CCD Image Sensors for Astronomy · CCD Image Sensors for Astronomy Erik Bogaart, Inge Peters, Jan Bosiers, and Nixon O DALSA Professional Imaging Eindhoven, The Netherlands October

DALSA Corporation 2009

CCD Image Sensors for Astronomy

Erik Bogaart, Inge Peters, Jan Bosiers, and Nixon O

DALSA Professional ImagingEindhoven, The Netherlands

October 13th, 2009

& CMOS

2DALSA Corporation 2009 - Bogaart

Outline

• DALSA Corp.

• CCD Image Sensors• Architecture• Ultra-low dark current• Backside thinned devices

• CMOS Image Sensors• Wafer-scale• Radiation hardness

• Summary


DALSA Corp at a Glance

• Established in 1980• Headquarters in Waterloo ON, Canada• Listed at Toronto Stock Exchange

• Stock Symbol: DSA (TSX)• Shares Outstanding: ~20M


DALSA Corp Overview

Europe: 100Eindhoven, NLGröbenzell, D

Asia: 25Beijing, ChinaTokyo, Japan

Canada & USA: 850Waterloo, ONBromont, QC

Santa Clara, CA


DALSA Corp – Our Businesses

• Semiconductor fab - Bromont, Canada• CCD & CMOS image sensors• Digital cameras• Vision processors & software

Image sensors

MEM technology



• Semicondcutor fab - Bromont, Canada• CCD & CMOS image sensors• Digital cameras• Vision processors & software

Professional DSC

Broadcast& video



• Semiconductor fab - Bromont• CCD & CMOS image sensors• Digital cameras• Vision processors & software Medical X-ray &

Dental applications



• Semiconductor fab - Bromont• CCD & CMOS image sensors• Digital cameras• Vision processors & software

AerialPhotogrammetry

Scientific& Space



• Semiconductor fab - Bromont, Canada• CCD & CMOS image sensors• Digital cameras• Vision processors & software


Outline

• DALSA Corp.



• Summary


CCD Image Sensor Architecture

• FF- & FT-CCD• Bi-directional registers• Multiple readout amplifiers• 1…22…60… Mpixels• Colour & monochrome• Up to 100 MHz pixel rate per output

Manoury et al., IEDM Tech. Dig. 2008, pp. 263


Poly-1

Poly-2+

+

-

-

color filter

TiN grid

p-well p+ channelstop

a a’

microlenswith topcoat

DN1

n-substrate

poly gate

n-substrate

DN1p-well

b

b’ Cross-section a-a’

Cross-section b-b’

Poly-1

Poly-2

CCD Image Pixel Architecture (1)

micro-lens

Gapless micro-lenses



tungsten

• Thin membrane poly-silicon gate→ High quantum

efficiency• Non-overlapping gates

→ Low RC→ Reduced power

dissipation• Low-Ohmic interconnects

→ Fast charge transport• Excellent pixel separation

→ High MTF



nitride layer

microlenswith topcoat

n-channel

n-substratep-well

p+ channelstop

poly gate

TiN grid

14

12

10

8

6

n-substratep-welln-channelP

oten

tial (

V)Depth in silicon

0.0

1.0

2.0

3.0

4.0

SiO

2

Silicon

e-density under the integrating gate

integrating gate

blocking gate

barrier to neighboranti-blooming barrier

Ele

ctro

n de

nsity

(arb

. uni

ts)

• 4-phase buried-channel

• Vertical overflow drain to handle overexposure

• Low dark current

• High charge capacity

• Fast electronic shuttering Bogaart et al., Proc. SPIE 7250, pp. 725 003 (2009)


Outline

• DALSA Corp.



• Summary


Dark Current in Image Pixels

Dark current generation can be divided in three components:

Suppression• ISurface: interface of the buried channel biased into inversion

→ MPP• IBulk: built-in potential barrier reduces carrier diffusion

→ vertical anti-blooming

++=

++=

nA

ni

ggi

BulkDepletionSurfaceDark

LNDnWSqn

IIII

τ

Bogaart et al., IEEE TED (2009) accepted


CCD image sensors - Ultra-low dark current (1)

Multi-pinned phase

Anti-blooming

Electronic shuttering

All-gates pinning(AGP)

Poly-1

Poly-2+

+

-

-

color filter

TiN grid

p-well p+ channelstop

a a’

DN1

n-substrate

-

-

-

-

a a’

n-substrate

tungsten wirepoly gate

DN1 + DN2

Additional n-channelimplant area

n-substrate

DN1p-well

n-substratep-well

DN1DN1+DN2

b

b’

