- BareModule rework
failed: 120;
10%
b-layer
layer2: 256;
21%
layer2
layer1
b-layer: 668;
54%
layer2
failed
layer1: 180;
15%
layer1
b-layer
from J. Weingarten
LECC-Heidelberg, 15.06.2004
Norbert Wermes, Bonn
19
Hybrid Pixels / full pixel system tests
BiStave in cool box
“stand alone” and “module in system” difference
distribution of
• final power supplies
• patch-panels
threshold differences
• final cables w original lengths
PP0 with optoboard
noise differences
type3 cables
Wiener LV supply
σ = 12e
σ = 50e
ISEG HV supply
from J. Weingarten
LECC-Heidelberg, 15.06.2004
Norbert Wermes, Bonn
20
Main Issue for ATLAS and CMS: Irradiation
target: 10 years LHC ≅ 1015 neq/cm2 ≅ 500 kGy
•
•
•
•
•
Si sensors:
FE chips:
glue:
mechanics:
cooling:
depletion voltage and leakage currents
threshold shifts & parasitic transistors
becomes hard and brittle
material performance degrades
larger capacity needed to cool more power
Î intensive irradiation and test beam program over years
including dedicated high intensity beams with LHC like
rates and timing structure
LECC-Heidelberg, 15.06.2004
Norbert Wermes, Bonn
21
Irradiated Modules after 1 MGy (2xLHC)
before irradiation
noise
thr
<ENC> = 152e
σthr = 40e
LECC-Heidelberg, 15.06.2004
ATLAS
20yrs
LHC
lab
measm’ts
after 1 MGy
noise
thr
<ENC> = 182e
σthr = 127e
Norbert Wermes, Bonn
22
Hybrid Pixels / Depletion Depth after 10 yrs
Track position from beam
telescope
600 kGy
depleted
non depleted
1/N*dN/dQ
18000e
0.07
0.06
Particle Track
200 V
400 V
600 V
dN/dh
The maximum track segment depth
corresponds to an effective depletion depth
(threshold dependent)
800
700
600
0.05
500
0.04
400
0.03
300
0.02
200
ATLAS
0.01
0
100
0
5
10
15
20
25
30
35
Cluster charge, all clusters
40
cluster charge
LECC-Heidelberg, 15.06.2004
200 V
400 V
600 V
45
50
ke
ATLAS
0
50
100
150
200
spurtiefe
250
300
350
track depth (µm)
Norbert Wermes, Bonn
depth (μm)
23
Hybrid Pixels / Trapping after 10 yrs LHC
Also done using tilted tracks.
For non-irradiated sensors,the
collected charge is uniform along
the depth.
The charge yield yield as a
function of the depth can be
translated, via the drift
velocity, in a carrier lifetime:
Charge (arbitrary units)
Charge Vs Depth
1
0.8
τe = 4.1 ± 0.3 ± 0.5 ns
notirradiated
0.6
Irradiated
0.4
0.2
0
0
Bonn3, irradiated, 600 V (run1857)
ATLAS
50
Bonn9, not irradiated, 150 V (run 1333)
100
150
mean CCE after 10 yrs LHC ~ 80%
(with LHC type annealing scenario)
due to 1. bias grid, 2. trapping
200
250
Track depth ( μ m)
from A. Andreazza
LECC-Heidelberg, 15.06.2004
Norbert Wermes, Bonn
24
Spatial resolution in irradiated assemblies
before irradiation
(100 incl.)
after 60 Mrad
(100 incl.)
ATLAS
from A. Andreazza
LECC-Heidelberg, 15.06.2004
Norbert Wermes, Bonn
25
In-time track efficiency in irradiated assemblies
efficiency
before irradiation
after 600 kGy
efficiency
no hit
eff.
99.9%
no hit 0.1%
out of time 0%
plateau 14ns
1
0.8
out of time
0.7%
plateau
masked
0.6
9.7 ns
~10-4
25ns
25ns
0.4
97.8%
1.5%
0.2
0
ATLAS
0
10
20
30
40
50
efficiency vs time, standard
60
70
ns
large in-time plateau for efficency margin
improved also by late hit duplication feature in FE-chip
LECC-Heidelberg, 15.06.2004
Norbert Wermes, Bonn
26
Hybrid Pixels / Support Structures
ALICE
ATLAS
ATLAS
-minimal X0 “C-C” structures
-cooling (pumped C3F8: bp -250)
-T < -60 C to limit damage
from irradiation
-power dissipation: ~100W/stave
(ATLAS)
~15kW/detector
LECC-Heidelberg, 15.06.2004
Norbert Wermes, Bonn
27
Hybrid Pixels / Support Structure
carbon-carbon
space frame
ATLAS
~1.8 m2, 80 Mpix
LECC-Heidelberg, 15.06.2004
carbon-fibre
structure
CMS
~1m2, 50 Mpix
carbon-fibre
structure
ALICE
~0.24 m2, 10 Mpix
Norbert Wermes, Bonn
28
Main Issue for ALICE: minimal material
In central HI collisions up to 8000 charged particles/ |η| are expected.
~80 hits/cm2
Primary charged particles in a central event
from P. Riedler
radiation levels only ~ 5 kGy, 6x1012 neq / cm2
Æ operation at room temperature possible !
