Versatile plasma ion source with an internal evaporator

Abstract

A novel construction of an ion source with an evaporator placed inside a plasma chamber is presented. The crucible is heated to high temperatures directly by arc discharge, which makes the ion source suitable for substances with high melting points. The compact ion source enables production of intense ion beams for wide spectrum of solid elements with typical separated beam currents of ∼100–150 μA for Al +, Mn +, As + (which corresponds to emission current densities of 15–25 mA/cm 2) for the extraction voltage of 25 kV. The ion source works for approximately 50–70 h at 100% duty cycle, which enables high ion dose implantation. The typical power consumption of the ion source is 350–400 W. The paper presents detailed experimental data (e.g. dependences of ion currents and anode voltages on discharge and filament currents and magnetic flux densities) for Cr, Fe, Al, As, Mn and In. The discussion is supported by results of Monte Carlo method based numerical simulation of ionisation in the ion source.