IBL TDR Addendum
ATLAS Project Document No:
Institute Document No.
ATL-SYS-XX-XXX
Created: 17/03/2012
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Modified:
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IBL TDR Addendum
Abstract
This document is an addendum of the ATLAS IBL TDR of September 2010. This document focuses on the
“Mixed Scenario” where staves are populated in the centre with planar sensor modules and 3D sensors at
the two extremities. Planar sensors will be two chips in module size and 3D single chip.
Prepared by:
IBL Management Board + D. Ferrere
and C. Gemme.
Distribution List
ATLAS IBL Collaboration for comments
Checked by:
Approved by:
G. Darbo, H. Pernegger, M. Nessi, B.
Di Girolamo
ATLAS Project Document No:
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History of Changes
Rev. No.
Date
Pages
Description of changes
1
17/03/2012
All
First Draft
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Table of Contents
1 INTRODUCTION ................................................................................................................ 4
1.1
Sensor Qualification and Production Status .............................................................................................................. 4
2 MIXED SENSOR SCENARIO ............................................................................................ 5
2.1
Module Layout .............................................................................................................................................................. 5
2.2
Stave Layout.................................................................................................................................................................. 7
2.3
Module Loading on Stave ............................................................................................................................................ 8
2.4
Electrical services ......................................................................................................................................................... 8
3 DIAMOND BEAM MONITOR (DBM) ................................................................................. 9
4 REFERENCES ................................................................................................................... 9
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1
INTRODUCTION
At the time the IBL TDR [1] was submitted in September 2010, the sensor technology to go in the detector was not decided
yet. Three technologies were considered for the IBL: planar sensors n-on-n and n-on-p, 3D sensors with active or slim edge
and diamond detectors. A program of extensive testing of detector assemblies irradiated to IBL fluence of 5x1015 neq/cm2
and 250 Mrad was carried on in the Spring of 2011. Results were presented to the sensor technology review in July 2011.
The review panel recommendation was to investigate a “mixed scenario”, in which the 3D technology populates the
forward region where the tracking could take advantage of the electrode orientation to give a better z-resolution after heavy
irradiation. In section 2 of this Addendum document are presented the implications of the IBL “mixed scenario” to the
module, stave and services design.
In section 3 is presented the Diamond Beam Monitor (DBM) [5], which is a spin-off of the IBL technology coming from
the built assemblies of FE-I4 and diamond sensors. The DBM is a detector that is constructed by the IBL collaboration and
will be installed, if the existing ATLAS Pixel detector will be brought to surface for replacing the Quarter Service Panels
(nSQP project).
1.1
Sensor Qualification and Production Status
Between the end of two 2010 and early 2011, the plans for construction of IBL were substantially modified by two facts:
the change in the LHC long shutdowns (necessary to install the IBL) and the very good results of the FE-I4A front-end
chip, which raised the confidence to the need of minor changes for the production version.
The LHC shutdown to install the IBL, assumed in the IBL TDR, was for the end of 2015. The decision of LHC (Chamonix
2011) to have a long shutdown in 2013/14 has been considered by ATLAS a serious possibility to install the IBL. From all
the sensor technologies under study for IBL were considered the two that were more advanced and at mature stage for a
possible production: planar n-in-n and double side 3D sensors: it was decided to restrict the qualification of these two
technologies and develop FE-I4 modules to fully qualify in the test beam and at full IBL radiation dose. To fulfil the “speed
up schedule” it was decided, in January 2011, to launch a pre-production of planar sensors from CiS i and of double side 3D
sensors from CNMii and FBKiii. The idea behind was that we would have had already between 30% to 50% of sensor
available after the decision of the technology following the qualification phase and the subsequent sensor review.
The recommendation from the review panel are that both technologies fulfil the IBL requirements, and that there is an
opportunity to populate the forward region where the tracking could take advantage of the electrode orientation to give a
better z-resolution after heavy irradiation.
The IBL collaboration, following the recommendation from the review panel, decided to complete the production of planar
and 3D sensors and endorsed the proposal to build enough modules for a mixed IBL sensor scenario where 25% of IBL
modules populate the forward and backward part of every stave. Full production of planar sensors will be also made to
cover the 100% of IBL in case would be needed. The fractions of planar and 3D sensors that can be put in the IBL are
quantized by the granularity of the high voltage services, which individually bias a group of four FE-I4 equivalent area of
sensor (i.e. 4 FE-I4 out of 32 in a stave). Backward/forward symmetry restricts only to multiple of 25% the fraction of
planar/3D that can populate each stave.
Table 1 and Table 2 are a summary of the planar and 3D sensor production as at 31 st of March 2012. There are enough
sensors from both technologies to fulfil the mixed scenario, considering the expected overall yield for the module
production and stave loading.
Batch #
1
2
3
4
5
6
Total
Received wafers
20
22
18
20
17
22
119
Good DC tiles
69
76
64
70
62
83
424
Yield
86.3 %
86.4 %
89.9 %
87.5 %
91.2 %
94.3 %
89.1%
Table 1: Status of planar sensor production at the end of March 2012. IBL in the 75% of planar sensors scenario has 168 tiles.
i
CiS: Forschungsinstitut fur Mikrosensorik und Photovoltaik GmbH, Konrad-Zuse-Strasse 14, 99099 Erfurt, Germany
CNM: Centro Nacional de Microelectronica (CNM-IMB-CSIC), Campus Universidad Autonoma de Barcelona, 08193
Bellaterra (Barcelona), Spain. See http://www.imbcnm.csic.es.
iii
FBK: Fondazione Bruno Kessler (FBK), Via Sommarive 18, 38123 Povo di Trento, Italy. See http://www.fbk.eu.
ii
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Status
Produced
Wafers
Selected
Wafers
Yield
selected
FBK-A10
Completed
20
12
60 %
58
FBK-A11
Completed
12
4
44 %
14
FBK-A12
Completed
16
13
60 %
63
FBK-A13
In proc. (backup batch)
-
CNM-1
Completed
19
18
60 %
86
CNM-2
Completed
17
15
71 %
85
CNM-3
In proc.
-
-
-
-
62
62 %
306
Total
on
Good tiles
-
Table 2: Status of planar 3D sensor production at the end of March 2012. IBL in the 25% of 3D sensors scenario has 112 tiles.
Additionally to the sensors qualification and production, thin modules have been developed with both sensor
technologies, making single and double chip assemblies. The prototyping were done with 100 µm and 150 µm thin
FE-I4 chip. For IBL was decided to stay with 150 µm thickness to be on the safe side of the unexpected yields issues.
Table 3 summarizes the produced thin modules. Several of such modules have been dressed with the flex hybrid and
are assigned for “stave 0” use.
FE-I4
Thickness
Planar (200µm)
Single Chip
Double Chip
3D (230µm)
Single Chip
Total
FE-I4
100 µm
4
22
7
55
150 µm
16
17
20
70
20
39
27
125
Total
Table 3. Modules produced with thin FE-I4A chips to qualify the assembly procedure.
2
Mixed Sensor Scenario
This section describes the main changes from the IBL TDR design to fulfil the mixed sensor scenario. The impact of the the
mixed scenario on the IBL construction are on the following items:
2.1

