Large area detectors and new sensor technologies at ... · Astronomical Telescopes and Instrumentation 24-31 May 2006, SPIE 6276-5 Large area detectors and new sensor technologies

Astronomical Telescopes and Instrumentation 24-31 May 2006, SPIE 6276-5

Large area detectors and new sensor Large area detectors and new sensor technologies at Fairchild Imaging technologies at Fairchild Imaging

Paul Vu, Chiao Liu, Dan Laxson

© Fairchild Imaging 2Astronomical Telescopes and Instrumentation

24-31 May 2006, SPIE 6276-5

OutlineOutline

• Introduction• Large area CCD detectors at Fairchild Imaging• MTF optimization of 4k x 4k CCD• CCD-CMOS hybrid technology status• Summary


24-31 May 2006, SPIE 6276-5

IntroductionIntroduction

• Fairchild Imaging manufactures advanced image sensors for industrial, scientific, and medical applications

• Full line of wafer-scale sensors• Monolithic sensors 8 x 8 cm2

• Pixel size 8.75 µm to 40 µm• High speed low noise CMOS• In-house CCD wafer fab• Large format back-illuminated

CCDs in high volume

Fairchild Imaging sensor manufacturing facilities are located in Milpitas, California


24-31 May 2006, SPIE 6276-5

OutlineOutline



24-31 May 2006, SPIE 6276-5

Large area CCD detectorsLarge area CCD detectors

CCD part number

Format H x V (pixels)

Pixel size (µm2)

Imaging area (H x V, mm) Features

CCD485 4k x 4k 15 x 15 61.20 x 61.21 Frontside, 3-phase, MPP, 4 outputs

CCD486 4k x 4k 15 x 15 61.44 x 61.45 Front or back-illuminated, 4 outputs

CCD595 9k x 9k 8.75 x 8.75 80.64 x 80.64 Frontside, eight 25-MHz outputs

CCD8161 4k x 4k 19.5 x 19.5 79.87 x 79.87 Frontside, 3-side butting, 4 low-noise and 4 high-speed outputs

CCD3041 2k 2k 15 x 15 30.72 x 30.72 Front or back-illuminated, 4 outputs


24-31 May 2006, SPIE 6276-5

Monolithic 9k x 9k CCD595Monolithic 9k x 9k CCD595

• Developed for aerial reconnaissance• 9216(H) x 9216(V) full frame CCD• 8.75 µm x 8.75 µm pixels• 80.64 x 80.64 mm image area• 100% fill factor• 3-phase parallel shift registers• 2-phase serial shift registers• Buried channel CCD• 8 high-speed output amplifiers

• Readout noise <30 e- at 25 MHz• 200 MHz data rate (25 MHz x 8)• Flight package with TEC coolers

CCD595 in ceramic package


24-31 May 2006, SPIE 6276-5

4k x 4k CCD81614k x 4k CCD8161

• Developed for mosaic applications• 3-side abuttable• 4096(H) x 4096(V) full frame CCD• 19.5 µm x 19.5 µm pixels• 79.87 mm x 79.87 mm active area• 100% fill factor• Front and back-illuminated• Multi-Pinned Phase (MPP)• 8 selectable output ports

– 4 low-noise– 4 high-speed

• 3-phase vertical and serial registers• Supports pixel binning


24-31 May 2006, SPIE 6276-5

2k x 2k CCD30412k x 2k CCD3041UPPER RIGHT

LOWER RIGHT

OUTPUT

OUTPUT

2048 Pixels

2048 Pixels

512

Pixe

ls51

2 P

ixel

s51

2 P

ixel

s51

2 P

ixel

s

2048 Lines

LOWER LEFTOUTPUT

UPPER LEFTOUTPUT

6.5

2.72.32.1

0

1

2

3

4

5

6

7

10 100 1000Frequency (kHz)

Noi

se (e

- rm

s)

• Scientific grade CCD• FF 2048(H) x 2048(V)• FT 2048(H) x 1024(V)• 15 x 15 µm2 pixels• Die size: 32.820 x 34.028 mm2

• 3-phase shift registers• 4 output ports• MPP• 90dB dynamic range• Front or back-illuminated• Compact package


