Inline refractive index measurements have established themselves as the technique of choice for detecting faults in the CMP slurry blending and dispense systems of leading fabs. Refractive index, a continuous, non-sampling measurement, helps fabs identify slurry composition changes quickly.

Once calibrated to a specific slurry’s temperature/refractive index characteristics, refractive index measurements can determine the concentration of hydrogen peroxide in slurry with a precision to within ±0.02% by weight, for both copper and tungsten slurries. In long-term
studies at this leading edge fab, measurements for low node technology CMP processes detected slurry compositions reliably for three years, with no instrument maintenance beyond routine flushing of the slurry blender tank. 

Download the complete white paper In-line Refractive Index Monitoring for CMP Slurry Fault Detection (PDF).