A 3D analysis technique for detecting trace metal contamination

Abstract

A 3D analysis technique for detecting trace metal contamination has been developed. Trace metal contamination is contained in a site-specific failure on a semiconductor device. In this research, first, a sample extracted from the plane direction is observed in a 3D perspective using the STEM (Scanning Transmission Electron Microscope) method, which is less affected by chromatic aberration. With this method, a failure point can be localized at the sub-μm level. Next, the sample was thinned from the cross-sectional direction by the FIB (Focused Ion Beam) method and observed in a 3D perspective using the STEM method. By repeating the STEM and FIB methods, it was possible to fabricate a sample to a thickness of 0.1 μm, without missing any failure points. Moreover, element analysis (1 nm ϕ) by the EDX (Energy Dispersive X-ray) method made it possible to detect trace metal contamination (10 −20 g or less) contained in the failure point.