Nitrogen Plasma Passivation Effects on Ti-N Diffusion Barrier for Al Planarization Process

摘要

2-step cold/hot Al sputtering is one of the promising processes that can fill the sub-0.25μm contact holes, however, there are still many technical issues in 2-step cold/hot Al sputtering technology. The biggest issue is increased spiking susceptibility due to its high processing temperature that it known to enhance Al-Si inter-diffusion. In this paper, novel nitrogen plasma post-treatments were proposed and employed to the Al planarization process. Thermal stability was improved for Al interconnects with nitrogen plasma passivated titanium nitride barrier. The conventional nitrogen rapid thermal annealing (RTA) post-treatment was also applied and evaluated its feasibility. It was not as efficient in improving thermal stability as the novel nitrogen plasma post-treatments. The nitrogen plasma enhanced titanium nitride barrier had been successfully applied to Al planarization process on 0.25 μm contacts.