Forming ferroelectric polymer memories

Abstract

In accordance with some embodiments, a ferroelectric polymer memory may be formed of a plurality of stacked layers. Each layer may be separated from the ensuing layer by a polyimide layer. The polyimide layer may provide reduced layer-to-layer coupling, and may improve planarization after the lower layer fabrication.

1 . A method comprising: 
 coating a first metal layer with hexamethyldisilazane;    forming a layer of polymer over said coating, said polymer to act as a ferroelectric polymer in a ferroelectric polymer memory; and    plasma etching a second metal layer formed over said polymer using a gas mixture including helium, said metal layers and polymer layer to form a first layer of ferroelectric polymer memory.    
     
     
         2 . The method of  claim 1  including forming a polyimide layer over said first layer of ferroelectric polymer memory.  
     
     
         3 . The method of  claim 2  including forming a second layer of a ferroelectric polymer memory and forming another polyimide layer over said second memory layer.  
     
     
         4 . The method of  claim 1  wherein forming a layer of polymer over said coating includes forming a copolymer layer including vinyledene fluoride and trifloroethylene over said coating.  
     
     
         5 . The method of  claim 4  including spin coating the copolymer in an organic solvent.  
     
     
         6 . The method of  claim 5  including evaporating the organic solvent using heat.  
     
     
         7 . The method of  claim 1  wherein plasma etching a second metal layer includes etching said metal layer with a selectivity greater then 1.25.  
     
     
         8 . The method of  claim 1  wherein plasma etching a second metal layer includes etching said metal layer with a selectivity greater than 2.  
     
     
         9 . The method of  claim 1  wherein plasma etching a second metal layer includes using a radio frequency bias from about 20 to about 30 Watts.  
     
     
         10 . The method of  claim 1  wherein plasma etching a second metal layer includes using a gas mixture including Cl 2  and BCL 3 .  
     
     
         11 . A method comprising: 
 forming a ferroelectric polymer over a first metal layer, said first metal layer patterned to form metal bitlines, said ferroelectric polymer to extend over said bitlines and downward between said bitlines toward an underlying substrate; and    forming a second metal layer over said ferroelectric polymer layer, said second metal layer to be patterned to form row lines that extend transverse to said bitlines.    
     
     
         12 . The method of  claim 11  wherein forming a ferroelectric polymer over a first metal layer includes forming a ferroelectric copolymer of vinyledene fluoride and trifluoroethylene over said first metal layer.  
     
     
         13 . The method of  claim 11  further including before forming said ferroelectric polymer, coating said bitlines with hexamethyldisilazane.  
     
     
         14 . The method of  claim 13  further including using a solution including diethylcarbonate to coat said bitlines.  
     
     
         15 . The method of  claim 13  further including annealing to form a piezoelectric film.  
     
     
         16 . The method of  claim 11  wherein said first and second metal layers and said ferroelectric polymer form a first layer of a ferroelectric polymer memory.  
     
     
         17 . The method of  claim 16  further including forming a polyimide layer over said metal row lines.  
     
     
         18 . The method of  claim 17  further including forming a second layer of ferroelectric polymer memory over said polyimide layer, said second layer of ferroelectric polymer memory including a ferroelectric polymer formed over metal bitlines and metal row lines formed over said ferroelectric polymer.  
     
     
         19 . The method of  claim 18  including forming another polyimide layer over said second layer of ferroelectric polymer memory.  
     
     
         20 . A method comprising: 
 forming a layer of a polymer over a first metal layer coated with hexamethyldisilazane, said polymer to enable data storage in a ferroelectric polymer memory;    plasma etching a second metal layer formed over said polymer, said plasma etching using a gas mixture including helium; and    after said etching, forming a polyimide layer over said second metal layer.    
     
     
         21 . The method of  claim 21  including forming a plurality of bitlines over a semiconductor structure.  
     
     
         22 . The method of  claim 21  wherein plasma etching includes etching a plurality of row lines extending generally transverse to said bitlines.  
     
     
         23 . The method of  claim 20  including etching said second metal layer with a selectivity greater than  2 .  
     
     
         24 . The method of  claim 20  wherein plasma etching includes plasma etching using a radio frequency bias of from about 20 Watts to about 30 Watts.  
     
     
         25 . The method of  claim 20  wherein plasma etching includes plasma etching using a gas mixture including Cl 2  and BCL 3 .  
     
     
         26 . The method of  claim 20  wherein forming a layer of a polymer includes forming a copolymer including vinyledene fluoride and trifluroethylene.  
     
     
         27 . The method of  claim 20  wherein said polymer and said first and second metal layers form a first layer of a ferroelectric polymer memory, and including forming a second layer of ferroelectric polymer memory over said polyimide layer, the polymer layer of the second layer of ferroelectric polymer memory formed; over a metal layer, and a hexamethyldisilazane layer between said polymer layer and said metal layer of said second layer of ferroelectric polymer memory.