LECC-Heidelberg, 15.06.2004
Norbert Wermes, Bonn
29
Main Issue for ALICE: minimal material
ALICE
very light weight Carbon Fibre
support structure (200µm,0.1 X0)
sensor
200µm
IC
150µm
cooling (C4F10) @ RT
0.3% X0
total X0 per layer ~ 0.9%
(ATLAS, CMS > 2%)
(PHYNOX tubes, wall 40µm)
LECC-Heidelberg, 15.06.2004
Norbert Wermes, Bonn
30
NA60: LHC pixels put to test
from M. Keil
8 (4 chip) + 8 (8 chip) planes Æ 12 tracking points in 2.5 T dipole
ALICE1/LHCb pixel chip (@ 120 kGy)
sensors operated through type inversion
and through partial type inversion
107 ions/s → single hit rate up to 200 kHz
for comparison: ATLAS B-Layer: 20 kHz
LECC-Heidelberg, 15.06.2004
Norbert Wermes, Bonn
31
NA60: LHC pixels put to test
from M. Keil
addition of 4 planes Æ 16 tracking points in 2.5 T dipole
2004 pA running @ 2x109 p/burst
1 interaction / 25 ns
Î upgrade to ATLAS production modules
LECC-Heidelberg, 15.06.2004
Norbert Wermes, Bonn
32
Hybrid Pixels / NA60 results
p-on-n type pixels become
p-on-p after type inversion
Lowering the bias voltage
leaves a larger and larger
undepleted region
y [cm]
After type inversion only
fully depleted pixels should
work
80 VV
100
150
50
60
40
30
V
222
4500
1800
2000
7000
4000
5000
1800
4000
1600
3500
6000
1600
3500
1400
4000
3000
1400
5000
3000
1200
1200
2500
2500
1000
4000
3000
1000
2000
800
2000
3000
800
2000
1500
600
1500
600
2000
1000
400
1000
400
1000
1000
500
200
500
200
1.5
1.5
1.5
111
0.5
0.5
0.5
000
-0.5
-0.5
-0.5
-1
-1
-1
-1.5
-1.5
-1.5
-2
-2
-2
-2
-1.5
-2
-2 -1.5
-1.5
-1
-0.5
-1
-1 -0.5
-0.5
000
0.5
0.5
0.5
111
1.5
1.5
1.5 222
[cm]
xxx[cm]
[cm]
000
from M. Keil
LECC-Heidelberg, 15.06.2004
Norbert Wermes, Bonn
33
Hybrid Pixels / NA60 results
Indium targets
23 MeV ΔMµµ
position (mm)
Identification of interaction vertex to
20 µm transverse, 200 µm along beam
operation with
ATLAS modules
from M. Keil
LECC-Heidelberg, 15.06.2004
Norbert Wermes, Bonn
34
Hybrid Pixels
spin off into imaging applications
LECC-Heidelberg, 15.06.2004
Norbert Wermes, Bonn
35
Hybrid Pixels for Imaging Applications
radiography / crystallography
film-foil system
signal
output
digital
imaging by counting of X-ray photons
the principle
• excellent linearity
• large dynamic range
• good image contrast
• real time
challenge
build m2 & cheap
detectors
spin-off
from HEP
LECC-Heidelberg, 15.06.2004
dose / mGy
under-exposed
normal
under-exposed
normal
over-exposed
over-exposed
Norbert Wermes, Bonn
36
Hybrid Pixels for Imaging Applications
radiography / crystallography
imaging by counting of X-ray photons
the principle
The challenges
• high speed counting (107-9 cnts/s/mm2)
>15 bit counter, > 1 MHz / pixel
• no (little) dead time during exposure
• operation at even lower noise / thr disp.
ENC < 100e, σthr << 100e (tuned)
• diff. energy window (double threshold)
• high X-ray absorption (GaAs, Cd(Zn)Te)
X-ray imaging
• MEDIPIX Collaboration (CERN et al. )
• MPEC (Bonn Univ.)
• Uppsala, Svedberg, Scanditronix Coll.
really digital
LECC-Heidelberg, 15.06.2004
Crystallography with synchrotron light
XPAD (CPPM-Marseille @ ESRF)
PILATUS (PSI @ SLS)
Norbert Wermes, Bonn
37
Hybrid Pixels / counting pixels
MEDIPIX (0.25µm CMOS)
256 x 256 pixels 55 x 55 μm2
max. count rate ~ 1 MHz/pixel
2 (3-bit tunable) discriminators
13 bit counter
Si
14kV
LECC-Heidelberg, 15.06.2004
MPEC (0.8µm CMOS)
2x2 chips, 1.3x1.3 cm2
2 x 2 chip modules (Si and CdTe)
32 x 32 pixels 200 x 200 μm2
max. count rate ~ 1 MHz/pixel
2 tunable thresholds, 18 bit cntr
Si
20kV
CdTe
60kV
Norbert Wermes, Bonn
38
Hybrid Pixels / crystallography by counting
PILATUS @ SLS , XPAD @ ESRF
experimental setup
Detector Plates
Protein
Sample
monochromatic
Xray Beam
CPPM Marseille
& ESRF
protein crystallography
diffraction expts (mat.sci)
small angle scattering
• Ephoton > 6 keV
• spot size of diffraction maxima: 50 - 100 µm
• Æ ~ 200 x 200 µm2 pixels, good PSF
• single photon counting with large dyn. range
• digestible hit rate per pixel = 1- 1.5 MHz
• desirable: no dead area !
