Chemical mechanical planarization of low dielectric constant materials

Abstract

The present invention relates to apparatus, procedures and compositions for avoiding and reducing damage to low dielectric constant materials and other soft materials, such as Cu and Al, used in fabricating semiconductor devices. Damage reduction can be achieved by decreasing the role of mechanical abrasion in the CMP of these materials and increasing the role of chemical polishing, which can also improve material removal rates. Increasing the role of chemical polishing can be accomplished by creating a polishing slurry, which contains components that interact chemically with the surface to be polished. This slurry may or may not also contain soft abrasive particles, which replace the hard abrasive particles of conventional slurries. Use of soft abrasive particles can reduce the role of mechanical abrasion in the CMP process. Use of this slurry in CMP can reduce surface scratches and device damage.

We claim:  
     
         1 . An abrasive slurry for the planarization of a low dielectric constant surface comprising abrasive particles having a hardness comparable to the hardness of said surface, wherein said abrasive particles have a surface charge opposite to that of said surface.  
     
     
         2 . An abrasive slurry as in  claim 1  wherein said abrasive particles are polymers.  
     
     
         3 . An abrasive slurry as in  claim 2  wherein said abrasive particles are selected from the group consisting of polystyrene-acrylonitrile, Nylon-6, polyoxymethylene, polyurethane and poly(para-divinylphenylene) and mixtures thereof.  
     
     
         4 . An abrasive slurry as in  claim 1  wherein said abrasive particles comprise a coating on a core wherein said coating material is softer than said core material.  
     
     
         5 . A method of planarizing a low dielectric constant surface comprising performing a conventional chemical mechanical planarization followed by buffing with an abrasive slurry wherein said abrasive slurry has a hardness less than or comparable to the hardness of said surface.