Solid memory

Abstract

In one embodiment of the present invention, recording and erasing of data in PRAM have hitherto been performed based on a change in physical characteristics caused by primary phase-transformation of a crystalline state and an amorphous state of a chalcogen compound including Te which serves as a recording material. Since, however, a recording thin film is formed of a polycrystal but not a single crystal, a variation in resistance values occurs and a change in volume caused upon phase-transition has placed a limit on the number of times of readout of record. In one embodiment, the above problem is solved by preparing a solid memory having a superlattice structure of thin films including Ge and thin films including Sb. The solid memory can realize the number of times of repeated recording and erasing of 10 15 .

1 . A Solid Memory consisting mainly of tellurium (Te),
 electric characteristics thereof changing due to phase-transformation of a substance constituting the solid memory,   the substance serving as a material for recording and reproducing data, the material including a laminated structure of artificial superlattice structures made of thin films each including a parent phase which causes the phase-transformation.   
     
     
         2 . The Solid Memory as set forth in  claim 1 , wherein:
 the laminated structure is made of alloy thin films including germanium (Ge) atoms and alloy thin films including stibium (Sb) atoms.   
     
     
         3 . The solid memory as set forth in  claim 1 , wherein:
 a thickness of each of the alloy thin films including germanium (Ge) atoms and the alloy thin films including stibium (Sb) atoms ranges from 0.3 to 2 nm.   
     
     
         4 . The solid memory as set forth in  claim 2 , wherein:
 data is recorded by causing the germanium (Ge) atoms to be anisotropically diffused from the alloy thin films including the germanium (Ge) atoms to interfaces between the alloy thin films including germanium (Ge) atoms and the alloy thin films including stibium (Sb) atoms.   
     
     
         5 . The solid memory as set forth in  claim 2 , wherein:
 data is erased by causing germanium (Ge) atoms stored in interfaces between the alloy thin films including germanium (Ge) atoms and the alloy thin films including stibium (Sb) atoms to be anisotropically diffused to the alloy thin films including germanium (Ge) atoms.   
     
     
         6 . The solid memory as set forth in  claim 2 , wherein:
 a thickness of each of the alloy thin films including germanium (Ge) atoms and the alloy thin films including stibium (Sb) atoms ranges from 0.3 to 2 nm.