Polishing pad with window

Abstract

Polishing pads with a window, systems containing such polishing pads, and processes that use such polishing pads are disclosed. For example, a light beam having a wavelength between about 300 and 500 nm may be directed through a transparent portion of a polishing surface of a polishing pad. The polishing may be for a shallow trench isolation (STI) fabrication process, a spin-on glass fabrication process and a silicon-on-insulator (SOI) fabrication process.

1 . A method of polishing a substrate, comprising: 
 bringing a polishing surface having a transparent portion into contact with a substrate;    causing relative motion between the polishing surface and the substrate;    directing a light beam having a wavelength between about 300 and 500 nm through the transparent portion of the polishing surface; and    detecting reflections of the light beam from the substrate to determine a polishing endpoint.    
     
     
         2 . The method of  claim 1 , wherein the light beam consists essentially of blue light.  
     
     
         3 . The method of  claim 2 , wherein the light beam consists essentially of blue(indigo) light.  
     
     
         4 . The method of  claim 1 , wherein the light beam has a wavelength of about 400 nm.  
     
     
         5 . The method of  claim 4 , wherein the wavelength is between 400 and 415 nm.  
     
     
         6 . The method of  claim 5 , wherein the wavelength is approximately 405 nm.  
     
     
         7 . The method of  claim 1 , wherein the light beam has a wavelength of about 470 nm.  
     
     
         8 . The method of  claim 1 , wherein the substrate includes an active area in which an outermost oxide layer has an incoming thickness of about 1000 to 2000 Angstroms.  
     
     
         9 . The method of  claim 1 , wherein the polishing process is a step in a shallow trench isolation (STI) fabrication process.  
     
     
         10 . The method of  claim 1 , wherein the polishing process is a step in a spin-on glass fabrication process.  
     
     
         11 . The method of  claim 1 , wherein the polishing process is a step in a silicon-on-insulator (SOI) fabrication process.  
     
     
         12 . A method of polishing a substrate in a shallow trench isolation (STI) process, comprising: 
 bringing a polishing surface having a transparent portion into contact with an active area of a substrate, wherein the active area includes an oxide layer disposed on a nitride layer;    causing relative motion between the polishing surface and the substrate;    directing a light beam having a wavelength consisting essentially of 400 to 415 nm through the transparent portion of the polishing surface; and    detecting reflections of the light beam from the substrate to determine a polishing endpoint.    
     
     
         13 . A method of polishing a substrate, comprising: 
 bringing a polishing surface having a transparent portion into contact with a substrate, the substrate needing polishing in one of a shallow trench isolation (STI) fabrication process, a spin-on glass fabrication process and a silicon-on-insulator (SOI) fabrication process;    causing relative motion between the polishing surface and the substrate;    directing a light beam having a wavelength between about 300 and 500 nm through the transparent portion of the polishing surface; and    detecting reflections of the light beam from the substrate to determine a polishing endpoint.    
     
     
         14 . The method of  claim 13 , wherein the polishing process is a step in a shallow trench isolation (STI) fabrication process.  
     
     
         15 . The method of  claim 13 , wherein the polishing process is a step in a spin-on glass fabrication process.  
     
     
         16 . The method of  claim 13 , wherein the polishing process is a step in a silicon-on-insulator (SOI) fabrication process.