Ferromagnetic liner for conductive lines of magnetic memory cells

Abstract

A method of forming a ferromagnetic liner on conductive lines of magnetic memory devices and a structure thereof. The ferromagnetic liner increases the flux concentration of current run through the conductive lines, reducing the amount of write current needed to switch magnetic memory cells. The conductive lines are formed in a plate-up method, and the ferromagnetic liner is selectively formed on the plated conductive lines. The ferromagnetic liner may also be formed over conductive lines and a top portion of vias in a peripheral region of the workpiece.

1 . A method of fabricating a conductive line of a magnetic memory device, the method comprising: 
 providing a workpiece having at least one magnetic memory cell formed thereon;    encapsulating the at least one magnetic memory cell within a first insulating layer, the at least one magnetic memory cell comprising an electrical contact disposed thereon;    exposing the electrical contact of the magnetic memory cell at a top surface of the first insulating layer;    forming a plating seed layer upon the first insulating layer and the electrical contact over the at least one magnetic memory cell;    forming a mask over the plating seed layer, leaving an unmasked region above the at least one magnetic memory cell;    plating a first conductive line in the unmasked regions, including over the at least one magnetic memory cell;    removing the mask, exposing portions of the plating seed layer;    removing the portions of the plating seed layer exposed by removing the mask; and    forming a ferromagnetic liner over at least the first conductive line.    
     
     
         2 . The method according to  claim 1 , wherein forming the ferromagnetic liner over the first conductive line comprises forming the ferromagnetic liner using an electroless plating process, an electroless plating process using Pd activation, a potentiostatically triggered electroless process, a potentiostatic electroplating process, a galvanostatic plating process, an electroplating process, a selective chemical vapor deposition (CVD) process, or combinations thereof.  
     
     
         3 . The method according to  claim 1 , wherein forming the plating seed layer comprises forming about  50  nm or less of Ru, Cu, or Ag, or combinations thereof.  
     
     
         4 . The method according to  claim 3 , wherein removing the plating seed layer comprises a reactive ion etch (RIE) or ion milling.  
     
     
         5 . The method according to  claim 4 , wherein plating the first conductive line comprises forming a first conductive line comprising a top surface and sidewalls, wherein corners are disposed where the top surface meets the sidewalls, wherein removing the plating seed layer comprises removing a portion of the corners of the first conductive line, forming rounded corners on the first conductive line.  
     
     
         6 . The method according to  claim 1 , further comprising forming a barrier layer over the at least one magnetic memory cell, before forming the plating seed layer, and further comprising removing the barrier layer from over the first insulating layer, before forming the ferromagnetic liner.  
     
     
         7 . The method according to  claim 6 , wherein forming the barrier layer comprises forming about 20 nm or less of Ta, TaN, WN, TiN, Ru, or combinations thereof.  
     
     
         8 . The method according to  claim 1 , wherein forming the ferromagnetic liner comprises forming about 50 nm or less of Ni, Fe, Co, alloys thereof, P, B, or combinations thereof.  
     
     
         9 . The method according to  claim 8 , wherein forming the ferromagnetic liner comprises forming CoWP, CoWB, CoWCu, NiFe, NiFeP, NiFeB, CoNi, CoNiP, CoNiB, CoNiFe, CoNiFeP, or CoNiFeB.  
     
     
         10 . The method according to  claim 1 , further comprising forming an anti-reflective coating (ARC) over the plating seed layer, before forming the mask, and further comprising removing the ARC from over the first insulating layer, before forming the ferromagnetic liner.  
     
     
         11 . The method according to  claim 1 , wherein plating the first conductive line comprises forming a first conductive line comprising Cu, Ag, or Al, or combinations thereof, and wherein plating the first conductive line comprises forming a first conductive line comprising a thickness of about 450 nm or less.  
     
     
         12 . The method according to  claim 1 , wherein plating the first conductive line comprises plating the first conductive line using an electroless plating process, a potentiostatically triggered electroless plating process, a potentiostatically triggered electroless plating process using Pd activation, an electroplating process, a potentiostatic plating process, or combinations thereof.  
     
     
         13 . The method according to  claim 1 , wherein exposing the electrical contact to the magnetic memory cell comprises a chemical-mechanical polish (CMP) of the first insulating layer.  
     
     
         14 . The method according to  claim 1 , wherein exposing the electrical contact to the magnetic memory cell comprises a combination of a chemical mechanical polish (CMP) process to planarize the first insulating layer followed by a reactive ion etch (RIE) or wet chemical etch to expose the electrical contact to the magnetic memory cell.  
     
     
         15 . The method according to  claim 1 , wherein the first insulating layer used to encapsulate the memory cell comprises a self-planarizing material, and wherein exposing the top electrical contact to the memory cell is achieved by a reactive ion etch (RIE) or a wet chemical etch of a portion of the self-planarizing material.  
     
     
         16 . The method according to  claim 1 , further comprising: 
 planarizing the first insulating layer; and    using a single damascene process, forming a via in the first insulating layer after planarizing the first insulating layer, filling the via in the first insulating layer with a conductive material, and polishing the first insulating layer and the conductive material to form a conductive via within the first insulating layer; wherein plating the first conductive line further comprises plating a first conductive line over the conductive via, and wherein forming the ferromagnetic liner further comprises forming the ferromagnetic liner over the first conductive line over the conductive via.    
     
