2-dimensional distribution of dielectric constants in patterned low-k structures by a nm-probe STEM/valence EELS (V-EELS) technique

2D distribution of dielectric constants or damage in porous low-k trench structures have been characterized with nm-order space resolution by valence electron energy loss spectroscopy (V-EELS) combined with scanning transmission electron microscopy (STEM) for the first time. Kramers-Kronig analysis (KKA) was carried out to estimate dielectric constants from V-EELS spectra. The results derived from the STEM/V-EELS technique showed that the dielectric constant at a side wall was higher than that at a central region in a trench patterned porous poly-methylsilsequioxane (MSQ) film. It is shown that the STEM/V-EELS technique combined with KKA is a unique technique to investigate changes in local structures and dielectric constants of low-k films, caused by such as plasma treatments, in fine structures.