A semiconductor memory cell is formed in a substrate and includes a trench capacitor and a selection transistor. The trench capacitor includes a capacitor dielectric and a conductive trench filling. Disposed on the conductive trench filling is a diffusion barrier on which an epitaxial layer is formed. The selection transistor is disposed as a planar transistor above the trench capacitor. A drain doping region of the selection transistor is disposed in the epitaxial layer.