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The ongoing integration density increase changes the demands on failure analysis methods for ICs drastically. Laser Voltage Probing (LVP) is an all-optical laser-based technique that acquires waveforms through the silicon backside. Although widely used in failure analysis labs, the knowledge about LVP signal origin is still very low. A detailed investigation of the signal origin is presented, using a modified LVP setup, which employed a 1319 or 1064 nm CW laser. Three new measurement methods were introduced, extracting frequency-information with a spectrum analyzer in opposition to the standard time-domain waveform acquisition with an oscilloscope. Signal-to-voltage correlations and modulation amplitude and sign maps were performed for a broad spectrum of MOSFETs: from 10 µm (to study signal sources) to 65 nm gates (effects on structures with decreased dimensions). These low-noise frequency-domain measurement methods enabled very short signal acquisition times (seconds to minutes). A concise model, describing the interaction of laser light and device activity, was built, explaining the signal sources and enabling the forecast of signal levels for future technologies and scaling.

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Dr. Ulrike Kindereit studied Electrical Engineering at Berlin Institute of Technology, Germany, with focus on semiconductor devices. From 2005 to 2008 she was engaged as a PhD student in a project with DCG Systems, doing research on Laser Voltage Probing (passed exam with distinction). Currently she is working at the IBM TJ Watson Research Center.

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