rf impedance, dc self-bias, and ion sheath (dark space) thicknesses are measured in an O2 discharge for 7–53 Pa pressure and 50–800 W rf power (13.56 MHz). Special attention is paid to corrections for reactor stray impedances. It is concluded that the discharge can be described as a capacitance (the ion sheath) with both a parallel and a series resistance, the series element being the more important one. Good agreement is found between optical and electrical measurements of the ion sheath thickness. Evidence is presented that the dc potential difference between plasma and ground and rf electrode can be estimated with reasonable accuracy from the dc self-bias and the optical dark space thicknesses. Positive ion acceleration in the ion sheath and electron-neutral collisions in the bulk of the plasma glow account for only part of the total rf power transfer. It is suggested that significant dissipation takes place near the glow-sheath boundary, although a quantitative description cannot be given yet.

The influence of fluoride on the spontaneous precipitation of calcium phosphates from moderately supersaturated solutions at pH 8.50 was studied over a wide fluoride concentration range (10_6-1( 3 M). An experimental technique was used which allowed a desired supersaturation to be built up under well-defined conditions. The initial stage of the formation process which preceeds the growth of apatitic crystals is extended at low fluoride concentrations (<10~6 M) and shortened at higher (>10~5 M) fluoride concentrations. Another elongation of the first stage is observed at fluoride concentrations in excess of 5.9 X 10"4 M. Suggestions are made to account for these effects. The crystal-growth stage of the overall formation process may be described satisfactorily by a suitably modified Doerner-Hoskins equation at fluoride concentrations below 2.5 X 10"4 M.

A novel multilevel metallization scheme has been developed that uses tungsten for the primary levels of interconnection. 1-ym-wide 2.0-pm-deep grooves, corresponding to a level of line conductor interconnection, are pattern etched into a planar layer of oxide dielectric. Grooves are filled by isotropically depositing a blanket layer of pure tungsten using low-pressure CVD, followed by etch-back of the tungsten to produce a filled interconnect groove (FIG) conductor structure. Fabricated FIG conductors display an average sheet resistivity of 48 mQ/square, comparable to conventional aluminum conductors. In addition, FIG metallization provides excellent planarity, greatly improved electromigration strength, and facilitates the use of stacked vias.

Retarding field analyzer for ion energy distribution measurements at a radio-frequency biased electrode Rev. Sci. Instrum. 79, 033502 (2008); 10.1063/1.2890100Numerical studies on the transition of tuned substrate self-bias in a radio-frequency inductively coupled plasma Phys. Plasmas 13, 043504 (2006); 10.1063/1.2180687Compact floating ion energy analyzer for measuring energy distributions of ions bombarding radio-frequency biased electrode surfaces Rev.Influence of magnetic field on the selfbias potential on a radio frequencypowered electrode in radio frequency plasma J.