Real-time depth measurement in glow discharge optical emission spectrometry via differential interferometric profiling

We developed an in situ measurement technique implemented on a Glow Discharge Optical Emission Spectrometry (GD-OES) instrument, which provides the depth information during the profiling process. The setup is based on a differential interferometer, and we show that a measurement accuracy better than 5% can be obtained for crater depths ranging from 100 nanometers to several tens of micrometers. This development can be directly applied to non-transparent coatings, and brings significant improvement to the quantification process in GD-OES.