Effect of porogen residue on electrical characteristics of ultra low- k materials

Porogen residue (sp 2 hybridized carbon) formed during UV curing of low- k materials increases leakage current and decreases breakdown voltage of low- k materials. The amount of porogen residue increases with increasing porosity of PECVD low- k films because of larger amount of co-deposited porogen. Electrical characteristics of PECVD ultra low- k films are significantly worse in comparison with CVD and SOG low- k film prepared without porogen. SOG low- k films prepared by self-assembling of nanocrystalline silica demonstrate very low leakage current. Removal of porogen residue significantly improves the electrical characteristics. Therefore, preparation of porogen residue free low- k films is an important challenge of future scaling of low- k materials.