The improvement of Al-Si-Cu alloy interconnects by hafnium and boron addition

It is shown that a few hundred p.p.m. of Hf and B addition is useful for improving the quality of Al-Si-Cu alloy film as an interconnect material, without changing the manufacturing feasibility. The effect of the addition of Hf and B on hillock formation was evaluated by adding them separately or simultaneously to Al-Si and Al-Si-Cu alloys. The migration resistance of the Al alloy films is also presented. The etching characteristics of the material are almost the same as those of the Al-Si-Cu alloy film, and the simultaneous addition of Hf and B significantly suppresses hillock formation in Al-Si-Cu alloy films. The migration resistance of the metal lines for the Hf modified sample shows 100 times longer life than Al-Si, and the Hf and B modified sample has longer lifetime than the Hf modified sample