| 摘要 |
PURPOSE: A method for fabricating a semiconductor device is provided to prevent a refresh characteristic from being deteriorated by forming a field stopper only under a field oxide layer in an N-type well. CONSTITUTION: A mask layer(35) is formed on a semiconductor substrate(31) having the first and second conductive wells to define an isolation region and an active region. By using the mask layer, a predetermined depth of the isolation region is etched to form the first trench(37) in the first conductive well, the second trench(38) in the second conductive well, and the third trench(39) whose one side is positioned in the first conductive well and the other side is positioned in the second conductive well. The first ion implantation mask is formed in the second conductive well on the substrate. The first field stopper(45) of the second conductivity type is formed under one part of the first and third trenches. The first ion implantation mask is removed. The second ion implantation mask(47) is formed in the first conductive well on the substrate. The second field stopper(51) of the first conductivity type is formed under the other part of the second and third trenches. The second ion implantation mask is removed. A field oxide layer is formed in the first, second and third trenches. The mask layer and the pad oxide layer are eliminated.
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