Volume 87, Issue 11, 01 June 2000
Index of content:
- PLASMAS AND ELECTRICAL DISCHARGES (PACS 51-52)
87(2000); http://dx.doi.org/10.1063/1.373435View Description Hide Description
Ion energy distribution (IED) is one of the primary factors governing the etching or depositioncharacteristics in plasma-aided microelectronicsmanufacturing processes. This article explores the influence of rf bias voltage waveform and frequency on the IED. It is demonstrated that the sheath voltage above the wafer is reasonably similar to the rf voltage on the biased substrate. Since the IED correlates well with the sheath voltage if the ion transit time through the sheath is smaller than the rf time period, the IED can be controlled by means of the rf bias voltage. The voltage waveform controls the shape of the distribution while the frequency determines its width. The sinusoidal waveform leads to a distribution that peaks at high energies and gradually decreases with decreasing energy. Square wave results in a sharp step in the IED at high energies, the width of which can be controlled by means of the blocking capacitance. The triangular waveform generates a constant IED over a considerable range of energy. It is also demonstrated that, by utilizing the correlation between the IED and applied voltage waveform, one can design voltage waveforms that produce distributions with specific features.
Populations of excited atomic states along argon surface-wave plasma columns at low and intermediate pressures87(2000); http://dx.doi.org/10.1063/1.373436View Description Hide Description
The axial distributions of the electrons and and excited atoms in argon plasma columns sustained by traveling electromagnetic waves have been studied both experimentally and theoretically in the gas pressure range of 0.2–2.8 Torr. Various diagnostic methods (surface-wave interferometry, emission and absorption spectroscopy) have been used in data gathering. The theoretical model includes a self-consistent solution to the electronBoltzmann equation,electronenergy balanceequation, a set of balance equations for excited atoms and charged particles, the gas thermal balance equation, the wave dispersion relation, and the waveenergy balanceequation. The agreement between experimental data and theoretical results is very good.
87(2000); http://dx.doi.org/10.1063/1.373437View Description Hide Description
Electron and negative ion densities have been measured in inductively coupled discharges containing and Line integrated electron density was determined using a microwave interferometer, negative ion densities were inferred using laser photodetachmentspectroscopy, and electron temperature was determined using a Langmuir probe. For the range of induction powers, pressures and bias power investigated, the electron density peaked at (line-integrated) or approximately The negative ion density peaked at approximately A maximum in the negative ion density as a function of induction coil power was observed. The maximum is attributed to a power dependent change in the density of one or more of the potential negative ion precursor species since the electron temperature did not depend strongly on power. The variation of photodetachment with laser wavelength indicated that the dominant negative ion was Measurement of the decay of the negative ion density in the afterglow of a pulse modulated discharge was used to determine the ion–ion recombination rate for and discharges.