An evaluation of Fuchs-Sondheimer and Mayadas-Shatzkes models below 14nm node wide lines

The applicability of the Fuchs-Sondheimer and Mayadas-Shatzkes scattering models below the 14nm node with wide interconnect trenches of variable aspect ratio is investigated. The aspect ratio of these lines was varied between 1.2, 1.8, and 2.5; and the grain structure was concurrently manipulated. As the vertical dimension varied from greater than and less than the mean free path in Cu (39nm) at 21 degrees C, the experiment found that the current approximation to the Fuchs-Sondheimer equation requires adjustment to the leading coefficient. Further, parameter fitting leads to the conclusion that specularity in these samples has a negative value of -0.2. The negative specularity is explained by surface roughness. The Mayadas-Shatzkes model retains its applicability and fits the data with a reflectivity of 0.16-0.17. (C) 2019 Author(s).