Transcript CPIX14_Porterx

September 17, 2014
Design and Characterization of a High-Speed
Multi-frame Hybrid CMOS Camera
J.L. Porter1, L.D. Claus1, L. Fang1, R.R. Kay1, M.W. Kimmel1,
A.T. Pomerene2, G.A. Robertson1, M.O. Sanchez1, J.W.
Stahoviak2, D.C. Trotter3
1Sandia
National Laboratories
2Sandia Staffing Alliance
3Doug Trotter Consulting
We are developing a high-speed solid-state x-ray
framing camera for use on high-energy-density
science facilities such as Sandia’s Z machine
22 MJ peak stored energy
26 MA peak current
100 TW electrical power
100-300 ns pulse length
50 Megagauss magnetic field
100 Mbar magnetic pressure
2 MJ, 400 TW x-ray source
150 experiments/year typical
Desired imager characteristics from user community
 High spatial resolution (25µm or better)
 High speed (1ns or better)
 Many frames (10 or more frames)
 High sensitivity to visible light, x-rays, or particles (100% fill
factor and sensitive to single keV x-ray photons)
 Large dynamic range (1000 or better)
 Large sensor (multi-cm scale size)
 High timing precision (50 ps or better)
 Low trigger insertion delay (few 10’s ns)
 Compact, rugged, and easy to integrate into diagnostic systems
and experiments
 Radiation tolerant (can operate on large ICF facilities)
Design specifications for “Furi” prototype camera
 Spatial resolution: 25µm pixel size and pitch
 Time resolution: 1ns minimum integration time, user selectable
integration times up to 100µs
 Frames: 2 frames/pixel in architecture that scales to 32 frames/pixel
 Sensitivity: 100% photodiode fill factor, 50% QE for 6 keV x-rays
 Dynamic range: 1 – 1000 photons/pixel @ 6 keV x-ray energy
 Pixels: 1024x448 (25x11 mm2)
Biggest design challenge is dealing with the large
photocurrents generated during short exposure times with
high flux: up to 250µA/pixel and 100A for entire sensor
A hybrid CMOS sensor enables near 100% diode fill
factor and use of different diode arrays with the same ROIC
Optical, x-ray or particle Illumination
Substrate
Contact: 50V
Substrate
Contact: 50V
~1µm thick P+
25µm
Si diode array
N+ pixel
P+ channel stop
Interconnect
CMOS ROIC
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Pixel
Electronics
Pixel
Electronics
Pixel
Electronics
6” ROIC and diode wafers produced at Sandia’s 0.35 µm SOI CMOS fabrication
facility
Wafer hybridization performed at Ziptronix using their proprietary Direct Bond
Interconnect process (oxide-to-oxide bond)
Die sawing, packaging, and integration with control electronics performed at
Sandia
There is a tradeoff between Si diode detection efficiency
and time response for x-rays with energies >5 keV
25µm thick diodes
25µm thick diodes
The unit pixel is composed of 11 transistors and
2 analog storage capacitors
photodiode node
reset control
frame #1 write
control
frame #1 read
buffer
VRST
VDD
nRST
nW0
photodiode
input
nFR0
W0
frame #1 read
control
VSS
VDD
PD_IN
FR0
nW1
COL
frame read
output
nFR1
W1
VSS
FR1
frame #2 write
control
frame #2 read
buffer
frame #2 read
control
The ROIC incorporates high-speed timing generation
and distribution, multi-frame image capture, and data readoff
frame timing setup
High Speed Timing
Generation
trigger Input
Rese
t
:
:
Unit
Diode
DETECTOR
ARRAY
Analog
Memory
:
:
I/O
Buffers
Buffer
Unit
Pixel
PIXEL ARRAY
Row and Frame
Decode
:
:
analog outputs
Buffer
multiplexer
Analog
Memory
READ OUT
Column
Decode
Bias
Bias
12-Bit Control 5-Bit Control
“Furi” prototype 2-frame sensor
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30x19 mm2 die, 25x11 mm2 sensor area
High speed timing generation with user selectable gate time between 1ns and
100µs
Timing distribution fed from 2 sides of ROIC to each of 1024 image columns
(timing skew limits row dimension with this timing distribution approach)
Compact and modular electronics package can be readily
customized and integrated into a range of diagnostic systems
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Inputs/Outputs
- 7V power
