Metal interconnect fabrication with dual plasma silicon dioxide

Abstract

In the fabrication of an integrated circuit, an intermetal dielectric is formed using a plural plasma processes that can be performed without having to transfer the wafer in the interim. This saves on wafer handling. A wafer with a patterned first metal wafer is placed into a plasma chamber. A relatively low-power noble gas plasma is applied to clean the wafer. A reactive plasma treatment is then used to deposit silicon dioxide to a thickness greater than ultimately desired. A noble gas plasma is used to etch back the silicon dioxide. Spin-on glass is then applied. The previous etch back aids the conformance of the spin-on glass to the underlying structure. The spin-on glass can be polished for further planarization. A second silicon dioxide layer can be deposited on top of the spin-on glass. Via apertures can be photolithographically defined through the three-layer dielectric. Finally, second layer metal is deposited and patterned. The method provides for high wafer throughput, while minimizing voids at the interface between the spin-on glass and the underlying silicon dioxide layer.