Identi cation of Materials in Integrated Circuit InterconnectsUsing X - Ray Absorption Near - Edge

Most integrated circuit interconnects are principally composed of a few metals , including aluminum alloyed with copper, tungsten, titanium, Al 3 Ti, and Al 2 Cu, in a silica matrix. Integrated circuit interconnects have recently been proposed as a candidate system for visualization by computerized microto-mography using absorption in the soft X-ray region. In this work, we demonstrate the feasibility of materials identiication using volume-resolved x-ray absorption near edge spectra (XANES) obtained by tomographic reconstruction. We calculate the XANES for interconnect materials near the Al K edge, experiment when possible. The signal-to-noise ratio required to distinguish among the aluminum compounds from their Al K edge spectra is shown to be about one order of magnitude higher than that needed to detect elemental aluminum.