Module layout and assembly.

Stave layout and stave flex.

Module loading on stave.

Electrical services.
Module Layout
The IBL module outlines for two-chip modules and one-chip modules are geometrical compatible; the physical size of a
two single-chip 3D sensor assemblies has the same width as a planar two-chip module. The difference in r of both sensors
is compatible with the IBL envelopes. In Table 4 are listed the geometric parameters for the sensors used in the IBL mixed
scenario.
Bare module assembly will be dressed by gluing a flex hybrid circuit on the sensor side; there will be two circuits, one for
single-chip 3D assembly and one for the planar double-chip assembly. Such circuits are shown in Figure 1. They will be
mechanically different, but electrical very similar once the test pigtail is cut. The reason for having two flex-circuits is for
easing the assembling procedure, and not for electrical connections, which will basically stay individual for each of the two
FE-I4 chips. In the case of the double-chip module flex, there will be two individual wire-bonding connectors that bring the
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signals from the stave flex “wings”. The step of such connectors, once the module are on the stave, is the same for single
and double modules; in this way the stave with the stave flex becomes compatible for either single or double chip modules.
Structure
Planar
3D
Gap b/w modules
205 µm
205 µm
Sensor thickness
200 µm
230 µm
Module width (along z)
41 315 µm
20 450 µm
Bias tab / guard-ring extension (in r)
630 µm
1 230 µm
Table 4: main geometrical parameters of the IBL sensor used for planar and 3D sensor modules.
A few special precautions have been used in the design of the module flex:

The back of the flex (which is glued on the module) has used a 25µm thick polyimide film based coverlayiv which
is rated to stand 100V/µm to hold the 1000V needed by the planar modules once they have received the life
radiation dose. It was considered to maintain the same for the 3D modules even if it is planned to have 160÷180 V
as maximum operation voltage. Increase in radiation length is low.

