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.
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.
A compact, floating retarding field energy analyzer for measurement of ion energy distributions impacting an electrode through a radio‐frequency or pulsed bias sheath in a plasma discharge is presented. The analyzer is designed to sit on the electrode surface, in place of the substrate, and wide‐band low pass filters allow it to float at the electrode potential. This avoids the need for modification of the electrode. The capabilities of the analyzer are demonstrated through ion energy distribution and electron energy distribution measurements at the electrode surface in an inductively coupled plasma reactor. For a sinusoidal radio‐frequency driving signal applied to the electrode the analyzer is shown to resolve ions with different mass. When the radio‐frequency power to the plasma pulsed the analyzer is used to resolve the ion energy distributions at different times in the pulse. The high energy tail of the electron energy distribution reaching the electrode surface is also measured. A comparison with a Langmuir probe shows exceptional agreement in the energy region where both devices overlap.
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