Abstract: A method of forming memory device is provided. A substrate having at least two cell areas and at least one peripheral area between the cell areas is provided. A target layer, a sacrificed layer and a first mask layer having first mask patterns in the cell areas and second mask patterns in the peripheral area are sequentially formed on the substrate. Sacrificed layer is partially removed to form sacrificed patterns by using the first mask layer as a mask. Spacers are formed on sidewalls of the sacrificed patterns. The sacrificed patterns and at least the spacers in the peripheral area are removed. A second mask layer is formed in the cell areas. Target layer is partially removed, using the second mask layer and remaining spacers as a mask, to form word lines in the cell areas and select gates in a portion of cell areas adjacent to the peripheral area.

Abstract: A method of forming memory device is provided. A substrate having at least two cell areas and at least one peripheral area between the cell areas is provided. A target layer, a sacrificed layer and a first mask layer having first mask patterns in the cell areas and second mask patterns in the peripheral area are sequentially formed on the substrate. Sacrificed layer is partially removed to form sacrificed patterns by using the first mask layer as a mask. Spacers are formed on sidewalls of the sacrificed patterns. The sacrificed patterns and at least the spacers in the peripheral area are removed. A second mask layer is formed in the cell areas. Target layer is partially removed, using the second mask layer and remaining spacers as a mask, to form word lines in the cell areas and select gates in a portion of cell areas adjacent to the peripheral area.

Abstract: The invention is directed to a method for adjusting sizes and shapes of plug openings for border plug openings overlapping with trenches respectively, wherein the border plug openings are separated from each other with a distance equal to or smaller than a specific distance. The method comprises performing an adjusting process for separating the border plug openings away from each other and enlarging the dimensions of the border plug openings so that the border plug openings are located within the trenches respectively and the edges of the borer openings are separated from the sidewalks of the trenches, wherein the border plug openings are enlarged within ranges of the trenches respectively.