24-31 May 2006, SPIE 6276-5

OutlineOutline



24-31 May 2006, SPIE 6276-5

4k x 4k CCD4864k x 4k CCD486

Back-illuminated CCD486

Front-illuminated CCD486

• 4096(H) x 4097(V) full frame CCD• 15 µm x 15 µm pixels• 61.44 mm x 61.44 mm image area• 100% fill factor• Front and back-illuminated• Multi-Pinned Phase (MPP) mode• Readout noise < 3 e- at 50 kHz• Full well > 100 ke-

• 4 output ports• 3-phase buried channel CCD• Supports pixel binning• Notch channels for improved

radiation tolerance


24-31 May 2006, SPIE 6276-5

CCD486 performanceCCD486 performance

0

1

2

3

4

5

6

7

8

9

10

100 1000Frequency (kHz)

Rea

d no

ise

(e- r

ms)

Overscan

Image

Parameter Typical measured value Units Vertical full well (1 x 1) 102,000 e- Horizontal full well 760,000 e- Par. & Hor. CTE at 1000 e- 0.999998 Par. & Hor. CTE at 60,000 e- 0.999999 Read noise at 250 kHz < 4 e- Read noise at 1 MHz < 7 e- Dark current at -60°C 0.02 e-/pix/sec PRNU, measured at half sat 5 % full well DSNU at +30°C 25 pA/cm2 p-p Non-linearity (up to 80% FW) < 1 %


24-31 May 2006, SPIE 6276-5

Backside thinning processBackside thinning process

• Known-good CCD is bonded to substrate

• Special mask is applied to define thinned area

• Selective chemical etch removes bulk Si

• Perform back surface accumulation process and AR coating

• Mount die in package and wirebond

• Stable and well controlled CCD thinning process performed in high volume

P+

P-

Support Substrate

CCD die

Underfillepoxy

P-

Support Substrate

HF : HNO3 : CH3COOH

1. Bond die to substrate,protect non-active areas

2. Selective chemical etch

P-

Support Substrate

3. Back surface processing and AR coating4. Die attach and wirebond


24-31 May 2006, SPIE 6276-5

Diffusion MTF effectsDiffusion MTF effects

• Carrier diffusion in the field free region degrades the MTF

• Field free region is effectively eliminated by sufficiently large bias on high resistivity material

• Fully depleted CCD concept

• Fully depleted CCD offers excellent MTF characteristics, but add process complexity and increase in dark current

• The field free region can be minimized by additional thinning

Depletion layer

Undepleted neutral layer

e-

e-

e-e-

LW SW

Potential well

hν

SiO2 p-Si frontsidegate

e-

n-buriedchannel

field-freeregion

e-

depletion width ∝ SiR

depletion region

Front-Illuminated Back-Illuminated


24-31 May 2006, SPIE 6276-5

CCD486 MTF optimizationCCD486 MTF optimization

• Silicon thinned to ~ 10 µm compared to standard ~ 20 µm • MTF at Nyquist frequency improved ~3x at 410 nm


24-31 May 2006, SPIE 6276-5

QE responseQE response

• Some impact on red response compared to standard ~ 20 µm

0

10

20

30

40

50

60

70

80

90

100

300 400 500 600 700 800 900 1000 1100

Wavelength, nm

QE,

%

10-um epi Blue-enhanced ARC20-um epi Blue-enhanced ARC


24-31 May 2006, SPIE 6276-5

OutlineOutline



24-31 May 2006, SPIE 6276-5

MotivationsMotivations

• Many scientific, medical, and military imaging applications require optical quality, high speed and low noise performance that exceed standard CCD or CMOS image sensor technology– Wavefront sensing for Adaptive Optics– Synchrotron x-ray crystallography– Night vision surveillance

• Requirements– Photon counting sensitivity – Resolution: 1M ~ 100M pixels – Frame rate: 30 Hz ~ 3 kHz– Minimal or no cooling– Low power


24-31 May 2006, SPIE 6276-5

Existing technologiesExisting technologies

• Monolithic CMOS image sensor– Low power, and system integration capability– High dark current, low QE, high read noise

