Method for manufacturing phase change memory device which can stably form an interface between a lower electrode and a phase change layer
View Patent ↗A phase change memory device is manufactured by forming a sacrificial layer and a hard mask layer on a lower electrode; performing a first etching these layers and forming on the lower electrode a first stack pattern having a first width less than a width of the lower electrode; performing a second etching the first stack pattern and forming a second stack pattern having a second width less than the first width; forming an insulation to cover the second stack pattern; CMPing the insulation layer to expose the sacrificial layer; removing the sacrificial layer to define a contact hole; forming a lower electrode contact in the contact hole; and forming a phase change layer and an upper electrode on the insulation layer including the lower electrode contact. By manufacturing the phase change memory device in this manner, the size of the contact hole can be decreased and uniformly defined.
1. A method for manufacturing a phase change memory device, comprising the steps of:
forming a first insulation layer on a semiconductor substrate, the first insulation layer having an opening;
forming a lower electrode in the opening;
forming a sacrificial layer and a hard mask layer on the lower electrode;
performing a first etching using a first etching process on the hard mask layer and the sacrificial layer to form a first stack pattern on the lower electrode, the first stack pattern having a first width less than a width of the lower electrode, wherein the first etching process is performed using a photoresist pattern;
performing a second etching using a second etching process on the sacrificial layer and the hard mask layer of the first stack pattern to form a second stack pattern of the sacrificial layer and the hard mask layer which has a second width less than the first width, wherein the second etching process is a different etching process than the first etching process, and the second etching process is a reactive ion etching process;
forming a second insulation layer on the first insulation layer to cover the second stack pattern;
chemical mechanical polishing the second insulation layer to expose the sacrificial layer of the second stack pattern;
removing the exposed sacrificial layer of the second stack pattern to define a contact hole in the second insulation layer;
forming a lower electrode contact in the contact hole; and
forming a phase change layer and an upper electrode on the second insulation layer and the lower electrode contact.
2. The method according to claim 1 , wherein the sacrificial layer is made of any one of a polysilicon layer, a nitride layer, and an oxide layer.
3. The method according to claim 1 , wherein the hard mask layer is made of any one of a nitride layer, an oxide layer, and a polysilicon layer.
4. The method according to claim 1 , wherein the lower electrode contact is made of any one of a tungsten nitride layer, a titanium nitride layer, a titanium tungsten layer, and a titanium aluminum nitride layer.
5. The method according to claim 4 , wherein the lower electrode contact is formed through atomic layer deposition or chemical vapor deposition.
6. The method according to claim 1 , wherein the upper electrode is made of any one of a tungsten nitride layer, a titanium nitride layer, a titanium tungsten layer, and a titanium aluminum nitride layer.