Porous silicon dioxide insulator

DETAILED DESCRIPTION Parasitic capacitance is reduced in a semiconductor integrated circuit (IC) by forming a porous silicon dioxide insulator between at least one interconnect and other conductive regions therein.
The porous silicon dioxide layer provides mechanical integrity to the structure, while at the same time effectively reducing the dielectric constant as compared to, for example, silicon dioxide.
When, for example, porous silicon dioxide of this invention is formed between conductive digit lines in a memory cell array, noise immunity of the memory cell array is improved considerably.
Thus, packing density in such memory cell arrays can be increased, as demanded by current consumers to meet high speed, low power consumption applications.
Open digit line architecture can even be used, as compared to conventionally used folded digit line architecture, because coupling between adjacent digit lines is reduced when using the insulator of this invention.
In one aspect, the present invention provides a method for fabricating a porous silicon dioxide insulator, comprising steps of forming a substantially undoped layer of silicon carbide supported by a substrate; forming voids in the layer of silicon carbide to form a porous silicon carbide layer; and oxidizing the porous silicon carbide layer to form porous silicon dioxide.
In another aspect, the present invention provides a method for fabricating a porous silicon dioxide insulator, comprising forming a homogenous layer of silicon carbide supported by a substrate; forming voids in the layer of silicon carbide to form a porous silicon carbide layer; and oxidizing the porous silicon carbide layer to form porous silicon dioxide.
In another aspect, the present invention provides a method for fabricating a porous silicon dioxide insulator, comprising forming silicon carbide on a substrate, wherein the silicon carbide is selected from the group consisting of undoped silicon carbide, p-doped silicon carbide, and n-doped silicon carbide; forming voids in the silicon carbide to form porous silicon carbide; and oxidizing the porous silicon carbide to form porous silicon dioxide