Outline
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.
introduction
yield
H8 – ATLAS beam tests
radiation damage tests
a puzzle
active edges
speed
tasks / groups
SNF r & d fabrication run
SINTEF fabrication run
conclusions
1
Data, Fabrication Work From:
Cinzia Da Via, Jasmine Hasi, Steve Watts (Manchester University)
Chris Kenney (Molecular Biology Consortium)
Sherwood Parker (University of Hawaii)
Angela Kok, Thor-Erik Hansen, Trond Hansen, N. Lietaer (SINTEF)
Sally Seidel, Martin Hoeferkamp, . . (University of New Mexico)
Kevin Einsweiler, Maurice Garcia-Sciveres (LBL)
Norbert Wermes, Markus Mathes, Lars Reuen, . . (Universität Bonn)
S. Pospisil, Vladimir Linhart, Tomas Slavicek, Tomas Horadzov, . .
(Czech Technical University)
G. Anelli, P. Jarron, M. Despeisse (CERN – Microelectronics group –
high speed work)
J. Morse (European Synchrotron Radiation Facility), Eric Perozziello
2
Planned steps for the full-3D project include:
1. If needed, complete some or all of the remaining wafers in the current
run. (We already have enough for the FP420 part of the fall CERN
tests, and the plan is to have SINTEF provide sensors for ATLAS
part.)
2. Continue test beam work (Sept. – Dec. 2007).
3. Start and complete a developmental fabrication run (Sept. 2007 –
Mar. 2008).
4. Test sensors from that run (Jan. – June 2008).
5. Test samples fabricated by SINTEF (by September 07).
6. Neutron irradiation, up to SLHC fluences, for 4-electrode per pixel
sensors.
7. Start proton irradiations of 2-, 3-, and 4-electrode per pixel sensors.
8. Start advanced planning for B-layer replacement items that could
affect current developments (December 07 – August 08).
9. Pre-production for the B-layer replacement (January 2009).
3
Outline
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.
introduction
yield
H8 – ATLAS beam tests
radiation damage tests
a puzzle
active edges
speed
tasks / groups
SNF r & d fabrication run
SINTEF fabrication run
conclusions
4
Figure 6. Stanford clean room near diffusion
furnaces, looking in the direction of the red arrow.
5
Pictures of clean rooms like the one preceding
are familiar, but many other things are needed
for high yield, for example: specific, careful
checking of the results of each of the 37 main
steps and of the many sub-steps, cleanliness not
just of the room and air, but of everything used –
tools, chemicals, cassettes, etc.
The deep etching may leave an uneven surface
that makes it difficult to spin on a uniform layer
of photoresist for a following lithography step. If
this step is a deep etch, a thick resist is needed.
They seem to have a higher level of particulates
and clumps of resist.
Active edge fabrication requires support wafers,
which must be oxide-bonded to the sensor wafer
under extremely clean conditions.
6
The following specific steps were added to the fabrication
procedure for the two-order-of-magnitude larger, 9 cm2 planar /
3D active edge Totem sensors:
1. The wafers were carefully inspected after every litho step. If
defects were seen, the resist was removed, new resist was
applied, and the wafers were re-spun and re-exposed.
2. Defects in the thick resist used for the trench etch were
covered with polyimide.
3. The surface planarity in the region of the dips at the centers of
the poly-filled electrodes was improved by etching the poly off
the top surface, and then repeating the fill and etch procedure.
(Use of CMP would be better.)
4. The plasma dice lane was widened from 50 microns to 120
microns. The more open trench prevented the formation of
silicon chips along the trench edges. This seems to have
eliminated this defect class, which caused a 25% loss for the first
batch.
5. Evaporated aluminum instead of sputtered gold was used for
7
the backside contact.
Add Yield Improvement Steps – First 10 of 107 steps:
2) CLEAN at WBNONMETAL - YIELD FACTOR: Change chemicals/ Do at
least two spins on the spin dryer
3) CLEAN at WBDIFF - YIELD FACTOR: Change chemicals/ Do at least two
spins on the spin dryer
5) FIELD IMPLANT BOTH THE FRONT AND BACK SURFACES OF THE
WAFERS - YIELD FACTOR : When picking up the double-sided device
wafers, only pick up from the laser edged area of the wafer and Use clean
tweezers
6) CLEAN at WBNONMETAL - YIELD FACTOR: Change chemicals / Do at
least two spins on the spin dryer
7) CLEAN at WBD - YIELD FACTOR: Change chemicals / Do at least two
spins on the spin dryer
8) GROWN THERMAL OXIDE USING TYLAN1-4 - YIELD FACTOR: Load with
delrin tweezers and let wafers cool down before unloading the wafers from
the furnace with the delrin tweezers.
