Magnetic random access memory and manufacturing method of the same

Abstract

A magnetic random access memory includes a magnetoresistive effect element which has a fixed layer, a recording layer and a non-magnetic layer provided between the fixed layer and the recording layer and in which the magnetization directions of the fixed layer and the recording layer are brought into a parallel state or an anti-parallel state in accordance with a direction of a current flowing between the fixed layer and the recording layer, a first contact which is connected to the recording layer and in which a contact area between the recording layer and the first contact is smaller than an area of the recording layer, and a cap layer which is provided between the first contact and the recording layer and which directly comes in contact with the first contact and which has a resistance higher than a resistance of the recording layer.

1 . A magnetic random access memory comprising:
 a magnetoresistive effect element which includes a fixed layer having a fixed magnetization direction, a recording layer having a reversible magnetization direction and a non-magnetic layer provided between the fixed layer and the recording layer and in which the magnetization directions of the fixed layer and the recording layer are brought into a parallel state or an anti-parallel state in accordance with a direction of a current flowing between the fixed layer and the recording layer;   a first contact which is connected to the recording layer and in which a contact area between the recording layer and the first contact is smaller than an area of the recording layer; and   a cap layer which is provided between the first contact and the recording layer and which directly comes in contact with the first contact and which has a resistance higher than a resistance of the recording layer.   
     
     
         2 . The memory according to  claim 1 , wherein a planar shape of the magnetoresistive effect element and the contact is circle, and
 a diameter of the contact is smaller than a diameter of the magnetoresistive effect element.   
     
     
         3 . The memory according to  claim 1 , wherein an area of the cap layer on the side of the first contact is larger than an area of the first contact on the side of the cap layer. 
     
     
         4 . The memory according to  claim 1 , wherein the first contact is positioned above the magnetoresistive effect element. 
     
     
         5 . The memory according to  claim 4 , further comprising:
 a first insulating film formed around the magnetoresistive effect element and the first contact and having, on the magnetoresistive effect element, a groove having a size equal to a size of the magnetoresistive effect element; and   a second insulating film formed only on a side surface of the groove and made of a material different from a material of the first insulating film,   the groove being filled up with the first contact.   
     
     
         6 . The memory according to  claim 1 , wherein the first contact is positioned under the magnetoresistive effect element. 
     
     
         7 . The memory according to  claim 6 , further comprising:
 a first insulating film formed around the first contact and having a groove; and   a second insulating film formed only on a side surface of the groove and made of a material different from a material of the first insulating film,   the groove being filled up with the first contact.   
     
     
         8 . The memory according to  claim 1 , wherein a hollow portion is formed at a center of the first contact. 
     
     
         9 . The memory according to  claim 8 , wherein an outer side surface of the first contact coincides with a side surface of the magnetoresistive effect element. 
     
     
         10 . The memory according to  claim 8 , further comprising:
 a first insulating film formed around the magnetoresistive effect element and the first contact, having, on the magnetoresistive effect element, a groove having a size equal to a size of the magnetoresistive effect element, and provided with the first contact only on a side surface of the groove; and   a second insulating film formed in the hollow portion and made of a material different from a material of the first insulating film.   
     
     
         11 . The memory according to  claim 8 , further comprising:
 a first insulating film formed around the first contact, having a groove, and provided with the first contact only on a side surface of the groove; and   a second insulating film formed in the hollow portion and made of a material different from a material of the first insulating film.   
     
     
         12 . The memory according to  claim 1 , wherein an area of the first contact is equal to an area of the magnetoresistive effect element, and
 a center of the first contact shifts from a center of the magnetoresistive effect element, the contact area between the first contact and the recording layer is reduced.   
     
     
         13 . The memory according to  claim 1 , wherein an area of the first contact is smaller than an area of the magnetoresistive effect element, and
 a center of the first contact sifts from a center of the magnetoresistive effect element.   
     
     
         14 . The memory according to  claim 1 , wherein the first contact has linear first and second portions disposed away from each other. 
     
     
         15 . The memory according to  claim 1 , further comprising:
 a second contact connected to the fixed layer, a contact area between the fixed layer and the second contact being smaller than an area of the fixed layer.   
     
     
         16 . The memory according to  claim 1 , wherein during a write operation, magnetization of the recording layer reverses from a portion where the first contact comes in contact with the recording layer, and the whole magnetization of the recording layer reverses owing to propagation of the magnetization reverse. 
     
     
         17 . A magnetic random access memory manufacturing method comprising:
 forming a magnetoresistive effect element having a fixed layer having a fixed magnetization direction, a recording layer having a reversible magnetization direction and a non-magnetic layer provided between the fixed layer and the recording layer;   forming a first insulating film on the magnetoresistive effect element;   covering the first insulating film with a second insulating film and removing the second insulating film until the first insulating film is exposed;   removing the first insulating film to form a groove;   forming a third insulating film only on a side surface of the groove; and   forming a contact in the groove, a contact area between the contact and the magnetoresistive effect element being smaller than an area of the magnetoresistive effect element.   
     
     
         18 . The method according to  claim 17 , further comprising:
 forming, between the contact and the magnetoresistive effect element, a cap layer having a resistance higher than a resistance of the recording layer.   
     
     
         19 . A magnetic random access memory manufacturing method comprising:
 forming a magnetoresistive effect element having a fixed layer having a fixed magnetization direction, a recording layer having a reversible magnetization direction and a non-magnetic layer provided between the fixed layer and the recording layer;   forming a first insulating film on the magnetoresistive effect element;   covering the first insulating film with a second insulating film and removing the second insulating film until the first insulating film is exposed;   removing the first insulating film to form a groove;   forming a contact having a hollow portion at the center thereof only on a side surface of the groove, a contact area between the contact and the magnetoresistive effect element being smaller than an area of the magnetoresistive effect element; and   forming a third insulating film at the hollow portion.   
     
     
         20 . The method according to  claim 19 , further comprising:
 forming, between the contact and the magnetoresistive effect element, a cap layer having a resistance higher than a resistance of the recording layer.