Fluidized web polishing apparatus and method using contact pressure feedback

Abstract

An abrasive article with an abrasive element fabricated on a flexible foil suspended by a hydrostatic preloader, a gimball mechanism or a soft pad capable of selectively engaging with substrate to remove material while monitoring the contact pressure. A hydrostatic pressure bed is applied to the non-abrasive surface of the tensioned flexible foil to provide a contact pressure to the abrasive surface against the substrate. A series of fluid bearing surfaces are fabricated or imparted onto the abrasive side of the flexible foil to cause controlled interference and pressure with the substrate. A hydrostatic pressure emanating from the preloader supports the non-abrasive side of the flexible foil under tension while the abrasive side of the flexible foil engages a substrate. Alternatively the flexible foil web is constructed of a series of individual flexible foil bearings connected by non-straight links and housed in flexible holder pads capable of deforming and conforming to the substrate and wafer topography under applied externally applied load and moments.

1 . An abrasive article for polishing a substrate surface, the abrasive article comprising:
 a holder pad assembly;   an abrasive member held in place with respect to a holder pad, the abrasive member further comprising:
 a first surface engaged with the holder pad assembly, and 
 a second surface including an abrasive; 
   a preload mechanism positioned to biases the second surfaces of the abrasive member toward the substrate surface; and   one or more fluid bearing features on the second surface of the abrasive member configured to generate lift forces during relative motion between the abrasive article and the substrate surface.   
     
     
         2 . The abrasive article of  claim 1  further comprising at least one abrasive features located on the second surface of the abrasive member, the at least one abrasive feature applying a cutting force to the substrate surface during relative motion between the abrasive article and the substrate surface. 
     
     
         3 . The abrasive article of  claim 2  wherein the fluid bearing is a hydrostatic bearing. 
     
     
         4 . The abrasive article of  claim 3  wherein the fluid bearing is a hydrodynamic bearing. 
     
     
         5 . The abrasive article of  claim 2  wherein the at least one abrasive feature of  claim 2  includes diamond like carbon. 
     
     
         6 . The abrasive article of  claim 2  wherein the at least one abrasive feature of  claim 2  includes aluminum oxide. 
     
     
         7 . The abrasive article of  claim 2  wherein the at least one abrasive feature of  claim 2  includes a shaped abrasive feature. 
     
     
         8 . A flexible foil bearing abrasive article for polishing a substrate surface, the abrasive article comprising:
 a preloader assembly;   a flexible foil web held over the preloader assembly, the flexible foil web further comprising:
 a first surface comprising one or more fluid bearings fabricated on the flexible foil web to generate lift forces during motion of the abrasive article relative to the substrate surface; 
   a second surface engaging the preloader assembly; and   a mechanism that biases the second surface of the abrasive members toward the substrate surface.   
     
     
         9 . The flexible foil bearing abrasive article of  claim 8  further comprising at least one abrasive feature located on the first surface of the flexible foil web, the at least one abrasive feature applying cutting forces to the substrate surface during relative motion of the abrasive article and the substrate surface. 
     
     
         10 . The flexible foil bearing abrasive article of  claim 8  wherein the preloader assembly is a hydrostatic pressure bed fabricated on a curved contactor. 
     
     
         11 . The flexible foil bearing abrasive article of  claim 8  wherein the preloader assembly is a gimbal assembly with a negative suction cup. 
     
     
         12 . The flexible foil bearing abrasive article of  claim 8  wherein the fluid bearing is a hydrostatic bearing. 
     
     
         13 . The flexible foil bearing abrasive article of  claim 8  wherein the fluid bearing is a hydrodynamic bearing. 
     
     
         14 . The flexible foil bearing abrasive article of  claim 10  wherein the preloader further comprises pressure contact sensors located on a hydrostatic bed. 
     
     
         15 . A flexible foil bearing abrasive article for polishing a substrate surface, the abrasive article comprising:
 a flexible foil web under tension;   a hydrostatic preloader comprising a plurality of closed form hydrostatic beds separated by grooves connected to ambient pressure;   a first non abrasive foil surface associated with the flexible foil web;   a second abrasive foil surface associated with the flexible foil web; the first non abrasive foil surface engaging the hydrostatic preloader to impart bearing surfaces on the abrasive second flexible foil bearing surface;   a mechanism that biases the second abrasive surface toward the substrate surface; and   an abrasive feature located on the second surface of the flexible foil web, the abrasive feature applying cutting forces to the substrate surface during motion of the abrasive article relative to the substrate surface.   
     
     
         16 . The flexible foil bearing abrasive article of  claim 15  wherein the hydrostatic preloader further comprises pressure contact sensors located at a closed form hydrostatic bed. 
     
     
         17 . The flexible foil bearing abrasive article of  claim 15  wherein the second abrasive surface includes a hydrostatic bearing. 
     
     
         18 . The flexible foil bearing abrasive article of  claim 15  wherein the second abrasive surface comprises a hydrodynamic bearing. 
     
     
         19 . The flexible foil bearing abrasive article of  claim 15  wherein the second abrasive surface includes diamond like carbon. 
     
     
         20 . The flexible foil bearing abrasive article of  claim 15  wherein the second abrasive surface includes alumina. 
     
     
         21 . A flexible foil bearing abrasive article for polishing a substrate surface, the abrasive article comprising:
 a foil hydrodynamic bearing suspended with non straight links between two tensioned tapes;   a mechanism that biases the second surfaces of the abrasive members toward the substrate surface; and   abrasive features located on a surface of the flexible foil nearest the substrate surface, the abrasive features applying cutting forces to the substrate during motion of the abrasive article relative to the substrate.   
     
     
         22 . The flexible foil bearing abrasive article of  claim 21 , the foil hydrodynamic bearing suspended with a gimballing mechanism. 
     
     
         23 . The flexible foil bearing abrasive article of  claim 21 , the foil hydrodynamic bearing suspended with a hydrostatic preloader. 
     
     
         24 . A method of polishing a surface of a substrate, the method comprising:
 biasing a flexible foil web under tension wrapped around a hydrostatic preloader toward the surface of the substrate;   pressurizing an abrasive surface of the flexible foil web to provide a contact pressure for the abrasive surface; and   monitoring the pressure between the substrate and the abrasive with a pressure opening in the hydrostatic preloader.