The Effects of Phosphorus-Doped Passivation Glass on the Corrosion of Aluminum

The corrosion rate of aluminum metallization under bias was measured as a function of the phosphorus content of the CVD passivation glass under different temperature and humidity conditions. The electrolytic corrosion was the most intense at the negative electrode and the corrosion product was aluminum hydroxide Changing the phosphorus concentration from 2 to 10 wt. pct. increased the corrosion rate by a factor of 25. Increasing the relative humidity at 85°C from 85 to 100% caused the corrosion gate to increase by two orders of magnitude. A 30°C rise in temperature resulted in five times the corrosion rate. A model to account for the observed corrosion has been proposed.