Ultra-Low Dielectric Properties of Porous Polyimide Thin Films Fabricated by Using the Two Kinds of Templates with Different Particle Sizes

Abstract Porous polyimide (PI) thin films have been fabricated successfully by using silica microparticles (MPs) with different particle sizes as a template, and the three dimensional porous structure has been observed clearly by mean of transmission electron microtomography. The measured values of dielectric constant (e) decreased remarkably by introducing a porous structure, compared with ordinary PI thin films. Especially, the porosity evidently increased (ca. 10%) by suitably employing silica MPs having different particle sizes, and then the value of e was further reduced. Bruggeman model could reproduce nearly the relationship between the value of e and porosity.