Development and Performance of
Kyoto’s X-ray Astronomical SOI pixel sensor Sensor
T.G.Tsuru (tsuru@cr.scphys.kyoto-u.ac.jp)
S.G. Ryu, S.Nakashima, Matsumura, T.Tanaka (Kyoto U.), A.Takeda, Y.Arai (KEK),
K.Mori,Y.Nishioka (U. Miyazaki), T.Kohmura (Kogakuin U.) + SOIPIX group
T. Imamura, A. Iwata, T. Ohmoto, T. Maeda (A-R-Tec) for Chip Design

Publication
Ryu et al.
Ryu et al.
Tsuru et al.
Ryu et al.
Nakashima et al.
Nakashima et al.
Ryu et al.
Takeda et al.
Tsuru et al.
Nakashima et al.
MatsumuraIEEE NSS 2010, Conf. Record
IEEE TNS 58, 2528 (2011)
IEEE NSS 2011
IEEE NSS 2011, Conf. Record
IEEE NSS 2011, Conf. Record
Physics Procedia 37, 1373 (2012)
IEEE TNS 60, 465 (2013)
IEEE TNS 60, 586 (2013)
SPIE Astro2012
NIM A, Accepted (2013)
NIM A in Prep.

XRPIX1-CZ -FI
XRPIX1-CZ-FI
Review
Event-Driven Readout system
XRPIX-ADC1
XRPIX1-FZ-FIXRPIX1b-CZ-FI, Inter-pixel cross-talk
Event-Driven Readout with XRPIX1b-CZ-FI
Review
XRPIX2
Charge Collection Efficiency

20131009_SDW2013_XRPIX_v81

Talk Plan

• “XRPIX”

the Kyoto’s X-ray Astronomical SOI pixel sensor• Spectral Performance• Depletion Layer• Trigger output and Event Driven Readout• Charge loss at the interface between thedepletion layer and SiO2 insulator

2

The standard Imaging Spectrometer ofmodern X-ray astronomicalsatellites
l.
[Vol. 59,
Suzaku「すざく」 XIS

3X-ray CCD• Fano limited spectroscopy with thereadout noise ~3e- (rms).
• Wide and fine imaging with the sensor•size of ~20-30mm pixel size of ~30μm□
High QE by BI and thick depletion(200μm for ASTRO-H).

• Non X-ray background above. 5. The CCD and heat sink assembly installed in the base. Theer shield is removed in this picture.

10keV is too high to study faintsources.
lso supply
reverse current to the TEC, to warm up thechip in orbit. The CCD temperature may be raised a fewf ◦C above that of the base. In practice, the requirement toexcessive mechanical stresses due to differential thermal
nsion of the copper heat sink relative to the alumina CCD
rate imposes an upper limit on CCD temperature in this. For example, with the heat sink at a typical operating
erature of −35 ◦C, we have adopted a maximum allowCCD temperature of about + 15 ◦C. The CCD temperature
limit is higher at higher heat sink temperatures.

• The time resolution is too poor(~sec) to make fast timing
obervation of time variable
sources (eg. BH and NS).

Non X-ray backgroundof Suzaku XIS (BI)Due to high energy
particles on orbit.

Sensor(high ρ,depleted Si)“XRPIX” = Monolithic SOI pixel sensor
for future X-ray astronomical satellites
X-rayV_backElectronInsulator(SiO2)
Fast CMOS(low ρ Si)

X-ray

HoleP+CMOS
Readout

CMOS
Readout

CMOSReadout

V_sig

BPW
CMOSReadout

4

non X-ray
BGD(high energyparticle)

scintillatorTimeon-board processor
Our SOIPIX (XRPIX)
Each pixel has its own trigger and Very low BGD by anti-coincidence
analogue readout CMOS circuit.
(1/100 of CCD at 20keV)

Imaging
Energy Band
Target Spectroscopy
Spec. Timing
Dark Current
Function
Non X-ray BGD

area > 25x25mm2, pixel ~ 30-60μm□ (1” @ F=9m)
0.3-40keV with BI (<0.1μm), and thick depletion (>250μm)
ΔE < 140eV @ 6keV, Fano limit (Req.<10e-, Goal < 3e-)
<1μsec<2pA/cm2 (assuming working T = -40℃)
Trigger signal & pixel address output, built-in ADC (option)
5e-5 c/s/keV/10x10mm2 at 20keV (1/100 of CCD)

