.0.14 Micron Process Aluminum Interconnect Electromigration Reliability Improvement

The reliabilities of semiconductor chips are very important topics for academica research and industrial production, of which the electro-migration (EM) of interconnects is the most challenging issues. As we know, ultra-deep submicron Al interconnection is a key technology for chip production, however, with the feature size of integrated circuits down-scaling, the EM failure of Al interconnects becomes much severer. Thus, this thesis focuses on the EM issue of the Al interconnects for 0.14μm technology node that is developed from 0.15μm counterpart, and comprehensively studies the mechanisms of the influence of process condition on the EM reliability of the Al interconnects, therefore, some possible solutions are addressed. The main achievements are listed as follows:(1) The effect of the Ti/TiN deposition process on the EM reliability of the Al interconnects is investigated. The results indicate that the stack of ionized-metal-plasma (IMP) deposited Ti and magnetic sputtered TiN (i.e., i-Ti) exhibits the strongest ability to resist the EM. Furthermore, the thickness, square resistance, surface reflectivity and XRD of the films are measured in the case of different process condition, revealing that the improvement of the EM reliability should be attributed to the growth of the preferential Al (111) orientation in terms of the i-Ti diffusion barrier.(2) The influence of post-Ti vaccum breaking and post-TiN vaccum breaking on the ability to resist the EM of the Al interconnects are compared together with the normal deposition process. The results show that the post-TiN vaccum breaking can improve significantly the EM reliability of the Al interconnects. Further, this should be mainly ascribed to the formation of Al(111) grains with more uniform sizes. Moreover, the post-TiN vaccum breaking leads to the growth of more Al (111) orientation, which is helpful to resist the EM of Al interconnects.(3) By increasing the critical dimension of via by 10nm and overetching the bottom TiN, the medium time of failure (MTF) of the Al interconnects increases by around 25%, meanwhile, the via resistance decreases by～40% in comparison with the regular via. Further, the TiN overetching-induced volcanic eruption of W cannot be observed. Key Words:Al interconnects, electro-migration, Ti/TiN films, medium time of failure (MTF)Classification:TN305.7...