November_EDFA

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ELECTRONIC DEVICE FAILURE ANALYSIS | VOLUME 18 NO. 4

SUPERCONDUCTING SINGLE‑PHOTON DETECTOR

ENABLES TIME‑RESOLVED EMISSION TESTING OF

LOW‑VOLTAGE SCALED ICs

Andrea Bahgat Shehata, Franco Stellari, and Peilin Song

IBM T.J. Watson Research Center, Yorktown Heights, NY

TIME-RESOLVED OPTICAL PROBING OF

SIGNALS ON SCALED ICs

Notwithstanding the continuous advances in design-

for-manufacturing and design-for-test features, the use

of noninvasive optical techniques for probing waveforms

from internal nodes of integrated circuits (ICs) remains

very important for the fast and accurate localization of

failures.

Currently, laser voltageprobing (LVP)

[1]

is themost com-

monly used time-resolved technique. A continuous-wave

laser beam is focused through a high-numerical-aperture

(NA) optical systemto a specific transistor. When a voltage

waveform is applied across the transistor under test,

there is a change in free-carrier density that alters the

local refractive index and the silicon absorbance, thus

giving rise to a modulation in the reflected laser light.

The small modulation in the light reflected from the

structure is detected by a fast photodiode (Fig. 1a). This

method is extremely sensitive and has only a modest

EDFAAO (2016) 4:16-22

“LUCKILY, NOVEL PHOTODETECTORS

SUCH AS THE SUPERCONDUCTING

SINGLE‑PHOTON DETECTOR (SSPD) THAT

HAVE BECOME AVAILABLE IN RECENT

YEARS HAVE HELPED RETURN THE LIGHT

TO THE TRE TECHNIQUE, DUE TO LOWER

NOISE (FEW DARK COUNTS PER SECOND)

AND BETTER JITTER .”

(a)

(b)

Fig. 1

Comparison of the two main optical techniques used to detect timing‑related faults within an IC. (a) In LVP, a laser is

shined toward the device, and the reflected light is modulated by the carriers and detected by a detector. (b) In TRE,

NIR photons are spontaneously emitted by the IC and collected by the detector.