5

XRPIX Series - Road Map 2010

2011

1.0mm

2012
4.0mm

1.0mm

2013
4.5mm

XRPIX1 XRPIX1b
XRPIX2XRPIX2b

2014
1.0mm

1.0mm

XRPIX3

XRPIX3b

2.9 mm

2.9 mm

2.4 mm 2.4 mm

First Model
6.0 mmTriggerOutputMiddle Size2.4mm

XRPIX
ΔΣ-typeADC

A-R-Tec PROPRIETARY/CONFIDENTIAL

2.4mm

2.4 mm56.0 mm

Buttable

ChargeSensitive AMP

6XRPIX1: Pixel Circuit
TriggerComparator
VDD18

Trigger
output

GND18

AnalogoutputAnalogReadout
VDD18

SF1

SF2
STORE

CDS

SensorSensor C
Sample C
100fF

PD_VRST

OUT_BUF

G=1

G=1

CDS C
100fF

Sample/Store
GND18

COL_AMPTEST_ECACDS _VRST

VTH

EOXX

Depletion Depth [um]

XRPIX1-CZ (0.7kΩcm), -FZ(2010) (7kΩcm): Depletion Depth
350

7FZ : 250μm @ VBB=30V

300

FZ : Physical Thickness

250200

CZ : 150μm @ VBB=100V

150100+ : Experimental results– : Expected value

50001020304050
Back Bias [V]60708090100110• Measure the depletion thickness by observing the ratio between thecounting rates of two energies X-rays having different attenuation
lengths.
Nakashima et al.,• CZ: Depletion thickness of 150μm at VBB=100V.
2012, Physics
Procedia 37, 1373
• FZ: Full depletion is achieved at VBB=30V.

XRPIX1b-FZ(2012)-FI (7kΩcm) : Depletion Depth

8Counting Rate of 22keV X-ray
Physical Thickness 500μm (not 260μm)

Depletion
Preliminary
back_bias

VBB^1/2200V200V

• Counting Rate of 22keV X-ray (Cd-109) as a function of VBB.

(Attenuation Length = 1200μm > Physical Thickness = 500μm.)• The data follow the expected slope of depletion VBB^1/2.

• Full Depletion of 500μm is reached at VBB=200V.

20130502_matsumura.pdf

XRPIX2-CZ-FI (Small Pixel) : Spectrum in the frame modeCu Kα (8.0 keV)

Mo Kα (17.4 keV)

150

1800

800 eVFWHM100Mo Kβ(19.6 keV)

656 eV
FWHM

120010001000800600500400

Pulse Hight (ch)Cu Count

1400Mo Count

2001500120100100806050

XRPIX1 Gain
3.6 µV/e-402020000

XRPIX2 Gain
6.5 µV/e-

140

1600

080
40120160
Pulse Hight (ch = 244 µV)
406080100Observed
Cu Kα

656 eV

Mo Kα

800 eV

120140160
PH [ADU]

Readout
Noise

90000FanoNoise548 eV (FWHM) 139 eV
64 e-(rms)
205 eV

24101214 1610X-ray Energy (keV)6818Pixel-Pixel Gain
Dispersion 1%Sum255 eV620 eV553 eV

805 eV

2020

Nakashima et al., 2012, NIM A submitted

XRPIX3/3b : Pre Amp in Each Pixel

10Reset SWProtectionDiodeSensor
NodeFeedback Charge Amp
Capacitance 1fF• A charge sensitive amp (CSA) in every pixel in order to increase thegain and improve energy resolution.
• CSA is basically the same that developed in another SOIPIX (PIXOR).
• Gain ~50 μV/e, higher by a factor of ~10.
• Readout noise = 64e (rms) → Now testingXRPIX1b-CZ : Event Driven Readout③・④④

TRIG_COL
TRIG_ROW①①X-ray !

Row Hit Add.
Resister

ROW Readout ADDR

COL Hit Add. Resister

COL Readout ADDRCOL AmpOR

11TRIG_OFPGA②A_OUT

ADC⑤Takeda et al., IEEE
Accepted (2012)

XRPIX2b-CZ : Event-driven Readout Mode
Trigger !
TRIG_OUT

Trigger Address
Readout Clock

12Fe-55 (5.9keV)

22keV X-ray detection
Cd-109Note: Pixel gain is
not calibrated.

