Semiconductor devices having a contact window and fabrication methods
thereof are provided. A lower dielectric layer, conductive patterns and an upper
dielectric layer are formed sequentially on a semiconductor substrate. The lower
dielectric layer has a higher isotropic etch rate than that of the upper dielectric
layer. The upper dielectric layer and the lower dielectric layer are patterned
by anisotropic etching to form a trench without exposing the semiconductor substrate.
The resultant structure is subject to isotropic etching to expose the substrate
and to form a contact window having a wider width in a lower region than in an
upper region without damaging the semiconductor substrate.
