Method for forming a multi-layer metallic wiring structure

Abstract

After accumulating a BPSG film layer on a silicon substrate, a first Al--Si--Cu film layer, a W film layer and a second Al--Si--Cu film layer are successively accumulated on this BPSG film layer. A resist pattern with wide-width and narrow-width pattern portions is formed on the second Al--Si--Cu film layer. The wide-width pattern portion is provided at a position corresponding to a contact for connecting a first-layer metallic wiring and a second-layer metallic wiring, while the narrow-width pattern portion is provided at a position corresponding to a wiring portion for the first-layer metallic wiring. After applying first etching on the second Al--Si--Cu film layer with a mask of the resist patter, second etching is applied on the W film layer. Thereafter, by applying third etching, the resist pattern remaining on the first-layer metallic wiring is removed and the first Al--Si--Cu film layer is transfigured into a tall metallic film portion and a short metallic film portion. After accumulating an inter-layer insulating film layer on the first Al--Si--Cu film layer, etchback is applied on this inter-layer insulating film layer until the top of the tall metallic film portion is bared. Then, the second-layer metallic wiring is formed on the inter-layer insulating film layer so that the second-layer metallic wiring is connected with the tall metallic film portion.