LECC-Heidelberg, 15.06.2004
Norbert Wermes, Bonn
39
Hybrid Pixels / crystallography by counting
PILATUS @ SLS , XPAD @ ESRF
experimental setup
Detector Plates
Protein
Sample
monochromatic
Xray Beam
PILATUS-1MCPPM
@ SLS
/ PSI
Marseille
20 x 24 cm2, 1 Mpix
& ESRF
Æ upgrade to 6Mpix
protein crystallography
diffraction expts (mat.sci)
small angle scattering
• Ephoton > 6 keV
• spot size of diffraction maxima: 50 - 100 µm
• Æ ~ 200 x 200 µm2 pixels, good PSF
• single photon counting with large dyn. range
• digestible hit rate per pixel = 1- 1.5 MHz
• desirable: no dead area !
LECC-Heidelberg, 15.06.2004
from B. Henrich
Norbert Wermes, Bonn
40
Hybrid Pixels / crystallography by counting
PILATUS @ SLS , XPAD @ ESRF
experimental setup
CPPM Marseille
&pixel
ESRFB
pixel A
Detector Plates
50%
Protein
Sample
critical threshold tuning
for homogeneous
response !
monochromatic
Xray Beam
• Ephoton > 6 keV
• spot size of diffraction maxima: 50 - 100 µm
• Æ ~ 200 x 200 µm2 pixels, good PSF
• single photon counting with large dyn. range
• digestible hit rate per pixel = 1- 1.5 MHz
flat
field
image
• desirable: no dead area !
LECC-Heidelberg, 15.06.2004
Norbert Wermes, Bonn
41
Thaumatin
electron
density
Thaumatin
crystal
map
Data Taking:
Processing with XDS
Data set: 120o
Refinement with SHELXL
Exp Time: 4s
Integration: 1o
Completeness: 90.3%
Beam energy: 11.9 keV
Beam intensity: 13.5%
Rsym 8.4%
D Sample-Det: 128 mm
Resolution: 1.4 Å
Resolution: 1.4 Å
Analysis:
Refinement:
R-Factor 28%
3 data sets merged
full geometrical correction
Processed with XDS
Robs: 8.9% (overall)
Completeness: 90%
(98% up to 1.6 Å)
from B. Henrich
Paul Scherrer Institut • 5232 Villigen PSI
Beat Henrich
Hybrid Pixels
Hybrid Pixels
challenges of a Super-LHC
for pixels: Φ ~ 1016 neq/cm2
LECC-Heidelberg, 15.06.2004
Norbert Wermes, Bonn
43
RD50
Radiation Damage in Silicon Sensors
A revie
w
in 5 s li
des
Two general types of radiation damage to the detector materials:
• Bulk (Crystal) damage due to Non Ionizing Energy Loss (NIEL)
- displacement damage, built up of crystal defects –
I.
Change of effective doping concentration (higher depletion voltage,
under- depletion)
II. Increase of leakage current (increase of shot noise, thermal runaway)
1016 neq/cm2
=
III. Increase of charge carrier trapping (loss of charge)
• Surface damage due to Ionizing Energy Loss (IEL)
- accumulation of positive in the oxide (SiO2) and the Si/SiO2 interface –
affects: interstrip capacitance (noise factor), breakdown behavior, …
Impact on detector performance and Charge Collection Efficiency
(depending on detector type and geometry and readout electronics!)
10 x LHC
big effect
M. Moll
Pixel2005
Signal/noise ratio is the quantity to watch
⇒ Sensors can fail from radiation damage !
Michael Moll – PIXEL 2005, September 7, 2005
-44-
RD50
Approaches to develop
radiation harder tracking detectors
Scientific strategies:
I.
Material engineering
II. Device engineering
III. Change of detector
operational conditions
CERN-RD39
“Cryogenic Tracking Detectors”
Talks this Workshop
H.Kagan, R.Stone
D.Moraes
S.Parker
M.Swartz
• Defect Engineering of Silicon
• Understanding radiation damage
• Macroscopic effects and Microscopic defects
• Simulation of defect properties & kinetics
• Irradiation with different particles & energies
• Oxygen rich Silicon
• DOFZ, Cz, MCZ, EPI
• Oxygen dimer & hydrogen enriched Si
• Pre-irradiated Si
• Influence of processing technology
• New Materials
• Silicon Carbide (SiC), Gallium Nitride (GaN)
• Diamond: CERN RD42 Collaboration
• Amorphous silicon
• Device Engineering (New Detector Designs)
• p-type silicon detectors (n-in-p)
• thin detectors
• 3D and Semi 3D detectors
• Stripixels
• Cost effective detectors
• Simulation of highly irradiated detectors
• Monolithic devices
Michael Moll – PIXEL 2005, September 7, 2005
-45-
Hybrid Pixels / CVD diamond pixel detectors
• ongoing effort RD42-ATLAS (Ohio-IZM-Bonn)
• single chip modules (2880 pixels) and full ATLAS modules made
• very nice results with 109Cd !! (22 keV, only 1600e) source
2250
2000
1750
1500
1250
1000
750
500
250
109Cd
0
0
4
6
8
10
12
Ladung/1000e
position correlation
Lab
LECC-Heidelberg, 15.06.2004
2
Landau distr.
Test Beam
Norbert Wermes, Bonn
46
Hybrid Pixels / diamond pixel detectors
what one can study very well with pixels …
CVD diamond
E
T. Lari et al., NIM A 537 (2005) 581-593
diamond
Si
Look at correlation of the residuals of two events as a
function of the track separation.
