Paper PS1-FrM5
The NEPTUNE Bipolar Source: A New Instrument for Surface Treatment Applications

Friday, November 14, 2014, 9:40 am, Room 305

In this work we present a recently patented and developed source of oppositely charged particles called “Neptune”. The source accelerates simultaneously positive ions and electrons extracted from an ICP discharge. The produced broad beam is quasi-neutral with high directionality of all emitted charged particles, and as a result a dedicated neutralizer is redundant in this system. The source can be operated using any kind of working gas, such as Ar, SF₆, CF₄ etc. The simultaneous ion-electron extraction is realized using the RF self-bias effect in low-pressure plasmas. A double-grid ion optical system is RF-powered ensuring both efficient ion extraction and acceleration, and electron injection. In the extraction system ions are continuously accelerated in the RF sheath between the first (plasma/screen) and second grids, while the electrons are extracted periodically when the sheath collapses. Due to the fact that the extraction system is RF-powered via a capacitor, a DC current cannot flow between the extraction grids, and the total amount of ions and electrons escaping the plasma is the same. The first proof-of-concept of the Neptune source is demonstrated. First results of the beam measurements are reported, particularly in comparison with a traditional 2-grid ion source equipped with an external neutralizer. We show here that the Neptune source can be efficiently used for low-ARDE processes, as well as for other applications where the accelerated flows with high directionality of both kinds of charged species are required. It is demonstrated that the independent control of the ion flux and energy allows achieving bipolar beams generation in wide range of parameters. It is shown that the proposed ion-electron extraction technique reduces charging effects on the substrate. This work was supported by a Marie Curie International Incoming Fellowships within the 7th European Community Framework (NEPTUNE PIIF-GA-2012-326054) and by ANR under grant number ANR-2011-BS09-40.