SNAP CCD Development Progress Hakeem Oluseyi January 9, 2003

H. M. Oluseyi 2 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

H. M. Oluseyi 3 Outline Motivation and Technology Commercialization of CCD Technology Precision 4-Side Buttable Packaging Characterization Results Summary

H. M. Oluseyi 4 SNAP r in =6.0 mrad; r out =13.0 mrad r in = mm; r out = mm Guider HgCdTe Spectrograph CCDs Spectrograph port SNAP CCD Design Drivers Wavelength Response Plate Scale/PSF Radiation Tolerance HgCdTe Area Match

H. M. Oluseyi 5 LBNL CCD Technology

H. M. Oluseyi 6 Outline Motivation and Technology Commercialization of CCD Technology Precision 4-Side Buttable Packaging Characterization Results Summary

H. M. Oluseyi 7 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

H. M. Oluseyi 8 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.

H. M. Oluseyi 9 SNAP Prototype

H. M. Oluseyi 10 Outline Motivation and Technology Commercialization of CCD Technology Precision 4-Side Buttable Packaging Characterization Results Summary

H. M. Oluseyi 11 Packaged 2k  2k CCD

H. M. Oluseyi 12 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.

H. M. Oluseyi 13 Outline Motivation and Technology Commercialization of CCD Technology Precision 4-Side Buttable Packaging Characterization Results Summary

H. M. Oluseyi 14 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 − 60 Co 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 ~ pre-irradiation.  1.5x g/MeV-cm 2  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.

H. M. Oluseyi 15 QE & Noise Performance 2 layer anti-reflection coating: ~ 600A ITO, ~1000A SiO 2

H. M. Oluseyi 16 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  g/MeV. [1]L.Cawley, C.Hanley, “WFC3 Detector Characterization Report #1: CCD44 Radiation Test Results,” Space Telescope Science Institute Instrument Science Report WFC , Oct.2000 [2] T. Hardy, R. Murowinski, M.J. Deen, “Charge transfer efficiency in proton damaged CCDs,” IEEE Trans. Nucl. Sci., 45(2), pp , April 1998

H. M. Oluseyi 17 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 Results V SUB = 20V V SUB = 60V 1100 x 800 back-illuminated CCD, 15  m pixels

H. M. Oluseyi 18 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