Patent ID: 7323394
Filing Date: 2008-01-29
Classification: H01L

Abstract:
1. A method of producing an element separation structure, comprising the steps of: defining a plurality of element forming regions and an element separation structure forming region for separating the element forming regions on a substrate having a surface and a lower surface opposite to the surface; forming a first thermal oxide film on the surface of the substrate; forming a silicon nitride film on the first thermal oxide film; removing the first thermal oxide film and the silicon nitride film in the element separation structure forming region; forming a groove portion extending from the surface of the substrate into the substrate in the element separation structure forming region; forming a groove portion oxide film for covering inside the groove portion; forming a pre-filling oxide film for filling the groove portion covered with the groove portion oxide film and covering exposed surfaces of the silicon nitride film and the first thermal oxide film; removing the pre-filling oxide film until the silicon nitride film is exposed and the pre-filling oxide film has a first height same as that of the silicon nitride film in the element separation structure forming region; removing the pre-filling oxide film until the pre-filling oxide film with the first height has a second height same as that of the first thermal oxide film; forming a resist layer for covering exposed surfaces of the silicon nitride film and the pre-filling oxide film; patterning the resist layer to form a resist mask having openings at the element forming regions and covering the element separation structure forming region; removing the silicon nitride film exposed from the resist mask; removing the first thermal oxide film exposed from the resist mask; removing the resist mask; forming a second thermal oxide film on an exposed surface of the substrate with the first thermal oxide film removed; and removing the second thermal oxide film and leveling the pre-filling oxide film at a third height same as that of an exposed surface of the substrate with the second thermal oxide film removed to form a filling portion.