Chemical-mechanical planarization using ozone

Abstract

The present invention relates to the use of ozone (O 3 ) as a reagent in chemical mechanical planarization either in aqueous solution or as a gas directly impinging on the surface to be planarized. An aqueous solution containing ozone may optionally contain abrasive particles and/or additional CMP reagents co-dissolved with the ozone including carbonate and bicarbonate anions, and organic acids such as formic, oxalic, acetic and glycol. Abrasives that may be added include alumina, silica, spinel, ceria, zirconia. Typical concentrations of ozone aqueous solution are in the range from approximately 1 part-per-million up to saturation. Ammonium salts, particularly ammonium carbonate facilitate planarization in cooperation with ozone-containing aqueous solution. Low k dielectric materials, organic as well as inorganic, and difficult to oxidize metals can be planarized with ozone reagents pursuant to the present invention.

We claim:  
     
         1 . A composition for chemical mechanical planarization comprising an aqueous solution of ozone and abrasive particles.  
     
     
         2 . A composition as in  claim 1  wherein said abrasive particles are selected from the group consisting of alumina, silica, ceria, spinel, zirconia and mixtures thereof.  
     
     
         3 . A composition as in  claim 1  further comprising at least one additive selected from the group consisting of carbonate, bicarbonate, oxalic acid, formic acid, acetic acid, glycol acids and mixtures thereof.  
     
     
         4 . A composition as in  claim 1  wherein the concentration of ozone in said aqueous solution is less that at which ozone interactions occur.  
     
     
         5 . A composition as in  claim 4  wherein said concentration of ozone is less than about 20 parts per million.  
     
     
         6 . A composition as in  claim 1  further comprising at least one ammonium salt.  
     
     
         7 . A composition as in  claim 6  wherein said at least one ammonium salt is ammonium carbonate.  
     
     
         8 . A method of planarizing a surface by directing ozone gas onto said surface.  
     
     
         9 . A method of planarizing a surface by directing onto said surface an aqueous solution containing ozone and causing relative motion of said surface and a polishing pad in contact therewith.  
     
     
         10 . A method as in  claim 9  further comprising abrasive particles in said aqueous solution.  
     
     
         11 . A method as in  claim 10  wherein said abrasive particles are selected from the group consisting of alumina, silica, ceria, spinel, zirconia and mixtures thereof.  
     
     
         12 . A method as in  claim 10  further comprising at least one ammonium salt.  
     
     
         13 . A method as in  claim 12  wherein said at least one ammonium salt is ammonium carbonate.