Method of forming metal contact in semiconductor device

Abstract

A method of forming metal contacts in a semiconductor device having an active metal contact region and a bit line contact region is provided. In the method, a contact pad is formed in the active metal contact region and the bit line contact region using a conductive plug. An etch stopper is formed on the upper sides of the conductive plug. A portion of a lower interlayer dielectric layer is etched so that the etch stopper protrudes above the lower interlayer dielectric layer. A bit line stack is formed in the bit line contact region. An etch stopper is formed in the active metal contact region. An upper interlayer dielectric layer is etched to expose the surfaces of the etch stopper and bit line capping layer pattern of the bit line stack. The exposed surfaces of the etch stopper and bit line capping layer pattern are etched to form a contact hole which exposes the conductive plug and a bit line conductive layer of the bit line stack. The contact hole is filled with a conductive layer.