Semiconductor device having a contact window including a lower with a wider to provide a lower contact resistance

Abstract

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.