New HF Linear Ion Source For Industrial Applications

Abstract

Development of ion beam technologies such as ion assisted deposition of thin films, surface modification of materials, and especially utilization of these technologies in industry, require the development of the new generation of the ion sources, which can provide large size ion beams of inert and chemically reactive gases with current density in the range 0.05 1.5 mA/cm2 . In order to provide industry by devices with mentioned parameters the new HF linear ion source (HF LIS) with the size of the extracted ion beam 5x30cm2 was developed. HF LIS consists of gas discharge chamber where the ionization of working gas takes place and ion optic system that utilizes the principle of electrostatic acceleration for ion extraction. The ion beam in HF LIS is extracted from plasma of HF discharge ignited and sustained in HF LIS gas discharge chamber. To ignite and sustain a discharge the HF power is supplied from a high-frequency generator via a matching device to the antenna ends positioned on the extemal surface of gas discharge chamber. To avoid HF power losses the walls of a gas-discharge chamber are made of dielectric (glass, quartz, glass ceramic). To increase the efficiency of highfrequency power input in plasma the gas discharge chamber is placed in a static extemal magnetic field which induction value is chosen from the condition of electrostatic volume plasma waves excitation. The magnetic field shape is taken from the best electron confinement condition. Ion extraction and ion beam formation runs by means of an electrostatic ion optic system consisting of the emitting, accelerating and decelerating electrodes. The emitting electrode is a partially ion-transparent wall under positive potential with respect to the ground. The accelerating electrode is also partially transparent for ions and is under negative potential with respect to the ground. The decelerating electrode is grounded. Tests of the new HF LIS showed reliable operation of the ion source while using inert or reactive working gases as well as high uniformity of the extracted ion beam.