Semiconductor device and its manufacturing method

A semiconductor device comprising:

• a substrate having an electrically conducting portion;
• a plurality of wirings lying above the electrically conducting portion and insulated from the electrically conducting portion;
• a first top protection layer formed on the top surface of each said wiring;
• a second top protection layer made of a material higher in etching rate than the first top protection layer, said second top protection layer being formed on the top surface of each said first top protection layer;
• a side protection film formed on each side surface of the first top protection layer, the second top-protection layer and said wiring;
• an inter-layer insulation film made of a material with a higher etching rate than the first top protection layer, said inter-layer insulation film filling a space between the wirings and covering the second top protection layer;
• and
• a contact hole penetrating the inter-layer insulation film between the wirings and reaching said electrically conducting portion, said contact hole having a step portion formed on inner walls of said contact hole due to projections of the side protection films.

A manufacturing method of a semiconductor device, comprising:

• forming a plurality of wirings on a substrate;
• forming a first top protection layer protecting top surfaces of the wirings;
• forming second top protection layers on the top surfaces of the first top protection layers, said second top protection layers being higher in etching rate than the first top protection layers;
• forming side protection films on each side surfaces of the wirings, the first top protection layers and the second top protection layers;
• depositing an inter-layer insulation film to fill a space between adjacent said wirings and to cover the second top protection layers, said inter-layer insulation film being made of a material higher in etching rate than the first top protection layers;
• and
• locally etching the inter-layer insulation film between adjacent said wirings in substantial self-alignment by using the second top protection layers and the side protection film.