     
         17 . The method according to  claim 16 , wherein the conductive via comprises sidewalls, further comprising removing a top portion of the first insulating layer, before forming the ferromagnetic liner, and wherein forming the ferromagnetic liner further comprises forming the ferromagnetic liner over a top portion of the sidewalls of the conductive via.  
     
     
         18 . The method according to  claim 1 , further comprising: 
 planarizing the first insulating layer; and    using a single damascene process, forming a via in the first insulating layer after planarizing the first insulating layer, filling the via in the first insulating layer with a conductive material, and polishing the first insulating layer and the conductive material to form a conductive via within the first insulating layer; wherein plating the first conductive line further comprises plating a first conductive line over the conductive via, and wherein forming the ferromagnetic liner does not comprise forming the ferromagnetic liner over the first conductive line over the conductive via.    
     
     
         19 . The method according to  claim 1 , wherein forming the mask comprises forming a resist or forming a dielectric material comprising SiO x , SiN, SiCOH, SiCN, fluorinated SiO x , or a low dielectric constant (low-k) material.  
     
     
         20 . The method according to  claim 1 , wherein the magnetic memory device comprises a magnetic random access memory (MRAM) device, wherein the at least one magnetic memory cell comprises a plurality of magnetic tunnel junctions (MTJ's) arranged in an array of rows and columns, wherein plating the first conductive line comprises forming a first conductive line over each of the MTJ's in a row or column of the array.  
     
     
         21 . The method according to  claim 1 , further comprising planarizing the at least one magnetic memory cell and the first insulating layer, before forming the mask over the first insulating layer.  
     
     
         22 . The method according to  claim 21 , further comprising depositing a second insulating layer over the at least one magnetic memory cell and the first insulating layer, wherein planarizing the at least one magnetic memory cell and the first insulating layer further comprises planarizing the second insulating layer.  
     
     
         23 . The method according to  claim 1 , wherein the electrical contact disposed over the at least one magnetic memory cell comprises about 200 nm or less of TiN, Ti, Ta, TaN, WN, W, Cu, or combinations thereof.  
     
     
         24 . The method according to  claim 1 , further comprising forming a diffusion barrier over the first conductive line, before forming the ferromagnetic liner.  
     
     
         25 . The method according to  claim 24 , wherein forming the diffusion barrier comprises forming about 30 nm or less of a Co alloy.  
     
     
         26 . The method according to  claim 24 , wherein forming the diffusion barrier comprises forming CoWP or CoWB.  
     
     
         27 . A magnetic memory device, comprising: 
 a plurality of magnetic memory elements formed in an array region;    a plurality of conductive vias formed in a peripheral region, the plurality of conductive vias comprising sidewalls;    a first conductive line disposed over at least one of the plurality of magnetic memory elements, the first conductive line comprising a top surface and sidewalls;    a second conductive line disposed over at least one of the plurality of conductive vias, the second conductive line comprising a top surface and sidewalls; and    a ferromagnetic liner disposed on the top surface and the sidewalls of the first conductive line and disposed on the top surface and sidewalls of the second conductive line, wherein the ferromagnetic liner is also disposed on a top portion of the sidewalls of a conductive via proximate the second conductive line.    
     
     
         28 . The magnetic memory device according to  claim 27 , wherein the ferromagnetic liner comprises about 50 nm or less of Ni, Fe, Co, alloys thereof, P, B, or combinations thereof.  
     
     
         29 . The magnetic memory device according to  claim 28 , wherein the ferromagnetic liner comprises CoWP, CoWB, CoWCu, NiFe, NiFeP, NiFeB, CoNi, CoNiP, CoNiB, CoNiFe, CoNiFeP, or CoNiFeB.  
     
     
         30 . The magnetic memory device according to  claim 27 , wherein the first conductive line and the second conductive line comprise Cu, Ag, Al, or combinations thereof.  
     
     
         31 . The magnetic memory device according to  claim 27 , further comprising a barrier layer disposed between the first conductive line and the at least one of the plurality of magnetic memory elements, and between the second conductive line and the at least one of the plurality of conductive vias, and a seed layer disposed between the barrier layer and the first conductive line, and between the barrier layer and the second conductive line.  
     
     
         32 . The magnetic memory device according to  claim 31 , wherein the barrier layer comprises about 20 nm or less of Ta, TaN, WN, TiN, Ru, or combinations thereof, and wherein the seed layer comprises about 50 nm or less of Ru, Cu, Ag, or combinations thereof.  
     
     
         33 . The magnetic memory device according to  claim 27 , wherein the magnetic memory device comprises a magnetic random access memory (MRAM) device, and wherein the plurality of magnetic memory elements comprise magnetic tunnel junctions (MTJ's).  
     
     
         34 . The magnetic memory device according to  claim 27 , further comprising a diffusion barrier disposed between the ferromagnetic liner and the first conductive line, between the ferromagnetic liner and the second conductive line, and between the ferromagnetic liner and the top portion of the at least one of the plurality of conductive vias.  
     
     
         35 . The magnetic memory device according to  claim 34 , wherein the diffusion barrier comprises about 30 nm or less of CoWP, CoWB, or other Co alloys.