LECC-Heidelberg, 15.06.2004
Norbert Wermes, Bonn
47
Hybrid Pixels / diamond pixel detectors
Full 16-chip pixel module (using ATLAS FE-chips)
Ohio
IZM, Berlin
Bonn
RD42 – Ohio – IZM - Bonn
LECC-Heidelberg, 15.06.2004
Norbert Wermes, Bonn
48
Hybrid Pixels / diamond pixel detectors
noise map
mean = 137e
LECC-Heidelberg, 15.06.2004
threshold map
tuned
sigma = 25e
Norbert Wermes, Bonn
49
Testbeams: CERN (4hrs !) and DESY (4 GeV)
CERN
CERN
residuals
DESY
1 chip
module
16 chip
module
7µm
resolution multiple scattering dominated !
homogeneity tests under study
LECC-Heidelberg, 15.06.2004
-30µm
+30µm -150µm
Norbert Wermes, Bonn
37µm
+150µm
50
Hybrid Pixels / Edge Active 3D Detectors
Electrodes are processed inside the detector
bulk instead of being implanted on the
wafer's surface.
Holes are plasma-etched and then filled with
doped polysilicon.
• charges drift parallel to surface over
short range Æ fast and radhard
• the edge itself is an electrode
Æ large active area (close to beam !)
f
• lower fields for full depletion
Æ less breakdown
detector photo
speed: planar
3D
4.
4.
from
S. Parker
4.
LECC-Heidelberg, 15.06.2004
Norbert Wermes, Bonn
51
Hybrid Pixels / Edge Active 3D Detectors
pixel detector assemblies are
still to be made !
first assemblies with bump
bonded ATLAS FE-I3
did not work !
effort is repeated very soon !
LECC-Heidelberg, 15.06.2004
Norbert Wermes, Bonn
52
(Semi)-Monolithic Pixels
a „dream“ of detector physicist
1. (high Z) semiconductor sensor
with
2. fully integrated ampl. circuitry and R/O logic
using
3. commercially available CMOS technologies
developments largely driven by requirements for the ILC
Total > 500 MPixel with ~ 25x25 µm cells
hit rate = 80 hits / mm2 / bunch train (due to beamstrahlung e+e- pairs)
occupancy ~20% Î need tricks eg. permanent R/O to both sides
LECC-Heidelberg, 15.06.2004
Norbert Wermes, Bonn
53
CMOS Active Pixels
LECC-Heidelberg, 15.06.2004
Norbert Wermes, Bonn
54
Monolithic Pixels / CMOS Active Pixels
charge coll. in several µm thin epi-layer by thermal diffusion to n-well/epi junction
p-wells and substrate highly doped Æ charges kept between reflection boundaries
signals processed by standard CMOS circuitry integrated on sensor
only nMOS in active area (due to n-well/epi collection diode)
Q-collection time ~100 ns (due to diffusion)
incomplete Q-collection and small signals (< 1000 e) => challenge for IC design
small pixel sizes (< 20x20 µm2): a must and a virtue !
1 Pixel - Cluster Signal Distribution
MIMOSA I 4-diode pixel
Nent: 15721
Big Peak
Mean: 55.53
SD: 17.53
R2: 3.74
Second Peak
Mean: 109.09
5.9 keV
SD: 3.63
R2: 1.85
epi-layer
full Q
55Fe
# Entries
•
•
•
•
•
•
•
at n-well
partial
collection
in
6.49 keV
Cluster Signal [ADC]
Diericks, Meynants, Scheffer (1997)
LECC-Heidelberg, 15.06.2004
Norbert Wermes, Bonn
55
Monolithic Pixels / CMOS Active Pixels
R&D on CMOS pixels wide spread in HEP: >20 labs (10 IC design groups)
Target projects:
BELLE upgrade Æ SuperBELLE (< 2008)
Univ.Hawaii, KEK, Univ.Tsukuba, Univ.Krakow,
Univ.Tokyo, Univ. Nova Gorica
STAR upgrade
LBNL, IReS (Strasbourg), Univ.Irvine
ILC
IReS (Strasbourg), DAPNIA (Saclay), LPC (Clermont),
LPSC (Grenoble), Univ.Roma-3, Univ.Bergamo, LBNL,
RAL, Univ.Hamburg, Univ.Liverpool, Univ.Glasgow, DESY,
Univ.Pavia, Univ.Oregon, Univ.Yale, Univ.Como
CBM @ GSI
IReS (Strasbourg), GSI, Univ.Frankfurt
LECC-Heidelberg, 15.06.2004
Norbert Wermes, Bonn
56
CMOS active pixels / R/O & performance
row selection → column R/0
„standard“ 3 transistor R/O scheme (e.g. MIMOSA-1, BELLE with pipeline)
→ upgraded to include amplification, current memory (15 transitors, MIMOSA-7)
reset
source follower stage
• detectors sizes up to
19.4 x 17.4 mm2 (1Mpix)
select
• smallest pitch: 17 µm
• achieved frame speed:
10µs for 132x48 pixels
(BELLE) @ 30-50e- noise.
from M. Winter
LECC-Heidelberg, 15.06.2004
Norbert Wermes, Bonn
57
from D. Contarato
LECC-Heidelberg, 15.06.2004
Norbert Wermes, Bonn
58
Monolithic Pixels / achieved features
MPV~334 e
noise ~10-15eS/N > 20
εmip > 99%
1 Mpix devices in
testbeam
AMS 0.6µm
spatial resolution
1.5 µm (20 µm pix)
5 µm (40 µm pix)
(14 µm epi)
from M. Winter
present favourite
AMS 0.35µm
OPTO process
(10 µm epi)
LECC-Heidelberg, 15.06.2004
cluster charge
Norbert Wermes, Bonn
59
Monolithic Pixels / radiation tolerance
NIEL non-ionizing
energy loss
1012
IEL
(M. Winter)
(ionizing energy loss)
-shift of threshold voltages
-leakage current in nMOS trans. and intertrans.
