Transcript Talk_N28-6 - INFN - Torino Personal pages

Building Pixel Detector Modules in
Multi Chip Module Deposited Technology
IEEE Nuclear Science Symposium
Roma Oct.2004
Bergische Universität Wuppertal
Peter Gerlach
Originally…
…this talk should have
been given by my
colleague
Christian Grah.
Here you can see,
how he looks like, at least.
But if you would have met
him during the last years,
he probably looked as
shown on the right
picture!
Christian Grah
Now at Desy Zeuthen
(Berlin, Germany)
20.Oct. 2004
NSS Roma 2004; P.Gerlach (Ch.Grah);
Multi Chip Module Deposited
2
Subject of this talk
Application of a ‘thin’ film technology on a high energy physics
detector.
Hybrid pixel detector (ATLAS, LHC, CERN)
Definition
Geometrical constrains
Thin film technology
Explanation of the process
Typical dimensions
Introduce some prototypes build,
gaining from a strong support of
The ATLAS pixel detector project
Fraunhofer Institute IZM (Berlin, Germany)
Structures realised
Results optained
Laboratory and
test-beam environment
Summary (How to…)
20.Oct. 2004
NSS Roma 2004; P.Gerlach (Ch.Grah);
Multi Chip Module Deposited
3
Hybrid Pixel Detector
Three parts:
Sensor
High quality silicon wafer
PiN structure
Segmentation into ‘pixels’
Readout Electronics
Interconnection
Sizes for e.g. ATLAS Pixel:
Module 2x6cm²
16 readout chips
~50.000 pixels à 50x400µm
20.Oct. 2004
NSS Roma 2004; P.Gerlach (Ch.Grah);
Multi Chip Module Deposited
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Interconnect via Kapton-foil
„ATLAS Flex“
Interconnect
Sensor
FE
20.Oct. 2004
FE
3D design
note control chip and
components on top
>500 wire-bonds per module
Sensor has to cover gaps in
electronics
NSS Roma 2004; P.Gerlach (Ch.Grah);
Multi Chip Module Deposited
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Interconnect integrated
„ATLAS MCM-D“
FE
FE
Interconnect
Sensor
20.Oct. 2004
NSS Roma 2004; P.Gerlach (Ch.Grah);
Multi Chip Module Deposited
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MultiChipModule-Deposited
Technology
Spin-On BCB (Benzocyclobuthen)
Photolithographic structuring/exposure
Developing and stripping of unexposed
BCB (soft-cure)
Sputtering of Cu – plating base layer
Spin-On and structuring of PhotoResist
Electroplating of Cu – layer
Stripping of Photo-Resist and etching
of plating base
Spin-On next BCB layer ( h) = a) )
20.Oct. 2004
NSS Roma 2004; P.Gerlach (Ch.Grah);
Multi Chip Module Deposited
7
MCM-D wafer after processing
10cm
20.Oct. 2004
NSS Roma 2004; P.Gerlach (Ch.Grah);
Multi Chip Module Deposited
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MCM-D structures
Different scales!
75µm
contact to signal bus system
75µm
contact to power distribution system
50µm
500µm
contact for Probecard
(process monitoring)
20.Oct. 2004
pixel matrix - feedthroughs
NSS Roma 2004; P.Gerlach (Ch.Grah);
Multi Chip Module Deposited
9
MCM-D Module Prototype
readout chips
NTC, capacitors
and LVDS
termination
MCC
Kapton
flex circuit
VBias (backside)
20.Oct. 2004
NSS Roma 2004; P.Gerlach (Ch.Grah);
Multi Chip Module Deposited
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MCM-D, geometry
conductor layers
Up to 5 copper layers:
magnetron sputtered
up to 300 nm Ti:W/Cu
additive electroplating
up to 3 mm Cu
Minimal
width
15µm
spacing
15µm
Final metallisation:
5mm Cu/200nm Au
5mm Cu/Ni/200nm Au
20.Oct. 2004
dielectric layers
“Spin-on” polymer: BCB
(Benzocyclobutene /
DOW:CYCLOTENE™)
Photosensitive
Specific dielectric constant
er= 2.7
Process temperatures :
1h 220C per layer
last layer 1h 250 C
Thickness / layer 2 - 6 mm
Via  >22 mm, Pad >25µm
NSS Roma 2004; P.Gerlach (Ch.Grah);
Multi Chip Module Deposited
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MCM-D Module Prototype
20.Oct. 2004
NSS Roma 2004; P.Gerlach (Ch.Grah);
Multi Chip Module Deposited
12
Geometrically Optimized
Pixel Sensor
conventional sensor layout:
(inter-chip region)
optimized sensor layout
(Equal-sized Bricked):
drawn: sensor layout, top metal layer
20.Oct. 2004
NSS Roma 2004; P.Gerlach (Ch.Grah);
Multi Chip Module Deposited
special thx to Tilman Rohe
