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Internal node timing probing of silicon integrated circuits (ICs) has been a mainstay of the microelectronics industry since very early in its history. In recent years, however, due in part to the increase in the number of interconnection layers and continued proliferation of packaging techniques exposing only the silicon substrate, conventional probing technologies such as e-beam and mechanical probing have become cumbersome or impractical. In an effort to continue transistor-level probing, backside optical probing technologies have been developed and adopted [1]. Chronologically, such techniques include picosecond image circuit analysis (PICA)[2], laser voltage probing (LVP)[3], and dynamic or time-resolved emission (TRE)[4]. In typical examples of backside probing the device under test (DUT) relies on device stimulation from automatic test equipment (ATE) or equivalent bench top setup. This generally requires a specially designed DUT card designed to accommodate a low-profile socket and lid. The DUT card, which is significantly smaller than the tester motherboard, is designed to fit within the chamber opening of the probe system in order to interact with the optical column. Tester stimulation of packaged parts, however, does not address the need to probe the DUT in-situ and in the intended application, such as a PC board. It is often desirable to probe the DUT under conditions typical of the final product or running standardized application based tests. We present here this application and have addressed some of the challenges associated with PC card based optical probing and show successfully performed time-resolved emission on a second-generation advanced graphics processor in a standard graphics card.

A new tool (Schlumberger IDS 2000) has become available for acquiring waveforms from C4 (also known as flip chip) packaged IC’s. The waveform acquisition technique is based on electro-optic sampling through the backside of silicon. After explaining the physics of electro-optic sampling, the technique is demonstrated through the backside of Si on a simple diode test structure and a flip chip microprocessor. Also, many of the issues and challenges with this tool are discussed.

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