Air-gaps for electrical interconnections

The fabrication of air-gap structures for electrical interconnections has b een demonstrated using a sacrificial polymer encapsulated in conventional d ielectric materials. The air-gap is formed by thermally decomposing the sac rificial polymer and allowing the byproducts to diffuse through the encapsu lating dielectric. The diffusivity of the polymer decomposition products is adequate at elevated temperatures to allow the formation of an air-gap. Th e decomposition of a 5 mu m thick polymer film results in less than 100 Ang strom of residue. Electromagnetic simulation shows that the effective diele ctric 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.