Diffusion copper and

There are, however, several challenges with the using copper metal before it can be accepted into IC manufacturing. First, copper exhibits deep levels in the silicon band gap and copper impurities in SiOj lead to leakage. However, several materials are effective barriers to copper diffusion and their use as liner films... 

With the above in mind it is of interest to calculate the rate and extent of copper diffusion and to correlate these results with the time scale of the induction period and autocatalytic stages of the oxidation in order to determine how reasonable the proposed mechanisms are. This calculation is carried out below for conditions representative of a typical polyethylene/copper sample oxidized at 90 °C. 

A large grain size tin layer furthermore reduces the speed of copper diffusion, and thus less stress is produced compared to a rapid diffusion of copper into a small grain size tin. 

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