Titanium-related emission signals for endpoint detection during via etch process

In this paper, we report the use of titanium-related emission signals, typically Ti 399.9 nm, as an alternative for endpoint detection in the via etch process. These signals give a characteristic peak-like structure in the intensity vs. time (I-T) plot. The cross-sectional profiles of samples etch-stopped at different points on the I-T plot have been verified using secondary electron microscopy (SEM). The proposed endpoint method also gives promising results for samples with device topography and smaller percentage exposed area.