THE EFFECT OF SOL VISCOSITY ON THE SOL-GEL DERIVED LOW-DENSITY SIO2 XEROGEL FILM FOR INTERMETAL DIELECTRIC APPLICATION

SiO2 sol was prepared using a typical two-step acid/base catalyst proc edure to investigate the effect of sol viscosity on the microstructure of SiO2 xerogel film. The viscosity of coating sol was varied in the range of 4 to 50 cP. With coating sols in the viscosity range of 10-40 cP, stable SiO2 xerogel films of 73.5-47.5% porosity could be prepare d. During the spin coating of sol, high evaporation of solvent was ine vitable and this induced the accelerated and abnormal gelation. The mi crostructure of SiO2 xerogel was found to be largely dependent on the viscosity of coating sol. Dielectric constant and leakage current dens ity were obtained in metal-insulator-semiconductor structure. The meas ured dielectric constants were ranged from 1.99 to 2.45 according to t he porous nature of xerogel films. Leakage current density measurement s showed that at low electric field strength the conduction behavior o f low density xerogel film was ohmic conduction, but at high field str ength, Poole-Frenkel electron emission was the conduction mode. (C) 19 98 Elsevier Science S.A. All rights reserved.