13
Routing structures
50µm
20µm
200µm
20.Oct. 2004
BCB is etched for visualisation
(except of some pillars)
NSS Roma 2004; P.Gerlach (Ch.Grah);
Multi Chip Module Deposited
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Equal - Sized - Bricked single chip assembly:
distribution of threshold
3500
Equal Sized Bricked Design
1200
per bin
Counts
Einträge/Bin
2500
threshold
Schwelle [e/] e-
Equal Sized Bricked Design
1400
3000
2000
1500
1000
= 146.42943
Chi^2/DoF
= 0.99766
R^2
1000
2085.66048
159.01999
xc
w
800
±0.88028
±1.66184
600
400
500
200
0
0
0
320
640
960
1280
1600
1920
2240
2560
2880
0
500
Kanal (Spalte*160+Reihe)
Pixel number
1000
1500
2000
2500
3000
3500
4000
threshold
Schwelle [e ] / e-
No influence of the thin film structures, nor the bricked sensor structure visible
20.Oct. 2004
NSS Roma 2004; P.Gerlach (Ch.Grah);
Multi Chip Module Deposited
15
Equal - Sized - Bricked single chip assembly:
distribution of noise
Equal Sized Bricked Design
Standard Sensor Design
Equal Sized Bricked Design
Standard Sensor Design
1200
Einträge/bin
per bin
Counts
400
/ e- [e-]
ENCRauschen
300
200
100
EQB:
m1=
184.68 ±0.51
1=
36.01 ±1.06
1000
800
Standard:
m2=
180.85 ±0.76
2=
36.69 ±1.63
600
400
200
0
0
0
320
640
960
1280
1600
1920
2240
2560
2880
0
Pixel number
Kanal (Spalte*160+Reihe)
100
200
300
400
Rauschen
ENC
/ [ee-]
-
No influence of the thin film structures, nor the bricked sensor structure visible
20.Oct. 2004
NSS Roma 2004; P.Gerlach (Ch.Grah);
Multi Chip Module Deposited
16
Testbeam data
H8 Testbeam at
SPS (CERN)
primary: 450
GeV protons
Data was mainly
taken with:
180 GeV pions
Telescope with 4 x 2
layers of stripdetectors (Strip
pitch: 50 µm)
20.Oct. 2004
H8 Telescope system
NSS Roma 2004; P.Gerlach (Ch.Grah);
Multi Chip Module Deposited
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Charge collection of
equal sized bricked base-cell
Charge collection
very uniform
with expected
behaviour of
bias grid contacts
20.Oct. 2004
NSS Roma 2004; P.Gerlach (Ch.Grah);
Multi Chip Module Deposited
18
Charge collection for
single, double and triple hits
Slight charge deficit
of double hits is due
to high threshold
(chosen by mistake).
This fits to the
expected/seen number
of triple hits.
20.Oct. 2004
NSS Roma 2004; P.Gerlach (Ch.Grah);
Multi Chip Module Deposited
19
Summary
nice
higher manageability and better
handling of a module
bump bonds only (no wire-bonding)
sensor cell geometry can be optimized
reduced assembly steps
rework of full assembled module
possible (detach and reattach of chips)
options of final metallization
(Cu/CuNi/CuAu/CuNiAu/PbSn)
allow different technologies
higher degree of automation during
production
Experience with MCMD
successfully operated a radhard pixel
detector MCMD module
performance compatible with Flex
modules
Cooling ok (chip up design)
successfully increased
thin film yield
defect tolerant design with reduced
"critical" area
high demand on cleanliness
(includes new machinery and
optimization of process flow)
not so nice
increased size (but reduced height)
lower testability
(reduced access to inter-chip signals)
high complexity of the process
(find vendor)
20.Oct. 2004
NSS Roma 2004; P.Gerlach (Ch.Grah);
Multi Chip Module Deposited
20
How to build MCMD Modules:
Sensor:
1 module per 4” wafer
sensor dedicated for MCMD
(including dicing streets and
1cm rim)
Make use of geometrical
optimizations!
Thin Film Design:
defect tolerant design recommended
set of design rules has been developed
Metal-lines: 15/15um; Via 22um
Layer number vs. effort
is not linear!
Electronics:
Known good die problem
of Multi-Chip Module
is relaxed by the reworking option
prototyping restrictions:
changes in pin-out are expensive
(money and time)!
thinning: depending on the
interconnection technique (reflow)
thin chips get bowed during
heating up
Thin Film Processing:
automation <=> cleanliness
industry keeps increasing wafer size
NO PROBLEM for MCM-D, but
4 inch wafer (Sensors)
processing might become a
problem
20.Oct. 2004
NSS Roma 2004; P.Gerlach (Ch.Grah);
Multi Chip Module Deposited
21