| 摘要 |
<p>A method for fabricating a flash memory device is provided to avoid a program disturbance defect caused by dislocation of an isolation layer in a program preventing cell by forming a trench for forming an isolation layer wherein the center part of the trench has a negative slope and by forming an inner wall insulation layer and a liner oxide layer by a proper deposition method. A trench whose center part is convex is formed in an isolation region of a semiconductor substrate(52). An insulation layer is formed on the inner wall of the trench in a manner that voids(V) are formed between the inner wall of the trench and the insulation layer in the intermediate part of the trench. The trench is filled with a buried insulation layer to form an isolation layer. The process for forming the trench can include the following steps. A gate insulation layer is formed on the semiconductor substrate. A polysilicon layer(56) to be used a floating gate is formed on the gate insulation layer. An etch stop layer is formed on the polysilicon layer. A mask layer for defining a trench formation region is formed on the etch stop layer. By using the mask layer as an etch mask, the etch stop layer, the polysilicon layer and the gate insulation layer are etched to expose the substrate where the trench is to be formed. A predetermined depth of the exposed substrate is etched to form the trench.</p> |
