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 and drain region...http://www.google.de/patents/US6713345?utm_source=gb-gplus-sharePatent US6713345 - Semiconductor memory device having a trench and a gate electrode vertically formed on a wall of the trench