9) PREPARE SURFACES FOR FUSION BONDING AT WBDIFF - YIELD
FACTOR: Change chemicals, definitely for the HCL step prior to fusion
bonding the wafers.
10) FUSION BOND - YIELD FACTOR: Wear face shield to reduce particle
generation. Perform after hours or on weekend when there aren’t many
8
people around. (Seems not to be needed now.)
Test Metal
Over 17,000 electrodes per chip
Active edge 4 cm long per chip
One flaw and the chip is useless
Use temporary aluminum pattern to
characterize the diodes
Temporary metal connects the electrodes into
a set of 9 to 11 “strips” per chip
Remove temporary aluminum after testing,
then deposit final metal, etc.
9
Test Metal
3E test pattern – interdigitated “strips” of
alternating N and P electrodes
Each “strip” equals 320 ATLAS pixels
ACTIVE EDGES
P ELECTRODES
N ELECTRODES
10
Preliminary Tests
• 3 Wafers Test So Far at 40 Volts
• Two have Contact Problem
– Hope to Solve
• Of 40 Chips Tested, 32 Work
• 80% Yield
11
Contact Problem
Contact Analysis
• Only Affects n+
Electrodes
1.4
1.2
1
Current
• Likely Affects about Half
of Wafers
1.6
0.8
0.6
0.4
0.2
0
-0.2 0
1
2
3
4
5
6
7
Location (Column)
• Correlated with
Residual, Hazy Film
• Additional Plasma and
Wet Etching Ameliorates
the Effect
Hazy Film
12
Plan
• Understand/Fix
Contacts
• Test Remaining 7
Wafers
• Finish Processing All
10
• 2 to Bonn/IZM for
Mechanical Sawing and
Bump Bonding
13
Outline
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.
introduction
yield
H8 – ATLAS beam tests
radiation damage tests
a puzzle
active edges
speed
tasks / groups
SNF r & d fabrication run
SINTEF fabrication run
conclusions
14
Aug. 17 Sept. 3, 2006
H8 Cern beam line
x
scint.
Telescope by Lars Reuen
(Bonn group)
3D
x
scint.
y
y
100 GeV pTriggers: 3x3 mm2 , 12x12 mm2
15
16
CERN, H8 beam line, August 2006, Beam telescope, detectors under test
17
(3D – ATLAS readout is tilted)
18
Outline
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.
introduction
yield
H8 – ATLAS beam tests
radiation damage tests
a puzzle
active edges
speed
tasks / groups
SNF r & d fabrication run
SINTEF fabrication run
conclusions
19
Radiation hardness tests Praha, 2005
Volume = 1.2 x 1.33 x 0.23 mm3 = 0.37 mm3
(pixel volume = 0.18 mm3)
Inter-electrode spacing = 71 mm
n-electrode readout
n-type before irradiation
12 kW cm
Irradiated with neutrons (Praha)
Name Fluence
Fluence
[n1MeV/cm2] [p/cm2]
7F
3.74e15
6.0e15
7A
5.98e15
9.6e15
7D
8.60e15
1.4e16
20
Peak amplitude versus bias voltage scan of the measured samples. The
Non-irradiated sample is visible at the top of the plot and shows a full
depletion voltage of 15V, while the plateau amplitude is reached at 160V for
21
the most highly irradiated sample.
0.002
Amplitude [V]
0
15
-0.002
8.6 e
-0.004
5.98e
-0.006
n/cm
15
3.7e
15
2
n/cm
n/cm
2
2
-0.008
NON IRRADIATED
C. DaVia et al March 06
-0.01 -8
-8
-8
-8
-8
-8
-3 10 -2 10 -1 10
0
1 10
2 10
3 10
Time [s]
22
Averaged radiation induced volumetric leakage current at 20oC
versus fluence
23
Full depletion voltage versus fluence (n/cm2)
24
1.8 x 1016p/cm2 =
10 years SLHC at 1035cm-2s-1
At r=4cm
3x1015 p/cm2 =
10 years LHC at 1034 cm-2s-1
At r=4cm
2
Fluence [p/cm ]
0
8 10
15
16
1.6 10
16
2.4 10
16
3.2 10
100
Signal efficiency [%]
80
60
3D silicon C. DaVia et a. March 06
Diamond W. Adam et al.
