Neocera, Inc.

Antonio Orozco

Vladimir Vladimirovich Talanov

Alfred Benjamin Cawthorne, Iii

Thirumalai Venky Venkatesan

Lee A Knauss

Alfred B Cawthorne

Nicholas Eric Gagliolo

Nesco Mario Lettsome, Jr

Elena Talanova

Vladimir V Talanov

Alfred Benjamin Iii Cawthorne

Viadimir V Talanov

Nicolas Eric Gagliolo

Non-destructive localization of open defects in electronic devices is performed with a DC SQUID based RF magnetometer capable of sensing coherent magnetic fields up to 200 MHz and higher. RF magnetic fields (or RF current) images are correlated to conductive paths layout of the electronic device, and the open defect is pinpointed at a location of RF current disappearance on the current image. The bandwidth limitations associated with transmission line delays between SQUID circuit and readout electronic, as well as with near-field coupling between different parts of the measurement scheme, are overcome by superimposing the RF flux emanating from device under study on the modulation flux to produce at the SQUID output a binary phase modulated RF voltage, which is processed to lock the static flux, and to control modulation regime by producing an AC bias for the RF flux. RF readout electronics is based on a double lock-in through sequential demodulation of the RF component of the output SQUID voltage at the modulation flux frequency &#x3c9;and the RF flux frequency &#x3c9;.

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

An RF DC SQUID based magnetometer capable of sensing coherent magnetic fields up to 200 MHz and higher is developed which overcomes frequency limitations associated with noise signals due to transmission line delays between the SQUID circuit and readout electronics. The bandwidth limitations are overcome by superimposing the RF flux on the modulation flux to produce at the SQUID output a binary phase modulated RF voltage, which is processed to lock the static flux, and to control modulation regime by producing an AC bias for the RF flux. RF readout electronics based on a double lock-in technique (sequential demodulation of the RF SQUID voltage at the modulation flux frequency &#x3c9;and the RF flux frequency &#x3c9;), yields a signal proportional to the product of amplitude and phase cosine of RF flux with linear dynamic range up to five orders in magnitude if compared to DC SQUID operated in traditional flux-locked loop regime.

DC SQUID based RF magnetometer operating at a bandwidth of 200 MHz and higher

Circuit flaws in microelectronic circuitry present regions of high resistance in which a current distribution deviates from that of a defect-free circuit. The altered current distribution emits a correspondingly altered magnetic field in accordance with Ampere's Law. When compared with the magnetic field of a defect-free circuit, the anomaly in the magnetic field of the defective device is detected and the location of the circuit flaw may be determined therefrom. As the anomaly in the magnetic field is very small in magnitude, a sensitive magnetic microscope is utilized to obtain images of the magnetic fields of a defect-free reference device and a device-under-test. The distance between the magnetic sensor and the devices being scanned is precisely controlled to minimize influences of scanning distance on the difference in measured magnetic field strength. Comparative image analysis reveals the location of the circuit flaw. Maximal image registration through image interpolation, displacement and resampling optimizes the comparative image analysis.

Fault isolation of circuit defects using comparative magnetic field imaging

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Washington, DC, United States of America

Antonio Orozco