Plasma Uniformity Control via DC Anode Spots in Ion Beam Etching System with Inductively Coupled Plasma Source

In ion beam etching systems that generate ribbon ion beams through elongated slit apertures, plasma density tends to decrease near the slit ends, potentially leading to non-uniform beam profiles. To address this, we installed a pair of tungsten electrodes at both edges of the extraction aperture and applied DC voltage to create two localized anode spots. These anode spots enhanced plasma density in regions where the main inductively coupled plasma was deficient, resulting in improved plasma uniformity near the extraction zone. Two-dimensional optical emission spectroscopy tomography confirmed increased local emission intensity and improved density flatness across a range of pressure conditions. This method offers a compact and energy-efficient approach to plasma shaping and is expected to contribute to better beam uniformity in future ion beam etching operations.