Fabrication and characterisation of nanoscale programmed defects for EUV lithography

In this paper we have developed and characterised with several measurement techniques a process achieving ultra-smooth nanoscale programmed defects for EUV lithography applications. The originality of this work consists in manufacturing defects of different width (25, 50, 75, and 100 nm) and height (20, 40, and 80 nm), for various densities (1 def/50 μm 2, 1 def/150 μm 2, 1 def/300 μm 2, and 1 def/500 μm 2), all together on the same wafer. Square dots have been manufactured by high resolution e-Beam lithography, using a hydrogen silsesquioxane (HSQ) resist. Three lithographic process iterations are applied to the same wafer using different HSQ solution concentrations. Finally, top-down CD-SEM, light scattering particles counting tools and atomic force microscope measurements were performed in order to check if the programmed defects were correctly printed and to monitor their dimensions. As a result, the fabrication procedure has been shown successful in term of location and size accuracy.