Polymeric dielectric layers having low dielectric constants and improved adhesion to metal lines

DETAILED DESCRIPTION The present invention provides thermally stable polymeric IMDs and ILDs having enhanced adhesiveness by introduction of an adhesive material in the IMD or ILD polymeric material.
In the preferred embodiments, the adhesive material resides only at the interface of the IMD or ILD with adjacent metalization or polysilicon layers.
One aspect of the invention generally provides an electronic circuit having a dielectric material for electrically isolating one or more conductive pathways.
Specifically, the dielectric material includes a thermally stable polymeric material having its adhesiveness to the one or more conductive pathways improved by a polar material disposed on at least an interface between the polymeric material and the one or more conductive pathways.
When the electronic circuit is an integrated circuit, at least three options for using the invention are available: (a) the dielectric material is an intermetal dielectric and the conductive pathways are metal lines of a metalization layer, (b) the dielectric material is an interlayer dielectric and the conductive pathways include polysilicon gate structures, and (c) the dielectric material is a packaging material and the conductive pathways include a top layer of metalization on the integrated circuit.
The thermally stable polymeric material may be evidenced by a glass transition temperature of at least about 300.
degree.
centigrade.
Alternatively or in addition, the thermal stability may be evidenced by the polymeric material retaining at least about 99.
5% of its mass when heated to 450.
degree.
centigrade for one hour.
Many thermally stable polymeric materials meeting this criteria are fluorocarbon polymers.
One particularly preferred fluorocarbon polymer is polyfluoropyreline.
Suitable adhesion promoting polar materials increase the polymeric material's surface energy and may include, for example, sulfur, phosphorus, nitrogen, or oxygen containing moieties.
Such polar material may be integrated within the polymeric material or it may terminate at least some of the polymer chains of the thermally stable polymeric material