Etch tailoring through flexible end-point detection

Accurate measurement, in-situ and in real-time, of film thickness during Reactive Ion Etching (RIE) can lead to new levels of process control. The two techniques described are used to stop an etch close to an interface, less than 50nm, and have an accuracy of 3nm and 8nm respectively. The long term goal, etch tailoring, depends on pin-pointing in real-time the film remaining to be etched. With etch tailoring process parameters can be changed to improve product quality.