In-situ endpoint detection and process monitoring method and apparatus for chemical-mechanical polishing

An in-situ chemical-mechanical polishing process monitor method for monitoring a polishing process during polishing of a workpiece in a polishing machine, the polishing machine having a rotatable polishing table provided with a polishing slurry, said method comprising the steps of:

• a) providing a window embedded within the polishing table, the window traversing a viewing path during polishing and further enabling in-situ viewing of a polishing surface of the workpiece from an underside of the polishing table during polishing as the window traverses a detection region along the viewing path;
• and
• b) providing a means coupled to the window on the underside of the polishing table for measuring a reflectance, the reflectance measurement means providing a reflectance signal representative of an in-situ reflectance, wherein a prescribed change in the in-situ reflectance corresponds to a prescribed condition of the polishing process.

A polishing machine having in-situ polishing process monitor control of a polishing process during polishing of a workpiece on a rotatable polishing table provided with a polishing slurry, said polishing machine comprising:

• a) a window embedded within the polishing table, said window traversing a viewing path during polishing and further enabling in-situ viewing of a polishing surface of the workpiece from an underside of the polishing table during polishing as said window traverses a detection region along the viewing path;
• b) means coupled to said window on the underside of the polishing table for measuring a reflectance, said reflectance measurement means providing a reflectance signal representative of an in-situ reflectance, wherein a prescribed change in the in-situ reflectance corresponds to a prescribed condition of the polishing process.