Optical coupler hub for chemical-mechanical-planarization polishing pads with an integrated optical waveguide.

Abstract

An apparatus is disclosed which improves the optical monitoring of semi-conductor wafers undergoing chemical mechanical planarization (CMP). The apparatus consists of a hub containing printed circuit board mounted optical and electronic devices, which couple light into a waveguide integrated into a CMP polishing pad. The hub is attached to the CMP polishing pad and rotates with the pad during the CMP operation. The electronics sense light emitting from the waveguide, convert the light into an electrical signal, amplify and analyze the electrical signal, and communicate the result of the analysis to remote CMP tool control systems.

An article of manufacture comprising:  
     
       An optical coupling hub, which is free to rotate about an axis extending through the center of rotation the entrance pupil of a waveguide integrated into a CMP polishing pad.  
     
     
         1 . The article of  claim 1  wherein said optical coupling hub contains an opto-electronic device placed in close proximity (approximately 10 mm) to the entrance pupil of said waveguide to couple light into said waveguide, and also to convert light emitting from said waveguide into an electrical signal.  
     
     
         2 . The article of  claim 1  wherein said optical coupling hub contains additional printed circuit board mounted electronics to perform amplification, digital signal processing, and communication of said electrical signal.  
     
     
         3 . The article of  claim 1  wherein said optical coupling hub contains a bearing to allow the hub to rotate about an axis extending through the center of the waveguide entrance pupil.