NIMA 565 (2006) 278-283
40
20
n-on-p strips P. Allport et al.
IEEE TNS 52 (2005) 1903
n-on-n pixels CMS T. Rohe et al.
NIMA 552(2005)232-238
0
0
Simulation by
S. Watts/Brunel
5 10
15
16
C. Da Via'/ Aug.06
16
1 10
1.5 10
2
Fluence [n/cm ]
2 10
16
Signal Efficiency versus 1MeV equivalent neutron (bottom legend) and 24
Gev/c proton fluence (top legend) per cm-2. The data are from the 3D
samples, from silicon pixel [16] and strips [17] and from pixilated diamond
25
detectors [18].
26
Outline
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.
introduction
yield
H8 – ATLAS beam tests
radiation damage tests
a puzzle
active edges
speed
tasks / groups
SNF r & d fabrication run
SINTEF fabrication run
conclusions
27
28
no low-side tail, so
very few, if any, events
with partial charge
collection efficiency
29
Outline
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.
introduction
yield
H8 – ATLAS beam tests
radiation damage tests
a puzzle
active edges
speed
tasks / groups
SNF r & d fabrication run
SINTEF fabrication run
conclusions
30
Reasons for dead borders on standard planar
technology sensors
a
b
d
c
a.
b.
c.
d.
space for guard rings
sawed edges connecting top and bottom are conductors
chips and cracks are also conducting and can reach inside the
edges
the field lines bulge out, and should be kept away from b and c
31
Active Edges
oxide
p
p
n
1. etch border trenches
2. diffuse in dopant
n
3. grow protective oxide
cover
sensor wafer
4. fill trench with poly
support wafer
5. vertical, directed etch
(to dotted lines)
oxide
6. turn off sidewall
protection step
p
p
n
support wafer
n
oxide
7. isotropic etch to oxide
stop
8. additional steps are not
included on this slide
(and note, bonding
oxide to support wafer
not colored )
9.
n and p electrodes can32
be
reversed
45-54
36-45
27-36
18-27
9-18
54
45
0
0-9
36
60
27
18
9
0
120
180
microns
240
300
360
Current from scan in an x-ray microbeam, of another 3D sensor with
a photomicrograph of the corresponding part on the right. Grid
33
lines are spaced 10µm apart.
28
Cinzia Da Via
34
line
scan
50
ID 3rd harmonic
100
1.73keV
p+ electrode
0
0
20
40
60
Energy (keV)
electrode pitch 150mm
Window count integral to 24.9keV
ADC counts
linescan through p+ electrode
column and across active edge
6000
15mm
3000
6000
0
230
235
240
245
250
255
260
265
thresh6.5keV
thresh10keV
thresh15keV
3000
edge response
over ~10mm
15V bias
0
100
200
300
position (microns)
35
270
Totem X5 test beam at CERN.
1. The 3D planes: 16 -- 200 µm (y) by 40 -- 100 µm (x) cells, n bulk and edges.
2. They are tied together in x-rows for a y readout using SCTA integrated
circuits and a scintillator trigger.
3. The 3D planes are centered between a 4-plane silicon strip telescope with 4
y planes and 2 x ones. σy = ± 4 µm.
4. The beam was set for 100 GeV muons.
36
Some results from the CERN X5 beam test
(100 GeV muons)
Measured hit position in 3D
sensor plane #3 vs. predicted
position from beam telescope.
Fitted 3D sensor width = 3,203 ±4µm.
Drawn width = 3,195 µm.
Sensor
efficiency = 98%. System efficiency less
due to DAQ, triggering electronics. 37
X5 (Totem) beam test – cell uniformity measurements
Observed 3D hits / predicted telescope hits as a function of position within the 100 µm x
200 µm non-edge cells. To improve statistics, the hits for all cells are superimposed.
(Note: 3D discriminator thresholds can magnify the true collection efficiency differences.)
n
Left above: grid with p
electrodes on corners.
Right above: grid with p
electrodes in center.
p
38
Center: data is further projected onto one quadrant. Null-field points are at upper
right and lower left.
1. It was expected the grain boundary regions in polycrystalline
silicon might be a large source of leakage current if the depleted
region with its fields reached it. So the implants in the surrounding
single crystal region were designed to stop the field.
2. Electrons at room temperature diffuse about 1 μm in 1 ns.
3. Their lifetime in poly is proportional to the grain size and is 0.5 ns
for 1 μm grains.
