Impact of Barrier Deposition Process on Electrical and Reliability Performance of Cu/Cvd Low K Sioch Metallization

Integration of Cu with low k dielectrics provided solution to reduce both resistance–capacitance time delay and parasitic capacitance of BEOL interconnections for 130nm and beyond technology node. The motivation of this work is to study and improve electrical and reliability performance of two-level Cu/CVD low k SiOCH metallization from the results of diffusion barrier deposition schemes. Barrier deposition schemes are (a) high-density-plasma 250Å Ta; (b) surface treatment of forming gas followed by high-density-plasma 250Å Ta and (c) bi-layer of 100Å Ta(N)/150Å Ta. In this work, we demonstrated the superior and competency of high-density-plasma Ta deposition for Cu/CVD low k metallization and achieved excellent electrical and reliability results. Wafers fabricated with high-density-plasma Ta barrier scheme resulted in the best electrical yields, >90% for testing vehicles of dense via chains (via size=200nm) and interspersed comb structures (width/space=200nm/200nm). Dielectric breakdown strength of the interspersed comb structures obtained at electric field of 0.3MV/cm was ∼4MV/cm.