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In this paper, we describe an advanced optical diagnostic technique used for diagnosing the IBM z990 eServer microprocessor (Slegel et al., 2004). Time-to-market pressure demands quick diagnostic turnaround time and high diagnostic resolution while the ever increasing design complexity, density, cycle time, and shrinking technologies dramatically add difficulties to diagnostics. Although design-for-test (DFT) and design-for-diagnostics (DFD) features are implemented in the latest microprocessors to help easing the diagnostic efforts, they may still not be sufficient to diagnose certain fails. The well-known picosecond imaging circuit analysis (PICA) (Kash and Tsang, 1997) tool, equipped with the high quantum efficiency superconducting single-photon detector (SSPD,) shows a unique diagnostic capability for optically probing the internal nodes of a chip. Several hard-to-diagnose examples will be used to demonstrate the unique capabilities of this technique |
