The present application provides a memory device having a bit line (BL) with a stepped profile. The memory device includes a semiconductor substrate including a first surface; and a bit line disposed on the first surface of the semiconductor substrate, wherein the bit line includes a first dielectric layer, a conductive layer disposed over the first dielectric layer, a second dielectric layer disposed over the conductive layer, and a spacer surrounding the first dielectric layer, the conductive layer and the second dielectric layer, wherein the second dielectric layer includes a first portion surrounded by the spacer, and a second portion disposed over the first portion and exposed through the spacer, wherein a first width of the first portion is substantially greater than a second width of the second portion.