Volume 92, Issue 6, 15 September 2002
Index of content:
- PLASMAS AND ELECTRICAL DISCHARGES (PACS 51-52)
Insulator surface charging and dissipation during plasma immersion ion implantation using a thin conductive surface film92(2002); http://dx.doi.org/10.1063/1.1503149View Description Hide Description
Plasma immersion ion implantation of insulating materials is inherently problematic due to charge accumulation on the insulator surface.Surface charge can be removed by the application of an ultrathin conductivefilm, which is essentially transparent to the incident ions. The minimum thickness of the film is determined by its capability to effectively conduct away the implanted charge. We present a model for charge accumulation on insulators during plasma immersion ion implantation and use this to study the plasma sheath width and voltage, with and without an ultrathin metal film. Charge accumulation occurs more quickly when the plasma has a directed velocity greater than the Bohm velocity, which is the case for a cathodic arc plasma. We show that for both cases the effectiveness of plasma immersion ion implantation is improved with the application of an ultrathin conductivefilm.
Measured energy distributions of ions driven by an asymmetrically pulsed bias during magnetron sputtering92(2002); http://dx.doi.org/10.1063/1.1501739View Description Hide Description
A retarding field analyzer is used to obtain a measure of the energy of the ions extracted from a direct current discharge driven by a low-frequency (100–100 kHz) asymmetrically pulsed bias. Measurements are made to illustrate the effects of the pulse’s shape (frequency and duty) on the distribution in the energies of the ions extracted from the plasma. Ion energy distributions are computed by a quasistatic treatment of the ion’s response to the measuredwave form of the pulsed electrode. Comparisons are made between the measured and calculated ion energy distributions to demonstrate the effectiveness of the technique used to calculate the ion energy distribution. Expressions are then produced for the time scales in which the quasistatic treatment of the sheath remains a valid approximation to predict the energy distribution of the ions.
Estimation of dissociation degree of in an inductively coupled plasma by vacuum ultraviolet emission spectroscopy92(2002); http://dx.doi.org/10.1063/1.1501741View Description Hide Description
A simple procedure for estimation of the dissociation degrees in low-pressure, high-density plasmas is proposed. This procedure is applied to the estimation of the dissociation in an inductively coupled plasma and confirmed to give dissociation degrees similar to those reported previously. The rf power and pressure dependence of the dissociation degree is also presented. The contribution of stepwise excitation out of metastables to the second positive emission is found to be negligible from the net excitation rate computed using an assumed cross section of the electron-impact excitation from to the state and the number density deduced from a simple kinetic model. The recombination of N atoms on the inner surfaces of the plasma reactor used in this study is discussed briefly. Finally, the advantages of the dissociation estimation by vacuum ultraviolet optical emission spectroscopy are mentioned.