Reliability and Failure Mechanisms of Nonhermetic Aluminum SIC's: Literature Review and Bias Humidity Performance

The aging of aluminum metallized silicon integrated circuit (SIC) test vehicles (bare, SiN CAPS only, room temperature vulcanizing (RTV) silicone rubber only, SiN CAPS + RTV) at 85°C, 85 percent relative humidity (RH), for 12 597 h was carried out with either +10 V, -10 V, or 0 Vdc bias imposed on the samples. No failures and no unusual leakage current behavior were observed in humidity. Auger depth profiles of the passivating oxide indicate no change in oxide thickness due to temperature and humidity alone. In a moist environment, anodization of the aluminum takes place. An estimate of the median life under worst case use conditions was calculated to be better than 1.6 x 106h. This was obtained by assuming the same value of sigma and the same acceleration factors as those obtained from N-type metal-oxide semiconductor (NMOS) failure rate data applied to an Eyring Model. The results show that the failure rate for aluminum metallization under worst case use conditions is less than 1 FIT (failure in 109device hours) after 40 years. A literature survey of aluminum corrosion is also included.