# Presentation: 477340

## SNAP CCD Development Progress

**Hakeem Oluseyi**
**January 9, 2003**

## Development 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

**Notes:**
What is Dominic’s last name?

## Outline

**Motivation and Technology**
**Commercialization of CCD Technology**
**Precision 4-Side Buttable Packaging**
**Characterization Results**
**Summary**

## SNAP

_**SNAP CCD Design Drivers**_

**  ****Wavelength Response**
**  ****Plate Scale/PSF**
**  ****Radiation Tolerance**
**  ****HgCdTe Area Match**

## LBNL CCD Technology

## Outline

**Motivation and Technology**
**Commercialization of CCD Technology**
**Precision 4-Side Buttable Packaging**
**Characterization Results**
**Summary**

## LBNL 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

## Commercially fabricated 150 mm wafer

- Front-illuminated 2k x 4k (15m pixel)
- Back-illumination technology development in progress
- Fabrication 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.

## SNAP Prototype

## Outline

**Motivation and Technology**
**Commercialization of CCD Technology**
**Precision 4-Side Buttable Packaging**
**Characterization Results**
**Summary**

## Packaged 2k2k CCD

## CCD 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.

- Speckle interferograph – excursions within 6 m.

## Outline

**Motivation and Technology**
**Commercialization of CCD Technology**
**Precision 4-Side Buttable Packaging**
**Characterization Results**
**Summary**

## LBNL 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.

## QE & Noise Performance

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

## Radiation Tolerance

**CTE is measured using the ****55****Fe X-ray method at 128 K. The readout speed is**
**30 kHz, the X-ray density is 0.015/pixel.**
**Degradation is about 1********10****-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**

**Notes:**
What can I say to elucidate degradation?

## 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

- 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 Results**

-         VSUB = 20V                                    VSUB = 60V
-                1100 x 800 back-illuminated CCD, 15 m pixels

## Summary

- 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
- 10.5m pixels with PSF ~ 4m 
- Higher voltages/thinner wafers