Transcript bez titulu

Silicon sensor design and prototyping
for the TESLA W-Si ECal
Vaclav Vrba
Institute of Physics, AS CR, Prague
Jeju Island, Korea, August 26-30, 2002
1
Vaclav Vrba, Institute of Physics, AS CR
Outline
• Sensor tile outer dimensions
• Pad array design consideration
• Sensor pre-prototype production
• Tests outlines
• Conclusions
Jeju Island, Korea, August 26-30, 2002
2
Vaclav Vrba, Institute of Physics, AS CR
Sensor tile outer dimensions
Outcome from the meeting
at EP:
- 4” high resistivity wafers
- tile side: 62.0+0.0
-0.1 mm
- scribe line: 100 m
- scribe safety zone: 200 m
- guard ring width: cca 750 m
(cca 1.5 * wafer thickness)
1.0 mm
The dead zone width is
about 1 mm
Wafer book keeping information
Jeju Island, Korea, August 26-30, 2002
3
Vaclav Vrba, Institute of Physics, AS CR
On-sensor electrical elements
Along with the diodes, the technique used for fabrication of bias
resistors and coupling capacitors represents an important issue:
a) polysilicon resistors – production of the tile needs about 7-8 masks;
can be the source of additional yield reduction.
b) punch through resistors – production of the tile needs about 5
masks; easy to produce – needs to check whether required
parameters can be achieved.
c) deposited resistors (amorphous silicon) – achievement of EP;
- needs about 4-5 masks for production of the diodes array; on top
of that additional fabrication of resistor and capacitors.
d) ion implantation resistors – not considered here.
Jeju Island, Korea, August 26-30, 2002
4
Vaclav Vrba, Institute of Physics, AS CR
Design consideration: Polysilicon resistors
Bias lines
Top view
Bias
resistor
Coupling
capacitor
Direct
contact on
diode – e.g.
for testing
Vertical
cross section
Jeju Island, Korea, August 26-30, 2002
5
Vaclav Vrba, Institute of Physics, AS CR
Design consideration: Punch through resistors
Bias lines
Top view
Bias
resistor
Coupling
capacitor
Direct
contact on
diode – e.g.
for testing
Vertical
cross section
Jeju Island, Korea, August 26-30, 2002
6
Vaclav Vrba, Institute of Physics, AS CR
Deposited resistors – before deposition
Jeju Island, Korea, August 26-30, 2002
7
Vaclav Vrba, Institute of Physics, AS CR
Deposited resistors – after deposition
Bias lines
e.g.Wire bonding,
Flex cable gluing,
etc.
Jeju Island, Korea, August 26-30, 2002
8
Vaclav Vrba, Institute of Physics, AS CR
ECal slab components
Front End electronics
.
Silicon sensor array
Aluminum
shielding
sensor pad
1 x 1 cm2
Cooling system
n-p junction:
vertical cross
section
Jeju Island, Korea, August 26-30, 2002
(C / W) structure type
9
H
Vaclav Vrba, Institute of Physics, AS CR
Design consideration
a) polysilicon resistors:
should not be a problem to have resistors  10 M;
capacitors  1-10 nF.
b) punch through resistors:
resistors to be tested; if acceptable then it is a simple solution;
capacitors as a).
c) deposited resistors:
will be considered in the first prototype submission  to test the
deposition technology of capacitors and resistors
Compatibility of process for variants b) and c) on one wafer. Option c)
is a baseline for the first prototype.
Jeju Island, Korea, August 26-30, 2002
10
Vaclav Vrba, Institute of Physics, AS CR
Pre-prototyping
using existing masks:
- elaborate the technology process of sensor
fabrication;
- estimate the quality of sensors;
evaluate some effects of high resistive silicon,
guard rings, scribe lines, etc.
we used following input material:
- #wafers
thickness [m]
5
SSP Wacker
530
5
DSP Topsil
500
5
DSP Topsil
300
5
DSP Topsil
250
Jeju Island, Korea, August 26-30, 2002
11
Vaclav Vrba, Institute of Physics, AS CR
Pre-prototyping
Active area cca 0.25 cm2
Wafer diameter: 100 mm
Wafer backside all Al metallized
Jeju Island, Korea, August 26-30, 2002
12
Vaclav Vrba, Institute of Physics, AS CR
Tests outlines
Diode tests:
a) C-V curves:
determination of Vfull-depletion; Vop = Vfulldepletion + 50 V.
b) I-V curves:
- Vbreak-down  Vop
- Ileak @ Vop < cca 30 nA/cm2
c) Long term stability tests:
- Ileak @ Vop .
Jeju Island, Korea, August 26-30, 2002
13
Vaclav Vrba, Institute of Physics, AS CR
Parameters of pre-prototype sensors
thickness=250μm, ρ≈4kΩcm
Jeju Island, Korea, August 26-30, 2002
Ufd
14
Vaclav Vrba, Institute of Physics, AS CR
Parameters of pre-prototype sensors
thickness=530μm, ρ≥5kΩcm
thickness=500μm, ρ≈12kΩcm
Ufd
thickness=300μm, ρ≈12kΩcm
Ufd
thickness=250μm, ρ≈3kΩcm
Ufd
Jeju Island, Korea, August 26-30, 2002
Ufd
15
Vaclav Vrba, Institute of Physics, AS CR
Long term current stability on a tile
Measured @ 150V
x 10s
time
Jeju Island, Korea, August 26-30, 2002
16
Vaclav Vrba, Institute of Physics, AS CR
Summary and next steps
• A lot of pre-production sensors has been
produced at the Czech producer Tesla Sezam.
Sensor parameters comply with QA criteria for
CALICE ECal.
• Full size prototype sensors are in production
and will be available for testing in October.
• Mechanical assembly and tests with electronic
chips, which are expected to be available in
September, will follow.
Jeju Island, Korea, August 26-30, 2002
17
Vaclav Vrba, Institute of Physics, AS CR