Method for forming bit-line contact plug and transistor structure

Abstract

A method for forming a bit-line contact plug includes providing a substrate including a transistor which includes a gate structure and a source/drain at both sides of the gate structure; forming a conductive layer, a bit-line contact material layer and a hard mask layer; performing an etching process using the conductive layer as an etching stop layer to etch the bit-line contact material layer and the hard mask layer and forming the bit-line contact plug on the source/drain. A transistor structure includes a gate structure and a source/drain at both sides of the gate structure, a conductive layer covering part of the gate structure and connected to the source/drain, and a bit-line contact plug disposed on the conductive layer and directly connected to the conductive layer.