The present application provides a method for manufacturing a semiconductor device, and a semiconductor device. The method includes: providing a substrate; forming a first conductive material layer on the substrate; performing plasma treatment on the first conductive material layer to form a first conductive layer; successively forming a second conductive layer, a first block layer, a third conductive layer and a fourth conductive layer on the first conductive layer; forming a dielectric layer on the fourth conductive layer, and forming an ohmic contact layer at a junction of the first conductive layer and the second conductive layer; forming an initial bit line structure; performing NH3/N2 plasma treatment on the initial bit line structure to form a second block layer on a sidewall of the first conductive layer and a third block layer on a sidewall of the ohmic contact layer.