Method for fabricating semiconductor device with metal line

A method for fabricating a semiconductor device, comprising:

• forming an inter-layer insulation layer on a substrate;
• forming openings in the inter-layer insulation layer;
• forming a metal barrier layer in the openings and on the inter-layer insulation layer;
• forming a first conductive layer on the metal barrier layer and filled in the openings;
• performing a first etching process to etch the first conductive layer to form interconnection layers in the openings, wherein the interconnection layers are formed inside the openings and at a depth from a top of the openings;
• performing a second etching process on portions of the metal barrier layer exposed after the first etching process to obtain a sloped profile of the metal barrier layer at top lateral portions of the openings, the sloped profile of the metal barrier having a rounded cusp;
• forming a second conductive layer over the inter-layer insulation layer, the interconnection layers, and the metal barrier layer with the sloped profile;
• and
• patterning the second conductive layer to form metal lines,
• wherein the second etching process comprises a dry etching process using a main etch gas for physicochemically etching the metal barrier layer and an additional gas for chemically etching the metal barrier layer.