Studying the Dependence of Low-Frequency Noise on Geometrical Shape of Al-Based Thin Film Interconnects

摘要

In this paper the experimental results of a study conducted to investigate dependence of low-frequency noise on the geometrical shape of VLSI interconnect are discussed. The metal thin films are most commonly used in fabrication of these metallic interconnects. The interconnection lines of modern ICs have effective cross sections in the range of 1-5 square μm. Therefore, the operating currents of a few milliamps results in current densities in the range of MA/square cm. Under these conditions, the phenomenon of electromigration arises, which may lead to the failure of the interconnection lines in a time ranging from a few several hours to several years, depending on the subjected current density J and thermal stress T. To study the effect of subjected current densities and temperatures, low-frequency noise measurements were performed on a group of ten metal thin film VLSI interconnects. These measurements were carried out under stressing current densities between 1.0 x 10~5 A/ cm~2 and 2.2 x 10~6 A/ cm~2 at different heating temperatures up to 280 °C. We used a sophisticated noise measurement system based on dual-channel dynamic signal analyzer and ultra low-noise amplifier to monitor and capture the noise spectra exhibited by the samples when subjected to electrical and thermal stress. The low-frequency noise measurement system and measurement technique, metal thin film sample design, and the behavior of these samples under subjected stressing conditions are discussed in the paper.