Cross-section a-a’

Cross-section b-b’

contact

p-well

Standard AGP

Bosiers et al., IEEE TED 42, 1449 (1995)Peters et al., IEDM Tech. Dig. 2004, pp. 993


CCD Image Sensors – Ultra-low dark current (2)

0 50 100 150 200

1

10

100

1000

10000

# o

f pix

els

Signal level (DN)0 50 100 150 200

1

10

100

1000

10000

# of

pix

els

Signal level (DN)

Non-AGP AGP

Dark images at room temperature with 6 s integration time(equally contrast enhanced)


CCD Image Sensors – Ultra-low dark current (3)

80x reductionDark current over full well factor (DCFF) improved 28x

80 fA/cm2 @ 10 °C

Allows low-light imaging, long integration times, and astronomical observations at elevated temperatures

Bogaart et al., IEEE TED (2009) accepted

3.0 3.2 3.4 3.6

0.1

1

10

100

AGP pixel

non-AGP pixel

I Dar

k (pA

/cm

2 )

1000/T (K-1)


Outline

• DALSA Corp.



• Summary


CCD Image Sensors - Backside thinned devices (1)

• Backside thinning: p--epi on p+ andSOI substrates

• Die thinning up to 10 × 10 cm2 devices• Wafer level thinning on 6″ wafers• Si-thickness ~ 8..12 µm• In-bumps, OK at cryogenic temperatures

Substrate

CCD~ 12 µm

Au

In


CCD Image Sensors - Backside thinned devices (2)

200 400 600 800 10000

20

40

60

80

100

16 µm pixel, ~ 10 µm Si-thickness

15 nm HfO2

20 nm HfO2

VIS-NIR

Optimized for UV

New resultsM

easu

red

QE

(%)

Wavelength (nm)


Outline

• DALSA Corp.

• CCD Image Sensors• Architecture• UItra-low dark current• Backside thinned devices


• Summary


CMOS Image Sensors – Wafer-scale (1)

• 8” wafer, p-substrate

• 77 x 145 mm2 active area

• 33.55 µm pixel pitch

• 2,304 x 4,320 resolution

• Buttable on three sides

• Radiation-hard pixel design


CMOS Image Sensors – Wafer-scale (2)

• 2 x 3 CMOS sensors tiled toCsI-coated FOP

• 231 x 290 mm2 active area

• 6,912 x 8,640 resolution(60 Mpixel)


CMOS Image Sensors – Radiation hardness (1)

PHOTO DIODE

N- WELL P- SUBSTRATE

LOCOS

N+ N+

RESETGATE

positive chargetrappingLOCOS

enhanced thermal generation

SOURCE FOLLOWER

X- RAY

Dark increment after X ray

1

10

100

1000

10000

100000

100 1000 10000X-ray Cobalt60 (Gray)

incr

emen

t fac

tor

Dark current increment after 144 hours RT

Vref

Out

reset

select

SourceFollowerPhoto

Diode

Classical Pixel



Radiation Hard PPD Pixel

100x better radiation hard

0 25 50 75 1000

2

4

6

8

10Cobalt 60 - 1.2 MeV

Dar

k cu

rren

t inc

reas

e fa

ctor

Radiation dose (Gray)

Measurement Linear fit



DALSA CMOS imager before and after radiation.

0.0E+00

2.0E+05

4.0E+05

6.0E+05

8.0E+05

1.0E+06

0 5000 10000

Illumination level (Arb. Units)

Out

put (

# el

ectr

ons)

0

4

8

12

16

20

Non

-line

arity

(%)

before radiation after 100Gy radiation


• World record ultra-low dark current CCD image sensor with All-Gates Pinning» 1.5 pA/cm2 @ 60 °C» 0.08 pA/cm2 @ 10 °C

• Dark current over full well factor (DCFF) improved 28x(6 µm pixel)

• Charge transport efficiency, anti-blooming, and electronic shuttering performance are not compromised

• Die level – 10x10 cm2 – and 6” wafer level BST CCD» UV – QE 94% @ 240 nm» VIS – QE 97% @ 565 nm

• 8” Wafer scale buttable CMOS image sensor• PPD pixel design, radiation hardness 100x better

Summary


Thank youfor your attention

Info: www.dalsa.com/sensors/E-mail: [email protected]

Documents

CCD Image Sensors for Astronomy · CCD Image Sensors for Astronomy Erik Bogaart, Inge Peters, Jan Bosiers, and Nixon O DALSA Professional Imaging Eindhoven, The Netherlands October