Method for fabricating semiconductor device with fine patterns

A method for fabricating a semiconductor device, comprising the steps of:

• forming a plurality of conductive structures on a substrate provided with a cell region and a peripheral region;
• forming an etch stop layer on the conductive structures;
• forming an inter-layer insulation layer on the etch stop layer;
• planarizing the inter-layer insulation layer and the etch stop layer by removing the inter-layer insulation layer and the etch stop layer until the conductive structure is exposed;
• forming a nitride layer for forming a hard mask on the planarized conductive structures and the inter-layer insulation layer;
• forming an anti-reflective coating layer on the nitride layer;
• forming a photoresist pattern on the anti-reflective coating layer through a photolithography process by using a light source of ArF;
• selectively etching the anti-reflective coating layer and the nitride layer with use of the photoresist pattern as an etch mask to thereby form a hard mask;
• removing the photoresist pattern and the anti-reflective coating layer;
• etching the inter-layer insulation layer disposed between conductive structures with use of the hard mask as an etch mask to thereby form a contact hole exposing the etch stop layer;
• removing the exposed etch stop layer, thereby exposing the substrate;
• cleaning inside the contact hole;
• forming a conductive plug layer to be electrically connected with the exposed substrate;
• performing a first etch-back process for exposing the hard mask under a condition that the conductive plug layer is etched faster than the hard mask;
• and
• performing a second etch-back process for exposing the inter-layer insulation layer under a condition that the hard mask is etched faster than the conductive plug layer, thereby obtaining at least one isolated plug.