Damage Caused by Stored Charge during ECR Plasma Etching

The influence of stored charge caused by changing the plasma parameter can be accurately shown by measuring the leakage current in CMOS-inverter integrated circuits. The leakage current increase is due to nonuniform ion current density distribution and self-bias voltage at the point of ECR plasma discharge turn-off. Positive charge ions are stored by the ion current density difference on a wafer. Moreover, a large voltage across the gate oxide is generated by the self-bias voltage at the point of ECR plasma discharge turn-off, and finally degrades the gate oxide.