CONTACT STRUCTURE WITH A LOWER INTERCONNECTION HAVING T-SHAPED PORTION IN CROSS SECTION AND METHOD FOR FORMING THE SAME

摘要

A contact structure in a semiconductor device including a dynamic random access memory (DRAM) and a method of forming the same are provided. The contact structure, which is formed in a peripheral circuit area or a logic circuit area of a semiconductor device including a DRAM having a cell array area with a plurality of DRAM cells and the peripheral or logic circuit area, includes a lower interconnection formed of the same material as a capacitor upper electrode of each of the plurality of DRAM cells; an interlayer dielectric layer formed on the lower interconnection and having a contact hole exposing a predetermined portion of the lower interconnection; and an upper interconnection formed on the interlayer dielectric layer and electrically connected to the lower interconnection through the contact hole. The lower portion of the lower interconnection has a larger area than the bottom of the contact hole and extends downward so that the lower interconnection has a T-shape in a cross-section view. By forming the lower interconnection under a shallow contact hole to have a T-shape extending downward when forming contact holes having a large difference in depth, the lower interconnection can be prevented from being pierced when the contact holes are formed. Consequently, stable and uniform contact resistance can be obtained.