Abrasive article with array of gimballed abrasive members and method of use

Abstract

An abrasive article with an array of independently gimballed abrasive members that are capable of selectively engaging with nanometer-scale and/or micrometer-scale height variations and micrometer-scale and/or millimeter-scale wavelengths of waviness, on the surfaces of substrates. Each abrasive member maintains a fluid bearing (air is the typical fluid) with the substrate. The spacing and pitch of the abrasive members can be adjusted to follow the topography of the substrate to remove a generally uniform layer of material; to engage with the peaks on the substrate to remove target wavelengths of waviness; and/or to remove debris and contamination from the surface of the substrate.

1 . An abrasive article for lapping a surface of a substrate, the abrasive article comprising:
 a gimbal structure including an array of gimbal assemblies;   a plurality of abrasive members each comprising a first surface engaged with one of the gimbal assemblies, and a second surface, the gimbal assemblies permitting each abrasive member to move independently in at least pitch and roll;   a preload mechanism that biases the second surfaces of the abrasive members toward the substrate;   one or more fluid bearing features on the second surfaces of the abrasive members configured to generate lift forces during motion of the abrasive article relative to the substrate; and   abrasive features located at an interface of the second surface of the abrasive members with the substrate, the abrasive features applying cutting forces to the substrate during motion of the abrasive article relative to the substrate.   
     
     
         2 . The abrasive article of  claim 1  wherein the abrasive features comprise one or more of an abrasive material attached to the second surface of the abrasive members, a slurry of free abrasive particles located at the interface of the second surface and the substrate, or a combination thereof. 
     
     
         3 . The abrasive article of  claim 1  wherein the gimbal structure comprises a polymeric film with a plurality of areas of weakness bonded to the abrasive members. 
     
     
         4 . The abrasive article of  claim 1  wherein the plurality of abrasive members comprises an array of abrasive members molded to a backing layer. 
     
     
         5 . The abrasive article of  claim 1  wherein the abrasive members are arranged in a circular array, a rectangular array, an off-set pattern, or a random pattern. 
     
     
         6 . The abrasive article of  claim 1  wherein one or more of the fluid bearing features and the abrasive features comprise abrasive particles disbursed in a binder comprising abrasive composites. 
     
     
         7 . The abrasive article of  claim 1  wherein the lift force maintains the leading edges of the abrasive members further away from the substrate than the trailing edges. 
     
     
         8 . The abrasive article of  claim 1  wherein the lift forces generate moments on the abrasive members that is greater than moments generated by frictional forces at interfaces of the trailing edges with the substrate. 
     
     
         9 . The abrasive member of  claim 1  wherein clearance between the abrasive members and the substrate is maintained between about 25 nanometers to about 100 nanometers. 
     
     
         10 . The abrasive article of  claim 1  wherein the abrasive features comprise a nano-scale roughened surface coated with a hard coat. 
     
     
         11 . The abrasive article of  claim 1  wherein the abrasive features comprise nano-scale diamonds attached to the fluid bearing features at the trailing edges of the abrasive members. 
     
     
         12 . The abrasive article of  claim 1  wherein the abrasive members comprise one of topography following or topography removing abrasive members. 
     
     
         14 . The abrasive article of  claim 1  comprising a plurality of gas conduits adapted to deliver pressurized gas to one or more pressure ports positioned opposite the substrate, the pressurized gas generating a lift force on the abrasive members relative to the substrate. 
     
     
         15 . The abrasive article of  claim 14  wherein the conduits selectively deliver the source of pressurized gas to the abrasive members. 
     
     
         16 . The abrasive system comprising:
 a first abrasive article of  claim 1  positioned opposite a first surface of the substrate;   a second abrasive article of  claim 1  positioned opposite a second surface of the substrate; and   a mechanism positioning the substrate so the first and second abrasive articles can simultaneously lap the first and second surface of the substrate.   
     
     
         17 . A method of lapping a surface of a substrate, the method comprising the steps of:
 biasing an array of individually gimballed abrasive members toward the surface of the substrate;   permitting each gimballed abrasive member to move independently in at least pitch and roll;   creating fluid bearings between each abrasive member and the substrate; and   positioning abrasive features at an interface of the abrasive members and the substrate, the abrasive features applying cutting forces to the substrate during motion of the abrasive article relative to the substrate.   
     
     
         18 . The method of  claim 17  comprising one or more of attaching the abrasive features to the abrasive members, and depositing a slurry of free abrasive particles at the interface of the second surface and the substrate. 
     
     
         19 . The method of  claim 17  comprising
 molding an array of abrasive members to a backing layer; and 
 forming areas of weakness in the backing layer adjacent the abrasive members. 
 
     
     
         20 . The method of  claim 17  comprising maintaining a greater lift force at leading edges of the abrasive members than at trailing edges. 
     
     
         21 . The method of  claim 17  wherein the fluid bearings generate moments on the abrasive members greater than moments generated at the interface of the abrasive members with the substrate. 
     
     
         22 . The method of  claim 17  comprising delivering a pressurized gas to one or more pressure ports positioned opposite the substrate to create a hydrostatic fluid bearing. 
     
     
         23 . The method of  claim 17  comprising moving the array of abrasive members relative to the substrate to create a hydrodynamic fluid bearings. 
     
     
         24 . The method of  claim 17  comprising the steps of:
 delivering a pressurized gas to one or more pressure ports positioned opposite the substrate to create a hydrostatic fluid bearing during a start-up phase; and 
 moving the array of abrasive members relative to the substrate to create a hydrodynamic fluid bearings. 
 
     
     
         25 . The method of  claim 24  comprising reducing or terminating the flow of pressurized gas after the hydrodynamic fluid bearing is formed.