Yield enhancement of a 16.6 cm2 monolithic large-area integrated multiprocessor system using laser reconfiguration

A 16.6 cm² monolithic large-area integrated multiprocessor system comprising nine identical programmable video signal processing elements was reconfigured by excimer laser-formed connections and discontinuities of conductor lines in a redundant bus system. The total yield enhancement of processors using laser reconfiguration amounts to 13.3%. On the prototypes, up to six processors per chip were functional at 66 MHz, providing a peak arithmetic performance of 6 GOPS per multiprocessor system. The power supply to defective processors with a high stand-by power consumption was terminated by laser, leading to a halving of power consumption. Furthermore, for the improvement of the laser process, vertical links between two metallization levels were formed on two chips with different standard CMOS layer sequences on special test structures. For the yield statistics of the formed vertical links, a contact resistance R_K larger than 3 Ω was treated as a failure. With the laser processing of vertical links with an area of 14×14 μm² , a yield of 100% has been achieved. Beyond those, conventional accelerated life time tests were performed to examine the reliability of laser-formed vertical links. In microelectronic systems, a failure rate of 10 FIT/layer in 11.4 years corresponding to 0.1% failures is accepted. An extrapolation of Black´s equation to operating conditions (100°C, 2.5 mA) resulted in a failure rate of 0.1% in a time of 39 years