Silicon is electropolished in hydrofluoric acid solutions if a critical current density is exceeded. Below the critical c.d., silicon dissolution is largely divalent, and a thick solid layer forms. This film is unstable and reacts slowly with the electrolyte to form tetravalent silicon and hydrogen gas. In the electro‐polishing region, silicon dissolution is mainly tetravalent with the formation of a very thin high resistance type of film.Experimental results on the effect of HF concentration, viscosity, and temperature indicate that electropolishing begins when the HF concentration at the silicon becomes limited by the rate of “mass transfer” of HF from the solution bulk to the surface.
ing basic fundamental theory, formal methods of analysis of data, and appropriate scheduling of experiments that the professional should be able to use the statistical approach to research or production.The basic theory is presented in the first five chapters. The next four chapters are devoted to the statistical design of an experiment and the analysis of data resulting therefrom. Chapter Ten treats control charts not only from the production aspect but also as an analytical tool for the researcher. The final chapter treats of several techniques for examining admissibility of data.Undoubtedly this volume will become a standard reference book as it is exceedingly well written as to methodology. It is unfortunate that not all the confusing notation has been expunged and that the mathematics is overcumbersome. The chapter on control charts seems to suffer from a failure either to introduce the midrange and median or to discuss chart analysis of data h'om complex experiments. The treatment of tolerance limits, components of NOW! GET 10% TO 15% MORE ANODE MILEAGE WITH... NEW ANACONDA "PLUS-4" ANODES* (PHOSPHORIZED COPPER)Freedom from anode sludge--"J" no "bagging" or diaphragms required.No copper build-up ~"in solution.Exceptionally smooth, "J" heavy cathode deposits.10% to 15% more cathode "J" deposits per pound of anode.It has been discovered that carefully controlled amounts of phosphorus, together with minute amounts of other elements in electrolytic copper, make anodes of vastly superior quality for acid plating. ANACONDA "PLUS-4" Anodes are available in all the standard sizes and forms at no increase in cost over ordinary anodes. Look for the stamp "Pnus-4" on the anodes you buy.We'll be glad to supply additional information, in detail, without obligation. Just write to: The American Brass Company, Waterbury 9.0, Connecticut. ~4~5~ *For use under Patent No. 2,689,216
The electrode potential of germanium or silicon in a chemical etching solution is a function of solution pH, rate of etching, physical condition of the surface, conductivity type, and resistivity. The results suggest that excess holes and electrons are produced at the surface of the semiconductor during chemical etching. Holes are injected at cathode sites, but only a portion of these holes are consumed at anode sites since the anode reaction involves current multiplication.
The mechanism whereby certain organic addition agents modify the crystal growth of copper electrodeposits was studied with the aid of cathode polarization measurements and microscopic examination of the deposit. Thiourea and 1(−) cystine refine grain size and brighten the deposit. The effect is attributed to a degradation of the additive at the cathode surface with the formation of sulfide ions and precipitation of normalCuS . The normal crystal growth habit is modified by the incorporation of copper sulfide into the deposit. Gelatin, a grain refiner and hardener, modifies crystal growth of copper electrodeposits by being adsorbed on growth sites thereby interfering with normal growth. Glycine, a “leveling” agent, affects cathode polarization only between about 0.1 and 1 ma/cm2. Additions of up to 0.1 g/l dextrin have no effect on the cathode polarization curve for copper plating.
The anode characteristics of n-and p-type germanium are different. A large voltage barrier is observed at about 0.8 ma/cm 2 current density at room temperature on n-type but not on p-type electrodes. The voltage barrier on 3 ohm-cm n-type germanium anodes breaks down at about 9 volts in many electrolytes. During anodie dissolution the germanium surface appears to be covered with about a monolayer of oxide or hydroxide. This suggests that germanium goes into solution as a complex ion with the hydroxyl or oxide radicals attached. A mechanism is proposed for the over-Ml anode dissolution process involving two holes and two electrons for each germanium atom dissolving.) unless CC License in place (see abstract). ecsdl.org/site/terms_use address. Redistribution subject to ECS terms of use (see 130.102.42.98
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