Processing of a CMP slurry for improved planarization of integrated circuit wafers

Abstract

The disclosure is directed to a system that processes chemical mechanical planarization (CMP) slurries to reduce or eliminate large particles in the slurries, which can scratch integrated circuit wafers without substantially altering a percentage of solids in the CMP slurry by weight. In particular, the system breaks up particles of a CMP slurry using an intensifier pump system and a fluid processing device. The techniques have proven much more effective than conventional filtering techniques in reducing or eliminating scratches to integrated circuit wafers when a processed CMP slurry is used in a CMP process.

1 . A method comprising processing a chemical mechanical planarization (CMP) slurry via an intensifier pump system and a fluid processing device that breaks up at least some particles of the CMP slurry to reduce particle size. 
   
   
       2 . The method of  claim 1 , wherein the processing does not substantially alter a percentage of solids in the CMP slurry by weight. 
   
   
       3 . The method of  claim 1 , further comprising planarizing an integrated circuit wafer using the processed CMP slurry. 
   
   
       4 . The method of  claim 3 , wherein planarizing the integrated circuit wafer includes several separate planarizing steps. 
   
   
       5 . The method of  claim 3 , wherein planarizing the integrated circuit wafer includes depositing the processed CMP slurry onto a polishing pad. 
   
   
       6 . The method of  claim 5 , wherein the polishing pad rotates and wherein planarizing the integrated circuit wafer includes rotating the integrated circuit wafer relative to the rotating polishing pad. 
   
   
       7 . The method of  claim 3 , further comprising filtering the processed CMP slurry prior to planarizing the integrated circuit wafer. 
   
   
       8 . The method of  claim 1 , wherein the intensifier pump system includes at least two hydraulic intensifier pumps, and wherein processing the CMP slurry includes operating the hydraulic intensifier pumps in a complementary fashion. 
   
   
       9 . The method of  claim 1 , wherein the fluid processing device includes:
 a first annular flow path for the CMP slurry;   a second annular flow path for the CMP slurry;   an outlet for the CMP slurry flowing within the first and second annular flow paths;   a flow path cylinder that defines an outer diameter of the first and second annular flow paths, the outlet being formed in the flow path cylinder; and   a cylindrical rod positioned within the flow path cylinder that defines an inner diameter of the first and second annular flow paths, wherein the cylindrical rod is not attached to any structure within the fluid processing device and is free to move under fluid dynamic force relative to the flow path cylinder.   
   
   
       10 . The method of  claim 1 , wherein the CMP slurry includes particles dispersed in water. 
   
   
       11 . The method of  claim 10 , wherein the particles comprise at least one of:
 alumina (Al 2 O 3 );   cerium oxide (CeO 2 ) and   silicon dioxide (SiO 2 ).   
   
   
       12 . The method of  claim 1 , further comprising adding additives to the CMP slurry. 
   
   
       13 . A planarization system for integrated circuit wafers comprising:
 a chemical mechanical planarization (CMP) slurry processing system that processes a CMP slurry to break up at least some particles of the CMP slurry to reduce particle size; and   a CMP unit that planarizes an integrated circuit wafer using the processed CMP slurry.   
   
   
       14 . The planarization system of  claim 13 , wherein the CMP slurry processing system does not substantially alter a percentage of solids in the CMP slurry by weight. 
   
   
       15 . The planarization system of  claim 14 , wherein the CMP slurry processing system includes an intensifier pump system and a fluid processing device that breaks up at least some of the particles of the CMP slurry. 
   
   
       16 . The planarization system of  claim 15 , wherein the intensifier pump system includes at least two hydraulic intensifier pumps that operate in a complementary fashion. 
   
   
       17 . The planarization system of  claim 16 , wherein the fluid processing device includes:
 a first annular flow path for the CMP slurry;   a second annular flow path for the CMP slurry;   an outlet for the CMP slurry flowing within the first and second annular flow paths;   a flow path cylinder that defines an outer diameter of the first and second annular flow paths, the outlet being formed in the flow path cylinder; and   a cylindrical rod positioned within the flow path cylinder that defines an inner diameter of the first and second annular flow paths, wherein the cylindrical rod is not attached to any structure within the fluid processing device and is free to move under fluid dynamic force relative to the flow path cylinder.   
   
   
       18 . The planarization system of  claim 14 , wherein the CMP unit includes a polishing pad and wherein the processed CMP slurry is deposited onto the polishing pad. 
   
   
       19 . The planarization system of  claim 18 , wherein the polishing pad rotates and wherein a mechanism rotates the integrated circuit wafer relative to the rotating polishing pad. 
   
   
       20 . The planarization system of  claim 14 , wherein the CMP slurry includes particles dispersed in water, wherein the particles comprise at least one of:
 alumina (Al 2 O 3 );   cerium oxide (CeO 2 ) and   silicon dioxide (SiO 2 ).   
   
   
       21 . The planarization system of  claim 14 , further comprising one or more filters to filter the processed CMP slurry prior to planarizing the integrated circuit wafer. 
   
   
       22 . The planarization system of  claim 14 , further comprising a feedback loop to feed unused portions of the processed CMP slurry back to the CMP slurry processing system. 
   
   
       23 . A chemical mechanical planarization (CMP) slurry comprising:
 water; and   particles dispersed in the water, wherein substantially all of the particles have a diameter less than approximately 1 micron and wherein the particles comprise at least one of:   alumina (Al 2 O 3 );   cerium oxide (CeO 2 ) and   silicon dioxide (SiO 2 ).