The high voltage capacitor will be encapsulated using an isolating resin. One candidate is a Polyurethane resin
(PUR)v that was used for the ATLAS SCT.

The clock and data signals, which are individual lines on the stave flex, are routed separately on the double
module flex to the input of two FE-I4s. Each line is terminated with a 160Ω resistance. This is acceptable being
the two stubs only 4 cm long and the frequency of the signals 40/20 MHz for clock/data. Single chip module uses
the same routing topology on two separated flexes.

FE-I4 chip ID address is differentiated by a pull-up wire-bond connection to VDD. This is needed to differentiate
the two FE-I4 chips in a module. For the double chip module an additional wire-bond is for only one of the two
chips. In case of single chip module the wire-bond of one of the two chips making a logical module will have the
wire-bond pulled out.

The module flexes are produced with a surrounding frame having precision holes for positioning pins in the
mounting jigs. When the pigtail is cut, such frame is removed and module can then picked up by vacuum tools.
This is done at the last moment, before loading to the stave.
All tooling and jigs for assembling the modules are made such to be compatible with both designs.
The module test is done using the USBPix R/O system; two USBpix systems are connected in master/slave configuration to
a double-module using the test connector and an adapter card. Both single and double-chip modules uses the same adapter
card; double module uses additional pin for the extra signal on the test connector.
iv
v
SF302C polyimide film from Shengyi (http://www.syst.com.cn/en/index.html)
VU 4453 from Peters (www.peters.de).
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Figure 1: Module Flex Hybrid for single chip (left) and double chip module (right). The flexes come with a pigtail and a test connector,
which is cut away before loading on stave. The stave flex wing is glued on the module flex and then connections are provided by wire
bonding. The double chip flex is electrically equivalent to two single chip ones.
2.2
Stave Layout
The mixed sensor scenario stave layout is shown in Figure 2. The 3D sensors populate the 2 extremities. The covered
surface with planar and 3D sensors is respectively 75 % (equivalent to 24 FE-I4 chips) and 25 % (equivalent to 8 FE-I4
chips). The modules have a fixed gap of 205 µm. The planar and 3D differ slightly in thickness: respectively 200 µm and
230 µm; and in the r being the 3D 700 µm longer. The 3D design floorplan was made compliant for the double and single
side design (active edge), where the high voltage connection is foreseen on the same side of the bump-bonding; for this
reason the sensor needs to extend over the FE-I4. The Figure 3 shows a cross section of the stave, respectively (left) at the
position of a planar double chip module and (right) at a position where a 3D single chip module is situed.
Figure 2: Stave layout for the mixed sensor scenario. 3D sensor modules populate the two stave extremities. The gap between module is
fixed of 205 mm.
Figure 3: stave cross section at position of a planar module (right) and a 3D module (left).
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Module Loading on Stave
Figure 4: Tooling to load modules on stave. On the right side are visible 4 3D single-chip sensors, while other 6 double-chip planar
sensor modules are shown toward the centre of the stave. Modules are placed with respect to the cut edge of the sensors. In the 200µm
gap between module is placed a peek spacer to electrically isolate the modules.
Figure 5
2.4
Electrical services
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Diamond Beam Monitor (DBM)
(Marko to provide 2 pages of text. Two figures: a 3D CAD drawing of the detector in the Pixel volume and a short
schedule. EDMS document with details is referenced [9])
4
References
[1] ATLAS Collaboration, ATLAS Insertable B-Layer Technical Design Report, ATLAS TDR 19, CERN/LHCC
2010-013, 15 September 2010.
[2] IBL Collaboration, Prototype ATLAS IBL Modules using the FE-I4A Front-End Readout Chip, to be published
on JINST.
[3] R. Klingenberg, D. Muenstermann and T. Wittig, Sensor Specifications and Acceptance Criteria for Planar Pixel
Sensors of the IBL at ATLAS, ATU-SYS-XX-XXXX
[4] C. Da Vià, M. Boscardin, G. Pellegrini, G-F. Dalla Betta, Technical Specifications and Acceptance Criteria for
the 3D Sensors of the ATLAS IBL, ATU-SYS-QC-0004, https://edms.cern.ch/document/1162203/1
[5] H. Kagan, M. Mikuz and W. Trischuk, ATLAS Diamond Beam Monitor (DBM), ATL-IP-ES-0187,
https://edms.cern.ch/document/1211792/1.