4. Our grain size is about 2 – 3 μm. So electrons in poly might be
expected to diffuse no more than a few microns before capture.
5. It would then be expected ionization created in the outer regions
of the poly electrodes might have a probability p, with 0 < p < 1, of
escaping to the electric field region and to being counted.
6. This should result in pulse height distributions with low-side tails.
7. But the results on slides 28, 29 and 35 disagree.
39
Some possible sources of the observed differences in
collection efficiencies seen from n and p electrodes:
1. Differences in electrode diameters and
thermal history (increased Dt increases
dopant diffusion distances and radius
of built-in fields, and can increase grain
sizes – the N electrodes were done
first).
electron lifetime
vs. grain size
2. The dopant gasses available at SNF
produce an oxide layer on the hole
surface which remains after the hole is
filled; they may differ in radii and
effectiveness as barriers.
3. Electrons and holes have different
diffusion rates and lifetimes in the poly
electrodes.
4. Note: The CERN -- X5 beam test data
shows counts, not signal heights, and
discrimination levels will affect the
results.
(from Kamins –
Polycrystalline silicon
for integrated circuit
applications)
40
Outline
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.
introduction
yield
H8 – ATLAS beam tests
radiation damage tests
a puzzle
active edges
speed
tasks / groups
SNF r & d fabrication run
SINTEF fabrication run
conclusions
41
42
43
44
First, one problem with betas: an
example of a possible angled track
distorting the pulse shape.
(We will need real test beam data)
trigger
adjacent
adjacent
3d.speed.20v.02
2
1
0
-1
-2
-3
-4
-5
-30
-20
-10
0
10
20
30
time (ns)
45
trigger
adjacent
adjacent
two triggers later, a clearer example
3d.speed.20v.04
2
1
0
-1
-2
-3
-4
-30
-20
-10
0
10
20
30
time (ns)
46
a track in two and an induced pulse
in the other (green) neighbor
trigger
adjacent
adjacent
3d.speed.20v.09
4
2
0
-2
-4
-6
-8
-30
-20
-10
0
10
20
30
time (ns)
47
Uncollimated 90Sr betas, 20 C, hex sensor
(20V bias) to 0.13 μm current amplifier,
self-triggers, events 1 and 99 of 99
trigger channel
adjacent channel
adjacent channel
Sr - 90, 20V, event 99
2
2
0
0
pulse height (mV)
pulse height (mV)
Sr - 90 20V, event 01
-2
-4
-6
-8
-10
-30
-2
-4
-6
-8
30 ns
-20
-10
0
time (ns)
10
20
30
-10
-30
30 ns
-20
-10
0
10
20
30
time (ns)
48
trigger channel
adjacent channel
adjacent channel
0.8 ns rise time pulse to cal. input
2
pulse height (mV)
0
-2
-4
-6
-8
-10
-30
-20
-10
0
10
20
30
time (ns)
49
Estimate the time resolution at room temperature with
• the hex sensor, and
•a preliminary version of a 0.13 µm integrated circuit readout
•using data from un-collimated 90-Sr βs (but only with tracks in the central channel).
•(A wall-electrode with parallel plates would give shorter times, but the hex sensor
already has the same output rise time as a 0.8 ns input rise time pulse generator, so
the output shape is primarily determined by the amplifier, not the sensor).
•To simulate a constant fraction discriminator set at 50% (where slope is steepest):
•Fit leading baseline, and measure noise,
•Fit top and find halfway point,
σ-noise
ΔT
•ΔT = σ-noise / slope
•With wall-electrode sensor and a parallel beam, might do better fitting entire pulse.
The measured ΔT values for first 20 pulses (other than two channel cases):
average 131 ps, maximum 286 ps, minimum 40 ps. (partial, very
preliminary)
If random, 9 layers would give 44, 95, and 13.3 ps. But watch out for beam pipe fields!
And unexpected systematic errors should be expected.
