Semiconductor device having improved interconnection-wiring structures

摘要

A fourth and a fifth interlayer insulating film are formed and a connecting hole which passes through these films is formed. The connecting hole is filled with a metallic plug. The exposed surface of the fifth interlayer insulating film and metallic plug is etched back by dry etching in an atmosphere containing CF4 gas. Thus, the step difference between the surfaces of the metallic plug and fifth interlayer insulating film is reduced. The shape of the connecting hole is shaped so that its opening has a larger diameter at its upper position. The surfaces of the fifth interlayer insulating film and metallic plug are exposed to plasma atmosphere containing oxygen, irradiated with the light having a wavelength of several 10 nm to 400 nm or subjected to the sputter etching using an Ar gas.