Study on the characteristics of toluene-tetraethoxysilane hybrid plasma-polymer thin films

This study investigated the interaction of varied plasma power with ultralow- k toluene-tetraethoxysilane (TEOS) hybrid plasma-polymer thin films, as well as changing electrical and mechanical properties with varied radio frequency (rf 13.56 MHz) power of plasma. The hybrid films with low dielectric constants were deposited on silicon(100) substrates by plasma enhanced chemical vapor deposition system. Toluene and tetraethoxysilane were utilized as organic and inorganic precursors. In addition, bubbling ratio of TEOS to toluene is 1:10. The as-grown hybrid plasma-polymer thin films were characterized by Fourier transform infrared spectroscopy, atomic force microscopy (AFM), nanoindentation, I-V curves, and capacitance. To analyze their trends of electrical and mechanical properties, the thin films were grown under conditions of various rf powers. The IR spectra showed them to have completely different chemical functionalities from the liquid toluene and TEOS precursors. The AFM images showed changing of surface roughness that depended on different deposition rf powers. An MTS nanoindenter was used to measure the hardness and Young's modulus that increased as-deposition rf power increased, with the highest values being 2.69 and 27.6 GPa at 50 W of deposition rf power. An impedance analyzer was utilized for measurements of the I-V curves (for leakage current density; 1× 10-9 A cm2 at 1 MVcm) and capacitance (for dielectric constant; 1.69).