50
Outline
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.
introduction
yield
H8 – ATLAS beam tests
radiation damage tests
a puzzle
active edges
speed
tasks / groups
SNF r & d fabrication run
SINTEF fabrication run
conclusions
51
Task/Group
Bonn
Freiburg
Genova
Glasgow
Fabrication
Assembly *
Test Beam, pixels
x
x
x
x
x
x
Lab tests Radiation
damage
Data analysis, simulation
LBL
x
Irradiation**
Lab tests pixels
Hawaii
MBC
Stanford
x
x
x
x
Manchester
Oslo
x
x
x
x
x
x
x
x
SINTEF
CTU
Praha
U. New
Mexico
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
* The CERN silicon facility will also be used
**Ljubljana, Los Alamos, and CERN are also other proposed irradiation facilities.
52
Outline
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.
introduction
yield
H8 – ATLAS beam tests
radiation damage tests
a puzzle
active edges
speed
tasks / groups
SNF r & d fabrication run
SINTEF fabrication run
conclusions
53
Possible Topics for R&D investigations
1) electrodes
a) poly crystallization
b) doping: lifetime x mobility – affects efficiency?
2) Contacts – yield
a) geometry / topography
b) films?
3) CMP (chemical – mechanical polishing)
4) Back side bias contacts
5) Surface studies: Q (ox), etc.
6) Temporary test structure W, Al, ...
7) ALS beam test: charge collection from tracks in electrodes
8) 5- electrode pixel
9) Breakdown, radiation hardness, capacitance optimization.
This can take a lot of time as it is a lot of work. Just getting the
CMP going and a process developed for us could take a month or
more. We might also have to purchase special and costly slurries.
54
ATLAS R&D
SNF
Poly Runs
Masks
Wafers FZ
Wafers CZ
Equipment
Implants
Travel CERN
Travel LBL
Eng. Eric
Phys. CJK
A
8
4
14
25
50
months 2500
batches 1000
masks
600
wafers
80
wafers
23
per month
per batch
per mask
per wafer
per wafer
4
1
8
30
3
batches 500
trip
2000
trips
51
hours
80
months 10000
per batch
per trip
per trip
per hour
per month
Sum
Cost
20000
4000
8400
2000
1150
5000
2000
2000
408
2400
30000
CJK, JH, EP
Upgrade Mtg.
ALS beam test
77358
OVERHEAD (U. Hawaii is 20.6% on first $25K)
55
ATLAS R&D B (partial r&d, no tests, limited ability to study electrode efficiency, etc.)
Cost
SNF
6
Poly Runs
0
Masks
8
Wafers FZ 15
Wafers CZ 25
Equipment
Implants
2
Travel CERN 0
Travel LBL 0
Eng. Eric
0
Phys. CJK
2
Sum
months
batches
masks
wafers
wafers
2500 per month
1000 per batch
600 per mask
80 per wafer
23 per wafer
batches
trips
trips
hours
months
500 per batch
2000 per trip
51 per trip
80 per hour
10000 per month
15000 CJK, JH only
0
4800
1200
575
2000
1000
0 Upgrade Meeting
0 ALS beam test
0
20000
44575
OVERHEAD
56
Outline
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.
introduction
yield
H8 – ATLAS beam tests
radiation damage tests
a puzzle
active edges
speed
tasks / groups
SNF r & d fabrication run
SINTEF fabrication run
conclusions
57
SINTEF
1. They have all the needed machines except boron diffusion which they
will get. (We will do that step for them on this first run.)
2. They have started a fabrication run.
3. P-spray implants and oxide-bonding to support wafers have been done.
4. They have successfully etched holes. (See next two slides.)
5. They use a different mask material for their plasma etching.
6. It makes better masks, but any residue could cause problems for later
steps.
7. They now have a cleaning regime that has given satisfactory results on
a SIMS test (secondary ion mass spectroscopy – a primary ion beam
sputters out secondary ions which are analyzed – less than 1:1014, both
on the surface and in the holes).
8. They will be sent here for a TXRF test (total x-ray reflection
fluorescence – a SNF requirement – more sensitive to some
contaminants, but only for surfaces).
9. They do not have CMP (chemical-mechanical polishing), which is now
being installed in SNF.
58
59
60
Outline
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.
introduction
yield
H8 – ATLAS beam tests
radiation damage tests
a puzzle
active edges
speed
tasks / groups
SNF r & d fabrication run
SINTEF fabrication run
conclusions
61
Conclusions –
Full-3D, active-edge sensors:
•
•
•
•
•
•
•
•
We have adequate fabrication yields for now.
But specific steps should still be improved.
Test beam results with ATLAS readout OK.
Neutron irradiation to 1016 protons/cm2 OK.
Must now use protons (oxide damage, etc.).
Non-zero electrode efficiency is a surprise.
We should try to improve it.
An r & d fabrication run at SNF will be important
for that and many other reasons.
• SINTEF has started on an ATLAS sensor
fabrication run.
62