SEMICONDUCTOR MEMORY DEVICE AND FABRICATION METHOD THEREOF

摘要

PURPOSE: A DRAM(Dynamic Random Access Memory) and a method for manufacturing the same are provided to improve a capacitance by increasing surface area of capacitors. CONSTITUTION: A first trench is formed on a semiconductor substrate(100). A capacitor includes a storage node(25), a dielectric film(28) formed at sidewalls of the first trench and a plate electrode(29) filled into the first trench. A second trench(26) is formed at lower part of the first trench. An isolation layer(27) is formed in the second trench. A third trench is formed at an active region. A gate oxide is formed at both sidewalls of the third trench. A vertical-shaped gate electrode(35) is formed on the gate oxide. A drain region is formed at lower portions of the third trench and a source region is formed to connect to the storage node(25). A polysilicon pad(37) is formed on the gate electrode to connect to the drain region.