Laser reconfiguration for yield enhancement of a 16.6 cm2 monolithic multiprocessor system

A 16.6 cm² monolithic large area integrated multiprocessor system comprising 9 identical programmable video signal processing elements was reconfigured by excimer laser formed connections and discontinuities of conductor lines in a redundant bus system. The yield enhancement of functional processors amounts to 13.3%. On two prototypes, the laser reconfiguration of the bus system led to 4 functional processors per chip at 66 MHz, providing a peak arithmetic performance of 4 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 >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. An extrapolation of Black´s equation to operating conditions (100°C, 2.5 mA) resulted in a failure rate of 0.1% in 39 years