Traceable 3D Metrology For Manufacturing Reliable High Aspect Ratio Tsv Interconnects

The aim of WP1 is to accurately measure (at micron and submicron resolution) dimensional and structural properties of high aspect ratio (HAR>10) TSV interconnects before and after Cu filling. This will be done by developing the first reliable 3D characterisation techniques (traceable AFM based methods, SEM and FIB/SEM techniques, TEM, IR microscopy and SAM, X-ray spectrometry, Raman spectroscopy, DLTS and synchrotron based methods). The parameters to be measured are sidewall roughness, via shape, seed- and barrier-layer thickness, sidewall layer conformity, void detection and characterisation, grain size and grain boundary character distribution of the copper grains, crystalline structure, dislocations, stress around TSV.

WP1 will also develop methods to accurately measure electrical and thermal transport properties of nanostructured copper TSV interconnects in order to establish traceable measurements of electrical conductivity and temperature change in copper as a function of the current density. Modelling of thermal transport in those structures will help to identify the various thermal scattering mechanisms in nanostructured copper grains. First TSV structures and arrays will be produced and these will be used to validate the measurement techniques and methodologies developed.

A stack of 9 dies connected with Through Silicon Vias

A stack of 9 dies connected with Through Silicon Vias (Image courtesy of Fraunhofer IZM)

Nano-Observer atomic force microscope

Nano-Observer atomic force microscope (image courtesy of LNE)