An advanced optical diagnostic technique of IBM z990 eServer microprocessor

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