Linewidth dependence of notchlike void generation in fine aluminum conductors

Abstract

In a silicon integrated circuit, stress-induced void generation in fine Al conductor lines degrades device reliability. Optically observable void (often called ‘‘notchlike void’’) generated during the manufacturing process was investigated. It was experimentally observed that void generation decreases with decreasing linewidth in the width range narrower than about 1.8 μm. The reduction was attributed to the decreasing gradient of tensile stress in the line. The stress gradient was obtained by stress analysis using a numerical simulator. It was proposed from the determined activation energy of Al diffusion that lattice diffusion of Al atoms is the rate limiting process for notchlike void generation.