A method is provided for use on a DRAM (dynamic random access memory) device for forming a data storage capacitor with a wide electrode area, and thus a high capacitance, for the DRAM device. The high capacitance allows the data storage capacitor to preserve high data retaining capability when the DRAM device is downsized for high integration. The method is characterized in the forming of silicon-nitride based sidewall spacers and polysilicon-based sidewall spacers in openings formed in oxide layers that allows the subsequently formed contact window to be narrowed to a reduced width, thereby preventing the subsequent etching process to damage the nearby polysilicon-based bit lines and gate electrodes due to misalignment in the etching. Moreover, the method allows the resultant data storage capacitor to have a wide electrode area that helps increase the capacitance thereof, thereby allowing the DRAM device to preserve a high and reliable data retaining capability to the data stored therein.