Fixed-abrasive chemical-mechanical planarization of titanium nitride

Abstract

Planarizing solutions, and their methods of use, for removing titanium nitride from the surface of a substrate using a fixed-abrasive planarizing pad. The planarizing solutions take the form of an etchant solution or an oxidizing solution. The etchant solutions are aqueous solutions containing an etchant and a buffer. The etchant contains one or more etching agents selective to titanium nitride. The oxidizing solutions are aqueous solutions containing an oxidizer and a buffer. The oxidizer contains one or more oxidizing agents selective to titanium nitride. In either solution, i.e., etchant or oxidizing solution, the buffer contains one or more buffering agents. Titanium nitride layers planarized in accordance with the invention may be utilized in the production of integrated circuits, various apparatus utilizing such integrated circuits, and memory systems.

1 . A memory device, comprising: 
 an array of memory cells;    a row access circuit coupled to the array of memory cells;    a column access circuit coupled to the array of memory cells; and    an address decoder circuit coupled to the row access circuit and the column access circuit, wherein at least one of the memory cells, the row access circuit, the column access circuit and the address decoder circuit have a titanium nitride layer, further wherein the titanium nitride layer is planarized by a method comprising: 
 abrading the titanium nitride layer with a planarizing surface of a planarizing medium comprising a fixed-abrasive planarizing pad and a clean planarizing solution.  
   
   
   
       2 . A memory device, comprising: 
 an array of memory cells;    a row access circuit coupled to the array of memory cells;    a column access circuit coupled to the array of memory cells; and    an address decoder circuit coupled to the row access circuit and the column access circuit,    wherein at least one of the memory cells, the row access circuit, the column access circuit and the address decoder circuit have a titanium nitride layer, the titanium nitride layer planarized by a method comprising: 
 abrading the titanium nitride layer with a planarizing surface of a planarizing medium comprising a fixed-abrasive planarizing pad and a clean planarizing solution, wherein the planarizing solution is an aqueous etchant solution comprising an etchant and a buffer, wherein the etchant comprises at least one etching agent selected from the group consisting of oxalic acid, ascorbic acid and phosphoric acid.  
   
   
   
       3 . The memory device of  claim 2 , wherein the buffer comprises at least one buffering agent selected from the group consisting of ammonium acetate, ammonium oxalate, ammonium phosphate and diammonium phosphate.  
   
   
       4 . The memory device of  claim 2 , wherein the planarizing solution has a pH of approximately 1 to 5.  
   
   
       5 . A memory device, comprising: 
 an array of memory cells;    a row access circuit coupled to the array of memory cells;    a column access circuit coupled to the array of memory cells; and    an address decoder circuit coupled to the row access circuit and the column access circuit, wherein at least one of the memory cells, the row access circuit, the column access circuit and the address decoder circuit have a titanium nitride layer, the titanium nitride layer planarized by a method comprising: 
 abrading the titanium nitride layer with a planarizing surface of a planarizing medium comprising a fixed-abrasive planarizing pad and a clean planarizing solution, wherein the planarizing solution is an aqueous oxidizing solution comprising an oxidizer and a buffer, wherein the oxidizer comprises at least one oxidizing agent selected from the group consisting of ammonium persulfate, ammonium heptamolybdate, ceric ammonium nitrate, ceric ammonium sulfate and hydrogen peroxide.  
   
   
   
       6 . The memory device of  claim 5 , wherein the buffer comprises at least one buffering agent selected from the group consisting of phosphoric acid, ammonium acetate, ammonium oxalate, ammonium phosphate and diammonium phosphate.  
   
   
       7 . The memory device of  claim 5 , wherein the planarizing solution has a pH of approximately 1 to 6.  
   
   
       8 . A memory device, comprising: 
 an array of memory cells;    a row access circuit coupled to the array of memory cells;    a column access circuit coupled to the array of memory cells; and    an address decoder circuit coupled to the row access circuit and the column access circuit, wherein at least one of the memory cells, the row access circuit, the column access circuit and the address decoder circuit have a titanium nitride layer, the titanium nitride layer planarized by a method comprising: 
 abrading the titanium nitride layer with a planarizing surface of a planarizing medium comprising a fixed-abrasive planarizing pad and a clean planarizing solution, wherein the planarizing solution comprises approximately 1% to 5% by weight of oxalic acid and approximately 2% to 10% by weight of ammonium acetate.  
   
   
   
       9 . A memory device, comprising: 
 an array of memory cells;    a row access circuit coupled to the array of memory cells;    a column access circuit coupled to the array of memory cells; and    an address decoder circuit coupled to the row access circuit and the column access circuit, wherein at least one of the memory cells, the row access circuit, the column access circuit and the address decoder circuit have a titanium nitride layer, the titanium nitride layer planarized by a method comprising: 
 abrading the titanium nitride layer with a planarizing surface of a planarizing medium including a fixed-abrasive planarizing pad and a clean planarizing solution, the planarizing solution having an oxidizer and a buffer, the planarizing solution being approximately 2% by weight of the oxidizer, wherein the oxidizer comprises at least one oxidizing agent selected from the group consisting of ammonium persulfate, ammonium heptamolybdate, ceric ammonium nitrate, ceric ammonium sulfate and hydrogen peroxide.  
   
