Radial distribution function analysis of ultra low-k interlayer dielectric from electron diffraction

The continuous scaling of transistor size towards deep submicron level needs an inevitable replacement of SiO2 with a low-k dielectric material. In this study we choose three different low-k dielectric materials to determine their structural arrangement by Selected Area Electron Diffraction (SAED). The SAED analysis for the local short-range ordering has been carried out with homemade software package BEUG having been developed in our group by S. Schulze. Using BEUG, it is possible to Fourier transform the diffracted intensity distribution ending up with the radial distribution function (RDF).The bond lengths calculated from RDF between the Si-O, O-O and Si-Si have a significant change in low-k materials as compared to the corresponding lengths in bulk amorphous SiO2. These changes in bond lengths have a reasonable impact on the binding energy of the corresponding elements. We observed an inverse relation between bond lengths and binding energies for the elements present in the materials. Further the local densities of the materials have also been derived from the RDF curve.