Patent ID: 8021955

Claim:
A method of selecting a thickness of a lower dielectric layer and a thickness of an upper dielectric layer to be formed above the lower dielectric layer of a multi-layer isolation structure comprises: selecting a silicon oxycarbide (SiOC) material for a lower dielectric layer and one of a amorphous silicon carbide and a silicon dioxide material for an upper dielectric layer; selecting a range of one or more effective dielectric constants that correspond to thicknesses of both the lower dielectric material and the upper dielectric material; and determining a range of one or more thicknesses of each of the lower dielectric layer and the upper dielectric layer from the range of acceptable dielectric constants using information indicating an effective dielectric constant corresponding to thicknesses of both the lower dielectric material for the lower dielectric layer and the upper dielectric material for the upper dielectric layer, wherein the thicknesses of the upper and lower dielectric layers are arranged so that an effective dielectric constant for the multi-layer isolation structure is less than that of silicon dioxide and such that the parasitic capacitance of the multi-layer isolation structure is less than that of silicon dioxide thereby enabling the multi-layer isolation structure to be formed.