METHOD AND APARATUS FOR ELECTROCHEMICAL MECHANICAL POLISHING NiP SUBSTRATES

Abstract

The present invention relates to an apparatus and a method of electrochemical mechanical polishing (ECMP) for microelectronics applications. The apparatus and method of electrochemical mechanical polishing can be used planarize NiP substrate for a magnetic storage medium and for a process which allows polishing with a controlled surface finish, and a set of corresponding polishing electrolytes and slurry.

1 . An electromechanical chemical polishing apparatus for polishing a NiP substrate which comprises:
 (a) a fixed carrier body where the NiP substrate is affixed;   (b) a polishing pad below the carrier body and in contact with the NiP substrate, wherein the pad has two layers:
 (i) a top layer which is a perforated pad which allows the polishing slurry or electrolyte to have direct contact with the lower layer of the polishing pad; and 
 (ii) a lower layer which is electrically conductive and acts as a cathode; 
   (c) an NiP substrate which acts as an anode; and   (d) a power supply.   
     
     
         2 . An electromechanical chemical polishing apparatus for polishing a NiP substrate which comprises:
 (a) a carrier body where the NiP substrate is affixed;   (b) a first polishing tape which polishes the front side of the NiP substrate;   (c) a second polishing tape which polishes the back side of the NiP substrate;   wherein:
 (i) the carrier body with an NiP substrate affixed is rotating between the first and second polishing tape; 
 (ii) the first and second polishing tape comprise of an electrically conductive material with a thin, porous, non-conductive polymer coating to allow for the first and second tape to carry an slurry or electrolyte; 
   (d) an an NiP substrate which acts as an anode;   (e) a cathode which is attached to the carrier body; and   (f) a power supply.   
     
     
         3 . The apparatus of  claim 2 , wherein the rotating carrier/NiP substrate moves in a direction which is substantially perpendicular to the movement of the first and second polishing tape. 
     
     
         4 . A shear sensitive electrolyte delivery system which is a liposome formed from 5-15% egg lecithin, 25-35% sodium xylenesulfonate and 50-70% deionized water which encapsulated the electrolytes from a 0.2-0.5% solution of CuSO 4  which has been added to the liposome. 
     
     
         5 . A process of polishing an NiP substrate which comprises affixing an NiP substrate to the apparatus of  claim 1  and polishing the substrate with the polishing pad with the addition of a slurry or electrolyte, wherein the surface charge of the substrate is controlled by the electric potential applied onto the surface of the NiP substrate. 
     
     
         6 . A process of polishing an NiP substrate which comprises affixing an NiP substrate to the apparatus of  claim 2  and polishing the substrate with the first and second tape with the addition of a slurry or electrolyte, wherein the surface charge is controlled by the electric potential applied onto the surface of the NiP substrate. 
     
     
         7 . The process of  claim 5 , wherein the polishing process results in a microwaviness of about 1.0-2.5 (Å/max.amplitude) and a surface roughness of 1.0-2.5 Å. 
     
     
         8 . The process of  claim 7 , wherein the polishing process results in a microwaviness of about 1.0-1.5 (Å/max.amplitude) and a surface roughness of 1.0-1.5 Å. 
     
     
         9 . The process of  claim 8 , wherein the polishing process is a continuous process. 
     
     
         10 . The process of  claim 9 , wherein the electrolyte is delivered by a shear sensitive electrolyte delivery system which is a liposome formed from 5-15% egg lecithin, 25-35% sodium xylenesulfonate and 50-70% deionized water which encapsulated the electrolytes from a 0.2-0.5% solution of CuSO 4  which has been added to the liposome 
     
     
         11 . The process of  claim 6 , wherein the polishing process results in a microwaviness of about 1.0-2.5 (Å/max.amplitude) and a surface roughness of 1.0-2.5 Å. 
     
     
         12 . The process of  claim 11 , wherein the polishing process results in a microwaviness of about 1.0-1.5 (Å/max.amplitude) and a surface roughness of 1.0-1.5 Å. 
     
     
         13 . The process of  claim 12 , wherein the polishing process is a continuous process. 
     
     
         14 . The process of  claim 13 , wherein the electrolyte is delivered by a shear sensitive electrolyte delivery system which is a liposome formed from 5-15% egg lecithin, 25-35% sodium xylenesulfonate and 50-70% deionized water which encapsulated the electrolytes from a 0.2-0.5% solution of CuSO 4  which has been added to the liposome.