Passivation Material and Thickness Effects on the MTTF of Al-Si Metallization

Different passivation materials, namely undoped oxides (plasma and non-plasma deposited), P-doped oxide (PSG), oxynitride and their sandwiches were used to passivate the Al-Si test structures. MEF data (correlated to MTTF) were obtained from the wafer level test method called BEM (Breakdown Energy of Metal) which is presented separately in this conference by Hong and Crook [10]. The test results show: 1. The MEF of Al-Si is nearly proportional to the passivation thickness. 2. The effect of the different passivation materials was not as dominant as their thickness effect. 3. Post Aluminum heat cycles of the passivated test devices did not show improvement or deterioration of the MTTF. Conventional electromigration tests were conducted on Al-Si with different passivation thickness and the results agree with the BEM data.