Reliability evaluation of multilevel thin film structures

IBM Microelectronics has evaluated the reliability of structures built by various processes which we developed for multilevel thin film (MLTF) applications. Two distinct processes were used for the building of conformal copper-polyimide structures on alumina ceramic: Laser ablation of the polyimide for via patterning and wiring defined by subtractive etching of Cr/Cu/Cr, and photosensitive polyimide for via patterning and wiring defined by electroplating through a resist. Reliability evaluation was performed on test-vehicles with both MLTF processes by a combination of IBM standard and MIL-STD-883 stress procedures. These stresses were designed to monitor any potential reliability problems due to metal migration, corrosion (or contamination), metal fatigue, and poor step coverage. Electrical measurements were done before, during, and after stress to check for opens and inter and intralevel shorts. At completion of stressing, no failures were observed in either type of test vehicles. This indicates that both processes meet or exceed IBM current product reliability standards