Materials and methods for control of stability and rheological behavior of particulate suspensions

Abstract

The subject invention relates to a method and materials for the control of the energy barrier to agglomeration with respect to particles. Controlling the energy barrier to agglomeration can, for example, cause the particles to enter suspension and/or depart from suspension, as desired. By fine-tuning the energy barrier, a variety of processes can be enhanced. The subject invention also pertains to the control of the energy barrier between particles and a surface. In a specific embodiment, the subject invention can be utilized for chemical-mechanical polishing (CMP) processes. In a preferred embodiment, the subject invention concerns a slurry composition including abrasive particles, at least one dispersant, and at least one competing agent, wherein the competing agent competes with the dispersant for adsorption sites on the substrate, thereby hindering the dispersant's influence on the particle-substrate interaction within the composition, without eliminating the dispersant's influence on the particle-particle interaction (steric repulsion) within the composition, thereby maintaining a stable solution.

We claim:  
     
         1 . A composition for polishing a substrate, said composition comprising particles, at least one dispersant, and at least one competing agent.  
     
     
         2 . The composition of  claim 1 , wherein said competing agent is present within said composition in an amount effective to compete with said dispersant for adsorption sites on said substrate, thereby hindering said dispersant's influence on the particle-substrate interaction within said composition.  
     
     
         3 . The composition of  claim 2 , wherein said competing agent does not eliminate said dispersant's influence on the particle-particle interaction within said composition.  
     
     
         4 . The composition of  claim 1 , wherein said competing agent competes with said dispersant for the same adsorption sites on said substrate as the dispersant, thereby weakening the affinity of said dispersant for the substrate.  
     
     
         5 . The composition of  claim 1 , wherein said dispersant is a surfactant.  
     
     
         6 . The composition of  claim 1 , wherein said competing agent comprises a multivalent counterion.  
     
     
         7 . The composition of  claim 1 , wherein said multivalent counterion is selected from the group consisting of barium, calcium, aluminum, and magnesium.  
     
     
         8 . The composition of  claim 1 , wherein said competing agent comprises a metal hydroxide.  
     
     
         9 . The composition of  claim 8 , wherein said metal hydroxide is selected from the group consisting of Ca(OH) +  and Ba(OH) + .  
     
     
         10 . The composition of  claim 1 , wherein said competing agent comprises a polyelectrolyte.  
     
     
         11 . The composition of  claim 1 , wherein said competing agent comprises an organic amine.  
     
     
         12 . The composition of  claim 1 , wherein said surfactant is a cationic surfactant.  
     
     
         13 . The composition of  claim 12 , wherein said cationic surfactant is selected from the group consisting of long chain amines, synthetic amines, diamines, polyamines, quaternary ammonium salts, quaternized polyoxyalkylenated long chain amines, unquaternized polyoxyalkylenated long chain amines, and amine oxides.  
     
     
         14 . The composition of  claim 12 , wherein said cationic surfactant comprises a long chain quaternary ammonium compound.  
     
     
         15 . The composition of  claim 12 , wherein said cationic surfactant has an alkyl chain 8 to 16 carbon atoms in length.  
     
     
         16 . The composition of  claim 12 , wherein said cationic surfactant comprises an alkyl trimethylammonium bromide.  
     
     
         17 . The composition of  claim 16 , wherein said alkyl trimethylammonium bromide has an alkyl chain 8 to 16 carbon atoms in length.  
     
     
         18 . The composition of  claim 16 , wherein said alkyl trimethylammonium bromide is selected from the group consisting of octyl trimethyl ammonium bromide, decyl trimethyl ammonium bromide, and dodecyl trimethyl ammonium bromide.  
     
     
         19 . The composition of  claim 6 , wherein said multivalent counterion is a divalent cation.  
     
     
         20 . The composition of  claim 19 , wherein said divalent cation is selected from the group consisting of Ca ++  and Ba ++ .  
     
     
         21 . The composition of  claim 1 , wherein said surfactant and said competing agent are the same substance.  
     
     
         22 . The composite of  claim 1 , wherein said particles are abrasive particles.  
     
