System and method of measuring warpage of a workpiece on a noncontact support platform

Abstract

Methods and systems for determination of warpage in a workpiece supported by a non-contact support platform, including a surface with a plurality of pressure ports and a plurality of fluid evacuation ports on the surface, a supply system with a pressure supply connected to the plurality of pressure ports on the surface and configured to supply pressure at a substantially constant level and cause a fluid to flow out of the plurality of pressure ports, so as to support a workpiece by fluid-bearing formed under the workpiece, and at least one flowmeter, coupled to a controller and configured to measure the flowrate at the surface, wherein the workpiece is determined to be warped when the measured flowrate is outside a predefined flowrate range.

1 . A system for determination of warpage in a workpiece supported by a non-contact support platform, the system comprising:
 a surface comprising a plurality of pressure ports and a plurality of fluid evacuation ports on the surface;   a supply system, comprising a pressure supply connected to the plurality of pressure ports on the surface and configured to supply pressure at a substantially constant level and cause a fluid to flow out of the plurality of pressure ports, so as to support a workpiece by fluid-bearing formed under the workpiece; and   at least one flowmeter, coupled to a controller and configured to measure the flowrate at the surface,   wherein the workpiece is determined to be warped when the measured flowrate is outside a predefined flowrate range.   
     
     
         2 . The system of  claim 1 , wherein the supply system further comprises a vacuum source connected to the plurality of evacuation ports to cause flow of the fluid into the plurality of evacuation ports. 
     
     
         3 . The system of  claim 2 , wherein at least one of the pressure ports and the evacuation ports corresponds to a flow restrictor. 
     
     
         4 . The system of  claim 1 , further comprising at least one manometer coupled to the controller and configured to measure pressure at the non-contact support platform. 
     
     
         5 . The system of  claim 1 , wherein the at least one flowmeter is positioned on a line supplying a region of the surface, and wherein the workpiece is determined to be warped in the area supplied by the line which the flowmeter is measuring. 
     
     
         6 . A system for determination of warpage in a workpiece supported by a non-contact support platform, the system comprising:
 a surface comprising a plurality of pressure ports and a plurality of fluid evacuation ports on the surface;   a supply system, comprising a pressure supply connected to the plurality of pressure ports on the surface and configured to maintain a substantially constant flowrate and evacuate a fluid into the plurality of evacuation ports, so as to support a workpiece by fluid-bearing formed under the workpiece; and   at least one manometer, coupled to a controller and configured to measure the pressure at the surface,   wherein the workpiece is determined to be warped when the measured pressure is outside a predefined pressure level.   
     
     
         7 . The system of  claim 6 , wherein the supply system further comprises a vacuum source connected to the plurality of evacuation ports to cause the fluid to flow out of the plurality of evacuation ports. 
     
     
         8 . The system of  claim 7 , wherein at least one of the pressure ports and the evacuation ports corresponds to a flow restrictor. 
     
     
         9 . The system of  claim 6 , further comprising at least one flowmeter coupled to the controller and configured to measure flowrate at the surface. 
     
     
         10 . The system of  claim 6 , wherein the at least one manometer is positioned in at least a portion of the non-contact support platform, and wherein the workpiece is determined to be warped in an area corresponding to the position of the at least one manometer. 
     
     
         11 . A system for determination of warpage in a workpiece supported by a non-contact support platform, the system comprising:
 a surface comprising a plurality of pressure ports and a plurality of fluid evacuation ports on the surface;   a supply system, having known relationship between pressure and flowrate for a flat supported workpiece, the supply system comprising a pressure supply connected to the plurality of pressure ports on the surface and configured to supply pressure and cause a fluid to flow out of the plurality of pressure ports, so as to support a workpiece by fluid-bearing formed under the workpiece; and   at least one flowmeter or at least one manometer, coupled to a controller and configured to measure the flowrate or the pressure in the supply system or at the surface,   wherein the workpiece is determined to be warped when the measured flowrate or pressure is outside a predefined range.   
     
     
         12 . The system of  claim 11 , wherein the at least one manometer is positioned in at least a portion of the non-contact support platform, and wherein the workpiece is determined to be warped in an area corresponding to the position of the at least one manometer. 
     
     
         13 . The system of  claim 11 , wherein the supply system further comprises a vacuum source connected to the plurality of evacuation ports to cause flow of the fluid into the plurality of evacuation ports. 
     
     
         14 . The system of  claim 11 , wherein at least one of the pressure ports and the evacuation ports corresponds to a flow restrictor. 
     
     
         15 . The system of  claim 11 , wherein the at least one flowmeter is positioned on a line supplying a region of the surface, and wherein the workpiece is determined to be warped in the area supplied by the line which the flowmeter is measuring.