| 摘要 |
PROBLEM TO BE SOLVED: To provide a method and a structure for establishing reliable, low-resistance connection between damascene copper wiring of upper level and damascene tungsten wiring of lower level. SOLUTION: A method for forming a dual-damascene copper interconnect portion 120, that is connected to damascene tungsten wiring at a lower level comprises a step of forming a first layer 90, which includes tungsten interconnect regions, electrically insulated by an insulating material on a semiconductor substrate 110; a step of forming a silicon nitride layer on the first layer 90, and a silicon dioxide layer 150 on the silicon nitride layer; a step of forming a continuous space, by etching two connection troughs passing through the silicon dioxide layer and the silicon nitride layer to expose the underlying tungsten interconnect regions and by etching a top portion of the silicon dioxide layer between the two connection troughs to reduce sharp edges of the silicon dioxide layer between the two connection troughs; and a step of filling the continuous space with damascene copper, to electrically connect the dual damascene copper interconnect portion to the exposed underlying tungsten interconnect regions. COPYRIGHT: (C)2008,JPO&INPIT
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