Air-gaps for electrical interconnections

The fabrication of air-gap structures for electrical interconnections has been demonstrated using a sacrificial polymer encapsulated in conventional dielectric materials. The air-gap is formed by thermally decomposing the sacrificial polymer and allowing the byproducts to diffuse through the encapsulating dielectric. The diffusivity of the polymer decomposition products is adequate at elevated temperatures to allow the formation of an air-gap. The decomposition of a 5 mu m thick polymer film results in less than 100 Angstrom of residue. Electromagnetic simulation shows that the effective dielectric constant of silicon dioxide (epsilon = 4.2) can be lowered to 2.4-2.8 for relevant structures. (C) 1998 The Electrochemical Society, Inc. S1099-0062(98)01-087-6.