Magnetic random access memory and a method of fabricating the same

Abstract

An aspect of the present embodiment, there is provided magnetic random access memory device including a semiconductor substrate, a selection transistor on the semiconductor substrate, the selection transistor including a diffusion layer, a contact plug on diffusion layer, an amorphous film on the contact plug, a lower electrode provided on the amorphous film, a first magnetic layer, a nonmagnetic layer, a second magnetic layer, an upper electrode stacked in an order and a sidewall contact film on the contact plug, the sidewall contact film being in contact with a sidewall of the upper electrode.

1 . A magnetic random access memory, comprising:
 a semiconductor substrate;   a selection transistor provided on the semiconductor substrate, the selection transistor including a diffusion layer on a surface area of the semiconductor substrate;   a contact plug provided on the diffusion layer;   an amorphous film provided on the contact plug;   a lower electrode provided on the amorphous film;   a first magnetic layer provided on the lower electrode;   a nonmagnetic layer provided on the first magnetic layer;   a second magnetic layer provided on the nonmagnetic layer;   an upper electrode provided on the second magnetic layer; and   a sidewall contact film provided on the contact plug, the sidewall contact film being in contact with a sidewall of the lower electrode.   
     
     
         2 . The magnetic random access memory of  claim 1 , further comprising:
 a sidewall mask being in contact with sidewalls of the upper electrode, the second magnetic layer and the nonmagnetic layer, a height of a bottom surface of the sidewall mask being lower than a height of a bottom surface of the second magnetic layer and being higher than a height of a bottom surface of the nonmagnetic layer.   
     
     
         3 . The magnetic random access memory of  claim 1 , wherein
 a sidewall mask is in contact with the sidewalls of the upper electrode, the second magnetic layer and the nonmagnetic layer, and a sidewall of the first magnetic layer, a height of a bottom surface of the sidewall mask being lower than the height of the bottom surface of the nonmagnetic layer and being higher than a height of a bottom surface of the first magnetic layer.   
     
     
         4 . The magnetic random access memory of  claim 1 , wherein
 a sidewall mask being in contact with the sidewalls of the upper electrode, the second magnetic layer, the nonmagnetic layer, the first magnetic layer, and a portion of the sidewall of the lower electrode, a height of a bottom surface of the sidewall mask is lower than the height of the bottom surface of the first magnetic layer and is higher than a height of a bottom surface of the lower electrode.   
     
     
         5 . The magnetic random access memory of  claim 1 , wherein
 the sidewall contact film is composed of a titanium nitride film.   
     
     
         6 . The magnetic random access memory of  claim 1 , wherein
 a seam is provided in the contact plug and the amorphous film is provided in at least a portion of the seam.   
     
     
         7 . The magnetic random access memory of  claim 1 , wherein
 a surface asperity of the amorphous film is 0.2 nm or less.   
     
     
         8 . The magnetic random access memory of  claim 1 , further comprising;
 a metal film provided between the contact plug and the amorphous film, the sidewall contact film including metal composing the metal film.   
     
     
         9 . The magnetic random access memory of  claim 8 , wherein
 the sidewall contact film is constituted with a first sidewall contact film and a second sidewall contact film, the first sidewall contact film is in contact with the sidewall of lower electrode and the second sidewall contact film is in contact with a sidewall of the first sidewall contact film.   
     
     
         10 . The magnetic random access memory of  claim 9 , wherein
 the second sidewall contact film includes metal composing the contact plug.   
     
     
         11 . The magnetic random access memory of  claim 8 , wherein
 the first sidewall contact film is composed of a titanium nitride film.   
     
     
         12 . The magnetic random access memory of  claim 8 , wherein
 the seam is provided in the contact plug and the metal film is provided in at least a portion of the seam.   
     
     
         13 . A method of fabricating a magnetic random access memory, comprising;
 providing a selection transistor on a semiconductor substrate, the selection transistor including a diffusion layer on a surface of the semiconductor substrate;   providing a contact plug on the diffusion layer;   providing an amorphous film on the contact plug;   polishing a surface of the amorphous film;   providing a lower electrode on the amorphous film;   providing a first magnetic layer on the lower electrode;   providing a nonmagnetic layer on the first magnetic layer;   providing a second magnetic layer on the nonmagnetic layer;   providing an upper electrode on the second magnetic layer;   etching the upper electrode and the second magnetic layer as a first step;   providing a sidewall mask to cover sidewalls of the upper electrode and the second magnetic layer;   etching the nonmagnetic layer, the first magnetic layer, the lower electrode and the amorphous film until exposing a surface of the contact plug as a second step so as to provide a magneto resistive element including the lower electrode, the first magnetic layer, the nonmagnetic layer, the second magnetic layer and the upper electrode; and   providing a sidewall contact on sidewalls of the magneto resistive element and the amorphous film so as to be in contact with the contact plug and the lower electrode.   
     
     
         14 . A method of  claim 13 , wherein
 etching as the first step further includes etching the nonmagnetic layer, etching as the second step includes other than etching the nonmagnetic layer, and the sidewall mask further covers a sidewall of the nonmagnetic layer.   
     
     
         15 . A method of  claim 14 , wherein
 etching as the first step further includes etching the nonmagnetic layer and the first magnetic layer, etching as the second step includes other than etching the nonmagnetic layer and the first magnetic layer, and the sidewall mask further covers the sidewall of the nonmagnetic layer and a sidewall of the first magnetic layer.   
     
     
         16 . A method of  claim 14 , wherein
 etching as the first step further includes etching the nonmagnetic layer, the first magnetic layer and a portion of the lower electrode, etching as the second step includes other than etching the nonmagnetic layer, the first magnetic layer and the portion of the lower electrode, and the sidewall mask covers the sidewalls of the nonmagnetic layer and the first magnetic layer, and a sidewall of the lower electrode.   
     
     
         17 . A method of  claim 13 , wherein
 providing the sidewall contact is constituted with providing a sidewall material which covers the magneto resistive element, and etching the sidewall material on the magneto resistive element.   
     
     
         18 . A method of  claim 13 , wherein
 providing the sidewall contact is constituted with etching the first magnetic layer, the lower electrode and the amorphous film until exposing the surface of the contact plug, and etching the contact plug so as to provide a material of the contact plug to the sidewall of the lower electrode.   
     
     
         19 . A method of  claim 18 , wherein
 etching the first magnetic layer, the lower electrode and the amorphous film, and etching the contact plug so as to provide a material of the contact plug are seriously performed.   
     
     
         20 . A method of fabricating a magnetic random access memory, comprising;
 providing a selection transistor on a semiconductor substrate, the selection transistor including a diffusion layer on a surface of the semiconductor substrate;   providing a contact plug on the diffusion layer;   providing a metal film on the contact plug;   providing an amorphous film on the metal film;   polishing a surface of the amorphous film;   providing a lower electrode on the amorphous film;   providing a first magnetic layer on the lower electrode;   providing a nonmagnetic layer on the first magnetic layer;   providing a second magnetic layer on the nonmagnetic layer;   providing an upper electrode on the second magnetic layer;   etching the upper electrode, the second magnetic layer and the nonmagnetic layer;   providing a sidewall mask to cover sidewalls of the upper electrode, the second magnetic layer and the nonmagnetic layer;   etching the first magnetic layer, the lower electrode and the amorphous film until exposing a surface of the contact plug;   etching the metal film so as to provide a first sidewall contact containing same metal as the metal film on a sidewall of the lower electrode on the metal film;   etching the contact plug to provide a second sidewall contact being in contact with the first sidewall contact on the contact plug.