New PI-Silica Hybrids Via Sol-Gel Process for Thin Film Dielectric Materials

Abstract

A new class of polyimide-silica hybrid materials for thin film microelectronics were successfully prepared by the sol-gel reaction of tetraethoxysilane (TEOS) in the solution of polyimide precursor in N.N′-dimethylformamide. The composite films were obtained by the hydrolysis and polycondensation of TEOS in the polyimide precursor solution, followed by heating at 270 °C. The chemical structures of polyimide-silica hybrid films were characterized by analytical techiques. X-ray diffraction showed that the polyimide-silica hybrid material has an amorphous structure. The hybrid material was quite stable at elevated temperatures (> 400 °C), with the associated weight loss of 10 wt % only around 600 °C. The dielectric constant of the polyimide-silica (50 wt%) composite measured by ellipsometry was 3.935 to 3.885 as a function of frequency in the range of 1kHz to 20kHz.