SNAP CCD SNAP CCD Development ProgressDevelopment Progress

Hakeem OluseyiJanuary 9, 2003

H. M. Oluseyi 2

Development TeamDevelopment Team

LBNL Physics/Astrophysics

C. Bebek, M. Levi, H. Oluseyi, S. Perlmutter, V. Prasad

LBNL Engineering

J. Bercovitz, A. Karcher, W. Kolbe

LBNL Microsystems Laboratory

S. Holland, N. Palaio, G. Wang

Student Interns

H. Bertsch, S. Farid, M. Wagner

H. M. Oluseyi 3

OutlineOutline

• Motivation and Technology

• Commercialization of CCD Technology

• Precision 4-Side Buttable Packaging

• Characterization Results

• Summary

H. M. Oluseyi 4

SNAPSNAP

rin=6.0 mrad; rout=13.0 mradrin=129.120 mm; rout=283.564 mm

Guider

HgCdTe

Spectrograph

CCDs

Spectrograph port

SNAP CCD Design Drivers

• Wavelength Response

• Plate Scale/PSF

• Radiation Tolerance

• HgCdTe Area Match

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LBNL CCD TechnologyLBNL CCD Technology

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OutlineOutline

• Motivation and Technology

• Commercialization of CCD Technology

• Precision 4-Side Buttable Packaging

• Characterization Results

• Summary

H. M. Oluseyi 7

LBNL MicroSystems LaboratoryLBNL MicroSystems Laboratory

CCD’s fabricated at LBNL Microsystems Laboratory Commercialization efforts at CCD foundry in progress

Thermco furnaces at LBNL Microsystems Laboratory

150 mm Lithography tool at LBNL Microsystems Laboratory

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Commercially fabricated Commercially fabricated 150 mm wafer150 mm wafer

Front-illuminated 2k x 4k (15m pixel)Back-illumination technology development in progressFabrication at Dalsa Semiconductor (formerly Mitel)

150 mm DALSA-fabbed wafer. Large rectangular devices are 2k x 4k, 15 m; large square devices are 2.8k x 2.8k, 10.5 m with 4-corner readout.

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SNAP PrototypeSNAP Prototype

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OutlineOutline

• Motivation and Technology

• Commercialization of CCD Technology

• Precision 4-Side Buttable Packaging

• Characterization Results

• Summary

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Packaged 2kPackaged 2k2k CCD2k CCD

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CCD Assembly and TestCCD Assembly and Test

Established a factory to reliably package devices:

• With reliable connectivity (wire-bonding)• Without damage to optically active surface• Without ESD damage• Without excessive mechanical stress on CCD

Packaging status:

• Used LBNL speckle interferometer to study detector distortion due to differential CTE of CCD, substrate, and moly mount.

• About a dozen configurations have been studied.• Thick AlN looks acceptable for now.

Future:

• CCD mounted to a “thick” silicon substrate is the preferred solution to minimize stress in CCD.

• We will explore the elimination of wire-bonds and support of the CCD over its entire area.

moly

~0.25 epoxy

1.524 AlN

0.25 epoxy

5.726 moly

0.200 CCD

>8.000

Speckle interferograph – excursions within 6 m.

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OutlineOutline

• Motivation and Technology

• Commercialization of CCD Technology

• Precision 4-Side Buttable Packaging

• Characterization Results

• Summary

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LBNL CCD PerformanceLBNL CCD Performance

• Pixel size• Well depth• Linearity• Dark current• Sensitivity• Persistence• Read noise• Quantum efficiency• Charge transfer efficiency• CTE radiation degradation• Diffusion• Intrapixel response• Radiation

− Proton when irradiated cold

− 60Co when cold− Heavy ion study

• Fabrication• Packaging

10.5 m devices work, need more experience. 130 ke– for 10.5 m pixel. Better than 1%. 2 e–/hr/pixel. 3.5 V/e–

Erase mechanism is effective. 2 e–. Extended red performance realized. CTI ~ 10-6 pre-irradiation. 1.5x10-13 g/MeV-cm2

On-going study. On-going study.

More robust than existing space devices when damaged warm.

No surprises. An activity during the next 6 months. Partially commercialized. Underway

R&D areas.

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QE & Noise PerformanceQE & Noise Performance

Quantum Effi ciency of state-of -the-art CCDs

0

10

20

30

40

50

60

70

80

90

100

300 400 500 600 700 800 900 1000 1100

Wavelength (nm)

Qua

ntum

Effi

cien

cy (

%)

LBNL

MIT/LL high rho

Marconi

From “An assessment of the optical detector systems of the W.M. Keck Observatory,”J. Beletic, R. Stover, K Taylor, 19 January 2001.

2 layer anti-reflection coating: ~ 600A ITO, ~1000A SiO2

Noise vs Sample Time for LBNL CCDs

1

10

1 10 100

Sample time (us)

No

ise

(rm

s el

ectr

on

s)

47/6 compact geometry

150 kps

100 kps

50 kps

rt-Hz scaling

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Radiation ToleranceRadiation Tolerance

0.99900

0.99910

0.99920

0.99930

0.999400.99950

0.99960

0.99970

0.99980

0.99990

1.00000

0 200 400 600 800 1000 1200 1400 1600

Dose (106MeV/g)

CT

E

LBNL CCD

LBNL Notch CCD

Marconi [1]

Tektronix [2]

CTE is measured using the 55Fe X-ray method at 128 K. The readout speed is30 kHz, the X-ray density is 0.015/pixel.

Degradation is about 110-13 g/MeV.

[1]L.Cawley, C.Hanley, “WFC3 Detector Characterization Report #1: CCD44 Radiation Test Results,” Space Telescope Science Institute Instrument Science Report WFC3 2000-05, Oct.2000

[2] T. Hardy, R. Murowinski, M.J. Deen, “Charge transfer efficiency in proton damaged CCDs,” IEEE Trans. Nucl. Sci., 45(2), pp. 154-163, April 1998

Dark Current vs Temperaturefor CCD after 5x109 protons/cm2

0.1

1

10

100

1000

10000

100000

50 55 60 65 70 75 80 85 90 95

1/kT (eV)

Dark

Cur

rent

(e- /h

)

e-1.218/2kT

208K

158K

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• Spatial resolution limited by diffusion of photogenerated carriers during drift from generation point to CCD potential wells

• Key issue for SNAP: Desire for small pixel sizes requires spatial resolution consistent with pixel size

• Major ramifications on technology development and device design

PSF ResultsPSF Results

VSUB = 20V VSUB = 60V

1100 x 800 back-illuminated CCD, 15 m pixels)(

2

Jsubsub VVq

kTz

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SummarySummary

• Fully depleted, back-illuminated CCD technology

— Device physics

— Fabrication at LBNL and commercially

— Spatial resolution

• Use at telescopes

• On-going efforts

— Deployment of more CCD’s at telescopes

— Completing 4-side buttable packaging

— CCD Development for SNAP

• Moving towards “Volume” manufacturing

• Proton damage studies (June 2002 IEEE Trans. Nucl. Sci., Jan ‘02 SPIE)

• Good spatial resolution and small pixel size

– 10.5m pixels with PSF ~ 4m – Higher voltages/thinner wafers