ILC
int.
time
studies still ongoing
≤1012 neq/cm2 acceptable
for AMS 0.35 OPTO
LECC-Heidelberg, 15.06.2004
> 1 MRad ok
for short integration times
Norbert Wermes, Bonn
60
Monolithic Pixels / next steps / improvements
‹ improve rad. tolerant designs
• guard rings
• avoid thick oxide around n-wells
‹ thinning Æ 50 µm
‹ improve charge collection
i.e. increase depleted region
• enlarge n-well surface
• increase n-well potential
• buried electrode
e.g. triple n-well technology
or photo-FET techniques
triple n-well
‹ towards large detectors
• large reticules
• reticle stitching
LECC-Heidelberg, 15.06.2004
Norbert Wermes, Bonn
61
Monolithic Pixels / “in early R&D phase”
CMOS with SOI technology
• high res.(4kΩcm) 300 µm bulk
„via“ structure to electr. layer
+ full Q-collection (drift !)
+ probably radhard !?
- non-Standard technology
~ 1.5 μm
~ 1.0 μm
~ 300 μm
prototypes successful
SUCIMA (Cracow/Warsaw/Como)
produced, but …
noise
90Sr
128 x128 matrix
3.0 µm technology
150x150 µm2 pixels
2.4 cm x 2.4 cm
first resultsneeds a detector vendor with a CMOS line !
LECC-Heidelberg, 15.06.2004
Norbert Wermes, Bonn
62
Monolithic Pixels / early R&D
P. Jarron (CERN) et al.
amorphous-SI atop CMOS ICs
• a-Si:H layer for Q-coll. (~1000e)
- Æ semi-monolithic
+ standard CMOS technology !
- low signal
Æ very low noise required
still in its beginnings
LBNL (Perez-Mendez), CERN (Jarron) & others
a-Si:H
Artistic view
~20% H
LECC-Heidelberg, 15.06.2004
Norbert Wermes, Bonn
63
DEPFET Pixels
LECC-Heidelberg, 15.06.2004
Norbert Wermes, Bonn
64
Monolithic Pixels / DEPFET pixels
Potential distribution:
source
top gate
internal gate
-
bulk
p+
n+
n+
p+
p-channel
+
drain
---- +
-+ -
potential via axis
top-gate / rear contact
1 μm
n
-+
totally depleted
n--substrate
internal Gate
potential minimum
for electrons
50 µm
- 300 μm
p+
rear contact
V
[TeSCA-Simulation]
(MOS)FET-Transistor integrated in every pixel (first amplification)
Local potential minimum (for e- ) under transistor channel
Electrons are collected in „internal gate“ and modulate the transistor-current
Signal charge removed via clear contact
output is a current
J. Kemmer und G. Lutz;, NIM A253 (1987) 365
LECC-Heidelberg, 15.06.2004
Norbert Wermes, Bonn
65
Monolithic Pixels / DEPFET pixels
Potential distribution:
+15V
source top gate
drain
0V
clear
0V
bulk
internal Gate
symmetry axis
p+
p
n+
n+
n
- ----internal gate
CLEAR complete ?
n
Ælow noise CLEAR
Æfast pedestal subtraction
p+
YES ! (C. Sandow)
50 µm
p+
~1µm
n+
-
rear contact
[TeSCA-Simulation]
(MOS)FET-Transistor integrated in every pixel (first amplification)
Local potential minimum (for e- ) under transistor channel
Electrons are collected in „internal gate“ and modulate the transistor-current
Signal charge removed via clear contact
output is a current
J. Kemmer und G. Lutz;, NIM A253 (1987) 365
LECC-Heidelberg, 15.06.2004
Norbert Wermes, Bonn
66
Monolithic Pixels / DEPFET pixels
‹
‹
full (high ohmic) bulk sensitivity Æ large Q for mip
very low input capacitance
Æ low noise
Æ high E-resolution / thin sensors
‹ for ILC Æ high speed (>10 MHz / row)
Collaboration:
Bonn – Mannheim – Munich (MPI,HLL)
interested: Aachen, Prague, Valencia, Fermilab, LBL, Cracow, Como
LECC-Heidelberg, 15.06.2004
Norbert Wermes, Bonn
67
PXD4 - DEPFET: Two projects on one wafer
XEUS (satellite mission)
ILC
purpose
imaging spectroscopy
particle tracking
sensor size
7.68 x 7.68 cm²
1.3 x 10 cm², 2.2 x 12.5 cm²
pixel size
75 µm
25 µm
sensor thickness
300 ... 500 µm
50 µm
noise
4 el. ENC
~ 100 el. ENC
Readout time per row
2.5 µs
20 ns
from L. Andricek, P. Lechner
PXD4 - DEPFET: Two projects on one wafer
gate_2
global
source
drain_2
common
clear
drain_1
gate_1
XEUS (satellite mission)
ILC
purpose
imaging spectroscopy
particle tracking
sensor size
7.68 x 7.68 cm²
1.3 x 10 cm², 2.2 x 12.5 cm²
pixel size
75 µm
25 µm
sensor thickness
300 ... 500 µm
50 µm
noise
4 el. ENC
~ 100 el. ENC
Readout time per row
2.5 µs
20 ns
from L. Andricek, P. Lechner
DEPFET / operation of a DEPFET Matrix
• 1 active row
DEPFETs are ON
R/O Æ CLEAR Æ R/O
• all other rows OFF
still active for signals
Æ low power !
