| abstract |
The present invention provides an infrared spectroscopic method of removing a first layer from a semiconductor wafer without overpolishing the underlying second layer. The first layer and the second layer of the semiconductor wafer is subjected to infrared (IR) spectroscopy and an absorbance curve is produced, whereby each layer absorbs IR light at different wavenumbers to produce different absorbance peaks. Once the CMP process is performed, a change in the IR absorptivity and thus the absorbance peak of each layer is detected. The endpoint of the CMP process is determined at a point when significant change in the IR absorptivity of the first layer is no longer detected and change in the IR absorptivity of the second layer occurs. |