Charging and Aging Effects in Porous ULK Dielectrics

The down-scaling of CMOS interconnects increases dielectric reliability challenges. Porous ULK materials used in advanced interconnects may suffer from charge trapping and detrimental aging during bias-thermal stress experiments. We demonstrate that a threshold between charging and aging domains may occur for an injected electrical energy of 0.1 MJ/cm3. Electron injection in the dielectric induces hydrogen radical formation first. For more damaging current stressing, in-situ Auger experiments demonstrate that the degradation is mostly due to the modification around carbon bonds.