Paper PS-ThM2
Electron-beam Sustained Plasma with Unique Characteristic of Low Electron Temperature at Very Low Pressure

Thursday, October 25, 2018, 8:20 am, Room 104A

Low electron temperature plasmas have recent interest because of their potential applications in atomic layer etching, etch of non-volatile materials and polymer processing. Electron-beam sustained plasmas (ESP) are primarily sustained by an electron beam. In this presentation we describe one kind of ESP system consisting of two plasmas separated by a dielectric injector. The electron-source plasma is generated by an inductively coupled source (ICP), on the boundary walls of which a negative DC voltage is applied. The main plasma is the ESP itself, which is generated by the electron beam extracted from ICP through a dielectric injector by an accelerator located inside the ICP. The electron temperature and electron energy distribution functions (EEDf) are measured by Langmuir Probe. We show the ESP plasma is characterized by a low electron temperature (less than 1eV) at very low pressure (1-10mT) measured. This unique characteristic is unavailable to conventional plasmas, in which pulsing or high pressure is required to obtain low electron temperature. The plasma also illustrates the controllable EEDf especially when superposed on an additional plasma such as a simple ICP source. The electron temperature of the ICP source can be significantly dropped with the addition of an ESP. The presentation includes a discussion regarding the uniformity and scalability of the ESP system. In particular, the generation of a sheet electron beam without the aid of a magnetic field and the impact of externally coupled capacitive power are discussed.