Hard abrasive particle-free polishing of hard materials method

Abstract

A method of chemical mechanical polishing (CMP) includes providing a slurry solution including at least one per-compound permanganate oxidizer in a concentration between 0.01 M and 2 M, with a pH level from 1.5 to 5 or from 8 to 11, and at least one buffering agent. The buffering agent is different from this pure-compound permanganate oxidizer, and comprises a surfactant and/or an alkali metal ion. The slurry solution is exclusive of any added particles. The slurry solution is dispensed on a hard surface having a Vickers hardness >1,000 kg/mm2 and is pressed by a polishing pad with the slurry solution in between while rotating the polishing pad relative to the hard surface.

1 . A method of chemical mechanical polishing (CMP) hard surfaces, comprising:
 providing a slurry solution comprising:
 an aqueous medium; 
 at least one per-compound permanganate oxidizer with a concentration between 0.01 M and 2 M; 
 a pH level from 1.5 to 5 or from 8 to 11; 
 at least one buffering agent different from the per-compound permanganate oxidizer, the buffering agent comprising at least one of a surfactant and an alkali metal ion; 
 the slurry solution being exclusive of any added particles, 
 dispensing the slurry solution on a hard surface having a Vickers hardness>1,000 kg/mm 2 , and 
 pressing with a polishing pad with the slurry solution on the hard surface in between while rotating the polishing pad relative to the hard surface. 
   
     
     
         2 . The method of  claim 1 , wherein the pH level is 1.5 to 5 and wherein the slurry solution includes in situ soft particles formed by a decomposition of the per-compound permanganate oxidizer to form MnO 2  particles that have a Mohs hardness less than or equal to (≤) 3. 
     
     
         3 . The method of  claim 1 , wherein the hard surface comprises a carbide, a nitride, or a mixture thereof. 
     
     
         4 . The method of  claim 1 , wherein the slurry solution further comprises transition metal ions in a concentration from 0.03 M to 1 M in addition to any transition metals ions that may be in the per-compound permanganate oxidizer. 
     
     
         5 . The method of  claim 1 , wherein the polishing pad comprise a polymeric pad having a Shore D hardness less than 100, and wherein a polishing pressure used for the pressing is less than 15 psi. 
     
     
         6 . The method of  claim 1 , wherein the buffering agent comprises the surfactant, and wherein the surfactant is an anionic surfactant having a concentration from 0.01 grams per liter to 20 grams per liter. 
     
     
         7 . The method of  claim 1 , wherein the slurry solution further comprises at least one alkali metal ion besides an alkali metal ion in the per-compound permanganate oxidizer if the per-compound permanganate oxidizer includes an alkali metal ion. 
     
     
         8 . A method of chemical mechanical polishing (CMP) hard surfaces, comprising:
 providing a slurry solution comprising:
 an aqueous medium, 
 at least one per-compound permanganate oxidizer with a concentration between 0.01 M and 2 M, 
 a pH level from 1.5 to 5, 
 at least one buffering agent different from the per-compound oxidizer, the buffering agent comprising at least one of a surfactant and an alkali metal ion, 
 the slurry solution being exclusive of any added particles, 
 dispensing the slurry solution on a hard surface having a Vickers hardness>1,000 kg/mm 2 , 
 pressing with a polishing pad with the slurry solution on the hard surface in between while rotating the polishing pad relative to the hard surface, and 
 wherein the slurry solution includes in situ soft particles formed by a decomposition of the per-compound permanganate oxidizer to form MnO 2  particles that have a Mohs hardness less than or equal to (≤) 3. 
   
     
     
         9 . The method of  claim 8 , wherein the polishing pad comprise a polymeric pad having a Shore D hardness less than 100, and wherein a polishing pressure used for the pressing is less than 15 psi. 
     
     
         10 . The method of  claim 8 , wherein the hard surface comprises a carbide, a nitride, or a mixture thereof. 
     
     
         11 . The method of  claim 8 , wherein the buffering agent comprises the surfactant, and wherein the surfactant is an anionic surfactant having a concentration from 0.01 grams per liter to 20 grams per liter.