     
         23 . The composition of  claim 22 , wherein said abrasive particles comprise silica.  
     
     
         24 . The composition of  claim 1 , wherein the mean size of said particles is within the range about 10 nm to 10 μm.  
     
     
         25 . The composition of  claim 1 , wherein the mean size of said particles is within the range of about 10 nm and 300 nm.  
     
     
         26 . The composition of  claim 1 , wherein said composition has a pH within the range of about 9 to 12.  
     
     
         27 . The composition of  claim 1 , wherein said composition has a pH within the range of about 10 and about 11.  
     
     
         28 . The composition of  claim 1 , wherein said dispersant is adsorbed onto said substrate.  
     
     
         29 . The composition of  claim 24 , wherein said substrate is silica.  
     
     
         30 . The composition of  claim 1 , wherein said dispersant is present in said slurry composition at a concentration equal to or greater than the critical micelle concentration.  
     
     
         31 . The composition of  claim 1 , wherein said dispersant is present in said slurry composition within a range of about 1 critical micelle concentration to about 2 critical micelle concentration.  
     
     
         32 . The composition of  claim 1 , further comprising an anionic surfactant.  
     
     
         33 . The composition of  claim 32 , wherein said anionic surfactant comprises sodium dodecyl sulfate.  
     
     
         34 . The composition of  claim 1 , wherein said dispersant is a cationic surfactant selected from the group consisting of octyl trimethyl ammonium bromide, decyl trimethyl ammonium bromide, and dodecyl trimethyl ammonium bromide, wherein said multivalent counterion is a divalent cation selected from the group consisting of Ca ++  and Ba ++ , and wherein said cationic surfactant present in said composition at a concentration equal to or greater than the critical micelle concentration.  
     
     
         35 . The composition of  claim 1 , wherein said particles are in suspension.  
     
     
         36 . The composition of  claim 31 , wherein said particles are in stable suspension.  
     
     
         37 . A method for polishing a substrate, said method comprising: contacting a slurry composition to the substrate and polishing the substrate, wherein the slurry composition comprises the composition of  claim 1 .  
     
     
         38 . The method according to  claim 37 , wherein said polishing comprises applying a polishing pad to the substrate, wherein the slurry composition is interposed between the substrate and the polishing pad.  
     
     
         39 . The method according to  claim 37 , further comprising placing the substrate on a carrier, wherein said polishing comprises applying a polishing pad to the substrate on the carrier, and wherein the slurry composition is interposed between the substrate and the polishing pad.  
     
     
         40 . The method according to  claim 37 , wherein the substrate has a surface, and wherein the dispersant is adsorbed onto the surface of the substrate.  
     
     
         41 . The method according to  claim 37 , wherein the substrate has a surface, wherein the slurry composition is contacted to the surface of the substrate, wherein said method further comprises removing the abrasive particles from the surface of the substrate.  
     
     
         42 . A method of making a slurry composition, said method comprising admixing at least one dispersant with particles, and subsequently adding at least one competing agent to the mixture.  
     
     
         43 . The method of  claim 42 , wherein the competing agent is present within the slurry composition in an amount effective to compete with the dispersant for absorption sites on a substrate, thereby weakening the affinity of the dispersant for the substrate.  
     
     
         44 . A method for controlling the energy barrier to agglomeration of particles in a composition containing at least one dispersant, said method comprising modulating the interaction between the particles and a substrate.  
     
     
         45 . The method of  claim 1 , wherein said modulating comprises weakening the affinity of the dispersant for the substrate, thereby increasing the stability of the composition.  
     
     
         46 . The method of  claim 45 , wherein said weakening comprises adding at least one competing agent to the mixture, wherein the competing agent competes with the dispersant for the same adsorption sites on the substrate as the dispersant.  
     
     
         47 . The method of  claim 44 , wherein said modulating comprises strengthening the affinity of the dispersant for the substrate, thereby decreasing the stability of the composition.  
     
     
         48 . The method of  claim 47 , wherein the composition comprises at least one competing agent, and wherein said stregthening comprises inhibiting the competing agent's affinity for the substrate.  
     
     
         49 . The method of  claim 48 , where said inhibiting comprises removing the competing