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[en] Laser induced fluorescence has been used to measure the spatial distribution of the two lowest energy argon excited states, 1s₅ and 1s₄, in inductively driven plasmas containing argon, chlorine and boron trichloride. The behavior of the two energy levels with plasma conditions was significantly different, probably because the 1s₅ level is metastable and the 1s₄ level is radiatively coupled to the ground state but is radiation trapped. The argon data is compared with a global model to identify the relative importance of processes such as electron collisional mixing and radiation trapping. The trends in the data suggest that both processes play a major role in determining the excited state density. At lower rfpower and pressure, excited state spatial distributions in pure argon were peaked in the center of the discharge, with an approximately Gaussian profile. However, for the highest rfpowers and pressures investigated, the spatial distributions tended to flatten in the center of the discharge while the density at the edge of the discharge was unaffected. The spatially resolved excited state density measurements were combined with previous line integrated measurements in the same discharge geometry to derive spatially resolved, absolute densities of the 1s₅ and 1s₄ argon excited states and gas temperature spatial distributions. Fluorescence lifetime was a strong fi.mction of the rf power, pressure, argon fraction and spatial location. Increasing the power or pressure resulted in a factor of two decrease in the fluorescence lifetime while adding Cl₂ or BCl₃ increased the fluorescence lifetime. Excited state quenching rates are derived from the data. When Cl₂ or BCl₃ was added to the plasma, the maximum argon metastable density depended on the gas and ratio. When chlorine was added to the argon plasma, the spatial density profiles were independent of chlorine fraction. While it is energetically possible for argon excited states to dissociate some of the molecular species present in this discharge, it does not appear to be a significant source of dissociation. The major source of interaction between the argon and the molecular species BCl₃ and Cl₂ appears to be through modification of the electron density

[en] Electron and negative ion densities have been measured in inductively coupled discharges containing C₂F₆ and CHF₃. Line integrated electron density was determined using a microwave interferometer, negative ion densities were inferred using laser photodetachment spectroscopy, 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 9 x 10¹² cm^-2 (line-integrated) or approximately 9 x 10¹¹ cm^-3. The negative ion density peaked at approximately 1.3 x 10¹¹ cm^-3. 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 F^-. 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 CF₄, C₂F₆ and CHF₃ discharges

[en] This report documents measurements in inductively driven plasmas containing SF(sub 6)/Argon gas mixtures. The data in this report is presented in a series of appendices with a minimum of interpretation. During the course of this work we investigated: the electron and negative ion density using microwave interferometry and laser photodetachment; the optical emission; plasma species using mass spectrometry, and the ion energy distributions at the surface of the rf biased electrode in several configurations. The goal of this work was to assemble a consistent set of data to understand the important chemical mechanisms in SF(sub 6) based processing of materials and to validate models of the gas and surface processes

[en] In October 1996, an interdisciplinary team began a three-year LDRD project to study the plasma processes of reactive ion etching and plasma-enhanced chemical vapor deposition on large-area silicon devices. The goal was to develop numerical models that could be used in a variety of applications for surface cleaning, selective etching, and thin-film deposition. Silicon solar cells were chosen as the experimental vehicle for this project because an innovative device design was identified that would benefit from immediate performance improvement using a combination of plasma etching and deposition processes. This report presents a summary of the technical accomplishments and conclusions of the team

[en] Argon plasma characteristics in a dual-frequency, capacitively coupled, 300 mm-wafer plasma processing system were investigated for rf drive frequencies between 10 and 190 MHz. We report spatial and frequency dependent changes in plasma parameters such as line-integrated electron density, ion saturation current, optical emission and argon metastable density. For the conditions investigated, the line-integrated electron density was a nonlinear function of drive frequency at constant rf power. In addition, the spatial distribution of the positive ions changed from uniform to peaked in the centre as the frequency was increased. Spatially resolved optical emission increased with frequency and the relative optical emission at several spectral lines depended on frequency. Argon metastable density and spatial distribution were not a strong function of drive frequency. Metastable temperature was approximately 400 K

[en] There is much interest in scaling rf-excited capacitively coupled plasma reactors to larger sizes and to higher frequencies. As the size approaches operating wavelength, concerns arise about non-uniformity across the work piece, particularly in light of the well-documented slow-surface-wave phenomenon. We present measurements and calculations of spatial and frequency dependence of rf magnetic fields inside argon plasma in an industrially relevant, 300 mm plasma-processing chamber. The results show distinct differences in the spatial distributions and harmonic content of rf fields in the plasma at the three frequencies studied (13.56, 60 and 176 MHz). Evidence of a slow-wave structure was not apparent. The results suggest that interaction between the plasma and the rf excitation circuit may strongly influence the structures of these magnetic fields and that this interaction is frequency dependent. At the higher frequencies, wave propagation becomes extremely complex; it is controlled by the strong electrical nonlinearity of the sheath and is not explained simply by previous models