Lanthanum quantification for optimization of advanced high-k/metal gate stacks using low energy electron x-ray emission spectrometry

The authors report about accurate monitoring of ultralow La doses inserted in advanced high-k/metal gate stacks for threshold voltage tuning purposes. Three characterization techniques are implemented for precise and reproducible lanthanum quantification. Low energy electron x-ray emission spectrometry capabilities are highlighted in terms of sensitivity and accuracy, thanks to a comparison with reference results obtained by Rutherford Backscattering Spectrometry. The capabilities of state-of-the-art Auger nanoprobes for depth profiling in the subnanometer range are also illustrated.