Volume 88, Issue 4, 15 August 2000
Index of content:
- PLASMAS AND ELECTRICAL DISCHARGES (PACS 51-52)
88(2000); http://dx.doi.org/10.1063/1.1305843View Description Hide Description
Under certain discharge conditions, radial cataphoresis causes significant mercury depletion in a low-pressure neon–mercury positive column. This depletion can result in the addition of neon radiation to the emission spectrum of the column. The addition of neon radiation can be used to change the color of fluorescent lamps. In order to investigate the radial cataphoresis process, we performed spatially resolved emission measurements. For the relevant spectral lines of mercury and neon, the emission coefficient is determined, along with the density of the upper state of the corresponding transition. Absorption measurements are performed to check the amount of self-absorption of the spectral lines. We present emission and density profiles for various discharge conditions. The obtained results can be understood using an approximate description of the radial cataphoresis process.
In situ electrical characterization of dielectric thin films directly exposed to plasma vacuum-ultraviolet radiation88(2000); http://dx.doi.org/10.1063/1.1305836View Description Hide Description
In this article we report a method for in situ electrical characterization of dielectric thin films under direct exposure to plasma in an electron-cyclotron-resonance etcher. This method is based on the development of a special test structure that allows for the measurement of the influence of plasma vacuum-ultraviolet (VUV) radiation on the electrical conductivity of thin dielectric layers. Results show that the measured conductivity of layers temporarily increases during exposure to argon and oxygen plasmas, with controlled VUV emission. Based on the measurements made through this method, a model of the VUV-induced conductivity of is developed. These measurements are very important for plasma processing of semiconductor devices, because the temporary increase in the conductivity of these layers upon exposure to processing plasmas can decrease the plasma-induced charging of these dielectric layers depending on the intensity of the plasma VUV emission. This can have an impact on the properties and reliability of processed devices.
88(2000); http://dx.doi.org/10.1063/1.1302993View Description Hide Description
The internal temperature of rhodamine B-dyed dust particles immersed in radio-frequency (rf)plasmas has been measured for various plasma conditions. For this purpose, the dye has been excited with an argon-ion laser and the fluorescent emission of the particles has been recorded with an optical multichannel analyzer system. The temperature has been determined after comparison with calibration curves. In argon, the particle temperature increases with rf power and is independent of pressure. In oxygen, an increase with rf power is observed, too. However, the energy flux towards the particles includes also heating by atom recombination (association) and exothermic combustionreactions. These temperature measurements have been compared with calculations based on the thermal balance, where measurements of gas temperature, electron density, and electron temperature have been used. A good agreement between theory and experiment has been found.
Measurement and control of absolute nitrogen atom density in an electron-beam-excited plasma using vacuum ultraviolet absorption spectroscopy88(2000); http://dx.doi.org/10.1063/1.1305559View Description Hide Description
The absolute nitrogen (N) atom density in an electron-beam-excited plasma (EBEP) operating at an ultralow pressure has been investigated by vacuum ultraviolet absorption spectroscopy, employing a microdischarge hollow-cathode lamp. The measured N atom density was estimated to be around and the dissociation fraction was 4.9% at a pressure of 0.05 Pa, an electron-beam current of 10 A, and an electron-beam acceleration voltage of 120 V. The EBEP potentially enables us to control the electron density and electron energy independently with the electron-beam current and electron-beam acceleration voltages, respectively. It was found that N atom densities increased with increasing electron-beam current and electron acceleration voltage under low-pressure conditions. The EBEP shows great promise as a N atom source operating at an ultralow pressure.
88(2000); http://dx.doi.org/10.1063/1.1303077View Description Hide Description
Here a self-consistent one-dimensional continuum model is presented for a narrow gap plane-parallel dcglow discharge. The governing equations consist of continuity and momentum equations for positive and negative ions and electrons coupled with Poisson’s equation. A singular perturbation method is developed for the analysis of high pressuredcglow discharge. The kinetic processes of the ionization, electron attachment, and ion–ion recombination are included in the model. Explicit results are obtained for the asymptotic limits: where is the Debye radius, is recombination length, and L is the gap length. The discharge gap divides naturally into four layers with multiple space scales: anode fall region, positive column, transitional region, cathode fall region and diffusion layer adjacent to the cathode surface, its formation is discussed. The effects of the gas pressure, gap spacing and dc voltage on the electrical properties of the layers and its dimension are investigated.