PURPOSE: To prevent an interlayer insulating film from being irregular in thickness and clevis from occurring at a fine groove by forming an organic resin layer and an insulating layer in a laminated shape on a conductor wiring layer, then etching back in two stages to have selectivity of another etching gas type for both, and then forming newly an insulating layer as an interlayer insulting film.

CONSTITUTION: An organic coating film 15 is etched back in a first stage, for example, by a reactive ion etching method with oxygen gas. Then, with remaining organic coating film 15a on a stepwise side 23 and a stepwise groove 24 as a mask an insulating layer 14 is etched back in second stage, the layer 14 on a conductor wiring layer 13 is completely removed, the remaining film 15a is removed, and an insulating layer 16 is newly formed as an interlayer insulating film on the layer 13, the top of the remaining insulating layer 14a, and other substrate by a CVD method. A fine groove can be flattened without clevis by suitably setting the etching selectivity ratio of the film 15a to the layer 14.