Manufacture method of multilevel phase-change memory and operating method thereof

Abstract

A manufacture method of a multilevel phase-change memory and operating method thereof are provided. The method includes providing a substrate, forming a bottom electrode on the substrate, forming a first heating layer on top of the bottom electrode, forming a second heating layer on top of the first heating layer, forming a first phase-change layer and a second phase-change layer respectively on the first heating layer and the second heating layer, and forming a first top electrode and a second electrode respectively on the first phase-change layer and the second phase-change layer. Hence, the bottom electrode, the first heating layer and the first phase-change layer constitute an electrical current path, the bottom electrode, the first heating layer, the second heating layer and the second phase-change layer constitute another electrical current path, and the resistances of the two electrical current path are different, thereby increasing the memory density.

1 . A method of manufacturing a multilevel phase-change memory, comprising:
 providing a substrate;   forming a bottom electrode on the substrate;   forming a first heating layer on top of the bottom electrode;   forming a second heating layer on top of the first heating layer;   forming a first phase-change layer and a second phase-change layer respectively on the first heating layer and the second heating layer; and   forming a first top electrode and a second electrode respectively on the first phase-change layer and the second phase-change layer.   
     
     
         2 . The method of  claim 1 , wherein the step of forming the second heating layer comprises:
 depositing an insulation layer on top of the first heating layer;   etching a guiding hole on the insulation layer at a position where the bottom electrode is located;   depositing a second heating layer in the guiding hole and on top of the insulation layer; and   etching the second heating layer to remove the second heating layer on the insulation layer.   
     
     
         3 . The method of  claim 1 , wherein the step of forming the second heating layer comprises:
 depositing the second beating layer on the first heating layer corresponding to the bottom electrode;   depositing an insulation layer on top of the first heating layer and the second heating layer; and   etching the insulation layer above the second heating layer.   
     
     
         4 . The method of  claim 1 , wherein the step of forming the first phase-change layer and the second phase-change layer comprises:
 forming a phase-change layer on the second heating layer, and   etching the phase-change layer to form the first phase-change layer and the second phase-change layer.   
     
     
         5 . The method of  claim 1 , wherein the step of forming the first top electrode and the second top electrode comprises:
 depositing an insulation layer on top of the first phase-change layer and the second phase-change layer;   forming guiding holes by etching the insulation layer at positions where the first phase-change layer and the second phase-change layer are located; and   forming the first top electrode and the second top electrode in the guiding holes.   
     
     
         6 . The method of  claim 1 , wherein the phase-change ratios of the first phase-change layer and the second phase-change layer are different, and the resistance of the first heating layer and the second heating layer are different. 
     
     
         7 . The method of  claim 6 , wherein the material of the first phase-change layer and the second phase-change layer is Ge 2 Sb 2 Te 5 , the material of the first heating layer is TiN and the material of the second heating layer is SiC. 
     
     
         8 . The method of  claim 1 , wherein the bottom electrode, the first heating layer and the first phase-change layer constitute an electrical current path, the bottom electrode, the first heating layer, the second heating layer and the second phase-change layer constitute another electrical current path, and the resistances of the two electrical current path are different. 
     
     
         9 . A method of operating a multilevel phase-change memory, wherein the phase-change memory comprises a first phase-change layer, a second phase-change layer, a first heating layer formed on a first surface of the first phase-change layer, a second heating layer formed between the first heating layer and the second phase-change layer, a first top electrode formed on a second surface of the first phase-change layer, a second top electrode formed on the second surface of the second phase-change layer opposite to the second heating layer, and a bottom electrode formed on the second surface of the first heating layer opposite of the second heating layer, the method comprising:
 grounding the first top electrode and the second top electrode; and   applying a pulse current to the bottom electrode to make the first phase-change layer and the second phase-change layer to change states thereof according to the pulse current.   
     
     
         10 . The method of  claim 9 , further comprising, before applying the pulse current, converting the first phase-change layer and the second phase-change layer into a non-crystal state. 
     
     
         11 . A method of operating a multilevel phase-change memory, wherein the phase-change memory comprises a first phase-change layer, a second phase-change layer, a first heating layer formed on a first surface of the first phase-change layer, a second heating layer formed between the first heating layer and the second phase-change layer, a first top electrode formed on a second surface of the first phase-change layer, a second top electrode formed on the second surface of the second phase-change layer opposite to the second heating layer, and a bottom electrode formed on the second surface of the first heating layer opposite of the second heating layer, the method comprising:
 grounding the first top electrode and the second top electrode; and   applying a pulse current to one of the first top electrode and the second top electrode.