Correlation between plasma-induced gate oxide damage and charging sensor measurements

This paper describes for the first time a methodology which allows direct correlation between charging potential, measured under actual process conditions using a flash memory cell as a charging sensor, and “latent” oxide damage revealed through FN injection on transistors. The methodology was used to study charging effects in a transformer-coupled plasma (TCP) metal etcher under actual process conditions, as a function of antenna shape. Significant V_th shifts after FN injection were found only with very dense “finger” antennas, revealing enhanced oxide damage due to the “electron shading” effects. The oxide damage is strictly correlated with charging potential using flash memory cells with the same antenna structures as the transistors