Abstract

Recent developments and improvements of laser probing techniques are a good complement to traditional techniques like emission microscopy (static and dynamic) or laser stimulation (also static and dynamic, based on thermal or photoelectric stimulus) for the investigation of failure analysis and diagnostic of integrated circuits. Laser probing techniques have in fact evolved from mainly pulsed approach with high bandwidth [1] to other methodologies based on Continuous Wave (CW) [2,3,4,5]. The bandwidth of these CW approaches is generally lower than pulsed techniques and fine characterization of rising and falling edges or measurement of very small timing shifts can be more difficult or not possible for high speed devices. This bandwidth limitation is most of the time due to the amplification chain. But, CW probing bandwidth is good enough, and continuously improving, to identify directly or indirectly timing issues and to identify bad digital or analog behavior. The setup is also much easier than pulsed laser systems which require complicated synchronization between the system timebase and the device. On this other side new internal analysis modes have been introduced with for example some mapping mode based on frequency analysis or on timing degradation identification through second harmonic analysis [6,7]. At the same time these techniques have pushed the capabilities of a lot of existing tools to investigate low current, low voltage and/or low frequency devices such as analog parts, transmission gates and configurations when the defect cannot be activated at normal or high voltage. Comparison with EMission MIcroscopy (EMMI) in dynamic mode, which can have the higher bandwidth [8] is then possible.

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