SCLK

Preliminary
CA[151-0]

Pulse Hight (ch)4μsec
RA[151-0]

RowColumn- Event-driven mode basically operates.
- Capacity of event rate >1kHz.
- The gain is different. There is offset.
- Due to interference between analog
and digital circuits

Pulse Hight (ch)Address ofTriggered Pixel

Event-Driven
5.4 μV/e-Offset

Frame-Mode
7.0 μV/ePreliminary
X-ray Energy (keV)
Takeda et al., IEEE (2013)

4

103

1000
1000

10500
500

1020

BPW

4060

80

10000

120
140
Channel (ADU)

300
250

1000

800

150

100100(17.4 keV)

020

40

60

80

100

50120140
Channel (ADU)

100

1200

600

Mo Kα

120

1400

200
200

1500
1500

102Counts

Counts1-FZ-FI10- Large Pixel 1 100 2-CZ-FI/LP1350(8.04 keV)
2000
2000

- Small Pixel 300 2-CZ-FI/SP= 1b-FZ-FI
1600

CountsPixel	  structureCircuit
SiO2P+510CMS Split3 Histgram

Peak / Tail
= 6.7

Mo-K

Counts

10Cu Kα

2500
2500

13CMS Split2 Histgram

Counts6CMS Split1 Histgram
CountsCountsCMS Raw Histgram

CountsBPW :Buried p-well

XRPIX1/2-CZ : Charge Loss
Peak / Tail= 2.9200

6050

Mo-K

150

40100

20200

4300

250

80

400

04350

050

12 14 16 18 20 2212 14 16 18 20 2288 10 1216 20PH [ADU]
44 6 88 10 1216 20PH [ADU]
11 pixel eventEnergy (keV)
1 pixel eventEnergy (keV)
0 6020406080100120140
Channel (ADU)0020406080100

2201412160

BI_Cu_Mo_Vb30V_10000000f

4500

200180CMS Sum Histgram

CountsCMS Split5 Histgram

CountsCountsBack	  Bias
Sensor	  NodeBPW• Suppress the back Nodegate effect of Tr.
• Also act as a part20μmof charge collectingnode.
• Increase parasitic
30μm
capacitance.
6μV/e
6μV/e
3μV/e
• A large BPW
A part of signal charge is lost somewhere.
reduces node gain.
CMS Split4 Histgram

40003500101403000

8120

2500

100

62000

80

1500

460

1000

40

2500

20
00204060

80

100

120
140
Channel (ADU)00204060

80

100120140
Channel (ADU)00204060

80

100120140
Channel (ADU)

120
ChanneCharge Loss

120
120

10

1200

4

1000

10
1500
1500

800

3101000
1000

600
210Mo Kα(17.4 10keV)

500
500

400

60

1200
1200

120
14040

1000
1000

3500
200

80

10800
800

3000

60
0.6

8600
600

150
2500

40

6
400
400

100
2000

0.4
200
200
40100 20120 40140 60
Channel (ADU)

00

80

100
120
1400stgram
CMS Split4 Histgram
Channel (ADU)

2060

080 0410020 120
40 1406080
100120140
CMSSplit3Histgram
Channel (ADU)
Channel (ADU)

BI_Cu_Mo_Vb30V_10000000f

2020

21000.6

1515

1.5
80

10100.4

16055

4060

charge is sharedby two pixels.

0.5
40

000.2
80
0 10020 12040 14060

80
100
120
1400 204060 80
100120 140
Channel(ADU)
Channel (ADU)

0020

2040

2040

channel [ADU]080 0 100 20 12040 14060
80
100120140
CMS Sum Histgram
Channel (ADU)
Channel (ADU)

00160

Counts4500

CountsCounts

The charge loss occurs in the region of pixel boundary.
1CMS Sum Histgram

3.5160351

2.5120004060
80 0 100 20120 40 140 60
02080100CMS
Sum Histgram
CMS Split5 Histgram 120 140
Channel (ADU)
Channel (ADU)

channel [ADU]

0CMS Split5 Histgram

40

0.860

80

20140

0 2040(ADU)
60 80 100Channel
120 (ADU)
140
Channel

2525

40

40
60
0 20 406080

020
100 2 120
140
Channel (ADU)

doublepixel
peak shift event
03140

1000
0020100
120140500
Channel (ADU)0.2
800 0 100 20 120 40 140 60100Channel
120 140(ADU)

