W88 integrated circuit shelf life program

Abstract

The W88 Integrated Circuit Shelf Life Program was created to monitor the long term performance, reliability characteristics, and technological status of representative WR ICs manufactured by the Allied Signal Albuquerque Microelectronics Operation (AMO) and by Harris Semiconductor Custom Integrated Circuits Division. Six types of ICs were used. A total of 272 ICs entered two storage temperature environments. Electrical testing and destructive physical analysis were completed in 1995. During each year of the program, the ICs were electrically tested and samples were selected for destructive physical analysis (DPA). ICs that failed electrical tests or DPA criteria were analyzed. Fifteen electrical failures occurred, with two dominant failure modes: electrical overstress (EOS) damage involving the production test programs and electrostatic discharge (ESD) damage during analysis. Because of the extensive handling required during multi-year programs like this, it is not unusual for EOS and ESD failures to occur even though handling and testing precautions are taken. The clustering of the electrical test failures in a small subset of the test operations supports the conclusion that the test operation itself was responsible for many of the failures and is suspected to be responsible for the others. Analysis of the electrical data for the good ICs found no significant degradation trends caused by the storage environments. Forty-six ICs were selected for DPA with findings primarily in two areas: wire bonding and die processing. The wire bonding and die processing findings are not surprising since these technology conditions had been documented during manufacturing and were determined to present acceptable risk. The current reliability assessment of the W88 stockpile assemblies employing these and related ICs is reinforced by the results of this shelf life program. Data from this program will aid future investigation of 4/3 micron or MNOS IC technology failure modes.