Fully planarized multilevel interconnection using selective SiO₂ deposition

A fully planarized mutilevel interconnection technology using both selective SiO₂ and tungsten deposition techniques has been developed. Selective SiO₂ deposition is performed by Liquid Phase Deposition (LPD) using a supersaturated hydrofluosilicic acid (H₂SiF₆) aqueous solution. LPD-SiO₂ film deposition and its properties have been investigated. It has become clear that the film properties for interlayer dielectrics are superior to those of CVD-SiO₂ film. Selectivity of LPD-SiO₂ deposition to on CVD-SiO₂ against on photoresist patterns is good. This good selectivity is caused by wettability difference. Full planarization of interlayer using selective LPD-SiO₂ deposition with a photoresist mask has been realized. Fully planarized two level tungsten interconnection using both LPD-SiO₂ deposition and selective CVD via filling has been demonstrated. Via hole contact resistance was as low as 0.33 Ω at the diameter of 0.8 μm.