Phase change memory and manufacturing method thereof

Abstract

Even if sizes of storage cells are reduced in a phase change memory, properties of the respective storage cells can be set to be approximately equal to one another and a current amount required for phase change can be reduced sufficiently. The phase change memory includes at least a storage cell. The storage cell includes a first electrode, an electrically conductive portion provided on the first electrode and having at least two electrically conductive bodies with approximately the same shape provided on the first electrode, the electrically conductive bodies being spaced by a high resistance film with a high resistance, a recording layer provided on the electrically conductive portion and having phase change material which can change between a first phase state with a first specific resistance and a second phase state with a second specific resistance different from the first specific resistance, and a second electrode provided on the recording layer.

1 . A phase change memory comprising at least a storage cell, the storage cell comprising: 
 a first electrode;    an electrically conductive portion having at least two electrically conductive bodies with approximately the same shape provided on the first electrode, the at least two electrically conductive bodies being spaced from one another by a high resistance film with a resistance higher than those of the at least two electrically conductive bodies;    a recording layer being provided on the electrically conductive portion, and having phase change material which can change between a first phase state having a first specific resistance and a second phase state having a second specific resistance different from the first specific resistance; and    a second electrode being provided on the recording layer.    
   
   
       2 . The phase change memory according to  claim 1 , further comprising an ordered structure where the at least two electrically conductive bodies have been arranged approximately regularly.  
   
   
       3 . The phase change memory according to  claim 1 , wherein a ratio x/d of an average distance x of distances between the centers of the electrically conductive bodies adjacent to each other to an average value d of the shortest distances between the electrically conductive bodies adjacent to each other is 1.5 or more.  
   
   
       4 . The phase change memory according to  claim 1 , wherein the high resistance film spacing the at least two electrically conductive bodies from one another is made from material for promoting crystallization for the phase change material.  
   
   
       5 . The phase change memory according to  claim 4 , wherein the high resistance film is made from nitride of Ge or Hf, oxide of Cr, Ce, Hf, Zr, or Ta, or carbide of Si, or mixture thereof.  
   
   
       6 . The phase change memory according to  claim 1 , further comprising a first wiring connected to the first electrode in the storage cell and a second wiring directly connected to the second electrode in the storage cell, wherein a transistor or a diode is provided between the first wiring and the first electrode in the storage cell or between the second wiring and the second electrode in the storage cell.  
   
   
       7 . The phase change memory according to  claim 2 , wherein a ratio x/d of an average distance x of distances between the centers of the electrically conductive bodies adjacent to each other to an average value d of the shortest distances between the electrically conductive bodies adjacent to each other is 1.5 or more.  
   
   
       8 . The phase change memory according to  claim 2 , wherein the high resistance film spacing the at least two electrically conductive bodies from one another is made from material for promoting crystallization for the phase change material.  
   
   
       9 . The phase change memory according to  claim 8 , wherein the high resistance film is made from nitride of Ge or Hf, oxide of Cr, Ce, Hf, Zr, or Ta, or carbide of Si, or mixture thereof.  
   
   
       10 . The phase change memory according to  claim 2 , further comprising a first wiring connected to the first electrode in the storage cell and a second wiring directly connected to the second electrode in the storage cell, wherein a transistor or a diode is provided between the first wiring and the first electrode in the storage cell or between the second wiring and the second electrode in the storage cell.  
   
   
       11 . The phase change memory according to  claim 3 , wherein the high resistance film spacing the at least two electrically conductive bodies from one another is made from material for promoting crystallization for the phase change material.  
   
   
       12 . The phase change memory according to  claim 11 , wherein the high resistance film is made from nitride of Ge or Hf, oxide of Cr, Ce, Hf, Zr, or Ta, or carbide of Si, or mixture thereof.  
   
   
       13 . The phase change memory according to  claim 3 , further comprising a first wiring connected to the first electrode in the storage cell and a second wiring directly connected to the second electrode in the storage cell, wherein a transistor or a diode is provided between the first wiring and the first electrode in the storage cell or between the second wiring and the second electrode in the storage cell.  
   
   
       14 . A manufacturing method of a phase change memory comprising: 
 forming a first electrode;    forming an electrically conductive layer on the first electrode;    forming a block copolymer layer having an ordered structure where first polymer phases and second polymer phases are approximately regularly arranged on the electrically conductive layer;    selectively removing the first polymer phases to form a plurality of recesses on a surface of the block polymer layer;    forming a plurality of electrically conductive bodies corresponding to the ordered structure of the block copolymer by utilizing the recesses as masks to perform etching process on the electrically conductive layer;    forming a high resistance film with a resistance higher than that of the electrically conductive bodies among the plurality of electrically conductive bodies;    forming a phase change material layer which can change its phase between a first phase state having a first specific resistance and a second phase state having a second specific resistance different from the first specific resistance on the plurality of electrically conductive bodies and the high resistance film; and    forming a second electrode on the phase change material layer.    
   
   
       15 . The manufacturing method of a phase change memory according to  claim 14 , wherein the electrically conductive layer has a feature pattern on a surface thereof before the block copolymer layer is formed, and 
 the ordered structure of the block copolymer layer formed on the electrically conductive layer is oriented so as to correspond to the feature pattern.    
   
   
       16 . The manufacturing method of a phase change memory according to  claim 14 , further comprising a step of forming a mask layer on the recesses, wherein a size of the pattern corresponding to the ordered structure is controlled by adjusting a filling amount of material for the mask layer.  
   
   
       17 . A manufacturing method of a phase change memory comprising: 
 forming a first electrode;    forming an electrically conductive layer on the first electrode;    forming a transfer layer on the electrically conductive layer;    forming, on the transfer layer, a block copolymer layer having an ordered structure where first polymer phases and second polymer phases are approximately regularly arranged;    selectively removing the first polymer phases to form a plurality of recesses on a surface of the block polymer layer;    forming a pattern corresponding to the ordered structure of the block copolymer layer by utilizing the plurality of recesses as masks to etch the block copolymer layer and the transfer layer;    forming a plurality of electrically conductive bodies corresponding to the ordered structure of the block copolymer layer by utilizing the transfer layer as a mask to perform etching process;    forming a high resistance film with a resistance higher than the electrically conductive body among the plurality of electrically conductive bodies;    forming a phase change material layer which can phase-change between a first phase state having a first specific resistance and a second phase state having a second specific resistance different from the first specific resistance on the plurality of electrically conductive bodies and the high resistance film; and    forming a second electrode.    
   
   
       18 . The manufacturing method of a phase change memory according to  claim 17 , wherein the transfer layer has a feature pattern on a surface thereof before the block copolymer layer is formed, and 
 the ordered structure of the block copolymer layer formed on the transfer layer is oriented so as to correspond to the feature pattern.    
   
   
       19 . The manufacturing method of a phase change memory according to  claim 17 , further comprising a step of forming a mask layer on the recesses, wherein a size of the pattern corresponding to the ordered structure is controlled by adjusting a filling amount of material for the mask layer.