Something about copper aluminum etching

[cicididi]

A steady demand for increasing performance in the electronics industry has driven integrated circuit technology to faster operation and more densely packed circuits. This translates to smaller devices and smaller propagation delays. In particular, the cross section of conductive interconnections among devices decreases with circuit downsizing, but an increase in their resistance and stray capacitance will degrade propagation delay times. This has led to the replacement of polysilicon interconnections with more conductive materials such as silicided polysilicon, copper aluminum etching, and tungsten. Indeed, aluminum alloy interconnections for top metal level is industry standard; but large current densities used in small cross sectional aluminum interconnections leads to electromigration