Method of making a trench capacitor dram cell

Abstract

Disclosed is a semiconductor memory device (DRAM) which includes a plurality of island regions, at least one cell transistor disposed on each island region and cylindrical capacitor surrounding said each island region. By so composing, the capacity of the cell capacitor incorporated into a small space can be increased. Also disclosed is method of fabricating a semiconductor memory device which includes a step of forming a groove having a necessary depth in a semiconductor substrate, a step of depositing a membrane excelling in coverage on it, a step of etching by an etching method having a strong anisotropy in the vertical direction while leaving said deposit membrane on sidewall, and a step of etching deeper the exposed portion of the semiconductor surface in the groove and forming capacity element and isolation region by using this deep trench.