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Current status of the silicon strip sensor
development in Korea
1.
2.
3.
4.
5.
Introduction
Silicon Inner tracker configuration for ILC
Silicon strip sensors development
Beam test and radiation damage test
Prospect
H.J.Kim (KyungPook National U.)
For Korean silicon tracker collabortion
ACFA9, Feb. 6/2007
Silicon Tracker R&D (SiLC group)
GLD
LDC
SiD
LDC
1. VTX (FPCCD)
2. Barrel Inner tracker
3. Endcap Inner tracker
1. VTX
2. Intermediate tracker
3. Endcap tracker
AGFA9,
H.J.Kim
1. VTX
2. Whole tracker
Inner Tracker in GLD
IT
VTX
Beam Pipe IP
W-Si Cal
TPC
Concept of Silicon Strip Sensor
type
DC
AC
fabrication
readout
relatively simple
readout electronics is connected directly to the strips
- coupling capacitors are made by separating strip
implantation and metallization
- biasing resistors are made in poly-silicon
relatively complicate
readout
fabrication
position
single-sided
relatively simple
1-dimensional
double-sided
complicate, low yield
2-dimensional
poly-silicon bias
resistor
guard-ring
biasing-ring
pad
SiO2
DC pad
guard-ring
AC pad
Al
P+
N-type silicon
N+
Al
AC-type single-sided strip sensor
AGFA9,
DC-type double-sided strip sensor
H.J.Kim
DC Double-sided Silicon Strip Sensor
Hour-glass pattern on the p-side
to reduce the capacitance
in the double metal structure
Dicing line
guard-ring pad
Readout pad
d
N bulk pad
Bulk Capacitance
Leakage current
1.00E+00
3.50E-10
expected value
~55V(~92V)
1.00E-01
3.00E-10
1.00E-02
1.00E-03
2.50E-10
Capacitance(F)
current(A)
1.00E-04
1.00E-05
1.00E-06
1.00E-07
• ~10nA/strip
• <5μA/sensor
1.00E-08
1.00E-09
1.00E-10
1.00E-11
2 11.8  8.854 10 14
Vdep
1.6 10 19  ND
measured
value
Vdep < 60V
2.00E-10
1.50E-10
1.00E-10
5.00E-11
0.00E+00
0
20
40
60
80
100
120
Voltage(V)
1.00E-12
0
20
40
60
80
100
120
voltage(V)
C1T2
D4T1
E3T3
G2T3
G6T2

2εε 0
Vdep
qND
C1T3
D4T2
E4T1
G3T1
G6T3
C2T1
D4T3
E4T2
G3T2
N3T1
C2T2
D6T1
E4T3
G3T3
N4T1
C2T3
D6T2
E5T1
G4T1
N5T1
C3T1
D6T3
E5T2
G4T2
N6T1
C3T2
E2T1
G1T1
G4T3
N3T3
C3T3
E2T2
G1T2
G5T1
N4T3
D3T1
E2T3
G1T3
G5T2
N5T3
D3T2
E3T1
G2T1
G5T3
N6T3
D3T3
E3T2
G2T2
G6T1
C1T2
D3T1
E2T1
E4T3
G1T2
G4T1
C1T3
D3T2
E2T2
E5T1
G1T3
G4T2
Id v.s. V
C2T1
D4T1
E2T3
E5T2
G2T1
G4T3
C2T2
D4T2
E3T1
E5T3
G2T2
G5T1
C2T3
D4T3
E3T2
E6T1
G2T3
G5T2
C3T1
D6T1
E3T3
E6T2
G3T1
G6T1
C v.s. V
AGFA9,
H.J.Kim
C3T2
D6T2
E4T1
E6T3
G3T2
G6T2
C3T3
D6T3
E4T2
G1T1
G3T3
Fabrication of AC/DC SSD
5-inch process
AC-coupled Single-sided Silicon Strip Detector
5-inch
6-inch
thckness(μm)
380
400
35000 ×
55610 x
Area (μm2)
35000
29460
Effective area (μm2)
31970 ×
31970
51264 x
25178
SiO2 layer thickness
(nm)
Polysilicon length
(μm)
Polysilicon width
(μm)
sheet resistance(kΩ)
1000
250
Number of strips
Strip pitch (μm)
Strip width (μm)
readout width (μm)
AC TRK1
P+width:200um
Al wdth:220um
Poly-Si Resists
Test patterns
AC TRK2
P+width:300um
Al wdth:320um
AC1
AC type
Pitch:500um
Channel:64
DC1
DC TRK1
P+width:400um
Al wdth:420um
DC TRK2
P+width:600um
Al wdth:620um
DC type
Pitch:1000um
Channel:32
PIN diode
AC2
DC2
Test patterns
10
8
13500
480
~25
Type Type2
1
64
64
500
500
200
300
220
320
~400
Type Typ
1
e2
256
512
100
50
8
8
12
12
Test patterns
Test patterns
6-inch process
AC
64ch
AC
256ch
AC
512ch
AC
256ch
DC
512ch
AGFA9,
H.J.Kim
DC
32ch
Electrical test of SSD
Leakage current
1.00E-06
Electrical characteristic of
each channel in one of the AC-SSD
current(A)
1.00E-07
Current@60V
~10nA/strip
<500nA/sensor
1.00E-08
1.00E-09
0
20
40
60
80
100
120
140
160
180
200
voltage(V)
Id v.s. V
Bulk capacitance(1/F^2)
8E+20
measured value
Vdep < 60V
7E+20
6E+20
1/F^2
5E+20
4E+20
3E+20
2E+20
1E+20
0
0
50
100
150
200
voltage(V)
channel
ch1
ch2
ch3
ch4
ch5
ch6
ch7
ch8
ch9
ch10
ch34
ch35
ch55
ch56
ch57
ch58
ch59
ch60
ch61
ch62
ch63
ch64
AVE.
