Retrograde wells

Ion Implantation- these plasma machines are used to form the various parts of the coupled transistors at voltages of 5 kV to 2 MV. These include retrograde well formation, gates, drains and sources. 

Fig. 14.6. Application of ion implantations in advanced CMOS structure at several stages of the process, (a) Ion implants for retrograde well formation, punch-through-stop, and threshold voltage adjust (b) shallow source/drain (S/D) implant and (c) halo implant...

Fig. 14.8. Schematic dopant distributions in a conventional well formed by the drive-in diffusion and in a retrograde well formed by high energy implantation...

Condensable Hquids also are recovered from high pressure gas reservoirs by retrograde condensation. In this process, the high pressure fluid from the reservoir produces a Hquid phase on isothermal expansion. As the pressure decreases isotherm ally the quantity of the Hquid phase increases to a maximum and then decreases to disappearance. In the production of natural gas Hquids from these high pressure wells, the well fluids are expanded to produce the optimum amount of Hquid. The Hquid phase then is separated from the gas for further processing. The gas phase is used as a raw material for one of the other recovery processes, as fuel, or is recompressed and returned to the formation. 

The product is a P-hydroxy aldehyde (called an aldol) or ketone, which in some cases is dehydrated during the course of the reaction. Even if the dehydration is not spontaneous, it can usually be done easily, since the new double bond is in conjugation with the C=0 bond so that this is a method of preparing a,P-unsaturated aldehydes and ketones as well as P-hydroxy aldehydes and ketones. The entire reaction is an equilibrium (including the dehydration step), and a,P-unsaturated and P-hydroxy aldehydes and ketones can be cleaved by treatment with OH (the retrograde aldol reaction). There is evidence that an SET mechanism can intervene when the substrate is an aromatic ketone. ... 

Diffusion Retrograde Gates Isolation Barriers Wells... 

For this purpose, as well as for many other food uses, the vegetable gums, as a group, are often preferred to the starches, especially those of the cereal variety, because they do not tend to retrograde at low temperatures, as do these starches. Consequently, with the increasing popularity of frozen food products, the water-soluble gums are in greater demand. 

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