Current Readout chip
(read currents, store and subtract pedestals)
LECC-Heidelberg, 15.06.2004
- Read cells of a row
& store their currents
- Clear internal gates
of this row completely
- Read again (pedestal
currents) and subtract
by adding currents
Norbert Wermes, Bonn
70
DEPFET / operation of a DEPFET Matrix
Gate
Switcher
Hybrid
DEPFET Matrix
64x128 pixels, 36 x 28.5µm2
Current Readout
CUROII
Clear
Switcher
Testbeam Stack
PCB with
DEPFET matrix
Analog board
with ADCs etc.
USB based digital
interface board
from R. Kohrs
LECC-Heidelberg, 15.06.2004
Norbert Wermes, Bonn
71
DEPFET / radiation tolerance
concern: IEL from beamstrahlung e+e- at ILC
ƒ 60Co
ƒ
(1.17 MeV and 1.33 MeV)
X-Ray tube with Mo target at 30kV
pre- vs post-irradiation
∆Not (cm-2)
-∆Vth (V)
"ON"
~ 4-5 V"OFF"
ILC
3.5h 123.5h 293.5h
annealing
Drain current (µA)
Dose (krad)
threshold shifts
transistor characteristics
from L. Andricek
LECC-Heidelberg, 15.06.2004
Norbert Wermes, Bonn
72
Performance after irradiation
Irradiated double pixel DEPFET
o L=7μm, W=25 μm
o after 913 krad, 60Co
o
Vthresh≈-4V, Vgate=-5.3V
o
Idrain=21 μA
o
Drain current read out
o
time cont. shaping τ=6 μs
55Fe
Counts/channel
o
Noise ENC=7.9 e- (rms)
at T>23 degC
Energy (eV)
from L. Andricek
DEPFET / testbeam performance
correlation
telescope ⇔ DEPFET
DEPFET
data
pedestal and common
mode corrected
Î noise ~ 225 e-
resolution multiple scattering dominated !
LECC-Heidelberg, 15.06.2004
Norbert Wermes, Bonn
74
DEPFET / testbeam events
128 Rows
64 columns
raw data hit
LECC-Heidelberg, 15.06.2004
single hit cluster
interpretation
δ-electron with perpendicular emission
range consistent with measured energy deposit
Norbert Wermes, Bonn
75
DEPFET / testbeam results
spatial residuals
for stiff tracks
dominated by multiple scattering (6
ry
a
in
m
eli
r
P
GeV e-)
Pixel Size 36 µm x 28.5 µm
Æ Spatial residuals
σres ~ 10 μm
pitch
Æ Binary position reconstruction ( 12 )
σsp ~ 10.4 µm x 8.3 µm
Æ Center of Gravity (S/N ~ 144) expected σsp ~ 2 - 4 µm
from L. Reuen
LECC-Heidelberg, 15.06.2004
Norbert Wermes, Bonn
76
ILC Module Concept: use good S/N for thinning !
‘Holes’ in frame save
material
Chips are thinned to 50 μm,
connection via bump bonding
Thinned sensor (50 µm) in
active area
Thick support
frame (~300 µm)
50 µm
300 µm
Cross section of a module
1st layer module
minimal cooling (X0 !!) necessary
~ 5W for 5 layer VTX detector
m
m
.5
15
thinning technology ;
proven with active diodes
sketch of a(<1nA/cm2)
300µm
r=
50 µm
8 Modules in Layer1
from L. Andricek
Concluding Remarks
¾ Hybrid Pixels
- state of the art for tracking (LHC) Æ imaging (biomed & synchr. light)
- SLHC: new materials, 3D ?
¾ (Semi)-Monolithic Pixels
- a MUST for the next generation of pixel VTX detectors
because of: X0, small pixel size, low power potential
- more „mature“ solutions developments
- CMOS Active Pixels
- DEPFET pixels
- very interesting R&D developments: SOI pixels and a-Si:H
¾ ultimate goals (dreams ?)
- tracking: full CMOS R/O & logic with charge coll. in high res. bulk
- imaging: amorphous high-Z materials (a-Se, PbI2 , HgI2 , PbO)
on top of CMOS ICs
LECC-Heidelberg, 15.06.2004
Norbert Wermes, Bonn
78
END
.
LECC-Heidelberg, 15.06.2004
Norbert Wermes, Bonn
79
Backup Transperencies
Hybrid Pixels
LECC-Heidelberg, 15.06.2004
Norbert Wermes, Bonn
80
# Pixels
/ chip
Pixel area
[mμ2]
Iana
Power/chip
Power/pixel
Power density
[mA]
[mA]
[mW]
[μW]
[ mW/cm2 ]
ALICE
8192
21’250
150
300
810
99
466
ATLAS
2880
20’000
35
75
190
67
335
CMS
4160
15’000
32
24
121
29
194
LECC-Heidelberg, 15.06.2004
Idig
Norbert Wermes, Bonn
81
CMS
LECC-Heidelberg, 15.06.2004
Norbert Wermes, Bonn
82
LECC-Heidelberg, 15.06.2004
Norbert Wermes, Bonn
83
LECC-Heidelberg, 15.06.2004
Norbert Wermes, Bonn
84
DEPFET / testbeam results
• Purity ≈ 0.97
• Efficiency ≈ 0.99
(6σ seed cut)
x 10
S/N = 144 @ 450 µm thickness Î S/N ~ 15 for 50 µm
from R. Kohrs
LECC-Heidelberg, 15.06.2004
Norbert Wermes, Bonn
85
Because of time walk, if charge is shared,
some low pulse heights may be associated
to the wrong beam crossing.
