Mram structure and method of fabricating the same

Abstract

An MRAM structure includes a dielectric layer. A contact hole is disposed in the dielectric layer. A contact plug fills in the contact hole and protrudes out of the dielectric layer. The contact plug includes a lower portion and an upper portion. The lower portion fills in the contact hole. The upper portion is outside of the contact hole. The upper portion has a top side and a bottom side greater than the top side. The top side and the bottom side are parallel. The bottom side is closer to the contact hole than the top side. An MRAM is disposed on the contact hole and contacts the contact plug.

1 . An MRAM structure, comprising:
 a dielectric layer;   a contact hole disposed in the dielectric layer;   a contact plug filling in the contact hole and protruding out of the dielectric layer, wherein the contact plug comprises a lower portion and an upper portion, the lower portion fills in the contact hole, the upper portion is outside of the contact hole, the upper portion has a top side, a bottom side, a first sloping side and a second sloping side, the top side and the bottom side are parallel, the bottom side is closer to the contact hole than the top side, the bottom side is greater than the top side, two ends of the first sloping side respectively connect the top side and the bottom side, and two ends of the second sloping side respectively connect the top side and the bottom side; and   an MRAM disposed on the contact hole and directly contacting the contact plug, wherein a sidewall of the MRAM and a sidewall of the contact plug form a continuous sloping side inclining toward the dielectric layer.   
     
     
         2 . The MRAM structure of  claim 1 , wherein a first angle is disposed between the first sloping side and the top side, a second angle is disposed between the second sloping side and the top side, and the size of the first angle equals the size of the second angle. 
     
     
         3 . The MRAM structure of  claim 1 , wherein a first angle is disposed between the first sloping side and the top side, a second angle is disposed between the second sloping side and the top side, and the size of the first angle does not equal the size of the second angle. 
     
     
         4 . The MRAM structure of  claim 1 , further comprising a spacer material layer covering the MRAM and the contact plug, wherein the first sloping side and the second sloping side of the contact plug are entirely covered by the spacer material layer. 
     
     
         5 . The MRAM structure of  claim 1 , further comprising a spacer covering the MRAM, wherein part of the contact plug is not covered by the spacer. 
     
     
         6 . The MRAM structure of  claim 1 , wherein the contact plug is monolithic, and is made of a single material. 
     
     
         7 . The MRAM structure of  claim 1 , wherein the contact plug is made of tungsten. 
     
     
         8 . The MRAM structure of  claim 1 , wherein the MRAM comprises an MTJ, a top electrode and a bottom electrode. 
     
     
         9 . The MRAM structure of  claim 1 , wherein a barrier only contacts an inner sidewall of the contact hole. 
     
     
         10 . The MRAM structure of  claim 1 , wherein a barrier contacts a sidewall of the contact hole and a top surface of the dielectric layer. 
     
     
         11 . A fabricating method of an MRAM structure, comprising:
 providing a metal line and a dielectric layer covering the metal line;   forming a contact hole in the dielectric layer and exposing the metal line through the contact hole;   forming a first metal layer covering and filling the contact hole;   performing a first planarization process to planarize the first metal layer;   forming a bottom electrode, an MTJ material layer and a top electrode covering the first metal layer after the first planarization process; and   performing an ion beam etch process to pattern the top electrode, the MTJ material layer, the bottom electrode and the first metal layer to form an MRAM and a contact plug.   
     
     
         12 . The fabricating method of an MRAM structure of  claim 11 , further comprising forming a spacer material layer to cover the MRAM and the contact plug. 
     
     
         13 . The fabricating method of an MRAM structure of  claim 12 , further comprising etching the spacer material layer to form two spacers at two sides of the MRAM, wherein part of the contact plug is not covered by the spacer. 
     
     
         14 . The fabricating method of an MRAM structure of  claim 11 , wherein the contact plug fills in the contact hole and protrudes from the dielectric layer, the contact plug has a lower portion and an upper portion, the lower portion fills in the contact hole, the upper portion is outside of the contact hole, the upper portion has a top side, a bottom side, a first sloping side and a second sloping side, the top side and the bottom side are parallel, the bottom side is closer to the contact hole than the top side, the bottom side is greater than the top side, two ends of the first sloping side respectively connect the top side and the bottom side, two ends of the second sloping side respectively connect the top side and the bottom side. 
     
     
         15 . The fabricating method of an MRAM structure of  claim 14 , wherein a first angle is disposed between the first sloping side and the top side, a second angle is disposed between the second sloping side and the top side, and the size of the first angle equals the size of the second angle. 
     
     
         16 . The fabricating method of an MRAM structure of  claim 14 , wherein a first angle is disposed between the first sloping side and the top side, a second angle is disposed between the second sloping side and the top side, and the size of the first angle does not equal the size of the second angle. 
     
     
         17 . The fabricating method of an MRAM structure of  claim 11 , wherein the contact plug contacts the metal line. 
     
     
         18 . The fabricating method of an MRAM structure of  claim 11 , wherein after planarizing the first metal layer, part of the first metal layer is outside of the contact hole. 
     
     
         19 . The fabricating method of an MRAM structure of  claim 11 , further comprising:
 before forming the first metal layer, forming a barrier contacting the contact hole and a top surface of the dielectric layer, wherein after planarizing the first metal layer, a top surface of the first metal layer is aligned with the dielectric layer and the barrier on the top surface of the dielectric layer is removed.   
     
     
         20 . The fabricating method of an MRAM structure of  claim 19 , further comprising:
 after planarizing the first metal layer, forming a second metal layer covering the first metal layer; and   performing a second planarization process to planarize the second metal layer, wherein after planarizing the second metal layer, part of the second metal layer is outside of the contact hole.