Patent ID: 7052949

Claim:
A method for forming a bit line, comprising: providing a semiconductor substrate having a peripheral circuit layer, wherein a MOS having a gate and an S/D area is formed on the semiconductor substrate; forming a first dielectric layer with a first contact opening on the semiconductor substrate, wherein the first contact opening exposes the S/D area; forming a first contact plug in the first contact opening; forming a first barrier layer on the surface of the first dielectric layer and the first contact plug; forming a second dielectric layer on the first barrier layer; patterning the second dielectric layer to form a first bit line trench and a second bit line trench on the first barrier layer using the first barrier layer as an etching stop, the first bit line trench corresponding to the first contact opening and the second bit line trench does not correspond to the first contact opening; forming a patterned photoresist layer with a first corresponding to the first bit line trench, a second opening corresponding to the second bit line trench and a third opening corresponding to the second dielectric layer, the position of the third opening corresponding to the peripheral circuit layer; sequentially etching the second dielectric layer, the first barrier layer, and the first dielectric layer to form a second contact opening, wherein the second contact opening exposes the surface of the peripheral circuit layer, and the barrier layer in the first bit line trench and second bit line trench is removed; conformally forming a second barrier layer on the surface of the first bit line trench, the second bit line trench and the second contact opening; and filling a metal layer in the first bit line trench and the second bit line trench as bit lines, the metal layer filling the second contact opening as a second contact plug.