The development of integrated circuits(IC), especially the exploration of ultralarge integrated circuits(ULSI) is essential to the fabrication of modern semiconductor devices, and thus is the basis of our information society. Owing to the excellent electron-transfer resistance and the low electrical resistance, the copper interconnects have been widely used in the IC fabrication, especially after the chemical mechanical polishing(CMP) was successfully introduced into the IC planarization. Additionally, unlike aluminum based metal interconnect systems which are formed by subtractive etch processes, copper