• Conventional scientific CCD– Near ideal imaging performance — high QE, low dark

current, excellent uniformity– Elevated noise at high frame rates

• EMCCD– Very low-noise performance– Not suitable for some applications due to cooling and power

requirements


24-31 May 2006, SPIE 6276-5

Benefits of hybrid architectureBenefits of hybrid architecture

• Highly parallel architecture– Enables high frame rates at low noise– Eliminates high-power, high-bandwidth, on-chip CCD amplifiers– Uses low-bandwidth low-noise, high gain amplifiers in CMOS ROIC

• Low noise CMOS ROIC design– High conversion gain via LFPN CTIA– Bandwidth limiting for low noise– Low-power and high-speed performance

• Optimized CCD performance– Low dark current with MPP or pinned photodiode technology– Flexible CCD architecture: frame transfer (FT), interline transfer

(IT), front or back-illuminated– Charge binning capability for improved SNR


24-31 May 2006, SPIE 6276-5

CCDCCD--CMOS hybrid architectureCMOS hybrid architecture

CCD Clock Drivers

Control

Digital Output

Indium Bump Bonding

Shielded Storage Area

CMOS CIRCUIT


CMOS CIRCUIT

CCD Clock Drivers

Control

Digital Output

1280 Columns

1024

Row

sCharge Coupled Device

• CMOS ROICs directly coupled to CCD• CCD contains no output amplifiers• Charge to voltage conversion performed in CMOS ROIC


24-31 May 2006, SPIE 6276-5

Frame transfer CCDFrame transfer CCD



Sense node

V1

V4

V3

V2

V1

Channel stops

CCD channel


24-31 May 2006, SPIE 6276-5

Interline frame transfer CCDInterline frame transfer CCD



Photodiode

Shielded vertical registers

Sense node

1

1

3

3 4

2

2




24-31 May 2006, SPIE 6276-5

CMOS readout IC block diagramCMOS readout IC block diagram

S1

C1

S2

C2

Vref

Reset

Cfb

Cin A

VinConnected toCCD

A A A

A A A

Output

CTIA andsamplingnetworkA A A A

16 : 1 16 : 1

320 x 1 bumps

ShiftRegister

Pixel control signals Analog outputs

Bump

Analogbias

Clock

10 : 1 10 : 1

Analog outputs

Entire Chip

Single Channel


24-31 May 2006, SPIE 6276-5

Noise analysisNoise analysis

• CTIA is dominant noise source• The input referred noise power

spectral density includes thermal noise and 1/f

• Assuming that 1/f noise is removed by CDS, noise in e-rms is given by

Vn~

Cin

Cfb

Cload

AVout

fAmf

mn f

gKgkTfV

22

38)( +=

223

8in

m

CNBWqg

kTN ⋅⋅≈

AmplifierBWNBW2π

=where


24-31 May 2006, SPIE 6276-5

Estimated noise performanceEstimated noise performance

Noise as a function of frame rate


24-31 May 2006, SPIE 6276-5

Hybrid development statusHybrid development status

• Prototype 1280(H) x 1024(V) hybrid sensor demonstrated

• Frame transfer CCD• CMOS CTIA readout ICs• Read noise ~ 2.9 e- at 30 Hz

H1011 Characteristics

Format 1280(H) x 1024(V)Pixel size 12 x 12 µm2

Spectral range 400 - 1100 nmPeak QE 40%Conversion gain 160 uV/e-Non-linearity <1%Dynamic range high gain mode = 2000:1

low gain mode = 6000:1Dark current at 23 °C 6 - 8 pA/cm2

Smear at full saturation 0.05%Outputs 4 (multiplexed)Frame rate 1x1 unbinned 30 fps 2x2 binned 52 fps 4x4 binned 128 fps


24-31 May 2006, SPIE 6276-5

OutlineOutline



24-31 May 2006, SPIE 6276-5

SummarySummary

• Fairchild Imaging offers a unique family of scientific CCDs with ultra large imaging areas

• Reliable manufacturing capability• Improved MTF of back-illuminated 4K x 4K CCD• New breed of advanced sensors developed to

address the need for high speed and low noise performance

Documents

Large area detectors and new sensor technologies at ... · Astronomical Telescopes and Instrumentation 24-31 May 2006, SPIE 6276-5 Large area detectors and new sensor technologies