Semiconductor memory device having a trench and a gate electrode vertically formed on a wall of the trench

摘要

A semiconductor memory device includes a trench type SRAM(Static Random Access Memory) cell having a higher integration than a stack type SRAM. The SRAM cell memory device is provided with a trench formed in a semiconductor substrate and having four side walls therein, wherein a source region and a drain region of each of first and second drive transistors are formed in two of the four side walls. A pair of active layers respectively having a source region and a drain region of a first load transistor and a second load transistor, respectively, are formed on the substrate adjacent to the side walls. A gate electrode common to the first drive transistor and the first load transistor is formed on a gate oxide film. A gate electrode of an access transistor is vertically formed in a direction vertical to the semiconductor substrate instead of being formed on the substrate for thereby decreasing an area to be occupied by the transistor.