In‐line 90 nm Technology Gate Oxide Nitrogen Monitoring With Non‐Contact Electrical Technique

The continuous race to reduce the dimensions of IC components has lead to the introduction of Nitrogen in the thin gate oxide layer in order to increase the dielectric constant and to improve the gate dielectric properties. It is mandatory to apply in‐line monitoring to control the amount of Nitrogen to ensure that electrical behavior is correct over time. Historically, this monitoring was performed by measuring the delay to reoxidation (D2R) with an ellipsometer. But, this method is not suitable in production as it is depending on both initial oxidation and reoxidation reproducibility, which implies implementing dedicated Statistical Process Control (SPC) monitoring at these two specific processing steps. We are here presenting an alternative method to D2R for 90 nm Technology gate oxide grown by Rapid Thermal Process (RTP). Applying a non‐contact Metrology technique, which couples Kelvin probe surface voltage measurement with surface Corona deposition, directly after the nitridation step, the interface ...