Interlevel dielectric with multiple air gaps between conductive lines of an integrated circuit

Claim 1

In an integrated circuit having a plurality of semiconductor devices, multilevel interconnections with levels of conductive lines having interconnection therebetween for interconnecting the semiconductor devices comprises: at least one level of conductive lines with a pair of conductive lines separated by a gap between opposing walls of the lines and having a length dimension in the longest dimension in a direction; a composite insulation formed from a plurality of solid insulating material portions each having a dimension in said direction less than the length dimension of said pair of conductive lines and disposed in the gap between said opposing walls of said pair of conductive lines and each portion being separated from an adjacent portion by a single space filled with a gas having a dielectric constant of slightly above 1, said solid insulating material portions disposed in the gap being of a size and shape to permit the solid insulating material to support a deposited upper insulating layer but limited in number so that the dielectric constant of the composite insulation of solid insulating material and gas in the spaces over the length of the pair of the conductive line is not greater than about 3.0.