BEHAVIOUR OF LOW DOSE ARSENIC IMPLANTS IN SILICON

Le comportement d'ions d'arsenic de 80 keV implantés à température ambiante dans des cristaux de silicium orientés ou non, en dessous de la dose d'amorphisation, a été étudié en mesurant les profils physique et électrique suivant des recuits isochrones. A partir de l'analyse du profil physique, les paramètres de pénétration, [MATH]p, Ɗ[MATH]p, et Rmax pour des ions canalisés le long de l'axe , ont été mesurés. Après un recuit isochrone d'échantillons implantés hors canalisation, un coefficient de diffusion effectif à 900°C pour l'arsenic a été calculé égal à 5 × 10-16 cm2· s-1. Il est montré que pour des ions d'arsenic implantés dans le silicium hors canalisation, la fraction électriquement active, qui est d'environ 0,4 après un recuit de 30 min à 600°C, augmente continuellement jusqu'à ce qu'une activation électrique des ions arsenic de 100 % soit atteinte à environ 900°C. Une tendance similaire est observée pour les implantations en canalisation . Le procédé de recuit semble suivre une réaction cinétique du premier ordre avec une énergie d'activation égale à 0,4-0,5 eV. Il est donné un essai d'interprétation du mécanisme impliqué.The behaviour of 80 keV arsenic ions implanted at room temperature in oriented and disoriented silicon crystals below the amorphization dose, has been studied by measuring the physical profile and the electrical profile following isochronal anneals. From the analysis of the physical profile, the penetration parameters, [MATH]p, Ɗ[MATH]p, and Rmax for ions channeled along axis, have been measured. After isochronal annealing of off-channeling implants, an effective diffusion coefficient at 900 °C for arsenic equal to 5 × 10-16 cm2· s-1 has been calculated. It is shown that for arsenic ions implanted in disoriented silicon, the electrically active fraction, which is about 0.4 after 30 min annealing at 600 °C increases continuously until 100 % electrical activation of the arsenic ions is reached at about 900 °C. Similar trend is observed for channeled implants. The annealing process appears to follow a first order reaction kinetics with an activation energy equal to 0.4-0.5 eV. A tentative interpretation of the mechanism involved is given

Electrochemical oxidation of phenolic compounds using a flow-through electrolyser with porous solid electrodes

Organic compounds such as phenol and cresols may be found in industrial wastewater along with other organics and are difficult to be economically removed down to concentrations below environmentally permissible limits. By circulating a wastewater through an electrolytic reactor with a stack of porous solid anodes and cathodes, it has been demonstrated that it is feasible to electrochemically oxidize phenolic compounds in the presence of other organic molecules. A porous solid DSAtype titanium anode coated with several mixed oxide layers was used as the active material. At low applied current densities, phenol and cresol concentrations were reduced from 5000 ppb to below 20 ppb. The influence of the flow rate and electrodes number was also studied and it was demonstrated that the current density was the main factor to be considered. This work confirms the hypotheses of other authors on the reaction mechanisms involved during the electrochemical oxidation of cresol and phenol.Peer reviewed: YesNRC publication: Ye

An electrochemical approach to total organic carbon control in printed circuit board copper sulfate plating baths Part II: Overfall system

An electrochemical system for oxidative removal of high levels of total organic carbon (TOC) in printed circuit board (PCB) copper sulfate plating baths has been developed. These organic contaminants build-up over the course of pattern plating of PCBs, and at high concentrations they interfere with the quality of the plated copper. The chemistry of the electrochemical oxidation of the plating bath contaminants was qualitatively followed using high performance liquid chromatography (HPLC) and chemical oxygen demand (COD) measurements. A complete treatment system is described and rough calculations are given showing, for a given set of conditions, how the proper choice of electrode material and current density can minimize the system cost.Peer reviewed: YesNRC publication: Ye

Improving iron compact green strength using powder surface modification

Peer reviewed: NoNRC publication: Ye