Memory cell having a recessed gate and manufacturing method thereof

Abstract

A memory cell with a recessed gate includes a semiconductor substrate, a shallow trench isolation, an active region, a gate electrode, a halogen-doped dielectric layer and at least a capacitor. The shallow trench isolation is disposed in the semiconductor substrate in order to define the active region. A source region and a drain region are respectively disposed on each end of the active region along a first direction. A gate trench is formed in the semiconductor substrate between the source region and the drain region, wherein the gate trench includes a sidewall portion and a curved-bottom surface. The curved-bottom surface has a convex profile when viewed from a cross-sectional view taken along a second direction perpendicular to the first direction. The gate electrode is disposed in the gate trench and the halogen-doped dielectric layer is disposed between the gate electrode and the semiconductor substrate.