53030

50
1500

2050

CMS Sum 40
Histgram

4000250

Counts

10000.8

charge cloud

100

4060
80
0 100 20 120
40 140Split26080
100
1200
CMS
Split3
Histgram
CMS
Histgram

3004500

100

12150

15Counts

CountsCountscounts / channel

1430

2060

CountsNo peak
shift

1400
1400

CMS Split4 Histgram
350

35300
Mo Kα(17.4 keV)

200

20

counts / channel

CMS Split5140
Histgram

CountsCounts1600
1600

stgram40258080

doublepixel 40
event 35
20140
Channel (ADU)CountsChannel (ADU)

0020
4060
80
120 40 140 60
00 100 20
100120CMS
Split2
Histgram
020
4060
80
100
120
140Split1 80
CMS
Histgram
Channel (ADU)

CMS Split2 Histgram

single
pixel
event

350

250

20Counts

doublepixel
event

100120140stgram
CMS Raw Histgram

1Cu Kα(8.04 keV)

100
100

20000

CMS Split3 Histgram

CMS Split1 Histgram

Counts

1400

52000
2000

140
140

1600

counts / channel

counts / channel

6CountsCu Kα10(8.04 keV)

2500
2500

XRPIX1b-FZ-FICMS Split2 Histgram

pixel
event

CountsCountsCMS Split1 Histgram

CountssingleXRPIX1-FZ-FI CMS Raw Histgram
Countssingle
pixel
event

tgram

Top view of
3x3 pixels

Small BPW (14.0μm)
Counts

Large BPW (20.9μm)

14BI_Cu_Mo_Vb30V_10000000f

6080100120140
Channel (ADU)

Matsumura+13
HSTD96080100120140
Channel (ADU)

BI_Cu_Mo_Vb100V_-55c_10000000f

(a) 電荷収集比：BNW(b) 電荷収集速度：BNW
8Charge Loss at interface between Si and SiO2 1560

図 6.27: 電荷収集パラメータ：BNW

BNW: 0um

6E field ( NHR50um,30V )BNW: 4um

Psub2

No BPW
40

E field ( NHR50um,30V,BPW6um ) Psub3

BNW: 8um

1.50e+04
1.50e+04

Active+BOX

Substrate

20

BPWBNW:12um

BPW• Electric field penetrates into2

1.50e+04BNW

1.15e+04
1.15e+04

BNW:16um

E field (4NHR50um,30V,BNW6um )SiO2 insulator.
01.15e+04-20 10 20 30 40 50 60 70 80
Signalcharge moves toCollectionthe ra•interface region between(a) 電荷収集比：BNW(b) 電荷収集速度：BNW
depleted Si and SiO2
図 6.27: 電荷収集パラメータ：BNW
insulator.
boundaryof(a) BPW：幅(b)EBNW
6 (µm)The signal
chargewould beE field ( NHR50um,30V,BPW6um) 6 (µm)
field( ：幅NHR50um,30V,BNW6um)•two図pixels
6.28: BPW, BNW による電場形状の違い
trapped and lost at theLarge BPW
Circuitinterface.
(b) Active 層あり
00

8.84e+03

8.84e+03

2

4

6

8.84e+03810
depo_x (um)

6.79e+03

6.79e+03

6.79e+03

5.21e+03

5.21e+03

5.21e+03
4.00e+03

4.00e+03

4.00e+03

1.50e+04

BPW

い：Active 層の有無

BPW

BNW

SiO2

1.15e+04

Sensornode
8.84e+03

6.79e+03

BPW
5.21e+03• Pencil X-ray beam test in
SPring-8.

Y. Ono, master thesis "Research and development of thePIXOR (PIXel OR) semiconductor detector for the highenergy experiments based on the SOI
technology" (unpublished, in Japanese) http://epx.phys.tohoku.ac.jp/eeweb/paper.html

Summary16• Developing monolithic SOI sensor ‘XRPIX’ for future Xray Astronomical Satellites.

• Realize the event driven readout mode and very low nonX-ray BGD by the function of the trigger signal output.

• Depletion region ~500μm.
• The readout noise ~60e- → Charge Sensitive Amp.
• The event driven readout basically operates.
• Signal charge would be lost at the interface between thedepleted Si and SiO2 insulator. → Pencil X-ray mean test.

A-R-Tec

Analog and RF Technologies

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