| abstract |
Laser induced fluorescence is utilized to detect and control the reactive ion etch-through of a given layer in a wafer by detecting a large change in the concentration of a selected minor species from the wafer in the etching plasma. This selected minor species must be present in a significantly different concentration in the etched given layer compared to adjacent layers in the wafer in order to provide a proper endpoint detection. In one embodiment, when the large change in the selected minor species concentration is detected, then the RF electrodes for the reactor are automatically de-energized. |