Ion Microprobe Analysis of Integrated Circuit Structures

The ion microprobe mass analyzer was used to determine the presence of both intentional and unintentional impurities in integrated circuit structures. The in-depth distribution of these impurities and their relative concentrations was determined by ion sputtering through the layers of the circuit. Analysis of areas where each layer has a matrix element change, e.g., SiO2 to silicon, was used to relate sputter time to layer interfaces. Impurities detected in dielectric films include carbon fluorine, zinc, tin, lead and barium, while resistors were observed to contain lead and tin.