High-Resolution Thermal Wave Imaging of Surface and Subsurface Defects in IC Metal Lines

Abstract

Using a thermal wave imaging system we have been able to detect and identify a variety of microscopic defects commonly found in fine metal Al connector lines used in the IC industry. The defects of interest are hillocks, surface and subsurface Si and Cu precipitates and subsurface voids and notches. Defects as small as 0.1 ~m have been detected. This thermal wave imaging system has also been used to detect subsurface defects in Al and W metal contact plugs.