Patent ID: 8450772

Claim:
A method for manufacturing a phase change Random Access Memory (RAM) device, the method comprising the steps of: providing a semiconductor substrate, the semiconductor substrate having an isolation layer for isolating an active area, a gate formed on the active area, and source and drain areas formed under a substrate surface on both sides of the gate; sequentially forming a first oxide layer, a nitride layer and a second oxide layer on an entire surface of the semiconductor substrate; etching the second oxide layer using the nitride layer as an etch stopping layer, thereby forming a trench shaped like a bar on the second oxide layer above the source area, without etching the second oxide layer above the drain area to prevent a metal pad from being formed above the drain; etching the first oxide layer, the nitride layer and the second oxide layer, thereby forming a first contact hole for exposing the drain area and a second contact hole for exposing the source area in a lower surface of the trench; filling in a conductive layer within the first contact hole, the second contact hole, and the trench, thereby forming a first plug making contact with the drain area in the first contact hole, forming a second plug making contact with the source area in the second contact hole, and forming a conductive line in the trench, wherein the conductive line is formed as one body with the second plug; forming a third oxide layer on the second oxide layer including the first plug and the conductive line; forming a lower electrode shaped like a plug, the lower electrode directly contact with the first plug in the third oxide layer above the drain area; and sequentially forming a phase change layer and an upper electrode on the lower electrode and the third oxide layer in a pattern form, the third oxide layer being adjacent to the lower electrode, wherein the phase change layer is formed so as to directly make contact with the lower electrode.