| 摘要 |
PURPOSE:To smooth the stepwise difference on the shoulder of the lower layer wirings of a PSG film and to simultaneously prevent the decrease in the thickness of an interlayer insulating film on the shoulder of the lower layer wirings by forming the lower layer wirings having an overhang insulating film on the upper surface on a substrate, forming the PSG film to become the interlayer insulating film on the entire substrate surface including the insulating film on the lower layer wirings, and heat treating it. CONSTITUTION:A metal layer to become lower layer wirings such as a polycrystalline silicon layer 10 is formed through the first insulating film 9 made of SiO2 on a semiconductor substrate 8, and the second insulating film 11 made of SiO2 by thermal oxidation is formed. A resist 12 of lower layer wiring shape is formed on the film 11, which is etched in a lower layer wiring shape. Then, a plasma etching using, for example, CF4+O2 gas is performed to form the lower layer wiring 13 of polycrystalline silicon. After the resist 12 is removed, a PSG film 15 is formed on the entire surface of the substrate 7 including the film 11 on the wirings 13. A stepwise difference 17 of the film 15 is formed on the position corresponding to the shoulder 16 of the wirings 13 at this time. Thereafter, when high temperature heat treatment is performed, the difference 17 is smoothly shaped. An upper layer wirings 18 are formed of aluminum on the film 15 to form multilayer interconnection. |
