Compact floating ion energy analyzer for measuring energy distributions ofions bombarding radio-frequency biased electrode surfaces

A compact floating retarding-field ion energy analyzer and the accompanying electronics have been designed and built to measure the energy distributio n of ions bombarding radio-frequency (rf) biased electrodes in high-density plasma reactors. The design consists of two main components, a compact ret arding field vacuum probe and an integrated stack of floating electronics f or providing output voltages, measuring currents and voltages and transmitt ing data to a computer. The operation and capabilities of the energy analyz er are demonstrated through ion energy distribution measurements conducted on a 4 MHz rf-biased electrostatic chuck in a 13.56 MHz high-density transf ormer coupled plasma (TCP) reactor. The analyzer is capable of operating wh ile floating on several hundreds of volts of rf bias and at pressures up to 30 mTorr without differential pumping. The effects of pressure (2-30 mTorr ), TCP power (500-1500 W), rf-bias power (0-800 W), gas composition, and io n mass on the ion energy distributions are demonstrated through Ar, Ne, and Ar/Ne discharges. (C) 1999 American Institute of Physics. [S0034-6748(99)0 3206-2].