- slow and fast triggers
- Frame timing monitors
- serial communication computer interface
A pulsed laser-produced-plasma x-ray source is used
to uniformly illuminate the sensor
Laser wavelength: 532 nm (frequency doubled)
Laser energy: 15 J (max. at 2w)
Pulse duration: 1 – 4 nsec (user selectable)
Furi
X-ray target material: Ti (4.7 keV x-rays)
sensor
vacuum
vessel
x-ray filter
focusing
lens
pulsed laser
Example of x-ray time-history
x-ray
reference
photodiode
Ti foil
x-ray filter
An x-ray line-pair test pattern was used to measure
the spatial resolution with 20 LP/mm clearly resolved
20 line-pair/mm
32 x 32 pixels
The time response is determined by varying the
timing between the x-ray pulse and the frame gate times
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x-ray pulse FWHM = 2.5ns, frame gate time = 4ns, 10ns frame separation
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x-ray pulse convolved with 4ns gate time for comparison with measurements
A large-area reference Si diode is used to determine
the absolute x-ray sensitivity and gain of each pixel
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Each absorbed 6 keV photon creates 1,700 electron/hole pairs and generates
a 1mV voltage change on the 250 fF pixel capacitor
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Initial measurements of transmission through an x-ray step wedge indicate a
dynamic range > 400 presently limited by the broad-band nature of our laserproduced-plasma x-ray source.
Demonstration of image capture on a dynamic object:
Shadowgraphs of a laser generated blast wave
Z-Beamlet laser driver:
1 kJ in 1 ns pulse, 527nm,
F/10 focusing lens
Target
chamber
Shadowgraph probe laser:
4 1ns 1mJ pulses at
532nm spaced in time
blast wave expanding
into 10-90 Torr N2
Foil target
location
Imaging and
relay optics
Furi visible sensor
Example of blast wave shadowgraphs recorded with
visible Furi sensors on a single experiment
shadowgraph timing
1TW Z-Beamlet laser
focused onto
1µm-thick Mylar foil
16.8mm
17.8mm
21.5mm
t=90ns
t=150ns
blast waves
t=10ns
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t=70ns
Time-gating enables each individual shadowgraph to be seen and eliminates
the bright plasma emission that occurs when Z-Beamlet strikes the thin foil
Near term plans for cameras with more frames
 Hippogriff – modification/evolution of Furi architecture
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Interlacing mode to provide 2,4,6, or 8 frames with decreasing spatial resolution
Fabrication and hybridization complete, in packaging available for testing next
month
 Icarus - next generation 0.35µm ROIC targeting lower energy x-rays
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4 frames, 25µm, 1024x512 pixels
Sensitive down to 100 eV x-rays, will use common cathode photodiodes
500 – 500k e- full well capacity
In fabrication, planned for initial testing to begin in early 2015
 Acca – future ROIC fabricated in smaller CMOS process
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8 frames, 25µm, 512x512 pixels
H-tree timing distribution
3-side abuttable to enable tiling multiple sensors
Being designed for IBM 0.13µm CMOS process
Tape out planned for April 2015
Conclusion and Future Plans
 Demonstrated fast multi-frame x-ray and visible imaging with a
hybrid CMOS camera
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Initial measurements are very promising but more characterization required
with pulsed sources to determine if all performance goals were achieved
Excellent success with Ziptronix DBI hybridization process
 Cameras with more frames/pixel presently in fabrication and design
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Interlacing with 4 or 8 frames options (“Hippogriff”, in packaging)
4-frame/pixel camera (“Icarus”, in fabrication)
8-frame/pixel camera in design using 0.13µm CMOS process (fabrication
planned for 2015)
Goal to develop cameras with 32 frames/pixel in 6 years