US Patent 7906396 Flash memory and method of fabricating the same

In a method of fabricating a flash memory, a substrate with isolation structures formed therein and a dielectric layer and a floating gate formed thereon between isolation structures is provided. A mask layer is formed on the substrate, covering the isolation structures in a periphery region and the isolation structure in a cell region adjacent to the periphery region. The isolation structures in the cell region not covered by the mask layer are partially removed. Therefore, a first height difference is between surfaces of the isolation structures in the periphery region and a surface of the dielectric layer, and between a surface of the isolation structure in the cell region adjacent to the periphery region and the surface of the dielectric layer. A second height difference smaller than the first height difference is between surfaces of other isolation structures in the cell region and the surface of the dielectric layer.