   
   
       10 . A memory module, comprising: 
 a support;    a plurality of leads extending from the support;    a command link coupled to at least one of the plurality of leads;    a plurality of data links, wherein each data link is coupled to at least one of the plurality of leads; and    at least one memory device contained on the support and coupled to the command link, wherein the at least one memory device comprises: 
 an array of memory cells;  
 a row access circuit coupled to the array of memory cells;  
 a column access circuit coupled to the array of memory cells; and an address decoder circuit coupled to the row access circuit and the column access circuit, wherein at least one of the memory cells, the row access circuit, the column access circuit and the address decoder circuit have a titanium nitride layer, further wherein the titanium nitride layer is planarized by a method comprising: 
 abrading the titanium nitride layer with a planarizing surface of a planarizing medium comprising a fixed-abrasive planarizing pad and a clean planarizing solution.  
 
   
   
   
       11 . The memory module of  claim 10 , wherein the planarizing solution is an aqueous etchant solution comprising an etchant and a buffer, wherein the etchant comprises at least one etching agent selected from the group consisting of oxalic acid, ascorbic acid and phosphoric acid.  
   
   
       12 . The memory module of  claim 1   1 , wherein the buffer comprises at least one buffering agent selected from the group consisting of ammonium acetate, ammonium oxalate, ammonium phosphate and diammonium phosphate.  
   
   
       13 . The memory module of  claim 11 , wherein the planarizing solution has a pH of approximately 1 to 5.  
   
   
       14 . The memory module of  claim 10 , wherein the planarizing solution is an aqueous oxidizing solution comprising an oxidizer and a buffer, wherein the oxidizer comprises at least one oxidizing agent selected from the group consisting of ammonium persulfate, ammonium heptamolybdate, ceric ammonium nitrate, ceric ammonium sulfate and hydrogen peroxide.  
   
   
       15 . The memory module of  claim 14 , wherein the buffer comprises at least one buffering agent selected from the group consisting of phosphoric acid, ammonium acetate, ammonium oxalate, ammonium phosphate and diammonium phosphate.  
   
   
       16 . The memory module of  claim 14 , wherein the planarizing solution has a pH of approximately 1 to 6.  
   
   
       17 . The memory module of  claim 10 , wherein the planarizing solution is an aqueous solution comprising approximately 1% to 5% by weight of oxalic acid and approximately 2% to 10% by weight of ammonium acetate.  
   
   
       18 . A memory system, comprising: 
 a controller;    a command link coupled to the controller;    a data link coupled to the controller; and    a memory device coupled to the command link and the data link, wherein the memory device comprises: 
 an array of memory cells;  
 a row access circuit coupled to the array of memory cells;  
 a column access circuit coupled to the array of memory cells; and  
 an address decoder circuit coupled to the row access circuit and the column access circuit, wherein at least one of the memory cells, the row access circuit, the column access circuit and the address decoder circuit have a titanium nitride layer, further wherein the titanium nitride layer is planarized by a method comprising: 
 abrading the titanium nitride layer with a planarizing surface of a planarizing medium comprising a fixed-abrasive planarizing pad and a clean planarizing solution.  
 
   
   
   
       19 . The memory system of  claim 18 , wherein the planarizing solution is an aqueous etchant solution comprising an etchant and a buffer, wherein the etchant comprises at least one etching agent selected from the group consisting of oxalic acid, ascorbic acid and phosphoric acid.  
   
   
       20 . The memory system of  claim 19 , wherein the buffer comprises at least one buffering agent selected from the group consisting of ammonium acetate, ammonium oxalate, ammonium phosphate and diammonium phosphate.  
   
   
       21 . The memory system of  claim 19 , wherein the planarizing solution has a pH of approximately 1 to 5.  
   
   
       22 . The memory system of  claim 18 , wherein the planarizing solution is an aqueous oxidizing solution comprising an oxidizer and a buffer, wherein the oxidizer comprises at least one oxidizing agent selected from the group consisting of ammonium persulfate, ammonium heptamolybdate, ceric ammonium nitrate, ceric ammonium sulfate and hydrogen peroxide. agent selected from the group consisting of phosphoric acid, ammonium acetate, ammonium oxalate, ammonium phosphate and diammonium phosphate.  
   
   
       24 . The memory system of  claim 22 , wherein the planarizing solution has a pH of approximately 1 to 6.  
   
   
       25 . The memory system of  claim 18 , wherein the planarizing solution is an aqueous solution comprising approximately 1% to 5% by weight of oxalic acid and approximately 2% to 10% by weight of ammonium acetate.