Method for fabricating dynamic random access memory device

A method for fabricating a dynamic random access memory (DRAM) device is provided. Two separated masking layers are formed on a substrate. A material layer is conformably formed on the substrate with mask layers, such that the material layer between the mask layers has a recess region therein. Two spacers are formed on the opposing sidewalls of the recess region to define a first region between the spacers and two second regions between the spacers and the mask layer. Multiple etching processes are performed using the mask layers and the spacers as etching masks to correspondingly form a first trench and two second trenches in the first region and the second regions of the substrate. The depth of the first trench is deeper than that of the second trenches. A dummy gate layer is filled into the first trench and gate layers are respectively filled into the second trenches.