A fabricating method of a stop layer includes providing a substrate. The substrate is divided into a memory region and a peripheral circuit region. Two conductive lines are disposed within the peripheral circuit region. Then, an atomic layer deposition is performed to form a silicon nitride layer to cover the conductive lines. Later, after forming the silicon nitride layer, a silicon carbon nitride layer is formed to cover the silicon nitride layer. The silicon carbon nitride layer serves as a stop layer.