A method of manufacturing an electrical interconnection of a semiconductor device produces an erosion protecting plug in a contact hole to protect a selected portion of an interlayer dielectric layer when the interlayer dielectric layer is being etched to form a recess for a conductive line. The contact hole is formed in the interlayer dielectric layer. The contact hole is filled with an organic material to form the erosion protecting plug. The organic material is a photoresist material or an organic polymer. A photoresist pattern is formed for exposing the erosion protecting plug and a portion of the interlayer dielectric layer adjacent to the erosion protecting plug. A recess which extends down to the contact hole is formed by etching the portion of the interlayer dielectric layer which is exposed by the photoresist pattern. The erosion protecting plug and the photoresist pattern are then removed. A conductive line filling the recess and a contact filling the contact hole are then formed.