Finding substrate notch on substrate in a chemical mechanical polishing system

Abstract

A polishing apparatus has a polishing station, a notch finding station, and a substrate handling system to move a substrate therebetween. The notch finding station includes a housing having an internal volume that provides forms a reservoir with a floor, a ceiling, and first sidewalls that extend from the floor to the ceiling. An aperture extends through the ceiling of the reservoir and a side-passage extends laterally from a region of the reservoir below the aperture to an entry port such that a liquid injected through the entry port flows emerges from the aperture to form a liquid column. An optical fiber extends through a floor of the reservoir and is positioned to direct a light beam through the aperture and through the liquid column onto a substrate when held at the notch finding station and to receive reflections of the light beam from the substrate.

What is claimed is: 
     
         1 . A polishing apparatus, comprising:
 a polishing station;   a notch finding station; and   a substrate handling system to move a substrate between the polishing station and the notch finding station and including a carrier hold a substrate at the notch finding station;   wherein the notch finding station includes
 a housing having an internal volume that provides forms a reservoir with a floor, a ceiling, and first sidewalls that extend from the floor to the ceiling, wherein an aperture extends through the ceiling of the reservoir and a side-passage extends laterally from a region of the reservoir below the aperture to an entry port such that a liquid injected through the entry port flows through the side-passage into the region below the aperture and forms a liquid column that emerges from the reservoir through the aperture, and 
 an optical fiber extending through a floor of the reservoir and positioned to direct a light beam through the aperture and through the liquid column onto the substrate when held by the carrier at the notch finding station and to receive reflections of the light beam from the substrate. 
   
     
     
         2 . The apparatus of  claim 1 , comprising a baffle in the side-passage to disrupt flow of the liquid. 
     
     
         3 . The apparatus of  claim 2 , wherein the baffle extends from a ceiling of the side passage. 
     
     
         4 . The apparatus of  claim 2 , wherein the baffle is oriented perpendicular to a longitudinal axis of the side passage. 
     
     
         5 . The apparatus of  claim 1 , wherein the side passage narrows from the cavity toward the entry port. 
     
     
         6 . The apparatus of  claim 1 , wherein the entry port is in a floor of the side-passage. 
     
     
         7 . The apparatus of  claim 6 , comprising a pipe coupled to the entry port. 
     
     
         8 . The apparatus of  claim 7 , wherein a centerline of the pipe is laterally offset from a center of the entry port. 
     
     
         9 . The apparatus of  claim 1 , comprising a second cylindrical sidewall extending upwardly from the aperture in the ceiling of the reservoir. 
     
     
         10 . The apparatus of  claim 9 , wherein the second cylindrical sidewall has a lower portion and an upper portion having an upper edge that is thinner than the lower portion. 
     
     
         11 . A polishing apparatus, comprising:
 a polishing station;   a notch finding station; and   a substrate handling system to move a substrate between the polishing station and the notch finding station and including a carrier hold a substrate at the notch finding station;   wherein the notch finding station includes
 a housing having an internal volume that provides forms a reservoir with a floor, a ceiling, and first sidewalls that extend from the floor to the ceiling, wherein an aperture extends through the ceiling of the reservoir such that a liquid injected into the reservoir flows forms a liquid column that emerges from the reservoir through the aperture, a cylindrical inner second sidewall that projects upwardly from the floor of the reservoir, and 
 an optical fiber extending through the floor of the reservoir, wherein the cylindrical inner second sidewall surrounds the optical fiber, and wherein the optical fiber is positioned to direct a light beam through the aperture and through the liquid column onto the substrate when held by the carrier at the notch finding station and to receive reflections of the light beam from the substrate. 
   
     
     
         12 . The apparatus of  claim 11 , wherein the aperture is coaxial with the optical fiber. 
     
     
         13 . The apparatus of  claim 11 , wherein the cylindrical inner second sidewall is coaxial with the optical fiber. 
     
     
         14 . The apparatus of  claim 11 , wherein an inner surface of the cylindrical inner second sidewall is separated from the optical fiber by an annular gap. 
     
     
         15 . The apparatus of  claim 11 , comprising a cylindrical third sidewall extending upwardly from the aperture in the ceiling of the reservoir. 
     
     
         16 . The apparatus of  claim 15 , wherein the cylindrical third sidewall is coaxial with the optical fiber. 
     
     
         17 . The apparatus of  claim 15 , wherein the cylindrical third sidewall is coaxial with the cylindrical inner second sidewall. 
     
     
         18 . The apparatus of  claim 17 , wherein the cylindrical third sidewall has a lower portion and an upper portion having an upper edge that is thinner than the lower portion. 
     
     
         19 . The apparatus of  claim 11 , comprising a window secured to an upper edge of the cylindrical inner second sidewall and extending over an end of the optical fiber. 
     
     
         20 . The apparatus of  claim 19 , further comprising a lens positioned on an end of the optical fiber below the window.