1/C2 v.s. V
AGFA9,
H.J.Kim
(nA)
8.1
3.0
3.1
3.2
3.3
3.3
3.4
3.5
3.6
3.7
4.5
4.4
4.3
4.2
4.2
4.1
4.0
3.9
3.9
3.8
3.8
3.9
4.0
Ccoupling@60V bias resistance
(pF)
260.0
260.0
259.0
259.0
260.0
260.0
259.0
259.0
259.0
259.0
257.0
256.0
256.0
256.0
256.0
255.0
255.0
255.0
255.0
255.0
255.0
256.0
257.3
(MΩ)
22.0
22.0
21.0
21.0
21.0
21.0
21.0
21.0
21.0
21.0
23.0
23.0
22.0
22.0
22.0
22.0
22.0
22.0
21.0
22.0
22.0
21.0
21.6
AC coupling capacitance
Coupling capacitance (Cc )
– Target value : AC1 214pF / AC2 322pF
– Measured value : AC1 177pF / AC2 257pF
– Differences are due to different permittivity depending on SiO2 layer
– And due to the limitation of SiO2 layer thickness in the our fabrication process.
Coupling capacitance of 0101AC2
AC2 ch1
AC2 ch33
AC1 ch1
AC1 ch33
AC2 ch32
AC2 ch64
AC1 ch32
AC1 ch64
AC2 ch3
AC2 ch63
AC1 ch3
AC1 ch63
AC2 ch2
AC2 ch62
AC1 ch2
AC1 ch62
280
260
AC2
240
capacitance(pF)
•
220
Target value : 322pF
200
180
160
AC1
140
Target value : 214 pF
120
100
0
40
20
60
80
100
voltage(V)
Probing for coupling capacitance measurement
AGFA9,
Measured capacitances of the AC SSD
H.J.Kim
120
Biasing structure
•
Bias resistor structure
– Purpose and advantage :
• Isolation of each strip
• Automatic biasing of total strip
• total leakage current is measured
easily with only one connection on
each surface
Length
R  Rs 
–
Width
here, Rs=20 KΩ
width=10 μm
length=12700 μm
Bias-ring Pad
DC Pad
Probing for Biasing resistance measurement
• Result
ch1
ch2
Bias resistance of 0101AC1
ch3
ch32
ch33
ch62
ch63
ch64
30
• Test patterns
25
R1
R2
R3
15
R4
length(μm) width(μm) Rs(kΩ)
resistance(ohm)
20
expected(M Ω)
measurement(MΩ)
R1
12710
10
20
25
26.04
R2
16810
10
20
34
34.04
R3
20910
10
20
42
41.85
R4
25010
10
20
50
49.38
Resistances of various test patterns
AGFA9,
10
Target value : 25 MΩ
5
0
0
20
40
60
voltage(V)
80
100
120
The Bias resistance of the AC-coupled SSSD
H.J.Kim
Silicon Strip Sensor Summary
5-inch double-sided process
• yields
type
DC-type
Type 1
AC-type
Various patterns
singlesided
90%
doublesided
< 30%
80%
Type 2
N/A
5-inch single-sided process
AC TRK1
P+width:200um
Al wdth:220um
Poly-Si Resists
Test patterns
AC TRK2
P+width:300um
Al wdth:320um
DC TRK1
P+width:400um
Al wdth:420um
DC TRK2
P+width:600um
Al wdth:620um
AC1
• fabrication line
AC type
Pitch:500um
Channel:64
DC1
DC type
Pitch:1000um
Channel:32
PIN diode
line
DC-type
AC2
AC-type
DC2
Test patterns
Test patterns
5 inch
6 inch
8 inch
double/single-sided
single-sided
single-sided
single-sided (in
progress)
thickness ( 725 um, can be thinned ~500
um)
Test patterns
6-inch single-sided process
AC
256ch
AC
64ch
AC
512ch
AC
256ch
DC
512ch
AGFA9,
H.J.Kim
DC
32ch
Radioactive source test block diagram
Photodiode sensor of HPK
Pre-amp. Amp. Discriminator
Trigger Sensor
Pb
Pb
Sensor
Light-tight box
90Sr
source
Pre-amp.
