COCOS (Corona Oxide Characterization of Semiconductor) Non-Contact Metrology for Gate Dielectrics

COCOS metrology enables gate dielectrics to be quickly monitored in a non-contact manner for all wafer sizes including 300mm. This approach has been developed during the last five years and is already implemented in many microelectronic fablines. The method uses corona charging in air to deposit an electric charge on a dielectric thus changing the electric field in the dielectric and in the semiconductor. The response is measured in a non-contact manner by using a contact potential difference, VCPD, in the dark and under strong illumination.