TEM characterization of ALD layers in deep trenches using a dedicated FIB lamellae preparation method

Driven by the shrinking of microelectronic devices there is a demand for novel high-k insulators and electrode materials. Recently, atomic layer deposition was integrated into volume production to coat the extreme geometries of modern DRAM capacitors. In order to evaluate next generation materials for those applications we introduce a sophisticated, modified TEM lamellae preparation using H-bars and FIB technology that allows to uncover buried features not accessible by conventional preparation. This technique was used to study the film properties of HfO₂, AlN and TaN ALD layers in deep trench structures with aspect ratio up to 50:1. It was demonstrated that the method provides cross section lamellae with low FIB damage as deep as 7 µm below the original sample surface.