A retarding field energy analyzer designed to measure ion energy distributions impacting a radio-frequency biased electrode in a plasma discharge is examined. The analyzer is compact so that the need for differential pumping is avoided. The analyzer is designed to sit on the electrode surface, in place of the substrate, and the signal cables are fed out through the reactor side port. This prevents the need for modifications to the rf electrode--as is normally the case for analyzers built into such electrodes. The capabilities of the analyzer are demonstrated through experiments with various electrode bias conditions in an inductively coupled plasma reactor. The electrode is initially grounded and the measured distributions are validated with the Langmuir probe measurements of the plasma potential. Ion energy distributions are then given for various rf bias voltage levels, discharge pressures, rf bias frequencies--500 kHz to 30 MHz, and rf bias waveforms--sinusoidal, square, and dual frequency.

A retarding field energy analyzer is used to characterize an asymmetric, 13.56 MHz driven, capacitively coupled, parallel plate discharge operated at low pressure. The characterization is carried out in argon discharges at 10 and 20 mTorr where the sheaths are assumed to be collisionless. The analyzer is set in the powered electrode where the impacting ion and electron energy distributions are measured for a range of discharge powers. A circuit model of the discharge is used to infer important electrical parameters from the measured energy distributions, including electrode excitation voltages, plasma potential and sheath potentials. Analytical models of the ion energy distribution in a radio-frequency sheath are used to determine plasma parameters such as sheath width, ion transit time, electron temperature and ion flux. A radio-frequency compensated Langmuir probe is used for comparison with the retarding field analyzer measurements.

A comparison is made between plasma parameters measured with a retarding field energy analyzer (RFEA), mounted at a grounded electrode in an inductive discharge, and a Langmuir probe located in bulk plasma close to the analyzer. Good agreement between measured plasma parameters is obtained for argon gas pressure in the range 2-10 mTorr. Parameters compared include time averaged plasma potential, the tail of the electron energy distribution function (EEDF), the electron temperature and the ion flux. This highlights the versatility of the RFEA for determining plasma parameters adjacent to the surface where probe measurements are not easily made. Combination of the probe and energy analyzer has enabled the measurement of the EEDF to a higher energy than otherwise possible.

Ion energy distributions are investigated in an inductively coupled radio-frequency discharge at low pressures. A Langmuir probe is used to characterize the discharge and a retarding field energy analyzer measures the ion flux and energy distributions impacting a remote rf driven electrode. Comparisons are made between capacitive and direct coupling of the rf bias potential. The effects of ICP power, rf bias voltage (0-75 V amplitude), bias frequency (0.5-20 MHz) and discharge pressure (0.2-1.2 Pa) are presented. Results are shown for Ar, O 2 and Ar-He discharges. A double layer was observed during source characterization measurements in an O 2 discharge; however, the focus of this paper is on the behavior of ions through capacitively and directly coupled plasma sheaths.

A commercial retarding field analyzer is used to measure the time-averaged ion energy distributions of impacting ions at the powered electrode in a 13.56 MHz driven, capacitively coupled, parallel plate discharge operated at low pressure. The study is carried out in argon discharges at 10 mTorr where the sheaths are assumed to be collisionless. The analyzer is mounted flush with the powered electrode surface where the impacting ion and electron energy distributions are measured for a range of discharge powers. A circuit model of the discharge, in combination with analytical solutions for the ion energy distribution in radio-frequency sheaths, is used to calculate other important plasma parameters from the measured energy distributions. Radio-frequency compensated Langmuir probe measurements provide a comparison with the retarding field analyzer data. The time-resolved capability of the retarding field analyzer is also demonstrated in a separate pulsed dc magnetron reactor. The analyzer is mounted on the floating substrate holder and ion energy distributions of the impinging ions on a growing film, with 100 ns time resolution, are measured through a pulse period of applied magnetron power, which are crucial for the control of the microstructure and properties of the deposited films.