Vladimir V. Talanov

Reproducible operating margins on a 72 800-device digital superconducting chip

We report the design and test of Reciprocal Quantum Logic shift-register yield vehicles consisting of up to 72,800 Josephson junction devices per die, the largest digital superconducting circuits ever reported. Multiple physical layout styles were matched to the MIT Lincoln Laboratory foundry, which supports processes with both four and eight metal layers and minimum feature size of 0.5 {\mu}m. The largest individual circuits with 40,400 junctions indicate large operating margins of

High resolution Magnetic Current Imaging for die level short localization

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A scanning SQUID microscope with 200 MHz bandwidth

20% on AC clock amplitude. In one case the data were reproducible to the accuracy of the measurement,

High Resistance Open localization

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Open localization on copper wirebond using Space Domain Reflectometry

1% across five thermal cycles using only the rudimentary precautions of passive mu-metal magnetic shielding and a controlled cool-down rate of 3 mK/s in the test fixture. We conclude that with proper mitigation techniques, flux-trapping is no longer a limiting consideration for very-large-scale-integration of superconductor digital logic.

Microwave near-field imaging of electrical and magnetic properties of graphene and graphite

Magnetic Field Imaging (MFI) technology is capable of localize shorts using Magnetic Current Imaging (MCI) technique with a very high spatial resolution [1]. In this paper we demonstrate that a Giant Magneto Resistance (GMR) sensor positioned in close proximity to the front side of a die sample enables MFI to achieve sub micron resolution.

DC SQUID RF magnetometer with 200 MHz bandwidth

We developed a scanning SQUID microscope utilizing DC SQUID with novel readout electronics capable of sensing coherent magnetic fields from 50 to 200 MHz. To overcome the bandwidth limitation of traditional closed-loop SQUID magnetometers, we employ a flux-modulated closed loop to simultaneously lock the quasi-static magnetic flux and flux-bias the SQUID for amplification of RF flux. Demodulating the SQUID voltage with a double lock-in technique yields the signal proportional to the amplitude and phase of RF magnetic field. We describe the system performance and present images of a variety of samples.

DC SQUID BASED RF MAGNETOMETER OPERATING AT A BANDWIDTH OF 200 MHZ AND HIGHER

Magnetic Field Imaging (MFI) is a widely used technique in the Semiconductor industry for non-destructive Electrical Fault Isolation (EFI) for shorts, leakages and opens. When the devices shrink and the mobile electronics industry has a more strict criteria for speed with low power consumption, making High Resistance Opens (HRO) failures more important to detect. We show in this paper two cases in which magnetic field phase analysis using MFI helped localize HRO failures that were causing delays and slower speed in addition to higher power consumption.

Method and system for localization of open defects in electronic devices with a dc squid based rf magnetometer

Space Domain Reflectometry (SDR) is a new technique that has already shown to be a reliable non-destructive method to image open failures in semiconductor chips by pumping a high frequency signal into the open trace. We show in this paper that SDR can be used to accurately find a breakage location in copper wire bond that failed during stress test.

Reproducible Operating Margins on a 72800-Device Digital Superconducting Chip

We report on microwave response of graphene and graphite measured using electric field and magnetic field-detecting near-field scanning probe microwave microscopes.