Amp.
DSO
Trigger
512ch Double-sided Silicon Strip Sensor
Xilinx
ADC
FADC4VA
AGFA9,
H.J.Kim
PC
Source Test Measurement Result
• Signal-to-noise ratio is measured to be 25.0
AGFA9,
H.J.Kim
Beamtest & Radiation damage test
• Korea Institute of Radiological And Medical Science
• Beam energy from 35 ~ 45MeV
• Beam current from 0.2nA ~ few micro A
AGFA9,
H.J.Kim
Front-end electronics for SSD (DC type)
VA interface
VA chip
SSD
hybrid
OpAmp.
FADC4VA
VA Hybrid board
This VA1 chip has 128 channels, and a low noise charge sensitive
preamp, a shaper, and a sample and hold for each channel.
Analog signals are serially clocked out by control via a shift register.
FADC4VA board
VA Interface board
Power supply to VA and silicon strip sensor
Logic converter for interfacing between VA and Xilinx
AGFA9,
Xilinx chip on Flash ADC4VA board makes a control logic and distributes it to
VA and ADC chip converts analog signal to digital signal.
Digital signal from ADC is sent to PC through USB2 bus for data analysis
H.J.Kim
Block Diagram of Experimental Set-up for Beam Test
Collimator (Al)
Collimator (Pb)
Liquid
Scintillator
Proton Beam Pipe
VA Hybrid
VA Interface
thin Cu windows
FADC4VA
PMT
HV
Amplifier
DSO
Discriminator
Light-tight box
Control
PC
(To outside)
Gate & Delay
generator
Trigger
Ethernet Hub
AGFA9,
PC
H.J.Kim
Experimental Set-up
collimator
Silicon strip sensor
Al light-tight box
Liquid Scintillator and PMT for
trigger
AGFA9,
USB2
H.J.Kim
VA1_prime2.3
Test results
Simulated absorbed energy spectrum
of 37.5 MeV proton impinging onto
380 um silicon sensor
This problem is well
understood : random trigger
due to misalignment
AGFA9,
H.J.Kim
Results of beam test : S/N
• The SNR is defined as the ratio of the most probable energy deposit in the
sensor to the noise RMS.
• The estimated SNRs of channels 0 ~ 22 have large errors because of only
few properly triggered events. Channels 23 ~ 31 show good SNRs of 164 ~
67 for as 37.5 MeV proton, which corresponds to be 16.4 ~ 6.7 for a
Minimum Ionizing Particle.
AGFA9,
H.J.Kim
Radiation damage test
• Irradiation
45 MeV proton beam from MC-50 cyclotron at KIRAMS fluence
normalization based on NIEL scaling hypothesis
– for different particles
– for different energy ranges
• The standard for particle
fluence is to normalize all
damage to the equivalent
damage caused by 1 MeV
neutron.
 eq   tot
κ is “hardness factor” = D(E)/Dneutron(1MeV)
Energy dependence on NIEL in silicon
for different particle types and energies
Radiation damage test results
• Increase in leakage currents
Φeq=3.0×108
Φeq=1.6×109
Φeq=1.6×1010
Φeq=1.6×1011
Leakage currents as a function of bias voltage
Radiation damage effects
Fluence dependence of leakage
current
Fluence independence of damage
parameter
ROSE data
•current increase is strictly proportional to fluence
•Damage induced bulk
•current related damage rate α is expected
to be independent of irradiation
•
I / V     eq
• α can be used to monitor the particle fluence
AGFA9,
H.J.Kim
More Beam Test at KIRAMS on 2007 :analysis ongoing
AGFA9,
H.J.Kim
Beam Test at CERN on 2006 : analysis on going
150 GeV
electron beam
AGFA9,
H.J.Kim
Summary and Prospect
• Double sided silicon sensor, DC-type single
sided silicon sensor and AC-type single sided
silicon sensor was successfully produced and
tested.
• Beam test and radiation damage shows that
developed sensor can be used for the ILC
environment.
• Radioactive source test and beam test
showed that S/N ratio is good enough for
the ILC environment.
• Electronics R&D is under progress.
AGFA9,
H.J.Kim