Issue No. 04 - October-December (1998 vol. 15)
DOI Bookmark: http://doi.ieeecomputersociety.org/10.1109/54.735930
Chip defect densities set the complexity limits of FPGAs. However, wafer-scale techniques expand this with defect avoidance routing around flawed blocks to build working systems. FPGAs have the features required for successful defect avoidance systems: repeatable cells, built-in switchable flexible routing, and potentially large number of applications. Laser-formed connections/cuts switches are effective in bypassing fabrication time defects in cell power, clocks, and signal buses, thus creating defect-free large working systems. Experiments on test FPGAs show laser defect avoidance routing signal delays 50% those of active switches. Thus laser defect avoidance after fabrication eliminates errors creating large-area FPGAs whose defective cell distribution is nearly unseen by the user.
FPGA, defect avoidance, laser linking, laser redundancy, IC yield improvement
G. H. Chapman and B. Dufort, "Using Laser Defect Avoidance to Build Large-Area FPGAs," in IEEE Design & Test of Computers, vol. 15, no. , pp. 75-81, 1998.