Wafer-scale integration defect avoidance tradeoffs between laser links and Omega network switching

Abstract

Area, signal delay, and power consumption requirements are obtained in both 3 micron and 1.5 micron CMOS for two wafer scale defect avoidance methods: laser linking and active switching. In laser linking, focused laser power is used at each site to interconnect and cut bus lines. Active switching elements, such as the Omega network, enable real-time defect bypassing for self healing reconfigurations. Comparisons using simulations and fabricated device measurements of an Omega switch relative to laser links shows the area ranges from 5 to 11 times larger (respectively for the 1.5 and 3 micron processes), it requires an extra 18 to 25 nsec of signal delay and cell drivers to consume 60% more power than the laser links. Laser linked signal paths are so much faster than active switches that they effectively bypass failed switches without introducing significant extra delay. Thus a superior defect avoidance switch combines laser links and the Omega switch into a single unit.