These lost hits results in degradation of
resolution, there is also an issue of intime resolution.
A feature of the FE is the ability to
duplicate hits with low pulse height (ToT),
changing the beam crossing assignement.
Therefore the efficiency to collect all
hits generated by one track can be
greatly improved, giving maximum
resolution, with just a moderate increase
of occupancy.
LECC-Heidelberg, 15.06.2004
efficiency
Late hit duplication
Cluster
efficiency
efficiency
1
no hit duplication
duplicate ToT 5
0.8
duplicate ToT 10
duplicate ToT 15
0.6
0.4
Efficiency for
all hits in the
same BCO
0.2
0
0
10
20
30
40
efficiency hit
50
60
70
time (ns)
ToT threshold
Hits/track
No duplication
2.03
ToT<5
2.24
ToT<10
2.71
ToT<15
3.11
Norbert Wermes, Bonn
86
Charge collection in irradiated assemblies
Pixel Cluster Charge
200V
Unirradiated
0.025
1.1 10
15
2
n eq/cm , 25h@60C
0.02
0.015
400V
0.01
0.005
0
0
600V
LECC-Heidelberg, 15.06.2004
10
15
20
25
30
35
40
45
50
Cluster Charge (ke)
cluster charge (ke)
700V
Vbias
5
mean CCE after 10 yrs LHC
~ 80 %
2 pixels
(with LHC type annealing scenario)
due to 1. bias grid, 2. trapping
Norbert Wermes, Bonn
87
Hybrid Pixels / MPEC / energy windowing
multi threshold counting
Æ differential E-measurement
2 thresholds
+ window logic
0.030
tube
flux, arbitrary units
0.025
low
tube spectrum
after 1 cm tissue
after 1 cm bone
high
behind tissue
0.020
behind
bone
0.015
0.010
MPEC2.3
0.005
0.000
20
30
40
50
60
energy / keV
LECC-Heidelberg, 15.06.2004
70
80
N38-1 Löcker
see also N36-106 Edling
Norbert Wermes, Bonn
88
Hybrid Pixels / Summary
¾ state of the art technology
• large (~m2) rad hard tracking detectors in production 9
• counting pixel detectors for X-ray imaging 9
even at large scale (PILATUS) 9
¾ issues
•
•
•
•
complicated assembling (hybridization, R/O flex hybrid)
watch yield losses (many production steps)
material budget (for tracking detectors) not low (>2% X0)
high Z materials (for imaging) not trivial (Q-coll+hybridiz.)
¾ trends
•
•
•
•
diamond (better than Si ?)
smaller pixel cells / interleaved pixels Æ < 5µm resolution
MCM-D – hybridization
3D edge active sensors for high rate / large active area
LECC-Heidelberg, 15.06.2004
Norbert Wermes, Bonn
89
Indium process (AMS)
Rome, 31st of January 2000
Wafer Cleaning
Photolithography
Process parameters:
Plasma activation
• Resist Thickness: 15 μm
• Pre-bake: 30min @ 80 °C
Evaporated
Indium
• Deposition rate: 0.5 μm/min
• Dep. Pressure: 9 x 10 - 7 Torr
• Temp. during Dep. < 50 °C
Wet Lift off process
Anna Maria Fiorello - Research Dept
LECC-Heidelberg, 15.06.2004
Norbert Wermes, Bonn
90
Processflow PbSn-Bumping using Electroplating
Sputter Etching and Sputtering
of the Plating Base / UBM
Spin Coating and Printing
of Photoresist
Resist Stripping and wet Etching
of the Plating Base
Electroplating of Cu and PbSn
Reflow
LECC-Heidelberg, 15.06.2004
Norbert Wermes, Bonn
91
PbSn Solder Bump Structure
oxidation protection (Au) (100 - 200 nm)
(1 - 5 µm)
(200 nm)
(30 - 200 nm)
LECC-Heidelberg, 15.06.2004
Norbert Wermes, Bonn
92
Monolithic Pixels / tracking Î Linear Collider
requirements
Thin (< 50 µm, 0.1% Xo)
Small cells (< 25 µm x 25 µm)
Fast (50 MHz/line, 25 kHz/frame ≈2Mpix)
Low power (few Watts for full detector)
No trigger
Options:
CCD
MAPS
HAPS
DEPFET
Layer
Module size
No. Of
modules
I
13 x 100 mm
1 x 8
II
22 x 125 mm
2 x 8
III
22 x 125 mm
2 x 12
IV
22 x 125 mm
2 x 16
V
22 x 125 mm
2 x 20
Total > 500 MPixel (w. 25x25 µm cells)
hit rate = 80 hits / mm2 / bunch train due to beamstrahlung e+e- pairs
occupancy ~20% Î need tricks : continuous R/O to both sides
LECC-Heidelberg, 15.06.2004
Norbert Wermes, Bonn
93
3D
LECC-Heidelberg, 15.06.2004
Norbert Wermes, Bonn
94
Speed: planar
3D
from
S. Parker
4.
4.
4.
