Retrograde Well Implant

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...

High energy implantation typically refers to doses in the 1011—1013 cm"2 at energies up to several MeV. The most common applications for which high energy implanters are used include retrograde and triple well formation, buried layer formation, and field isolation. 

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