Deposition of porous low-k thin films using Tween 80 porogen for ILD application in ULSI circuits

The porous silica low-k thin films were deposited by using Sol-gel spin coating technique. The tetraethylorthosilicate (TEOS) was used as a source of Si and the porogen Tween 80 was used for the introduction of porosity of the films. The chemical bondings of porous low-k SiO2 films have been realized by using Fourier transform infrared spectroscopy (FT-IR). The appearance of stretching, bending and rocking peaks at 1075.8, 967, 426 cm(-1) respectively confirms the formation of Si-O-Si network. The Refractive index (RI) and thickness of the films were determined by using ellipsometer. Further, from RI the density and porosity of the films was estimated using standard formula. As from results it's seems that the density of the films reduces after the addition of Tween 80. The lowest value of films density after the addition of Tween 80 was found to be 1.27 g/cm(3). The reduction in the film density results in increase of the porosity of films due to the removal of porogen during the curing. The increase in film porosity from 6% to 45% resulted in lower in the dielectric constant to 2.58.