1. 3D lateral cell size can be smaller than wafer thickness, so
1.
shorter collection distance
2. in 3D, field lines end on cylinders rather than on circles, so
2.
3. most of the signal is induced when the charge is close to the
electrode, where the electrode solid angle is large, so planar
signals are spread out in time as the charge arrives, and
higher average fields for any
given maximum field (price:
larger electrode capacitance)
3.
3D signals are concentrated in
time as the track arrives
4. Landau fluctuations along track arrive sequentially and may cause
secondary peaks (see next slide)
4.
Landau fluctuations arrive
nearly simultaneously
5. if readout has inputs from both n+ and p+ electrodes,
5.
drift time corrections can be
made
6. for long, narrow pixels and fast electronics,
6.
track locations within the pixel
can be found
LECC-Heidelberg, 15.06.2004
Norbert Wermes, Bonn
95
Keys to the technology
S. Parker
1. Plasma etchers can now make deep, near-vertical holes and trenches:
a. SF6 in plasma → F, F – → driven onto wafer by E field
b. Si + 4F → SiF4 (gas)
c. SF6 replaced with C4F8 → CF2 + other fragments which
d. form teflon-like wall coat protecting against off-axis F, F –
e. repeat (a – d) every 10 – 15 seconds
2. At ~620ºC, ~0.46 Torr, SiH4 gas molecules bounce off the walls many times before they
stick, mostly entering and leaving the hole. When they stick, it can be anywhere, so
they form a conformal polysilicon coat as the H leaves and the silicon migrates to a
lattice site.
3. Gasses such as B2O3, B2H6 (diborane), P2O5, and PH3 (phosphine) can also be deposited
in a conformal layer, and make p+ and n+ doped polysilicon.
4. Heating drives the dopants into the single crystal silicon, forming p–n junctions and ohmic
contacts there. Large E drift fields can end before the poly, removing that source of
large leakage currents.
5. Active edges are made from trench electrodes, capped with an oxide coat. Plasma dicing
up to the oxide etch stop makes precise edges.
LECC-Heidelberg, 15.06.2004
Norbert Wermes, Bonn
96
MAPS
LECC-Heidelberg, 15.06.2004
Norbert Wermes, Bonn
97
CMOS active pixels / towards larger modules
8” wafer (0.25µm technology)
large & full reticles
seamless reticle stitching
~2x2 cm2
Æ approach
100% active area
for modules
of order 10cm2
CLRC-RAL
LECC-Heidelberg, 15.06.2004
IRES/LEPSI
Norbert Wermes, Bonn
98
CMOS pixels /
towards more complete charge collection
Triple n-well
(CLRC&RAL)
better field shaping
R. Turchetta, Vertex03
photo-FET (IReS&LEPSI)
Deptuch/Dulinski IEEE2003
similar to DEPFET pixels
charge collected at n-well
affects gate voltage of
pMOS FET and modulates
its current
LECC-Heidelberg, 15.06.2004
Norbert Wermes, Bonn
99
CMOS pixels /
towards more complete charge collection
Triple n-well
(CLRC&RAL)
better field shaping
R. Turchetta, Vertex03
photo-gate (Irvine-LBL)
S. Kleinfelder, IEEE2003
LECC-Heidelberg, 15.06.2004
Norbert Wermes, Bonn
100
DEPFET
LECC-Heidelberg, 15.06.2004
Norbert Wermes, Bonn
101
DEPFET / three (very different) projects
Bioscope
a single circular
DEPFET
Îmedical
imaging
purpose
Fe
imaging spectroscopy
Xray astronomy
55 tracking
particle
HEP
64 x 64 pixels
7.68 x 7.68 cm²
1024 x 1024 pixels
1.3 x 10 cm² (x 8)
520 x 4000 pixels (x 8)
4 kpix
1 Mpix
2.1 Mpix (x120)=2.5 x 108
75 µm
25 µm
biomed. imaging
L = 5 µm,P.
W Weilhammer
= 40 µm
Thursday,
detector format
3.2 x 3.2
mm²
time-continuous
filter,
τ9h
= 6 µs
Next for XEUS development:
pixel size
µm
operation
of 64 x 64 50
prototype
incl. readout & control ASICs
sensor thickness
300 µm
300 ... 500 µm
50 µm
matrix noise
65 el. ENC
< 4 el. ENC
50-100 el. ENC
readout time
... per detector
... per row
1 ms
200 µs
1.2 ms
2.5 µs
50 µs
20 ns
status
finished Æ 57lp/mm
dev. phase
dev. phase
LECC-Heidelberg, 15.06.2004
Norbert Wermes, Bonn
102
DEPFET thinning
Top Wafer
Handle <100> Wafer
a) oxidation and back side implant of top wafer
b) wafer bonding and grinding/polishing of top
wafer
TESLA-Module („dummy“ sample)
50µm silicon with 350µm (perforated) frame
LECC-Heidelberg, 15.06.2004
c) process Î passivation
open backside passivation
d) anisotropic etching from backside (TMAH)
thinned diode structures:
leakage current: <1nA /cm2
Norbert Wermes, Bonn
103
DEPFET / Module Concept for LC
Auslesechips
520 x 4000 pixel
DEPFET-Matrix
(25 x 25µm Pixel)
Steuerchips
Auslesechips
LECC-Heidelberg, 15.06.2004
• Sensor area thinned down to 50 µm
• Remaining frame for mechanical stability
carrying readout and steering chips
Norbert Wermes, Bonn
104